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Marine  Biological  Laboratory  Library 

Woods  Hole,  Mass. 


Presented  by 

The  Combined  Book  Exhibit,  Inc. 
August,  1963 


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PROTOZOAN  PARASITES 

OF 

DOMESTIC  ANIMALS 

AND 
OF  MAN 


PROTOZOAN  PARASITES 

OF 


DOMESTIC  ANIMALS 
AND 

OF  MAN 


by 


NORMAN  D.  LEVINE.  Ph.D. 

Professor  of  Parasitology 

College  of  Veterinary  Medicine 

University  of  Illinois,  Urbana,  Illinois 


^*  "^ 


w 


BURGESS  PUBUSHING  COMPANY 

426  South  Sixth  Street  —  Minneapolis  15,  Minnesota 


Copyright  ©   1961 

by 
Norman  D.  Levine 


All  Rights  Reserved 
Library  of  Congress  Catalog  Card  No.  61  9214 


No  part  of  this  book  may  be  reproduced  in  any  form 
without  permission  in  writing  from  the  publishers. 


Printed  in  the  United  States  of  America 


DEDICATED   TO  MY  PARENTS: 

To  Max  Levine,  whose  example  guided  me  to  a 

career  in  science 
To  Adele  Levine,   whose  example  helped  me  to 

an  interest  in  the  humanities 


Preface 


The  importance  of  protozoan  parasites  as  causes  of  disease  in  domestic  animals  is 
well  recognized,  yet  the  literature  on  them  is  still  widely  scattered  and  the  books  now 
available  provide  little  more  than  an  introduction  to  the  subject.     The  present  book  was 
written  to  serve  as  a  text  and  reference  work  for  veterinarians,   protozoologists,   para- 
sitologists,  zoologists  and  also  for  physicians.    As  our  knowledge  of  the  relations  be- 
tween human  and  animal  parasites  has  increased,  the  list  has  also  increased  of  parasites 
which  were  once  thought  to  be  confined  to  domestic  and  wild  animals  but  which  are  now 
known  to  occur  also  in  man.     The  area  of  overlap  between  the  fields  of  human  and  animal 
disease  is  becoming  continually  greater,  and  the  zoonoses  are  receiving  more  and  more 
attention.     For  this  reason,  the  protozoan  parasites  of  man  are  included  in  this  book, 
and  their  relations  to  those  of  lower  animals  are  indicated. 

When  this  book  was  begun,  it  was  intended  to  be  a  revision  of  the  pioneering 
Veterinary  Protozoology  by  the  late  Banner  Bill  Morgan  and  the  late  Philip  A.   Hawkins, 
the  second  edition  of  which  was  published  in  1952.     However,  it  soon  became  apparent 
that  far  more  than  this  was  necessary,  and  the  result  has  been  an  entirely  new  book. 

It  is  planned  to  follow  this  volume  with  others  on  veterinary  helminthology  and  en- 
tomology.    The  first  chapter,  therefore,  deals  with  the  general  principles  of  parasitology, 
while  the  second  is  an  introduction  to  protozoology.     The  different  groups  of  protozoa  are 
discussed  in  the  succeeding  chapters,  and  the  final  chapter  deals  with  laboratory  diag- 
nostic technics.     This  systematic  organization  based  on  parasite  groups  is  used  rather 
than  one  based  on  host  animals  because  it  is  more  efficient,  avoids  repetition,  and  makes 
the  subject  easier  to  present  and  to  understand.     However,  it  is  also  useful  to  know  which 
parasites  one  can  expect  to  find  in  each  host.     Lists  of  parasites  by  host  have  therefore 
been  prepared  and  are  incorporated  in  the  index.     E.  A.   Benbrook  (1958.    Outline  of 
parasites  reported  for  domesticated  animals  in  North  America.     5th  ed.    Iowa  State  Univ. 
Press)  has  listed  the  parasites  both  by  host  and  by  location  in  the  host. 

The  world  today  is  too  small  to  permit  a  provincial  approach  to  parasitism  and 
disease.    Katanga  and  Uttar  Pradesh,  Kazakhstan  and  Luzon  are  only  a  step  from  New 
York  and  San  Francisco,  and  their  problems  and  their  diseases  are  becoming  more  and 
more  our  concern.     The  scope  of  this  book,  therefore,   is  world-wide,  and  parasites  are 
discussed  regardless  of  where  they  occur.     However,  major  attention  is  given  to  the 
parasites  of  those  domestic  animals  which  occur  in  the  temperate  zones,  and  relatively 
little  is  included  on  parasites  of  animals  like  the  elephant,  camel,  llama,  reindeer  and 
yak,  even  tho  they  are  important  domestic  animals  in  some  regions. 

When  C.  M.  Wenyon  wrote  his  classic  Protozoology  in  1926,   he  remarked  that  one 
of  his  chief  difficulties  had  been  that  hardly  a  week  passed  without  the  publication  of  some 
paper  of  importance;  that  difficulty  is  far  greater  today  than  it  was  then.     The  number  of 
published  papers  has  been  increasing  exponentially,  and  there  is  no  sign  that  the  loga- 
rithmic phase  of  the  curve  is  near  its  end.    Even  if  one  tries  to  read  the  current  journals 
faithfully  and  to  use  the  abstract  journals  assiduously,  important  papers  may  escape  his 
notice.    I  am  sure  that  some  have  escaped  mine,  and  I  should  appreciate  having  them 
called  to  my  attention.    In  addition,  to  help  me  in  preparing  future  editions,  I  should  ap- 
preciate receiving  reprints  of  pertinent  papers. 

-  i  - 


A  favorite  saying  of  Jean  Baer  is  that  textbooks  perpetuate  errors  by  copying  them 
from  one  to  another.    I  have  tried  to  avoid  this  by  going  to  the  original  papers  as  much 
as  possible,  but  in  so  doing  I  may  well  have  introduced  some  errors  of  my  own.    I  should 
appreciate  having  these  called  to  my  attention  also. 

Papers  are  appearing  so  fast  that,  unless  one  is  forced  to  it,  he  cannot  take  the 
time  to  read  and  ponder  those  outside  his  own  immediate  field  of  interest  and  to  try  to 
integrate  them  into  a  coherent  whole.    Writing  this  book  has  made  me  do  so,  and  the 
process  has  taught  me  a  great  deal.     Not  only  have  I  learned  many  things  which  I  did  not 
know,  but  I  have  come  to  realize  more  clearly  how  much  information  we  still  lack,  even 
about  parasites  which  have  been  studied  extensively.     This  book  reflects  that  situation. 
The  reader  will  find  at  least  one  question,  one  gap  in  our  knowledge  on  each  page.     Each 
is  a  challenge  for  future  research  which  I  hope  will  be  accepted  by  many  who  read  this 
book. 

I  should  like  to  express  appreciation  to  Drs.  Carl  A.  Brandly,  John  O.  Corliss, 
William  R.   Horsfall,   Francis  J.  Kruidenier,   R.   N.   Mohan  and  Miss  Virginia  Ivens  for 
reading  and  commenting  on  various  chapters;  to  Mrs.   Helen  V.  Olson  for  preparing  fig- 
ures 6,   13A,   18,   19,   20K-1,  24  and  31;  to  Miss  Ada  Price  for  typing  the  greatest  part  of 
the  manuscript;  to  Mesdames  Marion  Corzine,   Mardell  Harris,  Kathryn  Hill,  Janet 
Manning,   Lucille  Rice,   Carolyn  Seets  and  Misses  Eileen  Bourgois  and  Beverly  Seward 
for  proof-reading  the  manuscript;  to  Drs.   E.   R.   Becker,  J.   F.   Christensen,   H.   Christl, 

F.  P.   Filice,  D.   M.   Hammond,   C.  A.   Hoare,  R.  R.  Kudo,  J.   Ludvik,  E.   R.   Noble, 

G.  A.   Noble,   Muriel  Robertson,  R.  M.  Stabler,   E.  E.   Tyzzer  and  D.   H.  Wenrich,  to 
Balliere,  Tindall  &  Cox,   Cambridge  University  Press,   Charles  C  Thomas,  the  Common- 
wealth Agricultural  Bureaux,  Gustav  Fischer  Verlag,  Iowa  State  University  Press,  Johns 
Hopkins  Press,   Springer-Verlag,   University  of  California  Press,  Williams  &  Wilkins  Co. 
and  The  Wistar  Institute,  and  to  the  Annals  of  Tropical  Medicine  and  Parasitology,  Iowa 
State  Journal  of  Science,  Journal  of  Morphology,  Journal  of  Parasitology,  Journal  of 
Protozoology,   Parasitology,  Quarterly  Journal  of  Microscopic  Science,  Quarterly  Re- 
view of  Biology,  University  of  California  Publications  in  Zoology,   Veterinary  Reviews 
and  Annotations,   Zeitschrift  fur  Parasitenkunde,   and  Zentralblatt  fur  Bakteriologie  for 
permission  to  reproduce  some  of  their  illustrations;  and,  not  the  least,  to  the  Burgess 
Publishing  Company  for  its  patience  and  understanding  during  the  time  this  manuscript 
was  in  preparation. 

NORMAN  D.   LEVINE 


University  of  Illinois 
Urbana 
November,  1960 


-  11  - 


^    -"-  Contents 

Page 

Preface  i 

Chapter 

1  Introduction  to  Parasitology 1 

2  Introduction  to  the  Protozoa 18 

3  The  Hemoflagellates 40 

4  Histomonas 74 

5  The  Trichomonads 82 

6  Other  Flagellates 107 

7  The  Amoebae 129 

8  The  Telosporasida  and  the  Coccidia  Proper 158 

9  Klossiella  and  Hepatozoon 254 

10  Plasmodium,  Haemoproteus  and  Leucocytozoon 259 

11  The  Piroplasmasida 285 

12  Sarcocystis,  Toxoplasma  and  Related  Protozoa 317 

13  The  Ciliates 347 

14  Laboratory  Diagnosis  of  Protozoan  Infections 377 

Appendix   Scientific  and  Common  Names  of  Some  Domestic 

and  Wild  Animals 395 

Index  and  Host-Parasite  Lists 399 


81589 


-  Ill 


Parasitology  is  the  science  which 
treats  of  parasites.     The  word  "parasite" 
is  derived  from  the  Greek  and  means, 
literally,   "situated  beside.  "    It  was  used 
by  the  ancient  Greeks  originally  for 
people  who  ate  beside  or  at  the  tables  of 
others,   and  referred  both  to  sycophants 
or  hangers-on  and  to  priests  who  col- 
lected grain  for  their  temples.    While  the 
social  meaning  of  the  term  has  been  par- 
tially retained,  it  has  been  given  a  new 
connotation  by  scientists.     Parasites  are 
defined  as  organisms  which  live  on  or 
within  some  other  living  organism,  which 
is  known  as  the  host.     Parasitism  is  the 
association  of  two  such  organisms. 

Parasites  may  be  either  animals  or 
plants--viruses,   rickettsiae,   spirochetes, 
bacteria,  yeasts,  fungi,   algae,  mistletoe, 
dodder,   protozoa,  helminths,  arthropods, 
molluscs,   and  even  certain  vertebrates 
such  as  the  cuckoo.     The  general  prin- 
ciples of  parasitology  apply  to  all.     How- 
ever,  in  this  book  we  shall  deal  primarily 
with  animal  parasites,   leaving  the  plant 
parasites  to  textbooks  of  microbiology. 

In  our  everyday  thinking  we  consider 
that  animals  can  live  in  three  main  hab- 
itats--land,  fresh  water  and  sea  water. 
A  fourth  habitat  is  the  parasitic  one, 
which  is  quite  different  from  the  other 
three.     As  a  matter  of  fact,  there  are 
quite  a  few  different  parasitic  habitats, 
each  with  its  own  characteristics.     Para- 
sites are  found  in  the  lumen  of  the  intes- 
tinal tract,  on  the  outside  of  the  body,  in 
the  skin,  in  various  tissues,   in  the  blood 
plasma,   inside  different  types  of  cells, 
and  even  inside  cell  nuclei. 

Parasites  have  arisen  from  free- 
living  animals.    Some  parasites  closely 
resemble  their  free-living  relatives,  but 
others  have  undergone  structural  changes 
which  make  them  more  suited  to  their 
changed  environment.     Since  these 
changes  have  in  many  cases  been  the  loss 
of  some  power  which  their  free-living 
relatives  possess,  parasites  have  some- 


C/iapter  1 


IHTROdUCTm 

TO 
PARASITOLOGY 


- 1 


INTRODUCTION  TO  PARASITOLOGY 


times  been  considered  degenerate  crea- 
tures.    The  opposite  is  true.     Parasites 
are  highly  specialized  organisms.     Those 
powers  which  were  unnecessary,  they 
have  lost.     For  instance,  the  adults  of 
most  parasitic  worms  have  relatively 
little  ability  to  move  around.     But  they 
don't  need  it.     Too  much  activity  might 
even  lead  to  their  reaching  the  point  of  no 
return  and  being  discharged  from  their 
host's  body. 

As  another  example,  tapeworms  have 
no  intestinal  tract.     But,   since  they  ob- 
tain their  nourishment  directly  thru  the 
body  wall,   an  intestine  would  be  super- 
fluous.    Thus,   in  the  case  of  parasites  as 
with  all  other  animals  and  plants,  the  use- 
less has  been  eliminated  in  the  course  of 
evolution. 


being  confronted  by  odds  of  this  sort  and 
are  continually  surmounting  them. 

Life  of  one  sort  or  another  seems  to 
have  flowed  into  every  possible  niche. 
Parasites  live  in  some  of  the  most  diffi- 
cult niches,  and  it  is  remarkable  how  they 
have  succeeded  in  surviving  in  them. 
Parasites  have  tremendous  problems  to 
solve--problems  of  nutrition,  of  respira- 
tion, of  excretion,  of  getting  from  one 
host  to  another--and  the  different  and 
often  ingenious  ways  in  which  different 
parasites  have  solved  these  problems  are 
amazing.     Some  of  their  adjustments  are 
almost  perfect;  others  are  less  satisfac- 
tory.   In  general,  we  may  say  that  the 
more  satisfactory  the  solution,  the  more 
abundant  are  the  parasites.     The  rare 
ones  are  the  less  successful  ones. 


In  contrast,  the  reproductive  system 
of  parasites  is  often  tremendously  devel- 
oped.   Since  the  chances  of  an  egg  or 
larva  leaving  one  host  and  infecting  an- 
other are  very  small,  the  numbers  of 
eggs  produced  must  be  very  large.    Many 
parasitic  worms  produce  thousands  of 
eggs  a  day.     The  female  of  Ascaris  suum, 
the  large  roundworm  of  swine,  lays  about 
1,  400,  000  eggs  per  day  (Kelley  and  Smith, 
1956).     Assuming  that  she  lives  200  days, 
which  is  not  an  excessive  life,   she  will 
have  laid  280  million  eggs  in  her  lifetime. 
Since  the  number  of  Ascaris  in  the  world 
is  staying  more  or  less  the  same,  we  can 
conclude  that  on  the  average  only  two  of 
these  eggs  will  produce  adult  worms--a 
male  and  a  female.    The  chance  of  any 
particular  egg  ever  becoming  a  mature 
worm  is  thus  about  1  in  140  million, 
which  is  much  less  than  a  man's  chance  of 
being  struck  by  lightning. 

The  broad  fish  tapeworm  of  the  dog, 
man  and  other  animals,  Diholliriocephalus 
laliis,  will  produce  over  4  miles  of  seg- 
ments containing  2  billion  eggs  during  a 
10-year  life  span,  and  again  the  number 
of  these  tapeworms  is  not  increasing. 
Since  these  tapeworms  are  hermaphro- 
dites, each  egg  can  become  an  egg-laying 
worm,  but  its  chances  of  doing  so  are  a 
hundred  times  less  than  those  of  the 
Ascaris  egg.     Parasites  are  continually 


We  can  think  of  parasitism  as  related 
basically  to  the  solution  of  the  problem  of 
nutrition,   and  we  can  think  of  the  other 
problems  as  somewhat  secondary.     This 
is  obviously  an  incomplete  and  defective 
view,  but  nevertheless  it  has  some  value. 

Living  organisms  have  four  general 
types  of  nutrition.    Holophytic  nutrition  is 
typical  of  plants;  it  involves  synthesis  of 
carbohydrates  by  means  of  chlorophyll. 
Holozoic  nutrition  is  animal-like;  it  in- 
volves ingestion  of  particulate  food  thru  a 
permanent  or  temporary  mouth.    Sapro- 
zoic  or  saprophytic  nutrition  (the  choice 
of  term  depending  upon  whether  the  organ- 
ism is  an  animal  or  plant)  involves  ab- 
sorption of  nutrients  in  solution  thru  the 
body  wall.    The  fourth  type  of  nutrition  is 
that  employed  by  viruses,  which  synthe- 
size their  proteins  directly  from  the  host's 
amino  acids  and  do  not  have  a  true  body 
wall  during  their  parasitic  phase. 

The  terms  saprophyte  and  saprophytic 
are  often  used  by  bacteriologists  in  an- 
other sense  also,  to  refer  to  non-patho- 
genic, non-parasitic  organisms.    The 
terms  saprozoite  and  saprozoic  are  also 
similarly  used  with  reference  to  free- 
living  animals,  but  much  less  frequently. 

Coprozoic  or  coprophilic  organisms 
are  animals  which  live  in  feces.    They 


INTRODUCTION  TO  PARASITOLOGY 


may  be  either  saprozoic  or  holozoic  or 
both,  and  are  sometimes  mistaken  for 
true  parasites. 

Parasites  resemble  predators  in  some 
respects;  indeed,  one  grades  into  the 
other.    In  general,  we  think  of  predators 
as  larger  than  or  as  large  as  their  prey, 
while  we  think  of  parasites  as  consider- 
ably smaller.     A  lion  seizing  an  antelope 
is  a  predator,   as  is  a  spider  capturing  a 
fly.     But  there  is  a  distinction  only  in  size 
of  prey  between  a  predatory  assassin  bug 
capturing  another  insect  and  sucking  out 
its  juices  and  the  closely  related,   para- 
sitic kissing  bug  sucking  blood  out  of  a 
man.     And  a  mosquito  is  just  as  much  a 
predator  as  the  kissing  bug.     The  distinc- 
tion is  one  of  degree.     As  Elton  (1935)  put 
it,   "The  difference  between  a  carnivore 
and  a  parasite  is  simply  the  difference  be- 
tween living  upon  capital  and  income,  be- 
tween the  burglar  and  the  blackmailer. 
The  general  result  is  the  same  although 
the  methods  employed  are  different." 


TYPES  OF   PARASITISM 

There  are  several  types  of  parasitism. 
Parasitism  itself  is  defined  as  an  associa- 
tion between  two  specifically  distinct  or- 
ganisms in  which  one  lives  on  or  within 
the  other  in  order  to  obtain  sustenance. 

SvDibiosis  is  the  permanent  associa- 
tion of  two  specifically  distinct  organisms 
so  dependent  upon  each  other  that  life 
apart  is  impossible  under  natural  condi- 
tions.   The  relation  between  many  ter- 
mites and  their  intestinal  protozoa  is 
symbiotic.     The  termites  eat  wood,  but 
they  cannot  digest  it;  the  protozoa  can  di- 
gest wood,  turning  it  into  glucose,  but 
they  have  no  way  of  obtaining  it;  working 
together,  the  termites  ingest  wood  par- 
ticles, the  protozoa  break  the  cellulose 
down  to  glucose,  and  the  termites  then 
digest  the  glucose.     Lichens  furnish  an- 
other example  of  symbiosis.     They  are 
composed  of  certain  species  of  algae  and 
fungi  living  together. 

Many  insects,  ticks  and  mites  have 
symbiotic  bacteria  and  rickettsiae.    The 


symbiotic  organisms  are  found  either  in 
special  cells,  the  mycetocytes,   in  modi- 
fied parts  of  the  Malpighian  tubules,  or 
in  special  organs,  the  mycetomes.    It  is 
significant  that,   among  blood-sucking 
arthropods,  symbiosis  occurs  in  those 
which  live  on  blood  thruout  their  life  cy- 
cles (ticks,  lice,  bedbugs,  kissing  bugs, 
tsetse  flies,  hippoboscid  flies)  but  not  in 
those  in  which  only  the  adults  suck  blood 
while  the  larvae  are  free-living  (fleas, 
mosquitoes,   phlebotomines,  tabanids  and 
stable  flies).     Blood  lacks  some  metabo- 
lites which  the  arthropods  are  unable  to 
synthesize  themselves  and  for  which  they 
depend  on  their  symbiotes.     These  meta- 
bolites appear  to  include  vitamins  of  the 
B  group  and  probably  other  substances  as 
well  (Buchner,   1953;  Koch,   1956;  Weyer, 
1960). 

Mutualism  is  an  association  of  two 
organisms  by  which  both  are  benefited. 
It  differs  from  symbiosis  in  that  it  is  not 
obligatory  for  both  partners.     One  exam- 
ple often  cited  is  that  of  a  sea  anemone 
living  upon  the  back  of  a  crab.     The  anem- 
one is  benefited  by  being  moved  to  new 
hunting  grounds  and  by  obtaining  morsels 
of  food  torn  off  by  the  crab,  while  the  crab 
is  protected  by  the  bulk  and  stinging  ten- 
tacles of  the  anemone.     Another  marine 
example  is  that  of  the  scorpion  fish  of 
Indo-Malaya.    It  lives  on  the  bottom  of  the 
sea,  where  it  lies  in  wait  for  passing  fish. 
It  is  covered  with  a  crust  of  hydroids 
which  camouflage  it  so  that  it  can  seize 
its  unwary  prey  more  easily.    The  hydroids 
presumably  benefit  by  being  moved  to  new 
sources  of  food  and  by  being  provided  with 
a  dwelling-place.    However,  since  they 
can  live  other  places  beside  the  scorpion 
fish's  back,  their  relation  is  mutualistic. 

Another  example  of  mutualism,  and 
one  closer  to  us,   is  the  relationship  be- 
tween ruminants  and  the  cellulose-digest- 
ing bacteria  and  other  micro-organisms 
in  their  rumens.    The  latter  are  furnished 
a  favorable  home  by  their  hosts  and  aid 
them  by  breaking  down  cellulose  to  usable 
compounds.     The  rumen-dwelling  bacteria 
which  produce  B  group  vitamins  and  thus 
make  an  outside  source  of  them  unneces- 
sary for  ruminant  nutrition  probably 


INTRODUCTION   TO  PARASITOLOGY 


belong  here  too,  altho  they  verge  on  the 
symbiotic.     The  bacteria  which  produce 
these  vitamins  in  the  large  intestine  of 
swine  are  more  nearly  mutualistic,  since 
the  pigs  cannot  absorb  the  vitamins  thru 
the  colon  wall  but  must  re-ingest  their 
feces  to  obtain  them.     The  same  is  true 
of  rabbits,   and  is  undoubtedly  responsible 
for  their  coprophagy. 

The  bizarre  protozoa  which  swarm 
in  the  rumen  and  reticulum  are  almost 
certainly  mutualistic.     Their  host  can  get 
along  without  them,  but  they  may  benefit 
it  by  providing  a  better  type  of  protein 
than  it  ingests.    In  addition,  they  are  an 
important  source  of  volatile  fatty  acids, 
and  they  smooth  out  the  carbohydrate  fer- 
mentation process. 

Commensalism  is  an  association  be- 
tween host  and  parasite  in  which  one  part- 
ner is  benefited  and  the  other  is  neither 
benefited  nor  harmed.     Many  intestinal 
bacteria  such  as  Escherichia  coli  are 
normally  commensals,  as  are  many  in- 
testinal protozoa  such  as  Entamoeba  coli 
and  Trichomonas  spp. 

The  next  two  terms  both  refer  to  po- 
tentially pathogenic  parasites.    Parasito- 
sis is  the  association  between  two  organ- 
isms in  which  one  injures  the  other, 
causing  signs  and  lesions  of  disease. 
Parasitiasis  is  the  association  between 
two  organisms  in  which  one  is  potentially 
pathogenic  but  does  not  cause  signs  of 
disease. 

The  difference  between  parasitosis 
and  parasitiasis  is  quantitative.     In  para- 
sitiasis the  host  is  able  to  repair  the 
damage  caused  by  the  parasite  without 
noticeable  injury,  while  in  parasitosis  it 
cannot.     As  Whitlock  (1955)  put  it,   "Para- 
sitiasis is  a  state  of  balance.     Parasitosis 
is  a  state  of  imbalance.  "    Applying  the 
concept  to  ruminant  helminths,  Gordon 
(1957)  said,   "Helminthiasis  is  almost  uni- 
versal and  continuous,   helminthosis  is 
more  restricted  and  sporadic.     However, 
one  shades  imperceptibly  into  the  other  in 
subclinical  infestations."    The  same  or- 
ganism can  cause  either  parasitosis  or 
parasititiasis,  depending  upon  the  number 


present  or  upon  the  nutritional  condition, 
age,   sex,   immune  state,  etc.  of  the  host. 
Failure  to  recognize  this  distinction  may 
cause  many  false  diagnoses--the  mere 
presence  of  a  potentially  pathogenic  spe- 
cies of  parasite  does  not  necessarily 
mean  that  it  is  causing  disease. 

The  carrier  state  furnishes  a  good 
example  of  parasitiasis.     Carriers  are 
animals  which  have  a  light  infection  with 
some  parasite  but  are  not  harmed  by  it, 
usually  due  to  immunity  resulting  from 
previous  exposure,  but  which  serve  as  a 
source  of  infection  for  susceptible  ani- 
mals.    Thus,   adult  sheep  and  cattle  may 
be  lightly  infected  with  gastrointestinal 
nematodes  without  noticeable  effect,  but 
their  lambs  and  calves  may  become  heav- 
ily parasitized  from  grazing  with  them. 
The  condition  in  the  adults  is  parasitiasis; 
that  in  the  young  is  parasitosis.     Adult 
chickens  rarely  suffer  from  coccidiosis 
because  they  have  recovered  from  a  clin- 
ical or  subclinical  attack  when  young. 
However,   they  are  usually  still  lightly  in- 
fected and  continue  to  shed  a  few  oocysts; 
they  have  coccidiasis.     Cattle  which  have 
aborted  as  a  result  of  Brucella  infection 
may  continue  to  shed  the  bacteria  in  their 
milk  without  ordinarily  suffering  further 
clinical  attacks.     The  aborting  cow  has 
brucellosis,  while  the  carrier  has  bru- 
celliasis. 

These  endings  can  also  be  applied  to 
the  names  of  the  disease  agents,  as  has 
already  been  done  above.     Thus,  Haenion- 
chiis  coiitortus  may  cause  haemonchosis 
or  haemonchiasis,  Taenia  may  cause 
taeniosis  or  taeniasis,  Histomo>ias  mel- 
eagridis  may  cause  histomonosis  or  his- 
tomoniasis,  depending  on  the  circum- 
stances. 

It  was  mentioned  earlier  that  the  so- 
lutions different  parasites  have  made  of 
their  problems  of  living  have  varied  in 
satisfactoriness.    We  might  consider  this 
in  regard  to  type  of  parasitism.    Symbio- 
sis is  a  highly  specialized  type  of  associ- 
ation which  occurs  only  in  certain  groups. 
Mutualism  is  a  much  looser  association, 
also  fairly  uncommon.    It  could  well  be  a 
step  on  the  road  to  symbiosis.    The  most 


INTRODUCTION  TO  PARASITOLOGY 


common  types  of  parasitism  are  the  last 
three.    Of  these,  commensalism  is 
clearly  the  most  desirable,  both  from  the 
standpoint  of  the  host  (which  isn't  harmed) 
and  of  the  parasite.     Parasitosis,  which 
harms  the  host,  is  in  the  long  run  harm- 
ful to  the  parasite  also.     By  injuring  their 
hosts,   parasites  harm  their  environment, 
and  if  they  are  so  indiscreet  as  to  kill 
their  hosts,  they  die  too.     Parasitiasis 
is  intermediate  between  parasitosis  and 
commensalism  in  some  cases,  but  not  in 
all. 


HOST- PARASITE 
RELATIONS 

Depending  on  their  species,   para- 
sites may  live  in  any  organ  or  tissue  of 
the  host;  they  may  live  on  its  surface,  or 
they  may  spend  most  of  their  time  away 
from  it.    Special  terms  have  been  applied 
to  these  relationships.    An  endoparasite 
is  a  parasite  that  lives  within  the  host's 
body.    An  ectoparasite  is  one  that  lives 
on  the  outside  of  the  body.    An  erratic 
{oT  aberrant)  parasite  is  one  that  has 
wandered  into  an  organ  in  which  it  does 
not  ordinarily  live.    An  incidental  para- 
site is  a  parasite  in  a  host  in  which  it  does 
not  usually  live.     A  facultative  parasite  is 
an  organism  that  is  capable  of  living 
either  free  or  as  a  parasite.    An  obliga- 
tory parasite  is  an  organism  which  must 
live  a  parasitic  existence.    A  periodic 
parasite  is  one  which  makes  short  visits 
to  its  host  to  obtain  nourishment  or  other 
benefits.    A  pseudoparasite  is  an  object 
that  is  mistaken  for  a  parasite.    Para- 
sites may  themselves  be  parasitized  by 
hyperparasites . 

An  organism  which  harbors  a  para- 
site is  its  host.    There  are  several  types 
of  host.     A  definitive  host  is  the  host 
which  harbors  the  adult  stage  of  a  para- 
site.    An  intermediate  host  is  the  host 
which  harbors  the  larval  stages  of  the 
parasite.    A  first  intermediate  host  is 
the  first  host  parasitized  by  the  larval 
stages  of  the  parasite.    A  second  inter- 
mediate host  is  the  host  parasitized  by 
the  larval  stages  at  a  later  period  in  the 
life  cycle.    A  paratenic  or  transport  host 


is  a  second  (or  third)  intermediate  host 
in  which  the  parasite  does  not  undergo  any 
development  but  usually  remains  encysted 
until  the  definitive  host  eats  the  paratenic 
host. 

The  vector  of  a  parasite  or  disease 
agent  is  an  arthropod,  mollusc  or  other 
agent  which  transmits  the  parasite  from 
one  vertebrate  host  to  another.    If  the 
parasite  develops  or  multiplies  in  the 
vector,   it  is  called  a  biological  vector. 
If  the  parasite  does  not  develop  or  mul- 
tiply in  it,  it  is  called  a  mechanical  vec- 
tor. 

Intermediate  hosts  of  helminths  are 
biological  vectors,  but  biological  vectors 
are  not  necessarily  intermediate  hosts. 
Indeed,  the  latter  term  has  no  applica- 
tion to  protozoa,  bacteria,   rickettsia  or 
viruses,  none  of  which  have  larvae.  Mos- 
quitoes are  biological  vectors  of  malaria 
and  of  yellow  fever,   and  the  tsetse  fly  is 
a  biological  vector  of  Trypanosoma 
brucei,   for  the  parasites  must  develop  in 
them  to  become  infective  for  the  next  ver- 
tebrate host.    However,  tabanid  flies  are 
merely  mechanical  vectors  of  Trypano- 
soma evansi,   since  the  parasites  undergo 
no  development  in  them. 

The  terms  infection  and  infestation 
are  used  by  different  people  in  different 
ways.     The  former  term  originally  re- 
ferred to  internal  agents  of  disease, 
while  the  latter  was  used  with  reference 
to  external  harassing  agents,  including 
not  only  ectoparasites  but  also  rodents, 
pirates  and  thieves.    This  usage  was  cur- 
rent during  the  latter  part  of  the  nine- 
teenth century.     Later  on,  it  was  felt  de- 
sirable to  distinguish  between  parasites 
which  multiplied  in  their  hosts  and  those 
which  did  not.     "Infection"  was  then  used 
for  the  former  type  of  parasitism,  and 
"infestation"  for  the  latter.     This  usage 
was  popular  for  a  time,  but  it  was  never 
universally  accepted.     More  recently 
there  has  been  a  trend  toward  the  older 
usage.     Most  American  parasitologists 
have  accepted  it,  but  most  British  ones 
prefer  to  speak  of  helminth  infestations. 
In  this  book  infection  will  be  used  to  refer 
to  parasitism  by  internal  parasites,  and 


INTRODUCTION  TO  PARASITOLOGY 


infestation  to  parasitism  by  external  para- 
sites. 

The  term  life  cycle  refers  to  the  de- 
velopment of  a  parasite  thru  its  various 
forms.    It  may  be  simple,  as  in  an  organ- 
ism which  multiplies  only  by  binary  fis- 
sion, or  it  may  be  extremely  complex, 
involving  alternation  of  sexual  and  asexual 
generations  or  development  thru  a  series 
of  different  larval  forms.     A  )>ionogenetic 
parasite  is  one  in  which  there  is  no  alter- 
nation of  generations.     Examples  of  this 
type  are  bacteria,  flagellate  protozoa 
such  as  Trichomonas ,  nematodes  such  as 
Ascaris    and  Ancylostoma,  and  the  ecto- 
parasitic  fish  trematodes  of  the  order 
Monogenorida  (=  Monogenea).     A  hetero- 
genetic  parasite  is  one  in  which  there  is 
alternation  of  generations.     Examples  of 
this  type  are  malarial  parasites  and  coc- 
cidia,  in  which  sexual  and  asexual  gen- 
erations alternate,  the  endoparasitic 
trematodes  of  higher  vertebrates  of  the 
order  Digenorida  (=  Digenea),  in  which 
there  may  be  several  larval  multiplicative 
stages  before  the  adult,  and  the  nematode, 
Strongyloides,  in  which  one  generation  is 
parasitic  and  parthenogenetic  while  an- 
other is  free-living  and  sexual. 

Depending  on  their  type,  parasites 
may  live  in  only  one  or  in  a  number  of 
different  types  of  hosts  during  the  course 
of  their  normal  life  cycles.    A  monoxen- 
ous  parasite  has  only  one  type  of  host-- 
the  definitive  host.     Examples  are  coc- 
cidia,  amoebae,  hookworms,  fish  trema- 
todes, horse  bots,   streptococci  and  most 
pox  viruses.     A  heteroxenous  parasite 
has  two  or  more  types  of  host  in  its  life 
cycle.     Examples  are  the  malarial  para- 
sites, most  trypanosomes,  trematodes  of 
higher  vertebrates,  filariae,  tapeworms, 
the  rickettsiae,  yellow  fever  virus  and 
various  encephalitis  viruses. 

These  two  pairs  of  terms  are  inde- 
pendent of  each  other.     Parasitic  amoebae 
and  hookworms  are  monogenetic  and 
monoxenous.     Filariid  and  spirurid  nema- 
todes are  monogenetic  and  heteroxenous. 
Strongyloides  and  most  coccidia  are  het- 
erogenetic  and  monoxenous.    Malarial 
parasites  and  trematodes  of  birds  and 


mammals  are  heterogenetic  and  hetero- 
xenous. 

Another  group  of  terms  deals  with 
host  range,  i.e.  ,  the  number  of  host  spe- 
cies in  which  a  particular  parasite  may 
occur.     These  parasites  can  be  either 
monoxenous  or  heteroxenous,  monogen- 
etic or  digenetic.    Indeed,  there  may  be 
a  difference  in  host-restriction  between 
the  definitive  and  intermediate  hosts  of 
the  same  parasite.    For  example,  the 
blood  fluke,  Schistosoma  japoniciini,    can 
become  adult  in  a  rather  wide  range  of 
mammals,  but  its  larval  stages  will  de- 
velop in  only  a  few  closely  related  species 
of  snails. 

The  term,  monoxenous  parasite,  is 
used  by  some  authors  for  a  parasite  which 
is  restricted  to  a  single  host  species. 
Such  parasites  undoubtedly  exist,  but  they 
are  fewer  than  our  present  records  indi- 
cate.    The  human  malarial  parasites  were 
once  thought  to  be  monoxenous  in  this 
sense  of  the  word,  but  they  have  more  re- 
cently been  found  capable  of  infecting 
apes,   and  it  is  now  known  that  chimpan- 
zees in  West  Africa  are  naturally  infected 
with  P.  malariae,  the  cause  of  quartan 
malaria  in  man  (Garnham,   1958).     Many 
species  of  coccidia  are  also  known  from 
but  a  single  host,  but  for  the  most  part 
closely  related  wild  hosts  have  not  been 
examined  nor  have  cross  transmission  ex- 
periments been  attempted  with  them.     Be- 
cause of  this  and  because  of  the  confusion 
arising  between  this  usage  of  monoxenous 
and  the  one  defined  above,  this  usage 
should  be  avoided. 

A  stenoxenoiis  parasite  is  one  which 
has  a  narrow  host  range.     Among  the 
coccidia,  members  of  the  genus  Eimeria 
are  generally  stenoxenous,  as  are  the 
human  malaria  parasites  and  cyclophyl- 
lidorid  tapeworms.     Many  nematodes  such 
as  the  hookworms,  nodular  worms,  fila- 
riids  and  spirurids  tend  to  be  stenoxenous. 
Both  biting  and  sucking  lice  are  steno- 
xenous, and  many  are  even  limited  to 
specific  areas  on  their  host.    Relatively 
few  bacteria  are  stenoxenous,  but  Strep- 
tococcus agalactiae,  Mycobacterium 
leprae,    Vibrio,  Mycoplasma,  the  spiro- 


INTRODUCTION  TO  PARASITOLOGY 


chete,   Treponema,   the  rickettsiae,  Ana- 
plasma,  Eperythrozoon,  Haemobartonella 
and  Cowdria,   and  the  viruses  of  hog  chol- 
era, duck  hepatitis  and  yellow  fever  are 
stenoxenous. 


5.  7%  of  its  mammals.    If  all  these  pos- 
sible hosts  were  to  be  examined,  one 
might  expect  to  find  some  3500  species  of 
Eimeria  in  mammals  and  34,000  in  chor- 
dates. 


An  euryxenous  parasite  is  one  which 
has  a  broad  host  range.     Among  the  coc- 
cidia,  members  of  the  genus  Isospora 
are  often  euryxenous.    So  are  most  try- 
panosomes,  most  Plasmodium  species 
(but  not  those  affecting  man),  and  many 
species  of  Trichomonas.    Most  trema- 
todes  are  euryxenous,  as  are  Trichinella, 
Dracunculns  and  Dioctophyma  among  the 
nematodes.    Fleas,  chiggers  and  many 
ticks  are  euryxenous.     Most  parasitic 
bacteria  are  euryxenous;  examples  are 
most  species  of  Salmonella,  Escherichia, 
Brucella,  Erysipelothrix  and  Listeria. 
Among  euryxenous  rickettsiae  are 
Rickettsia,   Coxiella  and  Miyagawanella 
psittacii.     Among  euryxenous  viruses  are 
those  of  rabies  and  many  encephalitides. 
Leptospira  and  Borrelia  are  euryxenous 
spirochetes. 

The  use  of  these  two  terms,  however, 
may  be  deceptive.    There  exist  in  nature 
all  intergrades  between  them,  and  all  we 
have  done  has  been  to  pick  out  the  two 
extremes  of  a  continuum  and  give  them 
names. 

Actually,  the  host  range  of  most 
parasites  is  broader  than  generally  sup- 
posed.   The  fact  is  that  most  animal 
species  have  not  been  examined  for  para- 
sites.    For  example,  the  genus  Eimeria 
is  one  of  the  commonest  and  best  known 
among  parasitic  protozoa.    Becker  (1956) 
listed  403  species,  of  which  394  were 
from  chordates  and  202  from  mammals. 
This  is  quite  impressive,  especially  to 
someone  who  wishes  to  study  their  tax- 
onomy.    However,  according  to  Muller 
and  Campbell  (1954),  there  are  33,640 
known  living  species  of  chordates  and 
3552  of  mammals.    Some  hosts  have 
more  than  one  species  of  Eimeria,  but 
some  coccidian  species  occur  in  more 
than  one  host.    Assuming  that  these  more 
or  less  cancel  out,  we  can  calculate  that 
Eimeria  has  been  described  from  only 
1. 17%  of  the  world's  chordates  and  from 


So  far  only  the  qualitative  aspect  of 
the  host  range  has  been  discussed.     How- 
ever, altho  a  parasite  may  be  capable  of 
living  in  more  than  one  host,  it  is  much 
more  common  in  some  hosts  than  in 
others.     The  principal  hosts  of  a  parasite 
are  those  hosts  in  which  it  is  most  com- 
monly found.     The  supplementary  hosts 
are  those  of  secondary  importance,  and 
the  incidental  hosts  are  those  which  are 
infected  only  occasionally  under  natural 
conditions.     To  these  should  be  added 
experimental  hosts,   which  do  not  normally 
become  infected  under  natural  conditions 
but  which  can  be  infected  in  the  laboratory. 
This  last  category  may  include  both  inci- 
dental and  supplementary  hosts  and  also 
hosts  never  infected  in  nature. 

In  order  to  take  into  account  this 
quantitative  aspect  of  the  host-parasite 
relationship,  the  terms  quantitative  host 
spectrum  or  quantitative  host  range  are 
used.    These  give  the  amount  of  infection 
present  in  each  infected  species. 

Several  factors  affect  the  quantita- 
tive host  spectrum.     One  is  geographic 
distribution.    The  natural  quantitative 
spectrum  may  be  quite  different  in  one 
locality  than  in  another.    The  species  of 
animals  present  may  be  different,  or  the 
incidence  of  infection  may  be  different. 
For  example,  a  number  of  nematodes 
parasitize  both  domestic  and  wild  rumi- 
nants.    However,  since  the  wild  rumi- 
nants of  North  America  and  Africa  are 
not  the  same,  the  quantitative  host  spec- 
tra of  the  same  parasites  on  the  two  con- 
tinents are  different.     The  spectrum  is 
still  different  in  Australia,  where  there 
are  no  wild  ruminants  but  where  wild 
rabbits  are  susceptible  to  infection  with 
a  few  ruminant  nematodes. 

A  second  factor  is  climate.    Many  of 
the  same  host  species  may  be  present  in 
different  areas  but  climatic  conditions  in 
one  area  may  prevent  or  favor  a  para- 


INTRODUCTION   TO  PARASITOLOGY 


Site's  transmission.     For  instance,  the 
common  dog  hookworm  in  most  parts  of 
the  United  States  is  Ancylostoma  caninum, 
but  in  Canada  it  is  Uncinaria  slenocephala. 
This  is  due  to  a  difference  in  temperature 
tolerance  of  the  free-living  larval  stages. 

Local  conditions  such  as  ground  cover 
are  also  important.    If  the  vegetation  is 
open  so  that  the  sunlight  can  get  down  to 
the  surface  of  the  soil  where  a  parasite's 
eggs,  cysts  or  free-living  stages  are 
found,  survival  will  be  much  less,  trans- 
mission will  be  reduced  and  the  numbers 
of  affected  hosts  will  be  fewer  than  if  the 
vegetation  is  thick  and  protective.    Or  the 
kinds  and  numbers  of  parasites  in  a  herd 
of  animals  confined  to  a  low,  moist  pas- 
ture may  be  quite  different  from  those  in 
a  herd  kept  on  a  hill  pasture  or  on  drylot. 

A  fourth  factor  is  that  of  the  distribu- 
tion of  acceptable  intermediate  hosts. 
Trypanoso7na  briicei  occurs  only  in  Africa 
because  its  tsetse  fly  intermediate  hosts 
occur  only  there.     The  fringed  tapeworm 
of  sheep,   Thysanosoma  actinioides,   is 
found  in  the  western  United  States  but  not 
in  the  east  despite  the  fact  that  infected 
sheep  have  repeatedly  been  introduced 
onto  eastern  pastures.     A  suitable  inter- 
mediate host  does  not  occur  on  these 
pastures,  so  the  parasite  cannot  be  trans- 
mitted. 

A  fifth  factor  is  that  of  chronologic 
time.    The  quantitative  host  spectrum  may 
be  quite  different  in  the  same  locality  at 
different  periods,  particularly  if  an  erad- 
ication campaign  has  been  carried  out  in 
the  interim.     Echinococcosis  is  a  case  in 
point.     At  one  time  it  was  extremely  com- 
mon in  the  dogs,  sheep  and  people  in  Ice- 
land, but  it  has  now  been  eradicated. 
Gapeworms  were  once  common  in  poultry 
in  the  United  States,  but  as  the  result  of 
modern  poultry  management  practices 
they  are  now  exceedingly  rare  in  chickens 
and  turkeys,  altho  they  are  not  uncommon 
in  pheasants. 

A  sixth  factor  is  that  of  the  ethology 
or  habits  of  the  host.    A  species  may  be 
highly  susceptible  to  infection  with  a  par- 
ticular parasite,  yet  natural  infections 


may  seldom  or  never  occur.     The  habits 
of  the  host  may  be  such  that  it  rarely 
comes  in  contact  with  a  source  of  infec- 
tion even  tho  both  exist  in  the  same  local- 
ity.    For  example,  wild  mink  in  the  mid- 
western  United  States  are  not  infrequently 
infected  with  the  lung  fluke,   Paragonimus 
kelUcotti.     It  is  easy  to  infect  dogs  with 
this  fluke  experimentally,  yet  it  is  ex- 
tremely rare  in  midwestern  dogs.    The 
reason  is  that  dogs  rarely  eat  the  cray- 
fish which  are  the  fluke's  intermediate 
host. 

Because  of  these  factors,  we  must 
speak  of  «a///rrt/  and  potential  host  spec- 
tra.    The  latter  term  refers  to  the  abso- 
lute infectability  of  potential  hosts  and  not 
to  the  natural  situation.     The  natural  host 
spectrum  is  an  expression  of  the  actual 
situation  at  a  particular  time  and  place. 
The  two  spectra  may  be  quite  different, 
and  of  course  the  natural  one  will  vary 
considerably,  depending  on  the  circum- 
stances.   The  complete  host  spectrum  has 
not  been  worked  out  for  any  parasite,   and 
to  do  so  would  be  a  very  time-consuming 
process.     However,   it  will  have  to  be 
done,  at  least  for  the  more  important 
parasites,  before  we  can  fully  understand 
their  ecology  and  the  epidemiology  of  the 
diseases  they  cause. 

Certain  parasites  and  diseases  occur 
in  man  alone,  others  in  domestic  animals 
alone,  and  others  in  wild  animals  alone. 
Still  others,   including  some  important 
ones,  occur  in  both  man  and  domestic 
animals,  man  and  wild  animals,  domestic 
and  wild  animals,  or  in  all  three.     A 
knowledge  of  their  host  relations  is  im- 
portant in  understanding  their  ecology  and 
epidemiology. 

A  disease  which  is  common  to  man 
and  lower  animals  is  known  as  a  zoo)iosis. 
Zoonoses  were  redefined  in  1958  by  the 
Joint  WHO  FAO  Expert  Committee  on 
Zoonoses  as  "those  diseases  and  infec- 
tions which  are  naturally  transmitted  be- 
tween vertebrate  animals  and  man"  (World 
Health  Organization,   1959).     Less  than  20 
years  ago  it  was  said  that  there  were  50 
zoonoses,  but  in  the  above  report  the 
World  Health  Organization  listed  more 


INTRODUCTION  TO  PARASITOLOGY 


than  100,  of  which  23  were  considered  of 
major  importance.  Many  more  are  cer- 
tain to  be  revealed  by  future  investigations. 

Our  thinking  about  parasites  and  dis- 
eases is  ordinarily  oriented  toward  either 
man  or  domestic  animals.    In  this  context, 
it  is  convenient  to  have  a  special  term  for 
hosts  other  than  those  with  which  we  are 
primarily  concerned.    A  reservoir  host 
is  a  vertebrate  host  in  which  a  parasite  or 
disease  occurs  naturally  and  which  is  a 
source  of  infection  for  man  or  domestic 
animals,  as  the  case  may  be.    Wild  ani- 
mals are  reservoirs  of  infection  for  man 
of  relapsing  fever,  yellow  fever  and  moist 
Oriental  sore,  while  domestic  animals  are 
reservoirs  for  man  of  trichinosis  and 
classical  Oriental  sore.    Wild  animals  are 
reservoirs  of  infection  for  domestic  ani- 
mals of  many  trypanosomes,  while  man  is 
a  reservoir  for  domestic  animals  of  Enta- 
moeba histolytica. 

Parasites  and  diseases  may  continue 
to  exist  indefinitely  in  their  reservoir 
hosts,  and  man  or  domestic  animals  may 
become  infected  when  they  enter  the  local- 
ity where  the  parasites  or  diseases  exist. 
Such  a  locality  is  known  as  a  nidus  (liter- 
ally, "nest").    This  term  is  used  primarily 
in  connection  with  vector-borne  diseases, 
altho  it  need  not  be  restricted  to  them. 


epidemiology,  taxonomy,  evolution,  etc. 
(see  Hoare,   1955).     A  dei)ie  is  a  natural 
population  within  a  species.    It  lies  more 
or  less  below  the  subspecies  level,  but  it 
is  not  a  formal  taxon  and  is  not  given  a 
Latin  name.     There  are  different  types  of 
deme.     Nosodemes  differ  in  their  clinical 
manifestations.     One  example  is  Leish- 
mania  donovani,  which  has  five  nosodemes, 
Indian,   Mediterranean,  Sudanese,   Chinese 
and  South  American,  which  produce  differ- 
ent types  of  disease.    Serodemes  differ 
serologically.     These  are  best  known 
among  the  bacteria  and  viruses,  but  also 
occur  among  the  animal  parasites.     Tri- 
trichonionas  foetus,  for  example,   has 
several  serological  types  or  serodemes. 
Xenodemes  differ  in  their  hosts,  and  topo- 
demes  differ  in  geographic  distribution. 

There  are  also  other  types  of  demes. 
The  population  of  a  parasite  species  within 
a  single  host  animal  is  a  i)io)iodenie,  and 
that  in  a  single  flock  or  herd  is  an  agele- 
deme.    Thus,  a  population  of  the  stomach 
worm,   Haemouchus  contortus,  in  a  single 
sheep  is  a  monodeme,  the  population  in 
all  the  sheep  of  a  single  flock  is  an  agele- 
deme,  that  in  all  sheep  is  a  xenodeme. 
The  population  in  all  cattle  is  another 
xenodeme  and  that  in  all  goats  is  a  third, 
the  population  of  H.   contortus  in  all  hosts 
in  North  America  is  a  topodeme,  etc. 


Natural  nidi  may  be  elementary  or 
diffuse  (Palovsky,  1957).    An  elementary 
nidus  is  confined  within  narrow  limits. 
A  rodent  burrow  containing  rodents,  arga- 
sid  ticks  and  relapsing  fever  spirochetes 
or  a  woodrat  nest  containing  woodrats, 
kissing  bugs  and  Trypanosoma  cruzi  is  an 
elementary  nidus.    In  a  diffuse  nidus  the 
donors,  vectors  and  recipients  are  distrib- 
uted more  widely  over  the  landscape.     A 
wooded  region  in  which  ticks  circulate 
Rickettsia  rickettsii  among  the  rodents 
and  lagomorphs  is  a  diffuse  nidus  of 
Rocky  Mountain  spotted  fever,  as  is  an 
area  where  tsetse  flies  transmit  trypan- 
osomes among  wild  game.    The  nidality 
of  a  disease  refers  to  the  distribution  and 
characteristics  of  its  nidi. 

The  concept  of  the  deme  is  useful  in 
discussing  host-parasite  relationships, 


Each  of  these  demes  may  differ  mor- 
phologically and  physiologically,  and  a 
large  part  of  the  taxonomist's  work  con- 
sists in  determining  the  limits  of  their 
variation  and  deciding  whether  they  are 
really  demes  or  different  species.     Since 
the  judgments  of  all  taxonomists  do  not 
agree,  there  is  some  variation  in  the 
names  which  different  parasitologists  use. 
Demes  are  advance  guards  in  the  march 
of  evolution,  and  no  sharp  line  can  be 
drawn  beyond  which  they  become  subspe- 
cies or  species.    Taxonomists  have  been 
able  to  arrive  at  no  better  statement  of 
how  species  are  defined  than  to  say  that  a 
species  is  what  a  specialist  on  its  group 
says  it  is.     And  since  some  scientists  are 
splitters  and  others  are  lumpers,  their 
definitions  vary  with  their  temperaments. 
For  most  of  us,  the  best  rule  is  the  prag- 
matic one  of  using  those  names  which 


10 


INTRODUCTION  TO  PARASITOLOGY 


make  for  the  greatest  understanding  of  the 
organisms  we  study  and  of  their  relations 
with  each  other  and  with  their  hosts. 

Parasite  evolution:      Parasites  have 
evolved  along  with  their  hosts,  and  as  a 
consequence  the  relationships  between  the 
parasites  of  different  hosts  often  give  val- 
uable clues  to  the  relationships  of  the 
hosts  themselves.     Certain  major  groups 
of  parasites  are  confined  to  certain  groups 
of  hosts.    Sucking  lice  are  found  only  on 
mammals.     Biting  lice  occur  primarily  on 
birds,  but  a  few  species  are  found  on 
mammals.     The  monogenetic  trematodes 
are  found  almost  without  exception  on  fish; 
some  of  the  more  highly  evolved  digenetic 
trematodes  are  found  in  fish,  but  more 
occur  in  higher  vertebrates.     There  is  a 
tendency,  too,  for  the  more  advanced  di- 
genetic trematodes  to  occur  in  the  higher 
host  groups. 

One  would  expect  that,  as  evolution 
progressed  in  different  host  groups,  there 
would  develop  in  each  one  its  own  group 
of  parasites.     This  has  often  occurred. 
Thus,  of  the  48  families  of  digenetic 
trematodes  listed  by  Dawes  (1956),   17 
occur  only  in  fish,   8  only  in  birds,   3  only 
in  mammals,   2  in  fish  and  amphibia,   3  in 
reptiles  and  birds,   6  in  birds  and  mam- 
mals,  1  in  fish,  amphibia  and  reptiles, 
2  in  reptiles,  birds  and  mammals,   1  in 
amphibia,  reptiles  and  birds,  3  in  all  but 
fish,   and  2  in  all  five  classes  of  verte- 
brates.   Of  the  11  classes  of  tapeworms 
recognized  by  Wardle  and  McLeod  (1952), 
4  are  found  only  in  elasmobranch  fish,   3 
only  in  teleosts,   1  only  in  birds,   1  in 
teleosts,  amphibia  and  reptiles,   1  in  tel- 
eosts, birds  and  mammals,  and  1  in  am- 
phibia,  reptiles,  birds  and  mammals. 

This  same  tendency  is  apparent  even 
in  parasitic  groups  which  are  quite  widely 
distributed.     For  example,  many  reptiles 
and  mammals  (but  not  birds)  have  pin- 
worms  of  the  family  Oxyuridae,  but  each 
group  has  its  own  genera.    Iguanas  have 
Ozolaimus  and  Macrae  is,  other  reptiles 
have  Thelandros ,  Pharyngodon  and  sev- 
eral other  genera,   rodents  have  Asfiicu- 
liiris,   Syphacia  and  Wellcomia,   rabbits 
have  Passalurus,  equids  have  Oxyuris, 


ruminants  have  Skrjabinema,    and  man  and 
other  primates  have  Enlerobius . 

On  the  other  hand,  there  are  many 
exceptions  to  this  general  rule,   and  it 
cannot  be  used  without  corroboration  as 
the  sole  criterion  of  host  relationship. 
Many  fish-eating  birds  and  mammals  have 
the  same  species  of  trematodes  for  which 
fish  act  as  intermediate  hosts.     And  the 
fact  that  the  pig  and  man  share  a  surpris- 
ing number  of  parasites  is  no  proof  of 
their  close  relationship  despite  their  sim- 
ilarity of  character  and  personality;  it 
simply  reflects  their  omnivorous  habits 
and  close  association. 

Adaptation  to  parasitism:     Adaptation 
to  a  parasitic  existence  has  required  many 
modifications,  both  morphological  and 
physiological.     Locomotion,   at  least  of  the 
parasitic  stages,  has  often  become  re- 
stricted.    Certain  organs  and  organ  sys- 
tems may  be  lost.     Tapeworms  lack  an  in- 
testine altho  their  ancestors  presumably 
had  one,  and  adult  trematodes  have  no  eye- 
spots  altho  their  turbellarian  ancestors 
and  many  of  their  larvae  have  them. 
Parasitic  amoebae  have  no  contractile 
vacuoles  altho  their  free-living  relatives 
do. 

In  contrast,   many  structures  are 
modified  or  hypertrophied  for  the  para- 
sitic life.    Many  helminths  have  hooks  and 
suckers  to  help  them  hold  their  position. 
The  protozoon,  Gianiia,    has  turned  most 
of  its  ventral  surface  into  a  sucking  disc. 
The  mouthparts  of  many  insects  and  mites 
have  become  highly  efficient  instruments 
for  tapping  their  hosts'  blood  supply.    The 
chigger,  which  does  not  suck  blood,  has 
developed  a  method  of  liquefying  its  hosts' 
tissues.    The  food  storage  organs  of  many 
parasites  have  been  enlarged.     Many  blood- 
sucking arthropods  which  are  unable  to  ob- 
tain all  the  nutrients  they  need  from  blood, 
have  established  symbiotic  relationships 
with  various  microorganisms  and  have 
formed  special  organs  for  them. 

The  reproductive  system  of  many 
parasites  has  been  hypertrophied  to  pro- 
duce tremendous  numbers  of  eggs.    Other 
parasites,  such  as  the  trematodes,  have 


INTRODUCTION  TO  PARASITOLOGY 


11 


developed  life  cycles  in  which  the  larvae 
also  multiply. 

In  the  parasites  with  high  reproduc- 
tive rates,   infection  is  left  largely  to 
chance.     Many  other  parasites,  however, 
have  developed  life  cycles  in  which  chance 
is  more  or  less  eliminated.    In  these,  the 
reproductive  rate  is  low.     The  larva  of 
the  sheep  ked,   Melophagns  ovinus,  devel- 
ops to  maturity  in  the  body  of  its  mother 
and  pupates  immediately  after  emerging. 
The  pupa  remains  in  its  host's  wool.     The 
female  tsetse  fly,  too,   produces  fully  de- 
veloped larvae.    The  tropical  American 
botfly,  Derinaiobia  honiinis,    captures  a 
mosquito  and  lays  her  eggs  on  it.     These 
hatch  when  the  mosquito  lights  to  suck 
blood,  and  the  larvae  enter  the  host. 

Morphological  and  developmental 
modifications  are  the  most  obvious  ones, 
but  biochemical  ones  are  even  more  im- 
portant.    How  do  parasites  survive  in 
their  hosts  without  destruction?    What 
keeps  those  which  live  in  the  intestine 
from  being  digested  along  with  the  host's 
food?    Why  is  it  that  morphologically  sim- 
ilar species  are  restricted  to  different 
hosts  which  themselves  may  be  morpho- 
logically quite  similar? 

The  second  question  has  been  an- 
swered by  saying  that  the  same  mecha- 
nism operates  which  prevents  the  hosts 
from  digesting  themselves,  that  the  para- 
sites protect  themselves  by  producing 
mucus  or  that  mucoproteins  in  their  in- 
tegument protect  them,  that  they  secrete 
antienzymes,  or  that  the  surface  mem- 
brane of  living  organisms  is  impermeable 
to  proteolytic  enzymes.     However,  much 
more  research  must  be  done  before  a 
satisfactory  answer  can  be  given.     An- 
swers given  to  the  first  and  third  ques- 
tions are  vague.    Compatibility  of  host 
and  parasite  protoplasm  is  invoked,  but 
all  this  does  is  put  a  name  to  the  beast. 
The  question  of  how  this  compatibility  is 
brought  about  remains  unanswered,  and  a 
great  deal  of  biochemical  and  immuno- 
chemical research  must  be  done  before  it 
can  be  answered  (see  Becker,  1953;  Read, 
1950;  von  Brand,  1952). 


Injurious  effects  of  parasites  on  their 
hosts.      Parasites  may  injure  their  hosts 
in  several  ways: 

1.  They  may  suck  blood  (mosquitoes, 
hookworms),   lymph  (midges)  or  exu- 
dates (lungworms). 

2.  They  may  feed  on  solid  tissues,  either 
directly  (giant  kidney  worms,  liver 
flukes)  or  after  first  liquefying  them 
(chiggers). 

3.  They  may  compete  with  the  host  for 
the  food  it  has  ingested,   either  by  in- 
gesting the  intestinal  contents  (asca- 
rids)  or  by  absorbing  them  thru  the 
body  wall  (tapeworms).    In  some  cases 
they  may  take  up  large  amounts  of  cer- 
tain vitamins  selectively,  as  the  broad 
fish  tapeworm  does  with  Vitamin  B12. 

4.  They  may  cause  mechanical  obstruc- 
tion of  the  intestine  (ascarids),  bile 
ducts  (ascarids,  fringed  tapeworm), 
blood  vessels  (dog  heartworm),  lymph- 
atics (filariids),  bronchi  (lungworms) 
or  other  body  channels. 

5.  They  may  cause  pressure  atrophy 
(hydatid  cysts). 

6.  They  may  destroy  host  cells  by  grow- 
ing in  them  (coccidia,  malaria  para- 
sites). 

7.  They  may  produce  various  toxic  sub- 
stances such  as  hemolysins,  histoly- 
sins,  anticoagulants,  and  toxic  prod- 
ucts of  metabolism. 

8.  They  may  cause  allergic  reactions. 

9.  They  may  cause  various  host  reac- 
tions such  as  inflammation,  hyper- 
trophy, hyperplasia,  nodule  forma- 
tion, etc. 

10.  They  may  carry  diseases  and  para- 
sites, including  malaria  (mosquitoes), 
trypanosomosis  (tsetse  flies),   swine 
influenza  (lungworms),   salmon  poison- 
ing of  dogs  (flukes),   heartworms  (mos- 
quitoes) and  onchocercosis  (blackflies). 

11.  They  may  reduce  their  hosts'  resis- 
tance to  other  diseases  and  parasites. 

A  great  deal  more  could  be  said  about 
this  subject.     Additional  information  is 
given  in  the  symposium  on  mechanisms  of 
microbial  pathogenicity  of  the  Society  for 
General  Microbiology  (Howie  and  O'Hea, 
1955). 


12 


INTRODUCTION  TO  PARASITOLOGY 


Resistance  and  Immunity  to  Para- 
sites.     This  is  such  a  tremendous  sub- 
ject that  its  facets  can  only  be  hinted  at. 
The  general  principles  of  immunology 
apply  to  animal  parasites  as  much  as  they 
do  to  bacteria,  viruses  and  other  micro- 
organisms.    However,  since  the  associ- 
ation of  many  of  the  larger  parasites  with 
their  hosts  is  not  as  intimate  as  that  of 
microorganisms,  the  hosts'  immune  res- 
ponses may  not  be  as  great.     This  is 
especially  true  with  regard  to  the  forma- 
tion of  circulating  antibodies. 

Immunity  or  resistance  may  be  either 
natural  {innate)  or  acquired.     Natural  re- 
sistance is  the  basis  of  host-parasite 
specificity,  but,  as  mentioned  above, 
little  is  known  of  its  mechanism.    Ac- 
quired immunity  may  be  either  active  or 
passive.     Active  immunity  results  from 
the  body's  own  action.    It  follows  expo- 
sure to  living  or  dead  disease  agents,  and 
can  result  from  natural  infection  or  arti- 
ficial administration  of  virulent,  attenu- 
ated or  killed  organisms. 

One  type  of  active  immunity  is  pre- 
munition.     This  is  immunity  due  to  the 
continued  presence  of  the  disease  agent. 
It  occurs  in  such  diseases  as  babesiosis 
and  anaplasmosis. 

Passive  immunity  results  from  the 
introduction  of  antibodies  produced  by 
some  other  animal.    It  may  be  acquired 
naturally,  thru  the  colostrum  or  milk  in 
mammals  or  thru  the  egg  yolk  in  birds, 
or  artificially  by  injection  of  antiserum. 
Passive  immunity  is  seldom  as  long- 
lasting  as  active  immunity. 

Immunity  against  parasites  and  dis- 
ease agents  generally  increases  with  age. 
There  are  exceptions,  however.    Young 
cattle,  for  instance,  are  more  resistant 
to  Babesia  and  Anaplasnia  than  are  adults. 
Age  immunity  may  be  either  developed  as 
the  result  of  previous  exposure  or  it  may 
be  natural.     Not  all  the  factors  operating 
in  the  latter  case  are  known.     An  impor- 
tant one  is  that  very  young  animals  can- 
not mobilize  their  body  defenses  against 
invasion  as  efficiently  as  adults.     For  in- 
stance, they  do  not  produce  antibodies  at 


first,  depending  on  those  acquired  from 
their  mothers.     Another  factor,  discov- 
ered by  Ackert  and  his  co-workers  (cf. 
Ackert,   Edgar  and  Frick,   1939)  to  explain 
the  relative  resistance  of  older  chickens 
to  Ascaridia  galli,  is  that  these  birds  have 
more  intestinal  goblet  cells  than  do  young 
birds.     The  goblet  cells  secrete  mucus 
which  inhibits  the  development  of  the 
worms.     For  further  information  on  im- 
munity in  parasitic  infections,   see  Talia- 
ferro (1929),   Culbertson  (1941)  and  Soul- 
sby  (1960). 

Genetic  constitution  is  also  important 
in  determining  resistance  to  parasites. 
For  instance,  Ackert  el  al.     (1935)  showed 
that  Rhode  Island  Red  and  Plymouth  Rock 
chickens  are  more  resistant  to  Ascaridia 
galli  than  are  Buff  Orpingtons,   Minorcas 
and  White  Leghorns.     Cameron  (1935) 
found  that  in  a  mixed  flock  of  sheep.  Chev- 
iots were  less  heavily  parasitized  with 
gastrointestinal  nematodes  than  Shetlands 
and  Scottish  Blackface,  and  that  these  in 
turn  were  less  heavily  parasitized  than 
Border  Leicesters.     Stewart,  Miller  and 
Douglas  (1937)  found  that  Romney  sheep 
were  markedly  resistant  to  infection  with 
Ostertagia  circunicincta.   while  Rambouil- 
lets  were  less  so  and  Southdowns,  Shrop- 
shires  and  Hampshires  were  least  resist- 
ant.    Certain  individuals  among  the  more 
susceptible  breeds,  however,  were  just  as 
resistant  as  the  Romneys.    Whitlock(1958) 
has  studied  genetic  resistance  to  tricho- 
strongylidosis  in  sheep  in  some  detail. 

The  nutritional  status  of  the  host  may 
affect  its  resistance.     Poorly  nourished 
animals  are  usually  more  susceptible  to 
infection  and  suffer  more  severely  from 
its  effects.     Protein  depletion  or  protein 
starvation  is  particularly  important. 
Lack  of  specific  vitamins  and  minerals 
generally  decreases  resistance,  but  there 
are  cases  in  which  lack  of  a  certain  vita- 
min which  the  parasite  requires  may  af- 
fect the  parasite  adversely.     Thus,  Becker 
and  Smith  (1942)  found  that  when  calcium 
pantothenate  was  added  to  a  ration  con- 
taining restricted  vitamins  B,,   Bg  and  pan- 
tothenate, the  number  of  oocysts  produced 
hy  Einteria  nieschulzi  infections  in  the  rat 
was  increased. 


INTRODUCTION   TO  PARASITOLOGY 


13 


Geographic  Distribution.      Some  para- 
sites, particularly  those  of  man  and  his 
domestic  animals,  are  worldwide  in  dis- 
tribution, but  others  are  much  more  re- 
stricted.    But  even  a  widely  distributed 
species  may  be  much  more  prevalent  in 
one  region  than  another.     Many  factors 
are  responsible,   some  of  which  have  al- 
ready been  discussed  (pp.   7-8).     A  para- 
site which  originated  in  a  particular  place 
in  a  particular  host  species  may  never 
have  been  introduced  into  some  other  lo- 
cality or  host  where  it  could  develop  per- 
fectly well.    It  may  have  been  introduced 
but  may  have  died  out  because  a  suitable 
vector  was  lacking  or  because  the  climate 
was  not  suitable.    The  ox  warble  has  not 
been  able  to  establish  itself  in  the  south- 
ern hemisphere  because  the  reversal  of 
seasons  has  prevented  it  from  completing 
its  life  cycle. 

Whenever  domestic  animals  are  in- 
troduced into  a  new  region,  there  is  a 
good  possibility  that  they  will  pick  up 
some  of  the  parasites  of  their  wild  rela- 
tives there.     The  parasite  spectrum  of 
cattle  in  Africa  differs  from  that  in  North 
America,  both  of  these  differ  from  the 
spectrum  in  Europe,  and  all  three  differ 
from  the  spectrum  in  Australia.    Wild 
animals,  too,  may  acquire  parasites 
from  domestic  ones  or  from  other  wild 
species.    Hence,  the  parasite  spectrum 
of  animals  in  zoos  may  be  quite  different 
from  that  in  their  normal  habitat,   and  the 
success  of  an  attempt  to  introduce  a  new 
game  bird  or  mammal  into  a  region  may 
depend  in  part  on  the  parasites  and  dis- 
eases that  it  encounters. 

The  importance  of  wildlife  as  a  para- 
site reservoir  for  domestic  animals  is 
well  illustrated  by  the  report  of  Longhurst 
and  Douglas  (1953)  on  the  interrelation- 
ships between  the  parasites  of  domestic 
sheep  and  Columbian  black-tailed  deer  in 
the  north  coastal  part  of  California, 
where  the  two  live  on  the  same  range. 
They  found  in  their  survey  of  63  sheep 
and  81  deer  that  1  species  of  trematode, 
5  of  cestodes,  and  13  out  of  18  species 
of  nematodes  were  common  to  both 
hosts. 


Origin  of  Parasitism.      Parasites 
originated  from  free-living  ancestors. 
The  process  probably  began  soon  after 
the  first  living  forms  appeared.    The 
change  from  a  free-living  to  a  parasitic 
habitat  has  taken  place  many  times  in  the 
course  of  evolution.    It  has  occurred  as 
new  major  groups  appeared,  it  has  taken 
place  independently  many  times  in  each 
group,   and  it  is  undoubtedly  still  occur- 
ring.   Once  established,  the  parasites 
evolved  along  with  their  hosts. 

In  some  cases,  the  parasites  first 
invaded  the  host  thru  the  integument,  like 
Pelodera  and  related  rhabditid  nematodes. 
In  other  cases,  the  parasites  were  swal- 
lowed along  with  their  host's  food.     Para- 
sites with  life  cycles  involving  two  or 
more  hosts  became  established  first  in 
one  host,  and  later  on  developed  their 
more  complicated  life  cycles.     The  try- 
panosomes,  for  instance,  were  originally 
gut  parasites  of  insects  and  only  later  be- 
came blood  parasites  of  vertebrates. 

Preadaptation  was  necessary  for 
parasites  to  become  established.    They 
must  have  had  the  ability  to  survive  and 
reproduce  in  the  host  before  they  entered 
it.     By  far  the  great  majority  of  free-liv- 
ing forms  which  entered  the  alimentary 
canal  of  some  larger  animal  were  killed 
and  digested,  but  some  of  them  were  able 
to  resist  this  process  and  a  few  were  able 
to  live  there.    Some  of  the  factors  involved 
have  already  been  discussed  (p.  10). 

Economic  Importance.      Parasites 
are  responsible  for  heavy  economic  losses 
to  the  livestock  industry.     These  are  due 
in  part  to  death,  but  even  more  important 
are  the  losses  due  to  illness,   reduced 
growth  rate,  decreased  meat,  milk,   egg 
and  wool  production  and,  in  working  ani- 
mals, loss  of  working  energy.    It  is  im- 
possible to  quantitate  these  losses  accu- 
rately, but  rough  estimates  can  be  made. 
The  U.  S.  Department  of  Agriculture 
(1954)  made  such  an  estimate  for  losses 
in  agriculture  during  the  ten-year  period, 
1942-1951.    The  figures  on  parasite  losses 
in  Table  1  are  taken  from  this  publication. 
Further  details  are  given  in  the  publication 
itself  and  by  Schwartz  et  al.  (1955). 


14 


INTRODUCTION  TO  PARASITOLOGY 


TABLE  1 

ANNUAL  LOSSES   DUE  TO  PARASITES   OF 

LIVESTOCK  IN  THE  U.S.,    1942-1951 

(from  USDA,    1954) 


Class  of 
Livestock 

Average  Annual 
Value  of 
Production 

Annual  Losses 

DoUais 

%  of 
Production 

Cottle 

Sheep 

Goats 

Swine 

Hoises  and 
Mules 

Poultry 

All  Livestock 
(screw-worms 
only) 

$3,431,539,000 

404,  162,  000 

16,375,000 

3,473,817,000 

835,  852,  000* 
3,  149,  002,  000 

$420,  658,  000 

64,  626,  000 

1,  886,  000 

279,  826,  000 

26,  320,  000 
126,532,000 

20,  000,  000 

12.3 

16.0 

11.5 

8.1 

3.1 
4.0 

TOTAL 

$11,310,747,000 

$939,  848,  000 

8.3 

♦Average  annual  value  of  animals. 


Parasites  caused  an  estimated  loss  of 
$939,  848,  000  per  year.     All  other  dis- 
eases, both  infectious  and  nutritional,  were 
estimated  to  cause  a  total  annual  loss  of 
$1,748,  594,000,   so  parasites  are  consid- 
ered to  be  responsible  for  about  35%  of  the 
losses  in  the  American  livestock  industry. 
A  billion  dollars  a  year  is  a  sizeable  fig- 
ure.   We  can  hardly  expect  to  eliminate 
this  loss  completely,  but  if  every  animal 
owner  took  advantage  of  our  present  know- 
ledge, a  half  billion  dollars  a  year,  or 
even  more,  could  be  saved. 

Scientific  Names.      There  are  several 
million  species  of  animals  in  the  world. 
Many  of  them  are  well  enough  known  and 
easy  enough  to  recognize  to  have  received 
common  names.     However,  these  names 
vary  from  one  language  to  another  and 
from  one  locality  to  another  among  people 
who  speak  the  same  language.     Further- 
more, the  same  common  name  is  often 
applied  to  different  species  in  different 
regions. 

In  the  United  States,  "cattle"  refers 
to  the  ox.   Box  laiirus,  but  in  India  it  re- 
fers to  the  zebu.   Bus  indiciis,  and  in  Eng- 
land and  some  other  countries  (and  in  the 


Bible)  to  domestic  livestock  in  general. 
"Fowl"  has  more  than  one  meaning.    It 
may  refer  to  the  chicken,    Gallns  domesti- 
cus,   but  it  may  refer  to  any  bird  raised 
for  food,  including  the  turkey,   Meleagris 
gallopavo ,   and  ducks.     Most  domestic  ducks 
are  Anas  platyrhynchos,   but  the  Muscovy 
duck  is  Cairina  moschata.    One  of  the  worst 
offenders  is  "rabbit"  which  is  applied  in- 
discriminately to  many  quite  different  spe- 
cies.    Rabbits  are  not  rodents,  but  lago- 
morphs;  they  have  four  upper  incisors, 
whereas  rodents  have  only  two.     The  do- 
mestic rabbit  is  the  common  wild  rabbit  of 
Europe,   Oryctolagus  cunicitlus.     The  com- 
mon wild  rabbit  of  North  America,   however, 
is  the  cottontail,  Sylvilagiis,   of  which  there 
are  13  species.    In  addition,  there  are  sev- 
eral species  of  jack  rabbits  belonging  to  the 
genus  Lepiis.     A  list  of  scientific  names  of 
domestic  and  common  wild  animals  is  given 
in  Appendix  I. 

In  order  to  prevent  the  confusion  which 
would  be  inevitable  in  dealing  with  these 
myriad  species,   a  system  of  scientific 
names  has  been  worked  out.    This  system 
was  first  established  by  Linnaeus  in  the 
eighteenth  century,   and  the  starting  point 
for  the  names  of  animals  is  the  tenth  edition 
of  Linnaeus'  Syste»ia  Naturae,  which  was 
published  in  1758.     An  International  Code  of 
Zoological  Nomenclature  was  adopted  in 
1904;  it  was  reviewed  at  a  colloquium  held 
in  Copenhagen  in  1953,  and  a  new,  revised 
code  was  adopted  by  another  colloquium 
held  in  London  in  1958.    This  code  estab- 
lishes rules  for  naming  animal  species  and 
for  indicating  their  relationships. 

In  the  system  of  binomial  nomenclature 
used  for  scientific  names,  each  species  is 
given  two  names.    The  first  name,  which 
is  capitalized,  is  used  for  a  group  of  closely 
related  species;  this  group  is  called  a 
and  its  name  is  the  generic  name.    The  sec- 
ond name,  which  is  not  capitalized,  is  used 
for  a  single  species  within  the  genus  and  is 
called  the  specific  name.     A  particular  gen- 
eric name  can  be  used  for  only  a  single 
group  of  species  in  the  animal  kingdom,  but 
the  same  specific  name  can  be  applied  to 
species  in  different  genera.     The  generic 
and  specific  names  are  often  derived  from 
Latin  or  Greek,  but  they  may  also  be  based 


INTRODUCTION  TO  PARASITOLOGY 


15 


on  the  names  of  persons,   geographic  lo- 
calities, etc.     They  must,   however,   have 
latinized  endings.     Both  names  are  writ- 
ten in  italics. 

The  name  of  the  person  who  first 
named  each  species  and  the  date  when  he 
did  it  are  also  part  of  its  scientific  name, 
altho  these  are  often  omitted  in  non-taxo- 
nomic  writing.    If  the  namer  assigned  the 
species  to  a  different  genus  from  the  one 
which  is  accepted  as  correct,  then  his 
name  and  date  are  enclosed  in  parentheses 
and  are  followed  outside  the  parentheses 
by  the  name  of  the  person  who  assigned 
the  species  to  its  present  genus  with  the 
date  when  he  did  it.    If  there  has  been  no 
change  in  the  genus  designated  by  the  or- 
iginal author,   parentheses  are  not  used. 
Thus,  the  common  large  roundworm  of  the 
dog,    Toxocara  canis,  was  first  described 
by  Werner  in  1782,  but  he  assigned  it  to 
the  same  genus  as  the  earthworm,   Lum- 
bricus.     In  1905,  Stiles  established  a  new 
genus,   Toxocara,   for  this  species.    The 
original  name,  then,  was  Lumbricus  canis 
Werner,  1782,  and  the  presently  accepted 
name  is   Toxocara  canis  (Werner,   1782) 
Stiles,   1905.     Similarly,  in  the  early  days 
of  parasitology  almost  all  tapeworms  were 
assigned  to  a  single  genus,    Taenia.    As 
knowledge  increased,  more  and  more  gen- 
era were  split  off  from  it.     The  common 
sheep  tapeworm  was  called  Taenia  expansa 
by  Rudolphi  in  1805,  but  in  1891  Blanchard 
established  a  new  genus,  Moniezia,   for  it, 
so  that  its  correct  name  is  now  Moniezia 
expansa  (Rudolphi,   1805)  Blanchard,   1891. 

Genera  are  grouped  together  into 
families,  families  are  grouped  into  orders, 
orders  into  classes,  and  classes  into  phyla. 
Each  of  these  categories,  and  also  each  of 
the  lower  ones,  is  known  as  a  taxon  (pi. , 
taxa).    Subfamilies  and  superfamilies,  sub- 
orders and  superorders,   etc.   are  often 
used,  and  in  some  cases  so  many  relation- 
ship levels  are  recognized  that  it  is  neces- 
sary to  introduce  cohorts,  tribes,  etc. 

Each  family  is  based  on  one  of  its 
genera,  known  as  the  type  genus,  and  the 
name  of  the  family  is  obtained  by  attach- 
ing the  ending,  -idae,  to  the  root  of  the 
name  of  the  genus.    Thus,  Strongylus  be- 


longs to  the  family  Strongylidae,  and 
Trichomonas  to  the  family  Trichomonad- 
idae.     The  subfamily  ending  is  -inae. 

While  the  botanists  long  ago  adopted 
a  system  of  uniform  endings  for  the  names 
of  their  higher  taxa,  the  zoologists  have 
never  been  able  to  agree  on  one.     As  a 
consequence,  it  is  impossible  to  determine 
the  ranks  of  the  higher  taxa  with  certainty 
from  their  names.    In  the  present  book, 
however,  the  system  of  uniform  endings 
proposed  by  Levine  (1959)  is  used,   so  this 
problem  does  not  arise.    These  are: 
Superclass,   -asica;  Class,   -asida;  Sub- 
class,  -asina;  Superorder,   -orica;  Order, 
-orida;  Suborder,   -orina;  Supercohort, 
-icohica;  Cohort,   -icohida;  Subcohort, 
-icohina;  Superfamily,   -icae;  Family, 
-idae;  Subfamily,   -inae;  Supertribe, 
-ibica;  Tribe,   -ibida;  Subtribe,   -ibina. 

Many  scientific  names  appear  quite 
formidable  at  first  glance.    They  have  def- 
inite meanings,  however,   and  it  helps  in 
remembering  them  to  know  what  these 
meanings  are.    Since  most  scientific  names 
are  based  on  Latin  or  Greek,  a  knowledge 
of  some  of  the  descriptive  words  from 
these  languages  is  helpful.     Much  informa- 
tion can  be  obtained  from  a  dictionary  of 
derivations  such  as  that  of  Jaeger  (1955). 
The  thorny -headed  worm  of  swine  is 
MacracantJiorhynchus  hirudinaceus.     This 
name  is  derived  from  the  Greek.     The  gen- 
eric name  means  "large  {macr-)  thorny 
{acantho-)  proboscis  {-rhynchus)."    The 
specific  name  is  derived  from  the  scien- 
tific name  of  the  leech  (Hirudo)  and  means 
"leechlike";  it  was  given  because  the  worm 
is  firmly  attached  to  the  intestinal  wall  and 
looks  vaguely  like  a  leech.    The  name  of 
the  whipworm,    Trichuris,  commemorates 
an  error.    This  nematode  looks  a  good 
deal  like  a  buggy-whip,  with  a  sturdy  body 
and  a  long,  whip-like  anterior  end  about  as 
thick  as  a  hair.    T''       .  ne,  however, 
means  hair-tail  an  '  "tir-head.     This 

mistake  was  so  offe.  some  scien- 

tists that  they  propos     .  to  substitute 
Trichocephaliis  for  j.richuris.     This  is 
not  permissible  according  to  the  rule  of 
priority  of  the  International  Code  of  Zoo- 
logical Nomenclature,  so  the  error  re- 
mains. 


16 


INTRODUCTICN  TO  PARASITOLOGY 


It  is  often  discouraging  to  students 
and  scientists  alike  to  see  the  many 
changes  in  scientific  names  which  continue 
to  be  made.    These,  however,  appear  to 
be  inevitable.     As  new  knowledge  is 
gained,   some  species  must  be  split  up, 
others  recombined  and  still  others  shifted 
from  one  genus  to  another.     It  is  some- 
times found  that  a  name  which  has  been 
long  used  and  accepted  must  be  dropped 
in  favor  of  an  unfamiliar  one,  either  be- 
cause it  had  been  used  first  for  some  other 
species  or  because  the  less  familiar  name 
had  been  given  earlier  but  overlooked. 

Another  reason  for  these  changes  lies 
in  human  nature  itself.     No  satisfactory 
criteria  have  ever  been  established  for 
the  definition  of  species,   and  some  taxo- 
nomists  go  into  finer  differences  than 
others  in  separating  them. 

The  taxonomists'  difficulties  arise 
because  what  they  are  dealing  with  are 
individual  organisms,  and  all  taxonomic 
schemes  are  the  result  of  man's  attempts 
to  arrange  these  individuals  in  a  system 
which  shows  their  relationships.     All 
taxa,  whether  species,   subspecies,  gen- 
era, families  or  whatnot,   are  products 
of  this  abstraction  process  and  have  no 
real  existence  outside  the  human  mind. 
Many  taxonomists,   however,   refuse  to 
accept  this  idea,  believing  that  species 
are  real  and  external,  and  that  their  task 
is  simply  to  discover  and  differentiate 
them.    It  is  easy  to  understand  why  they 
do  not  like  to  believe  that  they  are  devot- 
ing their  lives  to  figments  of  the  imagin- 
ation. 

Without  the  labors  of  the  systema- 
tists  we  should  be  in  a  state  of  hopeless 
confusion.    Their  scientific  names  and 
their  taxonomic  schemes  are  absolutely 
necessary  if  we  are  to  carry  out  repro- 
ducible experimental  work  or  understand 
practically  all  biological  phenomena. 


Becker,    E.    R.   and  L.   Smith.     1942.     Iowa  St.  Col.  ).   Sci. 

16:443-449. 
von  Brand,    T.     1952.     Chemical  physiology  of  endoparasitic 

animals.    Academic  Press,  New  York. 
Buchner,   P.     1953.     Endosymbiose  der  Tiere  mit  pflanzlichen 

Mikroorganismen.     Birkhauser,   Basel/Stuttgart. 
Cameron,   T.   W.  M.     1935.     Proc.    12th  Intern.   Vet.   Congr. 

3:44-62. 
Culbeitson,  J.   T.     1941.     Immunity  against  animal  parasites. 

Columbia  Univ.  Press,   New  York. 
Dawes,   B.     1956.     The  Trematoda.     Cambridge  Univ.  Press, 

Cambridge,   England. 
Elton,   C.     1935.     Animal  ecology.     Macmillan,   New  York. 
Gamham,    P.   C.   C.     1958.     ].   Trop.  Med.  Hyg.   61:92-94. 
Gordon,   H.  M.     1957.     Adv.  Vet.  Sci.   3:287-351. 
Hoare,   C.  A.    1955.     Refuah  Vet.    12:258-263. 
Howie,   J.  W.   and  A.  ].   O'Hea,    eds.     1955.     Mechanisms 

of  microbial  pathogenicity.     Fifth  symposium  of  the 

Society  for  General  Microbiology  held  at  the  Royal  In- 
stitution,  London,   April  1955.     Cambridge  Univ.   Press, 

Cambridge,    England. 
Jaeger,    E.   C.     1955.     A  source -book  of  biological  names 

and  terms.     3rd  ed.     Thomas,   Springfield,    Illinois. 
Kelley,    G.   W.   and  L.  J.   Smith.     1956.    J.  Pamsit.     42:587. 
Koch.   A.     1956.     Exper.   Parasit.     5:481-518. 
Levine,    N.   D.     1959(1958).     System.  Zool.     7:134-135. 
Longhuret,   W.  M.  and  ].   R.  Douglas.      1953.     Trans.  N.  Am. 

Wildlife  Conf.     18:168-187. 
Muller,    S.  W.  and  A.  Campbell.     1954.     Syst.   Zool. 

3:168-170. 
Pavlovsky,    Y.  N.     1957.     Natural  nidality  of  disease  in  re- 
lation to  the  ecology  of  the  zoonoses.     WHO  Regional 

office  for  Europe,    Seminar  on  Veterinary  Public  Health. 

EURO-85. 2/20  Rev.    1,    pp.    30. 
Read,    C.   P.,   Jr.     1950.   Rice  Inst.   Pamph.   37(2):l-94. 
Schwartz,   B.    et  al.     1955.     Proc.   U.  S.   Livestock  San. 

Assoc.    58:303-308. 
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J.  Ag.    Res.    55:923-930. 
Taliaferro,   W.  H.     1929.     The  immunology  of  parasitic 

infections.     Century,   New  York. 
U.   S.   Dept.   of  Agriculture.     1954.     Losses  in  agriculture. 

A  preliminary  appraisal  for  review.     USDA    Agr.   Res. 

Serv.  ARS-20-1,   Washington,    D.   C. 
Wardle,    R.  A.  and  J.   A.  McLeod.     1952.     The  zoology  of 

tapeworms.     Univ.   of  Minnesota  Press,   Minneapolis. 
Whitlock,  J.  H.     1955.    Proc.  Am.  Vet.  Med.  Assoc. 

92:123-131. 
Whitlock,   J.   H.     1958.     Cornell  Vet.  48:127-133. 
World  Health  Organization.     1959.    Joint  WHO/FAO  Expert 

Committee  on  Zoonoses.     Second  Report.     Tech.   Rep. 

Ser.  No.    169,    Geneva,     pp.   83. 


GENERAL  REFERENCES 


CHAPTER   REFERENCES 

Ackert,    J.    E.  ,   S.  A.   Edgar  and  L.   P.   Frick.    1939.     Trans. 

Am.   Micr.  Soc.    58:81-89. 
Ackert,   J.   E.  ,   L.   L.   Eisenbrondt,  J.   H.   Willmoth,   B. 

Glading  and  I.   Pratt.    1935.    J.  Agr.   Res.   50:607-624. 
Becker,    E.   R.     1953.     J.   Parasit.   39:467-480. 
Becker,    E.    R.     1956.     Iowa  St.  Col.  J.  Sci.   31:85-139. 


The  following  general  references  are  a  supple- 
ment to  the  chapter  references  given  above, 
some  of  which  are  also  general  in  nature. 

Antipin,    D.  N.  ,    V.   S.    Ershov,   N.  A.   Zolotarev  and  V.  A. 
Salycev.     1959.     Parasitologiya  i  invazionnye  bolezni 
sel'skokhozyaistvennykh  zhivotniykh.     2nd  ed.     Gos.   hdat. 
Sel'skokh.     Liter. ,   Moscow. 


INTRODUCTION  TO  PARASITOLOGY 


17 


Audy,  J.  R.  1958.  The  localization  of  disease  with  special 
reference  to  the  zoonoses.  Trans.  Roy.  Sec.  Trop.  Med. 
Hyg.   52:308-328. 

Baer,   J.   G.     1951.     Ecology  of  animal  parasites.     Univ.   of 
111.   Press,    Urbana. 

Baer,   J.    G. ,    ed.     1957.     First  symposium  on  host  specificity 
among  parasites  of  vertebrates.     Univ.   Neuchatel,    Swit- 
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Baker,    E.   W.  ,   T.  M.   Evans,    D.   J.    Gould,   W.  B.   Hull  and 
H.  L.   Keegan.     1956.     A  manual  of  parasitic  mites  of 
medical  or  economic  importance.     Nat.   Pest  Control 
Assoc. ,    New  York. 

Baker,    E.   W.  and  G.  W.   Wharton.     1952.     An  introduction 
to  acorology.     Macmillan,   New  York. 

Ball,  G.  H.  1943.  Parasitism  and  evolution.  Am.  Natur- 
alist 78:345-364. 

Becker,    E.   R.     1933.     Host  specificity  and  specificity  of 
animal  parasites.    Am.  J.   Trop.  Med.    13:505-523. 

Belding,  D.  H.  1952.  Textbook  of  clinical  parasitology. 
2nd  ed.     Appleton-Century-Crofts,   New  York. 

Benbrook,    E.  A.     1958.     Outline  of  parasites  reported  for 
domesticated  animals  in  North  America.     5th  ed.     Iowa 
St.   Coll.   Press,   Ames,    Iowa. 

Benbrook,   E.  A.  and  M.   W.  Sloss.     1955.    Veterinary  Clin- 
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Iowa. 

Biester,  H.  E.  and  L.  H.  Schwarte,  eds.  1959.  Diseases  of 
poultry.     4th  ed.     Iowa  State  College  Press,   Ames,    Iowa. 

Borchert,   A.     1958.     Lehrbuch  der  Parasitologie  fur  Tierarzte. 
2nd  ed.     S.  Hirzel,   Leipzig. 

Brumpt,  E.  1949.  Precis  de  parasitologie.  6th  ed.  2  vols. 
Masson  et  Cie.  ,   Paris. 

Cameron,   T.   W.  M.     1952.     The  parasites  of  domestic 
animals.     2nd  ed.     Lippincott,    Philadelphia. 

Cameron,    T.    W.    M.      1956.     Parasites  and  parasitism. 
Wiley,   New  York. 

CauUery,  M.  1950.  Le  parasitisme  et  la  symbiosis.  2nd 
ed.     G.    Doin,   Paris. 

Chandler,  A.  C.  1923.  Speciation  and  host  relationships 
of  parasites.     Parasitol.     15:326-339. 

Chandler,   A.   C.     1948.     Factors  modif>'ing  host  resistance 
to  helminthic  infections.     Proc.  4th  Intern.   Congr.   Trop. 
Med.  Malaria  2(6):975-983. 

Chandler,  A.  C.  1953.  The  relation  of  nutrition  to  para- 
sitism.    J.    Egypt.  Med.  Assoc.     36:533-552. 

Chandler,  A.  C.  1953a.  Immunity  in  parasitic  diseases. 
J.   Egypt.  Med.   Assoc.     36:811-834. 

Chandler,  A.  C.  1955.  Introduction  to  parasitology.  9th 
ed.     Wiley,   New  York. 

Chitwood,    B.   G.   and  M.   B.   Chitwood.     1950.    An  introduc- 
tion to  nematology.     Rev.   ed.     B.   G.  Chitwood,    Balti- 
more,  Md. 

Clunies  Ross,    I.  and  H.  McL.  Gordon.     1936.     The  internal 
parasites  and  parasitic  diseases  of  sheep.    Angus  S  Robert- 
son,  Sydney,   Australia. 

Cole,  W.  H. ,  ed.  1955.  Some  physiological  aspects  and 
consequences  of  parasitism.  Rutgers  Univ.  Press,  New 
Brunswick,    N.  J. 

Faust,  E.  C.  1955.  Animal  agents  and  vectors  of  human 
disease.     Lea  S  Febiger,    Philadelphia. 


Faust,  E.  C,  P.  F.  Russell  and  D.  R.  Lincicome.  1957. 
Craig  and  Faust's  clinical  parasitology.  6th  ed.  Lea  & 
Febiger,   Philadelphia. 

Hall,  M.  C.  1930.  The  wide  field  of  veterinary  parasitol- 
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Herms,  W.  B.  1950.  Medical  entomology.  4th  ed.  Mac- 
millan,  New  York. 

Kotldn,    S.     1953.     Parazitologia.     Mezogazdasagi  Kiado, 
Budapest. 

Lapage,    G.     1951.     Parasitic  animals.     Cambridge  Univ. 
Press,    Cambridge,    England. 

Lapage,   G.     1956.     Veterinary  parasitology.     Charles  C 
Thomas,    Springfield,    111. 

Lapage,  G.  1956.  Monnig's  veterinary  helminthology  and 
entomology.     4th  ed.     Williams  G  Wilkins,     Baltimore. 

Markell,    E.    K.   and  Marietta  Voge.     1958.     Diagnostic 
medical  parasitology.     W.   B.  Saunders,    Philadelphia. 

Martini,    E.  C.   W.     1952.     Lehrbuch  der  medizinischen 
Entomologie.     4th  ed.     G.   Fischer,   Jena. 

Matheson,  R.  1950.  Medical  entomology.  2nd  ed.  Corn- 
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Morgan,  B.  B.  and  P.  A.  Hawkins.  1949.  Veterinary  hel- 
minthology.    Burgess,   Minneapolis. 

Most,  H.  ,  ed.  1951.  Parasitic  infections  in  man.  Colum- 
bia Univ.   Press,   New  York. 

Neveu-Lemaire,   M.     1936.     Traite  d'helminthologie 
medicale  et  veterinaire.     Vigot  Freres,   Paris. 

Newsom,  I.  E.  1952.  Sheep  disease.  Williams  S  Wilkins, 
Baltimore. 

Orlov,  N.  P.  1958.  Veterinamaya  parazitologiya.  Gosud. 
Izdat.     Sel'skokh.     Liter,   Moscow. 

Pearse,  A.  S.  1942.  Introduction  to  parasitology.  Thomas, 
Springfield,    111. 

Reichenow,    E.  ,   H.   Vogel  and  F.   Weyer.     1952.     Leitfaden 
zur  Untersuchung  der  tierischen  Parasiter  des  Menschen 
und  der  Haustiere.     3rd  ed.     J.   A.   Barth,    Leipzig. 

Rothschild,  Miriam  and  Theresa  Clay.  1957.  Fleas,  flukes 
and  cuckoos.  A  study  of  bird  parasites.  2nd  ed.  Collins, 
London. 

Smith,  Theobald.  1934.  Parasitism  and  disease.  Princeton 
Univ.   Press,    Princeton,   N.  J. 

Soulsby,    E.  J.   L.     1960.     Immuirity  to  helminths--recent 
advances.    Vet.   Rec.   72:322-328. 

Strong,  R.  P.  1935.  The  importance  of  ecology  in  relation 
to  disease.     Science  82:307-317. 

Stunkard,  H.  W.  1929.  Parasitism  as  a  biological  phenom- 
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20:469-492. 

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698.     pp.    135. 

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Tindall  and  Cox,    London. 

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pluro)  and  microbial  agents.    Ann.  Rev.  Ent.   5:405-420. 

Whitlock,  J.  H.  1960.  Diagnosis  of  veterinary  parasitisms. 
Lea  &  Febiger,   Philadelphia. 


Chapter  2 


iNTRODUCTION 
TO 

THE  PROTOZOA 


Protozoa  form  the  most  primitive 
group  in  the  animal  kingdom.    The  bodies 
of  all  other  animals  are  composed  of 
many  units,  or  cells,  but  those  of  the 
protozoa  are  a  single  cell.    No  matter 
how  complex  their  bodies  may  be,  and 
many  of  them  are  very  much  so,  all  the 
different  structures  are  contained  in  a 
single  cell.    This  complexity  has  made 
some  investigators  maintain  that,   instead 
of  being  considered  single  cells,  protozoa 
should  be  thought  of  as  non-cellular  (see, 
for  example,   Boyden,   1957).     This  argu- 
ment is  essentially  a  verbal  issue--a 
matter  of  how  one  wants  to  define  "cell.  " 

Protozoa  are  microscopic  in  size, 
only  a  few  being  visible  to  the  naked  eye. 
They  differ  from  the  Metazoa  in  being 
unicellular,  but  this  difference  is  not  as 
clearcut  as  might  be  supposed.     Some 
protozoa  have  a  syncytial  stage  in  their 
life  cycle  in  which  there  are  no  cell  walls 
between  the  nuclei,   and  some  species  form 
colonies  which  swim  as  a  unit  and  which 
contain  somatic  and  reproductive  organ- 
isms which  look  different.     The  difference 
between  these  and  Metazoa  is  again  partly 
a  matter  of  definition,  and  gives  a  clue  to 
how  the  Metazoa  could  have  arisen. 

The  boundary  between  the  Protozoa 
and  certain  one-celled  plants,  too,   is  not 
clearcut.     For  example,  the  whole  group 
of  slime  molds  are  considered  by  proto- 
zoologists  to  be  protozoa  and  assigned  to 
the  order  Mycetozoorida  in  the  class 
Sarcodasida,  but  botanists  consider  them 
fungi  and  assign  them  to  the  class  Myxo- 
mycetes. 

A  still  more  confusing  situation  in- 
volves the  plant-like  protozoa  which  con- 
tain chlorophyll.     Protozoologists  assign 
them  to  the  subclass  Phytomastigasina, 
but  botanists  consider  them  green  algae. 
The  problem  is  that  there  are  many  spe- 
cies of  colorless  protozoa  which  differ 
from  green  ones  only  in  that  they  lack 
chromatophores.     Loss  of  chromatophores 
can  be  produced  experimentally.    It  has 


18  - 


INTRODUCTION  TO  THE  PROTOZOA 


19 


been  done  in  Euglena,  for  instance,  by 
treatment  with  streptomycin  or  simply  by 
growing  the  organisms  at  34  to  35°  C 
(Pringsheim  and  Pringsheim,   1952).    This 
change  of  a  plant  into  an  animal  would  be 
just  as  astounding  as  the  metamorphosis 
of  Cinderella's  pumpkin  into  a  golden 
coach  if  the  differences  between  the  lower 
forms  were  as  great  as  those  between 
higher  plants  and  animals.     However,  the 
principal  difference  is  one  of  nutrition, 
and  many  species  are  quite  plastic,  their 
form  of  nutrition  depending  on  circum- 
stances.   Indeed,  many  of  the  metabolic 
pathways  of  the  phytoflagellate,   Ochro- 
monas  Dialhaniensis,  aside  from  those  in 
which  its  chlorophyll  takes  part,  are  so 
similar  to  those  of  men  that  Hutner  has 
facetiously  called  it  a  humanoid! 

In  recognition  of  this  situation,  Ernst 
Haeckel  proposed  that  the  name  Protista 
be  applied  to  all  single-celled  organisms 
and  that  the  group  be  considered  inter- 
mediate between  the  animal  and  plant 
kingdoms.     Relatively  few  modern  taxon- 
omists  subscribe  to  this  idea,   perhaps 
less  because  of  any  defect  in  the  idea  itself 
than  because  they  have  been  trained  either 
as  botanists  or  zoologists  and  not  as  biol- 
ogists. 

Since  their  discovery  by  Leeuwenhoek, 
some  30,000  species  of  protozoa  have  been 
described.     They  occur  in  practically  all 
habitats  where  life  can  exist  and  are  among 
the  first  links  of  the  food  chain  on  which 
all  higher  life  depends.     Floating  in  the 
plankton  of  tropic  seas,  they  cause  the 
luminous  glow  of  waves  and  ship-wakes. 
Blooming  off  our  coasts,  they  cause  the 
red  tide  which  deposits  windrows  of  dead 
fish  on  shore.     They  abound  in  ponds  and 
streams  and  in  the  soil.     Their  role  in 
sewage  purification  is  just  beginning  to  be 
understood.    Their  skeletons  cover  the 
ocean  floor  and  form  the  chalk  we  use  in 
classrooms. 

As  parasites,   protozoa  play  a  double 
role.     Malaria  is  still  the  world's  most 
important  disease.     Trypanosomes  have 
interdicted  vast  African  grazing  lands  for 
livestock.     Amoebae  cause  dysentery  in 
man,  and  coccidia  cause  it  in  his  domes- 


tic animals.     But  other  protozoa,   packing 
the  termite's  hind-gut  almost  solidly,  di- 
gest the  cellulose  that  it  eats  and  feed  it 
with  their  wastes  and  dead  bodies.     Fabu- 
lous numbers  of  protozoa  swarm  in  the 
rumen  and  reticulum  of  cattle  and  sheep 
and  in  the  cecum  and  colon  of  the  horse, 
but  their  role  is  still  not  clear. 

In  this  book  we  are  concerned  with  the 
protozoan  parasites  of  domestic  animals. 
Our  understanding  of  these  forms  can  be 
enhanced  by  knowledge  of  the  parasites  of 
other  animals  and  of  free-living  forms. 
For  further  information  on  the  protozoa  in 
general,   reference  is  made  to  Doge'l  (1951), 
Grasse  (1952-53),  Grell  (1956),   Hall  (1953), 
Hyman  (1940),  Kudo  (1954),   Reichenow 
(1949-53)  and  Wenyon  (1926). 


STRUCTURES 

The  structures  of  protozoa  are  not 
referred  to  as  organs  as  in  higher  animals 
but  as  organelles,  organs  being  composed 
of  cells  and  organelles  being  differentiated 
portions  of  a  cell. 

NUCLEI 

Protozoa  contain  one  or  more  nuclei, 
which  may  be  of  several  types.    In  the 
protozoa  other  than  ciliates,  the  nucleus 
is  vesicular,  and  all  the  nuclei  in  the  same 
individual  look  alike.     There  are  two  types 
of  vesicular  nuclei.    In  one  type,  an  endo- 
some  is  present.     The  endosome  is  a  more 
or  less  central  body  with  a  negative  Feul- 
gen  reaction  and  therefore  without  deoxy- 
ribonucleic acid.     The  chromatin,  which 
is  Feulgen  positive  and  which  forms  the 
chromosomes,  lies  between  the  nuclear 
membrane  and  the  endosome.    This  type 
of  nucleus  is  found  in  the  trypanosomes, 
parasitic  amoebae  and  phytoflagellates. 
In  the  other  type  of  vesicular  nucleus, 
there  is  no  endosome,  but  there  may  be 
one  or  more  Feulgen-positive  nucleoli. 
In  these,  the  chromatin  is  distributed  thru- 
out  the  nucleus.     This  type  of  nucleus  is 
found  in  the  Telosporasida,   hypermasti- 
gorid  flagellates,  opalinids,  dinoflagel- 
lates,  and  radiolaria. 


20 


INTRODUCTION  TO  THE  PROTOZOA 


In  the  ciliates  there  are  two  types  of 
nucleus  which  look  different,   and  each 
individual  has  at  least  one  of  each.    The 
niicronucleiis  is  relatively  small;  it  di- 
vides by  mitosis  at  fission  and  apparently 
controls  the  reproductive  functions  of  the 
organism.     The  ))iac  runnel  ens  is  relatively 
large;  it  divides  amitotically  at  fission  and 
apparently  has  to  do  with  the  vegetative 
functions  of  the  organism.     Both  these 
nuclei  appear  quite  homogeneous  in  com- 
position in  contrast  to  the  vesicular  nuclei 
of  other  protozoa. 


LOCOMOTION 

Protozoa  move  by  means  of  flagella, 
cilia  or  pseudopods.     A  flagelhim  is  a 
whip-like  organelle  composed  of  a  central 
axoneme  and  an  outer  sheath.     The  axo- 
neme  arises  from  a  basal  granule  or 
blepharoplast  in  the  cytoplasm.     The  axo- 
neme has  been  shown  by  electron  micro- 
scopy to  be  composed  of  9  peripheral  and 
2  central  fibrils.    In  some  species  a  fla- 
gellum  may  pass  backward  along  the  body, 
being  attached  to  it  along  its  whole  length 
or  at  several  points  to  form  an  nndulating 
membrane.     Flagella  are  found  in  the 
Mastigasida  and  in  the  flagellate  stages  of 
the  Sarcodasida  and  Telosporasida. 

A  cilium  is  an  eyelash-like  organelle 
resembling  a  small  flagellum.    It  has  a 
sheath,  basal  granule  and  axoneme.    In 
Paramecium  and  other  forms,  the  axo- 
neme is  composed  of  9  peripheral  and  2 
central  fibrils.     Cilia  are  found  in  the 
Ciliasida.     The  less  specialized  ciliates 
have  large  numbers  of  cilia  which  are 
arranged  in  rows  and  beat  synchronously. 
In  the  more  specialized  ciliates,  special 
locomotory  organelles  have  been  devel- 
oped by  fusion  of  cilia.    A  cirrus  is  a  tuft 
of  fused  cilia  embedded  in  a  matrix.     A 
membranelle  is  a  more  or  less  triangular 
flap  formed  by  the  fusion  of  two  or  more 
transverse  rows  of  cilia;  membranelles 
are  found  especially  around  the  mouth. 
An  undulating  membrane  (not  to  be  con- 
fused with  the  undulating  membrane  of 
flagellates)  is  formed  by  the  fusion  of  one 
or  more  longitudinal  rows  of  cilia;  they 
occur  in  the  oral  groove  of  some  ciliates. 


A  pseudopod  is  a  temporary  locomo- 
tory organelle  which  can  be  formed  and 
retracted  as  needed.    There  are  four  types 
of  pseudopod.     A  lobopod  is  a  relatively 
broad  pseudopod  with  a  dense  outer  layer 
and  a  more  fluid  inner  zone;  lobopods  are 
found  in  the  amoebae  and  some  flagellates. 
Afilopod  is  a  slender,  hyaline  pseudopod 
which  tapers  from  its  base  to  its  pointed 
tip;  filopods  tend  to  anastomose  and  may 
fuse  locally  to  produce  thin  films  of  cyto- 
plasm; they  contain  no  cytoplasmic  gran- 
ules.    A  tnyxopod  [rhizopod,   reticnlupod) 
is  a  filamentous  pseudopod  with  a  dense 
inner  zone  and  a  more  fluid  outer  layer 
in  which  cytoplasmic  granules  circulate; 
myxopods  branch  and  anastomose  to  form 
complex  networks  which  are  used  for 
trapping  food  and  also  for  locomotion; 
they  are  found  in  the  Foraminiferorida. 
An  axopod  is  a  slender  pseudopod  which 
projects  from  the  body  without  branching 
or  anastomosing;  it  is  composed  of  a  thin 
outer  layer  of  fluid  cytoplasm  and  an  axial 
filament  composed  of  a  fibrillar  tube  con- 
taining a  homogeneous  core;  axopods  are 
found  in  the  Heliozoorida  and  Radiolari- 
orida. 

Locomotion  can  also  be  effected  by 
bending,  snapping  or  twisting  of  the  whole 
body.     A  number  of  protozoa  employ  this 
method. 

There  is  still  another  type  of  locomo- 
tion, gliding,    exemplified  by  Toxoplasma, 
Sarcocystis,    coccidian  merozoites,  greg- 
arines  and  Labyrintlinla,    in  which  the  body 
glides  smoothly  along  without  benefit  of 
any  apparent  locomotor  organelles,  change 
in  shape  or  other  visible  cause.     Kummel 

(1958)  found  by  means  of  electron  micro- 
graphs that  the  outer  surface  of  certain 
gregarines  {Gregarina  cuneata,   G.  poly- 
morpfia,   Beloides  sp.)  is  thrown  into  a 
series  of  deep,  microscopic  folds  which 
he  thought  produce  mucus.     Beneath  these 
folds  in  the  pellicle  are  fibrils  which  he 
thought  contract  to  move  the  organism 
along  a  mucous  track.     Jarosch  (1959) 
thought  that  the  gliding  of  Gregarina, 
Euglena  and  various  single-celled  plants 
is  caused  by  superficial  fibrils  thrusting 
against  extruded  mucus.     Beams  et  at. 

(1959)  found  numerous  ultramicroscopic 


INTRODUCTION  TO  THE  PROTOZOA 


21 


folds  in  the  surface  membrane  and  an 
ultramicro^scopic  network  of  fibrils  about 
50  to  200  A  in  diameter  in  the  ectoplasm 
of  the  trophozoites  of  Gregarina  rigida 
from  the  grasshopper.     They  believed  that 
gliding  is  probably  accomplished  by  move- 
ment of  the  body  surface  in  contact  with 
the  substrate  and  that  the  mucus  which  is 
secreted  may  possibly  provide  a  suitable 
surface  for  locomotion.     Ludvik  (1958) 
observed  superficial,  longitudinal  fibrils 
in  electron  micrographs  of  Sarcocystis 
tenella.    However,  a  definitive  explana- 
tion of  the  mechanism  of  gliding  still 
eludes  us. 


EXCRETORY  ORGANELLES 

Excretion  in  the  Protozoa  is  either 
thru  the  body  wall  or  by  means  of  a  con- 
tractile vacuole  which  may  be  simple  or 
may  be  associated  with  a  system  of  feeder 
canals  or  vacuoles.     Contractile  vacuoles 
are  probably  more  important  as  osmoreg- 
ulatory organelles  than  for  excretion. 
They  maintain  water  balance  by  removing 
excess  water  from  the  cytoplasm  and 
passing  it  out  of  the  body.     They  are  found 
in  fresh-water  protozoa  but  are  absent  in 
most  marine  and  parasitic  protozoa.    How- 
ever, some  of  the  latter,  including  Balan- 
tidiuni  and  trypanosomes,   contain  them. 


ORGANELLES  ASSOCIATED 
WITH  NUTRITION 


OTHER  ORGANELLES 


Nutrition  among  the  protozoa  may  be 
of  several  types.     Rather  elaborate  clas- 
sifications have  been  proposed  by  some 
authors,  but  three  types  are  sufficient  for 
our  purposes.    In  holophytic  nutrition, 
which  is  characteristic  of  the  phytoflagel- 
lates,  carbohydrates  are  synthesized  by 
means  of  chlorophyll  which  is  carried  in 
chroiuatophores ,  which  vary  consider- 
ably in  size,   shape  and  number. 

In  holozoic  nutrition,   particulate  food 
material  is  ingested  thru  a  temporary  or 
permanent  mouth.     A  temporary  mouth  is 
formed  by  amoebae  when  they  engulf  their 
food.     A  permanent  mouth  is  a  cytostome. 
It  may  be  simple  or  it  may  lead  into  a 
cytopharynx.    In  many  ciliates  the  area 
around  the  cytostome  forms  a  peristome, 
and  there  may  be  a  number  of  other  spe- 
cialized structures  associated  with  it. 
Particulate  food  passes  into  a.  food  vacuole 
in  the  cytoplasm,  where  it  is  digested. 
The  indigestible  material  may  be  extruded 
from  the  body  either  thru  a  temporary 
opening  or  thru  a  permanent  cytopyge. 

In  saprozoic  nutrition,  no  specialized 
organelles  are  necessary,  nutrients  being 
absorbed  thru  the  body  wall.  This  type  is 
found  in  many  protozoa,  and  may  be  pres- 
ent along  with  holophytic  or  holozoic  nu- 
trition. 


Protozoa  have  many  other  specialized 
organelles  which  are  found  in  different 
groups.     These  will  be  described  in  the 
appropriate  places  below. 


REPRODUCTION   AND   LIFE   CYCLES 

Reproduction  in  the  Protozoa  may  be 
either  asexual  or  sexual.    The  commonest 
type  of  asexual  reproduction  is  binary 
fission,   i.e.,  each  individual  divides  into 
two.     The  plane  of  fission  is  longitudinal 
in  the  flagellates  and  transverse  in  the 
ciliates.     Cytoplasmic  division  follows 
nuclear  fission  and  separation  of  the 
daughter  nuclei.     Vesicular  nuclei  and 
micronuclei  divide  mitotically;  macronu- 
clei  divide  amitotically. 

Multiple  fission  or  schizogony  is 
found  mostly  in  the  Telosporasida.    In  this 
type  of  fission,  the  nucleus  divides  several 
times  before  the  cytoplasm  divides.     The 
dividing  cell  is  known  as  a  schizont, 
agamont  or  segmenter,  and  the  daughter 
cells  are  merozoites  or  schizozoites. 
Nuclear  division,  again,   is  mitotic. 

A  third  type  of  asexual  division  is 
budding.     In  this  process,  a  small  daugh- 
ter individual  is  separated  off  from  the 


22 


INTRODUCTION  TO  THE  PROTOZOA 


Side  of  the  mother  and  then  grows  to  full 
size. 

Internal  budding  or  endodyogeny  has 
been  described  in  Toxoplasma  and  Bes- 
noitia.    Two  daughter  cells  are  formed 
within  the  mother  cell  and  then  break  out, 
destroying  it  (Goldman,   Carver  and  Sul- 
zer,  1958). 

Several  types  of  sexual  reproduction 
have  been  described,  but  only  two  occur 
in  parasitic  protozoa.    In  conjugation, 
which  is  found  among  the  ciliates,  two  in- 
dividuals come  together  temporarily  and 
fuse  along  part  of  their  length.     Their 
macronuclei  degenerate,  their  micronu- 
clei  divide  a  number  of  times,  and  one  of 
the  resultant  haploid  pronuclei  passes 
from  each  conjugant  into  the  other.    The 
conjugants  then  separate,  and  nuclear  re- 
organization takes  place. 

In  syngamy,  two  gametes  fuse  to  form 
a  zygote.    If  the  gametes  are  similar  in 
appearance,  the  process  is  called  isogamy; 
if  they  are  different,  it  is  anisogamy,  the 
smaller  gamete  being  the  microgamete 
and  the  larger  one  the  macrogamete.    The 
gametes  may  be  produced  by  special  cells, 
the  microgametocytes  and  macrogamet- 
ocytes,    respectively.    These  are  also 
sometimes  called  gamonts.    The  zygote 
may  or  may  not  then  divide  by  multiple 
fission  to  form  a  number  of  sporozoites. 
The  process  of  gamete  formation  is  known 
as  gametogony.    It  may  differ  in  different 
groups,  and  will  be  described  in  the  ap- 
propriate places  below. 

Some  protozoa  form  resistant  cysts 
or  spores.    A  cyst  results  from  the  for- 
mation of  a  heavy  wall  around  the  whole 
organism.    Spores  are  produced  within  the 
organism  by  the  formation  of  heavy  walls 
around  a  number  of  individuals  which  have 
been  produced  by  multiple  fission  or  other- 
wise.   This  process,  known  as  sporogony, 
ordinarily  follows  syngamy.     Each  spore 
may  contain  one  or  more  individual  organ- 
isms or  sporozoites. 

The  vegetative,  motile  stage  of  a 
protozoon  is  known  as  a  tropliozoite. 


HISTORY 

The  first  person  to  see  protozoa  was 
the  Dutch  microscopist,  Antony  van  Leeu- 
wenhoek  (1632-1723).     He  used  simple 
lenses  which  he  ground  himself  and  which 
gave  magnifications  as  high  as  270  times. 
His  letters  to  the  Royal  Society  are  a 
classic  of  biology.     Between  1674  and  1716, 
Leeuwenhoek  described  many  free-living 
protozoa,  among  them,  according  to  Dobell 
(1932),  being  Euglena,    Volvox  and  Vorti- 
cella.    Huygens  in  1678  was  the  first  to 
describe  Paramecium.    Classic  work  on 
free-living  protozoa  was  done  by  O.   F. 
Milller  (1786),   Ehrenberg  (1830,   1838)  and 
Dujardin  (1841). 

The  first  parasitic  protozoon  to  be 
discovered  was  Eimeria  stiedae;  Leeuwen- 
hoek found  its  oocysts  in  the  gall  bladder 
of  an  old  rabbit  in  1674.     Later,  in  1681, 
Leeuwenhoek  found  Giardia  lamblia  in  his 
own  diarrheic  stools,  and  in  1683  he  found 
Opalina  and  Nyctotherus  in  the  intestine  of 
the  frog. 

The  first  species  of  Tricfiomonas, 
T.  tenax,  was  found  by  O.   F.  Miiller  in 
1773  in  the  human  mouth;  he  named  it 
Cer carta  tenax.    Donne  found  T.   vaginalis 
in  the  human  vagina  in  1837,  and  Davaine 
found  Trichomonas  and  Chilomastix  in  the 
stools  of  human  cholera  patients  in  1854. 

The  first  trypanosome  was  discovered 
in  the  blood  of  the  salmon  by  Valentin  in 
1841,  and  the  frog  trypanosome  by  Gluge 
and  Gruby  in  1842.     Lewis  found  the  first 
mammalian  trypanosome,    T.   lewisi,  in  the 
rat  in  1878.     Evans  discovered  the  first 
pathogenic  one,  T.   eva>isi,    in  1881  in  India, 
where  it  was  causing  the  disease  known  as 
surra  in  elephants.     Bruce  discovered    T. 
brucei  in  Africa  in  1895  and  described  its 
life  cycle  and  transmission  by  the  tsetse 
fly  in  1897.    In  1902,  Dutton  discovered 
that  African  sleeping  sickness  of  man  was 
caused  by  T.  gambiense.     Leishmania 
tropica  was  first  seen  by  Cunningham  in 
India  in  1885  and  was  first  described  and 
identified  as  a  protozoon  by  Borovsky  in 
Russia  in  1898.     Leishman  and  Donovan 
independently  discovered  Leishmania 
donovani  in  India  in  1903. 


INTRODUCTION  TO  THE  PROTOZOA 


23 


Histomonas  meleagridis ,  the  cause  of 
blackhead  of  turkeys,  was  discovered  by 
Theobald  Smith  in  1895.    Its  transmission 
in  the  eggs  of  the  cecal  worm  was  discov- 
ered by  Tyzzer  and  Fabyan  in  1922  and 
described  in  detail  by  Tyzzer  in  1934. 

The  first  parasitic  amoeba,  Enta- 
moeba gbtgivalis,  was  found  in  the  human 
mouth  by  Gros  in  1849.     Lewis  found  E. 
coli  in  India  in  1870,  and  Losch  found  E. 
histolytica  in  Russia  in  1875. 

Balantidium  coli  was  discovered  by 
Malmsten  in  1857. 

It  was  not  until  154  years  after  Leeu- 
wenhoek  saw  Eimeria  stiedae  that  any 
other  telosporasids  were  found.     Then,   in 
1828,  Dufour  described  gregarines  in  the 
intestines  of  beetles,  and  in  1838  Hake 
rediscovered  the  oocysts  of  E.  stiedae. 
The  most  extensive  early  study  of  the  coc- 
cidia  was  that  of  Eimer  (1870),  who  des- 
cribed a  number  of  species  in  various 
animals.     Schaudinn  and  Siedlecki  (1897) 
described  the  gametocytes  and  gametes  of 
coccidia  and  showed  that  they  formed 
zygotes.     Further  studies  on  the  life  cycle 
of  coccidia  were  published  by  Schaudinn 
in  1898  and  1899.    Classic  work  on  the 
coccidia  of  gallinaceous  birds  was  done  by 
Tyzzer  (1929)  and  Tyzzer,  Theiler  and 
Jones  (1932). 

The  human  malaria  parasite  was  dis- 
covered in  1880  by  the  French  army  doctor, 
Alphonse  Laveran.    Golgi  (1886,   1889)  re- 
ported on  its  schizogony  and  distinguished 
the  types  of  fever  caused  by  the  different 
species.    MacCallum  (1897),  working  with 
the  closely  related  Haemoproteiis  of  birds, 
recognized  that  the  exflagellation  which 
had  been  seen  by  Laveran  was  microgamete 


formation,  and  later  observed  fertilization 
and  zygote  formation  in  Plasmodium  fal- 
ciparum. 

Ross  worked  out  the  life  cycle  of  the 
bird  malaria  parasite,   Plasmodium  re- 
lictum   {P.  praecox),  in  India  in  1898, 
showing  that  it  was  transmitted  by  the 
mosquito,   Culex  fatigans .    Working  inde- 
pendently in  Italy,  Grassi  and  his  collab- 
orators (1898)  almost  immediately  after- 
ward found  that  human  malaria  is  trans- 
mitted by  Anopheles  mosquitoes. 

Babesia  bovis  was  discovered  by 
Babes  in  1888.     Theobald  Smith  and  Kil- 
borne  described  the  cause  of  Texas  fever 
of  cattle,  B.  bigemina  in  1893;  they  showed 
that  it  was  transmitted  by  the  tick,  Boo- 
philus  annulatus,  being  passed  thru  its 
eggs  to  the  next  generation  of  ticks  which 
then  infected  new  cattle.    This  was  the 
first  demonstration  of  arthropod  trans- 
mission of  a  protozoon. 

The  present  century  has  seen  many 
advances  in  protozoology,  but  there  are 
many  more  ahead.    Several  times  more 
species  of  parasitic  protozoa  have  been 
described  since  1900  than  were  known  be- 
fore, but  these  are  only  a  fraction  of  the 
total  number.     Exciting  new  discoveries 
are  being  made  every  year  on  the  physi- 
ology and  nutritional  requirements  of  pro- 
tozoa (Lwoff,   1951;  Hutner  and  Lwoff, 
1955),  and  the  life  cycles,  host-parasite 
relations,  and  pathogenesis  of  many  spe- 
cies are  only  now  being  worked  out.    The 
electron  microscope  and  the  phase  micro- 
scope have  opened  up  a  whole  new  field 
for  morphologic  study,  chemotherapy  is 
progressing  rapidly,  and  new  discoveries 
are  being  made  even  in  taxonomy,  which 
most  people  used  to  consider  a  dead  field. 


CLASSIFICATION 

Various  classifications  have  been  proposed  for  the  Protozoa.    They  have  been  dis- 
cussed by  Hall  (1953)  and  also  by  Biocca  (1957).     The  classification  used  in  the  present 
book  is  based  on  those  used  by  Jahn  and  Jahn  (1949)  and  Hall  (1953),  with  certain  mod- 
ifications; the  classification  of  the  Ciliasida  is  based  on  Corliss  (1956,   1959).    The  uni- 
form endings  for  the  names  of  higher  taxa  proposed  by  Levine  (1959)  are  used.    Most  of 
the  groups  not  of  veterinary  or  medical  interest  are  omitted.    In  addition,  some  genera 


24  INTRODUCTION  TO  THE  PROTOZOA 

once  thought  to  be  protozoa  but  now  known  to  be  otherwise  are  not  included.    Among  these 
are  AnafilasDia,   Eperyllirozooii  and  Haeniohartonella,  all  of  which  are  rickettsiae;   Bar- 
tonella, which  is  a  bacterium;  and  Pneumocystis,  which  is  a  yeast. 

Class  MASTIGASIDA 

With  1  or  more  flagella.    Nucleus  vesicular. 

Subclass   PHYTOMASTIGASINA 

Typically  with  chromatophores.     Nutrition  typically  holophytic. 

Order  CHRYSOMONADORIDA 

With  1  to  3  flagella.     Chromatophores,  if  present,  yellow,  brown, 
orange,  or  occasionally  blue.    Stored  reserves  include  leucosin  (pre- 
sumably a  polysaccharide)  and  lipids,  but  no  starch. 

Suborder  EUCHRYSOMONADORINA 

Flagellate  stage  dominant.     Without  siliceous  skeleton  or  peri- 
pheral zone  of  coccoliths. 

Family  CHROMULINIDAE 
With  1  flagellum. 

Caviomonas 

Oikomonas 

Sphaeromonas 

Family  OCHROMONADIDAE 

With  1  long  and  1  short  flagellum. 

Monas 

Family   PRYMNESIIDAE 
With  3  flagella. 

Prymnesium 


INTRODUCTION  TO  THE  PROTOZOA  2S 


Order  EUGLENORIDA 

With  1  to  4  flagella.     Chromatophores,  if  present,  green. 
Stored  reserves  composed  of  paramylum. 


Suborder  EUGLENORINA 

Pellicle  rigid.     Flagellar  sheath  not  swollen  at  base. 
Seldom  holozoic. 


Family  ASTASHDAE 

Without  chromatophores  or  stigma.    With  1  flagellum. 
Body  highly  plastic,   altho  usually  elongate  spindle-shaped. 


Copromonas 

Order  DINOFLAGELLORIDA 

With  2  flagella,   1  of  which  is  transverse.     Marine  forms. 

Suborder   GYMNODINIORINA 

Unarmored  dinoflagellates  (without  theca). 

Family  GYMNODINIIDAE 

With  well-developed  girdle  and  sulcus.     Transverse  fla- 
gellum typically  flattened.     Tentacle  and  ocellus  absent. 

Gymnodinium 

Suborder  PERIDINIORINA 

With  a  theca  of  a  cellulose-like  material,  composed  of  separate 
plates. 

Family  GONYAULACIDAE 

Thecal  plates  distinct.    One  antapical  plate  is  characteristic. 

Gonyaulax 


26  INTRODUCTION  TO  THE  PROTOZOA 


Order   PHYTOMONADORIDA 

With  1  to  8  flagella.     Typically  with  1  green  chromatophore. 
Body  wall  contains  cellulose.    Starch  and  lipids  stored  as  food. 


Family  CHLAMYDOMONADIDAE 

Solitary,  with  a  well-developed  membrane. 

Polytoma 

Subclass   ZOOMASTIGASINA 

Without  chromatophores.     Nutrition  holozoic  or  saprozoic. 

Order  RfflZOMASTIGORIDA 

With  both  flagella  and  pseudopods. 

Family  MASTIGAMOEBIDAE 

With  1  to  3,   rarely  4  flagella. 

Histomonas 

Order  PROTOMASTIGORIDA 
With  1  or  2  flagella. 

Family  TRYPANOSOMATIDAE 

With  1  flagellum.     Body  characteristically  leaf -like  but 
may  be  rounded.    With  a  single  nucleus  and  a  kinetoplast. 
With  a  basal  granule  from  which  a  flagellum  arises.     Ex- 
clusively parasitic. 


Blastocrithidia  Leptomonas 

Crilhidia  Phytomonas 

Herpelo»ioiias  Tyypa>ioso)ua 
Leisliuiaiiia 


Family   BODONIDAE 

With  2  flagella  originating  anteriorly,  one  directed  anter- 
iorly and  the  other  posteriorly.     Anterior  end  more  or  less 
drawn  out.    With  1  to  several  contractile  vacuoles. 


INTRODUCTION  TO  THE  PROTOZOA  27 


Bodo 

Cercomonas 
PleuroDionas 
Proteroinonas 


Family  AMPfflMONADIDAE 

Body  naked  or  loricate,  with  2  equal  flagella. 

Spiromonas 


Order   POLYMASTIGORIDA 

With  3  to  about  12  flagella  (2  in  Retortamonas)  and  1,  2  or  several 
nuclei.    Without  costa,  axostyle  (except  in  some  Hexamitidae  and  Poly- 
mastigidae)  or  parabasal  body. 


Family  TETRAMITIDAE 

With  4  flagella,   1  or  2  of  which  may  be  trailing. 


Enteromonas 
Tetrmnitus 


Family  RETORTAMONADIDAE 

With  2  or  4  flagella,  of  which  1  is  trailing.    With  1  nucleus. 
Cytostome  with  supporting  fibrils  present. 


Chilomastix 
Retortamonas 


Family  CALLIMASTIGIDAE 

With  a  compact  antero-lateral  group  of  flagella  which  beat 
as  a  unit.    With  1  nucleus. 


Callimastix 
Selenonwnas 


Family  POLYMASTIGIDAE 

With  4  anterior  flagella  and  axostyle.    With  1  nucleus. 
Apparently  without  parabasal  body. 


Monocercomonoides 


28 


INTRODUCTION  TO  THE  PROTOZOA 


Family   COCHLOSOMATIDAE 

With  6  anterior  flagella,   1  axostyle  and  a  single  nucleus. 
Apparently  without  parabasal  body. 


Cochlosoma 


Family  HEXAMITIDAE 

With  6  or  8  flagella,  2  nuclei  and  sometimes  axostyles  and 
median  or  parabasal  bodies.     Bilaterally  symmetrical. 


Giardia 
Hexaniila 
Octomilus 
Trepomonas 


Order  TRICHOMONADORIDA 

With  3  to  6  flagella,  of  which  1  is  trailing  and  may  form  part  of  an  un- 
dulating membrane.    With  1  or  many  nuclei  (the  forms  in  vertebrates 
have  only  1  nucleus),  but  not  with  2.    With  axostyle  and  parabasal  body. 


Family  MONOCERCOMONADIDAE 

With  either  a  free  or  an  adherent  trailing  flagellum  but  no 
undulating  membrane  or  costa. 


Chilomitus 
Hexamastix 
Monocercomonas 
Protrichomonas 


Family  TRICHOMONADIDAE 

With  an  undulating  membrane  and  a  costa.    Sometimes  with 
a  pelta. 


Pentatrichomonas 

Trichomonas 

Tritrickomonas 

Order  HYPERMASTIGORIDA 

With  many  flagella,   1  nucleus  and  often  multiple  axostyles  and  para- 
basal bodies.    Intestinal  parasites  of  termites  and  roaches. 

Trichonynipha 


INTRODUCTION  TO  THE  PROTOZOA  29 

Class  SARCODASIDA 

With  pseudopods  but  without  flagella  or  cilia.     Nucleus  vesicular. 

Subclass  RfflZOPODASINA 

With  lobopods,  filopods  or  myxopods  but  without  axopods. 

Order  AMOEBORIDA 

With  lobopods.    Without  test. 

Family  NAEGLERIDAE 

With  amoeboid  and  flagellate  stages. 

Naegleria 
Trimastigamoeba 


Family  AMOEBIDAE 

Free-living  or  coprozoic  amoebae  without  a  flagellate 
phase. 


Acanthamoeba  Sappinia 

Hartmannella  Vahlkampfia 


Family  ENDAMOEBIDAE 

Parasites  in  the  digestive  tract  of  vertebrates  and  inverte- 
brates. 


Dientamoeba  Entamoeba 

Endamoeba  lodamoeba 

Endolimax 


Order  TESTACEORIDA 

With  a  single-chambered  test. 

Family  ARCELLIDAE 

Test  simple  and  membranous.     Pseudopods  filose  or  sim- 
ply branched. 

Chlamydophrys 


30  INTRODUCTION    TO  THE  PROTOZOA 


Class  TELOSPORASIDA 

With  simple  spores  containing  1  to  many  sporozoites  but  without  polar  filaments. 
Without  pseudopods,  cilia  or  flagella  (except  for  flagellated  microgametes  in  some 
groups).     Locomotion  by  body  flexion  or  gliding.     Reproduction  both  sexual  and 
asexual.    All  parasitic. 


Subclass  GREGARINASINA 

Mature  trophozoite  extracellular,  large.     Parasites  of  digestive  tract  and 
body  cavity  of  invertebrates. 


Subclass  COCCIDIASINA 

Mature  trophozoite  ordinarily  intracellular,  small. 

Order  EUCOCCIDIORIDA 

Parasites  of  epithelial  and  blood  cells  of  vertebrates  and  invertebrates. 
Life  cycle  involves  both  sexual  and  asexual  phases.    Schizogony  present. 

Suborder  ADELEORINA 

Macrogamete  and  microgametocyte  associated  in  syzygy  during 
differentiation.    Microgametocyte  usually  produces  few  micro- 
gametes.    Sporozoites  enclosed  in  an  envelope.    Monoxenous  or 
heteroxenous. 

Superfamily  ADELEICAE 

Zygote  inactive,  may  or  may  not  develop  a  typical  oocyst. 

Family  ADELEIDAE 

Sporocysts  formed  in  oocyst.    In  epithelium  of  gut 
and  its  appended  organs.     Chiefly  in  invertebrates. 

Klossia 

Family  KLOSSIELLIDAE 

Typical  oocyst  not  formed;  a  number  of  sporocysts, 
each  with  many  sporozoites,  develops  within  a  mem- 
brane which  is  perhaps  laid  down  by  the  host  cell. 
Two  to  4  non-flagellate  microgametes  formed  by 
microgametocyte.     Monoxenous,  gametogony  and 
schizogony  occurring  in  different  locations  in  the  same 
host.    In  kidney  and  other  organs  of  host. 

Klossiella 


INTRODUCTION  TO  THE  PROTOZOA  31 


Superfamily  HAEMOGREGARINICAE 

Zygote  active  (ookinete),   secreting  a  flexible  membrane  which  is 
stretched  during  development.     Heteroxenous.     Life  cycle  in- 
volves 2  hosts,  one  vertebrate  and  the  other  invertebrate.    In 
cells  of  circulatory  system  of  vertebrates  and  digestive  system 
of  invertebrates. 


Family  HAEMOGREGARINIDAE 

Oocysts  small,  without  sporocysts. 

Haemogregarina 

Family  HEPATOZOIDAE 

Oocysts  large,  containing  many  sporocysts,  each  with  4  to 
12  or  more  sporozoites.     Microgametes  non-flagellate. 

Hepatozoon 


Family  KARYOLYSIDAE 

Sporoblasts  become  sporokinetes  which  invade  the  egg  of  a 
mite  before  secreting  sporocyst  membrane.     Sporocysts 
with  numerous  sporozoites.     Gametocytes  in  erythrocytes 
of  vertebrate  host. 


Karyolysus 


Suborder  EIMERIORINA 

Macrogamete  and  microgametocyte  develop  independently. 
Syzygy  absent.     Microgametocyte  typically  produces  many  micro- 
gametes.     Zygote  not  motile.    Sporozoites  typically  enclosed  in 
a  sporocyst.    Monoxenous  or  heteroxenous. 


Family  EIMERIIDAE 

Development  in  host  cell  proper.     Oocysts  and  schizonts 
without  attachment  organ.     Oocysts  with  0,   1,   2,   4  or  many 
sporocysts,  each  with  1  or  more  sporozoites.     Monoxenous. 
Schizogony  in  the  host,   sporogony  typically  outside.     Mi- 
crogametes with  2  flagella. 

Dorisiella  Tyzzeria 

Einieria  Wenyonella 

Isospora 


32  INTRODUCTION  TO  THE  PROTOZOA 


Family  CRYPTOSPORIDIIDAE 

Development  on  the  surface  of  the  host  cell  or  within  its 
striated  border  and  not  in  the  cell  proper.     Oocysts  and 
schizonts  with  a  knob-like  attachment  organ  at  some  point 
on  their  surface.     Oocysts  without  sporocysts.     Monoxenous. 
Microgametes  without  flagella. 

Crxptospu)-idii(7n 


Family  AGGREGATIDAE 

Development  in  host  cell  proper.     Oocysts  typically  with 
many  sporocysts.     Heteroxenous.    Schizogony  in  one  host, 
sporogony  in  another. 

Merocystis 


Family  LANKESTERELLIDAE 

Development  in  host  cell  proper.     Oocysts  without  sporo- 
cysts, but  with  8  or  more  sporozoites.     Heteroxenous,  with 
schizogony,   gametogony  and  sporogony  in  a  vertebrate  host. 
Sporozoites  in  blood  cells,  transferred  without  developing 
by  an  invertebrate  (mite  or  leech).     Microgametes  with  2 
flagella,   so  far  as  is  known. 

Lankesterello 
Schellackia 


Suborder  HAEMOSPORORINA 

Macrogamete  and  microgametocyte  develop  independently.    Syzygy 
absent.     Microgametocyte  produces  moderate  number  of  micro- 
gametes.    Zygote  motile  (ookinete).     Sporozoites  naked.     Heter- 
oxenous.   Schizogony  in  vertebrate  host,   sporogony  in  inverte- 
brate.    Pigment  (hematin)  formed  from  host  cell  hemoglobin. 


Family   PLASMODIIDAE 

With  the  characters  of  the  suborder. 

Haemoproteus  Leucocytozoon 

Hepatocystis  Plasmodium 

Class  PIROPLASMASIDA 

Small,  piriform,  round,  amoeboid  or  rod-shaped  parasites  of  vertebrate  erythro- 
cytes and  also  in  some  cases  of  leucocytes  or  histiocytes.     Pigment  (hematin)  not 


INTRODUCTION  TO  THE  PROTOZOA  33 


formed  from  host  cell  hemoglobin.    Without  spores.     Nucleus  vesicular.    Without 
flagella  or  cilia.     Locomotion  by  body  flexion  or  gliding.     Reproduction  asexual, 
by  binary  fission  or  schizogony.     Existence  of  sexual  reproduction  dubious.     All 
parasitic.     Heteroxenous.     Vectors  (if  known),   Lxodid  or  argasid  ticks. 

Order  PIROPLASMORIDA 

With  the  characters  of  the  class. 


Family  BABESHDAE 

Relatively  large,  piriform,  round  or  oval  parasites  occur- 
ring in  erythrocytes  of  vertebrate  host.  Asexual  reproduc- 
tion in  erythrocytes  by  binary  fission  or  schizogony. 

Aegyptianella 

Babesia 

Echinozoon 


Family  THEILERIIDAE 

Relatively  small,   round,  oval,  irregular  or  rod-shaped 
parasites  of  erythrocytes  and  lymphocytes  or  histiocytes  of 
vertebrate  host.     The  forms  in  the  erythrocytes  may  or 
may  not  reproduce;  in  the  former  case  they  divide  into  2  or 
4  daughter  cells.     Asexual  reproduction  by  schizogony  (or 
a  series  of  binary  fissions)  in  lymphocytes  or  histiocytes 
followed  by  invasion  of  erythrocytes. 

Cytauxzoon 
Gonderia 
The  Her  ia 


Class  TOXOPLASMASIDA 

Without  spores.    With  cysts  or  pseudocysts  containing  many  naked  trophozoites. 
Nucleus  vesicular.    Without  flagella  or  cilia.     Locomotion  by  body  flexion  or  glid- 
ing.    Reproduction  asexual,  by  binary  fission  or  endodyogeny  (and  possibly  by 
schizogony  in  young  cysts).     All  parasitic.     Monoxenous. 


Order  TOXOPLASMORIDA 

With  the  characters  of  the  class. 


Family  SARCOCYSTIDAE 

With  cysts.    Multiplication  by  binary  fission,   and  possibly 
also  by  schizogony  in  young  cysts. 

Sarcocystis 


34  INTRODUCTION  TO  THE  PROTOZOA 


Family  TOXOPLASMATIDAE 

With  pseudocysts  and  probably  true  cysts  as  well.  Multi- 
plication by  binary  fission  or  endodyogeny  and  possibly  by 
schizogony  in  young  pseudocysts. 

Besnoitia 

Encephalilozoon 

Toxoplasma 


Class  CNIDOSPORASIDA 

With  spores  containing  polar  filaments.    Nucleus  vesicular.    All  parasitic. 

Order  MYXOSPORORIDA 

Spores  comparatively  large,  with  bivalve  shell  and  1  to  4  polar  cap- 
sules.    Parasites  of  lower  vertebrates,  especially  fish. 

Order  MICROSPORORIDA 

Spores  comparatively  small,  with  1 -piece  shell  and  1  or  2  polar  fila- 
ments.    Typically  parasites  of  invertebrates  and  fish. 


Class  CILIASIDA 

With  two  types  of  nucleus--macronucleus  and  micronucleus.    With  cilia  at  some 
stage  of  the  life  cycle. 


Subclass  HOLOTRICHASINA 

Without  or  with  poorly  developed  adoral  zone  of  membranelles  (except  in 
Peritrichorida). 


Order  GYMNOSTOMORIDA 

Cytostome  opens  directly  at  surface  or  else  into  a  slight  depression 
which  lacks  well-developed  peristomial  ciliature. 


Family  BUETSCHLIIDAE 

Cytostome  usually  at  anterior  end.     Anterior  concretion- 
vacuole  (possibly  a  statocyst),  one  or  more  contractile 
vacuoles  and  posterior  cytopyge  present.     Cilia  uniformly 
distributed  over  body  or  restricted  to  certain  areas. 

Alloiozona  Bundleia 

Ampullacula  Didesmis 


INTRODUCTION  TO  THE  PROTOZOA 


35 


Blepharoconus  Holophryoides 

Blephah'oprosthium  Parnisotrichopsis 

Blephayosphaera  Polymorphella 

Blepharozoum  Prorodonopsis 

BuetschUa  Sulcoarcus 


Family  PYCNOTRICHIDAE 

Body  completely  ciliated.     A  long  groove  usually  leads  to 
the  cytostome,  which  may  lie  near  the  middle  or  at  the 
posterior  end  of  the  body. 


Bnxtouello 
Infuiidibiiloriiiui 


Order  SUCTORIORIDA 

Young  with  cilia;  adults  with  tentacles. 

Family  ACINETIDAE 

With  endogenous  budding.  Tentacles  capitate,  usually  ar- 
ranged in  groups.  Lorica  often  present.  Stalk  present  or 
absent. 

Allantosoma 

Order  TRICHOSTOMORIDA 

Cytostome  usually  at  base  of  well-defined  oral  groove  or  pit,  the  wall 
of  which  bears  1  or  more  dense  fields  of  adoral  cilia;  in  some  primi- 
tive forms  the  cytostome  is  almost  at  the  anterior  end,  but  more  often 
it  is  shafted  posteriorly  on  the  ventral  surface.    Spiral  torsion  of  the 
body  occurs  in  some  genera. 

Family  BLEPHAROCORYTHIDAE 

Somatic  ciliation  reduced  to  a  few  anterior  and  posterior 
fields,  with  1  or  2  groups  of  anal  cilia  near  the  cytopyge 
and  2  or  3  distinct  anterior  groups.     Cytostome  antero- 
ventral,  opening  into  a  long  ciliated  pharynx. 

Blepharocorys  Qchoterenaia 

Charonina 

Family  CYATHODINIIDAE 

Cilia  limited  to  anterior  half  of  body.     Peristome  a  non- 
ciliated,  rather  long  triangular  groove.    Slender  trichites 


36  INTRODUCTION  TO  THE  PROTOZOA 


extend  from  a  row  of  papillae  along  left  rim  of  peristome, 
and  an  adoral  cilium  arises  from  each  papilla. 

Cyathodinium 


Family  ISOTRICHIDAE 

Mouth  terminal  or  subterminal.     Pharynx  ciliated,  with 
longitudinal  striations  in  its  wall.    Somatic  ciliation  com- 
plete and  practically  uniform. 

Dasytriclia 
Isotricha 


Family   PARAISOTRICHIDAE 

Mouth  subterminal,  opening  just  posterior  to  concretion 
vacuole.    Somatic  ciliation  complete,  with  an  anterior  tuft 
of  longer  cilia. 

Paraisotricha 


Family   BALANTIDIIDAE 

Somatic  ciliation  complete,  with  cilia  arranged  in  approx- 
imately longitudinal  rows.     Peristome  a  pouch  with  a  tri- 
angular opening,  thru  which  the  short  adoral  band  of  mem- 
branelles  is  not  easily  seen  from  the  outside.     Numerous 
long  fibrils  extend  into  the  endoplasm  from  the  basal  gran- 
ules of  cilia  and  membranelles.     Concretion  vacuole  absent. 

Balantidium 


Order  HYMENOSTOMORIDA 

Adoral  cilia  fused  in  membranes,  the  number,   size  and  arrangement 
of  which  vary  in  different  genera. 


Family  OPHRYOGLENIDAE 

With  a  ciliated  vestibule  (peristome),   an  invagination  of  the 
body  wall,  and  a  pharynx  which  opens  into  the  vestibule.     A 
retractile  body  ("body  of  Lieberkiihn",   "watch-glass  body") 
lies  just  to  the  left  of  the  vestibule.     Reproduction  takes 
place  within  a  cyst.     The  resultant  young  ciliates  (tomites) 
leave  the  cyst,  develop  into  trophic  therontes  and  then  into 
large  trophonts  which  encyst. 

Ichthyophthirius 


INTRODUCTION  TO  THE  PROTOZOA  37 


Family  PARAMECIIDAE 

With  oral  groove  extending  from  the  anterior  end  toward 
the  middle  of  the  body.     Somatic  ciliation  complete  and 
essentially  uniform.     Adoral  ciliature  including  a  dorsal 
zone  of  long  cilia  (quadripartite  membrane)  and  2  peniculi 
(dense  bands  of  cilia  extending  in  a  shallow  spiral  toward 
the  cytostome). 

Paramecium 


Family  TETRAHYMENIDAE 

Adoral  ciliature  composed  of  3  membranelles  lying  to  the 
left  in  the  oral  pouch;  a  fourth,   paroral  membrane  extends 
along  its  right  margin.     One  or  more  stomatogenous  rows 
of  cilia  end  at  the  posterior  margin  of  the  oral  pouch. 

Tetrahymena 


Subclass  SPIROTRICHASINA 

Bases  of  adoral  zone  membranelles  usually  at  right  or  oblique  angle  to  long 
axis  of  adoral  zone;  this  series  of  membranelles  extends  anteriorly  from  the 
left  margin  of  the  cytostome;  the  basal  plate  of  each  membranelle  contains 
2,   3  or  rarely  4  rows  of  basal  granules. 


Order  HETEROTRICHORIDA 

Somatic  ciliation  usually  complete.     Peristome  usually  elongated  and 
fairly  narrow,  with  adoral  zone  of  membranelles  along  left  wall.    An 
undulating  membrane  often  extends  for  some  distance  along  right  mar- 
gin of  peristome. 


Family   PLAGIOTOMIDAE 

Body  densely  ciliated.     Adoral  zone  of  membranelles  well 
defined.     Undulating  membrane  at  right  margin  of  peri- 
stome. 


Nyctotherus 


Order  ENTODINIORIDA 

Ciliation  may  be  limited  to  the  adoral  zone;  there  may  be  1  or  more 
additional  bands  or  groups  of  membranelles.    Skeletal  plates  usually 
present. 


38 


INTRODUCTION  TO  THE  PROTOZOA 


Family  OPHRYOSCOLECIDAE 

With  not  more  than  1  band  of  membranelles  in  addition  to 
adoral  zone. 


Amphacanthus 

Caloscolex 

Cunhaia 

Diplodinium 

Diploplastron 

Elytroplastron 


Enoploplastron      EiuUplodinuim 


Enlodiniiim 

Eodinium 

Epidinimn 

Epiplastron 

Eremoplastron 


Meladiniujn 

Ophryoscolex 

Opisthotriclmm 

Ostracodinium 

Polyplastron 


Family  CYCLOPOSTHIIDAE 

With  2  or  more  bands  of  membranelles  in  addition  to 
adoral  zone. 


Cochliatoxum 

Cycloposthium 

Ditoxuni 

Elepliantophilus 

Polydiniella 


Prototapirella 

Spirodinium 

Tetratoxuni 

Tlioracodinium 

Triadinium 


Trifasciciilaria 
Tripalmaria 
Tripliimaria 
Troglodytella 


Class   PROTOCILIASIDA 

With  cilia.    Nucleus  vesicular. 


Opalina 


REFERENCES 

The  following  list  includes  not  only  the  papers  cited  in 
this  chapter  but  also  a  number  of  general  references  on  the 
Protozoa  and  on  veterinary  and  medical  protozoology. 

Beams,   H.   W.  ,    T.   N.   Tahmisian,    R.   L.   Devine  and  E. 

Anderson.     1959.    J.  Protozool.   6:136-146. 
Becker,   E.   R.     1959.    Protozoa.     Chap.   36inBiester,   H.  E. 

and  L.   H.  Schwarte,   eds.     Diseases  of  poultry.     4th  ed. 

Iowa  St.  Univ.   Press,  Ames.   pp.   828-916. 
Biocca,    E.     1957(1956).     Alcune  considerazioni  suUq  sis- 

tematica  dei  protozoi  e  Sulla  utilita  di  creare  una  nuova 

closse  di  protozoi.     Rev.  Brosil.    Malariol.    8:91-102. 
Boyden,   A.     1957.    Are  there  any  "acellular  animals"? 

Science  125:155-156. 
Corliss,   J.    O.     1956.     On  the  evolution  and  systematics  of 

ciliated  protozoa.     Syst.   Zool.   5:68-91,    121-140. 
Corliss,   ].   O.     1959.     An  illustrated  key  to  the  higher 

groups  of  the  ciliated  protozoa,   with  definitions  of  terms. 

J.   Protozool.    6:265-284. 
Craig,   C.   F.     1948.     Laboratory  diagnosis  of  protozoan  dis- 
eases.    2nd  ed.    Lea  &  Febiger,  Philadelphia,    pp.   384. 


Curasson,    G.     1943.     Traite  de  protozoologie  veterinaire  et 

comparee.     Vigot  Freres,    Paris.     3  vols.     pp.  xcv  + 1268. 
Dobell,    C.     1932.     Anthony  van  Leeuwenhoek  and  his  "little 

animals. "    Harcourt,   Brace,   New  York.     pp.   vii    +    435. 
Dogiel,   V.   A.     1951.     Obshchaya  protistologiya.     Gosud. 

Izdat.  Sovet.    Nauka,  Moscow,    pp.  603. 
Dujardin,    F.     1841.     Histoire  noturelle  des  zoophytes  infus- 

oires.     etc.     Roret,    Paris,    pp.    xii    +  684. 
Ehrenberg,   C.   G.     1830.     Organisation,   systematik  und  geo- 

graphisches  Verhaltniss  der  Infusionsthierchen.     Konig. 

Akad.   Wissenschaft,   Berlin,     pp.    108. 
Ehrenberg,    C.   G.     1838.     Die  Infusionsthierchen  als  voUkom- 

mene  Organismen,    etc.     L.  Voss,   Leipzig,     pp.  xviii 

+    547. 
Goldman,   M.  ,   R.    K.   Carver  and  A.  J.   Sulzer.     1958.     Re- 
production of  Toxoplasma  gondii  by  internal  budding. 

J.   Parasit.     44:161-171. 
Crosse,    P. -P. ,    ed.     1952-53.     Traite  de  zoologie.     Vol.   I, 

Fuse.    1,    2.     Masson,    Paris,     pp.   xii   +   2231. 
Grell,    K.   G.     1956.     Protozoologie.     Springer,   Berlin,     pp. 

vii  +    284. 
Hall,   R.  P.     1953.     Protozoology.     Prentice-Hall,   New  York, 

pp.  682. 


INTRODUCTION  TO  THE  PROTOZOA 


39 


Hoare,   C.   A.     1949.      Handbook  of  medical  protozoology. 

Balliere,   Tindall  G  Cox,    London,     pp.   xv   +   334. 
Hutner,    S.   H.   and  A.   Lwoff,    eds.     1955.     Biochemistry  and 

physiology  of  protozoa.     Vol.    2.     Academic  Press,    New 

York.     pp.    xiii    +  388. 
Hyman,    L.   H.     1940.     The  invertebrates.     Vol.    1.     Protozoa 

through  Ctenophorc.     McGraw-Hill,   New  York.     pp.   xii 

+    726. 
John,    T.   L.  and  F.   F.  Jahn.     1949.     How  to  know  the  pro- 
tozoa.    Brown,    Dubuque,    la.     pp.   234. 
Jarosch,    R.     1959.     Zur  Gleitbewegung  der  niederen  Organ- 

ismen.     Protoplasma  50:277-289. 
Jirovec.O.  ,    K.   Wenig,   B.    Pott,    E.  Bartos,   J.   Weiser  and 

R.   Sramek-Husek.     1953.     Protozoologie.     Nak.   Cesk. 

Akad.    Ved,    Prague,     pp.   643. 
Kirby,   H.     1950.     Materials  and  methods  in  the  study  of 

protozoa.     Univ.   Calif.   Press,   Berkeley,     pp.   x    +   72. 
Kudo,    R.   R.     1954.     Protozoology.     4th  ed.     Thomas, 

Springfield,    111.     pp.  xi    +  966. 
Kummel,    G.     1958.     Die  Gleitbewegung  der  Gregarinen. 

Elektronmikroskopische  und  experimentalle  Unteisuch- 

ungen.     Arch.   Protist.     102:501-522. 


Levine,    N.    D.     1959(1958).     Uniform  endings  for  the  names 
of  higher  taxG.     Syst.   Zool.     7:134-135. 

Ludvik,   J.     1958.     Elektronenoptische  Befunde  zur  Morphol- 
ogie  der  Sarcosporidien  (Sarcocystis  tenella  Railliet  1886). 
Zbl.   Bakt.   I.   Orig.    172:330-350. 

Lwoff,   A.,    ed.     1951.     Biochemistry  and  physiology  of  pro- 
tozoa.    Vol.    1.     Academic  Press,   New  York.     pp.  x 
+    434. 

Morgan,   B.   B.  and  P.   P.   Hawkins.     1952.     Veterinary  proto- 
zoology.    2nd  ed.     Burgess,   Minneapolis,     pp.   vii 
+    187. 

Mullet,    O.    F.     1786.     Animalcule  Infusoria  fluviatilia  et 
marina,    quae  detexit,   systematice  descripsit  et  ad  vivum 
delineari  curavit,    etc.     Typis  N.   MoUeri,   Hauniae.    pp. 
Ivi  -I-    367. 

Reichenow,    E.     1949-53.     Lehrbuch  der  Protozoenkunde. 
6th  ed.     3  vols.     Fischer,  Jena.     pp.  viii    +     1213. 

Richardson,  U.  F.  and  S.  B.  Kendall.  1957.  Veterinary 
protozoology.  2nd  ed.  Oliver  G  Boyd,  Edinburgh,  pp. 
xii  +   260. 

Wenyon,   C.  M.     1926.     Protozoology.     2  vols.     Wood,   New 
York.     pp.  xvi    +    1563. 


Chapter  3 


THE 
HBmHAGEUATBS 


The  flagellates  belong  to  the  class 
Mastigasida.     They  have  1  or  more  fla- 
gella,  and  a  few  have  pseudopods  as  well. 
Their  nutrition  is  holophytic,   holozoic  or 
saprozoic.     They  multiply  by  longitudinal 
binary  fission,  and  many  produce  cysts. 

The  class  is  divided  into  2  subclasses, 
Phytomastigasina  and  Zoomastigasina. 
The  former  contains  the  phytoflagellates, 
the  great  majority  of  which  are  free-living 
and  holophytic.     Those  of  parasitic  interest 
will  be  discussed  in  Chapter  6. 

It  is  convenient  for  our  purposes  to 
divide  the  Zoomastigasina  into  2  groups, 
the  hemoflagellates  which  live  in  the  blood, 
lymph  and  tissues,   and  the  other  flagel- 
lates which  live  in  the  intestine  and  other 
body  cavities. 


FAMILY   TRYPANOSOMATIDAE 

The  hemoflagellates  all  belong  to  the 
family  Trypanosomatidae.     Members  of 
this  family  have  a  leaf-like  or  sometimes 
a  rounded  body  containing  one  nucleus. 
They  have  a  single  flagellum  which  arises 
from  a  basal  granule  or  blepharoplast 
posterior  to  the  end  of  an  elongate  blind 
pouch  or  reservoir  and  passes  anteriorly, 
usually  extending  beyond  the  body.     A  con- 
tractile vacuole  opens  into  the  reservoir, 
but  both  of  these  structures  can  be  seen 
only  with  the  phase  microscope  and  not 
with  the  ordinary  light  microscope  (Ket- 
terer,   1952;  Cosgrove  and  Kessel,   1958; 
Clark,   1959).     The  flagellar  axonenie  is 
composed  of  9  peripheral  and  2  central 
fibrils  (Anderson,  Saxe  and  Beams,   1956). 
An  undulating  membrane  is  present  in 
some  genera;  the  flagellum  lies  in  its  outer 
border.     Posterior  to  the  basal  granule  is 
a  rod-shaped  or  spherical  kinetoplast  con- 
taining deoxyribonucleic  acid.     The  struc- 
ture of  the  kinetoplast  as  seen  in  electron 
micrographs  has  been  interpreted  in  dif- 
ferent ways.     According  to  Anderson,  Saxe 
and  Beams  (1956),   it  consists  of  lamellae 
oriented  at  right  angles  to  its  long  axis; 


-  40 


THE  HEMOFLAGELLATES 


41 


Meyer  and  Queiroga  (1960)  called  it  an 
apparently  lamellar  mass  located  in  a 
vacuole-Iike  space;  Hans  Ris  (unpublished) 
said  that  the  lamellae  represent  sections 
of  a  continuous  spiral;  Clark  and  Wallace 
(1960)  considered  the  kinetoplast  to  be  a 
mitochondrion  containing  antero-posteriorly 
oriented  anastomosing  fibers.     Under  the 
ordinary  light  microscope,  the  kinetoplast 
and  blepharoplast  may  appear  to  be  fused. 
Mitochondria  and  volutin  granules  have  also 
been  seen  in  electron  micrographs. 

Members  of  this  family  were  originally 
parasites  of  the  intestinal  tract  of  insects, 
and  many  are  still  found  only  in  insects. 
Others  are  heteroxenous,   spending  part  of 
their  life  cycle  in  a  vertebrate  and  part  in 
an  invertebrate  host. 

In  the  course  of  their  life  cycles,   mem- 
bers of  one  genus  may  pass  thru  forms 
morphologically  similar  to  those  of  other 
genera.     These  stages  are  named  for  the 
genera  which  they  resemble.    In  the  tryp- 
anosome  form,  which  is  perhaps  the  most 
advanced,  the  kinetoplast  and  basal  granule 
are  near  the  posterior  end  and  the  undulat- 
ing membrane  runs  the  length  of  the  body. 
In  the  crithidial  form,  the  kinetoplast  and 
basal  granule  are  just  anterior  to  the  nu- 
cleus and  the  undulating  membrane  runs 
forward  from  there.    In  the  leptomonad 
form,  the  kinetoplast  and  basal  granule  are 
still  further  forward  in  the  body  and  there 
is  no  undulating  membrane.    In  the  leish- 
manial form,  the  body  is  rounded  and  the 
flagellum  has  degenerated  into  a  tiny  fibril 
which  remains  inside  the  body  (Fig.   1). 
Further  information  on  life  cycles  and 
morphology  is  given  by  Noble  (1955). 

There  are  several  genera  in  the  fam- 
ily Trypanosomatidae.     Members  of  the 
genus  Trypanosoma  are  heteroxenous  and 
pass  thru  leishmanial,   leptomonad,  cri- 
thidial and  trypanosome  stages  in  their 
life  cycle.    In  some  species,  only  trypan- 
osome forms  are  found  in  the  vertebrate 
host,  while  in  other,  more  primitive  ones, 
both  leishmanial  and  trypanosome  forms 
are  present. 

Members  of  the  genus  Blastocrithidia 
are  monoxenous  in  arthropods  and  other 


B 


D 


Fig.    1.        Forms  of  the  Trypanosomatidae. 
A.     Leishmanial  form.     B.     Lep- 
tomonad form.     C.    Crithidial 
form.    D.    Trypanosome  form. 
(Original) 

invertebrates.     They  pass  thru  crithidial, 
leptomonad  and  leishmanial  stages  in 
their  life  cycle.     This  generic  name  was 
introduced  by  Laird  (1959)  for  the  crithi- 
dial species  commonly  and  erroneously 
assigned  to  the  genus  Crithidia.     As  both 
Laird  (1959),  Wallace  (1943)  and  Clark 
(1959)  have  shown,  the  type  species  of 
Crithidia.    from  mosquitoes,   C.  fascicu- 
lata,   is  a  short,  truncate  form  with  a 
stiff  flagellum  emerging  from  a  funnelled 
anterior  depression,  and  never  has  an 
undulating  membrane.     However,  the  term 
crithidial  is  so  deeply  Embedded  in  our 
terminology  as  referring  to  forms  with  an 
undulating  membrane  that  it  is  best  to  re- 
tain it. 

Members  of  the  genus  Crithidia  are 
monoxenous  in  arthropods.    Despite  their 
name,  they  have  only  a  leptomonad  stage. 

Members  of  the  genus  Leptonionas 
are  monoxenous  in  invertebrates.     They 
pass  thru  leptomonad  and  leishmanial 
stages  in  their  life  cycle. 

Members  of  the  genus  Leishmania 
are  heteroxenous,  passing  thru  the  leish- 
manial stage  in  their  vertebrate  host  and 
the  leptomonad  stage  in  their  invertebrate 
host  or  in  culture. 

Members  of  the  genus  Herpetomonas 
are  monoxenous  in  invertebrates.     They 
pass  thru  trypanosome,  crithidial,  lepto- 
monad and  leishmanial  stages  in  their  life 
cycle.     The  trypanosome  form  in  this 
genus  differs  from  that  of  Trypanosoma 


42 


THE  HEMOFLAGEUATES 


in  that  the  undulating  membrane  lies  in  a 
long  reservoir  which  runs  the  whole  length 
of  the  body  and  opens  at  the  anterior  end, 
whereas  in  Trypanosoina  the  reservoir  is 
very  short  and  opens  laterally  near  the 
posterior  end  so  that  the  undulating  mem- 
brane runs  along  the  side  of  the  body 
(Clark,   1959). 

Members  of  the  genus  Phylomonas 
are  heteroxenous  in  the  latex  of  plants  and 
hemipterous  insects,   passing  thru  lepto- 
monad  and  leishmanial  stages  in  their  life 
cycle.     They  are  found  in  milkweeds  and 
related  plants,  and  cause  the  normally 
milky  sap  to  become  colorless. 

The  only  genera  parasitic  in  domestic 
animals  and  man  are  Trypanosoma  and 
Leishmania.    Since,   however,  their 
stages  in  the  invertebrate  vector  are  mor- 
phologically similar  to  those  of  the  genera 
confined  to  invertebrates,  one  cannot  be 
positive,  when  he  finds  an  infected  inver- 
tebrate, whether  it  is  infected  with  a  para- 
site of  vertebrates  or  with  one  of  its  own. 
It  is  possible,  too,  that  some  of  the  forms 
which  we  now  think  are  confined  to  inverte- 
brates may  actually  be  normal  parasites 
of  some  wild  vertebrates. 


make  it  practically  impossible  to  raise 
livestock  in  many  parts  of  the  tropics 
which  would  otherwise  be  ideal.     Accord- 
ing to  Hornby  (1949),   "Trypanosomiasis 
is  unique  among  diseases  in  that  it  is  the 
only  one  which  by  itself  has  denied  vast 
areas  of  land  to  all  domestic  animals 
other  than  poultry.     The  areas  of  complete 
denial  are  all  in  Africa  and  add  up  to  per- 
haps one  quarter  of  the  total  land  surface 
of  this  continent.  "    Some,  but  not  all,  of 
the  African  species  are  transmitted  by 
tsetse  flies.    These  flies  occupy  almost 
4  million  square  miles,  an  area  larger 
than  the  United  States,  and  this  whole  re- 
gion is  under  the  threat  of  trypanosomosis. 

In  a  recent  Hollywood  epic  on  South 
African  history,  there  is  a  scene  in  which 
a  line  of  Boer  covered  wagons  on  the  Great 
Trek  to  the  north  is  attacked  by  Zulus. 
The  warriors  pour  over  the  hills,  the  wag- 
ons form  a  circle  with  the  women  and  chil- 
dren in  the  center,   and  the  Boer  men  pre- 
pare to  fight.    It  is  just  like  a  scene  from 
the  American  Wild  West,  with  the  Indians 
attacking  a  wagon  train  of  pioneers.     But 
there  is  one  difference- -the  Zulus  had  no 
horses,   and  made  their  attack  on  foot. 
The  reason?    Trypanosomosis. 


Genus  lITfPANOSOmA  Gruby,  1843 

Members  of  this  genus  occur  in  all 
classes  of  vertebrates.    They  are  para- 
sites of  the  circulatory  system  and  tissue 
fluids,  but  some,   such  as  T.   cruzi,   may 
actually  invade  cells.     Almost  all  are 
transmitted  by  blood-sucking  invertebrates. 
Most  species  are  probably  non-pathogenic, 
but  the  remainder  more  than  make  up  for 
their  fellows. 

Trypanosomosis  is  one  of  the  world's 
most  important  diseases  of  livestock  and 
man.     Trypanosomes  cause  African  sleep- 
ing sickness  and  Chagas'  disease  in  man 
and  a  whole  series  of  similar  diseases  in 
domestic  animals.     They  are  relatively 
unimportant  in  North  America,  but  they 


A  large  number  of  species  of  Trypano- 
soma   has  been  named.     At  one  time  it 
was  customary,  and  still  is  to  some  extent, 
to  give  different  names  to  trypanosomes 
from  different  hosts.     Many  of  these  names 
are  still  valid,  but  as  we  learn  more  and 
more  about  the  host-parasite  relations  and 
epidemiology  of  the  trypanosomes,   many 
other  names  have  fallen  into  synonymy. 
No  attempt  will  be  made  here  to  list  all 
the  synonyms  of  each  species,  but  the  more 
important  ones  will  be  mentioned. 

Trypanosomes  are  classified  in  groups 
on  the  basis  of  their  morphology,   life  cy- 
cles and  other  biological  characteristics. 
The  validity  of  this  grouping  is  shown  by 
the  fact  that  their  metabolic  characteris- 
tics, which  vary  widely,  fall  into  the  same 
groups. 


THE  HEMOFLACELLATES  43 


The  following  outline  classification  of  trypanosomes  of  veterinary  and  medical  im- 
portance is  based  on  Hoare  (1957,   1959).     Sections  on  metabolism  based  on  von  Brand 
(1956),   Ryley  (1956)  and  von  Brand  and  Tobie  (1959),  and  a  section  on  avian  trypanosomes 
have  been  added. 


I.       PARASITES  OF  MAMMALS 

A.      Morphology  in  Mammal 

Kinetoplast  not  terminal,  large.     Free  flagellum  always  present.     Posterior 
end  of  body  pointed.    Division  in  crithidial,   leishmanial  or  trypanosome  stages. 

Biology 

Multiplication  in  mammal  typically  discontinuous.    Development  of  metacyclic 
trypanosomes  in  hind  gut  (posterior  station)  of  vector  (in  T.   raiigeli  also  in 
salivary  glands:    anterior  station).     Transmission  contaminative  thru  feces  (in 
T.   rangeli  also  inoculative).     Except  for  T.   cruzi.  trypanosomes  slightly  or  not 
pathogenic. 

Metabolism 

Blood  forms  have  high  respiratory  quotient  and  low  sugar  consumption,  produc- 
ing acetic,   succinic  and  lactic  acids  aerobically  and  succinic,  lactic,   acetic  and 
pyruvic  acids  anaerobically.     Cyanide  markedly  inhibits  oxygen  consumption. 
Sulfhydryl  antagonists  moderately  inhibit  oxygen  consumption.     Culture  forms 
have  high  respiratory  quotient  and  moderately  high  sugar  consumption,  produc- 
ing acetic  and  succinic  acids  aerobically  and  succinic  and  acetic  acids  anaero- 
bically; cyanide  markedly  inhibits  oxygen  consumption;  sulfhydryl  antagonists 
moderately  to  markedly  inhibit  oxygen  consumption.     Cytochrome  pigments, 
cytochrome  and  succinic  oxidase  activity  are  present  in  T.   cruzi  and   T.   lewisi. 

1.      LEWISI  GROUP 

a.  Mode  of  reproduction  unknown. 
T.  nielophagium  of  sheep. 

b.  Reproduction  by  binary  fission  in  crithidial  stage. 
T.  theileri  of  cattle. 

c.  Reproduction  by  multiple  fission  in  crithidial  stage. 
T.   lewisi  of  rats. 

T.  duttoni  of  mice. 

d.  Reproduction  by  binary  fission  in  leishmanial  stage. 
T.   cruzi  of  man,  dog,  opossum,  monkeys. 

e.  Reproduction  by  multiple  fission  in  leishmanial  stage. 
T.  nabiasi  of  rabbits. 

f.  Reproduction  by  binary  fission  in  trypanosome  stage. 
T.  rangeli  of  man,  dog,  opossum,  monkeys. 


44  THE  HEMOFLAGELLATES 


B.      Morphology  in  Mammal 

Kinetoplast  terminal  or  subterminal.     Posterior  end  of  body  blunt.    Division  in 
trypanosome  stage. 

Biology 

Multiplication  in  mammal  continuous.    Development  of  metacyclic  trypanosomes 
in  proboscis  or  salivary  glands  (anterior  station)  of  vector  (except  evansi  sub- 
group).   Transmission  inoculative,  thru  bite  (except  T.  equip erduni).    Trypano- 
somes pathogenic. 

1.  VIVAX  GROUP 

Morphology  in  Mammal 

Monomorphic  forms.     Posterior  end  of  body  typically  rounded.     Free  fla- 
gellum  always  present.     Kinetoplast  large,  terminal.     Undulating  mem- 
brane inconspicuous. 

Biology 

Development  in  Glossina,  in  proboscis  only.     T.   vivax  is  also  transmitted 
mechanically  by  tabanids. 

Metabolism 

Blood  forms  have  high  respiratory  quotient  and  high  sugar  consumption, 
producing  pyruvic,  acetic,  lactic  acids  and  glycerol  aerobically  and  glycerol, 
pyruvic,  lactic,   and  acetic  acids  anaerobically.     Cyanide  does  not  inhibit 
oxygen  consumption.    Sulfhydryl  antagonists  markedly  inhibit  oxygen  con- 
sumption.   Cytochrome  and  succinic  oxidase  activity  are  present. 

a.  Long  forms 

T.  vivax oi  cattle,  sheep,  goats,  antelope. 

b.  Short  forms 

T.  uniforme  of  cattle,  sheep,  goats,  antelope. 

2.  CONGOLENSE  GROUP 

Morphology  in  Mammals 

Monomorphic  or  polymorphic  forms.     Free  flagellum  absent  or  present. 
Kinetoplast  medium,  typically  marginal. 

Biology 

Development  in  Glossina,   in  midgut  and  proboscis. 

Metabolism 

Blood  forms  have  high  respiratory  quotient  and  high  sugar  consumption, 
producing  acetic  acid,   succinic  acid,  glycerol  and  pyruvic  acid  aerobically 


THE  HEMOFLAGELLATES  45 


and  succinic  acid,  glycerol,  acetic  acid  and  pyruvic  acid  anaerobically. 
Cyanide  and  sulfhydryl  antagonists  moderately  inhibit  oxygen  consumption. 
Cytochrome  pigments  are  absent  but  cytochrome  and  succinic  oxidase  ac- 
tivity are  present.     Culture  forms  of  T.   co)igoleuse  have  R.  Q.  of  0.9, 
produce  pyruvate,   acetate  and  smaller  amounts  of  lactate,   succinate  and 
glycerol  aerobically,   and  pyruvate,   acetate  and  succinate  with  small  amounts 
of  glycerol  and  no  carbon  dioxide  anaerobically.     Cyanide  and  sulfhydryl 
antagonists  (iodoacetate  and  sodium  arsenite)  inhibit  oxygen  consumption, 
but  Krebs  cycle  inhibitors  (fluoro acetate  and  malonate)  do  so  only  slightly. 

a.  Monomorphic  (free  flagellum  absent  or  short,  undulating  membrane  in- 
conspicuous). 

(1)  Short  forms  (means  12.2-14.4  (n). 

T.  congolense  of  cattle,  equids,  swine,  sheep,  goat,  dog. 

(2)  Long  forms  (means  15.3-17.6  i^). 

T.  dimorphon  of  horse,  cattle,  sheep,  goat,  pig,  dog. 

b.  Polymorphic  (short  forms  without  free  flagellum,  and  long  forms,  of 
which  some  are  stout,  with  conspicuous  undulating  membrane  and  some 
are  slender  with  inconspicuous  undulating  membrane;  free  flagellum 
absent  or  present). 

T.  si))iiae  of  swine,  camels,   cattle,  horse,  warthog. 

3.      BRUCEI  GROUP 

Morphology  in  Mammal 

Monomorphic  or  polymorphic  forms.     Free  flagellum  present  or  absent. 
Kinetoplast  small,   subterminal  (absent  in  T.   equinutn).    Undulating  mem- 
brane conspicuous. 

Biology 

Development  in  Glossina,   in  midgut  and  salivary  glands  (except  evansi  sub- 
group). 

Metabolism 

Blood  forms  have  very  low  respiratory  quotient  and  very  high  sugar  con- 
sumption,  producing  pyruvic  acid  and  sometimes  glycerol  aerobically  and 
pyruvic  acid  and  glycerol  anaerobically.     Cyanide  does  not  inhibit  oxygen 
consumption.    Sulfhydryl  antagonists  markedly  inhibit  oxygen  consumption. 
Culture  forms  have  high  respiratory  quotient  and  moderately  high  sugar 
consumption,   producing  acetic,   succinic,   pyruvic  and  lactic  acids  aero- 
bically.    Cyanide  moderately  inhibits  oxygen  consumption.    Sulfhydryl 
antagonists  markedly  inhibit  oxygen  consumption.     Cytochrome  pigments 
have  not  been  found  in  T.  rhodesiense  or  T.   equiperdum ,  but  cytochrome 
and  succinic  oxidase  activity  are  present  in   T.   rhodesiense. 

a.     Monomorphic  (stout  forms  with  short  free  flagellum). 
(1)    SUIS  SUBGROUP 
T.  suis  of  swine. 


46 


THE  HEMOFIACELLATES 


b.     Polymorphic  (slender,   intermediate  and  stumpy  forms). 

(1)  BRUCEI  SUBGROUP 

Polymorphism  constant  (stumpy  forms  always  present). 
T.  brucei  of  all  domestic  animals,  antelope. 
T.  rhodesiense  of  man,  bushbuck  and  probably  antelope. 
T.  gambiense  of  man. 

(2)  EVANSI  SUBGROUP 

Polymorphism  inconstant  (stumpy  forms  rare  or  sporadic);  no 
cyclic  development  in  vector  host. 

(a)  Transmission  mechanical  by  insects. 

T.  efflnsi of  cattle,  camels,  equids,  dogs,  etc. 
T.  equinum  of  equids. 

(b)  Transmission  by  contact  (coitus)  from  mammal  to  mammal. 
T.  equiperdum  of  equids. 

II.      PARASITES  OF  BIRDS 

Very  polymorphic,  sometimes  attaining  great  size.    Relatively  easy  to  cultivate. 
Cyclic  development  probably  in  biting  arthropods. 

AVIUM  GROUP 

T.  avium  of  various  birds. 
T.  calmettei  of  chickens. 
T.  gallinarum  of  chickens. 
T.  hannai of  pigeons . 
T.  numidae  of  guinea  fowl. 


Fig.   2.       Species  of  Trypanosoma.     A.    T.   llwilcri.     B.    T.  cnizi.     C.    T.  coiigoleiise. 
D.    T.   vivax.     E.    T.  equiperduvi .     F.    T.   bnicei.     X  2800.     (Original) 


THE  HEMOFLAGELLATES 


47 


In  the  discussion  which  follows,  each 
trypanosome  species  is  taken  up  separ- 
ately, but  special  attention  is  paid  to 
T.   briicei  and  T.  criizi  as  representatives 
of  different  types. 


TRYPANOSOMA  BRUCEI 
PLIMMER  AND   BRADFORD,   1899 

Synonym :      T.  pecaudi. 

Disease:     Trypanosomosis,  nagana. 

Hosts:     Horse,   mule,  donkey,  ox, 
zebu,   sheep,  goat,  camel,   pig,  dog,   and 
many  wild  game  animals.     Antelopes  are 
the  natural  hosts  of  T.  brncei  and  serve 
as  reservoirs  of  infection  for  domestic 
animals.     Experimental  attempts  to  infect 
man  have  failed  (Ashcroft,   1959a). 

Location:      Blood  stream,   lymph, 
cerebrospinal  fluid. 

Geographic  Distribution:     Widely  dis- 
tributed in  tropical  Africa  between  15^  N 
and  25°  S  latitude,   coinciding  with  the  dis- 
tribution of  its  vector,  the  tsetse  fly. 

Prevalence:     T.   brucei  is  one  of  the 
commonest  and  most  important  parasites 
of  domestic  animals  in  Africa.    It  has  pre- 
vented the  raising  of  livestock  in  vast 
areas. 


Morphology:      Polymorphic,  with 
slender,  intermediate  and  stumpy  forms. 
Undulating  membrane  conspicuous.    Ki- 
netoplast  small,   subterminal.     Slender 
forms  average  29 /i  in  length  but  range  up 
to  42  (i;  posterior  end  usually  drawn  out, 
tapering  almost  to  a  point,  with  kineto- 
plast  up  to  4jj,  from  posterior  end,  with  a 
long,  free  flagellum.     Stumpy  forms  stout, 
averaging  18  ju  in  length  with  a  range  of 
12  to  26 /i;  posterior  end  broad,  obtusely 
rounded,  with  kinetoplast  almost  terminal; 
free  flagellum  typically  absent.     Interme- 
diate forms  average  23  jj.  in  length;  body 
of  medium  thickness,  with  blunt  posterior 
end;  moderately  long  free  flagellum  al- 
ways present.     A  fourth  form  with  a 
posterior  nucleus  often  appears  in  labor- 
atory animals. 


Life  Cycle:     When  it  is  first  intro- 
duced into  the  body,    T.  bnicei  multiplies 
in  the  blood  and  lymph  by  longitudinal 
binary  fission  in  the  trypanosome  stage, 
being  particularly  common  in  the  lymph 
glands.     Later  the  trypanosomes  pass  into 
the  cerebrospinal  fluid  and  multiply  here 
and  between  the  cells  of  the  brain.     Leish- 
manial forms  have  also  been  reported 
from  the  heart  muscle  of  infected  monkeys 
(Noble,   1955). 

The  vector  is  a  tsetse  fly  of  the  genus 
Glossina.     T.  brucei  is  generally  trans- 
mitted by  members  of  the  iiiorsifans  group 
of  this  genus,   i.e.,    G.  uiorsilaiis,   G. 
sivynnertoni  and  G.  pallidipes.     Both  males 
and  females  feed  on  blood  and  act  as  vec- 
tors.    Only  a  small  percentage  of  the  tsetse 
flies  which  feed  on  an  infected  animal  be- 
come infected,  most  being  apparently  re- 
sistant.    In  experimental  studies,   10%  or 
less  become  infected,  while  less  than  1% 
of  wild  flies  caught  in  endemic  areas  are 
infected. 

When  ingested  by  a  tsetse  fly,   T.  bru- 
cei localizes  in  the  posterior  part  of  the 
midgut  and  multiplies  in  the  trypanosome 
form  for  about  10  days.     At  first  the  try- 
panosomes are  relatively  broad,  up  to 
35/i  long,  with  a  kinetoplast  about  halfway 
between  the  posterior  end  of  the  body  and 
the  nucleus,  with  a  less  pronounced  undu- 
lating membrane  than  the  blood  form,   and 
with  a  free  flagellum.     On  the  10th  to  12th 
day,   slender  forms  appear  and  migrate 
slowly  toward  the  proventriculus,  where 
they  are  found  on  the  12th  to  20th  days. 
They  then  migrate  forward  into  the  esopha- 
gus and  pharynx,  thence  into  the  hypopharynx 
and  finally  into  the  salivary  glands.     Here 
they  attach  themselves  to  the  walls  by  their 
flagella  or  lie  free  in  the  lumen,  and  turn 
into  the  crithidial  form.     These  multiply 
further  and  then  transform  into  the  meta- 
cyclic  trypanosome  form,  which  is  small, 
stumpy,   and  may  or  may  not  have  a  short 
free  flagellum. 

The  metacyclic  trypanosomes  are  the 
infective  forms.     They  are  injected  into  the 
blood  with  the  saliva  when  the  fly  bites;  up 
to  several  thousand  may  be  introduced  by 
the  bite.    The  whole  life  cycle  in  the  tsetse 


48 


THF.  HIMOFLACELLATES 


fly  takes  15  to  35  days,  and  the  flies  are 
not  infective  until  the  metacyclic  trypano- 
somes  have  appeared  in  the  salivary  glands. 

This  type  of  development,  in  which  the 
trypanosomes  are  found  in  the  anterior 
part  of  the  vector  and  are  introduced  by 
its  bite,   is  known  as  development  in  the 
anterior  station  to  contrast  it  with  devel- 
opment in  the  posterior  station  or  hindgut. 
In  the  latter,  exemplified  by  the  lewisi 
group,  infection  is  by  contamination  with 
feces. 

In  addition  to  the  cyclical  transmis- 
sion described  above,  T.   briicei  may  oc- 
casionally be  transmitted  mechanically  by 
tsetse  flies  or  other  biting  flies.    In  this 
case,  the  trypanosomes  remain  alive  in 
the  proboscis  for  a  short  time  and  are 
transferred  to  a  new  host  if  the  fly  bites  it 
soon  enough  after  having  bitten  an  infected 
one. 


mrtacjclic 


crithUiat* 


Fig.   3.       Simplified  life  cycle  of  Trypano- 

sotna  briicci.     (From  Noble,   1955) 


Pathogenesis:    The  signs  and  patho- 
genesis of  the  trypanosomoses  of  domestic 


animals  are  more  or  less  similar.    Dif- 
ferent hosts  are  affected  to  different  de- 
grees.   Horses,  mules  and  donkeys  are 
very  susceptible  to  T.  briicei.    Affected 
animals  have  a  remittent  fever,  edema- 
tous swellings  of  the  lower  abdomen,   gen- 
italia and  legs,  a  watery  discharge  from 
the  eyes  and  nose,  and  anemia.     The  ani- 
mals become  emaciated  altho  their  appe- 
tite is  good.     Muscular  atrophy  sets  in, 
and  eventually  incoordination  and  lumbar 
paralysis  develop,  followed  by  death.    The 
course  of  the  disease  is  15  days  to  4 
months,  and  untreated  animals  rarely  re- 
cover. 

The  disease  in  sheep,  goats,  camels 
and  dogs  is  also  severe.  The  signs  are 
much  the  same  as  in  horses.  In  the  dog, 
fever  may  appear  as  shortly  as  five  days 
after  infection,  and  the  parasites  often 
cause  conjunctivitis,  keratitis  and  blind- 
ness. 

The  disease  is  usually  more  chronic 
in  cattle.  There  is  remittent  fever  with 
swelling  of  the  brisket,  anemia,  gradual 
emaciation,  and  discharge  from  the  eyes 
and  nose.  The  animals  may  survive  for 
several  months.  Swine  are  more  resistant 
than  cattle  and  usually  recover. 

Following  infection,  the  trypanosomes 
appear  first  in  the  blood  and  lymph,  caus- 
ing fever,  edema,  anemia,  etc.   and  only 
later  on  are  they  able  to  invade  the  central 
nervous  system,  causing  incoordination, 
paralysis  and  meningo-encephalitis. 

The  exact  way  in  which  they  act  to  kill 
their  victims  is  unknown,   altho  several 
theories  have  been  advanced.    It  is  known 
that  they  have  a  high  glucose  metabolism, 
and  one  theory  was  that  they  rob  the  body 
of  glucose  so  that  death  is  due  to  hypo- 
glycemia.   In  experimental  animals,   life 
can  be  prolonged  by  feeding  glucose  and 
shortened  by  injecting  insulin.     This 
theory,  however,  has  been  discredited. 

It  is  known  that  the  serum  potassium 
level  increases  in  trypanosomosis,  and 
another  theory  was  that  the  effects  are  due 
to  the  high  potassium  level.     However,  the 
latter  is  a  result  of  the  disease  and  not  a 


THE  HEMOFLAGELLATES 


49 


cause.    It  is  due  to  the  destruction  of  red 
cells  with  consequent  release  of  potassium 
into  the  plasma,   and  the  observed  levels 
are  not  too  harmful. 

Epidemiology:     The  epidemiology  of 
the  diseases  caused  by  T.   briicei  and  other 
tsetse-borne  trypanosomes  depends  upon 
the  bionomics  and  distribution  of  their 
vectors.    This  is  such  a  vast  subject  that 
no  attempt  will  be  made  to  cover  it  here. 
In  general,  tsetse  flies  occupy  almost  4 
million  square  miles  of  Africa.     They 
occur  in  woodlands,  bush  or  forested  areas 
where  there  is  ample  rainfall  and  where 
the  mean  annual  temperature  is  above 
about  70°  F.     Not  all  species  are  good  vec- 
tors, and  trypanosomosis  does  not  occur 
every  place  that  tsetse  flies  do.     For  fur- 
ther information  on  tsetse  flies  and  the 
epidemiology  of  trypanosomosis,  see 
Buxton  (1948,   1955,   1955a),   Hornby  (1949, 
1952),  Davey  (1958)  and  Ashcroft  (1959). 

Diagnosis:     In  the  acute  or  early  stage 
of  the  disease,  trypanosomes  can  be  found 
in  the  peripheral  blood.    Thick  blood 
smears  are  preferable  to  thin  ones.    The 
protozoa  are  found  even  more  often  in  the 
lymph  glands.    They  can  be  detected  in 
fresh  or  stained  smears  of  fluid  obtained 
by  puncture  of  the  glands.    In  the  later 
stages  of  the  disease,  trypanosomes  can 
be  found  in  the  cerebrospinal  fluid.     Lab- 
oratory animals  such  as  the  rat  can  also 
be  inoculated.     The  complement  fixation 
test  can  also  be  used;  it  is  not  specific 
for  T.   brucei  infections,  but  also  reacts 
in  a  number  of  other  trypanosomoses. 

Cultivation:     Trypanosomes  can  be 
successfully  cultivated  in  a  number  of 
media.     A  common  one  is  NNN  medium, 
which  is  essentially  a  25%  blood  agar 
slant.     Another  medium  is  that  of  Weinman 
(1946),  which  contains  beef  extract,   pep- 
tone, washed  erythrocytes  and  plasma. 
Still  another  is  that  of  Tobie,  von  Brand 
and  Mehlman  (1950).     A  discussion  of 
problems  of  cultivation  and  diagnosis  is 
given  by  Weinman  (1953). 

Trypanosomes  can  also  be  cultivated 
in  developing  chick  embryos  or  in  tissue 
culture.     See  Pipkin  (1960)  for  a  review 
of  this  subject. 


Treatment:     Many  different  drugs  have 
been  used  in  the  treatment  of  trypanoso- 
mosis.   Indeed,  the  first  synthetic  organic 
compound  of  known  composition  ever  used 
to  cure  an  experimental  disease  was  try- 
pan red,  which  was  developed  by  Ehrlich 
and  Shiga  (1904).    Since  that  time  thousands 
of  drugs  have  been  found  to  show  some  ac- 
tivity, but  the  number  of  satisfactory  ones 
is  very  small.    The  chemotherapy  of  try- 
panosomiasis has  been  reviewed  by  Findlay 
(1950),  Ing  (1953),   Browning  (1954),  Good- 
win and  RoUo  (1955),  Davey  (1957),  and 
others. 

Altho  much  of  the  earlier  work  on 
chemotherapy  was  done  on  members  of 
ihebyncei  subgroup,  most  of  that  since 
World  War  n  on  trypanosomosis  of  live- 
stock has  dealt  with  the  vivax  and  coiigo- 
lense  groups. 

Antrycide  methyl  sulfate  is  perhaps 
the  drug  of  choice  for  T.   brucei  in  horses. 
It  is  injected  subcutaneously  at  the  rate 
of  5  mg/kg  body  weight;  two  treatments 
may  be  given  4  days  apart.     Antrycide  is 
also  effective  against  T.   brucei  in  dogs, 
cattle  and  other  animals. 

Suramin  (Germanin,   Naganol,   Antry- 
pol,   Moranyl,   Bayer  205,   Fourneau  309, 
etc. )  has  been  used  for  many  years.     A 
single  dose  of  4  g  per  1000  lb  body  weight 
is  given  intravenously  to  horses,  but  it 
may  be  toxic  in  some  animals.    In  dogs, 
5  mg/kg  is  given  intravenously. 

The  diamidines,  pentamidine  and 
stilbamidine,   have  been  used  extensively 
against  T.  ga)iibie)2se  and  T.   rhodesiense 
in  man,  but  have  been  used  very  little  in 
veterinary  medicine.     Another  diamidine, 
Berenil,  appears  promising  against  T. 
brucei,  but  needs  more  study. 

Control:      Preventive  measures 
against  trypanosomosis  include  measures 
directed  against  the  parasite,  measures 
directed  against  the  intermediate  hosts, 
livestock  management,  elimination  of 
reservoir  hosts,  and  avoidance  of  acci- 
dental,  mechanical  contamination. 

Measures  directed  against  the  para- 
site include  continuous  survey  and  treat- 


so 


THE  HEMOFIAGEXLATES 


ment  or  slaughter  of  all  affected  animals 
and  periodic  mass  prophylactic  treatment 
of  all  animals.    The  latter  is  discussed  in 
the  section  on  treatment  of  T.  congolense. 

Fly  traps  and  fly  repellents  have  been 
used  without  much  success  in  attempting 
to  control  tsetse  flies.     Elimination  of 
breeding  places  has  been  practiced  on  a 
wide  scale  in  many  areas.     Since  the  tsetse 
flies  breed  under  brush  along  streams  or 
in  other  localities,   such  measures  consist 
essentially  of  brush  removal.    Two  meth- 
ods are  used: 

Eradicative  clearing  aims  at  eradica- 
tion of  tsetse  flies  thruout  an  area.     All 
the  species  of  trees  and  shrubs  under  which 
the  flies  survive  thru  the  dry  season  are 
removed.    When  this  is  done  thoroughly 
over  a  large  area,  the  flies  disappear  com- 
pletely. 

Protective  clearing  is  more  limited. 
It  is  designed  to  break  the  contacts  between 
tsetse  flies  and  domestic  animals  and  man 
at  the  places  where  transmission  is  taking 
place.     Fly-free  belts  wide  enough  so  that 
the  flies  cannot  cross  them  are  established. 
In  addition,  inspection  stations  known  as 
deflying  houses  may  be  set  up  on  traffic 
routes  to  remove  flies  which  may  be  car- 
ried across  on  vehicles  or  animals. 

Bush  clearing  can  be  quite  successful. 
The  incidence  of  trypanosomosis  was  re- 
duced by  92%  between  1938  and  1944  in  the 
Kamba  area  of  Africa  by  this  means 
(Morris,   1946).     However,  it  is  expensive, 
requires  a  large  amount  of  labor,  and  the 
initial  clearing  must  be  followed  up  faith- 
fully as  new  growth  occurs. 

A  potentially  much  more  satisfactory 
control  measure  is  the  spraying  of  insec- 
ticides on  fly  breeding  places  by  means  of 
aircraft.    DDT  and  benzene  hexachloride 
are  highly  effective  for  this  purpose. 
Glossina  pallidipes  was  eradicated  from 
Zululand  by  airplane  spraying  with  these 
insecticides  at  a  total  cost  of  2.  5  million 
pounds,  or  slightly  less  than  2  shillings 
per  acre  (DuToit,   1959). 

Since  tsetse  flies  bite  only  in  the  day- 
time, night  grazing  has  been  practiced  by 


African  natives  to  avoid  their  bites.    The 
animals  are  held  in  a  protected  corral 
during  the  day. 

Cattle  can  be  sprayed  with  DDT  or 
another  insecticide  in  order  to  kill  any 
tsetse  flies  which  light  on  them. 

The  elimination  of  reservoir  hosts, 
e.  g.  ,  wild  game  in  Africa,   has  been  ad- 
vocated and  practiced  in  some  regions 
despite  the  protests  of  many  people  inter- 
ested in  game  preservation.     The  Trypan- 
osomiasis Committee  of  Southern  Rhodesia 
(1946)  has  described  and  defended  the  prac- 
tice.   It  claims  that  if  a  zone  10  miles 
wide  with  its  ends  in  fly-free  country  is 
fenced  off  and  all  the  game  within  it  is 
killed,   Glossina  morsitans  will  disappear 
in  less  than  10  years.     The  fences  can 
then  be  removed  and  the  game  allowed  to 
return  into  the  area. 

Since  trypanosomes  can  be  transmitted 
mechanically  by  inoculation  of  infected 
blood  or  lymph,  there  is  danger  of  its 
transmission  by  the  use  of  contaminated 
instruments  in  bleeding,   castrating,   etc. 

A  great  deal  has  been  written  on  try- 
panosomosis control.     For  further  infor- 
mation,  see  Hornby  (1949,   1952),   Morris 
(1946),   Buxton  (1948,   1955)  and  the  pro- 
ceedings of  the  meetings  of  the  International 
Scientific  Committee  for  Trypanosomiasis, 
which  held  its  sixth  meeting  in  1956. 


TRYPANOSOMA   GAMBIENSE 
DUTTON,   1902 

TR  Y'PANOSOMA  RHODESIENSE 
STEPHENS  AND   FANTHAM,   1910 

These  two  species  cause  African 
sleeping  sickness  in  man.    T.  rliodesiense 
is  thought  to  occur  also  in  antelopes 
(Hoare,   1955)  and  was  isolated  once  from 
a  bushbuck  (Heisch,   McMahon  and  Manson- 
Bahr,   1958).    T.  ganibiense   does  not  occur 
in  wild  game.     Neither  occurs  in  domestic 
animals.    They  are  morphologically  indis- 
guishable  from  each  other  and'from  T. 
brucei,  and  for  this  reason  some  people 
prefer  to  consider  all  three  as  subspecies 
of  T.  brucei.    However,  the  biological  and 


THE  HEMOFLAGELLATES 


51 


epidemiologic  differences  between  them 
make  it  more  convenient  to  retain  separ- 
ate names.    Whatever  the  names  used,  it 
is  clear  that  these  species  arose  from 
strains  of  T.   brucei  which  became  adapted 
to  man. 

Human  trypanosomosis  occurs  in 
tropical  Africa,   roughly  between  15°  N 
and  15°  S  latitude.     T.   yliodesiense,  which 
causes  an  acute  form  of  the  disease, 
occurs  in  Rhodesia,  Tanganyika,  Nyasa- 
land,   Bechuanaland  and  Portuguese  East 
Africa,  while  T.  gambiense,  which  causes 
a  chronic  form  of  the  disease,  occurs  in 
a  large  part  of  the  remainder  of  the  area. 
Kunert  (1953)  prepared  a  map  of  the  dis- 
tribution of  human  sleeping  sickness  in 
Africa  together  with  climatologic  and 
other  information.     Ashcroft  (1959a)  and 
Morris  (1960)  reviewed  its  epidemiology. 

In  general,    T.  gambiense  causes  a 
"domesticated"  type  of  disease,  trans- 
mitted by  tsetse  flies  from  man  to  man  in 
regions  of  human  habitation,  while  T. 
rhodesiense  causes  more  of  a  woodland 
disease  and  people  become  infected  with 
it  away  from  their  village  areas. 

Altho  it  is  certain  that  some  wild  ani- 
mals must  serve  as  reservoirs  of  Trypano- 
soma rhodesiense,    it  has  been  isolated 
from  them  only  once.     Heisch,  McMahon 
and  Manson-Bahr  (1958)  isolated  it  from 
a  bushbuck  (  Tragelaphus  scriptus)  in 
Kenya  by  inoculation  of  a  human  volunteer. 

Epidemiologic  evidence  for  a  wild 
animal  reservoir  is  exemplified  by  the  ob- 
servation that  every  year  fishermen  and 
honey  hunters  become  infected  with  T. 
rhodesiense  near  the  Ugalla  River  in  the 
Western  Province  of  Tanganyika,  yet  this 
is  an  uninhabited  region,  and  no  people 
are  there  at  all  during  the  6-month  rainy 
season.     The  Ugalla  River  is  part  of  the 
Malagarasi  river  system  of  the  Western 
Province.    It  runs  thru  a  sparsely  popu- 
lated, woodland  region  inhabited  by  many 
wild  animals  and  infested  with  Glossina 
morsitans .    Jackson  (1955)  described  25 
cases  of  sleeping  sickness  in  fly-boys 
stationed  in  remote  outposts  in  this  area 
between  1935  and  1939,  and  concluded 


that  there  was  strong  evidence  that  game 
was  acting  as  a  reservoir.    Over  half  the 
cases  of  T.   rhodesiense  infection  diag- 
nosed in  Africa  in  1953,   1954  and  1955 
were  contracted  in  this  region  (Ashcroft, 
1958);  2069  cases  were  reported  in  the 
Western  Province  in  these  years  (Apted, 
1955). 

The  only  way  to  be  positive  that  a 
brucei-Hyie  strain  of  trypanosome  isolated 
from  wild  animals  is  actually  T.   rhodesi- 
ense is  to  inoculate  human  volunteers  with 
it,  and  very  few  such  attempts  have  been 
made.    In  one  of  the  latest  of  these,  Ash- 
croft (1958)  inoculated  a  strain  which  he 
had  isolated  from  a  Coke's  hartebeest 
{Alcelaphus  cokei)  in  Tanganyika  into  2 
African  volunteers,  but  no  infection  re- 
sulted and  he  concluded  that  the  organism 
was  T.  brucei. 

The  life  cycles  of  the  human  trypano- 
somes  are  the  same  as  that  of  T.  brucei. 
The  vectors  are  species  of  tsetse  flies  of 
the  genus  Glossina.    The  chief  vectors  of 
T.  gambiense  are  the  riverine  tsetse  flies, 
G.  palpalis  and  G.   tachinoides,  while 
those  of  T.   rhodesiense  are  the  game 
tsetse  flies,    G.   morsitans,   G.  swynner- 
toni  and  G.  pallidipes. 

Human  trypanosomosis  is  similar  to 
nagana  in  its  manifestations.     For  further 
information,  any  human  parasitology  text 
may  be  consulted. 


TRYPANOSOMA  EVANSI 
(STEEL,   1885)  BALBIANI,   1888 

Synonyms:      T.  soudanense,    T. 
elepfiantis,    T.  annamense,    T.  cameli, 
T.  marocanum,    T.  ninae  kohl-yakimov, 
T.  aegyptum,    T.  hippicum,    T.  venezue- 
lense. 

Disease:     Trypanosomosis  due  to 
T.   evansi  has  been  given  different  names 
in  different  localities.    The  most  widely 
used  name,   surra,   is  applied  to  the  dis- 
ease in  all  hosts.     The  disease  in  camels 
is  called  el  debab  in  Algeria  and  mbori  in 
Sudan.     That  in  horses  is  called  murrina 
in  Panama  and  derrengadera  in  Venezuela. 


52 


THE  HEMOFLAGELLATES 


Hosts:     Camels,  horse,  donkey,  ox, 
zebu,  goat,   pig,  dog,  water  buffalo,  ele- 
phants,  capybara,  tapir,   and  (in  Mauri- 
tius) deer. 

Location:      Blood,   lymph. 

Geographic  Distribution:     Northern 
Africa  (north  of  15    N  latitude  in  the  west 
and  central  part  of  the  continent,  but  ex- 
tending almost  to  the  equator  in  the  east), 
Asia  Minor,   U.S.S.R.  from  the  Volga 
River  east  into  Middle  Asia,  India,  Burma, 
Malaya,  Indochina,   parts  of  southern 
China,  Indonesia,   Philippines,   Central 
America,  South  America.     Hoare  (1956) 
has  shown  how  the  original  distribution  of 
T.   evansi  coincided  with  that  of  the  camel. 
In  Africa,   its  southern  boundary  coincides 
roughly  with  the  northern  boundary  of 
tsetse  fly  distribution.    It  now  extends  far 
to  the  east  of  the  camel's  range  in  the  Old 
World.    It  is  often  associated  with  arid 
deserts  and  semi-arid  steppes,  but  may 
occur  in  other  types  of  climate  as  well. 
In  India,  it  is  most  common  in  the  Punjab, 
which  is  mostly  in  the  northwestern  dry 
region  (Basu,   1945;  Basu,   Menon  and  Sen 
Gupta,   1952).     It  was  probably  introduced 
into  the  New  World  in  infected  horses  by 
the  Spanish  conquerors  during  the  16th 
century. 

Prevalence:  T.  evansi  is  an  impor- 
tant cause  of  disease  over  a  large  part  of 
its  range. 

Morphology:     The  morphology  of  the 
Old  World  strains  of  T.  evansi  has  been 
studied  intensively  by  Hoare  (1956).     The 
mean  length  of  different  host  and  geo- 
graphic strains  varies  considerably.    How- 
ever, the  typical  forms  are  15  to  34  ji 
long,  with  a  mean  of  24  |i.    Most  are  slen- 
der or  intermediate  in  shape,  but  stumpy 
forms  occur  sporadically.     All  forms  are 
morphologically  indistinguishable  from 
the  corresponding  ones  of  T.   briicei. 
Strains  which  lack  a  kinetoplast  have  oc- 
casionally arisen  spontaneously  or  can  be 
produced  by  treatment  with  certain  dyes 
(Hoare,   1954). 

Life  Cycle:      T.   evansi  is  transmitted 
mechanically  by  biting  flies.     No  cyclic 


development  takes  place  in  the  vectors, 
the  trypanosomes  remaining  in  the  pro- 
boscis.   The  usual  vectors  are  horseflies 
of  the  genus  Tabanus,   but  Stomoxys, 
Haematopola  and  Lyperosia  can  also  trans- 
mit it.     In  Central  and  South  America,  the 
vampire  bat  is  a  vector,  the  disease  in 
this  case  being  known  as  murrina. 

Pathogenesis:     Surra  is  nearly  always 
fatal  in  horses  in  the  absence  of  treatment; 
death  occurs  in  a  week  to  six  months.     The 
disease  is  also  severe  in  dogs  and  elephants. 
It  is  less  severe  in  cattle  and  water  buffalo. 
Cattle  may  carry  the  parasites  without 
showing  signs  of  disease  for  months.    How- 
ever, occasional  outbreaks  of  acute  disease 
occur  in  cattle  and  water  buffalo.    Surra  in 
camels  is  similar  to  the  disease  in  horses 
but  more  chronic.    In  dogs,    T.   evansi 
causes  a  chronic  disease  with  a  high  mor- 
tality rate;  untreated  dogs  usually  die  in  1 
to  2  months  (Gomez  Rodriguez,   1956). 

The  signs  of  surra  include  intermittent 
fever,  urticaria,  anemia,  edema  of  the  legs 
and  lower  parts  of  the  body,  loss  of  hair, 
progressive  weakness,   loss  of  condition 
and  inappetence.     Conjunctivitis  may  occur, 
and  abortion  is  common  in  camels. 

The  lesions  include  splenomegaly,  en- 
largement of  the  lymph  glands  and  kidneys, 
leucocytic  infiltration  of  the  liver  paren- 
chyma,  and  petechial  hemorrhages  and 
parenchymatous  inflammation  of  the  kidneys. 

Diagnosis:     Same  as  for  T.  brucei. 

Cultivation:     Same  as  for  T.  brucei. 

Treatment:     Treatment  of  T.   evansi 
is  similar  to  that  of  T.   brucei.    Antrycide 
methyl  sulfate  is  less  toxic  than  suramin 
for  horses;  a  single  subcutaneous  dose  of 
5  mg/kg  or  even  less  is  effective.     A  dose 
of  3  mg/kg  has  given  good  results  in  cattle. 
A  single  injection  of  2  g  is  effective  in 
camels. 

The  dose  of  suramin  for  horses  is  4  g 
per  1000  lb  body  weight  intravenously. 
Camels  tolerate  suramin  well,  and  a  single 
intravenous  injection  of  4  to  5  g  is  effective 
against  surra  in  these  animals.    Tartar 


THE  HEMOFLAGELLATES 


53 


emetic,  which  has  been  largely  superseded 
in  other  animals,   is  still  used  in  treating 
surra  in  the  camel;  a  single  intravenous 
injection  of  200  ml  of  a  1%  solution  is 
given.     This  drug  is  also  widely  used  in 
cattle  in  India  because  of  its  cheapness. 

Control:     Essentially  the  same  meas- 
ures used  in  the  control  of  T.  brncei.    ex- 
cept of  course  those  directed  against  the 
tsetse  fly,   can  be  used  in  the  control  of 
T.   evansi  infections.     Control  of  horse- 
flies and  other  biting  flies  is  important. 

Remarks:      Hoare  (1956,   1957)  has 
discussed  the  phytogeny  of  T.   evansi. 
This  species  undoubtedly  arose  from  T. 
briicei,   being  introduced  into  camels  when 
they  entered  the  tsetse  fly  belt  and  then 
becoming  adapted  to  mechanical  transmis- 
sion by  tabanids. 


TRYPANOSOMA  EQUINUM 
VOCES,   1901 

This  species  occurs  in  South  America, 
where  it  causes  a  disease  known  as  mal  de 
Caderas  in  horses.     The  disease  is  similar 
to  surra.     T.   equimim  differs  morpholog- 
ically from  T.   evansi  only  in  lacking  a 
kinetoplast.     However,   strains  of  T.  evansi 
without  a  kinetoplast  have  appeared  in  the 
laboratory,  and  T.  eqidnuni  undoubtedly 
originated  in  this  way. 

T.   equimim  is  transmitted  mechan- 
ically by  tabanids.     Both  antrycide  methyl 
sulfate  and  suramin  can  be  used  in  treat- 
ing it.     The  former  is  less  toxic.     A  single 
subcutaneous  dose  of  5  mg/kg  or  less  of 
antrycide  methyl  sulfate  or  a  single  intra- 
venous dose  of  4  g  per  1000  lb  body  weight 
of  suramin  can  be  used.     Control  measures 
are  the  same  as  for  T.  evansi, 


TRYPANOSOMA  EQUIPERDUM 
DOFLEIN,    1901 

'I'his  species  is  morphologically  indis- 
tinguishable from  T.   evansi.     It  causes  a 
disease  of  horses  and  asses  known  as 
dourine.    This  is  a  venereal  disease, 
transmitted  by  coitus.    Dourine  is  similar 


to  nagana,  but  runs  a  more  chronic  course 
of  6  months  to  2  years.    The  incubation 
period  is  2  to  12  weeks. 

The  first  sign  of  the  disease  is  edema 
of  the  genitalia  and  often  of  the  dependent 
parts  of  the  body.     There  is  slight  fever, 
inappetence,   and  a  mucous  discharge  from 
the  urethra  and  vagina.     Circumscribed 
areas  of  the  mucosa  of  the  vulva  or  penis 
may  become  depigmented. 

The  second  stage  of  the  disease, 
characterized  by  urticaria,   appears  after 
4  to  6  weeks.     Circular,   sharply  circum- 
scribed, urticarial  plaques  about  3  cm  in 
diameter  arise  on  the  sides  of  the  body, 
remain  3  or  4  days,   and  then  disappear. 
They  may  reappear  later.     Muscular  pa- 
ralysis later  ensues.     The  muscles  of  the 
nostrils  and  neck  are  affected  first,  but 
the  paralysis  spreads  to  the  hind  limbs 
and  finally  to  the  rest  of  the  body.    Inco- 
ordination is  seen  first,  and  is  followed 
by  complete  paralysis.    Dourine  is  usually 
fatal  unless  treated,  altho  mild  strains  of 
the  parasite  may  occur  in  some  regions. 

T.   equiperdum  is  found  in  Asia,   North 
and  South  Africa,   southern  and  eastern 
Europe  and  the  U.  S.  S.  R.     It  was  once 
common  in  western  Europe  and  North 
America,  but  has  been  eradicated  from 
these  regions.    The  last  place  where  it 
was  known  to  occur  in  North  America,  the 
Papago  Indian  Reservation  in  Arizona,  was 
released  from  quarantine  in  1949. 

Dourine  can  be  diagnosed  by  finding 
the  parasites  in  smears  of  fluid  expressed 
from  the  urticarial  swellings,  lymph,  the 
mucous  membranes  of  the  genitalia  or 
blood.    The  signs  of  the  typical  disease  are 
characteristic  enough  to  permit  diagnosis 
in  endemic  areas.    Inoculation  of  mice, 
rats,  rabbits  or  dogs  may  also  be  prac- 
ticed, but  it  is  often  difficult  to  demonstrate 
the  parasites  on  the  first  passage.     The 
complement  fixation  test  is  invaluable  in 
detecting  early  or  latent  infections,  and  it 
was  only  by  its  use  that  dourine  was  erad- 
icated from  North  America.     All  horses 
imported  into  the  United  States  must  be 
tested  for  dourine  before  they  are  ad- 
mitted. 


S4 


THE  HEMOFLAGELLATES 


To  treat  dourine  in  horses,  a  single 
subcutaneous  dose  of  5  mg/kg  antrycide 
methyl  sulfate  or  two  intravenous  injec- 
tions of  2  g  suramin  each  15  days  apart 
can  be  used. 


TRYPANOSOMA   SUIS 
OCHMANN,   1905 

This  species,  which  was  once  thought 
to  be  the  same  as  T.  siniiae,    was  redis- 
covered in  the  Belgian  Congo  by  Peel  and 
Chardome  (1954).    It  is  a  member  of  the 
brute i  group,  but  differs  from  the  others 
in  being  monomorphic,   having  only  stout 
forms  14  to  19  ji  long,  with  a  short,  free 
flagellum.     The  kinetoplast  is  very  small 
and  marginal. 

T.  si</s  occurs  in  pigs,   causing  a 
chronic  infection  in  adults  and  a  more 
acute  disease  with  death  in  less  than  2 
months  in  young  pigs.     Peel  and  Chardome 
attempted  without  success  to  transmit 
T.  suis  to  the  goat,  sheep,  dog,  white  rat, 
guinea  pig,    Cricetomys  gambianus ,  Den- 
drohyrax,   chimpanzee,  cat,   rabbit,   cattle, 
monkey  and  ass.    It  is  transmitted  by  the 
tsetse  fly,  Glossina  brevipalpis,   in  which 
it  develops  first  in  the  intestine  and  pro- 
ventriculus  and  then  in  the  salivary 
glands.    Metacyclic  infectious  trypano- 
somes  appear  in  the  hypopharynx  on  the 
28th  day. 


TR  YPANOSOMA 
BRODEN,    1904 


CONGOLENSE 


Synonyms:      Trypanosoma  nanum, 
T.   confiisiun,    T.  pecorimi,    T.  somaliense, 
T.  cellu,   T.  frobeniusi,   T.  monlgomeryi, 
T.   ruandae. 

Disease:     The  South  African  disease 
of  cattle  known  as  nagana  is  ordinarily 
caused  by  T.  cotigolense.     Other  names 
which  have  been  given  to  the  disease  are 
paranagana,  Gambia  fever,  ghindi  and 
gobial. 

Hosts:     Cattle,  equids,  sheep,  goats, 
camels,  dogs  and,  to  a  lesser  extent, 
swine.    Antelopes,  giraffes,  zebras. 


elephants  and  wart  hogs  are  also  infected 
and  act  as  reservoirs. 

Location:     This  species  develops 
almost  exclusively  in  the  blood.     It  does 
not  invade  the  lymph  or  central  nervous 
system. 

Geographic  Distribution:     Widely 
distributed  in  tropical  Africa  between  15° 
N  and  25"  S  latitude,  coinciding  with  the 
distribution  of  the  tsetse  flies  which  act 
ad  its  vectors. 

Prevalence:     T.  co>igolense  is  the 
commonest  and  most  important  trypano- 
some  of  cattle  in  tropical  Africa. 

Morphology:     This  species  is  small, 
being  8  to  20|:i  long;  the  mean  lengths  of 
different  populations  range  from  12.2  to 
14.4|i  (Hoare,   1959).     It  lacks  a  free 
flagellum  or  has  a  short  one,  has  an  in- 
conspicuous undulating  membrane,  and  a 
medium-sized  kinetoplast  which  lies  some 
distance  from  the  posterior  end  and  is 
typically  marginal. 

Life  Cycle:     The  vectors  of   T.   con- 
golense  are  various  species  of  Glossina, 
including  G.  morsitans,   G.  palpalis,   G. 
longipalpis,   G.  pallidipes  and  G.  austeni. 
After  the  trypanosomes  have  been  ingested 
by  the  tsetse  flies,  they  develop  in  the 
midgut  as  long  trypanosomes  without  a 
free  flagellum.     They  then  migrate  to  the 
proventriculus  and  thence  to  the  proboscis, 
where  they  assume  a  crithidial  form  with- 
out a  free  flagellum.     These  are  attached 
at  first  to  the  wall  of  the  proboscis  and 
multiply  for  a  time.     Later  they  pass  into 
the  hypopharynx,  where  they  turn  into 
metacyclic,  infective  trypanosomes  sim- 
ilar in  appearance  to  the  blood  forms. 
These  are  injected  into  the  blood  stream 
when  the  flies  bite. 

T.   congolense  can  also  be  transmitted 
mechanically  by  other  biting  flies  in  tsetse- 
free  areas. 

Pathogenesis:  Many  strains  which 
differ  markedly  in  virulence  and  also  in 
antigenic  properties  are  united  under  T. 
congolense  (Fiennes,  1950).    In  cattle. 


THE  HEMOFLAGELLATES 


55 


the  parasite  may  cause  an  acute,  fatal 
disease  resulting  in  death  in  about  10  weeks, 
or  a  chronic  condition  with  recovery  in 
about  a  year,  or  a  mild,   almost  asympto- 
matic condition  (Hornby,   1949).     The  dis- 
ease is  similar  in  sheep,  goats,  camels 
and  horses.    Swine  are  more  resistant. 

The  signs  of  trypanosomosis  due  to 
this  species  are  similar  to  those  caused 
by  other  trypanosomes,  except  that  the 
central  nervous  system  is  not  affected. 

Fiennes  (1953)  described  the  lesions 
observed  in  untreated  T.  coiigolense  in- 
fections of  cattle.     The  lymph  nodes  are 
edematous,  the  liver  is  congested,  the 
marrow  of  the  long  bones  is  largely  des- 
troyed,  and  there  are  hemorrhages  in  the 
heart  muscle  and  renal  medulla.    In  cattle 
treated  with  antrycide  or  dimidium,  the 
lesions  are  more  chronic.    The  spleen  is 
enlarged,  the  liver  is  swollen  and  some- 
times fibrous,  the  lymph  nodes  are  hyper- 
trophied,  edematous  and  somewhat  fibro- 
tic,  the  kidneys  show  chronic  degenera- 
tion, the  hemolymph  tissue  is  hyperplas- 
tic, and  the  marrow  of  the  long  bones  is 
largely  destroyed. 

Fiennes  (1950),  described  a  cryptic 
form  of  trypanosomiasis  in  cattle,  usually 
following  drug  prophylaxis  or  unsuccessful 
drug  therapy,   in  which  severe  lesions 
occur  in  the  heart.    These  lesions  were 
associated  with  degenerate  or  lysed  try- 
panosomes, but  some  normal  forms  were 
also  present.    This  is  probably  similar  to 
the  condition  described  by  Curasson  (1943) 
and  Reichenow  (1952),  in  which  masses  of 
degenerating  trypanosomes  plug  the  capil- 
laries. 

Diagnosis:     This  disease  can  be  diag- 
nosed by  detection  of  the  parasites  in  blood 
smears.     Repeated  examinations  may  be 
necessary  in  chronic  cases.    Inoculation 
of  rats  or  guinea  pigs  may  give  positive 
results  when  blood  examinations  are  neg- 
ative. 

Cultivation:     Same  as  for  T.  brucei. 


T.   vivax  until  after  World  War  II.     Several 
drugs  have  been  introduced  since  then,  and 
active  research  is  still  going  on.     The  gen- 
eral pattern  has  been  similar.     Each  new 
drug  was  introduced  with  glowing  accounts 
of  its  effectiveness,   later  its  limitations 
were  discovered,  and  it  was  either  dropped 
or  assumed  its  place  in  the  trypanocidal 
armamentarium  while  the  search  passed 
on  to  a  new  field.    The  review  articles 
listed  under  treatment  of  T.  brucei  may  be 
consulted  for  further  information,  but 
progress  is  being  made  so  rapidly  that  both 
they  and  some  of  the  recommendations  be- 
low may  soon  be  out  of  date. 

Ethidium  is  the  most  effective  and 
safest  of  several  phenanthridinium  deriv- 
atives which  have  been  used.    Cattle  are 
treated  by  intramuscular  injection  of 
1  mg/kg  ethidium  bromide  or  chloride. 
The  tiypanosomes  disappear  from  the 
blood  within  2  days.     The  earlier  phenan- 
thridinium compounds  caused  photosen- 
sitization  and  liver  damage,  but  Ethidium 
apparently  does  not. 

Antrycide  methyl  sulfate  is  also  effec- 
tive against  T.  coiigolense.     Cattle  are 
treated  with  a  single  subcutaneous  injection 
of  4.  5  to  5.0  mg/kg,  while  3  to  5  mg/kg  is 
used  in  horses  and  dogs.     Antrycide  causes 
a  painful  local  reaction  when  given  subcu- 
taneously,   and  may  sometimes  also  cause 
increased  salivation,   sweating  and  tremors. 
In  addition,  there  are  a  number  of  reports 
of  drug-fastness  developing  to  antrycide. 

The  diamidine,   Berenil,   has  been  used 
with  success  in  preliminary  experiments, 
but  has  yet  to  be  completely  evaluated.    The 
dosage  for  cattle  is  about  2  mg/kg  subcu- 
taneously  or  intramuscularly. 

The  above  recommendations  deal  with 
curative  treatment.     A  great  deal  of  work 
has  also  been  done  on  chemical  prophylaxis 
of  trypanosomosis.    The  idea  here  is  to 
inject  drugs  in  relatively  insoluble  form  so 
that  they  will  be  released  slowly  over  a 
long  period  of  time  and  will  protect  animals 
for  months. 


Treatment:     No  effective  treatment 
was  known  for  either  T.  coiigolense  or 


Antrycide  chloride,  which  is  much  less 
soluble  than  antrycide  methyl  sulfate,   is 


56 


THE  HEMOFIAGELLATES 


used  for  prophylaxis.    In  actual  use,  a 
mixture  of  3  parts  of  the  methyl  sulfate 
and  4  of  the  chloride,  known  as  Antrycide 
prosalt,  is  employed.     The  methyl  sulfate 
eliminates  any  trypanosomes  that  might 
be  present  at  the  time  of  treatment,  and 
the  chloride  provides  the  prophylaxis.    The 
prosalt  is  injected  subcutaneously  in 
amount  sufficient  to  give  5  mg/kg  of  the 
methyl  sulfate.    In  areas  where  there  are 
relatively  few  tsetse  flies  (defined  as  an 
apparent  density  (AD)  of  less  than  10  flies 
caught  per  10,000  yards  of  patrol,  using  a 
standardized  catching  technic),  treatment 
every  2  months  is  effective,  but  under 
heavy  challenge  (defined  as  an  AD  of  40  or 
more)  this  protection  may  break  down. 

Prothidium  (R.D.   2801),  which  con- 
tains the  pyrimidine  moiety  of  Antrycide 
linked  to  a  phenanthridinium  instead  of  a 
quinoline  nucleus,  was  introduced  in  1956 
as  a  prophylactic  agent.     According  to 
Robson  and  Cawdery  (1958),   it  is  better 
than  Antcycide  prosalt,  a  single  subcutan- 
eous dose  of  4  mg/kg  protecting  zebus 
naturally  exposed  to  T.  congolense,    T. 
vivax  and  T.  brucei  injections  for  110  or 
more  days. 

Complexes  or  salts  of  suramin  with 
Ethidium,   Antrycide  and  other  trypano- 
cides  were  introduced  by  Williamson  and 
Desowitz  (1956)  for  prophylactic  use. 
They  obtained  more  than  7  months'  pro- 
tection against  T.  congolense  and  T.  vivax 
by  subcutaneous  injection  of  Ethidium  sur- 
aminate.     However,  Robson  and  Cawdery 
(1958)  considered  that  the  local  reactions 
which  it  produced  were  so  severe  as  to 
preclude  its  use  even  tho  at  5  mg/kg  it 
protected  naturally  exposed  zebus  for  113 
days  or  more.     Further  work  with  such 
complexes  may  be  rewai'ding. 

Pentamidine  has  been  used  extensively 
in  prophylaxis  of  human  trypanosomosis, 
but  is  not  used  in  domestic  animals. 

Whenever  a  drug  is  used  continuously 
for  prophylaxis,  there  is  danger  that  drug- 
fast  strains  of  parasites  may  appear  be- 
cause the  blood  level  becomes  so  low  that 
relatively  resistant  individuals  can  survive. 
This  has  happened  particularly  with  Antry- 


cide and  also  with  the  phenanthridinium 
derivatives.    Unfortunately,  too,  strains 
which  have  become  resistant  to  Antrycide 
are  also  resistant  to  phenanthridinium 
compounds.    No  drug  resistance  has  ap- 
peared so  far  to  Berenil. 

Control:     Same  as  for  T.   brucei. 


TRYPANOSOMA  DIMORPHON 
LAVERAN  AND  MESNIL,   1904 

This  species  was  once  thought  to  be  a 
synonym  of  T.   congolense,   but  Hoare 
(1959)  restudied  Laveran  and  Mesnil's 
original  slides,   measuring  1200  individuals 
and  analyzing  the  data  statistically,  and 
showed  that  it  differs  in  length.      T.  di- 
morphon  is  11  to  24  jj,  long  with  a  mean  of 
16.  2  (i;  the  means  of  different  populations 
ranged  from  15.  3  to  17.  6|n  .    Despite  its 
name,   Hoare  (1959)  found  that  it  is  actually 
monomorphic.    It  is  slender,  without  a 
free  flagellum,  and  its  undulating  membrane 
is  not  pronounced.     The  posterior  end  is 
rounded  (chiefly  in  the  shorter  forms)  or 
pointed  (chiefly  in  the  longer  forms).     The 
nucleus  is  in  the  middle  or  posterior  part 
of  the  body.     The  kinetoplast  is  fairly  large 
and  typically  subterminal  and  marginal. 

T.  dimorphon  occurs  in  Gambia,  French 
Guinea,  Ivory  Coast,   Belgian  Congo,  Sudan, 
Somalia,  Southern  Rhodesia,   Portuguese 
East  Africa,   Zululand  and  possibly  Nigeria, 
and  has  been  found  in  the  horse,  sheep, 
goat,  cattle,  pig  and  dog.    It  is  transmitted 
by  tsetse  flies  in  the  same  way  as  T.  con- 
golense. 


TRYPANOSOMA   SIMLAE 
BRUCE   ET  AL.  ,   1912 

Synonyms:      T.   ignotum,    T.   rodhaini, 
T.  porci. 

T.  simiae  was  first  found  in  a  monkey, 
but  its  natural  reservoir  host  is  the  wart- 
hog  {Phacophoerus  aethiopiciis).    It  is 
highly  pathogenic  for  the  pig  and  camel, 
causing  a  peracute  disease  with  death 
usually  in  a  few  days.    This  is  the  most 
important  trypanosome  of  domestic  swine. 


THE  HEMOFLAGELIATES 


57 


It  is  only  slightly  pathogenic  for  sheep 
and  goats,  and  apparently  non-pathogenic 
for  cattle,   horses  or  dogs,  altho  it  may 
infect  them.     The  rabbit  appears  to  be  the 
only  susceptible  laboratory  animal.    There 
is  a  great  deal  of  variation  in  pathogenicity 
between  strains,   and  indeed  marked 
changes  can  occur  in  the  pathogenicity  of 
a  single  strain. 

T.  slniiae  occurs  mostly  in  East 
Africa  and  the  Belgian  Congo,  but  it  has 
also  been  found  in  other  parts  of  Africa 
where  T.  co)igolense  occurs. 

T.  simiae  differs  morphologically 
from   T.  congolense  in  being  polymorphic 
instead  of  monomorphic.    It  varies  in 
length  from  12  to  2^\i.    About  90%  of  its 
forms  are  long  and  stout,  with  a  conspicu- 
ous undulating  membrane,  about  7%  are 
long  and  slender  with  an  inconspicuous  un- 
dulating membrane,   and  about  3%  are 
short,  with  an  inconspicuous  undulating 
membrane.     A  free  flagellum  is  usually 
absent,  but  has  been  reported  in  from  1  to 
4%  of  different  strains. 

This  species  is  transmitted  in  the 
warthog  reservoir  host  by  tsetse  flies,  in- 
cluding Glossliia  morsitans  and  G.   brevi- 
palpis,  in  which  it  develops  in  the  midgut 
and  proboscis.     Tsetse  flies  also  transmit 
it  to  swine,  but  once  it  has  been  introduced 
into  a  herd,  it  can  apparently  be  trans- 
mitted mechanically  by  horseflies  and 
other  blood-sucking  flies  (Unsworth,   1952). 

T.  simiae  is  more  resistant  to  drugs 
than  the  other  African  trypanosomes. 
Antrycide  methyl  sulfate  is  probably  the 
best  drug,  but  it  may  not  be  completely 
effective.    It  is  injected  subcutaneously 
at  the  rate  of  5  mg/kg;  more  than  one  in- 
jection is  probably  necessary. 

Control  measures  are  the  same  as 
for  T.  briicei.     In  addition,   horseflies  and 
other  biting  flies  should  be  controlled. 


Disease:     Souma.     T.   vivax  is  also 
sometimes  found  in  mixed  infections  of 
cattle  with  T.   congolense  and  T.   briicei. 

Hosts:     Cattle,   sheep,  goats,  camels, 
horse.     Antelopes  and  the  giraffe  are  res- 
ervoir hosts  in  Africa,  and  the  deer  (Odo- 
coileiis  g\'))inolis)  in  Venezuela  (Faisson, 
Mayer  and  Pifano,   1948).     The  pig,  dog 
and  monkey  are  refractory  to  infection. 
The  small  laboratory  rodents  are  difficult 
to  infect. 

Location:    Blood  stream,  lymph.     Cen- 
tral nervous  system  infections  have  been 
described  in  sheep. 

Geographic  Distribution:      T.  vivax 
is  found  thruout  the  tsetse  fly  belt  in  Africa. 
It  has,   however,   spread  beyond  this  region 
to  other  parts  of  Africa  and  to  Central 
America,  South  America,  the  West  Indies 
and  Mauritius. 

Morphology:      T.   vivax  is  20  to  27  ji 
long  and  monomorphic.    The  posterior  end 
is  typically  rounded,  a  free  flagellum  is 
always  present,  the  kinetoplast  is  large 
and  terminal,  and  the  undulating  membrane 
is  inconspicuous  (Fairbairn,   1953). 

Life  Cycle:     The  original  vectors  of 
T.   vivax  and  still  the  most  important  in 
Africa  are  tsetse  flies,  including  Glossina 
morsitans,   G.   tachinoides  and  other  spe- 
cies.   Development  takes  place  only  in  the 
proboscis.     The  trypanosomes  turn  into 
the  crithidial  form,   multiply  in  this  form 
and  then  turn  into  metacyclic,  infective 
trypanosomes  which  pass  to  the  hypopharynx 
and  infect  new  hosts  when  the  tsetse  flies 
bite.     The  flies  become  infectious  as  early 
as  6  days  after  they  themselves  were  in- 
fected. 

Horseflies  and  other  tabanids  may  act 
as  vectors;  they  are  the  only  ones  in  the 
New  World  and  in  Africa  outside  the  tsetse 
zone.    In  this  case  transmission  is  mechan- 
ical. 


TRYPANOSOMA   VIVAX 
ZIEMANN,   1905 

Synonyms:     T.  cazalboui,    T.   viennei, 
T.  bovis,   T.  angolense,   T.   caprae. 


Pathogenesis:      T.  vivax  is  most  im- 
portant in  cattle,  in  which  the  disease  is 
similar  to  that  caused  by  T.  congolense. 
According  to  Fairbairn  (1953),   T.  vivax 
infections  of  cattle  in  East  Africa  usually 


58 


THE  HEMOFLAGELLATES 


cause  a  mild  disease,  but  in  West  Africa 
they  are  usually  fatal  in  some  types  of 
cattle.     Virulent  strains  may  also  occur 
in  East  Africa.     Unsworth  (1953)  found 
that  T.  L'ivax  is  highly  pathogenic  for  zebu 
cattle  in  laboratory  infections,  and  that 
when  these  cattle  were  exposed  to  infec- 
tion under  natural  conditions  in  Nigeria, 
all  of  them  died. 

Camels  are  less  seriously  affected 
than  cattle.     T.   vivax  is  apparently  more 
pathogenic  for  sheep  than  other  trypano- 
somes,  and  may  be  found  in  the  central 
nervous  system.    It  is  apparently  less 
pathogenic  for  goats.    It  causes  a  chronic 
disease,  often  with  spontaneous  recovery, 
in  horses.     It  is  not  pathogenic  for  dogs, 
pigs  and  monkeys,   and  only  slightly  so  for 
the  common  laboratory  rodents. 

The  signs  of  disease  are  similar  to 
those  caused  by  T.   coiigolense.     There  is 
a  wide  variation  in  virulence  between  dif- 
ferent strains,  but  the  virulence  of  any 
particular  strain  tends  to  remain  constant. 

Diagnosis:     T.   vivax  is  detected  most 
readily  in  lymph  node  smears.     Large 
numbers  are  found  in  the  blood  only  in 
early  infections.    Inoculation  of  laboratory 
animals  is  not  particularly  satisfactory; 
inoculation  of  sheep  or  goats  is  better, 
the  trypanosomes  appearing  in  7  to  10  days. 


being  smaller.    It  is  12  to  20  ji  long,  with 
an  average  of  about  16/j..    It  occurs  in 
cattle,  sheep,  goats  and  antelopes,  causing 
a  disease  similar  to  that  caused  by  T.  vivax 
(Wilson,   1949).     Laboratory  rodents  are 
refractory  to  infection.    T.  uniforme 
occurs  only  in  Uganda  and  the  Belgian  Congo. 
It  is  transmitted  by  tsetse  flies  in  the  same 
way  as    T.   vivax. 


TRYPANOSOMA   CRUZI 
CHAGAS,    1909 

Synonyms:     Schizotrypanum  cruzi. 

Disease:     American  human  trypano- 
somosis,  Chagas'  disease. 

Hosts:     Many  species  of  wild  and  do- 
mestic animals  have  been  found  naturally 
infected  with  Trypanosoma  cruzi,  and 
probably  most  mammals  are  susceptible. 
Man  is  also  susceptible,   infants  and  young 
children  being  most  often  affected.     The 
most  important  wild  reservoir  hosts  are 
probably  armadillos  (Dasypus)  in  South 
America,  opossums  (Didelphis)  in  South 
and  Central  America  and  the  United  States, 
and  woodrats  {Neotoma)  and  possibly  rac- 
coons (Procyo)i)  in  the  United  States.     The 
dog,  cat  and  possibly  the  pig  are  consid- 
ered of  some  importance  as  reservoirs  of 
infection  for  man  in  South  America. 


Cultivation:     Same  as  for  other  try- 
panosomes. 

Treatment:     T.  vivax  can  be  success- 
fully treated  with  the  same  drugs  and  in 
the  same  dosages  as  T.  congolense.     It  is 
perhaps  slightly  more  resistant,  but  not 
significantly  so. 

Control:     Control  measures  are  the 
same  as  those  for  T.  coiigolense  infections. 
In  areas  where  tabanids  are  the  vectors, 
measures  directed  against  these  flies 
should  be  practiced. 


TR  YPANOSOMA   UNIFORME 
BRUCE  et  al.  ,    1911 

This  species  is  similar  to  T.   vivax, 
differing  from  it  morphologically  only  in 


Location:     The  trypanosomes  are 
found  in  the  blood  early  in  an  infection. 
Later,  they  invade  the  cells  of  the  reticulo- 
endothelial system,   heart  and  striated 
muscles  and  other  tissues.    In  central  nerv- 
ous system  infections,  they  are  found  in 
the  neuroglial  cells.    Trypanosome  forms 
occur  in  the  blood,   and  leishmanial  forms 
within  the  cells. 

Geographic  Distribution:      T.   cruzi 
occurs  in  South  America  from  Argentina 
north,   in  Central  America  and  in  southern 
United  States.    Dias  (1953)  published  maps 
of  the  distribution  of  Chagas'  disease  in 
South  and  Central  America  together  with 
climatologic  and  other  information. 

In  the  United  States,    T.  cruzi  had  been 
thought  until  recently  to  be  confined  to  the 
southwestern  states,  including  Texas, 


THE  HEMOFLAGELLATES 


59 


Arizona,   New  Mexico  and  southern  Califor- 
nia, but  Walton  et  al.    (1956)  discovered  it 
in  raccoons  in  Maryland,  and  it  appears 
that  it  may  be  rather  widely  distributed  in 
the  southeastern  states.     McKeever,  Gor- 
man and  Norman  (1958)  found  it  in  17%  of 
552  opossums,   2%  of  118  grey  foxes  {Uro- 
cyon  cinereoaygentens),   1.  5%  of  608  rac- 
coons and  1%  of  306  striped  skunks  {Me- 
phitis mephitis)  from  Georgia  and  Florida. 
Walton  et  al.   (1958)  found  it  in  5  of  400 
raccoons  from  Maryland.     Norman  et  al. 
(1959)  reported  that  their  strains  were 
typical  T.  criizi  of  relatively  low  virulence 
for  mice. 

Morphology:     The  forms  in  the  blood 
are  monomorphic,   16  to  20 /i  long,  with  a 
pointed  posterior  end  and  a  curved,   stumpy 
body.     The  kinetoplast  is  subterminal  and 
larger  than  that  of  any  other  trypanosome 
of  domestic  animals  or  man,  often  causing 
the  body  to  bulge  around  it.     The  undulating 
membrane  is  narrow,  with  only  2  or  3  un- 
dulations.    There  is  a  moderately  long 
free  flagellum.     The  leishmanial  forms  in 
the  muscle  and  other  tissue  cells  are  1.  5 
to  4.  0|i  in  diameter  and  occur  in  groups. 
Electron  microscope  studies  of  this  spe- 
cies have  been  made  by  Meyer  and  Porter 
(1954),   Meyer,  Musacchio  and  Mendonca 
(1958)  and  Meyer  and  Queiroga  (1960). 


Fig.   4.       Successive  stages  in  the  transfor- 
mation of  a  leishmanial  form  of 
Trypanosoma  criizi  into  a  meta- 
cyclic  trypanosome  form.     The 
metacyclic  trypanosome  (lower 
right)  is  from  a  Giemsa  stained 
smear;  the  other  stages  are  from 
living  preparations  of  culture  ma- 
terial viewed  with  the  phase  mi- 
croscope.    (From  Noble,   1955) 


Life  Cycle:     Altho  the  trypanosome 
form  of  T.  cruzi  is  common  in  the  blood 
in  the  early  stages  of  Chagas'  disease,  it 
does  not  multiply  in  this  form.     The  try- 
panosome forms  enter  the  cells  of  the 
reticulo-endothelial  system,   striated  mus- 
cles and  especially  of  the  heart  muscle, 
where  they  round  up  and  turn  into  leish- 
manial forms.     These  multiply  by  binary 
fission,  destroying  the  host  cells  and 
forming  cyst-like  nests  of  parasites. 
There  does  not  appear  to  be  conclusive 
proof  that  they  turn  into  the  crithidial 
form  in  mammals,  as  was  once  believed. 
The  leishmanial  forms  turn  into  trypano- 
some forms  which  re-enter  the  blood. 
Among  recent  studies  or  reviews  of  the 
life  cycle  of  T.   cruzi  in  the  vertebrate  host 
are  those  of  Elkeles  (1951),   Noble  (1955), 
Romana  (1956)  and  Wood  (1951,   1951a, 
1953). 


The  vectors  of  T.  cruzi  are  kissing 
bugs  or  conenose  bugs,  members  of  the 
hemipteran  family  Reduviidae.  Natural 
infections  have  been  found  in  at  least  36 
species  of  these  bugs.  They  get  their  first 
name  from  the  fact  that  in  sucking  blood 
they  prefer  to  attack  the  thinner  parts  of 
the  skin  such  as  the  lips  or  eyelids. 

The  most  important  vector  in  South 
America  is  probably  Panstrongylus  (syn. , 
Triatoma)  megistus.     Other  important 
vectors  in  South  and  Central  America  are 
P.  geniculatus,   Eutriatoma  sordida,    Tri- 
atoma infestans,  Rliodnius  prolixiis  and 
Eratyrus  cuspidatus. 

According  to  Faust  (1949),   15  naturally 
infected  species  of  reduviids  have  been 
found  in  the  United  States.    Dias  (1951, 


60 


THE  HEMOFLACELLATES 


1951a)  listed  Triatoma  pro Ir acta,   T.  san- 
giiisiiga  (=  T.  gerstaeckeri),   T.   lecliilar- 
ius,    T.  longipes,    T.  neolomae  and  T. 
rubida  as  having  been  found  infected  in  the 
U.  S.   Mehringer  and  Wood  (1958)  found 
T.  C7-uzi  in  24%  of  383  Triatuma  prolracta 
collected  in  the  Boy's  and  Girl's  Camp 
areas  in  Griffith  Park,   Los  Angeles, 
Calif.    Most  of  the  conenose  bugs  were 
taken  in  human  habitations. 

Both  the  nymphs  and  adults  of  these 

reduviids  can  be  infected  and  can  transmit 
the  disease.     In  addition,  it  is  possible  to 
infect  sheep  keds  (Rodhain  and  Brutsaert, 
1935),  ticks  {Orinthodorus){Bv\im'()i,   1939) 
and  bedbugs  (Wood,   1951a)  experimentally. 

After  they  have  been  ingested  by  the 
triatomids  along  with  a  blood  meal,  the 
trypanosomes  pass  to  the  midgut.     Here 
they  turn  into  leishmanial  forms  which 
multiply  by  binary  fission  and  turn  into 
either  metacyclic  trypanosomes  or  cri- 
thidial  forms.    The  crithidial  forms  multi- 
ply further  by  binary  fission,  and  extend 
into  the  rectum.     Here  they  turn  into  meta- 
cyclic trypanosomes,  which  are  unable  to 
divide  until  they  enter  a  vertebrate  host. 
The  life  cycle  in  the  invertebrate  host  takes 
6  to  15  days  or  longer,  depending  on  the  in- 
sect species  or  stage  and  on  the  temperature. 

The  infective  trypanosome  forms  pass 
out  in  the  feces.    They  can  penetrate  the 
mucous  membranes  or  skin  actively. 
Triatomids  commonly  defecate  after  feed- 
ing, and  most  human  infections  occur  when 
feces  are  rubbed  into  the  eyes  or  mucous 
membranes  following  a  bite.     Animals  can 
become  infected  by  licking  their  bites  or 
by  eating  infected  bugs  or  rodents. 

Epidemiology:      Human  infections 
with  T.  cnui  are  common  in  many  parts 
of  tropical  America,  including  Brazil, 
Bolivia,  northern  Chile,  northern  Argen- 
tina,  French  Guiana,   Paraguay,   Uruguay 
and  Venezuela.    In  some  localities  10  to 
20%  or  even  507o  of  the  inhabitants  are 
positive  to  the  complement  fixation 
(Machado)  test,  but  in  other  localities 
where  exposure  to  the  vectors  is  minimal, 
there  are  very  few  positive  reactions.     As 
mentioned  below,  acute  Chagas'  disease 


occurs  primarily  in  infants  and  children, 
and  the  number  of  acute  cases  is  far  lower 
than  the  numbers  of  chronic  and  unrecog- 
nized infections. 

Chagas'  disease  becomes  increasingly 
uncommon  to  the  north  of  the  endemic  area 
even  tho  infected  reservoir  hosts  and  vec- 
tors may  be  common.     Less  than  140  cases 
of  Chagas'  disease  had  been  reported  from 
Guatemala,  Salvador,  Nicaragua,   Costa 
Rica  and  Panama  according  to  Dias  (1952a) 
while  only  9  cases  were  known  from  Mexico 
(Mazzotti  and  Dias,   1950).    Only  a  single 
indigenous  case  has  been  reported  from 
the  United  States,  by  Woody  and  Woody 
(1955)  in  Texas. 

Chagas'  disease  is  a  zoonosis,   infec- 
tions occurring  widely  in  animals  and  man. 
The  armadillo  is  thought  by  Hoare  (1949) 
to  be  the  original  source  of  the  human  dis- 
ease in  South  America,  but  the  opossum 
and  many  other  wild  animals  are  also  in- 
fected.    The  most  important  wild  reser- 
voirs in  the  United  States  are  woodrats  of 
the  genus  Neotoitia.    Natural  infections 
have  been  found  in  the  southwestern  states 
and  southern  California  in  jV.  fuscipes, 
N.  albigida,  N.  micropus,  in  the  deer- 
mouse,   Peromyscus  boylii,  and  also  in 
the  opossum,  house  mouse  and  nine -banded 
armadillo  {Dasypus  novemcbictus).    The 
recent  discovery  of  T.   criizi  infections  in 
raccoons  {Procyon  lotor),  opossums,  gray 
foxes  and  skunks  in  Maryland,  Georgia  and 
Florida  (Walton  t^/ «/.  ,   1956,   1958;    Mc- 
Keever,  Gorman  and  Norman,   1958) 
raises  the  question  how  widespread  the  in- 
fection is  in  these  animals. 

Cats  and  dogs  are  often  naturally  in- 
fected in  South  America,   and,  because  of 
their  closer  association  with  man,  are 
probably  more  important  as  sources  of 
human  infection  than  wild  animals.     Natur- 
ally infected  pigs  have  been  found  in  South 
America,  and  sheep  and  goats  can  be  in- 
fected experimentally  with  these  South 
American  strains. 

In  a  study  of  the  possible  role  of  farm 
animals  as  reservoirs  of  North  American 
strains  of  T.  criizi.   Diamond  and  Rubin 
(1958)  established  low-grade  infections  in 


THE  HEMOFLAGELLATES 


61 


young  pigs,   lambs,  kids  and  calves  with 
a  strain  isolated  from  a  raccoon  in  Mary- 
land.    The  infections  persisted  at  least 
57  days  in  the  pigs,   53  to  85  days  in  the 
lambs,   38  days  in  a  kid  and  21  days  in  a 
calf. 

Infection  is  common  in  the  triatomid 
vectors  of  Chagas'  disease.    In  the  endemic 
regions  of  South  and  Central  America,  40 
to  60%  of  them  are  infected,  while  20  to 
25%  are  infected  in  Mexico  and  southwest- 
ern United  States.    The  triatomids  infest 
armadillo  burrows  and  woodrat  nests,  and 
thus  maintain  the  infection  in  these  animals. 
They  also  infest  houses,  where  they  live 
like  bedbugs;  it  is  these  triatomids  which 
are  responsible  for  the  vast  majority  of 
human  infections. 

Because  triatomids  are  rare  in  south- 
eastern U.  S.  where   T.  criizi  is  common 
in  the  opossums,  and  because  they  iso- 
lated the  organism  from  the  urine  of  in- 
fected opossums,   McKeever,  Gorman  and 
Norman  (1958)  believed  that  infections  may 
be  passed  from  mammal  to  mammal  by 
contact  with  infected  urine. 

For  further  information  on  the  epide- 
miology of  T.   cruzi  infections  see  Dias 
(1951,   1951a,   1951b,   1952,   1952a,   1952b), 
Dias  and  Chandler  (1951),  Dias  and  Laranja 
(1948),  Dias,   Laranja  and  Nobrega  (1946) 
and  other  papers  by  these  authors.     For 
information  on  the  epidemiology  of  T. 
cruzi  in  southwestern  United  States,   see 
Elkins  (1951)  and  particularly  Wood  (1950, 
1953a,   1958),   and  Mehringer  and  Wood 
(1958). 

Pathogenesis:     Chagas'  disease  may 
be  either  acute  or  chronic  in  man.     The 
great  majority  of  acute  cases  occur  in 
infants  and  young  children.     The  first  sign 
of  disease  is  often  swelling  of  the  eyes  and 
conjunctiva.     This  swelling  may  affect 
either  one  or  both  sides  of  the  face.    The 
tear  glands  become  inflamed,  and  the 
cervical  lymph  nodes  swell.     Later  on, 
swellings  may  appear  in  other  parts  of  the 
body.     Each  swelling,  known  as  a  chagoma, 
is  due  to  an  inflammatory  exudate  in  the 
region  where  the  parasites  are  invading 
the  tissue  cells.    In  addition  to  this  edema, 


there  may  be  anemia,  more  or  less  con- 
tinuous fever,   prostration  and  severe 
headache. 

If  the  patient  survives  the  acute  phase, 
the  disease  becomes  more  or  less  chronic. 
Some  authorities  believe  that  it  persists 
for  life.     The  lymph  nodes  are  edematous 
and  inflamed,   and  the  liver  and  spleen  are 
enlarged.    The  heart  is  affected  in  many 
cases.     Electrocardiographic  abnormal- 
ities are  common.    Inflammatory  infiltra- 
tion by  phagocytes,  fibrosis,   separation  of 
the  muscle  cells  and  partial  destruction  of 
the  fibers  by  the  multiplying  parasites  are 
present.     The  death  rate  due  to  cardiac 
conditions  is  increased  in  endemic  areas. 

T.   cruzi  may  cause  an  acute  or  chronic 
disease  in  laboratory  animals,  depending 
on  the  strain  of  the  parasite  and  the  age  of 
the  host.     Puppies  and  kittens  are  most 
susceptible,  followed  in  order  by  mice  and 
guinea  pigs.     The  reservoir  hosts  are  ap- 
parently not  seriously  affected,  nor  are 
farm  animals.    No  clinical  signs  were  ob- 
served in  the  infected  young  pigs,  lambs, 
kids  and  calves  studied  by  Diamond  and 
Rubin  (1958). 

Diagnosis:     In  the  acute  stage  of  the 
disease,   T.   cruzi  can  be  found  in  thick 
blood  smears.    In  chronic  or  light  infec- 
tions, other  methods  must  be  used.     One 
of  the  most  important  is  xeuodiagiios is, 
the  inoculation  of  susceptible  vector  hosts. 
Laboratory-reared,   parasite-free  triato- 
mids are  allowed  to  feed  on  suspected  in- 
dividuals, and  their  droppings  or  intestines 
are  examined  7  to  10  days  later  for  devel- 
oping trypanosomes.     Rhodnius  prolixus 
is  often  used  for  this  purpose  (Pifano,  1954a). 

Laboratory  animals  can  also  be  inoc- 
ulated.   In  descending  order  of  suscepti- 
bility, these  are  puppies,  kittens,  mice 
and  guinea  pigs.     The  trypanosomes  can 
be  cultivated  in  NNN  medium,  Weinman's 
(1946)  medium,  Diamond  and  Herman's 
(1954)  SNB-9  (serum -neopeptone-blood) 
medium,  or  in  a  number  of  other  media. 
The  trypanosomes  can  also  be  found  in 
biopsy  examinations  of  affected  lymph 
glands  or,  on  necropsy,  in  sections  of 
heart  muscle. 


62 


THE  HEMOFLAGELLATES 


A  complement  fixation  test,  the 
Machado  reaction,   has  been  used,  but  it  is 
also  positive  in  Leislunaitia  infections  and 
weakly  positive  in  a  number  of  other  con- 
ditions.   Other  serologic  tests  which  have 
been  used  are  the  precipitin  reaction,   an 
intradermal  skin  test  and  a  slide  agglu- 
tination test.     T.   cruzi  can  be  differenti- 
ated from  the  non-pathogenic  T.  rmigeli 
by  its  smaller  size  and  large  kinetoplast. 

Treatment:     No  satisfactory  drug  is 
known  for  the  treatment  of  T.   criizi  infec- 
tions, altho  Bayer  7602  Ac  is  used. 

Control:      Prevention  of  human    T. 
cruzi  infection  depends  upon  eliminating 
triatomids  from  houses.    This  will  also 
largely  prevent  infections  among  domestic 
dogs  and  cats.    Dusting  or  spraying  houses 
with  residual  lindane  or  dieldrin  has  given 
good  results. 


TR  YPANOSOMA  RANGELI 
TEJERA,   1920 

Synonyms:      Tr\'pa>ioso))ia  guaterna- 
lense,    T.  ariarii. 

T.   yaiigeli  was  first  found  in  the  tri- 
atomid,  Rhodnius  prolixus,   in  Venezuela. 
It  was  later  found  in  children  in  Guatemala 
and  still  later  in  Colombia,   Chile  and  El 
Salvador.    It  is  quite  common  in  dogs, 
cats  and  man  in  certain  areas  of  Venezuela, 
Colombia  and  Guatemala,   and  is  sometimes 
found  in  mixed  infections  with  T.   cruzi. 
Groot,   Renjifo  and  Uribe  (1951)  found  it  in 
67  of  183  persons  in  the  Ariari  Valley  and 
Groot  (1951)  found  it  in  1  of  30  persons,   2 
of  27  dogs  and  an  opossum  in  the  Mira- 
flores  region  of  Colombia.     It  has  also  been 
found  in  the  monkey,    Cebiis  fatiiellns. 
Young  mice,   rats  and  rhesus  monkeys  can 
be  infected  experimentally. 

The  trypanosomes  in  the  blood  are 
considerably  larger  than  T.  cruzi,  being 
26  to  36  )i  long.     The  nucleus  is  anterior 
to  the  middle  of  the  body,  the  undulating 
membrane  is  rippled  and  the  kinetoplast 
is  small  and  subterminal. 

The  most  common  vector  is  Rhodnius 
prolixus,  but  Triatoma  dimidiata  and  other 


triatomids  have  also  been  found  infected. 
A  piriform  stage  about  1  ji  long  has  been 
found  in  the  foregut,  and  crithidial  and 
metacyclic  trypanosome  forms  develop  in 
the  hindgut.     The  crithidial  stages  may  be 
extremely  long,   ranging  from  32  to  70  or 
even  over  100 /i  in  length.     The  metacyclic 
trypanosome  forms  have  a  well-developed 
undulating  membrane  and  a  long  free  fla- 
gellum.     They  may  pass  into  the  hemolyniph 
and  thence  to  the  salivary  glands.     They 
can  be  transmitted  either  by  bite  or  by 
fecal  contamination. 

T.  rangeli  does  not  appear  to  be  path- 
ogenic for  vertebrates,  but  Grewal  (1957) 
found  that  it  was  pathogenic  for  R.  prolixus 
and  also  for  experimentally  infected  bed- 
bugs. 

The  blood  forms  of  T.   ra)igeli  can  be 
readily  differentiated  from  those  of    T. 
cruzi  by  their  larger  size  and  their  much 
smaller  kinetoplast.     The  forms  in  the  in- 
sect hosts  can  be  distinguished  by  their 
small  kinetoplast  and  giant  crithidial  forms. 

T.   rangeli  can  be  easily  cultivated  in 
a  modified  NNN  medium  containing  glucose, 
peptone  and  macerated  meat  (Pifano,   1948). 
The  culture  forms  are  similar  to  those  in 
the  triatomid  intestine.     For  further  infor- 
mation regarding  this  species,   see  Groot, 
Renjifo  and  Uribe  (1951),  Groot  (1954), 
Pifano  (1948,  1954)  and  Zeledon  (1954). 


TR  YPANOSOMA 
LAVERAN,   1902 


THEILERI 


Synonyms:      Trypanosoma  franki, 
T.  ivrublewskii,    T.  himalayanum,    T. 
indiciim,    T.  muktesari,    T.  falsliaici,    T. 
scheini,   T.  americanum,    T.  rulherfordi. 

T.  theileri  occurs  in  the  blood  of  cat- 
tle.   It  is  worldwide  in  distribution.    It  is 
probably  quite  common,  but  is  rarely  found 
in  blood  smears.     Crawley  (1912)  found  it 
in  blood  cultures  from  74%  of  27  cattle 
around  Washington,  D.   C.  and  Glaser  (1922) 
found  it  in  blood  cultures  from  25%  of  28 
New  Jersey  cattle.     Neither  found  it  in 
direct  blood  smears.     Atchley  (1951)  found 
it  in  the  blood  of  1%  of  500  South  Carolina 
cattle. 


THE  HEMOFLACELLATES 


63 


T.   theileri  is  relatively  large,  being 
ordinarily  60  to  70  ;i  long,  but  forms  up 
to  120jLi  long  and  smaller  ones  25|i  long 
often  occur;  those  found  by  Levine  et  al. 
(1956)  in  an  Illinois  heifer  were  34  to  40 /i 
long  exclusive  of  the  flagellum.     The  pos- 
terior end  is  long  and  pointed.     There  is 
a  medium -sized  kinetoplast  some  distance 
anterior  to  it.     The  undulating  membrane 
is  prominent,   and  a  free  flagellum  is  pres- 
ent.    Both  trypanosome  and  crithidial  forms 
forms  may  occur  in  the  blood.     Multipli- 
cation occurs  by  binary  fission  in  the 
crithidial  form  in  the  lymph  nodes  and 
various  tissues. 

T.   theileri  is  transmitted  by  various 
tabanid  flies,  including  Tabamis  and 
Haeinatopota.     It  reproduces  in  the  fly 
intestine  by  binary  fission  in  the  crithidial 
stage. 

T.   theileri  is  ordinarily  non-patho- 
genic, but  under  conditions  of  stress  it 
may  cause  serious  signs  and  even  death. 
It  has  caused  losses  in  cattle  being  im- 
munized against  rinderpest  and  other 
diseases,  and  has  occasionally  been 
accused  of  causing  an  anthrax-like  dis- 
ease.    Carmichael  (1939)  found  masses  of 
T.   theileri  in  the  brain  of  a  cow  which  had 
died  with  signs  of  "turning  sickness"  in 
Uganda. 

T.  theileri  may  also  be  associated 
with  abortion,   altho  it  has  not  proved  that 
it  causes  this  condition.     Levine  et  al. 
(1956)  found  it  in  an  Illinois  heifer  which 
had  aborted,   and  Dikmans,   Manthei  and 
Frank  (1957)  found  it  in  the  stomach  of 
an  aborted  bovine  fetus  in  Virginia.    Lund- 
holm,  Storz  and^McKercher  (1959)  found 
it  as  a  contaminant  in  a  primary  culture 
of  kidney  cells  from  a  bovine  fetus  in 
California.     This  was  further  evidence 
that  intrauterine  transmission  may  occur. 

Ristic  and  Trager  (1958)  found  T. 
theileri  in  three  Florida  dairy  cattle  with 
depressed  milk  production;  it  was  not 
found  in  cows  in  the  same  herd  with  nor- 
mal milk  production.     The  affected  cows 
had  a  marked  eosinophilia. 

Since  T.   theileri  is  rarely  seen  in 
the  blood,  diagnosis  ordinarily  depends  on 


cultivation.    It  can  be  cultivated  in  NNN 
and  other  media  at  room  temperature. 
Ristic  and  Trager  (1958)  also  cultivated 
it  at  37""  C  in  a  blood-lysate  medium. 
Both  crithidial  and  trypanosome  forms 
were  present  in  their  cultures.     Lundholm, 
Storz  and  McKercher  (1959)  found  that  it 
grew  well  in  tissue  culture  medium  con- 
taining 10%  lamb  serum,  but  better  if 
bovine  kidney  cells  were  present. 

No  treatment  is  known  for  T.  theileri. 
Infections  can  be  prevented  by  elimination 
of  the  tabanid  vectors. 


TRYPANOSOMA  MELOPHAGIUM 
(FLU,   1908) 

This  parasite  is  very  common  in  sheep 
thruout  the  world.    It  is  non-pathogenic, 
and  infections  are  so  sparse  that  it  can  or- 
dinarily be  found  only  by  cultivation.     The 
trypanosomes  in  the  blood  resemble  T. 
theileri  and  are  50  to  60  |i  long. 

T.   nielophagimn  is  transmitted  by  the 
sheep  ked,  Melophagns  oviuiis,    and  can 
readily  be  found  in  its  intestine.    Its  life 
cycle  has  been  described  by  Hoare  (1923). 
Crithidial  forms  are  abundant  in  the  mid- 
gut,  and  leishmanial  forms  occur  here 
also.     Both  multiply  by  binary  fission. 
The  crithidial  forms  change  into  small, 
metacyclic  trypanosome  forms  in  the  hind- 
gut.     Nelson  (1956)  found  that  T.  melo- 
phagiiim  may  kill  the  ked  by  blocking  the 
midgut.     Sheep  are  infected  when  they 
bite  into  the  keds  and  the  trypanosomes 
pass  thru  the  intact  buccal  mucosa.     Be- 
cause infections  in  sheep  are  so  sparse, 
it  has  been  suggested  that  no  multiplication 
occurs  in  this  host. 


TRYPANOSOMA    THEODORI 
HOARE,   1931 

This  non- pat  ho  genie  species  was 
found  in  goats  in  Palestine.    It  resembles 
T.  melophagiHui  and  has  a  similar  life 
cycle,  except  that  its  intermediate  host 
is  another  hippoboscid  fly,   Lipoptena 
capriiia.     T.   tJieodori  may  be  a  synonym 
of    T.  nielophagiuni. 


64 


THE  HEMOFLACELLATES 


TRVPAXOSUMA  NABIASI 
RAILLIET,    1895 

This  species  occurs  in  the  wild 
European  rabbit,   Oryctolagns  cuniculiis. 
It  has  been  found  sporadically  in  England, 
France  and  other  European  countries.    It 
is  24  to  28  fi  long.     Its  intermediate  host 
is  the  flea,  Spilopsyllus  cuniculi,   in  which 
it  develops  in  the  gut.    The  metacyclic 
infective  forms  occur  in  the  rectum.    In- 
fection is  presumably  by  ingestion.    Grewal 
(1956)  described  its  life  cycle  briefly. 


TRYPANOSOMA   LEWISI 

CKENT,   1880) 

LAVERAN  AND  MESNIL, 


1901 


This  species  occurs  quite  commonly 
in  the  black  rat,   Norway  rat  and  other 
members  of  the  genus  Ralliis  thruout  the 
world.    It  is  not  normally  transmissible 
to  mice.    It  is  26  to  34  ^t  long.    Its  vector 
is  the  rat  flea,  Nosopsyllus  fasciatus,   in 
which  it  develops  in  the  gut,   and  in  which 
the  metacyclic,  infective  forms  occur  in 
the  rectum.     Rats  become  infected  by 
eating  infected  fleas  or  flea  feces.      T. 
lewlsi  is  non-pathogenic. 

A  great  deal  of  research  has  been 
done  on  this  species,   since  it  is  easy  to 
handle  and  its  host  is  a  convenient  one. 


TRYPANOSOMA  DUTTONI 
THIROUX,   1900 

This  species  occurs  in  the  house 
mouse  and  other  species  of  Alus  thruout 
the  world.    It  is  not  normally  transmis- 
sible to  rats.    It  is  28  to  34  ^  long.    Its 
vector  is  the  flea,   Nosopsyllus  fasciatus, 
and  its  life  cycle  is  the  same  as  that  of 
T.  lewisi.     It  is  non-pathogenic. 


TRYPANOSOMES  OF  BIRDS 

Trypanosomes  have  been  reported 
under  a  large  number  of  names  from 
many  species  of  birds.    They  all  look 
very  much  alike  and  probably  belong  to 
relatively  few  species.    However,  exten- 


sive cross  transmission  studies  are 
needed  to  establish  their  relationships, 
and,   until  these  are  carried  out,  it  is 
probably  best  to  refer  to  them  by  the  names 
under  which  they  were  first  described. 

Trypanosoma  avium  Danilew sky,  1885 
was  first  described  from  owls  (scientific 
name  not  given)  and  roller-birds  {Coracias 
garrulus)  in  Europe,  and  has  since  been 
reported  from  a  wide  variety  of  birds,  in- 
cluding crows  (Baker,   1956)  and  Canada 
geese  (Diamond  and  Herman,   1954).    Baker 
(1956  a,  b)  transmitted  it  from  the  rook 
[Corvus  frugilegns)  and  jackdaw  (C.   mone- 
dula)  to  canaries,  but  failed  to  transmit  it 
to  a  single  3-day-old  chick. 

T.  calmettei  Mathis  and  Leger,   1909 
was  described  from  the  chicken  in  south- 
east Asia;  it  is  about  36 |i  long.     T.  gal- 
linarum  Bruce  et  al.  ,   1911  was  described 
from  the  chicken  in  central  Africa;  it  is 
about  60 /i  long.     T.  Iiannai  was  described 
from  the  pigeon,   and  T.  numidae  from  the 
guinea  fowl. 

Avian  trypanosomes  are  very  poly- 
morphic,  sometimes  attaining  great  size. 
They  may  be  26  to  60j:x  long  or  even  longer. 
The  kinetoplast  is  generally  a  long  distance 
from  the  posterior  end.     There  is  a  free 
flagellum,   and  the  body  is  often  striated. 

Blood-sucking  arthropods  such  as 
mosquitoes  and  hippoboscids  are  believed 
to  be  the  vectors  of  avian  trypanosomes, 
but  the  only  complete  life  cycle  was  worked 
out  by  Baker  (1956, a,  b)  for  T.  avimn  from 
rooks  and  jackdaws.     He  found  that  in  Eng- 
land the  hippoboscid  fly,    Oniilhoiiiyia 
avicularia,   acts  as  the  vector.    Upon  in- 
gestion with  a  blood  meal,  the  trypanosomes 
change  into  the  crithidial  form  in  the  mid- 
gut, multiply  by  binary  fission  in  this  form, 
and  pass  to  the  hindgut.     They  multiply  fur- 
ther and  then  turn  into  a  piriform  stage 
which  develops  in  turn  into  a  small,  meta- 
cyclic trypanosome  form.     Birds  become 
infected  when  they  eat  infected  insects. 
The  metacyclic  trypanosomes  penetrate 
the  membranes  of  the  mouth,  esophagus 
and/or  crop  and  probably  invade  the  lymph- 
atic system,  developing  into  large  forms 


THE  HEMOFLAGELLATES 


65 


which  first  appear  in  the  blood  18  to  24 
hours  after  infection. 

According  to  Baker,  there  is  no  mul- 
tiplication in  the  avian  host,  the  trypano- 
somes  simply  becoming  larger.     This 
would  account  for  their  sparse  numbers  in 
the  blood.    They  persist  in  the  rook  and 
jackdaw  over-winter,  being  more  or  less 
restricted  to  the  bone  marrow,   and  re- 
appear in  the  peripheral  blood  in  the  spring 
Diamond  and  Herman  (1954),  too,  found 
that  T.  avium  could  be  isolated  from  the 
bone  marrow  of  Canada  geese  much  more 
readily  than  from  the  blood. 

Nothing  is  known  of  the  pathogenicity 
of  the  avian  trypanosomes.     They  are  pre- 
sumably non-pathogenic. 

Avian  trypanosomes  can  be  readily 
cultivated  on  several  media,   including 
NNN  medium  and  the  SNB-9  (saline-neo- 
peptone-blood)  medium  described  by 
Diamond  and  Herman  (1954). 


Genus   LEISHMANIA   Ross,   1903 

Members  of  this  genus  occur  primar- 
ily in  mammals.    They  cause  disease  in 
man,  dogs  and  various  rodents  including 
gerbils  and  guinea  pigs.    Leishiiiaiiia  is 
heteroxenous,  being  transmitted  by  sand- 
flies of  the  genus  Phlebotoiuiis.     It  is 
found  in  the  leishmanial  stage  in  the  cells 
of  its  vertebrate  hosts  and  in  the  lepto- 
monad  stage  in  the  intestine  of  the  sandfly 
and  in  culture. 

Morphology:     All  species  of  Leish- 
mania  look  alike,  altho  there  are  size  dif- 
ferences between  different  strains.     The 
leishmanial  stage  is  ovoid  or  round, 
usually  2.  5  to  5.  0  by  1 .  5  to  2.  0  p. ,   altho 
smaller  forms  occur.     Only  the  nucleus 
and  kinetoplast  are  ordinarily  visible  in 
stained  preparations,  but  a  trace  of  an  in- 
ternal fibril  representing  the  flagellum 
can  sometimes  be  seen.     This  flagellum 
and  the  basal  granule  from  which  it  arises 
can  also  be  seen  in  electron  micrographs 
(Chang,   1956;  Pyne  and  Chakraborty, 
1958).     The  leptomonad  forms  in  culture 
and  in  the  invertebrate  host  are  spindle- 


shaped,   14  to  20  |i  long  and  1.  5  to  3.  5(i 
wide. 

Life  Cycle:     In  the  vertebrate  host, 
Leishmauia  is  found  in  the  macrophages 
and  other  cells  of  the  reticulo-endothelial 
system  in  the  skin,   spleen,   liver,  bone 
marrow,  lymph  nodes,  mucosa,  etc.    It 
may  also  be  found  in  the  leucocytes,  es- 
pecially the  large  mononuclears,  in  the 
blood  stream.    It  multiplies  by  binary 
fission  in  the  leishmanial  form. 

The  invertebrate  hosts  of  Leishmauia 
are  sandflies  of  the  genus  Phlebotomus . 
When  the  sandflies  suck  blood  they  ingest 
the  leishmanial  forms.     These  pass  to  the 
midgut,  where  they  assume  the  leptomonad 
form  and  multiply  by  binary  fission.     They 
may  be  either  free  in  the  lumen  or  attached 
to  the  walls. 

Their  further  development  varies  with 
the  particular  species  of  Pldebotomiis  and 
strain  of  Leislniiaitia.    In  good  vectors  like 
P.  argentipes,  P.  papatasii  and  P.   sergenti, 
they  begin  to  extend  their  range  forward  to 
the  esophagus  and  pharynx  by  the  fourth  or 
fifth  day.     They  continue  to  multiply  to 
such  an  extent  that  they  plug  up  the  esopha- 
gus and  interfere  with  blood- sucking.    When 
an  infected  sandfly  bites,  it  clears  the  pas- 
sage by  injecting  some  of  the  leishmanial 
forms  into  its  victim  and  thus  transmits  the 
parasite.   Leishmauia  may  also  be  transmit- 
ted when  sandflies  are  crushed  on  the  skin. 

In  other  cases,  the  parasites  remain 
in  the  sandfly  midgut  and  do  not  pass  for- 
ward into  the  pharynx.     These  can  then  be 
transmitted  only  by  crushing  the  sandflies. 
A  third  type  of  development  was  described 
by  Shoshina  (1953),  who  found  leptomonads 
in  the  hindgut  of  P.  )nini(tiis  var.   arpark- 
leiisis  in  Russia  and  suggested  that  feces 
containing  them  might  be  rubbed  into  the 
bite  while  scratching  it. 

In  addition  to  transmission  by  sand- 
flies, it  has  been  suggested  that  direct 
infection  by  means  of  excretions  of  infected 
individuals  might  occur  in  kala  azar. 

Species  of  Leishmania:     The  specia- 
tion  of  Leislimaiiia  has  been  discussed  by 


66 


THE  HEMOFLACELLATES 


Hoare  (1949),  Kirk  (1949,   1950)  and  Biaga 
(1953)  among  others.    While  some  22  dif- 
ferent specific  or  subspecific  names  have 
been  given  to  mammalian  leishmanias,  and 
while  different  strains  are  associated  with 
different  types  of  disease,  neither  morpho- 
logic, cultural  nor  immunologic  characters 
can  be  used  to  differentiate  the  species  of 
Leishiiia)iia.     In  practice,  the  species  are 
separated  on  the  basis  of  pathologic  and 
epidemiologic  differences  and,   since  most 
studies  have  been  made  by  parasitologists 
oriented  toward  human  disease,  the  patho- 
logic characters  used  for  each  strain  have 
been  those  seen  in  man.    In  the  earlier 
days  of  our  knowledge,  when  relatively  few 
types  were  known,  it  was  quite  easy  to  de- 
lineate their  characteristics  and  set  up 
separate  species,  but  as  more  studies 
were  made,  intermediate  types  were  found 
and  the  boundaries  between  species  tended 
to  disappear. 

Some  parasitologists  consider  that  all 
the  leishmanias  of  man  and  dogs  should  be 
assigned  to  a  single  species.     Others  pre- 
fer to  assign  them  to  two  species,  and 
still  others  to  three.    One  can  justify  each 
of  these  schemes,  but  in  all  of  them  each 
species  is  still  composed  of  a  number  of 
strains  or  demes. 

In  this  book,  two  species  of  Leish- 
mania  are  recognized:      L.  doiiovani, 
causing  various  visceral  forms  of  disease, 
and  L.  tropica,   causing  various  cutaneous 
and  mucocutaneous  forms.     The  third  spe- 
cies recognized  by  some  authorities  is 
L.   hrasiliensis,  which  causes  a  mucocu- 
taneous form  of  the  disease. 

Maps  of  the  world  distribution  of 
leishmanioses  together  with  climatologic 
and  other  information  have  been  published 
by  Piekarski  (1952),   Piekarski  and  Sibbing 
(1954),   Piekarski,   Hennig  and  Sibbing 
(1956,  1958a),  the  American  Geographical 
Society  (1954)  and  May  (1954). 


LEISHMANIA  DONOVANI 
(LAVERAN  AND   MESNIL,    1903) 
ROSS,   1903 

Synonyms:     Piroplasma  donovani, 
Leishmania  infantum,   L.  canis,  L.  chagasi. 


Disease:     Kala-azar;  dum-dum  fever; 
visceral  leishmaniosis. 

Hosts:     Man  and  the  dog  are  the  prin- 
cipal hosts  of  L.  donovani.     Infections  have 
also  been  reported  in  the  cat  by  Sergent 
el  at.   (1912)  and  Bosselut  (1948),   in  the 
sheep  by  De  Paolis  (1935)  and  in  the  horse 
by  Richardson  (1926). 

Location:     L.  donovani  occurs  in  the 
cells  of  the  reticulo -endothelial  system, 
including  both  the  endothelial  cells  and  the 
circulating  monocytes  and  polymorphonu- 
clear leucocytes.    The  parasites  are  found 
thruout  the  body,  but  particularly  in  the 
endothelial  cells  of  the  blood  and  lymph 
vessels  of  the  spleen,  liver,  bone  marrow, 
lungs,  kidneys,   mesenteric  lymph  nodes 
and  skin. 

Types  of  Disease,  Geographic  Distri- 
bution and  Epidemiology: 

Five  types  of  visceral  leishmaniosis  can 
be  recognized: 

1.  Indian  kala-azar  or  dum-dum  fever  is 
the  classical  type  of  the  disease.    It  is 
found  in  India  and  affects  young  adults 
(60%)  and  children  5  to  15  years  old. 

It  does  not  occur  naturally  in  dogs  altho 
they  can  be  infected  experimentally.    It 
is  transmitted  by  Phlebotoums  argen- 
tipes. 

2.  Sudanese  kala-azar  is  found  in  the 
Sudan  and  Abyssinia.    It  affects  people 
of  the  same  ages  as  Indian  kala-azar 
and  does  not  occur  naturally  in  dogs. 
It  was  found  once  in  a  horse  (Kirk, 
1956).     Oral  lesions  are  frequently 
present,  and  this  type  of  the  disease  is 
relatively  refractory  to  treatment  with 
antimony  compounds.    It  is  transmitted 
by  P.  orientalis.    A  similar  form  oc- 
curs in  small,  isolated  pockets  scat- 
tered thru  Africa  south  of  the  Sahara. 
It  may  cause  skin  lesions  in  addition 

to  the  visceral  ones.     It  is  a  zoonosis, 
and  has  been  found  in  a  gerbil  (  Tatera 
vicina)  and  a  ground  squirrel  {Xenis 
)7<////fs)(Manson-Bahr,   1959). 

3.  Chinese  kala-azar  is  found  in  northern 
China.    It  is  more  common  in  children 


THE  HEMOFLAGELLATES 


67 


than  in  adults,  and  also  occurs  com- 
monly in  dogs.    It  is  transmitted  by 
P.   cliiiieiisis  and  P. 


sergeiiti. 


4.  Mediterranean  or  infantile  kala-azar 
is  found  in  countries  of  the  Mediter- 
ranean basin  including  southern 
Europe  and  in  parts  of  tropical  Africa. 
Dogs  are  much  more  commonly  in- 
fected than  man,  and  90%  of  the  af- 
fected people  are  children  less  than  5 
years  old.     The  incidence  in  dogs  may 
reach  20%  in  some  countries,   and  in- 
fection rates  as  high  as  40%  have  been 
reported  in  Greece  and  Samarkand. 
Even  in  such  countries,  the  infection 
rate  in  children  is  only  1  to  2%. 
Mediterranean  kala-azar  is  transmitted 
principally  by  P.  perniciosus  and  P. 
major. 

5.  South  American  kala-azar  is  found 
from  Mexico  to  northern  Argentina. 

It  attacks  human  beings  of  all  ages  and 
also  occurs  in  dogs  and  cats.     In  a 
monographic  review  of  visceral  leish- 
maniosis  in  Brazil,  Da  Silva  (1957) 
stated  that  it  is  endemic  and  at  times 
epidemic  in  certain  areas,  that  it  is 
transmitted  by  Plilebotonius  longipal- 
pis  from  a  natural  reservoir  host  such 
as  the  dog,  and  that  it  occurs  mostly 
among  persons  with  a  low  economic 
status  and  particularly  among  the 
children  of  that  group.     According  to 
Deane  (1956,   1958),  the  dog  is  the 
principal  urban  reservoir  and  the  most 
important  source  of  human  infection, 
while  the  "bush-dog"  {Lycalopex  vet- 
uliis)  is  probably  the  principal  rural 
one.    The  disease  is  also  transmitted 
by  P.   iiitermedius. 

Two  cases  of  visceral  leishmaniosis 
have  been  reported  in  dogs  in  the  United 
States,  one  in  Alabama  by  Thorson  et  al. 
(1955)  and  the  other  in  Washington,  D.  C. 
by  Gleiser,   Thiel  and  Cashell  (1957). 
Both  dogs  had  been  imported  into  this 
country  from  Greece. 

Of  the  five  types  of  visceral  leish- 
maniosis, the  Mediterranean,   Chinese 
and  South  American  are  zoonoses  while 
the  Indian  and  Sudanese  are  not.    The 


reasons  for  this  are  not  clear,   since  dogs 
can  be  infected  experimentally  with  the 
Indian  and  Sudanese  denies  of  L.  cloiiovani. 
Adler  and  Theodor  suggested  that  it  may 
be  because  the  Mediterranean  type  is  trans- 
mitted by  sandfly  bites  whereas  the  Indian 
type  is  transmitted  when  the  sandfly  is 
crushed  on  the  skin.    Since  dogs  and  infants 
are  not  good  flyslappers,  they  are  not  so 
likely  to  get  Indian  kala-azar. 

Pathogenesis:     Kala-azar  is  an  im- 
portant and  highly  fatal  disease  of  man, 
particularly  in  India.     After  an  incubation 
period  of  several  months,   it  starts  with  an 
irregular  fever  lasting  weeks  to  months. 
The  spleen  and  liver  hypertrophy.     In  ad- 
vanced cases,  there  is  ulceration  of  the 
digestive  tract  (mouth,  nose,   large  intes- 
tine) resulting  in  diarrhea,  and  ulceration 
of  the  skin.     There  is  great  emaciation, 
but  the  abdomen  is  swollen.    In  untreated 
cases,  the  mortality  is  75  to  95%,  being  a 
little  higher  in  adults  than  in  infants. 
Death  occurs  in  a  few  weeks  to  several 
years,  often  resulting  from  intercurrent 
disease.    In  treated  cases,  85  to  95%  re- 
cover.    Following  recovery,  whitish  spots 
which  develop  into  lentil-sized  nodules  may 
appear  in  the  skin,   particularly  of  the  face 
and  neck.     This  condition  is  known  as  post- 
kala-azar  dermal  leishmanoid. 

Mediterranean  kala-azar  in  children 
is  similar  to  the  above,  but  the  disease 
usually  runs  a  shorter  course. 

Kala-azar  is  essentially  a  reticulo- 
endotheliosis.     The  reticulo-endothelial 
cells  are  increased  in  number  and  invaded 
by  the  parasites.     The  cut  surface  of  the 
enormously  enlarged  spleen  is  congested, 
purple  or  brown,  with  prominent  Malpig- 
hian  corpuscles.     The  liver  is  enlarged 
and  there  is  fatty  infiltration  of  the  Kupf- 
fer  cells.    The  macrophages,  myelocytes 
and  neutrophiles  of  the  bone  marrow  are 
filled  with  parasites.     The  lymph  nodes 
are  usually  enlarged  and  the  intestinal 
submucosa  is  infiltrated  with  macrophages 
filled  with  parasites;  these  are  especially 
numerous  around  the  Peyer's  patches.    In- 
testinal ulceration,   if  present,   is  usually 
a  secondary  condition.     There  is  progres- 
sive leucopenia  accompanied  by  monocytosis. 


68 


THE  HEMOFLAGELLATES 


There  may  be  anemia  due  to  blockage  of 
the  reticulo-endothelial  system. 

In  dogs  and  also  in  the  Brazilian  bush- 
dog,   L.  duiiova)ii  may  cause  either  vis- 
ceral or  cutaneous  lesions,  but  the  latter 
are  much  more  common.    The  disease  is 
usually  chronic  with  low  mortality,  altho 
an  acute,   highly  fatal  type  is  known. 
There  may  be  emaciation  and  anemia. 
There  is  an  abundant  scurfy  desquamation 
of  the  skin,  and  in  some  dogs  more  or 
less  numerous  cutaneous  ulcers.     In 
Chinese  kala-azar,  cutaneous  lesions  occur 
especially  around  the  nose  and  ears.    The 
hair  is  shed  on  parts  of  the  body,   particu- 
larly the  head.     The  parasites  occur  in  the 
macrophages  in  the  subcutaneous  tissues 
or  in  nodular  lesions  in  the  skin.     They 
have  also  been  recovered  from  healthy 
appearing  skin.    The  visceral  type  of  the 
disease  is  similar  to  that  in  man. 

Diagnosis:     The  only  sure  diagnostic 
method  is  the  demonstration  of  the  para- 
sites themselves,  altho  serologic  and 
other  tests  have  also  been  used  and  are  of 
suggestive  value.     Smears  made  from 
biopsy  samples  of  spleen  pulp,   liver  pulp, 
superficial  lymph  nodes,  bone  marrow  or 
thick  blood  smears  can  be  stained  with 
Giemsa's  stain  and  examined  microscopi- 
cally.   In  visceral  leishmaniosis,  the 
spleen  is  most  often  positive,  but  a  certain 
amount  of  danger  is  associated  with  punc- 
turing a  soft,   engorged,  enlarged  spleen. 
Thick  blood  smears  are  more  often  posi- 
tive in  man  than  in  dogs. 

Examination  of  bone  marrow  obtained 
by  sternal  puncture  is  becoming  increas- 
ingly popular.    In  the  cutaneous  form  of 
the  disease,   scrapings  should  be  made 
for  staining  from  the  lesions  or  from  the 
dermis  with  as  little  bleeding  as  possible. 
This  is  probably  the  method  of  choice  for 
dogs,  since  the  cutaneous  disease  is  more 
common  than  the  visceral  form  in  them. 
L.  donovaiii  can  often  be  found  in  appar- 
ently normal  skin  in  dogs  and  also,   in  the 
Sudanese  and  Middle  Asiatic  forms  of  the 
disease,  in  man  (Manson-Bahr,   1959). 
Examination  of  the  superficial  lymph 
nodes  is  also  valuable. 


Leishmania  can  be  cultivated  readily 
in  NNN  medium  or  a  similar  medium.    The 
medium  is  inoculated  with  spleen,   lymph 
node  or  liver  juice,  bone  marrow,  blood, 
or  excised  dermis  and  incubated  for  a  week 
to  a  month  at  22  to  24"^  C.     Leptomonad 
forms  are  present  in  culture.     Leishmania 
can  also  be  grown  in  chicken  embryos 
(Trincao,   1948)  and  in  tissue  culture 
(Hawking,   1948);  see  Pipkin  (1960)  for  a 
review  of  this  subject. 

Animal  inoculation  can  also  be  prac- 
ticed, but  is  not  usually  done  because  it 
takes  several  months.     The  golden  hamster 
is  the  most  susceptible  laboratory  animal. 

The  complement  fixation  test  has  been 
used  with  some  success,   particularly  in 
man.    It  is  often  positive  before  the  para- 
sites themselves  can  be  found. 

The  formol  gel  test  (Napier's  aldehyde 
test)  is  positive  in  more  advanced  cases. 
It  is  carried  out  by  adding  a  drop  of  com- 
mercial formalin  to  1  ml  of  serum.    In  a 
positive  reaction  the  serum  turns  into  a 
milky  white  gel;  a  clear  gel  is  not  positive. 
Organic  antimony  compounds,   resorcinol, 
and  many  other  compounds  will  also  pro- 
duce this  reaction.    It  is  due  to  an  increase 
in  euglobulin  and  decrease  in  albumin  in 
the  serum.    It  also  occurs  in  diseases 
other  than  kala-azar. 

Treatment:     Leishmanial  infections 
can  be  treated  successfully  with  various 
organic  antimony  compounds.     The  cheap- 
est is  tartar  emetic,  which  is  administered 
intravenously.    In  man,  at  least  25  or  30 
doses  totaling  at  least  2.  5  g  must  be  ad- 
ministered daily  or  on  alternate  days. 
Pentavalent  antimony  compounds  are  more 
expensive,  but  they  are  less  toxic,  act 
more  quickly,  and  most  of  them  can  be  in- 
jected intramuscularly  as  well  as  intra- 
venously.    Even  so,   10  or  12  doses  total- 
ing 2.  7  to  4.  0  g  are  needed.     Among  these 
compounds  are  neostibosan,  neostam, 
solustibosan  and  urea  stibamine.     The 
aromatic  diamidines,   pentamidine  and  stil- 
bamidine,  have  been  used  in  treating  hu- 
man leishmaniosis,  but  they  are  appar- 
ently not  very  effective  in  dogs.    Goodwin 


THE  HEMOFLAGELLATES 


69 


and  Rollo  (1955)  reviewed  the  chemother- 
apy of  leishmaniosis  briefly. 

Control:      Prevention  of  leishmanial 
infections  depends  on  breaking  the  life 
cycle  by  elimination  of  sandflies.     This 
can  be  done  by  residual  spraying  of  houses, 
barns  and  outside  resting  places  with  DDT 
or  other  chlorinated  hydrocarbon  insecti- 
cides (Hertig,   1949;  Corradetti,   1954; 
Deane,   1958).     In  addition,  insect  repel- 
lents such  as  dimethylphthalate  can  be 
rubbed  on  the  skin,   houses  can  be  screened 
with  very  fine  mesh  wire,   and  decaying 
vegetation  and  other  breeding  places  can 
be  cleaned  up. 

In  regions  where  kala-azar  is  a 
zoonosis,  treatment  of  infected  dogs  and 
destruction  of  strays  will  eliminate  the 
reservoir  of  infection  for  man. 


LEISHMANIA   TROPICA 
(WRIGHT,   1903) 
LUHE,   1906 

Synonyms:      Helcosoma  tropicnm, 
Sporozoa  furuncidosa,   Ovoplas»ia  orien- 
tale,  Plasmosoma  jericiiaense,   Leish- 
mania  wrighti,   L.   Cunningham i,   L.  nilo- 
tica,  L.  recidiva,  L.  brasilieiisis,  L. 
peruviana. 

Disease:     Cutaneous  leishmaniosis, 
mucocutaneous  leishmaniosis,  Oriental 
sore,  Aleppo  button,  Jericho  boil,  Delhi 
boil,  espundia,  uta,   chiclero  ulcer,  buba, 
plan  bois,  American  forest  leishmaniosis. 

Hosts:     The  usual  hosts  are  man,  the 
dog  and,  in  parts  of  the  Old  World,  gerbils 
{Rhombomys  opimus)  and  other  wild  ro- 
dents. 

Location:      L.   tropica  occurs  in  the 
monocytes  and  other  cells  of  the  reticulo- 
endothelial system,  in  cutaneous  lesions 
and  in  the  skin.    It  may  also  occur  in  the 
lymph  nodes  and  in  the  mucous  membranes. 

Types  of  Disease,  Geographic  Distri- 
bution and  Epidemiology: 

Two  forms  of  cutaneous  leishmaniosis 
have  been  described  in  man  in  the  Old 


World  and  4  in  the  New.  Separate  sub- 
specific  names  have  been  given  to  some 
of  them: 

1.     Classical  Oriental  sore  is  found  in 
regions  with  a  hot,  dry  climate  from 
the  Mediterranean  basin  to  central  and 
northern  India.    It  is  caused  by    L. 
tropica  minor.     The  incubation  period 
is  several  months.     The  lesions  are 
circumscribed,   "dry"  sores  in  the 
skin.     They  heal  spontaneously  and  do 
not  extend  to  the  mucous  membranes. 
The  lymph  nodes  are  involved  in  about 
10%  of  the  cases.    Dogs  are  commonly 
infected,   and  the  disease  is  urban  in 
distribution.    In  Teheran,  Iran,  for 
example,   40  to  50%  of  the  dogs  have 
skin  ulcers.     The  disease  is  transmit- 
ted by  Phleboto)}ins  papatasii,  P.  ser- 
genti,  P.  perfiliewi  and  P.  tongicuspis. 

2.  "Moist"  or  "wet"  Oriental  sore  is  found 
in  Central  Asia  and  southern  USSR.    It 
is  caused  by  L.  tropica  major;  there  is 
no  cross-immunity  between  this  sub- 
species and  L.  t.  minor.      The  incuba- 
tion period  is  1  to  6  weeks.     The  lesions 
are  wet  and  ulcerative,  but  do  not  ex- 
tend to  the  mucous  membranes.     They 
heal  spontaneously.    The  lymph  nodes 
are  often  involved.     The  disease  is  rural 
in  distribution.     The  reservoir  hosts 
are  various  desert  rodents,  the  gerbil 
{Rhombomys  opimus)  being  the  most 
important.    The  vector  is  P.  caucasicus, 
which  lives  in  the  gerbil  burrows. 

3.  Mucocutaneous  leishmaniosis  or  espun- 
dia is  found  in  the  Brazilian  rain  for- 
ests.   It  is  caused  by  L.  tropica  bra- 
siliensis,   which  many  authors  consider 
a  separate  species,   L.  brasiliensis. 
The  skin  lesions  are  chronic  and  spread- 
ing, often  invading  the  mucous  mem- 
branes either  by  metastasis  or  extension, 
and  sometimes  causing  great  disfigure- 
ment.    Spontaneous  recovery  is  rare. 
The  lymph  nodes  are  seldom  involved. 
Dogs  and  occasionally  cats  have  been 
found  naturally  infected,  but  the  true  res- 
ervoir hosts  have  not  been  discovered; 
they  are  probably  wild  jungle  mammals. 
The  retus  monkey  and  various  squirrels 
can  be  readily  infected,  but  the  golden 
hamster  is  refractory.    The  vectors  are 


70 


THE  HEMOFLAGEUATES 


Phlebotomus  intermedins  (syn.  ,  Pllittzi), 
and  also  probably  P.  iiiigonei,  P.  whit- 
niani  and  P.  pessoai. 

4.  Uta  occurs  in  the  mountains  of  Peru. 
It  is  a  benign  form  of  the  disease, 
with  numerous  small  skin  lesions.    Its 
reservoir  hosts  and  vectors  are  ap- 
parently unknown. 

5.  American  forest  leishmaniosis,   pian 
bois  or  buba  is  found  in  Panama,  Costa 
Rica,  the  Guianas  and  other  parts  of 
northern  South  America.    It  is  caused 
by  L.   Iropica  gidaneiisis.    The  skin 
lesions  are  moderately  ulcerated,  and 
ordinarily  heal  spontaneously  unless 
they  involve  the  nose.     About  5%  of  the 
patients  have  lesions  of  the  mucous 
membranes  which  have  arisen  by  ex- 
tension rather  than  by  metastasis. 
The  lymph  nodes  are  involved  in  about 
10%.    Dogs  may  be  naturally  infected, 
but  the  wild  reservoirs  are  unknown. 
The  vectors  in  Venezuela  are  believed 
to  be  PlilebutoDius  evansi,   P.  niigoiiei, 
P.  parasinensis  and  P.  siiis. 

6.  Chiclero  ulcer  or  bay  sore  is  found  in 
Guatemala,   southeastern  Mexico  and 
British  Honduras.     It  gets  its  name 
because  it  is  common  among  chicle 
and  rubber  hunters  in  rain  forests.    It 
is  caused  by  L.   tropica  mexicaiia.    The 
skin  lesions  are  small.     They  heal 
spontaneously  in  a  few  weeks  to  a  few 
months  unless  they  involve  the  ear.    In 
this  location  they  cause  chronic,  dis- 
figuring nodular  ulcers  which  may  per- 
sist many  years.    There  is  no  metas- 
tasis to  the  mucous  membranes,   and 
cutaneous  metastases  are  rare.     The 
lymph  nodes  are  involved  in  about  2%. 
Nothing  is  known  of  the  wild  reser- 
voirs or  of  the  vectors,   altho  the  dis- 
ease is  clearly  a  zoonosis  (Garnham 
and  Lewis,   1959). 

Both  the  Old  World  types  of  cutaneous 
leishmaniosis  are  zoonoses,  but  their 
epidemiology  is  quite  different.     The  dry 
type  is  an  urban  disease  common  to  dogs 
and  man,  while  the  moist  type  is  a  rural 
disease  of  gerbils  and  other  rodents  which 
affects  man  more  or  less  incidentally. 


The  American  forms,  too,  occur  primarily 
in  wild  animals,  mostly  unknown,  of  the 
tropical  rain  forests;  both  man  and  dogs 
are  secondary  hosts. 

Pathogenesis:     The  ulcers  or  sores 
of  classical,  dry  Oriental  sore  are  found 
on  exposed  parts  of  the  body  in  man.     At 
first  they  resemble  mosquito  bites,  but 
they  do  not  go  away.    The  lesion  grows 
slowly,  becoming  covered  with  thick  brown 
scales.    It  itches  a  great  deal,   and  scratch- 
ing produces  a  small  ulcer  which  is  covered 
with  a  crust.     This  enlarges  slowly,   and 
may  finally  be  several  centimeters  in  diam- 
eter.    After  some  months  or  a  year,   con- 
nective tissue  is  formed,  but  a  permanent 
scar  is  left.     The  disease  is  very  seldom 
fatal. 

In  the  central  Asian  form  of  the  dis- 
ease, the  lesions  are  moist.     They  develop 
more  rapidly,  becoming  ulcerative  in  one 
or  two  weeks,   and  then  heal  spontaneously. 
Relatively  few  parasites  can  be  found  in 
them. 

In  espundia,  the  ulcers  are  often  worse 
than  those  of  Oriental  sore  and  may  last 
much  longer.     They  usually  heal  in  7  to  8 
months,  but  sometimes  last  more  than  20 
years.    In  addition,   in  some  cases  they  may 
extend  to  the  mucosa  of  the  mouth  or  nose 
either  directly  or  by  metastasis.    When 
they  do  this,  they  may  cause  a  great  deal  of 
disfigurement;  in  extreme  cases  the  nose 
may  even  be  completely  eaten  away. 

The  lesions  in  the  dog  are  similar  to 
those  in  man.  They  are  probably  confined 
to  the  skin.  Visceral  leishmaniosis  due  to 
L.  tropica  has  been  reported  in  dogs,  but 
many  observers  believe  that  these  are  due 
to  concurrent  infections  with  L.  donovani. 
In  infected  gerbils,  cutaneous  sores  occur 
on  the  ears. 

Immunity:      Persons  who  have  recov- 
ered spontaneously  from  classical  Oriental 
sore  have  a  solid  immunity.    This  fact  is 
so  well  known  among  the  natives  that  they 
vaccinate  themselves  on  the  arm  in  order 
to  avoid  natural,  disfiguring  ulcers  on  the 
face.     There  is  no  cross-immunity  between 
the  wet  and  dry  Old  World  types  of  the 


THE  HEMOFLAGELLATES 


71 


disease,  between  these  and  the  New  World 
forms,  or  between  L.   tropica  and  L.  dono- 
vani  infections. 

Diagnosis:     The  same  methods  are 
used  in  diagnosing  L.  tropica  as  L.  dono- 
vaiii  infections,   except  for  the  tissues  ex- 
amined.    The  parasites  are  usually  abun- 
dant in  dry  Oriental  sore,  but  are  scanty 
in  wet  Oriental  sore  and  New  World  muco- 
cutaneous leishmaniosis. 

A  skin  test,  the  Montenegro  intrader- 
mal reaction,  is  used  with  considerable 
success  in  diagnosing  American  muco- 
cutaneous leishmaniosis.     A  suspension  of 
killed  organisms  from  NNN  culture  is  in- 
jected intradermally.    In  positive  cases, 
an  erythematous  wheal  appears  in  48  hours 
and  lasts  4  or  5  days.     A  small  sterile 
papule  which  becomes  vesicular  or  pustu- 
lar develops  in  the  center  of  the  wheal. 

Treatment:     Organic  antimony  com- 
pounds are  effective  against  cutaneous 
leishmaniosis.     The  same  ones  are  used 
as  for  kala-azar. 

Control:     The  same  measures  used 
to  prevent  kala-azar  are  effective  against 
cutaneous  leishmaniosis. 


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THE  HEMOFLAGELLATES 


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Wood, 

S 

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s. 

F. 

1958. 

Chapter  4 


HISTOMOHAS 


Histomonas  belongs  to  the  order 
Rhizomastigorida,  members  of  which 
possess  both  flagella  and  pseudopods. 
Within  this  order  it  belongs  to  the  family 
Mastigamoebidae,  members  of  which  have 
1  to  4  flagella.    Histo»ionas  is  the  only 
genus  in  this  order  occurring  in  domestic 
animals. 

Genus  HISTOMONAS 
Tyzzer,   1920 

The  body  is  actively  amoeboid, 
usually  rounded,   sometimes  elongate, 
with  a  single  nucleus,   and  with  1  to  4  ex- 
tremely fine  flagella  arising  from  a  basal 
granule  close  to  the  nucleus.     A  single 
species,  H.  meleagridis  is  recognized. 


HISTOMONAS  MELEAGRIDIS 
(SMITH,    1895)    TYZZER,    1920 

Disease:    Histomonosis,  infectious 
enterohepatitis,  blackhead. 

Hosts:     Chicken,  turkey,   peafowl, 
guinea  fowl,   pheasant,   ruffed  grouse, 
quail,  chukar  partridge. 

Location:     Ceca,  liver. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  parasite  is  prac- 
tically ubiquitous  in  chickens,  altho  it 
seldom  causes  disease  in  them.    It  is  one 
of  the  most  important  causes  of  disease 
in  turkeys.     Before  control  measures  were 
developed,   it  drove  many  turkey  raisers 
out  of  the  business,   and  even  now  the  United 
States  Department  of  Agriculture  (1954)  has 
estimated  that  it  causes  an  annual  loss  of 
$3,815,000  in  turkeys  and  Sl49,000  in 
chickens  due  to  mortality  alone. 

Morphology:     This  parasite  was  first 
recognized  by  Theobald  Smith  in  1895.     He 
thought  it  was  an  amoeba  and  named  it 
accordingly.    It  was  later  confused  with  a 
number  of  other  microorganisms.    Some 
workers  thought  that  it  was  one  of  the  forms 


74  - 


HISTOMONAS 


75 


assumed  by  a  pleomorphic  Trichomonas, 
others  that  it  was  part  of  the  life  cycle  of 
a  coccidium,  and  still  others  confused  it 
with  the  budding  fungus,    Blastocyslis. 
Finally  Tyzzer  (1919,   1920,   1920a)  showed 
that  the  organism  was  a  flagellate  and  des- 
cribed it  in  detail.     His  observations  have 
been  confirmed  by  DeVolt  and  Davis  (1936), 
Bishop  (1938)  and  Wenrich  (1943)  among 
others. 

H.  meleagridis  is  pleomorphic,  its 
appearance  depending  upon  its  location  and 
the  stage  of  the  disease.     The  forms  in  the 
tissues  have  no  discernible  flagella,   altho 
there  is  a  basal  granule  near  the  nucleus. 
Tyzzer  described  three  stages.     The  in- 
vasive stage  is  found  in  early  cecal  and 
liver  lesions  and  at  the  periphery  of  older 
lesions.    It  is  extracellular.    It  is  8  to 
ITjLL  long  and  is  actively  amoeboid,  with 
blunt,   rounded  pseudopods.    Its  cytoplasm 
is  basophilic  with  an  outer  zone  of  clear 
ectoplasm  and  finely  granular  endoplasm. 
Food  vacuoles  containing  particles  of  in- 
gested material  but  no  bacteria  are  pres- 
ent. 

The  vegetative  stage  is  found  near  the 
center  of  the  lesions  and  in  slightly  older 
lesions  than  the  invasive  stage.    It  is 
larger,   measuring  12  to  15  by  12  to  21  jj,. 
It  is  less  active  than  the  invasive  stage 
and  has  few  if  any  cytoplasmic  inclusions. 
Its  cytoplasm  is  basophilic,   clear  and 
transparent.     The  vegetative  forms  are 
often  packed  tightly  together,  and  cause 
disruption  of  the  tissues. 

Tyzzer  called  the  third  form  the  re- 
sistant stage,  but  it  is  actually  no  more 
resistant  than  the  other  stages.     There 
are  no  cysts.    This  form  is  4  to  11  fi  in 
diameter,  compact,   and  seems  to  be  en- 
closed in  a  dense  membrane.     The  cyto- 
plasm is  acidophilic  and  filled  with  small 
granules  or  globules.     These  forms  may 
be  found  singly  or  they  may  be  packed  to- 
gether so  that  their  outlines  appear  rather 
angular.     They,  too,   are  extracellular, 
but  they  may  be  taken  up  by  phagocytes  or 
giant  cells. 

A  fourth  form  of  the  parasite  is  fla- 
gellated and  occurs  in  the  lumen  of  the 


ceca.    The  same  form  is  found  in  cultures. 
Its  body  is  amoeboid  and  may  be  5  to  30  [^ 
in  diameter.    Wenrich  (1943)  found  that 


Fig.   5.       Histoiiionas  meleagridis  tropho- 
zoites from  cecum.     A.    Living 
trophozoite.     B.  ,  C.  ,  D.    Tropho- 
zoites fixed  in  Schaudinn's  fluid 
and  stained  with  iron-alum  hema- 
toxylin.    X  2300  (From  Wenrich, 
1943,  J.   Morph.   72:279) 

400  individuals  from  the  ceca  of  2  phea- 
sants measured  9  to  28 /i  in  diameter  with 
a  mean  of  13.9fi,  and  that  400  individuals 
from  the  ceca  of  2  chickens  measured  5  to 
18  JJ,  in  diameter  with  a  mean  of  7.  9  |j. . 
The  cytoplasm  is  usually  composed  of  a 
clear,  outer  ectosarc  and  a  coarsely  gran- 
ular endosarc.    It  may  contain  bacteria, 
starch  grains  and  other  food  particles,  in- 
cluding an  occasional  red  blood  cell.    The 
nucleus  is  often  vesicular,  with  a  single 
dense  karyosome,  or  it  may  contain  as 
many  as  8  scattered  chromatin  granules. 
Near  the  nucleus  is  a  basal  granule  or 
blepharoplast  from  which  the  flagella  a- 
rise.     There  is  typically  a  single,   short 
flagellum,  but  as  many  as  4  may  be  pres- 
ent.    Movement  may  be  amoeboid,   and 
there  may  be  a  pulsating,   rhythmic, 


76 


HISTOMONAS 


intracytoplasmic  movement.    The  flagella 
produce  a  characteristic,  jerky,  oscillat- 
ing movement  resembling  that  of  tricho- 
monads,  but  Hislomonas  can  be  differen- 
tiated from  them  because  it  lacks  an 
undulating  membrane  and  cixostyle. 
Wenrich  (1943)  found  peculiar,  cylindrical 
feeding  tubes  in  about  15"(  of  the  individuals 
from  one  of  the  2  pheasants  he  examined 
and  also  in  some  individuals  from  a  chicken. 
These  sometimes  extended  out  as  much  as 
the  body  diameter  and  often  had  internal 
extensions  as  long  or  longer. 

This  form  is  sometimes  present  in 
large  numbers  in  the  lumen  of  the  ceca, 
but  it  is  ordinarily  absent  or  very  difficult 
to  find. 

Life  Cycle:     Reproduction  is  by  binary 
fission,   and  there  is  no  evidence  of  a  sex- 
ual cycle.    Wenrich  (1943)  considered  the 
larger,  4-flagellate  forms  in  the  ceca  to 
be  adult.     There  are  no  cysts. 

The  naked  trophozoites  are  delicate 
and  do  not  survive  more  than  a  few  hours 
when  passed  in  the  feces.     Turkeys  can  be 
infected  by  ingesting  trophozoites,   and  this 
mode  of  infection  plays  a  part  in  transmit- 
ting the  parasites  once  disease  has  ap- 
peared in  a  flock  (Tyzzer  and  Collier, 
1925).     However,   large  numbers  of  the 
parasites  must  be  ingested.     Tyzzer  (1934) 
pointed  out  that  oral  infection  with  infected 
liver  tissue  or  cecal  discharges  is  some- 
what unreliable  because  of  the  death  of  the 
protozoa  during  their  passage  thru  the  al- 
imentary tract.     Lund  (1956)  found  that 
oral  administration  of  10,000  to  100,000 
protozoa  in  saline  caused  infections  in 
about  40%  of  6-  to  9-week-old  poults,  and 
illness  in  about  20%.     However,  when  di- 
gestible materials  were  added  to  the  inoc- 
ulum, the  infection  and  morbidity  rates 
fell  sharply.     The  protozoa  remained  in 
the  gizzard  and  upper  intestine  longer  in 
the  presence  of  food,  and  were  destroyed 
before  they  reached  the  cecum.     Horton- 
Smith  and  Long  (1956a)  found  that  infections 
with  trophozoite  suspensions  could  be  pro- 
duced only  in  starved  chickens  or,  in 
chickens  that  were  feeding,  by  giving  them 
an  alkaline  mixture  just  before  dosing 
them.     They  believed  that  successful  in- 


fection depends  on  the  pH  of  the  gizzard 

and  possibly  upper  intestine.     The  pH  of 
the  starved  gizzard  is  6.  3  to  7.  0,  that  of 
chickens  on  feed  is  2.  9  to  3.  3,   and  that  of 
chickens  on  feed  which  have  received 
alkali  is  6.  2  to  6.  5. 

By  far  the  most  important  mode  of 
transmission  is  in  the  eggs  of  the  cecal 
worm,  Heterakis  galli)iariim.     Its  discov- 
ery by  Smith  and  Graybill  (1920)  was  a 
milestone  in  the  history  of  parasitology. 
This  mode  of  transmission  has  been  amply 
confirmed  by  many  workers,   and  is  the 
preferred  method  of  producing  experimental 
infections  (Tyzzer  and  Fabyan,    1922;  Tyzzer, 
1926;  Swales,    1948;  McKay  and  Morehouse, 
1948;  Lund  and  Burtner,   1958).     The  para- 
sites are  carried  inside  the  Heterakis  eggs; 
eggs  treated  with  disinfectants  or  other 
chemicals  which  do  not  kill  them  are  still 
infective. 

Infection  of  Heterakis  eggs  is  so  wide- 
spread that  Histouionas  infections  can  be 
produced  with  batches  of  eggs  taken  from  a 
very  high  percentage  of  turkeys  or  chickens 
even  if  the  hosts  do  not  appear  sick.     Not 
every  egg  is  infected,   however.     Lund  and 
Burtner  (1957)  found  that  less  than  0.  5%  of 
the  embryonated  eggs  from  experimentally 
infected  chickens  contained  the  protozoa, 
that  less  than  half  of  the  cecal  worms  they 
examined  from  these  birds  contained  Hist- 
o)iiuiias -iniected  eggs,   and  that  positive 
worms  contained  an  average  of  only  2  in- 
fected eggs  each. 

The  Heterakis  eggs  must  hatch  and 
liberate  larvae  in  order  to  transmit  the 
protozoa.    Histomonas  has  never  been  seen 
in  the  infective  eggs,   its  presence  being 
inferred  from  the  experimental  results. 
However,  Tyzzer  (1926)  found  the  protozoa 
in  half-grown  Heterakis  from  birds  with 
histomonosis,   and  (1934)  in  the  cells  of  the 
intestinal  wall  of  10-,   12-,  and  21 -day  old 
worms  from  experimentally  infected  birds, 
and  Kendall  (1959)  found  them  in  a  4-day - 
old  H.  galluiarum  larva. 

The  possibility  that  arthropods  may 
transmit  histomonosis  has  been  considered 
by  a  number  of  authors.     Mechanical  trans- 
mission by  flies  and  even  grasshoppers  is 


HISTOMONAS 


77 


possible  (Frank,   1953),  but  it  is  of  minor 
importance. 

Epidemiology:      Histomonas  is  ex- 
tremely  common  in  Heterakis-irdecieA 
chickens,  and  these  birds  constitute  the 
principal  reservoir  of  infection  for  turkeys. 
This  accounts  for  the  fact  that  it  is  almost 
impossible  to  raise  turkeys  successfully 
on  the  same  farm  with  chickens.     In  addi- 
tion, wild  gallinaceous  birds  such  as  the 
wild  turkey,  pheasant,  quail  and  ruffed 
grouse  may  be  infected,  but  their  role  as 
reservoirs  of  infection  for  domestic  tur- 
keys has  not  been  properly  assessed. 

Birds  become  infected  most  commonly 
by  ingesting  infected  Heterakis  eggs.    In- 
fective eggs  can  survive  for  one  to  two 
years  or  even  longer  in  the  soil.     Farr 
(1956)  infected  chickens  and  turkeys  with 
Hisfonioiias  from  eggs  which  had  been  in 
the  soil  in  Maryland  for  66  weeks. 

Pathogenesis:      Histomonosis  can 
affect  turkeys  of  all  ages;  the  course  and 
mortality  of  the  disease  vary  with  age. 
Poults  less  than  3  weeks  old  are  refrac- 
tory according  to  Swales  and  Frank  (1948), 
but  from  this  age  to  about  12  weeks,  the 
disease  is  acute  and  may  cause  losses 
averaging  50%  of  the  flock  and  ranging  up 
to  100%.     The  birds  often  die  2  or  3  days 
after  showing  the  first  signs  of  disease. 
In  older  birds,  the  disease  is  more  chronic, 
and  recovery  may  take  place.    The  mortal- 
ity decreases  with  age,  and  losses  in  these 
birds  rarely  exceed  25%.    However,  even 
birds  of  breeding  age  may  be  affected. 

Chickens  are  much  less  susceptible 
than  turkeys.     They  ordinarily  show  no 
signs  of  disease,  but  serious  outbreaks 
may  occur  in  young  birds.     Histomonosis 
occasionally  occurs  in  the  peafowl  (Gray- 
bill,   1925;  Dickinson,   1930),  guinea  fowl 
(Graybill,  1925)  and  quail  (GraybiU,  1925). 
Serious  outbreaks  may  occur  in  captive 
ruffed  grouse  (Tyzzer  and  Fabyan,   1920; 
Graybill,   1925)  and  chukar  partridges 
(Honess,   1956).    Altho  the  parasite  occurs 
in  pheasants,  it  is  apparently  not  very 
pathogenic  for  them. 

When  the  histomonads  are  released 
in  the  cecum,  they  enter  the  wall  and 


multiply,  causing  characteristic  lesions. 
Later  they  pass  by  way  of  the  blood  stream 
to  the  liver. 

The  incubation  period  is  15  to  21  days. 
The  first  sign  of  disease  is  droopiness. 
The  birds  appear  weak  and  drov/sy,  and 
stand  with  lowered  head,   ruffled  feathers 
and  drooping  wings  and  tail.     There  is  a 
sulfur-colored  diarrhea.     The  head  may 
or  may  not  become  darkened.     This  sign, 
which  is  responsible  for  the  name  black- 
head, may  also  occur  in  other  diseases, 
so  the  term  is  a  misnomer. 

The  principal  lesions  of  histomonosis 
occur  in  the  cecum  and  liver.     One  or  both 
ceca  may  be  affected.    Small,  raised  pin- 
point ulcers  containing  the  parasites  are 
formed  first.     These  enlarge  and  may  in- 
volve the  whole  cecal  mucosa.    Sometimes 
the  ulcers  perforate  the  cecal  wall  and 
cause  peritonitis  or  adhesions.     The  mu- 
cosa becomes  thickened  and  necrotic.    It 
may  be  covered  with  a  characteristic,  foul- 
smelling,  yellowish  exudate  which  may 
consolidate  to  form  a  dry,  hard,  cheesy 
plug  that  fills  the  cecum  and  adheres 
tightly  to  its  wall.    The  ceca  are  markedly 
inflamed  and  often  enlarged. 

The  liver  lesions  are  pathognomonic o 
They  are  circular,  depressed,  yellowish 
to  yellowish  green  areas  of  necrosis  and 
tissue  degeneration.    They  are  not  encap- 
sulated, but  merge  with  the  healthy  tissue. 
They  vary  in  diameter  up  to  a  centimeter 
or  more  and  extend  deeply  into  the  liver. 
In  older  birds  the  lesions  are  often  con- 
fluent. 

Other  organs  such  as  the  kidney  and 
lung  may  occasionally  be  affected.    P.  P. 
Levine  (1947),  for  example,  described 
numerous  white,   round  areas  about  1  mm 
in  diameter  in  the  kidneys  of  an  affected 
turkey. 

The  parasites  can  be  readily  found  on 
histologic  examination  of  the  lesions.     Hy- 
peremia, hemorrhage,   lymphocytic  infil- 
tration, and  necrosis  occur,  and  macro- 
phages and  giant  cells  are  present.    The 
pathology  of  histomonosis  in  turkeys  has 
been  described  by  Malewitz,  Runnels  and 
Calhoun  (1958)  among  others. 


78 


HISTOMONAS 


McGuire  and  Cavett  (1952)  studied  the 
effect  of  histomonosis  on  the  blood  picture 
of  experimentally  infected  turkeys.    The 
non-protein  nitrogen,  uric  acid  and  hemo- 
globin levels  declined  progressively,  but 
tended  to  recover  just  before  death.    The 
blood  sugar  rose  during  the  incubation 
period  but  decreased  during  development 
of  the  liver  lesions;  severe  hypoglycemia 
was  present  just  before  death.    The  total 
leucocyte  count  rose  as  the  result  of  pro- 
liferation of  heterophils,  myelocytes  and 
monocytes. 

If  the  birds  recover,  the  protozoa  dis- 
appear from  the  tissues,  and  repair  takes 
place.     The  exudate  and  necrotic  tissue  in 
the  ceca  are  incorporated  into  the  cecal 
plug,  which  becomes  smaller  and  is  finally 
passed.    U  the  lesions  were  not  too  severe, 
the  ceca  may  eventually  appear  entirely 
normal,  but  in  other  cases  there  may  be 
so  much  scarring  that  the  lumen  is  oblit- 
erated.   In  the  repair  process,  the  lesions 
are  invaded  by  blood  vessels,  lymphoid 
cells  and  connective  tissue.    The  liver 
lesions  may  be  completely  repaired  or 
there  may  be  extensive  scar  tissue. 

Immunity:     Birds  which  recover  from 
histomonosis  are  immune  to  reinfection. 
In  addition,  as  mentioned  above,  suscep- 
tibility decreases  with  age. 

Lund  (1959)  found  that  infection  of  tur- 
keys with  a  nonpathogenic  strain  of  Histo- 
monas  did  not  protect  the  birds  against 
subsequent  infection  with  a  pathogenic 
strain  introduced  by  feeding  Heterakis  eggs, 
altho  it  did  afford  some  protection  against 
rectally  introduced  pathogenic  histomonads. 

Diagnosis:     Histomonosis  can  be  di- 
agnosed from  its  lesions.    Those  in  the 
liver  are  pathognomonic.    In  case  of  doubt 
and  in  order  to  differentiate  the  liver  le- 
sions from  those  caused  by  tumors,  tuber- 
culosis or  mycotic  infections,  histologic 
examination  is  desirable.    The  cecal  le- 
sions can  be  distinguished  from  those 
caused  by  coccidia  by  microscopic  exam- 
ination of  scrapings  from  the  mucosa. 

Cultivation:     Histomonas  was  first 
cultivated  by  Drbohlav  (1924)  in  a  diphasic 
medium  consisting  of  coagulated  egg  white 


slants  overlaid  with  blood  bouillon  contain- 
ing 1%  peptone.    It  has  since  been  culti- 
vated in  a  number  of  other  media,  both  di- 
phasic and  monophasic  (Tyzzer,   1934; 
De Volt  and  Davis,   1936;  Bishop,   1938). 
Delappe  (1953,   1953a)  found  that  addition 
of  penicillin  or  streptomycin  or  both  to 
Laidlaw's  culture  medium  facilitated  the 
initial  isolation  of  the  protozoa,  but  he  was 
unable  to  obtain  axenic  cultures.    When  the 
bacteria  disappeared,  the  protozoa  did 
likewise. 

Treatment:     Since  histomonosis  can 
be  prevented  by  proper  management,  drug 
therapy  should  be  regarded  as  a  secondary 
line  of  defense  against  the  disease.    The 
chemotherapy  of  this  disease  has  been  re- 
viewed by  Wehr,   Farr  and  McLoughlin 
(1958). 

While  a  number  of  phenylarsonic  acid 
and  quinoline  derivatives  have  been  used 
with  some  success  in  the  past,  the  only 
one  of  them  which  is  now  used  to  any  extent 
is  4-nitrophenylarsonic  acid.    When  fed  as 
0.0125  to  0.075%  of  the  mash  or  0.006  to 
0.  04%  of  the  drinking  water  for  3  days  be- 
fore and  21  days  after  experimental  infec- 
tion, this  compound  prevents  death.    How- 
ever, there  is  a  high  relapse  rate  following 
cessation  of  treatment.     Hence,  to  be  effec- 
tive this  compound  must  be  fed  continuously 
until  5  days  before  slaughter.     Mashes  con- 
taining 0.01  to  0.03%  of  this  compound 
stimulate  growth,  but  0.02%  in  the  drinking 
water  decreases  egg  production  of  adults 
and  growth  and  livability  of  poults  (Moreng 
and  Bryant,   1956). 

Thiazole  derivatives  are  used  most 
commonly  against  histomonosis.    Three  of 
these  are  enheptin,  acetylenheptin,  and 
nithiazide  (Hepzide).    The  first  is  2-amino- 
5-nitrothiazole,  and  the  other  two  are  de- 
rivatives of  it.     Enheptin  was  introduced 
by  Waletzky,  Clark  and  Marson  (1950), 
and  its  activity  was  confirmed  by  a  number 
of  workers,   including  McGregor  (1953), 
Jungherr  and  Winn  (1950),  DeVolt,   Tromba 
and  Hoist  (1954),  and  Joyner  and  Kendall 
(1955).    Acetylenheptin  (2-acetylamino-5- 
nitrothiazole)  was  found  by  Grumbles, 
Boney  and  Turk  (1952,   1952a,   1952b)  to  be 
just  as  effective  as  enheptin;  it  was  also 
studied  by  Brander  and  Wood  (1955)  and 


HISTOMONAS 


79 


Cooper  and  Skulski  (1957)  among  others. 
Nithiazide  (l-ethyl-3-[  5-nitro-2-thiazolyl] 
urea)  was  introduced  by  Cuckler  et  al. 
(1956,   1957)  and  Cuckler  and  Malanga 
(1956). 

These  drugs  have  both  prophylactic, 
suppressive  and  therapeutic  value.     En- 
heptin  is  usually  fed  continuously  in  the 
mash  at  the  rate  of  0.05%  for  prevention 
and  suppression.    If  feeding  is  begun 
within  2  days  after  the  infective  dose  of 
Histomonas  is  given  in  an  experimental 
infection,  it  will  almost  completely  pre- 
vent the  disease.    If  it  is  begun  later  than 
this,   it  will  suppress  the  disease  as  long 
as  it  is  continued,  but  after  it  is  withdrawn, 
histomonosis  will  reappear  in  the  flock. 
If  enheptin  is  to  be  used  in  treating  turkeys 
which  already  show  signs  of  disease,  0. 1 
to  0.  2%  of  the  drug  is  mixed  in  the  feed. 
Not  all  the  birds  will  recover,  but  quite  a 
high  percentage  do.    Acetylenheptin  is 
used  in  much  the  same  way.     The  preven- 
tive level  of  nithiazide  in  the  feed  recom- 
mended by  the  manufacturer  in  1958  was 
0.03%. 

Potential  hazards  are  often  associ- 
ated with  feeding  drugs  continuously. 
Hudson  and  Pino  (1952)  and  Pino,   Rosen- 
blatt and  Hudson  (1954)  found  that  enheptin 
prevented  or  delayed  sexual  maturity  in 
chickens  and  turkeys.    When  fed  in  the 
ration  to  chickens,  it  produced  complete - 
sexual  involution  or  inhibition  in  both 
males  and  females.    In  young  birds,  sex- 
ual development  did  not  take  place,  while 
in  older  ones  the  testes,  ovary  and  oviduct 
atrophied.     The  effect  was  less  marked  in 
turkeys,  altho  0.1%  enheptin  in  the  ration 
reduced  the  level  of  reproductive  perform- 
ance.   This  effect  was  found  to  be  due  to 
inhibition  of  gonadotropin  secretion  by  the 
pituitary,  and  could  be  counteracted,  at 
least  in  part,  by  simultaneous  administra- 
tion of  gonadotropic  hormone.    Shellabar- 
ger  and  Schatzlein  (1955)  found  that  enhep- 
tin caused  rats  to  have  larger  thyroid 
glands  and  to  accumulate  less  iodine  than 
normal  rats.    They  suggested  that  these 
antithyroid  properties  might  explain  why 
enheptin  inhibits  the  secretion  of  pituitary 
gonadotropin  in  the  chicken. 


Grumbles,  Boney  and  Turk  (1952) 
and  Cooper  and  Skulski  (1957)  compared 
enheptin  with  acetylenheptin.     The  former 
found  that  0. 1%  enheptin  in  the  feed  reduced 
production,  fertility  and  hatchability  in  tur- 
keys, but  that  acetylenheptin  had  no  such 
effect.     The  latter  found  that  enheptin  de- 
creased spermatogenesis  and  egg  produc- 
tion and  increased  embryo  mortality  when 
fed  to  chickens  at  preventive  levels.    Acet- 
ylenheptin was  less  toxic.    It  had  no  effect 
on  egg  production,  fertility  or  embryo 
mortality,  and  reduced  sperm  production 
only  slightly. 

According  to  Cuckler,   Porter  and  Ott 
(1957),  0.1%  nithiazide  in  the  feed  did  not 
interfere  with  growth,  maturation  or  re- 
production of  chickens  or  turkeys. 

The  nitrofuran,  furazolidone  (NF-180, 
Furoxone),  was  found  by  McGregor 
(1953a,   1954),   Horton-Smith  and  Long 
(1955,   1956)  and  Costello  and  DeVolt  (1956) 
to  suppress  histomonosis  when  fed  at  the 
rate  of  0.  01  to  0.  04%  in  the  feed.     Even 
with  the  higher  doses,   however,   some  re- 
lapses occurred  after  medication  was 
stopped,  and  slight  lesions  were  found  in 
treated  birds  killed  during  the  experiments. 

Cooper  (1956)  reported  that  feeding 
0.  02%  furazolidone  to  pullets  for  12  weeks 
had  no  effect  on  body  weight,  egg  produc- 
tion, fertility  or  hatchability,  but  Cooper 
and  Skulski  (1955,  1956)  found  that  feeding 
this  drug  to  cockerels  and  roosters  re- 
duced the  number  of  spermatozoa  and  de- 
creased weight  gains. 

Control:     Histomonosis  can  be  pre- 
vented by  good  management.    Turkeys 
should  be  kept  separate  from  chickens, 
since  chickens  are  carriers.     Young  tur- 
keys should  be  kept  separate  from  adults. 
The  same  attendants  should  not  care  for 
chickens  and  turkeys.    Persons  who  go 
from  one  flock  to  another  should  take  care 
not  to  carry  the  infection  on  contaminated 
shoes  or  equipment. 

Young  birds  should  be  raised  on  hard- 
ware cloth,  and  the  droppings  should  be 
removed  regularly.    When  the  poults  are 


80 


HISTOMONAS 


old  enough  to  move  onto  range,  they  should 
be  placed  on  clean  ground  where  neither 
turkeys  nor  chickens  have  been  kept  for  2 
years.     The  length  of  time  infective  cecal 
worm  eggs  survive  in  the  soil  depends  upon 
soil  type,  weather  and  amount  of  cover 
provided  by  vegetation.     They  will  survive 
only  a  few  weeks  on  barren  soils  in  warm, 
dry  regions,  but  may  remain  alive  for 
several  years  in  heavy  soils  in  moist  cli- 
mates. 


roughage.    The  medicated  ration  is  given 
for  5  to  7  days,  the  regular  ration  is  fed 
for  about  15  days,  the  medicated  ration  is 
then  given  again  and  alternated  as  before 
with  regular  feed  until  about  3  weeks  be- 
fore the  birds  are  to  be  marketed.     Pheno- 
thiazine  should  not  be  fed  during  these  3 
weeks. 


LITERATURE  CITED 


The  range  should  be  rotated  at  regular 
intervals.    Different  farmers  use  different 
intervals.     Many  of  them  move  the  birds 
along  every  week,  not  returning  to  the 
same  place  during  the  same  season.    An- 
other rotation  system  which  has  been  rec- 
ommended is  to  move  the  birds  thru  a 
series  of  4  lots,  allowing  them  to  remain 
on  each  for  a  month.     The  frequency  of  ro- 
tation depends  on  the  climate.    In  cool, 
damp  climates  the  birds  should  be  moved 
at  least  every  10  days,  but  in  hot,  dry 
climates  they  need  be  moved  less  frequent- 
ly, and  it  is  even  possible  to  raise  turkeys 
successfully  without  changing  the  range  if 
the  area  around  the  feeders,  waterers, 
roosts  and  shelters  is  kept  dry. 

Low  areas  and  streams  that  drain 
poultry  yards  should  be  fenced  off. 

The  feeders  and  waterers  should  be 
placed  on  wire  platforms.     Most  of  the 
droppings  are  deposited  around  them,  and 
this  practice  keeps  the  turkeys  from  getting 
at  them.    Wire  should  also  be  used  beneath 
roosts  and  in  shelters  to  keep  the  birds 
from  their  droppings. 

Treating  the  birds  with  phenothiazine 
to  prevent  histomonosis  by  killing  the 
cecal  worms  has  been  suggested.    It  is  in- 
effective in  controlling  active  outbreaks, 
but  may  help  prevent  future  ones.     Pheno- 
thiazine kills  the  cecal  worms,  but  does 
not  prevent  their  eggs  from  hatching  and 
releasing  the  histomonads  (Wehr  and 
Olivier,   1946). 

To  eliminate  Heterakis,  0.  5%  pheno- 
thiazine is  mixed  with  the  feed  if  the  birds 
are  not  getting  roughage,  and  1.0%  if  they 
are  on  good  range  or  getting  supplementary 


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406-409. 
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Chapter  5 


WE 
TRICHOmUdS 


The  trichomonads  belong  to  the  family 
Trichomonadidae  within  the  order  Trich- 
omonadorida.     The  body  is  usually  piriform, 
with  a  rounded  anterior  end  and  a  pointed 
posterior  end.    There  is  a  single  nucleus 
in  the  anterior  part  of  the  body.     Anterior 
to  the  nucleus  is  a  blepharuplasl  composed 
of  several  basal  granules .     Two  to  five 
anterior  flagella  and  a  posterior  flagellum 
arise  from  the  blepharoplast.     The  posterior 
flagellum  passes  along  the  border  of  an  iin- 
dHlati)ig  me»ibrane  which  extends  along  the 
side  of  the  body;  a  secondary  or  accessory 
filament  may  be  associated  with  it.     The 
posterior  flagellum  may  or  may  not  extend 
beyond  the  undulating  membrane  as  a  free 
flagellum.     A  filamentous  costa  arises  from 
the  blepharoplast  and  runs  along  the  base  of 
the  undulating  membrane.     A  parabasal 
body  arises  from  the  blepharoplast;  there 
may  or  may  not  be  a  parabasal  filament 
at  its  posterior  end.    A  clear,  rod-like 
axostyle  also  arises  from  the  blepharoplast 
and  passes  thru  the  center  of  the  body  to 
emerge  from  the  posterior  end.     The  an- 
terior end  of  the  axostyle  is  enlarged  to 
form  a  capitulum.    There  may  or  may  not 
be  a  chromatic  ring  at  the  point  of  emer- 
gence of  the  axostyle.    There  may  or  may 
not  be  a  cytostome  near  the  anterior  end. 
Just  anterior  to  the  blepharoplast  and  lying 
along  the  anterior  margin  of  the  body  is  a 
pelta  which  stains  with  silver.    In  addition 
to  these  structures,  there  may  be  various 
granules  within  or  along  the  axostyle, 
along  the  costa,  or  in  other  locations. 


An  electron  micrograph  study  of 
Tritrichomonas  muris  by  Anderson  (1955) 
revealed  the  fine  structures  of  these  or- 
ganelles which  may  be  taken  to  represent 
the  group.    He  found  that  the  blepharoplast 
appears  to  be  limited  by  a  membrane  and 
to  contain  basal  granules  for  each  organelle. 
The  anterior  and  posterior  flagella  are 
composed  of  2  central  and  9  peripheral 
fibrils.     The  accessory  filament  is  com- 
posed of  two  differentiated  meshwork 
areas.    The  undulating  membrane  is  com- 
posed of  a  series  of  lamellae  300  to  400  A 
thick;  it  is  attached  to  the  outer  surface  of 
the  body  by  fine  fibers  167  to  300  A  thick. 


82  - 


THE  TRICHOMONADS 


83 


PARABASAL    BODY 
COSTA 


PARABASAL 

FILAMENT 


UNDULATING 
MEMBRANE 


FREE   FLAGELLUM 


CHROMATIC    RING 


TRICHOMONAS 
Fig.   6.       Structures  of  Tyicliomonas.     (Original) 

The  costa  consists  of  a  series  of  discs 
about  370  A  thick  and  490  A  apart,   em- 
bedded in  a  matrix;  it  is  attached  to  the 
inner  surface  of  the  body  wall  by  exten- 
sions of  the  discs.     The  axostyle  is  lim- 
ited by  a  double,   corrugated  membrane. 
The  chromatic  ring  is  composed  of  a  series 
of  rods  about  640  A  thick.     The  parabasal 
body  consists  of  a  series  of  filaments  about 
190  A  thick.     The  chromatic  granules  along 
the  costa,  inside  the  axostyle  and  scattered 
in  the  cytoplasm  are  irregular  in  shape  and 
vacuolated.    The  mitochondria  are  spher- 
ical and  contain  a  varying  number  of  pro- 
jections internally. 

Trichomonads  are  divided  into  sev- 
eral genera  on  the  basis  of  the  number  of 
their  anterior  flagella.    Ditrichomonas 
has  2,   Tritrichomonas  has  3,   Trichomonas 
has  4,  and  Pentatrichonionas  has  5.    These 
genera  are  closely  related;  Mehra,  Levine 
and  Reber  (1960),  for  example,  found  in  a 
column  chromatographic  study  of  the  hy- 
drolysates  of  Tritrichomonas  foetus ,    T. 
suis,    Trichomonas  gallinae,    T.  galli- 
narum  and  T.  buttreyi,  that  they  are  all 
composed  of  the  same  amino  acids  but  that 
there  are  some  differences  in  the  amounts 


of  each  amino  acid  present  in  the  different 
species. 

Gabel  (1954)  established  the  genus 
Paratrichomonas  for  P.  marmotae  from 
the  woodchuck  and  possibly  T.  batrachorum 
from  the  frog.    Paratrichomonas  differs 
from   Tritrichomonas  orincipally  in  having 
a  ring-shaped  parabasal  body.     T.  buttreyi 
of  the  pig  resembles  it,  but  has  4  anterior 
flagella.    There  does  not  seem  to  be  suf- 
ficient justification  for  accepting  this  genus, 
at  least  at  present. 

Morgan  (1943,   1946)  and  Trussell  (1947) 
have  given  host-parasite  lists  of  the  trich- 
omonad  species. 

There  are  several  species  of  tricho- 
monads in  domestic  animals  and  man,  but 
the  nomenclatorial  status  and  host-parasite 
relations  of  many  of  them  are  not  yet  clear. 
They  have  been  found  in  the  cecum  and 
colon  of  practically  every  species  of  mam- 
mal or  bird  that  has  been  examined  for 
them,  and  they  also  occur  in  reptiles,  am- 
phibia, fish  and  many  invertebrates.     Those 
in  the  termite  gut  are  particularly  well 
known.     Many  of  the  cecal  trichomonads 
look  alike,   and  cross-transmission  studies 
have  shown  that  many  of  them  can  be  easily 
transmitted  from  one  host  species  to  an- 
other.    Some  mammalian  trichomonads 
have  even  been  transmitted  successfully  to 
day-old  chicks,  altho  they  will  not  become 
established  in  older  birds.     Further  and 
extensive  studies  are  needed  to  establish 
the  correct  names  and  host  spectra  of  all 
but  a  few  trichomonads. 

Most  trichomonads  are  non- pathogenic 
commensals,  but  a  few  are  important  path- 
ogens.    None  of  the  cecal  trichomonads  has 
ever  been  proven  to  be  pathogenic,  altho 
some  people  have  thought  that  they  were 
because  they  were  found  in  animals  which 
had  enteritis  or  diarrhea.     However,  the 
mere  presence  of  an  organism  in  a  diseased 
animal  does  not  mean  that  the  organism 
caused  the  disease.    The  latter  may  have 
set  up  conditions  favorable  to  the  organism's 
growth  and  multiplication.    This  is  espe- 
cially true  of  the  cecal  trichomonads,  which 
flourish  in  a  fluid  or  semi-fluid  habitat. 


84 


THE  TRICHOMONADS 


The  life  cycle  of  trichomonads  is  sim- 
ple.   They  reproduce  by  longitudinal  binary 
fission.     No  sexual  stages  are  known. 
There  are  no  cysts,  altho  degenerating  or 
phagocytized  individuals  (or  entirely  dif- 
ferent organisms  such  as  Blaslocyslis) 
have  been  mistaken  for  them. 

Genus  TRITRICHOMONAS 
Kofoid,   1920 

Members  of  this  genus  have  3  anterior 
flagella. 


TRITRICHOMONAS  FOETUS 

(RIEDMULLER,   1928) 

WENRICH  AND   EMMERSON,   1933 

Synonyms:      Trichomonas  utero- 
vaginalis  vilulae,   T.  bovis,   T.  genitalis, 
T.   bovinus,    T.  mazzanti. 

Disease:     Bovine  trichomonad  abor- 
tion, bovine  genital  trichomonosis. 

Hosts:     Ox,   zebu,   possibly  pig, 
horse,   roe  deer. 


productive  disorders  in  cows  bred  by  in- 
fected western  range  bulls  may  amount  to 
about  S800  annually  per  infected  bull.     On 
this  basis,  the  23  infected  bulls  they  found 
in  their  survey  would  cost  their  owners 
about  $18,000  a  year.     The  annual  loss  due 
to  an  infected  bull  in  an  artificial  insemin- 
ation ring  would  be  considerably  greater 
than  this. 

Morphology:     The  morphology  of  T. 
foetus  has  been  studied  by  Wenrich  and 
Emmerson  (1933),  Kirby  (1951)  and  Ludvik 
(1954),   among  others.     The  body  is  spin- 
dle- to  pear-shaped,   10  to  25/i  long  and 
3  to  15|U  wide.    It  has  3  anterior  flagella 
and  a  posterior  flagellum  which  trails  as 
a  free  flagellum  about  as  long  as  the  an- 
terior flagella.     The  undulating  membrane 
extends  almost  the  full  length  of  the  body 
and  has  an  accessory  filament  along  its 
margin.     The  costa  is  prominent.     The 
axostyle  is  thick  and  hyaline,  with  a  cap- 
itulum  containing  endoaxostylar  granules 
and  a  chromatic  ring  at  its  point  of  emer- 
gence from  the  posterior  end  of  the  body. 
The  parabasal  body  is  sausage-  or  ring- 
shaped.     A  cytostome  is  present.     There 
is  no  pelta. 


Location:     Genital  tract. 

Geographic  Distribution:     Worldwide. 
Morgan  and  Beach  (1942)  mapped  the  geo- 
graphic distribution  of  bovine  trichomon- 
osis. 


Prevalence:     Altho   T.  foetus  is 
known  to  be  widely  distributed,  few  studies 
have  been  made  of  its  incidence.    It  is 
especially  common  in  southern  Germany 
and  Switzerland,  up  to  30%  of  the  cattle 
having  been  found  infected  in  some  areas. 
In  the  U.  S.  ,  it  is  probably  third  to  brucel- 
losis and  leptospirosis  as  a  cause  of  abor- 
tion in  cattle.     In  a  survey  of  383  beef 
bulls  in  Utah,  Idaho  and  Colorado,   Fitz- 
gerald et  at.  (1958)  found  6%  to  be  infected. 

The  USDA  Agricultural  Research  Serv- 
ice (1954)  estimated  that  bovine  trichomon- 
osis causes  an  annual  loss  of  $750,000  in 
the  United  States.     This  figure  is  probably 
low.     Fitzgerald  et  at.  (1958)  estimated 
that  losses  in  production  because  of  re- 


Fig.  7. 


Tyilrichomonas  foetus.  X  3400 
(From  Wenrich  and  Emmerson, 
1933,   J.   Morph.    55:193) 


Pathogenesis:     A  great  deal  has  been 
written  about  bovine  trichomonosis. 


THE  TRICHOMONADS 


85 


Morgan's  (1946)  review  listed  447  refer- 
ences,  and  many  more  papers  have  been 
published  since  then.     Among  more  recent 
papers  on  its  pathogenesis  are  those  of 
Morgan  (1947),   Bartlett  (1947),   Bartlett 
and  Dikmans  (1949),   Bartlett,   Moist  and 
Spurrell  (1953),   Laing  (1956)  and  Gabel 
et  al.   (1956). 

Bovine  trichomonosis  is  a  venereal 
disease,  transmitted  by  coitus.    It  can 
also  be  transmitted  by  artificial  insemin- 
ation.    Non-venereal  transmission  is  very 
rare  under  natural  conditions.     After  in- 
fection of  the  female,  the  trichomonads 
multiply  at  first  in  the  vagina,   causing  a 
vaginitis.     They  are  most  numerous  here 
14  to  18  days  after  infection  (Hammond 
and  Bartlett,   1945).     They  invade  the 
uterus  thru  the  cervix.     They  may  disap- 
pear from  the  vagina  or  they  may  remain 
there,   producing  low-grade  inflammation 
and  catarrh. 

Early  abortion  is  characteristic  of 
bovine  trichomonosis.     Abortion  usually 
occurs  1  to  16  weeks  after  breeding.     The 
foetus  is  often  so  small  that  it  is  not  ob- 
served by  the  owner,  and  he  does  not 
realize  that  abortion  has  occurred,  be- 
lieving that  the  animal  failed  to  conceive 
and  that  its  heat  periods  are  irregular. 
Morgan  and  Hawkins  (1952)  knew  of  only 
6  reports  in  the  literature  of  abortion  due 
to   T.  foetus  after  6  months  gestation. 

If  the  placenta  and  fetal  membranes 
are  completely  eliminated  following  abor- 
tion, the  animal  usually  recovers  spon- 
taneously.    This  is  the  most  common 
course.     If,   however,   part  of  the  placenta 
or  membranes  remain,  a  chronic  catar- 
rhal or  purulent  endometritis  results  which 
which  may  cause  permanent  sterility. 

Sometimes  the  animal  does  not  abort, 
but  the  fetus  dies  and  becomes  macerated 
in  the  uterus.     Pyometra  results,   and  the 
uterus  may  contain  several  quarts  of  a 
thin,   greyish  white  fluid  swarming  with 
trichomonads.    In  the  absence  of  bacteria, 
this  fluid  is  almost  odorless.     The  cervi- 
cal seal  may  remain  intact  or  it  may  allow 
a  small  amount  of  fluid  to  escape  when  the 
animal  is  lying  down.    Animals  with  pyo- 


metra seldom  come  in  heat,   and  the  owner 
may  believe  them  to  be  pregnant.     In  long- 
standing cases,  the  trichomonads  may 
disappear  from  the  uterine  fluid. 

Occasionally  normal  gestation  and 
calving  may  occur  in  an  infected  animal, 
but  this  is  rare. 

In  the  bull,  the  most  common  site  of 
infection  is  the  preputial  cavity,  altho  the 
testes,  epididymis  and  seminal  vesicles 
may  sometimes  be  involved.     Spontaneous 
recovery  is  rare;  bulls  remain  infected 
permanently  unless  treated.     The  numbers 
of  trichomonads  fluctuate,  the  intervals 
between  peaks  being  5  to  10  days  according 
to  Hammond  el  al.  (1950). 

Immunology:     Cows  or  heifers  which 
recover  from  infection  are  usually  rela- 
tively immune,  altho  reinfections  can  occur. 

A  number  of  investigators  have  studied 
various  immunological  responses  to  trich- 
omonad  infection.    Kerr  and  Robertson 
(1945)  showed  that  there  is  more  than  one 
serological  strain  of  T.  foetus.      McEnte- 
gart  (1956)  found  that  T.  foetus  var.  belfast 
and  T.  foetus  var.  )uaiiley  differed  sero- 
logically from  each  other  and  from  T. 
vaginalis.     Menolasino  and  Hartman  (1954) 
were  unable  to  distinguish  T.  foetus  from 
T.  vaginalis   serologically,  but  McDonald 
and  Tatum  (1948)  and  Schoenherr  (1956) 
were  able  to  do  so.     Both  also  found  sero- 
logical differences  between  T.foetus  and 
Pentatyicho>no)ias  lioiiiiiiis,    and  the  latter 
between  T. /oe/;(S  and  T  richonionas  gal- 
liuae.     Sanborn  (1955)  found  that  T.  foetus 
differed  serologically  from  the  large  pig 
cecal  trichomonad,   T.  suis  and  from  the 
pig  nasal  trichomonad. 

Kerr  and  Robertson  (1941,   1943)  and 
Pierce  (1947)  studied  the  agglutination  test 
in  cattle,  and  Feinberg  (1952)  described  a 
capillary  agglutination  test.    Kerr  (1943) 
felt  that  his  test  was  positive  in  about  60% 
of  all  infected  cattle,  but  Morgan  (1943a) 
considered  it  impractical.    The  wide  dis- 
tribution in  the  animal  kingdom  of  non- 
specific antibodies  against   T.  foetus  was 
brought  out  by  Morgan  (1944),  who  showed 
that  the  sera  of  the  carp,  horned  lizard 


86 


THE  TRICHOMONADS 


and  leopard  frog  agglutinated  T.  foetus  at 
1:2,  those  of  the  gold  fish,   pigeon  and 
domestic  rabbit  at  1:4,  those  of  the  guinea 
fowl  and  chicken  at  1:8,  those  of  the  turkey 
and  sheep  at  1:16,  those  of  deer  and  goat 
at  1:32,  that  of  the  cow  at  1:128  and  that 
of  the  horse  at  1:1024. 

Nakabayasi  (1952)  distinguished  be- 
tween agglutination  and  agglomeration. 
With  immune  rabbit  and  infected  guinea 
pig  sera,  agglomeration  reached  its  max- 
imum within  30  minutes  and  then  decreased 
gradually  as  the  agglomerated  individuals 
separated.     On  the  other  hand,  the  agglu- 
tination reaction  reached  its  maximum 
within  about  an  hour  and  did  not  reverse. 
Levine  et  al.   (unpublished)  have  seen  ag- 
glomeration of  T.  foetus  following  mixture 
with  fresh  culture  media  containing  inac- 
tivated serum. 

Kerr  and  Robertson  (1954,   1956) 
found  "normal  agglutinin"  in  the  blood  of 
calves  which  they  apparently  acquired  in 
the  colostrum;  this  agglutinin  disappeared 
after  17  to  55  days.     Injection  of  calves 
less  than  4  weeks  old  did  not  induce  anti- 
body formation,  but  instead  caused  im- 
pairment of  antibody  production  (immuno- 
logical paralysis)  which  persisted  for 
about  2  years. 

Complement  fixation  and  precipitin 
reactions  have  been  studied,  but  with  un- 
satisfactory results  (Svec,   1944;  Morgan, 
1948). 

Kerr  (1944)  developed  an  intradermal 
test,  using  a  trichloracetic  acid-precip- 
itated extract  of  T.  foetus  called  "tricin.  " 
Positive  reactions  appear  in  10  minutes, 
reach  their  peak  within  30  minutes  and 
disappear  in  about  6  hours.     Fifty  of  592 
cows  at  an  abattoir  were  positive  to  this 
test,   and  trichomonads  were  found  in  11 
of  them  on  direct  examination.     Tricho- 
monads were  also  found  in  11  of  34  bulls 
which  were  positive  to  the  skin  test. 
Morgan  (1948)  obtained  negative  results 
with  skin  tests  with  a  number  of  different 
antigens.    Kerr,   McGirr  and  Robertson 
(1949)  found  that  cattle  could  be  desensi- 
tized to  the  skin  test  by  injecting  antigen 
intramuscularly,   instilling  it  into  the 


uterus  of  non-pregnant  cows,  or  by  inject- 
ing adreno-cortical  hormone  or  sphingo- 
myelin at  parturition.     Absorption  of 
antigen  from  acute  uterine  infections  also 
desensitized  the  animals. 

A  local  immune  reaction  takes  place 
in  the  vaginal  mucosa  of  infected  animals. 
In  addition,  the  uterine  mucosa  is  sensi- 
tized (Kerr  and  Robertson,   1953).     The 
presence  of  agglutinins  in  the  vaginal 
mucus  prompted  the  development  of  a 
mucus  agglutination  diagnostic  test  by 
Pierce  (1947a,   1949)  and  Florent  (1947, 
1948,   1957).     This  test  is  considerably 
better  than  the  blood  agglutination  test, 
but,  according  to  Pierce  (1949),  must  still 
be  regarded  as  only  a  herd  test  because  a 
number  of  infected  animals  fail  to  react. 
Unsatisfactory  results  are  obtained  with 
estral  and  post-estral  vaginal  mucus  and 
with  purulent  uterine  mucus  containing 
trichomonads.     Mucus  from  pregnant  an- 
imals sometimes  gives  a  false  positive 
reaction.    Schneider  (1952),  too,  consid- 
ered the  mucus  agglutination  test  simply 
an  adjunct  to  other  means  of  diagnosis. 

Morgan  (1947a)  found  that  a  series  of 
16  intramuscular  or  intravenous  injec- 
tions with  living  T.  foetus  over  a  period  of 
3  months  apparently  protected  heifers 
temporarily  against  genital  infection,  but 
6  intramuscular  injections  over  a  period 
of  3  weeks  did  not.    This  does  not  appear 
to  be  a  practical  method  of  prevention. 

Epidemiology:     Bovine  trichomonosis 
is  a  venereal  disease  transmitted  at  coitus. 
T.  foetus  is  known  to  occur  in  cattle,  but 
whether  it  is  also  present  in  other  animals 
and  whether  it  may  be  transmitted  from 
them  to  cattle  by  a  non-venereal  route  re- 
main to  be  determined. 

With  the  introduction  of  the  technic  of 
preserving  bovine  semen  by  freezing  in 
the  presence  of  glycerol,  the  question  arose 
whether  T.  foetus  would  survive  in  frozen 
semen.    Several  investigators  have  studied 
the  problem,   and  have  found  that  the  pro- 
tozoa may  or  may  not  survive  freezing  in 
the  presence  of  glycerol,  depending  on  the 
conditions  (see  Levine,  Mizell  and  Houla- 
han,  1958  for  a  review  of  the  literature). 


THE  TRICHOMONADS 


87 


They  survive  in  some  media  but  not  in 
others.     Rapid  freezing  and  high  salt  con- 
centration are  deleterious  (Levine  and 
Marquardt,   1955;  Levine,  Mizell  and 
Houlahan,   1958).     The  stage  of  the  popu- 
lation growth  curve  is  important,  the  pro- 
tozoa being  much  more  sensitive  to  injury 
when  frozen  during  the  initial  and  logarith- 
mic phases  than  at  the  peak  of  the  curve 
and  for  some  time  thereafter  (Levine, 
McCaul  and  Mizell,   1959).     Temperature 
fluctuation  during  storage  is  deleterious 
(Fitzgerald  and  Levine,  1961). 

A  particularly  interesting  fact  is  that 
glycerol  appears  to  be  toxic  at  refrigerator 
temperatures  but  not  at  either  sub-freezing 
or  incubator  (37°  C)  temperatures  (Joyner, 
1954;  Joyner  and  Bennett,   1956;  Fitzgerald 
and  Levine,  1961).     It  may  be  possible  to 
develop  a  technic  for  freezing  semen  which 
would  be  sure  to  kill  the  protozoa,  but  at 
present  the  use  of  frozen  semen  from  in- 
fected bulls  cannot  be  recommended. 

Many  different  laboratory  animals 
can  be  infected  experimentally  in  various 
ways  with  T.  foetus  (see  Morgan,   1946  for 
review).     Leaving  aside  other  routes  of 
infection,  successful  vaginal  infections 
with  T.  foetus  have  been  established  in 
the  rabbit  by  Witte  (1933)  and  others,   in 
the  guinea  pig  by  Riedmuller  (1928)  and 
several  others,   in  the  golden  hamster  by 
Kradolfer  (1954)  and  Uhlenhuth  and 
Schoenherr  (1955),   in  the  dog  by  Trussell 
and  McNutt  (1941),  in  the  goat  by  Wittfogel 
(1935)  and  Hammond  and  Leidl  (1957),  in 
the  sheep  by  Wittfogel  (1935)  and  Andrews 
and  Rees  (1936),   and  in  the  pig  by  Ham- 
mond and  Leidl  (1957).     The  golden  ham- 
ster is  the  laboratory  animal  of  choice  for 
experimental  vaginal  infections.     Abortions 
were  produced  in  some  of  the  infected 
guinea  pigs.     Laboratory  mice  and  rats 
are  refractory  to  vaginal  infection. 

Kijst  (1936)  found  trichomonads  simi- 
lar to  T.  foetus  in  the  genital  tract  and 
aborted  fetuses  of  swine  and  horses  in 
Germany.     Petersen  (1937)  cultured  trich- 
omonads resembling  T.  foetus  from  the 
genital  tracts  of  13  mares  with  pyometra. 
He  also  found  an  infected  stallion  which 
had  transmitted  trichomonads  to  mares. 


Schoop  and  Oehlkers  (1939)  also  found 
trichomonads  in  the  genital  tract  of  horses. 
Schoop  and  Stolz  (1939)  found  trichomonads 
resembling  T.  foetus  in  the  uteri  of  4  out 
of  5  roe  deer  in  Germany.     The  infections 
were  associated  with  sterility,   and  the 
trichomonads  produced  vaginitis  in  guinea 
pigs.    Schoop  (1940)  suggested  that  if  the 
trichomonads  from  deer  were  T.  foetus, 
deer  might  be  a  source  of  infection  for 
cattle. 

The  relation  of  T.  foetus  to  the  trich- 
omonads of  swine  still  remains  to  be  elu- 
cidated.    The  pig  nasal  trichomonad, 
TritricJioiuoiias  suis,  greatly  resembles 
T.  foetus  morphologically  (Buttrey,   1956) 
and  in  metabolic  characteristics  (Doran, 
1957,   1959),   and  vaginal  infections  were 
readily  established  in  cattle  with  it  by 
Switzer  (1951)  and  Fitzgerald  et  at.  (1958). 
The  infection  reported  by  Switzer  lasted  3 
weeks  and  was  accompanied  by  a  mild 
catarrhal  vaginitis.     Those  reported  by 
Fitzgerald  et  al.  lasted  46  to  133  days, 
and  some  infections  appeared  to  interfere 
with  breeding  efficiency. 

Vaginal  infections  of  cattle  with  trich- 
omonads from  the  cecum  and  stomach  of 
swine  have  also  been  readily  established 
(Switzer,   1951;  Hammond  and  Leidl, 
1957a;  Fitzgerald  e/ aZ.  ,    1958),  and  the 
latter  two  authors  reported  that  bulls  be- 
came infected  by  breeding  infected  heifers 
and  then  transmitted  their  infections  to 
other  heifers.    The  bulls  later  recovered 
spontaneously  in  both  studies.    Kerr  (1958), 
too,  infected  heifers  intravaginally  with 
trichomonad  from  swine,  using  both  strains 
obtained  from  Hammond  and  a  strain  of 
T.  suis  isolated  in  England.     He  found  that 
the  vaginal  mucus  agglutination  test  of 
heifers  infected  with  porcine  trichomonads 
was  positive  with  T.  suis  and  Belfast  strain 
T.  foetus  antigens  but  not  with  Manley 
strain  T.  foetus  antigen. 

In  the  other  direction,   Fitzgerald  et  al. 
(1958)  produced  cecal  infections  with  T. 
foetus  in  young  pigs. 

Robertson  (1960)  made  a  serologic 
comparison  of  the  Belfast  and  Manley 
strains  of  T.  foetus  and  Strains  S2  and  414 


88 


THE  TRICHOMONADS 


of  T.  siiis,    isolated  by  Hammond  and 
Leidl  from  the  ceca  of  pigs  in  Germany 
and  Utah,   respectively.     Using  both  the 
tube  agglutination  and  precipitin  tests  and 
especially  the  gel  diffusion  precipitin  test, 
she  found  considerable  cross-reaction  be- 
tween the  4  strains.     All  had  the  same 
major  protein  antigens,  but  they  shared 
their  major  polysaccharide  antigens  only 
partially.     The  2  bovine  strains  were 
readily  distinguished  from  each  other, 
while  the  2  porcine  strains  were  very 
closely  related  but  not  identical.     The  por- 
cine strains  were  more  closely  related  to 
the  Belfast  than  to  the  Manley  strain  of  T. 
foetus.     Robertson  concluded  that  the 
serologic  distinctions  between  the  4  strains 
did  not  justify  separating  them  into  2  spe- 
cies, and  she  called  them  all  T.  foetus. 

Diagnosis:     Altho  the  mucus  aggluti- 
nation test  and  a  number  of  other  sero- 
logical procedures  have  been  suggested 
for  diagnosing  T.  foetus  infections,  the 
only  sure  method  is  to  demonstrate  the 
protozoa  microscopically  either  directly 
or  in  culture.    Diagnostic  procedures  have 
been  described  by  Hammond  and  Bartlett 
(1945),   Morgan  (1945),   Bartlett  (1949), 
Fitzgerald  et  at.   (1952)  and  Thorne,  Shupe 
and  Miner  (1955),  among  others. 

In  heavy  infections,  particularly  of 
females,  the  trichomonads  can  be  seen 
by  direct  examination  of  mucus  or  exudate 
from  the  vagina  or  uterus,  amniotic  or 
allantoic  fluid,  fetal  membranes,   placenta, 
fetus  stomach  contents,  oral  fluid  or  other 
fetal  tissues,  or,  in  bulls,  of  washings 
from  the  preputial  cavity  and  rarely  sem- 
inal fluid  or  semen.    If  trichomonads  can- 
not be  found  on  direct  microscopic  exam- 
ination, cultures  should  be  made  in 
CPLM,  BGPS  or  Diamond's  media  (see 
below). 

Samples  can  be  obtained  from  the 
vagina  by  washing  with  physiological  salt 
solution  in  a  bulbed  douche  syringe.    They 
can  be  obtained  from  the  preputial  cavity 
with  a  cotton  swab  or,  better,  by  washing 
with  physiological  salt  solution  in  a  bulbed 
pipette  or  syringe.    The  washings  should 
be  allowed  to  settle  for  1  to  3  hours  or 
centrifuged  before  examination. 


The  external  genitalia  should  be  cleaned 
thoroughly  before  the  samples  are  taken  in 
order  to  avoid  contamination  with  intestinal 
or  coprophilic  protozoa  which  might  be  mis- 
taken for  T.  foetus.    Among  these  are 
Tritrichomonas  enteris,  Monocercotnonas 
noninaniiuni,  Protriclwmonas  niminantiutn, 
Bodo  foetus,  B.  glissans,  Spiromonas 
atigusta,   Cercomonas  crassicauda,   Poly- 
tonia  uvella,  Monas  obliqua  and  Lenibus 
pusillus.    In  identifying  T.  foetus,  ii  must 
be  distinguished  from  these. 

Trichomonads  are  most  numerous  in 
the  vagina  2  to  3  weeks  after  infection. 
Their  numbers  fluctuate  in  bulls,  the  in- 
terval between  peaks  being  5  to  10  days 
(Hammond  et  at.  ,    1950). 

A  single  examination  is  not  sufficient 
to  warrant  a  negative  diagnosis.     A  cow  can 
be  considered  uninfected  if,  after  at  least  3 
negative  examinations,   she  has  2  normal 
estrus  periods  and  subsequently  conceives 
and  bears  a  normal  calf;  she  should  be  bred 
by  artificial  insemination  to  avoid  infecting 
the  bull.     A  bull  can  be  considered  negative 
if,  after  at  least  6  negative  examinations  at 
weekly  intervals,  he  is  bred  to  2  or  more 
virgin  heifers  and  they  remain  negative. 

Cultivation:      T.  foetus  can  be  readily 
cultivated  in  a  number  of  media.     Among 
them  are  CPLM  (cysteine-peptone-liver  ex- 
tract-maltose-serum) medium  (Johnson  and 
Trussell,   1943),  BGPS  (beef  extract-glu- 
cose-peptone-serum) medium  (Fitzgerald, 
Hammond  and  Shupe,   1954)  and  Diamond's 
(1957)  trypticase -yeast  extract-maltose- 
cysteine-serum  medium. 

T.  foetus  was  first  cultivated  in  tissue 
culture  by  Hogue  (1938).    It  was  cultivated 
in  the  chorio-allantoic  sac  of  chicken  em- 
bryos by  Nelson  (1938)  and  independently 
by  Levine,   Brandly  and  Graham  (1939)  and 
Hogue  (1939). 

Treatment:     Since  trichomonosis  is 
ordinarily  self-limiting  in  females,  treat- 
ment is  unnecessary.     No  satisfactory 
treatment  is  known  for  these  infections. 

Many  investigators  have  reported  on 
treatment  of  T.  foetus  infections  in  bulls, 


THE  TRICHOMONADS 


89 


including  Bartlett  (1948),   Bartlett,   Moist 
and  Spurrell  (1953),  Mahoney,   Christen- 
sen  and  Steere  (1954),  Thorne,  Shupe  and 
Miner  (1955),  Gabel  et  al.  (1956)  and 
Brodie  (1960).     Treatment  is  expensive, 
tedious  and  time-consuming;  unless  a  bull 
is  exceptionally  valuable,  it  is  best  to  sell 
it.     Bartlett  (1948)  found  that  the  German 
proprietary  preparation,   Bovoflavin-Salbe, 
cured  7  out  of  8  infected  bulls,   and  later 
workers  have  confirmed  its  effectiveness. 
This  salve,  which  contains  trypaflavine 
and  surfen  in  an  ointment  base,  is  rubbed 
into  the  penis  and  prepuce  following  pu- 
dendal nerve  block  or  relaxation  of  the  re- 
tractor penis  muscles  with  a  tranquilizer. 
Brodie  (1960)  injected  200  to  1000  mg 
promazine  hydrochloride  intravenously 
for  the  latter  purpose,  and  found  that  its 
ease  of  administration  and  quieting  effect 
made  it  preferable  to  nerve  block. 

Massage  is  continued  for  15  to  20 
minutes,  using  120  ml  of  the  ointment. 
In  addition,   30  ml  of  1%  acriflavine  solu- 
tion is  injected  into  the  urethra.     Repeated 
treatment  may  be  necessary.    If  the  epid- 
idymis or  testis  are  affected,  this  treat- 
ment will  be  ineffective. 

For  reasons  which  have  not  been  de- 
termined, American  bulls  are  much  more 
refractory  to  treatment  and  much  more 
difficult  to  infect  experimentally  than 
European  bulls.    Treatment  with  silver 
nitrate  or  by  injecting  10  1  of  3%  hydrogen 
peroxide  into  the  preputial  cavity  under 
pressure  with  the  apparatus  described  by 
Hess  (1949),  which  is  successful  in  Ger- 
many and  Switzerland  (Jondet  and  Guilhon, 
1957),  has  been  found  unsatisfactory  in 
the  United  States. 

Control:     Control  of  bovine  tricho- 
monosis  depends  on  proper  herd  manage- 
ment.   Most  infected  bulls  should  be 
slaughtered.    Infected  cows  should  be 
given  breeding  rest,  and  should  then  be 
bred  by  artificial  insemination  to  avoid 
infecting  clean  bulls. 

Proper  management  of  bulls  used  for 
artificial  insemination  is  especially  im- 
portant, since  they  may  spread  the  infec- 
tion widely.    They  should  be  examined  for 


T.  foetus  before  purchase,  and  the  herds 
from  which  they  originated  should  be  stud- 
ied at  the  same  time.    In  addition,  they 
should  be  examined  repeatedly  while  in  use 
(Bartlett,   Moist  and  Spurrell,  1953). 
Freezing  the  semen  in  the  presence  of  glyc- 
erol cannot  be  expected  to  kill  the  trich- 
omonads. 


TRITRICHOMONAS  SUIS 
(GRUBY  AND  DELAFOND,   1843) 

Synonym:     Trichomonas  suis  Gruby 
and  Delafond,   1843. 

Common  Name:     Large  pig  tricho- 
monad,   pig  nasal  trichomonad. 

Disease :     None . 

Hosts:     Pig. 

Location:     Nasal  passages,  stomach, 
cecum,  colon,  occasionally  small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Switzer  (1951)  found 
this  species  in  the  nasal  passages  of  80% 
of  swine  affected  with  atrophic  rhinitis  and 
in  only  3%  of  nonrhinitic  pigs  in  Iowa. 
Shuman  et  al.  (1953)  found  it  in  27%  of  36 
pigs  with  atrophic  rhinitis  and  in  17%  of  32 
unaffected  pigs  in  a  herd  near  Washington, 
D.  C.     Levine,  Marquardt  and  Beamer 
(1954)  found  it  in  91%  of  11  pigs  with  atro- 
phic rhinitis  and  in  39%  of  23  pigs  with 
normal  nasal  passages  in  Illinois.     Ham- 
mond,  Fitzgerald  and  Johnson  (1957)  found 
it  in  the  nasal  passages  of  56%  of  64  pigs 
from  Utah,  Nebraska  and  Idaho.    Hibler 
et  al.    (1960)  found  it  in  the  nasal  passages 
of  55%  of  100  pigs,  the  stomach  of  8%  of 
512,  the  cecum  of  43%  of  496  and  the  small 
intestine  of  3%  of  100  pigs  in  Utah. 

Morphology:     This  species  was  des- 
cribed in  detail  by  Hibler  et  al.  (1960), 
Marquardt  (1954)  and  Buttrey  (1956);  the 
latter  described  it  under  the  name  Tri- 
tricfiomonas  sp.  from  the  nasal  passages. 
T.  suis  is  characteristically  elongate  or 
spindle-shaped,  occasionally  piriform  or 
rotund,  9  to  16  by  2  to  6ju,,  with  a  mean  of 


90 


THE  TRICHOMONADS 


Fig.   8.       Trichomonads  of  swine.     A.    Trtlrichoiiionas  siiis.     X  7700.     B.    Trilriclioiii- 
onas  rotunda.     X  5100.     C.    Trichomonas  buUrexi.     X  5700.     (From  Hibler 
et  ai.,   1960) 


11.3  by  3.4^1.     Buttrey  described  a  cyto- 
stome,  but  Hibler  et  al.  did  not  see  one. 
The  3  anterior  flagella  are  about  equal  in 
length,   7  to  17 /i  long  with  a  mean  of  about 
12.6^L,   and  end  in  a  round  to  spatulate 
knob.     The  blepharoplast  is  composed  of 
several  granules.     The  undulating  mem- 
brane runs  the  full  length  of  the  body  and 
has  4  to  6  subequal  folds.     Its  marginal 


filament  continues  as  a  posterior  free  fla- 
gellum  5  to  11  ji  long.     An  accessory 
filament  is  present.     The  costa  runs  the 
full  length  of  the  body,   and  fine  subcostal 
granules  are  present.     The  axostyle  is  a 
hyaline  rod  0.  6  jj.  in  diameter  with  a  bulb- 
ous capitulum  1.  7  p.  in  diameter.    It  ex- 
tends 0.  6  to  1.  7fi  beyond  the  body  as  a 
cone-shaped  projection  narrowing  abruptly 


THE  TRICHOMONADS 


91 


to  a  short  tip.     There  is  a  chromatic  ring 
around  its  point  of  exit.     The  parabasal 
body  is  usually  a  single,   slender,  tube- 
like  structure  2  to  5jn  long.     The  nucleus 
is  oval  or  elongated,   2  to  5  by  1  to  3 /li  , 
with  a  large,   conspicuous  endosome  sur- 
rounded by  a  relatively  clear  halo. 

Pathogenesis:     The  discovery  of  this 
trichomonad  by  Switzer  (1951)  in  a  high 
percentage  of  cases  of  atrophic  rhinitis 
and  in  a  relatively  low  percentage  of  nor- 
mal pigs  raised  the  question  whether  it 
was  the  cause  of  the  condition.     Spindler, 
Shorb  and  Hill  (1953)  produced  the  disease 
in  young  pigs  with  nasal  washings  contain- 
ing trichomonads  from  pigs  with  atrophic 
rhinitis,  but  Switzer  (1951),   Levine, 
Marquardt  and  Beamer  (1954)  and  Fitz- 
gerald,  Hammond  and  Shupe  (1954a), 
among  others,  were  unable  to  do  so  with 
axenic  cultures  of  the  protozoon.    It  is 
now  generally  agreed  that  this  trichomonad 
is  not  pathogenic.     Several  other  agents, 
including  Pasteiirella  tnultocida  and  Myco- 
plasDia  hyorhinis,    have  been  incriminated 
as  causes  of  atrophic  rhinitis,  but  their 
roles  require  further  elucidation  (see 
Switzer,   1955  for  review). 

While  T.   suis  is  not  pathogenic  for 
pigs  in  its  natural  locations,   it  may  cause 
abortion  in  heifers  with  experimental  in- 
fections of  the  reproductive  tract  (see 
below). 

Cultivation:     This  trichomonad  can 
be  readily  cultivated  in  any  of  the  media 
used  for  T.  foetus.     In  mixed  cultures 
with  other  species  of  porcine  trichomon- 
ads, it  survives  while  the  others  die  out, 
so  that  it  sometimes  seems  as  tho  one 
species  has  taken  on  the  appearance  of 
another  (Hibler  et  al.  ,   1960).     Because  of 
this  fact,   cultures  of  pig  cecal  trichomonad 
heretofore  used  in  cross-transmission 
studies  have  most  probably  been  this  spe- 
cies. 

Switzer  (1959)  cultivated   T.  suis  from 
the  nasal  passages  in  pig  kidney,  nasal 
mucosa  and  lung  tissue  cultures. 

Remarks:     Uncertainty  has  existed 
for  many  years  regarding  which  of  the 


trichomonads  known  to  occur  in  swine  was 
T.  suis.     This  specific  name  was  origi- 
nally given  by  Gruby  and  Delafond  (1843) 
to  a  form  found  in  the  stomach.    Since 
that  time,  trichomonads  have  been  found  in 
the  cecum  and  nasal  passages,  but  it  was 
not  certain  what  their  relationship  was  to 
the  form  which  Gruby  and  Delafond  had 
named.     However,   Hibler  et  al.   (1960) 
found  that  the  species  described  above  is 
the  only  one  which  occurs  in  the  stomach 
and  that  it  also  occurs  in  the  nasal  pas- 
sages, cecum  and  small  intestine.     They 
found  the  other  2  trichomonad  species  of 
swine  only  in  the  cecum. 

The  relationship  between  T.  suis  and 
T.  foetus   requires  further  study.     Buttrey 
(1956)  and  Hibler  et  al.    (1960)  pointed  out 
their  great  morphological  similarity. 
Doran  (1957,   1959)  concluded  on  the  basis 
of  metabolic  studies  that  T.  suis  is  a 
highly  adapted  strain  of  T.  foetus.    The 
other  way  around  would  be  more  likely  in 
terms  of  evolution,  i.e.,    T.  foetus  may 
well  have  arisen  from  T.  suis  or  may  be 
an  adapted  strain  of  it. 

Fitzgerald  et  al.  (1958)  produced 
vaginal  infections  in  3  heifers  with  T.  suis 
from  the  pig  nose;  the  infections  lasted  46 
to  133  days.       They  also  produced  vaginal 
infections  in  2  heifers  with  T.  suis  from 
the  pig  cecum  which  lasted  33  and  84  days, 
respectively,  and  in  another  heifer  with 
T.  suis   from  the  pig  stomach  which  lasted 
88  days.    They  produced  abortion  in  a  4- 
month-pregnant  heifer  by  intrauterine 
inoculation  of    T.  suis  from  the  pig  cecum. 
In  addition,  a  bull  became  infected  by 
breeding  an  infected  heifer.     He  remained 
positive  for  4  months  and  transmitted  the 
infection  to  a  virgin  heifer  by  coitus. 
Hammond  and  Leidl  (1957a)  infected  the 
preputial  cavity  of  bulls  with  T.  suis  from 
the  pig  cecum  and  found  that  the  infections 
were  transmissible  by  coitus.    Kerr  (1958) 
produced  vaginal  infections  in  heifers  with 
Hammond's  strains  and  also  with  a  strain 
of  T.  suis  which  he  isolated  from  pigs  in 
England. 

Hammond  and  Leidl  (1957)  produced 
vaginal  infections  with   T.  suis  from  the 
pig  cecum  in  4  of  5  sows;  the  infections 


92 


THE  TRICHOMONADS 


lasted  3  to  42  days.     Fitzgerald  el  al. 
(1958)  produced  nasal  and  cecal  infections 
in  young  pigs  with  cultures  of  T.  suis  from 
the  pig  nose,  and  they  produced  nasal,  gas- 
tric and  cecal  infections  with  T.  sicis  from 
the  pig  stomach  and  from  the  pig  cecum. 

Shaw  and  Buttrey  (1958)  were  able  to 
infect  young  chickens  with  T.  siiis  from 
the  pig  nose  by  rectal  inoculation  but  not 
by  mouth. 

Kerr  (1958)  found  that  the  vaginal 
mucus  agglutination  test  of  heifers  infected 
with  T.  suis  was  positive  with  T.  suis  and 
Belfast  strain  T.  foetus  antigens  but  not 
with  Manley  strain  T.fuelus  antigen. 
Sanborn  (1955)  found  by  microagglutination 
tests  that  a  strain  of  T.  suis  from  the  pig 
nose  was  antigenically  different  from  a 
strain  of  T.  foetus  and  that  both  differed 
from  a  pig  cecal  trichomonad. 

As  mentioned  above  under  the  discus- 
sion of  T.  foetus,    Robertson  (1960)  found 
that  the  Belfast  and  Manley  strains  of  T. 
foetus  and  Strains  S2  and  414  of  T.  suis 
were  serologically  related  and  concluded 
that  the  differences  between  them  did  not 
justify  separating  them  into  2  species. 

Cattle  and  swine  are  often  raised  to- 
gether, and  the  broad  host  ranges  and  mor- 
phologic, metabolic  and  serologic  similar- 
ity between  T.  suis  and  T.  foetus  suggest 
that  they  may  have  had  a  common  origin  if 
they  are  not  indeed  the  same.     Robertson 
(1960)  believed  that  they  are  the  same  and 
called  them  all  T.  foetus,  but  the  correct 
name,  as  Hibler  et  al.   (1960)  pointed  out, 
would  be  T.  suis.     Even  so,   however,  it 
might  still  be  worth-while  to  retain  both 
names,  simply  as  a  matter  of  convenience. 


TRITRICHOMONAS  ROTUNDA 
HIBLER,   HAMMOND,   CASKEY, 
JOHNSON  AND   FITZGERALD,   1960 

Synonym :     Tritrichomonas  suis  pro 
parte. 

Common  Name:     Medium -sized  pig 
cecal  trichomonad. 


Disease:    None. 

Hosts:      Pig. 

Location:     Cecum,  colon. 

Geographic  Distribution:     This  spe- 
cies has  been  recognized  so  far  only  in 
North  America,  but  presumably  occurs 
thruout  the  world. 

Prevalence:     Hibler  et  al.  (1960) 
found  T.  rotunda  in  the  ceca  of  10.  5%  of 
496  pigs  in  Utah. 

Morphology:     This  species  was  des- 
cribed in  detail  by  Hibler  et  al.    (1960)  and 
by  Buttrey  (1956);  the  latter  referred  to  it 
as  "T.  s«/s -like."    T.  rotunda  is  typically 
broadly  piriform,  and  only  occasionally 
ovoid  or  ellipsoidal.    It  measures  7  to  11 
by  5  to  7  (i  with  a  mean  of  9.  0  by  5.  8  p. . 
Hibler  et  al.   saw  no  cytostome.     Cyto- 
plasmic inclusions  were  frequently  pres- 
ent.    The  3  anterior  flagella  are  about 
equal  in  length,  being  10  to  17/j.  long  with 
a  mean  of  14.9|j,,  and  terminate  in  a  knob 
or  spatulate  structure.     The  blepharoplast 
appears  to  consist  of  a  single  granule. 
The  undulating  membrane  is  relatively 
low.     It  and  the  costa  extend  about  1/2  to 
2/3  of  the  length  of  the  body  according  to 
Hibler  et  al.  (the  full  length  of  the  body, 
according  to  Buttrey),   and  its  undulation 
pattern  varies  from  smooth  to  tightly 
telescoped  or  coiled  waves  (with  3  to  5  in- 
distinct folds,  according  to  Buttrey).    The 
accessory  filament  impregnates  heavily 
with  silver.     The  posterior  free  flagellum 
is  generally  shorter  than  the  body.     The 
axostyle  is  a  narrow,   straight,  non-hya- 
line rod  with  a  crescent-  or  sickle-shaped 
capitulum.    It  extends  a  relatively  long 
distance  beyond  the  body  (0.  6  to  6.  3 /i  with 
a  mean  of  4.  3fi).     There  is  no  chromatic 
ring  at  its  point  of  exit  from  the  body. 
The  nucleus  is  practically  spherical,   2  to 
3  fi  in  diameter,  with  an  endosome  sur- 
rounded by  a  clear  halo.    The  parabasal 
body  measures  2.  3  to  3.  4  by  0.  4  to  1.3/1. 
It  is  composed  of  2  rami  which  form  a  V; 
each  ramus  has  a  parabasal  filament. 

Pathogenesis:     Non- pathogenic. 


THE  TRICHOMONADS 


93 


Cultivation:      T.   rotunda  grows  read- 
ily on  primary  culture  in  standard  tricho- 
monad  media,  but  dies  out  on  subculture 
and  can  no  longer  be  found  after  the  4th  or 
5th  subculture.     However,   it  can  be  main- 
tained indefinitely  in  a  cecal  extract- 
serum  medium  provided  that  Pseudonionas 
aeruginosa  is  present  (Hibler  et  al.  ,  1960). 


TRITRICHOMONAS  ENTERIS 
(CHRISTL,   1954)  nov.   comb. 

Synonym:      Trichomonas  enteris 
Christl,   1954. 

Hosts:     Ox,   zebu. 

Location:     Cecum,  colon. 

Geographic  Distribution:     Germany, 
India,   probably  worldwide. 

Prevalence:     Common  in  Bavaria, 
according  to  Christl  (1954). 

Morphology:     The  body  is  6  to  12jLi 
long  and  5  to  6fi  wide.     Three  anterior 
flagella  of  equal  length  arise  from  a  single 
blepharoplast.    The  flagellum  at  the  edge 
of  the  undulating  membrane  is  single, 
without  an  accessory  filament.     The  un- 
dulating membrane  extends  3/4  of  the  body 
length,  and  a  free  flagellum  extends  be- 


Fig.   9. 


Tritrichomonas  enteris.     X  1950. 
(From  Christl,   1954  in  Zeitschrift 
fiiy  ParasitenkiDide,    published  by 
Springer- Verlag). 


yond  the  undulating  membrane.     The  axo- 
style  is  straight,   slender,  bent  like  a 
spoon  around  nucleus,  and  extends  at  the 
most  1/4  of  the  body  length  beyond  the 
body.    Subcostal  granules  are  present. 


TRITRICHOMONAS   SP. 

Host:     Ox. 

Location:     Feces. 

Geographic  Distribution:     North 
America  (Maryland). 

Morphology:     Diamond  (1957)  culti- 
vated this  form  from  calf  feces.     He  did 
not  describe  it  except  to  say  that  it  resem- 
bled T.  batrachorum. 


TRITRICHOMONAS  EQUI 
(FANTHAM,   1921) 

Synonyms:      Trichomonas  equi. 

Host:     Horse. 

Location:     Cecum,  colon. 

Geographic  Distribution:     Presum- 
ably worldwide,  altho  it  has  been  reported 
specifically  only  from  South  Africa  and 
the  U.S.  (Iowa). 

Prevalence:     Fantham  (1921)  found 
T.  equi  very  rarely  and  in  very  small  num- 
bers in  horses  in  South  Africa.     Hsiung 
(1930)  found  it  on  several  occasions  in 
Iowa. 

Morphology:     According  to  Hsiung 
(1930),    T.  equi  measures  about  11  by  6fx 
and  seems  to  possess  3  anterior  flagella 
and  an  undulating  membrane.     The  axo- 
style  is  slender. 


TRITRICHOMONAS  FECALIS 
CLEVELAND,   1928 

This  species  was  isolated  once  from 
human  feces  by  Cleveland  (1928).  It  has 
3  very  long  flagella,  a  heavy  undulating 


94 


THE  TRICHOMONADS 


membrane,  a  long,  coarse  axostyle  and  a 
costa  with  2  rows  of  granules.     Like  T. 
hiitlreyi  and  the  form  cultured  from  a  calf 
by  Diamond  (1957),   it  resembles  T.  balra- 
churiDn.     The  relationship  between  the 
small  trichomonads  of  mammals  requires 
study. 


TRITRICHOMONAS  EBER  THI 
(MARTIN  AND   ROBERTSON,    1911) 
KOFOID,   1920 

Synonyms:     Trichomonas  eberthi. 

Hosts:     Chicken,  turkey.     Kotlan 
(1923)  reported   T.  eberthi  from  the  duck. 

Location:     Ceca. 

Geographic  Distribution:     Worldwide. 

Prevalence:  Common.  McDowell 
(1953)  found  T.  eberthi  in  35%  of  a  large 
number  of  chickens  in  Pennsylvania. 

Morphology:     The  body  is  carrot- 
shaped,   8  to  14  by  4  to  7|ii ,  with  vacuo- 


Fig. 


10.      Tritrichoinonas  eberllu.     X  4700. 
(From  Martin  and  Robertson,  1911) 


lated  cytoplasm,  and  3  anterior  flagella. 
The  undulating  membrane  is  prominent, 
extending  the  full  length  of  the  body.     The 
posterior  flagellum  extends  about  half  of 
the  body  length  beyond  the  undulating  mem- 
brane.    An  accessory  filament  is  present. 
The  cytostome  is  difficult  to  demonstrate. 
The  blepharoplast  is  composed  of  4  equi- 
distant granules,  but  tends  to  stain  as  a 
single  body.     Five  to  12  or  more  subcostal 
granules  are  present.     The  axostyle  is 
massive,   hyaline,  with  its  anterior  end 
broadened  to  form  a  capitulum  which  con- 
tains siderophilic,  argentophilic  granules. 
Other  endoaxostylar  granules  are  also 
present.     A  ring  of  chromatic  granules 
surrounds  the  axostyle  at  its  point  of  emer- 
gence from  the  body.     The  parabasal  body 
is  shaped  like  a  flattened  rod,  sometimes 
lumpy,  of  variable  length.     There  are  5 
chromosomes. 

Pathogenesis:     Non- pathogenic. 

Cultivation:  Diamond  (1957)  culti- 
vated T.  eberthi  axenically  for  the  first 
time  in  Diamond's  medium. 


OTHER  SPECIES  OF    TRITRICHOMONAS 

Tritrichomonas  muris  (Grassi,   1879) 
occurs  in  the  cecum,  colon  and  sometimes 
small  intestine  of  the  Norway  rat,  black 
rat,   house  mouse,  golden  hamster  and  a 
large  number  of  wild  rodents.     It  measures 
16  to  26  by  10  to  14^l. 

T.  minuta  (Wenrich,   1924)  occurs  in 
the  cecum  and  colon  of  the  Norway  rat, 
house  mouse  and  golden  hamster.    It  meas- 
ures 4  to  9  by  2  to  5  jli  . 

T.  wenyoni   (Wenrich,   1946)  occurs  in 
the  cecum  and  colon  of  the  Norway  rat, 
house  mouse,   golden  hamster,   rhesus 
monkey  and  Chacma  baboon.    It  measures 
4  to  16  by  2.5  to  6 fi. 

T.  caviae  (Davaine,  1875)  occurs  in 
the  cecum  and  colon  of  the  guinea  pig.    It 
measures  10  to  22  by  6  to  11  ji . 

Tritrichomonas  sp.  Nie,   1950  occurs 
in  the  cecum  of  the  guinea  pig.    It  meas- 
ures 6  to  13  by  4.  5  to  6.  5 |i. 


THE  TRICHOMONADS 


95 


Tritrichomonas  criceti  (Wantland, 
1956  emend. )  nov.   comb.   (syn.  ,  Tri- 
chomonas cricetus  Wantland,  1956)occurs  in 
the  cecum  and  colon  of  the  golden  hamster. 
It  measures  12  to  25  by  5  to  10 /i. 


Genus  TRICHOMONAS  Donne,  1837 

Members  of  this  genus  have  4  anter- 
ior flagella. 


TRICHOMONAS   TEN  AX 
(MULLER,   1773)DOBELL,    1939 

Synonyms:  Cercaria  tenax,  Tetra- 
tyiclio)iioiias  buccaUs,  Trichomonas  biic- 
calis,    Trichomonas  elongata. 

Disease:     None. 

Hosts:     Man,  monkeys  [Macaco 
nmlatta.   Papio  sphinx). 

Location:     Mouth,  especially  between 
gums  and  teeth. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common.     T.   tenax  has 
been  found  in  4%  to  53%  of  persons  exam- 
ined in  different  surveys  (Wenrich,   1947). 

Morphology:     The  morphology  of  T. 
tenax  has  been  studied  by  Wenrich  (1947) 
and  Honigberg  and  Lee  (1959).     The  latter 
remarked  on  the  close  morphological  re- 
semblance of  this  species  to  T.  gallinae. 
The  body  is  ellipsoidal,  ovoid  or  piriform, 
4  to  16  (i  long  and  2  to  15(a  wide.    Different 
strains  differ  in  size;  the  smallest  of  5 
strains  studied  by  Honigberg  and  Lee  (1959) 
averaged  6.  0  by  4.  3  /i  and  the  largest  8.  4 
X  6.  0|U .     The  4  anterior  flagella  are  7  to 
15fx  long.     They  originate  in  a  basal  gran- 
ule complex  anterior  to  the  nucleus  and 
terminate  in  little  knobs  or  rods.     The  un- 
dulating membrane  is  shorter  than  the  body; 
it  ranged  from  40  to  100%  and  averaged 
from  69  to  82%  of  the  body  length  in  the  5 
strains  studied  by  Honigberg  and  Lee  (1959). 
An  accessory  filament  is  present.     There 
is  no  free  posterior  flagellum.     The  costa 
is  slender  and  accompanied  by  a  group  of 


large  paracostal  granules.     The  parabasal 
apparatus  consists  of  a  typically  rod- 
shaped  body  and  a  long  filament  extending 
posteriorly  from  it.     The  axostyle  is  slen- 
der and  extends  a  considerable  distance 
beyond  the  body.     There  is  no  periaxostylar 
ring  at  its  point  of  exit  nor  is  it  accompa- 
nied by  paraxostylar  granules.     The  capi- 
tulum  of  the  axostyle  is  somewhat  enlarged 
and  spatulate.     The  pelta  is  of  medium 
width.    Wenrich  (1947)  said  that  a  cyto- 
stome  was  present,  but  Honigberg  and  Lee 
(1959)  found  no  evidence  of  one.     Honigberg 
and  Lee  (1959)  described  the  division  proc- 
ess in  detail. 

Pathogenesis:     None. 

Cultivation:     Honigberg  and  Lee  (1959) 
cultivated   T.  tenax  in  Balamuth's  yolk  in- 
fusion medium.    Diamond  (1960)  cultivated 
it  axenically  in  a  complex  medium  contain- 
ing chick  embryo  extract. 

Remarks:     Hinshaw  (1928)  infected  a 
dog  which  had  gingivitis  with  T.   tenax. 


TRICHOMONAS  EQUIBUCCALIS 
SIMITCH,   1939 


Disease:     None . 

Hosts:     Horse,  donkey. 

Location:     Mouth,   around  gums  and 
teeth^ 

Geographic  Distribution:     This  species 
has  apparently  been  reported  only  from 
Jugoslavia. 

Prevalence:     Simitch  (1939)  found  T. 
eqidbuccalis  by  culture  in  7  out  of  22 
horses  and  2  out  of  4  donkeys  in  Jugoslavia. 

Morphology:     The  body  is  piriform  or 
ovoid,   7  to  10 /i  long.    It  has  a  single  ble- 
pharoplast  and  4  anterior  flagella  10  to 
15;i  long.     The  undulating  membrane  is 
relatively  short,   rarely  reaching  the  pos- 
terior end.     There  is  no  free  posterior 
flagellum.     The  costa  is  slender  and  not 
always  visible.    The  axostyle  is  apparently 
slender  and  extends  beyond  the  body. 


96 


THE  TRICHOMONADS 


Pathogenesis:     Non- pathogenic. 

Remarks:     Simitch  (1939)  transmitted 
T.  eqiiibiiccalis  readily  from  the  horse  to 
the  donkey  and  vice  versa,  but  was  unable 
to  infect  cattle,  sheep  and  goats  with  it. 


length  of  the  body.     The  free  posterior  fla- 
gellum  is  about  half  as  long  as  the  body. 
The  costa  is  apparently  slender.     The  axo- 
style  is  thread-like,  staining  black  with 
hematoxylin,   and  extends  a  considerable 
distance  beyond  the  body.    Subcostal  gran- 
ules are  absent. 


TRICHOMONAS  FELISTOMAE 
HEGNER  AND   RATCLIFFE,   1927 

Hosts:     Cat. 

Location:     Mouth. 

Geographic  Distribution:     United 
States. 

Prevalence:     Hegner  and  Ratcliffe 
(1927)  found  this  species  in  2  out  of  28 
cats  examined  in  Baltimore,  Md. 

Morphology:     The  body  is  piriform, 
6  to  1 1  by  3  to  4  (I  with  a  mean  of  8  by  3  ji , 
and  has  4  anterior  flagella  longer  than 
body.     The  costa  is  illustrated  as  promi- 
nent.    The  undulating  membrane  extends 
most  of  the  body  length.     There  is  a  free 
posterior  flagellum.     The  axostyle  extends 
a  considerable  distance  beyond  the  body. 

Pathogenesis:     Non-pathogenic. 


TRICHOMONAS  CANISTOMAE 
HEGNER  AND  RATCLIFFE,    1927 


Pathogenesis:     Non- pathogenic. 

Remarks:     An  old  dog  with  advanced 
gingivitis  was  infected  with   T.  leiiax  by 
Hinshaw  (1928);  the  infection  was  still 
present  14^  months  later.    Simitch  and 
Kostitch  (1938)  were  unable  to  infect  hu- 
mans with  T.   caiiistoDiae  or  to  infect  dogs 
with  T.  tenax.     The  morphological  differ- 
ence described  between  the  two  species 
indicates  that  they  are  different.     T.  can- 
istomae  and  T.  felistomae,    however,  may 
well  be  the  same;  further  study  is  needed 
to  determine  this. 


TRICHOMONAS  VAGINALIS 
DONNE,   1836 

Hosts:    Man. 

The  golden  hamster  can  be  infected 
intravaginally  (Uhlenhuth  and  Schoenherr, 
1955).     Mice  can  be  infected  subcutaneously 
(Honigberg,   1959). 

Location:     Vagina,  prostate  gland, 
urethra. 


Hosts:     Dog. 

Location:     Mouth. 

Geographic  Distribution: 
States,  Europe. 


United 


Prevalence:     Hegner  and  Ratcliffe 
(1927a),  found  this  species  in  22  out  of  23 
dogs  examined  in  Baltimore,  Md. 

Morphology:     The  following  descrip- 
tion is  based  on  Hegner  and  Ratcliffe 
(1927a).     The  body  is  piriform,   7  to  12|j, 
long  and  3  to  4/i  wide.     Four  anterior 
flagella  about  as  long  as  the  body  arise  in 
pairs  from  a  large  blepharoplast.     The 
undulating  membrane  extends  almost  the 


Geographic  Distribution:     Worldwide. 

Prevalence:      T.  vaginalis  has  been 
reported  in  2%  to  as  high  as  80  to  90%  of 
women  and  in  1  to  47%  of  men  in  various 
surveys  (Wenrich,   1947;  Kucera,   1957; 
Burch,  Rees  and  Reardon,  1959). 

Morphology:     The  body  is  piriform, 
7  to  23  by  5  to  12  ;i,   and  has  4  anterior 
flagella  about  as  long  as  the  body.     The  un- 
dulating membrane  has  3  or  4  waves  and 
extends  a  little  more  than  half  the  body 
length.     There  is  no  free  posterior  flagel- 
lum.    An  accessory  filament  is  present. 
The  costa  is  very  narrow.     The  parabasal 
body  is  long,   cylindrical,   and  has  a  para- 
basal filament  extending  posteriorly  from 


THE  TRICHOMONADS 


97 


Fig.  11.      Trichonionads  of  man.     1.    Trichomonas 
vaginalis.     2.    Trichomonas  lenax. 
3.    Pentatrichomonas  hominis.     X  2500. 
(From  Wenrich,   1947) 

it.     Paracostal  and  extra- axostylar  gran- 
ules are  numerous;  other  siderophil  gran- 
ules are  scattered  in  the  cytoplasm.    Four 
chromosomes  are  present.    The  axostyle 
is  rather  slender.     The  cytostome  is  in- 
conspicuous. 

Pathogenesis:      T.  vaginalis  infec- 
tions are  often  asymptomatic  in  womena 
and  are  usually  so  in  the  male.    Tricho- 
monad  vaginitis  is  characterized  by  leu- 
korrhea  and  vaginal  and  vulvar  pruritis. 
T.  vaginalis  may  occasionally  cause  pur- 
ulent urethritis  and  prostato-vesiculitis 
in  the  male.    Concomitant  bacteria  and 
yeasts  may  exacerbate  the  symptoms  and 
lesions. 

Epidemiology:      T.  vaginalis  infec- 
tions are  essentially  venereal  in  origin, 
the  organism  being  transmitted  during 
sexual  intercourse.    In  exceptional  cases, 
infants  have  been  infected  from  their 
mothers.     Transmission  thru  contamina- 
ted towels,  underwear  or  toilet  seats  is 
extremely  rare. 

Diagnosis:      T.  vaginalis  infections 
can  be  readily  identified  by  microscopic 


examination  of  vaginal  secretions  or  scrap- 
ings, sedimented  urine  or  prostate  secre- 
tions obtained  by  massaging  the  prostate 
gland. 

Cultivation:      T.  vaginalis  can  be 
readily  cultivated  in  any  of  the  media  used 
for  trichonionads,  such  as  CPLM  medium. 

Treatment:     A  number  of  preparations 
are  used  in  treating  trichomonad  vaginitis. 
Among  them  are  suppositories  containing 
chiniofon,  diodoquin,  vioform,   carbarsone 
or  oxytetracycline.     Lactic  acid  douches 
are  often  used  to  make  the  vaginal  pH  acid 
and  provide  conditions  unsuitable  for  the 
protozoa.     Infections  in  the  male  may  be 
treated  by  introducing  oxytetracycline 
ointment  into  the  urethra  or  irrigating 
with  a  sulfonamide  or  antibiotic.    To  pre- 
vent reinfection,  both  husband  and  wife 
should  be  treated. 

Remarks:     Trussell  (1947)  has  writ- 
ten a  definitive  monograph  on  this  species. 


TRICHOMONAS  PAVLOVI 
NOM.  NOV. 

Synonym:      Trichomonas  bovis  Pavlov 
and  Dimitrov,   1957,  non  Trichomonas 
bovis  Riedmiiller,   1930. 

Host:     Ox. 

Location:      Large  intestine. 

Geographic  Distribution:    Bulgaria. 

Morphology:     This  species  was  des- 
cribed by  Pavlov  and  Dimitrov  (1957).    The 
trophozoites  are  piriform  and  usually  meas- 
ure 11  to  12  by  6  to  7  (jL .     The  4  anterior 
flagella  are  about  the  same  length  as  the 
body.    The  undulating  membrane  is  well  de- 
veloped, with  2  to  4  waves,  and  extends  al- 
most to  the  posterior  end  of  the  body.     A 
posterior  free  flagellum,  an  accessory  fil- 
ament and  a  costa  are  present.    The  nucleus 
is  round-oval  or  oval.    The  axostyle  is  rel- 
atively weak  and  slender,  broadening  to 
form  a  capitulum  at  the  anterior  end,   and 
extending  about  1/4  of  its  length  from  the 
posterior  end  of  the  body.    There  are  many 
food  vacuoles  in  the  cytoplasm. 


98 


THE  TRICHOMONADS 


PathoRenesis:      Pavlov  and  Dimitrov 
(1957)  found  this  species  in  the  feces  of 
calves  5  days  to  4  months  old,   all  of  which 
had  diarrhea.    They  thought  that  the  pro- 
tozoa were  the  cause  of  the  diarrhea,  bas- 
ing their  opinion  on  their  inability  to  find 
another  cause  and  on  the  fact  that  the 
trichomonads  disappeared  from  the  feces 
when  the  diarrhea  ceased.    Needless  to 
say,  this  is  not  sufficient  justification  for 
their  view. 

Remarks:      Further  study  is  necessary 
to  be  sure  whether  this  species  is  valid. 
Pending  such  a  study,   it  is  considered  best 
to  retain  it. 

Pavlov  and  Dimitrov  (1957)  named 
this  species  Trichomonas  bovis.     This 
name  is  a  homonym  of  Tyichomonas  bovis 
Riedmiiller,   1930,  which  is  in  turn  a  syn- 
onym of  TritrichoHiuiias  foetus  (Ried- 
miiller,  1928).     Hence  I  am  renaming  it 
Trichomonas  pavlovi  nom.  nov. 


r.  bultreyi  is  ovoid  or  ellipsoidal,  4 
to  7  by  2  to  5 (i  with  a  mean  of  about  5.  9 
by  3.4p..     Cytoplasmic  inclusions  are 
frequently  present,  but  Hibler  et  al.  saw 
no  cytostome.     There  are  4  or  3  anterior 
flagella  which  vary  in  length  from  a  short 
stub  to  more  than  twice  the  length  of  the 
body  and  end  in  a  knob  or  spatulate  struc- 
ture.    The  undulating  membrane  runs  the 
full  length  of  the  body  and  has  3  to  5  un- 
dulations.    The  accessory  filament  is 
prominent  and  the  costa  relatively  deli- 
cate.    A  posterior  free  flagellum  is  pres- 
ent.    The  axostyle  is  relatively  narrow, 
with  a  spatulate  capitulum,  and  protrudes 
3  to  6|i  beyond  the  body.     There  is  no 
chromatic  ring  at  its  point  of  exit.     A 
pelta  is  present  anteriorly.     The  nucleus 
is  frequently  ovoid  but  varies  consider- 
ably in  shape;  it  measures  2  to  3  by  1  to 
2 /J,  and  has  a  small  endosome.    The  para- 
basal body  is  a  disc  0.  3  to  1. 1  /i  in  diam- 
eter. 

Pathogenesis:     Non- pathogenic. 


TRICHOMONAS  BUTTREYI 
fflBLER,   HAMMOND,   CASKEY, 
JOHNSON  AND   FITZGERALD,    1960 

Common  Name:     Small  pig  cecal 
trichomonad. 

Disease:     None. 

Host:      Pig. 

Location:     Cecum,  colon,   rarely 
small  intestine. 

Geographic  Distribution:     This  spe- 
cies has  been  recognized  so  far  only  in 
North  America,  but  presumably  occurs 
thruout  the  world. 

Prevalence:     Hibler  et  al.  (1960) 
found  T.  biittreyi   in  the  ceca  of  25.  4%  of 
496  pigs  and  in  the  small  intestine  of  1% 
of  100  pigs  in  Utah. 

Morphology:     This  species  was  des- 
cribed in  detail  by  Hibler  et  al.  (1960)  and 
by  Buttrey  (1956);  the  latter  referred  to  it 
as  a  Paralricho>nonas-like  form  resem- 
bling P.    (or  Trichomonas)  batrachorum. 


Cultivation:     According  to  Hibler 
et  al.  ,    T.   biittreyi  grows  readily  on  pri- 
mary culture  in  standard  trichomonad 
media,  but  dies  out  on  subculture;  they 
maintained  it  indefinitely  in  a  cecal  ex- 
tract-serum medium  provided  Pseiido- 
monas  aeruginosa  was  present.    Diamond 
(1957)  however,  established  it  in  axenic 
culture. 

Remarks:     Doran  (1958)  studied  the 
metabolism  of  this  species,  using  Strain 
PC-287.    It  could  not  oxidize  Krebs  cycle 
intermediates,  but  produced  carbon  diox- 
ide and  other  gas  not  absorbed  by  KOH 
anaerobically.    It  resembled   T.  siiis 
more  than  other  trichomonads,  but  dif- 
fered in  carbohydrate  utilization  and  in 
having  a  generally  lower  respiratory 
rate. 


TRICHOMONAS  GALLINAE 
(RIVOLTA,   1878)   STABLER,   1938 

Synonyms:     Cercomonas  gallinae, 
Cercomonas  hepaticiim.    Trichomonas 
columbae,    Trichomonas  diversa,   Tri- 
chomonas halli. 


THE  TRICHOMONA  DS 


99 


Disease:     Avian  trichomonosis,  upper 
digestive  tract  trichomonosis. 

Hosts:     The  domestic  pigeon  is  the 
primary  host  of  T.  gallinae.  but  it  also 
occurs  in  a  large  number  of  other  birds, 
including  hawks  and  falcons  which  feed  on 
pigeons.    Its  natural  hosts  besides  the 
pigeon  include  the  mourning  dove  {Zen- 
aidura  macroura),  Indian  dove  (  Turtiir 
siiratensis),  wood  pigeon  [Columba  pa- 
lumbiis),  band-tailed  pigeon  (C.  fasciata), 
ring  dove  {Streptopelia  risoria),  white- 
winged  dove  {Zenaida  asiatica),  turkey, 
chicken,   Cooper's  hawk  {Accipiter  cooperi), 
golden  eagle  {Aquila  chrysaetos),  duck 
hawk  [Falco  peregrinus  anatiini),  Java 
sparrow  {Miinia  oryzivora),  zebra  finch 
and  orange-cheeked  waxbill. 

A  number  of  other  birds  have  been 
experimentally  infected.     They  include  the 
bobwhite  quail,   canary,   English  sparrow 
(Levine,   Boley  and  Hester,   1941),  barn 
swallow,  goldfinch  and  song  sparrow 
(Stabler,   1953),  and  Tovi  parakeet  and 
Verraux's  dove  (Callender  and  Simmons, 
1937).     Parenteral  infections  have  also 
been  produced  experimentally  in  mammals 
--by  Bos  (1934)  in  mice  and  guinea  pigs, 
by  Wagner  and  Hees  (1935),  Wittfogel 
(1935),   Miessner  and  Hansen  (1936), 
Schnitzer,   Kelly  and  Leiwant  (1950)  and 
Honigberg  (1959)  in  mice,  and  by  Rakoff 
(1934)  in  rats  and  kittens. 

Prevalence:      T.  gallinae  is  extremely 
common  in  domestic  pigeons,  in  which  it 
often  causes  serious  losses.     It  is  fairly 
common  in  the  turkey;  the  U.S.  Dept.  of 
Agriculture  (1954)  estimated  that  it  causes 
an  annual  loss  of   $47,000  in  these  birds. 
It  is  rare  in  chickens.    It  is  common  in 
mourning  doves,  and  may  cause  serious 
losses  among  them  (Stabler  and  Herman, 
1951).     According  to  Stabler  (1954),  it  was 
common  in  trained  hawks  during  the  hey- 
day of  falconry;  they  became  infected  be- 
cause they  were  fed  largely  on  pigeons. 
Stabler  and  Herman  (1951)  and  Stabler 
(1954)  give  further  information  on  incidence 
in  domestic  and  wild  birds. 

Morphology:    The  following  description 
is  based  on  Stabler  (1941,  1954).     The  body 


Fig.  12.      Trichomonas  gallinae 
(From  Stabler,   1947) 


X  3400. 


is  roughly  piriform,  6  to  19  by  2  to  9  |j,. 
Four  anterior  flagella  8  to  ISfi  long  arise 
from  the  blepharoplast.     The  axostyle  is 
narrow  and  protrudes  a  short  distance 
from  the  body.     There  is  no  chromatic 
ring  around  its  point  of  emergence.     The 
parabasal  body  is  sausage-shaped,  about 
4|i  long,  with  a  parabasal  filament.     The 
costa  runs  2/3  to  3/4  of  the  body  length. 
The  undulating  membrane  does  not  reach 
the  posterior  end  of  the  body.     An  acces- 
sory filament  is  present.     A  free  trailing 
flagelium  is  absent.     A  cytostome  is 
present.     There  are  6  chromosomes. 

Pathogenesis:     In  the  pigeon,  tricho- 
monosis is  essentially  a  disease  of  young 
birds;  80  to  90?o  of  the  adults  are  infected 
but  show  no  signs  of  disease.     The  sever- 
ity of  the  disease  varies  from  a  mild  con- 
dition to  a  rapidly  fatal  one  with  death  4  to 
18  days  after  infection.     This  is  due  in 
part  to  differences  in  virulence  of  different 
strains  of  the  trichomonad  (Stabler,   1948). 
Severely  affected  birds  lose  weight,  stand 
huddled  with  ruffled  feathers,  and  may  fall 
over  when  forced  to  move.     A  greenish 
fluid  containing  large  numbers  of  tricho- 
monads  may  be  found  in  the  mouth. 

Lesions  are  found  in  the  mouth,   si- 
nuses, orbital  region,   pharynx,   esophagus, 
crop  and  even  the  proventriculus.     They  do 
not  involve  the  digestive  tract  beyond  the 


:oo 


THE  TRICHOMONADS 


proventriculus.    They  often  occur  in  the 
liver  and  to  a  lesser  extent  in  other  organs, 
including  the  lungs,  air  sacs,   heart,   pan- 
creas, and  more  rarely  the  spleen,  kid- 
neys, trachea,  bone  marrow,  navel  re- 
gion, etc. 

The  early  lesions  in  the  mouth  are 
small,  yellowish,  circumscribed  areas  in 
the  mucosa.     They  increase  in  number  and 
become  progressively  larger,  finally  de- 
veloping into  very  large,  caseous  masses 
which  may  invade  the  roof  of  the  mouth  and 
sinuses  and  may  even  extend  thru  the  base 
of  the  skull  to  the  brain.     The  early  lesions 
in  the  pharynx,  esophagus  and  crop  are 
small,  whitish  to  yellowish  caseous  nod- 
ules which  also  grow.     They  may  remain 
circumscribed  and  separate,  or  they  may 
form  thick,  caseous,  necrotic  masses 
which  may  occlude  the  lumen.     The  cir- 
cumscribed, disc-shaped  lesions  are 
often  described  as  "yellow  buttons".    Those 
in  the  esophagus  and  crop  may  have  central, 
spur-like  projections.     A  large  amount  of 
fluid  may  accumulate  in  the  crop.     The  le- 
sions in  the  liver,  lungs  and  other  organs 
are  solid,  yellowish,  caseous  nodules 
ranging  up  to  a  centimeter  or  more  in  di- 
ameter. 

In  the  turkey  and  chicken,  the  lesions 
occur  mostly  in  the  crop,  esophagus  and 
pharynx,  and  are  relatively  uncommon  in 
the  mouth  and  liver.    The  lesions  in  the 
mourning  dove  are  similar  to  those  in  the 
pigeon. 

Immunology:     As  mentioned  above, 
different  strains  of  T.  gallinae  differ 
greatly  in  virulence  (Stabler,   1948;  Flor- 
ent,   1938;  Gloor,   1943).     Previous  infec- 
tion bestows  more  or  less  immunity;  adult 
pigeons  which  have  survived  infection  as 
squabs  are  symptomless  carriers.    Infec- 
tion with  a  relatively  harmless  strain  pro- 
duces immunity  against  virulent  strains 
(Stabler,   1948a,   1951).    According  to 
Florent  (1938),  pigeons  are  particularly 
susceptible  at  the  time  of  weaning  and  of 
the  first  molt.    Stabler  (1953)  found  that 
immunity  did  not  increase  with  age  of  un- 
infected birds.     Certain  breeds  or  strains 
of  birds  may  be  more  sensitive  than  others. 
Miessner  and  Hansen  (1936)  felt  that  roller 


and  tumbler  pigeons  were  such,  and  Levine 
and  Brandly  (1940)  were  able  to  infect 
chicks  from  one  source  readily  while  chicks 
from  other  sources  were  very  resistant. 

Epidemiology:     In  pigeons  and  mourn- 
ing doves,  trichomonosis  is  transmitted 
from  the  adults  to  the  squabs  in  the  pigeon 
milk  which  is  produced  in  the  crop.     The 
squabs  are  infected  within  minutes  after 
hatching.     Hawks  and  other  wild  raptors 
become  infected  by  eating  infected  birds. 
Turkeys  and  chickens  are  infected  thru 
contaminated  drinking  water.     Feral  pig- 
eons and  other  columbid  birds  are  the  or- 
iginal source  of  infection.    The  trichom- 
onads  pass  into  the  water  from  the  mouths 
of  infected  birds,  and  not  from  the  drop- 
pings (Stabler,  1954).     T.  gallinae  has  no 
cysts  and  is  very  sensitive  to  drying,  so 
direct  contamination  is  necessary. 

Diagnosis:     Upper  digestive  tract 
trichomonosis  is  readily  diagnosed  by  ob- 
servation of  the  lesions  together  with  dem- 
onstration of  the  protozoa.    It  must  be 
differentiated  from  other  conditions  which 
may  cause  more  or  less  similar  lesions, 
including  fowl  pox,  vitamin  A  deficiency 
and  moniliosis  (thrush). 

Cultivation:      T.  gallinae  can  be  cul- 
tivated readily  in  any  of  the  customary 
trichomonad  media.    Diamond  (1954)  com- 
pared 28  culture  media  for  it  and  (1957) 
introduced  a  trypticase-yeast  extract- 
maltose-cysteine-serum  medium  for  it  and 
other  trichomonads. 

Treatment:     A  number  of  workers 
have  recommended  the  use  of  copper  sul- 
fate for  20  days  or  more  in  the  drinking 
water  to  eliminate  T.  gallinae  (see  Stab- 
ler,  1954)  but  this  is  not  particularly  sat- 
isfactory.   The  optimal  concentration  for 
non-breeding  pigeons  is  1-1000  and  that  for 
breeding  pigeons  with  squabs  is  1-3000 
according  to  Jaquette  (1948),  but  it  tends 
to  make  the  birds  sick,  and  Jaquette  felt 
that  all  the  treated  birds  may  have  suffered 
liver  damage.     Turkeys  will  not  drink 
1-2000  copper  sulfate. 

The  best  treatment  for  T.  gallinae  is 
2-amino-5-nitrothiazole  (enheptin). 


THE  TRICHOMONADS 


101 


Stabler  and  Mellentin  (1953)  recommended 
7  daily  doses  of  28  mg/kg  for  homing  pi- 
geons and  45  mg/kg  for  commercial  birds. 
This  treatment  cures  both  acute  cases  and 
carriers.    Stabler,  Schmittner  and  Harman 
(1958)  used  6.  3  g  enheptin  soluble  per  gal- 
lon of  drinking  water  for  7  to  14  days  in 
non-breeding  pigeons.     The  birds  consumed 
9  to  27  mg  of  the  drug  per  day--operation 
of  the  peck  order  may  have  cut  down  water 
consumption  by  some  birds--and  53  of  61 
infected  birds  were  freed  of  their  infec- 
tions.    Zwart  (1959)  obtained  promising 
results  with  0. 125%  enheptin  in  the  drink- 
ing water  of  a  Dutch  aviary  where  the  in- 
fection had  been  found  in  zebra  finches 
and  an  orange-checked  waxbill. 

Control:     Control  of  trichomonosis 
in  pigeons  depends  upon  elimination  of  the 
infection  from  the  adults  by  drug  treat- 
ment.    Prevention  in  turkeys  and  chickens 
is  based  upon  preventing  wild  pigeons  and 
doves  from  drinking  from  their  watering 
places. 


TRICHOMONAS  GALLINARUM 
MARTIN  AND   ROBERTSON,    1911 

Synonym :     Trichomonas  pullorum. 

Disease :     None . 

Hosts:     Chicken,  turkey,  guinea  fowl, 
and  possibly  other  gallinaceous  birds  such 
as  the  quail,   pheasant  and  chukar  par- 
tridge.   Diamond  (1957)  found  a  T.  gal- 
linarum -like  form  in  the  Canada  goose 
{Branta  canadensis). 

Location:     Ceca,   sometimes  liver. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common.    McDowell 
(1953)  found  T.  gallinarum  in  over  60%of 
a  large  number  of  chickens  in  Pennsyl- 
vania. 

Morphology:     The  body  is  piriform, 
7  to  15  by  3  to  9  jj, ,  with  4  anterior  fla- 
gella  and  a  posterior  flagellum  which  runs 
along  the  undulating  membrane  and  ex- 
tends beyond  it.    An  accessory  filament  is 


present.     The  axostyle  is  long,   pointed 
and  slender,  without  a  chromatic  ring  at 
its  point  of  emergence.     The  cytostome  is 
prominent.    Supracostal  granules  but  no 
subcostal  or  endoaxostylar  granules  are 
present.     The  pelta  is  elaborate,  ending 
abruptly  with  a  short  ventral  extension 
more  or  less  free  from  the  ventral  edge 
of  the  axostyle,  according  to  McDowell 
(1953);  Marquardt  (1954),   however,  did 
not  find  a  pelta  in  his  cultures  of  a  strain 
from  a  turkey.    The  shape  of  the  para- 
basal body  is  highly  variable,  but  it  is 
usually  a  ring  of  variously  spaced  gran- 
ules plus  1  or  2  fibrils  or  rami.    The 
chromosome  number  is  apparently  5.     A 
rather  uniform  perinuclear  cloud  of  ar- 
gentophilic  granules  is  usually  present 
(McDowell,   1953). 

The  form  originally  described  by 
Martin  and  Robertson  (1911)  had  4  anterior 
flagella.     Allen  (1940)  described  a  trichom- 
onad  from  the  ceca  and  liver  of  chickens 
and  turkeys  which  she  considered  to  be  this 
species  but  which  had  5  anterior  flagella. 
Walker  (1948),  too,   illustrated  the  trichom- 
onad  he  isolated  from  turkey  livers  with  5 
anterior  flagella.    Further  study  is  needed 
to  determine  the  relationship  of  this  form 
to  T.  gallinarum.     McDowell  (1953)  in- 
sisted on  the  fact  that  the  usual  number  of 
anterior  flagella  is  4,   rarely  3  and  in  even 
rarer  cases  5.     He  studied  1000  slides  from 
a  large  number  of  chickens.     Marquardt 
(1954),  too,  found  only  4  anterior  flagella 
in  a  culture  strain  from  a  turkey. 

Pathogenesis:     Allen  (1936,   1941), 
Olsen  and  Allen  (1942)  and  Walker  (1948) 
isolated  a  trichomonad  from  turkey  liver 
lesions  resembling  those  of  histomonosis 
and  considered  that  the  trichomonad    had 
caused  them.     The  disease  they  described 
resembled  histomonosis,  with  cecal  and 
liver  lesions,  pale  yellow,  cecal  diarrhea, 
inappetance,   loss  of  weight,  and  a  mor- 
tality of  0  to  44%.     The  cecal  lesions  were 
said  to  be  the  same  as  those  of  histomo- 
nosis, but  the  liver  lesions  were  said  to 
be  smaller,  to  have  irregular  outlines  and 
to  be  raised  or  level  with  the  liver  surface 
instead  of  depressed  below  it.    Wichmann 
and  Bankowski  (1956)  described  a  similar 
condition  in  chukar  partridges.    However, 


102 


THE  TRICHOMONADS 


the  mere  presence  of  an  organism  in  a 
lesion  is  no  proof  that  it  caused  the  lesion. 
There  is  no  satisfactory  proof  that   T.  gal- 
liiutru))!  by  itself  is  capable  of  causing 
disease,   and  the  weight  of  evidence  is 
against  it.    Delappe  (1957)  infected  chick- 
ens and  turkeys  experimentally  with  a 
strain  of  T.  galliiianiDi  isolated  from 
liver  lesions  of  a  turkey  with  histomonosis, 
but  was  unable  to  produce  either  symptoms 
or  lesions.     The  possibility  has  still  not 
been  completely  eliminated,   however,  that 
a  Penlalrichomonas  may  exist  which  is 
pathogenic  (see  below). 

Epidemiology:     Birds  become  infected 
by  ingestion  of  trichomonads  in  contamin- 
ated water  or  feed.     McLoughlin  (1957) 
found  that  one-week-old  turkey  poults  were 
more  susceptible  than  9-week-old  ones. 
He  also  found  that  T.  gcilliiiarnni  survived 
for  24  hours  but  not  for  48  hours  in  cecal 
droppings  at  37"  C,  and  for  120  hours  at 
6'  C. 

Cultivation:      T.  gnlUnanuv  is  readily 
cultivated  in  the  usual  trichomonad  media. 


TRICHOMONAS  ANATIS 
(KOTLAN,   1923) 

Synonym :     Tetratrichomonas  anatis. 

Host:     Domestic  duck. 

Location:      Posterior  part  of  intes- 
tinal tract. 

Geographic  Distribution:     Europe 
(Hungary). 

Morphology:     The  body  is  broadly 
beet-shaped,   13  to  27  by  8  to  18  fx,  with  4 
anterior  flagella,  an  undulating  membrane 
extending  most  of  the  length  of  the  body,   a 
free  trailing  flagellum,  a  costa  and  a 
fibrillar  axostyle. 


TRICHOMONAS  ANSERI 
HEG^fER,   1929 

Hosts:     Domestic  goose,  baby  chick 
(experimental). 


Morphology:     The  body  is  oval,  6  to 
9  by  3.  5  to  6.  5(i  with  a  mean  of  8  by  5jx . 
Four  anterior  flagella  appear  to  arise  in 
pairs  from  2  blepharoplasts.     The  undulat- 
ing membrane  extends  almost  the  full 
length  of  the  body.     A  free  trailing  flagel- 
lum and  a  costa  are  present.     The  axo- 
style is  broad  and  hyaline,  extending  a 
considerable  distance  beyond  the  body. 
There  is  no  chromatic  ring  at  its  point  of 
emergence  from  the  body.     The  nucleus  is 
characteristic,  completely  filled  with  min- 
ute chromatin  granules  and  also  with  a 
single  large  karyosome  usually  at  one 
side.     The  cytostome  is  prominent.     Many 
specimens  have  large  bacteria  in  the  en- 
doplasm. 

Location:     Ceca. 

Geographic  Distribution:     United 
States  (Maryland). 

Prevalence:     Unknown. 

Remarks:      Hegner  (1929)  found  a  very 
few  of  these  trichomonads  in  cecal  material 
from  a  goose.     He  inoculated  3-day-old 
chicks  with  the  material /»(?r  os  and  per 
rectimi  and  the  above  description  is  based 
on  material  from  the  chicks. 


OTHER  SPECIES  OF    TRICHOMONAS 

Trichomonas  macacovaginae  Hegner 
and  Ratcliffe,   1927  occurs  in  the  vagina 
of  the  rhesus  monkey.    It  measures  8  to  16 
by  3  to  6 ^  and  has  a  free  posterior  flagel- 
lum, a  feature  which  differentiates  it  from 
T.   vaginalis. 

T.  w^/cro//  Wenrich  and  Saxe,   1950 
occurs  in  the  cecum  of  the  Norway  rat, 
house  mouse,  goldfen  hamster,  vole  {Mi- 
croliis  peniisylL'a)iici<s)  and  other  wild  ro- 
dents.   It  is  4  to  9  ji  long.    Simitch,   Petro- 
vitch  and  Lepech  (1954)  transmitted  it  from 
the  white  mouse  to  the  laboratory  rat,  guin- 
ea pig,  ground  squirrel  (Citellus  citelliis), 
dog  and  cat,  but  were  unable  to  infect  the 
chicken  and  a  human  volunteer.    Wenrich 
and  Saxe  (1950)  transmitted  if  from  the  vole 
to  the  laboratory  rat,   hamster  and  guinea 
pig,  but  could  not  infect  a  human  volunteer. 


THE  TRICHOMONADS 


103 


Genus  PENTATRICHOMONAS 
Mesnil,    1914 

Members  of  this  genus  have  5  anter- 
ior flagella. 

PENTATRICHOMONAS  HOMINIS 
(DAVAINE,    1860) 

Synonyms:      Cercomonas  hominis, 
Monocercomonas  hominis,    Trichomonas 
intestinalis.    Trichomonas  confusa,  Pen- 
tatrichomonas  ardin  delteili,    Tricliom- 
onas  felis,    Trichomonas  parva,  Pentatri- 
chomonas  canis  auri. 

Disease :     None . 

Hosts:     Man,   gibbon,  chimpanzee, 
orang-utan,  rhesus  monkey,   pigtailed 
monkey  {Macaca  nemestrina),  brown 
capuchin  (Cebus  fatuellus),  weeping 
capuchin  (C.  apella),  white-throated 
capuchin  (C.  capucinus),  black  spider 
monkey  {Ateles  ater),  white-crested  titi 
monkey  (Callicebus  amictus),  Guinea 
baboon  {Papio  papio),  Humboldt's  woolly 
monkey  {Lagothrix  lagotricha),  vervet 
monkey  {Cercopithecus  pygerythrus),  dog, 
cat,  rat,  mouse,  golden  hamster.    The 
primates  were  listed  by  Flick  (1954). 

Kessel  (1928)  infected  kittens  with 
trichomonads  from  man,  the  monkey  and 
rat.    Simitch  (1932,   1932a,   1933)  trans- 
mitted P.   hominis  from  the  rat  to  the  cat, 
dog  and  man.    Saxe  (1954)  transmitted  it 
from  the  golden  hamster  to  the  laboratory 
rat  and  from  the  rat  to  the  hamster. 
Simitch,   Petrovitch  and  Lepech  (1954)  in- 
fected the  white  mouse,  laboratory  rat, 
guinea  pig,  ground  squirrel  (Citellus  ci- 
telliis ),  dog,   cat  and  chicken  with  P.  ho- 
minis from  man. 

Location:     Cecum,  colon. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:  The  following  descrip- 
tion is  based  primarily  on  Wenrich  (1947) 
and  Kirby  (1945).    The  body  is  usually 


piriform,  8  to  20  by  3  to  14 /i.     Five  an- 
terior flagella  are  ordinarily  present,  al- 
tho  some  organisms  may  have  4  and  a  few 
3.     Flick  (1954)  found  in  a  study  of  more 
than  13,000  individuals  from  13  P.  hominis 
strains  from  13  hosts  that  77%  had  5  fla- 
gella,  17%  had  4,   5%  had  3,  and  1%  had  6 
or  more  anterior  flagella.     Four  of  the 
anterior  flagella  are  grouped  together  and 
the  fifth  is  separate  and  directed  poster- 
iorly.    A  sixth  flagellum  runs  along  the 
undulating  membrane  and  extends  beyond 
it  as  a  free  trailing  flagellum.     The  undu- 
lating membrane  extends  the  full  length 
of  the  body.     An  accessory  filament,  a 
costa  and  paracostal  granules  are  present. 
The  axostyle  is  hyaline,  thick,  with  a 
sharply  pointed  tip  but  without  a  chromatic 
ring  at  its  point  of  exit.     The  parabasal 
body  is  small  and  ellipsoidal.     The  bleph- 
aroplast  is  composed  of  2  granules.    The 
pelta  is  crescent-shaped,  prolonged  dor- 
sally  in  a  filament  which  passes  posteriorly 
in  the  cytoplasm  dorsal  to  the  nucleus.     A 
cytostome  is  present.    There  are  5  or  6 
chromosomes. 

Pathogenesis:     Non- pathogenic. 

Cultivation:      P.  hominis  is  readily 
cultivable  in  the  usual  trichomonad  media. 


PENT  A  TRICHOMONAS 
SP.   ALLEN,   1936 

Synonym:     Pentatrichomonas  gal- 
linarum  auct. 

Hosts:     Chicken,  turkey,  guinea  fowl. 

Location:     Ceca,  liver. 

Geographic  Distribution:     Probably 
worldwide. 

Prevalence:     Unknown. 

Morphology:     Pentatricliomonas  sp. 
resembles  T.  gallinarum  morphologically 
except  that  it  has  5  anterior  flagella.     Four 
of  these  are  of  equal  length  and  the  fifth  is 
about  half  as  long  as  the  others.    The  body 
is  usually  spherical,  sometimes  more  or 
less  pear-shaped,  fixed  specimens 


104 


THE  TRICHOMONADS 


measuring  3  to  7  by  5  to  8  |i  with  a  mean 
of  5  by  7  ji.     The  undulating  membrane  ex- 
tends the  full  length  of  the  body,  with  a 
free  flagellum  at  its  end.    A  costa  is  pres- 
ent (Allen,   1940  called  it  a  parabasal  body). 
A  row  of  paracostal  granules  runs  between 
the  costa  and  the  undulating  membrane. 
The  axostyle  is  slender,   projecting  from 
the  posterior  end,  but  not  discernible  in 
rounded-up  specimens.     A  cytostome  is 
present.    The  blepharoplast  is  composed 
of  a  group  of  small  granules. 

Pathogenesis:     As  mentioned  in  the 
discussion  of  Trichomonas  galli)iaru))i , 
Allen  and  others  isolated  this  form  from 
turkey  liver  lesions  resembling  those  of 
histomonosis  and  attributed  the  disease  to 
it.     However,  post  hoc  reasoning  is  not 
enough,  and  there  is  as  yet  no  acceptable 
proof  that  this  trichomonad  is  pathogenic. 

Remarks:     Allen  (1936)  first  assigned 
this  species  to  the  genus  Pentatrichomonas 
without  naming  it.    She  later  (1940)  des- 
cribed it  as  a  five-flagellate   "Trichom- 
onas galli>iarum  Martin  and  Robertson, 
1911".     Later  authors  such  as  Morgan  and 
Hawkins  (1952)  called  it  Pentatrichomonas 
gallinaritm.    The  species  described  by 
Martin  and  Robertson  has  4  anterior  fla- 
gella,   as  does  the  form  described  by 
McDowell  (1953).     Further  study  is  needed 
to  determine  the  relationship  between  the 
two  forms. 

Genus  DfTR/CHOMONAS 
Cutler,  1919 

Similar  to  Trichomonas,  but  with  2 
anterior  flagella. 


DITRICIiOMONAS  OVIS 
ROBERTSON,   1932 

Host:     Sheep. 

Location:      "Gut. " 

Geographic  Distribution:     England. 

Prevalence:     Robertson  (1932)  found 
this  species  in  1  out  of  86  sheep  in  a  Lon- 
don abattoir. 


Morphology:     The  protozoa  were  des- 
cribed from  cultures.     The  body  is  slightly 
ovoid  or  nearly  spherical,   3  to  14  by  3  to 
10  ji,  with  2  anterior  flagella,  one  12  to 
16.  5/i  and  the  other  7.  5  to  10.  5^  long. 
The  undulating  membrane  is  poorly  devel- 
oped but  extends  the  whole  length  of  the 
body.    A  free  flagellum  was  described  as 
present,  but  was  absent  in  7  out  of  9  draw- 
ings.    A  costa  is  present.     The  axostyle 
extends  beyond  the  body.    Three  blepharo- 
plasts  and  another  granule  described  as  a 
parabasal  body  are  present. 

Pathogenesis:     Non- pathogenic. 

Cultivation:     Robertson  (1932)  culti- 
vated D.  ovis  in  Tanabe's  medium  with  or 
without  added  rice  starch. 

Remarks:     Robertson's  paper  was 
apparently  overlooked  by  Grasse,   Reich- 
enow  and  others  who  discussed  the  validity 
of  the  genus  Ditricho)nonas.    Robertson 
insisted  that  there  are  only  2  anterior  fla- 
gella except  when  the  protozoa  are  divid- 
ing.    No  one  else  appears  to  have  studied 
the  intestinal  trichomonads  of  sheep  care- 
fully, altho  they  are  more  common  in  the 
United  States  than  Robertson  found  them 
to  be  in  England.     Whether  they  are  the 
same  species  remains  to  be  determined. 


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In  this  chapter  is  discussed  a  miscel- 
lany of  flagellates,  most  of  which  are 
found  in  the  digestive  tract.     Only  a  few 
are  pathogenic,  the  great  majority  being 
commensal.    Some  are  not  parasitic  at  all 
but  are  coprophilic  or  have  been  found  as 
contaminants  in  washings  from  the  sheath 
of  bulls;  these  are  mentioned  because  they 
must  be  differentiated  from  parasitic 
forms.     A  few  other  species  are  free-liv- 
ing toxin-producers. 


TOXIC   MARINE   PHYTOFLAGELLATES 

The  great  majority  of  phytoflagellates 
are  free-living  and  holophytic.    Some  of 
them  produce  powerful  toxins  which  may 
kill  fish  or  even  man. 

Gonyaulax  catanella  is  a  marine  dino- 
flagellate,  found  particularly  off  the  coast 
of  California,  which  causes  a  fatal  dis- 
ease of  man  known  as  mussel  poisoning. 
Its  toxin  is  one  of  the  most  powerful  known. 
Under  conditions  still  largely  unknown,  the 
protozoa  multiply  tremendously,  forming 
a  luminescent  "bloom"  in  the  ocean.     Mus- 
sels and  certain  other  shellfish  feeding  on 
plankton  are  not  harmed  by  the  toxin  but 
accumulate  it  in  their  internal  organs. 
People  who  eat  these  mussels  may  then  be 
killed  by  the  toxin. 

The  blooming  of  other  dinoflagellates, 
including  several  species  of  Gymnodinium, 
cause  the  "red  tide"  or  "red  water"  which 
sometimes  kills  huge  numbers  of  fish,  de- 
positing them  in  rotting  windrows  on  the 
shore.     This  condition  is  particularly 
common  off  the  coast  of  Florida,  where  it 
is  associated  with  the  discharge  of  phos- 
phates into  the  ocean,  but  it  also  occurs 
off  the  Texas  coast  and  elsewhere  (Hutner 
and  McLaughlin,   1958). 

A  third  marine  phytoflagellate,  the 
chrysomonad  Prymnesium  parvmn,  has 
killed  fish  en  masse  in  brackish  fish  ponds 
in  Israel,  and  has  formed  blooms  accom- 
panying fish  kills  in  Holland  and  Denmark 
(McLaughlin,   1958). 


,RY 


Chapter  6 


OTHER 
HAGBUATES 


-  107 


108 


OTHER   FLAGELLATES 


A  few  phytoflagellates  are  coprophilic 
and  may  be  mistaken  for  true  parasites, 
and  still  fewer  are  parasitic.    These  will 
be  discussed  below. 


PARASITIC   FLAGELLATES 

The  parasitic  mode  of  life  has  arisen 
independently  a  number  of  times  in  this 
group.     Free-living  species  or  genera  in 
distantly  related  or  unrelated  families 
have  found  suitable  living  conditions  in 
various  hosts.     Many  of  these  were  pre- 
viously inhabitants  of  stagnant  water. 
The  fact  that  so  few  of  them  are  pathogenic 
effectively  refutes  the  notion  that  para- 
sites tend  to  be  pathogenic  in  their  first 
association  with  a  new  host  and  that  later 
on  the  host  and  parasite  adjust  to  each 
other,  the  latter  becoming  less  pathogenic 
and  eventually  commensal. 


FAMILY   MONOCERCOMONADIDAE 

This  family,   like  the  Trichomonadidae, 
belongs  to  the  order  Trichomonadorida. 
Its  members  have  either  a  free  or  adherent 
trailing  flagellum,  but  lack  the  undulating 
membrane  and  costa  found  in  the  Trichom- 
onadidae.    Four  genera,   Monocercomonas , 
Hexamastix,   Protrichomonas  and  Cliilo- 
mitus,    occur  in  the  intestinal  tracts  of 
domestic  animals. 


Genus  MONOCERCOMONAS   Grassi,   1879 

In  this  genus  the  body  is  piriform, 
with  a  rounded  anterior  end.     There  is  a 
pelta.     The  cytostome  and  nucleus  are 
anterior.    There  are  3  anterior  flagella 
and  a  trailing  one.    The  axostyle  projects 
beyond  the  posterior  end  of  the  body. 
Travis  (1932)  showed  that  Trichomastix 
Blochmann,   1884  and  Entrichomastix 
Kofoid  and  Swezy,   1915  are  synonyms  of 
Monocercomonas .     Morgan  (1944)  gave  a 
checklist  of  species  of  the  genus;  it  in- 
cluded 20  species,  of  which  4  were  from 
mammals,   4  from  birds,   2  from  reptiles, 
1  from  amphibia,  2  from  fish  and  7  from 
insects  and  other  arthropods.    Others 
have  been  described  since. 


Fig.  13.     Monocercomonas. 
(Original) 


X  2800. 


Monocercomonas  ruminantium 
(Braune,   1914)  nov.   comb,  occurs  in  the 
rumen  of  cattle.     In  addition,  Morgan  and 
Noland  (1943)  found  what  was  probably  the 
same  organism  in  material  from  the  sheath 
of  bulls. 

The  body  is  about  S/i  long,  with  3  an- 
terior flagella  about  8)i  long  and  a  trailing 
flagellum  a  little  longer.     The  axostyle  is 
curved  and  does  not  extend  beyond  the 
body,  altho  the  posterior  end  is  pointed. 
A  line  of  granules  runs  beside  the  convex 
side  of  the  axostyle.     This  species  is  non- 
pathogenic, but  must  be  distinguished  from 
Tri trichomonas  foetus. 

Synonyms  of  this  species  are  Tri- 
chomonas noiiiiiaiitiiiiii  Braune,   1914; 
Tricercomitus  ni)>iiiiaiitiii»i   (Braune,  1914) 
Christl,   1954;  and  Tritrichomonas  rumin- 
antium (Braune,   1914);  but  not  Tricho- 
))iastix  ruminantium  Braune,   1914.    Altho 
Braune  (1914)  assigned  this  species  to  the 
genus  Trichonioiias  and  succeeding  work- 
ers have  followed  him  in  this  or  at  the 
most  have  changed  the  generic  name  of 
Tritrichonionas.    Christl  (1954)  pointed  out 
that  the  absence  of  an  undulating  membrane 
made  this  assignment  incorrect.     Christl 
transferred  it  to  the  genus  Tricercomitus, 
but  it  belongs  more  properly  to  the  genus 
Monocercomonas . 


OTHER   FLAGELLATES 


109 


Monocercomouas  cuniculi  (Tanabe, 
1926)  occurs  in  the  cecum  of  the  domestic 
rabbit.    It  is  piriform,   5  to  14  ji  long. 
Its  axostyle  is  slender,   hyaline,  and  pro- 
jects from  the  body. 

Monocerco))io)ias  gaUinaritm  (Martin 
and  Robertson,   1911)  Morgan  and  Hawkins, 
1948  is  said  to  occur  in  the  ceca  of  the 
chicken.    Kotlan  (1923)  reported  it  from  a 
single  domestic  duck.     Its  body  is  piri- 
form,  5  to  8  by  3  to  4  fj, .     There  is  some 
question  whether  this  is  a  valid  species. 
It  has  been  reported  by  Martin  and  Robert- 
son (1911)  in  England,  Kotlan  (1923)  in 
Hungary,  and  Morgan  and  Hawkins  (1952) 
in  Wisconsin,  but  McDowell  (1953)  failed 
to  find  it  in  1000  slides  from  a  large  num- 
ber of  chickens  in  Pennsylvania.    McDowell 
believed,  along  with  Minchin  (1917), 
Wenyon  (1926),  Doflein  and  Reichenow 
(1929)  and  others,  that  it  is  simply  a  de- 
generate Trichomonas  eberthi. 


Genus  HEXAMASHX 
Alexeieff,    1912 

In  this  genus  the  body  is  piriform, 
with  a  rounded  anterior  end.     The  cyto- 
stome  and  nucleus  are  anterior.     There 
are  6  flagella,  of  which  1  trails.     (Ac- 
cording to  Nie,   1950,  the  number  of  an- 
terior flagella  varies  in  this  genus  from 
2  to  6.  )    A  pelta  is  present,  the  axostyle 
is  conspicuous,  and  the  parabasal  body 
prominent.     Members  of  this  genus  have 
been  found  in  mammals,  amphibia  and 
insects.     Hexamastix  caviae  Nie,   1950 
and  H.  robustus  Nie,   1950  occur  in  the 
guinea  pig  cecum,  and  H.   muris  (Wen- 
rich,   1924)  in  the  cecum  of  the  Norway 
rat,  golden  hamster  and  other  rodents. 


Genus  CHILOMITUS 
Da  Fonseca,  1915 

The  body  is  elongate,  with  a  convex 
aboral  surface.    The  pellicle  is  well  de- 
veloped.    The  cuplike  cytostome  is  near 
the  anterior  end.     Four  flagella  emerge 
thru  it  from  a  bilobed  blepharoplast.    The 
nucleus  and  parabasal  body  are  just  below 
the  cytostome.    An  axostyle  is  present  but 


may  be  rudimentary.     Cysts  may  occur. 
Only  a  few  species  have  been  described, 
all  in  mammals.     Cliilo»nlus  caviae  da 
Fonseca,   1915  and  C.   coiiexits  Me,  1950 
occur  in  the  guinea  pig  cecum. 


Genus  PROTRICHOMONAS 
Alexeieff,   1912 

The  body  is  piriform  or  beet- shaped, 
with  3  anterior  flagella  of  equal  length 
arising  from  an  anterior  blepharoplast, 
an  anterior  nucleus  and  an  axostyle.    Three 
species  have  been  named,  from  birds, 
mammals  and  a  fish. 

Protrichomonas  niniinantiiiDi  (Braune, 
1914)  nov.   comb,  was  originally  assigned 
by  Braune  (1914)  to  the  genus  TrichoDias- 
tix  (now  Monocerconionas),  but  the  absence 
of  a  trailing  flagellum  makes  this  assign- 
ment incorrect.     Its  description  agrees 
with  that  of  Protricho))wiias,  altho  it  must 
be  said  that  this  genus  is  badly  in  need  of 
redescription.     P.   ru)ninaiitium  occurs  in 
the  rumen  of  cattle  and  sheep.    It  is  about 
8/i  long.    Its  nucleus  is  often  surrounded 
by  a  clear  zone.    No  cytostome  was  seen. 

Protrichomonas  anatis  Kotlan,   1923 
has  been  described  from  the  large  intes- 
tine of  the  domestic  duck  and  other  water 
birds.     It  is  10  to  13|Li  long  and  4  to  6ju 
wide.     Two  distinct  fibrillae  arise  from 
the  anterior  blepharoplast  and  pass  back 
thru  the  body,   separating  to  pass  around 
the  nucleus  and  finally  passing  out  of  the 
body  as  a  pointed  axostyle.     The  nucleus 
is  often  triangular. 


ORDER   POLYMASTIGORIDA 

Members  of  this  group  have  2  to  about 
12  flagella  and  1,   2  or  several  nuclei. 
They  lack  a  costa,  axostyle  (except  in  some 
Hexamitidae  and  Polymastigidae)  and  para- 
basal body. 


FAMILY   TETRAMITIDAE 

In  this  family  there  is  a  single  nucleus 
and  4  flagella,  1  or  2  of  which  may  be 


no 


OTHER  FLAGELLATES 


trailing.  Eiiferonionas  is  parasitic  in 
domestic  and  laboratory  animals,  and 
Tetramitus  is  coprophilic. 


Genus  TETRAMITUS  Perty,  1852 

In  this  genus  the  life  cycle  involves 
flagellate  and  amoeboid  forms;  there  are 
also  uninucleate  cysts.     In  the  flagellate 
stage  the  body  is  ellipsoidal  or  piriform, 
with  a  large,  trough-shaped  cytostome  at 
the  anterior  end,  a  vesicular  nucleus  with 
a  large  endosome,   4  anterior  flagella, 
and  a  contractile  vacuole.     Nutrition  is 
holozoic. 

Tetramitus  rostratus  Perty,   1852 
(syn. ,  Copromastix  prowazeki  Aragao, 
1916)  is  found  in  stagnant  water  and  is 
also  coprophilic.     It  has  been  found  in 
human  and  rat  feces.    The  flagellate  stage 
is  14  to  18 /i  long  and  7  to  IOjll  wide.     The 
amoeboid  stage  is  14  to  48  jm  long  and 
usually  has  a  single  lobose  pseudopod. 
The  cysts  are  spherical,  thin-walled,  and 
6  to  18  fi  in  diameter.     The  life  cycle  of 
this  species  has  been  studied  by  Bunting 
(1926),   Bunting  and  Wenrich  (1929)  and 
Hollande  (1942). 


Genus  ENTEROMONAS 
Da  Fonseca,   1915 

The  body  is  spherical  or  piriform  and 
is  plastic.     It  has  3  short  anterior  flagella, 
1  of  which  may  be  difficult  to  see,  and  a 
4th,  long  flagellum  which  runs  along  the 
flattened  body  surface  and  extends  free  for 
a  short  distance  at  the  posterior  end  of 
the  body.    A  strand-like  funis  arises  from 
the  blepharoplast  and  extends  posteriorly 
along  the  body  surface;  it  stains  faintly 
with  iron  hematoxylin  and  strongly  with 
protargol.     The  nucleus  is  anterior,  vesi- 
cular, with  or  without  an  endosome.    There 
is  no  cytostome.    The  cysts  are  ovoid,  and 
are  tetranucleate  when  mature.    A  syno- 
nym of  this  genus  is  TricercoDionas  Wen- 
yon  and  O'Connor,   1917.     This  genus  has 
been  reported  from  a  number  of  mammals. 

E>itero»io)ias  hu»iinis  da  Fonseca, 
1915  (synonyms,  Octomitus  hominis, 


Tricercomonaa  intestinalis,  Diplucerco- 
monas  soudanensis,  Enteromonas  beiiga- 
lensis)  occurs  in  the  cecum  of  man,  maca- 
ques (Macaca  »iHlatta,  M.   sinica,  M. 
nemestrina)  the  golden  hamster  and  prob- 
ably other  animals  thruout  the  world. 
Wantland  (1955)  reported  it  in  l%of  500 
golden  hamsters  in  the  United  States. 
Saxe  (1954)  transmitted  it  from  the  golden 
hamster  to  the  laboratory  rat.    Dobell 
(1935)  was  unable  to  infect  himself  with  a 
culture  of  £.   liominis  from  the  macaque, 
M.   sinica,  but  believed  that  future  work 
would  show  that  the  human  and  macaque 
forms  are  the  same  species.    Simitch 
et  at.  (1959)  reported  failure  to  transmit 
E.  hominis  to  2  young  pigs. 

The  trophozoite  is  oval,  4  to  10  by  3 
to  6|:x,  and  has  many  food  vacuoles  con- 
taining bacteria.     The  cysts  are  ovoid  or 
ellipsoidal;  they  are  usually  binucleate 
but  have  4  nuclei  when  mature.    E.  hominis 
is  readily  cultivated  on  the  usual  media 
for  enteric  protozoa  such  as  LES  medium; 
cysts  form  in  the  cultures.    It  is  non-path- 
ogenic. 


Fig.  14.      A.    Enteromonas.     B.    Retorta- 
iiionas.     X  2800.     (Original) 


Enteromonas  suis  (Knowles  and  Das 
Gupta,  1929)  Dobell,  1935  (syn. ,   Tricer- 
comonas  suis)  was  described  from  the 
cecum  of  a  pig  in  India.    It  was  cultivated 
easily  in  Dobell  and  Laidlaw's  medium. 
It  is  shaped  like  a  broad,  ovate  leaf  with 
a  more  or  less  rounded  anterior  end  and 
a  pointed  posterior  end,  and  is  9  to  20ju 
long  and  6  to  14/i  wide.    It  moves  slug- 
gishly more  or  less  directly  forward  and 
does  not  rotate  like  Trichomonas.     The 
three  anterior  flagella  are  8  to  ISji  long 


OTHER   FLAGELLATES 


111 


With  a  mean  of  14fi,  and  the  posterior 
flagellum  is  9  to  26|j,  long  with  a  mean  of 
17jLt.    Simitch  et  al.  (1959)  found  it  in 
2%  of  1800  pigs  in  Yugoslavia. 


FAMILY   RETORTAMONADIDAE 

Members  of  this  family  have  2  or  4 
flagella,  of  which  1  is  trailing,  a  single 
nucleus  and  a  cytostome  with  supporting 
fibrils.     There  are  2  genera  of  veterinary 
interest,  Retortamonas  and  Chilomastix . 


Genus   RET0RTAA10NAS 
Grassi,  1879 

The  body  is  usually  piriform  or  fusi- 
form, drawn  out  posteriorly,  and  plastic. 
There  is  a  large  cytostome  near  the  an- 
terior end  containing  in  its  margin  a 
cytostomal  fibril  which  extends  across 
the  anterior  end  and  posteriorly  along 
each  side.    An  anterior  flagellum  and  a 
posteriorly  directed,  trailing  flagellum 
emerge  from  the  cytostomal  groove.     The 
cysts  are  piriform  or  ovoid,   have  1  or  2 
nuclei,  and  retain  the  cytostomal  fibril. 
A  synonym  of  this  genus  is  Embadonionas 
Mackinnon,   1911.    Species  occur  in  var- 
ious insects,  amphibia,  reptiles  and  mam- 
mals.    (Ansari,   1955,   1956). 

Retortamonas  intestinalis  (Wenyon 
and  O'Connor,   1917)  Wenrich,   1932  (syns.  , 
Embadomonas  intestinalis,    Waskia  intes- 
tinalis) occurs  in  the  cecum  of  man  and 
probably  also  in  the  chimpanzee,  macaques 
and  other  monkeys.    Dobell  (1935)  was  un- 
able to  infect  a  Macaca  mulatta  and  a  M. 
sinica  with  cultures  of  R.   intestinalis  from 
man,  but  nevertheless  believed  it  likely 
that  the  Retortamonas  of  man  and  maca- 
ques belong  to  the  same  species.    It  is  not 
common  in  man,  and  is  non- pathogenic. 

The  trophozoites  oi  R.   intestinalis 
are  elongate  piriform,  4  to  9|i.long  and  3 
to  4/i  wide.     The  cysts  are  uninucleate, 
piriform,   4.  5  to  7fj,  long  and  3  to  4.  Sjj. 
wide  and  have  a  rather  thick  wall.    This 
species  can  be  cultivated  in  the  usual  cul- 
ture media  for  intestinal  protozoa. 


Retortamonas  ovis  (Hegner  and  Schu- 
maker,   1928)  (syn.  ,  Einbadoi)iO)ias  ovis) 
was  described  from  trophozoites  and  cysts 
in  cultures  from  sheep  feces  in  Maryland. 
The  trophozoites  are  piriform  and  average 
5.2  by  3.4^L. 

Retortamonas  cuniculi  (Collier  and 
Boeck,   1926)  (syn. ,  Embadomonas  cuni- 
culi) occurs  in  the  cecum  of  the  rabbit. 
The  trophozoites  are  generally  ovoid  but 
occasionally  have  a  tail-like  process;  they 
measure  7  to  13  by  5  to  10 |U  .     The  cysts 
are  oval  and  measure  5  to  7  by  3  to  4  ji . 
Collier  and  Boeck  (1926)  found  this  species 
in  1  of  50  rabbits.    It  is  apparently  non- 
pathogenic. 


Genus  CHILOMASTIX 
Alexeieff,  1912 

The  body  is  piriform  and  plastic,  with 
a  large  cytostomal  groove  near  the  anterior 
end  containing  in  its  margin  a  cytoplasmic 
fibril  which  extends  across  the  anterior  end 
and  posteriorly  along  each  side.    The  nu- 
cleus is  anterior.     There  are  3  anteriorly 
directed  flagella  and  a  short  fourth  flagel- 
lum which  undulates  within  the  cytostomal 
cleft.     Cysts  are  formed.    Synonyms  of  this 
genus  are  Macrostoma  Alexeieff,   1909  and 
Fanapepea  Prowazek.     Chilomastix  is 
found  in  mammals,  birds,  reptiles,  am- 
phibia, fish,  insects  and  leeches.    All  spe- 
cies are  apparently  non- pathogenic. 

Chilomastix  mesnili  (Wenyon,   1910) 
Alexeieff,   1912  (syns.  ,  Macrostoma 
mesnili,   Chilomastix  suis,   Chilomastix 
hominis)  is  found  in  the  cecum  and  colon  of 
man,  the  orang-utan,  chimpanzee,  a  num- 
ber of  monkeys  {Macaca,   Cercopithecus, 
Cebus,  Pithecus)  and  the  pig.    It  is  quite 
common  in  man,   having  been  found  in  1  to 
28%  in  various  surveys;  according  to 
Belding  (1952),  it  was  found  in  3.  4%  of 
35,  577  persons  in  recent  surveys  in  the 
United  States,  and  in  6. 1%  of  19,  006  per- 
sons elsewhere  in  the  world.    Frye  and 
Meleney  (1932)  found  it  in  3  of  127  pigs  in 
Tennessee.    Kessel  (1928)  found  it  in  pigs 
in  California,  and  Reichenow  (1952)  in 
Hamburg,  Germany.    Simitch  et  al.  (1959) 


112 


OTHER   FLAGELLATES 


found  it  in  1. 1%  of  1800  pigs  in  Yugosla- 
via. 

Kessel  (1924)  transmitted  C.  mesnili 
from  man  to  monkeys,  and  Deschiens 
(1926)  from  the  chimpanzee  to  Macaca 
siiiicci.  However,  Simitch  el  al.  failed  to 
transmit  C.  iiiesiiili  from  man  to  2  young 
pigs  and  consequently  named  the  pig  form 
C.  sitis. 


Fig.  15.     Chiloniastix.     A.    Trophozoite. 
B.    Cyst.    X  2800  (Original) 


The  trophozoites  of  C.   mesnili  are 
asymmetrically  piriform,  with  a  spiral 
groove  running  thru  the  middle  half  of  the 
body.     The  posterior  end  is  drawn  out 
when  the  protozoa  are  moving.    The 
trophozoites  are  6  to  24ji  long  and  3  to 
10|i  wide.     The  cytostomal  cleft  is  about 
6  to  8|i  long  and  2\i  wide.     A  complex  of 
6  minute  blepharoplasts  lies  anterior  to 
the  nucleus;  from  them  come  the  3  free 
anterior  flagella  (of  which  2  are  short  and 
the  third  is  relatively  long),  the  cytostomal 
flagellum,  and  the  2  cytostomal  fibrils. 
The  cysts  are  lemon-shaped,  6.  5  to  lOfi 
long,   and  contain  a  single  nucleus  and  the 
organelles  of  the  trophozoite. 

C.  mesnili  is  ordinarily  considered 
non- pathogenic.     However,  Mueller  (1959) 
suggested  that  it  might  possibly  be  a  mild 
pathogen  occasionally.     He  referred  to  an 
outbreak  of  watery  diarrhea  in  very  young 
children  in  Czechoslovakia  and  to  his  own 


experience  with  watery  diarrhea  accom- 
panied by  swarms  of  Cliiloinaslix  following 
a  visit  to  Mexico.    This  species  can  be 
cultivated  in  the  usual  media  used  for  in- 
testinal protozoa. 

C.  cuniciili  da  Fonseca,   1915  occurs 
in  the  cecum  of  the  domestic  rabbit.    It  is 
morphologically  similar  to  C.   mesnili. 
The  trophozoite  is  ordinarily  10  to  15pL 
long,  but  may  range  from  3  to  20fi  . 

C.   ca/>rae  da  Fonseca,   1915  was  re- 
ported from  the  rumen  of  the  goat  in  Bra- 
zil.   Das  Gupta  (1935)  found  it  in  India.    It 
is  morphologically  very  similar  to  C.  mes- 
nili and  is  8  to  10 ^L  long  and  4  to  6(1  wide. 

C.  gallinarum  Martin  and  Robertson, 
1911  occurs  in  the  ceca  of  the  chicken  and 
turkey.     McDowell  (1953)  found  it  in  40% 
of  a  large  number  of  chickens  in  Pennsyl- 
vania.   The  body  is  pear-  or  carrot-shaped, 
11  to  20  by  5  to  12/1 .     The  nucleus  is 
pressed  against  the  anterior  end  of  the 
body.    The  cytostomal  pouch  is  8-shaped, 
spirals  toward  the  left  on  the  ventral  side, 
and  extends  1/2  to  2/3  of  the  body  length. 
Cysts  are  rare  in  cecal  material  but  com- 
mon in  culture.     They  are  lemon-shaped, 
measure  7  to  9  by  4  to  6  jj. ,  and  have  a 
single  nucleus.     McDowell  (1953)  cultiva- 
ted C.  gallinarum  easily  in  Ringer's  solu- 
tion with  0.2%  gastric  mucin  at  39  to  40  C. 

C.  intestinalis  Kuezynski,   1914  and 
C.  wenrichi  Nie,   1948  occur  in  the  cecum 
of  the  gunea  pig,  and  C.  bettencoiirti  da 
Fonseca,   1915  in  that  of  the  laboratory 
rat,  domestic  mouse  and  golden  hamster. 


FAMILY   CALLIMASTIGIDAE 

Members  of  this  family  have  a  single 
nucleus  and  a  compact  antero-lateral  group 
of  flagella  which  beat  as  a  unit.    There  are 
2  genera,  Callimastix  and  Selenomonas. 


Genus  CALLIMASTIX 
Weissenberg,   1912 

The  body  is  ovoid,  with  a  compact 
central  or  anterior  nucleus.    There  are 


OTHER   FLAGELLATES 


113 


12  to  15  long  flagella  near  the  anterior  end 
which  beat  in  unison.     One  species  occurs 
in  the  body  cavity  of  copepods  and  the 
others  in  ruminants  and  equids.     They  are 
non- pathogenic. 

CaUi)Jiastix  frontalis  Braune,   1913 
occurs  in  the  rumen  of  cattle,  sheep  and 
goats  thruout  the  world.     Becker  and  Tal- 
bot (1927)  reported  it  in  Iowa.     The  body  is 
spherical  or  ovoid,  about  12  to  14  fi  in  di- 
ameter.   The  nucleus  has  a  large  central 
endosome.    The  12  flagella  are  about  30 /i 
long;  they  arise  from  a  row  of  basal  gran- 
ules on  the  anterior  margin  of  the  body 
and  join  to  form  a  single  unit  distally. 
This  species  has  been  found  in  material 
submitted  for  diagnosis  of  Tritrichomonas 
foetus  infections  (Morgan  and  Hawkins, 
1952). 

Callimastix  eqiii  Hsiung,   1929  occurs 
in  the  cecum  and  colon  of  the  horse.     The 
body  is  kidney- shaped  with  the  hilus  at  its 
anterior  third;  it  is  12  to  18  ^l  long  and  7 
to  10  fi  wide  with  a  mean  of  14  by  8  /i . 
Just  behind  the  hilus  is  a  clear,  granule- 
free  area  on  the  margin  of  which  are  12  to 
15  basal  granules  which  give  rise  to  fla- 
gella 25  to  30  ^  long;  these  unite  distally 
and  function  as  a  unit.    The  rest  of  the 
cytoplasm  is  filled  with  deeply  staining 
granules.     The  nucleus  \s  Zii  in  diameter 
has  a  large  endosome  and  lies  near  the 
center  of  the  body. 


Genus  SEUNOMONAS 
Von  Prowazek,  1913 

The  body  is  kidney-  to  crescent- 
shaped,  with  blunt  ends.     One  or  more 
flagella  are  attached  to  the  middle  of  the 
concave  side.    The  flagella  are  thicker  at 
the  base  than  at  the  free  end  and  are 
usually  1  to  1.  5  times  as  long  as  the  body. 
The  nucleus  is  highly  retractile  and  lies 
on  the  concave  side  near  the  base  of  the 
flagella.    Reproduction  is  by  transverse 
binary  fission  thru  the  flagellar  region. 
This  genus  has  been  placed  by  many  au- 
thors in  the  Spirillaceae  among  the  bac- 
teria, but  Jeynes  (1955,   1956)  showed 
that  it  is  actually  a  protozoon.    It  is  not 
pathogenic. 


Selenomonas  ruminantium   (Certes, 
1889)  Wenyon,   1926  (syns.,  Ancyromonas 
ri())iiiiantiii»i.   Seleiioniastix  rioiiinantium) 
occurs  in  the  rumen  of  cattle,  sheep, 
goats  and  various  wild  ruminants  including 
the  gazelle,  giraffe,  antelope  (CepJialoplins 
)uaxivelli)  in  Africa  and  the  pronghorn  an- 
telope (A)itilocapra  ainericmia),  deer 
(Odocoileus  hemionus)  and  elk  {Cervus 
iianiiodes)  in  the  United  States  (California). 
It  was  also  found  in  the  blood  of  the  African 
antelope  by  Kerandel  (1909),  of  the  prong- 
horn  antelope  by  Chattin,   Herman  and 
Kirby  (1944)  and  of  the  deer  (O.  lieii/ioiiKs) 
by  Herman  and  Sayama  (1951)  in  California. 
According  to  Lessel  (1957),  S.  rii»iinan- 
tiiu)i  is  the  predominant  organism  found  on 
microscopic  examination  of  the  rumen 
juices. 

The  body  of  S.  ru})ii)iautii(>n   is  cres- 
cent-shaped,  9.  5  to  11  by  2  to  3  li ,  with  a 
tuft  of  flagella  arising  from  the  center  of 
the  concave  side.     The  nucleus  is  in  the 
center  of  the  concave  side.     There  are  no 
cysts.     This  species  has  not  been  culti- 
vated. 


Fig.  16.     Selenomonas  ruminantium. 
X  2800.     (Original) 


Selenomonas  palpitans  Simons,  1922 
occurs  in  the  cecum  and  upper  part  of  the 
colon  of  the  guinea  pig. 

S.   spidigeua  (Flugge,   1886)  Dobell, 
1932  occurs  in  the  mouth  of  man.    It  grows 
well  in  thioglycollate  broth. 


FAMILY   POLYMASTIGIDAE 

Members  of  this  family  have  4  anter- 
ior flagella,  an  axostyle  and  a  single 


114 


OTHER   FLAGELLATES 


nucleus.    They  apparently  lack  a  para- 
basal body.     The  only  genus  found  in  do- 
mestic animals  is  Monocerconiunoides . 


Genus  MONOCERCOMONOfDES 
Travis,   1932 

Members  of  this  genus  have  4  anterior 
flagella  in  2  pairs,  a  pelta  and  an  axostyle 
which  is  generally  filamentous.     Nie  (1950) 
described  1  to  4  strand-like  funises  which 
stain  with  protargol  in  4  species  of  this 
genus  from  the  guinea  pig.     The  funis  is 
a  costa-like  structure  extending  backwards 
just  beneath  the  body  surface.     Members 
of  this  genus  occur  in  insects,  amphibia, 
reptiles  and  a  number  of  mammals.    They 
are  non-pathogenic. 

Monocercomonoides  caprae  (Das 
Gupta,   1935)  (syn.  ,  Monocercomonas 
caprae)  was  described  from  the  rumen  of 
the  goat  in  India.    The  body  is  ovoid,  6  to 
12(1  long  and  4  to  8  p.  wide. 

Monocercomonoides  caviae  (Cunha 
and  Muniz,   1921)  Nie,   1950,  M.  qiiadri- 
funilis  Nie,   1950,  Al.  ivenrichi  Nie,   1950 
andM.  exilis  Nie,  1950  occur  in  the  cecum 
of  the  guinea  pig. 

MonocercoDionoides  sp.  was  found  by 
Saxe  (1954)  in  the  laboratory  rat  and 
golden  hamster.     He  transmitted  it  from 
the  hamster  to  the  rat.     This  species 
awaits  morphologic  study  and  specific 
characterization. 


Genus  COCHLOSOMA 
Kotlan,  1923 

The  body  is  ovoid,  broadly  rounded 
anteriorly  and  narrowly  rounded  poster- 
iorly.   Six  flagella  of  unequal  length  arise 
from  a  blepharoplastic  complex  at  the  an- 
terior end;  2  of  them  are  trailing  and  lie 
in  a  longitudinal  groove.     The  nucleus  is 
near  the  middle  of  the  body.    A  slender, 
fibrillar  axostyle  and  a  more  lateral  costa 
arise  from  the  blepharoplastic  complex. 
On  the  anteroventral  surface  is  a  large 
sucker  which  opens  on  the  left  side  and 
has  a  marginal  filament.    A  parabasal 
body  is  present. 

Cochlosoma  anatis  Kotlan,   1923  (syn. , 
Cochlosoma  roslratn»i)  occurs  in  the  cloaca, 
large  intestine  and  sometimes  the  ceca  of 
the  domestic  duck,   Muscovy  duck  and  also 
in  the  wild  mallard  and  various  other  wild 
ducks.     It  has  been  reported  in  Hungary  by 
Kotlan  (1923),  in  California  by  Kimura 
(1934),   in  Iowa  by  Travis  (1938),  and  is 
probably  worldwide  in  distribution.    Kimura 
(1934)  found  it  in  23  of  30  White  Pekin  and 
Muscovy  ducks  in  central  California. 

The  body  of  C.  anatis  is  beet-shaped, 
6  to  12^1  long  and  4  to  Yfi  wide.    The  sucker 
covers  1/3  to  12  the  body  length.    The  or- 
ganism swims  forward  with  an  erratic, 
jerky  motion,  rotating  on  its  long  axis  but 
with  very  little  of  the  dipping  motion  of 
Giardia.     The  parabasal  body  is  sausage- 
shaped.     Reproduction  is  by  longitudinal 
fission.     C.  anatis  has  not  been  cultivated. 


FAMILY   COCHLOSOMATIDAE 

In  this  family  there  are  6  anterior 
flagella,  an  axostyle,  an  anteroventral 
sucker,  and  a  single  nucleus.    There  may 
or  may  not  be  a  parabasal  body.    The  only 
genus  so  far  reported  from  domestic  ani- 
mals is  Cochlosoma,  but  Cyathostonia 
Tyzzer,   1930  and  Ptychostoma  Tyzzer, 
1930  have  been  described  from  the  ruffed 
grouse  (Bonasa  iimbellus)  in  North  Amer- 
ica. 


The  pathogenicity  of  C.  anatis  in  water- 
fowl is  unknown.     Kimura  (1934)  found  it  in 
both  healthy  and  sick  birds,  but  the  condi- 
tion of  the  latter  was  due  to  bacterial  or 
nutritional  disturbances,  and  even  in  heavy 
Cochlosonia  infections  there  was  no  intes- 
tinal inflammation.     Travis  (1938)  found 
no  lesions  in  the  infected  domestic  and 
wild  ducks  which  he  examined. 

McNeil  and  Hinshaw  (1942)  reported 
finding  a  Cochlosoma  morphologically  in- 
distinguishable from  C.  anatis  in  turkeys 


OTHER   FLAGELLATES 


115 


in  California.    In  young  poults  it  was  pres- 
ent thruout  the  intestinal  tract,  and  in 
adults  in  the  region  of  the  cecal  tonsil. 
Campbell  (1945)  found  Coclilosonia  in 
large  numbers  in  the  intestinal  tracts  of  a 
flock  of  young  turkeys  in  Scotland  affected 
with  a  disease  clinically  and  pathologically 
indistinguishable  from  infectious  catarrhal 
enteritis  due  to  Hexa»iita  meleagridis. 
Both  McNeil  and  Hinshaw  and  Campbell 
considered  the  turkey  form  to  be  the  same 
species  found  in  ducks,  but  experimental 
and  further  morphological  studies  are 
needed  to  be  sure  of  this. 

It  has  not  been  established  whether 
this  form  is  pathogenic  for  turkeys. 
Campbell  believed  that  it  was  the  cause  of 
the  enteritis  which  he  saw,  but  Hexamita 
was  also  usually  detectable  in  his  affected 
birds.    In  the  turkey  poults  studied  by 
McNeil  and  Hinshaw,   Cochlosoma  was  al- 
ways found  in  association  with  Hexamita 
or  with  Hexamita  and  SalDionella. 


FAMILY   HEXAMITIDAE 

Members  of  this  family  are  bilaterally 
symmetrical,  with  2  nuclei,   6  or  8  fla- 
gella  and  sometimes  with  axostyles  and 
parabasal  bodies.     Three  genera  are  of 
veterinary  interest:     Hexamita,   Giardia 
and  Trepomonas. 


Genus  HEXAMITA 
Dujardin,  1838 

The  body  is  piriform,  with  2  nuclei 
near  the  anterior  end,   6  anterior  and  2 
posterior  flagella  and  2  independent  axo- 
styles (which  may  possibly  be  hollow  tubes 
rather  than  rods).     The  body  is  quite  sym- 
metrical, three  anterior  flagella  and  1 
posterior  one  arising  on  each  side.     Free- 
living  forms  have  1  or  2  contractile  vac- 
uoles.   The  cytostome  is  obscure  if  pres- 
ent.   Some  species  form  cysts.    Some 
members  of  this  genus  are  free-living, 
while  others  are  parasitic  in  insects, 
other  invertebrates  and  all  classes  of  ver- 
tebrates.    The  taxonomic  relations  of  the 
various  species  are  greatly  confused,  and 
much  work  is  needed  before  they  will  be 


understood.    Reasons  why  some  workers 
use  the  spelling  Hexamitus  are  given  by 
Kirby  and  Honigberg  (1949). 


HEXAMITA  MELEAGRIDIS 
McNEIL,   fflNSHAW  AND 
KOFOID,   1941 

Disease:     Hexamitosis,  infectious 
catarrhal  enteritis. 

Hosts:     Turkey,  peafowl,   California 
valley  quail,  Gambel's  quail,  chukar  par- 
tridge,  ring-neck  pheasant,   golden  pheas- 
ant.   See  Levine,  Beamer  and  McNeil 
(1952)  for  references.     H.  meleagridis 
has  been  transmitted  from  the  turkey  to 
the  chicken,  quail  and  domestic  duck,  and 
from  the  ring-neck  pheasant,  quail  and 
chukar  partridge  to  the  turkey. 

Location:     Duodenum  and  small  in- 
testine of  younger  birds;  some  occur  in 
the  cecum  and  bursa  of  Fabricius,  espe- 
cially in  adults. 

Geographic  Distribution:     United 
States,  Canada,  Great  Britain,  South 
America  (Uruguay).      The  distribution  of 
hexamitosis  in  California  has  been  dis- 
cussed by  Hinshaw,   McNeil  and  Kofoid 
(1938).     It  has  been  reported  from  Con- 
necticut by  Jungherr  and  Gifford  (1944), 
from  Indiana  by  Doyle,  Cable  and  Moses 
(1947),  from  Virginia  by  Farr,  Wehr  and 
Jaquette  (1948),  from  Alberta  by  Vance 
and  Bigland  (1956),  from  Scotland  by 
Campbell  (1945)  and  from  England  by 
Slavin  and  Wilson  (1953).    It  also  occurs 
in  Illinois. 

Prevalence:     The  published  reports 
of  outbreaks  of  hexamitosis  are  too  few  to 
give  a  true  picture  of  its  importance.    It 
occurs  in  all  major  turkey  producing  areas 
in  the  United  States  and  in  other  countries 
as  well.    It  appears  to  be  particularly  im- 
portant in  California.     The  U.  S.  Dept.  of 
Agriculture  (1954)  estimated  that  it  causes 
an  annual  loss  of  $667,000  in  turkeys  in 
the  United  States. 

Morphology:     The  body  is  6  to  12/i 
long  and  2  to  5/j,  wide,  with  a  mean  of  9 


llfi 


OTHER  FLAGELLATES 


by  3/i.    The  two  nuclei  contain  round  endo- 
somes  2/3  the  diameter  of  the  nucleus. 
Anterior  to  each  nucleus  is  a  large  blephar- 
aroplast  or  group  of  blepharoplasts  from 
which  2  anterior  and  1  anterolateral  fla- 
gella  arise.    Just  behind  this  blepharoplast 
is  another  from  which  the  caudal  flagellum 
arises.    The  caudal  flagella  pass  poster- 
iorly in  a  granular  line  of  cytoplasm  to 
their  points  of  emergence  near  the  poster- 
ior end  of  the  body.     Hexamita  moves  ra- 
pidly without  the  spiralling  characteristic 
of  trichomonads. 


Fig.  17.     Hexamita  iiieleagridis. 
(Original) 


X  2800. 


Life  Cycle:     Multiplication  is  by 
longitudinal  binary  fission.    Slavin  and 
Wilson  (1953)  and  Wilson  and  Slavin  (1955) 
described  what  they  believed  to  be  schizog- 
ony and  cyst  formation,  but  Hoare  (1955) 
considered  their  idea  to  be  purely  specu- 
lative and  inacceptable. 

Pathogenesis:     Hexamitosis  is  a  dis- 
ease of  young  birds;  adults  are  symptom- 
less carriers.    The  mortality  in  a  flock 
may  be  as  high  as  70  to  80%,  but  heavy 
losses  seldom  occur  in  poults  over  ten 
weeks  old.    Affected  poults  appear  nervous 
at  first,   have  a  stilted  gait,   ruffled,  un- 
kempt feathers,  and  a  foamy,  watery 
diarrhea.    They  usually  continue  to  eat, 
but  chirp  continually.     They  lose  weight 
rapidly,  become  listless,  weak  and  finally 
die.    Birds  often  do  not  appear  to  be  ill 
until  shortly  before  death,  but  examination 


will  reveal  that  they  are  thin  and  have 
lowered  temperatures.     Birds  which  re- 
cover grow  poorly,  and  an  outbreak  may 
leave  many  stunted  birds  in  its  wake. 

The  incubation  period  is  4  to  7  days. 
Poults  may  die  within  a  day  after  signs 
appear.     In  acute  outbreaks,  the  mortality 
reaches  a  peak  in  the  flock  in  7  to  10  days 
after  the  first  birds  die;  in  other  flocks, 
deaths  may  continue  for  3  weeks. 

The  principal  pathological  changes 
are  found  in  the  small  intestine.     Catarrhal 
inflammation  with  marked  lack  of  tone  is 
present  in  the  duodenum,  jejunum  and 
ileum.     The  intestinal  contents  are  usually 
thin,  watery  and  foamy,  with  localized 
bulbous  swellings  filled  with  watery  fluid. 
The  small  intestine,  especially  the  anter- 
ior part,  is  inflamed  and  edematous.     The 
cecal  contents  are  usually  fluid,  and  the 
cecal  tonsils  are  congested. 

Epidemiology:     Hexamita  is  trans- 
mitted thru  contaminated  feed  and  water. 
Carrier  adult  birds  which  have  survived 
earlier  attacks  are  the  most  important 
source  of  infection  for  turkey  poults. 
Sometimes  the  disease  does  not  appear  in 
the  earlier  hatches  but  strikes  the  later 
ones  after  the  adults  have  been  sold.    This 
may  come  about  because  the  infections  in 
the  earlier  hatches  were  very  light  or  per- 
haps because  the  virulence  of  the  strains 
was  too  low  to  cause  noticeable  disease. 
According  to  Hinshaw  (1959)  it  may  take 
several  passages  in  poults  of  a  strain  from 
carrier  turkeys  before  an  acute  outbreak 
occurs. 

Wild  quail,  pheasants  and  chukar  par- 
tridges sharing  the  range  with  turkeys  may 
also  be  a  source  of  infection. 

Hot  weather  and  overcrowding  may 
also  contribute  to  the  severity  of  an  out- 
break.   In  addition,  the  role  of  flies  de- 
serves study.     Turkey  poults  are  excellent 
fly-catchers,   and  these  insects  might  carry 
the  protozoa  from  one  pen  to  another. 

Diagnosis:  Hexamitosis  can  be  diag- 
nosed by  finding  the  protozoa  in  scrapings 
from  the  small  intestine,  and  particularly 


OTHER   FLAGELLATES 


117 


from  the  jejunum  and  duodenum.     The 
smears  should  be  mixed  with  physiological 
salt  solution  and  examined  while  fresh. 
Hexanilta  can  be  readily  differentiated 
from  TrichoDionas,   Giardia  or  Cochlosoma 
by  its  small  size,  absence  of  a  sucker  or 
undulating  membrane,  and  characteristic 
motion.    Impression  smears  can  also  be 
made  of  cross  sections  of  fresh  small  in- 
testine, dried  rapidly  and  stained  with 
Giemsa's  stain;  the  protozoa  are  often 
found  in  groups  in  the  crypts.    Hexaiiiita 
can  also  be  found  in  the  bursa  of  Fabricius 
and  cecal  tonsils  in  carrier  birds. 

Cultivation:      Hexamita  nieleagridis 
has  not  been  cultivated  in  artificial  culture 
media,  but  Hughes  and  Zander  (1954)  cul- 
tured it  axenically  in  the  chorioallantoic 
fluid  of  chick  embryos. 

Treatment:     No  treatment  has  appar- 
ently been  uniformly  successful  for  hexa- 
mitosis.     McNeil  (1948)  recommended 
replacing  the  drinking  water  for  several 
days  with  a  mixture  of  3%  dried  whey  in 
1-2000  aqueous  copper  sulfate  solution. 
It  must  be  begun  early  in  an  outbreak  to  be 
effective,  and  Wilson  and  Slavin  (1955)  did 
not  find  it  to  be  of  value  in  their  studies. 

Almquist  and  Johnson  (1951)  found  in 
preliminary  tests  that  streptomycin  was 
ineffective,  but  that  penicillin,   chlortetra- 
cycline  and  oxytetracycline  were  of  some 
value.    Enheptin  also  gave  good  results 
when  fed  as  0.1%  of  the  mash  for  14  days. 
Wilson  and  Slavin  (1955)  said  that  they 
tested  every  antiprotozoal  drug  available 
commercially  in  England  (including  anti- 
malarials, trypanocides,  amoebicides  and 
antiluetics)  without  success.     Enheptin  was 
only  about  50%  effective  in  experimentally 
infected  poults.     The  most  promising  drug 
was  di-n-butyl  tin  dilaurate,  which  ap- 
peared to  control  mild  field  outbreaks  and 
to  lower  the  death  rate  in  more  severe 
ones. 

Mangrum  et  al.  (1955)  reported  that 
furazolidone  reduced  mortality  in  exper- 
imentally infected  turkey  poults.     McNeil 
(1958)  mentioned  that  nithiazide  had  been 
used  successfully  by  Merck,  Sharp  & 
Dohme  Research  Laboratories  in  a  com- 


bined outbreak  of  histomonosis  and  hexa- 
mitosis. 

Prevention  and  Control:     Hexamitosis 
can  be  prevented  by  proper  management 
and  sanitation.     Poults  should  be  separated 
from  adults,   and  separate  caretakers  should 
be  used  for  the  two  groups.    If  feasible, 
breeding  birds  should  be  sold  2  weeks  before 
any  poults  are  hatched.    Separate  equipment 
should  be  used  for  different  groups  of  birds. 
Attendants  should  keep  out  of  the  pens,  and 
the  feeders  and  waterers  should  be  placed 
where  they  can  be  reached  from  the  outside. 
Feeders  and  waterers  should  be  placed  on 
wire  platforms.     Young  birds  should  be  kept 
on  wire.     Ranges  frequented  by  pheasants, 
quail  and  chukar  partridges  should  be 
avoided.    General  sanitation  and  fly  control 
should  be  practiced. 


OTHER  SPECIES  OF   HEXAMITA 

Hexamita  columbae  (NoUer  and  Butt- 
gereit,   1923)     (syn.  ,  Octo»iitus  coliiuibae) 
occurs  in  the  duodenum,  jejunum,   ileum 
and  large  intestine  of  the  pigeon.    It  is  5 
to  9|u  long  and  2.  5  to  7 p.  wide.     It  is  path- 
ogenic,  causing  a  catarrhal  enteritis. 
Noller  and  Buttgereit  (1923)  found  it  in 
great  masses  from  the  gizzard  to  the  anus 
in  a  pigeon  with  catarrhal  enteritis  in  Ger- 
many, and  McNeil  and  Hinshaw  (1941) 
found  it  in  affected  pigeons  in  California. 
They  were  unable  to  infect  turkeys  with 
this  species. 

Hexam ita -was  found  by  Kotlan  (1923) 
in  the  intestinal  mucus  of  the  domestic 
duck  in  Hungary.     He  called  it  "Hexamitus 
intestinalis  (?)".    It  was  usually  piriform, 
10  to  13/i  long  and  4  to  5(u  wide.     Kimura 
(1934)  found  Hexamita  in  the  ceca  and  large 
intestine  of  domestic  ducks  in  California. 
McNeil  and  Hinshaw  (1941)  infected  domes- 
tic ducks  experimentally  with  H.  melea- 
gridis  from  the  turkey.    It  is  uncertain 
whether  the  duck  form  is  a  separate  species. 
It  has  not  been  adequately  described,  and 
its  pathogenesis  is  unknown. 

Hexamita  muris  (Grassi,   1881)  (syns.  , 
Octomitus  muris,   Syndyomita  nniris) occurs 
in  the  posterior  small  intestine  and  cecum 


118 


OTHER   FLAGELLATES 


of  the  Norway  rat,  house  mouse,  golden 
hamster  and  various  wild  rodents.    It 
measures  7  to  9  by  2  to  3  (i  . 

Wenrich  (1933)  described  Hexamita 
sp.  from  the  feces  of  a  rhesus  monkey. 
It  measured  4  to  6  by  2  to  4  jj, . 


Genus  OCTOMIlUi 
Von   Prowazek,    1904 

The  body  is  piriform,  with  2  nuclei 
near  the  anterior  end,  and  6  antenior  and 
2  posterior  flagella.     The  body  is  quite 
symmetrical,   3  anterior  flagella  and  1 
posterior  one  arising  on  each  side.    There 
are  2  axostyles  which  originate  at  the  an- 
terior end  and  fuse  as  they  pass  poster- 
iorly, emerging  as  a  single  central  rod 
from  the  middle  of  the  posterior  end. 
This  genus  differs  from  Hexamita,   of 
which  it  was  formerly  considered  a  syn- 
onym,  in  the  structure  of  its  axostyles 
(Gabel,  1954). 

Octomitus  pulcher  (Becker,  1926) 
Gabel,   1954  (syn. ,    O.  intestinalis)  occurs 
in  the  cecum  of  the  Norway  rat,   house 
mouse,  golden  hamster,   ground  squirrels 
and  other  wild  rodents.    It  measures  6  to 
10  by  3  to  7 /i. 


Genus  GIARDIA  Kunstler,   1882 

The  body  is  piriform  to  ellipsoidal, 
and  bilaterally  symmetrical.     The  anterior 
end  is  broadly  rounded,  and  the  posterior 
end  is  drawn  out.     There  is  a  large  suck- 
ing disc  on  the  ventral  side;  the  dorsal 
side  is  convex.     There  are  2  anterior  nu- 
clei,  2  slender  axostyles,   8  flagella  in  4 
pairs,  and  a  pair  of  darkly  staining  median 
bodies.    The  cysts  have  2  or  4  nuclei  and 
a  number  of  fibrillar  remnants  of  the 
trophozoite  organelles.    A  synonym  of  this 
generic  name  is  Lamblia  Blanchard,   1888. 

The  names  given  the  species  of  Giardia 
depend  on  the  authorities  concerned.  Tra- 
ditionally, it  has  been  believed  that  Giardia 
is  highly  host-specific,  and  different  names 
have  been  given  to  almost  all  the  forms  in 
different  hosts.    Thus,  if  we  accept  the 


names  in  Ansari's  (1951,  1952)  review, 
the  species  in  cattle  is  G.  bovis,   that  in 
goats  and  sheep  G.  caprae,    that  in  the  dog 
G.  canis,    that  in  the  cat  G.  cali,    that  in 
the  rabbit  G.  duodenaiis ,  that  in  the  guinea 
pig  G.   caviae,  those  in  the  Norway  rat  G. 
muris  and  G.   simoni,  and  those  in  the 
house  mouse  G.   muris  a.ndG.  microti. 
However,   Filice  (1952)  was  unable  to  find 
any  morphological  difference  between  the 
giardias  of  the  laboratory  rat  and  a  num- 
ber of  wild  rodents,  and  on  reviewing  the 
literature  discovered  that  almost  no  ac- 
ceptable cross-transmission  studies  exist 
between  some  species.     Altho  he  did  not 
discuss  them  all,   he  appears  to  have  con- 
cluded that  there  are  only  two  species  of 
Giardia  in  mammals,  each  with  a  number 
of  races.     G.  muris  occurs  in  the  mouse, 
rat  and  hamster,  and  G.   duodenaiis  in  the 
rabbit,   rat,  chinchilla,  ground  squirrel, 
deermouse,  pocket  mouse,  man  and  pre- 
sumably ox,  dog,  cat  and  guinea  pig, 
among  others.    The  essential  difference 
between  these  two  forms  is  that  the  median 
bodies  of  G.   muris  are  small  and  rounded 
while  those  of  G.  duodenaiis  are  long,   re- 
semble somewhat  the  claw  of  a  claw-ham- 
mer, and  lie  approximately  transversely 
across  the  body. 

In  this  connection,   Hegner's  (1930), 
Armaghan's  (1937)  and  Haiba's  (1956) 
success  in  infecting  laboratory  rats  with 
Giardia  from  man  suggests  that  Filice' s 
view  may  eventually  prevail.     However, 
careful  cross-transmission  studies  must 
be  carried  out  before  a  decision  can  be 
made.    In  the  meantime,   it  is  more  con- 
venient to  use  different  specific  names  for 
most  of  the  forms  from  different  hosts. 

Associated  with  this  nomenclatorial 
problem  is  an  important  epidemiological 
one.    If  it  turns  out  that  Giardia  can  be 
freely  transmitted  from  one  host  to  an- 
other, we  shall  have  to  revise  our  ideas 
about  the  danger  to  man  of  infections  in 
laboratory  and  domestic  animals,  and  of 
infections  in  one  domestic  animal  to  others. 
Here  is  an  area  of  ignorance  which  de- 
serves exploration. 

Giardia  has  not  yet  been  cultivated  in 
artificial  media,  a  fact  which  has  hampered 


OTHER   FLAGELLATES 


119 


studies  both  of  its  epidemiology  and  path- 
ogenicity.    However,  Karapetyan  (1960) 
cultivated  G.  lamblia  in  chicken  fibroblast 
tissue  cultures. 


GIARDIA  LAMBLIA 
STILES,   1915 

Synonyms:     CercoiHOiias  iiitestinalis, 
Lamblia  intestinalis,   Giardia    intestinalis , 
Megasto))Hi  entericiiiii ,   Giardia  enterica. 
European  writers  still  call  this  species 
Giardia  intestinalis,  but  there  was  so 
much  confusion  about  the  availability  of 
the  specific  names  intestinalis  and  enter- 
ica that  Stiles  (1915)  established  the  pres- 
ent name. 

Disease:     Giardiosis. 

Hosts:     Man,   Old  and  New  World 
monkeys,   pig.     Hegner  (1930)  and  Arma- 
ghan  (1937)  infected  laboratory  rats  and 
Bonestell  (1935)  infected  woodrats  (Neo- 
tonia  fiiscipes)  with  G.   huiiblia  from  man. 
Haiba  (1956)  infected  wild  and  laboratory 
Rattus  norvegicus ,   but  failed  to  infect 
wild  R.   rattus  and  laboratory  mice  with 
G.   lamblia  from  man. 


duodenalis  type.  The  cysts  are  ovoid,  8 
to  12j;i  long  and  7  to  lO/i  wide,  and  con- 
tain 4  nuclei. 

Pathogenesis:     There  was  considerable 
controversy  for  many  years  whether  Giardia 
is  pathogenic  in  man,  but  it  is  now  gener- 
ally agreed  that  it  may  be  in  some  individ- 
uals.   Most  infections  are  symptomless, 
but  in  a  fairly  small  number  there  is  a 
chronic  diarrhea.    The  feces  contain  a 
large  amount  of  mucus  and  fat  but  no  blood. 
The  diarrhea  is  accompanied  by  dull  epi- 
gastric pain  and  flatulence.    Affected  per- 
sons have  a  poor  appetite  and  lose  weight. 
In  some  cases  the  gall  bladder  may  be  in- 
vaded and  cholecystitis  may  be  present, 
but  there  is  no  proof  that  the  protozoa 
caused  this  condition.     Pizzi  (1957)  reviewed 
some  of  the  literature  on  the  pathogenicity 
of  G.   lamblia  and  concluded  that  in  heavy 
infections  it  may  also  interfere  with  fat 
absorption  and  produce  a  deficiency  in  fat- 
soluble  vitamins.    It  is  more  often  patho- 
genic in  children  than  adults. 


The  pathogenicity  of  G. 
sv/ine  is  unknown. 


lamblia  for 


Location:     Duodenum,  jejunum,  upper 
small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     G.   lamblia  is  common 
in  man.     In  86  surveys  of  134,966  people 
thruout  the  world  summarized  by  Belding 
(1952),  its  prevalence  ranged  from  2.4  to 
67.  5%  with  a  mean  of  10.  4%.    It  was  found 
in  7.  4%  of  35,  299  persons  in  24  surveys 
in  the  United  States,  and  in  6.  9%  of  65,  295 
persons  in  20  surveys  in  the  rest  of  the 
world.    It  is  about  3  times  as  common  in 
children  as  in  adults. 

G.   lamblia  was  reported  from  a  pig 
in  Tennessee  by  Frye  and  Meleney  (1932). 
Its  prevalence  in  swine  is  unknown. 

Morphology:     The  trophozoites  are  9 
to  21  ju  long,   5  to  15  p.  wide  and  2  to  4/^ 
thick;  they  are  usually  12  to  15ju  long. 
The  median  bodies  are  curved  bars  of  the 


Fig.  18.      A.    Giardia  trophozoite.     X  2800. 
(After  Filice,   1952).     B.    Giardia 
bovis  cyst.    X  2900.     (From 
Becker  and  Frye,   1929) 


120 


OTHER   FLAGELLATES 


Diagnosis:     Giardia  infections  can  be 
diagnosed  by  recognition  of  trophozoites 
or  cysts  in  stained  fecal  smears.     Fixation 
with  Schaudinn's  fluid  and  staining  with  iron 
hematoxylin  are  recommended.     Tropho- 
zoites alone  are  generally  found  in  diarrheic 
stools.     The  cysts  can  be  concentrated  by 
the  flotation  technic.     Zinc  sulfate  solution 
should  be  used  for  flotation;  sugar  and 
other  salt  solutions  distort  the  cysts  and 
make  them  unrecognizable. 

Cultivation:     Neither  G.   lamblia  nor 
any  other  species  of  Giardia  has  been  cul- 
tivated in  artificial  media.    Karapetyan 
(1960)  cultured  it  in  chicken  fibroblast 
tissue  cultures  along  with  the  yeast,   Can- 
dida guillierniondi.     The  protozoon  did  not 
develop  without  the  yeast,  which  led  him  to 
believe  that  there  may  be  a  synergistic  re- 
lation between  the  2  organisms. 

Treatment:     Giardia  infections  in  man 
can  be  successfully  treated  with  either 
quinacrine  or  chloroquine.     Three  oral 
doses  of  0. 1  g  each  are  given  daily  for  5 
days.    Amodiaquin  is  considered  even 
better  than  these  (Lamadrid-Montemayor, 
1954);  a  single  dose  of  0.  6  g  is  given  to 
adults. 

Prevention  and  Control:     These  de- 
pend on  sanitation.     Cerva  (1955)  found 
that  2  to  5%  phenol  or  lysol  would  kill  G. 
lamblia  cysts,  but  that  chloramine,  mer- 
curic chloride,  formalin  and  a  number  of 
other  disinfectants  were  ineffective  in  the 
concentrations  commonly  used.    The  cysts 
were  killed  by  temperatures  above  50°  C 
and,  after  10  hours,  by  freezing  below 
-20°  C.    They  remained  viable  in  water 
for  over  3  months. 


GIARDIA  CANIS 
HEGhfER,   1922 

Host:     Dog. 

Location:     Duodenum,  jejunum,  upper 
small  intestine.    Tsuchiya  (1932)  found 
the  optimum  location  to  be  10  to  30  inches 
posterior  to  the  stomach  in  puppies  on  a 
carbohydrate  diet  and  25  to  40  inches 
from  the  stomach  in  puppies  on  a  high 
protein  diet. 


Geographic  Distribution:     North 
America  (United  States,  Canada),  South 
America  (Uruguay). 

Prevalence:  Catcott  (1946)  found  G. 
canis  in  17.  7%  of  113  dogs  in  Ohio.  Cho- 
quette  and  Gelinas  (1950)  found  it  in  9.0% 
of  155  dogs  in  Montreal,  Canada.    Craige 

(1948)  found  it  in  8.  8%  of  160  dogs  in  Cal- 
ifornia.    We  have  seen  it  a  number  of 
times  in  dogs  in  Illinois,  but  have  not  at- 
tempted a  survey. 

Morphology:     The  trophozoite  is  12 
to  17 ;j  long  and  7  to  10 ji  wide.     The  me- 
dian bodies  are  curved  bars  of  the  duoden- 
alis  type.    The  cysts  measure  9  to  13  by 
7  to  9  fi  . 

Pathogenesis:     The  pathogenicity  of 
G.   canis  for  the  dog  has  still  to  be  incon- 
trovertibly  determined.    Catcott  (1946) 
noted  diarrhea  in  one-third  of  his  positive 
dogs.     Craige  (1948)  found  Giardia  in  17 
of  71  dogs  with  dysentery,  but  in  13  of  them 
other  organisms  which  he  considered  path- 
ogenic were  also  present.     Choquette  (1950) 
found  Giardia  in  several  cases  of  dysentery, 
but  some  of  these  were  complicated  by 
other  conditions.     Tsuchiya  (1931)  reported 
that  diarrheic  stools  alternated  with  formed 
stools  in  a  number  of  experimentally  in- 
fected puppies,  but  was  uncertain  whether 
it  was  due  to  an  existing  pathological  con- 
dition or  to  the  flagellates.     According  to 
Tsuchiya  (1932),  a  carbohydrate  diet  is 
more  favorable  for  G.  ca)iis  than  a  high 
protein  diet. 

Diagnosis:     Same  as  for  G.  lamblia. 

Treatment:     Quinacrine  has  been 
found  effective  against  G.   canis.     Craige 

(1949)  gave  dogs  50  to  100  mg  twice  daily 
for  2  or  3  days,   repeating  if  necessary 
after  3  to  4  days.     Choquette  (1950)  gave 
large  dogs  0.  2  g  three  times  the  first  day 
and  twice  a  day  for  6  more  days;  he  gave 
small  dogs  0. 1  g  twice  the  first  day  and 
once  a  day  for  6  more  days.     Chloroquine 
has  also  been  found  effective  in  man;  0. 1 
g  is  given  3  times  a  day  for  5  days. 

Prevention  and  Control:    The  standard 
sanitary  measures  should  be  used  in  pre- 
venting the  transmission  of  Giardia. 


OTHER  FLAGELLATES 


121 


GIARDIA  CATI 
DESCfflENS,   1925 

Synonym s :    Giardia  felis . 

Host:     Cat. 

Location:     Small  intestine,  large  in- 
testine.    Hitchcock  and  Malewitz  (1956) 
noted  G.   cati  trophozoites  thruout  the 
small  intestine,  cecum  and  colon  (except 
at  the  pyloric  valve)  of  a  naturally  infected 
64-day-old  kitten  in  Michigan.     They  were 
most  numerous  in  the  lower  part  of  the 
small  intestine. 

Geographic  Distribution:     North 
America  (United  States),  Europe  (France). 

Prevalence:     Hitchcock  (1953)  found 
Giardia  in  8  of  14  kittens  in  Michigan. 

Morphology:     It  is  quite  likely  that 
this  species  is  a  synonym  of  G.   canis. 
The  trophozoites  are  10  to  18  jj,  long  and  5 
to  9  jLi  wide  with  a  mean  of  13  by  7  ji .    The 
median  bodies  are  bars  of  the  duodenalis 
type.     The  cysts  are  10.  S/jL  long  and  7/1 
wide. 

Pathogenesis:     Unknown.    The  in- 
fected cats  studied  by  Hitchcock  (1953)  and 
Hitchcock  and  Malewitz  (1956)  apparently 
had  no  signs  of  enteritis. 


GIARDIA  BOVIS 
FANTHAM,   1921 

Host:     Ox. 

Location:     Duodenum,  jejunum,  ileum. 

Geographic  Distribution:     North 
America  (United  States),  Europe  (England, 
Holland,  Austria,  Italy),  South  Africa. 

Prevalence:     Unknown.    Becker  and 
Frye  (1927)  found  this  species  in  the  feces 
of  cattle  in  Iowa,  Nieschulz  (1923)  saw  it 
in  a  calf  in  Holland,  Graham  (1935)  found 
it  alive  and  active  in  the  digestive  tract  of 
6  of  21  female  Cooperia  oncophora  from  a 
calf  from  New  Jersey,  and  we  have  found 
it  from  time  to  time  in  casual  examinations 
in  Illinois. 


Morphology:     The  trophozoites  are 
11  to  19 jn  long  and  7  to  lOfi  wide.     The 
median  bodies  are  curved  bars  of  the  duo- 
denalis type.     The  cysts  are  7  to  16fj.  long 
and  4  to  lOfi  wide. 

Pathogenesis:     The  pathogenicity  of 
G.   bovis  is  unknown.    Supperer  (1952) 
found  it  in  a  calf  in  Austria  with  a  mucous 
diarrhea.     The  calf  was  killed  for  necropsy 
diagnosis  and  was  found  to  have  catarrhal 
duodenitis  and  jejunitis;  the  mucosa  was 
dark  red,  thickened  and  lay  in  folds.    Botti 
(1956,   1956a)  found  it  in  calves  with  hem- 
orrhagic diarrhea  in  Italy.     On  the  other 
hand,  the  cattle  in  which  we  saw  the  or- 
ganism in  Illinois  did  not  appear  to  be 
affected  by  it. 


OTHER  SPECIES  OF   GIARDIA 

Giardia  caprae  Nieschulz,   1923  (syn. , 
G.  ovis)  was  reported  from  the  anterior 
part  of  the  small  intestine  of  2  goats  in 
Holland.     Nieschulz  (1924)  described  it 
further.     Its  trophozoites  are  9  to  17 /i  long 
and  6  to  9jj,  wide  with  a  mean  of  13.  5  by 
7.  5/i.     The  median  bodies  are  curved  bars 
of  the  duodenalis  type.     The  cysts  have  4 
nuclei  and  measure  12  to  15  by  7  to  9/1 
with  a  mean  of  14  by  8  /j, . 

Giardia  caprae  was  found  by  Grassi 
(1881)  in  sheep  in  Italy  and  by  Turner  and 
Murnane  (1932)  in  the  small  intestine  of 
sheep  in  Australia.    The  Australian  sheep 
had  been  losing  weight  gradually  for  sev- 
eral months.    Deas  (1959)  found  it  in  a 
lamb  with  enteritis  in  England.    D.  A. 
Willigan  (unpubl.  )  found  Giardia  in  3  of  24 
iambs  brought  to  the  University  of  Illinois 
Veterinary  Diagnostic  Service.    All  came 
from  a  single  flock  in  which  many  of  the 
lambs  were  suffering  from  diarrhea  and 
loss  of  weight,  but  coccidiosis  and  sal- 
monellosis were  also  found.    Dissanaike 
(1954)  found  live  and  active  G.  caprae  in 
the  intestines  of  50  female  and  no  male 
Nematodirus  filicollis  from  5  sheep  in 
England. 

Giardia  equi  Fantham,   1921  was  or- 
iginally found  in  the  large  intestine  of  a 
horse  in  South  Africa.     Varela  and  Sal- 
samendi  (1958)  found  it  in  the  feces  of  a 


122 


OTHER   FLAGELLATES 


horse  with  colic  in  Venezuela.    Its  troph- 
ozoites measure  17  to  21  by  9  to  12  jx ,  and 
its  cysts  measure  12  to  16  by  8  to  9.  5  fi . 

Giardia  duodenalis  (Davaine,   1875) 
(syns.  ,  HexuDiila  duodenalis,   LciDiblia 
cuniciili)  occurs  in  the  anterior  small  in- 
testine of  Old  and  New  World  rabbits  and 
also  in  Coeiidu  uillosus  in  Brazil.     It  oc- 
curs sporadically  and  is  apparently  not 
pathogenic.    Its  trophozoites  measure  13 
to  19  by  8  to  11  |i  with  a  mean  of  16  by  9^t . 
The  median  bodies  are  curved  bars  re- 
sembling the  claws  of  a  claw-hammer;  th 
they  lie  transversely  across  the  body. 
The  cysts  contain  2  to  4  nuclei. 

Giardia  simoni  Lavier,   1924  occurs 
in  the  anterior  small  intestine  of  the  Nor- 
way rat,  golden  hamster  and  probably 
various  wild  rodents.     Its  trophozoites 
measure  11  to  19  by  5  to  11  jj,.    Its  median 
bodies  are  curved  bars  of  the  duudenalis 
type. 

G.  7nuris  (Grassi,   1879)  occurs  in 
the  anterior  small  intestine  of  the  house 
mouse,   Norway  rat,  black  rat,   golden 
hamster  and  various  wild  rodents.    It  is 
common  in  laboratory  rats  and  mice.     Its 
trophozoites  measure  7  to  13  by  5  to  I0\i. 
Its  median  bodies  are  small  and  rounded. 

G.   curiae  Hegner,   1923  occurs  in  the 
anterior  small  intestine  of  the  guinea  pig. 
Its  trophozoites  measure  8  to  15  by  6.  5 
to  lOfi.     Its  median  bodies  are  curved 
bars  of  the  duodenalis  type. 

Giardia  chinchillae  Filice,   1952 
emend,   (syn.  ,  Giardia  duodenalis  race 
chinchillae  Morgan,   1949  of  Filice,   1952; 
altho  he  gave  the  first  description  of  this 
form,   Morgan  did  not  give  it  a  specific 
name;  the  name  chinchillae  vfas  intro- 
duced by  Filice)  occurs  frequently  in  the 
chinchilla.     It  is  found  thruout  the  small 
intestine,  but  more  commonly  in  the  duo- 
denum and  anterior  jejunum.    Its  troph- 
ozoites measure  11  to  20  by  6  to  12  j:i  . 
Its  median  bodies  are  curved  bars  of  the 
duodenalis  type.     This  species  has  been 
accused  by  various  workers  of  causing 
diarrhea  and  even  death  (Shelton,  1954; 
Gorham  and  Farrell,   1955).     Treatment 
with  6  to  9  mg  quinacrine  for  5  to  7  days 


was  found  by  Hagan  (1950)  to  eliminate  the 
infection.     Attempts  to  transmit  G.   chin- 
chillae to  the  golden  hamster,  white  mouse, 
domestic  rabbit  or  guinea  pig  have  been  un- 
successful (Morgan,   1949;  Shelton,   1954). 


Genus  TREPOfAONAS  Dujardin,  1841 

These  are  free-swimming  protozoa 
with  a  more  or  less  rounded,  bilaterally 
symmetrical  body  and  with  a  cytostomal 
groove  on  each  side  of  the  posterior  half. 
There  are  8  flagella,  of  which  1  long  and 
3  short  ones  are  present  on  each  side.     A 
horseshoe-shaped  structure  near  the  an- 
terior margin  contains  the  2  nuclei.     Mem- 
bers of  this  genus  are  free-living  in  fresh 
water,  coprophilic  or  parasitic  in  am- 
phibia, fish  and  turtles. 

Trepomonas  agilis  Dujardin,   1841 
occurs  in  stagnant  water  and  the  intestine 
of  amphibia  and  is  also  coprophilic.     It  is 
7  to  25jj.  long  and  2  to  15|i  wide,  with  a 
flattened  body  and  with  the  posterior  end 
wider  than  the  rounded  anterior  end.     The 
flagella  come  off  near  the  middle  of  the 
body  at  the  anterior  end  of  the  cytostome. 


ORDER    PROTOMASTIGORIDA 

Members  of  this  order  have  1  or  2 
flagella. 


FAMILY   BODONIDAE 

Members  of  this  family  have  2  fla- 
gella which  originate  anteriorly;  one  is 
directed  anteriorly  and  the  other  poster- 
iorly.    The  anterior  end  is  more  or  less 
drawn  out.     There  are  1  to  several  con- 
tractile vacuoles.    There  are  several  gen- 
era of  free-living  and  parasitic  forms  in 
this  family. 


Genus  BODO  Stein,    1875 

These  are  small,  more  or  less  ovoid, 
plastic  forms  with  an  anterior  cytostome 
and  a  central  or  anterior  nucleus.    Cysts 
are  forme'd. 


OTHER   FLAGELLATES 


123 


Bodo  caudatus  (Dujardin,   1841)  Stein, 
1878  is  a  common  coprophilic  form  and 
also  occurs  in  stale  urine  and  stagnant 
water.    It  is  8  to  18;U  long  and  2.  5  to  6)ll 
wide,  with  a  polymorphic  body  ranging  in 
shape  from  spherical  to  elongate  ovoid. 
It  has  a  tiny  contractile  vacuole,  a  single 
vesicular  nucleus  with  a  large  endosome 
and  a  rounded  parabasal  body.    This  spe- 
cies and  also  B.  foetus  and  B.glissans 
have  been  found  in  material  from  bulls 
submitted  for  TritricIiouw>ias  foetus  diag- 
nosis. 


Genus  CBRCOMONAS  Dujardin,  1841 

These  are  small  forms  with  a  plastic 
body,  one  flagellum  directed  anteriorly 
and  the  other  running  backward  over  the 
body  to  become  a  trailing  flagellum.     The 
nucleus  is  piriform  and  is  connected  with 
the  basal  granule  of  the  flagella.    The 
cysts  are  spherical  and  uninucleate.    A 
number  of  freshwater  and  coprophilic 
species  have  been  described,  but  it  is  not 
clear  whether  all  the  species  are  valid. 

Cercomonas  longicauda  Dujardin, 
1841  is  a  common  coprophilic  flagellate. 
Its  trophozoites  are  amoeboid,  2  to  15 /j. 
long,  have  2  contractile  vacuoles,  and 
ingest  food  by  means  of  pseudopods.    Its 
cysts  are  4  to  7jj,  in  diameter. 

Cercomonas  heimi  (Hollande)  is  sim- 
ilar to  C.  longicauda  but  is  piriform  and 
has  longer  flagella. 

Cercomonas  equi  (Sabrazes  and  Mur- 
atet,  1908)  (syn. ,   C.  asini)  was  described 
from  the  large  intestine  of  the  horse  and 
donkey  and  also  occurs  in  their  feces. 


coprophilic.     It  has  been  found  in  material 
from  bulls  submitted  for  examination  for 
Tritrichomonas  foetus  (Morgan  and  Haw- 
kins,  1952).    Its  trophozoites  measure  10 
to  16  by  7  to  10 /ix. 


Fig.  19.      Coprophilic  flagellates.     A.    Cer- 
comonas sp.  X  4200.     B.     Copro- 
nionas  subtilis.     X  5100. 
C.   Moiias   sp.  X  4200.     (From 
Noble,   1956) 

Noble  (1956)  found  Cercomonas  sp. 
in  fresh  bovine  and  porcine  feces,  and 
cultivated  them  in  feces  in  the  refrigerator 
at  4°  C  for  5  months.     Noble  (1958)  found 
that  Cerco»io)ms  sp.  appeared  in  fecal 
specimens  from  Wyoming  elk,  bison,   cat- 
tle, horses  and  sheep  after  storage  at  4°C 
for  6  to  7  days.     They  persisted  for  sev- 
eral weeks  and  then  died  out.    They  failed 
to  survive  in  soil  alone  or  in  soil  mixed 
with  boiled  feces,  nor  could  they  be  found 
in  soil  samples  taken  from  areas  where 
elk,   sheep  or  horses  were  present.     Noble 
concluded  that  this  and  other  coprophilic 
protozoa  may  require  certain  essential 
metabolites  produced  by  bacteria. 


Cercomonas  faecicola  (Woodcock  and 
Lapage,   1915)  (syn.,  Helkesimastix fae- 
cicola) was  found  in  the  feces  of  the  goat. 
It  is  ovoid,  with  a  rigid,   pointed  anterior 
end.     The  anterior  flagellum  is  very  short 
and  easily  overlooked.     The  trophozoites 
are  4  to  6jLt  long  and  the  cysts  3  to  3.  5 /i 
in  diameter. 

Cercomonas  crassicauda  Dujardin, 
1841  occurs  in  fresh  water  and  is  also 


The  Cercomonas  sp.  trophozoites  ob- 
served by  Noble  (1958)  were  5.  4  by  2.  5jj,, 
somewhat  tadpole-shaped,  with  a  broad 
anterior  end  tapering  to  a  highly  flexible 
tail-like  posterior  end.    An  extremely 
short  anterior  flagellum,  visible  only  with 
phase  contrast,  extended  from  a  minute 
subterminal  cytostome.    Another  flagellum 
arose  from  the  anterior  region,  passed 
thru  the  cytoplasm  ventral  to  the  nucleus, 
emerged  about  2/3  of  the  body  length  from 


124 


OTHER   FLAGELLATES 


the  anterior  end,  and  continued  as  a  long 
trailing  whip.    Eight  to  10  large,  dark 
cytoplasmic  granules  were  arranged  along 
this  flagellum.     The  cytoplasm  contained 
a  large  contractile  vacuole  and  many  food 
vacuoles.    The  nucleus  was  vesicular. 


Genus  PLEUROMONAS  Perty,  1852 

The  body  is  somewhat  amoeboid. 
The  2  flagella  often  appear  to  emerge 
separately  from  the  body.     The  anterior 
flagellum  is  very  short  and  often  rolled 
up  into  a  ring.     The  posterior  flagellum 
is  very  thick  and  more  than  2  to  3  times 
the  length  of  the  body.    There  is  a  single 
vesicular  nucleus.    The  cyst  is  spherical, 
and  4  to  8  young  individuals  apparently 
emerge  from  it. 

There  is  a  single  species  in  this 
genus,  Pleuromonas  jacidans  Perty,  1852, 
which  occurs  in  stagnant  water.     It  is  6  to 
lOfi  long  and  about  Sfi  wide.     Uribe(1921) 
found  large  numbers  of  this  protozoon  in 
the  ceca  of  young  chickens  which  he  had 
fed  Heterakis  material,  and  believed  that 
it  could  become  adapted  to  parasitism. 


Genus   PROTEROMONAS 
Kunstler,    1883 

The  body  is  spindle-shaped.    An  an- 
terior and  a  free  trailing  flagellum  arise 
from  2  blepharoplasts  at  the  anterior  end. 
The  nucleus  is  anterior  to  the  middle  of 
the  body  and  contains  scattered  chromatin 
granules  but  no  endosome.    A  rhizoplast 
runs  from  the  blepharoplast  to  a  centro- 
some  on  the  nuclear  membrane.    A  peri- 
rhizoplastic  ring  surrounds  the  rhizoplast 
a  short  distance  behind  the  blepharoplast; 
this  is  considered  a  parabasal  body.    A 
paranuclear  body  the  same  size  as  the 
nucleus  lies  beside  the  nucleus;  it  divides 
when  the  nucleus  divides,  and  stains  with 
hematoxylin  but  not  with  protargol.    All 
the  species  are  parasitic.     They  are  com- 
mon in  the  intestines  of  reptiles  and  am- 
phibia.   Synonyms  of  this  genus  are 
Prowazekella  Alexeieff,  1912  and  Sc/ii2o- 
bodo  Chatton,  1917. 


Proteromonas  brevifilia  Alexeieff, 
1946  occurs  in  the  cecum  of  the  guinea 
pig- 


FAMILY   AMPHIMONADIDAE 

Members  of  this  family  have  a  naked 
or  loricate  body  with  2  equal  flagella. 
There  are  several  genera,  mainly  in  fresh 
water. 


Genus  SPIROMONAS  Perty,   1914 

Members  of  this  genus  have  an  elon- 
gate, spirally  twisted  body  with  2  anterior 
flagella.    They  form  spherical  cysts  in 
which  division  into  4  daughter  individuals 
takes  place.    They  live  in  fresh  water.    A 
synonym  is  Alphanwnas  Alexeieff. 

Spiromonas  miffusta  (Dujardin)  Alex- 
eieff lives  in  stagnant  water  or  is  copro- 
philic.     It  has  also  been  found  in  bull 
sheath  washings.    It  is  spindle-shaped  and 
about  lOfi  long. 


SUBCLASS  PHYTOMASTIGASINA 

Members  of  this  subclass  typically 
have  chromatophores  and  holophytic  nu- 
trition.   Some  are  colorless  but  closely 
resemble  other  holophytic  forms  and  are 
derived  from  them  or  from  a  common 
ancestor.    A  few  are  coprophilic  and  still 
fewer  are  parasitic.    In  each  group  the 
parasitic  mode  of  life  has  undoubtedly 
arisen  anew. 

ORDER   CHRYSOMONADORIDA 

In  this  order  the  chromatophores,  if 
present,  are  yellow,  brown,  orange  or 
occasionally  blue.     The  stored  reserves 
include  leucosin  (presumably  a  polysac- 
charide) and  lipids,  but  no  starch.     There 
are  five  suborders  in  the  Chrysomonador- 
ida,  but  only  one  of  them,   Euchrysomon- 
adorina,  contains  forms  of  veterinary  or 
medical  interest.     In  this  suborder  the 
flagellate  stage  is  dominant,  and  neither 
a  siliceous  skeleton  nor  a  peripheral  zone 


OTHER   FLAGELLATES 


125 


of  coccoliths  is  present.     This  suborder 
contains  4  families,   2  of  which  contain 
parasitic  or  coprophilic  species. 


FAMILY  CHROMULINIDAE 

Members  of  this  family  have  a  single 
flagellum. 


Genus  OIKOMONAS  Kent,   1880 

Members  of  this  genus  lack  chromato- 
phores,  lorica  or  test.     They  are  solitary. 
The  nucleus  is  near  the  center  of  the  body. 
The  single  flagellum  arises  from  a  basal 
granule  near  the  body  surface.     Cysts  are 
formed,  at  least  in  the  free-living  species. 
This  genus  is  the  colorless  homolog  of 
Chroninlina.    Its  parasitic  species  are 
poorly  known. 

Oikomonas  communis  Liebetanz, 
1910  and  Oikomonas  mini)>ia  Liebetanz, 
1910  were  both  described  from  the  rumen 
of  cattle.    They  are  said  to  differ  in  size, 
the  former  being  up  to  11  /i  long  and  the 
latter  more  than  4(i  long;  this  is  probably 
not  a  valid  difference.    Das  Gupta  (1935) 
found  0.  communis  in  the  rumen  of  goats 
in  India. 

Oikomonas  equi  Hsiung,   1930  was 
found  in  the  cecum  of  8  horses  in  Iowa. 
It  is  usually  spherical  or  ovoid  and  swims 
in  a  jerky  manner.    The  nucleus  has  a 
large,  central  endosome  and  the  cytoplasm 
is  filled  with  small,  dark-staining  gran- 
ules.   The  body  is  3.  5  to  1  [i  long  and  3  to 
5.  5/1  wide.    The  flagellum  is  about  20 /i 
long. 


Genus  SPHAIROMONAS 
Liebetanz,   1910 

The  body  is  spherical  or  ellipsoidal, 
with  a  more  or  less  central  nucleus.    A 
single,  long  flagellum  arises  from  a  basal 
granule  on  the  nuclear  membrane.     This 
genus  is  poorly  known  and  has  apparently 
not  been  studied  by  modern  methods.    It 
is  closely  related  to  Oikomonas  and  may 
even  be  a  synonym  of  that  genus.    Several 


species  have  been  named,  all  parasitic, 
but  most  of  them  are  probably  the  same. 

Sphaeromonas  communis  Liebetanz, 
1910  (syns.  ,  S.  minima,  S.  maxima,   S. 
liebeta)izi,  S.  rossica)  occurs  in  the  rumen 
of  the  ox  and  goat  and  in  the  cecum  and 
feces  of  the  guinea  pig.    It  may  also  be 
coprophilic.     Liebetanz  (1910)  and  Braune 
(1914)  found  it  in  the  rumen  of  cattle  in 
Europe,   Becker  and  Talbott  (1927)  found 
it  in  the  rumen  of  a  few  cattle  in  Iowa 
(calling  it,   however,   Monas  communis), 
and  Fonseca  (1916)  found  it  in  cattle  and 
goats  and  also  in  the  guinea  pig  in  Brazil. 
Yakimoff  et  al.   (1921)  found  it  in  the 
guinea  pig  in  Russia.    The  body  is  spher- 
ical or  ellipsoidal,  3  to  Mfi  in  diameter. 
The  cytoplasm  contains  many  dark-staining 
granules. 


Genus  CAVIOMONAS  Nie,  1950 

The  body  is  naked,  without  chromato- 
phores  and  with  a  vesicular  nucleus  at  the 
anterior  end.    One  flagellum  arises  from 
the  nuclear  membrane.    A  band-like  peri- 
style arises  from  the  nuclear  membrane 
opposite  to  the  origin  of  the  flagellum  and 
extends  posteriorly  along  the  periphery  of 
the  body  surface;  it  stains  with  hematoxylin 
and  protargol.    Cytostome  and  contractile 
vacuoles  are  absent. 

Caviomonas  mobilis  Nie,  1950  occurs 
in  the  cecum  of  the  guinea  pig.    The  body 
is  ovoid  to  elongate  carrot-shaped  and  the 
posterior  end  is  often  pointed.    It  measures 
2  to  7  by  2  to  3  n  with  a  mean  of  4  by  3  /j. . 


FAMILY   OCHROMONADIDAE 

Members  of  this  family  have  1  long 
and  1  short  flagellum. 


Genus  MONAS  Muller,  1773 

The  body  is  active  and  plastic.    Chrom- 
atophores  are  absent.    This  genus  is  the 
colorless  homolog  of  Ochromonas .     Reyn- 
olds (1934)  recognized  13  free-living  spe- 
cies, and  in  addition  there  is  at  least  1 
coprophilic  one. 


126 


OTHER  FLAGELLATES 


Noble  (1956)  cultivated  Monas  sp.   in 
bovine  feces  at  4"  C  in  the  refrigerator 
for  5  months.     He  also  (1958)  found  that 
Motias  sp.  appeared  in  fecal  samples  from 
Wyoming  elk,  bison  and  bear  after  storage 
at  4°  C  for  7  to  27  days.     The  protozoa 
persisted  for  several  weeks  and  then  died 
out.     They  failed  to  survive  in  soil  or  in 
soil  mixed  with  boiled  feces,  nor  could 
they  be  found  in  soil  samples  taken  from 
areas  whei-e  elk,  sheep  or  horses  were 
present.     Noble  concluded  that  this  and 
other  coprophilic  protozoa  may  require 
certain  essential  metabolites  produced  by 
bacteria.     The  form  which  Noble  studied 
was  spherical  and  4(i  in  diameter.     He 
assigned  it  to  the  "Moiias  coiiininnis"  re- 
ported by  Becker  and  Talbott  (1927)  from 
the  rumen  of  cattle,  but  the  latter  had 
only  a  single  flagellum  and  was  Spliaeyo- 
ntuiias  co>iii)iH)iis. 

Moiias  obliqua  Schewiakoff  has  been 
found  in  material  from  bulls  submitted 
for  Trilricliomonas  foetus  diagnosis 
(Morgan  and  Hawkins,   1952). 


ORDER    EUGLENORIDA 

In  this  order  the  chromatophores,  if 
present,  are  green.     The  stored  reserves 
include  lipids  and  paramylum.     There  is 
a  reservoir  or  "gullet"  from  the  posterior 
or  postero-dorsal  wall  of  which  the  fla- 
gella  arise.     There  are  3  suborders  in  the 
Euglenorida,  of  which  the  Euglenorina  in- 
cludes one  genus  containing  coprophilic 
forms. 


nucleus  is  vesicular,  with  a  large  endo- 
some.     Permanent  fusion  followed  by  en- 
cystment  takes  place.    Nutrition  is  holo- 
zoic  on  bacteria. 

Copromonas  subtilis  Dobell,  1908 
(syn.  ,  Copromonas  ruminantium)  was  first 
described  from  the  feces  of  frogs  and 
toads,  but  has  since  been  found  in  the  feces 
of  man  and  various  domestic  and  wild  mam- 
mals,   Wenyon  (1926)  and  Noble  (1956) 
found  it  in  pig  feces.    Woodcock  (1916) 
found  it  in  goat  feces.     Noble  (1958)  found 
that  it  appeared  in  fecal  samples  from 
Wyoming  elk,  bison,  cattle,   horses,   sheep 
and  moose  after  storage  at  4 '  C  for  7  to  11 
days.    It  persisted  from  2.  5  months  in  the 
bison  samples  to  more  than  18  to  24  months 
in  the  elk  and  cattle  samples.    It  failed  to 
survive  in  soil  or  in  soil  mixed  with  boiled 
feces,  nor  could  it  be  found  in  soil  samples 
taken  from  areas  where  elk,   sheep  or 
horses  were  present. 

The  trophozoites  of  C.   subtilis  are  7 
to  20  (i  long.     They  are  usually  ovoid,  but 
can  change  from  spindle-shaped  to  almost 
round.     The  flagellum  is  1  to  2  times  the 
length  of  the  body.    When  the  animal 
swims  straight,  only  the  tip  of  the  flagellum 
moves;  the  flagellum  is  sometimes  used 
like  a  highly  flexible  probe.     The  cysts  are 
ovoid  or  spherical  and  7  to  8)j.  long.     They 
have  a  thin  wall  and  clear  contents  with  a 
single  vesicular  nucleus. 

Reichenow  (1952)  and  Grasse'  (1952) 
considered  that  Copromonas  subtilis  is  a 
synonym  of  Scytomoiias  piisilla  Stein,  1878, 
which  was  incompletely  described  by  Stein. 


FAMILY   ASTASilDAE 

Members  of  this  family  have  a  single 
flagellum.  They  lack  chromatophores  or 
a  stigma. 


Genus  COPROMONAS  Dobell,   1908 

The  body  is  elongate  ovoid,  with  an 
elongate  reservoir  at  the  anterior  end  into 
which  a  contractile  vacuole  discharges. 
The  single  flagellum  arises  from  a  bleph- 
aroplast  at  the  base  of  the  reservoir.    The 


ORDER    PHYTOMONADORIDA 

In  this  order  a  single  large  green 
chromatophore  is  typical.    The  stored  re- 
serves are  starch  and  sometimes  lipids. 
No  members  of  this  order  are  parasites  of 
domestic  animals  or  man,  but  one  species 
deserves  mention. 

Polytoma  uvellaEhrenberg,  1838 
occurs  in  infusions  and  stagnant  water, 
and  has  been  found  in  bull  sheath  washings 
submitted  for  Tritrichomonas  foetus 


OTHER   FLAGELLATES 


127 


diagnosis  (Morgan  and  Hawkins,   1952). 
Its  body  is  ovoid  to  piriform,   15  to  30  by 
9  to  20  |i,  without  chromatophores  and 
with  numerous  starch  granules  in  the 
posterior  part  of  the  body.    A  red  or  pink 
stigma  may  or  may  not  be  present.    There 
are  2  anterior  flagella  of  equal  length. 

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The  amoebae  belong  to  the  class  Sar- 
codasida.    Members  of  this  class  move  by 
means  of  pseudopods.     They  have  no  cilia 
and,  except  in  rare  instances,  no  flagella. 
The  group  is  named  for  sarcode,  a  term 
introduced  by  Dujardin  for  what  was  later 
called  protoplasm.    Most  sarcodasids  are 
holozoic,  ingesting  their  prey  by  means 
of  their  pseudopods.    Their  cytoplasm  is 
usually  divided  into  endoplasm,  containing 
the  food  vacuoles,  nucleus,  etc.,  and  rel- 
atively clear  ectoplasm.    The  fresh  water 
forms  contain  one  or  more  contractile 
vacuoles;  these  are  absent  in  the  salt  water 
and  parasitic  species.    With  a  few  excep- 
tions,  reproduction  is  asexual,  by  binary 
fission  or  rarely  by  multiple  fission,  by 
budding  or  by  plasmotomy.     Most  species 
form  cysts. 

The  Sarcodasida  originated  from  the 
Mastigasida.     The  group  did  not  arise 
from  a  single  progenitor,  but  is  polyphyle- 
tic.    One  line,  for  example,  passes  from 
Tetramitus  thru  Naegleria  to  Vahlkampfia. 
In  Tetramitus,  which  is  usually  classified 
among  the  flagellates,  the  life  cycle  in- 
cludes flagellate  and  amoeboid  stages, 
and  the  flagellate  stage  has  a  permanent 
cytostome.    In  Naegleria,  which  is  usually 
classified  among  the  amoebae,  the  life 
cycle  also  includes  flagellate  and  amoeboid 
stages,  but  there  is  no  permanent  cyto- 
stome.   In  Vahlkampfia,  there  is  no  fla- 
gellate stage,  but  the  amoebae  are  very 
similar  to  those  of  Naegleria.    Another 
line  passes  from  the  amoeboid  flagellate, 
Histomonas,  to  the  very  similar  but  non- 
flagellate  amoeba,  Dientamoeba. 

Only  a  few  of  the  Sarcodasida  are 
parasitic.    The  free-living  forms  include 
the  most  beautiful  protozoa  of  all,  the 
pelagic  Radiolaria  with  their  delicate, 
latticework  siliceous  skeletons.    One 
group  of  Radiolaria  has  skeletons  of  stron- 
tium sulfate- -perhaps  some  day  proto- 
zoologists  will  be  asked  to  develop  ways 
of  using  them  to  eliminate  strontium  90 
pollution.    Another  marine  group,  the 
Foraminifera,  has  calcareous  shells. 


Chapter  7 


THE 
AMOEBAE 


129  - 


130 


THE  AMOEBAE 


Their  skeletons  form  our  chalk,  and  they 
and  the  Radiolaria  are  of  great  geological 
interest.     They  are  used,  too,  as  indica- 
tors in  oil  well  drilling.     More  species  of 
Foraminifera  have  probably  been  named 
than  of  all  the  other  protozoa  put  together; 
493  new  species  and  53  new  genera  of 
Foraminifera  were  listed  in  the  Zoological 
Record  for  1956,  and  of  these,  470  species 
and  48  genera  were  fossil.    In  contrast,  57 
new  species  and  4  new  genera  of  parasitic 
protozoa  were  listed.     And  this  was  not  an 
exceptional  year. 


ORDER   AMOEBORIDA 

Members  of  this  order  have  lobopodia 
and  are  naked,  without  a  test.     All  of  the 
parasitic  and  all  but  one  of  the  coprophilic 
Sarcodasida  are  found  in  this  order. 


FAMILY    NAEGLERIIDAE 

This  family  is  transitional  between 
the  Mastigasida  and  the  Sarcodasida. 
Both  amoeboid  and  flagellate  stages  occur 
in  its  life  cycle. 


ORDER   TESTACEORIDA 

Members  of  this  order  have  a  single- 
chambered  shell  or  test. 


FAMILY   ARCELLIDAE 

The  test  is  simple  and  membranous, 
without  foreign  bodies,  platelets  or  scales. 
The  pseudopods  are  filose  or  simply 
branched  and  do  not  anastomose.     There 
are  many  genera  and  species  of  free-living 
protozoa  in  this  family.     They  are  found 
commonly  in  fresh  water,  swamps,  etc. 
One  species  is  coprophilic. 


Genus  CHLAMYDOPHRYS 
Cienkowski,    1876 

The  test  is  rigid  and  circular  in  cross 
section.     The  nucleus  is  vesicular,  with  a 
prominent  endosome.    The  cytoplasm  is 
differentiated  into  distinct  zones,  and  re- 
fractile  waste  granules  are  present  in  it. 
The  pseudopods  are  branching. 

Chlamydophrys  slercorea  Cienkowski, 
1876  has  an  oval,  white  porcelaneous,  thin, 
smooth  shell  open  at  the  pointed  end.    It 
measures  about  20  by  14 /i.     The  pseudo- 
pods are  filose.    Somewhat  smaller  naked 
amoebae  may  also  be  seen.    The  cysts  are 
uninucleate,   12  to  l'b\i  in  diameter,  with 
thick,  irregular,  brownish  walls.     Multi- 
plication is  by  budding.     C.   slercorea  is 
coprophilic  and  may  also  be  found  in  fresh 
water. 


Genus    NAEGLERIA   Alexeieff, 
1912  emend.  Calkins,  1913 

The  flagellate  stage  has  2  flagella. 
The  amoeboid  stage  has  lobopodia  and  re- 
sembles Vahlkanipfia.     The  nucleus  is 
vesicular,  with  a  large  endosome.     The 
contractile  vacuole  is  conspicuous.     The 
cysts  are  uninucleate.    Naegleria  lives  on 
bacteria  and  is  free-living  in  stagnant 
water  or  coprophilic. 

Naegleria  gruberi  (Schardinger)  (syn. , 
Dimasligamoeba  gruberi)  is  found  in  stag- 
nant water  and  is  also  coprophilic.     The 
active  amoebae  are  10  to  36  by  8  to  18  p. 
and  have  a  single  vesicular  nucleus  3  to 
4fj,  in  diameter.     The  nucleus  has  a  cen- 
tral endosome  and  sparse  granules  of 
peripheral  chromatin.     The  flagellate  stage 
is  18  by  9  (i,  ovoid,  and  has  2  equal  anter- 
ior flagella.    It  can  be  produced  from  the 
amoeboid  stage  by  flooding  the  culture  with 
distilled  water  and  exposing  it  to  air.     The 
cysts  are  spherical,   8  to  12 /i  in  diameter, 
translucent,  with  a  single  nucleus  and  sev- 
eral large  spherical  chromatoid  bodies 
when  first  formed.     The  cyst  wall  is  double, 
and  the  outer  wall  is  perforated  by  3  to  8 
pores. 


Genus  TRIMASTIGAMOEBA 
Whitmore,   1911 

The  nucleus  is  vesicular,  with  a  large 
endosome.  The  flagellate  stage  has  3  fla- 
gella (4  according  to  Bovee,  1959)  and  the 


THE  AMOEBAE 


131 


amoeboid  stage  is  relatively  small.    The 
cysts  are  uninucleate,  with  a  smooth  wall. 

Triiuastigamoeba  philippinensis  Whit- 
more,   1911  was  first  found  in  human 
feces.     Bovee  (1959)  rediscovered  it  in 
sewage-seepage  into  a  spring  in  Florida 
and  redescribed  it.     According  to  Whit- 
more  (1911),  the  flagellate  stage  has  3 
(occasionally  2  or  4)  anterior  flagella  and 
measures  16  to  22  by  6  to  8  j:i  .     Bovee, 
however,  found  that  there  are  actually  4 
anterior  flagella  which  arise  in  pairs  from 
2  basal  granules  adjacent  to  the  nucleus. 
The  flagella  lie  in  an  anterior,  gullet-like, 
cylindrical  invagination  and  extend  20  to 
25 [x  beyond  it.    According  to  Bovee,  the 
fully  formed  flagellate  stage  is  17  to  20  |i 
long,  its  larger  rear  end  is  6.  5  to  7.  5  ji 
in  diameter,  the  narrower  anterior  end 
is  4.  5  to  5.  5|U  in  diameter  and  the  anter- 
ior pocket  is  1  ji  deep. 

The  amoeboid  stage  was  said  by 
Whitmore  (1911)  to  be  16  to  18 ii  in  diam- 
eter.    Bovee  (1959)  said  that  it  is  12  to 
18fi  in  diameter  when  at  rest  and  30  to 
40 (i  long  and  14  to  20  )i  wide  during  rapid 
locomotion.    It  moves  quickly  by  means 
of  rapidly-extruded  eruptive  waves  at  its 
frontal  margin.    It  feeds  principally  on 
bacteria  and  has  a  contractile  vacuole 
which  is  formed  by  the  union  of  several 
small  vacuoles  in  about  2  minutes.     The 
cysts  are  oval  to  subspherical.    Whitmore 
(1911)  gave  their  dimensions  as  13  to  14 
by  8  to  12  fi. 


FAMILY   AMOEBIDAE 

Members  of  this  family  are  free-living 
or  coprophilic.    They  have  no  flagellate 
phase.     This  family  contains,  besides 
Amoeba  and  a  number  of  other  free-living 
genera,  several  coprophilic  species  and 
one  which  can  produce  disease  with  a  little 
human  help. 


Genus  ACANTHAMOEBA 
Volkonsky,  1931 

These  are  relatively  small  amoebae 
without  well  developed  ectoplasm.    The 
nucleus  is  vesicular,  with  a  large  endo- 


some.    During  mitosis,  the  nuclear  mem- 
brane disappears  at  prophase.     The  mi- 
totic figure  at  the  end  of  metaphase  is  a 
straight  or  concave  spindle  with  sharply 
pointed  poles.     The  cysts  are  angular  and 
polyhedric,  with  2  membranes,  the  outer 
one  being  highly  wrinkled  and  mammillated. 

Acanthamoeba  hyalina  (Dobell  and 
O'Connor,   1921)  Volkonsky,   1931  (syn. , 
Hartnianiiella  hyalina)  is  a  common  copro- 
philic form.     It  occurs  in  soil  and  fresh 
water  and  is  easily  cultivated  from  old 
human  and  animal  feces.    Its  trophozoites 
are  9  to  17  fi  in  diameter  when  rounded. 
It  has  a  single  contractile  vacuole  and  a 
single  vesicular  nucleus  with  a  central 
endosome  and  peripheral  chromatin.     The 
cysts  are  spherical,  10  to  15fi  in  diam- 
eter, with  a  thin,  smooth  inner  wail  and 
a  thick,  wrinkled,  brownish  outer  wall. 

Walker  (1908)  described  an  amoeba 
from  the  intestinal  tract  of  the  turkey  in 
Massachusetts  under  the  name  A»ieba 
gallopavoiiis  which  Chatton  (1953)  listed 
as  Acanthamoeba  gallopavonis  Walker. 
It  had  angular  cysts  and  may  be  synony- 
mous with  A.   hyalina. 

Acanthamoeba  has  occasionally  been 
encountered  as  a  contaminant  of  tissue 
cultures  and,  because  of  its  pathogenicity 
on  injection  and  the  resistance  of  its  cysts 
to  virucidal  agents,  it  is  a  potential  haz- 
ard in  vaccines  prepared  from  viruses 
grown  in  tissue  culture. 

Jahnes,   Fullmer,  and  Li  (1957)  and 
Culbertson,  Smith  and  Minner  (1958) 
isolated  an  Acanthamoeba  sp.  from  tissue 
cultures  of  trypsinized  monkey  kidney 
cells.     The  latter  first  recognized  the 
amoebae  in  the  lesions  of  monkeys  which 
had  died  following  inoculation  of  tissue 
culture  fluid  thought  to  contain  an  unknown 
virus  but  later  shown  to  contain  only 
Acanthamoeba.     Following  intracerebral 
and  intraspinal  inoculation  into  cortison- 
ized  monkeys,  the  amoebae  caused  ex- 
tensive choriomeningitis,  destructive 
encephalomyelitis  and  death  in  4  to  7  days. 
Following  intracerebral  inoculation  into 
mice,  they  caused  destructive  encepha- 
litis and  death  in  3  to  4  days.     Following 
intranasal  instillation  into  mice,  they 


132 


THE  AMOEBAE 


produced  ulcers  in  the  nasal  mucous  mem- 
brane and  invaded  the  adjacent  base  of  the 
skull,  involving  the  frontal  lobes  of  the 
brain  and  causing  death  in  about  4  days. 
Following  intravenous  inoculation  into 
mice,  they  caused  perivascular  granulo- 
matous lesions  in  the  lungs.     These  were 
associated  with  severe  pneumonia,  exten- 
sive fibrinopurulent  exudate  containing 
polymorphonuclear  leucocytes  and  mono- 
cytes,  hemorrhage,  and  invasion  of  the 
pulmonary  veins  followed  by  the  formation 
of  thrombi  containing  the  amoebae. 

McCowen  and  Galloway  (1959)  also 
isolated  Acanlhamoeba  sp.  from  tissue 
cultures  of  trypsinized  monkey  kidney 
cells.    They  studied  the  pathogenicity  for 
mice  of  this  strain  and  of  others  isolated 
from  the  same  source.     The  average  sur- 
vival time  of  intracerebrally  inoculated 
mice  was  approximately  5  days.    Cysts 
remained  virulent  for  mice  after  storage 
at  -67  °C  for  15  months. 


Genus  SAPPINIA  Dangeard,   1896 

In  this  genus  the  trophozoites  have  2 
closely  associated  nuclei  with  large  endo- 
somes.    The  cysts  are  binucleate  also. 

Sappinia  diploidea  (Hartmann  and 
Nagler,  1908)  Alexeieff,  1912  is  a  com- 
mon coprophilic  amoeba  in  the  feces  of 
man  and  other  animals.    Its  trophozoites 
are  10  to  60  fi  long,  with  a  thick,  smooth, 
hyaline  pellicle;  according  to  Noble  (1958), 
the  ectoplasm  has  fine  lines  sometimes 
resembling  wrinkles  in  cellophane.    Two 
nuclei  are  present,  usually  pressed 
tightly  together.     Each  nucleus  has  a 
large  endosome  and  frequently  a  crescentic 
mass  of  granules  between  the  endosome 
and  the  nuclear  membrane.    The  cytoplasm 
is  usually  filled  with  many  food  vacuoles. 
A  contractile  vacuole  is  present,  formed 
by  the  enlargement  and  coalescence  of 
smaller  vacuoles.    A  single,  clear,  broad 
pseudopod  is  characteristic,  altho  occa- 
sionally many  pseudopods  may  be  present. 
Cytoplasmic  granules  and  food  vacuoles 
are  concentrated  between  the  pseudopod 
and  the  rest  of  the  body.    Movement  is 
quite  sluggish.    The  cytoplasmic  granules 


usually  move  rapidly.    The  cysts  are  typ- 
ically binucleate,  12  to  18/i  or  more  in 
diameter,  with  thick,  uniform  walls.    The 
cysts  are  formed  from  2  individuals  which 
come  together  and  secrete  a  common  cyst 
wall;  their  nuclei  fuse  so  that  each  one  has 
a  single  nucleus,  their  cytoplasm  fuses, 
each  nucleus  gives  off  reduction  bodies, 
and  the  2  remaining  nuclei  come  into  con- 
tact to  make  the  cyst  binucleate. 

Noble  (1958)  found  that  6'.  diploidea 
appeared  in  fecal  samples  from  Wyoming 
elk  and  bison  (but  not  from  cattle,   horses 
and  sheep)  after  storage  at  4°  C  for  a  few 
days  to  a  few  weeks.    It  failed  to  survive 
in  soil  or  in  soil  mixed  with  boiled  feces, 
nor  could  it  be  found  in  soil  samples  taken 
from  areas  where  elk,  sheep  or  horses 
were  present. 

S.  diploidea  is  readily  cultivated. 
Noble  (1958),  for  example,  cultivated  it 
both  at  4^^  C  and  at  room  temperature  on 
the  surface  of  agar  plates  containing  1.  5% 
agar,  0.  05%  yeast  extract  and  0.  05%  pep- 
tone.    The  cultures  held  at  room  temper- 
ature became  moldy  after  6  weeks.    Sap- 
pinia was  present  for  2  to  3  weeks  in  the 
cultures  at  4°  C. 

Genus  VAHLK4MPF/A  Chatton  and 

Lalung-Bonnaire,  1912  emend. 

Calkins,  1913 

These  are  small  amoebae  with  a  nu- 
cleus containing  a  large  endosome  and 
peripheral  chromatin,  with  polar  caps 
during  nuclear  division.     The  trophozoites 
have  a  single  broad  pseudopod  and  move 
like  a  slug.    The  cysts  have  a  perforated 
wall.     The  nucleus  of  this  genus  closely 
resembles  that  of  Naegleria,  but  the  latter 
has  both  flagellate  and  amoeboid  stages. 
A  number  of  species  have  been  described 
from  fresh  water,  old  feces,  lower  verte- 
brates and  invertebrates,  but  the  taxonomy, 
nomenclature  and  validity  of  some  of  them 
are  not  certain. 

Vahlkampfia  punctata  (Dangeard,  1910) 
Chatton  and  Lalung-Bonnaire,   1912  has 
been  found  in  human  feces.    Its  cysts  have 
punctate  markings. 


THE  AMOEBAE 


133 


Vahlkanipfia  lobospinosa  (Craig,  1912) 
Craig,   1913  is  another  coprophilic  species. 
Becker  and  Talbott  (1927)  found  it  in  the 
rumen  of  a  cow  in  Iowa.    Its  trophozoites 
are  10  to  24  ju  long.     Its  cysts  have  1  or  2 
nuclei  and  are  7  to  11  (i  in  diameter. 

Noble  (1958)  found  that  Vahlkampfia 
sp.  appeared  in  fecal  samples  from  Wy- 
oming elk,  bison,  cattle,   horses,  sheep, 
moose  and  marmots  after  storage  at  4^  C 
for  a  few  days  to  a  few  weeks.    The  proto- 
zoa persisted  for  several  months.     They 
failed  to  survive  in  soil,  nor  were  they 
present  in  soil  samples  taken  from  areas 
where  elk,  sheep  or  horses  were  present. 
The  trophozoites  were  20  to  40  p.  in  diam- 
eter, with  finely  granular  cytoplasm 
filled  with  food  vacuoles  and  other  parti- 
cles.   A  contractile  vacuole  was  present. 
The  pseudopods  were  broad,  usually  slug- 
gish but  sometimes  formed  almost  explo- 
sively; often  there  was  only  a  single, 
large  pseudopod.    The  nucleus  was  ves- 
icular, with  a  large,  central  endosome 
occasionally  appearing  to  be  composed  of 
several  closely  packed  granules.     Peri- 
pheral chromatin  was  rarely  present, 
altho  a  ring  of  minute  granules  was  often 
present  just  within  the  nuclear  membrane. 
The  cysts  were  8  to  15  in  in  diameter  and 
almost  exclusively  mononucleate.     The 
nucleus  was  different  from  that  of  the 
trophozoite.    Its  central  endosome  was 
usually  smaller  than  in  the  trophozoite 
and  often  composed  of  several  granules, 
and  the  peripheral  chromatin  was  distinct, 
arranged  in  irregular  clumps  and  often 
forming  a  crescent.    A  large  vacuole  and 
irregular  chromatoid  bodies,  many  of 
which  resembled  those  of  Entamoeba  his- 
tolytica, were  present.    Noble  believed 
that  many  of  the  cysts  found  in  animal 
and  human  feces  and  described  as  those 
of  Entamoeba  are  actually  of  the  Vahl- 
kampfia type. 

Noble  (1958)  cultured  this  species  at 
both  4°  C  and  room  temperature  on  the 
surface  of  agar-  plates  containing  1 .  5% 
agar,  0.  05%  yeast  extract  and  0.  05%  pep- 
tone.   The  cultures  held  at  room  temper- 
ature became  moldy  after  6  weeks  and 
were  discarded,  but  Vahlkampfia  was 
present  for  3  months  without  attention  in 
those  held  at  4°  C. 


FAMILY    ENDAMOEBIDAE 

Members  of  this  family  are  parasitic 
in  the  digestive  tract  of  vertebrates  and 
invertebrates.    The  genera  are  differen- 
tiated on  the  basis  of  nuclear  morphology. 
Four  genera  contain  parasites  of  domestic 
animals  and  man,  but  only  two  of  these 
contain  pathogenic  species.    However,  it 
is  important  to  be  able  to  identify  the  var- 
ious species  in  order  to  know  whether  an 
infection  with  a  pathogenic  one  is  present 
or  not. 


Genus  ENTAMOEBA  Casagrandi  and 
Barbagallo,   1895 

The  nucleus  is  vesicular,  with  a  com- 
paratively small  endosome  located  at  or 
near  its  center,  with  or  without  periendo- 
somal  granules  around  the  endosome,  and 
with  a  varying  number  of  granules  around 
the  periphery  of  the  nucleus.    Cysts  are 
formed;  they  contain  1  to  8  nuclei  and  may 
or  may  not  contain  chromatoid  bodies 
(rod-like  bodies  which  stain  with  hema- 
toxylin and  which  are  absorbed  and  dis- 
appear as  the  cysts  mature).    This  genus 
occurs  in  both  vertebrates  and  inverte- 
brates. 

The  name  of  this  genus  was  the  sub- 
ject of  one  of  the  most  famous  taxonomic 
controversies  in  protozoology  (Dobell, 
1938;  Kirby,   1945).     The  genus  Endamoeba 
was  established  by  Leidy  in  1879  for  an 
amoeba  of  the  cockroach,   Endamoebae 
blattae.    In  1895  and  in  ignorance  of  this 
name,  Casagrandi  and  Barbagallo  intro- 
duced the  name  Entamoeba  for  the  human 
amoeba,  E.  coll.     The  nuclei  of  these  two 
forms  are  very  different,  that  of  the  cock- 
roach species  lacking  a  central  endosome. 
Since  the  appearance  of  the  nucleus  is  the 
most  important  differentiating  character 
between  genera  in  this  family,  it  is  ob- 
vious to  a  protozoologist  that  these  forms 
belong  in  different  genera.    However,  the 
first  syllable  of  their  names  is  derived 
from  the  same  Greek  root.    Hence  the  In- 
ternational Commission  of  Zoological 
Nomenclature  was  asked  to  decide  whether 
the  name  that  had  been  given  second 
should  be  changed  to  something  else  (i.e. , 
whether  the  two  names  were  homonyms). 


134 


THE  AMOEBAE 


The  Commission,  which  had  no  protozo- 
ologists  among  its  members,  went  beyond 
this,  and  decided  that  £^^/rt»/0(;^/>f/  was  a 
synonym  of  EiidcDiiueba  and  that  both  pro- 
tozoa belonged  to  the  same  genus.     Altho 
the  latter  is  obviously  not  true,  this  dic- 
tum was  accepted  by  many  protozoologists. 
Finally,  after  much  agitation  and  several 
long,   involved  papers  by  various  author- 
ities, the  International  Commission  finally 
reversed  itself,  and  Enlanioeha  is  now 
universally  recognized  as  the  correct 
name  for  the  species  occurring  in  verte- 
brates. 

The  nomenclature  and  taxonomy  of  the 
species  of  Eiitamoeha  are  about  as  con- 
fused as  it  is  possible  to  make  them. 
Some  of  the  problems  are  explained  below, 
but  puzzle  addicts  are  referred  to  the 
cited  papers  for  the  details. 

Members  of  the  genus  found  in  domes- 
tic animals  and  man  can  be  divided  into  4 
groups  on  the  basis  of  trophozoite  and 
cyst  morphology.    A  fifth  group  includes 
species  about  which  insufficient  morpho- 
logical information  is  available  to  deter- 
mine which  of  the  other  groups  they  belong 
in.     Most  of  the  species  within  each  group 
are  morphologically  indistinguishable; 
they  are  differentiated  on  the  basis  of  size, 
hosts,  pathogenicity,  etc.     Criteria  of 
this  type  are  given  different  weights  by 
different  taxonomists,  and  this  fact  com- 
bined with  a  lack  of  cross-transmission 
studies  for  many  species  accounts  for 
some  of  the  confusion.     More  is  due  to 
the  fact  that  the  original  descriptions  of 
some  of  the  species  were  so  poor  as  to 
make  it  difficult  or  impossible  to  be  sure 
what  forms  the  authors  were  dealing  with. 

The  groups  of  Entamoeba  will  be  des- 
cribed first,  and  then  the  individual  spe- 
cies. 

1.     fflSTOLYTICA  GROUP.      The  nucleus 
has  a  small,  central  endosome,  a 
ring  of  small  peripheral  granules  and 
a  few  scattered  chromatin  granules 
between  them.     The  cysts  have  4  nuclei 
when  mature,  and  their  chromatoid 
bodies  are  rods  with  rounded  ends. 
Glycogen  vacuoles,  when  present  in 


the  cyst,  are  usually  diffuse  and  ill- 
defined. 

Entamoeba  histolytica  of  man,  other 
primates,  the  dog,  cat  and  rarely 
the  pig. 

E)itai)ioeba  harliuauiii  of  man  and  pre- 
sumably also  of  the  other  hosts  of 
E.  histolytica. 

Entamoeba  eqni  of  the  horse. 

Entanioeba  anal  is  of  the  duck. 

Entamoeba  moshkovskii  of  sewage. 

2.  COLI  GROUP.      The  nucleus  has  a 
somewhat  larger,  eccentric  endosome 
than  that  of  the  histolytica  group  and 
has  a  ring  of  coarse  peripheral  gran- 
ules and  some  scattered  chromatin 
granules  between  them.     The  cysts 
have  8  nuclei  when  mature,  and  their 
chromatoid  bodies  are  splinter-like. 
Glycogen  vacuoles,  when  present  in 
the  cyst,  may  be  fairly  well  defined. 

Entamoeba  coli  of  man,  other  pri- 
mates, the  dog  and  possibly  the  pig. 

Entamoeba  wenyoni  of  the  goat. 

E)itamoeba  nniris  of  mice,   rats,   ham- 
sters, and  other  rodents. 

Entamoeba  caviae  of  the  guinea  pig. 

Entamoeba  cunicnli  of  rabbits. 

Entamoeba  galli)iaynm  of  the  chicken, 
turkey,  guinea  fowl,  duck,  and  goose. 

3.  BO  VIS  GROUP.      The  endosome  of  the 
nucleus  varies  in  size;  it  may  be  as 
small  as  that  of  the  histolytica  group, 
but  is  generally  larger  than  that  of  the 
coli  group.     The  ring  of  peripheral 
granules  in  the  nucleus  may  be  fine  or 
coarse,  evenly  or  irregularly  distrib- 
uted.    Periendosomal  granules  may  be 
present.     The  cysts  have  1  nucleus 
when  mature,  and  their  chromatoid 
bodies  are  either  rods  with  rounded 
ends  or  less  often  splinter-like.     Gly- 
cogen granules,  when  present  in  the 
cyst,  are  usually  fairly  well  defined. 

Entamoeba  bovis  of  cattle. 
Entamoeba  ovis  of  sheep  and  goats. 
Entamoeba  dilimani  of  goats. 
Entanioeba  siiis  of  the  pig  and  perhaps 

man. 
Entamoeba  bubalis  of  the  carabao. 
E)ita»ioeba  cliattoni  of  monkeys  and 

probably  man. 


THE  AMOEBAE 


135 


4.  GINGIVALIS  GROUP.      The  nucleus 
has  a  small,  central  endosome  and  a 
ring  of  small  peripheral  granules. 
There  are  no  cysts.     Members  of  this 
group  are  found  in  the  mouth. 

Entamoeba  gingivalis  of  man,  other 

primates,  the  dog  and  cat. 
E)ita>noeba  equibuccalis  of  the  horse. 
Entamoeba  suigingivalis  of  the  pig. 

5.  INSUFFICIENTLY  KNOWN  SPECIES. 
This  group  includes  Entamoeba  gedo- 
etsti  of  the  horse  and  E.  caudata  of 
the  dog.     The  nucleus  of  E.   caudata 
resembles  that  of  E.  coli,  while  the 
nucleus  of  E.  caudata  resembles  that 
of  E.  histolytica.     The  cysts  of  these 
species  are  unknown. 

The  only  species  of  Entamoeba  patho- 
genic for  mammals  is  E.  histolytica.     The 
fact  that  it  has  been  recorded  in  an  aver- 
age of  about  18%  of  the  people  examined  in 
various  surveys  thruout  the  world  and  yet 
only  about  1/5  of  them  have  signs  or  symp- 
toms of  disease  has  puzzled  epidemiolo- 
gists for  many  years.     Two  other  facts 
contribute  to  the  problem.     One  is  that 
there  are  two  different  sizes  of  these 
amoebae,  the  smaller  of  which  is  not  asso- 
ciated with  disease;  it  has  been  encountered 
in  about  1/3  of  the  people  in  these  surveys. 
The  other  is  that  amoebic  dysentery  occurs 
mostly  in  the  tropics.    Autochthonous  cases 
occur  so  seldom  in  western  Europe  that 
many  European  parasitologists  believe  that 
cases  of  amoebic  dysentery  which  occur  in 
their  countries  have  been  imported  from 
the  tropics  either  directly  or  thru  contact 
with  infected  persons.    These  parasitolo- 
gists have  not  had  the  benefit  of  the  Amer- 
ican experience  with  the  disease.     There 
is  no  question  that  indigenous  cases  occur 
in  the  temperate  ZQne  of  this  country. 

Several  hypotheses  have  been  advanced 
in  explanation  (see  Hoare,  1958).    The 
first  theory,  suggested  about  1913  and  still 
held  by  perhaps  the  majority  of  parasitolo- 
gists,  is  based  on  an  unwillingness  to 
assign  separate  specific  names  to  protozoa 
which  differ  only  in  size  and  pathogenicity. 
According  to  this  view,  the  species  Enta- 
moeba histolytica  is  composed  of  a  small 


race  and  a  large  race.    The  small  race  is 
not  pathogenic,  while  the  large  race  may 
or  may  not  be.    In  its  virulent  phase  the 
latter  invades  the  tissues;  the  tropho- 
zoites of  this  phase  are  large- -the  "magna" 
form.    In  its  commensal  phase  it  remains 
in  the  lumen  of  the  intestine,  feeding  on 
bacteria  and  saprozoically.     The  tropho- 
zoites of  this  phase  are  small--the  "minuta" 
form.     Under  proper  conditions,  this  non- 
pathogenic "minuta"  form  can  invade  the 
intestinal  mucosa  and  turn  into  the  patho- 
genic "magna"  form.    The  trophozoites  of 
the  small  race  of  E.  histolytica  are  usually 
12  to  15 |U  in  diameter  and  the  cysts  are  5 
to  9|Li  in  diameter  with  a  mean  of  7  to  8/1. 
The  trophozoites  of  the  "magna"  form  of 
the  large  race  are  20  to  30  jj,  and  those  of 
the  "minuta"  form  12  to  15  |U.  in  diameter. 
However,  the  cysts  of  both  the  "magna" 
and  "minuta"  forms  are  the  same  size,   10 
to  20  jj,  in  diameter,  with  a  mean  of  about 
12^. 

The  second  theory  was  proposed  by 
Brumpt  in  1925.     He  recognized  3  species. 
He  called  the  small,  non- pathogenic  race 
Enta?noeba  liartmanni,   and  divided  the 
large  race  into  2  species.    Of  these,  E. 
dispar  is  non- pathogenic  and  occurs  thru- 
out the  world,  while  E.  dysenteriae  is 
pathogenic,  altho  it  may  cause  no  apparent 
symptoms  in  carriers,  and  occurs  only  in 
warm  and  hot  countries. 

The  third  theory  was  formulated  for- 
mally by  Hoare  in  1957.    It  calls  the  small, 
non- pathogenic  race  E.  hartmanni,    but  re- 
tains the  name  E.  histolytica  for  the  large 
race  of  the  first  theory.     It  then  divides  E. 
histolytica  into  an  avirulent  race  (corres- 
ponding to  Brumpt' s  E.  dispar)  and  a  viru- 
lent race  (corresponding  to  Brumpt's  E. 
dysenteriae)  which  may  invade  the  gut  wall 
or  live  in  the  lumen  without  causing  symp- 
toms. 

This  view  has  a  great  deal  to  recom- 
mend it.     By  giving  the  non- pathogenic 
small  form  a  separate  name,  it  makes  it 
easier  for  the  physician  to  interpret  lab- 
oratory reports  and  prevents  faulty  diag- 
noses and  needless  treatment.    However, 
the  question  whether  there  actually  are 
completely  non- pathogenic  strains  of  E. 


136 


THE  AMOEBAE 


histolytica  (sensu  stricto)  which  cannot  be 
induced  to  become  pathogenic  has  not  yet 
been  answered  satisfactorily.    Concomi- 
tant bacteria,  nutritional  deficiencies  and 
other  factors  affect  the  pathogenicity  of 
the  amoebae.    Indeed,   Phillips  el  al. 
(1955)  found  it  impossible  to  infect  bac- 
teria-free guinea  pigs  with  E.  histolytica 
at  all,  altho  normal  guinea  pigs  or  those 
infected  with  Escherichia  coli  or  Aero- 
bacter  aerogenes  could  be  readily  infected 
and  subsequently  developed  intestinal  le- 
sions. 

Some  of  the  amoebae  reported  as  E. 
histolytica  from  domestic  animals  may 
well  have  been  actually  E.  hartnianni.   but 
unless  they  were  specifically  described  as 
having  small  cysts,  it  is  impossible  to 
know  which  they  were. 

The  above  discussion  has  to  do  pri- 
marily with  a  matter  of  nomenclature.    In 
addition,  another  species  morphologically 
identical  with  E.  histolytica  has  been 
found  in  sewage.     This  is  E.  moshkovskii 
It  has  not  been  found  in  fresh  feces,  but 
nevertheless  its  existence  must  be  taken 
into  consideration  in  diagnosis.    It  is  not 
infective  for  rats,  kittens,  guinea  pigs  or 
frog  or  salamander  larvae  and  its  optimum 
temperature  is  about  24°  C,  altho  it  will 
grow  poorly  at  37°  C. 

Before  beginning  a  systematic  account 
of  the  species  of  Entamoeba,  a  word  is  in 
order  regarding  the  bovis  group.    All  of 
these  look  alike,  with  minor  differences 
which  may  not  be  of  taxonomic  significance. 
Different  names  have  been  given  to  the 
forms  in  different  hosts,  but  no  cross- 
transmission  studies  have  been  attempted, 
and  it  is  quite  likely  that  when  they  are, 
some  of  these  forms  will  be  found  to  be 
synonyms.    In  this  case.  Entamoeba  bovis 
will  have  precedence  over  the  other  names. 

The  name  Entamoeba  polecki  has 
been  used  for  members  of  the  bovis  group 
from  the  pig  and  goat,  but  it  is  a  nomeu 
nudum.     Prowazek's  (1912)  original  des- 
cription and  figures  of  it  are  so  poor  that 
it  is  impossible  to  know  whether  he  was 
dealing  with  a  member  of  the  genus  Enta- 
moeba at  all. 


Noble  and  Noble  (1952)  and  Hoare 
(1959)  have  reviewed  the  amoebae  of  do- 
mestic animals. 


ENTAMOEBA  IIISTOL  YTICA 
SCHAUDINN,   1903 

Synonyms:      Amoeba  coli,  Amoeba 
dysenleriae,  Entamoeba  tetragena.  Enta- 
moeba dispar.  Entamoeba  venaticum. 

Disease:     Amoebic  dysentery. 

Hosts:     Man,  orang-utan,  gorilla, 
chimpanzee,  gibbon,  many  species  of 
macaques,  baboons,  spider  monkeys  and 
other  monkeys,  dog,  cat,   pig,   rat,  pos- 
sibly cattle.    The  rat,  mouse,  guinea  pig 
and  rabbit  are  often  infected  experimentally. 

Location:      Large  intestine,  some- 
times liver,  occasionally  lungs,  and  rarely 
other  organs  including  the  brain,  spleen, 
etc. 

Geographic  Distribution:     Worldwide. 
Maps  of  the  world  distribution  of  amoebic 
dysentery  and  E.  Jiistolytica,    together 
with  climatological  and  other  information, 
were  published  by  Piekarski  and  Westphal 
(1952)  and  Westphal  (1955). 

Prevalence:     E.  histolytica  is  most 
important  as  a  parasite  of  man.     It  also 
occurs  in  monkeys  and  higher  primates. 
According  to  Belding  (1952),   it  was  found 
in  an  average  of  17.6%  of  42,713  persons 
(range,  0.8  to  50%)  in  37  surveys  thruout 
the  world  from  1941  to  1948.     In  10  surveys 
of  10,867  persons  in  the  United  States  from 
1941  to  1948,  it  was  found  in  an  average  of 
13.6%  (range,  0.8  to  38%). 

According  to  Benson,   Fremming  and 
Young  (1955),   it  has  given  considerable 
trouble  in  their  chimpanzee  colony  at  the 
Univ.  of  Texas. 

Sporadic  cases  of  amoebic  dysentery 
have  been  reported  in  dogs;  these  animals 
are  generally  considered  to  have  acquired 
their  infections  from  human  contacts. 
Kartulis  (1891,   1913)  found  £.  histolytica 
causing  dysentery  in  3  dogs  in  Egypt;  in 


THE  AMOEBAE 


137 


Q 


Fig.  20.      Species  of  Entamoeba.     A.    E.   hislolylica  trophozoite.     B.    E.  histolytica  cyst. 
C.    E.  hartmanni  trophozoite.    D.    E.  Iiartmanni  cyst.     E.    E.  coli  cyst. 
F.   E.  coli  trophozoite.     G.    E.  gallinarum  trophozoite.     H.    E.  gallinarum 
cyst.    I.    E.  bovis  trophozoite.    J.    E.  bovis  cyst.    K.    E.  ovis  trophozoite. 
L.    E.  ovis  cyst.     M.  E.  dilimani  trophozoite.     N.    E.  dilimani  cyst. 
O.   E.  suis,   large  trophozoite.     P.    E.  suis,   small  trophozoite.    Q.    E.  suis, 
large  cyst.    R.    E.  snis,   small  cyst.    X  1700.     (From  Hoare,   1959,   in  Veter- 
inary Reviews  and  Annotations) 


138 


THE  AMOEBAE 


one  of  these,  a  liver  abscess  was  also 
present.    Darling  (1915)  reported  a  fatal 
infection  in  a  dog  in  Panama.    Ware  (1916) 
reported  an  outbreak  in  a  pack  of  foxhounds 
in  the  Nilgiri  Hills  of  India,  Boyd  (1931) 
reported  an  outbreak  in  another  pack  of 
hounds  in  India,  and  more  recently  Gana- 
pathy  and  Alwar  (1957)  reported  2  cases  of 
amoebic  dysentery  in  dogs  in  India. 
Fischer  (1918)  reported  a  case  of  amoebic 
dysentery  in  a  dog  in  China,   Bauche  and 
Motais  (1920)  reported  one  in  Indochina, 
and  Morcos  (1936)  found  5  cases  in  Egypt. 
In  the  United  States,   Faust  (1930)  found  2 
dogs  in  New  Orleans  with  amoebic  dysen- 
tery, Andrews  (1932)  found  £.  histolytica 
in  the  feces  of  a  diarrheic  dog  in  Baltimore, 
and  Thorson,  Seibold  and  Bailey  (1956)  re- 
ported a  case  of  systemic  amoebosis  in  a 
puppy  which  also  had  distemper.    E.  his- 
tolytica was  found  in  large  numbers  in  the 
lungs  and  amoebae  were  also  seen  in  the 
liver,  kidneys  and  spleen. 

In  surveys  of  presumably  normal  dogs, 
Kubo  (1936)  found  E.  histolytica  in  8%  of 
85  street  dogs  in  Mukden,   China,  while 
Yamane  (1938)  found  it  in  3%  of  60  street 
dogs  from  the  same  city.    Chary  et  al. 
(1954)  stated  that  amoebic  dysentery  occurs 
frequently  in  dogs  in  Indochina.     Eyles 
et  al.    (1954)  found  E.  histolytica  in  8.  4% 
of  143  dogs  in  the  Memphis,  Tennessee  dog 
pound.    The  protozoa  were  so  scarce  that 
cultural  methods  were  required  to  reveal 
them.    This  finding  suggests  that  amoebic 
dysentery  may  be  more  common  in  dogs 
than  is  generally  believed. 

Natural  E.  histolytica  infections  are 
apparently  rare  in  cats,  but  Kessel  (1928) 
found  the  protozoon  in  3  of  150  kittens  in 
China. 

E.  histolytica  is  rare  in  swine.     Frye 
and  Meleney  (1932)  found  it  in  1  of  127 
pigs  which  they  examined  in  Tennessee; 
this  animal  came  from  a  farm  where  an 
infected  woman  lived. 

There  are  2  reports  of  what  may  have 
been  E.  histolytica  in  cattle.    Walkiers 
(1930)  saw  it  in  the  feces  of  dysenteric 
cattle  in  the  Belgian  Congo.    Thiery  and 
Morel  (1956)  found  it  in  the  lungs  of  a 


young  zebu  in  Dakar  which  was  slaughtered 
on  account  of  generalized  streptothricosis. 

Natural  infections  in  rats  have  been 
reported  by  a  number  of  workers.    Chiang 
(1925)  found  E.  histolytica  in  7  laboratory 
rats.     Brug  (1919)  found  it  in  2  of  50  wild 
rats  in  Batavia,   Nagahana  (1934)  found  it 
in  3  of  274  wild  rats  in  Mukden,   China, 
and  Epshtein  and  Avakian  (1937)  found  it  in 
7  of  515  wild  Rattiis  norvegicus  in  Moscow. 
In  the  United  States,  Lynch  (1915)  saw  it  in 
a  wild  rat,   Tsuchiya  and  Rector  (1936) 
found  it  in  2  of  100  wild  rats  in  St.   Louis, 
and  Andrews  and  White  (1936)  found  it  in 
28  (1.1%)  of  2515  wild  rats  in  Baltimore. 

Morphology:     The  trophozoites  of  the 
large,  pathogenic  race  of  E.  histolytica 
are  20  to  30  ji  and  those  of  the  small  race 
are  12  to  15 ji  in  diameter.     They  have  a 
thick,  clear  layer  of  ectoplasm  and  gran- 
ular endoplasm.    They  move  rapidly  when 
warm,  usually  moving  forward  in  a  straight 
line  with  a  single  clear  pseudopod  at  the 
anterior  end.    When  the  feces  have  cooled, 
the  amoebae  stay  in  one  place  and  throw 
out  large,  clear  pseudopods  from  various 
parts  of  their  body.     The  trophozoites  often 
ingest  erythrocytes,  a  feature  which  differ- 
entiates them  from  those  of  other  amoebae. 
The  nucleus  is  indistinct  in  living  amoebae. 
When  stained  with  hematoxylin,  it  has  a 
small,  central  endosome,  a  ring  of  small 
peripheral  granules  and  a  few  scattered 
chromatin  granules  in  between.     The  cysts 
of  both  the  large  and  small  races  are  10  to 
20jLt  (average,   12 /i  )  in  diameter.     They 
have  4  nuclei  when  mature  and  often  con- 
tain rod-like  chromatoid  bodies  with  rounded 
ends.    Diffuse  glycogen  is  present  in  the 
young  cysts. 

Life  cycle:     E.  histolytica  multiplies 
in  the  trophozoite  stage  by  binary  fission. 
It  has  6  chromosomes.     Before  encysting, 
the  amoebae  round  up,  became  smaller 
and  eliminate  their  food  vacuoles.    They 
lay  down  a  cyst  wall,  and  the  nucleus 
divides  into  2  and  then  into  4  small  nuclei. 
After  the  4-nucleate  amoebae  emerge  from 
the  cyst,  both  the  nuclei  and  cytoplasm 
divide  so  that  8  small  amoebulae  result. 
Each  then  grows  into  a  normal  tropho- 
zoite. 


THE  AMOEBAE 


139 


Pathogenesis:     As  mentioned  above, 
only  the  large  forms  of  E.  histolytica  are 
generally  considered  pathogenic,  altho 
there  are  reports  of  mild  disease  and 
slight  lesions  associated  with  the  small 
form  (Shaffer  et  al.^   1958).    They  may 
cause  diarrhea  or  dysentery,  and  may 
invade  the  wall  of  the  cecum  and  colon, 
forming  ragged,  undermining  or  flask- 
shaped  ulcers  which  may  be  pinpoint  in 
size  or  may  become  large  and  confluent. 
The  amoebae  invade  the  mucosa  at  first 
and  multiply  to  form  small  colonies.    These 
colonies  then  extend  into  the  submucosa  and 
even  into  the  muscularis.    In  the  absence  of 
bacterial  invasion,  there  is  little  tissue  re- 
action, but  in  complicated  infections  there 
is  hyperemia,  inflammation  and  infiltra- 
tion with  neutrophiles. 

Some  of  the  amoebae  may  pass  into 
the  lymphatics  or  even  the  mesenteric 
venules.     Those  entering  the  hepatic  portal 
system  pass  to  the  liver,  where  they  may 
cause  abscesses.    Those  which  enter  the 
lymph  ducts  are  generally  filtered  out  by 
the  lymph  nodes.    Abscesses  may  be 
formed  in  various  other  organs,  including 
the  lungs,  brain,  etc. ,  depending  on  the 
host's  resistance. 

The  relation  of  parasite  strain  to 
pathogenicity  has  already  been  mentioned. 
The  species  of  concomitant  bacteria  pres- 
ent may  also  affect  the  amoeba's  pathoge- 
nicity, as  may  the  nutritional  status  of  the 
host  and  other  environmental  factors. 
Dysentery  is  much  more  common  in  the 
tropics  than  in  the  temperate  zone. 

In  most  cases,  E.  histolytica  causes 
minor  symptoms  or  none  at  all.    Infections 
may  last  40  years  or  even  more.    There 
may  be  recurring  mild  to  severe  gastro- 
intestinal symptoms,  including  intermit- 
tent diarrhea,  bowel  irregularity,  abdom- 
inal pain,  nausea  and  flatulence.    Some- 
times affected  persons  tire  easily,  have 
headaches  or  feel  nervous.    Appendicitis 
or  symptoms  resembling  it  may  occur. 
These  symptoms  generally  clear  up  after 
treatment. 

In  acute  amoebic  dysentery,  the  feces 
consist  almost  entirely  of  blood  and  mucus 


filled  with  amoebae  and  blood  cells.    The 
patient  is  wracked  by  waves  of  severe 
abdominal  pain  and  spends  a  large  part  of 
his  time  on  the  stool,   straining  and  passing 
blood  and  mucus  every  few  minutes.     In 
contrast  to  bacillary  dysentery,  there  is  no 
fever  in  uncomplicated  cases. 

Epidemiology:     As  mentioned  above, 
E.  histolytica  is  primarily  a  parasite  of 
primates,  and  man  is  the  reservoir  of  in- 
fection for  his  domestic  animals.     This  is 
one  of  the  few  zoonoses  which  man  gives 
to  his  associated  animals  in  return  for  the 
many  which  he  receives  from  them. 

Infection  is  due  to  ingestion  of  cysts. 
Since  trophozoites  alone  are  passed  by 
dysenteric  individuals,  these  are  not  im- 
portant sources  of  infection,  while  cyst- 
producing  chronic  cases  and  carriers  are. 

The  cysts  are  relatively  resistant. 
They  are  not  affected  by  water  chlorina- 
tion,  but  can  be  removed  by  sand  filtration. 
They  survive  for  at  least  8  days  in  soil  at 
28  to  34°  C  (Beaver  and  Deschamps,  1949), 
but  live  only  an  hour  at  46  to  47°  C  and 
less  than  a  minute  at  52°  C  (Jones  and 
Newton,   1950).     They  survive  longest  at 
refrigerator  temperatures  (40  days  at  2  to 
6°  C  according  to  Simitch,  Petrovitch  and 
Chibalitch,   1954;  62.  5  days  at  0°  C  accord- 
ing to  Chang,   1955).    They  will  not  excyst 
after  24  hours  at  temperatures  of  -15°  C 
or  lower  (Halpern  and  Dolkart,  1954),  and 
die  in  7.  5  hours  or  less  in  the  deep  freezer 
at  -28°  C  (Chang,  1955). 

The  cysts  are  usually  transmitted  with 
food  or  water.    Raw  vegetables  may  be  a 
source  of  infection.     Flies  may  transmit 
the  cysts  also.     Pipkin  (1949)  was  able  to 
cultivate  cysts  from  the  vomitus  of  filth 
flies  {Musca  domestica,  Lucilia  pallescens, 
Cochliomyia  macellaria,  Phormia  regina 
and  Sarcophaga  ttiisera)  39  to  64  minutes 
after  ingestion  and  from  their  feces  172  to 
254  minutes  after  ingestion. 

Faulty  plumbing  and  water  systems 
may  cause  water-borne  transmission.    The 
most  striking  case  of  this  kind  occurred 
during  the  Chicago  World  Fair  in  1933. 
An  outbreak  of  amoebic  dysentery  occurred 


140 


THE  AMOEBAE 


among  guests  at  two  neighboring  hotels 
from  which  over  1000  cases  with  58  deaths 
were  tracked  down  in  44  states  and  3  Ca- 
nadian provinces  (Bundesen  el  al.  ,   1936). 
Cross  connections  between  the  water  and 
sewage  pipes,  back  siphonage  from  toilet 
bowls  into  the  water  supply  and  leakage 
from  an  overhead  sewage  pipe  in  the 
kitchen  were  involved. 

Food  handlers  may  play  an  important 
role  in  transmission  of  amoebae,  even  tho 
the  cysts  rarely  survive  more  than  10 
minutes  on  the  hands,  except  under  the 
fingernails  (Spector  and  Buky,   1934). 
Thus,  Schoenleber  (1940,   1941)  reported 
that  in  a  group  of  Americans  living  in  a 
Standard  Oil  Co.   camp  in  Venezuela,  the 
prevalence  of  amoebic  infection  was  re- 
duced in  3  years  from  25.  6%  to  1.  9%  and 
the  amoebic  dysentery  rate  from  36.84  to 
0.61  per  1000  per  year  by  inspection  and 
treatment  of  food  handlers.     Winfield  and 
Chin  (1939),  in  a  comparison  of  the  prev- 
alence of  amoebic  infection  with  food  hab- 
its in  different  parts  of  China,   concluded 
that  transmission  by  food  handlers  is 
probably  more  important  than  by  other 
means  in  that  country.     E.  histolytica  is 
much  commoner  in  North  China  than  in 
South  and  Central  China.     This  is  corre- 
lated with  the  serving  and  eating  of  cold 
bread  with  the  hands  in  North  China  as 
contrasted  to  the  handling  of  hot  rice  with 
a  serving  spoon  and  chopsticks  in  South 
and  Central  China.     On  the  other  hand, 
Sapero  and  Johnson  (1939,   1939a)  found  no 
evidence  that  carriers  were  important  in 
the  transmission  of  amoebae  in  a  study  of 
919  persons  in  the  U.S.   Navy.     The  sani- 
tary habits  of  American  sailors  probably 
had  something  to  do  with  this. 

Diagnosis:     The  laboratory  diagnosis 
of  amoebiasis  has  been  discussed  in  detail 
by  Brooke  (1958).     Live  amoebae  can  be 
found  in  wet  smears  made  with  physiolog- 
ical salt  solution.     These  smears  may  be 
stained  with  Lugol's  iodine  solution  diluted 
1:5  to  bring  out  the  nuclei  of  the  cysts  and 
stain  glycogen.     However,  for  accurate 
identification  and  differentiation  from 
other  species  of  amoebae,  staining  with 
hematoxylin  is  essential.     The  smears  are 
generally  fixed  in  Schaudinn's  fluid  and 
stained  with  Heidenhain's  iron  hematoxylin. 


Sapero  and  Lawless's  (1953)  MIF  (merthio- 
late -iodine -formaldehyde)  stain -preserva- 
tion technic  can  also  be  used. 

For  concentration  of  cysts,  flotation 
in  zinc  sulfate  solution  (Faust  et  al.  ,  1938) 
can  be  used.    The  cysts  are  distorted  be- 
yond recognition,   however,  by  the  other 
salt  and  sugar  solutions  in  common  use 
for  flotation  of  helminth  eggs.     For  con- 
centration by  sedimentation,  the  FTE 
(formalin- triton-ether)  sedimentation 
technic  (Ritchie,   Pan  and  Hunter,   1952, 
1953)  or  MIFC  (merthiolate- iodine-formal- 
dehyde-concentration) technic  (Blagg  el  al.  , 
1955) can  be  used. 

Cultivation  can  be  helpful  in  diagnosis 
of  amoebiasis,  but  only  if  fresh  specimens 
are  used  and  if  the  laboratory  personnel 
are  expert.    Cultivation  is  not  recommended 
for  general  use. 

E.  histolytica  cannot  be  differentiated 
morphologically  from  E.  haybiuDiiii,    and 
its  differentiation  from  other  intestinal 
amoebae,  and  especially  from  E.  coli,    is 
not  an  easy  task.     There  is  a  surprising 
amount  of  discrepancy  even  among  those 
who  should  be  qualified.     Thus,  in  an  eval- 
uation by  the  USPHS  Communicable  Dis- 
ease Center  of  the  diagnostic  ability  of  42 
state  health  department  laboratories 
(Brooke  and  Hogan,   1952),  an  average  of 
4.  1  out  of  18  £.   histolytica  infections  was 
missed  among  98  stool  samples  sent  to  the 
laboratories  for  examination,  and  an  aver- 
age of  4.4  false  positive  reports  was  made 
among  the  80  negative  samples.     Further- 
more, in  an  analysis  of  responses  by  mem- 
bers of  the  American  Society  of  Tropical 
Medicine  to  a  questionnaire  on  the  clinical 
and  laboratory  diagnosis  of  amoebiasis, 
Brooke  et  al.  (1953)  found  a  surprising 
lack  of  agreement  in  statements  concerned 
with  the  identification  of  E.  histolytica 
cysts  and  trophozoites. 

Goldman  (1959,   1960)  was  able  to  dif- 
ferentiate between  Entamoeba  histolytica, 
E.  liart>}ianni,   E.  nioshkovskii  and  E.  coli 
by  a  fluorescence  antibody  technic.    Three 
originally  invasive  strains  of  E.  histolytica 
which  he  studied  differed  significantly 
from  a  non-invasive  strain. 


THE  AMOEBAE 


141 


Cultivation:      E.  histolytica  was  first 
cultivated  by  Boeck  and  Drbohlav  (1925). 
Their  medium  was  composed  essentially 
of  a  coagulated  egg  slant  overlaid  with 
Locke's  solution  containing  serum.     Var- 
ious modifications  of  this  medium  are 
still  in  use.     Cleveland  and  Collier  (1930) 
used  a  liver  infusion  agar  slant  overlaid 
with  serum  and  physiological  salt  solution. 
Balamuth  (1946)  introduced  an  all-liquid 
egg  infusion-liver  extract  medium. 

Treatment:     Amoebiasis  can  be 
treated  with  a  number  of  drugs  (cf .   Bala- 
muth and  Thompson,  1955).    The  old  stand- 
ard drug,  emetine,  is  not  used  as  much  as 
formerly  because  of  its  toxicity.     Other 
drugs  from  which  one  can  choose  include 
(1)  the  arsanilic  acid  derivatives,  carbar- 
sone,   glycobiarsol  (bismuth  glycoarsani- 
late,  Milibis)  and  thiocarbarsone;    (2)  the 
iodoquinoline  derivatives,  diodohydroxy- 
quin  (Diodoquin),   chiniofon  (Yatren)  and 
iodochlorhydroxyquin  (Vioform);    (3)  the 
antimalarial  drug,  chloroquine;  and 
(4)  the  antibiotics,  erythromycin,  fuma- 
gillin,  tetracycline,  chlortetracycline  and 
oxytetracycline. 

The  particular  drug  selected  depends 
in  part  on  the  type  of  amoebic  infection 
involved.     For  acute  or  subacute  dysen- 
tery, erythromycin,  oxytetracycline  or 
chlortetracycline  may  be  used.    Erythro- 
mycin is  administered  to  man  by  mouth  at 
the  rate  of  15  mg/kg  daily  in  divided  doses 
for  14  days.    The  usual  human  course  of 
treatment  with  oxytetracycline  or  chlor- 
tetracycline is  0.  5  g  4  times  a  day  by 
mouth  for  10  days. 

For  chronic  cases  or  to  eradicate  in- 
testinal infections,  one  of  the  arsanilic 
acid  or  iodoquinoline  derivatives  may  be 
used.    The  usual  adult  human  course  of 
treatment  with  carbarsone  is  0.  25  g  2  or 
3  times  a  day  by  mouth  for  10  days.    That 
with  glycobiarsol  is  0.  5  g  3  times  a  day  by 
mouth  for  8  days.     That  with  chiniofon  is 
1.  0  g  3  times  a  day  by  mouth  for  7  days. 
That  with  diodohydroxyquin  is  0.  65  g  3 
times  a  day  by  mouth  for  20  days. 


For  amoebic  hepatitis  or  liver  ab- 
scesses, chloroquine  is  used.    A  loading 
dose  of  1  g  chloi'oquine  phosphate  (0.6  g 
base)  by  mouth  on  each  of  2  successive 
days  followed  by  0.  5  g  daily  for  2  to  3 
weeks  is  the  recommended  adult  human 
course  of  treatment. 

Diodohydroxyquin  has  also  been  rec- 
ommended as  a  prophylactic  drug  for  use 
by  travellers  in  ai-eas  of  high  endemicity. 

While  relatively  little  work  has  been 
done  on  the  treatment  of  amoebiasis  in 
domestic  animals,  the  same  drugs  are  in 
general  effective  in  them.    Benson,  Frem- 
ming  and  Young  (1955)  found  that  for  chim- 
panzees the  most  successful  drugs  were 
carbarsone  (0.25  g  twice  daily  for  10 
days)  and  fumagillin  (20  to  30  mg  twice 
daily  for  10  days)  administered  in  fruit  or 
fruit  juice.    They  also  frequently  gave  a 
course  of  emetine  hydrochloride  (1  mg/kg 
body  weight  up  to  a  maximum  of  60  mg, 
injected  intramuscularly  daily  for  a  max- 
imum of  6  days)  prior  to  carbarsone  or 
fumagillin  therapy  (see  also  Fremming 
et  al. ,   1955).     Herman  and  Schroeder 
(1939)  successfully  treated  amoebic  diar- 
rhea in  a  21 -lb.  orang-utan  with  carbar- 
sone.   They  gave  2  courses  of  treatment 
11  days  apart,  each  course  consisting  of 
0.  05  g  carbarsone  in  milk  or  a  slice  of 
banana  3  times  a  day  for  a  week. 

Prevention  and  Control:     Infection 
with  amoebae  can  be  prevented  by  sanita- 
tion.   Water  supply  systems  should  be 
built  without  cross  connections  to  sewage 
systems.    Water  which  may  be  polluted 
should  be  boiled  or  filtered  thru  sand, 
since  ordinary  chlorination  does  not  kill 
the  cysts.     Food  handlers  should  wash 
their  hands  thoroughly  after  using  the  toi- 
let.   Vegetables  grown  on  polluted  ground 
should  be  cooked,  or,  if  they  are  to  be 
eaten  raw,  should  be  scalded  or  soaked  in 
vinegar  containing  5%  acetic  acid  for  15 
minutes  at  30°  C  or  in  vinegar  containing 
2.  5%  acetic  acid  for  5  minutes  at  45°  C 
(Beaver  and  Deschamps,   1949).    Diodohy- 
droxyquin may  also  be  used  prophylactically. 


142 


THE  AMOEBAE 


ENTAMOEBA  HARTMANNI 
VON  PROWAZEK,   1912 

As  mentioned  above,  E.  kartmanni 
closely  resembles  the  small  race  of  E. 
histolytica.     It  can  be  differentiated  by 
careful  examination  of  hematoxylin-stained 
preparations.    Burrows  (1959)  compared 
the  two  species.     Most  trophozoites  of  E. 
hartmanni  are  smaller  than  those  of  E. 
histolytica.     Rounded  trophozoites  of  E. 
hartmanni  range  from  3  to  10.  Sjix  in  diam- 
eter, while  those  of  E.  histolytica  are 
6.  5|i  or  more  in  diameter.     The  tropho- 
zoite nucleus  of  E.  hartmanni  is  usually 
2.  0  to  2.  5 fi  in  diameter  but  may  range 
from  1.  5  to  3.  2^  ,  while  that  of  E.  his- 
tolytica is  usually  3.0  to  3.  5fj,  in  diameter 
but  may  range  from  2.8  to  3.  8/i .    The 
peripheral  chromatin  of  E.  hartmanni  is 
more  variable  in  its  arrangement  than 
that  of  E.  histolytica  and  may  consist  of 
discrete  granules  with  wide  spaces  be- 
tween them,  a  crescent  of  granules  on  one 
side  of  the  nucleus,  or  a  single  large  bar 
of  chromatin  with  several  small  granules 
around  the  membrane;  the  peripheral 
chromatin  of  E.  histolytica  is  generally 
distributed  uniformly  along  the  nuclear 
membrane. 

Most  cysts  of  E.   Itartmanni  are 
smaller  than  those  of  E.  histolytica.     They 
range  from  3.  8  to  8.  Ofi  in  diameter  while 
those  of  small  race  E.  histolytica  are 
5.  5(1  or  more  in  diameter.    The  cyst  nu- 
clei of  E.  hartmanni  are  1.  8  to  3.  Ojj,  in 
diameter  in  uninucleate  cysts,  1.  3  to  2.0 )i 
in  binucleate  cysts  and  0.  7  to  1.  7 /i  in 
tetranucleate  cysts;  those  of  small  race 
E.  histolytica  are  2.4  to  2.8  ji  in  diameter 
in  uninucleate  cysts,  2.  0  to  2.  8/j,  in  binu- 
cleate cysts  and  1.4  to  2.2 /i  in  tetranu- 
cleate cysts.     The  cysts  of  E.  liartmanni 
seldom  contain  large  glycogen  bodies,  but 
nearly  all  of  them  have  a  few  to  many 
small  vacuoles;  the  cysts  of  E.  histolytica 
generally  have  one  large  glycogen  vacuole 
or  no  vacuoles.    The  chromatoid  bodies  of 
the  two  species  are  similar. 

Freedman  and  Elsdon-Dew  (1959) 
suggested  that,  until  an  accurate,  prac- 
tical method  of  separation  is  devised, 
mean  sizes  of  12/i  for  trophozoites  and 


10/i  for  cysts  be  used  as  the  dividing  line 
between  E.  histolytica  and  E.  liartmanni. 
The  latter  criterion  has  been  used  for 
some  time  to  distinguish  between  the  cysts 
of  large  and  small  race  E.  histolytica  by 
those  who  do  not  accept  the  name  E.  liart- 
manni (Shaffer  et  al.  ,   1958). 

The  incidence  of  E.  liartmanni  in  an- 
imals and  man  is  unknown  because  in  the 
past  it  has  ordinarily  been  lumped  with 
E.  histolytica.     According  to  Burrows 
(1957,   1959)  about  half  of  the  reported 
cases  of  E.  histolytica  in  the  United  States 
were  actually  E.  hartmanni.     Further 
studies  in  which  the  two  species  are  sep- 
arated will  throw  light  on  this  point,  which 
is  important  because  E.  hartmanni  is  non- 
pathogenic. 


ENTAMOEBA  MOSHKOVSKII 
CHALAYA,   1941 

This  species  occurs  in  sewage.    It  is 
not  a  parasite  of  animals,  but  of  the  mu- 
nicipal digestive  tract.     It  was  found  in 
the  sewage  disposal  plant  and  sewer  sys- 
tem of  Moscow  by  Chalaya  (1941,   1947), 
in  sewage  in  Leningrad  by  Gnezdilov  (1947), 
in  sewage  in  Brazil  by  Amaral  and  Azzi 
Leal  (1949),  in  sewage  in  London  by  Neal 
(1950,  1953),  and  in  sewage  in  Quebec  by 
Lachance  (1959).     Probably  the  same  or- 
ganism was  found  in  sewage  in  California 
by  Wright,   Cram  and  Nolan  (1942),  altho 
they  did  not  name  it.     Chalaya  (1947)  cul- 
tivated it  from  the  water  of  2  ponds  and  a 
river  in  Russia.     Altho  E.  moshkovskii 
is  not  parasitic,  the  possibility  of  its  ac- 
cidental presence  in  fecal  samples  is  of 
concern  in  diagnosis. 

E.  moshkovskii  resembles  E.  histo- 
lytica morphologically.     The  trophozoites 
are  active,   9  to  29fi  (usually  11  to  13(j.) 
in  diameter.    The  nucleus  has  a  small, 
central  endosome  and  a  peripheral  layer 
of  fine  granules.    The  cysts  are  generally 
spherical,  7  to  17 /i  in  diameter.    They 
contain  a  very  large  glycogen  vacuole  at 
first  which  is  eventually  absorbed  as  the 
cysts  age.     The  chromatoid  bodies  are 
large,  rather  elongate,  and  have  rounded 
ends.    The  mature  cysts  have  4  nuclei. 


THE  AMOEBA 


143 


The  cysts  remain  viable  at  4"  C  up  to  10 
months  if  they  are  not  allowed  to  dry  out. 

E.  nioshkovskii  can  be  cultivated  in 
the  usual  Entamoeba  media..    Its  optimum 
temperature  is  about  24°  C  and  it  grows 
poorly  at  37°  C.     The  ability  to  grow  at 
room  temperature  differentiates  this  spe- 
cies from  E.  histolytica. 

Chalaya  (1941)  was  unable  to  infect 
kittens  with  E.  moshkovskii,    and  Neal 
(1953)  could  not  infect  rats,  frog  {Rana 
temporaria  )  tadpoles  or  salamander 
{Salamandra  maculosa)  larvae  by  feeding. 


ENTAMOEBA  EQUI 
FANTHAM,   1921 

Fantham  (1921)  found  this  amoeba  in 
the  feces  of  2  horses  with  signs  of  intes- 
tinal disturbance  in  South  Africa.     It  is 
unusually  large,  fully  extended  tropho- 
zoites measuring  40  to  50  by  23  to  29)Lt 
and  rounded  ones  28  to  35 /i  in  diameter. 
The  nucleus  is  of  the  histolytica  type,  but 
is  oval  rather  than  round.    Erythrocytes 
are  ingested.     The  cysts  are  15  to  24  ju.  in 
diameter  and  contain  4  nuclei  and  chroma- 
toid  bars. 


ENTAMOEBA  ANATIS 
FANTHAM,   1924 

Fantham  (1924)  found  this  amoeba  in 
the  feces  of  a  duck  which  had  died  of  acute 
enteritis  in  South  Africa.    It  resembles 
E.  histolytica  morphologically,  and  its 
trophozoites  ingest  erythrocytes.     The 
cysts  are  spherical  or  subspherical,  thin- 
walled,  13  to  14  n  in  diameter,  and  con- 
tain 1  to  4  nuclei  and  thin,  needle-like 
chromatoid  bodies. 


ENTAMOEBA   CO  LI 
(GRASSI,   1879) 
CASAGRANDI  AND 
BARBAGALLO,  1895 

Synonyms:     Am,oeba  coli,  Endamoeba 
hominis.  Council-mania  lafleuri. 

This  is  the  commonest  species  of 
amoeba  in  man.    According  to  Belding 


(1952),   it  was  found  in  28%  in  19  surveys 
of  17,733  persons  thruout  the  world  and 
occurs  in  about  30%  of  the  population  of 
the  United  States.     It  also  occurs  in  the 
gorilla,  orangutan,   chimpanzee,  gibbon 
and  in  various  species  of  macaques  and 
other  monkeys  (Mackinnon  and  Dibb, 
1938).    Smith  (1910)  saw  an  amoeba  sim- 
ilar to  E.  coli  in  pigs,  and  Kessel  (1928a) 
found  it  in  a  Chinese  pig.     Kessel  (1928a) 
also  infected  pigs  experimentally  with  E. 
coli  cysts  from  man,  but  the  infections 
lasted  less  than  6  weeks. 

Entamoeba  coli  occurs  in  the  cecum 
and  colon.    It  can  be  cultivated  on  the 
usual  media.    It  is  non- pathogenic,  and 
therefore  must  be  differentiated  from  E. 
histolytica. 

Its  trophozoites  are  15  to  50 /i  (usually 
20  to  30  jn)  in  diameter.     The  cytoplasm  is 
filled  with  bacteria  and  debris,  and  the 
ectoplasm  is  thin.     The  organism  moves 
sluggishly.    The  nucleus  has  an  eccentric 
endosome  larger  than  that  of  E.  histo- 
lytica, and  a  row  of  relatively  coarse 
chromatin  granules  around  its  periphery. 
There  may  also  be  a  few  scattered  chrom- 
atin granules  between  the  endosome  and 
the  nuclear  membrane.    The  cysts  are  10 
to  33  ju  in  diameter  and  have  8  nuclei  when 
mature.     The  cysts  contain  slender,  splin- 
ter-like chromatoid  bodies  with  sharp, 
fractured  or  square  ends;  these  disappear 
as  the  cysts  age.    The  young  cysts  also 
may  contain  a  large,  well-defined  glycogen 
globule;  it  usually  disappears  before  the 
cyst  is  mature. 


ENTAMOEBA   WENYONI 
GALLI-VALERIO,   1935 

Wenyon  (1926)  reported  that  he  had 
seen  8-nucleate  amoeba  cysts  of  the  E. 
coli  type  in  the  feces  of  goats.    Galli- 
Valerio  (1935)  described  this  form,  naming 
it  Entamoeba  wenyoni.    The  few  tropho- 
zoites which  he  saw  measured  12  by  9j^i, 
their  protoplasm  was  fairly  granular  with 
no  distinction  between  ectoplasm  and  endo- 
plasm,  and  they  contained  numerous  bac- 
teria.    They  moved  very  slowly  with  short, 
rounded  pseudopods.    The  cysts  were  spher- 
ical, 6  to  9(i  in  diameter,  and  contained  8 
nuclei. 


144 


THE  AMOEBAE 


ENTAMOEBA  MURIS 
(GRASSI,   1879) 

Synonyms:     Amoeba  miiris.  Council- 
mania  muris,   Councilmania  decumani. 

E.  muris  occurs  commonly  in  the 
cecum  and  colon  of  rats,   mice  and  the 
golden  hamster  thruout  the  world.    An- 
drews and  White  (1936)  found  it  in  10.4%  of 
2515  wild  rats  in  Baltimore.     Fry  and  Mel- 
eney  (1932)  found  it  in  48%  of  48  wild  Rattus 
norvegicus  and  24. 1%  of  54  grey  mice  cap- 
tured in  a  rural  area  of  Tennessee.  Tsuchiya 
and  Rector  (1936)  found  it  in  8%  of  100  rats 
in  St.  Louis.    Elton,  Ford  and  Baker  (1931) 
reported  it  in  50%  of  440  long-tailed  field 
mice  (Apodemus  sylvaticus), 4l"/o  oi  116  bank 
voles  {Clelhrionomys  glareolus)  and  41% 
of  51  short-tailed  field  mice  {Microtus 
hirtus)  in  England.    Wantland  (1955)  found 
it  in  33%  of  412  golden  hamsters  from  sev- 
eral American  suppliers  and  laboratories. 
Mudrow-Reichenow  (1956)  found  E.   luuris 
in  7%  of  14  golden  hamsters,   35%  of  21 
laboratory  rats  and  39%  of  92  laboratory 
mice  in  Germany. 

Kessel  (1924)  transmitted  E.  muris 
from  the  rat  to  the  mouse  and  vice  versa. 
Neal  (1947,  1950a)  and  Saxe  (1954)  infected 
rats  with  E.  uiuris  from  the  golden  ham- 
ster and  mouse.    Saxe  (1954)  infected  the 
golden  hamster  with  E.  muris  from  the  rat. 

E.  muris  is  morphologically  similar 
to  E.   coli.    Its  trophozoites  are  8  to  30 /i 
long.     Its  cysts  are  9  to  20jj,  in  diameter 
and  have  8  nuclei  when  mature.    Its  nu- 
clear structure  and  division  were  studied 
by  Wenrich  (1940).     He  found  that  the  nu- 
cleus is  intermediate  in  structure  between 
those  of  E.  kislolylica  and  E.  culi  but 
more  nearly  resembles  the  latter.     It  var- 
ies in  diameter  from  3  to  9fi  with  a  mean 
of  4  to  5 |i.     In  division,  approximately  8 
chromosomes  are  formed.     Binucleate 
cysts  almost  always  contain  a  large  gly- 
cogen vacuole,  and  mononucleate  cysts 
very  frequently  do. 

E.  muris  is  non- pathogenic.     It  is 
important  to  the  research  worker  because 
it  must  be  differentiated  from  other  amoe- 
bae introduced  in  experimental  infections. 


ENTAMOEBA  CAVIAE 
CHATTON,   1918 

This  species  is  often  referred  to  as 

Entamoeba  cobayae  (Walker ,   1908)  Chatton, 
1917.     However,  the  form  which  Walker 
(1908)  called  Amoeba  cobayae  -wcls  seen  in 
cultures  from  a  guinea  pig  intestine  and 
was  not  an  Enta»ioeba  at  all.     Hoare  (1959) 
considered  this  species  a  synonym  of  E. 
muris. 

E.  caviae  is  common  in  the  ceca  of 
laboratory  guinea  pigs.     Nie  (1950)  found 
it  in  14%  of  84  guinea  pigs  in  Pennsylvania 
and  Mudrow-Reichenow  (1956)  found  it  in 
46%  of  13  guinea  pigs  in  Germany. 

E.  caviae  resembles  E.   culi.    Its 
morphology  has  been  studied  by  Nie  (1950). 
The  trophozoites  are  10  to  20 )i  in  diam- 
eter with  a  mean  of  14.4jj,.     The  nucleus 
is  3  to  5 (i  in  diameter.    Its  endosome  var- 
ies in  size  and  shape  and  may  be  central 
or  eccentric.    In  some  cases  it  is  com- 
posed of  several  granules.     There  is  a 
ring  of  coarse  chromatin  granules  inside 
the  nuclear  membrane.    The  cysts  are  11 
to  17 |i  in  diameter  with  a  mean  of  14^ 
and  have  8  nuclei  (Holmes,   1923).     They 
are  rare. 

E.   caviae  is  non- pathogenic.     Because 
it  is  so  common,  it  must  be  differentiated 
from  other  amoebae  in  experimentally  in- 
fected animals. 


ENTAMOEBA   CUNICULI 
BRUG,   1918 

This  species  occurs  in  the  cecum  and 
colon  of  the  domestic  rabbit.     It  is  not 
pathogenic.    It  resembles^,   coli,    and 
Kheisin  (1938)  has  even  suggested  the  name 
Entamoeba  coli  forma  cnniculi  for  it. 
Hoare  (1959)  considered  it  a  synonym  of 
E.   muris.    It  is  apparently  quite  common 
in  rabbits,  altho  there  seem  to  be  relatively 
few  reports  on  it.    Kheisin  (1938)  found  it 
in  25%  of  the  rabbits  he  examined  in  Russia. 
The  trophozoites  range  from  12  to  30  ji  in 
length  with  means  of  13  to  17  fi  in  different 
rabbits.    The  cysts  have  8  nuclei.    They 


THE  AMOEBAE 


145 


range  in  diameter  from  7  to  21  ji  with 
means  of  10  to  15ju  in  different  rabbits. 


ENTAMOEBA   GALLINARUM 
TYZZER,   1920 

This  non-pathogenic  species  was  des- 
cribed from  the  ceca  of  the  chicken  and 
turkey  by  Tyzzer  (1920).     By  cecal  inocu- 
lation of  parasite-free  baby  chicks, 
Richardson  (1934)  found  what  appeared  to 
be  the  same  species  in  the  ceca  of  the 
domestic  duck,  turkey  and  goose.     E. 
galliiiaruni  is  common.     McDowell  (1953) 
found  it  in  about  30%  of  a  large  number  of 
chickens  he  examined  in  Pennsylvania. 

E.  gallinarmu  closely  resembles  E. 
coli.     The  trophozoites  are  9  to  25jj,  in 
diameter,  most  measuring  16  to  18|i. 
The  endoplasm  is  highly  vacuolated  and 
contains  many  food  vacuoles.    Altho 
Tyzzer  (1920)  said  that  E.  galliiiaruni 
did  not  ingest  bacteria,  McDowell  (1953) 
found  that  bacteria  were  its  main  food, 
altho  it  also  ingested  Trichouionas  among 
other  foods.    The  ectoplasm  is  clear  or 
granular.     The  nucleus  is  3  to  5  ji  in  di- 
ameter, with  an  eccentric  endosome  and 
a  row  of  granules  around  the  outside. 
The  mature  cysts  are  12  to  15/i  in  diam- 
eter and  contain  8  nuclei. 


found  it  in  the  feces  of  4  gnus  ( Conno- 
chaetes  taurinus)  in  the  London  zoo.     It 
has  been  described  most  recently  by  Noble 
(1950)  and  Noble  and  Noble  (1952).    The 
trophozoites  are  5  to  20jj.  in  diameter. 
The  cytoplasm  is  smoothly  granular  and 
filled  with  vacuoles  of  various  sizes.    The 
nucleus  is  large,  with  a  large,  central 
endosome  made  up  of  compact  granules 
and  a  conspicuous  row  of  chromatin  gran- 
ules of  different  sizes  around  its  periphery. 
The  cysts  are  4  to  14  p.  in  diameter  and 
contain  a  single  nucleus  when  mature. 
Their  chromatoid  bodies  are  irregular 
clumps  of  varying  size  and  rods,  splinters 
or  granules.    A  large  glycogen  vacuole 
may  or  may  not  be  present. 

Noble  and  Noble  (1952)  found  that  the 
uninucleate  entamoebae  from  the  feces  of 
cattle,  goats,  sheep  and  swine  were  mor- 
phologically indistinguishable.     However, 
since  their  physiological  characteristics 
have  not  been  studied  and  cross  infections 
have  not  been  attempted,  they  considered 
it  best  not  to  assign  them  all  to  the  same 
species.    If  future  work  should  show  that 
they  are  all  the  same,  their  correct  name 
would  be  E.  bovis. 


ENTAMOEBA   OVIS 
SWELLENGREBEL,   1914 


Richardson  (1934)  transferred  infec- 
tion from  chick  to  chick  by  association  in 
the  same  cage.    She  found  that  the  mini- 
mum oral  infective  dose  of  E.  gallinarum 
for  the  chick  was  240  cysts,  and  observed 
that  the  cysts  remained  viable  in  raw 
feces  for  10  days  and  in  feces  diluted  with 
water  for  at  least  28  days. 


ENTAMOEBA  BOVIS 
(LIEBETANZ,   1905) 

Synonym:     Amoeba  bovis. 

This  non- pathogenic  species  occurs 
commonly  in  the  rumen  and  feces  of  cattle 
thruout  the  world.    Noble  and  Noble  (1952) 
found  it  in  the  feces  of  all  of  34  cattle 
from  California,   Pennsylvania,  Korea 
and  Japan.    Mackinnon  and  Dibb  (1938) 


Synonym:     Entamoeba  debliecki,  pro 
parte". 

This  non- pathogenic  species  was  first 
described  from  the  intestines  of  sheep  in 
Sumatra,  but  it  is  common  thruout  the 
world.     Noble  and  Noble  (1952)  found  it  in 
the  feces  of  all  of  25  sheep  from  California 
and  Washington.     Triffitt  (1926)  reported 
it  from  the  feces  of  the  sable  antelope 
{Hippotragiis  niger)  and  common  water- 
buck  (  Cobus  ellipsiprymus)  in  Africa. 

By  a  historical  accident,  the  name  of 
the  pig  entamoeba  rather  than  that  of  the 
sheep  entamoeba  has  been  used  for  the 
entamoeba  of  the  goat.    Nieschulz  (1923) 
gave  the  first  description  of  E.  debliecki 
(a  synonym  of  E.  snis)  from  the  pig  and 
soon  after  (1923a)  found  what  appeared  to 
be  the  same  species  in  the  large  intestine 


146 


THE  AMOEBAE 


of  the  goat  in  Holland.    Hoare  (1940)  found 
it  in  the  feces  of  10  out  of  14  goats  in 
England  and  redescribed  it  under  the  name 
E.  deblieclii.     Noble  and  Noble  (1952) 
found  it  in  the  feces  of  27  out  of  28  goats 
in  the  United  States  and  called  it  E.  fiolecki 
(the  name  they  used  for  the  pig  entamoeba). 
However,  they  considered  the  uninucleate 
entamoebae  of  cattle,  goats,  pigs  and 
sheep  to  be  morphologically  indistinguish- 
able.   Since  goats  share  a  great  many 
parasites  with  sheep  but  relatively  few 
with  swine,  and  in  the  absence  of  cross- 
infection  experiments  to  the  contrary,  the 
best  name  for  the  goat  entamoeba  is  E. 
ovis . 

The  trophozoites  of  E.  ovis  measure 
11  to  12  by  13  to  14  ji.    The  nucleus  typ- 
ically contains  a  large,  pale  endosome 
generally  composed  of  several  granules, 
a  ring  of  peripheral  chromatin,  and  num- 
erous small  granules  between  the  endo- 
some and  the  nuclear  membrane.    In 
some  cases  there  is  very  little  peripheral 
chromatin  and  in  others  the  endosome 
may  be  very  small.    The  cysts  are  4  to 
13|Lx  in  diameter  with  a  mean  of  7|j.  and 
contain  a  single  nucleus  when  mature. 
They  usually  contain  numerous  chromatoid 
bodies  of  varying  size,  shape  and  abun- 
dance and  a  glycogen  vacuole. 

The  cysts  of  the  form  from  the  goat 
are  4  to  13fi  in  diameter.     Hoare  (1940) 
found  2  races  which  differed  in  size.    The 
cysts  of  one  ranged  from  5  to  9|j  in  diam- 
eter with  a  mode  of  6.  7  p. ,  while  the  cysts 
of  the  other  ranged  from  9  to  13^  with  a 
mode  of  10.4fi  Noble  and  Noble  (1952), 
however,  found  only  a  single  race  with 
cysts  ranging  in  diameter  from  4  to  12/:i 
with  a  mean  of  6.  4  /i . 

It  is  quite  likely  that  E.  ovis  is  a 
synonym  of  E.  hovis,    but  until  cross  in- 
fection experiments  have  been  carried 
out,  it  is  thought  best  to  retain  it  as  a 
separate  species. 


ENTAMOEBA  DILIMANI 
NOBLE,   1954 

Noble  (1954)  found  this  species  in  the 
feces  of  all  of  12  goats  he  examined  on 


Luzon  in  the  Philippines.     He  saw  only  2 
trophozoites.    They  were  12/1  across,  had 
broad,   rounded  pseudopods  whose  ends 
had  fairly  clear  ectoplasm,   and  food  vac- 
uoles containing  bacteria.     The  cysts  are 
5  to  16/i  in  diameter  with  a  mean  of  9.  7/i , 
and  contain  a  single  nucleus.     The  endo- 
some is  usually  a  small,  central  dot  but 
may  be  eccentric.     Peripheral  chromatin 
is  often  absent  or  may  appear  as  a  few 
large,  irregular  granules.     The  entire 
nucleus  is  filled  with  fine  granules  which 
may  form  a  ring  around  the  endosome. 
The  cyst  contains  1  or  more  large  glycogen 
vacuoles  and  from  one  to  a  large  number  of 
chromatoid  bodies  varying  in  shape  from 
small,   irregular  masses  to  a  single,  large, 
sausage-shaped  body.    Noble  considered 
this  species  to  differ  from  the  Entamoeba 
in  American  goats  in  that  the  peripheral 
chromatin  rarely  forms  a  heavy  ring,  the 
endosome  is  usually  a  single,  small  dot, 
and  a  periendosomal  ring  of  chromatin  is 
usually  present. 


ENTAMOEBA   SUIS 
HARTMANN,   1913 

Synonym:     Entamoeba  debliecki,  pro 
parte. 

A  number  of  authors  have  used  the 
name.  Entamoeba  polecki  Prowazek, 
1912,  for  this  species,  but  this  name  must 
be  considered  a  nomen  nudum  because 
Prowazek' s  description  was  so  poor  as  to 
be  unrecognizable  (see  Hoare,   1940,  1959). 

E.  siiis  occurs  in  the  cecum  and  colon 
of  swine.     Chang  (1938)  found  it  in  71%  of 
209  pigs  in  China.     Pavloff  (1935)  found  it 
in  26  of  1840  pigs  in  France  and  Bulgaria. 
Simitch  et  al.  (1959)  found  it  in  8%  of  1800 
pigs  in  Yugoslavia.     Frye  and  Meleney 
(1932)  found  it  in  63%  of  80  pigs,  Alicata 
(1932)  found  it  in  43%  of  35  pigs,  and  Noble 
and  Noble  (1952)  found  it  in  all  of  30  pigs 
in  the  United  States.    Mackinnon  and  Dibb 
(1938)  found  it  in  the  European  wild  boar 
{Stis  scrofa),  giant  forest  hog  (Hylochoerus 
meinertzliageni)  and  Indian  boar  (Sus 
cristatiis)  in  a  London  zoo.    Kessel  and 
Johnstone  (1949)  and  Kessel  and  Kaplan 
(1949)  reported  "E.  polecki"  from  the 
rhesus  monkey  but  remarked  that  it 


THE  AMOEBAE 


147 


appeared  identical  with  E.  chattoni  of 
monkeys;  this  is  the  species  to  which  their 
form  should  be  assigned.     Ten  human  in- 
fections have  been  reported  (Kessel  and 
Johnstone,   1949;  Lawless,   1954;  Burrows 
and  Klink,   1955).     However,  altho  no 
human  cross-infection  experiments  have 
been  attempted,  E.  suis  does  not  seem  to 
be  readily  transmissible  to  man.     Chang 
(1939)  observed  that  it  was  not  present  in 
27  Chinese  butchers,  altho  their  methods  of 
slaughtering  provided  ample  opportunity  for 
infection.     Pavloff  (1935)  was  unable  to  in- 
fect kittens  with  it  by  intrarectal  inoculation. 

E.  suis  has  been  described  by  a  num- 
ber of  authors,  including  Noble  and  Noble 
(1952)  in  domestic  animals,  and  by  Bur- 
rows (1959)  in  man.     The  following  des- 
cription is  based  on  Noble  and  Noble. 
The  trophozoites  are  5  to  25fi  long.    Some 
authors  (e.  g. ,  Hoare,  1959;  Simitch  et  al. 
1959)  have  considered  the  small  forms  to 
be  a  separate  species,  E.  debliecki,  but 
such  a  separation  does  not  appear  to  be 
justified. 

The  nucleus  varies  in  appearance. 
The  endosome  is  central  and  is  usually 
quite  large.    It  may  sometimes  almost  fill 
the  nucleus,  but  it  may  also  sometimes  be 
small  and  similar  to  that  of  E.  histolytica. 
There  is  a  rather  homogeneous  ring  of 
peripheral  chromatin  within  the  nuclear 
membrane.    There  are  ordinarily  no 
chromatin  granules  between  the  endosome 
and  the  peripheral  ring.     The  cytoplasm 
is  granular  and  vacuolated,  and  contains 
bacteria  in  its  food  vacuoles.    The  cysts 
are  4  to  17  ju  in  diameter  and  have  a 
single  nucleus  when  mature.    The  chroma- 
toid  bodies  in  the  cysts  vary  markedly  in 
shape  from  stout  rods  with  rounded  ends 
similar  to  those  of  E.  histolytica  to  irreg- 
ular granules  of  varying  size.    There  may 
or  may  not  be  a  glycogen  vacuole.     Cysts 
without  chromatoid  bodies  or  glycogen 
vacuoles  are  also  common. 


(1934)  observed  amoebae  associated  with 
necrosis  in  sections  of  the  colon  of  pigs 
which  had  died  of  experimental  hog  chol- 
era.    However,  altho  E.  suis  is  very 
common  in  swine,  it  has  never  been  found 
in  sections  of  intestinal  lesions  of  hundreds 
of  swine  examined  by  University  of  Illinois 
pathologists. 

E.  suis  can  be  cultivated  in  the  usual 
media.    It  is  apparently  less  sensitive 
than  E.  histolytica  to  amoebicidal  drugs, 
but  Frye  and  Meleney  (1932)  eliminated  it 
from  pigs  by  feeding  50  mg/kg  carbarsone 
in  the  milk  daily  for  10  days. 


ENTAMOEBA  BUBALUS 
NOBLE,   1955 

Noble  (1955)  found  this  species  in  the 
feces  of  12  of  15  carabao  (Bubalus  bubalis) 
from  several  islands  in  the  Philippines. 
Only  2  trophozoites  were  seen.     They 
averaged  12 /ii  in  diameter.    The  cysts  are 
5  to  9  fi  in  diameter  with  a  mean  of  8  jll  . 
They  contain  1  or  more  vacuoles,  but 
usually  a  single  large  one  which  crowds 
the  cyst  contents  to  its  periphery.     The 
chromatoid  bodies  are  usually  small  and 
irregular  in  shape  but  may  occasionally 
be  large,  with  rounded  ends,  similar  to 
those  of  E.  histolytica.     The  cysts  contain 
a  single  nucleus  2.  6ju  in  diameter  with  a 
large  endosome  1.4jj.  in  diameter  which 
often  appears  to  be  a  cluster  of  4  granules. 
There  is  usually  a  distinct  peripheral  ring 
of  chromatin,  but  the  amount  of  peripheral 
chromatin  may  vary  from  practically  none 
to  a  ring  of  dots  to  a  few  isolated  clumps. 
There  is  no  periendosomal  chromatin. 
Noble  (1955)  considered  E.  bubalus  to 
differ  from  other  entamoebae  with  uninu- 
cleate cysts  in  the  character  of  its  nucleus-- 
the  heavy,  usually  uniform  outer  ring  of 
chromatin  and  the  large,  prominent  endo- 
some. 


E.  suis  is  probably  non- pathogenic. 
Smith  (1910)  found  amoebae  in  sections  of 
intestinal  ulcers  in  swine.     Hartmann 
(1913),  who  studied  Smith's  preparations, 
named  the  amoeba  E.  suis.    Ratcliffe 


ENTAMOEBA   CHATTONI 
SWELLENGREBEL,   1914 


parte. 


Synonym:     Entamoeba  polecki,  pro 


148 


THE  AMOEBAE 


This  species  occurs  in  the  large  in- 
testine of  macaques  and  a  number  of  other 
monkeys.    It  was  first  seen  by  Chatton 
(1912),  who  called  it  Loeschia  sp.  ,  and 
was  given  its  present  name  by  Swellengre- 
bel  (1914),  who  found  it  in  the  rhesus 
monkey.     This  name  was  thought  to  be  one 
of  the  many  synonyms  of  E.  histolytica 
until  Salis  (1941)  showed  that  it  was  not. 
Kessel  and  Johnstone  (1949)  found  E. 
chattoni  and  E.  polecki  to  be  morphologi- 
cally similar,   and  used  the  older  name, 
E.  polecki,  for  the  species.     However, 
in  the  absence  of  cross-infection  exper- 
iments between  pigs  and  monkeys,  it  is 
best  to  retain  the  name,  E.  cliattoni,    for 
the  monkey  form.    In  any  case,  E.  polecki 
is  a  nomen  nudum  and  should  be  replaced 
by  E.  suis.     The  proper  name  for  the 
forms  in  the  10  human  cases  which  have 
been  reported  (see  Burrows  and  Klink, 
1955)  is  uncertain.     Perhaps  it  should  de- 
pend in  each  case  on  the  source  of  infec- 
tion, whether  pig  or  monkey,  or  perhaps 
both  these  names  will  eventually  be 
dropped  in  favor  of  E.  bovis.     However, 
for  the  present  E.  chattoni  is  preferable. 

E.  chattoni  is  probably  much  more 
common  in  monkeys  than  E.  histolytica, 
from  which  it  must  be  distinguished. 
Mudrow-Reichenow  (1956)  found  it  in  6  of 
7  rhesus  monkeys  in  Germany.    The 
trophozoites  of  E.  cliattoni  are  9  to  25 /i 
long.    The  cysts  are  6  to  18fi  in  diam- 
eter.   Salis  described  two  size  races 
with  cysts  averaging  10.  9  and  13. 1  fj. , 
respectively  but  other  workers  have  not 
made  this  differentiation.     The  nucleus 
varies  a  great  deal  in  morphology.    It 
may  be  indistinguishable  from  that  of  E. 
histolytica,  with  a  small,  central  endo- 
some  and  a  row  of  fine,  peripheral  chro- 
matin granules.     On  the  other  hand,  the 
endosome  may  be  large  or  small,  central 
or  eccentric,   compact  or  diffuse,  and 
composed  of  one  to  many  granules,  while 
the  peripheral  chromatin  may  be  fine  or 
coarse,  uniform,   irregular  or  diffuse, 
and  there  may  or  may  not  be  chromatin 
granules  between  the  endosome  and  the 
peripheral  chromatin.     The  cysts  are 
almost  always  uninucleate  when  mature. 
Less  than  1%  are  binucleate,  and  they  are 
never  tetranucleate.    The  chromatoid 


bodies  are  usually  irregular  and  small, 
but  may  also  be  rod-shaped  with  round  or 
pointed  ends,  oval  or  round.     A  glycogen 
vacuole  may  or  may  not  be  present. 

E.  cliattoni  is  generally  considered 
non- pathogenic,  altho  2  of  the  human  pa- 
tients studied  by  Burrows  and  Klink  (1955) 
had  diarrhea  which  may  or  may  not  have 
been  caused  by  the  amoebae. 


ENTAMOEBA  GINGIVA  LIS 
(GROS,   1849) 
BRUMPT,   1914 

Synonyms:     Amoeba  gingivalis , 
Amoeba  buccalis.  Entamoeba  buccalis. 
Amoeba  dentalis.  Amoeba  kartulisi,  Enta- 
moeba maxillaris.  Entamoeba  canibuc- 
calis. 

This  species  occurs  commonly  in  the 
human  mouth,  where  it  lives  between  the 
teeth,  in  the  gingival  margins  of  the  gums 
and  in  the  tartar.    It  has  occasionally  been 
found  in  infected  tonsils.     E.  gingivalis 
is  present  in  perhaps  50%  of  all  humans, 
but  in  up  to  95%  of  those  with  pyorrhea. 
It  was  once  thought  to  be  the  cause  of 
pyorrhea,  but  is  now  known  to  be  a  harm- 
less commensal  which  finds  an  ideal  home 
in  diseased  gums. 

Hinshaw  (1920)  transmitted  E.  gingi- 
valis to  5  dogs  with  gingivitis.    In  one  of 
them  the  infection  was  still  present  after 
14  1/2  months,  but  in  the  others  it  died 
out  within  4  months.    Kofoid,   Hinshaw  and 
Johnstone  (1929)  established  persistent  in- 
fections in  5  of  11  dogs  with  E.  gingivalis 
from  cultures.     They  could  not  infect  dogs 
with  healthy  mouths,  but  only  those  with 
gingivitis,   pus  pockets  or  loose  gums. 

Goodrich  and  Moseley  (1916)  found 
amoebae  indistinguishable  from  E.  gingi- 
valis in  pyorrheic  ulcers  in  the  mouths  of 
2  dogs  and  a  cat  in  England.     N6ller(1922) 
found  it  in  dogs  in  Germany.    Simitch 
(1938)  found  a  small  amoeba  in  the  saliva 
of  3  out  of  165  dogs  in  Serbia  and  named 
it  E.   canibuccalis.    The  trophozoites 
were  8  to  IGja  long  but  became  as  long  as 
2 5 /J  in  culture.    Simitch  infected  2  old 


THE  AMOEBAE 


149 


dogs  with  cultured  protozoa  but  failed  to 
infect  3  young  dogs,  a  young  wolf  and  2 
humans.     In  view  of  the  affection  with 
which  some  dog  and  cat  owners  treat  their 
pets,  there  is  no  reason  to  believe  that  the 
entamoebae  in  the  mouths  of  these  animals 
are  a  different  species  from  that  of  man. 


no  cysts.    Simitch  (1938a)  was  unable  to 
infect  horses  with  E.  gingivalis  (syn.  , 
E.   canibuccalis  )  from  the  dog  or  to  infect 
dogs  with  the  horse  form.     Hence  he  con- 
sidered the  latter  to  be  a  new  species. 
Further  study  is  needed  to  learn  whether 
this  view  is  correct. 


Kirby  (1928)  found  E.  gingivalis  in 
the  mouths  of  2  chimpanzees  with  pyorrhea. 
Kofoid,   Hinshaw  and  Johnstone  (1929) 
found  it  in  the  mouths  of  Macaco  mulatta 
and  M.  iriis.     Deschiens  and  Gourvil  (1930) 
found  it  in  the  M.  ))ii(latta  and  Papio 
sphynx.    Hegner  and  Chu  (1930)  found  it  in 
the  mouths  of  37  out  of  44  wild  M.  philip- 
pinensis. 

E.  gingivalis  has  no  cysts.     The  tro- 
phozoites are  usually  10  to  20j:i  long,  but 
may  range  from  5  to  35/^.     The  cytoplasm 
consists  of  a  zone  of  clear  ectoplasm  and 
granular  endoplasm  containing  food  vac- 
uoles.    The  amoebae  usually  feed  on  leuco- 
cytes, epithelial  cells,   sometimes  on  bac- 
teria and  rarely  on  red  blood  cells.    There 
are  usually  a  number  of  pseudopods.    The 
nucleus  is  2  to  4 |U  in  diameter,  with  a 
moderately  small  endosome,  a  peripheral 
layer  of  chromatin  granules  and  some  del- 
icate achromatic  strands  extending  from 
the  endosome  to  the  nuclear  membrane. 

Reproduction  is  by  binary  fission.    It 
was  described  in  detail  by  Child  (1926), 
Stabler  (1940)  and  Noble  (1947).     Child 
said  that  6  chromosomes  are  present,  but 
Stabler  and  Noble  found  only  5. 


ENTAMOEBA  EQUIBUCCALIS 
SIMITCH,   1938 

Synonym:     Entamoeba  gingivalis  va.r . 
eqiii. 

Nieschulz  (1924)  found  this  amoeba  in 
the  mouths  of  several  horses  in  Holland, 
and  Simitch  (1938a)  cultured  it  from  the 
mouths  of  16  out  of  22  mares  and  3  out  of 
4  donkeys  in  Serbia.    It  is  morphologically 
identical  with  E.  gingivalis,    except  that 
its  trophozoites  are  somewhat  smaller, 
measuring  7  to  14jj,  in  diameter.    It  has 


ENTAMOEBA   SUIGINGIVALIS 
TUMKA,   1959 

Tumka  (1959)  found  this  amoeba  on  the 
coating  of  the  teeth  of  6  out  of  32  domestic 
pigs  from  the  vicinity  of  Leningrad.    It  re- 
sembles E.  gingivalis  but  is  in  its  lower 
size  range,  measuring  7  to  12fi  with  a 
mean  length  of  9  jj,  when  fixed  and  stained. 
It  is  questionable  whether  this  is  a  sepa- 
rate species. 


ENTAMOEBA  CAUDATA 
CARINI  AND  REICHENOW,   1949 

This  species  was  found  in  the  feces 
of  a  dog  in  Brazil.    No  cysts  were  seen. 
The  trophozoites  were  10  to  36  fi  long. 
Their  pseudopods  and  nuclei  resembled 
those  of  E.  histolytica,   but  they  differed 
from  it  in  containing  many  ingested  bac- 
teria and  in  having  a  sac-like  appendage 
at  the  posterior  end  containing  dense, 
darkly  staining  cytoplasm  and  undigested 
bacteria. 


ENTAMOEBA   GEDOELSTI 
(HSIUNG,   1930) 

Synonym:     Endamoeba  gedoelsti. 

Hsiung  (1930)  found  this  amoeba  in 
the  cecum  or  colon  of  7  out  of  46  horses 
in  Iowa.    What  was  probably  the  same  spe- 
cies had  been  seen  in  the  horse  by  Gedoelst 
(1911)  in  Belgium  and  Fantham  (1920)  in 
South  Africa.     No  cysts  have  been  seen. 
The  trophozoites  are  7  to  13  |i  long  and 
contain  bacteria  in  their  food  vacuoles. 
The  nucleus  is  similar  to  that  of  E.  coli, 
with  an  eccentric  endosome  surrounded 
by  a  halo  and  a  row  of  peripheral  chromatin 
granules. 


ISO 


THE  AMOEBAE 


K 


M        N 


Q 


Fig.  21.      A.    Entcniioeha  bKlialiis   trophozoite.     B.    E.  bnluilus  cyst.     C.    Eiiliimocba 

chattoiii  Irophozoite.    D.    E.  clia I loni  cyst.     E.    E)ila»ioeba  gingivalis  tropho- 
zoite from  dog.     F.    Entamoeba  gedoelsti  trophozoite.    G.    Eiilaiiioeba  caudata 
trophozoite.     H.    lodaiiioeba  biictschlii  trophozoite.    I.    /.   buctschlii  cyst. 
J.   Entamoeba  cqiiibiiccalis  trophozoite.     K.    Eiidolimax  nana  trophozoite. 
L.   E.  nana  cyst.     M.    Endolima.x  grcgarini/ormis  trophozoite.     N.    E.  greg- 
ariniformis  cyst.    X  1700.     (From  Hoare,   1959,   in   Veterinary  Reiiens  and 
Annotations).    O.    Vahlkanipfia  lobospinosa  trophozoite.     P.    V.  lobospinosa 
cyst.    X  1050.     (From  Becker  and  Talbott,   1927).    Q.    Dientamoeba  fragilis 
trophozoite.    X  1700.     (From  Wenrich,   1944,  J.  Morph.   74:467) 


THE  AMOEBAE 


151 


ENTAMOEBA   CAPRAE 
FANTHAM,   1923 

Fantham  (1923)  described  this  species 
from  the  intestine  and  reticulum  of  a 
lightly  infected  goat  in  South  Africa.    It  is 
very  large,  one  streaming  individual 
measuring  34  by  24  jn.     The  pseudopods 
are  short  and  lobose,  and  red  cells  may 
be  ingested.    The  nucleus  is  oval,  9  to 
10 /i  in  diameter,  with  an  eccentric  endo- 
some.     No  cysts  were  seen.    The  relation- 
ship of  this  form  to  other  goat  amoebae 
remains  to  be  determined. 


papio,  kra  monkey,  green  monkey,  Anubis 
baboon,  Gelada  baboon  and  mandrill, 
(Mackinnon  and  Dibb,  1938;  Wenrich,  1937). 
In  addition,  Mackinnon  and  Dibb  (1938) 
found  this  species  in  the  giant  forest  hog, 
Hyloclioerus  meintritz-hageni.    Smith 
(1928)  infected  rats  with  /.   buetschlii 
from  man,  and  Pavloff  (1935)  did  so  with 
a  strain  from  the  pig.     However,  Simitch 
et  al.   (1959)  were  unable  to  infect  man 
with  cysts  from  fresh  pig  feces  or  to  infect 
the  pig  with  cysts  from  fresh  human  feces; 
they  gave  no  details  of  their  experiments. 

Location:     Cecum  and  colon. 


ENTAMOEBA  SP. 

Brenon  (1953)  tabulated  3  deaths  from 
amoebic  dysentery  among  the  causes  of 
death  he  observed  in  1005  chinchillas  in 
California.    Since  the  amoebae  of  chin- 
chillas have  apparently  not  been  described, 
they  cannot  be  assigned  to  any  species. 


Genus  lOD AMOEBA  Dobell,  1919 

In  this  genus  the  nucleus  is  vesicular, 
with  a  large  endosome  rich  in  chromatin, 
a  layer  of  lightly  staining  globules  sur- 
rounding the  endosome,   and  some  achro- 
matic strands  between  the  endosome  and 
nuclear  membrane.    The  cysts  contain  a 
large  glycogen  body  which  stains  darkly 
with  iodine.     They  are  ordinarily  uninu- 
cleate.   This  genus  occurs  in  vertebrates. 
A  single  species  is  recognized. 


lOD AMOEBA  BUETSCHLII 
(VON  PROWAZEK,   1912) 
DOBELL,   1919 

Synonyms:     Entamoeba  williamsi 
pro  parte,  Endoliniax  williamsi,  Endo- 
limax  pileonucleatus,  lodamoeba  wenyoni, 
lodamoeba  suis,  Endolimax  kueneni. 

Hosts:      Pig,  man,  chimpanzee,  gor- 
illa, macaques  and  other  monkeys  and 
baboons,  including  Macaca  mulatta,  M. 
irus,  M.  sancti-johannis,  M.  lasiotis, 
M.  philippinensis ,   Cercocebus  aethiops, 
Cercopithecus  mona,   C.  ascanius,  Papio 


Geographic  Distribution:     Worldwide. 

Prevalence:    /.  buetschlii  is  the  com- 
monest amoeba  of  swine,  and  the  pig  was 
probably  its  original  host.     Frye  and 
Meleney  (1932)  found  it  in  24%  of  127  pigs 
in  Tennessee.     Alicata  (1932)  found  it  in 
25%  of  35  pigs  in  the  U.  S.     Cauchemez 
(1921)  estimated  that  it  was  present  in  50 
to  60%  of  the  pigs  he  examined  in  France. 
Noller  (1922)  found  it  in  about  20%  of  those 
he  examined  in  Germany.     Pavloff  (1935) 
found  it  in  29%  of  530  pigs  in  France  and 
30%  of  1310  pigs  in  Bulgaria.    Simitch 
et  al.   (1959)  found  it  in  8%  of  1800  pigs  in 
Yugoslavia.    Kessel  (1928a)  found  it  in 
42%  of  the  pigs  he  examined  in  China,  and 
Chang  (1938)  found  it  in  51%  of  209  pigs  in 
China. 

According  to  Belding  (1952),  I.  buet- 
schlii was  found  in  8.  4%  of  17,  568  persons 
in  20  surveys  thruout  the  world,  and  in  4% 
of  the  people  in  American  surveys.    Wen- 
rich  (1937)  found  it  in  44%  of  55  apes  and 
monkeys  which  he  examined. 

Morphology:     Wenrich  (1937),  among 
others,  has  studied  the  morphology  of  /. 
buetschlii.     The  trophozoite  is  usually  9 
to  14/1  long  but  may  range  from"  4  to  20 /x. 
It  has  clear,  blunt  pseudopods  which  form 
slowly,  and  it  moves  rather  slowly.     The 
ectoplasm  is  clear,  but  not  well  separated 
from  the  granular  endoplasm.     Food  vac- 
uoles containing  bacteria  and  yeasts  are 
present  in  the  cytoplasm.    The  nucleus  is 
relatively  large,  and  ordinarily  contains 
a  large,  smoothly  rounded,  central 


152 


THI  AMOEBAE 


endosome  surrounded  by  a  vesicular  space 
containing  a  single  layer  of  periendosomal 
granules  about  midway  between  the  endo- 
some and  the  nuclear  membrane.     Fibrils 
extend  to  the  nuclear  membrane,  but 
there  are  no  peripheral  granules  inside 
the  membrane.    Stabler  (1945)  described 
tube-like  processes  which  may  be  used 
for  feeding  in  12%  and  27%,   respectively, 
of  the  trophozoites  of  2  human  strains. 

The  cysts  are  often  irregular  in  form. 
They  are  usually  8  to  lOji  long,  but  may 
range  from  5  to  14  fi.     They  contain  a 
single  nucleus  in  which  the  periendosomal 
granules  have  usually  aggregated  into  a 
crescent-shaped  group  at  one  side  of  the 
endosome,   pushing  it  to  one  side.     They 
contain  a  large,  compact  mass  of  glycogen 
which  stains  deeply  with  iodine.     The  gly- 
cogen disappears  after  8  to  10  days  in 
feces  held  at  room  temperature,  and  at 
the  same  time  the  cysts  die  and  disinte- 
grate (von  Brand,   1932).     There  are  no 
chromatoid  bodies  in  the  cysts,  but  they 
may  contain  small,  deeply  staining  gran- 
ules something  like  volutin  granules. 

Life  Cycle:     /.   buelschlii  reproduces 
by  binary  fission.     Pan  (1959)  studied  nu- 
clear division  in  the  trophozoites.     He 
considered  the  process  unique;  his  paper 
should  be  read  for  the  details.     The  hap- 
loid  number  of  chromosomes  is  usually 
more  than  10--possibly  12. 

Pathogenesis:     /.  buelschlii   is  non- 
pathogenic except  under  unusual  circum- 
stances.   These  have  never  been  noted  in 
the  pig,  but  Andrew  (1947)  reported  symp- 
toms similar  to  those  of  chronic  E.  Iiislo- 
lytica  in  a  few  persons,  and  Derrick  (1948) 
described  a  fatal  generalized  infection  in 
a  Japanese  soldier  captured  in  New  Guinea 
in  which  there  were  ulcers  in  the  stomach, 
small  intestine,   large  intestine,  lymph 
nodes,  lungs  and  brain. 

Bionomics  and  Epidemiology:     /. 
buelschlii,  like  other  intestinal  amoebae, 
is  transmitted  by  cysts. 

Cultivation:     This  species  can  be  cul- 
tivated in  the  usual  media. 


Treatment:     Little  is  known  about 
treatment  for  /.  buelschlii,   but  it  can  be 
eliminated  by  emetine. 

Prevention  and  Control:     The  same 
preventive  measures  recommended  for 
E.  hislolylica  will  also  prevent  /.  buel- 
schlii infections. 


Genus  ENDOUMAX   Kuenen   and 
Swellengrebel,    1917 

These  are  small  amoebae.    The  nu- 
cleus is  vesicular,  with  a  comparatively 
large,  irregularly  shaped  endosome  com- 
posed of  chromatin  granules  embedded  in 
an  achromatic  ground  substance,  and  with 
several  achromatic  threads  connecting  the 
endosome  with  the  nuclear  membrane. 
Cysts  are  present.     This  genus  occurs  in 
both  vertebrates  and  invertebrates. 


ENDOLIMAX  NANA 

(WENYON  AND  O'CONNOR,   1917) 

BRUG,   1918 

Synonyms:     Amoeba  Umax.   Enta- 
moeba nana,  Endolimax  inteslinalis, 
Endolimax  cynomolgi,  Endolimax  suis, 
Councilmania  tenuis . 

Hosts:     Man,   pig,  gorilla,   chimpan- 
zee,  gibbon,  macaques  and  other  monkeys 
and  baboons,  including  AJacaca  mulalta, 
M.   irus,  M.  sinica,  M.  sancti-johannis, 
M.   lasiotis,  M.  philippinensis,  Papio 
papiu,   Cercocebus  aethiops,   Cercopith- 
ecus  asca)iius,   Gamadyillns  sp.  ,  and 
Erytlirocebns  patas  (see  Mackinnon  and 
Dibb,   1938).     These  authors  also  reported 
a  morphologically  indistinguishable  form 
from  the  capybara  [Hydrochoerus  capybara) 
and  tree  porcupine  (Coendou  prehensilis). 

It  is  quite  likely  that  E.  ratti  (see  be- 
low) may  be  a  synonym  of  E.  nana,  so  that 
the  latter's  host  range  may  be  even  broader 
than  that  given  above.    Chiang  (1925)  con- 
sidered E.  ratti  a  separate  species  because 
he  was  unable  to  infect  14  rats  with  E.  nana 
from  man.     However,  Kessel  (1928)  suc- 
ceeded in  doing  so,  and  Smith  (1928)  found 


THE  AMOEBAE 


153 


an  E.  naua-\i]^e  amoeba  in  4  of  63  rats 
which  had  been  fed  human  feces  but  did 
not  know  whether  it  had  already  been 
present  in  the  rats. 

Dobell  (1933)  transmitted  E.  nana 
from  Macaca  sinica  to  a  man  (himself) 
and  from  man  to  M.  mulatto.     Kessel 

(1928)  infected  M.  irus  with  E.  nana  from 
man.     However,  Simitch  et  al.  (1959)  were 
unable  to  infect  4  young  pigs  with  E.  nana 
from  man  and  consequently  named  the  pig 
form  E.  siiis;  they  gave  no  details  of  their 
experiments. 

Location:     Cecum,  colon.     Hegner 

(1929)  and  Dobell  (1933)  found  E.  nana  in 
the  vagina  of  macaques,  where  it  was 
most  likely  of  fecal  origin. 

Geographic  Distribution:     Worldwide. 

Prevalence:      E.  nana  is  common  in 
man.    According  to  Belding  (1952),  it  was 
found  in  20.  5%  of  18,  333  persons  in  20 
surveys  thruout  the  world  and  in  about 
14%  of  those  examined  in  the  United  States. 
Frye  and  Meleney  (1932)  found  it  in  5.  5% 
of  127  pigs  in  Tennessee,  Alicata  (1932) 
found  it  in  1  of  35  pigs  in  the  U.S.  ,  Kessel 
(1928)  found  it  in  14%  of  the  pigs  examined 
by  him  in  China,  and  Chang  (1938)  found 
it  in  15%  of  209  pigs  in  China.    Simitch 
et  al.  (1959)  found  it  in  8%  of  1800  pigs 
in  Yugoslavia. 

Morphology:     The  trophozoites  are 
6  to  15  p.  in  diameter  with  an  average  of 
10  ju.     They  move  sluggishly  by  means 
of  a  few  blunt,  thick  pseudopods.     The 
endoplasm  is  granular,  vacuolated  and 
contains  bacteria  and  crystals.    The  nu- 
cleus contains  a  large,  irregular  endo- 
some  composed  of  a  number  of  chromatin 
granules.    Several  achromatic  fibrils  run 
from  the  endosome  to  the  nuclear  mem- 
brane.    There  are  ordinarily  no  peripheral 
chromatin  granules,  but  Stabler  (1932) 
noted  that  they  are  formed  after  fixation 
in  Schaudinn's  fluid  containing  20%  acetic 
acid.     The  cysts  are  oval,  often  irregular, 
and  thin-walled;  they  are  usually  8  to  10  ^ 
long  but  may  range  from  5  to  14 /i.     The 
mature  cysts  contain  4  nuclei,  and  they 


may  contain  ill-defined  glycogen  bodies. 
They  have  no  chi'omatoid  bodies  but  may 
have  small  granules  resembling  volutin 
and  occasionally  a  few  filaments  of  uncer- 
tain nature. 

Life  Cycle:     Reproduction  is  by  binary 
fission  in  the  trophozoite  stage.    The 
amoeba  which  leaves  the  cyst  is  multinu- 
cleate, but  it  divides  into  uninucleate 
amoebulae  which  grow  into  ordinary  tropho- 
zoites. 

Pathogenesis:     E.  nana  is  non-patho- 
genic. 

Bionomics  and  Epidemiology:     E.  nana 
is  transmitted  in  the  same  way  as  other 
enteric  amoebae.    Dobell  (1933)  found  that 
its  cysts  could  live  at  least  2  weeks  at 
room  temperature  (15-24°  C)  and  at  least 
3  weeks  at  10°  C,  while  all  the  trophozoites 
died  in  24  hours  at  both  temperatures. 
Frye  and  Meleney  (1932)  found  E.  nana 
cysts  in  1  out  of  46  lots  of  flies  which  they 
examined  in  Tennessee. 

Cultivation:     This  species  can  be  cul- 
tivated in  the  usual  media. 

Treatment:     Little  is  known  about  the 
treatment  of  E.  nana.    Dobell  (1933)  and 
others  found  that  emetine  has  no  effect  on 
it. 

Prevention  and  Control:     The  same 
preventive  measures  recommended  for 
E.  histolytica  will  also  prevent  E.  nana 
infections. 


ENDOLIMAX  RATTI 
CfflANG,   1925 

This  species,  which  may  be  a  synonym 
of  E.  nana,   occurs  in  the  cecum  and  colon 
of  laboratory  and  wild  rats.    Andrews  and 
White  (1936)  found  it  in  1  out  of  2515  wild 
rats  in  Baltimore,  and  Baldassari  (1935) 
found  it  in  1  of  225  wild  rats  in  Toulon, 
France.     Chiang  (1925)  did  not  describe  it, 
but  merely  stated  that  it  was  morphologi- 
cally identical  with  E.  nana. 


154 


THE  AMOEBAE 


ENDOLIMAX  CAVIAE 
HEGNER,   1926 

This  species  occurs  commonly  in  the 
cecum  of  the  guinea  pig.     Hegner  (1926) 
found  it  in  Baltimore  and  Hegner  and  Chu 
(1930)  found  it  in  the  Philippines.     Nie 
(1950)  found  it  in  18%  of  84  guinea  pigs  in 
Pennsylvania.     It  is  somewhat  smaller 
than  E.  nana,   the  trophozoites  measuring 
5  to  11  by  5  to  8n  ,  but  otherwise  resem- 
bles it.    Nie  saw  one  specimen  with  an 
ingestion  tube.     The  cysts  are  apparently 
unknown. 


ENDOLIMAX  GREGARINIFORMIS 
(TYZZER,    1920) 
HEGNER,   1929 

Synonyms:  Pygolimax  gregarini- 
formis,  Endolimax  janisae,  EndoUtnax 
niimidae. 


large  number  of  chickens  he  examined  in 
Pennsylvania. 

The  trophozoites  of  E.  gregariniformis 
are  usually  4  to  13 /i  long  with  a  mean  of 
9  by  5^1 ,  altho  Hegner  (1929a)  found  a 
small  race  in  the  guinea  fowl.     The  tropho- 
zoites are  oval,  often  with  a  posterior  pro- 
tuberance, and  move  sluggishly.     The  ecto- 
plasm is  not  clearly  separated  from  the 
endoplasm.    The  food  vacuoles  contain  bac- 
teria.    The  nucleus  is  very  similar  to  that 
of  E.  nana  but  tends  to  have  a  larger  endo- 
some  and  a  more  apparent  nuclear  mem- 
brane, often  with  chromatin  granules  at 
the  juncture  of  the  achromatic  threads  with 
the  membrane.     The  cysts  have  4  nuclei 
when  mature;  they  measure  7  to  8  by  8  to 
11 /x  with  a  mean  of  10  by  7;i  (McDowell, 
1953).     They  tend  to  be  somewhat  lima 
bean- shaped  instead  of  truly  ovoid,  and 
are  often  highly  vacuolated. 


This  species  is  found  in  the  ceca  of 
the  chicken,  turkey,  guinea  fowl,  pheas- 
ant, domestic  goose,  domestic  duck  and 
various  wild  birds,  including  the  black 
duck  (Anas  riibripes  Iristis),  black- 
crowned  night  heron  (Nycticorax  nycti- 
corax)  and  screech  owl. 

E.  gregariniformis  was  first  des- 
cribed by  Tyzzer  (1920)  from  the  turkey; 
he  transmitted  it  easily  to  the  chicken. 
Hegner  (1926)  described  it  from  the 
chicken,  naming  it  E.  janisae.     Hegner 
(1929a)  found  the  same  species  and  an- 
other form  which  he  named  E.  numidae 
in  the  guinea  fowl.    The  latter  was 
smaller  than  E.  gregariniformis ,  aver- 
aging 4  by  3/i,  but  nevertheless  fell  within 
its  size  range  and  did  not  differ  from  it 
morphologically.     Hegner  (1929a)  infected 
chicks  with  both  sizes  of  Endolimax  irom 
the  guinea  fowl  and  also  with  Endolimax 
from  the  domestic  goose,  domestic  duck 
and  screech  owl.    Richardson  (1934)  in- 
fected chicks  with  Endolimax  from  the 
duck,  goose,  pheasant,  black  duck  and 
black-crowned  night  heron. 

E.  gregariniformis  occurs  thruout 
the  world  and  is  non-pathogenic. 
McDowell  (1953)  found  it  in  over  50%  of  a 


Genus  DIENTAMOEBA  Jepps  and 
Dobell,   1918 

These  are  small  amoebae,  usually 
with  2  nuclei.    The  nuclei  are  vesicular, 
with  a  delicate  membrane  and  an  endosome 
consisting  of  several  chromatin  granules 
connected  to  the  nuclear  membrane  by 
delicate  strands.    No  cysts  are  known. 
Dobell  (1940)  considered  that  this  genus 
might  be  an  aberrant  flagellate  closely 
related  to  Histomonas . 


DIENTAMOEBA  FRAGILIS 
JEPPS  AND  DOBELL,   1918 

This  species  occurs  in  the  cecum  and 
colon  of  man  and  also  of  some  monkeys. 
According  to  Belding  (1952),   it  was  found 
in  4.  2%  of  7120  persons  in  14  surveys 
thruout  the  world.     Hegner  and  Chu  (1930) 
found  D.  frag  His  in  2  out  of  44  Macaca 
philippinensis  in  the  Philippines,  and 
Knowles  and  Das  Gupta  (1936)  found  it  in 
1  out  of  4  M.  iriis  in  India.    In  addition. 
Noble  and  Noble  (1952)  mentioned  finding 
a  Dientamoeba  in  sheep  feces  in  California. 

Only  trophozoites  are  known  for  this 
species.    They  are  very  sensitive  to 


THE  AMOEBAE 


155 


environmental  conditions,  bursting  in 
water  and  becoming  degenerate  in  older 
fecal  samples.     In  order  to  identify  them, 
smears  of  fresh  feces  should  be  fixed  in 
Schaudinn's  fluid  containing  10  to  20% 
acetic  acid  or  in  Bouin's  fluid  and  stained 
with  iron  hematoxylin.     Their  morphology 
has  been  studied  by  Wenrich  (1936,   1939, 
1944)  and  Dobell  (1940),  whose  accounts 
do  not  always  agree. 

The  trophozoites  range  from  3  to  22  jj. 
but  are  usually  6  to  12  jn  in  diameter. 
The  ectoplasm  is  distinct  from  the  endo- 
plasm,  which  contains  food  vacuoles  filled 
with  bacteria,  yeasts,  starch  granules, 
and  parts  of  cells.    In  fresh  feces  there 
may  be  a  single  clear,  broad  pseudopod. 
About  3/5  of  the  protozoa  contain  2  nuclei 
which  are  connected  by  a  filament  or  des- 
mose.    This  appears  to  be  one  of  the  first 
structures  to  disappear  during  degenera- 
tion.    Each  nucleus  is  vesicular  and  has 
an  endosome  composed  of  4  to  8  granules 
from  which  a  few  delicate  fibers  radiate 
to  the  nuclear  membrane.     There  is  no 
peripheral  chromatin. 

Reproduction  is  by  binary  fission. 
There  are  4  chromosomes. 

At  one  time  D.  fragilis  was  thought 
to  be  non- pathogenic,  and  this  is  true  in 
most  cases.     However,  in  some  persons 
it  causes  a  mucous  diarrhea  and  gastro- 
intestinal symptoms.    It  does  not  invade 
the  tissues,  but  may  cause  low-grade  ir- 
ritation of  the  intestinal  mucosa,  excess 
mucus  secretion  and  hypermotility  of  the 
bowel.     There  may  be  mild  to  moderate 
abdominal  pain  and  tenderness  or  dis- 
comfort.   There  may  also  be  an  increase 
in  eosinophiles. 

The  mode  of  transmission  of  D.  fra- 
gilis is  not  clear,  since  there  are  no  cysts 
and  the  trophozoites  are  so  delicate. 
Dobell  (1940)  was  unable  to  infect  himself 
by  mouth  or  2  monkeys  by  mouth  or  rec- 
tally  and  suggested,  by  analogy  with  His- 
tomonas,   that  D.  fragilis   might  possibly 
be  transmitted  by  an  intestinal  nematode 
such  as  Trichuris.    This  idea  has  been 
partially  confirmed  by  Burrows  and 
Swerdlow  (1956),  who  found  small,  amoe- 


boid organisms  resembling  D.  fragilis  in 
the  eggs  of  Enterobius  vermicularis  and 
suggested  that  the  pinworm  might  be  the 
vector. 

D.  fragilis  can  be  readily  cultivated 
in  the  usual  culture  media.    It  is  sensitive 
to  most  amoebicidal  drugs,   including  car- 
barsone,  diodoquin  and  erythromycin. 

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Chapter  8 


THE 

TELOSPORASIdA 
AND  THE 

cocaviA 

PROPER 


All  members  of  the  class  Telospo- 
rasida  are  parasitic.     They  have  simple 
spores,  without  polar  filaments.     (The 
spore  has  been  lost  secondarily  in  a  few 
genera.  )    Each  spore  contains  1  to  many 
sporozoites.     Pseudopods,  cilia  and  fla- 
gella  are  absent,  except  for  flagellated 
microgametes  in  some  groups.     Locomo- 
tion is  by  body  flexion  or  gliding.    Repro- 
duction is  both  sexual  and  asexual,  and 
there  may  or  may  not  be  alternation  of 
generations.    Most  Telosporasida  are 
saprozoic,  but  a  few,   including  the  tropho- 
zoites of  the  malaria  parasite,  are  holo- 
zoic. 

Most  of  the  Telosporasida  probably 
arose  from  the  Mastigasida,  but  some  may 
have  arisen  from  the  Sarcodasida.     How- 
ever, it  is  difficult  to  be  sure  of  their 
origin  because  of  their  lack  of  the  usual 
organelles  of  locomotion. 

The  classification  of  this  and  related 
groups  is  still  the  subject  of  considerable 
difference  of  opinion  among  taxonomists, 
and  that  used  in  this  book  is  not  consid- 
ered definitive.    It  may  require  several 
generations  of  parasitologists  to  work  out 
a  universally  acceptable  one.    This  class 
is  divided  into  2  subclasses,  of  which  the 
Gregarinasina  parasitize  invertebrates 
and  the  Coccidiasina  occur  in  both  verte- 
brates and  invertebrates.    In  the  latter 
group,  the  mature  trophozoite  is  ordinar- 
ily intracellular  and  comparatively  small. 

The  coccidia  and  their  relatives  belong 
to  the  order  Eucoccidiorida.    In  this  order, 
schizogony  is  present  and  the  life  cycle 
involves  both  sexual  and  asexual  phases. 
Members  of  the  order  are  found  in  the 
epithelial  and  blood  cells  of  vertebrates 
and  invertebrates. 

The  coccidia  proper  belong  to  the  sub- 
order Eimeriorina,  which  is  differentiated 
from  the  other  2  suborders  by  several  fea- 
tures of  its  life  cycle.     The  macrogamete 
and  microgametocyte  develop  independently, 
the  microgametocyte  produces  many  micro- 
gametes,  the  zygote  is  not  motile,  and  the 


158 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


159 


NUMBER 
SPOROCYSTS 
PER      OOCYST 


NUMBER      SPOROZOITES     PER      SPOROCYST 
I  2  3  4  8  16  n 


0 


8 


16 


u  I); 


^SClV 


^■M^i>' 


: ;  II  i ! 


CYCLOSPORA 


OCTOSPORELLA 


III;; 


■-iihOii); 


PFEIFFERINELLA 

CRYPTDSPORIDIUy       ^?l^,y-*5**'* 
iiZZERlA 


ISOSPORA  00RI51ELLA 

WENYONELLA 


PYTHONELLA 


-'JSa®' 


I  I  I  I  \ 


\  ^vy^''  / 


[^^.\\y\[{\l>]  iSJii;    ^ii'j 


Fig.  22.      Numbers  of  sporocysts  per  oocyst  and  of  sporozoites  per  sporocyst  in  the 

genera  of  the  suborder  Eimeriorina.     (In  the  genera  without  sporocysts,  the 
numbers  of  sporozoites  per  oocyst  are  given.  )    (Original) 


sporozoites  are  typically  enclosed  in  a 
sporocyst.    All  the  coccidia  of  domestic 
animals  and  man,  with  one  possible  ex- 
ception, belong  to  two  families,  the 
Eimeriidae  and  Cryptosporidiidae.    An- 
other family,  the  Lankesterellidae,  is  of 
considerable  interest.     Becker  (1934) 
wrote  a  classic  review  of  the  coccidia. 
Orlov  (1956)  discussed  those  of  domestic 
animals,  but  was  seriously  handicapped 
by  lack  of  information  about  non- Russian 
work.    Becker  (1956)  and  Pelle'rdy  (1956, 
1957)  have  given  checklists  of  the  species 
of  coccidia.    The  coccidia  of  the  avian 


orders  Galliformes,  Anserlformes  and 
Charadriiformes  were  reviewed  by  Levine 
(1953). 


FAMILY   EIMERIIDAE 

Members  of  this  family  have  a  single 
host.  Schizogony  and  gametogony  take 
place  within  the  host  cells,  and  sporogony 
ordinarily  occurs  outside  the  host's  body. 
The  oocysts  and  schizonts  lack  an  attach- 
ment organ.  The  oocysts  contain  0,  1,  2, 
4  or  many  sporocysts,  each  containing  1 


160 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


MICROPYLE    CAP 
MICROPYLE 


SPORULATED 
EIMERIA   OOCYST 


POLAR    GRANULE 
STIEOA    BODY 

SMALL    REFRACTILE    GLOBULE 
IN   SPOROZOITE 

LARGE    REFRACTILE    GLOBULE 
IN   SPOROZOITE 

SPOROCYST 

OOCYST   RESIDUUM 
SPOROCYST    RESIDUUM 
SPOROZOITE    NUCLEUS 
SPOROZOITE 

INNER    LAYER   OF  OOCYST   WALL 
OUTER    LAYER   OF  OOCYST  WALL 


Fig.  23.      Structures  of  sporulated  Eiiiicria  oocyst. 
(Original) 

or  more  sporozoites.    The  microgametes 
have  2  flagella.    The  genera  are  differen- 
tiated by  the  number  of  sporocysts  in  their 
oocysts  and  the  number  of  sporozoites  in 
each  oocyst. 

Morphology.      The  morphology  of  a 
typical  oocyst,  that  of  Einieria,   is  shown 
in  Fig.   23.    The  oocyst  wall  is  composed 
of  1  or  2  layers  and  may  be  lined  by  a 
membrane.    It  may  have  a  micropyle, 
which  may  be  covered  by  a  micropylar 
cap.    Within  the  oocyst  in  this  genus  are 
4  sporocysts,  each  containing  2  sporozoites. 
There  may  be  a  retractile  polar  granule  in 
the  oocyst.    There  may  be  an  oocyst  resi- 
duum or  a  sporocyst  residuum  in  the  oocyst 
and  sporocyst,   respectively;  these  are  com- 
posed of  material  left  over  after  the  forma- 
tion of  the  sporocysts  and  sporozoites.    The 
sporocyst  may  have  a  knob,  the  Stieda  body, 
at  one  end.     The  sporozoites  are  usually 
sausage-  or  comma-shaped,  and  may  con- 
tain 1  or  2  clear  globules. 

Location.      Most  coccidia  are  intra- 
cellular parasites  of  the  intestinal  tract, 
but  a  few  occur  in  other  organs  such  as  the 
liver  and  kidney.     Each  species  is  usually 
found  in  a  specific  location  within  the  in- 
testinal tract;  some  are  found  in  the  cecum, 
others  in  the  duodenum,  still  others  in  the 
ileum,  etc.    They  may  invade  different 
cells  in  these  locations.    Some  species  are 
found  in  the  mucosal  cells  at  the  tips  of 


the  villi,  others  in  the  crypts  and  still 
others  in  the  interior  of  the  villi.     Their 
location  within  the  host  cell  also  varies. 
Some  species  are  found  above  the  host 
cell  nucleus,  while  others  are  found  be- 
neath it  and  a  few  occur  inside  it.    Some 
species  enlarge  the  host  cell  only  slightly, 
while  others  cause  it  to  become  enormous. 
The  host  cell  nucleus  is  also  often  greatly 
enlarged  even  tho  it  may  not  be  invaded. 

Life  Cycle:     The  life  cycles  of  the 
Eimeriidae  are  similar,  and  can  be  illus- 
trated by  that  of  Ei»ieyia  teiiella,  which  is 
found  in  the  ceca  of  the  chicken  (Fig.   24). 
It  was  first  worked  out  in  a  classic  paper 
by  Tyzzer  (1929).     The  oocysts  are  passed 
in  the  feces;  at  this  time  they  contain  a 
single  cell,  the  sporont.     They  must  have 
oxygen  in  order  to  develop  to  the  infective 
stage,  a  process  known  as  sporulation  or 
sporogony.     The  sporont,  which  is  diploid, 
undergoes  reduction  division  and  throws 
off  a  retractile  polar  body.     The  haploid 
number  of  chromosomes  is  2  (Walton, 
1959).     The  sporont  divides  to  form  4 
sporoblasts,   each  of  which  then  develops 
into  a  sporocyst.     Two  sporozoites  develop 
within  each  sporocyst.     Sporulation  takes 
2  days  at  ordinary  temperatures.     The 
oocysts  are  then  infective  and  ready  to 
continue  the  life  cycle. 

When  eaten  by  a  chicken,  the  oocyst 
wall  breaks,   releasing  the  sporozoites. 
The  factors  which  cause  excystation  have 
not  been  determined.     Itagaki  and  Tsubo- 
kura  (1958)  found  that  pancreatic  juice  did 
not  cause  excystation  of  E.   lenella,   and 
Landers  (1960)  was  unable  to  induce  ex- 
cystation by  treating  the  oocysts  of  E. 
nieschulzi  from  the  rat  with  pepsin,  tryp- 
sin,  pancreatin,   pancreatic  lipase  or  bile. 
Ikeda  (1960),   however,   reported  that  pan- 
creatic juice  did  cause  excystation  of  E. 
teiiella,  and  that  trypsin  was  the  respon- 
sible enzyme. 

According  to  Challey  and  Burns  (1959) 
and  Pattillo  (1959),  the  sporozoites  first 
enter  the  cells  of  the  surface  epithelium. 
Pattillo  (1959)  observed  passageways, 
which  he  called  penetration  tubes,  in  the 
striated  border  and  epithelium  thru  which 
the  sporozoites  passed.    They  deploy  along 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


161 


Fig.  24.      Life  cycle  of  the  chicken  coccidium,  Eimeria  tenella.     A  sporozoite  (1)  enters 
an  intestinal  endothelial  cell   (2),   rounds  up,  grows,  and  becomes  a  first  gen- 
eration schizont  (3).     This  produces  a  large  number  of  first  generation  mero- 
zoites  (4),  which  break  out  of  the  host  cell  (5),  enter  new  intestinal  endothelial 
cells  (6),   round  up,  grow,  and  become  second  generation  schizonts  (7,   8). 
These  produce  a  large  number  of  second  generation  merozoites  (9,   10),  which 
break  out  of  the  host  cell  (11).    Some  enter  new  host  intestinal  endothelial 
cells  and  round  up  to  become  third  generation  schizonts  (12,   13),  which  pro- 
duce third  generation  merozoites  (14).     The  third  generation  merozoites  (15) 
and  the  great  majority  of  second  generation  merozoites  (11)  enter  new  host 
intestinal  endothelial  cells.    Some  become  microgametocytes  (16,   17),  which 
produce  a  large  number  of  microgametes  (18).     Others  turn  into  macrogametes 
(19,   20).     The  macrogametes  are  fertilized  by  the  microgametes  and  become 
zygotes  (21),  which  lay  down  a  heavy  wall  around  themselves  and  turn  into 
young  oocysts.     These  break  out  of  the  host  cell  and  pass  out  in  the  feces  (22). 
The  oocysts  then  sporulate.     The  sporont  throws  off  a  polar  body  and  forms  4 
sporoblasts  (23),  each  of  which  forms  a  sporocyst  containing  2  sporozoites 
(24).    When  the  sporulated  oocyst  (24)  is  ingested  by  a  chicken,  the  sporo- 
zoites are  released  (1).     (Original) 


the  basement  membrane  and  then  pass 
thru  it  into  the  lamina  propria.     Here 
they  are  engulfed  by  macrophages  and 
carried  by  them  to  the  glands  of  Lieber- 
kuhn.     They  then  leave  the  macrophages 
and  enter  the  epithelial  cells  of  the  glands, 


where  they  are  found  below  the  host  cell 
nucleus,  i.e. ,  on  the  side  away  from  the 
lumen.    We  do  not  know  how  common  this 
method  of  penetration  is  among  the  coc- 
cidia;  Van  Doorninck  and  Becker  (1957) 
first  found  it  in  E.  necatrix  of  the  chicken. 


162 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


Once  in  a  glandular  epithelial  cell, 
each  sporozoite  rounds  up  and  becomes  a 
first  generation  schizont.     By  a  process 
of  asexual  multiple  fission  (schizogony), 
each  schizont  forms  about  900  first  gen- 
eration merozoites,  each  about  2  to  4/j. 
long.     These  get  their  name  from  the 
Greek  word  for  mulberry,  which  they  re- 
semble before  they  separate.    They  break 
out  into  the  lumen  of  the  cecum  about  2.  5. 
to  3  days  after  infection.     Each  first  gen- 
eration merozoite  enters  a  new  host  cell, 
and  rounds  up  to  form  a  second  generation 
schizont,  which  lies  above  the  host  cell 
nucleus.     By  multiple  fission  it  forms 
about  200  to  350  second  generation  mero- 
zoites about  IGfi  long.    These  are  found 
5  days  after  infection.    Some  of  them 
enter  new  intestinal  cells,   round  up  to  form 
third  generation  schizonts,  which  lie  be- 
neath the  host  cell  nuclei  and  produce  4  to 
30  third  generation  merozoites  about  7ji 
long. 

Most  of  the  second  generation  mero- 
zoites,  however,  enter  new  host  cells  and 
begin  the  sexual  phase  of  the  life  cycle, 
known  as  gametogony.    Most  of  these 
merozoites  turn  into  female  gametes  (ma- 
crogametes),  which  simply  grow  until  they 
reach  full  size.    Some  of  the  merozoites 
turn  into  male  gametocytes  (microgameto- 
cytes).     Both  the  macrogametes  and  mi- 
crogametocytes  lie  below  the  host  cell 
nuclei.    Within  each  microgametocyte  a 
large  number  of  tiny  biflagellate  micro- 
gametes  are  formed.    These  break  out 
and  fertilize  the  macrogametes. 

The  resultant  zygote  lays  down  a  wall 
around  itself  in  the  following  way:    The 
macrogametes  contain  one  or  two  layers 
of  eosinophilic  plastic  granules  in  their 
cytoplasm;  these  are  composed  of  muco- 
protein  (Kheisin,   1958).     They  pass  to  the 
periphery,  flatten  out  and  coalesce  to 
form  the  oocyst  wall  after  fertilization. 
The  formation  of  this  wall  marks  the 
transition  of  a  fertilized  macrogamete  into 
an  oocyst.    According  to  Monne  and  Honig 
(1954),  the  outer  layer  of  the  oocyst  wall 
is  a  quinone-tanned  protein  and  the  inner 
layer  is  a  lipid  coat  firmly  associated 
with  a  protein  lamella. 


The  oocysts  then  break  out  of  their 
host  cells,  enter  the  intestinal  lumen,  and 
pass  out  in  the  feces.    The  prepatent  per- 
iod, from  the  time  of  infection  to  the  ap- 
pearance of  the  first  oocysts  in  the  feces, 
is  7  days.     Oocysts  continue  to  be  dis- 
charged for  a  number  of  days  thereafter, 
due  to  the  fact  that  the  sporozoites  do  not 
all  enter  the  host  cells  immediately  but 
may  remain  in  the  lumen  for  some  time, 
and  also  because  many  of  them  are  retained 
in  a  plug  of  material  in  the  ceca  for  some 
days  before  they  are  eliminated. 

In  the  absence  of  reinfection,  coccidial 
infections  are  self-limiting.     Asexual  re- 
production does  not  continue  indefinitely  as 
it  does,  for  example,  in  Plasmodium.    In 
E.   tenella,  3  generations  of  merozoites  are 
produced;  in  other  species  there  may  be  1, 
2  or  4.    After  this,  the  life  cycle  enters  its 
sexual  phase;  the  oocysts  are  formed, 
eliminated  from  the  body,  and  the  infection 
is  over.    Reinfection  may  take  place,  but 
the  host  develops  more  or  less  immunity 
following  primary  infection. 

The  number  of  oocysts  produced  in  an 
animal  per  oocyst  fed  depends  in  part  on 
the  number  of  merozoite  generations  and 
the  number  of  merozoites  per  generation. 
A  single  oocyst  of  E.  tenella  containing  8 
sporozoites  is  theoretically  capable  of  pro- 
ducing 2,  520,  000  second  generation  mero- 
zoites (8  X  900  X  350),  each  of  which  can 
develop  into  a  macrogamete  or  micro- 
gametocyte. 

In  E.  bonis  of  cattle,  there  is  only  a 
single  asexual  generation,  but  a  giant 
schizont  containing  about  120,000  mero- 
zoites is  formed  (Hammond  et  al.   1946). 
In  the  rat,  E.  nieschidzi  is  theoretically 
capable  of  producing  1,  500,000  oocysts 
per  oocyst  fed,  E.  miyairii    38,016,  and 
E.  separata  only  1536  (Roudabush,   1937). 
In  E.  nieschulzi  there  are  4  generations  of 
merozoites,  while  in  the  latter  two  species 
there  are  only  3,  and  fewer  merozoites  are 
usually  produced  in  each  than  in  E.  nie- 
sclmlzi.    In  the  rabbit,  E.  magna  produces 
800,000  oocysts  per  oocyst  fed,  E.  media 
produces  150,000  and  £.  coecicola  100,000 
(Kheisin,   1947,   1947a). 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


163 


The  actual  numbers  of  oocysts  pro- 
duced per  oocyst  fed  are  usually  consider- 
ably lower  than  the  theoretical  ones.    K 
the  host  is  resistant  or  immune,  it  des- 
troys many  merozoites,  and  many  others 
pass  out  in  the  feces  before  they  have  time 
to  enter  host  cells.    The  infecting  dose  is 
also  an  important  factor  in  determining 
the  number  of  oocysts  produced.     The 
greater  the  infecting  dose,  the  smaller  the 
number  of  oocysts  usually  produced  per 
oocyst  fed.     For  example.   Hall  (1934)  ob- 
tained a  yield  of  1,  455,  000  oocysts  of  E. 
nieschulzi  per  oocyst  fed  when  the  infecting 
dose  was  6  oocysts,  1,  029,  666  when  it  was 
150  oocysts,  and  144, 150  when  it  was  2000 
oocysts.     If  the  infecting  dose  is  too  small, 
however,  smaller  numbers  of  oocysts  are 
produced.     Hall  (1934)  found  that  when  only 
a  single  oocyst  was  fed,  the  yield  was 
62,000. 

Similarly,  Brackett  and  Bliznick 
(1950,   1952)  found  that  with  E.  acervuUna 
of  the  chicken,  9000  oocysts  were  produced 
per  oocyst  fed  when  the  infecting  dose  was 
200  oocysts,   35,  000  to  72,  000  when  it  was 
2000  oocysts,   35,000  when  it  was  10,000 
oocysts,  and  7,600  when  it  was  20,000 
oocysts.    With  E.  maxima  of  the  chicken, 
they  found  that  11,  500  oocysts  were  pro- 
duced per  oocyst  fed  when  the  infecting 
dose  was  200  oocysts,  2,  250  when  it  was 
2000  oocysts,  and  940  to  2900  when  it  was 
10,  000  oocysts.    With  E.  necatrix  of  the 
chicken,  they  found  that  50,  000  oocysts 
were  produced  per  oocyst  fed  when  the  in- 
fecting dose  was  200  oocysts,  and  2400 
when  it  was  2000  oocysts.    With  E.  tenella 
of  the  chicken,  they  found  that  the  maxi- 
mum number  of  oocysts  produced  per 
oocyst  fed  in  numerous  experiments  was 
400,000.     However,  in  one  series  of  2- 
week-old  chicks  this  figure  ranged  from 
1200  for  chicks  fed  40,  000  oocysts  to 
80,  000  when  the  infecting  dose  was  50 
oocysts. 

All  the  factors  responsible  for  these 
results  are  not  known.    More  effective 
mobilization  of  the  host's  defenses  is 
probably  important,  but  lack  of  enough 
epithelial  cells  to  parasitize,  sloughing  of 
patches  of  epithelium,  increased  intes- 
tinal motility  with  resultant  diarrhea  and 


elimination  of  merozoites  before  they  can 
reach  a  cell,  and  entrapment  of  merozoites 
in  tissue  debris  and  cecal  cores  may  also 
play  a  part. 

Pathogenesis.      While  many  species 
of  coccidia  are  pathogenic,  many  others 
are  not.     Pathogenicity  depends  on  a  num- 
ber of  factors,  some  of  which  are  probably 
still  unknown.    Among  those  which  might 
be  mentioned  are  the  number  of  host  cells 
destroyed  per  infecting  oocyst  (which  de- 
pends upon  the  number  of  merozoite  gen- 
erations and  the  number  of  merozoites  per 
generation)  and  the  location  of  the  parasite 
in  the  host  tissues  and  within  the  host  cells. 
The  size  of  the  infecting  dose  or  doses, 
the  degree  of  reinfection,  and  the  degree 
of  acquired  or  natural  immunity  of  the  host 
are  also  important. 

Even  with  a  pathogenic  species,  the 
final  effect  on  the  host  depends  on  the  in- 
terplay between  many  factors;  it  may  range 
from  rapid  death  in  susceptible  animals  to 
an  imperceptible  reaction  in  immune  ones. 

If  disease  is  present,  the  signs  are 
those  of  a  diarrheal  enteritis.    There  may 
or  may  not  be  blood  in  the  feces,  depending 
on  the  parasite  species  and  severity  of  in- 
fection.   Affected  animals  gain  weight 
poorly,  become  weak  and  emaciated,  or 
may  even  die,  depending  again  on  the  para- 
site species  and  the  size  of  the  infecting 
dose.    Young  animals  are  much  more  com- 
monly affected  than  older  ones.    Those  ani- 
mals which  recover  develop  an  immunity 
to  the  particular  species  which  infected 
them.     However,  this  is  not  an  absolute 
immunity,  and  recovered  adult  animals 
are  often  continuously  reinfected  so  that 
they  carry  light  infections  which  do  not 
harm  them  but  which  make  them  a  source 
of  infection  for  the  young.    In  addition, 
under  conditions  of  stress  their  immunity 
may  be  broken  down  and  they  may  suffer 
from  the  disease  again. 

Differentiation  of  Species .      Both 
morphological  and  biological  characters 
are  used  to  separate  the  species  of  coc- 
cidia.   Both  the  endogenous  and  exogenous 
stages  of  the  life  cycle  may  differ  morpho- 
logically.    However,  since  the  endogenous 


164 


THE  TELOSPORASIDA   AND  THE  COCCIDLA    PROPER 


stages  of  many  species  are  unknown,  the 
structure  of  the  oocyst  is    most  commonly 
used.     The  feeling  is  sometimes  expressed 
that  the  oocysts  have  so  few  structures 
that  not  many  species  can  be  distinguished 
morphologically,  but  conservative  calcu- 
lation shows  that  at  least  2,  654,  208  mor- 
phologically different  oocysts  are  possible 
in  the  genus  Eimeria  alone  (Levine,  1961). 

A  second  group  of  criteria  is  the  loca- 
tion of  the  endogenous  stages  in  the  host. 
This  has  been  discussed  above.     Host 
specificity  is  a  third  criterion.    This  var- 
ies with  the  protozoan  genus  and  to  some 
extent  with  the  species.    In  general,  the 
host  range  of  Isospora  and  Tyzzeria  spe- 
cies is  relatively  broad.    Several  mem- 
bers of  the  same  host  order  may  be  in- 
fected by  the  same  species  of  these  genera. 
For  example,  Isospora  bigemina  occurs  in 
the  dog,  cat,  ferret  and  mink,  while 
Tyzzeria  anseris  has  been  found  not  only 
in  the  domestic  goose  and  several  other 
members  of  the  genus  Anser,  but  also  in 
the  Canada  goose  and  Atlantic  brant  (both 
Branla)  and  whistling  swan  (Olor).    On  the 
other  hand,  the  host  range  of  Eimeria  spe- 
cies is  relatively  narrow.    A  single  species 
rarely  infects  more  than  one  host  genus 
unless  the  latter  are  closely  related. 

Cross-immunity  studies  are  also  used 
in  differentiating  the  coccidia  of  a  partic- 
ular host  species  from  each  other.    Infec- 
tion of  an  animal  with  one  species  of  coc- 
cidium  produces  immunity  against  that 
species  but  not  against  other  species  which 
occur  in  the  same  host. 

Diagnosis:     Coccidiosis  can  be  diag- 
nosed by  finding  the  coccidia  on  micro- 
scopic examination.     There  are  several 
pitfalls  in  diagnosis.    Each  species  of  do- 
mestic and  laboratory  animal  has  several 
species  of  coccidia,  some  of  which  are 
pathogenic  and  some  of  which  are  not. 
Since  an  expert  is  often  needed  to  differ- 
entiate between  some  of  the  species,  the 
mere  presence  of  oocysts  in  the  feces, 
even  in  the  presence  of  disease  signs,  is 
not  necessarily  proof  that  the  signs  are 
due  to  coccidia  and  not  to  some  other 
agent. 


Following  recovery  from  a  coccidial 
infection,  an  animal  is  relatively  immune 
to  reinfection  with  the  same  species.    This 
immunity  is  not  so  solid  that  the  animal 
cannot  be  reinfected  at  all,  but  it  does 
mean  that  the  resultant  infection  will  be 
low-grade  (except  possibly  under  conditions 
of  stress)  and  will  not  harm  the  host.    Such 
low-grade  infections  are  extremely  common, 
i.e.,  the  animals  have  coccidiasis  rather 
than  coccidiosis.     Hence,  the  presence  in 
the  feces  of  oocysts  of  even  highly  patho- 
genic species  of  coccidia  does  not  neces- 
sarily mean  that  the  animal  has  clinical 
coccidiosis. 

On  the  other  hand,  coccidia  may  cause 
severe  symptoms  and  even  death  early  in 
their  life  cycle  before  any  oocysts  have 
been  produced.     This  occurs  commonly, 
for  example,  with  E.  tenella  of  the  chicken 
and  E.  ziirnii  of  the  ox.     Consequently, 
failure  to  find  oocysts  in  the  feces  in  a 
diarrheal  disease  does  not  necessarily 
mean  that  the  disease  is  not  coccidiosis. 

The  only  sure  way  to  diagnose  coccid- 
iosis, then,  is  by  finding  lesions  containing 
coccidia  at  necropsy.    Scrapings  of  the  le- 
sions should  be  mixed  on  a  slide  with  a 
little  physiological  salt  solution  and  exam- 
ined microscopically.    It  is  not  enough  to 
look  for  oocysts,  but  schizonts,  mero- 
zoites,  gametes  and  gametocytes  inside 
the  host  cells  must  be  sought  for  and  rec- 
ognized. 

Some  species  of  coccidia  can  be  iden- 
tified from  their  unsporulated  oocysts, 
but  study  of  the  sporulated  oocysts  is  often 
desirable.    Oocysts  can  be  sporulated  by 
mixing  the  feces  with  several  volumes  of 
2.  5%  potassium  bichromate  solution,   plac- 
ing the  mixture  in  a  thin  layer  in  a  Petri 
dish  and  allowing  it  to  stand  for  1  day  to 
2  weeks  or  more,  depending  on  the  spe- 
cies.    The  potassium  bichromate  prevents 
bacterial  growth  which  might  kill  the  pro- 
tozoa, and  the  thin  layer  is  necessary  so 
that  oxygen  can  reach  the  oocysts. 

Treatment.      The  first  compound 
found  effective  against  coccidia  was  sulfur, 
which  was  introduced  by  Herrick  and 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


165 


Holmes  (1936).     Later,   Hardcastle  and 
Foster  (1944)  introduced  borax.     Neither 
of  these  compounds  was  a  satisfactory 
anticoccidial  drug.    Sulfur  interferes  with 
calcium  metabolism,  causing  a  condition 
known  as  sulfur  rickets  in  chickens,  while 
borax  is  only  partially  effective  and  in 
addition  is  toxic  in  therapeutic  doses. 

The  first  practical  anticoccidial  drugs 
were  the  sulfonamides,  of  which  the  first 
to  be  used  was  sulfanilamide,  introduced 
by  P.   P.   Levine  (1939).    Since  that  time 
many  different  drugs  have  been  used, 
particularly  against  Eimeria  lenella  of  the 
chicken.    These  include  not  only  sulfon- 
amides but  also  derivatives  of  phenylar- 
sonic  acid,  diphenylmethane,  diphenyldi- 
sulfide,  diphenylsulfide,  nitrofuran,  tri- 
azine,  carbanilide,   imidazole  and  benza- 
mide.    Several  thousand  papers  have 
probably  been  published  on  coccidiostatic 
drugs,  and  their  use  in  poultry  production 
is  so  common  in  the  United  States  that  it 
is  difficult  to  obtain  a  commercial  feed 
which  does  not  contain  one  or  another  of 
them.     They  are  used  to  a  considerably 
lesser  extent  for  other  classes  of  live- 
stock. 

None  of  these  drugs  will  cure  a  case 
of  coccidiosis  once  signs  of  the  disease 
have  appeared.     They  are  all  prophylactic. 
They  must  be  administered  at  the  time  of 
exposure  or  soon  thereafter  in  order  to  be 
effective.     They  act  against  the  schizonts 
and  merozoites  and  occasionally  against 
the  sporozoites,   preventing  the  life  cycle 
from  being  completed.     They  are  not 
effective  against  the  gametes.     Hence, 
since  exposure  in  nature  is  continuous, 
these  drugs  must  be  fed  continuously. 
This  is  usually  done  by  mixing  them  with 
the  feed  or  water. 

Nowhere  is  a  knowledge  of  the  normal 
course  of  the  disease  more  important  than 
in  interpreting  the  results  of  treatment  of 
coccidiosis,  and  nowhere  is  the  controlled 
experiment  more  important  than  in  research 
in  this  field.     This  disease  is  self-limiting 
not  only  in  the  individual  patient  but  also  in 
a  flock  or  herd.    In  a  typical  outbreak  of 
coccidiosis,  signs  of  disease  appear  in 
only  a  few  animals  at  first,  the  number  of 
affected  animals  builds  up  rapidly  to  a 


peak  in  about  a  week,  and  then  the  disease 
subsides  spontaneously.    In  the  early 
stages,   most  farmers  do  little,  thinking 
that  the  condition  is  unimportant  and  will 
soon  be  over.    Once  more  animals  become 
affected  and  losses  increase,  it  takes  a 
little  time  to  establish  a  diagnosis,  so 
treatment  is  often  not  started  until  the  out- 
break has  reached  its  peak.     Under  these 
circumstances,   it  matters  little  what  treat- 
ment is  used- -the  disease  will  subside. 
This  is  the  reason  why  so  many  quack  rem- 
idies  used  to  get  glowing  testimonials  from 
satisfied  users. 

A  similar  course  of  events  is  encoun- 
tered by  the  small  animal  practitioner. 
The  patient  with  coccidiosis  is  not  brought 
to  him  until  it  is  already  sick.     By  this 
time  it  is  too  late  for  any  anticoccidial 
drug  to  be  of  value,  altho  supportive  treat- 
ment and  control  of  secondary  infections 
may  be  helpful.    If  the  patient  recovers, 
however,  whatever  drug  happened  to  be 
used  is  often  given  undeserved  credit. 
Such  drugs  are  like  Samian  clay,  which 
was  Galen's  favorite  remedy.     He  said 
that  it  cured  all  diseases  except  those 
which  were  incurable,   in  which  case  the 
patient  died. 

Collins  (1949)  described  the  "four-pen 
test"  which  should  be  used  in  evaluating 
coccidiostats  and  other  drugs.     The  birds 
in  one  pen  are  infected  with  coccidia  and 
treated  with  the  compound  under  test. 
Those  in  the  second  pen  are  infected  and 
untreated,  those  in  the  third  pen  are  un- 
infected and  treated,  and  those  in  the 
fourth  pen  are  uninfected  and  untreated. 
Comparison  of  the  first  2  pens  determines 
whether  the  compound  has  any  effect  on 
the  coccidia;  the  third  and  fourth  pens  are 
used  to  determine  whether  the  drug  has 
any  effect  on  the  chickens  themselves  and 
to  make  sure  that  no  extraneous  infection 
has  taken  place. 

After  an  animal  has  been  receiving  a 
coccidiostatic  drug  for  some  time  during 
exposure  to  infection,  it  develops  an  im- 
munity to  the  coccidia.  This  occurs  be- 
cause the  sporozoites  are  not  affected  by 
the  drug  but  invade  the  tissue  cells  and 
stimulate  the  host's  defenses. 


166 


THE  TELOSPORASIDA  AND  THE  COCCIDLA   PROPER 


After  coccidiostats  had  been  mixed  in 
poultry  feeds  for  a  number  of  years,   it 
was  inevitable  that  drug  resistant  strains 
of  coccidia  would  appear.    The  first  report 
of  this  was  by  Waletzky,   Neal  and  Hable 
(1954),  who  found  a  field  strain  of  Eiiiieria 
tenella  resistant  to  sulfonamides.     Cuckler 
and  Malanga  (1955)  reported  on  40  field 
strains  of  chicken  coccidia  which  were  re- 
sistant to  one  coccidiostat  or  another,  and 
drug  resistance  is  now  a  well-known  com- 
plicating factor  in  the  use  of  these  agents. 
A  race  has  developed  between  the  coccidia 
and  the  pharmaceutical  houses,  and  some 
day,  horribile  dictu,   we  may  be  reduced 
to  sanitation  to  control  coccidia. 

Mixed  Infections.      All  domestic  ani- 
mals have  more  than  one  species  of  coc- 
cidia.   Some  are  highly  pathogenic,  others 
less  so,  and  still  others  practically  non- 
pathogenic.    Pure  infections  with  a  single 
species  are  rare  in  nature,  so  the  ob- 
served effect  is  the  resultant  of  the  com- 
bined actions  of  the  particular  mixture  of 
coccidia  and  other  parasites  present,  to- 
gether with  the  modifying  effects  of  the 
nutritional  condition  of  the  host  and  envi- 
ronmental factors  such  as  weather  and 
management  practices. 

In  the  remainder  of  this  chapter,  each 
species  of  coccidium  in  a  particular  host 
animal  will  be  taken  up  first,  and  then  a 
general  discussion  of  coccidiosis  in  the 
host  will  follow. 


Genus  EIMEMA  Schneider,   1875 

In  this  genus  the  oocyst  contains  4 
sporocysts,  each  of  which  contains  2 
sporozoites. 


EIMERIA  ALABAMENSIS 
CHRISTENSEN,   1941 

Hosts:     Ox. 

Location:     Posterior  half  of  ileum, 
especially  within  a  few  feet  forward  from 
the  ileo-cecal  valve.     In  heavy  infections, 
the  cecum  and  upper  colon  may  be  in- 
volved. 


Geographic  Distribution: 
America. 


North 


Prevalence:     Davis,   Boughton  and 
Bowman  (1955)  found  this  species  in  93% 
of  102  dairy  calves  in  6  herds  in  south- 
eastern United  States  in  a  weekly  fecal 
survey;  they  found  it  in  24%  of  135  animals 
from  which  only  a  single  fecal  sample  was 
taken;  it  was  present  in  all  of  26  herds 
from  which  at  least  5  animals  were  ex- 
amined.    Hasche  and  Todd  (1959)  found  it 
in  42%  of  355  cattle  in  Wisconsin. 

Morphology:     The  oocysts  have  been 
described  by  Christensen  (1941).     They 
measure  13  to  24  by  11  to  16  ji  with  a  mean 
of  18.9  by  13.4jLt.    They  are  typically  piri- 
form but  may  also  be  subellipsoidal  or  sub- 
cylindrical.    The  oocyst  wall  is  thin, 
delicate,  homogeneous,  transparent,  color- 
less to  greyish-lavender  to  pale  brownish 
yellow,  slightly  thinner  at  the  narrow  end 
but  without  a  perceptible  micropyle.    Dur- 
ing sporulation  there  is  a  parachute-shaped 
cap  at  each  end  of  the  sporoblasts.    Spor- 
ulation takes  4  to  5  days.     The  sporocysts 
are  elongate  and  gently  tapered.    Neither 
oocyst  nor  sporocyst  residua  are  present. 
A  polar  granule  is  presumably  absent. 

Life  Cycle:     Davis,   Bowman  and 
Boughton  (1957)  described  the  life  cycle  of 
E.  alabamensis .     It  is  unusual  in  being  an 
intranuclear  parasite,  occurring  within 
the  nuclei  of  the  epithelial  cells  at  the  tips 
of  the  villi.    Excysted  sporozoites  were 
seen  in  the  cytoplasm  of  the  intestinal 
epithelial  cells  2  days  after  infection. 
They  enter  the  nuclei  and  round  up,  form- 
ing schizonts.     These  are  present  as  early 
as  2  days  after  infection  and  are  uncommon 
by  the  8th  day.     They  form  16  to  32  mero- 
zoites,  which  are  slender  and  spindle- 
shaped  while  still  within  the  parent  schizont 
but  appear  short,  with  bluntly  rounded  ends 
in  the  intracellular  spaces  and  crypts. 
Davis,   Bowman  and  Boughton  (1957)  thought 
that  there  is  probably  more  than  one  gen- 
eration of  schizonts. 

Macrogametes  and  microgametocytes 
first  appear  4  days  after  infection.     Most 
are  found  in  the  lower  third  of  the  small 
intestine,  but  they  may  invade  the  cecum 


THE  TELOSPORASIDA  AND  THE   COCCIDLA    PROPER 


167 


and  upper  colon  in  heavy  infections. 
Young  oocysts  still  in  the  host  cell  nuclei 
first  appear  6  days  after  infection.     Mul- 
tiple infections  are  common,  as  many  as 
3  schizonts  or  microgametocytes  and  4  or 
5  macrogametes  or  oocysts  having  been 
found  in  a  single  host  cell  nucleus.     This 
crowding  may  affect  the  shape  of  the 
oocysts  in  heavy  infections,  making  some 
of  them  wedge-shaped  or  asymmetrical. 

The  prepatent  period  in  experimentally 
infected  calves  was  found  by  Davis,  Bough- 
ton  and  Bowman  (1955)  to  range  from   6  to 
13  days  with  a  mean  of  8  to  9  days.     The 
patent  period  ranged  from  1  to  10  days  with 
a  mean  of  4.  6  days  in  21  low-grade  infec- 
tions, and  from  1  to  13  days  with  a  mean 
of  7.  2  days  in  72  heavy  infections. 

Pathogenesis:     Under  field  conditions, 
E.  alabainensis  is  considered  essentially 
non- pathogenic.     However,   Boughton  (1943) 
produced  clinical  coccidiosis  in  5  young 
calves  by  feeding  them  200  million  oocysts. 
Within  5  days  they  developed  a  severe 
diarrhea,  with  yellowish  feces  having  a 
characteristic  acrid  odor.    They  become 
thin,  and  1  calf  died  on  the  8th  day  and 
another  on  the  14th.    In  the  first  calf  the 
lower  half  of  the  small  intestine  was  hy- 
peremic  and  there  was  massive  tissue  in- 
volvement with  merozoites  and  macro- 
gametes.     In  the  second  calf  there  was 
enteritis  in  only  the  last  3  feet  of  the 
ileum,  and  only  a  few  parasites  remained 
in  the  tissues,  most  of  these  being  within 
1  foot  of  the  ileocecal  valve. 

Davis,   Boughton  and  Bowman  (1955) 
fed  two  14-month-old  calves  140  million 
oocysts.     One  became  diarrheic  on  the 
fifth  day.    Its  feces  were  watery,  yellow- 
ish green,  with  some  bloody  mucus  and  a 
sharp,  acrid  odor.    The  diarrhea  grad- 
ually subsided.    In  the  second  calf  the 
feces  were  soft  toward  the  end  of  the  pre- 
patent  period.    A  7-month-old  heifer  which 
had  previously  been  exposed  to  coccidial 
infection  had  a  slight  diarrhea  on  the  9th 
and  11th  days  following  similar  exposure, 
and  a  2-year-old  cow  remained  normal. 

Immunity:     Reinfection  is  considered 
common  in  the  field.     Davis,   Boughton  and 


Bowman  (1955)  reported  that  in  58  attempts 
to  reinfect  calves  2  or  more  times,  there 
were  39  high-grade  infections,   11  low- 
grade  infections  and  8  failures.     Nine  of 
the  low-grade  infections  and  7  of  the  fail- 
ures followed  the  third  or  subsequent  in- 
oculations.   Some  animals  were  reinfected 
as  many  as  4  times  before  reinfection  at- 
tempts failed. 


EIMERIA  AUBURNENSIS 
CHRISTENSEN  AND   PORTER,   1939 

Synonym :     Eimeria  ildefonsoi  Torres 
and  Ramos,   1939. 

Hosts:     Ox.     In  addition,  Bohm  and 
Supperer  (1956)  reported  finding  this  spe- 
cies in  a  wild  roe  deer  in  Austria,  but 
gave  no  morphological  information  on  it. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     North 
America,  South  America  (Brazil),   Europe 
(Austria,  Spain,   England). 

Prevalence:     E.  anbiiruensis   is  one  of 
the  commonest  coccidia  of  cattle  in  North 
America.    Davis  and  Bowman  (1952)  found 
it  in  all  of  20  calves  in  Alabama.     Hasche 
and  Todd  (1959)  found  it  in  45%  of  355 
cattle  in  Wisconsin.    Torres  and  Ramos 
(1939)  found  it  in  32%  of  146  cattle  in  Brazil. 
Supperer  (1952)  found  it  in  3%  of  130  cattle 
in  Austria.    According  to  Lapage  (1956), 
Watkins  found  it  in  91%  of  the  calves  he 
examined  in  Devonshire. 

Morphology:     The  oocysts  have  been 
described  by  Christensen  and  Porter  (1939) 
and  Christensen  (1941).     They  measure  32 
to  46  by  20  to  26  fi  with  a  mean  of  38.  4  by 
23. 1  ILL.     Their  length-width  ratios  range 
from  1 .  32  to  2.  08  with  a  mean  of  1 .  67. 
They  are  typically  elongate  ovoid,  but  vary 
between  sub-ellipsoidal  and  markedly  ta- 
pered.    The  micropyle  appears  as  a  thin, 
pale  area  at  the  small  end  in  unstained 
specimens,  but  when  stained  with  iodine- 
eosin  in  physiological  salt  solution,  a  def- 
inite gap  covered  by  a  narrow  black  line 
which  may  be  a  flat  operculum  is  seen. 


168 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


A  membrane  lines  the  oocyst  wall,  which 
is  illustrated  as  composed  of  a  single 
layer.    The  oocyst  wall  is  1  to  1.  5 /i  thick, 
typically  smooth,   homogeneous,  transpar- 
ent and  yellowish  brown;  relatively  rarely 
it  may  be  semi-transparent  and  heavily 
mammillated,  and  all  gradations  between 
these  two  conditions  occur.    The  smooth- 
walled  forms  are  more  common  than  the 
rough. 

The  sporulation  time  at  room  temper- 
ature in  Alabama  is  2  to  3  days.    There  is 
no  oocyst  residuum  or  polar  granule.    The 
sporocysts  were  illustrated  by  Christensen 
and  Porter  (1939)  as  elongate  with  one  end 
pointed.     The  sporozoites  lie  lengthwise, 
head  to  tail,  in  them  and  contain  3  clear 
globules,  1  of  which  may  be  the  nucleus. 
The  sporocyst  residuum  consists  of 
rounded  masses  or  individual  granules  be- 
tween the  sporozoites. 

Christensen  and  Porter  (1939)  showed 
that  the  rough  and  smooth  forms  were  the 
same  species  by  infecting  a  calf  with  rough 
oocysts  and  recovering  all  types,  but  pre- 
dominantly smooth  ones,  from  it. 

Life  Cycle:  The  endogenous  stages 
of  this  species  are  unknown.  Christensen 
and  Porter  (1939)  found  that  the  prepatent 
period  in  one  calf  was  24  days.  Large 
numbers  of  oocysts  were  discharged  for  3 
days,  and  small  numbers  for  the  next  few 
weeks. 

Pathogenesis:     Christensen  and  Por- 
ter (1939)  produced  a  profuse,  watery, 
green  diarrhea  accompanied  by  slight  apa- 
thy in  a  2-week-old  calf  following  admin- 
istration of  8000  sporulated  oocysts.    The 
signs  appeared  9  days  after  infection  (i.e. , 
15  days  before  the  first  oocysts  appeared 
in  the  feces)  and  continued  for  5  days. 
According  to  Davis  and  Bowman  (1952), 
infections  with  E.  aubiiynensis  are  usually 
accompanied  by  straining  and  the  passing 
of  visible  blood  and  mucus,  especially 
following  experimental  inoculation  with 
large  numbers  of  oocysts  or  in  natural 
outbreaks  where  contamination  is  heavy. 


EIMERIA   BOVIS 
(ZUBLIN,   1908) 
FIEBIGER,   1912 

Synonyms:     Coccidium  bovis, 
Elmer ia  canadensis   (pro  parte),  Eimcria 
smithi,  Eimeria  thianelhi,   Globidiiiiii 
fusiformis  (?). 

Hosts:     Ox,   zebu,  water  buffalo. 
Wilson  (1931)  was  unable  to  infect  pigs  or 
goats  with  this  species. 

Location:     The  schizonts  are  mostly 
in  the  small  intestine  and  the  sexual  stages 
in  the  cecum,   colon  and  terminal  ileum. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  is  one  of  the  com- 
monest coccidia  of  cattle.    Boughton  (1945) 
found  it  in  41%  of  2492  bovine  fecal  samples 
in  south-eastern  U.S.     Hasche  and  Todd 
(1959)  found  it  in  41%  of  355  cattle  in  Wis- 
consin.   Supperer  (1952)  found  it  in  66%  of 
130  cattle  in  Austria.     Cordero  del  Cam- 
pillo  (1960)  reported  it  and  other  bovine 
species  in  Spain.    Torres  and  Ramos  (1939) 
found  it  in  49%  of  136  cattle  in  Brazil. 
Yakimoff,  Gousseff  and  Rastegaieff  (1932) 
found  it  in  40%  of  126  cattle  in  Uzbekistan. 
Yakimoff  (1933)  found  it  in  47%  of  17  zebus, 
23%  of  30  water  buffaloes  and  39%  of  44 
cattle  in  Azerbaidzhan.    Marchenko  (1937) 
found  it  in  54%  of  137  cattle  in  the  North 
Caucasus.     Rao  and  Hiregaudar  (1954) 
stated  that  it  is  common  in  Bombay  State, 
India.     Ruiz  (1959)  found  it  in  7%  of  100 
adult  cattle  in  the  San  Jose,  Costa  Rica 
abattoir. 

Morphology:     The  oocysts  of  £.  bovis 
were  described  by  Christensen  (1941). 
Five  hundred  oocysts  measured  23  to  34 
by  17  to  23  n  with  a  mean  of  27.  7  by  20.  3  ji . 
Their  length-width  ratios  ranged  from  1. 1 
to  1 .  8  with  a  mean  of  1 .  37.    They  are  typ- 
ically stoutly  ovoid  and  somewhat  blunted 
across  the  narrow  end,  but  vary  consider- 
ably in  shape,  especially  in  heavy  infec- 
tions, subellipsoidal,  asymmetrical  and 
elongated,  tapered  oocysts  also  occurring. 


THE  TELOSPORASTDA   AND  THE  COCCIDIA    PROPER 


169 


The  micropyle  is  a  lightened  area  at  the 
small  end.     The  oocyst  wall  is  smooth, 
homogeneous,  transparent,   pale  cloudy, 
greenish  brown  to  yellowish  brown,  and 
slightly  thinner  toward  the  micropylar  end. 
The  wall  is  not  so  delicate  as  that  of  E. 
alaba))ieiisis.     It  is  darker  than  that  of  E. 
alabai)ieiisis  and  lighter  than  that  of  E. 
aubnriiensis.     Christensen  (1941)  illus- 
trated the  wall  as  composed  of  a  heavy 
inner  layer  and  a  very  thin,  transparent 
outer  layer,  but  he  did  not  mention  layers 
in  his  description.    An  oocyst  residuum 
and  polar  granule  are  absent.     A  sporocyst 
residuum  is  present. 

The  sporulation  time  is  2  to  3  days. 

Life  Cycle:      Hammond  et  al.  (1946) 
described  the  endogenous  stages  of  the 
life  cycle  of  E.  bovis  in  detail.     There  is 
a  single  asexual  generation.     The  sporo- 
zoites  invade  the  endothelial  cells  of  the 
lacteals  of  the  villi  in  the  posterior  half 
of  the  small  intestine.    These  cells  be- 
come detached  from  the  lacteal  lining  and 
lie  free  and  greatly  swollen  in  the  lumens 
of  the  lacteals.    The  schizonts  are  first 
found  5  days  after  infection.     They  grow  to 
giant  size,  becoming  mature  14  to  18  days 
after  infection.    A  few  may  still  be  found 
as  long  as  30  days  after  inoculation,  but 
most  of  these  are  degenerate.     The  mature 
schizonts  measure  207  to  435  by  134  to 
267  jLi  with  a  mean  of  281  by  303  ji  and  con- 
tain 55,000  to  170,000  (mean,   120,000) 
merozoites.    They  are  easily  visible  to 
the  naked  eye  as  whitish  balls,  and  their 
presence  was  first  pointed  out  by  Boughton 
(1942)  as  a  macroscopic  lesion  which  could 
be  used  in  diagnosing  coccidiosis. 

The  merozoites  are  9  to  15jj,  (mean, 
11.6jLi)  long  and  about  2/i  wide.    They  are 
rounded  at  one  end  and  taper  abruptly  to  a 
point  at  the  other.     The  nucleus  is  near 
the  pointed  end. 

The  sexual  stages  usually  occur  only 
in  the  cecum  and  colon,  but  in  heavy  in- 
fections they  may  be  found  in  the  terminal 
3  or  4  feet  of  the  small  intestine.     They 
occur  in  the  epithelial  cells  of  the  intes- 
tinal glands.    The  cells  at  the  base  of  the 
glands  are  invaded  first,  and  later  the 


rest  of  the  gland  becomes  involved.    The 
first  sexual  stages  appear  17  days  after 
inoculation.     The  macrogametes  contain 
plastic  granules  in  their  cytoplasm,  there 
being  1  layer  of  small  granules  near  the 
surface  and  a  less  distinct  layer  of  larger 
granules  beneath  it.     Fertilization  was  not 
seen,  but  2  stages  in  the  union  of  nuclei 
were  seen  before  formation  of  the  oocyst 
wall. 

According  to  Walton  (1959),  the  hap- 
loid  number  of  chromosomes  in  E.   bovis 
is  2. 

Oocysts  appear  16  to  21  days  after 
experimental  infection.     Large  numbers 
are  discharged  for  5  to  7  days,  and 
smaller  numbers  are  present  in  the  feces 
for  2  to  3  weeks.    In  28  calves  studied  by 
Senger  et  al.   (1959),  oocysts  were  dis- 
charged for  7  to  15  days  with  a  mean  of 
11.5  days. 

Pathogenesis:     E.   bovis  is  one  of  the 
2  most  pathogenic  of  the  bovine  coccidia. 
Hammond,  Davis  and  Bowman  (1944) 
studied  its  effects  in  experimentally  in- 
fected calves.    An  infective  dose  of 
125,000  oocysts  or  more  was  generally 
needed  to  cause  marked  signs.     These 
appeared  about  18  days  after  infection, 
and  consisted  of  diarrhea  and/or  bloody 
diarrhea,  tenesmus,  and  temperatures  as 
high  as  106.  6°  F.    One  of  4  calves  given 
125,000  oocysts  become  moribund  due  to 
coccidiosis,  while  single  calves  given 
250,  000  to  1,  000,  000  oocysts  all  died  or 
became  moribund  24  to  27  days  after  in- 
fection. 

The  most  severe  pathologic  changes 
occur  in  the  cecum,   colon  and  terminal 
foot  of  the  ileum.    They  are  due  to  the 
sexual  stages  of  the  coccidia.    At  first 
the  mucosa  is  congested,  edematous 
and  thickened,  with  petechiae  or  diffuse 
hemorrhages.     Its  lumen  may  contain  a 
large  amount  of  blood.     Later,  the  mucosa 
is  destroyed  and  sloughed,  and  a  patchy 
or  continuous  membrane  forms  over  its 
surface.    The  sub  mucosa  may  also  be 
destroyed.     If  the  animal  survives, 
both  mucosa  and  submucosa  are  later 
replaced. 


170 


THE  TFLOSPORASIDA   AND  THE  COCCIDLA   PROPER 


Immunity:     Senger  et  a  I.  (1959)  found 
that  inocula  of  10, 000,   50, 000  or  100,  000 
oocysts  of  E.  bovis  produced  a  good  deal 
of  immunity  to  reinfection.     The  immunity 
developed  rapidly,  calves  being  resistant 
to  challenge  14  days  after  immunization. 
Immunity  persisted  to  a  moderate  degree 
for  2  to  3  months  in  young  calves,  and  in 
one  group  of  yearlings  there  was  appar- 
ently a  high  degree  of  immunity  7  months 
after  the  last  inoculation.     An  inoculum 
of  10,000  oocysts  did  not  produce  as  great 
an  immunity  as  50,000  or  100,000  oocysts; 
there  was  no  significant  difference  in  the 
degree  of  immunity  produced  by  the  higher 
doses.     All  these  immunizing  doses  caused 
diarrhea  and  bloody  feces;  the  greater  the 
number  of  oocysts  administered,  the  more 
severe  and  longer-lasting  the  resultant 
disease. 

Hammond  el  al.    (1959)  found  that  this 
immunity  was  not  directed  against  the 
schizonts  but  against  the  sexual  stages  or 
merozoites.    They  found  no  significant 
differences  in  numbers  or  size  of  schi- 
zonts between  immunized  and  non-immu- 
nized calves,  but  the  latter  had  many  more 
sexual  stages  than  the  former. 

Remarks:     Hassan  (1935)  described 
the  sporozoites  and  schizonts  of  an  organ- 
ism which  he  named  Globidium  fiisiformis 
from  5  zebus  with  dysentery  and  rinder- 
pest in  India.     The  schizonts  were  found 
in  the  abomasum,  duodenum  and  ileum; 
they  often  occurred  anterior  to  the  ileo- 
cecal valve,  but  were  not  found  in  the 
large  intestine.    They  were  whitish  and 
measured  0.  4  to  1.  0  by  0.  8  mm.     The 
merozoites  were  elongate,  spindle- 
shaped,  slightly  curved-,  with  one  end 
bluntly  rounded  and  the  other  finely 
pointed,   13  by  2  to  2.  5 /i  .     This  form  may 
well  be  Eimeria  bovis.     However,  the 
fact  that  schizonts  were  found  in  the  abo- 
masum as  well  as  in  the  small  intestine 
made  Hammond  et  al.  (1946)  hesitate  to 
assign  it  to  this  species,   since  they  never 
found  schizonts  of  E.  bovis  in  the  abo- 
masum. 


EIMERLi   BRASILIENSIS 
TORRES  AND   RAMOS,   1939 

Synonyms:     Eimeria  boehmi  Supperer, 
1952;  Eimeria  orlovi  Basanov,  1952. 

Hosts:     Ox,   zebu.     In  addition,  Bohm 
and  Supperer  (1956)  reported  finding  this 
species  in  several  chamois  in  Austria, 
but  gave  no  morphological  information  on 
which  a  comparison  could  be  based. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:    North  Amer- 
ica, South  America  (Brazil),   Europe(Aus- 
tria),  Africa  (Nigeria),  USSR  (Kazakhstan). 

Prevalence:     Davis  and  Bowman  (1952) 
stated  that  this  species  is  uncommon  in 
Alabama.     Hasche  and  Todd  (1959)  found 
it  in  6%  of  927  cattle  in  Wisconsin.     Torres 
and  Ramos  (1939)  found  it  in  3%  of  146 
cattle  in  Brazil.    Supperer  (1952)  found  it 
in  7%  of  130  cattle  in  Austria.     Lee  and 
Armour  (1958)  saw  it  frequently  in  cattle 
in  Nigeria.     Basanov  (1952)  found  it  in 
Kazakhstan,  USSR. 

Morphology:     The  oocysts  are  ellip- 
soidal,  colorless  to  yellowish  or  pinkish, 
smooth,   31  to  49  by  22  to  33  ji,  with  a 
mean  of  36  to  38  by  26  to  27  j^.     The  oocyst 
wall  is  composed  of  a  single  layer.     The 
micropyle  is  5  to  6^  in  diameter,  and  is 
covered  by  a  micropylar  cap  8  to  12 [^  wide 
and  1.  5  to  3  (i  high;  this  cap  tends  to  col- 
lapse on  storage  in  unprepared  feces  in 
the  refrigerator.    An  oocyst  polar  granule 
is  present.    An  oocyst  residuum  is  absent. 
The  sporocysts  are  elongate  ovoid  (with  a 
fine  "operculum",  according  to  Torres  and 
Ramos),   16  to  22  by  7  to  9 1^  (Supperer). 
A  sporocyst  residuum  is  present. 

The  sporulation  time  is  6  to  7  days  at 
27°  C  (Lee  and  Armour,  1958)  or  12  to  14 
days  at  20°  C  (Supperer,   1952). 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


THE  TELOSPORASIDA   AND  THE  COCCIDLA   PROPER 


171 


EIMERIA  BUKIDNONENSIS 
TUBANGUI,   1931 

Synonyms:     Eimeria  ivyomingensis 
Huizinga  and  Winger,   1942;  Eimeria 
khurodensis  Rao  and  Hiregaudar,   1954. 

Hosts:     Ox,   zebu. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:  North 
America,  Philippines,  USSR,  Africa 
(Nigeria),  South  America  (Brazil). 

Prevalence:     This  species  is  rela- 
tively uncommon.     Baker  (1938,   1939)  and 
Christensen  (1938)  reported  it  in  a  heifer 
in  New  York,   Christensen  (1941)  found  it 
infrequently  in  Alabama,   Huizinga  and 
Winger  (1942)  found  it  in  10  cattle  in 
Wyoming,  and  Hasche  and  Todd  (1959) 
found  it  in  5%  of  355  cattle  in  Wisconsin. 
Tubangui  (1931)  found  it  in  1  of  28  zebus 
in  the  Philippines.     Yakimoff,  Gousseff 
and  Rastegaieff  (1932)  found  it  in  2  of  126 
oxen  in  Uzbekistan.     Yakimoff  (1933) found 
it  in  2  of  17  zebus  and  1  of  41  oxen  in 
Azerbaidzhan.     Marchenko  (1937)  found  it 
in  0.  7%  of  137  cattle  from  the  North  Cau- 
casus.   Yakimoff  (1936)  found  it  in  1  of  49 
cattle  in  Brazil,  Torres  and  Ramos  (1939) 
reported  it  from  8%  of  146  cattle  in  Brazil. 
Lee  (1954)  found  it  in  a  Fulani  calf  (zebu) 
in  Nigeria. 

Morphology:     The  oocysts  are  piri- 
form, yellowish  brown  to  dark  brown,  33 
to  54  by  24  to  35jj,.     Their  length-width 
ratio  is  1.  3  to  1.8  with  a  mean  of  about 
1.  4.     The  oocyst  wall  is  about  2  to  4  jj. 
thick  except  at  the  micropylar  end,  where 
it  is  thin.    It  is  composed  of  2  layers  (3 
according  to  Yakimoff,  1933),  the  outer 
one  thick  and  the  inner  one  a  tough  mem- 
brane.    Tubangui  (1931),  Yakimoff  (1933), 
and  Lee  (1954)  described  the  wall  as 
radially  striated,  but  the  only  American 
author  to  note  this  feature  was  Baker 
(1939).     The  oocyst  wall  is  speckled,  and 
rather  rough.     The  micropyle  is  conspic- 
uous,  3.  5  to  7jLj,  in  diameter.    An  oocyst 
residuum  and  polar  granule  are  absent. 
The  sporocysts  are  elongate  lemon-shaped. 


14  to  22  by  9  to  12  |j..     A  Stieda  body  is 
possibly  present.    Definite  sporocyst  res- 
idual material  is  absent.     The  sporozoites 
were  described  by  Tubangui  as  more  or 
less  roundish  or  reniform  and  illustrated 
without  refractile  globules.    According  to 
Huizinga  and  Winger,   refractile  globules 
are  prominent,  and  it  is  possible  that 
Tubangui  mistook  these  for  the  sporozoites 
proper. 

Rao  and  Hiregauder  (1954)  described 
a  new  species,  E.  khurodensis  ,  from  zebus 
in  India.    It  failed  to  sporulate,  and  there 
is  nothing  in  their  description  which  differs 
from  that  of  E.   biikidnonensis. 

The  sporulation  time  is  4  to  7  days 
according  to  Christensen  (1941),   5  to  7 
days  according  to  Huizinga  and  Winger 
(1942),   24  to  27  days  according  to  Baker 
(1939). 

Life  Cycle:     Unknown.     Baker  (1939) 
found  that  oocysts  first  appeared  in  an  ex- 
perimentally infected  calf  on  the  10th  day. 

Pathogenesis:     Baker  (1939)  observed 
a  tendency  toward  a  diarrheic  condition 
from  the  7th  to  15th  days  after  experi- 
mental infection  of  a  70-day  old  calf  with 
55  oocysts. 


EIMERIA   CANADENSIS 
BRUCE,   1921 

Synonyms:     Eimeria  zurnabadensis . 

Hosts:     Ox,   zebu. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     North  Amer- 
ica,  USSR  (Azerbaidzhan). 

Prevalence:     This  species  is  quite 
common  in  the  United  States.     Hasche  and 
Todd  (1959)  found  it  in  35%  of  355  cattle  in 
Wisconsin. 

Morphology:     This  species  has  been 
described  by  Christensen  (1941).     The 
oocysts  are  28  to  37  by  20  to  27  jm  with  a 


172 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


mean  of  32.  5  by  23.4 /i.     Their  length- 
width  ratio  is  1 .  2  to  1 .  6  with  a  mean  of 
1.  39.    They  are  typically  ellipsoidal,  but 
vary  from  nearly  cylindrical  to  stoutly 
ellipsoidal  and  occasionally  slightly  ta- 
pered.    The  oocyst  wall  is  transparent, 
about  1  fi  thick  in  the  middle,  slightly 
thinner  at  each  end,  delicately  yellowish 
brown  (paler  toward  the  ends),  normally 
smooth,  and  apparently  composed  of  a 
single  layer  lined  by  a  membrane.     The 
micropyle  is  an  inconspicuous  gap  in  the 
wall  at  one  end,  appearing  covered  with  a 
thin,  dark  refraction  line.    An  oocyst 
residuum  and  polar  granule  are  absent. 
The  sporocysts  were  not  described  by 
Christensen  (1941).     The  sporulation  time 
is  3  to  4  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     Apparently  slight. 


EIMERIA   CYLINDRICA 
WILSON,    1931 

Hosts:     Ox,   zebu.     Wilson  (1931)  was 
unable  to  infect  pigs  or  goats  with  this 
species. 

Location:     Unknown.     Oocysts  found 
in  feces. 


a  mean  of  1.  67.    The  oocyst  wall  is  thin, 
smooth,   homogeneous,  transparent,  color- 
less to  slightly  tinted,  and  presumably 
composed  of  a  single  layer.    A  micropyle 
is  absent,  altho  the  wall  is  slightly  paler 
at  one  end.     An  oocyst  residuum  and  polar 
granule  are  absent.    A  sporocyst  residuum 
is  present,  but  there  is  no  sporocyst  Stieda 
body.     The  sporozoites  are  elongate,   lying 
lengthwise  in  the  sporocysts  and  filling 
them.     (According  to  Rao  and  Hiregaudar, 
1954,  the  sporocysts  measure  6  to  8  by  2 
to  4/i  and  the  sporozoites  are  very  small, 
rounded  bodies.  )    The  sporulation  time  is 
2  days. 

The  oocysts  of  E.  cylindrica  intergrade 
to  some  extent  with  those  of  E.  ellipsoidalis 
in  size  and  shape,  but  other  characters  in- 
dicate that  they  are  separate  species. 

Life  Cycle:     Unknown.    Wilson  (1931) 
found  oocysts  in  a  calf  from  the  eleventh 
to  twentieth  days  after  experimental  infec- 
tion. 

Pathogenesis:     This  species  appears 
to  be  somewhat  pathogenic.    Wilson  (1931) 
observed  blood  in  the  feces  of  an  experi- 
mentally infected  calf  6  days  after  infection. 
Rao  and  Hiregaudar  (1954)  considered  this 
species  pathogenic  in  zebu  calves. 


Geographic  Distribution:     North  Amer- 
ica,  Europe  (Austria),  India. 


EIMERIA  ELLIPSOIDALIS 
BECKER  AND   FRYE,    1929 


Prevalence:     This  species  is  quite 
common.     Hasche  and  Todd  (1959)  found  it 
in  20%  of  355  cattle  in  Wisconsin.    Supperer 
(1952)  found  it  in  4%  of  130  cattle  in  Austria. 
Rao  and  Hiregaudar  (1954)  considered  it 
quite  prevalent  in  zebu  calves  in  Bombay. 
Ruiz  (1959)  found  it  in  1%  of  100  adult  cattle 
in  the  San  Jose,  Costa  Rica  abattoir. 

Morphology:     This  species  has  been 
described  by  Wilson  (1931)  and  Christensen 
(1941).     The  oocysts  are  16  to  28  by  12  to 
16^1  with  a  mean  of  about  23  by  14  (i.    They 
are  typically  cylindrical,  their  sides  being 
nearly  parallel  thruout  their  middle  third, 
but  they  may  vary  from  ellipsoidal  to  nar- 
row cylinders  twice  as  long  as  wide.     The 
oocyst  length-width  ratio  is  1.  3  to  2.  0  with 


Hosts:     Ox,   zebu,  water  buffalo. 

Location:     Small  intestine. 

Geographic  Distribution:     North  Amer- 
ica,  Europe  (Austria,  Spain),   USSR. 

Prevalence:     This  species  is  common 
in  cattle.     Boughton  (1945)  found  it  in  45% 
of  2492  bovine  fecal  samples  from  south- 
eastern United  States  and  remarked  that 
its  oocysts  comprised  40  to  50%  of  the  total 
oocyst  population  in  959  samples  from  over 
100  calves  3  to  12  weeks  old.     Christensen 
(1941)  found  its  oocysts  more  frequently 
than  those  of  any  other  species  in  the  feces 
of  healthy  calves  in  Alabama  during  early 
natural  infection.    Hasche  and  Todd  (1959) 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


173 


found  it  in  43%  of  355  cattle  in  Wisconsin. 
Supperer  (1952)  found  it  in  15%  of  130 
cattle  in  A-ustria.    Yakimoff,  Gousseff  and 
Rastegaieff  (1932)  found  it  in  23%  of  126 
oxen  in  Uzbekistan.     Yakimoff  (1933)  found 
it  in  27%  of  41  oxen,   6%  of  17  zebus  and 
52%  of  21  water  buffaloes  in  Azerbaidzhan. 
Marchenko  (1937)  found  it  in  16%  of  137 
cattle  in  the  North  Caucasus.     Ruiz  (1959) 
found  it  in  3%  of  100  adult  cattle  in  the  San 
Jose,  Costa  Rica  abattoir. 

Morphology:     The  oocysts  have  been 
described  by  Becker  and  Frye  (1929)  and 
Christensen  (1941),  among  others.     They 
are  12  to  27  by  10  to  18  fi  with  a  mean  of 
17  by  13|Lt.     Their  length- width  ratio  is 
1 .  0  to  1 .  6  with  a  mean  of  1 .  30.     They  are 
predominantly  ellipsoidal,  but  vary  in 
shape  from  spherical  to  almost  cylindri- 
cal, the  spherical  and  subspherical  oocysts 
occurring  in  the  smaller  size  range.     The 
oocyst  wall  is  thin,   smooth,   presumably 
composed  of  a  single  layer,  homogeneous, 
transparent,  colorless  to  pale  lavender  or 
pale  yellowish,  and  slightly  thinner  and 
paler  at  one  end,  suggesting  a  possible 
micropyie.    A  true  micropyle  is  apparently 
absent,  however.    An  oocyst  residuum  and 
polar  granule  are  absent.    A  sporocyst 
residuum  is  present.    The  sporocysts  were 
illustrated  by  Becker  and  Frye  (1929)  with- 
out a  Stieda  body.    The  sporocysts  (in  the 
zebu)  measure  13  to  14  by  4.  5 fi  according 
to  Yakimoff  (1933).     The  sporozoites  were 
illustrated  by  Becker  and  Frye  (1929)  with- 
out clear  globules. 

The  sporulation  time  is  2  to  3  days. 

Life  Cycle:     Unknown.    The  endogen- 
ous stages  occur  in  the  epithelial  cells  of 
the  small  intestine  mucosa,  according  to 
Boughton  (1945). 

Pathogenesis:  According  to  Boughton 
(1945),  this  species  often  causes  nonbloody 
diarrhea  in  calves  1  to  3  months  old. 


EIMERIA  PELLITA 
SUPPERER,   1952 

Hosts:     Ox. 


Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     Europe 
(Austria). 

Prevalence:     Supperer  (1952)  found 
this  species  in  5%  of  130  cattle  in  Austria. 

Morphology:     This  species  has  been 
described  by  Supperer  (1952).     The  oocysts 
are  36  to  41  by  26  to  30)ii ,  ovoid,  with  a 
flattened  small  end.    There  is  a  micropyle 
at  the  small  end.     The  oocyst  wall  is  rel- 
atively thick  and  dark  brown.    The  surface 
of  the  oocyst  bears  numerous  small,  uni- 
formly distributed  protuberances  in  the 
form  of  small,  blunt  points  which  give  the 
wall  a  velvety  appearance.    An  oocyst  polar 
granule  and  residuum  are  absent.     The 
sporocysts  are  elongate  ovoid,   14  to  18  by 
6  to  8|i,  without  a  Stieda  body.    A  sporo- 
cyst residuum  is  present,  usually  compact. 
The  sporozoites  lie  lengthwise  in  sporo- 
cysts, with  2  refractile  globules.    The 
sporulation  time  is  10  to  12  days. 

It  is  possible  that  E.  pellita  is  a  syn- 
onym of  E.  bukidnonensis .     However,  it 
differs  from  it  in  the  velvety  appearance 
described  for  its  oocyst  wall;  the  oocyst 
wall  of  E.  bukidnonensis  has  been  des- 
cribed as  speckled,  and  as  a  matter  of  fact 
Supperer' s  drawing  of  E.  pellita  looks 
speckled,  too.    Other  differences  are  that 
a  sporocyst  residuum  has  not  been  des- 
cribed in  E.  bukidnonensis,    while  E.  pellita 
has  a  prominent  one,  and  the  sporocysts  of 
E.  bukidnonensis  are  somewhat  pointed  at 
one  end  (with  a  Stieda  body?),  while  those 
of  E.  pellita  are  not. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


EIMERIA  SUBSPHERICA 
CHRISTENSEN,   1941 

Hosts:     Ox. 

Location:     Unknown.    Oocysts  found 
in  feces. 


174 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


Geographic  Distribution: 
America. 


North 


Prevalence: 


This  species  is  rela- 
Christensen  (1941) 


tively  uncommon, 
found  it  in  6  calves  in  Alabama,  never  in 
large  numbers.  Hasche  and  Todd  (1959) 
found  it  in  11%  of  355  cattle  in  Wisconsin. 

Morphology:     This  species  has  been 
described  by  Christensen  (1941).     The 
oocysts  are  9  to  13  by  8  to  12 /i  with  a 
mean  of  11.  0  by  10.  4 /J  .    Their  length- 
width  ratio  is  1 .  00  to  1.3  with  a  mean  of 
1.06.     They  are  typically  subspherical, 
but  vary  from  spherical  to  bluntly  ellip- 
soidal.   A  micropyle  is  absent.     The 
oocyst  wall  is  thin,  smooth,   homogeneous, 
transparent,  of  uniform  thickness  thruout, 
and  colorless  to  faintly  yellowish.    An 
oocyst  residuum  and  polar  granule  are 
absent.     The  sporocysts  are  pale,  spindle- 
shaped,  without  a  sporocyst  residuum. 
The  sporulation  time  is  4  to  5  days. 

The  oocysts  of  this  species  might  be 
confused  with  the  smaller,  subspherical 
oocysts  of  E.  ellipsoiclalis  or  E.  ziirnii, 
but  Christensen  (1941)  considered  that 
they  can  be  differentiated  by  their  more 
fragile  appearance,  their  more  delicate 
wall,  and  by  their  requiring  2  days  longer 
to  sporulate. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


EIMERIA   Z  URN II 
(RIVOLTA,   1878) 
MARTIN,   1909 

Synonyms:     Cytospermium  zurnii, 
Eimeria  bovis  (pro  parte),  Eimeria  cana- 
densis (pro  parte). 

Hosts:     Ox,   zebu,  water  buffalo. 
Dahlberg  and  Guettinger  (1956)  reported 
E.  zurnii  in  2  white-tailed  deer  in  Wis- 
consin, and  Salhoff  (1939)  reported  it  in  a 
roe  deer  in  Germany.    Wetzel  and  Enigk 
(1936)  found  it  in  a  wisent  in  Germany. 
Honess  and  Winter  (1956)  recorded  it  from 
the  elk  in  Wyoming. 


Location:     Cecum,  colon,   rectum, 
thruout  small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  is  one  of  the  com- 
moner coccidia  of  cattle.     Boughton  (1945) 
found  it  in  42%  of  2492  bovine  fecal  sam- 
ples in  southeastern  U.S.  ,  and  Hasche  and 
Todd  (1959)  found  it  in  26%  of  355  cattle  in 
Wisconsin.    Supperer  (1952)  found  it  in  11% 
of  130  cattle  in  Austria.     Yakimoff,  Gousseff 
and  Rastegaieff  (1932)  found  it  in  13%  of 
126  oxen  in  Uzbekistan.     Marchenko  (1937) 
found  it  in  20%  of  137  cattle  in  the  North 
Caucasus.    Yakimoff  (1933)  found  it  in  18% 
of  41  oxen,   6%  of  17  zebus  and  37%  of  30 
water  buffaloes  in  Azerbaidzhan.     Tubangui 
(1931)  found  it  in  3  of  28  zebus  and  1  of  11 
carabaos  in  the  Philippines.     Torres  and 
Ramos  (1939)  found  it  in  38%  of  156  cattle 
in  Brazil.     Ruiz  (1959)  found  it  in  1%  of  100 
adult  cattle  in  the  San  Jose,  Costa  Rica 
abattoir. 

Morphology:     The  oocysts  have  been 
described  by  Christensen  (1941)  among 
others.     They  are  15  to  22  by  13  to  18 /i 
with  a  mean  of  17.  8  by  15.  6  ji  .     Their 
length-width  ratio  is  1 .  0  to  1 .  4  with  a 
mean  of  1.14.    They  are  spherical  to 
bluntly  ellipsoidal,  without  a  micropyle. 
The  oocyst  wall  is  thin,  homogeneous, 
transparent,   and  colorless  to  faint  greyish- 
lavender  or  pale  yellow.     An  oocyst  polar 
granule  and  residuum  are  absent.     The 
sporocysts  are  9  to  12  by  6  to  7  fi  according 
to  Yakimoff,  Gousseff  and  Rastegaieff 
(1932).    A  sporocyst  residuum  is  absent. 

Complete  sporulation  occurs  in  9  to 
10  days  at  12°  C,  6  days  at  15%   3  days  at 
20°,  40  hours  at  25°  and  23  to  24  hours  at 
30  to  32.  5°  C;  a  few  oocysts  may  sporulate 
at  temperatures  as  low  as  8°  C  in  several 
months,  but  sporulation  is  not  normal 
above  32°  C  (Marquardt,  Senger  and  Seg- 
hetti,   1960). 

Life  Cycle:     The  endogenous  stages 
of  E.  zuniii  were  described  by  Davis  and 
Bowman  (1957).    Schizonts  are  found  2  to 
19  days  after  experimental  infection  in  the 
epithelial  cells  of  the  upper,  middle  and 
lower  small  intestine,  cecum  and  colon. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


175 


When  mature  they  measure  about  10  by 
13(1  and  contain  24  to  36  merozoites. 
They  lie  distal  to  the  host  cell  nucleus. 
Merozoites  are  first  seen  7  days  after  in- 
fection.   They  are  about  5  by  12jll,  have 
their  nucleus  near  the  tapering  end  and 
contain  2  refractile  globules.    Davis  and 
Bowman  did  not  determine  the  number  of 
asexual  generations,  but  believed  that 
there  is  more  than  one.     The  mature  schi- 
zonts  late  in  the  cycle  are  slightly  larger 
than  the  early  ones. 

Macrogametes  are  first  seen  12  days 
after  infection.     They  occur  in  the  epithel- 
ial cells  of  the  glands  and  to  a  lesser  ex- 
tent of  the  surface  of  the  lower  small  in- 
testine, cecum,   colon  and  rectum,  and 
rarely  in  the  upper  small  intestine.     They 
are  about  11  by  14ji  and  contain  1  or  2 
rows  of  plastic  granules.     Microgameto- 
cytes  are  first  seen  15  days  after  infection 
in  the  same  location  as  the  macrogametes. 
They  measure  about  10  by  I4.fi  when  ma- 
ture.    Immature  oocysts  are  first  seen  12 
days  after  infection. 

Pathogenesis:     E.  ziirnii  is  the  most 
pathogenic  coccidium  of  cattle.     In  acute 
infections  it  causes  a  bloody  diarrhea  of 
calves.    At  first  the  feces  are  streaked 
with  blood.     The  diarrhea  becomes  more 
severe,  bloody  fluid,  clots  of  blood  and 
liquid  feces  are  passed,  and  straining  and 
coughing  may  cause  this  mixture  to  spurt 
out  as  much  as  6  to  8  feet.     The  animal's 
rear  quarters  may  look  as  tho  they  had 
been  smeared  with  red  paint.    Anemia, 
weakness  and  emaciation  accompany  the 
dysentery,  and  secondary  infections,  es- 
pecially pneumonia,  are  common.     This 
acute  phase  may  continue  for  3  or  4  days. 
If  the  calf  does  not  die  in  7  to  10  days,  it 
will  probably  recover. 

E.   zurnii  may  also  be  associated  with 
a  more  chronic  type  of  disease.    Diarrhea 
is  present,  but  there  may  be  little  or  no 
blood  in  the  feces.     The  animals  are  em- 
aciated, dehydrated,  weak  and  listless, 
with  rough  hair  coats,  drooping  ears  and 
sunken  eyes. 

The  lesions  of  coccidiosis  have  been 
described  by  Boughton  (1945)  and  Davis 


and  Bowman  (1952)  among  others.    A  gen- 
eralized catarrhal  enteritis  involving  both 
the  small  and  large  intestines  is  present. 
The  lower  small  intestine,  cecum  and  colon 
may  be  filled  with  semi-fluid,  bloody  ma- 
terial.    Large  or  smaller  areas  of  the  in- 
testinal mucosa  may  be  eroded  and  des- 
troyed, and  the  mucous  membrane  may  be 
thickened,  with  irregular  whitish  ridges  in 
the  large  intestine  or  smooth,  dull  grey 
areas  in  the  small  intestine  or  cecum. 
Diffuse  hemorrhages  are  present  in  the 
intestines  in  acute  cases,  and  petechia;l 
hemorrhages  in  mild  ones. 


EIMERIA  BOMBA  YANSIS 
RAO  AND   HIREGAUDAR,   1954 


Host:    Zebu. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     India. 

Prevalence:     Unknown.     Rao  and 
Hiregaudar  (1954)  stated  that  its  preva- 
lence was  great  in  calves  in  a  dairy  herd 
near  Bombay. 

Morphology:     The  oocysts  measure 
32  to  40  by  20  to  25  |i  with  a  mean  of  37  by 
22.4jLL.     They  are  ellipsoidal,  tending  to- 
ward the  cylindrical,  some  with  parallel 
sides  and  others  with  1  side  straight  and 
the  other  slightly  convex.     The  micropyle 
is  2  to  4 ji  in  diameter,  with  a  thickened 
wall  around  it.     The  oocyst  wall  is  smooth, 
transparent,   homogeneous,   pale  yellowish 
brown,   1  to  1.5/i  thick.     The  sporocysts 
are  12  to  15(j,  long,  oval,  with  1  end  a 
little  more  pointed  than  the  other.    An 
oocyst  residuum  is  absent,  but  a  sporocyst 
residuum  is  present.     The  sporozoites  are 
4  to  6  |i  long.     The  sporulation  time  is  2 
to  3  days. 

Pathogenesis:     Unknown. 


EIMERIA  MUNDARAGI 
fflREGAUDAR,   1956 

Host:    Zebu. 


176 


THE  TELOSPORASIDA   AND  THE  COCCIDLA    PROPER 


J    ^<:c^" 


Fig.  25.      Coccidia  of  cattle.     A.   Eimeria  subspherica  unsporulated  oocyst.     B.   E.  zurnii 
unsporulated  oocyst.     C.   E.  ellipsoidalis  unsporulated  oocyst.    D.   E.  cyliii- 
(/>-;c(7  unsporulated  oocyst.     E.    E.  a/a/ja)(u'«s(*-  unsporulated  oocyst. 
F.    E.  bukiduouensis  unsporulated  oocyst.    G.    E.  6oi7i' unsporulated  oocyst. 
H.    E.  caHarfe«s/s  unsporulated  oocyst.    I.    E.  n»6io-«e«s/s  unsporulated 
oocyst.    J.   E.  aiibiiniensis  unsporulated  oocyst  with  maniniillated  wall. 
K.    Isospora  sp.  sporulated  oocyst  from  cattle.     L.  Isospora  Incazci   sporu- 
lated  oocyst  from  English  sparrow;  note  the  close  resemblance  to  Fig.   K. 
(A. -J.,  X  1150,  from  Christensen,   1941;  K. -L. ,  X  2300,  from  Levine  and 
Mohan,   1960) 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


177 


Location:     Unknown.     Oocysts  found 


in  feces. 


Geographic  Distribution:     India  (Bom- 
bay). 

Prevalence:     Hiregaudar  (1956)  des- 
cribed this  species  from  a  single  calf. 

Morphology:     The  oocysts  are  ovoid, 
36  to  38  by  25  to  28  ji .     The  oocyst  wall  is 
0.3jn  thick,  slightly  thicker  toward  micro- 
pylar  end,   smooth,  transparent,  and  pale 
yellow  or  yellow.     The  micropyle  is  dis- 
tinct, 0.5|j.  in  diameter.     The  sporocysts 
are  oval,   15  to  9 /j,,  thinning  at  the  pointed 
end.     The  sporozoites  are  4  to  6  by  1  to  3/1 
and  finely  granular.     An  oocyst  residuum 
and  polar  granule  are  absent.    A  sporocyst 
residuum  is  present.     The  sporulation 
time  is  1  to  2  days  during  the  summer. 
The  extremely  thin  wall  and  the  tiny,  dis- 
tinct micropyle  may  differentiate  this 
species  from  other  bovine  coccidia.     How- 
ever, the  possibility  must  not  be  over- 
looked that  these  oocysts  may  be  those  of 
a  species  such  as  E.  bukkliioiiensis  from 
which  the  thick,  brittle  outer  wall  has 
cracked  off. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


COCCIDIOSIS   IN   CATTLE 

Epidemiology:     Infections  with  a 
single  species  of  coccidium  are  rare  in 
nature;  mixed  infections  are  the  rule. 
Ei))ieria  ziiynii  and  E.  bovis  are  the  most 
pathogenic  species,  but  E.  auburnensis 
and  the  other  species  may  contribute  to 
the  total  disease  picture,  and  some  of 
them  may  cause  marked  signs  by  them- 
selves if  they  are  present  in  large  enough 
numbers. 

Bovine  coccidiosis  is  primarily  a 
disease  of  young  animals.    It  ordinarily 
occurs  in  calves  3  weeks  to  6  months  old. 
Older  calves  and  even  adult  animals  may 
be  affected  under  conditions  of  gross  con- 
tamination, but  they  are  usually  symptom- 
less carriers. 


Calves  become  infected  by  ingesting 
oocysts  along  with  their  feed  or  water. 
The  severity  of  the  disease  depends  upon 
the  number  of  oocysts  they  receive.    If 
they  get  only  a  few,  there  are  no  symptoms, 
and  repeated  infections  produce  immunity 
without  disease.    If  they  get  more,  the 
disease  may  be  mild  and  immunity  may 
also  develop.     It  they  get  a  large  number, 
severe  disease  and  even  death  may  result. 

Crowding  and  lack  of  sanitation  greatly 
increase  the  disease  hazard.    Successive 
passage  of  coccidia  from  one  animal  to 
another  often  builds  up  infection  to  a  patho- 
genic level,  since  in  each  passage  the  re- 
cipient receives  more  oocysts  than  in  the 
previous  one.     This  is  the  reason  for  the 
common  observation  that  calves  placed  in 
a  lot  where  others  are  already  present  may 
suffer  more  from  coccidiosis  than  those 
which  were  there  first.    This  successive 
passage  from  a  carrier  to  a  symptomless 
"multiplier"  to  a  sub-clinical  case  to  a 
fatal  case  was  described  by  Boughton 
(1945)  as  typical  of  the  transmission  of 
bovine  coccidiosis.     In  addition,  it  is 
likely  that  recycling  by  repeated  infections 
of  a  single  individual  may  also  play  an  im- 
portant part. 

A  little -understood  type  of  bovine 
coccidiosis  is  winter  coccidiosis.     This 
occurs  when  it  is  so  cold  that  oocyst  spor- 
ulation should  be  minimal  if  it  occurs  at 
all.     Presumably  there  is  enough  heat  in 
the  bedding  to  permit  sporulation.    Another 
explanation  which  has  been  advanced  is 
that  the  stress  of  winter  conditions  exacer- 
bates a  latent  infection.     This  explanation 
is  not  easy  to  validate,  however,  in  view 
of  the  self-limiting  nature  of  coccidial 
infections. 

Davis,   Herlich  and  Bowman  (1959, 
1959a,   1960,   1960a)  found  that  concurrent 
infections  of  cattle  with  the  nematodes, 
Trichostrotigylus  colubrifonnis  or  Coop- 
eria  punctata,  exacerbated  the  effects  of 
coccidia  in  calves,  but  that  Ostertagia 
ostertagi  and  Strongyloides  papillosus  had 
no  such  effect. 

Diagnosis:     Bovine  coccidiosis  can 
be  diagnosed  from  a  combination  of  history, 


178 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


signs,  gross  lesions  at  necropsy  and  mi- 
croscopic examination  of  scrapings  of  the 
intestinal  mucosa  and  of  feces.    Diarrhea 
or  dysentery  accompanied  by  anemia, 
weakness,  emaciation  and  inappetance  are 
suggestive  of  coccidiosis  in  calves.    Sec- 
ondary pneumonia  is  often  present.     The 
lesions  found  at  necropsy  have  already 
been  described. 

Microscopic  examination  is  necessary 
to  determine  whether  the  lesions  are  due 
to  coccidia  or  to  some  other  agent.    How- 
ever, diagnoses  will  often  be  missed  if 
one  relies  only  on  finding  oocysts  in  the 
feces.    There  may  be  none  there  at  all  in 
the  acute  stage  of  zurnii  coccidiosis. 
Similarly,  the  mere  presence  of  oocysts 
in  the  feces  is  not  proof  that  coccidiosis 
is  present;  it  may  be  coccidiasis.    To  be 
sure  of  a  diagnosis,  scrapings  should  be 
made  from  the  affected  intestinal  mucosa 
and  examined  under  the  microscope.     It  is 
not  enough  to  look  for  oocysts,   however, 
but  schizonts,  merozoites  and  young  gam- 
etes should  be  recognized. 

Treatment:     A  number  of  investigators 
(Boughton,   1943;  Boughton  and  Davis, 
1943;  Davis  and  Bowman,-  1952,   1954; 
Hammond  et  al .  .    1956;  Senger  et  al.  .  1959) 
have  found  that  the  sulfonamides  have  some 
value  against  bovine  coccidiosis. 

Other  types  of  compounds  which  are 
used  in  avian  coccidiosis  are  unsatisfac- 
tory.    For  example,   Hammond  el  al.  (1957) 
found  that  nicarbazin  was  effective  in  pre- 
venting experimental  coccidiosis  due  to 
E.  bovis  in  calves  only  at  doses  which 
were  toxic  to  the  animals.     Gardner  and 
Wittorff  (1955)  found  that  0. 1  to  0.  3% 
furacin  in  the  ration  was  toxic  to  dairy 
calves,  causing  nervous  signs  and  reducing 
or  preventing  weight  gains.     Even  0.01% 
of  the  drug  had  some  toxic  effect.    It  in- 
jures the  myelin  sheaths  and  causes  cere- 
bral damage. 

Gasparini,  Roncalli  and  Ruffini  (1958) 
claimed  that  drenching  with  4  g  per  100  kg 
ammonium  sulfate  plus  2  ml  lactic  acid  in 
a  liter  of  milk  twice  a  day  for  4  consecu- 
tive days  cured  coccidiosis  due  to  E.  zurnii 
in  2  herds  of  cattle  in  Italy,    They  believed 


that  the  ammonium  sulfate  worked  by  re- 
leasing ammonia,  and  added  the  lactic  acid 
to  prevent  release  from  taking  place  in  the 
stomach.     However,  their  work  was  im- 
properly controlled,  and  the  efficacy  of 
this  compound  remains  to  be  determined. 

Sulfamethazine  and  sulfamerazine  ap- 
pear to  be  better  than  sulfaquinoxaline  or 
other  suKonamides.     They  are  only  par- 
tially effective,  however.    They  do  not 
prevent  the  diarrhea,  but  they  do  reduce 
the  severity  of  the  disease.     Thus,  Davis 
and  Bowman  (1954)  found  that  sulfametha- 
zine reduced  the  severity  of  experimental 
infections  with  E.  ziirnii  or  mixed  species 
in  calves  and  that  treated  calves  gained 
slightly  more  weight  than  the  controls. 
Drug  treatment  was  started  before  infec- 
tion, and  no  immunity  to  subsequent  expo- 
sures was  produced.     Hammond  cl  al. 
(1956)  found  that  sulfamerazine  or  sulfa- 
quinoxaline, given  to  calves  at  the  rate  of 
0.  143  g  per  kg  body  weight  for  2  days  and 
0.  072  g  per  kg  for  2  more  days,  decreased 
the  severity  of  coccidiosis  due  to  E.   bovis 
if  they  were  administered  between  13  and 
17  days  after  experimental  infection. 
They  were  not  effective  earlier  or  later 
than  this.     The  drugs  presumably  act  on 
the  merozoites  after  their  release  from 
the  schizonts.    Senger  el  al.  (1959)  found 
that  a  mixture  of  equal  parts  sulfamerazine 
and  sulfamethazine  given  by  mouth  at  the 
rate  of  213,   143  and  70  mg  per  kg  body 
weight  13,   14  and  15  days,   respectively, 
after  inoculation  reduced  the  severity  of 
the  disease  and  did  not  interfere  with  the 
development  of  immunity. 

Hammond  el  al.  (1959)  found  that  a 
single  treatment  with  0.  215  g  per  kg  sulfa- 
methazine or  sulfabromomethazine  13  days 
after  experimental  inoculation  with  E.   bovis 
effectively  controlled  coccidiosis.    Admin- 
istration of  either  compound  on  alternate 
days  at  the  rate  of  0.0215  g  per  kg  for  as 
short  a  period  as  10  to  18  days  after  inoc- 
ulation also  effectively  controlled  coccid- 
iosis, while  in  1  experiment  treatment  at 
this  rate  12  and  14  days  after  inoculation 
suppressed  the  disease.    This  treatment 
did  not  interfere  with  the  development  of 
immunity. 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


179 


Since  the  sulfonamides  are  generally 
only  partially  effective,  preventive  mea- 
sures are  more  important  than  curative 
ones. 

Prevention:     Sanitation  and  isolation 
are  effective  in  preventing  coccidiosis. 
Beef  calves  should  be  dropped  and  kept  on 
clean,  well  drained  pastures.     Overstock- 
ing and  crowding  should  be  avoided.     Feed 
and  water  containers  should  be  high  enough 
to  prevent  fecal  contamination.     Feed  lots 
should  be  kept  dry  and  should  be  cleaned 
as  often  as  possible.     Concrete  or  small 
gravel  are  preferable  to  dirt. 

Dairy  calves  should  be  isolated  within 
24  hours  after  birth  and  kept  separately. 
Individual  box  stalls  which  are  cleaned 
daily  may  be  used.    Slat-bottom  pens  are 
also  effective  and  require  less  cleaning. 
Allen  and  Duffee  (1958)  described  a  simple, 
raised,  wooden  home-made  stall  with  a  4 
by  2-1/2  foot  slatted  floor  in  which  dairy 
calves  can  be  raised  separately  for  the 
first  3  months.    Davis  (1949)  and  Davis 
and  Bowman  (1952)  described  a  5  x  10  x  3 
foot  outdoor  portable  pen  which  can  be 
moved  to  a  fresh  site  once  a  week  and  thus 
eliminates  the  need  for  cleaning.     It  is 
made  primarily  of  net  wire  and  1x4  lum- 
ber, with  a  removable  roof  and  siding  at 
one  end.     The  pens  should  not  be  returned 
to  the  same  ground  for  a  year. 

These  methods  will  not  eliminate  all 
coccidia,  but  they  will  prevent  the  calves 
from  picking  up  enough  oocysts  to  harm 
them.     In  addition,  they  will  greatly  reduce 
lice,   helminth  parasites,   pneumonia, 
white  scours  and  other  diseases. 

The  unsporulated  oocysts  of  E.  zurnii 
are  killed  by  sunlight  in  4  hours  or  by  dry- 
ing at  25%  relative  humidity  or  below  in 
several  days.     They  are  not  harmed  by 
freezing  at  -7  to  -8°  C  for  as  long  as  2 
months,  and  half  of  them  survive  as  long 
as  5  months;  at  -30 °C,   however,  only  5% 
survive  1  day.    The  oocysts  are  killed  by 
10"^  M  mercuric  chloride,  0.05  M  phenol, 
0.  25  M  formaldehyde,   1.  25%  sodium  hypo- 
chlorite, or  0.  5%  cresol  (Marquardt,  Sen- 
ger  and  Seghetti,  1960). 


EIMERIA  AHSATA 
HONESS,   1942  emend. 

Synonym:      Eimeria  ah-sa-ia  Honess, 
1942. 

Hosts:     Sheep,  Rocky  Mountain  big- 
horn sheep. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     North  Amer- 
ica (Wyoming,  Alabama). 

Prevalence:     Unknown. 

Morphology:     The  oocysts  are  ellip- 
soidal and  faint  pink.     The  oocyst  wall  is 
faint  straw-colored  and  lined  by  a  mem- 
brane.    A  micropyle  and  micropylar  cap 
are  present.     Oocysts  from  the  bighorn 
sheep  are  30  to  40  by  20  to  30|Lt  with  a 
mean  of  32.  7  by  23.  7  |j, ;  their  length- width 
ratio  is  1.1  to  1.8  with  a  mean  of  1 .  40; 
the  micropylar  cap  is  0.  4  to  4.  2  jn  high  and 
2.  1  to  12.  5)n  wide  with  a  mean  of  2. 1  by 
l.^li.    Oocysts  from  domestic  sheep  are 
29  to  37  by  17  to  28  ^i  with  a  mean  of  33.4 
by  22.6ju;  their  length-width  ratio  is  1.2 
to  1 .  8  with  a  mean  of  1 .  48;  the  micropylar 
cap  is  1.7  to  4.  2/i  high  and  5.  9  to  13.  4jj, 
wide  with  a  mean  of  3.  0  by  8.  4  |_i .     An 
oocyst  residuum  is  present  in  some  oocysts. 
Oocyst  polar  (?)  granules  are  almost  al- 
ways present.     The  sporocysts  are  15.4 
by  7.  8jj.  and  have  a  sporocyst  residuum. 

This  species  is  difficult  to  distinguish 
from  E.  arlouigi,   and  Morgan  and  Hawkins 
(1952)  and  Lotze  (1953)  considered  it  of 
doubtful  validity.     However,  Smith,  Davis 
and  Bowman  (1960)  rediscovered  it  in  Ala- 
bama and  confirmed  its  distinctiveness. 

Life  Cycle:  Unknown.  The  prepatent 
period  is  18  to  20  days  according  to  Smith, 
Davis  and  Bowman  (1960). 

Pathogenesis:     Smith,  Davis  and  Bow- 
man (1960)  considered  this  the  most  patho- 
genic of  all  sheep  coccidia.    They  produced 
fatal  infections  in  4  out  of  9  lambs  1  to  3 
months  old  by  feeding  100,  000  oocysts. 


180 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


The  intestines  of  infected  lambs  had  thick- 
ened, somewhat  edematous  areas  in  the 
upper  part.    The  Peyer's  patches  and  the 
last  8  to  10  inches  of  the  small  intestine 
above  the  ileocecal  valve  were  inflamed. 


EIMERIA  ARLOINGI 
(MAROTEL,    1905) 
MARTIN,   1909 

Hosts:     Sheep,  goat.  Rocky  Mountain 
bighorn  sheep,   Ovis  »iusl)>ioii,   O.  polii. 
Copra  ibex,  Hemmilragus  jenilaicus,  roe 
deer. 

Location:     Small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  is  probably  the 
most  common  coccidium  in  sheep.     Chris- 
tensen  (1938a)  found  it  in  90%  of  100  sheep 
from  Idaho,  Maryland,   New  York  and 
Wyoming.     Balozet  (1932)  found  it  in  52% 
of  63  sheep  and  56%  of  41  goats  in  Tunisia. 
Jacob  (1943)  found  it  in  58%  of  100  sheep 
and  18%  of  11  goats  in  Germany.    Svanbaev 
(1957)  found  it  in  52%  of  302  sheep  and  52% 
of  48  goats  in  Kazakhstan. 

Morphology:     The  oocysts  are  usually 
elongate  ellipsoidal,  but  are  sometimes 
asymmetrical,  with  one  side  curved  more 
than  the  other,  or  slightly  ovoid.     They 
are  17  to  42  by  13  to  27 /i  with  a  mean  of 
27  by  18/i;  their  length-width  ratio  is  1.  1 
to  1.9  with  a  mean  of  1.49  (Christensen, 
1938a).     The  oocyst  wall  is  1.0  to  1.  5  fi 
thick,  transparent,  almost  colorless  to 
yellowish-brown,  and  composed  of  2 
layers,  the  outer  one  being  half  as  thick 
as  the  inner,  according  to  Christensen 
(1938a).    The  oocyst  wall  is  apparently 
lined  by  a  membrane.    A  micropyle  2  to 
3(1  in  diameter  is  present.    A  micropylar 
cap  is  present;  it  varies  from  an  incon- 
spicuous, flat  structure  to  a  prominent, 
transparent,   pale  yellow  to  yellowish- 
green  rounded  cone  or  crescent,  0.2  to 
2[x  high  by  3  to  8  fi  wide  with  a  mean  of 
1.2  by  5/i.     This  cap  is  a  tough,   lid-like 
structure  which  is  easily  dislodged  and 
may  be  lost  in  some  specimens.    An 
oocyst  residuum  is  absent.    An  oocyst 


polar  granule  is  present  according  to 
Balozet  (1932).    The  sporocysts  are  ovoid, 
13  by  6/1.    A  sporocyst  residuum  is  pres- 
ent.    The  sporulation  time  is  1  to  2  days 
(Christensen,   1938a)  to  3  to  4  days  (Balo- 
zet,  1932). 

Life  Cycle:     Lotze  (1953a)  studied  the 
life  cycle  of  E.  arloiiigi  in  experimentally 
infected  lambs.     The  sporozoites  emerge 
from  the  oocysts  in  the  small  intestine, 
enter  the  crypts  of  Lieberkuehn,  and  pene- 
trate thru  the  tunica  propria  into  the  in- 
terior of  the  villi.     Here  they  enter  the 
endothelial  cells  lining  the  central  lacteals 
and  grow.    The  host  cell  also  grows,  and 
its  nucleus  becomes  very  large.    There  is 
apparently  only  1  generation  of  schizonts 
and  merozoites.     The  schizonts  become 
mature  13  to  21  days  after  infection.    At 
this  time  they  are  about  122  to  146 /i  in 
diameter  and  contain  a  large  number 
(probably  millions)  of  merozoites  about 
9/i  long  and  2 /i  wide. 

The  merozoites  break  out  of  the  schi- 
zonts and  enter  the  epithelial  cells  of  the 
small  intestine.    Sometimes  only  a  small 
group  of  cells  at  the  bottom  of  the  crypts 
is  parasitized,  but  in  heavy  infections 
practically  all  the  epithelial  cells  of  the 
villi  are  invaded.     The  infected  villi  are 
enlarged  and  greyish.    Some  of  these 
merozoites  become  microgametocytes; 
these  form  many  microgametes,  leaving 
a  large  mass  of  residual  material.    Most 
of  the  merozoites  become  macrogametes, 
which  contain  large  plastic  granules  when 
mature. 

Following  fertilization,  the  macro- 
gametes  turn  into  oocysts,  which  break 
out  of  the  host  cells  and  are  first  seen  in 
the  feces  on  the  20th  day  after  infection. 
Their  numbers  increase  for  about  5  days 
and  then  decrease  at  about  the  same  rate 
for  the  next  5  days.     Thus  the  prepatent 
period  is  19  days  and  the  patent  period 
about  10  days  following  a  single  exposure. 

Pathogenesis:     Lotze  (1952)  studied 
the  pathogenicity  of  E.  arloiiigi  in  3- 
month-old  lambs  experimentally  infected 
with  200,000  to  60  million  oocysts.    No 
visible  signs  were  produced  by  infections 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


181 


with  1  million  oocysts  or  less.     In  lambs 
infected  with  3  or  5  million  oocysts,  the 
feces  became  soft  on  the  13th  day  and  then 
returned  to  normal  during  the  next  6  days. 
The  health,  general  condition  and  weight 
gains  of  these  animals  were  not  affected. 

Severe  diarrhea  was  produced  with 
higher  doses,  but  none  of  the  animals 
died  altho  one  was  killed  in  extremis.     In 
general,  the  experimentally  infected  lambs 
appeared  normal  up  to  the  13th  day  after 
inoculation,  when  their  feces  became  soft. 
In  the  more  heavily  infected  lambs  the 
feces  then  became  watery,  and  diarrhea 
was  severe  beginning  on  the  15th  day. 
Blood-tinged  mucus  was  passed  by  affected 
lambs  only  occasionally.     The  feces  began 
to  return  to  normal  on  the  17th  day  and 
were  usually  nearly  normal  by  the  20th 
day.     Lambs  with  marked  diarrhea  be- 
came weak  and  refused  feed. 

At  necropsy,  only  a  few  small, 
slightly  hemorrhagic  areas  scattered 
thruout  the  lining  of  the  small  intestine 
were  seen  up  to  the  13th  day.     From  the 
13th  to  19th  days  the  small  intestine  was 
more  or  less  thickened  and  edematous, 
and  thick,  white  opaque  patches  made  up 
of  groups  of  heavily  parasitized  villi  were 
present. 

The  villi  containing  the  schizonts  be- 
come thin-walled  sacs  and  are  presumably 
destroyed.    The  sexual  stages  are  clus- 
tered in  the  epithelial  cells  of  the  villi 
and  destroy  these  cells  when  they  emerge. 
However,  they  do  not  do  as  much  damage 
'as  the  asexual  stages,  since  the  condition 
of  affected  animals  appears  to  improve 
before  oocysts  are  shed. 

E.  arloingi  is  less  pathogenic  than 
E.  ninakohlyakimovae . 

Epidemiology:     This  species  has 
been  reported  not  only  from  domestic 
sheep  and  goats  but  also  from  the  Rocky 
Mountain  bighorn  sheep  [Ovis  canadensis), 
moufflon  (O.   musimon),  argali  (O.  animon 
polii),  ihex  {Capra  ibex),  and  Hem )nitra- 
gus  jemlaicus  (see  especially  Yakimoff, 
1933a).     Ullrich  (1930)  found  it  in  the  roe 
deer.    Whether  the  forms  from  all  these 
animals  are  really  E.  arloingi  remains  to 


and  cross-transmission  experiments. 
According  to  Lotze  (1953),  no  cross-trans- 
mission studies,  even  between  domestic 
sheep  and  goats,  have  been  reported  up  un- 
til the  time  of  his  paper,  and  he  attempted 
none. 


EIMERIA   CRANDALLIS 
HONESS,   1942 

Hosts:     Sheep,   Rocky  Mountain  big- 
horn sheep.    This  species  was  originally 
described  from  the  bighorn  sheep,  but 
Hawkins  (in  Morgan  and  Hawkins,   1952) 
found  it  in  domestic  sheep. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     North 
America  (Wyoming,  Michigan). 

Prevalence:     Unknown. 

Morphology:     The  oocysts  are  spher- 
ical to  broadly  ellipsoidal  to  ovoid,  color- 
less to  faint  pink  or  greenish,  and  are  17 
to  23  by  17  to  22  jj.  with  a  mean  of  21.  9  by 
19.4|ji.     Their  length-width  ratio  is  1.00 
to  1.  35  with  a  mean  of  1. 11.    A  micro- 
pyle  and  micropylar  cap  are  present.    The 
micropylar  cap  measures  from  a  trace  to 
1 .  7  |i  high  and  3.  3  to  6.  6  /ji  wide  with  a 
mean  of  0.  8jj,  high  and  4.  9fi  wide.     The 
oocyst  wall  has  a  distinctly  demarcated 
outer  edge,  a  feature  which  Honess  (1942) 
considered  to  distinguish  this  species 
from  E.  arloingi.      The  sporocysts  are  8 
to  11  by  5  to  8  fj.  with  a  mean  of  9.  5  by 
6.  4|i  .     No  information  is  available  on 
oocyst  polar  granule,  oocyst  residuum  or 
sporocyst  residuum. 

Lotze  (1953)  considered  that  this  spe- 
cies was  of  doubtful  validity,  since  its 
oocysts  fall  into  the  size  range  of  E. 
arloingi.   but  Morgan  and  Hawkins  (1952) 
accepted  it,  stating  that  Hawkins  had  found 
that  its  peak  of  infection  in  Michigan  oc- 
curred at  a  different  time  from  that  of  E. 
arloi)igi. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


182 


THF  TFLOSPORASIDA   AND  THF  COCCrDIA    PROPER 


EIMERIA   FAUREI 

(MOUSSU   AND  MAROTEL,   1902) 

MARTIN,   1909 

Synonym:     Einieria  aemula. 

Hosts:     Sheep,  goat.  Rocky  Mountain 
bighorn  sheep,   Ovis  amnion  polii,   O. 
musinion,    O.  orienlalis.   Capra  ibex, 
Rupicapra  rupicapra  (chamois),  Ammotra- 
gus  lervia  {Barbary  sheep). 

Location:     Small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  fairly 
common.     Christensen  (1938a)  found  it  in 
11%  of  100  sheep  from  Idaho,   Maryland, 
New  York  and  Wyoming.     Balozet  (1932) 
found  it  in  21%  of  63  sheep  and  2%  of  41 
goats  in  Tunisia.    Jacob  (1943)  found  it  in 
40%  of  100  sheep  and  18%  of  11  goats  in 
Germany.    Svanbaev  (1957)  found  it  in  43% 
of  302  sheep  and  40%  of  48  goats  in  Kozak- 
hstan. 

Morphology:     The  following  descrip- 
tion is  based  primarily  on  those  of  Chris- 
tensen (1938a)  and  Balozet  (1932).     The 
oocysts  are  ovoid,  25  to  35  by  18  to  24|i , 
with  a  mean  of  28.  9  by  21.  Oj^t  according  to 
Christensen  or  31.  5  by  22.  1  ju.  according 
to  Balozet.     The  oocyst  wall  is  transparent, 
delicate  salmon  pink  to  pale  yellowish 
brown,   1  ^  thick  at  the  most  according  to 
Balozet;  with  a  faint,  yellowish-green 
"external  coat  .  .  .  about  half  as  thick  as 
wall"  according  to  Christensen.     The  mi- 
cropyle  is  conspicuous,  2  to  3fi  in  diam- 
eter, at  the  small  end.    A  micropylar  cap 
is  absent.    An  oocyst  polar  granule  was 
illustrated  by  Balozet  (1932).     Oocyst  and 
sporocyst  residua  are  absent.     The  sporu- 
lation  time  is  1  to  2  days  according  to 
Christensen,   3  to  4  days  according  to 
Balozet. 

Life  Cycle:     The  life  cycle  of  E. 
faitrei  does  not  seem  to  have  been  worked 
out  in  detail.    According  to  Lotze  (1953), 
its  schizonts  are  about  100  (i  in  diameter 
and  contain  thousands  of  merozoites. 


Pathogenesis: 
mildly  pathogenic. 


This  species  is  only 
Lotze  (1954) found 


that  single  infections  of  3-month-old  lambs 
with  5  million  oocysts  produced  only  a  tem- 
porary softening  of  the  feces  without  signifi- 
cantly affecting  the  general  health  or  physical 
condition  of  the  animals,  and  infections  with 
50  million  oocysts  failed  to  cause  death. 

Epidemiology:     This  species  has  been 
reported  not  only  from  the  domestic  sheep 
and  goat  but  also  from  the  Rocky  Mountain 
bighorn  sheep  (Ovis  canadensis),  moufflon 
(O.  am))2on),  urial  or  shapo  (O.  orienlalis), 
Barbary  sheep  [Amniulragus  lervia),   ibex 
(Capra  ibex)  and  chamois  (Rupicapra  rupi- 
capra) (see  especially  Yakimoff,   1933). 
Whether  the  forms  from  these  species  are 
all  E.  fanrei  remains  to  be  proven  by  care- 
ful study  of  their  oocysts  and  cross-trans- 
mission experiments.     According  to  Lotze 
(1953),  no  cross-transmission  studies, 
even  between  domestic  sheep  and  goats, 
had  been  reported  up  until  the  time  of  his 
paper,  and  he  attempted  none. 


EIMERIA   GILRUTHI 

(CHATTON,   1910) 

REICHENOW  AND   CARINI,   1937 

Synonyms:     Gastrocystis  gilruthi, 
Globidimn  gilruthi. 

Hosts:     Sheep,  goat. 

Location:     Abomasum,  seldom  small 
intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  form  is  very  com- 
mon in  Europe.     Chatton  (1910)  and  Triffitt 
(1928)  found  it  in  the  abomasa  of  almost  all 
the  sheep  they  examined  in  France  and  Eng- 
land,  respectively.     Alicata  (1930)  found  it 
in  9%  of  78  sheep  in  Indiana,   11%  of  101 
sheep  from  West  Virginia  and  8%  of  72  sheep 
from  Idaho.     It  has  also  been  seen  in  Mon- 
tana, Wyoming,   Michigan  (Morgan  and 
Hawkins,   1952)  and  Illinois.    Sarwar(1951) 
found  it  in  34%  of  the  sheep  and  goats 
slaughtered  at  the  Lahore,   Pakistan  abattoir, 
and  found  it  in  as  many  as  94%  in  other  parts 
of  East  Punjab.     Soliman  (1958)  found  it  in 
18%  of  250  sheep  and  28%.  of  150  goats 
slaughtered  in  Egypt.    Soliman  (1960)  found 
it  in  32%  of  425  sheep  and  40%  of  240  goats 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


183 


in  the  Sudan.     Rac  and  Willson  (1959)  re- 
ported it  in  Australia. 

Morphology:     Only  the  schizonts  and 
merozoites  of  this  form  have  been  des- 
cribed.    The  schizonts  occur  in  the  con- 
nective tissue  of  the  abomasal  wall.    They 
are  300  to  700  ^i  long  and  300  to  465 |i  wide, 
and  are  easily  visible  to  the  naked  eye  as 
whitish  nodules.     The  host  cell  nucleus  is 
flattened  and  greatly  enlarged.     The  ma- 
ture schizonts  are  filled  with  many  thou- 
sands of  crescent-shaped  merozoites 
about  4.  5  to  7.  5 ;i  long  and  1.  2  to  2.  Opt 
wide.    One  end  of  the  merozoites  is 
rounded  and  the  other  pointed.     The  nucleus 
is  near  the  broad  end,  and  a  heavily  stain- 
ing granule  is  in  the  center. 

These  schizonts  are  undoubtedly 
those  of  a  species  of  Eimeria  presently 
known  from  its  oocysts  alone,  but  we  do 
not  know  which  species  it  is.     Reichenow 
(1940)  said  that  it  was  very  probably  E. 
intricata.     Becker  (1956)  agreed  and,  since 
the  specific  name  gilrnthi  has  priority, 
synonymized  E.   intricata  with  it.     How- 
ever, Kotlan,   Pelle'rdy  and  Verse'nyi 
(1951,  1951a)  found  two  types  of  giant 
schizonts  in  sheep.     One  type,  which 
measured  64  to  256  by  48  to  179/i  and  con- 
tained straight,  slender  merozoites  10  to 
12  |i  long,  they  found  to  be  those  of  E.parva. 
The  other  type  of  schizont  was  larger  and 
contained  merozoites  about  16  fx  long  which 
were  bent  like  a  hoe  at  one  end  ("hacken- 
formigen").    These  they  said  were  those 
ofE.  intricata.      However,  they  saw  both 
schizonts  in  the  small  intestine  and  not  in 
the  abomasum,  and  they  used  only  2  lambs 
in  their  work.     Hence,   it  is  felt  best  for 
the  present  not  to  attempt  to  assign  the 
gilruthi  schizonts  to  any  other  species  of 
Eimeria. 


Geographic  Distribution: 
America,   Europe  (Germany). 


North 


Prevalence:     This  species  is  rela- 
tively uncommon  in  sheep.     Christensen 
(1938a)  found  in  in  10%  of  100  sheep  from 
Maryland  and  New  York.    Jacob  (1943) 
found  it  in  1%  of  100  sheep  in  Germany. 
Honess  (1942)  remarked  that  it  was  more 
frequent  and  numerous  in  bighorn  sheep 
than  in  domestic  sheep  in  Wyoming. 

Morphology:     This  species  has  been 
described  by  Christensen  (1938a).     The 
oocysts  are  piriform  or  shaped  like  a 
stout,  broad-shouldered  urn,  with  the  mi- 
cropyle  and  micropylar  cap  at  the  broad 
end;  small  oocysts  are  often  bluntly  ellip- 
soidal.    The  oocysts  are  22  to  35  by  17  to 
25^1  with  a  mean  of  29.4  by  20.9 fi.     Their 
length-width  ratio  is  1 .  2  to  1 .  7  with  a 
mean  of  1.41.    The  micropyle  is  distinct, 
3  to  5jj,  in  diameter.     The  micropylar  cap 
is  prominent,   5  to  lQ\i  wide  and  1  to  2.  5ji 
high  with  a  mean  of  7.  5  by  l.l \x;  it  is 
shaped  like  a  broad  truncated  cone  with  a 
flat  or  slightly  convex  top,  and  is  easily 
dislodged.    The  oocyst  wall  is  transparent, 
pale  brownish-yellow  to  yellowish-brown, 
and  composed  of  2  layers,  the  outer  one 
being  transparent,   pale  yellow  to  yellow- 
ish-green, and  half  as  thick  as  the  inner, 
heavier  layer.    The  oocyst  wall  is  lined 
by  a  membrane.     An  oocyst  polar  granule 
and  oocyst  residuum  are  absent.    The 
sporocysts  are  ovoid,  with  a  sporocyst 
residuum.    The  sporozoites  have  a  re- 
tractile globule  at  each  end.    The  sporula- 
tion  time  is  8  to  4  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


EIMERIA  GRANULOSA 
CHRISTENSEN,   1938 

Hosts:     Sheep,  Rocky  Mountain  big- 
horn sheep. 

Location:     Unknown.    Oocysts  found 
in  feces. 


EIMERIA  INTRICATA 
SPIEGL,   1925 

Hosts:     Sheep,   Rocky  Mountain  big- 
horn sheep,  moufflon,  roe  deer. 

Location:     Uncertain,  presumably 
abomasum  and  small  intestine. 


184 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  fairly 
common.     Christensen  (1938a)  found  it  in 
14%  of  100  sheep  from  Maryland,   New 
York  and  Wyoming.    Jacob  (1943)  found  it 
in  13%  of  100  sheep  in  Germany.     Balozet 
(1932)  found  it  in  3%  of  63  sheep  in  Tunisia. 
Svanbaev  (1957)  found  it  in  4%  of  302  sheep 
in  Kazakhstan. 


Morphology:     This  species  has  been 
described  by  Spiegl  (1925),  Balozet  (1932) 
and  Christensen  (1938a).    The  oocysts  are 
ellipsoidal,   39  to  54  by  27  to  36  (j.  with  a 
mean  of  47.0  by  32.0(:i  (Christensen)  or 
45.6  by  33.0/1  (Spiegl).     Their  length- 
width  ratio  is  1.  3  to  1.  8  with  a  mean  of 
1.47.    The  oocyst  wall,  as  described  by 
Henry  (1932),  is  composed  of  3  layers; 
the  outer  layer  is  a  transparent,  colorless 
membrane  which  is  very  difficult  to  see; 
the  middle  layer  is  thick,   rough,  brown, 
transversely  striated,   2.0  to  2.  5/i  thick, 
and  somewhat  thinner  at  the  micropylar 
end;  the  inner  layer  is  colorless,   0.8  to 
1.0 fi  thick.     The  micropyle  is  prominent, 
6  to  10 /I  in  diameter;  it  does  not  extend 
to  the  inner  layer.     The  micropylar  cap  is 
prominent,  transparent,  colorless  to 
yellowish-green,  crescent-shaped,  de- 
tachable, and  6  to  11  ji  wide  and  1  to  3j:i 
high  with  a  mean  of  9  by  2  jm  .  An  oocyst 
polar  granule  and  residuum  are  absent. 
The  sporocysts  are  elongate  ovoid,  17  to 
18  by  9  to  13  fi,  with  a  small  Stieda  body 
and  a  sporocyst  residuum.    The  sporo- 
zoites  are  wedge-shaped,  with  several 
refractile  globules.    The  sporulation  time 
is  3  to  5  days. 

Life  Cycle:     The  life  cycle  of  E. 
inlricala  has  not  been  worked  out.    As 
mentioned  above,   Reichenow  (1940)  and 
Becker  (1956)  considered  that  the  giant 
schizonts  described  from  sheep  under  the 
name  E.  gilruthi  are  those  oiE.  inlricala. 
According  to  Kotlan,   Pell^rdy  and  Versenyi 
(1951),  the  merozoites  of  E.  inlricala  are 
about  16/i  long  and  bent  like  a  hoe  at  one 
end. 

Pathogenesis:     Unknown.    These 
oocysts  are  rarely  found  in  large  numbers. 


Epidemiology:     Honess  (1952)  found 
this  species  in  the  Rocky  Mountain  bighorn 
sheep,  and  Wetzel  and  Enigk  (1936)  re- 
ported it  from  the  roe  deer  in  Germany. 


EIMERIA  NINAKOHLYAKIMOVAE 
YAKIMOFF  AND  RASTEGAIEFF, 
1930  emend. 

Synonyms:     Eimeria galouzoi  (pro 
parte),  E.  nina-kohl-yakimovi  Yakimoff 
and  Rastegaieff,  1930. 

Hosts:     Sheep,  goat.  Rocky  Mountain 
bighorn  sheep,  mouflon  [Ovis  nmsinion), 
0.  orientalis,    Siberian  ibex  (Capra  ibex 
sibirica),   Barbary  sheep  {Animotragus 
lervia),   Persian  gazelle  {Gazella  subgnt- 
turosa). 

Location:     Small  intestine,  especially 
the  posterior  part,and  also  cecum  and  colon. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  fairly 
common.     Christensen  (1938a)  found  it  in 
3%  of  100  sheep  from  Maryland  and  Idaho. 
Jacob  (1943)  found  it  in  5%  of  100  sheep  in 
Germany.     Balozet  (1932)  found  it  in  35% 
of  63  sheep  and  34%  of  41  goats  in  Tunisia. 
Svanbaev  (1957)  found  it  in  52%  of  302  sheep 
and  31%  of  48  goats  in  Kazakhstan. 

Morphology:     This  species  has  been 
described  by  Yakimoff  and  Rastegaieff 
(1930),   Balozet  (1932)  and  Christensen 
(1938a).     The  oocysts  are  usually  ellip- 
soidal, sometimes  spherical,  occasionally 
slightly  ovoid.    They  are  16  to  27  by  13  to 
22 /i  with  means  of  23.  1  by  18.  3  ^t  (Chris- 
tensen) or  19.  8  by  16.  5fj,  (Balozet).     Their 
length-width  ratio  is  1. 1  to  1.  5  with  a  mean 
of  1.27  according  to  Christensen  (1938). 
The  oocyst  wall  is  1  to  1.  5  |i  thick,  trans- 
parent, almost  colorless  to  pale  brownish 
yellow,  and  composed  of  two  layers  of 
which  the  outer  is  half  as  thick  as  the  inner. 
A  micropyle  is  absent  or  imperceptible 
(occasionally  visible  under  bright  light  if 
the  oocyst  is  tilted,  according  to  Christen- 
sen).   There  is  no  micropylar  cap.    An 
oocyst  polar  granule  and  oocyst  residuum 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


185 


are  absent.     The  sporocysts  are  ovoid,  4 
to  11  by  4  to  6  |u .    A  sporocyst  residuum 
is  present.     The  sporozoites  have  one  end 
slender  and  pointed  and  the  other  thick  and 
rounded;  they  measure  4  to  5  by  2 /j,  and 
lie  lengthwise,  head  to  tail,  in  the  sporo- 
cysts.    The  sporulation  time  is  1  to  2  days 
according  to  Christensen  (1938a)  or  3  to  4 
days  according  to  Balozet  (1932). 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  described  by  Balozet 
(1932)  in  the  goat  and  briefly  by  Lotze 
(1954)  in  the  sheep.     Their  accounts  differ, 
and  are  given  separately  below. 

Lotze  (1954)  found  in  sheep  that  the 
sporozoites  enter  the  epithelial  cells  ati 
the  base  of  the  glands  of  Lieberkuehn  in 
the  small  intestine,  where  they  form 
schizonts  about  300  jj,  in  diameter  contain- 
ing thousands  of  merozoites.     The  sexual 
stages  occur  in  the  epithelial  cells  of  the 
ileum,  cecum  and  upper  part  of  the  large 
intestine,  appearing  15  days  or  more 
after  infection. 

Balozet  (1932a)  found  in  a  kid  killed 
39  days  after  infection  that  the  schizonts 
were  only  15  to  35 /j,  in  diameter  and  con- 
tained only  40  to  200  merozoites.     How- 
ever, these  schizonts  were  found  very 
late  in  the  infection.     They  were  asso- 
ciated with  macrogametes  and  microga- 
metocytes,   and  it  is  possible  either  that 
they  may  have  belonged  to  a  second  gen- 
eration not  mentioned  by  Lotze  or  that 
they  may  have  belonged  to  some  other 
species. 

The  prepatent  period  was  found  by 
Shumard  (1957)  to  be  15  days  in  lambs 
and  by  Balozet  (1932)  to  be  10  to  13  days. 

Pathogenesis:     This  is  one  of  the 
most  pathogenic  species  of  coccidium  in 
sheep.     Lotze  (1954)  found  that  as  few  as 
50,000  oocysts  caused  diarrhea  in  a  3- 
month-old  lamb,  and  as  few  as  500,  000 
oocysts  caused  death.    Dysentery  was  pro- 
duced in  a  2-year-old  sheep  by  inoculation 
with  as  few  as  1  million  oocysts. 

Lotze  (1954)  found  that  in  lambs  the 
feces  became  soft  in  12  to  17  days  after 


experimental  infection.     They  became 
watery  a  day  or  2  later  and  remained  so 
for  a  week  or  more.    In  the  more  heavily 
infected  lambs,  the  feces  contained  blood- 
stained mucus  beginning  the  15th  day  after 
infection  or  soon  thereafter.    In  those  ani- 
mals which  recovered,  the  feces  remained 
soft  for  some  weeks. 

The  lambs  with  severe  diarrhea  lost 
their  appetites  at  first,  altho  they  appeared 
to  drink  more.    After  about  a  week  they 
drank  very  little.     There  was  rapid  loss  of 
weight  at  the  onset  of  diarrhea.    If  the 
lambs  recovered,  they  gained  weight  about 
as  rapidly  as  the  controls,  but  of  course 
had  taken  a  setback  in  growth.    About  2 
months  after  severe  coccidiosis,  the  wool 
began  to  break  off  over  extensive  areas, 
starting  on  the  flanks;  this  may  have  been 
due  to  nutritional  disturbance  caused  by 
the  infection. 

The  diarrheic  feces  attracted  flies, 
and  affected  animals  quickly  became  fly- 
struck.    Some  animals  which  would  other- 
wise have  recovered  died  of  flystrike  if 
they  were  not  treated  for  this  condition. 

At  necropsy,   petechial  hemorrhages 
were  found  in  the  small  intestine  3  to  7 
days  after  infection.     The  small  intestine 
then  became  thickened  and  inflamed.     Ex- 
tensive hemorrhage  was  present  in  the 
posterior  part  of  the  small  intestine  of 
severely  affected  lambs  by  the  15th  day. 
The  cecum  and  upper  part  of  the  large  in- 
testine became  thickened  and  edematous, 
and  were  hemorrhagic  by  the  19th  day. 
In  heavily  infected  lambs,  vast  areas  of 
the  posterior  part  of  the  small  intestine 
were  denuded  of  epithelium.     Thus,  one 
can  say  that  the  lesions  consisted  at  first 
of  petechial  hemorrhages,  followed  by 
thickening,  edema  and  inflammation,  and 
finally  by  epithelial  denudation.     The  small 
intestine,  especially  its  posterior  part, 
cecum  and  upper  colon  were  affected. 

Shumard  (1957a)  studied  a  somewhat 
less  pathogenic  strain.     He  reported 
lowered  feed  consumption,  lassitude,   gen- 
eralized incoordination  and  slight  diarrhea 
with  some  bleeding  in  lambs  experimentally 
infected  at  50  days  of  age  with  7  million 


IRfi 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


oocysts  of  E.  ninakohlyakimovae  and 
100,  000  oocysts  of  E.  faiirei.     There  was 
no  decrease  in  water  consumption.     Clin- 
ical signs  appeared  on  the  9th  day  after 
infection  and  ended  about  the  22nd  day. 
One  out  of  the  4  lambs  died  on  the  15th 
day.     There  were  decreases  in  percentage 
of  feed  protein  digested  and  inorganic 
serum  phosphorus,   increases  in  serum 
globulins  and  blood  glucose,   and  no  sig- 
nificant changes  in  total  serum  protein, 
blood  hemoglobin  and  hematocrit  values. 
Oocysts  of  both  species  appeared  in  the 
feces  on  the  15th  day,   increased  until  the 
21st  day  and  then  decreased  gradually. 

Balozet  (1932)  observed  a  case  of 
muco-sanguineous  diarrhea  followed  by 
death  in  a  naturally  affected  adult  goat, 
and  produced  the  disease  experimentally 
in  2  newborn  kids.    A  mucous  diarrhea 
appeared  on  the  22nd  day  after  infection, 
became  bloody,  and  persisted  until  about 
the  39th  day. 

Remarks:     In  one  of  the  very  few 
cross-transmission  experiments  attempted 
with  sheep  and  goat  coccidia,   Balozet 
(1932)  was  unable  to  infect  a  recently 
weaned  lamb  with  E.  numkohlyakimovae 
from  a  goat,  altho  he  did  infect  2  newborn 
kids.     He  thought  the  lamb  was  too  old. 


EIMERIA  PALLIDA 
CHRISTENSEN,   1938 


tible  and  there  is  no  micropylar  cap.    The 
oocyst  wall  is  thin,  homogeneous,  color- 
less to  pale  yellow  to  yellowish  green, 
appears  fragile  and  pallid,  and  is  com- 
posed of  2  layers  of  which  the  outer  is 
half  as  thick  as  the  inner,  with  a  single 
dark  refraction  line  marking  its  inner  edge. 
An  oocyst  polar  granule  and  oocyst  resi- 
duum are  absent.    The  sporocysts  are 
ovoid,  without  a  sporocyst  residuum.     The 
sporozoites  lie  lengthwise,  head  to  tail, 
in  the  sporocysts,  and  contain  a  spherical 
globule  at  each  end.     The  sporulation  time 
is  1  day. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     In  describing  E.  pallida, 
Christensen  (1938a)  said  that  it  differed 
from  E.  parva  is  being  narrower,  pale, 
inconspicuous  and  colorless,  and  in  having 
only  a  single  black  refraction  line  on  the 
inner  surface  of  the  oocyst  wall  instead  of 
2  black  refraction  lines,  one  on  each  side 
of  the  inner  wall.     However,  Kotlan,   Pel- 
lerdy  and  Versenyi  (1951)  considered  E. 
pallida  a  synonym  of  E.  parva. 


EIMERIA   PARVA 

KOTLAN,   MOCSY  AND  VAJDA,   1929 

Synonyms:     Ei»ieria  galouzoi  {pro 
parte). 


Host:     Sheep. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     North 
America. 

Prevalence:  Christensen  (1938a) 
found  this  species  in  10%  of  100  sheep 
from  Maryland  and  Wyoming. 

Morphology:     This  species  has  been 
described  by  Christensen  (1938a).     The 
oocysts  are  ellipsoidal,  12  to  20  by  8  to 
15^  with  a  mean  of  14.  2  by  10,  O^L .    Their 
length-width  ratio  is  1 .  2  to  1 .  7  with  a 
mean  of  1.  43.    A  micropyle  is  impercep- 


Hosts:     Sheep,  goat.  Rocky  Mountain 
bighorn  sheep,  Barbary  sheep  {Ammotra- 
gus  lervia),  Siberian  ibex  {Capya  ibex 
sibirica),  roe  deer. 

Location:     Schizonts  are  found  thru- 
out  the  small  intestine,  and  gametes  and 
gametocytes  in  the  cecum,  colon  and  small 
intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  common 
in  sheep,  less  common  in  goats.    Chris- 
tensen (1938a)  found  it  in  50%  of  100  sheep 
from  Idaho,  Maryland  and  Wyoming.    Jacob 
(1943)  found  it  in  52%  of  100  sheep  and  9% 
of  11  goats  in  Germany;  he  also  found  it  in 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


187 


a  roe  deer.  Balozet  (1932)  found  it  in  21% 
of  63  sheep  and  22%  of  41  goats  in  Tunisia. 
Svanbaev  (1957)  found  it  in  9%  of  302  sheep 
in  Kazakhstan. 

Morphology:     This  species  has  been 
described  by  Kotlan,  Mocsy  and  Vajda 
(1929),   Balozet  (1932)  and  Christensen 
(1938a).     The  oocysts  are  subspherical, 
ellipsoidal  or  spherical,   12  to  22  by  10  to 
18/i  with  a  mean  of  16.  5  by  14. 1  jj,  (Chris- 
tensen) or  17.  2  by  13.  5|u  (Balozet). 
Their  length  width  ratio  is  1.  0  to  1.5  with 
a  mean  of  1.18  (Christensen).    The  oocyst 
wall  is  smooth,  homogeneous,  pale  yellow 
to  yellowish  green,  and  composed  of  2 
layers  of  which  the  outer  is  half  as  thick 
as  the  inner;  there  is  a  heavy,  black  re- 
fraction line  on  each  side  of  the  inner 
layer,  according  to  Christensen.    Accord- 
ing to  Balozet,  the  wall  appears  to  be 
lined  by  a  membrane.     The  sporont  is 
clear.     A  micropyle  is  absent;  according 
to  Christensen,  the  oocyst  wall  occasion- 
ally appears  slightly  paler  at  one  end  than 
the  other.    An  oocyst  polar  granule  and 
oocyst  residuum  are  absent.     The  sporo- 
cysts  are  oval.    The  sporocyst  residuum 
is  indistinct  if  present  at  all.    The  spor- 
ulation  time  is  1  to  2  days  (Christensen) 
or  7  to  8  days  (Balozet). 

Life  Cycle:     The  life  cycle  of  E. 
parva  in  sheep  has  been  described  by 
Kotlan,  Pelle'rdy  and  Versenyi  (1951). 
The  schizonts  are  found  thruout  the  small 
intestine.    They  measure  up  to  185  to  256 
by  128  to  179^1  and  are  easily  visible  to 
the  naked  eye  as  whitish  bodies.    They 
lie  in  the  mucosa,  usually  near  the  sur- 
face but  sometimes  as  far  down  as  the 
muscularis  mucosae.    They  invade  endo- 
thelial cells  and  enlarge  both  the  host  cell 
and  its  nucleus  enormously.    They  are 
surrounded  by  a  rather  thick  layer  of 
connective  tissue  which  becomes  thinner 
as  they  increase  in  size.    Each  schizont 
produced  thousands  of  straight  merozoites 
10  to  12^1  long. 

Kotlan,   Pellerdy  and  Versenyi  (1951) 
also  found  a  second,  much  smaller  type  of 
schizont  in  the  small  intestine.    It  occurred 
in  the  superficial  epithelial  cells,  was 
10  to  12  fi  in  diameter  and  contained  about 


10  to  20  merozoites  2.  5  to  3 /i  long.     They 
were  not  sure,  however,  whether  it  was 
part  of  the  life  cycle  of  E.  parva. 

The  sexual  stages  occur  mostly  in  the 
cecum  and  colon  and  to  a  lesser  extent  in 
the  small  intestine.     They  are  found  in  the 
epithelial  cells  and  measure  15  to  19  by  10 
to  16  p.. 

Pathogenesis:     This  species  is  appar- 
ently not  very  pathogenic.     Most  of  the 
damage  is  caused  by  the  sexual  stages  in 
the  large  and  small  intestines.    In  a  lamb 
killed  by  Kotlan,   Pelle'rdy  and  Versenyi 
(1951)  16  days  after  experimental  infection, 
the  contents  of  the  cecum  and  colon  were 
semifluid,  dark  and  mixed  with  blood  in 
places.     The  wall  was  thickened  and  its 
surface  uneven  and  denuded  of  epithelium 
in  places.     By  histologic  examination  of  the 
cecum,  it  was  found  that  the  mucosa  had 
been  stripped  from  the  glandular  layer  in 
places  and  the  tissue  had  become  necrotic 
and  infiltrated  with  lymphocytes  and  neu- 
trophiles  but  no  eosinophiles.    Sharply 
separated  from  these  necrotic  areas  were 
other  areas  in  which  most  of  the  epithelial 
cells  contained  microgametocytes,  macro- 
gametes  or  young  oocysts. 


EIMERIA  PUNCTATA 
LANDERS,   1955 


Synonym:     Eimeria  honessi  Landers, 


1952. 

Host:     Sheep. 

Location:     Unknown.     Oocysts  found 
in  feces. 


Geographic  Distribution: 
America  (Wyoming). 


North 


Prevalence:     Landers  (1952) found 
this  species  in  2  of  9  sheep  in  Wyoming. 

Morphology:     This  species  has  been 
described  by  Landers  (1952).    The  oocysts 
are  subspherical,  18  to  25  by  16  to  21  fi. 
with  a  mean  of  21.2  by  17.7  j^.    Their 
length-width  ratio  is  1. 1  to  1.  3  with  a 
mean  of  1.  20.    The  oocyst  wall  has 


188 


THE  TELOSPORASIDA  AND  THE  COCCIDIA  PROPER 


conspicuous,  uniform,  cone-shaped  pits 
about  0.  5/jL  in  diameter.    It  is  1.  2  to  1.  Sfi 
thick  (mean,  1.5fi);  its  outer  layer  is 
colorless  to  yellowish,  and  its  inner  layer 
greenish,  with  two  dark  refraction  lines, 
one  at  either  surface.    There  is  a  conspic- 
uous micropyle.    A  micropylar  cap  is 
present,  sometimes  imperceptible,  up  to 
6.  5(i  wide  and  1.6^  high  with  a  mean  of 
4. 1  by  0.  8  )i .    An  oocyst  residuum  and 


oocyst  polar  granule  are  absent.    The 
sporocysts  are  spherical  to  ellipsoidal, 
and  average  8. 1  |j.  in  diameter  or  10.  4  by 
6.  9  (1 .    The  presence  or  absence  of  a 
sporocyst  residuum  was  not  mentioned. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


Fig.  26.      Coccidia  of  sheep.     A.   Eimeria  pallula  unspornl^tedoocysU    ^'JJ'^^^J'!^ 
^  sporulated  oocyst.     C.   E.  parva  unsporulated  oocyst      D.   E.  mnakohlyakn 

o.aeunsporulated  oocyst.  E.  E.  '"''"■«'"  ""fP^^^l^^'^'^o^^'y^'v  ^^,„^;,/;;; 
porulated  oocyst.  G.  E.  arloinni  unsporulated  oocyst.  H  £^  ^~°"' 
Dorulated  oocyst.    I.    £.  A'>-«««/osa  sporulated  oocyst.    X  1270.     (From 


E.  faiirei 


uns 

unsporulated  oocyst 

Christensen,   1938) 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


189 


COCCIDiOSIS    IN    SHEEP    AND    GOATS 

Coccidiosis  in  sheep  is  primarily  a 
disease  of  feedlot  lambs.    It  has  been 
studied  by  Newsom  and  Cross  (1931), 
Deem  and  Thorp  (1939,   1940)  and  Chris- 
tensen  (1940)  among  others.    It  appears 
12  days  to  3  weeks  after  the  lambs  arrive 
in  the  feedlot.    Diarrhea,  depression  and 
inappetance  appear,  followed  by  weakness 
and  loss  of  weight.     The  diarrhea  continues 
for  several  days  up  to  about  2  weeks,  and 
some  lambs  may  die  during  this  period. 
Most,   however,   recover.     The  mortality 
varies,  but  is  seldom  more  than  10%.    In 
a  group  of  16,  000  New  Mexico  feeder 
lambs  studied  by  Christensen  (1940)  on  a 
Nebraska  feedlot,  the  mortality  was  3.4%, 
but  another  9.  8%  of  scouring,  emaciated 
lambs  were  removed  to  a  hospital  lot  for 
special  diet  and  care. 

Even  if  there  are  no  deaths,  there 
may  be  loss  of  weight  or  reduced  weight 
gains.     Thus,  Shumard  (1957)  found  that 
80  lambs  experimentally  infected  with  a 
sublethal  mixture  of  coccidian  oocysts 
(mostly  E.  nlnakohlyakimovae  and£. 
arloingi)  lost  an  average  of  0.205  pounds 
per  pound  of  feed  consumed  during  the  24 
days  following  infection,  as  compared 
with  an  average  gain  of  0.  062  pounds  per 
pound  of  feed  consumed  for  40  control, 
uninfected  lambs. 

When  lambs  are  brought  into  the  feed- 
lot,  they  are  usually  shedding  small  num- 
bers of  coccidian  oocysts.    As  the  result 
of  crowding,  and  under  conditions  which 
promote  fecal  contamination  of  the  feed, 
the  coccidial  infections  build  up.    The 
number  of  oocysts  in  the  feces  rises  for 
about  a  month,   remains  stationary  for  1 
to  3  weeks  and  then  decreases  rather 
rapidly,  only  a  few  oocysts  being  present 
at  the  end  of  the  feeding  period.    Whether 
or  not  disease  will  appear  depends  upon 
the  number  and  species  of  oocysts  which 
the  lambs  ingest  during  the  crucial  first 
week  or  two.    By  the  end  of  the  first 
month,  there  is  little  danger  of  coccidio- 
sis.   The  lambs  have  been  infected,  but 
the  exposing  dose  of  oocysts  has  been 
small  enough  to  permit  immunity  to  de- 
velop.   In  other  words,  there  has  been 
coccidiasis  but  no  coccidiosis. 


Feeding  of  chopped  feed  in  open  troughs 
low  enough  to  be  contaminated  with  feces 
promotes  coccidiosis.     Christensen  (1941a) 
found  that  corn  silage  provided  an  amount 
of  moisture  which  favored  oocyst  sporula- 
tion,  while  chopped  alfalfa,  grain  and  mo- 
lasses also  permitted  sporulation. 

Dunlap,  Hawkins  and  Nelson  (1949) 
followed  oocyst  production  from  the  time 
of  birth  in  lambs  running  with  their  mothers. 
The  ewes  were  the  source  of  infection,  and 
lambs  became  infected  by  ingesting  sporu- 
lated  oocysts  from  the  bedding.     The  first 
oocysts  appeared  when  the  lambs  were  5  to 
8  weeks  old;  they  built  up  to  a  peak  which 
lasted  1  to  4  weeks,  and  then  declined. 

Temperature  affects  oocyst  sporula- 
tion.   Dunlap,   Hawkins  and  Nelson  (1949) 
found  the  first  sporulated  oocysts  in  the 
bedding  when  the  mean  temperature  was 
49°  F.     Christensen  (1939)  found  that  the 
optimum  sporulation  temperature  for  the 
oocysts  of  E.  arloingi  was  20-25°  C,  the 
sporulation  time  being  2  to  3  days  at  that 
temperature  in  a  thin  layer  of  water  or  in 
fecal  pellets.    The  oocysts  survived  less 
than  4  months  in  fecal  sediment  at  this 
temperature.    Sporulation  was  slow  at  0 
to  5°  C,  altho  oocysts  remained  alive  for 
at  least  10  months  in  fecal  sediment  or 
moist  pellets.    No  sporulation  took  place 
at  40°  C  and  the  oocysts  were  killed  within 
4  days.    If  the  fecal  sediment  was  allowed 
to  putrefy,  however,  no  sporulation  took 
place  at  any  temperature. 

Landers  (1953)  found  that  the  oocysts 
of  E.  arloi)igi,  E.  ninakohlyakiniovae  and 
E.  parva  did  not  survive  24  hours  in  sheep 
pellets  when  frozen  directly  to  -30°  C,  and 
survived  less  than  2  days  when  conditioned 
at  -19°  C  prior  to  freezing  to  -30°.    They 
survived  without  essential  mortality  when 
frozen  directly  to  -25°  C  for  7  days,  but 
only  about  half  of  the  first  two  species  and 
one  quarter  of  E.  parva  survived  14  days. 
Repeated  freezing  and  thawing  at  -19  or 
-25°  C  up  to  6  or  7  times  had  no  significant 
effect  on  survival.     Landers  said  that  in  an 
average  winter  at  Laramie,  Wyoming  the 
minimum  soil  surface  temperature  would 
probably  be  between  -15  and  -20°  C  and 
that  unsporulated  oocysts  would  not  nor- 
mally be  killed  by  such  temperatures. 


190 


THE  TELOSPORASIDA  AND  THE  COCCIDIA  PROPER 


Diagnosis:     Coccidiosis  in  sheep  and 
goats  can  be  diagnosed  from  a  combination 
of  history,  signs,  gross  lesions  at  necropsy 
and  microscopic  examination  of  the  intes- 
tinal mucosa  and  feces.     However,   recog- 
nition of  coccidia  in  the  lesions  at  necropsy 
is  necessary  for  positive  diagnosis.    The 
mere  presence  of  oocysts  in  the  feces  does 
not  necessarily  mean  that  the  disease  is 
due  to  coccidia.    On  the  other  hand,  acute 
coccidiosis  may  be  present  before  any 
oocysts  appear. 

Treatment:     Relatively  few  studies 
have  been  carried  out  on  the  treatment  of 
coccidiosis  in  sheep.     A  distinction  must 
be  made  between  preventive  and  curative 
treatments.    Several  sulfonamides  and 
sulfur  are  of  value  in  preventing  coccidio- 
sis in  lambs,  but  no  drugs  are  known  to 
cure  the  disease  once  signs  appear.     How- 
ever, oxytetracycline  and  related  anti- 
biotics may  be  of  value  in  controlling  sec- 
ondary infections. 


Christensen  (1944)  found  that  0.  5  to 
1.  5%  sulfur  fed  in  a  ration  of  chopped  al- 
falfa and  ground  corn  held  together  by 
molasses  and  water  prevented  coccidiosis 
in  feeder  lambs.     He  fed  this  amount  of 
sulfur  for  72  days  without  ill  effects,  but 
higher  concentrations  caused  diarrhea  and 
decreased  weight  gains. 

Tarlatzis,  Panetsis  and  Dragonas 
(1955)  claimed  that  furacin  was  effective 
against  coccidiosis  in  sheep  and  goats, 
but  their  work  was  uncontrolled. 

Prevention:     Good  sanitation  will 
largely  prevent  coccidiosis  in  lambs. 
Coccidiosis  is  not  a  problem  in  suckling 
lambs  on  the  western  range,  but  appears 
when  the  animals  are  brought  together  in 
the  feedlot.     Feedlots  should  be  kept  dry 
and  clean.    Clean  water  and  feed  should  be 
supplied,  and  feed  troughs  should  be  so 
constructed  that  they  cannot  be  contamin- 
ated with  feces. 


Foster,  Christensen  and  Habermann 
(1941)  found  that  2  g  sulfaguanidine  a  day 
prevented  the  acquisition  of  natural  coc- 
cidiosis in  5  lambs  and  reduced  the  level 
of  oocyst  output  in  4  subclinical  infections 
with  unnamed  species.     Christensen  and 
Foster  (1943)  reported  that  0.2%  sulfa- 
guanidine in  the  feed  for  20  days  beginning 
1  day  after  an  infective  feeding  with  500,000 
sporulated  oocysts  from  lambs  with  clin- 
ical coccidiosis  prevented  severe  coccid- 
iosis in  lambs,  but  that  0.45%  sulfaguanidine 
failed  to  affect  the  course  of  the  disease 
when  it  was  begun  the  day  after  clinical 
signs  had  appeared.    Steward  (1952)  found 
that  sulfamethazine  and  sulfadiazine  had 
some  value  in  an  outbreak  of  coccidiosis 
in  sheep,   reducing  the  numbers  of  oocysts 
passed,  but  that  quinacrine  was  valueless. 
Whitten  (1953)  found  in  a  controlled  exper- 
iment that  neither  0.01  g  per  kg  quinacrine 
hydrochloride  nor  0.01  g  per  kg  sulfameth- 
azine daily  for  3  days  had  any  significant 
effect  on  oocyst  production  or  weight  gains 
in  naturally  affected  lambs.     However, 
oocyst  production  decreased  markedly 
markedly  in  both  ireated  lambs  and  controls 
following  treatment,  so  that  if  no  controls 
had  been  used,  it  would  have  been  assumed 
that  the  treatment  had  been  of  value. 


Coccidiosis  is  a  potential  hazard  if 
lambing  takes  place  in  a  barn  or  restricted 
area,  and  the  bedding  is  the  most  common 
source  of  infection.    Shumard  and  Eveleth 
(1956)  recommended  as  a  practical  method 
for  raising  lambs  with  their  ewes  that  the 
animals  be  kept  in  concrete  pens  with 
straw  bedding,  that  the  pens  be  cleaned 
twice  a  week,  and  that  1  pint  of  a  3.  45% 
sulfaquinoxaline  solution  be  added  to  each 
50  gallons  of  drinking  water.     In  their 
studies,  coccidian  oocysts  did  not  appear 
in  the  lambs  until  18  days  after  treatment 
had  been  discontinued. 


EIMERIA  DEBLIECKI 
DOUWES,   1921 

Synonyms:      Eimeria  bri(»if>ti,  Eimeria 
jaliiia,  Eimeria  suis. 

Host:      Pig. 

Location:     Small  intestine,  and,  to  a 
lesser  extent,   large  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     E.  debUecki  is  the  com- 
monest coccidium  of  swine.    De  Graff 
(1925)  found  it  in  51%  of  500  pigs  in  the 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


191 


Netherlands.     Yakimoff  e/ flZ.   (1936)  found 
it  in  92%  of  141  pigs  in  Russia.     Yakimoff 
(1936)  found  it  in  27%  of  53  pigs  from 
Brazil.     Novicky  (1945)  found  it  in  27%  of 
62  pigs  in  Venezuela.     Nieschulz  and 
Ponto  (1927)  found  it  in  all  of  about  50 
pigs  in  Java. 

Morphology:     The  oocysts  are  ovoid 
to  ellipsoidal  or  subspherical,   13  to  29  by 

13  to  19/1.     The  oocyst  wall  is  1.0  to 
1.5ii  thick,  smooth,  colorless  to  brown- 
ish, and  composed  of  2  layers.    A  micro- 
pyle  is  absent.    An  oocyst  polar  granule 
is  absent  (present  according  to  Paichuk, 
1953).     An  oocyst  residuum  is  absent. 
The  sporocysts  are  ellipsoidal  or  ovoid, 

14  to  18  by  6  to  8|:x  with  a  Stieda  body.    A 
sporocyst  residuum  is  present. 

The  sporulation  time  is  6  to  9  days. 
The  sporulation  process  has  been  des- 
cribed in  detail  by  de  Graaf  (1925). 


that  pigs  experimentally  infected  with  20 
to  30  million  mixed  sporulated  oocysts  of 
E.  debliecki  and  E.  scabra  developed  a 
profuse  diarrhea  lasting  2  to  15  days, 
inappetance  and  did  not  gain  weight. 
Swanson  and  Kates  (1940)  described  an 
outbreak  of  coccidiosis  in  a  litter  of  4.  5 
month  old  pigs  in  Georgia.     The  pigs  had 
a  profuse  diarrhea  and  gained  weight 
poorly  despite  ravenous  appetites,  excel- 
lent rations  and  good  care.     Novicky  (1945) 
described  several  outbreaks  of  swine  coc- 
cidiosis in  Venezuela.    The  mortality  was 
relatively  low,  but  the  young  animals 
which  survived  were  retarded. 

Immunity:     Biester  and  Schwarte 
(1932)  produced  complete  immunity  in  pigs 
by  feeding  them  oocysts  daily  for  100  days 
or  more.     Light  infections  produced  partial 
immunity.    As  with  other  coccidia,  adult 
pigs  are  often  carriers,   shedding  a  few 
oocysts  in  their  feces. 


Life  Cycle:     De  Graaf  (1925)  and 
others  have  described  the  endogenous 
stages  of  this  species.    The  schizonts 
produce  14  to  16  banana-shaped  mero- 
zoites.     These  are  8  to  10  |i  long  and  3  to 
4.  5ju  wide;  one  end  is  rounded  and  the 
other  pointed.     The  nucleus  is  usually  in 
the  middle  of  the  merozoites.     The  micro- 
gametocytes  are  7  to  22|U  in  diameter 
when  mature.     The  microgametes  are 
3.  5jLt  long  and  0.  6;i  wide  and  have  2  fla- 
gella.    The  macrogametes  are  similar  to 
those  of  other  Eimeria  species. 


Remarks:    Brug  (1946)  found  E.  deb- 
liecki as  a  pseudoparasite  of  man  in  Hol- 
land.    Four  out  of  13  persons  in  a  psychi- 
atric ward  passed  oocysts  in  their  feces 
on  one  day.    They  had  probably  been  in- 
gested with  liver  sausage,  the  casing  of 
which  was  made  from  pig  intestines. 


EIMERIA  PERMINUTA 
HENRY,   1931 


Host:      Pig. 


Biester  and  Schwarte  (1932)  found  that 
the  prepatent  period  in  experimentally  in- 
fected pigs  was  about  7  days  and  that 
oocysts  were  present  in  the  feces  for  10 
to  15  days  in  the  absence  of  reinfection. 

Pathogenesis:      E.  debliecki  is  only 
slightly  pathogenic  if  at  all  in  adult  ani- 
mals, but  it  may  cause  diarrhea  and  even 
death  in  young  pigs.     Biester  and  Murray 
(1929)  found  that  young  pigs  fed  large  num- 
bers of  sporulated  oocysts  developed 
severe  diarrhea.     They  became  emaciated 
and  some  even  died.    Some  had  constipa- 
tion, but  dysentery  was  never  observed. 
The  pigs  which  recovered  usually  failed  to 
do  wen.    Alicata  and  Willett  (1946)  found 


Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     Worldwide. 

t*      Prevalence:     Yakimoff  et  al.  (1936) 
found  this  species  in  18%  of  141  pigs  in 
Russia.    Yakimoff  (1936)  found  it  in  45% 
of  53  pigs  in  Brazil. 

Morphology:     This  species  was  first 
described  by  Henry  (1931)  from  pigs  in 
California.     The  oocysts  are  ellipsoidal 
to  spherical,   11  to  16  by  10  to  13jj,.     The 
oocyst  wall  is  rough,  yellowish,  and  ap- 
parently composed  of  a  single  layer.    A 
micropyle  is  absent.    An  oocyst  polar 


192 


THE  TELOSPORASIDA  AND  THE  CCXTCIDIA  PROPER 


granule  is  present.  No  other  morphologi- 
cal information  is  known.  The  sporulation 
time  is  11  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

EIMERIA  POLITA 
PELLERDY,   1949 

Host:      Pig. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     Europe 
(Hungary),  North  America  (Alabama). 

Prevalence:     Unknown. 

Morphology:     This  species  has  been 
described  by  Pelle'rdy  (1949)  in  Hungary 
and  by  Lesser  and  Davis  (1958)  in  Alabama. 
The  oocysts  are  ellipsoidal,   rarely  broadly 
ovoid,   17  to  36  by  13  to  24  (J,  with  a  mean  of 
23.  8  by  17.  9  |Lt .    The  oocyst  wall  is  smooth 
or  occasionally  roughened,  yellowish 
brown  or  pinkish  brown,   1.0  to  1.5 /j,  thick. 
The  micropyle  is  imperceptible  or  is  seen 
only  when  the  oocyst  lies  in  a  favorable 
position.     A  polar  granule  is  present  in 
about  half  the  oocysts.     There  is  no  oocyst 
residuum.     The  sporocysts  are  ellipsoidal, 
15tol9by6/i.    A  sporocyst  residuum  is 
present.    The  sporulation  time  is  8  to  9  days. 

Life  Cycle:     Unknown.     Pellerdy  (1949) 
found  that  the  prepatent  period  in  3  exper- 
imentally infected  pigs  was  8  to  9  days. 

Pathogenesis:     Unknown. 

EIMERIA  SCABRA 
HENRY,   1931 

Host:     Domestic  and  wild  pigs. 

Location:     Intestine.     The  sexual 
stages  are  found  in  the  epithelial  cells  of 
the  villi. 

Geographic  Distribution:     Worldwide. 


Prevalence:     Yakimoff  et  al.  (1936) 
found  this  species  in  33%  of  141  pigs  in 
Russia. 

Morphology:     The  oocysts  are  ovoid 
to  ellipsoidal,   22  to  36  by  16  to  28  ^ .     The 
oocyst  wall  is  brown,   rough,  and  1.  5  to 
2.0ji  thick,  becoming  thinner  at  the  nar- 
row end.    A  micropyle  is  present  accord- 
ing to  Pelle'rdy  (1949),  but  was  not  men- 
tioned by  Henry  (1931).     An  oocyst  polar 
granule  is  present.     There  is  no  oocyst 
residuum.     The  sporocysts  are  ellipsoidal, 
15  to  19  by  6 jM,  and  have  a  sporocyst  res- 
iduum.    The  sporulation  time  is  9  to  12 
days. 

Life  Cycle:     The  endogenous  stages 
of  this  species  have  not  been  described. 
Pelle'rdy  (1949)  found  that  the  prepatent 
period  in  2  experimentally  infected  pigs 
was  9  days. 

Pathogenesis:     Uncertain.     Alicata 
and  Willett  (1946)  found  that  pigs  experi- 
mentally infected  with  20  to  30  million 
mixed  sporulated  oocysts  of  E.  debliecki 
and  E.  scabra  developed  a  profuse  diar- 
rhea lasting  2  to  15  days,   lost  their  appe- 
tites and  did  not  gain  weight.     How  much 
of  this  effect  was  due  to  E.  scabra  is  not 
known. 


EIMERIA  SCROFAE 
GALLI-VALERIO,   1935 

Host:     Domestic  pig. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     Europe 
(Switzerland). 

Prevalence:     Unknown. 

Morphology:     This  species  has  been 
described  only  by  Galli-Valerio  (1935). 
The  oocysts  are  cylindroid,  with  one  end 
slightly  flattened,  and  measure  24  by  15fi. 
There  is  a  distinct  micropyle.     Oocyst  and 
sporocyst  residua  are  absent.    The  sporont 
is  finely  granular.     Pelle'rdy  (1949)  con- 
sidered this  a  rather  doubtful  species 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


193 


resembling  E.  debliecki.     However,  the 
absence  of  a  sporocyst  residuum  and 
presence  of  a  micropyle  differentiate  it 
from  this  species. 

Life  Cycle:     Unknown. 

Pathogenesis :     Unknown . 

FIMBRIA  SPINOSA 
HENRY,   1931 

Host:     Pig. 

Location:     Unknown.    Oocysts  found 
in  feces. 


sorted  out  and  their  importance  assessed. 
Coccidia  are  among  the  least  known  of 
these  agents. 

Coccidiosis  is  primarily  a  disease  of 
young  pigs.    Adults  are  carriers.    Eiiiieria 
debliecki  is  probably  the  most  pathogenic 
species,  but  E.  scabra  and  Isospora  suis 
may  also  cause  disease. 

Pigs  become  infected  by  ingesting 
sporulated  oocysts  along  with  their  feed 
or  water.     The  presence  or  severity  of 
the  disease  depends  upon  the  number  of 
oocysts  they  receive.    Crowding  and  lack 
of  sanitation  greatly  increase  the  disease 
hazard. 


Geographic  Distribution:     North 
America  (California,  Minnesota,   Mary- 
land, Georgia),   Hawaii,  USSR  (North 
Caucasus). 

Prevalence:     Unknown.     This  species 
appears  to  be  relatively  uncommon. 

Morphology:     This  species  was  des- 
cribed by  Henry  (1931).     The  oocysts  are 
ovoid  or  ellipsoidal,   16  to  22  by  10  to 
13  ju..    The  oocyst  wall  is  brown,  opaque, 
and  studded  with  spines  about  1  /i  long  and 
1  iu  apart.    A  micropyle  is  absent.    An 
oocyst  polar  granule  is  present.    An 
oocyst  residuum  is  apparently  absent. 
The  sporocysts  have  a  Stieda  body.    A 
sporocyst  residuum  is  apparently  present 
(Henry's  description  is  ambiguous).     The 
sporulation  time  is  11  to  12  days. 

Pathogenesis:    This  species  is  only 
slightly  pathogenic  if  at  all.    Andrews  and 
Spindler  (1952)  observed  no  diarrhea  or 
other  signs  in  an  infected  pig  which  passed 
as  many  as  7  million  oocysts  per  gram  of 
feces. 


COCCIDIOSIS   IN  SWINE 

Epidemiology:     Coccidia  are  common 
in  swine,  but  we  know  little  about  the 
prevalence  and  importance  of  the  disease, 
coccidiosis.     Enteritis  is  so  common  in 
young  pigs  and  is  caused  by  so  many  dif- 
ferent agents  that  they  have  not  all  been 


Avery  (1942)  found  that  the  oocysts  of 
E.  debliecki  and  E.  scabra  could  survive 
and  remain  infective  in  the  soil  for  15 
months.     The  soil  surface  temperature 
varied  between  -4.  5°  and  40°  C  during 
this  period.     Unsporulated  oocysts  with- 
stood continuous  freezing  at  -2^  to  -7°  C 
or  alternate  freezing  and  thawing  at  0.  5° 
and  -3°  C  for  at  least  26  days,  altho  sub- 
sequent sporulation  was  somewhat  de- 
creased. 

Immunity:     Repeated  infections  over 
a  period  of  time  confer  immunity  to  coc- 
cidiosis.    Blester  and  Schwarte  (1932) 
produced  complete  immunity  in  pigs  by 
feeding  oocysts  daily  for  100  days  or 
more.     Light  infections  produced  partial 
immunity. 

The  coccidia  of  swine  are  not  trans- 
missible to  other  farm  animals,  and  pigs 
cannot  be  infected  with  their  coccidia. 

Diagnosis:     Coccidiosis  in  swine  can 
be  diagnosed  by  finding  the  endogenous 
stages  in  lesions  in  the  intestine.     The 
presence  of  oocysts  in  the  feces  does  not 
necessarily  mean  that  coccidiosis  is 
present,  nor  does  their  absence  necessar- 
ily mean  that  it  is  absent,  since  oocysts 
may  not  be  produced  until  2  or  3  days 
after  the  first  signs  of  disease  appear. 

Treatment:     Little  is  known  about 
treatment  of  coccidiosis  in  pigs.    Alicata 
and  Willett  (1946)  found  that  when  1  g 


194 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


sulfaguanidine  per  10  lb  body  weight  was 
administered  to  pigs  daily  with  their  feed 
for  7  or  10  days  beginning  2  days  before 
experimental  infection  with  20  to  30  mil- 
lion sporulated  oocysts  of  E.  debliecki  and 
E.   scabva,  very  few  if  any  oocysts  were 
produced  and  the  pigs  did  not  become  ill. 
Similar  treatment  with  sulfaguanidine  for 
3  days  beginning  on  the  2nd  day  of  oocyst 
discharge  reduced  the  numbers  of  occysts 
produced  and  the  period  of  discharge. 
Presumably  other  sulfonamides  would  also 
be  of  value. 

Prevention  and  Control:     Sanitation 
will  prevent  coccidiosis  in  swine.     Pens 
should  be  cleaned  frequently,  overcrowd- 
ing should  be  avoided,  and  pigs  should  be 
raised  under  conditions  which  prevent 
them  from  eating  many  infective  oocysts. 


the  hot  days  of  October  in  India  (Hire- 
gaudar). 

Life  Cycle:     The  schizonts  and  mero- 
zoites  of  this  species  have  not  been  des- 
cribed.    The  sexual  stages  were  described 
most  recently  by  Hemmert-Halswick  (1943). 
They  are  found  beneath  the  epithelium  in 
the  villi  of  the  small  intestine.     The  mi- 
crogametocytes  measure  up  to  300  by 
170|i  when  mature.     The  macrogametes 
contain  both  eosinophilic  and  basophilic 
plastic  granules  which  later  form  the  wall 
of  the  oocyst. 

Pathogenesis:     Diarrhea,  loss  of 
weight  and  even  death  have  been  reported 
in  heavily  infected  animals.     Hemmert- 
Halswick  (1943)  described  marked  inflam- 
matory changes  in  the  small  intestine 
mucosa. 


EIMERIA   LEUCKARTI 
(FLESCH,   1883) 
REICHENOW,   1940 

Synonyms:     Globidium  leuckarti. 

Hosts:     Horse,  ass. 


Diagnosis:  Diagnosis  can  be  made 
by  finding  the  endogenous  stages  of  this 
coccidium  in  association  with  lesions  in 
the  intestine.  The  oocysts  are  seldom 
seen  in  feces  because  they  are  so  heavy 
that  they  do  not  rise  to  the  surface  in  the 
salt  solutions  used  for  flotations. 


Location:     Small  intestine. 

Geographic  Distribution:     Europe, 
India. 

Prevalence:     Apparently  uncommon. 

Morphology:     The  sporulated  oocysts 
have  been  described  by  Reichenow  (1940a) 
and  Hiregaudar  (1956a).     They  are  ovoid, 
somewhat  flattened  at  the  smaller  end, 
and  75  to  88  by  50  to  59 /i.    The  oocyst 
wall  is  composed  of  2  layers,  of  which  the 
outer  is  dark  brown,   5  to  7)j,  thick,  opaque 
and  granular,  and  the  inner  layer  is  about 
1  [i.  thick  and  colorless.    The  micropyle  is 
distinct.    An  oocyst  residuum  is  absent. 
An  oocyst  polar  granule  is  apparently  ab- 
sent.    The  sporocysts  are  elongate,   30  to 
42  by  12  or  \A\x  with  a  Stieda  body.     A 
sporocyst  residuum  is  present.     The 
sporozoites  are  elongate,  up  to  35 ji  long, 
with  a  clear  globule  at  the  large  end.    The 
sporulation  time  is  21  days  at  20  to  22°  C 
in  Germany  (Reichenow)  or  15  days  during 


EIMERIA   SOLIPEDUM 
GOUSSEFF,   1935 

Hosts:     Horse,  ass. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     USSR 
(Azerbaidzhan,   Volga  basin,   Leningrad). 

Prevalence:     Gousseff  (1935)  found 
this  species  in  1.4%  of  3355  horses,   3% 
of  251  donkeys  and  1%  of  161  mules  in 
Russia. 

Morphology:     The  oocysts  are  spher- 
ical, bright  orange  to  yellowish  brown, 
and  15  to  28  jn  in  diameter.     The  oocyst 
wall  is  double  contoured,  without  a  micro- 
pyle.    An  oocyst  residuum  and  polar  gran- 
ule are  absent.    The  sporocysts  are 
ellipsoidal  or  oval,   5by3fi.     The  sporo- 
zoites are  piriform.     The  presence  or 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


195 


absence  of  a  sporocyst  residuum  could 
not  be  determined. 

Life  Cycle;     Unknown. 

Pathogenesis:     Unknown. 

EIMERIA   UNIUNGULATI 
GOUSSEFF,   1935 

Hosts:     Horse,  ass. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     USSR 
(Azerbaidzhan,  western  RSFSR,   Volga 
region,   Leningrad,  Siberia,   Tadzhikistan, 
Uzbekistan). 

Prevalence:     Gousseff  (1935)  found 
this  species  in  0.  8%  of  3355  horses,   3% 
of  251  donkeys  and  1%  of  161  mules  in 
Russia. 

Morphology:  The  oocysts  are  oval 
(ellipsoidal?),  bright  orange,  and  15  to 
24  by  12  to  17  )n  .  The  oocyst  wall  is 
double  contoured.  A  micropyle,  oocyst 
residuum  and  polar  granule  are  absent. 
The  sporocysts  are  6  to  11  by  4  to  6  jn . 
A  sporocyst  residuum  is  present. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


Geographic  Distribution:     Europe 
(England,   Holland),   North  America  (Ne- 
braska, Quebec),  Australia. 

Prevalence:     This  form  is  uncommon. 
It  was  found  by  Brown  and  Stammers  (1922) 
and  Wenyon  (1923)  in  England,   Nieschulz 
(1924)  in  Holland,  Skidmore  and  McGrath 
(1933)  in  Nebraska  and  Bearup  (1954)  in  a 
dingo  in  Australia.     Choquette  and  Gelinas 
(1950)  reported  it  in  10%  of  155  dogs  in 
Quebec. 

Morphology:     The  oocysts  are  ovoid 
or  ellipsoidal,   17  to  45  by  11  to  28/i, 
pink,   red  or  colorless.    The  oocyst  wall 
is  fairly  thick,   rough,  and  composed  of  2 
layers.    A  micropyle  is  present.     The 
sporocysts  measure  9.  5  by  2.  5|u.    The 
sporulation  time  is  1  to  4  days. 

Remarks:     It  is  far  from  certain  that 
this  is  a  valid  species.    Wenyon  (1926) 
remarked  that  in  many  respects  E.   canis 
resembles  a  mixture  of  E.  stiedae  and  E. 
perforans  of  the  rabbit,  and  Goodrich 
(1944)  considered  it  to  be  a  rabbit  form 
which  the  dogs  had  eaten. 


EIMERIA  CATI 
YAKIMOFF,   1933 

Hosts:     Cat,  dog. 

Location:     Intestine. 


COCCIDIOSIS   IN    HORSES, 
ASSES   AND   MULES 

Coccidiosis  is  such  a  rarity  in  horses, 
asses  and  mules  that  little  can  be  said 
about  it.    The  same  measures  which  are 
effective  in  cattle  should  control  coccid- 
iosis in  equids. 

EIMERIA  CANIS 
WENYON,   1923 

Hosts:.    Dog,  cat,  dingo. 

Location:     Unknown.    Oocysts  found 
in  feces. 


Geographic  Distribution:     USSR. 

Prevalence:     Rare. 

Morphology:     The  oocysts  are  ovoid 
or  spherical;  the  ovoid  oocysts  are  18  to 
24  by  14  to  20  ji  with  a  mean  of  21  by  17  fj,; 
the  spherical  oocysts  are  16  to  22  jj.  in 
diameter  with  a  mean  of  18jj, .     A  micro- 
pyle is  absent.    An  oocyst  polar  granule 
is  present.    An  oocyst  residuum  is  absent. 
A  sporocyst  residuum  is  present. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


196 


TlIF  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


EIMERIA   FELINA 
NIESCHULZ,   1924 

Hosts:     Cat,   lion. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     Europe 
(Holland). 

Prevalence:     Rare. 

Morphology:     The  oocysts  are  ellip- 
soidal,  21  to  26  by  13  to  17  ji  with  a  mean 
of  24  by  14.  5ji.     The  oocyst  wall  is  about 
1  ^t  thick,  smooth,  colorless,  and  double 
contoured.    A  definite  micropyle  is  ab- 
sent.   An  oocyst  polar  granule  is  absent. 
An  oocyst  residuum  is  present.     The 
sporocysts  are  elongate  ovoid,  with  a 
Stieda  body.    A  sporocyst  residuum  is 
present.     The  sporozoites  are  comma- 
shaped,  with  a  large  vacuole  at  the  large 
end  and  usually  a  small  one  at  the  small 
end. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


EIMERIA  STIEDAE 

(LINDEMANN.    1865) 

KISSKALT  AND   HARTMANN,    1907 

Synonyms:     Monocystis  stiedae, 
Cocciditu)!  ovi/orme,   Coccidium  cimicidi. 

Hosts:     Domestic  rabbit,   European 
hare  (Lepus  europaeiis),  varying  hare 
(L.  aniericanHs),  black-tailed  jack  rabbit 
(L.   calif  or  nic  us),  alpine  hare  (L.   tini- 
idus),   L.   variabilis,  cottontails  {Sylvil- 
agus  floridanus ,   S.  nuttalli). 

Location:      Liver.     The  coccidia  are 
found  in  the  bile  duct  epithelial  cells. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  is  the  most  com- 
mon and  most  important  coccidium  of 
domestic  rabbits.    It  also  occurs  in  hares 
{Lepus),  but  is  less  common  in  cottontails 
than  other  species. 


Morphology:     The  oocysts  are  ovoid, 
sometimes  ellipsoidal,  with  a  flat  micro- 
pylar  end,   and  measure  28  to  40  by  16  to 
25  ji  with  a  mean  of  37  by  21  /i .     The 
oocyst  wall  is  smooth  and  salmon-colored. 
A  micropyle  is  present.    An  oocyst  polar 
granule  and  oocyst  residuum  are  absent. 
The  sporocysts  are  elongate  ovoid,  18  to 
10  |i,  with  a  Stieda  body.     A  sporocyst 
residuum  is  present.     The  sporulation 
time  is  3  days. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  by  a  number  of 
workers  (see  Becker,   1934,  for  a  review). 
The  sporulated  oocysts  excyst  in  the  small 
intestine.     The  sporozoites  penetrate  the 
intestinal  mucosa,  enter  the  hepatic  portal 
system,  and  pass  to  the  liver.     Here  they 
enter  the  epithelial  cells  of  the  bile  ducts. 
The  liver  parenchyma  cells  are  only  rarely 
invaded.    Development  takes  place  above 
the  host  cell  nucleus.     Each  sporozoite 
rounds  up  and  becomes  a  schizont  which 
produces  6  to  30  or  more  (usually  8  to  16) 
merozoites  which  measure  about  8  to  10 
by  1.  5  to  2.  0(1 .     The  number  of  asexual 
generations  is  not  known.     Later,   some 
merozoites  become  microgametocytes 
which  produce  large  numbers  of  comma- 
shaped,  biflagellate  microgametes,  while 
others  become  macrogametes.     These  are 
fertilized,  lay  down  an  oocyst  wall,  break 
out  of  their  host  cell,   pass  into  the  intes- 
tine with  the  bile  and  thence  out  of  the 
body.    The  prepatent  period  is  18  days. 

Pathogenesis:     In  mild  cases  of  liver 
coccidiosis  there  may  be  no  signs,  but  in 
more  severe  ones  the  animals  lose  their 
appetites  and  grow  thin.     There  may  be 
diarrhea,  and  the  mucous  membranes  may 
be  icteric.     The  disease  is  more  severe  in 
young  animals  than  in  old.    It  may  be 
chronic,  or  death  may  occur  in  21  to  30 
days. 

Some  of  the  symptoms  are  due  to  in- 
terference with  liver  function.     The  liver 
may  become  markedly  enlarged,  and  white 
circular  nodules  or  elongated  cords  appear 
in  it.     At  first  they  are  sharply  circum- 
scribed, but  later  they  tend  to  coalesce. 
They  are  enormously  enlarged  bile  ducts 
filled  with  the  developing  parasites. 
There  is  tremendous  hyperplasia  of  the 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


197 


bile  duct  epithelial  cells.    Instead  of  form- 
ing a  simple,  narrow  tube,  the  epithelium 
is  thrown  into  great,  arborescent  folds, 
and  each  cell  contains  a  parasite. 

Dunlap,  Dickson  and  Johnson  (1959) 
found  that  infection  with  E.  stiedae  in- 
creased the  serum  /3-  and  y-globulin  and 
i3-lipoprotein  and  decreased  the  a-lipo- 
protein. 


EIMERIA  MAGNA 
PERARD,    1925 

Synonyms:     Eimeria  p  erf  or  ans  var. 
magna. 

Hosts:     Domestic  rabbit,   California 
jack  rabbit  {Lepus  calif ornicus),  varying 
hare  (L.   tiniidus),  European  hare  (L. 
europaeus),  cottontail  (Sylvilagus  flori- 
danus)  (experimental). 

Location:     Jejunum,  ileum. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  quite 
common.    Kessel  and  Jankiewicz  (1931) 
found  it  in  19%  of  over  2000  rabbits  in 
California. 

Morphology:     The  oocysts  are  ovoid 
or  ellipsoidal,  becoming  subspherical 
toward  the  end  of  the  patent  period, 
smooth,  orange-yellow  or  brownish,  and 
27  to  41  by  17  to  29  ;j  with  a  mean  of  35 
by  24jLL.     The  micropyle  is  large  and  sur- 
rounded by  prominent  shoulders.    An 
oocyst  polar  granule  is  absent.    An  oocyst 
residuum  is  present.     The  sporocysts  are 
elongate  ovoid,  with  a  Stieda  body.    A 
sporocyst  residuum  is  present.     The 
sporulation  time  is  2  to  3  days.     Oocyst 
variation  was  studied  carefully  by  Kheisin 
(1947). 

Life  Cycle:     Rutherford  (1943)  des- 
cribed the  life  cycle  of  this  species.     The 
endogenous  stages  are  found  below  the 
epithelial  cell  nuclei  of  the  villi  and  also 
in  the  submucosa.     There  are  2  asexual 
generations  of  merozoites  followed  by 
microgamete  and  macrogamete  production. 


It  takes  7  days  for  completion  of  the  endo- 
genous cycle,  and  the  prepatent  period  is 
7  to  8  days.    According  to  Kheisin  (1947), 
E.  magna  produces  800,000  oocysts  per 
oocyst  fed. 

Pathogenesis:     This  is  one  of  the 
most  pathogenic  of  the  intestinal  coccidia 
of  the  rabbit.     Only  a  few  hundred  oocysts 
of  some  strains  may  produce  symptoms, 
and  300,000  may  cause  death  (Lund,  1949). 
Other  strains  are  less  pathogenic,   1  mil- 
lion oocysts  not  causing  death.     The  prin- 
cipal signs  are  loss  of  weight,   inappetance 
and  diarrhea.    A  good  deal  of  mucus  may 
be  passed.    The  animals  lose  their  appe- 
tites and  grow  thin.    The  intestinal  mucosa 
is  hyperemic  and  inflamed,  and  epithelial 
sloughing  may  occur. 


EIMERIA  PERFORANS 

(LEUCKART,   1879) 

SLUITER  AND  SWELLENGREBEL,  1912 

Synonyms:      Coccidium  perforans, 
Eimeria  exigiia,  E.   Jugdunumensis. 

Hosts:     Domestic  rabbit,  varying 
hare  {Lepus  americanus),  east  Greenland 
hare  (L.  arcticus  groenlandicus),  Califor- 
nia jack  rabbit  (L.   calif  ornicus),  European 
hare  {L.   europaeus),  Brazilian  cottontail 
{Sylvilagus  brasiliensis),  cottontail  {Syl- 
vilagus floridanus)  (experimentally). 

Location:     Thruout  small  intestine 
and  also  in  cecum. 

Geographic  Distribution:     Worldwide. 

Prevalence:  Common.  Kessel  and 
Jankiewicz  (1931)  found  it  in  30%  of  over 
2000  rabbits  in  California. 

Morphology:    The  oocysts  are 
ellipsoidal,   sometimes  ovoid,   smooth, 
colorless  to  pinkish,   24  to  30  by  14  to 
20jLi    with  a  mean  of  26  by  lOju  .     A 
micropyle  is  absent.     An  oocyst  polar 
granule  is  absent.     An  oocyst  residuum 
is  present.     The  sporocysts  are  ovoid, 
with  a  Stieda  body.    A  sporocyst  residuum 
is  present.     The  sporulation  time  is 
2  days. 


198 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


Life  Cycle:     Rutherford  (1943)  des- 
cribed the  life  cycle  of  this  species.    The 
endogenous  stages  are  found  above  the 
nuclei  of  the  epithelial  cells  of  the  intes- 
tine.    There  are  2  asexual  generations  of 
merozoites,  followed  by  microgamete  and 
macrogamete  production.     Completion  of 
the  endogenous  cycle  takes  5  days,  and 
the  prepatent  period  is  5  to  6  days. 

Pathogenesis:     E.  perforans  is  one 
of  the  less  pathogenic  intestinal  coccidia 
of  rabbits,  but  it  may  nevertheless  cause 
mild  to  moderate  signs  if  the  infection  is 
heavy  enough.     The  duodenum  may  be  en- 
larged and  edematous,  sometimes  chalky 
white;  the  jejunum  and  ileum  may  contain 
white  spots  and  streaks,  and  there  may 
be  petechiae  in  the  cecum. 


production.    Completion  of  the  endogenous 
cycle  takes  6  days,  and  the  prepatent  per- 
iod is  5  to  6  days.    According  to  Kheisin 
(1947),  E.  media  produces  150,  000  oocysts 
per  oocyst  fed. 

Pathogenesis:     This  species  is  moder- 
ately pathogenic  (Pelle'rdy  and  Babos,  1953). 
It  may  cause  the  usual  signs  of  intestinal 
coccidiosis.     The  affected  parts  of  the  in- 
testine may  be  edematous,  with  greyish 
foci. 


EIMERIA  IRRESIDUA 

KESSEL  AND  JANKIEWICZ,   1931 

Hosts:     Domestic  rabbit,  California 
jack  rabbit  {Lepus  calif ornicus),  white- 
tailed  jack  rabbit  (L.  loivnsendii). 


EIMERIA  MEDIA 
KESSEL,   1929 

Synonym:     Eimeria  flavescens. 

Hosts:     Domestic  rabbit,   California 
jack  rabbit  (Lepus  californicus),  cotton- 
tail {Sylvllagiis  floridamis),  Wyoming 
cottontail  (S.  niiltallii  grangeri). 

Location:     Thruout  small  and  large 
intestines. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Quite  common.    Kessel 
and  Jankiewicz  (1931)  found  it  in  12%  of 
over  2000  rabbits  in  California. 

Morphology:     The  oocysts  are  ovoid, 
smooth,   19  to  33  by  13  to  21  jii .     A  micro- 
pyle  is  present.    An  oocyst  polar  granule 
is  absent.    An  oocyst  residuum  is  present. 
The  sporocysts  are  elongate  ovoid,  with  a 
Stieda  body.    A  sporocyst  residuum  is 
present.     The  sporulation  time  is  2  days. 

Life  Cycle:     Rutherford  (1943)  and 
Pellerdy  and  Babos  (1953)  described  the 
life  cycle  of  this  species.    The  endogenous 
stages  are  found  above  or  below  the  epi- 
thelial cell  nuclei  of  the  intestinal  villi 
and  also  occur  in  the  submucosa.    There 
are  2  asexual  generations  of  merozoites 
followed  by  microgamete  and  macrogamete 


Location:     Thruout  small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Quite  common.    Kessel 
and  Jankiewicz  (1931)  found  this  species 
in  10%  of  over  2000  rabbits  in  California. 

Morphology:     The  oocysts  are  ovoid, 
smooth,  and  38  by  26 jm.     The  micropyle 
is  prominent.    An  oocyst  polar  granule 
and  oocyst  residuum  are  absent.     The 
sporocysts  are  elongate  ovoid,  with  a 
Stieda  body.    A  sporocyst  residuum  is 
present.     The  sporulation  time  is  2  to  2.  5 
days. 

Life  Cycle:     Rutherford  (1943)  des- 
cribed the  life  cycle  of  this  species.    The 
endogenous  stages  are  found  above  or  be- 
low the  epithelial  cell  nuclei  of  the  intes- 
tinal villi  and  also  occur  in  the  submucosa. 
There  are  2  asexual  generations  of  mero- 
zoites followed  by  microgamete  and  macro- 
gamete production.     Completion  of  the 
endogenous  cycle  takes  9  to  10  days,  and 
the  prepatent  period  is  9  to  10  days. 

Pathogenesis:     This  is  one  of  the 
more  pathogenic  of  the  intestinal  coccidia 
of  rabbits.    It  causes  the  usual  signs  of 
intestinal  coccidiosis.    The  affected  areas 
are  hyperemic,  there  may  be  extravasation 
of  blood,  and  the  epithelium  may  slough 
and  become  denuded. 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


199 


EIMERIA  PIRIFORMIS 
KOTLAN  AND   POSPESCH,   1934 

Host:     Domestic  rabbit. 

Location:     Small  and  large  intestines. 


Geographic  Distribution: 
(France,   Hungary). 


Europe 


Prevalence: 
This  species 


Relatively  uncommon. 


has  been  found  in  both  wild 
and  captive  domestic  rabbits. 

Morphology:     The  oocysts  are  piri- 
form to  ovoid,  smooth,  yellowish  brown, 
26  to  32  by  17  to  21  ji  with  a  mean  of  29 
by  18jn.    A  micropyle  is  present.    An 
oocyst  polar  granule  and  oocyst  residuum 
are  absent.    A  sporocyst  residuum  is 
present.    The  sporulation  time  is  2  days. 

Life  Cycle:     The  life  cycle  of  this 
species  does  not  appear  to  have  been 
worked  out  in  detail.    The  life  cycle  des- 
cribed by  Pellerdy  (1953)  for  "E.  piri- 
fovDiis"  is  actually  that  of  E.   intestinalis. 
The  prepatent  period  is  9  days. 

Pathogenesis:     Unknown. 


The  sporozoites  are  elongate  ovoid,  with 
a  Stieda  body.  The  sporulation  time  is  2 
to  3  days. 

Life  Cycle:     The  endogenous  cycle  of 
this  species  has  not  been  described. 

Pathogenesis:     This  species  is 
slightly  to  markedly  pathogenic,  depending 
upon  the  extent  of  the  infection.    The  af- 
fected intestinal  mucosa  is  inflamed  and 
hyperemic,  and  caseous  necrosis  may  be 
present. 

Remarks:    Pelle'rdy  (1954a)  found  a 
coccidium  which  he  believed  to  be  E. 
neoleporis  in  domestic  rabbits  in  Hungary 
and  described  its  pathogenic  effects.     He 
believed  that  E.  coecicola  was  a  synonym 
of  this  species  and  he  may  be  right. 
Carvalho  (1942)  transmitted  E.  neoleporis 
from  the  cottontail  to  the  domestic  rabbit. 
However,  for  the  present  I  am  using  the 
name  E.  neoleporis  for  the  cottontail  form 
alone. 


EIMERIA  COECICOLA 
CHEISSIN,   1946 

Host:     Domestic  rabbit. 


EIMERIA  NEOLEPORIS 
CARVALHO,   1942 

Hosts:     Cottontail  (Sylvilagus  flori- 
danus),  domestic  rabbit  (experimentally). 

Location:     Posterior  part  of  small 
intestine,  large  intestine. 

Geographic  Distribution:     North 
America. 

Prevalence:     Common  in  cottontails. 
Ecke  and  Yeatter  (1956)  found  this  species 
in  31%  of  32  cottontails  in  Illinois. 


Location:     Posterior  ileum,  cecum. 

Geographic  Distribution:     Europe 
(Hungary),  USSR. 

Prevalence:     This  species  is  appar- 
ently rare  in  captive  domestic  rabbits,  but 
is  common  in  wild  ones. 

Morphology:     The  oocysts  are  ovoid, 
sometimes  ellipsoidal,    smooth,  light  yel- 
low, 25  to  40  by  15  to  21  |j, .    A  micropyle 
is  present.    An  oocyst  polar  granule  is 
absent.    Oocyst  and  sporocyst  residua  are 
present.     The  sporulation  time  is  3  days. 


Morphology:     The  oocysts  are  sub- 
cylindrical  or  elongate  ellipsoidal  to  ovoid, 
smooth,   pinkish  yellow,   33  to  44  by  16  to 
23  [I  with  a  mean  of  39  by  20  jix  .    A  micro- 
pyle is  present.    An  oocyst  polar  granule 
is  absent.    An  oocyst  residuum  is  usually 
absent.    A  sporocyst  residuum  is  present. 


Life  Cycle:  Kheisin  (1947)  described 
the  life  cycle  of  this  species.  The  schi- 
zonts  are  found  in  the  epithelial  cells  of 
the  villi  of  the  posterior  ileum,  and  the 
gametes  and  gametocytes  are  below  the 
host  cell  nuclei  of  the  crypt  cells  of  the 
cecum.    The  prepatent  period  is  9  days, 


200 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


and  100,000  oocysts  are  produced  per 
oocyst  fed. 

Pathogenesis:     According  to  Kheisin 
(1947),  this  species  is  slightly  if  at  all 
pathogenic.     He  saw  small  white  spots  in 
the  cecum  which  were  groups  of  developing 
oocysts. 


EIMERIA  ELONGATA 
MAROTEL  AND  GUILHON,   1941 

Synonym :     Eimeria  neoleporis 
Carvalho,  1942  (?). 

Host:     Domestic  rabbit. 

Location:     Unknown,  presumably  in- 
testine. 

Geographic  Distribution:     Europe 
(France). 

Prevalence:     Unknown. 

Morphology:     The  oocysts  are  slightly 
greyish,  elongate  ellipsoidal  with  almost 
straight  sides,   35  to  40  by  17  to  20  fi  .    The 
oocyst  wall  is  thin.     The  micropyle  is 
broad  and  easily  visible.     An  oocyst  polar 
granule  and  oocyst  residuum  are  absent. 
The  sporocysts  are  elongate.    A  sporo- 
cyst  residuum  is  present,  and  almost  as 
long  as  the  sporocysts.    The  sporulation 
time  is  4  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     Becker  (1956)  believed 
that  this  species  and  E.  neoleporis  from 
the  cottontail  might  be  the  same,  and  I 
agree.     However,  it  is  probably  best  to 
retain  both  names  pending  further  research. 


EIMERIA  INTESTINALIS 
KHEISIN,   1948 

Synonyms:     Eimeria  agnosia, 
Eimeria  piri/or)nis  Gwelessiany  and 
Nadiradze,   1945;  non  E.  piriformis  Kotlan 
and  Pospesch,  1934. 


Host:     Domestic  rabbit. 


Location:     Small  intestine  except 


anterior  duodenum. 

Geographic  Distribution: 
(Hungary),   USSR. 


Europe 


Prevalence:     Relatively  uncommon. 

Morphology:     The  oocysts  are  piri- 
form, smooth,  yellowish,  21  to  36  by  15 
to  21/i.    A  micropyle  is  present.     An 
oocyst  polar  granule  is  absent.     An  oocyst 
residuum  is  present.     The  sporulation 
time  is  1  to  2  days.     Kheisin  (1958)  made 
a  cytochemical  study  of  the  oocysts  and 
endogenous  stages  of  this  species. 

Life  Cycle:     Pelle'rdy  (1953)  des- 
cribed the  life  cycle  of  this  species  under 
the  name  E.  piriformis.     The  endogenous 
stages  occur  above  or  sometimes  beside 
the  nuclei  of  the  epithelial  cells  of  the 
small  intestine.     There  are  at  least  2  gen- 
erations of  merozoites.     The  prepatent 
period  is  9  days. 

Pathogenesis:     According  to  Pellerdy 
(1953,   1954),  experimental  infections  with 
this  species  cause  more  or  less  severe 
intestinal  catarrh  and  diarrhea,  and  may 
kill  young  rabbits.     At  necropsy,  edema 
and  greyish-white  foci  which  may  coalesce 
to  form  a  homogeneous,  sticky,   purulent 
layer  may  be  found  in  the  intestine. 


EIMERIA  MATSUBAYASHII 
TSUNODA,   1952 

Host:     Domestic  rabbit. 

Location:     Primarily  ileum. 

Geographic  Distribution:     Japan. 

Prevalence:     Unknown. 

Morphology:     The  oocysts  are 
broadly  ovoid,  22  to  29  by  16  to  22  ^l  with 
a  mean  of  25  hy  IS^i .    A  micropyle  is 
present.    An  oocyst  residuum  is  present. 
The  presence  or  absence  of  an  oocyst 
polar  granule  and  a  sporocyst  residuum 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


201 


are  unknown, 
to  2  days. 


The  sporulation  time  is  1.  5 


Life  Cycle:     Unknown. 

Pathogenesis:     According  to  Tsunoda 
(1952),  this  species  may  be  slightly  to 
moderately  pathogenic,  causing  a  diphther- 
itic enteritis. 


COCCIDIOSIS   IN    DOMESTIC   RABBITS 

Epidemiology:     The  most  important 
species  of  rabbit  coccidium  is  Eimeria 
stiedae,  which  occurs  in  the  liver.     All 
the  other  species  are  found  in  the  intestine. 
Of  these,  the  most  important  are  E. 
residua,  E.  magna,  E.   media  a.nd  E.  per- 
f oralis.     Kheisin  (1957)  has  assembled  in- 
formation on  the  localization  of  the  intes- 
tinal species. 

Coccidiosis  is  primarily  a  disease  of 
young  rabbits;  adults  are  carriers.     Rab- 
bits become  infected  by  ingesting  oocysts 
along  with  their  feed  or  water.     The  se- 
verity of  the  disease  depends  upon  the 
number  of  oocysts  they  ingest  and  also 
upon  the  species  involved.     Mixed  infec- 
tions are  the  rule,  infections  with  a  single 
species  usually  being  seen  only  under 
laboratory  conditions.     Crowding  and  lack 
of  sanitation  greatly  increase  the  disease 
hazard. 

Some  of  the  coccidia  of  the  domestic 
rabbit  {Oryctolagus  cnniculiis)  also  occur 
in  cottontails  {Sylvilagiis  spp. ).    Some 
have  also  been  reported  from  jack  rabbits 
and  hares  (Lepus  spp.  ).     However,  after 
reviewing  the  cross-transmission  studies 
carried  out  to  date,  Pelle'rdy  (1956a)  con- 
cluded that,  except  for  E.  stiedae,  none 
of  the  coccidia  of  jack  rabbits  and  hares 
occur  in  domestic  rabbits  and  cottontails, 
and  none  of  the  coccidia  of  the  latter  two 
genera  occur  in  Lepus.    If  this  conclusion 
is  confirmed,  the  listing  above  of  Lepus 
as  a  host  of  E.   niagna,  E.  perforans, 
E.  media  and  E.  irresidua  would  be  in- 
correct.    Further  cross-transmission 
experiments  are  needed  to  settle  this 
matter. 


Diagnosis:      Liver  coccidiosis  can  be 
diagnosed  by  finding  the  characteristic 
lesions  containing  coccidia.    Intestinal 
coccidiosis  can  be  diagnosed  by  finding 
the  coccidia  on  microscopic  examination. 
However,  the  mere  presence  of  these 
parasites  in  a  case  of  enteritis  does  not 
mean  that  they  caused  it.     Many  rabbits 
carry  a  few  coccidia  without  suffering  any 
noticeable  effects.     In  a  3-year  study  of 
mortality  among  hutch-raised  domestic 
rabbits  in  California,   Lund  (1951)  consid- 
ered coccidiosis  to  be  the  cause  of  enter- 
itis in  only  80  out  of  1541  affected  animals. 

Treatment:     Some  of  the  sulfonamides 
have  been  found  helpful  in  preventing  coc- 
cidiosis if  given  continuously  in  the  feed 
or  drinking  water.    Succinylsulfathiazole, 
sulfamerazine  or  sulfamethazine  mixed 
with  the  feed  at  the  rate  of  0.5%  have  been 
recommended  (Horton-Smith,   1947;  Ger- 
undo,  1948),  as  have  been  0.02  to  0.05% 
sodium  sulfaquinoxaline  or  sodium  sulfa- 
merazine in  the  drinking  water.     Lund 
(1954)  found  that  the  administration  of 
0.  03%  sulfaquinoxaline  in  the  feed  con- 
trolled E.  stiedae  infections  effectively  if 
begun  not  more  than  4  days  after  exper- 
imental infection.     The  drug  was  not  com- 
pletely effective  at  this  level,  but  it  did 
give  practical  control.     Lund  stated  further 
that  this  drug  had  not  been  found  to  harm 
rabbits  when  fed  continuously. 

However,   long-term,  continuous  feed- 
ing of  such  drugs  is  not  particularly  de- 
sirable, nor  is  it  usually  necessary.    It 
has  been  the  usual  experience  with  poultry, 
and  there  is  evidence  that  the  same  thing 
is  true  with  rabbits  (see  Horton-Smith, 
1947),  that  if  the  hosts  are  exposed  to 
coccidiosis  during  the  drug-feeding  period 
(as  they  usually  are),  an  aborted  infection 
occurs  which  is  sufficient  to  induce  immun- 
ity.   The  drug  can  then  be  safely  stopped. 

Prevention:     Coccidiosis  can  be  pre- 
vented by  proper  management  (see  Lund, 
1949).     Feeders  and  waterers  should  be 
designed  so  that  they  do  not  become  con- 
taminated with  droppings,  and  should  be 
kept  clean.    Hutch  floors  should  be  self- 
cleaning  or  should  be  cleaned  frequently 


202 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


and  kept  dry.     Manure  should  be  removed 
frequently.     The  animals  should  be  han- 
dled as  little  as  possible,  and  care  should 
be  taken  not  to  contaminate  either  the 
animals  themselves  or  their  food,  utensils 
or  equipment.    In  addition,  the  rabbitry 
should  be  kept  as  free  as  possible  of  in- 
sects,  rodents  and  other  pests. 


EIMERIA    TEN  ELLA 
(RAILLIET  AND   LUCET,    1891) 
FANTHAM,    1909 

Synonyms:     Eimeria  avium,   Coccid- 
ium  teiiellion,   Coccidiu»i  globosum, 
Eimeria  bracheti. 

Host:     Chicken. 

Location:     Ceca. 


Geographic  Distribution:     Worldwide. 

Prevalence:     Very  common. 

Morphology:     The  oocysts  are  broadly 
ovoid,  smooth,   14  to  31  by  9  to  25 ^t  with 
a  mean  of  22.  9  by  19.  1  p. .    A  micropyle  is 
absent.    An  oocyst  polar  granule  is  pres- 
ent.   An  oocyst  residuum  is  absent.     The 
sporocysts  are  ovoid,  without  a  sporocyst 
residuum. 


The  sporulation  time  is  1  to  2  days. 
Edgar  (1954)  found  that  the  minimum  spor- 
ulation time  is  18  hours  at  29°  C,   21  hours 
at  26.  5  to  28    and  24  hours  at  20,  24  and 
32   .     Maximum  sporulation  was  reached 
in  22  to  24  hours  at  29   ,  the  optimum 
temperature.    Some  sporulation  took  place 
at  41  ° .    When  the  oocysts  were  kept  at  8° 
they  failed  to  sporulate  in  8  weeks  and 
most  were  killed,  so  that  only  a  few  spor- 
ulated  when  they  were  subsequently  held 
at  28°. 

Life  Cycle:     The  life  cycle  of  E. 
tenella  has  already  been  described  as  an 
example  of  coccidian  life  cycles  (p.    160). 

Pathogenesis:     This  is  the  most 
pathogenic  of  the  chicken  coccidia  and  is 
responsible  for  heavy  losses.     Together 
with  the  other  species,   it  was  estimated 


by  the  USDA  (1954)  to  cause  an  annual  loss 
of  $38,  229,  000  in  the  United  States  due  to 
death  and  disease  alone.     To  this  should  be 
added  the  cost  of  the  medicated  feeds  which 
are  generally  fed  to  poultry,  and  various 
labor  and  other  costs  entailed  by  disease 
outbreaks. 

Cecal  coccidiosis  is  found  most  fre- 
quently in  young  birds.     Chicks  are  most 
susceptible  at  4  weeks  of  age,  while  chicks 
1  to  2  weeks  old  are  more  resistant  (Gardi- 
ner,  1955).     However,  day-old  chicks  can 
be  infected  (Gordeuk,  Bressler  &  Glantz, 
1951).     Older  birds  develop  immunity  as 
the  result  of  exposure. 

Coccidiosis  due  to  E.  tenella  may  vary 
in  severity  from  an  inapparent  infection  to 
an  acute,  highly  fatal  disease,  depending 
upon  the  infective  dose  of  oocysts.     The 
pathogenicity  of  different  strains  of  E. 
tenella  varies,  and  it  is  affected  also  by 
the  breed  and  age  of  the  chickens  and  their 
state  of  nutrition.     Thus,  Jankiewicz  and 
Scofield  (1934)  found  that  less  than  150 
sporulated  oocysts  produced  no  signs,   150 
to  500  oocysts  produced  slight  hemorrhagic 
diarrhea,   1000  to  3000  oocysts  produced 
moderate  hemorrhage  and  a  few  deaths, 
3000  to  5000  oocysts  produced  marked 
hemorrhage  and  moderate  mortality,  and 
more  than  5000  oocysts  produced  severe 
hemorrhage  and  high  mortality.    However, 
Horton-Smith(1949)  found  that  infections 
with  15,000  oocysts  caused  no  mortality 
in  week-old  birds,   30,000  oocysts  caused 
32%  mortality  and  60,  000  oocysts  caused 
45%  mortality.    Swales  (1944)  found  that 
in  6-week-old  chickens  15,000  oocysts 
caused  40%  mortality,   30,000  oocysts 
caused  44%i  moi'tality  and  200,  000  oocysts 
caused  80%  mortality,  while  in  4.  5-week- 
old  chicks  120,000  oocysts  caused  90% 
mortality  and  in  12-week-old  chicks 
100,000  oocysts  caused  50'(  mortality. 
Waletzky  and  Hughes  (1949)  found  that  in 
one  experiment  20.000  oocysts  produced 
18-';  mortality  and  100.  000  oocysts  36%. 
mortality  in  4-weck-old  chicks,  while  in 
other  experiments  50,  000  oocysts  produced 
45*'(  mortality  in  7-week-old  chicks, 
100,000  oocysts  produced  67'r  mortality  in 
4-  to  5-week-old  chicks  and  500,000 
oocysts  produced  48%  mortality  in  3-  to 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


203 


6-week-old  chicks.     Gardiner  (1955)  found 
that  200,  000  oocysts  were  required  to  pro- 
duce mortality  in  1-  to  2-week-old  chicks, 
while  50,000  to  100,000  oocysts  produced 
mortality  in  older  birds. 

Cecal  coccidiosis  is  an  acute  disease 
characterized  by  diarrhea  and  massive 
cecal  hemorrhage.     The  first  signs  appear 
when  the  second  generation  schizonts  be- 
gin to  enlarge  and  produce  leakage  of 
blood  into  the  ceca.     Blood  first  appears 
in  the  droppings  4  days  after  infection. 
At  this  time  the  birds  appear  listless. 
They  may  become  droopy  and  inactive, 
and  eat  little,  altho  they  still  drink.    The 
greatest  amount  of  hemorrhage  occurs  on 
the  5th  and  6th  days  after  infection.     It 
then  declines,  and  oocysts  appear  in  the 
feces  7  days  after  infection  if  the  birds 
live  that  long.     The  oocysts  increase  to  a 
peak  on  the  8th  or  9th  day  and  then  drop 
off  very  rapidly.     Very  few  are  still  being 
shed  by  the  11th  day.    A  few  oocysts  may 
be  found  for  several  months. 

Coccidiosis  is  self-limiting,  and  if 
the  birds  survive  to  the  8th  or  9th  day 
after  infection,  they  generally  recover. 

The  lesions  of  cecal  coccidiosis  de- 
pend upon  the  stage  of  the  disease.    They 
have  been  described  by  Tyzzer  (1929), 
Tyzzer,   Theiler  and  Jones  (1932)  and 
Mayhew  (1937).     On  the  fourth  day  after 
infection,   hemorrhage  is  present  thruout 
the  cecal  mucosa.    On  the  fifth  day,  the 
cecum  is  filled  with  large  amounts  of  un- 
clotted  or  only  partly  clotted  blood.     This 
increases  on  the  sixth  day.     Cecal  cores 
of  fibrinous  and  necrotic  material  begin 
to  form  on  the  7th  day.     They  adhere 
tightly  to  the  mucosa  at  first,  but  soon 
come  loose  and  lie  free  in  the  lumen. 

About  7  days  after  infection,  the  wall 
of  the  cecum  changes  color  from  red  to 
mottled  reddish  or  milky  white  due  to  the 
formation  of  oocysts.    It  is  greatly  thick- 
ened.    The  cecal  core,  which  was  at  first 
reddish,  becomes  yellowish  or  whitish. 
If  it  is  small  enough,  it  may  be  passed  in- 
tact in  the  feces,  but  usually  it  is  broken 
up  into  small  pieces.    In  a  few  days  the 
cecum  becomes  normal  in  appearance  or 


at  most  slightly  enlarged  and  thickened. 
Occasionally  the  cecum  may  rupture  or 
adhesions  may  form. 

About  the  4th  day,  when  the  second 
generation  schizonts  are  developing,  the 
lamina  propria  becomes  infiltrated  with 
eosinophiles,  there  is  marked  congestion, 
and  the  cecal  wall  is  thickened.     The 
epithelium  may  be  torn  and  coccidia,  blood 
and  tissue  cells  may  be  released  into  the 
lumen  in  areas  where  there  are  large 
numbers  of  parasites.     On  the  5th  day, 
when  the  second  generation  merozoites 
are  released,  their  host  cells  are  ruptured 
and  there  is  extensive  epithelial  sloughing. 
The  sloughed  material  and  cecal  contents 
consolidate  to  form  the  cecal  core,  which 
loosens  from  the  wall  as  the  epithelium  is 
regenerated. 

Epithelial  regeneration  is  complete  in 
light  infections,  but  in  severe  ones  it  may 
not  be.     There  is  a  marked  inflammatory 
reaction,  with  extensive  lymphoid  and 
plasma  cell  infiltration,  and  there  may  be 
some  giant  cells.     Connective  tissue  is  in- 
creased.   The  epithelium  may  not  be  re- 
placed between  the  glands,  and  cysts 
formed  by  constriction  of  the  glands  during 
the  inflammatory  stage  may  persist. 

The  loss  of  blood  into  the  ceca  causes 
anemia.     Using  the  microhematocrit  tech- 
nic,  Joyner  and  Davies  (1960)  found  that 
the  packed  red  cell  volume  decreased 
markedly  beginning  5  days  after  experi- 
mental infection.     From  an  original  level 
of  26  to  29%  it  decreased  to  18%  and  14%, 
respectively,   7  days  after  infection  with 
2000  and  10,000  oocysts.    It  had  returned 
to  normal  5  days  later. 

Natt  (1959)  found  that  E.  tenella 
causes  marked  changes  in  the  leucocyte 
picture.     He  observed  lymphopenia  and 
heterophilia  on  the  5th  day,  and  eosino- 
philia  on  the  10th  day  after  infection.     A 
marked  leucocytosis  began  on  the  7th  day 
and  persisted  thru  the  recovery  phase. 

Birds  which  recover  from  coccidiosis 
may  suffer  ill  effects  for  some  time  or 
even  permanently.    Gardiner  (1954)  found 
an  inverse  correlation  between  growth 


204 


THE  TELOSPORASIDA  AND  THE  CCXTCIDIA   PROPER 


rate  and  severity  of  cecal  coccidiosis. 
Chicks  which  recovered  following  severe 
infection  made  much  poorer  weight  gains 
than  mildly  affected  ones.     Mayhew(1932, 
1932a,   1934)  found  that  it  took  10  weeks 
to  6  months  after  recovery  before  in- 
fected birds  regained  the  weight  they  had 
lost  in  comparison  with  uninfected  con- 
trols.    He  found,  too,  that  pullets  which 
had  been  infected  when  6  to  8  weeks  old 
laid  19.25%  fewer  eggs  than  the  controls. 
In  addition,  severely  affected  birds  began 
to  lay  6  to  7  weeks  later  than  the  controls. 
Davidson,   Thompson  and  Morre  (1936) 
compared  a  group  of  chickens  which  was 
passing  oocysts  with  another  group  which 
was  not.    Over  a  period  of  11  months,  the 
positive  group  had  a  12. 1%  higher  mor- 
tality, while  the  negative  group  averaged 
0.  44  pounds  heavier  than  the  positive  one 
and  had  a  15.2%  higher  egg  production. 
Bressler  and  Gordeuk  (1951)  found,   in  a 
flock  of  Single  Comb  White  Leghorn  chick- 
ens which  had  survived  a  mortality  of 
8.  3%  due  to  cecal  coccidiosis,  that  weight 
gains  were  slightly  less  than  in  a  "control" 
group  fed  0.0125%  sulfaquinoxaline  con- 
tinuously which  had  not  suffered  an  out- 
break of  the  disease,  but  that  neither  egg 
production  nor  hatchability  were  impaired. 


EIMERIA  NECATRIX 
JOHNSON,   1930 

Host:     Chicken. 

Location:     The  first  and  second  gen- 
eration schizonts  are  found  in  the  small 
intestine  and  the  third  generation  schizonts, 
gametes  and  gametocytes  in  the  ceca. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  oblong 
ovoid,   12  to  29  by  11  to  24/1  with  a  mean 
of20byl7/i  (Becker  e/ aZ.  ,   1956).    The 
oocyst  wall  is  smooth  and  colorless,  with- 
out a  micropyle.     An  oocyst  polar  granule 
is  present.    An  oocyst  residuum  is  absent. 
The  sporocysts  are  elongate  ovoid,  with 
a  Stieda  body.    A  sporocyst  residuum  is 
absent.    The  sporulation  time  is  2  days 


(18  hours  at  29''  C  according  to  Edgar, 
1955). 

Life  Cycle:     Chickens  become  in- 
fected by  ingesting  sporulated  oocysts. 
When  the  sporozoites  emerge.   Van  Door- 
ninck  and  Becker  (1957)  found  that  they 
first  enter  the  epithelial  cells  of  the  villi 
in  the  small  intestine,   pass  thru  the 
epithelium  into  the  lamina  propria  or  core 
of  the  villus  and  migrate  toward  the  mus- 
cularis  mucosae.     Most  of  them  are  en- 
gulfed by  macrophages  en  route  and  are 
transported  by  them  to  the  epithelial  cells 
of  the  fundus.    The  macrophages  invade 
these  cells  and  appear  to  disintegrate 
during  or  after  the  invasion  process,   leav- 
ing the  sporozoites  unharmed.    These  then 
round  up  to  form  first  generation  schizonts. 

The  remainder  of  the  life  cycle  has 
been  studied  by  Johnson  (1930)  and  Tyz- 
zer,  Theiler  and  Jones  (1932).     Both  the 
first  and  second  generation  schizonts  are 
found  above  the  host  cell  nuclei  in  the 
epithelial  cells  of  the  gland  fundi.     The 
first  generation  merozoites  are  liberated 
2.  5  to  3  days  after  infection  and  enter  ad- 
jacent epithelial  cells.    The  second  gen- 
eration schizonts  are  relatively  large, 
measuring  39  to  66  by  33  to  54  fi  with  a 
mean  of  52  by  38  /n  .    Most  of  the  second 
generation  merozoites  are  liberated  5  to 
8  days  after  infection,  but  a  few  may  still 
be  liberated  as  long  as  23  days  after  in- 
fection.    They  measure  8  to  11  by  1.  5  to 
2.  0  /J  with  a  mean  of  9  by  2  /ii .     They  pass 
to  the  cecum,  where  they  penetrate  the 
epithelial  cells,  coming  to  lie  below  the 
host  cell  nuclei,  and  turn  into  third  gen- 
eration schizonts.     Most  of  them  are 
found  in  the  surface  epithelium,  but  some 
enter  the  glandular  epithelium.     Multiple 
infections  of  a  cell  with  3  or  4  schizonts 
may  occur.    These  third  generation  schi- 
zonts are  relatively  small  and  contain  only 
6  to  8  or  a  maximum  of  16  third  genera- 
tion merozoites.    It  is  not  certain  whether 
there  is  more  than  one  asexual  generation 
in  the  cecum. 

The  third  generation  and  some  of  the 
second  generation  merozoites  enter  other 
cecal  epithelial  cells  and  become  macro- 
gametes  or  microgametocytes.    These 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


205 


also  lie  below  the  host  cell  nuclei.     Micro- 
gametes  develop  from  the  microgameto- 
cytes,  fertilization  takes  place,  and 
oocysts  form  and  are  released.    The  pre- 
patent  period  is  7  days,  and  the  patent 
period  is  about  12  days. 

Brackett  and  Bliznick  (1952a)  reported 
that  the  number  of  oocysts  produced  by  E. 
necatrix  per  oocyst  fed  ranged  from  1  5  in 
a  group  of  chicks  infected  with  35,000 
oocysts  each  to  58,000  in  another  group  in 
which  the  infective  dose  was  50  oocysts. 

Pathogenesis:     Next  to  E.   teiiella, 
this  is  the  most  pathogenic  and  important 
species  of  chicken  coccidium.    Indeed, 
with  the  decrease  in  importance  of  E. 
tenella  due  to  the  use  of  coccidiostatic 
drugs,  E.  necatrix  has  come  to  the  fore 
in  many  areas  as  the  cause  of  more  losses 
than  E.  tenella. 

E.  necatrix  is  often  said  to  cause  a 
more  chronic  type  of  coccidiosis  than  E. 
tenella.     This  is  not  because  it  runs  a 
longer  course,  but  because  it  produces  so 
much  scar  tissue  in  the  small  intestine 
that  its  effects  are  more  lasting. 

The  pathogenesis  of  E.  necatrix  has 
been  studied  especially  by  Tyzzer,  Theiler 
and  Jones  (1932).    The  principal  lesions 
are  in  the  small  intestine,  the  middle 
third  of  which  is  most  seriously  affected. 
Small,  white,  opaque  foci  are  found  here 
by  the  fourth  day  after  infection.     They 
are  composed  of  second  generation  schi- 
zonts  developing  deep  in  the  mucosa. 
They  are  so  deep  that  they  can  be  seen 
thru  the  serosa  but  not  from  the  mucosal 
surface  of  the  intestine.     They  are  seldom 
more  than  a  millimeter  in  diameter,  but 
may  coalesce  and  thus  appear  larger. 
Severe  hemorrhage  may  appear  on  the 
5th  or  6th  days.     The  small  intestine  may 
be  markedly  swollen  and  filled  with  clotted 
or  unclotted  blood.    Its  wall  is  greatly 
thickened,  dull  red,  and  many  petechial 
hemorrhages  appear  in  the  white,  opaque 
foci  which  by  now  contain  second  genera- 
tion merozoites.     The  gut  wall  may  lose 
contractility,  become  friable  and  even 
appear  gangrenous.    The  epithelium  may 
slough,  and  by  the  end  of  the  6th  day  a 


network  of  fibrin  containing  mononuclear 
cells  appears  in  the  destroyed  areas. 
This  is  later  replaced  by  connective  tissue, 
and  permanent  scarring  results  which  in- 
terferes with  intestinal  absorption. 

There  is  less  anemia  than  in  E. 
tenella  infections.    Using  the  microhema- 
tocrit  technic,  Joyner  and  Davies  (1960) 
found  that  the  packed  red  cell  volume  de- 
creased from  28%  to  23%  seven  days  after 
experimental  infection  with  20,  000  oocysts, 
and  to  25%)  after  infection  with  10,  000 
oocysts,  but  that  there  was  no  significant 
decrease  after  infection  with  1000  oocysts. 
The  hematocrit  levels  had  not  returned  to 
the  original  level  12  days  after  infection. 

The  ceca  are  not  seriously  affected. 
They  may  be  contracted  and  their  contents 
may  be  dehydrated. 

Death  usually  occurs  5  to  7  days  after 
infection.     Many  of  the  birds  which  recover 
remain  unthrifty  and  emaciated.    The 
after-effects  of  this  type  of  coccidiosis  are 
often  so  long- lasting  that  it  is  not  worth- 
while to  keep  birds  which  have  recovered 
from  severe  attacks. 

Brackett  and  Bliznick  (1950,   1952) 
found  that  inoculation  with  25,000  to 
50,000  oocysts  (a  relatively  small  number) 
caused  a  high  degree  of  mortality  in  young 
chickens.     Following  inoculation  with  equal 
numbers  of  oocysts,  young  birds  are  more 
severely  affected  than  older  ones,  but  if 
the  inocula  are  calculated  on  a  weight  basis, 
older  birds  may  be  more  severely  affected 
than  younger  ones.    In  3-week-old  chicks, 
25,  000  oocysts  caused  a  mortality  of  87%, 
while  in  4-week-old  chicks,   18,000,  37,000, 
75,000  and  150,000  oocysts  caused  mor- 
talities of  8,  75,  85  and  61%,  respectively. 

EIMERIA  BRUNETTI 
LEVINE,   1942 

Host:     Chicken. 

Location:     First  generation  schizonts 
occur  thruout  the  small  intestine.    Second 
generation  schizonts,  gametes  and  gameto- 
cytes  occur  in  the  posterior  small  intes- 
tine, rectum,  ceca  and  cloaca. 


206 


THE  TEIOSPORASIDA   AND  THE  COCCIDIA   PROPER 


Geographic  Distribution:       North 
America. 


Prevalence:     Uncommon. 

Morphology:      P.   P.   Levine  (1942) 
described  this  species,  and  Becker,   Zim- 
mermann  and  Pattillo  (1955)  made  a  bio- 
metric  study  of  its  oocysts.     The  oocysts 
are  ovoid,  smooth,  14  to  34  by  12  to  26 /j. 
with  a  mean  of  23  by  20 /i.    A  micropyle 
is  absent.     An  oocyst  polar  granule  is 
present.    An  oocyst  residuum  is  absent. 
The  sporocysts  are  elongate  ovoid,  about 
13  by  7.  5(1,  with  a  Stieda  body.     A  sporo- 
cyst  residuum  is  present.     The  sporulation 
time  is  1  to  2  days.     Edgar  (1955)  found 
infective  oocysts  as  early  as  18  hours  at 
24"  C. 

Life  Cycle:     The  life  cycle  of  this 
species  was  described  by  Boles  and 
Becker  (1954).    The  sporozoites  are  liber- 
ated in  the  intestine  and  invade  the  epithel- 
ial cells  of  the  villi.     They  round  up  to 
become  first  generation  schizonts,  which 
lie  below  the  host  cell  nuclei  on  the  sides 
of  the  villi  of  the  upper,   middle  and  lower 
small  intestines.     They  are  present  51  to 
76  hours  after  infection,  measure  30  by 
20j^L,  and  contain  approximately  200  first 
generation  merozoites  when  mature. 
These  invade  other  cells  in  the  posterior 
small  intestine,   rectum,  tubular  part  of 
the  ceca  and  cloaca.    They  are  found  pri- 
marily at  the  tips  of  the  villi,  and  usually 
lie  below  the  host  cell  nuclei.     They  turn 
into  second  generation  schizonts,  which 
are  present  4  days  after  infection.    These 
average  30  by  16/i  and  contain  50  to  60 
merozoites.    Small  schizonts  about  10  by 
9/j.  were  also  seen  on  the  4th  day,  but 
their  significance  was  not  determined. 

The  second  generation  merozoites  in- 
vade fresh  cells  in  the  lower  small  intes- 
tine, ceca,  rectum  and  cloaca  and  turn 
into  sexual  stages.    These  first  appear  on 
the  5th  day  and  lie  at  the  tips  and  sides  of 
the  villi,  either  above  the  host  cell  nuclei 
or  on  the  basement  membrane.     The  micro- 
gametocytes  have  a  multicentric  appear- 
ance, and  are  larger  than  the  macroga- 
metes,  which  measure  about  25  by  22|:i. 
The  macrogametes  contain  eosinophilic 


plastic  granules  which  later  coalesce  and 
form  the  oocyst  wall. 

The  prepatent  period  is  5  days. 

Brackett  and  Bliznick  (1952)  found 
that  E.  brunetti  could  produce  a  maximum 
of  400,000  oocysts  per  oocyst  fed.     This 
figure  was  obtained  in  2-  to  3-week-old 
chickens  fed  50  oocysts  each.    With  larger 
inocula,   relatively  fewer  oocysts  were  ob- 
tained.   With  inocula  of  250,   1250,   6250, 
20,  000  and  40,  000  oocysts,   respectively, 
150,000,  26,000,   7000,   800  and  400  oocysts 
were  produced  per  oocyst  fed. 

Pathogenesis:     E.   briinelli  is  mark- 
edly pathogenic,  but  its  effects  depend  upon 
the  degree  of  infection.    In  light  infections, 
no  gross  lesions  may  be  seen.    In  heavier 
infections,   Levine  (1942)  found  that  the  gut 
wall  becomes  thickened  and  a  pink  or  blood- 
tinged  catarrhal  exudate  appears  4  or  5 
days  after  experimental  infection:  the  drop- 
pings are  quite  fluid  and  contain  blood- 
tinged  mucus  and  many  mucus  casts.     The 
birds  become  somewhat  depressed.     These 
signs  continue  for  5  days  and  then  subside 
if  the  birds  recover. 

In  early  or  light  infections,   hemor- 
rhagic, ladder-like  streaks  are  present  on 
the  mucosa  of  the  lower  intestine  and  rec- 
tum.   In  heavy  infections,  a  characteristic 
necrotic  enteritis  appears.    It  may  involve 
the  entire  intestinal  tract,  but  is  more  often 
found  in  the  lower  small  intestine,  large 
intestine  and  tubular  part  of  the  ceca.    A 
patchy  or  continuous,  dry,  caseous  necrotic 
membrane  may  line  the  intestine,   and  the 
intestine  may  be  filled  with  sloughed,  ne- 
crotic material.    Circumscribed  white 
patches  may  be  visible  thru  the  serosa, 
and  there  may  even  be  intestinal  perfora- 
tion with  resultant  peritonitis. 

Boles  and  Becker  (1954)  did  not  ob- 
serve the  extensive  coagulation  necrosis 
described  by  Levine  (1942)  in  their  experi- 
mentally infected  chicks,  but  the  other 
lesions  were  similar  to  those  of  his  moder- 
ately infected  birds.    The  birds  became 
listless  82  hours  after  infection,  and  pe- 
techial hemorrhages  were  found,  mostly 
in  the  lower  small  intestine  but  also  in  the 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


207 


middle  and  upper  small  intestine.     These 
became  more  severe  the  next  day  but  had 
disappeared  from  the  upper  and  middle 
intestine.     The  lower  small  intestine  and 
large  intestine  were  hyperemic  and  hem- 
orrhagic, there  was  epithelial  sloughing, 
and  the  intestinal  contents  were  watery 
and  blood-tinged.    The  tubular  part  of  the 
ceca  was  involved,  and  the  dilated  portion 
was  plugged  with  dehydrated  material.    The 
epithelial  denudation  was  most  probably 
caused  by  the  asexual  stages,  and  was 
most  prominent  on  the  4th  day.    Signs  of 
illness  continued  until  the  6th  day. 

Field  outbreaks  of  the  disease  were 
studied  by  Levine  (1943).     The  disease 
occurs  most  commonly  in  chicks  4  to  9 
weeks  old.    The  mortality  is  high,  and 
typical  necrotic  lesions  are  present.    We 
have  seen  the  same  condition  in  field  out- 
breaks in  Illinois. 


EIMERIA  ACERVULINA 
TYZZER.    1929 

Host:     Chicken. 

Location:     Anterior  small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  ovoid, 
smooth,   12  to  23  by  9  to  17  jii  with  a  mean 
of  16  by  13 p..     A  micropyle  is  absent.    An 
oocyst  polar  granule  is  present.    An 
oocyst  residuum  is  absent.     The  sporocysts 
are  ovoid,  with  a  Stieda  body  but  without  a 
sporocyst  residuum.     The  sporulation 
time  is  1  day.     Edgar  (1955)  found  that  the 
minimum  sporulation  time  for  this  species 
at  28°  C  was  17  hours. 

Life  Cycle:     The  life  cycle  of  this 
species  was  described  by  Tyzzer  (1929). 
The  schizonts  are  found  in  the  epithelial 
cells  of  the  villi  of  the  anterior  small  in- 
testine, where  they  lie  above  the  host  cell 
nuclei.    The  gland  cells  may  also  be  in- 
vaded.   Sometimes  more  than  one  parasite 
is  found  in  a  cell.    The  schizonts  produce 
16  to  32  merozoites  which  measure  about 


6  by  O.SjLL.  There  are  at  least  2  and  pos- 
sibly more  asexual  generations.  Asexual 
reproduction  lasts  longer  than  in  E.  teiiella. 


The  sexual  stages  occur  above  the 
host  cell  nuclei  in  the  epithelial  cells  of 
the  villi  and  to  a  lesser  extent  in  the  gland 
cells  in  the  anterior  small  intestine.     They 
first  appear  4  days  after  infection.     The 
microgametocytes  are  relatively  small, 
measuring  11  by  9ju. 

The  prepatent  period  is  4  days,  and 
oocysts  continue  to  be  produced  for  rela- 
tively longer  than  with  some  other  chicken 
coccidia. 

Brackett  and  Bliznick  (1950)  found 
that  the  maximum  number  of  oocysts  pro- 
duced per  oocyst  fed  in  their  studies  was 
72,  000.     This  occurred  in  a  group  of  3- 
week-old  birds  fed  2000  oocysts  each.    In 
another  experiment  in  which  similar  birds 
were  fed  the  same  number  of  oocysts, 
only  35,000  oocysts  were  produced  per 
oocyst  fed.    Oocyst  production  was  lower 
with  both  larger  and  smaller  inocula. 
Following  inoculation  with  200,   10,000  and 
20,000  oocysts,   respectively,  9000,35,000 
and  7,  600  oocysts  were  produced  per  oocyst 
fed. 

Pathogenesis:     E.  acerindina  is  gen- 
erally considered  only  slightly  pathogenic, 
but  very  large  inocula  may  cause  severe 
signs  and  even  death.    Generally,  however, 
this  species  causes  only  a  temporary  set- 
back.   Dickinson  (1941)  found  that  admin- 
istration of  as  many  as  25  million  oocysts 
to  pullets  produced  only  a  temporary  drop 
in  weight  and  temporary  cessation  of  egg 
production.     Between  4  and  9  days  after 
infection,  the  birds  were  droopy,  ate  rel- 
atively little  and  passed  slimy,  mucoid 
feces.     Peterson  (1949)  reported  losses 
from  E.  acerindina  infection  in  the  Pacific 
Northwest  in  older  birds  3  to  4  weeks  after 
they  had  been  brought  in  off  the  range  and 
placed  in  houses.     The  birds  lost  weight, 
egg  production  ceased,  the  combs  shriveled 
and  keratin  pigment  disappeared.    There 
were  few  if  any  deaths.    After  about  6 
weeks  the  birds  recovered  and  egg  produc- 
tion returned  to  normal. 


208 


THE  TELOSPORASIDA  AND  THE  COCCIDLA  PROPER 


Brackett  and  Bliznick  (1950)  found 
that  inoculation  with  500,000  oocysts  re- 
duced weight  gains  of  2-week-old  chicks. 
Moynihan  (1950)  obtained  similar  results. 
Becker  (1959)  found  that  300,000  oocysts 
produced  only  loss  of  appetite  for  2  or  3 
days  and  watery  feces  on  the  third  day 
after  infection  in  White  Leghorn  chicks. 
Morehouse  and  McGuire  (1958)  found  that 
infection  of  chicks  with  100,  000  oocysts 
retarded  weight  gains  somewhat  but  did 
not  affect  the  final  weight.     Larger  inocula 
produced  increasingly  severe  effects. 
Single  and  multiple  doses  of  5  million  or 
more  oocysts  caused  6  to  75%  mortality. 

The  lesions  produced  by  B.acervulina 
are  not  as  marked  as  with  E.  necatrix. 
The  intestine  may  be  thickened  and  a 
catarrhal  exudate  may  be  present,  but 
hemorrhage  is  rare.    The  maturing 
oocysts  lie  massed  in  limited  areas,  and 
form  whitish  or  grey  spots  or  streaks 
running  transversely  in  the  intestinal 
mucosa.    In  heavy  infections  the  entire 
mucosa  may  be  involved  and  may  appear 
greyish,  mottled  and  somewhat  thickened. 
Morehouse  and  McGuire  (1958)  described 
a  severe  inflammatory  reaction  in  chicks 
infected  with  1  to  20  million  oocysts.    The 
intestine  was  edematous  and  thickened, 
with  extensive  vasodilation  and  marked 
reddening  of  the  mucosa,  and  there  was 
also  degeneration  or  necrosis  and  slough- 
ing of  the  intestinal  epithelium. 


EIMERIA  MAXIMA 
TYZZER,   1929 

Host:     Chicken. 

Location:     Middle  and  posterior 
small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  ovoid, 
smooth  or  somewhat  roughened,  yellowish, 
21  to  42  by  16  to  30  ji  with  a  mean  of  29  by 
23  fx.    A  micropyle  is  absent.     An  oocyst 
polar  granule  is  present.    An  oocyst  resi- 
duum is  absent.    The  sporocysts  are 


elongate  ovoid,   15  to  19  by  8  to  9 /i ,  with 
a  Stieda  body.     A  sporocyst  residuum  is 
absent.     The  sporozoites  are  19  by  4ji, 
with  a  conspicuous  retractile  globule 
(Long,   1959).     The  sporulation  time  is  2 
days.     Edgar  (1955)  and  Long  (1959) found 
some  infective  oocysts  as  early  as  30 
hours  at  28'  C. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  by  Tyzzer  (1929), 
Scholtyseck  (1959)  and  Long  (1959),  among 
others.     The  schizonts  are  found  above  the 
host  cell  nuclei  or  occasionally  beside  them 
in  the  epithelial  cells  of  the  tips  of  the  villi 
of  the  duodenum  and  upper  ileum.     There 
are  2  generations  of  schizonts,  both  of 
which  are  relatively  small,   measuring 
about  10  by  8 p.;  they  produce  only  about  8 
to  16  merozoites  each.    Schizonts  may  be 
present  thru  the  5th  day.     The  second  gen- 
eration merozoites  enter  new  epithelial 
cells,  where  they  round  up  and  enter  the 
sexual  phase  of  the  life  cycle. 

The  sexual  stages  are  found  beneath 
the  host  cell  nuclei.    As  they  become 
larger,  the  host  cells  are  displaced  toward 
the  center  of  the  villus  and  come  to  lie  in 
its  interior.    The  mature  microgametoc3^es 
measure  30  to  39  by  22  to  33  jj.  and  form  a 
large  number  of  biflagellate  microgametes. 
The  macrogametes  are  somewhat  smaller, 
averaging  19  by  15fj,  (Long,   1959).     After 
fertilization,  they  lay  down  an  oocyst  wall, 
break  out  of  the  villus  and  are  passed  in 
the  feces.     The  prepatent  period  is  5  to  6 
days,  and  the  patent  period  is  only  a  few 
days. 

Brackett  and  Bliznick  (1950,   1952) 
reported  that  the  maximum  number  of 
oocysts  produced  per  oocyst  fed  in  their 
experiments  was  12,000.    In  a  series  of 
3-week-old  chicks,  they  found  that  11,500, 
2250  and  940  to  2900  oocysts  were  pro- 
duced per  oocyst  fed  when  the  inoculating 
doses  were  200,  2000  and  10,000  oocysts, 
respectively. 

Long  (1959)  found  that  the  number  of 
oocysts  produced  per  oocyst  fed  varied 
with  the  age  of  the  birds  and  the  inoculum. 
With  an  inoculum  of  10,000  oocysts  it 
averaged  128,  33,  176,  448,  1049  and 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


209 


3294,   respectively,  in  chicks  3,   7,   14, 
21,  28  and  42  days  old,  while  with  an  in- 
oculum of  80,000  oocysts  it  was  9,   31  and 
169,  respectively  in  chicks  7,   14  and  21 
days  old. 

Pathogenesis:     E.  maxima  is  slightly 
to  moderately  pathogenic.     Tyzzer  (1929), 
Brackett  and  Bliznick  (1950),  Scholtyseck 
(1959)  and  Long  (1959)  studied  its  effects 
on  chickens.    The  asexual  stages  cause 
relatively  little  damage,  the  most  serious 
effects  being  due  to  the  sexual  stages. 
Brackett  and  Bliznick  (1950)  observed  a 
mortality  of  35%  in  one  group  of  young 
chicks  infected  with  500,000  oocysts  each, 
but  there  were  no  deaths  in  another  group. 
The  survivors  lost  some  weight  and  then 
gained  less  than  the  controls  for  a  time, 
but  infection  with  100,  000  oocysts  had  no 
significant  effect  on  weight  gains.     Long 
(1959)  observed  no  deaths  in  a  group  of 
6-week-old  chicks  infected  with  500,  000 
oocysts  each  or  in  three  17-day-old  chicks 
infected  with  1  million  oocysts  each,  altho 
diarrhea  was  present  and  the  infected 
birds  gained  less  than  the  controls.    Im- 
munity is  quickly  produced. 

Berg,   Hamilton  and  Bearse  (1951) 
found  that  inoculation  of  White  Leghorn 
laying  pullets  with  8000  oocysts  each  pro- 
duced a  mild  infection  and  temporary 
cessation  of  egg-laying. 

The  principal  lesions  are  hemorrhages 
in  the  small  intestine.    The  intestinal 
muscles  lose  their  tone,  and  the  intestine 
becomes  flaccid  and  dilated,  with  a  some- 
what thickened  wall.    Short,  fine,  hair- 
like hemorrhages  in  the  intestinal  wall  are 
sometimes  present.    There  is  a  catarrhal 
enteritis  and  the  intestinal  contents  are 
viscid  and  mucoid,  greyish,  brownish, 
orange  or  pinkish,  occasionally  but  not 
usually  with  flecks  of  blood. 

Birds  which  recover  soon  return  to 
normal. 


EIMERIA  MITIS 
TYZZER,   1929 

Host:     Chicken. 


Location:     Anterior  small  intestine, 
occasionally  middle  and  lower  small  intes- 
tine or  even  tubular  part  of  ceca. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  sub- 
spherical,  smooth,  colorless,   10  to  21  by 
9  to  18|u  with  a  mean  of  16  by  13 /i .    A 
micropyle  is  absent.     An  oocyst  polar 
granule  is  present.    An  oocyst  residuum 
is  absent.     The  sporocysts  are  ovoid,   10 
by  6(1,  with  a  Stieda  body,  but  without  a 
sporocyst  residuum.     The  sporulation  time 
is  2  days.     Edgar  (1955)  found  some  infec- 
tive oocysts  as  early  as  18  hours  at  29°  C. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  by  Tyzzer  (1929) 
and  Joyner  (1958),  the  latter  using  a  strain 
derived  from  a  single  oocyst.     The  endo- 
genous stages  occur  in  the  epithelial  cells 
of  the  villi  and  occasionally  in  the  glands. 
They  lie  against  the  host  cell  nuclei,  and 
below  them  more  often  than  above  accord- 
ing to  Tyzzer.    However,  Joyner  stated 
that  the  schizonts  are  nearly  always  super- 
ficial; he  illustrated  the  sexual  stages  as 
below  the  host  cell  nuclei.    The  schizonts 
produce  6  to  24  or  rarely  30  merozoites, 
but  the  number  of  schizont  generations  is 
not  known.    The  merozoites  are  crescent- 
shaped,  with  blunt  ends,  and  measure 
about  5  by  1 .  5  /i . 

The  microgametocytes  are  about  9  to 
14  jj,  long  and  the  macrogametes  are  some- 
what larger.     In  contrast  to  most  other 
coccidian  species,  in  which  development 
following  a  single  inoculum  is  quite  syn- 
chronous, both  asexual  and  sexual  stages 
occur  together.    The  prepatent  period  is 
4  to  5  days,  and  the  patent  period  10  days 
(Joyner,   1958). 

Joyner  (1958)  found  that  chicks  in- 
fected with  1000  oocysts  produced  61,  709 
oocysts  per  oocyst  fed,  while  chicks  fed 
100,000  oocysts  produced  2253  oocysts  per 
oocyst  fed. 

Pathogenesis:     This  species  is 
slightly  pathogenic,  but  is  unlikely  to  be 


210 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


of  pathological  significance  under  normal 
field  conditions.     Tyzzer  (1929)  observed 
neither  signs  nor  gross  lesions  in  young 
chickens  given  tremendous  and  repeated 
doses  of  sporulated  oocysts.    Becker 
(1959)  found  neither  lesions  nor  diarrhea 
in  infected  chickens.    Joyner  (1958) found 
that  weight  gains  of  6-  to  26-day-old  birds 
fed  500,000  oocysts  were  reduced,  while 
38%  of  29  6-day-old  chicks  died  after 
being  fed  2.  5  million  oocysts. 


praecox  is  probably  no  more  pathogenic 
than  E.  mitis. 


EIMERIA  HAGANI 
LEVINE,   1938 


Host:     Chicken. 


Location:     Anterior  half  of  small  in- 


testine. 


EIMERIA   PRAECOX 
JOHNSON,    1930 

Host:     Chicken. 

Location:     Upper  third  of  small  in- 
testine. 

Geographic  Distribution:      Probably 
worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  ovoid, 
smooth,  colorless,   20  to  25  by  16  to  20(1 
with  a  mean  of  21  by  17 /i.    A  micropyle 
is  absent.    An  oocyst  polar  granule  is 
present.     Oocyst  and  sporocyst  residua 
are  absent.     The  sporulation  time  is  2 
days. 

Life  Cycle:     Tyzzer,  Theiler  and 
Jones  (1932)  studied  the  life  cycle  of  this 
species.    The  endogenous  stages  occur  in 
the  epithelial  cells  of  the  villi,  usually 
along  the  sides  of  the  villi  and  below  the 
host  cell  nuclei.     There  are  2  generations 
of  schizonts,  the  second  of  which  appears 
as  early  as  32  hours  after  infection. 
Later  development  is  irregular,  both  sex- 
ual and  asexual  stages  being  seen  together. 
The  prepatent  period  is  4  days,  and  the 
patent  period  is  short,   4  days  or  a  little 
more  in  the  absence  of  reinfection. 

Pathogenesis:     This  species  is  essen- 
tially non- pathogenic.    Tyzzer,   Theiler 
and  Jones  (1932)  were  unable  to  cause 
death  with  heavy  doses  of  oocysts,  altho 
they  did  observe  a  mucous  cast  containing 
large  numbers  of  oocysts  at  the  end  of  the 
infection.    Becker  (1959)  found  that  E. 


Geographic  Distribution: 
America,  India. 


North 


Prevalence:     Rare.    This  species  has 
apparently  been  reported  in  the  United 
States  only  by  P.   P.   Levine  (1938)  in  New 
York  and  Edgar  (1955)  in  Alabama.    Gill 
(1954a)  found  it  in  2.  5%  of  120  chickens  in 
India. 

Morphology:     The  oocysts  are  broadly 
ovoid,  smooth,   16  to  21  by  14  to  19/i  with 
a  mean  of  19  by  18  fj,  (18  by  16.  5  jm  accord- 
ing to  Edgar,   1955).    A  micropyle  is  ap- 
parently absent.     An  oocyst  polar  granule 
is  present.    No  other  morphological  data 
are  known;  this  species  was  differentiated 
from  other  chicken  coccidia  by  cross-im- 
munity tests.     The  sporulation  time  is  1 
to  2  days.       Edgar  (1955)  found  sporulated 
oocysts  as  early  as  18  hours  at  29"  C. 

Life  Cycle:  Unknown.  The  prepatent 
period  is  7  days  according  to  Levine  (1938) 
or  almost  6  days  according  to  Edgar  (1955). 

Pathogenesis:     This  species  is  only 
slightly  pathogenic.     Levine  (1938)  ob- 
served pin-head  size  hemorrhages  and 
catarrhal  inflammation  in  the  anterior 
half  of  the  small  intestine.     There  were 
also  a  few  hemorrhages  in  the  lower  small 
intestine.     Later,  however,   Levine  (1942a) 
referred  to  this  species  as  non- pathogenic, 
stating  that  300,  000  oocysts  had  no  effect 
on  experimentally  infected  birds. 


COCCIDIOSIS   IN   CHICKENS 

Epidemiology:     Infections  with  a 
single  species  of  coccidium  are  rare,  and 
mixed  infections  are  the  rule.    Eimeria 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


211 


Fig.  27.      Morphology  and  developmental  stages  of  species  of  Eiiiici'ki  from  the  chukcn. 
1-4.    Stages  in  development  of  oocysts  of  Eiiiicyia  IcnclUi.     5-7.     Stages  in 
development  of  oocysts  of  Eiiueria  initio.    8-9.    Stages  in  development  of 
oocysts  ol  Eiuieria  aceyvnlina.     10-13.     Stages  in  development  of  oocysts  of 
Eiiucria  maxima.     14-17.    Stages  in  development  of  oocysts  of  Eiiiicna 
iiccalyix.     18.     Developmental  stages  in  cecal  epithelium  7  to  9  days  after  in- 
fection,   oo  =  oocyst,     sch  =  third  generation  schizont.     nier  =  third  generation 
nierozoite.     mi  =  microgametocyte.     ma  =  macrogamete.     (From  Tyzzer,   1929 
in  the  Aincyicaii  Junyiial  uj  Hygiene,  published  by  the  Johns  Hopkins  Press). 


tenella  is  the  most  pathogenic  and  impor- 
tant species.    In  recent  years,   however, 
control  of  this  species  with  coccidiostats 
has  revealed  more  and  more  coccidiosis 
due  to  E.  )iccalri.x.     The  other  species 
may  contribute  to  the  total  picture.    E. 
brunelli  is  markedly  pathogenic  but  un- 
common.   E.  niaxiiiia  and  E.  acerviilina 
are  slightly  to  moderately  pathogenic. 
Both  are  conunon.     E.  )iiitis  and  E. 
praecox  are  common  but  non- pathogenic. 
E.  hagani  is  rare  and  only  slightly  if  at 
all  pathogenic.     Weiiyonella  galliiiae  is 
rare  but  moderately  pathogenic;  it  has 


been  found  so  far  only  in  India.     Crypto- 
sporidiiiiii  tyzzeri  is  rare  and  non-patho- 
genic,   laospora  gallinae  is  rare  if  it  is  a 
chicken  parasite  at  all,  and  is  presumably 
non- pathogenic. 

Coccidiosis  is  primarily  a  disease  of 
young  birds.     Older  birds  are  carriers. 
Birds  become  infected  by  ingesting  oocysts 
along  with  their  food  or  water.     Under 
farm  conditions,  and  even  in  the  laboratory 
unless  extreme  precautions  are  taken,  it 
is  practically  impossible  to  avoid  exposure 
to  at  least  a  few  oocysts. 


212 


THE  TELOSPORASIDA   AND  THE  COCCIDL\    PROPER 


^  "    0* 


',9-rTTJ 


mmlff^mS^m 


iLiSjj-i 


3 


Fig.  28.      Location  of  avian  coccidia  in  intestinal  epithelium  of  chicken.     1.    Cryplo- 

sporidium  tyzzeri.    2.    Eimeria  aceri'idina.     3.    Eiineria  iiiilis.     4.    Eimeria 
maxima.    5.   Eimeria  tenella.     (From  Tyzzer,   1929  in  the  American  Journal 
of  Hygiene,  published  by  the  Johns  Hopkins  Press) 


The  disease  picture  depends  upon  the 
number  of  oocysts  of  each  species  which 
the  birds  ingest.    If  they  get  only  a  few, 
there  are  no  signs,  and  repeated  infec- 
tions produce  immunity  without  disease. 
If  they  get  more,  the  disease  may  be  mild 
and  the  birds  will  become  immune.     Only 
if  they  get  a  large  number  of  oocysts  do 
severe  disease  and  death  result. 

Crowding  and  lack  of  sanitation  greatly 
increase  the  disease  hazard.    As  the 
oocysts  accumulate,  the  birds  receive 
heavier  and  heavier  exposures,  and  the 
disease  becomes  increasingly  severe  in 
each  successive  batch  of  birds  placed  in 
contaminated  surroundings. 


Immunity:      Coccidiosis  is  a  self- 
limiting  disease,  and  birds  which  have  re- 
covered become  immune.    The  speed  with 
which  immunity  develops  depends  upon  the 
species  of  Euneria  and  on  the  intensity  and 
frequency  of  infection.     Immunity  develops 
rapidly  following  infections  with  E.  »iax- 
ima,  E.  praecox  and  probably  E.  hagani, 
somewhat  more  slowly  following  infections 
■with  E.  tenella    and  E.   briiiietli,   and  is  de- 
layed following  infections  with  E.  mills, 
E.  acervulina  and£.  necatrix. 

Immunity  is  species-specific.    Chick- 
ens which  have  become  immune  to  one 
species  are  susceptible  to  all  the  others. 
This  fact  makes  it  possible  to  differentiate 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


213 


Fig.  29.      Location  of  chicken  coccidia  in  regions  of  the  intestinal  tract.     A.    Eiiiivrui 
tenella.    B.   E.  mitis.     C.   E.  acervuliiia.     D.    E.  niaxiiiia.     E.   E.  i/ccalrix. 
F.    E.   brnnetti.     (A-D  after  Tyzzer,   1929;  E  after  Tyzzer,  Theiler  and  Jones, 
1932;  F  after  Boles  and  Becker,   1954) 


between  species  by  cross-immunity  stud- 
ies, and  indeed  it  was  by  means  of  such 
studies  that  Levine  (1938),  for  instance, 
was  able  to  show  that  E.  hagani  was  a 
valid  species. 

Immunity  against  coccidia  is  seldom 
solid.     Birds  which  have  recovered  may 
be  reinfected,  but  such  infections  are 
light  and  do  not  cause  disease.     Carriers 
are  extremely  common  and  are  a  source 
of  infection  for  other  birds.     Thus,   Levine 
(1940)  found  E.  mitis,  E.  acervnlina  or 
both  in  53%,  E.  praecox  in  33%,   E.  max- 
ima in  28%,  E.  necatrix  in  38%  and£. 
tenella  in  23%  of  39  pullets  8  months  or 
more  old,  but  only  8%  of  them  had  gross 
lesions. 

Heredity  is  a  factor  in  resistance  to 
coccidiosis.     Herrick  (1934)  found  that 
chicks  from  resistant  parents  were  about 
100%  more  resistant  to  E.  tenella  than 


unselected  chicks.     Champion  (1954)  and 
Rosenberg,  Alicata  and  Palafox  (1954) 
established  E.  teiiella-res\sia.nt  and  sus- 
ceptible lines  of  chickens  by  selective 
breeding.     They  found  that  sex  linkage, 
passive  transfer  of  immunity  thru  the  egg 
and  cytoplasmic  inheritance  did  not  play  a 
significant  part  in  resistance  and  suscep- 
tibility.    Champion  considered  that  they 
were  controlled  in  large  part  by  non-dom- 
inant, multiple  genetic  factors  which  pre- 
sumably act  additively.     Rosenberg  et  al. 
also  thought  that  the  factor  or  factors  for 
resistance  or  susceptibility  did  not  show 
marked  dominance. 

Immunity  in  older  birds  is  due  mostly 
to  previous  infection.     The  birds  are  ex- 
posed repeatedly  and  almost  continuously, 
and  their  immunity  is  continually  being 
reinforced.     Coccidiasis  is  thus  extremely 
common- -and  indeed  normal  under  natural 
conditions- -while  coccidiosis  is  the  result 


214 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


of  imbalance  between  infection  rate  and 
resistance.    Actually,  the  best  type  of  en- 
vironment to  control  coccidiosis  is  one  in 
which  the  chickens  become  infected  lightly 
enough  to  develop  an  immunity  without 
suffering  any  disease. 

Many  workers  have  studied  the  devel- 
opment of  immunity  to  coccidiosis  (Walet- 
zky  and  Hughes,   1949;  Brackett  and 
Bliznick,   1950).     Most  of  this  research 
has  been  done  with  E.  lenella.     Farr  (1943) 
immunized  chickens  with  1000  oocysts 
daily  for  15  days  or  with  3  doses  of  1000, 
5000  and  9000  oocysts  given  5  days  apart. 
She  also  carried  out  5  similar  experiments 
with  differing  numbers  of  oocysts,  all  of 
which  showed  that  repeated  small  doses  of 
E.   lenella  oocysts  would  produce  immun- 
ity.    Horton-Smith  (1949),  Waletzky  and 
Hughes  (1949)  and  Gordeuk,  Dressier  and 
Glantz  (1951)  found  that  single  doses  of 
oocysts  would  also  produce  immunity,  and 
that  the  degree  of  protection  was  propor- 
tional to  the  intensity  of  the  initial  infec- 
tion.    Babcock  and  Dickinson  (1954)  found 
that  a  total  of  1600  sporulated  oocysts, 
given  either  in  one  or  several  doses, 
would  produce  practical  immunity  that 
withstood  severe  challenge.     The  number 
of  individual  doses  required  to  make  the 
total  did  not  materially  affect  the  immun- 
ity produced.    It  took  4  days  longer  for 
immunity  to  result  following  exposure  to 
1050  sporulated  oocysts  than  to  2125. 
Gordeuk,   Bressler  and  Glantz  (1951) found 
that  day-old  chicks  could  develop  a  certain 
degree  of  immunity.     They  found,  too,  that 
feeding  the  oocysts  in  the  mash  resulted 
in  higher  mortality  than  when  a  similar 
dose  was  given  by  mouth. 

Many  workers  have  shown  that  immun- 
ity will  develop  against  coccidiosis  in  birds 
on  suppressive  therapy  (Waletzky  and 
Hughes,   1949;  Johnson,  Mussell  and  Diet- 
zler,   1949,   1949a;  Grumbles  el  at.  , 
1949;  Bankowski,   1950;  Kendall  and  McCul- 
lough,   1952).     The  drugs  are  ineffective 
against  the  sporozoites  or  first  generation 
schizonts,  at  least  in  the  concentrations 
used,  but  they  do  kill  the  merozoites  or 
later  stages.    The  coccidia  are  thus  able 
to  invade  the  host  tissues  and  stimulate 
the  development  of  immunity,  but  are 


killed  before  they  can  multiply  enough 
to  harm  the  host. 

A  number  of  workers  have  attempted 
to  produce  immunity  by  infecting  birds 
with  oocysts  attenuated  in  different  ways. 
Jankiewicz  and  Scofield  (1934)  heated  the 
oocysts  to  46"  C  for  15  minutes  before 
sporulation,  and  found  that  when  they  were 
then  sporulated  and  fed  to  chickens,  they 
stimulated  the  production  of  immunity 
with  a  minimum  of  injury.    Waxier  (1941) 
produced  mild  infections  with  oocysts 
irradiated  with  9000  r  of  x-rays.     Follow- 
ing recovery,  the  chicks  were  almost  as 
resistant  as  those  which  had  had  a  severe 
attack  after  infection  with  normal  oocysts. 
Uricchio  (1953)  produced  marked  immunity 
by  feeding  chicks  100,  000  oocysts  which 
had  been  held  at  -5^  C  for  5  days,  and  a 
lesser  degree  of  immunity  with  oocysts 
which  had  been  heated  at  45''  C  for  12 
hou  rs . 

It  is  well  known  that  cultures  slowly 
lose  their  infectivity  upon  storage.     Bab- 
cock and  Dickinson  (1954),  for  example, 
observed  reduced  pathogenicity  in  a  culture 
of  E.  tenella  after  storage  for  236  days, 
and  reduced  immunogenicity  at  344  days. 
Using  a  standard  immunizing  procedure 
in  which  600  oocysts  were  fed  the  first 
day  and  1000  the  second,  they  found  that 
it  took  3  days  to  produce  immunity  with  a 
culture  less  than  150  days  old  and  6  days 
with  a  culture  more  than  300  days  old. 

There  is  an  unanswered  question 
whether  such  treatments  produce  true  at- 
tenuation or  whether  the  observed  results 
are  due  simply  to  the  death  of  some  of  the 
oocysts.    Invasion  must  take  place  for  im- 
munity to  result,  and  attempts  to  immu- 
nize birds  with  killed  antigens  have  not 
succeeded. 

Most  attempts  to  find  circulating  anti- 
bodies have  failed.     However,  McDermott 
and  Stauber  (1954)  found  agglutinins 
against  merozoites  in  the  serum  of  exper- 
imentally infected  chickens  and  also  pro- 
duced them  in  rabbits  and  roosters  by  in- 
jecting formalinized  merozoite  suspensions. 
Becker  and  Zimmermann  (1953)  found  that 
infected  chicks  injected  intravenously  with 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


215 


an  alcoholic  horse  kidney  extract  produced 
fewer  oocysts  than  untreated,   infected 
controls.     Burns  and  Challey  (1959)  found 
that  when  chicks  which  had  been  previously 
infected  thru  a  fistula  into  a  cecal  pouch 
which  had  been  isolated  from  the  intestine 
were  challenged  with  E.  tenella  orally, 
they  were  somewhat  more  resistant  than 
the  controls,   indicating  that  there  is  some 
generalized  host  response. 

Less  research  has  been  done  on  the 
development  of  immunity  in  other  species 
of  coccidia.     Tyzzer,  Theiler  and  Jones 
(1932)  found  that  chickens  which  had  re- 
covered from  E.  necatrix  infections  were 
immune,  as  did  Grumbles  and  Delaplane 
(1947).    Dickinson  (1941)  and  Brackett 
and  Bliznick  (1950)  showed  that  immunity 
developed  following  infection  with  E. 
acervulina.     The  latter  found  the  same 
thing  with  E.  maxima.    Similar  results 
have  been  obtained  for  the  other  species 
(Brackett  and  Bliznick,   1950). 

Diagnosis:     Avian  coccidiosis  can  be 
diagnosed  by  finding  lesions  containing 
coccidia  at  necropsy.    Diarrhea  with  or 
without  blood  in  the  droppings,   inappetence 
and  emaciation  are  suggestive,  but  scrap- 
ings of  the  affected  intestinal  mucosa  must 
be  examined  microscopically  to  determine 
whether  coccidia  are  present.    It  is  not 
enough  to  look  for  oocysts,  but  schizonts, 
merozoites  and  young  gametes  should  be 
recognized  also. 

Coccidiasis  is  much  more  common 
than  coccidiosis;  hence  the  mere  presence 
of  oocysts  in  the  feces  cannot  be  relied 
upon  for  diagnosis.    Conversely,  the  ab- 
sence of  oocysts  does  not  necessarily  mean 
that  coccidiosis  is  not  present,   since  the 
disease  may  be  in  too  early  a  stage  to 
produce  oocysts. 

Since  some  species  of  coccidia  are 
highly  pathogenic  for  the  chicken  while 
others  are  practically  non-pathogenic, 
the  species  present  must  be  identified  to 
establish  a  diagnosis.    This  can  often  be 
done  in  a  rough  way  from  the  type  and  lo- 
cation of  the  lesions. 

Treatment:     Many  hundreds  of  papers 
have  been  written  on  the  treatment  of  coc- 


cidiosis in  chickens,  and  there  is  no  space 
here  for  more  than  a  relatively  brief  dis- 
cussion.    By  far  the  greatest  part  of  the 
research  has  been  done  on  E.   tenella. 

The  first  compound  found  effective 
against  coccidia  was  sulfur,  which  Herrick 
and  Holmes  (1936)  introduced.    When  2  to 
5%  sulfur  is  mixed  with  the  feed,  coccid- 
iosis is  largely  prevented  in  young  chicks. 
The  use  of  sulfur  had  a  certain  vogue,  but 
it  was  soon  found  unsatisfactory  because 
it  causes  a  condition  known  as  sulfur  rick- 
ets.    Even  tho  the  chicks  are  on  an  ordin- 
arily adequate  diet,  the  sulfur  interferes 
with  calcium  utilization  and  causes  rickets. 

The  use  of  borax  in  E.  tenella  coccid- 
iosis was  introduced  by  Hardcastle  and 
Foster  (1944).    Several  others  have  done 
research  on  it  (Wehr,   Farr  and  Gardiner, 
1949),  and  the  consensus  is  that  0.  3  to 
0.  5%  borax  in  the  feed  prevents  death  from 
coccidiosis  if  administered  beginning  1  or 
2  days  after  experimental  infection  and 
continued  for  3  days  or  longer.     However, 
it  does  not  prevent  cecal  hemorrhage  or 
weight  losses.    It  is  also  toxic,  causing 
loss  of  weight  even  when  fed  alone. 

P.   P.   Levine  (1939)  was  the  first  to 
use  sulfonamides  against  coccidiosis.    His 
discovery  that  sulfanilamide  was  active 
opened  up  the  field.     Many  different-- 
probably  several  hundred--sulfonamides 
were  tested,  and  a  number  of  them  were 
found  of  practical  value.    Sulfaguanidine 
was  introduced  after  sulfanilamide.    It 
was  followed  by  sulfamerazine  and  sulfa- 
methazine (called  sulfamezathine  in  Eng- 
land), and  still  later  by  sulfaquinoxaline 
and  N'*-acetyl-N'-(4-nitrophenyl)  sulfanil- 
amide.   All  of  these  compounds  are  effec- 
tive against  E.  tenella,    the  last  2  are 
quite  effective  against  E.  necatrix,   and 
sulfaquinoxaline  and  sulfaguanidine  are 
quite  effective  against  E.   acervulina. 
Sodium  sulfadimidine  is  active  against 
E.  mitis,    but  does  not  completely  elim- 
inate it  (Joyner,   1958). 

Sulfaguanidine  is  fed  at  the  rate  of 
0.  5%  in  the  mash,  sulfamethazine  and  sul- 
famerazine at  0. 1  to  0.25%,  and  sulfaquin- 
oxaline at  0.025%.    Sodium  sulfamethazine 
and  sodium  sulfadimidine  are  given  in  the 


216 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


drinking  water  at  0.  2%,  and  sodium  sulfa- 
quinoxaline  at  about  0.04%  (see  Grumbles, 
el  al.  ,  1949;  Farr,   1949;  Dickinson,   1949; 
Kendall  and  McCuUough,   1952;  Peterson 
and  Munro,   1949;  Peterson  and  Hymas, 
1950;  Davies  and  Kendall,   1954;  Bankow- 
ski,   1950;  Horton-Smith  and  Long,   1959; 
and  McLoughlin  and  Chester,   1959  for  re- 
views and  further  information). 

The  sulfonamides  are  in  general  more 
effective  against  the  schizonts  and  mero- 
zoites  than  against  the  gametes,  gameto- 
cytes  and  sporozoites.    Bankowski  (1950) 
found  that  0.  5%  sulfaguanidine  was  coccid- 
iostatic  against  the  first  generation  schi- 
zonts of  E.  tenella  but  that  2%  sulfaguan- 
idine was  required  to  kill  the  second  gen- 
eration schizonts  in  the  lamina  propria 
and  even  this  concentration  had  no  effect 
on  the  sporozoites.     He  concluded  that 
this  drug  must  act  against  the  merozoites 
in  the  lumen  of  the  ceca,  since  0.  5%  is 
the  usual  concentration  in  the  feed.    Ken- 
dall and  McCullough  (1952)  found  that  0.  25 
to  0.  375%  sulfamethazine  in  the  feed  af- 
fected the  later  stages  in  the  life  cycle, 
but  that  0.  5  to  1.0%  was  required  to  affect 
the  early  stages.     Farr  and  Wehr  (1947) 
found  that  1%  sulfamethazine  almost  com- 
pletely destroyed  the  second  generation 
schizonts  and  their  merozoites,  somewhat 
affected  the  first  generation  schizonts  but 
did  not  completely  destroy  them,  and 
either  damaged  or  destroyed  the  young 
gametes.    It  did  not  injure  the  larger  gam- 
etes, oocysts  or  sporozoites.    The  action 
of  sulfaquinoxaline  is  similar. 

All  of  the  sulfonamides  are  coccidio- 
static  rather  than  truly  curative.    None 
will  cure  coccidiosis  once  signs  of  dis- 
ease have  appeared.    When  fed  continu- 
ously in  the  feed,  they  abort  the  disease. 
Sulfaquinoxaline  will  protect  birds  when 
given  as  late  as  4  days  after  experimental 
infection.    Since  the  sporozoites  are  not 
affected,  they  invade  the  intestinal  cells 
and  stimulate  the  development  of  immun- 
ity.   However,  if  too  much  of  a  sulfona- 
mide is  given,  immunity  will  not  develop. 
Thus,  Kendall  and  McCullough  (1952) 
found  that  when  0.  25  to  0.  375%  sulfameth- 
azine was  given  in  the  feed,  immunity  de- 
veloped, but  when  the  concentration  was 
raised  to  0.  5  to  1. 0%  it  did  not. 


When  given  in  the  recommended 
amounts,  the  sulfonamides  are  not  gener- 
ally harmful.    Sulfaquinoxaline  does  not 
depress  the  growth  rate  of  chicks  when  fed 
for  a  long  period  at  rates  of  0.01  to  0.02%, 
but  0.03%  gives  variable  results  and  higher 
concentrations  are  usually  toxic.     Dela- 
plane  and  Milliff  (1948)  found  that  when 
0.  05%  sulfaquinoxaline  was  fed  continu- 
ously to  pullets  in  egg  production,   signs 
of  poisoning  appeared  and  some  birds  died. 
They  found  greyish-white  nodules  in  the 
spleens  of  most  birds  and  in  the  livers, 
kidneys,  hearts  and  lungs  of  some.    There 
were  also  hemorrhages  beneath  the  skin  of 
the  legs  and  in  the  combs.    Davies  and 
Kendall  (1953)  found  that  0.0645%  sodium 
sulfaquinoxaline  in  the  drinking  water  was 
toxic  to  chickens  when  fed  for  as  short  a 
period  as  5  days.    The  principal  lesions 
were  hemorrhages,  especially  in  the 
spleen,  and  accumulation  of  fluid  in  the 
peritoneal  cavity.     On  the  other  hand, 
Cuckler  and  Ott  (1955)  reported  that  the 
continuous  administration  of  0.  05%  sulfa- 
quinoxaline in  the  feed  or  of  0.025%  in  the 
water  for  as  long  as  12  weeks  had  no  ad- 
verse effects  on  chickens.    The  blood 
clotting  time  was  prolonged  and  the  pro- 
thrombin time  increased  slightly  by  feeding 
0.4%  sulfaquinoxaline  for  3  to  12  weeks. 


Several  organic  arsenic  compounds 
have  been  found  effective  against  E. 
tenella,    but  not  against  the  other  species 
(Morehouse  and  Mayfield,   1946;  Goble, 
1949).    All  are  derivatives  of  phenylarsonic 
acid.    All  are  coccidiostatic,  and  none  will 
cure  coccidiosis  once  signs  of  disease  have 
appeared.    The  most  widely  used  of  these 
is  perhaps  3-nitro-4-hydroxyphenylarsonic 
acid,  which  is  generally  administered  in 


the  feed  at  a  concentration  of  0.  01' 


It 


apparently  acts  against  the  earlier  endog- 
enous stages,  but  not  against  the  sporo- 
zoites, and  birds  which  are  exposed  while 
under  prophylactic  treatment  become  im- 
mune.   At  the  recommended  dosage  it  has 
no  harmful  effect  on  the  host  but  is  actually 
a  growth  stimulant.    A  mixture  of  this 
compound  and  N^-acetyl-N'-(4-nitrophenyl) 
suKanilamide  is  sold  under  the  name  Ni- 
trosal  to  suppress  both  cecal  and  intestinal 
coccidiosis.    Another  active  organic  ar- 
senic compound  is  arsanilic  acid. 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


217 


A  number  of  alkylidenediphenols, 
which  are  diphenylmethane  derivatives, 
are  effective  against  E.  tenella,  (Johnson, 
Mussell  and  Dietzler,   1949,   1949a; 
Groschke  et  al.  ,  1949).    One  of  these, 
Parabis-90,  is  2,  2'-methylene-bis-4- 
chlorophenol.    It  is  used  in  the  starter 
feed  at  a  concentration  of  0. 15%,  and 
later  on,  when  the  chicks  are  6  to  8  weeks 
old,   in  the  grower  feed  at  a  concentration 
of  0. 12%.    These  compounds  are  also  coc- 
cidiostatic  and  will  not  cure  coccidiosis 
once  signs  of  the  disease  have  appeared. 
They  appear  to  act  primarily  against  the 
earlier  endogenous  stages  but  not  against 
the  sporozoites,  and  birds  which  are  ex- 
posed while  getting  the  drug  become  im- 
mune.    They  do  not  appear  to  harm 
chickens  when  fed  at  the  recommended 
levels. 

A  diphenyl  disulfide  derivative  which 
has  been  widely  used  as  a  coccidiostat 
against  both  E.  tenella  and  E.  necatrix 
is  nitrophenide  (Megasul).    It  is  3,  3'-di- 
nitrodiphenyldisulfide  (Waletzky,   Hughes 
and  Brandt,  1949;  Peterson  and  Hymas, 
1950;  Dickinson,  Babcock  and  Osebold, 
1951;  Gardiner,   Farr  and  Wehr,   1952; 
Horton-Smith  and  Long,   1959).    It  is 
mixed  with  the  feed  at  the  rate  of  0.  025  to 
0.  05%.    It  is  coccidiostatic  and  will  not 
cure  coccidiosis  once  signs  of  the  disease 
have  appeared.    It  acts  against  both  the 
sporozoites  and  later  stages,  but  is  more 
effective  against  the  latter  and  especially 
against  the  second  generation  schizonts. 
Immunity  does  not  appear  to  develop  if 
chickens  are  treated  before  infection,  but 
it  does  if  treatment  begins  at  the  time  of 
infection  or  later.     Nitrophenide  is  not 
harmful  if  fed  in  therapeutic  concentra- 
tions.   At  higher  doses  Newberne  and 
McDougle  (1956)  found  that  it  may  cause 
postural  and  locomotor  disturbances, 
lowered  weight  gains,  liver  degeneration 
and  bone  marrow  changes. 

Another  coccidiostat  is  the  diphenyl- 
sulfide  derivative,  bithionol,  or  2,2'- 
dihydroxy-3,  3',  5,  5'-tetrachlorodiphenyl 
sulfide.    The  commercial  coccidiostat, 
Trithiadol,  is  a  mixture  of  5  parts  bithi- 
onol and  1  part  methiotriazamine.    The 
latter  is  4,  6-diamino-l-(4-methylmer- 


captophenyl)-!,  2-dihydro-2,  2-dimethyl- 
1,  3,  5-triazine.     Bithionol  is  not  only  coc- 
cidiostatic but  also  antibacterial  and  anti- 
fungal.    Methiotriazamine  is  coccidiostatic 
at  high  concentrations  and  is  also  an  active 
antimalarial  agent.    In  combination,  these 
drugs  are  effective  against  coccidia  at 
lower  concentrations  than  when  used  alone. 
A  mixture  containing  60%  active  ingredients 
is  fed  in  the  feed  at  the  rate  of  2  pounds  per 
ton.    The  recommended  use  level  is  0.05% 
bithionol  plus  0.01%  methiotriazamine.    It 
is  effective  against  E.  tenella,  E.  necatrix, 
E.  maxima  and  E.  acervulina.     Chickens 
fed  it  develop  immunity  to  these  coccidia. 
McLoughlin  and  Chester  (1959)  found  that 
0.  06%  Trithiadol  gave  relatively  good  pro- 
tection from  mortality  due  to  E.  tenella. 
It  was  not  as  good  as  glycarbylamide  and 
nicarbazin  but  was  about  as  effective  as 
nitrofurazone  and  Bifuran  and  somewhat 
better  than  sulfaquinoxaline.     Trithiadol 
is  not  harmful  to  growing  chickens  when 
fed  at  the  recommended  levels  (Arnold 
and  Coulston,   1959).    It  does  not  appear 
to  affect  egg  production  or  egg  shell  color 
or  quality,  but  it  does  affect  hatchability 
to  some  extent  and  is  not  recommended 
for  use  in  laying  mashes. 

Two  nitrofurans  are  currently  used 
as  coccidiostats.     Nitrofurazone  (5-nitro- 
2-furaldehyde  semicarbazone)  was  intro- 
duced by  Harwood  and  Stunz  (1949,   1949a, 
1950)  and  has  been  studied  further  by 
Peterson  and  Hymas  (1950),  Gardiner  and 
Farr  (1954),   Horton-Smith  and  Long  (1952, 
1959)  and  McLoughlin  and  Chester  (1959), 
among  others.    It  is  mixed  with  the  feed 
at  the  rate  of  0.011%.    It  is  effective 
against  E.  tenella  and  to  a  lesser  extent 
against  E.  necatrix  and  E.  maxima. 
Higher  concentrations  give  better  results 
against  the  intestinal  species.    Nitrofur- 
azone is  coccidiostatic  and  will  not  cure 
coccidiosis  once  signs  of  the  disease  have 
appeared.    It  acts  against  the  schizonts, 
and  birds  infected  while  receiving  the 
drug  develop  immunity  to  reinfection. 

Nitrofurazone  is  not  harmful  if  fed  in 
therapeutic  amounts,  but  0.04  to  0.05%  in 
the  feed  is  definitely  toxic,  and  an  adverse 
effect  on  the  growth  rate  has  been  noted 
even  at  0.022%  (Gardiner  and  Farr,  1954; 


218 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


Peterson  and  Hymas,   1950).     Newberne 
and  McEuen  (1957)  found  that  0.  05  to  0. 1% 
of  nitrofurazone  in  the  feed  produced 
stunted  growth,  curled-toe  paralysis, 
clinical  polyneuritis,  atrophy  of  the  fol- 
licles of  the  bursa  of  Fabricius,   renal 
tubular  degeneration  and  pulmonary  ossifi- 
cation in  young  chicks.     The  blood  picture 
remained  essentially  normal.     McLoughlin 
and  Chester  (1959)  found  that  0.0055'f 
nitrofurazone  was  less  effective  than  gly- 
carbylamide  or  nicarbazin  but  more  effec- 
tive than  0.0125"(  sulfaquinoxaline  against 
E.  tenella. 

Another  nitrofuran  coccidiostat,   Bi- 
furan,  was  introduced  quite  recently.     It 
is  a  mixture  of  nitrofurazone  and  furazo- 
lidone (NF  180,  or  N-(5-nitro-2-furfury- 
lidene)-3-amino-2-oxazolidone).     The 
final  concentrations  in  the  feed  are  0.0055% 
nitrofurazone  and  0.0008%  furazolidone. 
McLoughlin  and  Chester  (1959)  found  that 
it  was  less  effective  than  glycarbylamide 
and  nicarbazin,  about  as  effective  as  nitro- 
furazone and  more  effective  than  sulfa- 
quinoxaline against  E.  tenella  infections 
in  chicks.     Horton-Smith  and  Long  (1959) 
found  that  it  was  effective  against  E. 
necatrix  when  fed  at  double  the  above  level. 
Kantor  and  Levine  (unpublished)  found  that 
furazolidone  by  itself  was  valueless  against 
E.  necatrix. 

Both  nitrofurazone  and  furazolidone 
are  also  antibacterial  agents.     Furazoli- 
done is  used  against  Salnionella  infections 
in  poultry,  and  also  has  some  effect 
against  Histomonas  meleagridis  (Harwood 
and  Stun z,   1954)  and  T)'icho»ioiias  gal- 
linae  (Stabler,   1957). 

The  anticoccidial  properties  of  sub- 
stituted carbanilide  complexes  were  dis- 
covered by  Cuckler  et  at.  (1955).    They 
introduced  nicarbazin,  which  is  an  equi- 
molar  complex  between  4,  4'-dinitrocar- 
banilide  and  2-hydroxy-4,  6-dimethylpyri- 
midine.    A  simple  mixture  is  no  better 
than  the  carbanilide  alone.     Nicarbazin  is 
fed  at  a  concentration  of  0.01  to  0.0125% 
in  the  feed,  or  0.  008%)  in  replacement 
flocks.    It  is  effective  against  E.  tenella, 
E.  acerviilina  and  E.  necatrix  (Cuckler, 
Malanga  and  Ott,   1956;  Rubin  et  al.  ,  1956; 


Cuckler,  Ott  and  Fogg,   1957;  Horton-Smith 
and  Long,  1959).    McLoughlin  and  Chester 
(1959)  found  that  nicarbazin  was  about  as 
effective  as  glycarbylamide  against  E. 
tenella,  and  more  effective  than  nitrofura- 
zone,  Bifuran,   sulfaquinoxaline  or  Trith- 
iadol. 

Nicarbazin  is  coccidiostatic,  and  will 
not  cure  coccidiosis  once  signs  of  the  dis- 
ease have  appeared.    It  acts  against  the 
second  generation  schizonts  and  their 
merozoites  (Cuckler  and  Malanga,   1956), 
and  birds  which  are  infected  while  receiv- 
ing the  drug  develop  immunity  to  reinfec- 
tion (Cuckler  and  Malanga,   1956;  Marthe- 
dal  and  Veiling,   1957;  McLoughlin,   Rubin 
and  Cordray,   1957,   1958). 

Nicarbazin  is  not  recommended  for 
laying  hens.    When  fed  at  the  recommended 
level,   it  makes  the  egg  shells  pale  (Mc- 
Loughlin, Wehr  and  Rubin,   1957).     At 
higher  levels  the  yolks  become  mottled, 
blotchy,   enlarged  and  sometimes  even 
brown,  the  whites  may  become  cloudy, 
hatchability  is  affected,  and  production 
may  be  reduced  (Snyder,   1956;  Sherwood, 
Milby  and  Higgins,   1956;  Baker  et  al.  , 
1956;  Lucas,   1958). 

Other  pyrimidine  derivatives  besides 
the  one  in  nicarbazine  may  have  a  syner- 
gistic effect  on  sulfonamide  coccidiostats. 
Lux  (1954)  found  that  pyrimethamine 
(Daraprim;  2,  4-diamino-5-p-chlorophenyl- 
6-ethyl  pyrimidine),  which  is  a  powerful 
antimalarial  drug,  acted  synergistically 
with  sulfanilamide  and  other  sulfonamides 
against  E.  tenella.     Joyner  and  Kendall 
(1955)  found  that  as  little  as  0.0025%  pyri- 
methamine allowed  the  effective  concen- 
tration of  sulfamethazine  against  E.  tenella 
to  be  reduced  to  1   8  to  1    16  of  that  nor- 
mally required  for  protection.     Marthedal 
and  Veiling  (1957)  found  that  pyrimetha- 
mine acted  synergistically  with  two  other 
sulfonamides,   sulfabenzpyrazine  and  sul- 
fadimidine, against  E.   tenella. 

Most  recently,  a  quaternized  deriva- 
tive of  pyrimidine,  amprolium,   has  been 
introduced.     This  compound  is  l-(2-«- 
propyl-4-amino-5-pyrimidinylmethyl)-2- 
methylpyridinium  chloride  hydrochloride. 


THE  TELOSPORASIDA  AND  THE  COCCIDIA    PROPER 


219 


According  to  Rogers  eL  al.  (1960),  0.0125% 
amprolium  in  the  feed  is  effective  against 
E.  tenella,   E.  necatrix    and  £.  acervuliiia. 
It  is  a  thiamine  antagonist,  and  0.  003% 
thiamine  in  the  feed  markedly  decreased 
its  activity  against  coccidia.    Another 
name  for  amprolium  is  mepyrium,  the 
discovery  of  which  was  announced  by 
Aries  (1960). 

According  to  Rogers  et  al.    (1960), 
many  other  l-(2-alkyl-4-amino-5-pyri- 
midinylmethyl)-alkyl  pyridinium  salts  have 
marked  prophylactic  activity  in  coccidiosis 
of  poultry.    Analogous  3-thiazolium  com- 
pounds are  also  effective. 

The  imidazole  derivative,  glycarbyla- 
mide  (4,  5-imidazoledicarboxamide)  was 
introduced  as  a  coccidiostat  by  Cuckler 
et  al.   (1958).    It  is  fed  in  a  concentration 
of  0.  003%  in  the  feed.    It  is  effective 
against  E.  tenella,  E.  necatrix  and  E. 
acervulina,  but  Horton-Smith  and  Long 
(1959a)  found  that  it  is  inferior  to  sulfa- 
quinoxaline  against  the  last.     McLoughlin 
and  Chester  (1959)  found  that  it  is  about 
as  effective  as  nicarbazin  against  E. 
tenella,   and  more  effective  than  nitrofura- 
zone,  Bifuran,   sulfaquinoxaline  or  Trithi- 
adol. 

Glycarbylamide  is  coccidiostatic,  and 
will  not  cure  coccidiosis  once  signs  of  the 
disease  have  appeared.    It  acts  against  the 
stages  prior  to  the  second  generation 
schizonts,  and  birds  which  are  infected 
while  receiving  the  drug  develop  immunity 
to  reinfection.    It  is  apparently  non-toxic 
when  fed  at  the  recommended  level. 

Several  benzamide  derivatives  are 
effective  coccidiostats.    Morehouse  and 
McGuire  (1957,   1959)  found  that  3,  5-di- 
nitrobenzamide  and  several  aliphatic  N- 
substituted  derivatives  are  effective 
against  E.  tenella  and  somewhat  less  ef- 
fective against  E.  necatrix.     They  found 
that  Unistat,  a  "coccidiostatic  growth 
stimulant"  mixture  containing  30%  N"*- 
acetyl-N^-(4-nitrophenyl)  sulfanilamide, 
25%  3,  5-dinitrobenzamide  and  5%  3-nitro- 
4-hydroxyphenylarsonic  acid  in  an  inert 
carrier,  when  fed  at  a  concentration  of 
0. 1%  in  the  feed,  prevented  death  and 


permitted  normal  or  near  normal  weight 
gains  in  chicks  infected  with  potentially 
lethal  doses  of  E.   tenella,  E.  necatrix 
and  E.  acervulina. 

Another  benzamide  derivative  is 
zoalene  (3,  5-dinitro-o-toluamide).    Hymas, 
Stevenson  and  Shaver  (1960)  reported  that 
it  prevents  mortality  and  weight  losses 
from  infections  with  E.  tenella,  E.  neca- 
trix, E.  acervulina,  E.  maxima  and  E. 
brunetti  when  fed  continuously  in  the 
ration  of  chicks  at  levels  ranging  from 
0.0025  to  0.015%.     They  recommended  a 
level  of  0.  0125%  for  broilers  and  lower 
levels  for  replacement  pullets.     This  com- 
pound is  most  effective  against  E.  necatrix. 

The  benzamide  derivatives  are  coc- 
cidiostatic and  will  not  cure  the  disease 
once  signs  have  appeared.    Birds  which 
are  infected  while  receiving  them  develop 
immunity  to  reinfection. 

Hemorrhage  is  an  important  cause  of 
death  from  cecal  coccidiosis,  and  its  con- 
trol will  ameliorate  the  disease.     Harms 
and  Tugwell  (1956)  and  Tugwell,  Stephens 
and  Harms  (1957)  found  that  the  vitamin  K 
activity  of  alfalfa  meal  or  menadione  so- 
dium bisulfite  complex  (Klotogen  F)  pre- 
vented deaths  from  cecal  coccidiosis  in 
birds  on  a  basic  vitamin  K-deficient  diet. 
Otto  et  al.    (1958)  confirmed  their  work, 
finding  that  1.0  g  of  the  water  soluble 
menadione  sodium  bisulfite  complex  per 
ton  of  feed  was  just  as  effective  as  3  g  per 
ton  of  menadione. 

Sulfonamides  and  other  coccidiostats 
have  been  mixed  in  poultry  feed  for  so 
many  years  that  it  was  inevitable  that  drug 
resistant  strains  of  coccidia  would  develop. 
The  first  report  of  this  was  by  Waletzky, 
Neal  and  Hable  (1954),  who  found  that  a 
field  strain  of  E.  tenella  from  a  Delaware 
broiler  flock  was  more  than  40  times  as 
resistant  to  sulfaquinoxaline  and  5  times 
as  resistant  to  sulfamethazine  as  ordinary 
strains.    It  was  unaffected  by  1.0%  sulfa- 
quinoxaline in  the  feed.    Cuckler  and 
Malanga  (1955)  studied  40  field  strains  of 
allegedly  drug-resistant  cecal  or  mixed 
intestinal  and  cecal  coccidia  from  chick- 
ens.   They  found  that  43%  were  resistant 


220 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


to  nitrophenide,  45%  to  sulfaquinoxaline 
and  57%  to  nitrofurazone.    Twenty-two 
percent  were  resistant  to  all  3  drugs,  18% 
to  2  and  18"f  to  1.     None  were  resistant 
to  nicarbazin,  which  had  only  recently 
been  placed  on  the  market.    They  produced 
resistance  against  sulfaquinoxaline  in  1 
strain  of  E.  acerviilina  and  2  strains  of 
E.  lenella  by  exposure  to  suboptimal  dos- 
ages of  the  drug  during  15  serial  passages, 
but  1  strain  of  E.  tenella  was  not  rendered 
resistant  to  nitrophenide,  nitrofurazone  or 
nicarbazin  by  the  same  method  for  15  ser- 
ial passages. 

Drug  resistance  is  becoming  increas- 
ingly common.    It  seems  to  develop  with 
especial  ease  against  glycarbylamide.    As 
a  consequence,  we  are  in  a  race  between 
the  discovery  of  new  coccidiostats  and  the 
development  by  the  parasites  of  resistance 
against  the  older  ones.    In  the  long  run, 
prevention  of  coccidiosis  without  reliance 
on  drugs  appears  to  hold  more  promise. 

Prevention  and  Control:     Coccidian 
oocysts  are  extremely  resistant  to  envir- 
onmental conditions.     They  may  remain 
alive  in  the  soil  for  a  year  or  more  (War- 
ner,  1933;  Farr  and  Wehr,   1949;  Koutz, 
1950).    They  will  not  sporulate  in  the  ab- 
sence of  oxygen,  and  they  are  killed  in 
time  by  subfreezing  temperatures.    Thus, 
Edgar  (1954)  found  that  the  oocysts  of  E. 
tenella  vieve  dead  after  7  days  at  -12°  C. 

Ordinary  antiseptics  and  disinfectants 
are  ineffective  against  them.     Pe'rard 
(1924),  for  instance,  found  that  the  oocysts 
of  rabbit  coccidia  would  sporulate  unharmed 
in  5%  formalin,   5%  phenol,   5%  copper  sul- 
fate, or  10%  sulfuric  acid.     Horton-Smith, 
Taylor  and  Turtle  (1940)  confirmed  this 
with  E.  tenella  and  added  5%  potassium 
hydroxide  and  5%  potassium  iodide  to  the 
list.    Indeed,  the  standard  storage  solu- 
tions for  coccidian  oocysts  are  2.  5% 
potassium  bichromate  or  1%  chromic  acid 
solution. 

The  oocysts  may  be  destroyed  by 
ultra-violet  light,  heat,  desiccation  or 
bacterial  action  in  the  absence  of  oxygen. 
Long  (1959)  found  that  exposure  to  a  tem- 
perature of  52°  C  for  15  minutes  killed 


the  oocysts  of  E.  tenella  and  E.  maxima. 
However,  Horton-Smith  and  Taylor  (1939) 
found  that  even  a  blowtorch  did  not  kill  all 
the  oocysts  on  the  floors  of  poultry  houses 
unless  it  was  applied  long  enough  to  make 
the  wood  start  to  char.     The  problem  is 
to  reach  and  maintain  a  lethal  temperature 
at  the  spot  where  the  oocysts  are. 

While  formaldehyde  fumigation  is  in- 
effective against  coccidia,   Horton-Smith, 
Taylor  and  Turtle  (1940)  showed  that  am- 
monia fumigation  is  of  practical  value. 
E.  tenella  oocysts  were  killed  by  an 
0.0088%  solution  of  ammonia  in  24  hours, 
by  an  0.  044%  solution  in  2  hours  and  by  an 
0.088%  solution  in  45  minutes.     They  fu- 
migated poultry  houses  successfully  with 
3  oz.  ammonia  gas  per  10  cu.  ft.     For 
satisfactory  results,  the  houses  should  be 
sealed  so  that  the  gas  does  not  leak  out. 

Boney  (1948)  found  that  methyl  bro- 
mide is  also  an  effective  fumigant.    It  in- 
activated sporulated  oocysts  of  E.  tenella 
in  the  litter  or  soil  when  applied  at  the 
rate  of  approximately  1  lb.   per  1000  square 
feet  (0.  3  ml  per  sq.  ft. ).    It  prevented  in- 
fection in  brooder  houses  using  artificially 
contaminated  cane  pulp  litter  on  wooden 
floors  when  used  as  a  space  fumigant  at 
the  rate  of  2  lb.   per  1000  cu.  ft. 

Since  it  is  practically  impossible  under 
farm  conditions  to  prevent  chickens  from 
picking  up  at  least  a  few  oocysts,  preven- 
tion of  coccidiosis  depends  upon  preventing 
a  heavy  enough  infection  to  produce  disease 
while  at  the  same  time  permitting  a  symp- 
tomless infection  (coccidiasis)  to  develop 
and  to  produce  immunity.     This  can  be 
accomplished  by  proper  sanitation  and 
management.    Strict  sanitation  is  effective 
alone,  but  it  is  usually  supplemented  by 
the  use  of  a  coccidiostatic  drug. 

Young  chickens  should  be  raised  apart 
from  older  birds,  since  the  latter  are  a 
source  of  infection.    If  birds  are  raised  on 
the  floor,  each  new  brood  of  chicks  should 
be  placed  in  a  clean  house  containing  clean, 
new  litter.     The  litter  should  be  kept  dry, 
stirred  frequently  and  removed  when  wet. 
The  feeders  and  waterers  should  be  washed 
in  boiling  water  before  use,  and  should  be 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


221 


cleaned  at  least  weekly  with  hot  water  and 
detergent.    The  waterers  should  be  placed 
on  wire  platforms  over  floor  drains,  and 
the  feeders  should  be  raised  high  enough 
to  prevent  their  being  fouled.     Enough 
feeders  should  be  provided  so  that  all  the 
birds  can  feed  at  once  without  crowding. 

Chicks  raised  on  wire  have  much  less 
chance  of  contamination  than  those  raised 
on  the  floor.     However,  the  wire  should  be 
cleaned  regularly. 

Flies,   rats  and  mice  around  the  poul- 
try houses  and  yards  should  be  eliminated, 
since  they  may  carry  coccidia  mechanic- 
ally.   Damp  areas  around  the  poultry  house 
should  be  filled  in  or  drained. 

Feeding  a  coccidiostat  during  times 
when  the  birds  are  especially  susceptible 
may  also  be  helpful.     The  drug  may  be  fed 
until  the  birds  are  8  or  9  weeks  old,  after 
which  they  have  ordinarily  become  im- 
mune.   In  addition,  it  is  often  recommended 
that  a  coccidiostat  be  fed  to  pullets  for  the 
first  2  or  3  weeks  after  they  have  been 
moved  into  laying  houses. 

If  an  outbreak  of  coccidiosis  occurs, 
all  sick  birds  should  be  removed  from  the 
flock  and  placed  in  a  separate  pen.    They 
should  be  given  ample  food  and  water,  but 
it  is  useless  to  attempt  to  treat  them.    The 
remaining,  apparently  healthy  birds  should 
be  treated  with  a  coccidiostat  in  the  dosage 
recommended  by  the  manufacturer.    Birds 
which  become  ill  should  be  removed.    The 
litter  should  be  kept  dry  and  stirred  fre- 
quently. 

All  dead  birds  should  be  burned.    The 
litter  should  also  be  burned  or  put  some- 
place where  chickens  will  never  have 
access  to  it. 

Care  should  be  taken  not  to  track  coc- 
cidia from  sick  birds  to  healthy  ones. 
Special  rubbers  or  overshoes  should  be 
put  on  before  entering  pens  containing  sick 
birds,  and  should  be  cleaned  thoroughly 
after  each  use.    Veterinarians  going  from 
one  farm  to  another  should  disinfect  their 
boots  before  leaving  each  premises. 


The  use  of  old,  built-up,  deep  floor 
litter  has  been  recommended  by  Kennard 
and  Chamberlin  (1949)  and  others  to  reduce 
losses  from  coccidiosis.     By  this  method, 
the  litter  is  not  changed  when  new  batches 
of  birds  are  placed  in  a  house,  but  some 
fresh  litter  may  be  added  from  time  to 
time  as  needed  to  keep  it  in  good  condition. 
The  litter  is  stirred  every  2  or  3  days  for 
the  first  8  weeks  and  every  day  thereafter. 
Every  2  to  4  weeks,   hydrated  lime  may  be 
mixed  in  with  the  litter  at  the  rate  of  10  to 
15  lb.  per  100  square  feet  of  litter,  but 
this  is  not  necessary.     The  litter  will  keep 
dry  for  8  to  16  weeks.    Using  this  method, 
Kennard  and  Chamberlin  (1949)  observed  a 
mortality  of  7%  as  compared  to  a  mortality 
of  19%  in  chickens  kept  on  fresh  litter  re- 
moved and  changed  every  2  weeks. 

On  the  other  hand,  Koutz  (1952,  1952a) 
found  that  many  coccidian  oocysts  and 
nematode  eggs  remain  alive  in  deep  litter. 
Horton-Smith  (1954),  too,  pointed  out  the 
dangers  inherent  in  its  use.     He  noted, 
however,  that  the  ammonia  produced  would 
kill  many  oocysts.     Long  and  Bingstead 
(1959)  found  that  chicks  on  old,  built-up 
litter  did  not  gain  as  well  as  chicks  on 
wire  or  new  wood  shavings,  and  that  coc- 
cidia appeared  in  them  earlier.    Because 
of  the  dust,  ammonia  fumes,  and  danger 
of  other  diseases,  the  use  of  built-up  litter 
in  raising  chickens  is  not  recommended. 

Edgar  (1955a)  developed  a  coccidiosis 
"vaccine"  which  is  said  to  be  highly  suc- 
cessful in  immunizing  chicks.    It  is  a 
mixture  of  sporulated  oocysts  of  E.  tenella, 
E.  necatrix,  E.  maxima,  E.  acervulina 
and  E.  hagani  (Libby,  Bickford  and  Glista, 
1959).    It  is  recommended  for  use  when 
the  chicks  are  3  to  5  days  old.    They  are 
starved  for  about  3  hours  and  then  given 
feed  freshly  mixed  with  the  commercially 
prepared  oocyst  culture.    The  chicks  are 
supposed  to  develop  light  infections  and 
seed  the  litter  with  the  oocysts  which  they 
produce.    These  oocysts  produce  reinfec- 
tions in  turn.    It  is  recommended  that  a 
coccidiostat  be  fed  at  a  low  level  until  5 
weeks  after  vaccination,  i.e.,  until  the 
birds  are  5^  to  6  weeks  old.    Under  these 
conditions,  the  birds  are  said  to  become 


222 


THE  TELOSPORASIDA  AND  THE  COCCIDLA   PROPER 


immune  without  suffering  disease.    While 
this  system  often  works  well,  failures 
have  been  encountered  too  often  to  justify 
recommending  its  general  use  at  present. 


EIMERIA  MELEAGRIDIS 
TYZZER,    1927 

Hosts:     Domestic  and  wild  turkey. 

Altho  Steward  (1947)  and  Gill  (1954) 
claimed  to  have  transmitted  this  species 
experimentally  to  the  chicken,   Tyzzer 
(1929)  was  unable  to  transmit  it  to  the 
chicken,   ring-necked  pheasant  or  bob- 
white  quail,   Hawkins  (1952)  was  unable  to 
transmit  it  to  the  bobwhite  quail  or  Hun- 
garian partridge,  and  Moore,   Brown  and 
Carter  (cited  by  Moore,   1954)  and  Clark- 
son  (1959a)  were  unable  to  transmit  it  to 
the  chicken. 

Location:     The  first  generation  schi- 
zonts,  which  are  relatively  few  in  number, 
are  found  only  in  the  small  intestine  a 
short  distance  on  either  side  of  the  yolk 
stalk.     They  lie  below  the  host  cell  nuclei 
in  the  epithelial  cells,   mostly  in  those 
near  the  base  of  the  villi  but  not  in  the 
deep  glands. 

The  second  generation  schizonts 
occur  in  the  cecum,  where  they  lie  above 
the  host  cell  nuclei  in  the  epithelial  cells 
of  the  tips  of  the  villi. 

The  sexual  stages  are  found  in  the 
cecum,   rectum  and,  to  a  slight  extent, 
ileum.     They  lie  above  the  host  cell  nuclei 
deep  in  the  glands  of  the  cecum  as  well  as 
in  the  surface  epithelium  (Clarkson,  1959a). 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common.    Kozicky 
(1948)  found  "E.  meleagridis"  in  the  drop- 
pings of  40%  of  95  wild  turkeys  in  Penn- 
sylvania. 

Morphology:     This  species  was  first 
described  by  Tyzzer  (1927).     The  oocysts 
are  ellipsoidal,   smooth,   19  to  31  by  14  to 
23  ^x  with  a  mean  of  24  by  17  (i.    The 
oocysts  measured  by  Clarkson  (1959a) 


were  22.3  +  2.3  by  16.  25  t  1.23fi.     A 
micropyle  is  absent.    One  or  2  oocyst 
polar  granules  are  present.     An  oocyst 
residuum  is  absent.     The  sporocysts  are 
ovoid,  with  a  Stieda  body.    A  sporocyst 
residuum  is  present.     The  sporulation 
time  is  1  day.     Edgar  (1955)  found  some 
sporulated  oocysts  as  early  as  15  hours 
at  28    C. 

Life  Cycle:     Hawkins  (1952)  and 
Clarkson  (1959a)  described  the  life  cycle, 
the  latter  using  a  strain  which  he  had  de- 
rived from  a  single  oocyst.     The  first 
generation  schizonts  are  present  2  to  5 
days  after  infection,  being  found  in  great- 
est numbers  at  60  hours.     They  measure 
20  by  15/1  and  contain  50  to  100  mero- 
zoites  measuring  7  by  1.  5(i.     The  second 
generation  schizonts  first  appear  60  hours 
after  infection,  and  mature  ones  are  pres- 
ent after  70  hours;  they  are  seen  in  great- 
est numbers  at  84  hours.     They  are  about 
9  (i  in  diameter  and  contain  8  to  16  mero- 
zoites  which  measure  10  by  2;i.     Hawkins 
stated  that  there  may  be  a  third  asexual 
generation,  but  that  most  of  the  second 
generation  merozoites  develop  into  sexual 
stages;  Clarkson  did  not  describe  third 
generation  schizonts. 

Macrogametes  and  microgametocytes 
appear  at  91  hours  and  become  mature  9 
days  after  infection.     They  measure  about 
18  by  13jLt.     The  microgametes  are  bi- 
flagellate. 

According  to  Hawkins,  oocysts  appear 
in  the  feces  5  days  after  infection;  Clarkson 
found  that  the  prepatent  period  was  108  to 
112  hours. 


Pathogenesis:     This  species  is  prac- 
tically non-pathogenic.     Hawkins  (1952) 
observed  only  a  slight  drop  in  weight  in 
poults  experimentally  infected  with 
400,000  to  1  million  sporulated  oocysts. 
Moore  and  Brown  (1951)  infected  poults 
with  "enormous  numbers"  of  fresh,  spor- 
ulated oocysts  without  producing  clinical 
evidence  of  coccidiosis.     Clarkson  (1959a) 
found  that  doses  of  up  to  1  million  oocysts 
produced  no  signs  of  disease  in  2-week- 
old  poults. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


223 


The  serosal  sui'face  of  the  ceca  of 
heavily  infected  birds  is  cream  colored. 
The  ceca  contain  a  non-adherent,   mucoid 
or  caseous,  yellow  plug  on  the  5th  and 
6th  days.     Caseous  material  composed  of 
oocysts  and  epithelial  cells  is  sometimes 
found  in  the  feces  on  the  6th  day,  but  the 
ceca  appear  quite  normal  in  another  day 
or  two.     Hawkins  noted  petechial  hemor- 
rhages in  the  cecal  mucosa. 

Immunity:     Turkeys  which  have  re- 
covered from  an  infection  with  E.  mele- 
agyidis  have  a  high  degree  of  immunity 
according  to  Hawkins  (1952).     Clarkson 
(1959a)  found  no  cross  immunity  between 
this  species  and  E.  adenoeides. 


EIMERIA  MELEAGRIMITIS 
TYZZER,   1929 

Host:     Turkey. 

Hawkins  (1952)  was  unable  to  trans- 
mit this  species  to  the  bobwhite  quail  or 
Hungarian  partridge.    Gill  (1954)  claimed 
to  have  transmitted  it  to  the  chicken. 

Location:     The  asexual  stages  occur 
mainly  in  the  upper  jejunum,  but  a  few 
are  present  in  the  duodenum  and  ileum  as 
far  as  the  yolk  stalk.     The  first  genera- 
tion schizonts  lie  below  the  host  cell  nuclei 
of  the  epithelial  cells  of  the  glands.     The 
second  generation  schizonts  develop  in 
colonies  in  the  epithelial  cells  of  the  deep 
glands  but  also  spread  up  the  sides  of  the 
villi.     They  usually  lie  just  beneath  the 
brush  border  of  the  cell  but  are  some- 
times found  below  the  host  cell  nucleus. 
The  third  generation  schizonts  are  found 
in  the  epithelial  cells  of  the  villi  but  never 
in  the  glands.     Most  of  them  lie  above  the 
host  cell  nucleus,  but  some  are  below  it. 

The  sexual  stages  are  found  mainly 
in  the  epithelial  cells  at  the  tips  of  the 
villi  but  also  spread  down  the  sides.     The 
great  majority  lie  above  the  host  cell 
nucleus  (Clarkson,   1959). 

Geographic  Distribution:      Presumably 
worldwide. 


Prevalence:     Quite  common.     Four 
out  of  22  outbreaks  studied  by  Clarkson 
and  Gentles  (1958)  in  Great  Britain  were 
due  to  this  species,  and  3  to  a  mixture  of 
it  and  E.  adenoeides. 

Morphology:     The  morphology  of  this 
species  has  been  studied  especially  by 
Tyzzer  (1929),   Hawkins  (1952)  and  Clark- 
son (1959).    The  oocysts  are  subspherical, 
smooth,   16  to  27  by  13  to  22  jj.  with  a  mean 
of  19  by  16fi;  150  oocysts  measured  by 
Clarkson  (1959)  were  20.  li  1.95  by 
17.3tl.7j:i.    A  micropyle  is  absent.    One 
to  3  oocyst  polar  granules  are  present. 
An  oocyst  residuum  is  absent.     The  sporo- 
cysts  are  ovoid,  with  a  Stieda  body.     A 
sporocyst  residuum  is  present.     The 
sporozoites  have  a  colorless  globule  at  the 
large  end.     The  sporulation  time  is  2  days 
according  to  Hawkins  (1952),   1  day  at  26°C 
according  to  Clarkson  (1959). 

Life  Cycle:     Tyzzer  (1929),   Hawkins 
(1952)  and  Clarkson  (1959)  studied  the  life 
cycle  of  this  species,  the  last  using  a 
strain  derived  from  a  single  oocyst.     The 
account  below  is  that  of  Clarkson,  which 
is  the  most  complete.     The  sporozoites 
invade  the  tips  of  the  villi  and  migrate 
down  the  villi  in  the  lamina  propria  until 
they  reach  the  glands.     Young  first  gener- 
ation schizonts  can  be  found  in  the  gland 
epithelial  cells  as  early  as  12  hours  after 
infection,  and  many  are  mature  by  48 
hours.     They  usually  measure  17  by  ISfj, 
and  enlarge  the  host  cell,   pushing  its 
nucleus  into  the  gland  lumen.    They  con- 
tain 80  to  100  merozoites  which  measure 
about  4.  5  by  1.  5jj,  and  have  the  nucleus 
at  the  larger  end. 

The  first  generation  schizonts  rupture 
and  release  the  merozoites,  which  invade 
the  adjacent  epithelial  cells,  forming  col- 
onies of  second  generation  schizonts. 
Most  of  these  are  mature  by  66  hours 
after  infection.     They  measure  8  by  7  |i 
and  contain  8  to  16  merozoites  which 
measure  about  7  by  1.  5/i  and  have  the 
nucleus  near  the  center. 

Third  generation  schizonts  may  be 
recognized  as  early  as  72  hours  after 


224 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


infection  and  reach  maturity  at  about  96 
hours.    They  measure  about  8  by  7/i  and 
differ  from  the  second  generation  schi- 
zonts  in  having  a  residuum.     They  produce 
8  to  16  merozoites  which  measure  about 
7  by  1.  5ju  and  have  the  nucleus  much 
nearer  the  large  end  than  do  the  second 
generation  schizonts. 

Macrogametes  and  microgametocytes 
first  appear  114  hours  after  infection. 
They  measure  about  15  by  11  /i,  and  the 
microgametocytes  contain  a  rounded  res- 
iduum.   The  microgametes  have  2  long 
flagella. 

According  to  Hawkins  (1952),  the 
prepatent  period  is  6  days.     Clarkson 
(1959)  found  that  it  ranged  from  114  to  118 
hours  with  an  average  of  116  hours. 


The  duodenal  mucosa  occasionally  seems 
to  have  undergone  coagulation  necrosis, 
and  pieces  of  caseous  material  may  be 
scattered  in  the  lumen  of  the  entire  intes- 
tine along  with  a  large  amount  of  fluid 
which  may  have  a  pinkish  tinge.     The  re- 
mainder of  the  intestine  is  congested,  and 
petechial  hemorrhages  may  be  present  in 
the  mucosa  of  most  of  the  small  intestine. 

Regeneration  of  the  mucosa  begins  on 
the  6th  or  7th  day.    A  few  petechiae  are 
present  in  the  duodenum  and  jejunum,  and 
there  are  a  few  minute  streaks  of  hemor- 
rhage and  spotty  congestion  in  the  ileum. 
The  posterior  part  of  the  jejunum  and 
ileum  may  contain  greenish,   mucoid  casts 
5  to  10  cm  long  and  3  to  6  mm  in  diameter, 
and  necrotic  material  may  be  found  in  the 
ileum  or  feces. 


Pathogenesis:     This  species  is  mod- 
erately to  markedly  pathogenic,  causing 
catarrhal  enteritis.    The  death  rate  is 
high  in  young  poults  up  to  6  weeks  of  age, 
but  older  birds  are  more  resistant.     Haw- 
kins (1952)  found  that  infection  with 
50,000  sporulated  oocysts  produced  a  high 
mortality  in  young  poults,  in  some  in- 
stances killing  100%  of  2-  to  3- week-old 
poults.    Clarkson  and  Gentles  (1958)  and 
Clarkson  (1959)  observed  mortalities  of 
62%,  36%  and  0%,  respectively,  in  poults 
1.  5,  3  and  4  weeks  old  fed  100,  000  oocysts; 
of  40%  and  100%,   respectively,   in  4-week- 
old  poults  fed  300,  000  and  400,  000  oocysts; 
and  of  0%  in  5-  and  10-week-old  poults  fed 
200,  000  and  2  million  oocysts,   respec- 
tively.    Food  utilization  is  reduced  in  in- 
fected birds,  and  those  which  recover  do 
not  gain  weight  well  for  some  time. 

Lesions  first  appear  at  the  end  of  the 
4th  day  after  infection  (Hawkins,   1952; 
Clarkson  and  Gentles,  1958;  Clarkson, 
1959).     The  jejunum  is  slightly  thickened, 
dilated,  and  contains  an  excessive  amount 
of  clear,  colorless  fluid  or  mucus  contain- 
ing merozoites  and  small  amounts  of  blood 
and  other  cells.    Five  to  6  days  after  infec- 
tion the  duodenum  is  enlarged,  its  blood 
vessels  are  engorged,  and  it  contains  a 
reddish  brown,  necrotic  core  which  ad- 
heres firmly  to  the  mucosa  and  extends  a 
little  way  into  the  upper  small  intestine. 


Feed  consumption  begins  to  drop  2  to 
3  days  after  infection,  and  4  days  after 
infection  the  birds  huddle  together  with 
closed  eyes,  drooping  wings  and  ruffled 
feathers.     Their  droppings  at  this  time 
are  scanty  and  slightly  fluid.    At  the  peak 
of  the  disease,   5  to  6  days  after  infection, 
some  of  the  feces  form  cylinders  1  to  2 
cm  long  and  3  to  6  mm  in  diameter.    The 
droppings  are  not  bloody,  altho  a  few  flecks 
of  blood  may  occasionally  be  seen.    Death 
usually  occurs  5  to  7  days  after  infection. 

The  first  reaction  of  the  host  is  local 
infiltration  of  the  whole  intestine  with 
eosinophiles  (Clarkson,   1959).     This  begins 
within  2  hours  after  infection,   reaches  a 
maximum  in  1  to  2  days,  and  persists  at 
least  10  days.    There  are  no  striking  ab- 
normalities at  4  days,  but  at  5  days  many 
of  the  infected  villi  appear  to  have  lost 
their  tips,  all  the  duodenal  blood  vessels 
are  congested,  and  many  of  the  epithelial 
cells  around  the  villi  stain  poorly  and  ap- 
pear necrotic.     These  changes  are  present 
also  in  birds  which  die  on  the  6th  or  7th 
days,  but  resolution  is  rapid  in  recovered 
birds,  and  Clarkson  (1959)  saw  very  little 
abnormality  by  the  8th  day  except  for  in- 
creased cellularity  of  the  lamina  propria. 

Immunity:    According  to  Hawkins 
(1952), the  immunity  produced  by  infections 
with  this  species  is  not  as  solid  as  that 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


22S 


produced  by  E.  meleagridis ,  E.  dispersa 
and  E.  gallopavonis ,   but  it  is  still  con- 
siderable. 


EIMERIA  DISPERSA 
TYZZER,   1929 

Hosts:  Turkey,  bobwhite  quail,  ring- 
necked  pheasant,  ruffed  grouse  (?),  sharp- 
tailed  grouse  (?). 

This  species  was  first  described  by 
Tyzzer  (1929)  from  the  bobwhite  quail. 
He  also  found  it  in  the  ring-necked  pheas- 
ant.    Hawkins  (1952)  first  found  it  in  the 
turkey.     Boughton  (1937)  reported  it  from 
the  ruffed  grouse  (Eonasa  umbellus  )  and 
sharp-tailed  grouse  (Pedioecetes  pha- 
sianelhis  campestris).     Tyzzer  (1929) 
transmitted  it  from  the  bobwhite  to  the 
turkey,  chicken  (producing  a  light  infec- 
tion) and  possibly  to  the  pheasant.    Venard 
(1933)  and  Patterson  (1933)  were  unable 
to  infect  chickens  with  strains  from  the 
bobwhite.     Tyzzer  (1929)  transmitted  it 
from  the  pheasant  to  the  bobwhite.    Haw- 
kins (1952)  infected  the  bobwhite  and 
Hungarian  partridge  [Perdix  perdix)  with 
E.  dispersa  from  the  turkey,  but  was  un- 
able to  infect  the  pheasant  or  chicken. 
Moore  and  Brown  (1952)  infected  the  bob- 
white  with  a  turkey  strain,  but,  according 
to  Moore  (1954),  were  unable  to  infect  the 
pheasant. 

Location:     Primarily  duodenum,  but 
also  small  intestine. 


Geographic  Distribution: 
America. 


North 


Prevalence:     Presumably  relatively 
uncommon. 

Morphology:     The  morphology  of  this 
species  was  studied  especially  by  Tyzzer 
(1929)  and  Hawkins  (1952).    The  oocysts 
are  broadly  ovoid,  smooth,  22  to  31  by  18 
to  24  /J,  with  a  mean  of  26  by  21  /i .    The 
oocyst  wall  is  composed  of  a  single  layer 
and  lacks  a  micropyle.    An  oocyst  polar 
granule  and  oocyst  residuum  are  absent. 
The  sporocysts  are  ovoid,  with  a  Stieda 
body.    The  sporulation  time  is  2  days. 


Life  Cycle:     Tyzzer  (1929)  and  Haw- 
kins (1952)  studied  the  endogenous  stages 
of  this  species.    They  are  found  above  the 
nuclei  of  the  epithelial  cells  near  the  tips 
of  the  villi.    There  are  apparently  two 
types  of  first  generation  schizonts.    Much 
the  commoner  is  a  small  type  about  6  ji  in 
diameter  which  produces  15  or  fewer 
merozoites  each  4  to  6jj,  long  and  Ijj,  wide. 
The  other  type  measures  up  to  24  by  18 /j. 
and  produces  at  least  50  merozoites.    The 
first  generation  merozoites  are  formed  by 
the  end  of  the  second  day  of  infection. 

The  second  generation  schizonts  are 
about  11  to  13/j.  in  diameter  and  produce 
18  to  23  merozoites  each  5  to  6(i  long  and 
1.  5  to  2jLL  wide  about  4  days  after  infection. 

There  are  a  few  third  generation  schi- 
zonts and  merozoites,  but  most  of  the  sec- 
ond generation  merozoites  develop  into 
sexual  stages.    The  macrogametes  are  18 
to  20  ji  in  diameter  when  mature,  and  the 
microgametocytes  are  slightly  smaller. 
The  microgametes  have  2  flagella.    Oocysts 
first  appear  in  the  feces  late  on  the  fifth  or 
on  the  sixth  day  after  infection. 

Pathogenesis:     This  species  is  only 
slightly  pathogenic  in  the  turkey.    Hawkins 
(1952)  found  the  most  severe  lesions  on  the 
fifth  and  sixth  days  after  experimental  in- 
fection.   The  entire  small  intestine  was 
markedly  dilated  and  the  duodenum  and 
anterior  jejunum  were  creamy  white  when 
seen  thru  the  serosal  surface.    The  anter- 
ior half  of  the  small  intestine  was  filled 
with  creamy,  yellowish,  sticky,  mucoid 
material.    The  wall  of  the  anterior  intes- 
tine was  edematous,  but  there  was  little 
epithelial  sloughing.    The  intestinal  tract 
was  virtually  normal  by  the  eighth  day 
after  infection. 

The  only  signs  Hawkins  saw  in  infected 
turkeys  were  a  slight  tendency  to  produce 
somewhat  liquid  feces  and  a  slight  depres- 
sion in  weight  gains. 

Immunity;    According  to  Hawkins 
(1952),  turkeys  which  have  recovered 
from  infection  are  strongly  immune  to  re- 
infection. 


226 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


EIMERIA  GALLOPAVONIS 
HAWKINS,   1952 

Host:    Turkey. 

Hawkins  (1952)  transmitted  this  spe- 
cies experimentally  to  the  Hungarian 
partridge  but  not  to  the  pheasant  or  bob- 
white  quail.     Gill  (1954)  claimed  to  have 
transmitted  it  from  the  turkey  to  the 
chicken. 

Location:     Ileum,  rectum  and,  to  a 
lesser  extent,  ceca. 

Geographic  Distribution:     North 
America,  India. 

Prevalence:     Uncommon. 

Morphology:     This  species  was  des- 
cribed by  Hawkins  (1952,   1952a),  who  re- 
marked that  its  oocysts  cannot  be  differ- 
entiated with  any  certainty  from  those  of 
E.  meleagridis.     The  oocysts  are  ellip- 
soidal,  smooth,   22  to  33  by  15  to  19 /i 
with  a  mean  of  27  by  17 p.,  without  a 
micropyle.     An  oocyst  polar  granule  is 
present.     There  is  no  oocyst  residuum. 
The  sporocysts  are  ovoid,  with  a  Stieda 
body.    A  sporocyst  residuum  is  present. 
The  sporulation  time  is  1  day. 

Life  Cycle:     Hawkins  (1952)  des- 
cribed the  life  cycle  of  this  species.    The 
endogenous  stages  are  found  in  the  epithel- 
ial cells  at  the  tips  of  the  villi,  where  they 
lie  mostly  above  the  host  cell  nuclei.     The 
first  generation  schizonts  occur  in  the 
ileum  and  rectum.     They  produce  approx- 
imately 8  merozoites  and  a  residual  mass 
3  days  after  infection.     There  are  appar- 
ently two  sizes  of  second  generation  schi- 
zonts.    The  smaller  ones  occur  in  the 
rectum,   ileum  and  rarely  in  the  ceca. 
They  produce  10  to  12  merozoites  and  a 
residual  mass  4  to  5  days  after  infection. 
The  larger  second  generation  schizonts 
occur  only  in  the  rectum.    They  are  20  ji 
in  diameter  and  produce  a  large,  unde- 
termined number  of  merozoites  4  days 
after  infection. 

There  are  a  few  third  generation 
schizonts  and  merozoites  in  the  rectum. 


They  produce  about  10  to  12  merozoites. 
These  and  most  of  the  second  generation 
merozoites  develop  into  sexual  stages. 
These  are  found  primarily  in  the  rectum 
and  only  occasionally  in  the  ileum  and  ceca. 
The  macrogametes  and  microgametocytes 
are  similar  to  those  of  other  turkey  proto- 
zoa.   Some  oocysts  are  passed  in  the  feces 
on  the  sixth  day  after  infection,  but  most 
appear  on  the  seventh  day. 

Pathogenesis:      Little  is  known  of  the 
pathogenicity  of  this  species.     Hawkins 
(1952)  noted  marked  edema,   sloughing  and 
lymphocytic  infiltration  in  the  intestines, 
but  did  not  have  sufficient  material  to 
make  a  thoro  study. 

Immunity:     According  to  Hawkins 
(1952),   infection  with  E.  gallopaionis  pro- 
duces a  more  solid  immunity  than  that 
elicited  by  £.  meleagridis,  E.  meleagri- 
milis  or  E.  dispersa. 


EIMERIA  ADENOEIDES 
MOORE  AND  BROWN,   1951 

Host:     Turkey. 

Moore  and  Brown  (1951)  were  unable 
to  transmit  this  species  to  the  chicken, 
guinea  fowl,   ringnecked  pheasant  or  bob- 
white  quail.     Clarkson  (1959a)  was  unable 
to  transmit  it  to  the  chicken. 

Location:     The  first  generation  schi- 
zonts (Clarkson,   1958)  occur  in  the  neck 
of  the  ceca  and  in  the  terminal  inch  or  so 
of  the  ileum,  where  80%  of  them  lie  below 
the  host  cell  nuclei  of  the  epithelial  cells. 
The  second  generation  schizonts  occur 
thruout  the  ceca,  and  some  are  found  in  the 
rectum  and  posterior  ileum.     They  lie  above 
the  host  cell  nuclei  of  the  epithelial  cells, 
just  beneath  the  brush  border.     The  sexual 
stages  occur  thruout  the  ceca,  rectum  and 
posterior  third  of  the  small  intestine.     A 
few  are  found  even  more  anteriorly,  but 
none  more  than  halfway  to  the  yolk  sac 
stalk.     They  invade  the  epithelial  cells  of 
the  crypts  and  deep  glands,  a  location  which 
distinguishes  them  from  E.  meleagridis 
and  E.  gallopavonis,   and  also  apparently 
the  epithelial  cells  of  the  villi.    Clarkson 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


227 


(1958)  illustrated  them  as  lying  above  the 
host  cell  nuclei. 


Geographic  Disti'ibution: 
America,  Great  Britain. 


North 


Prevalence:     Quite  common.     Fifteen 
out  of  22  outbreaks  studied  by  Clarkson 
and  Gentles  (1958)  in  Great  Britain  were 
caused  by  this  species  and  3  by  a  mixture 
of  it  and  E.  iiieleagriniitis. 

Morphology:     The  oocysts  have  been 
described  by  Moore  and  Brown  (1951)  and 
Clarkson  (1958).     They  are  similar  to 
those  of  E.  ))ieleagridis  and  E.  gallopa- 
vonis.    They  are  ellipsoidal,   sometimes 
ovoid,   smooth,  19  to  31  by  13  to  21  fi  with 
a  mean  of  26  by  17 /i.    A  micropyle  is 
sometimes  present.     One  to  3  oocyst  polar 
granules  are  present.     An  oocyst  residuum 
is  absent.     The  sporocysts  are  elongate 
ovoid,  apparently  with  a  Stieda  body.     A 
sporocyst  residuum  is  present.     The  sporo- 
zoites  contain  a  clear  globule  at  the  large 
end.     The  sporulation  time  is  1  day.     Edgar 
(1955)  found  sporulated  oocysts  as  early  as 
18  hours  at  29°  C. 

Life  Cycle:     Clarkson  (1958)  studied 
the  life  cycle  of  this  species,  using  a 
strain  derived  from  a  single  oocyst.    First 
generation  schizonts  can  be  found  in  the 
epithelial  cells  as  early  as  6  hours  after 
infection.     They  become  mature  60  hours 
after  infection;  by  66  hours  most  of  them 
have  released  their  merozoites,  altho  a 
few  remain  up  to  84  hours.     The  mature 
first  generation  schizonts  measure  30  by 
18  |i  and  contain  about  700  merozoites 
measuring  4.  5  to  7  by  1 .  5  fi ,  with  a  central 
nucleus. 

The  second  generation  schizonts  be- 
come mature  96  to  108  hours  after  infec- 
tion.    They  measure  10  by  lOjj  and  contain 
12  to  24  merozoites  measuring  about  10  by 
3|j.,  with  the  nucleus  a  little  nearer  the 
rounded  than  the  pointed  end. 

Sexual  stages  can  be  found  as  early  as 
114  hours  and  recognized  as  early  as  120 
hours  after  infection.     The  mature  macro- 
gametes  measure  about  20  by  18 /i  and  con- 
tain many  large,  plastic  granules  which 


f.tain  black  with  Heidenhain's  hematoxylin. 
The  mature  microgametocytes  are  about 
the  same  size  as  the  macrogametes. 

The  prepatent  period  was  given  by 
Moore  and  Brown  (1951)  as  112  hours. 
Edgar  (1955)  found  oocysts  in  the  feces  as 
early  as  104  hours,  and  Clarkson  (1958) 
found  that  the  prepatent  period  varied  from 
114  to  132  hours  in  30  birds. 

The  patent  period  is  7  to  8  days  accord- 
ing to  Moore  and  Brown  (1951).     Clarkson 
(1958)  found  that  very  few  oocysts  were 
passed  more  than  14  days  after  infection, 
and  none  after  the  20th  day. 

Pathogenesis:     This  species  is  highly 
pathogenic.    Moore  and  Brown  (1951)  were 
able  to  kill  100%  of  experimental  poults  up 
to  5  weeks  of  age  with  large  doses  of  spor- 
ulated oocysts.     Older  poults  developed  a 
severe  enteritis  with  few  or  no  deaths. 
Clarkson  (1958)  and  Clarkson  and  Gentles 
(1958)  observed  mortalities  of  0%,  0%, 
45%  and  100%,   respectively,   in  3-week-old 
poults  fed  10,000,  25,000,   100,  000  and 
200,000  oocysts;  of  33%  in  6-week-old 
poults  fed  1  million  oocysts;  and  of  0%  in 
11 -week-old  poults  fed  3  million  oocysts. 
Birds  which  did  not  die  had  decreased  food 
consumption  and  weight  gains. 

Poults  develop  signs  of  anorexia, 
droopiness  and  ruffled  feathers  during  the 
4th  day  after  experimental  infection.    If 
death  occurs,  it  is  usually  on  the  5th  or 
6th  days  but  may  be  a  little  later  (Moore 
and  Brown,   1951). 

The  gross  lesions  have  been  studied 
by  Moore  and  Brown  (1951),   Clarkson 
(1958)  and  Clarkson  and  Gentles  (1958). 
The  intestines  appear  quite  normal  until 
the  4th  day.    The  walls  of  the  lower  third 
of  the  small  intestine,   ceca  and  rectum 
become  swollen  and  edematous,   petechial 
hemorrhages  which  are  visible  from  the 
mucosal  but  not  from  the  serosal  surface 
appear,  and  the  lower  intestine  becomes 
filled  with  mucus. 

During  the  5th  day,  most  of  the  ter- 
minal intestine  is  congested  and  contains 
large  numbers  of  merozoites  and  long 


228 


THE  TELOSPORASIDA   AND  THE  CCXCIDIA   PROPER 


streaks  of  blood.     By  the  end  of  the  day, 
the  intestine  contains  caseous  material 
composed  of  cellular  debris,   gametes, 
and  a  few  immature  oocysts.     A  little  later 
the  caseous  exudate  is  composed  largely 
of  oocysts.    The  feces  in  severe  cases  are 
relatively  fluid  and  may  be  blood-tinged 
and  contain  mucous  casts  1  to  2  inches  long. 
Caseous  plugs  are  sometimes  present  in 
the  ceca. 


Since  E.  adenoeides  is  found  in  the  same 
locations  as  E.  meleagridia  and  E.  gal- 
lopavonis,  and  since  its  oocysts  are  ap- 
parently similar  to  theirs,  this  lack  of 
reciprocal  immunity  is  an  important  dif- 
ferentiating criterion.     The  only  other  dif- 
ferences are  its  greater  pathogenicity  ancj 
its  location  in  the  crypts  and  deep  glands 
rather  than  only  in  the  tips  of  the  villi. 


On  the  6th  to  8th  days  in  birds  infected 
with  10,000  oocysts,  the  terminal  intestine 
contains  white,  creamy  mucus,  and  pete- 
chiae  are  present  in  the  mucosa.     By  the 
9th  day  the  intestinal  contents  appear  nor- 
mal, altho  they  still  contain  large  numbers 
of  oocysts  (Clarkson,  1958). 

Infiltration  with  eosinophiles  commen- 
ces as  early  as  2  hours  after  infection, 
and  enormous  numbers  of  eosinophiles 
may  be  found  in  the  terminal  small  intes- 
tine, ceca  and  rectum  from  the  3rd  to  the 
10th  days. 

Beginning  4  days  after  infection,  ed- 
ematous changes  are  seen  in  the  intestine, 
and  infected  epithelial  cells  begin  to  break 
off,  leaving  the  villi  denuded.    The  blood 
vessels  become  engorged,  and  cellular 
infiltration  of  the  submucosa  and  epithel- 
ial denudation  increase  progressively  until 
the  6th  day.    In  birds  which  recover  from 
the  disease  or  which  have  received  rela- 
tively few  oocysts,   resolution  is  very 
rapid.    Vascularity  is  greatly  reduced, 
the  deep  glands  are  almost  free  of  para- 
sites by  the  7th  day,  and  the  intestine  is 
almost  normal  by  the  9th  or  10th  day 
(Clarkson,   1958). 

Clarkson  (1958)  found  no  changes  in 
the  blood  picture  of  infected  poults. 

Immunity:     Moore  and  Brown  (1951) 
produced  solid  immunity  to  E.  adenoeides 
by  infecting  turkey  poults  with  25  doses  of 
sporulated  oocysts  over  a  period  of  2 
months.    These  birds  were  not  immune  to 
E.  meleagridis .     Conversely,  poults  which 
had  been  immunized  against  E.  meleagridis 
were  not  immune  to  E.  adenoeides.    Clark- 
son (1959a),  too,  found  no  cross  immunity 
between  E.  meleagridis  and  E.  adenoeides . 


EIMERIA  INNOCUA 
MOORE  AND  BROWN,   1952 

Host:     Turkey. 

Moore  and  Brown  (1952)  were  unable 
to  infect  the  chicken,  guinea  fowl,   ring- 
necked  pheasant  and  bobwhite  quail  with 
E.  innocua. 

Location:     Thruout  the  small  intestine. 


Geographic  Distribution: 
America  (New  York). 


North 


Prevalence:     Apparently  uncommon. 

Morphology:     The  oocysts  of  this 
species  were  described  by  Moore  and 
Brown  (1952).     They  are  subspherical, 
smooth,   19  to  26  by  17  to  25  ji  with  a  mean 
of  22  by  21  ^t,  and  without  a  micropyle  or 
oocyst  polar  granule.    No  other  morpho- 
logical information  was  given.    The  sporu- 
lation  time  is  2  days. 

Life  Cycle:     Unknown.     The  endogen- 
ous stages  occur  in  the  epithelial  cells  of 
the  villi.     The  tips  of  the  villi  are  most 
heavily  parasitized,  while  the  crypts  and 
deep  glands  are  never  affected.    According 
to  Moore  and  Brown  (1952),  oocysts  first 
appear  in  the  feces  5  days  after  infection, 
and  the  patent  period  is  up  to  9  days. 

Pathogenesis:     This  species  is  non- 
pathogenic according  to  Moore  and  Brown 
(1952).    They  observed  no  macroscopic 
lesions,   even  in  heavy  infections;  poults 
less  than  5  weeks  old  showed  no  signs  of 
illness  and  had  no  diarrhea. 

Immunity:     Moore  and  Brown  (1952) 
immunized  turkey  poults  by  infecting  them 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


229 


with  4  to  7  doses  of  oocysts  over  a  period 
of  22  to  29  days.     The  immunized  birds 
were  not  immune  to  E.  dispersa,  the 
species  which  E.   innocua  most  closely 
resembles,  and  turkeys  immunized  against 
E.  dispersa  were  susceptible  to  infection 
with  E.   innocua. 


EIMERIA  SUBROTUNDA 

MOORE,  BROWN  AND  CARTER,   1954 

Host:     Turkey. 

Moore,   Brown  and  Carter  (1954)  were 
unable  to  infect  the  chicken,  guinea  fowl, 
ringnecked  pheasant  or  bobwhite  quail  with 
this  species. 

Location:     Duodenum,  jejunum  and 
upper  ileum  as  far  as  2  inches  anterior  to 


the  yolk  stalk  rudiment. 

Geographic  Distribution: 
America. 


North 


Prevalence:     Apparently  uncommon. 

Morphology:     This  species  closely 
resembles  E.   innocua,  according  to 
Moore,  Brown  and  Carter  (1954).    The 
oocysts  are  subspherical,  smooth,   16  to 
26  by  14  to  24  jj.  with  a  mean  of  22  by  20  ji , 
without  a  micropyle  or  polar  granule.     No 
other  morphological  information  was  given. 
The  sporulation  time  is  48  hours. 

Life  Cycle:     Unknown.    According  to 
Moore,  Brown  and  Carter  (1954),  the  en- 
dogenous stages  occur  in  the  epithelial 
cells  of  the  tips  of  the  villi,  extend  along 
the  sides  of  the  villi  to  some  extent,  but 
never  invade  the  crypts  and  deep  glands. 
Oocysts  first  appear  in  the  feces  96  hours 
after  infection,  and  the  patent  period  is  12 
to  13  days. 

Pathogenesis:     This  species  is  appar- 
ently non- pathogenic.    Moore,  Brown  and 
Carter  (1954)  observed  no  signs  of  infec- 
tion, diarrhea  or  gross  lesions  in  poults 
less  than  5  weeks  old  which  had  been  in- 
fected with  massive  doses  of  sporulated 
oocysts. 


Immunity:     Moore,   Brown  and  Carter 
(1954)  immunized  turkey  poults  by  feeding 
them  10,000  to  15,000  sporulated  oocysts 
every  4  days  until  they  ceased  to  shed 
oocysts;  this  occurred  in  less  than  a  month. 
Poults  which  had  been  immunized  against 
E.  subrotunda  were  not  immune  to   E. 
innocua  and  E.  dispersa,  and  poults  which 
had  been  immunized  against  the  latter  two 
species  were  not  immune  to  E.  subrotunda. 
This  was  the  primary  basis  for  separating 
E.  subrotunda  from  E.   innocua. 


COCCIDIOSIS   IN   TURKEYS 

Epidemiology:     Coccidiosis  in  turkeys 
has  been  discussed  by  Morehouse  (1949), 
Hawkins  (1952),  Moore  (1954)  and  Becker 
(1959)  among  others.    The  U.  S.  Dept.  of 
Agriculture  (1954)  estimated  that  it  caused 
an  annual  loss  of  $466,000  from  1942  to 
1951,  and  it  is  becoming  of  increasing  im- 
portance to  the  turkey  grower. 

Of  the  7  species  of  Eimeria,  1  of 
Isospora  and  1  of  Cryptosporidium  reported 
from  turkeys,  by  far  the  most  important 
are  E.  meleagriniitis  and  E.  adenoeides. 
The  former  affects  the  jejunum  and  the 
latter  the  lower  ileum,   ceca  and  rectum. 

Coccidiosis  is  primarily  a  disease  of 
young  birds.     Older  birds  are  carriers. 
Poults  become  infected  by  ingesting 
oocysts  along  with  their  feed  or  water. 
The  severity  of  the  disease  depends  on  the 
number  of  oocysts  they  receive.    If  they 
ingest  relatively  few,  they  may  develop 
immunity  without  ever  showing  signs  of 
illness,  while  if  they  ingest  large  numbers, 
they  may  become  seriously  ill  or  die. 
Crowding  and  lack  of  sanitation  greatly 
increase  the  disease  hazard. 

Diagnosis:     Coccidiosis  of  turkeys 
can  be  diagnosed  in  the  same  way  as  coc- 
cidiosis of  chickens  by  finding  endogenous 
stages  of  the  coccidia  in  scrapings  of  the 
affected  parts  of  the  intestinal  tract  of 
birds  which  show  signs  of  the  disease. 
The  mere  presence  of  coccidia  in  the  ab- 
sence of  disease  cannot  be  relied  on.  Since 
several  species  of  turkey  coccidia 


230 


THE  TELOSPORASIDA    AND  THE  COCCIDIA   PROPER 


(E.   innociia,   E.  subyolunda  a.nd  E.  niele- 
agridis  in  particular)  are  non- pathogenic 
or  nearly  so,  they  must  be  differentiated 
from  the  pathogenic  E.  nieleagriiuUis 
and  E.  adenoeides.    The  sporulated  oocysts 
of  both  the  latter  have  polar  bodies,  which 
differentiates  them  from  all  but  E.  Diele- 
agridis  and  E.  gallopavonis .     The  oocysts 
of  E.  »ielecigyi»iilis  are  ellipsoidal,  but 
apparently  only  pathogenesis  and  absence 
of  cross-immunity  differentiates  E. 
adenoeides  from  the  other  two.     This  last 
is  hardly  a  practical  diagnostic  test,  since 
it  requires  a  colony  of  turkeys  immunized 
against  the  various  species. 

Treatment:     The  sulfonamides  are 
effective  against  a  number  of  the  turkey 
coccidia.     Morehouse  (1949a)  found  that 
only  one  of  6  sulfonamides  was  ineffective 
against  E.  nieleagridis.     Peterson  (1949a) 
found  that  several  sulfonamides  were  ef- 
fective against  E.  nieleagriniitis.     Moore 
(1949)  found  that  0.031%  sulfaquinoxaline, 
1%  sulfaguanidine  or  0.  5%  sulfamerazine 
in  the  feed  was  effective  against  turkey 
coccidiosis.     Wilson  (1951)  reported  that 
0.  06%  sodium  sulfaquinoxaline  in  the 
drinking  water  stopped  losses  from  E. 
nieleagridis  and  E.  Dieleagriniltis  in  a 
natural  outbreak.    (Their  cultures  oiE. 
nieleagridis  may  have  contained  E. 
adenoeides,  a  species  which  had  not  yet 
been  named  at  the  time.  )    Boyer  and 
Brown  (1953)  found  that  0.0175%  acetyl- 
sulfaquinoxaline  in  the  feed  or  1-1000  to 
1-2000  sulfamethazine  in  the  water  was 
effective  against  E.  adenoeides,  E.  gal- 
lopavonis, E.  meleagridis,  E.   innocua, 
E.  subrotunda,  E.  dispersa  andE.  mele- 
agrimitis.     Horton-Smith  and  Long  (1959) 
found  that  0.0125%  sulfaquinoxaline  in  the 
feed  was  effective  against  E.  nieleagri- 
mitis. 

Other  coccidiostats  used  in  treating 
chickens  have  not  been  found  so  useful  in 
turkeys.     Morehouse  (1949)  found  that 
sodium  4-chlorophenyl  arsonate  was  the 
most  effective  of  10  organic  arsenic  com- 
pounds to  be  tested  against  E.  meleagri- 
dis, but  that  its  effective  dose  was  too 
close  to  the  toxic  one.    Another  organic 
arsenic  compound,   3-nitro-4-hydroxy- 
phenyl  arsonic  acid  was  of  less  value. 


Boyer  and  Brown  (1953)  found  that 
nitrophenide,   2-amino-5-nitrothiazole, 
sulfisoxazole,  nitrofurazone  and  furoxone 
were  not  effective  coccidiostatic  agents  in 
the  turkey.    Cuckler  et  at.  (1955)  reported 
that  nicarbazin  was  effective  against  E. 
galloparonis  and  E.   nteleagrimitis,  but 
Horton-Smith  and  Long  (1959)  found  that 
it  was  ineffective  against  £.  nieleagrimilis 
and  in  addition  found  that  nitrofurazone  and 
glycarbylamide  were  also  ineffective 
against  this  species. 

Prevention  and  Control:    The  same 
measures  should  be  used  for  the  prevention 
and  control  of  coccidiosis  in  turkeys  as  in 
chickens. 

EIMERIA    TRUNCATA 
(RAILLIET  AND   LUCET,    1891) 
WASIELEWSKI,    1904 

Synonym:      Coccidium  truncatum. 

Hosts:     Domestic  goose,  greylag 
goose  {Anser  anser),  Ross's  goose  {A. 
rossi),  Canada  goose  {Branta  ca>iadensis) 
(see  Levine,   1953;  Hanson,   Levine  and 
Ivens,   1957).     In  addition  to  these,   Pavlov 
(1942)  reported  finding  E.  truncata  in 
domestic  ducks  in  Bulgaria,  and  Christian- 
sen (1948,   1952)  found  oocysts  resembling 
E.  truncata  but  smaller  in  the  kidneys  of 
young  swans  {Cygniis  olor)  and  common 
eiders  [Soniateria  niollissima)  in  Denmark. 

Location:     Kidneys. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Relatively  uncommon  in 
domestic  geese,  at  least  in  North  America. 

Morphology:     This  species  has  been 
described  by  Kotlan  (1933)  and  Lerche 
(1923)  among  others.     The  oocysts  are 
ovoid,  with  a  narrow,  truncate,   small 
end,  and  measure  14  to  27  by  12  to  22  fi. 
The  oocyst  wall  is  smooth  and  delicate, 
shrinking  quickly  during  concentration  in 
hypertonic  solutions.    A  micropyle  with  a 
polar  cap  is  present.    An  oocyst  residuum 
is  sometimes  present.    A  sporocyst  resi- 
duum is  present.    The  sporulation  time  is 
1  to  5  days. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


231 


Life  Cycle:     The  endogenous  stages 
occur  in  the  epithelial  cells  of  the  kidney 
tubules.    The  life  cycle  has  not  been 
studied  in  detail.     The  prepatent  period  is 
5  to  6  days  according  to  Kotlan  (1933). 

Pathogenesis:     E.   truncata  is  highly 
pathogenic  for  goslings,  sometimes  wiping 
out  whole  flocks  within  a  few  days.     The 
disease  is  usually  acute,  lasting  only  2  or 
3  days.     Affected  birds  are  extremely 
weak  and  emaciated.    Their  kidneys  are 
greatly  enlarged,  light-colored,  with 
small,  yellowish  white  nodules,   streaks 
and  lines  on  the  surface  and  thruout  the 
parenchyma.     The  infected  epithelial  cells 
are  destroyed,  and  adjacent,  uninfected 
cells  are  also  destroyed  by  pressure. 
The  infected  tubules  are  so  filled  with 
urates  and  oocysts  that  they  are  enlarged 
to  5  to  10  times  the  diameter  of  normal 
tubules. 

Epidemiology:     E.   truncata  occurs 
only  sporadically  in  domestic  geese  in 
North  America.    It  was  first  described  in 
the  United  States  by  McNutt  (1929)  in 
Iowa,  and  has  since  been  reported  by 
Allen  (1933)  in  Washington,  D.  C,  Adler 
and  Moore  (1948)  in  Washington  state, 
Levine,   Morrill  and  Schmittle  (1950)  in 
Illinois,   Lindquist,   Belding  and  Hitchcock 
(1951)  in  Michigan,   Farr  and  Wehr  (1952) 
in  Maryland,  and  McGregor  (1952)  in 
Ontario.    It  has  also  been  found  in  New 
York  and  Quebec. 

The  epidemiology  of  E.  truncata  in 
wild  geese  is  especially  interesting  (Han- 
son,  Levine  and  Ivens,   1957).    It  has 
been  found  in  the  greylag  goose  {Anser 
anser)  in  Europe  by  Christiansen  and 
Madsen  (1948),  and  in  Ross's  goose  {A. 
rossi)  and  the  Canada  goose  {Branta  cana- 
densis) in  North  America.     However,  of 
the  6  wild  goose  flyways  which  form  ver- 
tical bands  across  North  America,  E. 
truncata  has  been  found  only  in  the  South 
Atlantic  and  Pacific  flyways,  and  not  from 
the  flyways  in  between.    It  is  common 
among  Canada  geese  of  the  South  Atlantic 
flyway,  and  has  been  associated  with 
losses  at  their  winter  quarters  at  Pea 
Island,  North  Carolina  (Critcher,   1950). 
Its  apparent  absence  from  wild  geese  in 


the  interior  flyways  does  not  seem  due  to 
the  examination  of  too  few  birds,  since 
Hanson,   Levine  and  Ivens  (1957)  failed  to 
find  it  in  258  wild  geese  from  these  fly- 
ways altho  they  recognized  it  in  birds  from 
both  coasts.     Perhaps  E.  truncata  was 
originally  a  parasite  of  greylag  and  domes- 
tic geese  in  Eurasia  and  has  reached  North 
American  wild  geese  relatively  recently, 
entering  from  both  the  east  and  west. 


EIMERIA  ANSERIS 
KOTLAN,   1932 

Hosts:     Domestic  goose,  blue  goose 
(Anser  caerulescens),   Richardson's 
Canada  goose  {Branta  canadensis  hutch- 
ins  i). 

Location:     Small  intestine,  mainly 
posterior  part. 

Geographic  Distribution:     Europe, 
North  America. 

Prevalence:    E.  anser  is  has  been 
reported  from  domestic  geese  only  in 
Europe  (Kotlan,   1933;  Cerna,   1956)  and 
is  apparently  not  particularly  common 
there.     Hanson,   Levine  and  Ivens  (1957) 
found  it  in  4%  of  73  blue  geese  from  Ft. 
Severn  and  Weenusk,  Ontario  and  in  33% 
of  6  Richardson's  Canada  geese  from 
York  Factory,  Manitoba. 

Morphology:     This  species  was  des- 
cribed in  detail  by  Hanson,  Levine  and 
Ivens  (1957).    The  oocysts  have  the  form 
of  a  sphere  surmounted  by  a  truncate 
cone,  with  a  micropyle  at  the  truncate  end, 
and  measure  20  to  24  by  16  to  19 /i  with  a 
mean  of  22  by  11  \x  (16  to  23  by  13  to  18 /i 
according  to  Kotla'n,   1933).    The  oocyst 
wall  is  smooth,  colorless,  composed  of  a 
single  layer  about  1  \i  thick,  and  slightly 
thickened  around  the  micropyle  but  incised 
sharply  to  form  a  plate  or  shelf  across  the 
micropyle  itself.    The  oocyst  residuum  is 
a  mass  of  amorphous  material  just  beneath 
the  micropyle  and  forming  a  seal  beneath 
it.    An  oocyst  polar  granule  is  absent. 
The  sporocysts  are  ovoid  and  almost  com- 
pletely fill  the  oocyst.    The  sporocyst 
wall  is  slightly  thickened  at  the  small  end. 


232 


THE  TELOSPORASIDA  AND  THE  COCCIDW   PROPER 


The  sporocysts  are  10  to  12  by  7  to  9 /i. 
A  sporocyst  residuum  is  present.     The 
sporozoites  often  lie  more  or  less  trans- 
versely at  the  anterior  and  posterior  ends 
of  the  sporocyst.     The  sporulation  time  is 
1  to  2  days  according  to  Kotlan  (1933). 

Life  Cycle:     The  endogenous  stages 
have  been  described  by  Kotlan  (1933). 
They  occur  in  compact  clumps  under  the 
intestinal  epithelium  near  the  muscularis 
mucosae  and  also  in  the  epithelial  cells  of 
the  villi.     The  schizonts  are  spherical, 
12  to  20  ji  in  diameter,  and  contain  15  to 
25  slightly  curved,  crescent-shaped  mero- 
zoites.     There  is  probably  only  a  single 
asexual  generation.    The  sexual  stages 
are  found  mostly  in  the  subepithelial  tis- 
sues of  the  villi,  but  invade  the  epithelium 
in  heavy  infections.     The  macrogametes 
measure  12  to  16  by  10  to  15 /i.    The  mi- 
crogametocytes  are  spherical  and  about 
the  same  size.    Oocysts  first  appear  in 
the  feces  7  days  after  infection,  and  the 
patent  period  is  2  to  8  days. 

Pathogenesis:     Kotlan  (1933)  reported 
that  experimental  infections  in  2.5-  to 
3-month-old  geese  were  harmless,  but 
described  two  outbreaks  of  intestinal  coc- 
cidiosis  in  goslings  which  he  considered 
due  to  a  combination  of  E.  anseris  and 
E.  nocens. 


EIMERIA  NOCENS 
KOTLAN,   1933 

Hosts:     Domestic  goose,  blue  goose 
{Anser  caerulescens). 

Location:      Posterior  part  of  small 
intestine. 

Geographic  Distribution:      Europe, 
North  America. 


Morphology:     The  sporulated  oocysts 
were  described  by  Hanson,  Levine  and 
Ivens  (1957).     They  are  ovoid  but  flattened 
at  the  micropylar  end,   29  to  33  by  19  to 
24 /i  with  a  mean  of  31  by  22 /i  (25  to  33  by 
17  to  24  |i  according  to  Kotlan,   1933).    The 
oocyst  wall  is  smooth  and  composed  of  2 
layers,  the  outer  one  1.  Sji  thick  and  pale 
yellow,  the  inner  one  0.9(1  thick  and  al- 
most colorless.    A  prominent  micropyle 
is  present.    A  true  micropylar  cap  is  ab- 
sent, but  the  micropyle  appears  to  be 
present  only  in  the  inner  wall  and  is  cov- 
ered by  the  outer  wall.    An  oocyst  polar 
granule  and  oocyst  residuum  are  absent, 
but  part  of  the  oocyst  wall  often  forms  one 
or  more  roundish  protuberances  just  below 
the  micropyle.    The  sporocysts  are  broadly 
ellipsoidal,  with  a  thin  wall  and  sometimes 
with  a  very  small  Stieda  body.     The  sporo- 
cysts are  10  to  14  by  8  to  IOjll  with  a  mean 
of  12  by  9 /J..    The  sporozoites  usually  lie 
head  to  tail  in  the  sporocysts  and  contain 
2  or  more  large,   clear  globules  which  al- 
most obscure  their  outline.    The  sporocyst 
residuum  fills  the  space  between  sporo- 
zoites. 


Life  Cycle:     According  to  Kotlan 
(1933),  the  endogenous  stages  are  found 
primarily  in  the  epithelial  cells  at  the  tips 
of  the  villi,  but  they  may  also  occur  be- 
neath the  epithelium.     The  younger  devel- 
opmental stages  lie  near  the  host  cell  nu- 
clei, but  as  they  grow  they  not  only  dis- 
place the  nuclei  but  also  destroy  the  host 
cell  and  come  to  lie  free  and  partly  be- 
neath the  epithelium.     The  schizonts  are 
spherical,   15  to  30 fi  in  diameter,  and  con- 
tain 15  to  35  merozoites.     The  macroga- 
metes are  usually  ellipsoidal  or  irregularly 
spherical,  uniformly  coarsely  granular, 
and  measure  20  to  25  by  16  to  21  /j, .     The 
microgametocytes  are  spherical  or  ellip- 
soidal and  measure  28  to  36  by  23  to  31  ji. 


Prevalence:     E.  nocens  has  been  re- 
ported from  the  domestic  goose  only  in 
Europe  (Kotlan,   1933;  Cerna,   1956),  and 
is  apparently  not  particularly  common 
there.     Hanson,   Levine  and  Ivens  (1957) 
found  it  in  blue  geese  from  Ft.  Severn 
and  Weenusk,  Ontario. 


Pathogenesis:     Kotlan  (1933)  described 
2  outbreaks  of  intestinal  coccidiosis  in 
goslings  in  Hungary  in  which  he  found  both 
E.  nocois  and  E.  anseris.     Since  the  latter 
is  apparently  non- pathogenic,  the  disease 
was  presumably  due  to  E.  nocens. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


233 


EIMERIA   PARVULA 
KOTLAN,   1933 

Host:     Domestic  goose. 

Location:     Small  intestine,   primarily 
posterior  part. 

Geographic  Distribution:     Europe. 

Prevalence:     This  species  is  com- 
mon in  geese  in  Hungary,  according  to 
Kotlah  (1933). 

Morphology:     This  species  was  des- 
cribed by  Kotlin  (1933).     The  oocysts  are 
spherical  or  subspherical,  smooth,  color- 
less, delicate,   10  to  15  by  10  to  14  p., 
without  a  micropyle.     No  other  morpho- 
logical details  were  given. 

Life  Cycle:     Unknown.     According  to 
Kotlan  (1933),  the  endogenous  stages  are 
found  almost  exclusively  in  the  epithelial 
cells  of  the  villi.     Oocysts  first  appear  in 
the  feces  5  days  after  infection. 

Pathogenesis:     According  to  Kotlan 
(1933),  this  species  is  non- pathogenic. 


EIMERIA  ANATIS 
SCHOLTYSECK,   1955 

Host:     Wild  mallard  (Anas  platyrhyn- 
chos).    Scholtyseck  did  not  find  this  spe- 
cies in  6  domestic  ducks,  which  he  called 
A.  domes tica. 

Location:     Small  intestine. 

Geographic  Distribution:     Europe 
(Germany). 

Prevalence:     Scholtyseck  (1955)  found 
this  species  in  5  of  32  wild  mallards. 

Morphology:     The  oocysts  are  ovoid, 
14  to  19  by  11  to  16fi  with  a  mean  of  17 
by  14 /J..     The  oocyst  wall  is  smooth,  about 
0.  7  to  1.0 /i'  thick,  with  a  thickened  ring 
forming  shoulders  around  the  micropyle. 
An  oocyst  residuum  and  polar  granule  are 
absent.     The  sporocysts  are  elongate 
ovoid  or  ellipsoidal,  with  a  slight  thicken- 


ing at  the  small  end  but  not  a  true  Stieda 
body.    A  few  sporocyst  residual  granules 
are  present  between  the  sporozoites. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     Tiboldy  (1933)  reported 
Eimeria  sp.  oocysts  in  domestic  ducks  in 
Hungary.     They  were  ovoid,  elongate  ovoid 
or  occasionally  spherical  are  measured  11 
to  25  by  8  to  13 /i  .     Their  relationship  to 
E.  anatis  is  unknown. 


EIMERIA   LABBEANA 
PINTO,    1928 

Synonyms:     Coccidium  pfeifferi, 
Ewieria  pfeifferi,  Eimeria  coliimbarum. 

Hosts:     Domestic  pigeon,   ring  dove 
(ColiDuba  palumbus),  turtle  dove  (Strep- 
topelia  turtur),  Streptopelia  orientalis 
meena  (see  Scholtyseck,   1956). 

Location:     Small  and  large  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common. 

Morphology:     The  oocysts  are  sub- 
spherical  to  spherical,   colorless  or 
slightly  yellowish  brown,   13  to  24  by  12  to 
23jLi.     The  oocyst  wall  is  composed  of  2 
layers,  the  inner  one  darker  than  the  outer. 
There  is  no  micropyle.    An  oocyst  polar 
granule  is  present.    An  oocyst  residuum 
is  absent.    The  sporocysts  are  elongate 
ovoid,  with  a  Stieda  body.    A  sporocyst 
residuum  is  present.     The  sporozoites  lie 
lengthwise,  head  to  tail,  in  the  sporocysts. 
They  are  slightly  crescent-shaped,  with 
one  end  wider  than  the  other,  a  vacuole  at 
each  end  and  the  nucleus  near  the  middle. 

Nieschulz  (1935)  separated  this  species 
into  two  on  the  basis  of  size.     He  retained 
the  name  E.  labbeana  for  the  smaller  form, 
which  measured  13  to  24  by  12  to  22  jn 
(usually  15  to  18  by  14  to  16jj,)  with  a  mean 
of  18  by  15(i.     He  named  the  larger  form 
E.  columbarum ;  it  measured  17  to  24  by 


234 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


Fig.  30.      Sporulated  oocyst  of  Eimeria  lab- 
beana  of  the  pigeon.    X  1700. 
(From  Nieschulz,   1935) 

16  to  22  11  (usually  19  to  21  by  17.  5  to  20  fi ) 
with  a  mean  of  20  by  19  ji.    On  the  other 
hand,  Duncan  (1959),  in  a  study  of  infec- 
tions in  more  than  300  pigeons,   measured 
a  large  but  unspecified  number  of  oocysts 
at  various  times  during  the  patent  period 
and  found  that  the  overall  range  was  14.  5 
to  24  by  13  to  22.  5 (i  with  an  overall  mean 
of  19  by  11 IX  .     However,   smaller  oocysts 
appeared  early  in  the  infection  in  13  birds, 
and  in  10  of  them  they  increased  in  size  to 
approximately  the  overall  average  by  the 
end  of  the  patent  period.    These  small 
oocyst  strains  averaged  15  to  18  by  14  to 
17ji.     It  would  appear,  therefore,   that  £. 
columbarum  is  a  synonym  of  E.  labbeaiia. 

Life  Cycle:     Nieschulz  (1925a)  des- 
cribed the  endogenous  stages  and  also  gave 
one  of  the  few  descriptions  extant  of  early 
sporogony  in  the  coccidia.    Soon  after  the 
macrogametes  are  fertilized  and  the 
oocysts  are  formed,  the  zygote  contracts 
into  a  ball  within  the  oocyst  wall.    A  fer- 
tilization spindle  then  forms;  it  is  a  clear 
band  which  passes  thru  the  center  of  the 
sporont  and  forms  extensions  which  reach 
to  the  oocyst  wall.    This  band  then  dis- 
appears and  the  sporont  rounds  up  again, 
but  a  refractile  granule  is  left  in  the 
oocyst.    Altho  Nieschulz  did  not  recognize 
it  as  such,  this  was  undoubtedly  reduction 
division  with  the  throwing  off  of  a  polar 
granule.     Four  prominences  form  on  the 
sporont,  which  then  divides  to  form  4 
spherical  sporoblasts.     These  become 
rather  triangular  or  elongate  ovoid,  and 
a  clear  area  appears  at  the  pointed  end 
(pyramid  stage).     The  sporoblasts  round 
up  again,  and  finally  elongate  to  form 
elongate  ovoid,  pointed  sporocysts  in 


which  the  sporozoites  develop.     The  spor- 
ulation  time  is  4  days  or  less  (Duncan, 
1959a). 

After  the  sporulated  oocysts  are  in- 
gested, the  sporozoites  are  released  and 
invade  the  epithelial  cells  of  the  intestine. 
They  round  up  and  grow  into  mature  schi- 
zonts  in  3  days.     Each  schizont  produces 
about  15  to  20  merozoites,  often  leaving  a 
residual  body.    The  merozoites  are  some- 
what crescent-shaped,   pointed  at  the  ends, 
and  5.  5  to  9 /J.  long.     There  is  a  second 
generation  of  schizonts  which  Nieschulz 
thought  might  be  extracellular.     These  are 
elongate,  up  to  18  by  5  ^i,  and  form  up  to 
16  merozoites. 

The  microgametocytes  form  a  large 
number  of  biflagellate  microgametes  about 
2>\i  long  with  flagella  10/i  long.     The  ma- 
crogametes have  a  row  of  large  plastic 
granules  around  their  periphery.     Nieschulz 
figured  what  was  probably  a  fertilized  ma- 
crogamete  in  which  a  microgamete  nucleus 
was  approaching  the  macrogamete  nucleus 
in  a  clear  pathway  thru  the  cytoplasm. 
After  fertilization,  the  plastic  granules 
coalesce  to  form  the  oocyst  wall.    Oocysts 
first  appear  in  the  feces  6  days  after  in- 
fection. 

Pathogenesis:     E.   labbeatia  is 
slightly  to  markedly  pathogenic,  depending 
in  part  upon  the  age  of  the  birds  (Levi, 
1957).     Adults  are  fairly  resistant,  altho 
fatal  infections  have  been  seen.     The  birds 
become  weak  and  emaciated,  eat  little  but 
drink  a  great  deal,  and  have  a  greenish 
diarrhea.     The  heaviest  losses  occur 
among  squabs  in  the  nest.    A  high  percent- 
age of  the  squabs  may  die,  and  those  which 
recover  are  often  somewhat  stunted. 

The  principal  gross  lesion  is  inflam- 
mation thruout  the  intestinal  tract. 

Diagnosis:     Diagnosis  depends  on 
recognizing  the  oocysts  and  other  stages  in 
the  intestine  in  association  with  the  signs 
and  lesions  of  the  disease. 

Treatment:     According  to  Lindsay 
(cited  by  Levi,   1957),  sulfaquinoxaline  is 
effective  against  E.   labbeana. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


235 


Prevention  and  Control:     The  same 
measures  used  to  control  coccidiosis  in 
chickens  are  effective  against  the  disease 
in  pigeons.    General  sanitation  and  dry 
quarters  are  especially  important. 


EIMERIA   COLUMBAE 

MITRA  AND  DAS  GUPTA,   1937 

Host:     Indian  pigeon  {Columba  livia 
intermedia). 

Location:     Intestine. 

Geographic  Distribution:     India. 

Prevalence:     Unknown. 

Morphology:     The  oocysts  of  this 
species  have  not  been  completely  des- 
cribed.    They  are  subspherical,   have  a 
maximum  size  of  16  by  14 /j,  and  differ 
from  E.   labbeana  in  having  an  oocyst 
residuum,  according  to  Mitra  and  Das 
Gupta  (1937). 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


Genus  ISOSPORA  Schneider,   1881 

In  this  genus  the  oocyst  contains  2 
sporocysts,  each  of  which  contains  4 
sporozoites. 


ISOSPORA  AKSAICA 
BASANOV,   1952 

Host:     Ox. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     USSR 
(Kazakhstan). 

Prevalence:     Unknown.    This  species 
was  found  only  in  calves  12  to  30  days  old. 

Morphology:     The  oocysts  are  26  ii  in 
diameter,  spherical,  dark  silver  under 


low  magnification  and  light,   pinkish  grey 
under  high.     The  oocyst  wall  is  1.6^  thick, 
smooth  and  double -contoured,  with  a  light 
blue  outer  layer  and  a  greenish,  dingy 
rose  inner  layer.    The  sporocysts  are  el- 
lipsoidal or  spherical,   22  by  15 /i.     Micro- 
pyle,  oocyst  residuum  and  sporocyst  resi- 
duum are  presumably  absent.     Polar 
granules  are  possibly  present.    The  sporo- 
zoites are  spherical,  bean-shaped  or 
ellipsoidal,  1 5  by  1 1  jj, . 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     There  is  a  question 
whether  this  is  actually  a  valid  species  of 
bovine  coccidium  or  whether  it  is  a  pseudo- 
parasite,  i.e.,  an  avian  or  other  foreign 
coccidium  which  the  cattle  had  ingested 
along  with  its  host's  feces.     Further  work 
will  be  necessary  to  decide  this  point. 
The  subjacent  discussion  of  the  Isospora 
species  found  by  Levine  and  Mohan  (1960) 
in  cattle  has  a  bearing  on  /.  aksaica  also. 


ISOSPORA  sp. 

LEVINE  AND  MOHAN,   1960 

Hosts:     Ox  and  ox-zebu  hybrids. 

Location:     Unknown.     Oocysts  found 
in  feces. 


Geographic  Distribution: 
America  (Illinois). 


North 


Prevalence:     Levine  and  Mohan  (1960) 
found  this  form  in  6  out  of  54  beef  cattle 
on  3  farms  in  central  Illinois. 

Morphology:     The  oocysts  are  usually 
subspherical,  occasionally  spherical,  21 
to  33  by  20  to  32  ^  with  a  mean  of  27  by 
25  ji.     The  oocyst  wall  is  smooth,  color- 
less, pale  lavender  or  pale  yellowish, 
composed  of  a  single  layer  about  1  ji  thick. 
In  some  oocysts,  the  wall  appeared  to  be 
lined  by  a  thin  membrane.    A  micropyle 
and  oocyst  residuum  are  absent.    Several 
oocyst  polar  granules  are  present.    The 
sporocysts  are  lemon-shaped,  quite  thick- 
walled,  14  to  20  by  10  to  12  ^x  with  a  mean 


236 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


of  17  by  11  /i.     The  sporocyst  Stieda  body 
is  a  button-shaped  cap,  with  a  dependent, 
globular  hyaline  mass  protruding  into  the 
interior  of  the  sporocyst.     The  sporocyst 
residuum  is  finely  granular.    The  sporo- 
zoites  are  sausage-shaped,   not  arranged 
in  any  particular  order  in  the  sporocyst. 
The  sporocyst  residuum  and  sporozoites 
are  enclosed  in  a  membrane,  forming 
more  or  less  of  a  ball  within  the  sporo- 
cyst. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:      Levine  and  Mohan  (1960) 
compared  this  form  with  /.  lacazei  of  the 
English  sparrow,  which  they  redescribed. 
They  found  that  the  2  forms  were  practi- 
cally indistinguishable  and  concluded  that 
the  oocysts  found  in  bovine  feces  were 
most  likely  those  of  /.  lacazei  and  were 
pseudoparasites  of  cattle.     They  calculated 
that,   in  a  steer  which  produced  about  20 
pounds  of  feces  per  day,  the  presence  of 
1  oocyst  per  gram  of  feces  would  represent 
contamination  of  the  feed  with  about  9000 
oocysts,  assuming  that  the  oocysts  were 
mixed  uniformly  with  the  ingesta  and 
passed  thru  the  animal  unchanged.    Assum- 
ing again  that  a  flotation  was  carried  out 
with  about  2  g  of  feces  and  that  about  10% 
of  the  oocysts  present  were  recovered, 
they  calculated  that  every  oocyst  found 
might  represent  an  initial  contamination 
of  a  day's  feed  with  about  45,  000  oocysts. 
Since  Boughton  (1933)  quite  frequently  ob- 
tained counts  of  200,000  to  2  million 
oocysts  per  gram  of  dried  sparrow  feces, 
they  considered  it  quite  likely  that  spar- 
row coccidia  could  be  detected  in  a  calf's 
feces  if  it  ingested  only  a  single  fecal 
deposit  from  a  single  sparrow  in  the 
course  of  a  day. 


ISOSPORA  SUIS 
BIESTER,   1934 

Host:     Pig. 

Location:     Small  intestine,  from  the 
lower  third  of  duodenum  to  2  or  3  feet 
from  the  ileocecal  valve. 


Geographic  Distribution:     North 
America  (Iowa),   USSR  (Kazakhstan). 

Prevalence:     Unknown. 

Morphology:     This  species  has  been 
described  by  Biester  (1934)  and  Biester 
and  Murray  (1934).     The  oocysts  are  sub- 
spherical  to  ellipsoidal,  becoming  more 
ellipsoidal  on  sporulation.     The  oocyst 
wall  is  often  stretched  by  the  oocysts  and 
pinched  in  between  them.     It  is  smooth, 
composed  of  2  layers,  brownish  yellow, 
and  1.5(i  thick.    A  micropyle  is  absent. 
The  unsporulated  oocysts  measure  20  to 
24  by  18  to  21  fi  with  a  mean  of  22.  5  by 
19.4/1.    An  oocyst  polar  granule  is  pres- 
ent.   An  oocyst  residuum  is  absent.     The 
sporocysts  are  ellipsoidal,  16  to  18  by 
10  to  12 /i  with  a  mean  of  16.4  by  11.  2u. 
The  sporocyst  wall  is  double,  0.  7|i  thick. 
The  sporozoites  are  elongate.    A  sporo- 
cyst residuum  is  present.    A  Stieda  body 
is  absent.     The  sporulation  time  is  4  days. 

Life  Cycle:     According  to  Biester  and 
Murray  (1934),  /.   suis  invades  the  epithe- 
lial cells  of  the  intestine.     Many  of  these 
invaded  cells  migrate  to  a  subepithelial 
position,  but  often  both  the  host  cells  and 
the  parasite  appeared  to  undergo  retro- 
gressive changes  and  to  be  desquamated. 

The  prepatent  period  after  experi- 
mental infection  is  6  to  8  days,  and  oocysts 
continue  to  be  eliminated  for  about  8  days 
after  a  single  infective  feeding. 

Pathogenesis:     According  to  Biester 
and  Murray  (1934),   /.  sids  causes  a  catar- 
rhal enteritis.    The  epithelium  of  the 
crypts  is  destroyed  except  near  the  intes- 
tinal lumen.     The  substantia  propria  of 
the  tips  of  the  villi  is  destroyed,   leaving 
a  reticular  honeycomb  without  cells  or 
nuclei.    Interstitial  inflammation  with 
marked  eosinophilic  infiltration  is  present, 
but  there  is  no  gross  hemorrhage. 

Diarrhea  began  about  the  6th  day  af 
after  experimental  infection,   continued 
for  3  or  4  days,  and  was  followed  by  con- 
stipation.   /.   suis  infections  are  appar- 
ently not  fatal,  but  they  may  retard  growth 
and  produce  unthriftiness. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA    PROPER 


237 


Cross-Transmission  Studies:    Biester 
and  Murray  (1934)  and  Biester  (1934)  re- 
ported that  attempts  to  transmit  /.   sids 
to  guinea  pigs,   rats,  and  dogs  were  un- 
successful. 


ISOSPORA  ALMATAENSIS 
PAICHUK,   1953 

Host:      Pig. 

Location:     Unknown.    Oocysts  found 
in  feces. 

Geographic  Distribution:     USSR 
(Kazakhstan). 

Prevalence:     Unknown. 

Morphology:     This  species  was  des- 
cribed by  Paichuk  (1953).     The  oocysts 
are  short-oval,   subspherical  or  spherical, 
and  grey.     The  short-oval  forms  are  25 
to  32  by  23  to  29  jj,  with  a  mean  of  27.  9  by 
26.  0  \i ;  the  spherical  forms  are  26  to  32  [i 
in  diameter  with  a  mean  of  27.  7  /j. .     The 
oocyst  wall  is  smooth,  bright  yellow,   "i^i 
thick,  and  composed  of  3  layers.    A  mi- 
cropyle  is  apparently  absent.    The  oocysts 
sometimes  have  2  sporoblasts  when 
passed.    Oocyst  polar  granules  are  pres- 
ent.   An  oocyst  residuum  is  absent.     The 
sporocysts  are  oval  or  ovoid  with  a 
pointed  end,   12  to  19  by  9  to  12 /i  with  a 
mean  of  15.5  by  10.  8  /i .     A  sporocyst 
residuum  is  present.     The  sporozoites  are 
short-oval,   6  by  4jj..     The  sporulation 
time  is  5  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 


ISOSPORA  BIGEMINA 
(STILES,   1891) 
LUHE,   1906 

Synonyms:      Coccidium  bigeminum, 
Liicetina  bigemina. 

Hosts:     Dog,  cat,  fox,  polecat  (Pu- 
toriiis  foetidus),  mink  (Mustela  vison), 
man  (?). 


Location:     Thruout  small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  quite 
common  in  dogs  and  cats.    Gassner  (1940) 
found  it  in  74%  of  320  dogs  in  Colorado. 
Catcott  (1946)  found  it  in  3%  of  113  dogs 
in  Ohio.     Choquette  and  Gelinas  (1950) 
found  it  in  2%  of  155  dogs  in  Montreal. 
Ehrenford  (1953)  found  it  in  0.7%  of  377 
dogs  in  Indiana  and  other  midwestern 
states.     Hitchcock  (1953)  found  it  in  1%  of 
147  kittens  in  Michigan.     Levine  (1948) 
reviewed  reports  of  this  species  in  Mus- 
telidae. 


Morphology:     The  oocysts  are  very 
thin-walled,  spherical  to  ellipsoidal  when 
unsporulated,  but  with  the  wall  stretched 
around  the  sporocysts  and  usually  con- 
stricted somewhat  between  them  when 
sporulated.     The  oocyst  wall  is  smooth, 
colorless,  and  composed  of  a  single  layer. 
Two  sizes  of  oocyst  have  been  reported. 
The  larger  ones  measure  18  to  20  by  14 
to  16  |i,  and  the  smaller,   more  common 
ones  10  to  14  by  7  to  9  ^t.     Micropyle, 
oocyst  polar  granule  and  oocyst  residuum 
are  absent.    The  sporocysts  are  ellip- 
soidal,  7.  5  to  9  by  5  to  7  |:x,  without  a 
Stieda  body.    A  sporocyst  residuum  is 
present.    The  oocysts  are  sporulated 
when  passed.    The  oocyst  wall  is  often 
ruptured  so  that  the  sporocysts  are  found 
free  in  the  feces.    In  acute  infections,  the 
oocysts  may  be  unsporulated  when  passed; 
their  sporulation  time  is  about  4  days. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  by  Wenyon  (1926a) 
and  Wenyon  and  Sheather  (1925).     The 
endogenous  stages  occur  thruout  the  small 
intestine.    Altho  the  course  of  infection  has 
not  been  followed  consecutively  in  a  series 
of  experimentally  infected  animals,  it  ap- 
pears that  the  epithelial  cells  are  invaded 
first,  followed  later  on  by  the  subepithelial 
cells.    At  any  rate,  Wenyon  and  Sheather 
(1925)  found  coccidia  only  in  the  epithelial 
cells  of  a  dog  killed  during  the  acute  phase 
of  the  infection.     The  schizonts  of  this 
stage  contain  8  merozoites.     Later  on,  the 
coccidia  are  found  in  the  subepithelial 
cells  and  cores  of  the  villi.    The  schizonts 


238 


THE  TELOSPORASroA  AND  THE  COCCIDIA   PROPER 


here  contain  about  12  merozoites.    Sexual 
stages  appear  to  be  produced  in  both  loca- 
tions.    The  oocysts  produced  in  the  epithe- 
lial cells  during  the  acute  phase  are 
unsporulated  when  passed  in  the  feces. 
They  appear  6  to  7  days  after  infection. 
The  oocysts  produced  in  the  subepithelial 
cells  are  sporulated  when  passed.    A 
number  of  unanswered  questions  are  raised 
by  this  account,  and  the  whole  life  cycle 
deserves  re-investigation. 

Pathogenesis:     This  species  is  mark- 
edly pathogenic  for  both  cats  and  dogs. 
Its  effects  on  the  dog,  cat  and  fox  were 
studied  by  Lee  (1934).     Puppies  and  kittens 
are  most  seriously  affected,  while  adults 
are  usually  carriers,   having  developed  an 
immunity  following  earlier  infection. 

The  first  signs  usually  begin  4  to  6 
days  after  infection.     Their  severity  de- 
pends on  the  degree  of  infection.     In 
severe  cases,  catarrhal  or  bloody  diar- 
rhea, rapid  emaciation  and  anemia  occur. 
Affected  animals  are  weak,  depressed  and 
lose  their  appetite.    There  may  be  a  rise 
in  temperature  or  muscular  tremors  of 
the  hind  legs.    If  the  animal  survives  the 
acute  phase,  the  dysentery  is  replaced  by 
mucous  stools  for  2  to  4  days  and  the 
other  signs  subside,  disappearing  7  to  10 
days  after  their  onset.     Recovered  animals 
may  continue  to  shed  oocysts  for  a  time. 


from  those  of  /.  bigemina,  and  a  number 
of  investigators  believe  that  they  are  the 
same  species  (Elsdon-Dew  and  Freedman, 
1953;  Routh,  McCroan  and  Hames,  1955; 
Becker,  1956).  Cross-transmission  ex- 
periments are  needed  to  determine  whether 
they  are. 


ISOSPORA  FEUS 
WENYON,   1923 

Synonyms:     Isospora  call,   Coccidium 
bigeniinuni  var.  cati,  Lucetina  cati, 
Lucetina  fells. 

Hosts:     Dog,  cat,  lion  and  possibly 
other  carnivores. 

Location:     Small  intestine,  some- 
times cecum,  occasionally  colon. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  in  common 
in  dogs  and  cats.     Gassner  (1940)  found  it 
in  6%  of  320  dogs  in  Colorado.     Catcott 
(1946)  found  it  in  3.  5%  of  113  dogs  in  Ohio. 
Choquette  and  Gelinas  (1950)  found  it  in  9% 
of  155  dogs  in  Montreal.     Hitchcock  (1953) 
found  it  in  75%  of  147  kittens  in  Michigan. 
Alves  da  Cruz,  de  Sousa  and  Cabral  (1952) 
found  it  in  10%  of  40  stray  cats  in  Lisbon, 
Portugal. 


In  severe  cases,  hemorrhagic  enter- 
itis is  present  thruout  the  small  intestine; 
it  is  most  severe  in  the  lower  ileum  and 
becomes  progressively  less  so  anteriorly. 
Petechiae  are  present  in  light  infections, 
and  diffuse  hemorrhages  in  more  severe 
ones.    There  may  be  ulcers  in  addition. 
The  mucosa  is  thickened,  and  there  may 
be  extensive  desquamation.     A  circulating 
eosinophilia  may  be  present,  and  the  para- 
sitized region  is  infiltrated  with  eosino- 
philes. 

Cross-Transmission:      Lee  (1934) 
transmitted  /.  bigemina  from  the  dog  to 
the  cat  and  fox,  but  failed  to  infect  rabbits 
or  guinea  pigs  with  it. 

Remarks:     The  oocysts  of /.   honiinis 
of  man  are  apparently  indistinguishable 


Morphology:     The  oocysts  are  ovoid, 
32  to  53  by  26  to  43  ji  with  a  mean  of  43 
by  33  jj. .     The  oocyst  wall  is  smooth  and 
colorless,  without  a  micropyle.    An  oocyst 
polar  granule  and  residuum  are  absent. 
The  sporocysts  are  ellipsoidal,  20  to  27 
by  18  to  21  /i.    A  sporocyst  residuum  is 
present.     The  sporozoites  are  10  to  15;^ 
long.     The  sporulation  time  is  3  days  or 
less. 

Life  Cycle:     The  life  cycle  of  /.  fells 
in  experimentally  infected  kittens  was  des- 
cribed in  detail  by  Hitchcock  (1955)  and 
Lickfeld  (1959).    It  is  similar  in  dogs. 
The  parasites  are  found  above  or  beside 
the  host  cell  nuclei  of  the  epithelial  cells 
of  the  villi  and  sometimes  in  the  subepi- 
thelial tissues.    There  are  2  asexual  gen- 
erations.    The  first  generation  schizonts 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


239 


are  found  in  the  small  intestine  and  cecum 
from  the  second  to  fourth  day  after  experi- 
mental infection.     They  are  ellipsoidal 
and  about  20  j^  long.     They  produce  40  to 
60  merozoites  according  to  Hitchcock,  or 
12  or  less  according  to  Lickfeld.    These 
merozoites  are  relatively  large,  measur- 
ing 16  to  18.5  by  5  to  8  ju. 

The  second  generation  schizonts  are 
found  on  the  5th  and  6th  days  after  infec- 
tion in  the  small  intestine  and  less  com- 
monly in  the  large  intestine.     According 
to  Hitchcock,  they  produce  up  to  24  mero- 
zoites, but  most  contain  12  to  16;  accord- 
ing to  Lickfeld  there  are  30  to  more  than 
100  of  these  merozoites,  and  they  measure 
7.  5  by  2.  5jLt. 

The  sexual  stages  are  found  on  the 
7th  and  8th  days  after  infection.     They 
occur  in  the  small  intestine  and  less  com- 
monly in  the  cecum.    According  to  Hitch- 
cock (1955),  the  macrogametes  average 
25  to  22 /J,,  but  other  workers  have  re- 
corded dimensions  up  to  56  by  48/j, .     The 
microgametocytes  average  28  by  19jll 
according  to  Hitchcock,  but  other  workers 
have  recorded  dimensions  up  to  50  by  30  ji , 
and  Lickfeld  said  that  they  are  73  jj,  in 
diameter  in  life.    Well  over  2000  spindle- 
shaped,   curved,  biflagellate  microgametes 
are  formed  in  each  microgametocyte.    The 
oocyst  wall  is  laid  down  following  fertiliza- 
tion while  the  zygotes  are  still  within  the 
host  cells.    The  young  oocysts  then  break 
out  and  are  passed  in  the  feces.     The  pre- 
patent  period  was  found  by  Hitchcock 
(1955)  to  be  7  to  8  days. 

According  to  Walton  (1959),  the  hap- 
loid  number  of  chromosomes  in  /.  felis 
is  2.     Lickfeld  (1959)  described  a  cryp- 
tomitotic  type  of  schizogony,  but  saw  no 
chromosomes. 

Pathogenesis:     This  species  is 
slightly  to  moderately  pathogenic,  depend- 
ing on  the  host  species,  age,  degree  of 
infection,  etc.    It  is  less  serious  in  cats 
than  in  dogs.     None  of  18  four-  to  nine- 
week-old  kittens  infected  by  Hitchcock 
(1955)  with  100,000  sporulated  oocysts 
showed  signs  of  disease.    Andrews  (1926), 


however,  observed  enteritis,  emaciation, 
weakness,  depression,  dysentery  and  even 
death  in  kittens  and  dogs  experimentally 
infected  with  I.  felis.     Hitchcock  thought 
that  these  signs  and  deaths  in  the  kittens 
might  well  have  been  due  to  feline  dis- 
temper. 

The  gross  pathologic  lesions  are 
similar  to  those  caused  by  /.   bigemina. 
There  is  hemorrhagic  enteritis,  frequently 
with  ulceration,  thickened  mucosa  and 
epithelial  desquamation. 

Immunity:     Animals  which  have  re- 
covered from  I.  felis  infections  are  re- 
sistant to  reinfection. 

Cross  Transmission:  Lee  (1934)  in- 
fected dogs  with  /.  felis  from  the  cat,  and 
a  fox  with  /.  felis  from  the  dog. 


ISOSPORA  RIVOLTA 

(GRASSl,   1879) 

Synonyms:      Coccidiuni  rivolta, 
Lucetina  rivoltai. 

Hosts:     Dog,  cat,  dingo,  and  prob- 
ably other  wild  carjiivores. 

Location:     Small  intestine. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  common 
in  dogs  and  cats.    Gassner  (1940)  found  it 
in  20%  of  320  dogs  in  Colorado.     Catcott 
(1946)  found  it  in  4%  of  113  dogs  in  Ohio. 
Ehrenford  (1953)  found  it  in  72%  of  377 
dogs  from  Indiana  and  nearby  states. 
Choquette  and  Gelinas  (1950)  found  it  in 
13.  5%  of  155  dogs  in  Montreal.     Hitchcock 
(1953)  found  it  in  13%  of  147  kittens  in 
Michigan. 

Morphology:     The  oocysts  are  ovoid, 
20  to  25  by  15  to  20  fi.     The  oocyst  wall  is 
smooth,  with  a  micropyle  at  the  small 
end.    An  oocyst  polar  granule  and  residuum 
are  absent.    The  sporocysts  are  16  by  10  \i. 
A  sporocyst  residuum  is  present.     The 
sporulation  time  is  4  days. 


240 


THE  TELOSPORASIDA  AND  THE  CCXTCmiA   PROPER 


Life  Cycle:     The  endogenous  stages 
of  /.  rivolla  are  poorly  known.    They  are 
said  to  resemble  those  of  /.  Jelis  but  to 
be  smaller.    They  are  found  in  the  epithe- 
lial cells  and  sometimes  in  the  subepithe- 
lial tissues  of  the  small  intestine.    Oocyst 
development  ordinarily  takes  place  out- 
side the  body,  but  occasionally  occurs  in 
the  subepithelial  tissues. 

Pathogenesis:     Altho  experimental 
studied  on  /.  rivolla  alone  have  apparently 
not  been  carried  out,   it  is  presumably  as 
pathogenic  as  /.   bigeiniiia  and  /.  Jelis. 

Cross  Transmission:     Lee  (1934)  in- 
fected a  fox  with  /.  rivolla  from  the  dog. 


Fig.  31. 


B 


Sporulated  oocysts  of  coccidia  of 

dog  and  cat.     A.    Isospora  blgem- 

iiia.     B.    Isospura  rivulla. 

C.    Isospoya  felis.     X  850.     (From 

Becker,   1934,  after  Wenyoii,   1926, 

Protozoology) 


COCCIDIOSIS   IN    DOGS   AND   CATS 

Epidemiology:     Coccidiosis  is  com- 
mon in  dogs  and  cats,  and  is  a  not  infre- 
quent cause  of  diarrhea  and  even  death 
in  puppies  and  kittens.     Crowding  and 
lack  of  sanitation  promote  its  spread. 
Coccidia  sometimes  seed  a  breeding  ken- 
nel, boarding  kennel  or  veterinarian's 
wards  so  heavily  that  most  of  the  puppies 
born  or  brought  there  become  infected. 

Diagnosis:     Coccidiosis  can  be  diag- 
nosed at  necropsy  by  finding  coccidia  in 
the  intestinal  lesions.    It  can  be  diagnosed 
in  affected  animals  by  finding  oocysts  in 


association  with  diarrhea  or  dysentery. 
However,  care  must  be  taken  to  differen- 
tiate coccidiosis  from  coccidiasis,   since 
many  animals  may  be  shedding  oocysts 
without  suffering  from  disease.     Other 
disease  agents  should  be  searched  for  and 
found  absent.     The  presence  of  a  wave  of 
oocysts  during  and  shortly  after  an  attack 
of  enteritis  and  their  marked  diminution  or 
disappearance  soon  thereafter  would  sug- 
gest that  coccidia  caused  the  attack. 

The  oocysts  of  Isospora  bigemina  are 
usually  sporulated  when  they  are  passed 
in  the  feces.     They  are  often  ruptured, 
releasing  the  sporocysts.     These  are  very 
small,   and  will  often  be  overlooked  unless 
the  high  dry  power  of  the  microscope  is 
used  in  making  a  fecal  examination.     In 
addition,  they  resemble  Cryptospuridium 
oocysts  and  might  be  mistaken  for  them. 

Treatment:     There  is  no  good  treat- 
ment for  coccidiosis  in  dogs  and  cats  once 
the  signs  of  disease  have  appeared.    All 
the  coccidiostatic  agents  on  the  market 
are  preventive  rather  than  curative  in 
action.     The  fact  that  coccidiosis  is  a 
self-limiting  disease  has  often  led  to  the 
belief  that  some  ineffective  drug,  admin- 
istered at  the  time  natural  recovery  was 
due  to  begin,  was  responsible  for  the 
cure.    Uncontrolled  studies  on  coccidiosis 
therapy,   such  as  that  of  Duberman  (1960) 
with  nitrofurazone,  are  worse  than  use- 
less, since  they  may  lead  to  false  con- 
clusions regarding  a  drug's  value. 

Craige  (1949),  a  clinician  with  con- 
siderable experience  in  handling  canine 
coccidiosis,  considered  treatment  in  an 
unsatisfactory  state.    Sometimes  the 
animals  would  respond  to  sulfonamides, 
but  he  had  better  success  by  combining  a 
sulfonamide  with  quinacrine,   sulfocar- 
bolates,  tannin-yeast,   iodine  preparations, 
etc.     McGee  (1950)  used  sulfamethazine. 
Altman  (1951)  used  chlortetracycline. 
Supportive  treatments  such  as  these,  and 
particularly  the  use  of  antibiotics  such  as 
chlortetracycline  and  oxytetracycline  to 
control  secondary  infections,  may  be 
helpful  even  tho  they  do  not  act  on  the 
coccidia  themselves. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


241 


Prevention:     Sanitation  and  isolation 
are  effective  in  preventing  coccidiosis. 
Animal  quarters  should  be  cleaned  daily. 
Runways  should  be  concrete.     Ordinary 
disinfectants  are  ineffective  against  coc- 
cidian  oocysts,  but  boiling  water,  if  it  is 
still  boiling  when  it  reaches  the  oocysts, 
will  kill  them. 


ISOSPORA  BELLI 
WENYON,    1923 

Host:     Man. 

Location:      Presumably  small  intes- 
tine.    Elsdon-Dew,  Roach  and  Freedman 
(1953)  found  oocysts  in  material  from  a 
duodenal  intubation. 

Geographic  Distribution:     Presumably 
worldwide,  but  more  common  in  the  trop- 
ics than  in  the  temperate  zone. 

Prevalence:     This  species  is  quite 
rare  in  man.     However,   Elsdon-Dew  and 
Freedman  (1953)  found  it  in  32  persons  in 
Natal,  and  considered  that  it  was  often 
missed  because  it  was  not  looked  for. 


Pathogenesis:     Most  infections  with 
/.   belli  appear  to  be  subclinical  and  self- 
limiting.     However,   it  may  cause  a  mu- 
cous diarrhea.    In  31  of  the  33  cases  of 
Isospora  infection  studied  by  Barksdale 
and  Routh  (1948),  anorexia,  nausea,  ab- 
dominal pain  and  diarrhea  were  present. 
Matsubayashi  and  Nozawa  (1948)  reported 
that  symptoms  appeared  1  week  after  ex- 
perimental infection  of  2  human  volunteers, 
presumably  with  /.  belli,    and  that  oocysts 
appeared  in  the  feces  10  days  after  infec- 
tion and  persisted  for  a  month. 

Cross-Transmission  Studies:     Jeffery 
(1956)  failed  to  transmit  /.  belli  from  man 
to  2  monkeys,   2  dogs,   2  pigs,   12  mice,  4 
rats,  a  guinea  pig  and  a  rabbit.     Robin  and 
Fondimare  (1960)  were  unable  to  transmit 
it  from  man  to  the  guinea  pig,   rabbit, 
mouse  or  rat. 


ISOSPORA  HOMINIS 
(RAILLIET  AND   LUCET,   1891) 
WENYON,    1923 

Synonyms:      Coccidiiun  bigeminum 
var.  hominis,   Lucetina  hominis. 


Morphology:     This  species  has  often 
been  confused  with  /.  hominis   (see  Elsdon- 
Dew  and  Freedman,   1953),  but  is  clearly 
different.     The  oocysts  are  elongate  el- 
lipsoidal,  20  to  33  by  10  to  19  fi  (mean, 
30  by  12  fi  according  to  Elsdon-Dew  and 
Freedman,   1953).    One  or  both  ends  of 
the  oocyst  may  be  somewhat  narrow.    The 
oocyst  wall  is  smooth,  thin,  and  colorless. 
A  very  small  micropyle  is  sometimes 
visible.    An  oocyst  polar  granule  may  be 
present  in  young,  incompletely  sporulated 
oocysts,  but  quickly  disappears.     An 
oocyst  residuum  is  absent.     The  sporo- 
cysts  are  subspherical  to  ellipsoidal,  with- 
out a  Stieda  body,  12  to  14  by  7  to  9  fi 
(mean  11  by  9fi  according  to  Elsdon-Dew 
and  Freedman,   1953).    A  sporocyst  resi- 
duum is  present.     The  sporozoites  are 
slender,  somewhat  crescent-shaped,  with 
the  nucleus  at  one  end.     Both  immature 
and  mature  oocysts  may  be  passed  in  the 
feces.     The  sporulation  time  is  up  to  5 
days. 

Life  Cycle:     Unknown. 


Host:     Man. 


Location:     Small  intestine. 


Geographic  Distribution:     Worldwide, 
but  more  common  in  the  tropics  than  in 
the  temperate  zone. 


Prevalence: 
rare  in  man. 
Freedman 

Natal,  and  thought  that  it  was  often  missed 
because  people  did  not  look  for  it. 


This  species  is  quite 
However,  Elsdon-Dew  and 
(1953)  found  it  in  23  persons  in 


Morphology:     The  oocysts  are  spor- 
ulated when  passed.     The  oocyst  wall  is 
very  thin,   stretched  around  the  sporocysts 
and  usually  constricted  between  them,  and 
sometimes  not  visible.    It  is  often  rup- 
tured,  releasing  the  sporocysts.     The 
oocysts  are  about  20  by  15|j..    Micropyle, 
oocyst  polar  granule  and  residuum  are 
absent.    The  sporocysts  are  ellipsoidal  or 
with  one  side  flattened,  about  15  by  10 /i, 
without  a  Stieda  body.    A  sporocyst  resi- 
duum is  present. 


242 


THi;  TELOSPORASIDA   AND  THE  COCCIDLA    PROPER 


Life  Cycle:     Unknown. 

Pathogenesis:     Most  infections  ap- 
pear to  be  subclinical  and  self-limiting. 
However,  /.  Iiominis  may  cause  a  mucous 
diarrhea.     In  31  of  33  cases  of  Isuspora 
infection  studied  by  Barksdale  and  Routh 
(1948),  anorexia,  nausea,  abdominal  pain 
and  diarrhea  were  present. 

Remarks:     This  species  resembles 
/.   bigetiiina  very  closely,  and  it  may  well 
be  the  same  species  (see  Becker,   1956, 
Elsdon-Dew  and  Freedman,   1953;  Routh, 
McCroan  and  Hames,   1955).     Elsdon-Dew 
(1954)  failed  to  infect  a  dog  with  /.  hominis 
from  man,  but  the  animal  was  an  adult  and 
could  have  been  immune. 


ISOSPORA  NATALENSIS 
ELSDON-DEW,   1953 

Host:     Man. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     Africa 
(Natal). 

Prevalence:     Elsdon-Dew  (1953) 
found  this  species  in  2  persons  in  Natal. 

Morphology:     The  oocysts  are  sub- 
spherical,   25  to  30  by  21  to  24^..    The 
oocyst  wall  is  smooth  and  thin,  without  a 
micropyle.     An  oocyst  polar  granule  and 
oocyst  residuum  are  absent.     The  sporo- 
cysts  are  ellipsoidal,   17  by  12 /i,  without 
a  Stieda  body.    A  sporocyst  residuum  is 
present.     The  sporulation  time  is  1  day. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     When  Elsdon-Dew  and 
Freedman  (1953)  first  saw  this  form, 
they  thought  that  it  was  /.  rivolla.     How- 
ever, it  differs  morphologically  from  that 
species. 


COCCIDIOSIS    IN    MAN 

Coccidiosis  is  quite  rare  in  man,  and 
the  relation  of  the  species  described  from 
man  to  those  in  lower  animals  is  still  not 
clear.     Isospora  belli  appears  to  be  con- 
fined to  man,  and  /.  nataletisis  may  be 
also.     However,  further  research  may 
show  that  /.  lioniinis  is  a  synonym  of  /. 
bige))iina  and  that  man  acquires  his  infec- 
tions with  this  parasite  from  dogs  and 
cats. 

In  addition  to  the  above  species  which 
produce  infections  in  man,  a  number  of 
other  coccidia  have  been  found  in  human 
feces  and  mistaken  for  parasites  of  man. 
Perhaps  the  most  famous  of  these  were 
Eimeria  wenyoni,  E.  oxyspora  and  E. 
snijdersi.  which  Dobell  (1919)  described 
as  human  parasites.     The  first  turned  out 
to  be  E.  clupearum,    a  coccidium  of  her- 
ring,  sprats  and  mackerel,  and  the  second 
two  were  both  E.  sardinae,  a  parasite  of 
sardines,   herring  and  sprats.     In  addition, 
oocysts  of  E.  stiedae  of  the  rabbit  have 
been  found  in  a  mental  hospital  patient  who 
liked  to  eat  raw  rabbit  livers,  and  oocysts 
of  E.  debliecki  of  the  pig  were  found  by 
Drug  (1946)  in  several  others  who  probably 
acquired  them  in  sausage  casings. 


ISOSPORA  GALLINAE 
SCHOLTYSECK,   1954 

Host:     Chicken. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     Europe. 

Prevalence:     Unknown,   presumably 
rare. 

Morphology:     The  oocysts  are  ellip- 
soidal,  19  to  27  by  15  to  23)ll  with  a  mode 
of  24  by  19  fi.    A  micropyle  is  absent. 
Oocyst  polar  granules  are  present.    An 
oocyst  residuum  is  absent.     The  sporo- 
cysts  are  piriform. 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


243 


Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     The  validity  of  this  spe- 
cies is  dubious.    It  is  more  likely  a  para- 
site of  some  wild  bird,   such  as  /.  lacazei 
of  the  English  sparrow. 


ISOSPORA  HEISSINI 
SVANBAEV,   1955 

Host:     Domestic  turkey. 

Location:     Unknown.     Oocysts  found 
in  feces. 

Geographic  Distribution:     USSR  (Ka- 
zakhstan). 

Morphology:     The  oocysts  are  spher- 
ical or  rarely  broadly  ovoid,   25  to  33/1  in 
diameter,  with  a  mean  of  31  by  30  fx.     The 
oocyst  wall  is  greenish,  smooth,  double 
contoured  (illustrated  with  a  single  layer), 
and  1.5  to  1.7|i  thick.    A  micropyle  is 
apparently  absent.    An  oocyst  polar  gran- 
ule is  present.    An  oocyst  residuum  is 
absent.     The  sporocysts  are  spherical  or 
ovoid  and  pointed  at  one  end,   15  by  10  jn. 
A  sporocyst  residuum  is  absent.     The 
sporozoites  are  oval,   7  to  9  by  4  to  5 /i . 
The  sporulation  time  is  16  to  20  hours  at 
20  to  25°  C. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:     Svanbaev  (1955)  found  this 
species  only  in  turkeys  up  to  4  months  of 
age. 


Genus  WENYONELLA  Hoare,  1933 

In  this  genus  the  oocyst  contains  4 
sporocysts,  each  of  which  contains  4 
sporozoites. 


WENYONELLA  GALLINAE 
RAY,   1945 

Host:     Chicken. 


Location:     Terminal  part  of  intestine. 

Geographic  Distribution:     India. 

Prevalence:  Uncommon.  Gill  (1954) 
found  this  species  in  1.7%  of  120  chickens 
near  Mukteswar. 

Morphology:     The  oocysts  are  ovoid, 
rough,   punctate,   29  to  34  by  20  to  23  ^i. 
The  sporocysts  are  flask-shaped,   19  by 
8jj,.     No  other  morphological  information 
was  given.     The  sporulation  time  is  28°  C 
is  4  to  6  days. 

Life  Cycle:     Unknown. 

Pathogenesis:     According  to  Ray 
(1945),  this  species  causes  a  diarrhea 
with  blackish-green,   semisolid  excreta. 
The  terminal  part  of  the  intestine  is  thick- 
ened and  congested,  and  there  are  pinpoint 
hemorrhages  in  the  mucosa. 


Genus  TYZZERIA  Allen,  1936 

In  this  genus  the  oocyst  contains  8 
naked  sporozoites  and  no  sporocysts. 

TYZZERIA   PERNICIOSA 
ALLEN,   1936 

Host:     Domestic  Pekin  duck. 

Location:     Thruout  the  small  intes- 
tine, but  especially  in  the  upper  half. 

Geographic  Distribution:     North 
America. 

Prevalence:     Uncommon.    This  spe- 
cies has  been  reported  from  domestic 
ducks  only  by  Allen  (1936)  on  Long  Island. 
However,   its  relationship  to  T.  alleni, 
which  Chakravarty  and  Basu  (1946)    des- 
cribed from  the  cotton  teal  {Cheniscus 
coromandelianus)  in  India,  to  Tyzzeria  sp. 
which  Farr  (1952)  reported  from  the  black 
duck  {Anas  rubripes),  to  T.  anseris  re- 
ported by  Farr  (1959)  from  the  lesser 
scaup  duck  {Nyroca  affinis)  in  Michigan, 
and  to  T.  anseris  from  domestic  and  wild 
geese  and  the  whistling  swan  (see  Hanson, 
Levine  and  Ivens,  1957)  remains  to  be  de- 
termined. 


244 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


Morphology:     The  oocysts  are  ellip- 
soidal,  10  to  13  by  9  to  11  (i.     The  oocyst 
wall  is  thick,   colorless,  composed  of  an 
outer  thin,  transparent  layer  and  an  inner 
thicker  layer.    A  micropyle  is  absent. 
The  sporozoites  are  curved,  with  one  end 
rounder  and  broader  than  the  other,  about 
10  fi  long  and  3.  5fx  wide  at  the  larger 
end.     The  oocyst  residuum  is  large, 
usually  spherical.    The  sporulation  time 
is  1  day. 

Life  Cycle:     According  to  Allen 
(1936),  the  endogenous  stages  are  found 
in  the  mucosal  and  submucosal  cells. 
There  are  at  least  3  asexual  generations. 
The  first  generation  schizonts  are  rela- 
tively small,  about  12  by  Sfi,  and  contain 
relatively  few,   small  merozoites.    The 
later  schizonts  measure  about  15  to  16  by 
14  to  15ji  and  contain  more  and  larger 
merozoites  than  the  first  generation  ones. 
Schizogony  continues  long  after  the  forma- 
tion of  gametes. 

The  first  microgametocytes  appear 
2  days  after  infection.    They  measure 
about  7.  5  by  6jn  and  produce  a  large  num- 
ber of  tiny  microgametes.     The  macro- 
gametes  are  somewhat  irregular  in  shape. 
Oocysts  first  appear  in  the  feces  6  days 
after  infection. 

Pathogenesis:     According  to  Allen 
(1936),   T.  peniiciosa  is  highly  pathogenic 
for  ducklings.    All  of  7  experimentally 
infected,  week-old  ducklings  died. 

Affected  birds  stop  eating,   lose 
weight,  become  weak  and  cry  continuously 
as  if  in  distress.    At  necropsy,  inflamma- 
tion and  hemorrhagic  areas  were  found 
thruout  the  small  intestine  and  especially 
in  its  upper  half.     The  intestinal  wall  was 
thickened,  and  round,  white  spots  were 
visible  thru  its  serosal  surface.    In  se- 
vere cases  the  lumen  was  filled  with  blood 
and  often  contained  a  cheesy  exudate.    The 
intestinal  epithelium  sloughed  off  in  long 
pieces,   sometimes  forming  a  tube  which 
could  easily  be  lifted  out. 

TYZZERIA  ANSERIS 
NIESCHULZ,   1947 

Hosts:     Domestic  goose,  white- 
fronted  goose  {Anser  albifrons),  blue  or 


snow  goose  (A.  caerulescens),  Ross's 
goose  (A.  rossi),  Canada  goose  {Bfanla 
ca)iadensis),  Atlantic  brant  (B.  bernicla 
hrola),  whistling  swan  (Olor  colunibianus), 
lesser  scaup  duck  {Nyroca  affinis). 

Location:     Small  intestine. 

Geographic  Distribution:     North 
America,   Europe. 

Prevalence:     This  species  is  appar- 
ently rare  in  domestic  geese,  having  been 
reported  in  them  only  by  Nieschulz  (1947) 
in  Holland  and  by  Farr  and  Wehr  (1952)  in 
Maryland.     It  is  common,   however,   in 
wild  geese,  and  has  been  found  in  all  the 
species  from  which  coccidia  have  been  re- 
ported and  from  all  6  North  American  fly- 
ways  (Hanson,   Levine  and  Ivens,   1957). 
It  is  most  likely  a  parasite  of  wild  geese 
which  occasionally  occurs  in  domestic 
ones  as  the  result  of  accidental  contam- 
ination. 

Morphology:     The  oocysts  were  des- 
cribed by  Levine  (1952).     They  are  ellip- 
soidal,  10  to  16  by  9  to  12jLL  with  a  mean 
of  about  13  by  l\  [i .     The  oocyst  wall  is 
smooth,   colorless,  about  0.6(i  thick,  and 
usually  appears  to  be  composed  of  a  sin- 
gle layer  altho  in  some  oocysts  a  second 
inner  line  is  visible;    this  may  perhaps  be 
a  membrane  which  has  pulled  away  from 
the  wall.    A  micropyle  is  absent.     The 
sporozoites  are  banana-shaped.     The 
oocyst  residuum  is  large,   irregular,  gran- 
ular, and  often  surrounded  by  the  sporo- 
zoites. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown  in  very 
young  birds;  negligible  in  adults. 


COCCIDiOSIS   IN    DUCKS   AND   GEESE 

Our  knowledge  of  the  coccidia  of 
ducks  and  geese  is  extremely  deficient. 
Except  for  renal  coccidiosis  of  the  goose 
caused  by  E.  Irmicata,    coccidiosis  ap- 
pears to  be  of  little  importance  in  these 
birds,  and  coccidia  have  seldom  been  re- 
ported from  them.    A  few  outbreaks  of 
intestinal  coccidiosis  have  been  reported, 


THE  TELOSPORASIDA   AND  THE  COCCIDIA   PROPER 


245 


however,    Jansen  (1931),  for  example-, 
described  one  in  Holland  in  which  more 
than  10%  of  a  flock  of  700  ducks  died  in  2 
days. 

Treatment:     Little  is  known  of  the 
treatment  of  coccidiosis  of  ducks  and 
geese.     McGregor  (1952)  reported  that  E. 
truiicata  infections  of  geese  seemed  to 
respond  to  sodium  sulfamethazine,  and 
the  urinary  excretion  of  sulfonamides  in 
general  would  suggest  that  they  should  be 
particularly  effective  against  this  species. 

Prevention  and  Control:    The  same 
measures  should  be  used  for  the  preven- 
tion and  control  of  coccidiosis  in  ducks 
and  geese  as  in  chickens. 


FAMILY   CRYPTOSPORIDIIDAE 

Members  of  this  family  are  mono- 
xenous.    Development  takes  place  on  the 
surface  of  the  host  cells  or  within  their 
striated  border,   and  not  in  the  cells 
proper.     The  oocysts  and  schizonts  have 
a  knob-like  attachment  organ  at  some 
point  on  their  surface.     The  oocysts  con- 
tain no  sporocysts.     The  microgametes 
have  no  flagella.    There  is  a  single  genus, 
Cryptosporidium . 

Genus  CRYPTOSPOMDIUM 
Tyzzer,  1907 

In  this  genus  the  oocyst  contains  4 
naked  sporozoites. 


CRYPTOSPORIDIUM  TYZZERI 
NOM.  NOV. 

Synonyms:      Cryptosporidium  parvum 
Tyzzer,   1912  pro  parte. 

Host:     Chicken. 

Location:     All  stages  occur  in  the 
striated  border  (cuticular  layer)  of  the 
surface  epithelial  cells  of  the  tubular 
part  of  the  ceca. 


Geographic  Distribution: 
America  (Massachusetts). 


North 


Prevalence:     Rare. 

Morphology:     Tyzzer  (1929)  did  not 
describe  this  form  in  detail,  but  illustrated 
it  and  said  that  it  appeared  morphologically 
identical  with  C.  parriim  of  the  mouse. 
The  following  description  is  based  primar- 
ily on  that  given  by  Tyzzer  (1912)  for    C. 
parviim.    The  oocyst  is  ovoid  or  spherical, 
4  to  5  by  3|i .     The  oocyst  wall  is  smooth, 
composed  of  a  single  layer,  with  a  small, 
knob-like  attachment  organ.    A  micropyle 
is  absent.     An  oocyst  residuum  is  present. 
The  sporozoites  are  slender,  bow-  or 
boomerang-shaped,   5.  5  to  6/1  long,  with 
a  rod-shaped,   slender  nucleus  near  the 
anterior  end. 

Life  Cycle:     The  following  description 
is  based  primarily  on  that  given  by  Tyzzer 
(1912)  for  C.  parvum,  which  is  morpho- 
logically identical  with  C.   tyzzeri.    The 
schizonts  are  3  to  5|i  in  diameter  when 
mature  and  have  an  attachment  organ. 
They  are  attached  to  the  cell  surface  or 
embedded  in  its  striated  border.     They 
form  8  falciform  merozoites  2.  5  to  5  by 
0.  5  to  0.  7  /i  ,  with  a  nucleus  near  the 
thicker  end,  and  a  small  residual  mass. 
The  microgametocytes  are  smaller  than 
the  schizonts  and  also  have  an  attachment 
organ.     They  give  rise  to  16  tiny  micro- 
gametes  and  a  spherical  mass  of  residual 
material.     The  microgametes  are  chroma- 
tin rods  about  1  ii  long  and  not  more  than 
0.4jj,  wide,  without  visible  flagella.     The 
macrogametes  are  larger  than  the  schi- 
zonts and  microgametocytes,  and  contain 
tiny,   retractile  granules.     They  have  a 
thin,  dense  limiting  membrane  and  an 
attachment  organ. 

Pathogenesis:     Apparently  non-path- 
ogenic. 

Remarks:     Tyzzer  (1929)  thought  that 
this  was  the  same  species  he  had  pre- 
viously found  in  mice,  but  he  attempted 
no  cross-infection  experiments.     He  said 
that  even  if  such  experiments  failed,  the 
morphological  agreement  was  such  that  the 
chicken  and  mouse  forms  could  only  be  re- 
garded as  biological  varieties  of  the  same 
species.    However,  such  a  narrow  species 
concept  is  no  longer  held,  and  it  seems 


246 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


best  to  draw  attention  to  the  chicken  form 
by  giving  it  a  name  of  its  own.     Conse- 
quently it  is  named  Cryptosporidium 
tyzzeri. 

In  this  connection,  too,  it  might  be 
mentioned  that  Tyzzer  (1910)  was  unable 
to  infect  the  laboratory  rat  with  the 
closely  related  C.  niuris  from  the  labor- 
atory mouse. 


CRYPTOSPORIDIUM  MELEAGRIDIS 
SLAVIN,   1955 


Pathogenesis:     According  to  Slavin 
(1955),   C.  »ieleagridis  may  cause  illness 
with  diarrhea  and  a  low  death  rate  in  10- 
to  14 -day-old  turkey  poults. 


CRYPTOSPORIDIUM  SP. 

Tyzzer  (1929)  remarked  in  passing 
that  he  had  found  a  Cryptosporidium 
morphologically  similar  to  C.  parviim  in 
the  rabbit's  intestine,  but  did  not  discuss 
it  further.     No  one  else  appears  to  have 
recognized  this  form. 


Host:     Domestic  turkey. 

Location:     All  stages  occur  on  the 
villus  epithelium  of  the  terminal  third  of 
the  small  intestine. 

Geographic  Distribution:     Scotland. 

Prevalence:     Unknown;  found  in  1 
flock. 

Morphology:     This  species  was  des- 
cribed by  Slavin  (1955).     The  oocysts  are 
oval,   4.  5  by  4.  0  |i  ,  with  very  foamy  cyto- 
plasm and  an  eccentric,  faint,   poorly  de- 
fined wisp  of  nucleus.     No  sporulated 
oocysts  were  seen. 

Life  Cycle:     The  young  schizonts 
(trophozoites)  are  attached  to  the  epithe- 
lium of  the  villi,  often  in  enormous  num- 
bers.   They  have  an  attachment  organ 
which  penetrates  the  striated  border  of 
the  epithelial  cells.    Slavin  also  saw 
these  forms  in  the  goblet  cells,  between 
cells  as  far  down  as  the  basement  mem- 
brane, and  in  surface  depressions  between 
the  epithelial  cells.    The  mature  schizonts 
measure  5  by  4^  and  contain  8  merozoites. 
These  are  falciform,   5  by  1  ^i. ,  and  taper 
toward  the  ends,  with  one  end  blunter  than 
the  other.    The  nucleus  is  subterminal. 

The  microgametocytes  are  rounded 
or  oval,  4  fi  in  their  greatest  diameter, 
and  contain  16  intensely  staining  rod-like 
microgametes.    These  measure  1  by  0.3 n 
and  have  no  flagella.    The  macrogametes 
are  roughly  oval,  4.  5  to  5.  0  by  3.  5  to 
4.0ji. 


FAMILY   AGGREGATIDAE 

Members  of  this  family  are  hetero- 
xenous,  with  two  hosts.    Schizogony  takes 
place  in  one  and  sporogony  in  the  other. 
Development  takes  olace  in  the  host  cell 
proper.     The  oocysts  typically  contain 
many  sporocysts.    With  one  dubious  ex- 
ception, the  Aggregatidae  are  parasites  of 
marine  annelids,   molluscs  and  Crustacea. 


Genus  MiROCYSTlS  Dalcin,  1911 

In  this  genus  the  oocysts  contain  num- 
erous sporocysts,  each  with  2  sporozoites. 
A  single  species,   M.  kathae,    has  been 
named.    It  occurs  in  the  kidney  of  the 
whelk,   Buccinuni  undatiim. 

In  addition,  Paichuk  (1953)  described 
oocysts  in  the  feces  of  several  pigs  in 
Kazakhstan  which  he  called  Merocystis 
sp.    The  oocysts  are  short-oval,  almost 
spherical,   34  to  43  by  30  to  37 ^t  with  a 
mean  of  38.7  by  33.  Ojix.     The  oocyst  wall 
is  smooth,   2y.  thick,  composed  of  3  layers 
of  which  the  outer  is  dark  brown,  the  mid- 
dle bright  green  and  the  inner  yellow-green 
or  bright  brown.     The  oocyst  wall  is  very 
fragile.     The  number  of  sporocysts  is  un- 
known, but  more  than  13.     The  sporocysts 
are  spherical,  9  to  13 /i  in  diameter  with 
a  mean  of  9. 1  jj, .     The  presence  of  an 
oocyst  polar  granule  is  unknown.     The 
oocyst  and  sporocyst  residua  are  com- 
posed of  dispersed  granules.     The  sporo- 
zoites are  spherical,  4.3/i  in  diameter. 
Altho  Paichuk  assigned  this  form  to  the 


THE  TELOSPORASIDA  AND  THE  COCCIDIA   PROPER 


247 


genus  Merocystis,  it  is  much  more  prob- 
ably Adelea  or  Adelina,  both  of  which 
occur  in  arthropods,  and  it  may  well  be  a 
parasite  of  some  arthropod  which  the 
pigs  had  eaten. 


FAMILY   LANKESTERELLIDAE 

Members  of  this  family  are  hetero- 
xenous,  with  2  hosts.    Schizogony,  game- 
togony  and  sporogony  all  take  place  in  a 
vertebrate  host.     The  sporozoites  enter 
the  blood  cells  and  are  taken  up  by  a 
blood-sucking  invertebrate  (a  mite  or 
leech).    They  do  not  develop  in  this  host, 
but  are  transferred  to  the  vertebrate  host 
when  the  latter  eats  the  invertebrate,  or 
possibly  by  injection.    In  the  vertebrate 
host,  development  takes  place  in  the  host 
cells  proper.     The  oocysts  contain  no 
sporocysts,  but  have  8  or  more  sporo- 
zoites, the  number  depending  on  the  genus. 
The  microgametes  have  2  flagella  so  far 
as  is  known.    There  are  2  genera  in  this 
family:    Lankesterella,  which  occurs  in 
birds  and  amphibia,  and  Schellackia, 
which  occurs  in  reptiles. 


Genus  LANKESTERELLA  Labbe,  1899 

In  this  genus  the  oocysts  contain  32 
or  more  naked  sporozoites.    The  vectors 
are  leeches  or  mites. 

The  type  species,  and  the  only  one 
known  for  a  long  time,  is  L.  minima, 
a  parasite  of  the  frog.    However,   Lainson 
(1959)  recently  showed  that  the  genus 
Atoxoplasma  Garnham,  1950  is  a  synonym 
of  Lankesterella,  enlarging  the  genus  con- 
siderably and  clearing  up  a  question  which 
has  puzzled  parasitologists  for  years. 

The  parasites  now  known  to  be  sporo- 
zoites of  Lankesterella  are  found  fre- 
quently in  the  lymphocytes  and  other  blood 
cells  of  wild  birds.    They  had  been  thought 
to  be  Haemogregarina  or  Toxoplasma,  but 
Garnham  (1950)  showed  that  they  were 
definitely  not  the  latter  and  therefore 
called  them  Atoxoplasma. 


The  names  and  accepted  species  of 
the  genus  are  still  in  a  highly  confused 
state  (Laird,   1959;  Lainson,   1959). 

Lankesterella  adiei  (Aragao,  1933) 
Lainson,   1959  (syns.  ,   L.  passeris  Raf- 
faele,   1938;  L.  garnham i  Lainson,   1959) 
is  a  common  parasite  of  the  English 
sparrow  thruout  the  world.     Lainson 
(1959)  found  it  in  all  of  99  adult  and  150 
fledgling  English  sparrows  in  England, 
Manwell  (1941)  and  Manwell  et  al.  (1945) 
reported  that  it  was  common  in  passerine 
birds,  and  D.  D.  Myers  (unpublished) 
found  it  commonly  in  English  sparrows  in 
Illinois.     The  sporozoites  occur  in  the 
lymphocytes  and  monocj^es,   and  often 
cause  a  pronounced  indentation  of  the  host 
cell  nucleus.     They  are  typically  sausage- 
shaped  with  rounded  ends,  stain  weakly 
and  lack  a  well  defined  periplast,  so  that 
it  is  often  difficult  to  differentiate  their 
cytoplasm  from  that  of  the  host  cell. 
Their  nucleus  is  diffuse  and  granular, 
with  a  tiny  karyosome.     They  measure  4 
to  5  by  2  to  4  fi  according  to  Lainson  (1959). 

The  life  cycle  of  L.  adiei  was  des- 
cribed (under  the  name   L.  garnliami)  by 
Lainson  (1959).    Schizogony  takes  place 
in  the  lymphoid-macrophage  cells  of  the 
spleen,  bone  marrow  and  liver.    There 
are  2  types  of  schizont,  one  producing  10 
to  30  (average  16)  oval  merozoites  meas- 
uring 4  by  2  (i  ,  and  the  other  producing  a 
smaller  number  of  larger  merozoites 
measuring  6  by  3.  5|ll.    Gametogony  and 
sporogony  take  place  in  the  lymphoid- 
macrophage  cells  of  the  liver,   lungs  and 
kidney.    The  microgametocytes  resemble 
those  of  Eimeria  and  produce  60  to  100 
microgametes.     The  macrogametes  are 
about  14.  5 /J,  in  diameter  when  mature  and 
produce  a  large  but  unspecified  number  of 
sporozoites  measuring  about  3.6  by  1.8)i. 
The  vector  is  presumably  the  common  red 
mite,  Dermanyssus  gallinae,  but  Lainson 
was  unable  to  prove  this  because  he  had 
no  uninfected  receptor  birds. 

According  to  Lainson  (1958),  Lanke- 
sterella may  cause  congestion  and  hemor- 
rhage of  the  blood  vessels  and  inflamma- 


248 


THE  TELOSPORASHDA  AND  THE  COCCIDLA   PROPER 


tory  foci  in  the  liver  and  lungs  of  infected 
English  sparrows.    Manwell  (1941)  stated 
that  infections  seemed  to  spread  rapidly 
among  adult  English  sparrows  from  New 
York  after  they  had  been  captured  and 
kept  in  relatively  close  quarters  in  the 
laboratory.     He  found  that  the  disease  was 
not  infrequently  fatal,  but  that  chronic 
cases  also  occurred.     The  liver  and  spleen 
were  greatly  enlarged  and  very  dark  in  one 
bird  which  he  necropsied,  but  there  were 
no  hematin  granules  in  either  organ. 
D.  D.  Myers  (unpublished)  also  observed 
deaths  from  this  infection  in  captured 
English  sparrows  in  Illinois. 

Lankesterella  serini  Lainson,   1959 
was  discovered  in  canaries  when  Lainson 
wanted  to  infect  them  with  L.  adici  from 
the  English  sparrow  and  found  that  they 
already  had  an  infection  of  their  own.     It 
apparently  resembles  L.  acUci.     Nothing 
is  known  about  its  pathogenicity.     Perhaps 
the  "x-bodies"  or  "Einschliisse"  which 
occur  in  the  macrophages  of  the  lungs, 
liver  and  spleen  of  canaries  (Manwell 
eL  al.  ,   1945)  belong  to  this  species. 


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Wehr,    E.    E.  ,   M.   M.    Farr  and  ].   L.   Gardiner.      1949.     Ann. 

N.   Y.   Acad.    Sci.     52:571-578. 
Wenyon,    C.   M.      1923.     Ann.   Trop.   Med.   Parasit.    17:231-288. 
Wenyon,    C.   M.     1926.     Protozoology.     2  vols.     Wood,   New 

York,    pp.   xvi  +  1563. 
Wenyon,    C.    M.      1926a.     Parasit.      18:253-266. 
Wenyon,    C.   M.  and  L.    Sheather.      1925.     Trans.    Roy.    Soc. 

Trop.   Med.   Hyg.     19:10. 
Wetzel,    R.   and  K.    Enigk.      1936.     Sitzungsber.   Ges.   Natur- 

forsch.     Freunde,    Berlin  21(IV):  162- 164. 


Whitten,    L.    K.     1953.     New  Zeal.   Vet.    J.     1:78-80. 
Wilson,    1.   D.      1931.     Va.  Ag.   Exp.   Sta.   Tech.   Bui.   #42. 

pp.  42. 
Wilson,   ].    E.      1951.     Vet.    Rec.     63:373-377. 
Yakimoff,    W.    L.      1933.     Ann.   Soc.   Beige  Med.   Trop. 

13:93-130. 
Yakimoff,    W.   L.      1933a.     Bull.    Soc.   Path.   Exot.     26:1192- 

1208. 
Yakimoff,    W.    L.      1936.     Arch.    Inst.   Biol.    Sao  Paulo    7:167- 

187. 
Yakimoff,    W.   L.  ,    W.   P.   Baskakoff,    W.    F.   Gousseff,    S.   N. 

Matschulsky,    W.   J.  Mizkewitsch,    E.    F.    Rastegaieff  and 

Keschner.      1936.     Berl.   Tierarztl.   Wchnschr.     52:358-362. 
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tist.     70:185-191. 


Chapter  9 


These  genera  belong  to  the  suborder 
Adeleorina,  which  is  differentiated  from 
the  Eimeriorina  and  Haemospororina  by 
the  fact  that  the  macrogamete  and  micro- 
gametocyte  are  associated  in  syzygy 
(i.e. ,  they  lie  up  against  each  other)  dur- 
ing development.     Correlated  with  this  is 
the  fact  that  the  microgametocytes  pro- 
duce very  few  microgametes.     The  zygote 
may  or  may  not  be  motile,  and  the  sporo- 
zoites  are  enclosed  in  an  envelope. 

The  great  majority  of  the  Adeleorina 
are  parasites  of  lower  vertebrates  and  in- 
vertebrates, but  a  few  occur  in  domestic 
and  laboratory  animals. 


KLOSSIBUA 

Am 

HEPATOZOOU 


FAMILY    KLOSSIELLIDAE 

In  this  family,  the  zygote  is  not  mo- 
tile.   A  typical  oocyst  is  not  formed,  but 
a  number  of  sporocysts  each  containing 
many  sporozoites  develop  within  a  mem- 
brane which  is  perhaps  laid  down  by  the 
host  cell.     Each  microgametocyte  forms 
2  to  4  non-flagellated  microgametes.    The 
life  cycle  involves  a  single  host,  game- 
togony  and  schizogony  occurring  in  differ- 
ent locations.     There  is  a  single  genus, 
Klossiella. 


Genus  Ki.OSS\mi\  Smith  and 
Johnson,  190:2 

This  genus  has  the  characters  of  the 
family. 

Infection  takes  place  by  ingestion  of 
sporulated  sporocysts,  and  the  sporozoites 
pass  into  the  blood  stream  and  enter  the 
endothelial  cells  of  the  capillaries  and 
arterioles  of  the  kidneys,   lungs,  spleen 
and  other  organs.     Here  they  turn  into 
schizonts,  and  these  then  produce  mero- 
zoites.     There  are  probably  several 
asexual  generations. 

Eventually  some  merozoites  enter  the 
epithelial  cells  of  the  convoluted  tubules 


-  254 


KLOSSIELLA   AND  HEPATOZOON 


255 


of  the  kidney,  where  they  become  gamonts 
and  where  gametogony  and  sporogony  take 
place.    A  macrogamete  and  microgameto- 
cyte  are  found  together  in  syzygy  within  a 
vacuole  in  the  host  cell.     The  microgame- 
tocyte  divides  to  form  2  to  4  microgam- 
etes,  one  of  which  fertilizes  the  macro- 
gamete.     The  resultant  zygote  (sporont  or 
mother  sporoblast)  divides  by  multiple 
fission  to  form  a  number  of  sporoblasts. 
Each  of  these  develops  into  a  sporocyst 
containing  8  to  25  or  more  sporozoites. 
The  sporocysts  are  enclosed  within  a 
membrane,  but  all  authorities  do  not  agree 
whether  it  is  a  true  oocyst  or  simply  the 
remnant  of  the  host  cell. 

The  sporocysts  are  released  into  the 
lumen  of  the  kidney  tubules  by  rupture  of 
the  host  cell,  and  pass  out  in  the  urine. 


KLOSSIELLA  EQUI 
BAUMANN,   1946 

Synonym:     Einieria  utinensls  (?). 

Hosts:     Horse,  ass. 


Location:     Kidneys. 

Geographic  Distribution: 
Turkey,   North  America. 


Europe, 


Prevalence:     Unknown.    This  species 
has  been  encountered  only  in  the  course  of 
histopathologic  examinations  of  the  kidney 
for  some  other  reason.     Baumann  (1946) 
found  it  in  the  kidney  of  a  horse  from 
Hungary  which  had  died  of  pneumonia, 
Seibold  and  Thorson  (1955)  found  it  in  the 
kidney  of  a  jackass  in  Alabama  which  had 
died  of  spinal  injuries  incurred  while  he 
was  being  roped.    Akcay  and  Urman(1954) 
found  it  on  histopathologic  examination  of 
the  kidneys  of  72  out  of  117  donkeys  in  the 
course  of  an  experiment  on  infectious 
anemia. 

Morphology:     The  stages  in  the  kidney 
are  the  only  ones  known.    These  are  found 
in  the  epithelial  cells  lining  the  thick 
limbs  of  Henle's  loops  in  the  medullary 
rays.    Schizonts  and  merozoites  have  not 
been  recognized.    The  macrogametes  and 


microgametocytes  develop  in  syzygy.     The 
latter  form  4  microgametes  (Baumann, 
1946).     After  fertilization,   the  zygote 
grows  to  38  to  46  by  32  to  39  \i  and  pro- 
duces a  large  number  of  sporoblasts  by 
multiple  nuclear  fission  followed  by  bud- 
ding from  a  large,   central  residual  mass. 
Each  sporoblast  develops  into  a  sporocyst. 
The  fully  developed  "oocysts"  are  thin- 
walled  sacs  50  to  90  by  35 /i  containing  as 
many  as  40  ovoid  sporocysts  measuring 
8  to  10  by  4  to  5  (i  .     Each  sporocyst  con- 
tains 8  to  12  sporozoites.    Seibold  and 
Thorson  (1955) found  40  sporocysts  in  a 
cross  section  of  one  of  the  largest  sacs 
they  saw,   so  there  must  have  been  many 
more  actually  present. 

Pathogenesis:     Apparently  non-patho- 
genic. 

Remarks:     Pachinger  (1886)  des- 
cribed parasites  resembling  EiDieria  fal- 
ciformis  in  the  kidneys  of  3  horses.    These 
were  almost  certainly  K.  equi.     Selan  and 
Vittorio  (1924)  described  a  parasite  from 
the  lungs  and  gall  bladder  of  a  horse  in 
Italy  which  they  called  Eimeria  utinensis. 
Their  description  was  too  poor  to  be  sure 
what  they  actually  saw,  but  it  may  perhaps 
have  been  a  stage  of  K.   equi. 


OTHER  SPECIES  OF  KLOSSIELLA 

Klossiella  muris  Smith  and  Johnson, 
1902  is  apparently  fairly  common  in  lab- 
oratory mice  thruout  the  world,  but  has 
been  reported  only  once  in  wild  house 
mice.    In  the  laboratory  colonies  in  which 
it  is  found,   20  to  100%  of  the  mice  are  in- 
fected.   Each  microgametocyte  forms  2 
microgametes.     Each  sporont  forms  12  to 
16  sporocysts,  each  of  which  contains 
about  25  to  34  banana-shaped  sporozoites. 
K.  muris  is  ordinarily  non-pathogenic, 
altho  in  heavy  infections  the  kidneys  may 
have  minute,  greyish,  necrotic  foci  over 
their  entire  surface,  and  the  epithelium 
of  the  infected  kidney  tubules  is  destroyed 
(Smith  and  Johnson,   1902).     Otto  (1957) 
described  a  perivascular,  follicular, 
lymphocytic  infiltration  in  the  region  of 
the  medullary  cortex  which  he  considered 
of  diagnostic  significance.    There  is  no 


256 


KLOSSIELLA   AND  HEPATOZOON 


inflammatory  reaction.    No  fatal  infec- 
tions have  been  reported. 

Klossiella  cobayae  Seidelin,  1914 
occurs  sporadically  in  the  guinea  pig 
thruout  the  world.     Each  microgametocyte 
forms  2  microgametes.     Each  sporont 
forms  30  or  more  sporocysts,  each  of 
which  contains  about  30  sporozoites.    K. 
cobayae  is  apparently  non-pathogenic  and 
produces  slight  if  any  pathologic  changes 
in  the  kidney.     However,   it  may  be  en- 
countered in  sections  of  the  kidney  or 
other  organs  which  are  being  examined 
for  something  else,  as  C.   C.   Morrill  and 
I  (unpublished)  did  in  some  guinea  pigs  at 
the  University  of  Illinois. 


FAMILY    HEPATOZOIDAE 

In  this  family  the  zygote  is  active  (an 
ookinete),   secreting  a  flexible  membrane 
which  is  stretched  during  development. 
The  life  cycle  involves  2  hosts,   1  of  which 
is  vertebrate  and  the  other  invertebrate. 
The  parasites  are  found  in  the  cells  of 
the  circulatory  system  of  vertebrates  and 
of  the  digestive  system  of  invertebrates. 
The  oocysts  are  large  and  contain  many 
sporocysts,  each  with  4  to  12  or  more 
sporozoites.     There  is  a  single  genus, 
Hepatozoon. 


Genus  HfPATOZOON  Miller,  1908 

In  this  genus  schizogony  takes  place 
in  the  viscera  of  a  vertebrate,  and  the 
gametocytes  are  either  in  the  leucocytes 
or  erythrocytes,  depending  on  the  species. 
Fertilization  and  sporogony  occur  in  a 
tick,   mite,   louse,  tsetse  fly,  mosquito  or 
other  blood-sucking  invertebrate,  de- 
pending again  on  the  species.     The  micro- 
gametocyte forms  2  microgametes.    A 
synonym  of  this  generic  name  is  Leucocy- 
togregarina . 

Species  of  Hepatozoon  have  been 
described  from  mammals,   reptiles  and 
birds.     They  ai-e  especially  common  in 
rodents. 

The  vertebrate  hosts  become  infected 
by  eating  the  invertebrate  hosts.    The 


sporozoites  are  released  in  the  intestine, 
penetrate  its  wall  and  pass  via  the  blood 
stream  to  the  liver,   lungs,  spleen  or  bone 
marrow;  different  species  prefer  different 
organs.     The  sporozoites  enter  the  tissue 
cells  and  become  schizonts,  which  divide 
by  multiple  fission  to  produce  a  number  of 
merozoites.     There  are  several  asexual 
generations  in  the  visceral  cells,  but  their 
number  is  known  in  only  a  few  cases.    The 
last  generation  merozoites  enter  the  blood 
cells  and  become  gamonts.     These  look 
alike;  presumably  the  female  is  a  macro- 
gamete  and  the  male  a  microgametocyte, 
but  no  evidence  is  available  on  this  point. 

No  further  development  takes  place 
until  the  parasites  reach  the  alimentary 
tract  of  the  intermediate  host.     The  ga- 
monts then  leave  their  host  cells,  asso- 
ciate in  syzygy,  and  the  microgametocyte 
forms  2  non-flagellate  microgametes. 
These  are  relatively  large,   but  smaller 
than  macrogametes.    One  of  them  ferti- 
lizes the  macrogamete,  and  the  resultant 
ookinete  penetrates  the  intestinal  wall  and 
comes  to  lie  in  the  haemocoel.     Here  it 
grows  considerably  and  becomes  an  oocyst. 
Several  nuclear  divisions  take  place  in  the 
sporont  within  the  oocyst  wall.     The  daugh- 
ter nuclei  migrate  to  its  periphery,  and 
each  one  buds  off  to  form  a  sporoblast, 
leaving  a  large  residual  mass.     The  sporo- 
blasts  then  form  a  wall  around  themselves, 
becoming  sporocysts.     Sporozoites  develop 
in  the  sporocysts,  their  number  depending 
on  the  species.     When  the  vertebrate  host 
ingests  the  invertebrate  one,  the  oocysts 
and  sporocysts  rupture  in  its  intestine, 
releasing  the  sporozoites. 

It  is  possible  that  trans-placental  in- 
fection may  also  occur,  at  least  in  some 
species.    At  any  rate,   Clark  (1958)  found 
a  full-blown  infection  with  H.  i^riseisciuri 
in  a  36-hour-oId  grey  squirrel  which  had 
been  born  in  a  mite-free  environment. 


HEPATOZOON  CAMS 
(JAMES,   1905) 

Synonyms:     Leucocylozoon  cauls, 
Hac'Diogyegarina  caiiis,  Haeniogregarina 
yolundata,  HacDiogregariiia  chatloiii, 
Hepatozoon  felis . 


KLOSSIELLA   AND  HEPATOZOON 


2S7 


Disease:     Hepatozoonosis. 

Hosts:     Dog,  cat,  jackal,   hyena  and 
palm  civet  or  musang  {Payadoxurns 
herniaphroditns).    The  forms  described 
from  the  cat,  jackal  and  hyena  under  the 
names  H.   felis,  H.  rotitndata  and  H. 
cliai/oni.   respectively,  are  practically 
indistinguishable  morphologically,  and 
are  probably  all  the  same  species.     Laird 
(1959)  believed  that  the  form  he  found  in 
the  palm  civet  in  Malaya  was  H.   caiiis. 

Location:     The  schizonts  are  in  the 
spleen,  bone  marrow  and  to  a  lesser  ex- 
tent in  the  liver.     The  gamonts  are  in  the 
polymorphonuclear  leucocytes. 

Geographic  Distribution:     India, 
Malaya,  Singapore,  Indochina,   Central 
Africa,   North  Africa,   Middle  East,  Italy. 
This  species  is  well  known  in  dogs,  but 
has  been  reported  from  cats  only  by 
Patton  (1908)  in  Madras  (Laird,   1959). 

Morphology:     The  gamonts  in  the 
leucocytes  are  elongate  rectangular  bodies 
with  rounded  ends  measuring  about  8  to  12 
by  3  to  6|_L,  and  with  a  central,  compact 
nucleus.    Their  cytoplasm  stains  pale  blue 
and  their  nucleus  dark  reddish  with 
Giemsa  stain.     They  are  surrounded  by  a 
delicate  capsule.     They  may  emerge  from 
the  leucocytes  and  capsule  and  lie  free  in 
citrated  blood.     Leitao  (1945)  saw  schi- 
zonts in  the  circulating  blood  which  he 
said  were  difficult  to  distinguish  from 
platelets. 

Life  Cycle:     The  life  cycle  of  H. 
canis  was  worked  out  by  Christophers 
(1906,   1907,   1912)  and  Wenyon  (1911). 
Schizogony  takes  place  in  the  spleen  and 
bone  marrow,  and  Rau  (1925)  saw  it  in  the 
liver  also.     There  are  several  types  of 
schizonts.    One  type  produces  a  small 
number  (usually  3)  of  large  merozoites, 
another  type  produces  a  large  number  of 
small  merozoites,  and  intermediate  types 
produce  merozoites  of  intermediate  num- 
bers and  size.    The  small  merozoites  are 
the  ones  which  enter  the  leucocytes  to 
form  gamonts. 

The  vector  is  the  brown  dog  tick, 
Rhipiceplialus  sanguineus .     Both  the 


nymph  and  adult  can  transmit  the  infection, 
but  there  is  no  transovarian  transmission. 
The  oocysts  are  found  in  the  haemocoel. 
They  are  about  100  fi  in  longest  diameter 
and  contain  30  to  50  sporocysts  15  to  16/1 
long,  each  containing  about  16  banana- 
shaped  sporozoites  and  a  residual  body. 
Dogs  become  infected  by  eating  infected 
ticks. 

Pathogenesis:     H.   canis  has  often 
been  found  in  apparently  healthy  dogs,  but 
it  may  also  cause  serious  disease  and 
death  (Rau,   1925;  Rahimuddin,   1942). 
The  principal  signs  are  irregular  fever, 
progressive  emaciation,  anemia  and 
splenomegaly.     Lumbar  paralysis  has 
also  been  reported.     Affected  dogs  may 
die  in  4  to  8  weeks. 

Diagnosis:     Hepatozoonosis  can  be 
diagnosed  by  identifying  the  gamonts  in 
stained  blood  smears  or  in  stained  smears 
of  spleen  pulp,  bone  marrow  or  liver. 

Treatment:     Unknown. 


Prevention  and  Control:     Since//. 
canis  is  transmitted  by  the  brown  dog 
tick,  elimination  of  ticks  will  eliminate 
the  disease. 


OTHER  SPECIES  OF   HEPATOZOON 

Hepatozoon  niuris  (Balfour,   1905) 
occurs  in  the  wild  and  laboratory  Norway 
rat  and  black  rat  thruout  the  world. 
Schizogony  takes  place  in  the  parenchymal 
cells  of  the  liver,  and  the  gamonts  are 
found  in  the  monocytes  and  rarely  in  the 
polymorphonuclear  leucocytes.     The  vector 
is  the  spiny  rat  mite,   Ecltinolaelaps 
echidninus.    Massive  infections  may  cause 
marked  degenerative  changes  in  the  liver 
and  death,  but  little  or  no  effect  has  been 
observed  in  lightly  infected  wild  rats. 

Hepatozoo)!  nnisculi  (Porter,   1908) 
was  reported  from  the  white  mouse  in 
England.     It  differs  from  H.  niuris  in  that 
schizogony  takes  place  only  in  the  bone 
marrow. 

Hepatozoon  cuniculi  (Sangiorgi,   1914) 
was  reported  from  the  domestic  rabbit  in 


258 


KLOSSIELLA   AND  HEPATOZOON 


Italy.    Its  gamonts  are  found  in  the  leu- 
cocytes and  its  schizonts  in  the  spleen. 

Hepalozoon  griseisciuri  Clark,   1958 
is  common  in  the  grey  squirrel  {Scittrus 
carolincnsis)  in  the  United  States.     Clark 
(1958)  described  its  life  cycle.    Schizogony 
takes  place  in  the  spleen,  liver  and  bone 
marrow,   and  the  gamonts  are  found  in  the 
monocytes.    The  natural  vector  is  the 
mite,  Euhaetnogmnasus  ambidans,   but 
Echinolaelaps  echidninus  can  act  as  a 
vector  experimentally. 


LITERATURE  CITED 

Akjay,    S.   and  H.    K.   Urmon.     1954.     Deut.   Tierarztl. 
Wchnschr.     61:393. 


Boumann,    R.     1946.     Wien.   Tierarztl.  Monatschr.     33:257-  260. 
Chriaophers,    S.   R.     1906.     Sci.  Mem.   Off.   Med.   G  San. 

Dep.   Govt.   India,   N.  S.     26:1-16. 
Christophers,   S.  R.     1907.     Sci.  Mem.  Off.  Med.  G  Son. 

Dep.  Govt.  India,  N.  S.     28:1-11. 
Christophers,   S.  R.     1912.     Parasit.     5:37-48. 
Clarl<,    G.  M.     1958.     J.   Parasit.     44:52-63. 
Laird,   M.     1959.     J.  Protozool.     6:316-319. 
Leieao,    S.     1945.     An.   Inst.  Med.  Trop.     2:217-226. 
Otto,    H.     1957.     Frankfurt.  Ztschr.  Path.     68:41-48. 
Pachinger,   A.     1886.     Zool.  Anz.     9:471-472. 
Patton,    W.   S.     1908.     In  Ann.   Rep.   Bact.   Sec.   King  Inst. 

Protect.  Med.,    Guindy,    1907,   Madras,     (cited  by 

Laird,    1959) 
Rahimuddin,   M.     1942.     Ind.  Vet.  ].     19:153-154. 
Rau,   M.  A.  N.     1925.     Vet.   ].      81:293-307. 
Seibold,   H.   R.  and  R.   E.   Thorson.     1955.     J.  Parasit. 

41:285-288. 
Solan,    U.  and  A.  Vittorio.     1924.     Clin.  Vet.     47:587-592. 
Smith,   T.   and  H."  P.  Johnson.     1902.     J.   Exp.  Med.     6:303-  316. 
Wenyon,    C.  M.     1911.     Parasit.     4:273-344. 


These  genera  belong  to  the  suborder 
Haemospororina,  which  is  differentiated 
from  the  Eimeriorina  and  Adeleorina  by 
the  facts  that  the  microgametocyte  pro- 
duces a  moderate  number  of  microgametes 
and  the  sporozoites  are  naked.     The  gam- 
onts  are  similar  and  develop  independently. 
The  zygote  is  motile  (i.e.  ,  it  is  an  ookinete). 
All  species  are  heteroxenous;  schizogony 
takes  place  in  a  vertebrate  host,  and  spor- 
ogony  in  an  invertebrate.     If  the  erythro- 
cytes are  invaded,   pigment  (hemozoin)  is 
formed  from  the  host  cell  hemoglobin. 

This  suborder  was  customarily  div- 
ided into  2  families,  the  Plasmodiidae 
containing  the  genus  Plasmodium,  and  the 
Haemoproteidae  containing  the  genera 
Haenioprotens  and  Leiicocytozoon.    The 
principal  difference  was  that  in  the  Plas- 
modiidae schizogony  was  thought  to  take 
place  only  in  the  erythrocytes,  while  in 
the  Haemoproteidae  it  takes  place  in  the 
lungs,  liver,   spleen,  kidneys  and  other 
internal  organs.     However,  when  the  com- 
plete life  cycles  of  several  species  of 
avian  and  human  Plas)}io(lium  were  worked 
out  (Huff  and  Coulston,   1944,   1946;  Shortt 
and  Garnham,   1948;  Short  et  al.  ,  1951; 
Garnham,   1954;  Bray,   1957),  it  was  real- 
ized that  schizogony  may  occur  both  within 
the  erythrocytes  and  exoerythrocytically. 
The  distinction  between  the  two  families 
is  thus  an  artificial  one,  and  there  is  no 
point  in  retaining  more  than  a  single  fam- 
ily in  the  suborder. 

It  is  likely,  as  Manwell  (1955)  has 
suggested,  that  the  Haemospororina  may 
well  have  arisen  from  the  coccidia  of  ver- 
tebrates rather  than  from  those  of  insects, 
as  had  been  more  commonly  supposed. 
Genera  like  Lankesterella  and  Schellackla, 
in  which  schizogony,  gametogony  and 
sporogony  all  take  place  in  the  vertebrate 
host  and  in  which  the  sporozoites  invade 
the  blood  cells  and  are  transmitted  by 
mites  or  other  blood-suckers,  could  well 
be  the  starting-point  for  the  transition 
from  the  Eimeriorina  to  the  Haemospor- 
orina. 


'■4^^  MAiS, 


KY  ]^| 


Chapter  10 


PLASMODIUM 
HAEMOPROTEUS 

AND 
LEUCOCYTOZOON 


-  259 


260 


PLASMODHJM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


FAMILY    PLASMODIIDAE 

This  family  has  the  characters  of  the 
suborder.     Its  taxonomy  has  been  reviewed 
by  Garnhan  (1953)  and  Bray  (1957).     These 
authors  preferred  to  split  the  classical 
genus  Plasniodtion  into  several  genera, 
based  on  the  life  cycles  of  their  species, 
but  it  is  simpler  not  to  do  so. 

Genus  PLASMODIUM   Marchiafava 
and   Celli,   1885 

The  gametocytes  occur  in  the  erythro- 
cytes.   Schizogony  takes  place  in  the  ery- 
throcytes and  also  in  various  other  tis- 
sues, depending  on  the  species.     The  exo- 
erythrocytic  ("e.e.")  schizonts  are  solid 
or,  at  the  most,  vacuolated  bodies.     Mem- 
bers of  this  genus  are  parasites  of  mam- 
mals, birds  and  lizards.     They  are  trans- 
mitted by  mosquitoes.  Anopheles  trans- 
mitting the  mammalian  species,  and 
culicines  or  sometimes  Anopheles  the 
avian  and  reptilian  ones. 

Members  of  this  genus  cause  malaria, 
which  is  still  the  most  important  disease 
of  man.     They  also  cause  a  similar  dis- 
ease in  birds.     Coatney  and  Roudabush 
(1949)  have  cataloged  the  species  of  Plas- 
modium, and  other  species  are  discussed 
by  Bray  (1957).     Man  has  4  species,  higher 
apes  4,   lower  apes  and  lemurs  7,   rodents 
2,  and  bats  1.     Birds  have  14  or  15  valid 
species  (Hewitt,   1940;  Bray,   1957;  Laird 
and  Lari,   1958). 

Life  Cycle:     The  life  cycle  of  Plas- 
modluin  vivaxoi  man  is  representative. 
The  sporozoites  enter  the  blood  thru  a 
mosquito  bite.     They  stay  in  the  blood  less 
than  an  hour,  quickly  entering  liver  par- 
enchymal cells.     Here  they  become  schi- 
zonts (known  as  cryptozoites  from  their 
location),  which  enlarge  and  divide  by 
multiple  fission  to  form  metacryptozoites 
(a  type  of  merozoite).    These  enter  new 
liver  parenchymal  cells,  undergo  multiple 
fission,  and  form  new  metacryptozoites. 
This  process  may  go  on  indefinitely  in  P. 
vivax,   but  in  another  human  species,  P. 
falciparnni ,   there  is  only  a  single  genera- 
tion of  metacryptozoites. 


The  metacryptozoites  break  out  of  the 
liver  cells,  pass  into  the  blood  stream  and 
enter  the  erythrocytes  about  a  week  to  10 
days  after  infection.     Here  they  round  up 
and  develop  a  large  vacuole  in  their  cen- 
ter.   They  are  called  ring  stages  because 
in  Romanowsky  stained  smears  they  re- 
semble a  signet  ring,  with  a  red  nucleus 
at  one  edge  and  a  thin  ring  of  blue  cyto- 
plasm around  the  vacuole.     These  grow 
and  are  now  called  schizonts  or  tropho- 
zoites. 

The  trophozoites  were  formerly 
thought  to  obtain  their  nutriment  sapro- 
zoically,  but  Rudzinska  and  Trager  (1957) 
showed  in  an  electron  microscope  study 
of  P.   lophurae  of  the  duck  that  they  are 
holozoic  as  well.    They  form  food  vacuoles 
containing  host  cell  cytoplasm  by  invagina- 
tion.    The  hematin  pigment  granules  are 
formed  within  these  food  vacuoles  by  di- 
gestion of  the  hemoglobin.    This  study, 
incidentally,   settled  once  and  for  all  the 
question  which  is  raised  perennially  as  to 
whether  Plasmodium  occurs  within  or  on 
the  surface  of  the  host  cell;  it  is  within  it. 

The  trophozoites  undergo  schizogony 
to  produce  merozoites,  the  number  depend- 
ing on  the  species.     These  break  out  of  the 
erythrocytes,  enter  new  ones,   and  repeat 
the  cycle  indefinitely. 

The  length  of  each  cycle  depends  on 
the  parasite  species.    It  is  2  days  in  P. 
vivax  and  P.  falciparum,  and  3  days  in 
another  human  species,  P.  malariae. 
Practically  all  the  parasites  are  generally 
in  the  same  stage  of  the  cycle  at  the  same 
time,   so  all  the  merozoites  break  out  of 
the  red  cells  and  pass  into  the  blood  at  the 
same  time.    Along  with  them  go  the  hema- 
tin granules  and  other  waste  products  pro- 
duced by  the  parasites'  metabolism.    These 
are  toxic,  and  cause  a  violent  reaction  or 
paroxysm  in  the  host- -the  chills  and  fever 
characteristic  of  malaria. 

After  the  infection  has  been  present 
for  some  time  and  after  an  indefinite  num- 
ber of  asexual  generations,   some  mero- 
zoites entering  the  erythrocytes  develop 
into  macrogametes  and  others  develop  into 
microgametocytes.    The  former  are 


PLASMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


261 


customarily  called  macrogametocytes, 
but  this  name  is  incorrect  since  they  are 
haploid  from  the  start  (see  below).     They 
remain  in  this  stage  until  the  blood  is  in- 
gested by  a  mosquito. 

In  the  stomach  of  the  mosquito,  micro- 
gametes  are  produced.     The  changes  in  the 
microgametocytes  are  striking.     Within  10 
to  15  minutes  the  nucleus  divides,  and  6 
to  8  long,   heavy  flagellum-like  micro- 
gametes  are  extruded.     This  process  is 
known  as  exflagellation.     The  microgam- 
etes  break  off  and  swim  freely  until  they 
find  a  macrogamete.     Fertilization  takes 
place,  and  a  motile  zygote  (ookinete)  is 
formed. 

The  ookinete  penetrates  into  the  stom- 
ach wall  and  grows  into  an  oocyst,  which 
forms  a  ball  50  to  60 /i  in  diameter  on  the 
outer  surface  of  the  stomach.     The  oocyst 
nucleus  divides  repeatedly  and  a  number 
of  sporoblasts  are  formed.     The  nucleus 
of  each  sporoblast  then  divides  repeatedly, 
and  eventually  each  oocyst  comes  to  con- 
tain 10,000  or  more  slender,   spindle- 
shaped  sporozoites  about  15/i  long  with  a 
nucleus  in  the  center.     These  break  out  of 
the  oocyst  into  the  body  cavity  and  migrate 
to  the  salivary  glands.     They  are  then  in- 
jected into  a  new  host  when  the  mosquito 
bites  again.     The  process  of  sporozoite 
development  takes  10  days  to  3  weeks  or 
longer,  depending  on  the  species  of  Plas- 
modin))i,  the  species  of  mosquito  and  the 
temperature. 

Once  infected,  a  mosquito  remains 
infected  for  life,  and  can  transmit  the 
parasites  every  time  it  bites.     There  is  a 
case  on  record  (James,   1927)  of  a  mos- 
quito which  lived  from  August  5  to  Novem- 
ber 16  and  infected  more  than  40  general 
paresis  patients  as  part  of  their  therapy. 

In  vivax  and  malariae  malaria,   re- 
lapses are  common  and  may  occur  for  a 
number  of  years  after  the  individual  has 
had  his  first  attack.     Between  attacks  the 
parasites  are  ordinarily  not  found  in  the 
blood.    What  apparently  happens  is  that 
all  the  parasites  do  not  leave  the  liver 
when  the  metacryptozoites  emerge  into  the 
blood  stream,  but  a  few  remain  there  and 


continue  to  multiply  in  secret  until  such 
time  as  the  body's  defenses  have  decreased 
sufficiently  so  that  the  parasites  can  again 
invade  the  blood. 

There  are  several  variations  of  the 
above  general  pattern.    In  P.  falciparimi 
of  man,  there  is  only  a  single  generation 
of  metacryptozoites  in  the  liver,  and  re- 
lapses rarely  occur.     In  addition,  the 
schizonts  and  merozoites  of  this  species 
are  rarely  seen  in  the  peripheral  blood. 
Instead,  the  infected  red  cells  become 
viscid  and  clump  together  in  the  internal 
organs. 

In  the  avian  species,   exoerythrocytic 
schizogony  does  not  take  place  in  the  liver 
parenchyma,  but  either  in  the  endothelial 
cells  (P.  gallinaceiiiii .  P.   relictum,  P. 
catlienieriuDi,   P.   lophnrae.  P.  fallax,  P. 
circitiii/lexiiiii,  P.  diirae,   P.  juxtaimcleare, 
P.   hexameriitm)  or  largely  in  the  haenio- 
poietic  cells  (P.   elo)2gatiau ,  P.   vanghaiii 
and  probably  P.  Imffi  and  P.   rouxi). 

In  bird  malaria  also,  but  not  in  mam- 
malian malaria,   some  of  the  merozoites 
which  have  been  formed  in  the  erythrocytes 
are  able  to  enter  the  tissue  cells  and  de- 
velop exoerythrocytically.     They  are  known 
as  phanerozoites,  but  they  do  not  differ 
morphologically  from  the  forms  derived 
from  sporozoites. 

Plas))todiuiii  is  haploid  thruout  its  life 
cycle  except  for  a  brief  period  following 
fertilization  and  zygote  formation.     In  a 
cytologic  study  of  the  early  oocysts  of  7 
species  of  Plasmodium  in  mosquitoes, 
Bano  (1959)  found  that  the  oocysts  undergo 
meiosis  2  to  3  days  after  the  infective  blood 
meal,  the  time  depending  on  the  species. 
For  P.   vivax  it  was  48  hours,  for  P.  gal- 
linaceiDii  53  to  55  hours,  and  for  P.   inui 
72  to  79  hours.     After  that,  division  is  by 
mitosis. 

The  haploid  number  of  chromosomes 
is  2  for  P.  falciparum,   P.  malariae,  P. 
ovale,  P.   lophurae,   P.   relictum,  P. 
floridense  (Wolcott,   1955,   1957),  P.   vivax, 
P.  kiioivlesi,  P.   berghei  (Wolcott,   1955, 
1957;  Bano,   1959),  and  P.  gallinaceum 
(Bano,   1959);  it  is  3  for  P.  gonderi  and 


262 


PLASMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


4  for  P.  cynoniolgi  and  P.   inui  (Bano, 
1959). 

Cultivation:      Various  species  of 
Plasniodiiun  have  been  cultivated  in  fluid 
media  (Trager,   1947;  Anfinsen  el  al.  , 
1946;  Geiman  el  al.  ,   1946)  and  in  avian 
embryos  and  tissue  culture  (see  Pipkin 
and  Jensen,   1958  for  a  review). 


HUMAN   MALARIA 

The  following  discussion  of  human 
malaria  is  necessarily  brief.     Further 
details  and  references  can  be  found  in  any 
textbook  of  human  parasitology  and,  in 
more  detail,  in  Boyd  (1949)  and  Mac- 
donald  (1957). 

Man  has  4  recognized  species  of 
Plasmodium .    P.  falciparum  (Welch, 
1897)  Schaudinn,   1902  is  the  cause  of  ma- 
lignant tertian,  aestivo-autumnal  or  fal- 
ciparum malaria.     Paroxysms  of  chills 
and  fever  occur  every  other  day  (i.  e. ,  on 
days  1  and  3,  which  accounts  for  the  name 
"tertian").     The  ring  forms  are  about 
1/6  to  1/5  the  diameter  of  a  red  blood 
cell.     The  schizonts  and  merozoites 
("segmenters")  rarely  occur  in  the  peri- 
pheral circulation,  but  are  found  in 
clumped  erythrocytes  in  the  viscera.    The 
schizonts  are  usually  compact  and 
rounded,  with  coarse,  blackish  pigment. 
The  segmenters  occupy  2/3  to  3/4  of  the 
host  cell  and  form  8  to  32  merozoites. 
The  host  erythrocyte  is  not  enlarged  but 
contains  reddish  clefts  known  as  Maurer's 
dots  and  may  also  have  bluish  stippling. 
The  macrogametes  and  microgametocytes 
are  crescent-  or  bean-shaped,  with  pig- 
ment granules  clustered  around  a  central 
nucleus  or  scattered  except  at  the  poles. 
The  microgametocytes  have  pale  blue  cyto- 
plasm and  a  relatively  large,  pink  nucleus 
when  stained  with  Giemsa's  stain.     The 
macrogametes  have  darker  blue  cytoplasm 
and  a  more  compact,   red  nucleus. 

Plasmodium  fif ax  (Grass i  and  Feletti, 
1890)  Labbe',   1899  is  the  cause  of  benign 
tertian  or  vivax  malaria.     Paroxysms 


occur  every  other  day  as  in  falciparum 
malaria.     The  ring  forms  are  about  1  '3  to 
1/2  the  diameter  of  the  host  cell.     The 
schizonts  are  highly  active  and  sprawled 
out  irregularly  over  the  host  cell,  with 
small,  brown  pigment  granules  usually 
collected  in  a  single  mass.    The  host  cell 
is  enlarged,  pale,  and  contains  red  dots 
known  as  Schuffner's  dots.     The  segment- 
ers nearly  fill  the  host  cell  and  produce 
15  to  20  or  occasionally  up  to  32  irregu- 
larly arranged  merozoites.     The  macro- 
gametes and  microgametocytes  are 
rounded,   10  to  14fi  in  diameter  (i.  e.  , 
larger  than  normal  erythrocytes),  and  have 
fine,  brown,  evenly  distributed  pigment 
granules.     The  microgametocytes  have 
pale  blue  cytoplasm  and  a  relatively  large, 
pink  nucleus  when  stained  with  Giemsa's 
stain.     The  macrogametes  are  slightly 
larger,  with  darker  blue  cytoplasm  and  a 
small,  red  nucleus. 

Plasmodimn  malariae  (Laveran,  1881) 
Grassi  and  Feletti,   1890  is  the  cause  of 
quartan  or  malariae  malaria.    This  species 
also  occurs  naturally  in  chimpanzees  in 
West  Africa  (Garnham,   1958).     Paroxysms 
occur  every  3  days  (i.  e. ,  on  days  1  and  4). 
The  ring  forms  are  similar  to  those  of  P. 
vivax.     The  schizonts  are  more  compact 
and  rounded  or  are  drawn  out  in  a  band 
across  the  host  cell;  their  pigment  gran- 
ules are  blacker  and  coarser  than  those  of 
P.   vivax.    The  host  cell  is  not  enlarged 
and  does  not  contain  Schuffner's  dots.    The 
segmenters  nearly  fill  the  host  cell  and 
produce  6  to  12  (usually  8  or  9)  merozoites 
arranged  in  a  rosette.    The  macrogametes 
and  microgametocytes  are  rounded  and 
smaller  than  those  of  P.   vivax.     They  do 
not  quite  fill  the  host  cell  and  contain 
blacker  and  coarser  pigment  granules. 

Plasmodium  ovale  Stephens,  1922  is 
a  rare  species  which  causes  a  tertian  type 
of  malaria.    Its  ring  forms  are  similar  to 
those  of  P.  vivax.     The  schizonts  are 
usually  round,  with  brownish,  coarse, 
somewhat  scattered  pigment  granules.    The 
host  cell  is  oval,  often  fimbriated,  not 
much  enlarged,  and  contains  Schuffner's 
dots.     The  segmenters  occupy  3/4  of  the 
host  cell  and  produce  8  to  10  merozoites 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


263 


in  a  grape-like  cluster.     The  macrogametes 
and  microgametocytes  are  rounded,  occupy 
3/4  of  the  host  cell  and  have  coarse,  black 
evenly  distributed  pigment  granules. 

A  vivax-type  Plasmodium,  P.  cyno- 
molgi,  occurs  in  macaques.     Eyles,   Coat- 
ney  and  Getz  (1960)  recently  described 
accidental  laboratory  infections  of  2  hu- 
mans with  P.  c.  bastianellii  originally 
isolated  from  Macaca  iriis  from  Malaya. 
They  were  able  to  infect  2  other  humans 
experimentally  by  allowing  them  to  be 
bitten  by  infected  Anopheles  freeborni 
mosquitoes.    This  finding  and  the  presence 
of  P.  malariae  in  chimpanzees  suggest 
that  more  than  one  of  the  human  malarias 
may  be  zoonoses. 

Pathogenesis:     The  malarial  paroxysm 
is  highly  characteristic.    It  begins  with  a 
severe  chill.     The  patient  shivers  uncon- 
trollably, his  teeth  chatter,  and  he  has 
gooseflesh,  altho  his  temperature  is  actu- 
ally above  normal.     The  chill  is  followed 
by  a  burning  fever,   headache  and  sweating. 
This  gradually  subsides,  the  temperature 
falls,  and  after  6  to  10  hours  the  patient 
feels  much  better--UDtil  his  next  paroxysm. 
The  destruction  of  erythrocytes  causes 
anemia. 

After  a  certain  number  of  paroxysms, 
the  attack  of  malaria  subsides.    Relapses 
may  occur  over  a  period  of  years  in  vivax 
and  malariae  malaria,  but  this  is  rarely 
the  case  in  falciparum  malaria. 

In  general,   mortality  from  malaria  is 
higher  in  children  than  in  adults  in  endemic 
areas,  because  by  the  time  the  people  be- 
come adult  they  have  had  repeated  attacks, 
and  those  who  have  survived  have  devel- 
oped a  good  deal  of  immunity.     For  this 
reason,  if  one  wants  to  determine  the  in- 
cidence of  malaria  in  an  area,  it  is  better 
to  examine  children  than  adults. 

A  highly  fatal,  cerebral  form  of  ma- 
laria may  occur  in  falciparum  infections. 
It  is  due  to  clogging  of  the  capillaries  of 
the  brain  by  agglutinated,  infected  ery- 
throcytes. If  enough  clogging  takes  place 
in  the  viscera,  a  severe  gastro-intestinal 
disease  resembling  typhoid,  cholera  or 


dysentery  may  occur.    Another  complica- 
tion of  falciparum  malaria  is  blackwater 
fever,  which  gets  its  name  from  the  color 
of  the  urine.     There  is  tremendous  des- 
truction of  the  erythrocytes- -60  to  80% 
may  be  destroyed  in  24  hours--accompanied 
by  fever,  intense  jaundice  and  hemoglobi- 
nuria.   Severe  attacks  are  usually  fatal. 
The  cause  of  blackwater  fever  is  not  known, 
but  it  may  involve  some  sort  of  immuno- 
logical reaction  which  hemolyzes  the  ery- 
throcytes. 

Epidemiology:     Malaria  is  transmitted 
by  Anopheles  mosquitoes.     There  are  about 
200  species  of  this  genus,  but  not  all  are 
equally  good  vectors,  and  the  epidemiology 
of  the  disease  in  any  particular  locality 
depends  not  only  upon  the  terrain  and  cli- 
matic conditions,  but  also  upon  the  partic- 
ular vectors  present,  their  breeding  habits, 
food  preferences,  susceptibility  to  infec- 
tion, etc.    The  subject  is  an  extremely 
complex  one  and  cannot  be  discussed  in  de- 
tail here.     Three  examples  will  suffice. 

The  principal  malaria  vector  in  south- 
eastern United  States  is  Anopheles  quadri- 
maculatus .     This  species  breeds  best  in 
clean,  open  water  with  dense  aquatic  veg- 
etation and  abundant  flotage.    It  prefers 
bovine  to  human  blood,   however,  so  that 
the  ratio  of  livestock  to  men  in  an  area  is 
an  important  factor  in  the  transmission 
rate. 

The  principal  malaria  vector  in  the 
Solomon  Islands  is  Anopheles  farauti.    It 
breeds  in  small  ponds  and  puddles.    During 
the  Guadalcanal  campaign  of  World  War  U, 
the  profusion  of  shell  holes,  fox  holes, 
road  ruts,  etc.  provided  ideal  conditions 
for  its  propagation,  and  the  result  was  an 
explosive  outbreak  of  malaria.    It  was  con- 
trolled by  eliminating  or  draining  the  breed- 
ing places  or  spraying  them  with  fuel  oil. 

These  measures  would  not  work  in  the 
Philippines,  where  the  principal  vector  is 
Anopheles  minimus  flavirostris.     This 
species  breeds  at  the  edges  of  slow-moving 
streams  in  the  plains,   hence  quite  different 
measures,  such  as  stream  clearing, 
straightening  and  flushing,  must  be  used 
to  prevent  its  breeding. 


264 


PLASMODRTM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


Malaria  is  primarily  a  disease  of 
warmer  climates  nowadays,  but  at  one 
time  it  was  common  in  the  temperate  zone. 
Nevertheless,   malaria  is  still  the  most 
important  human  disease  from  a  global 
standpoint.     Of  the  1955  world  population 
of  2,  653  million,   1070  million  lived  in 
malarious  areas,  and  696  million  of  these 
were  protected  poorly  or  not  at  all  from 
malaria.    In  1955  there  were  still  200  to 
225  million  cases  of  malaria  in  the  world, 
with  more  than  2  million  deaths  (Diehl, 
1955). 

Malaria  control  has  eliminated  or  al- 
most eliminated  malaria  from  many  parts 
of  the  world  (Pampana  and  Russell,   1955; 
Russell,   1956,   1958;  Anonymous,   1956), 
largely  by  use  of  residual  spraying  with 
DDT  and  other  insecticides.     At  the  end 
of  World  War  II  there  were  about  4  million 
cases  of  malaria  a  year  in  southern  Europe 
from  Spain  to  Bulgaria.    In  1956  there 
were  less  than  10,000  cases  in  the  same 
area. 

Malaria  was  one  of  the  causes  of  the 
decline  of  the  Roman  empire.     The  swampy 
land  of  the  Roman  Campagna  made  it  al- 
most uninhabitable  because  of  the  disease. 
There  were  411,  602  cases  of  malaria  in 
Italy  in  1945.    Systematic  spraying  with 
DDT  was  begun  in  1946,  and  as  a  result 
only  12  cases  of  indigenous  malaria  (both 
primary  cases  and  relapses)  were  reported 
in  1953.    In  1955  there  were  only  3. 

During  World  War  I,  the  British  and 
French  landed  armies  at  Salonika,  Greece, 
with  the  objective  of  driving  into  Germany 
thru  the  back  door.    Malaria  wrecked 
their  plans  and  immobilized  their  armies. 
There  were  2  million  cases  of  malaria  in 
Greece  in  1942.     In  1950  there  were 
50,000,  and  in  1952  only  408. 

In  the  Eastern  Mediterranean  coun- 
tries, with  a  population  of  about  170  mil- 
lion, there  were  about  40  million  cases  of 
malaria  a  year  in  1949.     There  are  now 
about  14  million,  and  it  has  been  shown 
that  it  is  technically  possible  to  eliminate 
malaria  from  the  area. 

Malaria  has  been  completely  elimina- 
ted from  Sardinia  and  Sicily,  and  it  is 


practically  gone  from  Venezuela,   Brazil, 
British  Guiana,  Argentina,   Cyprus,   Ceylon 
and  parts  of  India,  to  mention  a  few  of  the 
places. 

In  the  United  States  there  were  a  mil- 
lion cases  of  malaria  a  year  among  a  pop- 
ulation of  25  million  in  12  southern  states 
during  1912  to  1915.     Before  that,  malaria 
was  an  important  disease  thruout  the  mid- 
west.   Ackerknecht  (1945)  has  given  its 
history  in  that  region  from  1760  to  1900. 
The  decrease  of  malaria  in  this  country 
was  due  only  in  small  part  to  measures 
aimed  directly  at  the  disease,  but  more  to 
agricultural  development  and  to  other, 
still  unknown,  factors.     It  was  almost  en- 
tirely eliminated  from  the  midwest,  for 
instance,  by  farm  land  drainage. 

After  World  War  II  an  intensive  cam- 
paign was  started  to  wipe  out  malaria  from 
this  country.     Residual  spraying  of  dwell- 
ings, outhouses,  barns,  etc.  was  practiced 
in  malarious  areas.     Mosquito  larval  con- 
trol measures  were  intensified.     An  attempt 
was  made  to  follow  up  every  case  diagnosed 
as  malaria,  to  get  a  blood  smear  in  order 
to  be  sure  that  it  actually  was  malaria,  and 
to  treat  it  immediately  in  order  to  prevent 
it  from  being  a  source  of  further  cases. 

During  1949  less  than  5000  cases  were 
reported  in  the  U.  S.    During  1955,  477 
cases  were  reported.     Of  these,   64  were 
appraised  by  the  U.  S.   Public  Health  Serv- 
ice, and  only  29  were  confirmed  by  blood 
smear  as  malaria.     Only  4  were  primary 
indigenous  cases.    Two  were  in  California, 
1  in  Arizona,  and  the  fourth--acquired  by 
blood  transfusion--in  Illinois.    In  1957, 
157  cases  were  reported,  of  which  138 
were  appraised  by  the  Public  Health  Serv- 
ice; 102  were  confirmed,  and  11  of  these 
were  primary  indigeiious  cases  (Dunn  and 
Brody,   1959).    In  1958,  94  cases  were  re- 
ported, of  which  61  were  confirmed.    Seven 
of  these  were  primary  indigenous  cases,  4 
of  them  resulting  from  blood  transfusions, 
and  1  natural  case  each  originating  in  Cal- 
ifornia, Arizona  and  possibly  Pennsylvania 
(Brody  and  Dunn,   1959). 

One  outbreak  of  malaria  illustrates 
what  can  happen  if  conditions  are  right 
(Brunetti,   Fritz  and  Hollister,   1954).     It 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


265 


occurred  at  a  Campfire  Girl  camp  at 
Lake  Vera,   California.    A  marine  visited 
the  camp  on  July  4,   1952,  and  spent  the' 
night.     He  had  a  malarial  relapse  while  he 
was  there,   and  was  sleeping  without  a 
mosquito  bar.    Within  a  few  weeks  the 
first  case  appeared  among  the  girls,   and 
cases  continued  to  appear  until  January  or 
February.    A  total  of  35  cases  of  vivax 
malaria  occurred  among  that  group  of 
girls  as  the  result  of  one  night's  exposure 
from  one  infected  marine. 

There  are  no  obvious  technical  or 
economic  reasons  why  malaria  could  not 
be  eradicated  from  the  Americas,  Europe, 
Australia  and  much  of  Asia  during  the 
next  quarter  century,  altho  the  situation  is 
not  so  promising  in  tropical  Africa  (Wil- 
liams,  1958).     This  can  be  done  almost 
entirely  by  residual  spraying  of  dwellings. 
The  cost  of  protection  has  been  found  to 
vary  from  11  to  45  cents  per  capita  per 
year.     Properly  conducted,   residual  house 
spraying  for  2  to  3  years  will  eradicate 
Plasmodium ,  altho  the  mosquito  vector 
may  persist.    Some  mosquitoes  have  de- 
veloped a  resistance  to  DDT,  but  this  has 
always  taken  at  least  6  years,  so  malaria 
can  be  eliminated  before  the  mosquitoes 
become  resistant. 

New  problems  result  from  disease 
control,   however.    These  are  well  illus- 
trated by  the  effect  of  malaria  control  on 
the  population  of  Ceylon.    The  birth  rate 
on  that  island  was  40  per  1000  in  1920, 
and  it  was  still  about  the  same  in  1950. 
But  the  death  rate  in  1920  was  32  per 
1000,  while  in  1950  it  was  12  per  1000, 
and  this  decrease  was  due  primarily  to 
the  elimination  of  malaria.     This  means 
that  if  both  the  present  birth  and  death 
rates  are  maintained,  the  population  of 
Ceylon  will  double  in  about  26  years.     And 
how  can  all  these  additional  millions  be 
fed?    (Stone,   1954). 

Diagnosis:     Malaria  can  be  diagnosed 
with  certainty  only  by  finding  and  identify- 
ing the  causative  organisms  in  the  blood. 
This  is  done  by  microscopic  examination 
of  smears  stained  with  one  of  the  Roman- 
owsky  stains;  Giemsa's  stain  is  best.    At 
one  time  thin  smears  were  used  almost 


entirely,  but  thick,  laked  smears  are  much 
better,   since  they  permit  a  much  larger 
amount  of  blood  to  be  examined  in  a  given 
time.    Identification  of  the  species  and 
stages  requires  skill  and  practice.    An  ex- 
cellent guide  with  outstanding  colored  illus- 
trations is  that  of  Wilcox  (1960). 

Treatment:     A  number  of  drugs  have 
been  used  in  treating  malaria.     The  first 
one  was  quinine,  the  most  active  ingredi- 
ent of  cinchona  bark,  which  was  identified 
in  1820  by  Pelletier  and  Caventou.     It  is 
both  suppressive  and  curative,  but  does 
not  prevent  relapses.     Chemically  it  is 
6-methoxy-alpha-(5-vinyl-2-quinuclidyl-4- 
quinoline-methanol). 

Quinacrine  (Atebrin,  Atabrine,  mepa- 
crine)  was  discovered  by  Mauss  and 
Mietsch  (1933)  in  Germany.    It  is  2-chloro- 
5-diethylamino-isopentylamino-7-methoxy- 
acridine  dihydrochloride.     It  was  used  ex- 
tensively during  World  War  II  when  the 
Indonesian  cinchona  plantations  were  taken 
over  by  the  Japanese.    It  is  actually  better 
than  quinine.    It  is  prophylactic  against 
falciparum  malaria  and  suppressive 
against  vivax  and  malariae  malarias.    It 
cures  attacks  of  the  disease,  but  does  not 
prevent  relapses.    One  disadvantage  is 
that  it  is  a  dye  and  stains  the  skin  yellow. 

Chloroquine  (Aralen)  is  7-chloro-4, 
4-dimethylamino-l-methylbutylaminoquin- 
oline.     It  was  developed  thru  a  crash  drug- 
testing  program  during  World  War  II  in 
which  the  Americans  tested  over  14,000 
compounds  and  the  British  about  half  as 
many.     The  results  of  the  American  effort 
are  summarized  by  Wiselogle  (1946). 
Chloroquine  appeared  too  late  to  be  used 
in  that  war  except  experimentally.    It  is 
the  most  effective  drug  known  for  the  treat- 
ment and  suppression  of  all  types  of  ma- 
laria.    The  recommended  therapeutic  dose 
is  1.  5  g  in  3  days.     Following  its  use,  fever 
subsides  in  a  day,  and  the  parasites  dis- 
appear from  the  blood  in  2  or  3  days.     The 
suppressive  dose  is  0.  3  g  weekly.     Chlor- 
oquine does  not  prevent  vivax  malaria  re- 
lapses, however. 

Primaquine  appeared  even  later  than 
chloroquine,  having  been  introduced  in 


266 


PLASMODIUM,    RAEMOPROTEUS  AND  LEUCOCYTOZOON 


1949.    It  is  8-(4-amino-l-methylbutyl- 
amino)-6-methoxyquinoline.     It  is  most 
useful  as  a  truly  curative  agent  against 
vivax  malaria,  since  it  not  only  cures 
attacks  but  prevents  relapses.    It  is  best 
used  in  combination  with  chloroquine  if 
the  patient  is  having  an  attack,  but  can  be 
used  alone  in  between  relapses  to  prevent 
further  relapses.    The  dosage  is  15  mg 
daily  for  14  days.     The  effectiveness  of 
this  drug  in  preventing  relapses  was 
proven  in  returning  Korean  veterans. 

Chlorguanide  (Paludrine,   Proguanil) 
was  developed  by  the  British  during 
World  War  H.     It  is  N-p-chlorophenyl-N- 
5-isopropylbiguanide.     It  showed  a  great 
deal  of  promise,  but  after  it  had  been 
used  for  a  while,   resistant  strains  of 
Plasmodium  appeared,  and  it  is  no  longer 
being  used. 

Pyrimethamine  (Daraprim,  Malocide) 
was  introduced  by  the  British  in  1951.    Its 
discovery  grew  out  of  the  World  War  11 
study.    It  is  2,4-diamino-5-p-chlorophenyl- 
6-ethylpyrimidine.    It  is  perhaps  the  best 
suppressive  drug  known,  altho  it  is  not 
recommended  for  the  treatment  of  malarial 
attacks.    In  single  weekly  doses  of  25  mg 
it  completely  suppresses  all  Plasmodium 
species  and  is  prophylactic  against  P. 
falciparum  and  some  strains  of  P.   vivax. 
In  addition,  it  destroys  P.  falciparum 
gametocytes,   so  that  it  has  value  in  the 
epidemiological  control  of  this  type  of 
malaria.    It  is  being  mixed  with  the  salt 
for  prophylaxis  in  some  parts  of  the 
Americas.     Unfortunately,   resistant 
strains  have  appeared  in  some  areas 
where  it  has  been  used,  and  its  eventual 
value  is  uncertain. 

Many  other  drugs  have  been  used  for 
treating  malaria,  but  these  are  the  most 
important.     At  present,  the  ones  gener- 
ally recommended  are  chloroquine,  prima- 
quine and  pyrimethamine. 


BIRD  MAiARIA 

A  tremendous  amount  of  work  has 
been  done  on  the  bird  malarias.     The 
avian  species  of  Plasmodium  lend  them- 


selves well  to  experimentation,  and,  until 
the  discovery  of  P.  bergliei  in  rodents  in 
1948,  birds  were  the  only  experimental 
animals  in  which  malaria  could  be  conven- 
iently studied.    All  the  drug  screening  for 
antimalarials  in  World  War  II  was  carried 
out  in  birds  (Wiselogle,   1946). 

About  40  species  of  Plas»wdii(i)i  have 
been  described  from  birds,  but  only  14  or 
15  are  accepted  as  valid  (Hewitt,   1940; 
Bray,   1957;  Laird  and  Lari,   1958).    Many 
wild  birds  are  commonly  infected.     The 
most  complete  general  review  of  bird 
malaria  is  that  of  Hewitt  (1940),  altho  it  is 
now  somewhat  out  of  date.     Herman  (1944) 
and  Coatney  and  Roudabush  (1949)  have 
given  catalogs  and  host-indices  of  the  spe- 
cies of  Plasmodium  in  birds.     Levine  and 
Hanson  (1953)  tabulated  reports  of  Plas- 
modium from  waterfowl,  and  Levine  and 
Kantor  (1959)  did  the  same  for  birds  of 
the  order  Columbiformes.     Other  more 
recent  general  papers  are  those  of  Becker 
(1959),   Bray  (1957),   Herman  et  al.  (1954), 
Huff  (1954)  and  Wolfson  (1941). 

Bird  malaria  is  not  of  great  veterinary 
importance,  but  it  may  occasionally  cause 
losses,  especially  in  pigeons.     Most  of  the 
species  are  not  strongly  host  specific  and 
can  infect  several  species  of  birds.    Most 
laboratory  studies  have  been  carried  out 
with  Plasmodium  cathemerium  and  P. 
relictum  in  the  canary,  P.  gallinaceum  in 
the  chicken  and  P.  lophurae  in  the  duck. 

The  avian  species  of  Plasmodium  fall 
into  2  groups,  depending  upon  whether 
their  gametocytes  are  round  or  elongate. 
Among  those  with  round  gametocytes  are 
P.  cathei)ieriu»i,  P.   relictum  and  P-  gal- 
linaceum.   Among  those  with  elongate 
gametocytes  are  P.  circumflexum ,  P. 
micleophilum ,  P.  rouxi,  P.   elongatum, 
P.  hexamerium,  P.   vaughani  and  P. 
polare.     P.  lophurae  is  somewhat  different; 
its  gametocytes  are  elongate  at  first  but 
continue  to  grow  and  come  to  fill  up  the 
whole  host  cell  except  for  the  nucleus. 

Cutting  across  these  morphological 
groups  are  the  two  groups  based  on  the 
type  of  cell  invaded  by  the  exoerythrocytic 
forms  mentioned  on  page  261. 


PLASMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


267 


PLASMODIUM  GALLINACEUM 
BRUMPT,   1945 

Disease:     Chicken  malaria. 

Hosts:     Chicken. 

Crawford  (1945)  thought  that  jungle 
fowls  are  the  natural  hosts  of  P.  gallina- 
cemn.     These  are  Gallus  lafayetti  in 
Ceylon,   G.  sonnerati  in  Sumatra  and  G. 
bankiva  in  India.     Brumpt  (1936),   how- 
ever, thought  that  the  natural,  wild  host 
is  still  unknown.    Jungle  fowls  are  rela- 
tively resistant,  but  outbreaks  of  disease 
occur  in  domestic  chickens  introduced 
into  areas  where  the  parasite  is  endemic 
in  wild  birds. 

Pheasants,  partridges,  peacocks  and 
geese  have  been  infected  experimentally, 
but  the  duck,  guinea  fowl,  pigeon,  turtle 
dove,  quail,  buzzard,  canary,  English 
sparrow,  Java  sparrow  {Padda  oryzivora) 
and  finch  are  resistant  (Brumpt,   1936). 

Location:     Erythrocytes.     The  exo- 
erythrocytic  stages  are  in  endothelial 
cells. 

Geographic  Distribution:     Southern 
Asia,  Indonesia.     P.  gallinaceuni  was  first 
seen  by  Crawford  in  Ceylon  and  named  by 
Brumpt  (1935)  from  material  sent  to  him 
from  Indochina.     It  has  also  been  found  in 
India  (Rao,  Das  and  Ramnani,   1951;  Das, 
Rao  and  Ramnani,   1952)  and  Java,  Suma- 
tra and  Celebes  (Kraneveld  and  Mansjoer, 
1953).    It  was  reported  from  Egypt  by 
Haiba  (1948),  but  this  record  requires 
confirmation. 

Morphology:     The  gametocytes  and 
schizonts  are  round  or  irregular.     The 
host  cell  nucleus  is  displaced  but  seldom 
expelled.     The  pigment  granules  in  the 
gemetocytes  are  rather  large  and  not  very 
numerous.     The  schizonts  produce  8  to  30 
merozoites. 

Life  Cycle:     The  life  cycle  is  similar 
to  that  of  other  Plasmodium  species.    The 
exo-erythrocytic  stages  in  the  endothelial 
or  reticulo -endothelial  cells  of  the  spleen, 
brain,  liver,  etc.  have  been  described  by 


James  and  Tate  (1937,   1938),  James  (1939) 
and  Huff  and  Coulston  (1944).    The  natural 
vectors  are  unknown,  but  various  mosqui- 
toes,  including  Aedes  aegypti,  A.  albo- 
pictus,  A.  geniculatus  and  Culex  quinque- 
fasciatiis,  are  potential  vectors  (Brumpt, 
1936,   1936a;  Vargas  and  Beltran,   1941). 
Huff  (1954)  listed  29  susceptible  and  1 
questionable  species  of  which  19  are 
Aedes,   5  Armigeres,  2  (possibly  3)  Culex, 
1  Anopheles ,  1  Culiseta  and  1  Mansonia. 

Pathogenesis:     P.  gallinaceuni  causes 
a  serious  disease  with  a  high  mortality 
rate  in  domestic  chickens.     The  body  tem- 
perature fluctuates,  and  anemia  and  splen- 
omegaly are  present.     The  birds  may  be- 
come paralyzed  and  die  due  to  blocking  of 
the  brain  capillaries  by  the  exoerythrocytic 
stages. 

Remarks:     Beltran  (1941,   1943a)  and 
Crawford  (1945)  reviewed  the  history  of 
research  on  this  species.     Because  it  lends 
itself  well  to  experimental  study  and  be- 
cause the  chicken  is  such  an  excellent  lab- 
oratory animal,   hundreds  of  papers  have 
been  written  on  it--according  to  Brumpt 
(1949),   more  than  600  between  1935  and 
1948. 


PLASMODIUM  JUXTANUCLEARE 
VERSIANI  AND  GOMES,   1941 

Disease:     Chicken  malaria. 

Hosts:     Chicken.     Versiani  and  Gomes 
(1941)  infected  1  of  3  turkeys  experiment- 
ally, but  were  unable  to  infect  the  duck, 
guinea  fowl,   pigeon,  canary,  domestic 
sparrow,  tico  tico,  or  3  other  species  of 
wild  birds. 

Location:     Erythrocytes.     The  exo- 
erythrocytic stages  are  in  endothelial  cells. 

Geographic  Distribution:     South  Amer- 
ica (Brazil),   Mexico. 

Morphology:     This  species  has  been 
described  from  Minas  Gerais,   Brazil  by 
Versiani  and  Gomes  (1941,   1943)  and  from 
Chiapas,  Mexico  by  Beltran  (1941a,   1943). 
The  gametocytes  and  schizonts  are  round 


268 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


or  irregular,   relatively  small,  and  usually 
in  contact  with  the  red  cell  nucleus.     The 
schizonts  produce  3  to  7  (usually  4)  mero- 
zoites.    The  host  cell  is  often  distorted. 

Life  Cycle:     The  life  cycle  has  not 
been  completely  studied.    According  to 
Beltran  (1943),  schizogony  takes  about  24 
hours  and  its  synchronicity  is  low.     The 
prepatent  period  may  vary  from  2  to  38 
days.     Paraense  (1947)  saw  exoerythro- 
cytic  stages  in  the  endothelial  cells.   Culex 
qiiinqiiefasciatus  was  found  to  be  a  suit- 
able experimental  vector  by  Paraense 
(1944),  but  Aedes  aegypti  and  A.  lepidus 
are  not. 


are  elongate,  at  the  end  or  side  of  the  host 
cell,  and  often  displace  the  host  cell  nucleus 
when  oriented  obliquely  to  it.     This  tendency 
to  take  an  oblique  position  differentiates  P. 
diirae  from  other  avian  species  of  Plas- 
modium.   The  pigment  granules  are  usually 
large,  round  and  black.     The  host  cell  is 
not  enlarged.     The  trophozoites  are  more 
or  less  amoeboid.     Presegmenters  are 
often  at  the  end  of  the  host  cell.    The  mature 
schizonts  rarely  displace  the  host  cell  nu- 
cleus.    The  pigment  granules  are  round, 
black,  up  to  8  in  number,  and  tend  to  be- 
come clumped  together  in  the  mature  schi- 
zonts.   Six  to  14  (usually  8)  merozoites 
are  formed.    The  host  cell  is  not  distorted. 


Pathogenesis:    This  species  is  highly 
pathogenic.     The  Brazilian  strain  killed 
75%  of  the  infected  young  birds  and  68% 
of  the  adults  in  15  days  to  9  months,  and 
the  Mexican  strain  killed  12  of  13  birds  in 
1  to  8  months.    Affected  birds  do  not  show 
any  marked  signs.    Shortly  before  death 
they  appear  listless  and  weak,  with  pale 
combs.     Their  temperature  is  not  eleva- 
ted.    There  are  deposits  of  pigment  in  the 
liver  and  spleen.     Versiani  and  Gomes 
(1943)  observed  a  large  amount  of  peri- 
cardial fluid,  but  Beltran  (1943)  did  not. 


PLASMODIUM  DURAE 
HERMAN,   1941 

Disease:     Turkey  malaria. 

Hosts:     Turkey.     Purchase  (1942) 
produced  a  transient  infection  in  baby 
chicks.    Simpson  (1944)  infected  ducks  of 
various  ages.     This  is  probably  a  natural 
parasite  of  some  as  yet  unknown  wild 
African  bird. 

Location:     Erythrocytes.     The  exo- 
erythrocytic  stages  are  in  endothelial  cells. 

Geographic  Distribution:     Africa 
(Kenya). 

Prevalence:    Herman  (1941)  found  P. 
durae  in  1  of  75  domestic  turkeys  in  Kenya. 

Morphology:     This  species  was  des- 
cribed by  Herman  (1941).     The  gametocytes 


Life  Cycle:      Purchase  (1942)  and 
Simpson  (1944)  found  exoerythrocytic 
stages  of  P.  durae  in  the  endothelial  cells 
of  the  spleen,   liver,  lungs  and  brain  of 
turkeys.     The  prepatent  period  is  3  days 
to  2.  5  weeks  after  intravenous  injection  and 
12  days  to  40  days  after  intramuscular  in- 
jection (Herman,   1941).     Schizogony  in  the 
erjTthrocytes  apparently  takes  24  hours. 
The  vectors  are  unknown  (Huff,   1954). 

Pathogenesis:     P.  durae  causes  an 
acute,  often  fatal  disease  in  turkeys  less 
than  a  year  old.     Twelve  out  of  14  young 
poults  infected  by  Purchase  (1942)  died. 
They  showed  some  malaise  and  ruffled 
feathers,  but  usually  died  without  any  acute 
signs.     Two  naturally  affected  adult  birds 
showed  signs  of  cerebral  involvement, 
emaciation,  edema  of  the  legs  and  high 
blood  pressure. 

At  necropsy  of  acute  cases  (Purchase, 
1942)  the  liver,   spleen  and  kidneys  are  dark 
and  congested,  the  lungs  slightly  edematous, 
and  the  pericardial  cavity  contains  an  excess 
of  clear  fluid.     The  lumen  of  the  duodenal 
loop  is  light  chocolate  in  color  and  its  villi 
are  heavily  laden  with  pigment.     There  is 
injection  of  the  superficial  vessels  of  the 
brain  and  meninges. 

In  chronic,  naturally  infected  birds, 
the  spleen  is  reduced  in  size,  hard  and 
fibrous,  the  liver  is  firm,  with  chronic 
congestion  and  much  fibrosis.     The  villi  of 
the  duodenal  loop  are  packed  with  large 
pigment  granules. 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


269 


PLASMODIUM  RELICTUM 
(GRASSI  AND   FELETTI,   1891) 

Synonyms:     Plasmodium  praecox 
Grassi  and  Feletti,   1890.     (Bray,   1957 
considered  the  correct  specific  name  to 
be  praecox,  but  he  continued  to  use  re- 
lictum. ) 

Disease:     Pigeon  malaria. 

Hosts:     Pigeon,  mourning  dove,   pin- 
tail, cinnamon  teal,  falcated  duck,  black 
swan,  and  various  passerine  and  other 
wild  birds.     This  species  was  first  des- 
cribed from  the  English  sparrow.     Exper- 
imental infections  have  been  studied  in  the 
canary,  duck,  chicken  and  other  birds. 

Location:     Erythrocytes.     The  exo- 
erythrocytic  stages  are  in  endothelial  cells. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  common 
in  wild  passerine  birds.     It  occurs  occa- 
sionally in  domestic  pigeons,  having  been 
found  in  them  by  Sergent  and  Sergent 
(1904)  in  Algeria,   Coatney  (1938)  in  Ne- 
braska, Herman  et  al.   (1954),  Mathey 
(1955)  and  Graue  (cited  by  Levi,   1957)  in 
California,  Becker,  Hollander  and  Pat- 
tillo  (1956)  in  Iowa,   Pelaez  et  al.   (1951) 
in  Mexico,  Cassamagnaghi  (1950)  in 
Uruguay,   Haiba  (1946,   1948)  in  Egypt,  and 
Rousselot  (1943)  in  the  French  Sudan. 

Morphology:     The  gametocytes  and 
schizonts  are  round  or  irregular.     The 
host  cell  nucleus  is  displaced  and  often 
expelled  by  the  larger  forms.    The  pig- 
ment granules  of  the  gametocytes  are  rel- 
atively fine  and  dot-like.     The  schizonts 
produce  8  to  32  merozoites,  the  number 
depending  on  the  particular  strain. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  extensively 
(Bray,   1957).     The  exoerythrocytic  stages 
occur  in  the  endothelial  cells.    The  asex- 
ual cycle  has  been  reported  to  take  from 
12  to  36  hours  in  different  strains;  some 
have  a  very  high  and  others  a  low  degree 
of  synchronicity  (Hewitt,   1940).     Many 
species  of  mosquitoes  can  act  as  vectors. 


Huff  (1954)  listed  12  of  Culex,  4  of  Ano- 
pheles,  3  of  Aedes  and  2  of  Culiseta,  and 
remarked  that  93%  of  the  species  which  had 
been  tested  had  been  found  susceptible. 

Pathogenesis:     P.  relic  turn  is  highly 
pathogenic  for  the  pigeon  but  less  so  for 
the  mourning  dove  and  canary.     Affected 
squabs  become  weak  and  anemic,  with  en- 
larged and  heavily  pigmented  spleens  and 
livers.     Pigment  may  also  be  deposited  in 
the  fat.     Hill  (1942)  showed  that  anemia  is 
the  principal  cause  of  death. 


PLASMODIUM  CIRCUMFLEXUM 
KIKUTH,   1931 

Hosts:     This  species  is  quite  common 
in  a  wide  variety  of  hosts.     The  type  host 
is  a  German  thrush,    Tiirdus  pilaris.    It 
was  found  in  the  ruffed  grouse  in  Canada  by 
Fallis  (1945,   1946),  and  a  similar  form  was 
found  in  the  Canada  goose  in  Illinois  by 
Levine  and  Hanson  (1953). 

Location:     Erythrocytes.     The  exo- 
erythrocytic stages  are  in  endothelial  cells. 

Morphology:     The  gametocytes  and 
trophozoites  are  elongate;  they  tend  to  en- 
circle the  host  cell  nucleus  but  are  gener- 
ally not  in  contact  with  it  and  do  not  displace 
it.     The  schizonts  produce  13  to  30  mero- 
zoites (average  19). 

Life  Cycle:     The  life  cycle  is  similar 
to  that  of  other  avian  species  of  Plasmodium. 
Exoerythrocytic  stages  occur  in  the  endo- 
thelial cells.     The  known  vector  mosquitoes 
are  Culex  tarsalis,  Culiseta  annulata  and 
C.  melaneura.    Two  other  species  of  Culex 
and  5  of  Aedes  have  been  found  insuscepti- 
ble (Huff,   1954). 


PLASMODIUM  CATHEMERIUM 
HARTMAN,   1927 

Disease:     Canary  malaria. 

Hosts:     This  species  was  first  found 
in  the  English  sparrow.    It  is  common  in 
passerine  birds  and  has  also  been  found  in 
canaries. 


270 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


Location:     Erythrocytes.    The  exo- 
erythrocytic  stages  are  in  endothelial  cells. 

Morphology:  The  gametoc3^es  and 
schizonts  are  more  or  less  round,  dis- 
placing and  often  expelling  the  host  cell 
nucleus.  The  pigment  granules  in  the 
gametocytes  are  coarse,  often  elongate 
and  rod-like.  The  schizonts  produce  6  to 
24  merozoites. 


Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  extensively  (Bray, 
1957).     It  is  similar  to  that  of  other  avian 
species  of  Plasniudiuni.    Exoerythrocytic 
stages  occur  in  the  endothelial  cells.    The 
asexual  cycle  takes  24  hours,  and  syn- 
chronicity  is  high.     Huff  (1954)  listed  8 
species  of  Culex,  3  each  of  Aedes  and 


Anopheles  and  1  of  Psorophora  which  can 
act  as  vectors.    However,  he  remarked 
that  only  46%  of  the  mosquito  species 
which  had  been  tested  were  susceptible. 

Pathogenesis:     P.  cathemerimn 
causes  a  highly  fatal  disease  in  canaries. 
Herman  and  Vail  (1942)  reported  it  in  a 
canary  in  California,  and  Mathey  (1955a) 
described  an  outbreak  in  a  canary  breeding 
establishment  in  that  state  in  which  pos- 
sibly 165  out  of  700  birds  died. 

Affected  canaries  have  subcutaneous 
hemorrhages,  anemia,  splenomegaly  and 
hepatomegaly.    Mathey  (1955a)  described 
swelling  in  the  region  of  the  eyes.     Hewitt 
(1939)  found  splenic  infarcts  in  47%  of  his 
experimentally  infected  canaries. 


Fig.  32.      Avian  Plasmodium  and  Haemoproteus  in  erythrocytes.     A.   Plasmodium  gal- 

linaceum  young  trophozoite  (ring  stage).     B.   P.  galliiiacciim  older  trophozoite. 
C.    P.  galliiKiceuiii  mature  trophozoite  (segmenter).    D.   P.  gatlimicfum  mac- 
rogamete.     E.   P.  gallinaceum  microgametocyte.     F.    P.  reliclum  mature 
trophozoite  (segmenter).    G.   P.   relictu»i  macrogamete.     H.    Haemoproteus 
colitmbae  macrogamete.     X  2800.     (Original) 


BIRD   MALARIA 

Diagnosis:     Bird  malaria  can  be  diag- 
nosed by  finding  and  identifying  the  proto- 
zoa in  stained  blood  smears.    If  schizonts 
or  merozoites  are  present,  it  is  easy  to 
differentiate  Plasmodium  from  Haemo- 
proteus, since  these  stages  are  not  found 
in  the  peripheral  blood  in  the  latter.     How- 
ever, if  elongate  gametocytes  alone  are 
found,  differentiation  is  usually  not  possible. 


Treatment:     The  bird  malarias  res- 
pond to  treatment  with  quinacrine,  chloro- 
quine  and  other  antimalarial  drugs.     Indeed, 
these  were  discovered  by  screening  against 
bird  malarias.    Chloroquine  at  the  rate  of 
5  mg  per  kg,  chlorguanide  at  7.  5  mg  per 
kg  and  pyrimethamine  at  0.  3  mg  per  kg 
protect  chickens  against  P.  gallinaceum 
infections.    However,  as  a  practical  matter. 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


271 


treatment  is  usually  hardly  worthwhile, 
and  preventive  measures  are  recommended 
instead. 

Prevention  and  Control:     Since  bird 
malaria  is  carried  by  mosquitoes,   pre- 
vention depends  upon  mosquito  control. 
Residual  spraying  of  poultry  houses  with 
insecticides  such  as  DDT  or  lindane  should 
be  effective.     Birds  can  also  be  raised  in 
screened  quarters  where  mosquitoes  can- 
not get  to  them. 


Genus  HAEMOPROTEUS  Kruse,  1 890 

The  gametocytes  occur  in  the  ery- 
throcytes and  are  usually  halter- shaped. 
Schizogony  takes  place  in  the  endothelial 
cells  of  the  blood  vessels,  especially  in 
the  lungs,  and  not  in  the  erythrocytes. 
The  known  vectors  are  louse -flies  (Hippo- 
boscidae)  and  midges  {CuUcoides).    Mem- 
bers of  this  genus  are  parasites  of  birds 
and  reptiles.     A  synonym  of  this  generic 
name  is  Halteridium  Labbe",   1894. 

Members  of  this  genus  are  extremely 
common  in  wild  birds  and  also  occur  in 
domestic  pigeons,  ducks  and  turkeys. 
They  are  not  an  important  cause  of  disease. 
Coatney  (1936)  gave  a  checklist  and  host 
index  of  the  species  of  Haemoproteus ,  and 
Herman  (1944)  listed  the  species  reported 
from  North  American  birds. 

Life  Cycle:     The  life  cycle  of  Haemo- 
proteus is  similar  to  that  of  Plasmodium 
except  that  schizogony  does  not  take  place 
in  the  erythrocytes  but  in  the  endothelial 
cells  of  the  blood  vessels,  and  the  vectors 
are  not  mosquitoes  but  hippoboscid  flies 
or  midges. 


HAEMOPROTEUS  COLUMBAE 
KRUSE,   1890 

Synonyms:     Haemoproteus  maccal- 
lumi,  Haemoproteus  melopeliae,  Haemo- 
proteus turtur,  Haemoproteus  vilhenai  (?). 

Hosts:     Domestic  and  wild  pigeons, 
mourning  dove,  turtle  dove  and  a  large 
number  of  other  wild  columbiform  birds. 


Levine  and  Kantor  (1959)  tabulated  reports 
of  Haemoproteus,  all  of  which  were  prob- 
ably H.  columbae,    from  45  species  belong- 
ing to  19  genera  of  columbiform  birds. 

H.  maccallumi  was  first  described 
from  the  mourning  dove  {Zenaidura 
macroura).    It  is  morphologically  indis- 
tinguishable from  H.  columbae.      Huff 
(1932)  transmitted  it  from  the  mourning 
dove  to  the  pigeon,  but  Coatney  (1933)  was 
unable  to  transmit  it  from  the  pigeon  to 
the  mourning  dove;  both  used  the  hippo- 
boscid fly,   Pseudolynchia  canariensis, 
as  the  vector.     There  may  be  strain  dif- 
ferences between  the  different  hosts,  but 
until  greater  differences  than  these  are 
brought  out,  it  is  probably  better  to  use 
the  name  H.  columbae  for  the  species 
from  columbiform  birds. 

Location:  The  gametocytes  are  in 
the  erythrocytes.  Schizogony  occurs  in 
the  endothelial  cells  of  the  blood  vessels. 

Geographic  Distribution:     Worldwide. 

Prevalence:     Common.     Thirty-eight 
reports  of  H.  columbae  from  the  domestic 
pigeon  were  tabulated  by  Levine  and  Kan- 
tor (1959).     Among  those  in  which  rela- 
tively large  numbers  of  birds  were  ex- 
amined,  Coatney  (1935)  found  it  in  all  of 
about  28  pigeons  in  midwestern  United 
States,  Kartman  (1949)  found  it  in  82%  of 
101  pigeons  in  the  Honolulu  zoo,  Giovannoni 
(1946)  found  it  in  58%  of  159  pigeons  in 
southern  Curitiba,   Brazil,  Acton  and 
Knowles  (1914)  found  it  in  all  of  75  pigeons 
from  the  plains  of  India,   and  Singh,  Nair 
and  David  (1951)  found  it  in  22%  of  214  pig- 
eons in  Delhi,  India. 

Herman  (1938)  found  it  in  8%  of  86 
mourning  doves  {Zenaidura  macroura  car- 
olinensis)  on  Cape  Cod,  Massachusetts, 
Huff  (1939)  found  it  in  47%  of  188  mourning 
doves,  mostly  from  Illinois,   Couch  (1952) 
found  it  in  56%  of  213  mourning  doves  in 
Texas,  and  Hanson  et  al.  (1957)  found  it  in 
30%  of  392  immature  and  43%  of  72  adult 
mourning  doves  in  Illinois;  its  incidence 
in  this  last  survey  increased  steadily  from 
7  to  8%  in  very  young  doves  to  70%  in  the 
oldest  immatures,  and  varied  markedly  in 


272 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


different  parts  of  the  state  and  in  different 
years.    Wood  and  Herman  (1943)  found  it 
in  93't  of  27  western  mourning  doves  in 
Arizona  and  California. 

Morphology:     The  only  stages  found 
in  the  peripheral  blood  are  macrogametes 
and  microgametocytes.    When  mature, 
these  are  elongate  and  sausage -shaped. 
They  partially  encircle  the  host  cell  nu- 
cleus; they  may  displace  it  to  some  extent, 
but  they  do  not  push  it  to  the  edge  of  the 
host  cell.    They  contain  a  variable  number 
of  dark  brown  pigment  granules.     The  host 
cell  is  not  enlarged. 

When  stained  with  a  Romanowsky 
stain,  the  cytoplasm  of  the  microgameto- 
cytes is  pale  blue  or  almost  colorless  and 
their  nuclei  are  pale  pink  and  diffuse, 
while  the  cytoplasm  of  the  macrogametes 
is  darker  blue  and  their  nuclei  are  com- 
pact and  dark  pink  or  red. 

Life  Cycle:     The  life  cycle  of  H.  co- 
lumbae  has  been  studied  by  Aragao  (1908), 
Adie  (1915,   1924)  and  Huff  (1942)  among 
others.     Birds  become  infected  when  bit- 
ten by  the  dipteran  vector.     The  sporo- 
zoites  enter  the  blood  stream  and  invade 
the  endothelial  cells  of  the  blood  vessels 
of  the  lungs,  liver  and  spleen.     Here  they 
round  up  to  form  schizonts.     Each  schi- 
zont  undergoes  multiple  fission  to  form 
15  or  more  small,  unpigmented  bodies, 
the  cytomeres,  each  with  a  single  nucleus. 
Each  cytomere  grows  still  further,  and 
its  nucleus  undergoes  multiple  fission. 
Finally,  the  host  cell  becomes  considerably 
hypertrophied  and  is  filled  with  a  number 
of  multinucleate  cytomeres. 

The  endothelial  cells  break  down,   re- 
leasing the  cytomeres.     These  vary  in 
size,  but  may  reach  60 ^  in  diameter. 
They  accumulate  in  the  capillaries,  which 
they  sometimes  block  completely.     They 
are  irregularly  shaped  and  tortuous,  and 
may  send  out  branches  along  the  capillar- 
ies, becoming  bifurcate,  trifurcate  or 
even  multiradiate.     Each  cytomere  pro- 
duces an  enormous  number  of  merozoites, 
which  break  out  and  pass  into  the  blood 
stream. 


According  to  Wenyon  (1926),  the  schi- 
zonts do  not  necessarily  form  cytomeres 
but  may  produce  merozoites  directly. 
Presumably,  too,  schizogony  is  repeated 
a  number  of  times. 

Following  schizogony,  the  merozoites 
enter  red  blood  cells  and  become  macro- 
gametes and  microgametocytes.    These 
first  appear  28  to  30  days  after  infection. 
At  first  they  resemble  ring  stages  of  Plas- 
modiuDi,  but  grow  to  the  mature,  elongate 
form  in  a  few  days.     Multiple  infections  of 
erythrocytes  with  immature  parasites  are 
not  uncommon,  sometimes  as  many  as  12 
being  found  in  a  single  host  cell,  but  in- 
fections with  more  than  1  mature  gamete 
or  gametocyte  are  rare. 

The  only  proven  vector  is  the  hippo- 
boscid  fly,   Pseudolynchia  canariensis 
(syns. ,  Lynchia  maura,  L.  lividicolor, 
L.  capensis).    In  addition,  Arag'ao  (1916) 
stated  that  Alicrolyiichia  pus  ilia  is  a  vector 
in  South  America,  but  gave  no  experimental 
evidence.     Baker  (1957)  found  that  H.  co- 
limibae  from  the  English  wood  pigeon 
(Coluniba  palumbus)  would  undergo  sporo- 
gony  in  Ornithomyia  aviciilaria,  but  6 
attempts  to  infect  domestic  pigeons  by  bite 
or  injection  of  infected  louse-flies  failed. 

It  is  highly  unlikely  that  hippoboscids 
are  the  only  vectors  of  this  species,   how- 
ever.    As  Hanson  et  al.  (1957)  pointed  out, 
hippoboscids  are  extremely  rare  on  mourn- 
ing doves,  yet  H.  colinnbae  is  common  in 
them.     The  discovery  by  Fallis  and  Wood 
(1957)  that  biting  midges  (Ciilicoides)  are 
the  vectors  of  H.  nettionis  of  ducks  sug- 
gests that  they  may  also  transmit  H. 
columbae . 

In  the  stomach  of  the  hippoboscid  vec- 
tor, the  microgametocytes  produce  4  or 
more  snake-like  microgametes  by  exfla- 
gellation.     They  fertilize  the  macroga- 
metes, and  the  resultant  zygotes  are  ookin- 
etes which  crawl  to  the  midgut  wall  and 
form  oocysts  on  its  outer  surface.    These 
grow,   reaching  a  diameter  of  about  36  j^. 
They  become  mature  in  10  to  12  days,  pro- 
ducing very  large  numbers  of  slender,  fal- 
ciform sporozoites  up  to  10  ^  long  and 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


273 


similar  to  those  of  Plasmodium.    These 
break  out  of  the  oocysts  into  the  body  cav- 
ity and  pass  to  the  salivary  glands,  where 
they  accumulate  and  are  injected  into  a 
new  host  when  the  fly  bites  it. 

Pathogenesis:     U.  columbae  is  only 
slightly  pathogenic.    Infected  birds  usually 
show  no  signs  of  disease.     In  relatively 
heavy  infections  the  birds  may  appear 
restless  and  go  off  feed,  and  anemia  may 
result  from  destruction  of  erythrocytes, 
but  this  is  unusual.     The  liver  and  spleen 
of  affected  birds  may  be  enlarged  and  dark 
with  pigment. 


HAEMOPROTEUS  SACHAROVI 
NOVY  AND  MacNEAL,   1904 

Hosts:     Domestic  pigeon,  mourning 
dove  (Zenaidiira  macroura),  turtle  dove 
{Streptopelia  turtiir).     This  species  is 
primarily  a  parasite  of  wild  doves  which 
may  also  infect  pigeons. 

Location:  Gametocytes  in  erythro- 
cytes. Schizogony  in  endothelial  cells  of 
blood  vessels. 


Geographic  Distribution: 
America,  Europe  (Italy). 


North 


Prevalence:      H.  sacliarovi  is  common 
in  mourning  doves.     Levine  and  Kantor 
(1959)  tabulated  12  reports  from  this  host 
from  coast  to  coast  in  the  United  States. 
Among  those  studies  in  which  relatively 
large  numbers  of  birds  were  examined, 
Herman  (1938)  found  it  in  7%  of  86  mourn- 
ing doves  on  Cape  Cod,  Massachusetts, 
Huff  (1939)  found  it  in  56%  of  188  mourning 
doves,  mostly  from  Illinois,   Coatney  and 
West  (1940)  found  it  in  67%  of  18  mourning 
doves  in  Nebraska,   Couch  (1952)  found  it 
in  27%  of  213  mourning  doves  in  Texas, 
Wood  and  Herman  (1943)  found  it  in  41%  of 
27  western  mourning  doves  in  Arizona  and 
California,  and  Hanson  et  al.  (1957)  found 
it  in  58%  of  392  immature  and  43%  of  72 
adult  mourning  doves  in  Illinois.    In  this 
last  study,   its  incidence  was  31%  in  very 
young  doves  and  52%  to  69%  in  older  birds. 
Its  incidence  varied  markedly  in  different 
parts  of  the  state  and  in  different  years. 


H.  sacliarovi  was  found  in  22%  of  50 
domestic  pigeons  in  Nebraska  by  Coatney 
and  West  (1940)  and  in  15%  of  20  domestic 
pigeons  in  Iowa  by  Becker,   Hollander  and 
Pattillo  (1956). 

Morphology:     The  macrogametes  and 
microgametocytes  are  found  in  the  erythro- 
cytes.    They  differ  from  those  of  most 
species  of  Haemoproteus  in  that  when  ma- 
ture they  completely  fill  the  host  cell,  en- 
larging and  distorting  it,  and  often  pushing 
the  host  cell  nucleus  to  the  edge  of  the  cell. 
In  addition,  they  contain  very  little  pig- 
ment.   When  stained  with  a  Romanowsky 
stain,  the  microgametocytes  have  pale  blue 
to  almost  colorless  cytoplasm  and  a  light 
pink,  diffuse  nucleus,  while  the  macroga- 
metes have  dark  blue  cytoplasm  and  a 
dark  pink  to  red,   compact  nucleus. 

The  young  gametocytes  are  ring-forms, 
and  all  stages  between  these  and  mature 
gametocytes  can  be  found  in  the  blood. 

Life  Cycle:     Huff  (1932)  transmitted 
U.  sacliarovi  from  the  mourning  dove  to 
the  pigeon  by  means  of  the  hippoboscid  fly, 
Pseiidolyncliia  canariensis.     However,  the 
natural  vectors  of  this  protozoon  are  still 
unknown.     In  view  of  its  high  incidence  in 
mourning  doves  and  the  extreme  rarity  of 
hippoboscid  flies  on  these  birds,  the  nat- 
ural vector  must  be  some  other  ectopara- 
site,  possibly  Culicoides. 

Pathogenesis:     H.  sacliarovi  is  only 
slightly  if  at  all  pathogenic  in  the  mourning 
dove.     Becker,   Hollander  and  Pattillo  (1956) 
considered  that  it  caused  the  enlarged,  pur- 
plish livers  which  they  encountered  in 
dressing  domestic  pigeon  squabs  from  an 
infected  flock;  there  was  apparently  no 
other  evidence  of  disease. 


HAEMOPROTEUS  NETTIONIS 
(JOHNSTON  AND  CLELAND,   1909) 
COATNEY,   1936 

Synonyms:     Haemoproteus  anatis, 
Haemoproteus  liermani. 

Hosts:     Domestic  duck,  domestic 
white  Chinese  goose,  and  over  23  species 


274 


PIASMODIUM.    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


of  wild  ducks,  geese  and  swans,   including 
the  Canada  goose,  whistling  swan,  wood 
duck,  pintail,  green-winged  teal,  Aus- 
tralian teal,  blue-winged  teal,   mallard, 
black  duck,  white-winged  duck,  cotton  teal, 
Australian  sheldrake,  wattle  duck,   shov- 
eller,  Baer's  pochard,   ring-necked  duck, 
white-eyed  duck,  rufous -crested  duck, 
baldpate,  common  goldeneye,  surf  scoter, 
old  squaw  and  common  merganser  (Levine 
and  Hanson,   1953;  Herman,   1954;  Fallis 
and  Wood,   1957). 


infected  birds  is  14  to  21  days.    Schizogony 
has  not  been  described,  and  the  details  of 
sporogony  in  the  midge  are  still  to  be 
worked  out.     Fallis  and  Wood  found  ooki- 
netes in  the  midge  stomach  36  hours  after 
ingestion;  they  found  structures  which  they 
regarded  as  oocysts  on  the  stomach  wall, 
and  other  structures  which  they  regarded 
as  sporozoites  in  the  salivary  glands. 

Pathogenesis:     H.  nettionis  is  only 
slightly  if  at  all  pathogenic. 


Location:  The  gametocytes  are  in 
the  erythrocytes.  Schizogony  occurs  in 
the  endothelial  cells  of  the  blood  vessels. 


HAEMOPROTEUS  MELEAGRIDIS 
N.  SP. 


Geographic  Distribution:     Worldwide. 


Hosts:     Domestic  and  wild  turkey. 


Prevalence:     Common.     This  species 
is  a  parasite  of  wild  waterfowl  which  may 
infect  domestic  ducks  in  heavily  endemic 
regions. 

Morphology:     Only  the  sexual  stages 
are  found  in  the  red  blood  cells.     Except 
early  in  an  infection,  young  stages  are 
absent  or  rare.    The  mature  macroga- 
metes  and  microgametocytes  are  elongate 
and  sausage-shaped,   partially  (or  some- 
times completely)  encircling  the  host  cell 
nucleus,  often  displacing  it.     There  is  fre- 
quently a  narrow  band  of  cytoplasm  be- 
tween the  parasite  and  the  host  cell  nucleus, 
Free  macrogametes  and  microgametocytes 
may  occasionally  be  found;  these  are  usu- 
ally round.    The  macrogametes  and  micro- 
gametocytes contain  a  few  to  30  or  more 
(usually  12  to  24)  pigment  granules  which 
are  usually  coarse  and  round  and  tend  to 
be  grouped  at  the  ends  of  the  cell.    The 
host  cell  is  not  enlarged. 

When  stained  with  a  Romanowsky 
stain,  the  cytoplasm  of  the  microgameto- 
cytes is  pale  blue  or  almost  colorless  and 
their  nuclei  are  pale  pink  and  diffuse, 
while  the  cytoplasm  of  the  macrogametes 
is  darker  blue  and  their  nuclei  are  com- 
pact and  dark  pink  or  red. 

Life  Cycle:     The  vector  of  H.  nettionis 
was  first  discovered  by  Fallis  and  Wood 
(1957).     It  is  the  biting  midge,  Cidicoides. 
The  prepatent  period  in  experimentally 


Location:     The  gametocytes  are  in 
the  erythrocytes. 

Geographic  Distribution:     North 
America. 

Prevalence:     Uncommon.     Haemo- 
proteus  sp.  was  reported  from  1  out  of  4 
domestic  turkeys  in  the  District  of  Colum- 
bia and  vicinity  by  Wetmore  (1941),  from 
a  turkey  poult  from  Texas  by  Morehouse 
(1945),  from  5  of  97  eastern  wild  turkeys 
(of  which  4  had  been  reared  in  captivity) 
in  Pennsylvania  by  Kozicky  (1948),  from  a 
flock  of  turkeys  in  North  Dakota  by  Goldsby 
(1951),  from  3  out  of  10  turkeys  in  South 
Carolina  by  Atchley  (1951),  from  1  out  of 
2  wild  turkeys  in  Georgia  by  Love,  Wilkin 
and  Goodwin  (1953)  and  from  42%  of  52 
birds  in  a  flock  of  domestic  turkeys  in 
South  Carolina  by  Bierer,   Vickers  and 
Thomas  (1959). 

Morphology:     Only  Morehouse  (1945) 
described  the  macrogametes  and  micro- 
gametocytes.    They  are  elongate,   sausage- 
shaped,   curve  around  the  host  cell  nucleus 
and  occupy  about  1   2  to  3  4  of  the  host  cell. 
Their  surface  is  usually  in  close  contact 
both  with  the  host  cell  nucleus  and  host  cell 
wall.     The  macrogametes  measure  14  to 
19  by  2  to  4  ^  with  a  mean  of  17  by  3  fi . 
They  contain  18  to  48  (mean,   27)  round  or 
irregular  pigment  granules.     Their  nuclei 
measure  2  to  6  by  2  to  3 fx  with  a  mean  of 
4  by  2(i  and  are  ovoid  or  irregular  in  shape. 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


275 


The  microgametocytes  stain  less  intensely 
than  the  macrogametes.     They  measure 
13  to  18  by  3  to  4  pi  with  a  mean  of  16  by 
3|U.     They  contain  11  to  24  (mean,   18)  pig- 
ment granules.     Their  nuclei  measure  5 
to  10  by  2  to  4  jj.  with  a  mean  of  8  by  3  ji  . 
The  host  cells  are  not  enlarged.     More- 
house also  observed  occasional  extracellu- 
lar macrogametes. 

Life  Cycle:     Unknown. 

Pathogenesis:     Unknown. 

Remarks:    Altho  Haemoproteiis  is 
relatively  rare  in  turkeys,  it  has  been 
seen  enough  times  and  has  been  described 
well  enough  to  warrant  having  a  name  of 
its  own.    I  am  therefore  naming  it  H. 
meleagridis  n.  sp. 


species,  also  in  the  erythrocytes.    Schi- 
zogony takes  place  in  the  parenchyma  of 
the  liver,   heart,  kidney  or  other  organs, 
the  schizonts  forming  large  bodies  divided 
into  cytomeres.     There  is  no  schizogony 
in  the  erythrocytes  or  leucocytes.     The 
vectors  are  blackflies  {Simulium).     Mem- 
bers of  this  genus  are  parasites  of  birds. 

Leucocytozoo)i  is  common  in  many 
wild  birds  and  also  causes  disease  in 
ducks,   geese,  turkeys  and  chickens. 
Coatney  (1937)  gave  a  catalog  and  host- 
index  of  the  genus,  and  Herman  (1944) 
listed  the  species  occurring  in  North 
American  birds. 


LEUCOCYTOZOON  SIMONDI 
MATfflS  AND   LEGER,   1910 


HAEMOPROTEUS  INFECTIONS  IN 
BIRDS 

Diagnosis:     Haemoproteus  infections 
can  be  diagnosed  by  finding  and  identifying 
the  protozoa  in  stained  blood  smears. 
However,  not  all  infections  in  which  game- 
tocytes  alone  are  found  are  necessarily 
Haemoproteus  infections.    Some  of  them 
may  be  Plasmodium. 

Treatment:      Little  is  known  about 
treatment  of  Haemoproteus  infections. 
According  to  Coatney  (1935),  quinacrine 
inhibits  the  development  of  young  gameto- 
cytes  of  H.  columbae,    while  pamaquine 
destroys  the  mature  ones.     Neither  is 
effective  against  the  schizonts.     However, 
in  view  of  the  slight  pathogenicity  of 
Haemoproteus,  treatment  does  not  seem 
warranted. 

Prevention  and  Control:     Prevention 
of  Haemoproteus  infections  depends  on 
control  of  their  hippoboscid  and  midge 
vectors,  or,  at  least  in  the  latter  case, 
in  preventing  the  birds  from  being  bitten. 

Genus  LEUCOCYTOZOON 
Danilewsky,   1890 

The  macrogametes  and  microgameto- 
cytes occur  in  the  leucocytes  or,  in  some 


Synonyms:      Leucocytozoon  anatis, 
Lencocytozoon  anseris. 

Disease:      Leucocytozoonosis. 

Hosts:     Domestic  ducks,  domestic 
goose  and  many  wild  anseriform  birds. 
Levine  and  Hanson  (1953)  tabulated  reports 
of  L.   simondi  from  23  species  of  wild 
waterfowl,   including  the  grey-lag  goose, 
white -fronted  goose,   Canada  goose,  wood 
duck,  American  pintail,  green-winged 
teal,  teal  duck,  blue-winged  teal,  falcated 
teal,  mallard,  black  duck,  baldpate,  shov- 
eller, scaup,   lesser  scaup,   ring-necked 
duck,   redhead,  canvasback,  American 
goldeneye,  old  squaw  duck,   hooded  mer- 
ganser, American  merganser  and  red- 
breasted  merganser. 

Fallis,   Pearson  and  Bennett  (1954) 
transmitted  L.  simondi  from  domestic 
ducks  to  domestic  geese,  but  failed  to  in- 
fect ruffed  grouse,  chickens,  turkeys  and 
pheasants  with  it. 

Location:     The  gametocytes  are  in  the 
lymphocytes,  monocytes  and  also  erythro- 
cytes.   Schizogony  takes  place  in  the  liver, 
heart,  brain,  spleen,  lungs,  lymph  nodes 
and  pancreas. 


Geographic  Distribution: 
America,  Europe,  Indochina. 


North 


276 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZCXDN 


Prevalence:     This  species  is  common 
in  northern  United  States,   Canada  and 
other  mountainous  or  hilly  areas  where 
cold,  rapid  streams  permit  suitable  black- 
fly  vectors  to  breed. 


Fig.  33.      Species  of  Leiicocytozoon  in  avian 
leucocytes.     A.    L.   smithi  macro- 
gamete  from  turkey.     B.    L.  si- 
tiiondi  microgametocyte  from  duck. 
X  1400.     (Original) 


Morphology:     The  mature  macroga- 
metes  and  microgametocytes  are  more  or 
less  elongate,  and  14  to  22  fi  long.     Their 
host  cells  are  ordinarily  elongate,  up  to 
45  to  55 (J,  long,  with  their  nucleus  form- 
ing a  very  long,  thin,  dark  band  along  one 
side  and  with  pale  cytoplasmic  "horns" 
extending  out  beyond  the  parasite  and  the 
nucleus.    In  some  cases,   round  macro- 
gametes  and  microgametocytes  in  rounded 
host  cells  have  been  reported  (Fallis, 
Davies  and  Vickers,   1951;  Rawley,   1953; 
Cook,   1954);  both  types  are  mature  and 
able  to  exflagellate.    Briggs  (1960)  noted 
that  there  were  approximately  equal  num- 
bers of  round  and  elongate  forms  in  white 
Pekin  ducks  but  that  elongate  forms  were 
rare  in  Muscovy  ducks,  never  constituting 
more  than  5%  of  the  total  number.     He 
suggested  that  this  might  be  due  to  the  in- 
fluence of  the  host  species. 

The  cytoplasm  of  the  macrogametes 
is  rather  dark  blue  and  the  nucleus  com- 
pact and  red  when  stained  with  a  Roman- 
owsky  stain.     The  cytoplasm  of  the  micro- 
gametocytes is  very  pale  blue  and  the 
nucleus  diffuse  and  pale  pink.     The  micro- 
gametocytes are  more  delicate  and  more 
subject  to  distortion  than  the  macroga- 
metes. 


A  good  deal  of  controversy  has  existed 
as  to  the  type  of  cell  parasitized  by  L. 
sii>io)idi.     The  host  cells  of  the  mature 
gametocytes  are  so  distorted  that  they 
cannot  be  recognized.     Huff  (1942)  consid- 
ered them  to  be  lymphocytes  or  stages  in 
transformation  between  them  and  mono- 
cytes.    Levine  and  Hanson  (1953) found 
young  and  developing  forms  only  in  lymph- 
ocytes or  monocytes.     On  the  other  hand, 
Fallis,  Davies  and  Vickers  (1951)  and 
Cook  (1954)  found  very  young  forms  in  both 
lymphocytes  and  erythrocytes.     Using  the 
benzidine-peroxide  stain  for  hemoglobin. 
Cook  found  no  hemoglobin  in  the  host  cells 
containing  mature  gametocytes,   but  she 
found  at  least  some  hemoglobin  in  all  of 
the  191  host  cells  she  saw  which  contained 
developing  gametocytes.    She  concluded 
that,  while  the  ring  stages  may  invade  both 
erythrocytes  and  lymphocytes,  they  develop 
to  maturity  only  in  cells  of  the  red  blood 
series.     Whatever  the  host  cell  may  be,  the 
gametes  and  gametocytes  never  contain 
hematin  pigment  granules. 

Life  Cycle:     The  life  cycle  has  been 
studied  by  O'Roke  (1934),   Huff  (1942), 
Fallis,  Davies  and  Vickers  (1951),   Fallis, 
Anderson  and  Bennett  (1956)  and  Cowan 
(1955)  among  others.     Birds  become  in- 
fected when  bitten  by  a  blackfly  vector. 
The  sporozoites  enter  the  blood  stream, 
invade  various  tissue  cells,   round  up  and 
become  schizonts. 

Two  types  of  schizont  occur  in  the 
duck.     Hepatic  schizonts  11  to  18fi  in 
diameter  occur  in  the  liver  cells;  they 
form  a  number  of  cytomeres  which  in 
turn  form  small  merozoites  by  multiple 
fission. 

Megaloschizonts  60  to  164;i  in  diam- 
eter when  mature  are  found  in  the  brain, 
lung,  liver,  heart,  kidney,  gizzard,  in- 
testine and  lymphoid  tissues  4  to  6  days 
after  exposure.     They  are  more  common 
than  the  hepatic  schizonts.     The  megalo- 
schizonts develop  in  cells,   possibly  lymph- 
oid cells  or  macrophages,  within  or  out- 
side the  blood  vessels.     They  contain 
numerous  cytomeres  and  a  large,   conspic- 
uous central  body  which  may  be  either  a 
primordium  off  of  which  the  cytomeres 


PLASMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZCX5N 


277 


have  budded  (Cowan)  or  perhaps  a  hyper- 
trophied  host  cell  nucleus  (Huff). 

According  to  Cowan,   spherical  pri- 
mary cytomeres  are  first  formed.     Their 
chromatin  first  diffuses  and  then  prolifer- 
ates to  form  peripheral  clusters,  which 
separate  to  form  secondary  cytomeres, 
which  in  turn  multiply  in  the  same  manner. 
The  multiplying  cytomeres  become  smaller 
and  more  granular,  their  chromatin  be- 
comes more  concentrated,  and  finally 
merozoite-like  bodies  are  formed.    These 
reproduce  until  the  central  body  is  greatly 
compressed  and  the  megaloschizont  mem- 
brane is  ruptured,   releasing  the  mero- 
zoites  into  the  blood.     Many  thousands  of 
bipolar  merozoites  are  produced  by  each 
megaloschizont. 

In  addition  to  the  hepatic  schizonts 
and  megaloschizonts,  small  structures 
thought  to  be  schizonts  were  found  by 
R.  C.  Ritchie  (cited  by  Fallis,  Anderson 
and  Bennett,   1956)  in  the  Kupffer  cells 
of  the  liver  of  a  duck  killed  3  days  after 
exposure. 

On  the  basis  of  these  observations, 
Fallis,  Anderson  and  Bennett  postulated 
the  following  life  cycle:    The  first  asexual 
generation  occurs  in  the  Kupffer  cells  of 
the  liver.    Some  of  the  merozoites  from 
these  schizonts  may  develop  into  gameto- 
cytes;  this  explains  the  presence  of  a  few 
large  parasites  in  the  blood  5  to  6  days 
after  infection.     Other  merozoites  from 
the  first  generation  schizonts  develop  into 
hepatic  schizonts,  megaloschizonts  and 
perhaps  other  Kupffer  cell  schizonts. 
Merozoites  arising  from  megaloschizonts 
and  hepatic  schizonts  develop  into  gameto- 
cytes  which  flood  into  the  peripheral  circu- 
lation beginning  6  to  7  days  after  infection. 
Some  of  these  merozoites  presumably  de- 
velop into  another  asexual  generation. 

The  development  of  the  gametocytes 
in  the  blood  cells  has  already  been  men- 
tioned in  the  section  on  morphology. 
According  to  Chernin  (1952),  the  gameto- 
cytes may  disappear  from  the  blood  about 
30  days  after  they  first  appear.     Following 
this  primary  parasitemia,  which  begins  in 
mid-summer  in  northern  Michigan,  only 


an  occasional  parasite  is  seen  in  the  blood 
during  the  fall  and  winter  (O'Roke,   1934; 
Huff,   1942;  Chernin,   1952a).     With  the 
development  of  sexual  activity  in  the  spring, 
gametocytes  reappear  in  the  blood  and  in 
some  cases  continue  to  be  present  thruout 
the  summer. 

It  is  clear  from  this  account  that  schi- 
zogony continues  in  the  internal  organs  for 
an  indefinite,   long  time,  altho  at  a  much 
reduced  rate.     There  are  about  1000  times 
fewer  gametocytes  in  the  relapse  phase 
than  in  the  primary  infection,  and  these 
adult  birds  are  not  seriously  affected. 
However,  they  serve  as  the  source  of  in- 
fection for  the  new  crop  of  ducklings. 

According  to  Chernin  (1952a),  the 
early  season  infections  in  ducklings  are 
comparatively  light,  but  the  heavier  pool 
of  gametocytes  provided  by  these  primary 
infections  in  the  first  crop  ducklings  en- 
sures the  heavier  and  highly  fatal  infec- 
tions which  occur  during  midsummer. 

The  vectors  of  L.  simondi  are  various 
species  of  blackflies  {ShnuUmn).    O'Roke 
(1934)  showed  that  S.  venustum  is  the  vec- 
tor in  Michigan.     Fallis,   Anderson  and 
Bennett  (1956)  found  that  S.  croxtoni  and 
S.  euryacbniniculHm  are  the  important 
vectors  during  the  early  part  of  the  black- 
fly  season  (May  to  June)  in  Ontario,  while 
S.  rugglesi  is  the  important  vector  in  late 
June  and  July. 

In  the  blackfly's  stomach  (O'Roke, 
1934;  Fallis,  Davies  and  Vickers,   1951; 
Rawley,   1953),   4  to  8  microgametes  are 
formed  within  a  few  minutes  by  exflagella- 
tion  from  the  microgametocytes.     These 
fertilize  the  macrogametes  to  form  a  mo- 
tile zygote  or  ookinete  about  33  /i  long  and 
5|Lt  wide.     Ookinetes  are  present  in  the 
blackfly  stomach  2  to  6  hours  after  inges- 
tion of  infected  blood.    They  develop  into 
oocysts  both  in  the  stomach  wall  and  in 
the  stomach  itself. 

The  oocysts  are  10  to  13  |i  in  diameter. 
They  can  be  found  2  to  3  days  after  infection, 
and  complete  their  development  2.  5  to  4 
days  after  infection.     They  produce  rela- 
tively few  sporozoites  compared  with 


278 


PI^SMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


Plasmodium .    The  sporozoites  are  5  to 
10(1  long,   slender,  with  one  end  rounded 
and  the  other  pointed.    They  break  out  of 
the  oocysts  and  pass  to  the  salivary 
glands,  where  they  accumulate.     Viable 
sporozoites  can  be  found  for  at  least  18 
days  after  infective  feeding. 

Pathogenesis:      L.  simondi  is  mark- 
edly pathogenic  for  ducks  and  geese.    The 
heaviest  losses  occur  among  young  birds. 
O'Roke  (1934)  reported  mortalities  of 
35%,   57%  and  85%  among  young  ducks  in  3 
different  years  in  Michigan,  but  noted  that 
the  death  rate  among  adults  was  very  low. 
Knuth  and  Magdeburg  (1922)  and  Stephan 
(1922)  described  serious  outbreaks  in 
young  geese  in  Germany.     According  to 
Chernin  (1952b),  about  68%.  of  the  deaths 
in  ducklings  occur  11  to  19  days  after  ex- 
posure. 

Briggs  (1960)  found  that  Muscovy 
ducklings  were  more  resistant  to  L. 
simondi  infections  than  white  Pekin  duck- 
lings under  conditions  of  natural  exposure 
in  Michigan.    Altho  both  became  readily 
infected,  the  mortality  and  number  of  sex- 
ual forms  in  the  blood  were  much  lower 
among  the  Muscovies  than  the  white  Pekins. 
In  addition,  deaths  were  delayed  in  the 
Muscovies. 

The  outstanding  feature  of  an  outbreak 
of  leucocytozoonosis  is  the  suddenness  of 
its  onset.    A  flock  of  ducklings  may  appear 
normal  in  the  morning,   may  become  ill  in 
the  afternoon,  and  may  be  dead  by  the  next 
morning.     Acutely  affected  ducklings  are 
listless  and  do  not  eat.    Their  breathing 
is  rapid  and  labored  due  to  obstruction  of 
the  lung  capillaries  with  schizonts.    They 
may  go  thru  a  short  period  of  nervous  ex- 
citement just  before  death.    Adult  birds 
are  more  chronically  affected.     They  are 
thin  and  listless,  and  the  disease  develops 
more  slowly  in  them.    If  they  die  at  all,   it 
is  seldom  in  less  than  4  days  after  the 
appearance  of  signs.    Ducklings  which  have 
recovered  often  fail  to  grow  normally.    Re- 
covered birds,  as  mentioned  above,  re- 
main carriers. 

The  principal  lesions  of  leucocyto- 
zoonosis are  splenomegaly  and  liver  hy- 


pertrophy and  degeneration.  Anemia  and 
leucocytosis  are  present,  and  the  blood 
clots  poorly.  Cowan  (1957)  described  the 
tissue  reactions  of  infected  ducks  against 
the  megaloschizonts.  These  include  des- 
truction by  phagocytes  and  inflammatory 
cells,  necrosis  and  possibly  encapsulation. 

Diagnosis:     Leucocytozoonosis  can  be 
diagnosed  by  finding  and  identifying  the 
gametocytes  in  stained  blood  smears  or  the 
schizonts  in  tissue  sections. 

Treatment:     No  effective  treatment  is 
known.     Fallis  (1948)  found  that  quinacrine, 
sulfamerazine  and  chlorguanide  were  in- 
effective. 

Prevention  and  Control:     Prevention 
depends  upon  blackfly  control--ordinarily 
a  difficult  task--or  on  raising  ducks  and 
geese  under  conditions  which  prevent  them 
from  being  bitten  by  blackflies.    In  black- 
fly  areas  this  means  raising  them  in 
screened  quarters.     Blackflies  pass  readily 
thru  ordinary,   16  mesh  per  inch  window 
screening,  and  32  to  36  mesh  screen  is 
needed  to  keep  them  out.    Since  this  type 
of  screening  is  expensive,  a  good  grade  of 
cheesecloth  has  been  recommended  for  a 
single  season's  use. 

This  disease  can  be  avoided  entirely 
by  raising  ducks  and  geese  in  regions 
where  blackflies  do  not  occur  in  significant 
numbers.    Since  wild  ducks  and  geese  are 
reservoirs  of  infection  for  domestic  birds, 
the  latter  should  not  be  raised  close  to 
places  where  wild  waterfowl  congregate. 


LEUCOCYTOZOON  SMITHI 
LAVERAN  AND   LUCET,    1905 

Disease:     Leucocytozoonosis. 

Hosts:     Domestic  and  wild  turkeys. 

Location:     The  gametocytes  are  in 
the  leucocytes.    Schizogony  occurs  in  the 
liver. 

Geographic  Distribution:  North 
America,  Europe  (France,  Germany, 
Crimea). 


PLASMODIUM,    HAEMOPROTEUS  AND  LEUCOCYTOZOON 


279 


Pi'e valence:     This  species  is  common 
in  northern  and  southeastern  United  States, 
along  the  Gulf  Coast  and  Pacific  Coast  and 
in  Canada  in  mountainous  or  hilly  areas 
wherever  cold,  rapid  streams  permit  suit- 
able blackfly  vectors  to  breed.     It  was 
first  seen  by  Smith  (1895)  in  eastern  United 
States,  and  has  been  encountered  in  North 
Dakota,   Minnesota,   Nebraska,  Wisconsin, 
Illinois,   Virginia,  South  Carolina,  Georgia, 
Alabama,   Florida,   Pennsylvania,   Missouri, 
Texas,   California,  Ontario  and  Manitoba 
(Volkmar,   1929;  Skidmore,   1932;  Johnson, 
1942,   1945;  Johnson  et  al.  .  1938;  Hinshaw 
and  McNeil,   1943;  Banks,   1943;  Stoddard, 
Humlin  and  Cooperrider,   1952;  Travis, 
Goodwin  and  Gambrell,   1939;  Mosby  and 
Handley,   1943;  Wehr  and  Coburn,   1943; 
Kozicky,   1948;  West  and  Starr,   1940; 
Atchley,   1951;  Bierer,   1950;  Simpson 
Anthony  and  Young,   1956;  Savage  and  Isa, 
1945;  Fallis,   Pearson  and  Bennett,   1954). 

Travis,  Goodwin  and  Gambrell  (1939) 
found  it  in  81%  of  357  adult  domesticated 
turkeys  in  Georgia,   Florida,  Alabama 
and  South  Carolina.     Mosby  and  Handley 
(1943)  found  it  in  40%  of  268  captivity- 
reared  wild  turkeys,  wild  turkeys  and 
domestic  turkeys  in  Virginia.    Kozicky 
(1948)  found  it  in  21%  of  92  captivity-reared 
and  all  of  5  native  wild  turkeys  in  Penn- 
sylvania.    Atchley  (1951)  found  it  in  all  of 
10  domestic  turkeys  in  South  Carolina. 

Morphology:     The  mature  macroga- 
metes  and  microgametocytes  are  rounded 
at  first  but  later  become  elongate,  aver- 
aging 20  to  22  |j.  in  length.     Their  host 
cells  are  elongate,  averaging  45  by  14|j,, 
with  pale  cytoplasmic  "horns"  extending 
out  beyond  the  enclosed  parasite.     The 
host  cell  is  elongate,  forming  a  long,  thin, 
dark  band  along  one  side  of  the  parasite; 
often  it  is  split  to  form  a  band  on  each 
side  of  the  parasite.     The  cytoplasm  of  the 
macrogametes  is  rather  dark  blue  and  the 
nucleus  compact  and  red  when  stained 
with  a  Romanowsky  stain.     The  cytoplasm 
of  the  microgametocytes  is  very  pale  blue 
and  the  nucleus  diffuse  and  pale  pink. 

Life  Cycle:     The  life  cycle  of  L. 
smithi  is  similar  to  that  of  L.  simondi, 
but  is  not  known  in  nearly  so  much  detail. 


The  prepatent  period  is  about  9  days. 
Newberne  (1955)  and  Richey  and  Ware 
(1955)  described  hepatic  schizonts  in  the 
liver  parenchyma  of  infected  turkeys. 
According  to  Newberne,  they  measure  10 
to  20  by  7  to  14 /J.,  with  a  mean  of  13.  5  by 
10.  5ji  .     The  earliest  stage  he  saw  con- 
tained round  and  crescent-shaped,  baso- 
philic cytomeres.    These  developed  into 
masses  of  deeply  staining  merozoites  which 
completely  filled  the  host  cell  cytoplasm. 
Megaloschizonts  have  not  been  seen. 

The  vectors  of  L.  siiiitlii  are  various 
species  of  blackflies  {Siiiinlii(m).    Skid- 
more  (1932)  found  that  S.  occidentale 
transmitted  it  in  Nebraska,  Johnson  et  al. 
(1938)  found  S.   nigroparvuui  to  be  the 
vector  in  Virginia,  and  Richey  and  Ware 
(1955)  showed  that  S.  slossonae  could 
transmit  it  in  South  Carolina.     The  stages 
in  the  blackflies  are  similar  to  those  of 
L.  simondi. 

Pathogenesis:      L.  smithi  is  markedly 
pathogenic  for  turkeys,  and  extremely 
heavy  losses  have  been  reported.     Savage 
and  Isa  (1945)  described  an  outbreak  in 
Manitoba  in  which  more  than  3000  out  of 
8000  birds  died  in  2  months.     Not  more 
than  10%)  of  the  birds  which  became  ill  re- 
covered.   Stoddard,   Humlin  and  Cooper- 
rider  (1952)  described  an  outbreak  in 
Georgia  in  which  75%  of  1600  5-month-old 
turkeys  died  within  a  week.     Adult  birds 
are  less  seriously  affected  than  poults, 
and  the  disease  runs  a  slower  course  in 
them,  but  even  they  may  die. 

Affected  poults  fail  to  eat,   appear 
droopy  and  tend  to  sit.     They  move  with 
difficulty  when  disturbed;  in  the  later 
stages  there  may  be  incoordination,  and 
the  birds  may  suddenly  fall  over,   gasp, 
become  comatose  and  die.    If  the  birds  do 
not  die  within  2  or  3  days  after  signs  of 
disease  appear,  they  recover. 

Recovered  birds  continue  to  carry 
parasites  in  their  blood.    Some  may  show 
no  serious  after-effects,  but  others  de- 
velop a  chronic  type  of  the  disease.     They 
never  regain  their  vigor,   and  the  males 
pay  little  attention  to  the  females  and 
rarely  strut.     They  often  have  moist 


280 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


tracheal  rales,  and  cough  and  repeatedly 
try  to  clear  their  throats  when  disturbed. 
They  may  die  suddenly  under  stress  caused 
by  undue  excitement  or  handling. 

The  spleen  and  liver  of  affected  birds 
are  enlarged,  and  the  duodenum  is  more 
or  less  inflamed.    This  enteritis  may 
sometimes  extend  thruout  the  small  intes- 
tine.    The  birds  are  anemic  and  emaciated, 
their  flesh  is  flabby,  and  their  muscles 
may  be  brownish.     There  are  no  gross 
lesions  in  adult  carriers,  but  the  liver  may 
occasionally  be  icteric,  enlarged  and  cir- 
rhotic.    Newberne  (1955)  saw  no  local  tis- 
sue reaction  around  the  hepatic  schizonts, 
but  noted  hepatic  hemosiderosis  and  lymph- 
ocytic infiltration. 

According  to  Johnson  et  al.    (1938), 
death  is  due  to  obstruction  of  the  circula- 
tory system  by  large  numbers  of  parasites. 

Diagnosis,  Treatment,   Prevention  and 
Control:     Same  as  for  L.  sinwndi. 


LEUCOCYTOZOON  CAULLERYI 
MATfflS  AND   LEGER,   1909 

Synonyms:  Leucocytozoon  andrewsi 
Atchley,  1951;  Leucocytozoon  schueffneri 
Prowazek,   1912  pro  parte. 

Hosts:     Chicken. 

Location:     The  gametocytes  are  in 
the  leucocytes  and  erythrocytes. 

Geographic  Distribution:     Indochina, 
Malaya,  India,  Sumatra,   North  America 
(South  Carolina). 

Prevalence:     This  species  is  rela- 
tively uncommon  except  perhaps  in  Malaya. 
Atchley  (1951)  found  it  in  15%  of  400  adult 
domestic  chickens  in  South  Carolina,  but 
his  is  the  only  report  of  it  in  North  Amer- 
ica.   It  has  been  found  in  Indochina  by 
Mathis  and  Leger  (1909),   in  Sumatra  by 
Prowazek  (1912),   in  Malaya  by  Kuppusamy 
(1936),  and  in  India  by  Ramanujachari  and 


Alwar  (1953),   Ramaswami  (1955),  and 
Biswal  and  Naik  (1958).     In  addition,   Ham- 
erton  (1929)  reported  a  Leucocytozoon 
without  describing  it  from  a  domestic 
chicken  and  a  jungle  fowl  {Callus  lajayettei) 
in  the  London  zoo. 

Morphology:     The  mature  gametocytes 
are  round,   measuring  15.  5  by  15.  O/i  ac- 
cording to  Mathis  and  Leger  (1909).     Ac- 
cording to  Atchley  (1951)  the  macroga- 
metes  are  12  to  14  |j.  in  diameter  with  a 
nucleus  generally  3  to  4fi  in  diameter,  and 
the  microgametocytes  are  10  to  12  fi  in 
diameter  with  a  nucleus  10  to  12  fj.  in  diam- 
eter occupying  most  of  the  cell.     The  host 
cell  is  round,  about  20  ji  in  diameter  ac- 
cording to  Mathis  and  Leger  and  13  to  11  \x 
in  diameter  according  to  Atchley.     The 
host  cell  nucleus  forms  a  narrow,  dark 
band  extending  about  a  third  of  the  way 
around  the  parasite.    The  macrogametes 
stain  more  darkly  with  Romanowsky  stains 
than  the  microgametocytes. 

Life  Cycle:     Unknown.     Atchley  (1951) 
described  exflagellation  of  the  microga- 
metocytes, and  figured  one  with  what  ap- 
peared to  be  6  microgametes. 

Pathogenesis:     This  species  is  pre- 
sumably pathogenic,  but  accounts  of  it  have 
been  so  mixed  up  with  those  of  L.  sabrazesi 
(see  below)  that  its  pathogenicity  is  uncer- 
tain. 

Remarks:     Another  species  of  Leuco- 
cytozoon,  L.  sabrazesi,   with  elongate 
gametocytes,   has  been  described  from  the 
chicken.     There  has  been  a  good  deal  of 
uncertainty  as  to  whether  L.  caulleryi 
may  not  be  merely  an  immature  stage  of 
L.  sabrazesi.     Many  of  the  infections 
which  have  been  seen  have  been  mixed 
ones.     However,   Mathis  and  Leger,  who 
first  described  both  species,  found  pure 
infections  of  each,   and  Atchley  found  only 
round  forms  in  the  61  infected  chickens 
which  he  studied,  some  of  which  he  kept 
under  observation  for  a  year.     In  addition, 
Atchley' s  observation  of  exflagellation 
leaves  no  doubt  that  the  round  forms  are 
mature. 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZOON 


281 


LEUCOCYTOZ OON  SA BRA ZESI 
MATfflS   AND   LEGER,    1910 

Synonyms:      Lencocylozoon  scli/ieff- 
iieri  Prowazek,   1912  pro  parte. 

Hosts:      Chicken. 

Location:     The  gametocytes  are  in 
the  leucocytes  and  erythrocytes. 

Geographic  Distribution:      Indochina, 
Malaya,   India,  Sumatra,  Java. 

Prevalence:      Relatively  uncommon 
except  perhaps  in  Malaya.    L.  sabrazesi 
has  been  found  in  Indochina  by  Mathis  and 
Leger  (1910),   in  Malaya  by  Kuppusamy 
(1936),  and  in  India  by  Ramanujachari  and 
Alwar  (1953),   Ramaswami  (1955)  and 
Biswal  and  Naik  (1958).     In  addition,  de 
Haan  (1911)  reported  a  Leiicocyluzooii  in 
the  chicken  in  Java  which  he  assigned  to 
L.  i/eavei  (a  species  with  elongate  gameto- 
cytes occurring  in  the  guinea  fowl)  but 
which  was  undoubtedly  L.  sahyazesi. 

Morphology:     The  mature  gametocytes 
are  elongate  and  measure  about  24  by  4  (i 
according  to  Mathis  and  Leger  (1910). 
According  to  Ramanujachari  and  Alwar 
(1953),  the  macrogametes  average  22  by 
6.  5|j.  and  the  microgametocytes  20  by  6/j. 
The  host  cells  are  spindle-shaped,  with 
long,   cytoplasmic  "horns"  extending  be- 
yond the  parasites,  and  measure  about  67 
by  &\i  according  to  Mathis  and  Leger  (1910). 
The  host  cell  nucleus  forms  a  narrow, 
darkly  staining  band  along  one  side  of  the 
parasite.     The  macrogametes  stain  more 
darkly  with  Romanowsky  stains  than  the 
microgametocytes,  and  have  a  more  com- 
pact nucleus. 

Life  Cycle:     Unknown. 


in  the  chicken  in  Sumatra.     He  saw  and 
illustrated  both  spindle-shaped  and  round 
host  cells,  but  gave  dimensions  only  for 
the  spindle-shaped  ones.     These  ranged  in 
length  from  45  by  66 /i  .     He  also  observed 
granules  in  the  host  cell  cytoplasm  which 
stained  red  with  Giemsa's  stain.     He  stated 
that  these  granules  were  partially  missing 
in  L.  caiilleryi  and  L.  sabrazesi  and  that 
he  was  establishing  his  new  species  because 
of  this  and  also  because  of  the  difference  in 
size  between  them  and  his  form.     However, 
the  dimensions  he  quoted  for  L.  sabrazesi 
were  those  of  the  parasite  itself  and  not 
those  of  the  host  cell,  and  the  dimensions 
he  gave  for  L.  schiieffiieri  were  those  of 
the  host  cell  and  not  those  of  the  parasite 
itself.     There  is  actually  no  significant 
difference  in  size  between  the  two  forms, 
and  Prowazek' s  name  becomes  a  synonym 
of  L.  sabrazesi  and  also,   in  part,  of  L. 
caiilleryi.    Prowazek  also  saw  Trypano- 
soma in  the  same  chicken,  and  thought  it 
was  a  stage  of  Leiicocyiozooi/. 

The  type  of  cell  parasitized  by  Leuco- 
cytozoon  has  been  the  subject  of  some  dis- 
cussion (see  under  L.  siiitoiidi,    p.   276). 
The  host  ceils  containing  mature  gameto- 
cytes are  so  distorted  as  to  be  unrecog- 
nizable.    Both  Ramanujachari  and  Alwar 
(1953)  and  Ramaswami  (1955)  considered 
them  to  be  erythrocytes.     In  the  slide  sent 
to  me  by  Biswal,  I  saw  one  very  young 
parasite  in  a  cell  which  appeared  to  be  an 
erythrocyte,  but  the  host  cells  of  other, 
somewhat  older  parasites  did  not  appear 
to  be.     Further  study  is  needed  on  this 
point.     At  any  rate,  the  parasites  do  not 
form  hematin  granules  from  hemoglobin. 


LEUCOCYTOZOON  MARCHOUXI 
MATHIS   AND   LEGER,   1910 


Pathogenesis:  According  to  Kuppus- 
amy (1936),  this  species  causes  a  disease 
in  chickens  characterized  by  anemia,  py- 
rexia, diarrhea,  paralysis  of  the  legs  and 
a  ropy  discharge  from  the  mouth.  Raman- 
ujachari and  Alwar  (1953)  observed  similar 
signs  in  the  bird  they  studied. 

Remarks:      Prowazek  (1912)  gave  the 
name  L.  schueffneri  to  the  forms  he  found 


Synonyms:      Leiicocytozooii  tiirtiir. 

Hosts:     Various  doves  and  pigeons. 
Levine  (1954)  and  Levine  and  Kantor  (1959) 
assembled  reports  of  Leucocytozoon  from 
17  species  of  7  genera  of  columbiform 
birds.     All  but  one  were  probably  L.  )}iar- 
cliOHxi.    There  is  only  a  single  report  of 
this  species  in  the  domestic  pigeon,  by 
Jansen  (1952)  in  South  Africa. 


282 


PLASMODIUM,   HAEMOPROTEUS  AND  LEUCOCYTOZCXDN 


Location:     The  ganietocytes  are  in 
the  white  blood  cells. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  fairly 
common  in  wild  doves.     Hanson  el  al. 
(1957),  for  example,  found  it  in  1.2'/c  of 
392  immature  and  6.  5%  of  72  adult  mourn- 
ing doves  {Zenaidura  macroiira)  in  Illinois. 

Morphology:      Levine  (1954)  redes- 
cribed  this  species.     The  macrogametes 
are  rounded  or  elliptical,   8  to  15  by  7  to 
11  fi  with  a  mean  of  12  by  9 p.;  they  stain 
dark  blue  with  Giemsa's  stain  and  have  a 
compact,   reddish  nucleus.     The  micro- 
gametocytes  are  often  distorted  or  rup- 
tured by  the  smearing  process,  but  if  not 
badly  damaged  measure  8  to  15  by  5  to 
11  (1  with  a  mean  of  11  by  8  (i .     They  stain 
pale  blue  with  Giemsa's  stain  and  have  a 
very  diffuse,   pale  pink  nucleus.     Host 
cell  cytoplasm  is  rarely  seen  surrounding 
the  microgametocytes  and  was  found  in 
only  26%  of  the  cells  parasitized  by  macro- 
gametes.    When  present,   it  forms  a  nar- 
row border  around  part  of  all  of  the  para- 
site's periphery.     The  host  cell  nucleus 
forms  a  dark-staining  band  along  about 
1/3  of  the  periphery  of  the  parasite. 

Young  gametocytes  were  seen  only  in 
lymphocytes  or,  in  one  case,  in  a  mono- 
cyte. 

Life  Cycle:      Unknown. 

Pathogenesis:     Unknown.     There  were 
no  signs  of  illness  in  the  infected  mourning 
doves  seen  by  Levine  (1954),  even  though 
4  of  them  were  nestlings  and  1  was  only 
14  days  old. 


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Members  of  this  class  constitute  a 
fairly  cohesive  group  of  blood  cell  para- 
sites of  vertebrates.     They  are  small  in 
comparison  with  the  Plasmodiidae.     They 
are  piriform,   round,  amoeboid  or  rod- 
shaped,  depending  in  part  on  the  genus. 
They  occur  in  the  erythrocytes,  and  some 
genera  occur  in  the  leucocytes  or  histio- 
cytes as  well.     Pigment  (hemozoin)  is  not 
formed  from  the  host  cell  hemoglobin. 
No  spores  are  formed,  and  no  flagella  or 
cilia  are  present.     Locomotion  is  by  body 
flexion  or  gliding.     Reproduction  is  asex- 
ual, by  binary  fission  or  schizogony. 
Budding  has  also  been  said  to  occur,  but 
the  processes  described  under  this  name 
are  actually  binary  fission  with  the  forma- 
tion of  2  daughter  cells  or  schizogony 
with  the  formation  of  4.     The  existence  of 
sexual  reproduction  is  dubious,  altho  it 
has  been  described  by  earlier  authors. 
The  Piroplasmasida  are  heteroxenous;  the 
known  vectors  are  ixodid  or  argasid  ticks. 

The  systematic  position  of  this  group 
is  still  uncertain,  and  varies  with  the 
authority.     The  position  given  it  here 
seems  reasonable. 

There  is  a  single  order,   Piroplas- 
morida.    It  contains  2  families,  both  of 
which  contain  parasites  of  domestic 
animals. 


Chapter  11 


THE 
mOPLASMASm 


FAMILY   BABESIIDAE 

Members  of  this  family  are  relatively 
large,   piriform,   round  or  oval  parasites. 
They  occur  in  the  erythrocytes,  where 
they  reproduce  asexually  by  binary  fission 
or  schizogony.     The  vectors  are  ixodid  or 
argasid  ticks.     Binary  fission,  schizogony 
and  sexual  reproduction  have  been  des- 
cribed in  the  tick,  but  the  existence  of 
sexual  reproduction  is  dubious,  and  Reich- 
enow  (1953)  believed  that  schizogony  is 
simulated  by  repeated  binary  fissions. 

By  far  the  most  important  genus  in 
the  family  is  Babesia,  species  of  which 


-  285 


286 


THE  PIROPLASM-^SIDA 


cause  piroplasmosis  or  babesiosis,  a 
group  of  highly  fatal  and  economically  im- 
portant diseases  of  livestock.    Other  gen- 
era are  Echinozoon  and  Aegyptianella. 


Genus   BABESIA   Starcovici,   1893 


For  practical  purposes,  one  can  divide 
the  genus  into  2  groups  of  species,   large 
forms  more  than  3|i  long  and  small  forms 
less  than  3(i  long.    In  general,  infections 
with  the  large  forms  can  be  successfully 
treated  with  trypan  blue,  while  infections 
with  the  small  ones  cannot. 


In  this  genus  the  trophozoites  multiply 
by  binary  fission  in  the  erythrocytes, 
forming  pairs,  or  by  schizogony,  forming 
tetrads.     A  "blepharoplast"  from  which  a 
rhizoplast  arises  has  been  described  in 
the  trophozoites.     However,   Rudzinska 
and  Trager  (1960)  did  not  report  seeing 
either  of  these  structures  in  electron 
micrographs  of  Babesia  rodhaini  irom  the 
mouse. 

If  present,  the  blepharoplast  and 
rhizoplast  may  betray  a  flagellate  origin 
for  the  group  (Dennis,   1932).     However, 
Reichenow  (1953)  thought  that  it  originated 
from  the  amoebae.    Another  possibility  is 
that  it  is  related  to  PlasniocUiim.    This  is 
suggested  by  Rudzinska  and  Trager's  (1960) 
finding  in  B.  rodhaini  of  structures  com- 
posed of  concentric  membranes  (possibly 
representing  primitive  mitochondria) 
similar  to  those  they  had  previously  seen 
in  Plas)>iodimii  berghei,  and  by  their  ob- 
servation that  B.  rodhaini  apparently  en- 
gulfs bits  of  host  cell  cytoplasm  by  phago- 
trophy  like  Plasmodium . 

There  are  two  opposing  schools  of 
thought  as  to  the  speciation  of  this  genus. 
One  breaks  it  up  into  several  genera  or 
subgenera,  each  with  a  number  of  species 
(e.  g. ,  Sergent  et  al.  ,   1945;  Antipin  el  al.  , 
1959),  while  the  other  prefers  a  single 
genus  with  a  relatively  small  number  of 
species,  each  of  which  may  include  sev- 
eral strains  (e.g.,  Wenyon,   1926;  Neitz, 
1956).     The  second  system  seems  prefer- 
able.    The  taxonomy  of  the  group  has  been 
discussed  by  Reichenow  (1953),   Poisson 
(1953)  and  Laird  and  Lari  (1957)  in  addi- 
tion to  the  above  authors. 

Synonyms  of  Babesia  include  Piro- 
plasma,  Achro)>ialiciis,  Nicollia,  Niittal- 
lia,  Smithia,  Rossiella,  Microbabesia, 
Babesiella,  Francaiella,    Lnlisia,  Patton- 
ella,  Rangelia,  and  Gonderiain  part. 


Babesia  and  babesiosis  occur  in  most 
parts  of  the  world  where  there  are  ticks, 
except  in  countries  such  as  the  United 
States  where  they  have  been  wiped  out  by 
a  concerted  effort.     They  are  most  impor- 
tant in  the  tropics,  where,  along  with  the 
trypanosomoses,  they  often  dominate  the 
livestock  disease  picture.     However,  they 
also  occur  in  the  temperate  zone.     Bovine 
babesiosis  nearly  reaches  the  Artie  circle 
in  Norway,  and  Thambs-Lyche  (1943)  re- 
ported that  it  was  increasing  in  that  coun- 
try. 

Babesiosis  was  once  an  extremely 
important  disease  of  cattle  in  the  United 
States,  but  it  has  now  been  eliminated, 
and  the  only  domestic  animal  species  left 
in  this  country  is  B.  canis,   which  occurs 
in  dogs  in  Florida,   Virginia  and  Texas. 
However,   Babesia  is  still  important  in 
livestock  in  Central  and  South  America. 
It  occurs  in  most  of  Europe,  being  espe- 
cially important  in  the  countries  bordering 
the  Mediterranean  Ocean.     It  is  one  of  the 
most  important  diseases  of  livestock  in 
the  Middle  East,  thruout  Africa,  and  also 
in  parts  of  India  and  the  Far  East.     Its 
importance  in  the  USSR,  and  especially  in 
its  southern  part,  is  attested  by  the  fact 
that  61  X  of  the  protozoan  section  of  Antipin 
el  al.  's  (1959)  textbook  on  veterinary  para- 
sitology is  devoted  to  it  and  a  related  dis- 
ease, theileriosis.    It  also  occurs  in  Aus- 
tralia. 

Veterinarians  and  livestock  owners 
in  the  United  States  today  do  not  know 
what  it  is  to  have  to  contend  with  babesi- 
osis, but  other  parts  of  the  world  are  not 
so  fortunate.     The  disease  is  of  great  ec- 
onomic importance  in  the  tropics  and  sub- 
tropics;  indeed,   Curasson  (1943)  believed 
that  it  was  no  exaggeration  to  say  that  the 
babesioses  are  the  most  formidable  dis- 
eases of  livestock  in  these  regions  and 
that  they  are  taking  a  more  and  more 


THE  PIROPLASMASIDA 


287 


important  place  in  the  animal  disease 
picture  as  we  discover  new  manifesta- 
tions of  their  activity. 

Among  recent  discussions  of  babesi- 
osis and  its  manifestations  are  those  by 
Curasson  (1943),  Sergent  et  al.    (1945), 
Muromtseva  and  Dobrokhotova  (1955), 
Henning  (1956),   Malherbe  (1956)  and 
Antipin  et  al.  (1959). 

Life  Cycle:     The  trophozoites  of 
Babesia  occur  in  the  erythrocytes,  where 
they  multiply  by  binary  fission  or  by  schi- 
zogony.   In  some  species,  two  tropho- 
zoites are  formed,  which  break  out  of  the 
erythrocytes  and  enter  new  red  cells, 
while  in  others  tetrads  composed  of  4 
trophozoites  are  formed.     Some  authors 
place  the  latter  in  a  separate  genus, 
Nuttallia.     The  formation  of  more  than  4 
trophozoites  by  schizogony  has  also  been 
described  in  the  erythrocytes  (Dschun- 
kowsky,   1937;  Ivanic,   1942;  Delpy,   1946), 
but  most  workers  (e.  g.  ,  Reichenow,   1953) 
consider  that  it  is  merely  simulated  by 
repeated  binary  fissions  or  by  multiple 
invasion  of  a  host  cell. 

The  above  asexual  cycle  continues 
indefinitely,  the  animals  sometimes  re- 
maining infected  for  life. 

Babesia  is  transmitted  by  ticks.    The 
discovery  of  this  fact--by  Smith  and  Kil- 
borne  (1893)  for  B.  bigemi)ia  of  cattle-- 
was  a  milestone  in  the  history  of  para- 
sitology, since  it  was  the  first  demonstra- 
tion that  an  arthropod  was  the  vector  of 
any  disease. 

Dennis  (1932)  described  sexual  re- 
production of  B.  bigemina  from  cattle  in 
the  tick,  Boophilus  annulatus ,    and  Petrov 
(1941)  did  the  same  for  B.  bovis   in  Ixodes 
ricinus.     However,  Regendanz  and  Reich- 
enow (1933)  denied  its  existence  in  the 
life  cycle  of  B.  canis  from  the  dog  in 
Derniacentor  reticidatus,    and  Regendanz 
(1936)  and  Muratov  and  Kheisin  (1959) 
found  no  evidence  of  sexual  reproduction 
in  5.   bigemina  in  Boophilus  microplus 
and  B.  calcaratus,    respectively,  nor 
could  Polyanskii  and  Kheisin  (1959)  for 
B.  bovis  in  Ixodes  ricinus .     It  is  likely 


that  Dennis  and  Petrov  may  have  been 
misled  by  trying  to  draw  an  analogy  with 
the  life  cycle  of  Plasuiodiitiu .     Pending 
final  settlement  of  the  question,   however, 
both  accounts  are  given  below. 

According  to  Regendanz  and  Reichenow 
(1933),   most  of  the  B.  canis  ingested  by 
the  female  tick  die  in  its  intestine.    Some 
of  them  become  vermiform  and  enter  the 
intestinal  epithelial  cells,   coming  to  lie 
against  the  basal  membrane,  and  grow 
into  large  amoeboid  forms.     These  then 
multiply  by  a  series  of  binary  fissions, 
producing  more  than  1000  individuals  in  2 
to  3  days.     These  lie  together  loosely  at 
first,  but  finally  fill  the  whole  host  cell. 
They  then  become  vermiform  and  pass 
into  the  body  cavity. 

The  vermiform  stages  are  broadly 
rounded  at  the  anterior  end  and  pointed 
posteriorly,  about  16jj,  long,   and  have  a 
gliding  motion.     They  enter  the  ovary, 
where  they  penetrate  the  eggs.     Here  they 
round  up  and  divide  a  few  times,  forming 
very  small  round  individuals.     They  do 
not  develop  further  in  the  larval  tick 
which  hatches  from  the  egg,  but  when  it 
molts  they  enter  the  salivary  glands  and 
continue  their  development.     This  first 
occurs  in  the  nymphal  stage,  but  is  much 
more  active  in  the  adults,  both  male  and 
female.     The  parasites  undergo  a  series 
of  binary  fissions  and  enter  the  cells  of 
the  glandular  acini.     Here  they  multiply 
further,  becoming  smaller  and  filling  the 
whole  host  cell,   so  that  it  finally  contains 
thousands  of  minute  parasites.     These 
become  vermiform,  break  out  of  the  host 
cell,   come  to  lie  in  the  lumen  of  the  gland, 
and  are  injected  into  the  host  when  the  tick 
sucks  blood.     The  developmental  process 
in  the  salivary  glands  takes  2  to  3  days. 

The  tick  larvae  are  not  able  to  infect 
new  hosts.     The  nymphs  may  do  so,  but 
generally  it  takes  so  long  for  the  parasites 
to  reach  the  salivary  glands  that  most 
transmission,   in  this  species  at  least,  is 
by  the  adults. 

Regendanz  (1936)  found  that  the  devel- 
opment of  Babesia  bigeniiiia  from  cattle  in 
the  intestinal  wall  of  Boophilus  microplus 


288 


THE  PIROPL«iSM.\SIDA 


corresponded  completely  with  that  of  B. 
canis  in  Derniacentor  reticulaliis.     After 
numerous  binary  fissions,  the  protozoa 
turn  into  the  motile,  vermiform  stage  and 
enter  the  developing  eggs  of  the  female 
tick,  where  development  continues.     He 
found  no  evidence  of  sexual  stages. 

Muratov  and  Kheisin  (1959)  described 
a  similar  process  for  B.  bigonina  in 
Boophilus  calcaralus,   except  that  they 
said  that  schizogony  occurs.    They  studied 
only  the  stages  in  the  females  and  their 
eggs.    On  the  day  after  the  tick  drops  from 
its  host,  the  protozoa  begin  to  reproduce 
in  its  intestine  by  binary  fission  or  by 
schizogony,  producing  club-shaped  forms 
which  penetrate  into  the  epithelial  cells  of 
the  intestine.    Here  they  develop  and  un- 
dergo atypical  multiple  fission,  character- 
ized by  asynchronous  segmentation,  into 
amoeboid  or  round  agamonts.    These  be- 
come club-  or  cigar-shaped,   penetrate 
other  intestinal  cells  and  repeat  the  asex- 
ual cycle.    The  dividing  stages  in  the  intes- 
tinal cells  are  up  to  30  to  45 ji  in  diameter 
and  produce  about  250  daughter  parasites. 

Some  of  the  club-shaped  stages  enter 
the  body  cavity  and  divide  further.     They 
penetrate  all  the  organs  of  the  female, 
including  the  ovary,  and  continue  to  divide. 
In  the  ovary  they  enter  the  eggs  and  divide 
by  binary  or  multiple  fission  just  as  in  the 
intestine,   producing  round  or  amoeboid 
agamonts  which  turn  into  club-shaped 
stages.     Their  number  increases  as  the 
eggs  develop,  and  they  are  distributed 
thruout  the  organs  of  the  developing  larvae. 
Muratov  and  Kheisin  found  no  evidence  of 
copulation  or  sexual  reproduction. 

Polyanskii  and  Kheisin  (1959)  found 
essentially  the  same  pattern  for  B.  bovis 
in  Ixodes  ricinus.  They  said  that  it  re- 
produces by  binary  fission  or  schizogony 
in  the  tissues  of  the  tick  and  in  the  eggs 
of  infected  females,  and  found  no  stages 
of  sexual  reproduction  or  sporogony. 

Quite  a  different  process  was  des- 
cribed by  Dennis  (1932)  for  B.   bigemina 
in  Boophilus  annulatus .    According  to  him, 
when  a  female  tick  ingests  blood,   most  of 
the  parasites  in  the  blood  are  destroyed, 
but  some  of  them  turn  into  vermiform  bod- 


ies about  6|i  long  which  he  considered  to  be 
gametes  and  which  he  called  isogametes 
because  they  all  look  alike.    They  move 
actively  by  bending  or  gliding.     Two  of  them 
unite  to  form  a  motile,  club-shaped  zygote 
or  ookinete  7  to  12/i  long.     The  ookinetes 
pass  thru  the  intestinal  wall,   enter  the 
ovaries  and  then  the  eggs.    Here  they  round 
up  to  form  sporonts  7.  5  to  12)i  in  diameter. 
The  sporonts  grow,  and  then  divide  by  mul- 
tiple fission  into  4  to  32  amoeboid  sporo- 
blasts.    The  nuclei  of  the  sporoblasts  divide 
repeatedly,  forming  small,  multinucleate, 
amoeboid  sporokinetes  which  are  distribu- 
ted thruout  the  tissues  of  the  developing  tick 
embryo.     The  sporokinetes  vary  in  shape, 
being  round,  elongate,  club-  or  ribbon- 
shaped,   and  may  be  as  much  as  15fi  long. 
They  contain  a  varying  number  of  granular 
nuclei  0.4jll  in  diameter.    In  the  course  of 
the  embryonal  development  of  the  tick,  the 
sporokinetes  multiply,  probably  by  plasmo- 
tomy.    All  the  tissues  of  the  tick  may  be 
invaded,  and  sometimes  the  cytoplasm  of 
a  host  cell  is  almost  entirely  supplanted  by 
the  parasites,  particularly  in  the  salivary 
glands.    Toward  the  end  of  the  tick's  de- 
velopment, some  sporokinetes  produce 
sporozoites,  which  are  the  infectious  stage. 
Others  produce  them  only  after  the  larva 
has  hatched.     The  sporozoites  resemble 
minature  trophozoites;  they  are  piriform 
and  have  a  blepharoplast.    They  are  par- 
ticularly numerous  in  the  salivary  glands, 
in  the  coelenchymatous  tissue  at  the  base 
of  the  legs  and  around  the  viscera.    They 
are  inoculated  into  the  blood  with  the  sa- 
liva when  the  tick  feeds. 

Petrov  (1941)  described  a  similar 
process  for  B.  bovis    in  Ixodes  ricinus. 
According  to  him,  the  isogametes  fuse  in 
the  tick's  intestine  to  form  an  ookinete 
which  passes  thru  the  intestinal  wall  and 
enters  a  developing  ovum.     Here  it  rounds 
up,  forms  sporoblasts,  and  these  in  turn 
form  sporozoites  which  pass  to  the  sali- 
vary glands.    The  larvae,  nymphs  and 
adults  of  the  succeeding  generation  can  all 
transmit  the  parasite. 

It  should  be  said  that  Reichenow  (1953) 
considered  some  of  the  stages  described 
by  Dennis  to  be  normal,   intracellular  sym- 
bionts  (cf.   Buchner,   1953;  Koch,   1956) 
rather  than  Babesia. 


THE   PIROPLASMASIDA 


289 


In  the  life  cycles  described  above, 
the  adult  tick  picks  up  the  infection,  but 
does  not  transmit  it.     This  is  done  by  the 
next  generation.    Babesia  can  also  be 
transmitted  by  different  stages  in  the 
same  generation;  it  can  be  picked  up  by  a 
larval  tick  and  transmitted  by  the  nymph, 
or  it  can  be  picked  up  by  the  nymph  and 
transmitted  by  the  adult.    The  occurrence 
of  this  stage-to-stage  transmission  de- 
pends upon  both  the  species  of  Babesia  and 
the  species  of  tick.     Neitz  (1956)  has  as- 
sembled information  on  this  subject,  and 
it  is  given  below  in  the  discussion  of  the 
individual  species. 

The  life  cycle  in  the  tick  in  stage-to- 
stage  transmission  was  studied  carefully 
by  Shortt  (1936)  for  B.   vogeli  {B.   canis) 
of  the  dog  in  Rliipiceplialus  sanguineus  in 
India.     He  saw  no  evidence  of  sexual  stages. 
After  the  nymph  has  taken  a  blood  meal, 
the  parasites  do  not  multiply  in  the  gut 
epithelium,  but  in  the  phagocytes  next  to 
the  hypodermis  in  the  body  cavity.     Here 
they  reproduce  by  multiple  fission  to  form 
what  Shortt  called  pseudocysts- -clumps  of 
up  to  200  organisms  contained  within  the 
envelope  of  the  parasitized  host  cell. 
These  are  fully  developed  about  7  days 
after  the  nymph  has  left  its  host.     They 
are  14  to  35 )i  in  diameter.     The  stages 
within  these  pseudocysts  are  at  first  more 
or  less  spherical  and  1 .  7  to  3.  3  fi  in  di- 
ameter.    They  become  club-shaped  in  4  to 
8  more  days,  at  which  time  they  measure 
about  9  by  2|i  .     The  club-shaped  stages 
then  break  out  of  the  host  cell  and  migrate 
to  the  muscles  and  muscle-sheaths.    They 
penetrate  the  cells,   round  up,  and  divide 
by  repeated  binary  fissions  to  form  a 
large  number  of  relatively  small,  ovoid 
or  slightly  elongate  parasites  about  1.2(i 
long.     This  stage  is  reached  about  20  days 
or  more  after  the  nymph  has  fed.     This 
phase  of  the  life  cycle  corresponds  to  that 
which  takes  place  in  the  eggs  of  the  adult. 

The  muscles  remain  unchanged  during 
metamorphosis.    When  the  adults  begin  to 
feed  on  a  dog,  the  parasites  migrate  to  the 
salivary  glands  and  enter  their  cells.    De- 
velopment then  continues  as  described  by 
Reichenow  and  Regendanz  (1933) for  B. 
canis.    The  parasites  multiply  by  repeated 


binary  fissions  to  form  large  numbers  of 
spherical  or  ovoid  infective  stages  about 
1.9ji  or  less  in  diameter. 

Pathogenesis:     Babesiosis  is  a  highly 
pathogenic  disease  in  most  hosts.    It  is 
unusual  in  that  the  death  rate  is  much 
higher  in  adults  than  in  young  animals. 

The  various  species  of  Babesia  cause 
a  similar  disease  in  different  hosts.    In 
most  cases  there  are  fever,   malaise  and 
listlessness.    Affected  animals  do  not  eat, 
or  eat  little.    There  is  severe  anemia, 
and  destruction  of  the  erythrocytes  is  ac- 
companied by  hemoglobinuria.     The  mu- 
cous membranes  become  pale,  and  icterus 
develops.    The  spleen  is  greatly  enlarged, 
with  soft,  dark  red  pulp  and  prominent 
splenic  corpuscles.     The  liver  is  enlarged 
and  yellowish  brown.    The  lungs  may  be 
slightly  edematous.     There  may  be  diarrhea 
or  constipation,  and  the  feces  are  yellow 
except  in  very  early  or  peracute  cases. 
Affected  animals  lose  condition,  become 
emaciated,  and  often  die. 

The  signs  of  babesiosis  may  vary 
markedly  from  this  typical  picture,  how- 
ever.   As  Malherbe  (1956)  said,   "Anybody 
with  extensive  experience  of  these  dis- 
eases. .  .is  forcibly  struck  by  the  deviate 
and  protean  manifestations  of  the  disease 
picture  as  it  is  encountered  from  time  to 
time.     There  is  almost  no  guise  under 
which  the  disease  does  not  masquerade  at 
some  time  or  another,  and  it  is  therefore 
no  accident  that  the  majority  of  South  Af- 
rican veterinarians  have  a  pronounced 
attachment  to  their  microscopes."    Mal- 
herbe remarked  on  the  similarity  of  the 
clinical  and  pathological  manifestations  of 
babesiosis  to  those  of  malaria,  stating 
that  "in  spite  of  the  differences  in  the  life 
cycle  of  the  parasites,  their  effect  on  the 
body  is  capable  of  exactly  similar  poten- 
tialities. " 

Death,  if  it  occurs,  is  due  to  organic 
failure  which,  in  turn,  is  due  not  only  to 
the  destruction  of  erythrocytes  with  re- 
sultant anemia,  edema  and  icterus,  but 
also  to  the  clogging  of  the  capillaries  of 
various  organs  by  parasitized  cells  and 
free  parasites  (Malherbe  and  Parkin,  1951; 


290 


THE  PIROPD^SM^SIDA 


Malherbe,   1956).    The  stasis  resulting 
from  this  sludging  (Knisely  el  al.  .   1947) 
causes  degeneration  of  the  endothelial 
cells  of  the  small  blood  vessels,  anoxia, 
accumulation  of  toxic  metabolic  products, 
capillary  fragility,  and  eventually  peri- 
vascular escape  of  erythrocytes  and  ma- 
croscopic hemorrhage.     Purpura  may 
result,  the  great  majority  of  such  cases 
in  dogs  being  due  to  babesiosis.    The 
signs  of  the  disease  depend  in  part  on  the 
location  where  the  most  serious  stasis 
takes  place.    Cerebral  babesiosis  similar 
to  cerebral  falciparum  malaria  may  occur. 
Gilles,   Maegraith  and  Andrews  (1953) 
described  liver  damage  in  B.   canis  infec- 
tions, beginning  with  early  damming  of 
the  blood  in  the  sinusoids  around  the  cen- 
tral vein,  thru  centrilobular  atrophy  and 
degeneration  of  the  hepatic  cells,  to  ne- 
crosis of  the  cells.    Kidney  damage  is 
also  present. 


ported  animals  usually  die.     The  native 
cattle  were  infected  as  calves  and  are 
premunized.     Lambs  and  puppies,   how- 
ever, are  highly  susceptible. 

There  is  no  cross-immunity  between 
the  different  species  of  Babesia. 

Treatment:     The  treatment  of  babesi- 
osis has  been  reviewed  by  Goodwin  and 
Rollo  (1955),   Carmichael  (1956)  and 
Richardson  and  Kendall  (1957),  among 
others.    There  is  an  interesting  relation- 
ship between  the  chemotherapy  of  babesi- 
osis and  that  of  trypanosomosis.     Many  of 
the  compounds  effective  against  Try/jan- 
osoDia  are  also  effective  against  Babesia. 
This  may  perhaps  indicate  a  phylogenetic 
relationship,  but  I  hasten  to  warn  that  a 
similar  line  of  reasoning  was  once  used  to 
suggest  a  relationship  between  the  trypano- 
somes  and  the  spirochetes. 


Immunity:     Cattle  which  have  recov- 
ered from  an  attack  of  babesiosis  due  to 
B.   bigeuiiiia  remain  infected  for  life,  and 
are  immune  to  reinfection.    This  type  of 
immunity,  due  to  continuing  low-grade 
infection,  is  known  as  premunition.     Pre- 
munition  in  cattle  due  to  species  other 
than  B.   bigeniiiia,   and  in  sheep,   swine 
and  dogs,  lasts  up  to  2  years.     Premu- 
nized animals  do  not  show  signs  of  dis- 
ease except  under  stress  of  one  sort  or 
another.     For  instance,  an  attack  of  foot 
and  mouth  disease  may  reactivate  babesi- 
osis in  cattle,  and  distemper  may  do  the 
same  in  dogs. 

The  spleen  plays  an  important  role 
in  maintaining  immunity,  and  it  is  a  com- 
mon observation  that  splenectomy  is  often 
followed  by  a  severe  or  fatal  relapse  in 
premunized  animals.    In  addition,   sple- 
nectomized  animals  are  much  more  sus- 
ceptible to  infection  with  Babesia  and 
much  more  seriously  affected  than  nor- 
mal ones. 

Calves,  foals,  young  pigs  and  kids 
are  much  less  seriously  affected  by 
babesiosis  than  are  adult  animals.    This 
is  the  reason  that  cattle  can  often  be 
raised  in  highly  endemic  areas  without 
being  seriously  affected,  whereas  im- 


Nuttall  and  Hadwen  (1909)  introduced 
the  first  effective  drugs,  the  azo-naphtha- 
lene  dyes,  trypan  red  and  trypan  blue. 
The  latter  is  still  used  in  some  areas.    It 
is  the  sodium  salt  of  ditolyl  diazo-bis-8- 
amino-l-naphthol-3,  6-disulfonic  acid.    It 
must  be  given  intravenously,  since  absces- 
sation  and  sloughing  follow  subcutaneous 
injection.    It  stains  the  tissues  blue-green 
for  several  months  after  injection.    It  does 
not  eliminate  all  parasites,   so  that  recov- 
ered animals  are  premunized. 

The  acridine  derivative,  acriflavine 
(trypaflavine,  gonacrine,  flavin,  euflavin) 
was  introduced  by  Stephan  and  Esquibel 
(1929).    It  is  a  mixture  of  2,8-diamino- 
10-methylacridinium  chloride  with  a  small 
amount  of  2,  8-diaminoacridinium  chloride. 
It,  too,  is  still  being  used,  especially 
against  B.  eqiii  in  South  Africa  and  in 
cattle  in  North  Africa.    It  does  not  elim- 
inate all  parasites,   and  recovered, 
treated  animals  are  premunized. 

The  quinoline  derivative,  acaprin 
(Acapron,  Pirevan,  Babesan,  Piroparv, 
Zothelone,  Piroplasmin)  was  introduced 
by  Kikuth  (1935)  and  also  bv  Carmichael 
(1935).  It  is  6,6'-di-(N-methylquinolyl) 
urea  dimethosulfate„  It  is  administered 
subcutaneously.    In  large  doses  it  elim- 


THE  PIROPLASMASIDA 


291 


inates  all  parasites,  but  in  small  ones  it 
leaves  some  so  that  recovered  animals 
are  premunized  (Kikuth,   1938).     It  affects 
the  parasympathetic  nervous  system,  and 
may  cause  alarming  reactions,   including 
salivation,  vasodilation,   sweating,   copious 
urination,  diarrhea,   panting,  a  drop  in 
blood  pressure  and  even  collapse  and 
death.     Adrenaline  and  calcium  gluconate 
can  be  given  as  antidotes.     To  avoid  such 
reactions,  the  drug  is  often  given  in  2  or 
3  divided  doses  a  few  hours  apart.    Dogs 
are  much  more  sensitive  than  cattle. 
Animals  showing  reactions  usually  recover 
rather  quickly.    Despite  these  reactions, 
acaprin  is  still  one  of  the  most  widely  used 
drugs  for  treating  babesiosis  in  all  animals 
thruout  the  world. 

Lourie  and  York  (1939)  found  that  a 
number  of  aromatic  diamidines  were  ef- 
fective against  Babesia.    Adler  and 
Tchernomoretz  (1940)  found  that  stilbam- 
idine  (4,  4'-diamidinostilbene)  was  effec- 
tive against  5.   bigemina,  and  fi.   ovis, 
and  it  is  also  used  for  B.  canis  and  B. 
caballi  (Daubney  and  Hudson,   1941). 
Propamidine  (4,  4'-diamidino-l,  3-diphen- 
oxypropane)  has  been  used  against  B. 
caiiis  in  dogs  (Carmichael  and  Fiennes, 
1941).     Pentamidine  (lomidine;  4,4'- 
diamidino-1,  5-diphenoxypentane)  is  used 
quite  widely,  especially  in  North  Africa, 
for  babesiosis  in  all  animals.     Phenami- 
dine  (4,  4'-diamidinodiphenyl  ether)  was 
introduced  by  Carmichael  (1942)  for  canine 
babesiosis  and  is  now  used  in  cattle  and 
other  animals  as  well.    Berenil  (4,4'- 
diamidino  diazoaminobenzene  diaceturate) 
was  introduced  by  Bauer  (1955),  and  is 
effective  against  babesiosis  in  cattle,  dogs 
and  other  animals.    Amicarbalide  (M  &  B 
5062A;  3,  3'-diamidinocarbanilide  di- 
isethionate)  was  introduced  by  Ashley, 
Berg  and  Lucas  (1960).     Preliminary 
studies  indicate  that  it  is  effective  against 
babesiosis  in  cattle  (Beveridge,   Thwaite 
and  Shepherd,   1960;  Lucas,   1960). 

The  diamidines  are  injected  subcutan- 
eously  or  intramuscularly,  depending  upon 
the  compound.     Many  of  them  tend  to  cause 
a  fall  in  blood  pressure,  but  it  soon  re- 
turns to  normal.     Subcutaneous  injection 
of  concentrated  solutions  may  cause  ir- 


ritation.   Transitory  swelling  of  the  face 
and  lips  which  is  anaphylactic  in  nature 
sometimes  occurs  with  phenamidine. 

Prevention  and  Control:     Since  babesi- 
osis is  transmitted  by  ticks,   prevention 
and  control  depend  primarily  on  tick  elim- 
ination.    This  can  be  done  by  regular  dip- 
ping, which  should  be  carried  out  on  an 
area  basis  for  livestock,  at  least.    Dogs 
and  riding  horses  can  be  treated  individ- 
ually. 

Artificial  premunization  of  young  an- 
imals has  been  practiced  with  a  good  deal 
of  success,  especially  in  North  Africa 
(Sergent  et  al.  ,   1945).     A  mild  strain  of 
the  organism  is  ordinarily  used.     This 
practice  is  not  necessary  if  the  animals 
are  raised  in  an  endemic  area  where  they 
will  all  become  naturally  infected  at  an 
early  age,  but  it  is  worthwhile  in  areas 
where  only  a  certain  proportion  of  the 
animals  become  infected  or  for  animals 
which  are  destined  to  be  shipped  to  endemic 
areas  later  on. 


Fig.  34.      Bovine  species  of  Babesia  in  eryth- 
rocytes.    A.  ,   B.  ,   C.  ,  D.    Babesia 
bigemina.     E.  ,   F.  ,  G.    Babesia 
bonis.     H.  ,  I.    Babesia  divergens. 
X  2800.     (A.,   B.  ,  C,  D.   after 
Nuttall  and  Graham -Smith,   1908 
in  Pavasitology .    published  by  Cam- 
bridge Univ.   Press;  E. ,   F. ,  G., 
H.  ,  I.  after  Davies,  Joyner  and 
Kendall,   1958  in  Annals  of  Trop- 
ical Medicine  and  Hygiene,    pub- 
lished by  Liverpool  School  of 
Tropical  Medicine). 


292 


THE  PIRO°LASM\SlDA 


BABESIA   BIGEMISA 

(SMITH  AND   KILBORNE,    1893) 

Synonyms:     Pyrosoma  bigeminum, 
Apiosoma  bige»iinu»i ,   Piroplasma 
bigeni ilium,  Piroplasnia  auslrale,  Babesia 
hudsonius  bovis. 

Disease:     Bovine  babesiosis,  piro- 
plasmosis,  redwater,  Texas  fever. 

Hosts:     Ox,   zebu,  water  buffalo, 
deer  (Mazania  ainericana  reperlicia) 
(syn.,Ay.  sarlprii  reperlicia),  white- 
tailed  deer  (Odocoelius  virginianus  chir- 
iquensis  (syn. ,   O.  chiriquensis). 

Location:     Erythrocytes. 

Geographic  Distribution:     Central 
America,  South  America,   Europe,   North, 
Central  and  South  Africa,  Australia,  for- 
merly North  America  (U.S. ). 

Prevalence:     This  species  causes  one 
of  the  most  important  diseases  of  cattle 
in  the  tropics  and  subtropics. 

Morphology:     The  trophozoites  in  the 
erythrocytes  are  piriform,   round,  oval  or 
irregularly  shaped.    The  piriform  tropho- 
zoites occur  characteristically  in  pairs, 
a  feature  which  gives  the  species  its  name. 
B.  bigemina  is  relatively  large.    The 
round  forms  are  2  to  3 /i  in  diameter  and 
the  elongate  ones  4  to  Sjn  long. 

Life  Cycle:     This  has  been  described 
above  (p.  287).    The  tick  vectors  are 
Boopliilus  aiumlalus  in  North  America, 
B.  microplus  in  South  and  Central  Amer- 
ica, B.  auslralis  in  Australia,    B.  cal- 
carahis  in  North  Africa  and  the  USSR,   B. 
decoloralus  in  South  Africa,  Hae»iapliy- 
salis  punctata  in  Europe,  Rhipicephaliis 
appendiculatus  and  R.  everlsi  in  South 
Africa,  and  R.  bursa  in  North  Africa. 
Transmission  takes  place  thru  the  egg  in 
all  species;  stage-to-stage  transmission 
also  takes  place  in  Haeniapliysalis  and 
Rhipiceplmlus. 

Intrauterine  transmission  may  also 
take  place  (Enigk,  1942). 


Pathogenesis:     B.   bigemina  is  highly 
pathogenic  for  adult  animals  but  much  less 
so  for  calves.    The  incubation  period  is  8 
to  15  days  or  less.    The  first  sign  of  dis- 
ease is  a  rise  in  temperature  to  106  to 
108°  F.    The  temperature  persists  for  a 
week  or  more.     Affected  animals  are  dull, 
listless,  fail  to  eat  and  stop  ruminating. 
The  feces  are  yellowish  brown.    Severe 
anemia  is  caused  by  the  invasion  and  des- 
truction of  the  erythrocytes;  up  to  75' (  of 
them  may  be  destroyed.     Hemoglobinuria 
is  ordinarily  present,  but  may  be  absent. 
Affected  animals  become  thin,  emaciated 
and  icteric.     In  chronic  cases  the  temper- 
ature is  not  very  high  and  there  is  usually 
no  hemoglobinuria,  but  diarrhea  or  con- 
stipation with  hard,   yellowish  feces  is 
present. 

The  initial  febrile  response  is  asso- 
ciated with  the  appearance  of  parasites  in 
the  peripheral  blood. 

Death  may  occur  in  4  to  8  days  in 
acute  cases.    The  mortality  is  as  high  as 
50  to  90%  in  untreated  cases,  but  treat- 
ment reduces  it  markedly.     Calves  less 
than  a  year  old  are  seldom  seriously  af- 
fected. 

Chronically  affected  animals  lose  con- 
dition quite  rapidly  and  remain  thin,  weak 
and  emaciated  for  weeks  before  finally 
recovering. 

The  principal  lesions  are  splenomegaly 
with  soft,  dark  red  splenic  pulp  and  prom- 
inent splenic  corpuscles.     The  liver  is  en- 
larged and  yellowish  brown.     The  gall 
bladder  is  distended  with  thick,  dark  bile. 
The  mucosa  of  the  abomasum  and  intestine 
is  edematous  and  icteric,  with  patches  of 
hemorrhage.     The  subcutaneous,  subser- 
ous and  intramuscular  connective  tissues 
are  edematous  and  icteric,  and  the  fat  is 
yellow  and  gelatinous.     The  blood  is  thin 
and  watery,  the  plasma  may  be  tinged  with 
red,  and  the  urine  in  the  bladder  is  usually 
red. 

Immunity:     As  mentioned  in  the  gen- 
eral discussion  of  immunity,   recovered 
cattle  are  premunized,  and  premunition 
due  to  latent  infection  persists  for  life. 


THE  PIROPLASM.'\SIDA 


293 


Diagnosis:      Fever  associated  with 
hemoglobinuria,  anemia  and  icterus  is 
suggestive  of  babesiosis.    The  diagnosis 
can  be  confirmed  by  finding  B.  bigemina 
by  microscopic  examination  of  stained 
blood  smears. 

Treatment:     Trypan  blue  was  the 
first  effective  drug  used  against  babesio- 
sis, and  is  still  used  in  some  areas.    It 
is  administered  intravenously  in  1  to  2% 
aqueous  solution;  up  to  200  ml  may  be 
given  at  a  time.     Two  treatments  on  suc- 
cessive days  may  be  needed,  but  1  is  often 
enough.     The  tissues  turn  blue,  and  re- 
covery is  relatively  slow. 

Acriflavine  (trypaflavine)  is  also  used 
to  some  extent,   50  to  100  ml  of  a  1%  aq- 
ueous solution  being  given  intravenously. 
Neither  acriflavine  nor  trypan  blue  elim- 
inates all  parasites,  and  recovered  an- 
imals remain  premunized. 

A  number  of  aromatic  diamidines  are 
effective  against  B.   bigemina.    Stilbami- 
dine  was  found  by  Adler  and  Tchernomoretz 
(1940)  to  be  effective  in  calves  when  injec- 
ted subcutaneously  at  a  dosage  of  2  to  4 
mg  per  kg.     Phenamidine  is  used  quite 
widely.     Randall  and  Laws  (1947)  gave  15 
mg  per  kg  phenamidine  isethionate  sub- 
cutaneously; the  drug  was  well  tolerated 
in  doses  up  to  22.  5  mg  per  kg.     Berenil  is 
the  most  recent  of  these  drugs  to  be  intro- 
duced (Bauer,   1955).    It  is  injected  intra- 
muscularly at  a  dosage  rate  of  1  to  3  mg 
per  kg  body  weight. 

The  quinoline  derivative,  acaprin,  is 
also  effective.    The  dosage  for  cattle  is 
0. 02  ml  per  kg  of  a  5%  aqueous  solution 
subcutaneously. 

The  diamidines  and  acaprin  eliminate 
all  the  parasites,  so  that  treated  animals 
are  no  longer  premunized. 

Prevention  and  Control:     Since  B. 
bigemina  is  transmitted  only  by  ticks,  in- 
fection can  be  prevented  by  tick  control. 
This  can  be  done  by  dipping  the  cattle  reg- 
ularly.   This  is  the  way  in  which  Texas  fe- 
ver was  eliminated  from  the  United  States. 


Another  measure  which  has  been  used 
is  artificial  premunization  of  young  ani- 
mals with  a  mild  strain,  especially  before 
shipping  them  to  endemic  areas. 

Remarks:     Spindler  et  al.    (1958) 
found  a  Babesia  which  resembled  B.  bi- 
gemina in  a  white-tailed  deer  {Odocoilens 
virginianiis  coiiesi)  in  New  Mexico.    The 
animal  was  weak  and  had  lesions  charac- 
teristic of  babesiosis.    Blood  smears  made 
from  several  other  white-tailed  deer,   mule 
deer,  cattle  and  a  few  antelope  from  the 
same  region  were  negative,  but  this  find- 
ing raises  a  question  as  to  the  existence  of 
a  possible  reservoir  of  Babesia  in  wild 
deer  in  the  southwestern  states. 


BABESIA  BOVIS 
(BABES,   1888) 
STARCOVICI,   1893 

Synonyms:     Haematococcus  bouis, 
Piroplasma  bovis,  Babesiella  bovis, 
?  Babesiella  berbera. 

Disease:     Bovine  babesiosis,  piro- 
plasmosis,   redwater. 

Hosts:     Cattle,   roe  deer,   stag. 

Location:     Erythrocytes. 

Geographic  Distribution:     Europe, 
USSR,  Africa. 

Prevalence:     This  species  is  the  most 
important  cause  of  European  babesiosis. 
It  is  common  in  many  regions,  but  infor- 
mation on  its  true  prevalence  must  await 
a  decision  as  to  whether  B.  berbera  is  a 
synonym  and  must  also  await  new  surveys 
in  the  light  of  the  recent  recognition  that 
B.  divergens    is  a  separate  species  (see 
below). 

Morphology:     The  trophozoites  in  the 
erythrocytes  are  piriform,   round  or  ir- 
regular.    Vacuolated  "signet-ring"  forms 
are  especially  common.     B.  bovis  is  a 
small  form,  with  trophozoites  measuring 
about  2.  4  by  1.  5ji  (Davies,  Joyner  and 
Kendall,  1958). 


294 


THE  PIROPLASMASIDA 


Life  Cycle:     The  life  cycle  was  des- 
cribed above  (p.  287).     The  tick  vectors 
are  Ixodes  persiilcalus  in  the  USSR  and, 
according  to  Simitch,   Petrovitch  and 
Rakovec  (1955),  Buophilus  calcaratiis  and 
RliilJiceplialus  bursa  in  Europe.     The  tick 
ordinarily  considered  the  vector  in  Europe 
is  Ixodes  riciiiiis,  but  the  species  it  ac- 
tually transmits  may  be  B.  divergens 
(see  below).    Transmission  takes  place 
thru  the  egg  in  all  ticks,  and  from  stage 
to  stage  in  /.  ricinus. 

Intra-uterine  transmission  has  also 
been  reported  (Neitz,  1956). 

Pathogenesis:     The  disease  caused 
by  B.  bovls  is  similar  to  that  caused  by 
B.   bigemuia.  but  is  not  generally  as  se- 
vere.    The  incubation  period  is  4  to  10 
days,  and  the  first  sign  is  a  temperature 
of  104  to  106-  F  which  usually  lasts  2  to 
3  days.     Hemoglobinuria,  anemia,   icterus, 
diarrhea  and  rapid  heart  beat  are  present, 
and  affected  animals  may  die. 

Immunity:      Same  as  for  B.  bigemina, 
except  that  premunition  does  not  last  more 
than  about  2  years.     There  is  no  cross- 
immunity  between  B.  bigeviiim  and  B. 
bovis. 

Diagnosis:     Babesiosis  due  to  B. 
bovis  can  be  diagnosed  on  the  basis  of  the 
history,  clinical  signs  and  presence  of 
ticks  together  with  identification  of  the 
parasites  in  stained  blood  smears.     How- 
ever, they  are  easily  found  only  during 
the  febrile  period. 


B.  bovis  was  thought  to  be  primarily 
European.     However,  Simitch  and  Nev- 
enitch  (1953)  and  Simitch,   Petrovitch  and 
Rakovec  (1955)  found  a  Babesia  in  Yugo- 
slavia just  across  the  Danube  River  from 
the  area  where  Babes  (1888)  has  described 
B.   bovis  which  corresponded  completely 
with  B.  berbera.     The  latter  authors  also 
found  another,   morphologically  different 
species  in  Yugoslavia  which  corresponded 
completely  withi?.  divergens.      This  latter 
species  had  originally  been  described  in 
England  by  M'Fadyean  and  Stockman  (1911), 
and  had  generally  been  considered  a  syn- 
onym of  B.  bovis.     Simitch,   Petrovitch 
and  Rakovec  (1955)  concluded  that  B.  ber- 
bera is  a  synonym  of  B.  bovis  and  that  it 
occurs  in  North  Africa  and  southern  Europe 
in  association  with  Boopliiliis  calcaratus 
and  Rhipicephahis  bursa.      They  also  con- 
cluded that  the  species  which  occurs  in 
western  and  central  Europe  in  association 
with  Ixodes  ricinus  is  not  B.  bovis,   but 
B.  divergens. 

Davies,  Joyner  and  Kendall  (1958) 
compared  a  British  strain  of  Babesia  with 
a  strain  of  B.  bovis  sent  to  them  from 
Yugoslavia,  and  concluded  that  they  were 
indeed  morphologically  different  and  that 
the  correct  name  for  the  British  strain 
was  B.  divergens. 

Sergent,  Donatien  and  Parrot  (1954) 
felt  that  final  proof  as  to  the  identity  of 
B.  bovis  and  B.  berbera  must  await  cross- 
immunity  experiments.    I  am  retaining 
both  names  for  the  present,  with  the  strong 
suspicion  that  they  are  synonymous. 


Treatment:     In  contrast  to  B.  bigem- 
ina,  B.  bovis  does  not  respond  to  trypan 
blue.     Acaprin,  acriflavine,   phenamidine 
and  berenil  are  effective,  however;  the 
same  dosages  are  used  as  against  B. 
bigemina. 

Prevention  and  Control:     Same  as  for 
B.   bigemina. 


BABESIA   BERBERA 
(SERGENT,  DONATIEN,   PARROT, 
LESTOQUARD,    PLANTUREUX  AND 
ROUGEBIEF,   1924) 

Synonyms:     Babes iella  berbera, 
Francaiella  caucasica,    ?  Francaiella 
occidentalis. 


Remarks:     Recent  work  has  reopened 
the  question  of  synonymy  in  this  and  re- 
lated species.    B.   berbera  has  generally 
been  considered  a  separate  species  from 
B.  bovis.     It  was  thought  to  be  the  common 
small  Babesia  of  North  Africa,  whereas 


Hosts:     Cattle. 

Location:     Erythrocytes. 

Geographic  Distribution:     North  Af- 
rica,  USSR,   probably  southern  Europe. 


THE  PIROPLASMASIDA 


29S 


Morphology:     Same  as  B.   bovis. 

Life  Cycle:     Same  as  B.  bovis.      The 
vectors  in  North  Africa  are  Boophilus 
calcaratus  and  Rliipicephalus  bursa. 
Transmission  occurs  thru  the  egg  in  the 
former  and  stage-to-stage  in  the  latter. 
The  vector  in  the  USSR  is  Ixodes  ricinus. 

Pathogenesis:     Same  as  B.  bovis. 

Treatment:     Same  as  B.  bovis. 

Remarks:     As  mentioned  above,  B. 
berbera  is  probably  a  synonym  of  B.  bovis. 


BABESIA  DIVERGENS 

(M'FADYEAN  AND  STOCKMAN,    1911) 

Synonym:     Piroplasma  divergens. 

Hosts:     Cattle,  rarely  man. 

Location:     Erythrocytes. 

Geographic  Distribution:     Western 
and  central  Europe. 

Prevalence:     This  is  probably  the 
commonest  if  not  the  only  species  of 
Babesia  in  western  and  central  Europe, 
but  further  investigation  is  needed  to  con- 
firm this  statement.    B.  divergens  is  now 
definitely  known  to  occur  in  Yugoslavia, 
Austria  and  England  (Simitch,   Petrovitch 
and  Rakovec,  1955;  Davies,  Joyner  and 
Kendall,   1958). 

Morphology:     This  species  is  smaller 
than  B.  bovis.     The  trophozoites  usually 
occur  as  paired,  club-shaped  organisms 
about  1.  5  by  0.  4  jj. ;  the  angle  between  the 
members  of  the  pair  is  relatively  large, 
so  that  they  diverge  more  from  each  other 
than  the  trophozoites  of  B.  bovis;  in  addi- 
tion, they  tend  to  lie  along  the  circumfer- 
ence of  the  host  erythrocyte  (the  so-called 
accole'  position).    Other  trophozoites  are 
stouter  and  piriform  (about  2  by  1  |u ),   cir- 
cular (about  1.5)M  in  diameter),  or  vacu- 
olated and  circular  (up  to  2|u  in  diameter) 
(Davies,  Joyner  and  Kendall,   1958). 


Life  Cycle:     Same  as  that  of  B. 
The  vector  tick  is  Ixodes  ricinus. 


bovis. 


Pathogenesis:     Same  as  for  B.  bovis. 

Immunity:     Same  as  for  B.  bovis. 

Diagnosis:     Same  as  for  B.  bovis. 

Treatment:     Same  as  for  B.  bovis. 
Amicarbalide  was  found  by  Beveridge, 
Thwaite  and  Shepherd  (1960)  and  Lucas 
(1960)  to  be  effective  against  5.  divergens. 
The  dosage  is  about  5  to  20  mg  per  kg 
subcutaneously  or  intramuscularly. 

Remarks:     Skrabalo  and  Deanovic 
(1957)  described  a  fatal  human  case  of 
babesiosis  accompanied  by  blackwater  due 
to  B.  divergens  in  Yugoslavia.     The  pa- 
tient had  had  a  splenectomy  11  years  be- 
fore and  lived  on  a  tick-infested  farm 
where  the  cattle  had  babesiosis. 

Garnham  and  Bray  (1959)  infected  2 
splenectomized  chimpanzees  and  a  splen- 
ectomized  rhesus  monkey  with  the  British 
strain  of  B.  divergens  described  by  Davies, 
Joyner  and  Kendall  (1958),  but  were  unable 
to  infect  2  splenectomized  rabbits.    The 
parasites  in  the  rhesus  monkey  had  the 
typical  accole'  form,  but  those  in  the 
chimpanzees  did  not.    Garnham  and  Bray 
suggested  that  latent  babesiosis  might 
exist  in  man  on  a  large  scale  in  rural  pop- 
ulations in  infected  regions. 


BABESIA  ARGENTINA 
(LIGNIERES,   1903) 

Synonyms:     Piroplasma  argentinum, 
Fra)icaiella  argentina. 

Hosts:     Cattle. 

Location:     Erythrocytes. 

Geographic  Distribution:     South 
America,   Central  America,   Australia. 

Morphology:     The  trophozoites  re- 
semble those  of  B.  bovis.     They  are 
piriform,  about  2.0  by  1.  5jx,  and  usually 
lie  in  the  center  of  the  host  erythrocyte. 

Life  Cycle:     Similar  to  that  of  B. 
bovis.     The  vector  in  South  America  is 
Boophilus  microplus  and  that  in  Australia 


296 


THE  PIROPLASM.\SIDA 


is  B.  auslralis.     Transmission  takes 
place  thru  the  egg. 

Pathogenesis:     In  Australia,    IJ. 
argenllna  is  more  pathogenic  than  B. 
bigeiiihia  (Pierce,   1956).     Daly  and  Hall 
(1955)  found  that  the  mortality  in  Aus- 
tralian cattle  inoculated  with  B.  bigenuna 
was  30%  and  that  of  cattle  inoculated  with 
B.  argeiiliiia  was  70  to  80Vo.     The  clinical 
signs,  lesions,  etc.  are  similar  in  both 
diseases. 

Immunity:      Premunition  following 
recovery  from  B.  argeiilina  infections 
lasts  less  than  2  years,  and  the  minimum 
time  at  which  cattle  regain  susceptibility 
is  5  to  6  months  (Pierce,   1956).     Cattle 
infected  with  B.  bigemina  are  resistant 
to  infection  with  B.  argentina  (Legg,  1935; 
Seddon,   1952),  but  those  infected  with  B. 
argentina  are  susceptible  to  infection  with 
B.  bigemina  (Seddon,  1952). 

Diagnosis:     Same  as  for  B.  bovis. 
The  trophozoites  can  be  found  more  easily 
in  smears  from  the  heart  or  kidney  than 
in  the  peripheral  blood. 

Treatment:     Same  as  for  B.  bovis. 

BABESIA  MAJOR 

(SERGE NT,  DONATIEN,    PARROT, 

LESTOQUARD  AND   PLANTUREUX, 

1926) 

Synonyms:     Babesiella  major,   Fran- 
caiella  colchica. 

Hosts:     Cattle, 

Location:     Erythrocytes. 

Geographic  Distribution:      Europe, 
USSR. 

Morphology:     The  trophozoites  re- 
semble those  of  B.   bovis,   but  are  larger. 
The  piriform,   paired  forms  measure 
2.  6/1  by  1.  5(i  ,  and  the  round  ones  are 
1,8/i  in  diameter.     The  parasites  lie  in 
the  center  of  the  host  erythrocyte. 

Life  Cycle:    Similar  to  that  of  B.  bovis. 
The  vector  in  the  USSR  is  Boopliilus  cal- 
caratus . 


Pathogenesis:     This  species  is  con- 
siderably less  pathogenic  than  B.  bovis. 
There  is  little  fever,   relatively  slight 
anemia,  and  experimentally  infected  ani- 
mals show  no  clear  clinical  signs  of  illness. 

Immunity:     This  species  can  be  dif- 
ferentiated from  B.  bigemina  and  B.  ber- 
bera  by  cross-immunity  studies. 

Treatment:     Same  as  for  B.  bovis. 
Trypan  blue  is  ineffective  against  B. 
major. 


BABESIA  MOTASI 
WENYON,   1926 

Synonyms:     Haematococcus  ovis  pro 
parte,    Piroplasma  ovis. 

Hosts:     Sheep,  goats. 

Location:     Erythrocytes. 

Geographic  Distribution:  Southern 
Europe,  Middle  East,  USSR,  Indochina, 
Africa,  and  other  parts  of  the  tropics. 

Morphology:     This  is  a  large  form, 
measuring  2.  5  to  4  by  about  2/1 .    The 
trophozoites  resemble  those  of  B.  bigem- 
ina and  are  usually  piriform.    They  occur 
singly  or  in  pairs;  the  angle  between  mem- 
bers of  a  pair  is  acute. 

Life  Cycle:     Similar  to  that  of  B. 
bigemina.     The  vector  in  Roumania  is 
Rhipicephaliis  bursa,   that  in  Sardinia  is 
Haemaphysalis  punctata,    and  those  in  the 
USSR  are  Dermacentor  silvarum  and 
Haeniapliysalis  otopliila.     Transmission 
occurs  both  thru  the  egg  and  stage-to- 
stage  in  R.  bursa. 

Pathogenesis:  This  species  may 
cause  either  an  acute  or  chronic  disease. 
Fever,  prostration,  marked  anemia  and 
hemoglobinuria  are  present  in  the  acute 
disease,  and  affected  animals  often  die. 
There  may  be  no  characteristic  signs  in 
the  chronic  disease. 

Immunity:     Sheep  which  are  immune 
to  B.  molasi  are  not  immune  to  B.  ovis 
and  vice  versa. 


THE  PIROPLASMOiSIDA 


297 


Diagnosis:     Same  as  for  B.   bigemina. 
The  parasites  are  abundant  in  the  peri- 
pheral blood  during  an  attack. 

Treatment:     Trypan  blue  is  effective 
against  this  species,  as  is  acaprin.     The 
latter  is  administered  subcutaneously,  0.2 
ml  per  kg  of  a  0.  5%  aqueous  solution  being 
given. 

Prevention  and  Control:     Same  as  for 
other  species  of  Babesia. 


Treatment:     Trypan  blue  is  ineffec- 
tive against  B.  avis.     Acaprin  can  be  used 
in  the  same  way  as  for  B.  motasi,    but  it  is 
not  as  effective.    Acriflavine  is  recom- 
mended, a  single  intravenous  injection  of 
0. 15  g  being  given. 


BABESIA  FOLIATA 

RAY  AND  RHAGHAVACHARI, 

Host:    Sheep. 


1941 


BABESIA   OVIS 

(BABES,   1892)STARCOVICI,   1893 

Synonyms:      Hae)iiatococcns  ovis  pro 
parte,  Piroplasnia  ovis,  Piroplasjua 
hirci,   Babesiella  ovis. 

Hosts:     Sheep,  goats. 

Location:     Erythrocytes. 

Geographic  Distribution:     Southern 
Europe,  USSR,  thruout  the  tropics  and  in 
some  subtropical  regions. 

Morphology:     This  is  a  small  species, 
about  1  to  2.  5fi  long.    Most  of  the  para- 
sites are  round,  and  they  usually  lie  in 
the  margin  of  the  host  erythrocytes.     The 
angle  between  the  paired,   piriform  tropho- 
zoites is  usually  obtuse. 

Life  Cycle:     Similar  to  that  of  B. 
bovis.     The  vectors  in  the  USSR  are 
Rhipicephahts  bursa  and  Ixodes  persul- 
catus  (Rastegaeva,  1940). 

B.  ovis  was  found  in  2  sheep  fetuses 
by  Donatien,   Lestoquard  and  Kilcher- 
Maucourt  (1934). 

Pathogenesis:     This  species  is  less 
pathogenic  than  B.  >}iotasi,   but  it  may 
cause  fever,  anemia  and  icterus.    Usually 
not  more  than  0.  6%  of  the  erythrocytes 
are  infected. 

Immunity:     There  is  no  cross-immun- 
ity between  B.  ovis  and  B.  motasi. 

Diagnosis:     Same  as  for  B.  bovis. 


Location:     Erythrocytes. 

Geographic  Distribution:     India. 

Morphology:     This  species  resembles 
B.  ovis,    but  differs  in  being  leaf-shaped 
and  in  lying  more  centrally  in  the  host 
erythrocytes. 

Life  Cycle:     The  vectors  are  unknown. 

Remarks:     Richardson  and  Kendall 
(1957)  considered  this  to  be  probably  a 
synonym  of  B.  ovis,    but  Neitz  (1956) 
accepted  it  as  a  valid  species. 


BABESIA    TAYLORI 
(SARWAR,   1935) 

Synonym:     Piroplasnia  taylori. 

Host:     Goat. 

Location:     Er3rthrocytes. 

Geographic  Distribution:     India. 

Morphology:     This  is  a  small  species, 
the  trophozoites  measuring  about  2  by    . 
1.  5)u  when  there  is  a  single  one  per  host 
cell,  down  io  l\i  or  less  in  diameter  when 
there  are  several.    The  trophozoites  are 
mostly  ovoid  or  round,   rarely  piriform. 
The  host  cell  is  enlarged.    Division  is  by 
binary  or  quadruple  fission.    Many  ery- 
throcytes contain  8  or  even  16  parasites, 
which  Sarwar  thought  were  produced  by 
multiple  fission.     The  host  erythrocj^es 
are  enlarged.    Extracellular  dividing  forms 
are  common. 


298 


THE   PIROPLASMASIDA 


Life  Cycle:     Unknown. 

Pathogenesis:     According  to  Sarwar 
(1935),  this  species  is  probably  pathogenic. 
Hemoglobinuria  is  not  produced,  however. 


BABESIA  CABALLI 
(NUTTALL,   1910) 

Synonym:     Piroplasnia  caballi. 

Hosts:     Horse;  transmissible  to  mule 
and  donkey. 

Location:     Erythrocytes. 

Geographic  Distribution:     Southern 
Europe  thru  Asia,  USSR,   North  and  South 
Africa,  Central  America. 

Morphology:     This  is  a  large  species, 
resembling  B.  bigemina.     The  tropho- 
zoites are  piriform  and  2.  5  to  4)Lt  long, 
or  round  or  oval  and  1.  5  to  3|i  in  diam- 
eter.    The  piriform  trophozoites  are 
often  found  in  pairs  at  an  acute  angle  to 
each  other. 

Life  Cycle:     Similar  to  that  of  B. 
bigemina.    The  vectors  in  Europe  and  the 
USSR  are  Deniiacentor  Diarginatiis  (syn. , 
D.   reliculalus),  D.  pictus,  D.  silvariwi, 
Hyalomma  anatolicum  (syn. ,  H.  exca- 
valuni),   H.  niarginatimi  (syn. ,   H.  de- 
trilmii),   H.   volgense,  Rliipiceplialiis 
bursa  and  R.  sanguineus.    The  vector  in 
North  Africa  is  H\'alot}U)ia  droinedarii. 
Transmission  thru  the  egg  occurs  in  D. 
marginatus,  D.  silvarum,  H.  margina- 
tum, H.  volgense,  R.  sanguineus  and  H. 
dromedarii.    Stage-to-stage  transmission 
occurs  in  D.  margiimtus,  D.  pictus,  H. 
anatolicutn,  H.  marginatum,  R.  bursa 
and  R.  sanguineus . 

B.  caballi  has  also  been  found  in 
fetuses  (Neitz,  1956). 

Pathogenesis:     The  symptomatology 
of  this  disease  varies  markedly.    The 
disease  may  be  either  acute  or  chronic; 
in  either  case  it  may  be  relatively  mild 
or  severe,  ending  in  death.    Hemoglob- 
inuria is  rare,  but  fever,  anemia  and 


icterus  are  present.    Gastro-enteritis  is 
common.     Locomotor  signs  are  usually 
present,  and  posterior  paralysis  may 
occur.     The  incubation  period  is  7  to  19 
days.    In  fatal  cases  death  occurs  a  week 
to  about  a  month  after  the  appearance  of 
symptoms. 

Immunity:     Young  animals  are  less 
susceptible  than  old  ones.    There  is  no 
cross-immunity  between  B.  caballi  and 
B.   equi. 

Diagnosis:     Because  of  the  varied 
symptomatology,  diagnosis  depends  upon 
identification  of  the  parasites  in  stained 
blood  smears.    They  are  most  numerous 
in  the  blood  during  the  first  febrile  attack. 

Treatment:     Trypan  blue  is  quite  ef- 
fective against  B.   caballi,   but  acaprin  and 
acriflavine  are  better.     Trypan  blue  is 
given  intravenously,   50  to  75  ml  of  a  1% 
aqueous  solution  being  injected.    Acaprin 
is  given  subcutaneously,   1.2  ml  of  a  5% 
solution  being  injected  per  100  kg.    Acri- 
flavine is  injected  intravenously,  20  ml  of 
a  5%  solution  being  given. 

Prevention  and  Control:     Same  as  for 
B.   bigemina. 


BABESIA  EQUI 
(LAVERAN,   1901) 

Synonyms:     Piroplasma  equi,  Nut- 
tallia  equi,  Nuttallia  asini,    ?  Nuttallia 
f)iinor. 

Hosts:     Horse,  mule,  donkey,  Bur- 
chell's  zebra  (Equus  burchelli). 

Location:     Erythrocytes. 

Geographic  Distribution:     Europe, 
USSR,  Central  Asia,   North  and  South 
Africa,  India,  South  America.     This  spe- 
cies is  more  widely  distributed  than  B. 
caballi. 


Morphology: 
tively  small 


This  species  is  rela- 
5eing  2\x  long.     The  tropho- 


zoites in  the  erythrocytes  are  rounded, 
amoeboid  or  most  often  pear-shaped. 


THE   PIROPLASM\SIDA 


299 


The  last  are  usually  found  in  a  group  of  4 
joined  together  in  the  form  of  a  cross. 
Because  of  this,  some  authorities  prefer 
to  use  a  separate  generic  name,  NiittalUa, 
for  this  and  similar  species. 

Life  Cycle:  Division  in  the  erythro- 
cytes is  unlike  that  of  most  other  species 
of  Babesia  in  that  4  daughter  trophozoites 
are  formed  at  one  time. 

The  vectors  are  Dermacentor  mar- 
ginatus  (syn. ,  D.   reticitlatits  ),  D.  pictus, 
Hyalo)H7na  niarginatuni  (syn. ,   H.  detri- 
tinii ),   H.  iiralense  and  RJiipicephaliis 
bursa  in  the  USSR,   H.  aiialolicnm  (syn. , 
H.  excavatum  )  and  H.  marginatum  in 
Greece,   H.  droj)iedarii  andR.  sanguineus 
in  North  Africa,  R.  evertsi  in  South 
Africa,  and  H.  )narginatu)n  a.ndR.  san- 
guineus in  central  Asia.     Transmission  is 
thru  the  egg  in  H.  anatolicum,    and  stage- 
to-stage  in  all  the  others. 

Intra-uterine  transmission  may  also 
occur  (Neitz,   1956). 

Pathogenesis:     This  species  is  more 
pathogenic  than  B.  caballi.    Mixed  infec- 
tions are  not  rare,  however,  so  that  it  is 
sometimes  difficult  to  be  sure  which  spe- 
cies is  causing  the  symptoms.     The  incu- 
bation period  following  an  infective  tick 
bite  is  10  to  21  days.    The  first  sign  of 
disease  is  a  rise  in  temperature.    This 
is  followed  by  listlessness,  depression, 
marked  thirst,  inappetence,  watering  of 
the  eyes  and  swelling  of  the  eyelids.    The 
most  characteristic  sign  is  icterus.    There 
is  marked  anemia,  more  than  half  the 
erythrocytes  often  being  destroyed. 
Hemoglobinuria  is  present,  but  in  contrast 
to  B.  caballi  infections,   posterior  paral- 
ysis is  absent.    Edema  of  the  head,  legs, 
and  ventral  part  of  the  body  is  sometimes 
present.    Affected  animals  are  constipa- 
ted, passing  small,  hard  balls  of  feces 
covered  with  yellow  mucus;  they  lose  con- 
dition fairly  rapidly,  and  may  become 
extremely  emaciated.     Hemorrhages  are 
present  on  the  mucous  membranes  of  the 
nasal  passages,  vagina  and  third  eyelid. 

The  disease  usually  lasts  7  to  12  days, 
but  it  may  be  peracute,  with  death  occur- 


ring in  1  to  2  days,  or  it  may  be  chronic 
and  last  for  weeks.       The  mortality  is 
generally  not  more  than  10%,  but  may 
sometimes  reach  50%.     Recovery  is  slow, 
and  it  may  be  several  weeks  or  even 
months  before  the  animal  returns  to  nor- 
mal. 

At  necropsy,  emaciation,  icterus, 
anemia  and  edema  are  present.    There 
are  accumulations  of  fluid  in  the  pericar- 
dial sac  and  body  cavities,  and  the  fat  is 
gelatinous  and  yellow.    The  spleen  is  en- 
larged, with  soft,  dark  brown  pulp.    The 
lymph  nodes  are  swollen  and  sometimes 
inflamed.     The  liver  is  swollen,  engorged, 
and  brownish  yellow;  the  hepatic  lobules 
are  yellow  in  the  center  and  greenish  yel- 
low around  the  edges.    The  kidneys  are 
pale  yellow  and  may  contain  petechial 
hemorrhages.    There  are  hemorrhages  or 
red  streaks  on  the  mucosa  of  the  intestine 
and  stomach. 

Immunity:     There  is  no  cross -immun- 
ity between  B.  equi  and  B.  caballi.     Young 
animals  are  less  seriously  affected  than 
adults. 

Diagnosis:     Babesiosis  can  be  diag- 
nosed by  identifying  the  parasites  in 
stained  blood  smears.    Examinations 
should  be  made  as  early  as  possible,  since 
the  parasites  begin  to  disappear  from  the 
peripheral  blood  after  the  fifth  day. 

Treatment:     Trypan  blue  is  ineffective 
against  B.  equi.     Acriflavine  has  been 
recommended;  it  is  injected  intravenously, 
10  ml  of  a  2%  aqueous  solution  being  given 
per  100  kg  body  weight. 


BABESIA   TRAUTMANNI 
(KNUTH  AND  DU  TOIT,   1918) 

Synonyms:     Piroplasma  trautmanni, 
Piroplasma  suis. 

Host:      Pig. 

Location:     Erythrocjrtes. 

Geographic  Distribution:     Southern 
Europe,  Central  and  South  Africa,  USSR. 


300 


THE  PIROPLASMASIDA 


Morphology:     This  is  a  large  form, 
the  trophozoites  being  2.  5  to  4  ^  long  and 
1.  5  to  2;i  wide.     They  are  oval,   piriform, 
or  less  commonly  round.    They  often  occur 
in  pairs.    The  host  cells  usually  contain 
1  to  4  or  occasionally  5  to  6  parasites. 
From  a  very  few  to  65%  of  the  erythro- 
cytes may  be  invaded. 

Life  Cycle:     The  vector  is  Rhipiceph- 
alus  soiiiiiiiiieus  (syn. ,  R.  tiiraniciis). 
Transmission  occurs  thru  the  egg.    Other 
ticks  have  also  been  incriminated. 

Pathogenesis:     This  species  may 
cause  either  a  mild  disease  or  a  fatal  one 
with  fever,   listlessness,   inappetence, 
anemia,  hemoglobinuria,  icterus,  edema 
and  incoordination.    Infected  sows  may 
abort.     The  spleen  is  enlarged  and  en- 
gorged, the  liver  is  enlarged,  there  are 
pulmonary,  renal  and  gastrointestinal 
hyperemia  and  edema,  petechiae  are 
present  on  the  serous  membranes,  and 
there  are  subepicardial  and  subendocar- 
dial hemorrhages. 

Treatment:     Trypan  blue,  acaprin 
and  phenamidine  are  all  effective.      Aca- 
prin is  injected  subcutaneously,  2  ml  of  a 
5%  solution  being  administered  per  100  kg 
to  large  pigs  and  1  ml  of  a  0.  5%  solution 
per  10  kg  to  small  pigs.    Lawrence  and 
Shone  (1955)  injected  phenamidine  sub- 
cutaneously at  the  rate  of  1.  5  ml  of  a  40% 
aqueous  solution  per  100  pounds  body 
weight. 

Prevention  and  Control:     Same  as  for 
other  babesioses. 


BABESIA  PERRONCITOI 
(CERRUTI,   1939) 

Synonym :     Babesiella  perronciloi. 

Host:     Pig. 

Location:     Erythrocytes. 

Geographic  Distribution:     Europe 
(Sardinia),   French  Sudan. 

Morphology:     This  is  a  small  form. 
It  is  usually  annular,  0.7  to  2 /j,  in  diam- 


eter, with  a  thin  ring  of  cytoplasm  sur- 
rounding a  vacuole,  but  it  may  also  be 
oval,  quadrangular,   lanceolate  or  piriform, 
measuring  1.  2  to  2.  6  by  0.  7  to  1.  9  |i.    The 
trophozoites  usually  occur  singly  in  the 
host  cells,  but  sometimes  2  or  more  may 
be  present. 

Life  Cycle:     The  vector  is  unknown. 

Pathogenesis:  The  disease  caused 
by  this  species  is  similar  to  that  caused 
by  B.  tranhtimiiii. 

Treatment:     Acaprin  is  effective 
against  this  species,  but  trypan  blue  is 
presumably  not. 


BABESIA   CANIS 

(PIANA  AND  GALLI-VALERIO,   1895) 

Synonyms:     Pyrosoma  higeminum 
var.  cants,  Piroplasnia  canis,   Babesia 
rossi,  Rosslella  rossi,  Babesia  vilalii, 
Rangelia  vitalii. 

Disease:     Canine  babesiosis,  canine 
piroplasmosis,  biliary  fever,  malignant 
jaundice,  nambiuvu. 

Hosts:  Dog,  wolf,  side-striped 
jackal  {Thos  adiistus),  black-backed  jackal 
(T.  iiieso)tielas).  In  addition,  the  red  fox, 
and  jackal  {Canis  Inpaster)  have  been  in- 
fected experimentally.  However,  Thomas 
and  Brown  (1934)  were  unable  to  infect  the 
cat  even  after  splenectomy. 

Location:     Erythrocytes. 

Geographic  Distribution:     North 
America  (Florida,   Virginia,   Texas,   Puerto 
Rico),   Central  America,  South  America, 
southern  Europe,  USSR,  Africa,  Asia. 

Prevalence:     This  parasite  is  com- 
mon in  many  tropical  regions.    It  is  un- 
common in  the  U.S.  ,  but  has  been  reported 
from  Florida  by  Eaton  (1934)  and  Sanders 
(1937),  from  Texas  by  Merenda  (1939)  and 
from  Virginia  by  Grogan  (1953). 

Morphology:     This  is  a  large  form. 
The  trophozoites  are  piriform  and  4  to 
5/i  long,  or  amoeboid  and  2  to  4jj.  in 


THE  PIROPLASMASIDA 


301 


diameter.     They  generally  contain  a  vac- 
uole.    Multiple  infections  of  the  erythro- 
cytes are  common.    In  addition,  masses 
of  30  to  100  "merozoites"  have  been  des- 
cribed for  Raiigelia  vitalii  (a  synonym  of 
B.  caiiis)  in  the  endothelial  cells  of  the 
lungs  and  kidneys.     However,  these  were 
much  more  likely  agglomerations  of  or- 
ganisms in  the  small  blood  vessels. 

Life  Cycle:     The  life  cycle  has  been 
described  above  (p.  287).     The  vectors 
are  Rltipiceplialus  scaigiiineus  thruout  the 
world,  Dermacentor  marginalus  (syn. , 
D.  reticulati(s),  D.  pictiis  and  I>.  veiiiis- 
tus  in  Europe,   D.  pictiis  and  Hyalomina 
margiiiatum  in  the  USSR,  and  Hae)na- 
pliysalis  leaclii  in  South  Africa.     Trans- 
mission takes  place  thru  the  egg  in  all  but 
D.  pictiis,    and  stage-to-stage  in  this  spe- 
cies,  R.  sanguineus  and  H.   leaclii. 

Pathogenesis:     The  severity  of  in- 
fections with  B.  canis  varies  considerably 
with  the  strain.    In  some  localities  it  is  a 
comparatively  mild  disease,  while  in 
others  it  may  be  highly  pathogenic.    Both 
young  and  old  dogs  are  susceptible.    In 
countries  where  the  disease  is  endemic, 
the  indigenous  dogs  usually  become  in- 
fected while  young  and  do  not  suffer  such 
a  severe  disease,  while  the  mortality  is 
high  among  imported  dogs. 

The  incubation  period  is  10  to  21  days 
in  naturally  infected  dogs.    The  first  sign 
of  disease  in  acute  cases  is  fever.    This 
is  quickly  followed  by  marked  anemia, 
with  icterus,  inappetence,  marked  thirst, 
weakness,  prostration  and  often  death. 
Hemoglobinuria  is  sometimes  but  not 
usually  present. 

In  chronic  cases  the  fever  is  not  high 
and  seldom  lasts  more  than  a  few  days 
and  there  is  little  icterus.    Anemia  is 
severe,  and  the  dogs  are  listless  and  be- 
come very  weak  and  emaciated. 

Canine  babesiosis  is  protean  in  its 
manifestations,  and  may  take  on  many 
different  clinical  forms.    Involvement  of 
the  circulatory  system  may  produce  edema, 
purpura  and  ascites;  there  may  be  stoma- 
titis and  gastritis;  and  involvement  of  the 
respiratory  system  causes  catarrh  and 


dyspnea.    Keratitis  and  iritis  are  seen  if 
the  eyes  are  affected,  and  myositis  and 
rheumatic  signs  if  the  muscles  are  in- 
volved. 

Central  nervous  system  involvement 
causes  locomotor  disturbances,    paresis, 
epileptiform  fits,  etc.   (Malherbe  and 
Parkin,   1951;  Malherbe,   1956).    A  cere- 
bral form  of  the  disease  was  described  by 
Purchase  (1947)  in  which  parasites  were 
rare  in  the  blood  but  abundant  in  the  brain 
capillaries.    This  tendency  to  clog  the 
capillaries  is  common  to  many  species  of 
Babesia.     In  cerebral  babesiosis  the  signs 
may  be  confused  with  those  of  rabies. 

In  South  America,  the  disease  is 
called  nambiuvu,  meaning  "bloody  ears" 
in  the  Guarani  language.    As  the  name 
suggests,  it  is  a  hemorrhagic  disease. 
There  is  bleeding  from  the  edges  of  the 
ears  and  from  the  muzzle,  particularly 
in  young  dogs  in  summer.    There  are  also 
internal  hemorrhages. 

The  spleen  is  enlarged,  with  dark  red, 
soft  pulp  and  prominent  splenic  corpuscles. 
The  liver  is  enlarged  and  yellow,  with 
pathological  changes  ranging  from  conges- 
tion to  centrilobular  necrosis  (Gilles, 
Maegraith  and  Andrews,  1953).    The  heart 
is  pale  and  yellowish.    The  kidneys  are 
yellowish,  and  show  considerable  nephro- 
sis or  nephritis  histologically.    The  mus- 
cles are  pale  and  yellow,  and  the  fat  and 
mucous  membranes  may  be  yellowish. 
There  may  be  a  variable  amount  of  fluid 
in  the  pleural,  pericardial  and  peritoneal 
cavities.    Small  hemorrhages  are  some- 
times present  on  the  heart,  pleura,  bron- 
chi and  intestines.    There  is  less  icterus 
in  chronic  than  in  acute  cases. 

Immunity:     Recovered  animals  re- 
main infected  in  a  state  of  premunition. 
This  persists  for  life  if  they  are  kept  in 
an  endemic  area,  but  the  parasites  die 
out  in  a  year  or  more  in  the  absence  of 
reinfection. 

Diagnosis:     In  endemic  areas,  symp- 
toms of  fever,  anemia,  and  icterus,  with 
or  without  hemoglobinuria,  are  suggestive 
of  canine  babesiosis.    The  diagnosis  can 
ordinarily  be  confirmed  by  finding  the 


302 


THE  PIROPLAS?vlASIDA 


parasites  in  stained  blood  smears.  They 
are  often  present  in  capillary  blood  when 
they  cannot  be  found  in  venous  blood. 

Treatment:     Trypan  blue  is  effective 
against  B.  caiiis.    It  is  injected  intraven- 
ously, the  dosage  for  a  35-pound  dog  being 
4  to  5  ml  of  a  1%  solution.    Acriflavine  has 
also  been  recommended.    It  is  injected 
intravenously  in  0.1  to  2.0%  solution,  the 
dosage  being  1  to  3  ml  of  the  drug  per  kg 
body  weight.    Acaprin  is  safer  than  acri- 
flavine.   It  is  injected  subcutaneously  in 
0.  5%  solution  at  the  rate  of  0.05  ml  per 
kg  body  weight.     Phenamidine  has  given 
excellent  results.    It  is  injected  subcutan- 
eously in  5%  solution  at  a  dosage  rate  of 
10  mg  per  kg  (i.  e. ,  0.  2  ml  per  kg);  a 
single  dose  is  usually  effective,  but  it 
may  be  repeated  the  next  day. 

Prevention  and  Control:     As  for 
other  Babesia  infections,  these  depend 
upon  tick  control. 


BABESIA   VOCE  LI 
REICHENOW,   1937 


Synonym:     Babesia  major  Reichenow, 


1935: 

Host:     Dog. 

Location:     Erythrocytes. 

Geographic  Distribution: 
Asia,  North  Africa. 


Southern 


Morphology:     This  species  is  some- 
what larger  than  B.  canis. 

Life  Cycle:     Similar  to  that  of  B. 
canis.    The  vector  is  Rliipiceplialus  san- 
guineus (Shortt,  1936).    Transmission 
occurs  thru  the  egg  and  stage-to-stage. 

Pathogenesis:     This  species  is  less 
pathogenic  than  B.  canis,  but  the  disease 
it  causes  is  otherwise  similar. 

Immunity:     Dogs  infected  with  this 
species  are  not  resistant  to  infection  with 
B.  canis  transmitted  by  Derniacenior, 
which  is  the  reason  that  Reichenow  (1935) 
separated  the  two  species.    Some  authors. 


however,  (e.g.,  Poisson,  1953)  consider 
them  synonymous. 

Treatment:     Same  as  for  B.  canis. 


BABESIA   CIBSONI 
(PATTON,   1910) 

Synonyms:     Piroplasma  gibsoni, 
Aclironialicus  gibsoni,   Babesiella  gibsoni, 
Paltonella  gibsoni,  Nitltallia  bauryi. 

Disease:     Canine  babesiosis,   Lahore 
canine  fever,  tick  fever. 

Hosts:     Dog,  jackal  {Canis  aureus), 
wolf,  Indian  wild  dog  {Cuon  dukhensis), 
fox.    The  jackal  is  the  natural  host  in 
India. 

Location:     Erythrocytes. 

Geographic  Distribution:     India,   Cey- 
lon, parts  of  China,  occasionally  North 
Africa. 

Morphology:     This  species  is  smaller 
than  B.  canis  and  does  not  have  its  char- 
acteristic paired,  piriform  trophozoites. 
The  trophozoites  of  B.  gibsoni  are  usually 
annular  or  oval  and  not  more  than  1  /'S  of 
the  diameter  of  the  host  erythrocyte. 
Occasionally,  large  ovoid  forms  half  the 
diameter  of  the  host  cell  or  thin,  elongate 
forms  reaching  almost  across  the  cell 
may  be  found. 

Life  Cycle:     Similar  to  that  of  B. 
canis.    The  vectors  in  India  are  Haema- 
physalis  bispinosa  and  Rliipiceplialus 
sanguineus.     Transmission  is  thru  the  egg 
and  stage -to -stage  in  the  former,  and 
stage-to-stage  in  the  latter. 

Pathogenesis:     This  species  is  only 
slightly  pathogenic  for  its  natural  host, 
the  jackal,  but  is  highly  pathogenic  for 
the  dog,  causing  marked  anemia,   remit- 
tent fever,   hemoglobinuria,  constipation, 
marked  splenomegaly  and  hepatomegaly. 
The  disease  usually  runs  a  chronic  course, 
with  remissions  and  relapses  of  fever,  and 
death  may  not  occur  for  many  months.    In 
imported  dogs,  however,  death  is  said  to 
occur  in  3  to  4  weeks. 


THE  PIROPLASIVL^SIDA 


303 


Immunity:    Dogs  which  are  immune  to 
B.   canis  are  still  susceptible  to  B.  gibsoiii. 

Treatment:     Neither  trypan  blue  nor 
acaprin  is  effective  against  B.  gibsoni. 
Treatment  with  arsenicals  such  as  novar- 
senobillon  or  tryparsamide  has  been  sug- 
gested, but  they  are  apparently  not  too 
satisfactory. 


BABESIA  FELIS 
DAVIS,   1929 

Synonyms:      Babesiella felis,  Nut- 
tallia  felis  var.  duDieslica. 

Hosts:     Domestic  cat,  wild  cat  (Felis 
lybica),  puma  (F.   co)icolor),  lion  {F.   led), 
American  lynx  {Lynx  ntfiis),  Indian  leop- 
ard (Paiithera  pardiis ). 

Location:     Erythrocytes. 

Geographic  Distribution:     Africa, 
India,    ?  North  America  (California). 
This  species  was  first  found  in  a  wild  cat 
in  the  Sudan  and  has  since  been  found  in 
domestic  cats  in  India  and  South  Africa, 
in  the  lion  in  the  French  Sudan  and  in  the 
Indian  leopard.    In  addition,  it  was  found 
in  2  pumas  imported  into  Egypt  from  Cal- 
ifornia and  in  an  American  lynx  in  the 
London  zoo.    It  has  not  been  found  in  an- 
imals still  in  North  America,  so  its  ex- 
istence on  this  continent  is  still  proble- 
matical. 

Morphology:     This  is  a  small  form. 
Most  of  the  trophozoites  are  round  or  ir- 
regularly round  and  1.  5  to  2(j,  in  diameter. 
Some  are  elongate  and  2  to  3,  or  rarely 
4jj,  long.    Piriform  trophozoites  are  rare. 
Division  is  quadruple,  forming  a  cruciform 
schizont,  or  binary. 

Life  Cycle:     The  vectors  are  unknown, 
altho  Hae>napliysalis  leaclii  has  been  in- 
criminated in  South  Africa, 

Pathogenesis:  Feline  babesiosis  is 
less  severe  than  the  canine  disease,  and 
affected  animals  usually  recover  without 
treatment.  It  is  characterized  by  anemia, 
slow  respiration,  somnolence,  listless- 
ness,  emaciation,   constipation  with  yel- 


low or  orange  feces,  splenomegaly,  and 
sometimes  icterus  and  hemoglobinuria. 

Treatment:     Both  trypan  blue  and 
acaprin  are  effective  against  B.  felis. 

Genus  AEGYPTIANELLA 
Carpono,  1928 

This  genus  contains  small,   round, 
oval  or  piriform  parasites  of  the  erythro- 
cytes of  birds.    The  host  cell  is  not  de- 
formed.   Schizogony  occurs  in  the  ery- 
throcytes, with  the  formation  of  4  to  16  or 
20  merozoites.     Laird  and  Lari  (1957) 
have  questioned  the  justification  for  separ- 
ating this  genus  from  Babesia,  but  for  the 
present  it  is  probably  best  to  do  so. 


AEGYPTIANELLA  PULLORUM 
CARPANO,   1928 

Synonyms:     Balfouria  galUnarum. , 
Balfouria  anserina. 

Disease:     Aegyptianellosis,  avian 
piroplasmosis. 

Hosts:     Chicken,  goose,  duck,  tur- 
key.   This  species  has  been  transmitted 
experimentally  to  the  turtle  dove,  ring- 
dove, crowned  crane,  quail,   pigeon, 
canary  and  other  birds  (Curasson,  1943). 
The  chicken  is  probably  the  most  impor- 
tant host. 

Location:     Erythrocytes. 

Geographic  Distribution:     North 
Africa,  South  Africa,  Indochina,  India, 
USSR  (Transcaucasia),  southeast  Europe. 

Morphology:     The  trophozoites  are 
usually  small,  ranging  in  size  from  0.  5 
to  3  or  even  4|u ,  depending  upon  the  stage 
of  development.    They  are  round,  oval  or 
piriform,  sometimes  with  a  vacuole. 
They  multiply  by  schizogony,   producing 
a  variable  number — up  to  20--of  very 
small  merozoites. 

Life  Cycle:  The  natural  vector  is 
the  fowl  tick,  Argas  Persians .  Trans- 
mission does  not  take  place  either  thru 
the  egg  or  stage -to -stage.    After  the 


304 


THE  PIROPLASMASIDA 


adult  tick  becomes  infected  by  feeding  on 
an  infected  bird,  it  takes  26  days  or  more 
before  it  is  able  to  transmit  it  to  another 
bird  (Bedford  and  Coles,  1933).    Ticks 
can  remain  infective  for  as  long  as  162 
days.    The  stages  of  development  in  the 
tick  have  not  been  described.    .4.  pid- 
lonini  can  be  transmitted  experimentally 
by  intravenous,  intraperitoneal,  subcutan- 
eous or  intramuscular  injection  or  by 
scarification. 

The  incubation  period  in  chickens  is 
12  to  15  or  more  days. 

Pathogenesis:     A.  pullonim  may 
cause  either  a  latent,  chronic,  subacute 
or  acute  disease  in  chickens.    The  acute 
form  occurs  primarily  in  young  or  im- 
ported birds  in  endemic  regions,  while 
the  chronic  and  latent  forms  occur  pri- 
marily in  adult  birds  in  endemic  regions. 
Severe  outbreaks  have  been  reported  in 
chickens  in  Algeria,  Egypt,  South  Africa 
and  Greece.    Ducks  and  geese  are  appar- 
ently less  seriously  affected. 


is  said  to  be  highly  effective,  but  must  be 
given  intravenously. 

Prevention  and  Control:     These  de- 
pend upon  elimination  of  the  tick  vectors. 

AEGYPTLANELLA  MOSHKOVSKII 
(SCHURENKOVA,   1938) 
POISSON,   1953 

Synonyms:     Sogdianella  tnoshkovskii, 
Babesia  ardeae,  Niittallia  shortti,  Babesia 
moshkuvskii. 

Hosts:     Chicken,  turkey  (?),  pheas- 
ant (?),  eagle  (Gypaetiis  barbatus),  Indian 
house  crow  [Coriiis  splendens),   heron 
[Ardea  cinerea),  Egyptian  kestrel  {Falco 
timiunculus). 

Location:     Erythrocytes. 

Geographic  Distribution:     Indochina, 
USSR  (Tadzhikistan),  Egypt,   Pakistan, 
India,  United  States  (?),  South  Africa  (?), 
Iran  (?). 


The  principal  signs  are  anemia,  fever, 
icterus,  diarrhea  and  anorexia.    Necropsy 
findings  include  splenomegaly,  liver  de- 
generation, characteristic  greyish  yellow 
kidneys,  intestinal  congestion,  petechial 
hemorrhages  on  the  serosa,  and  some- 
times pericarditis.    Adult  birds  usually 
recover. 

Immunity:     Birds  which  have  recov- 
ered from  infection  are  premunized,  but 
their  latent  infections  can  be  reactivated 
by  splenectomy  or  by  intercurrent  disease. 

Diagnosis:     A.  piillornm  infections 
can  be  diagnosed  by  identifying  the  para- 
sites in  stained  blood  smears.    They  are 
difficult  to  stain,  however,  so  the  staining 
time  must  be  prolonged.    Affected  birds 
are  often  simultaneously  infected  with 
Borrelia  aiiseriiia.  the  cause  of  fowl 
spirochetosis,  which  is  also  transmitted 
by  Argas  persicus. 

Treatment:     Trypan  blue  and  acri- 
flavine  are  ineffective  against  A.  pnllorum, 
and  variable  results  have  been  obtained 
with  stovarsol  and  quinacrine.    Ichthargan 


This  species  was  first  described  by 
Schurenkova  (1938)  from  Gypaetns  bar- 
batus in  Tadzhikistan.     Laird  and  Lari 
(1957)  found  what  they  considered  the  same 
species  in  an  Indian  house  crow  in  Pakis- 
tan, reviewed  the  literature  on  avian 
babesioid  hematozoa,  and  concluded  that 
the  following  should  be  assigned  to  this 
species:    The  form  described  from  the 
chicken  in  Indochina  by  Henry  (1939),  the 
form  described  under  the  name  Babesia 
ardeae  by  Toumanoff  (1940)  Ivom  Ardea 
cinerea  in  Indochina,  and  the  form  des- 
cribed under  the  name  Niittallia  shortti 
by  Mohamed  (1952)  from  Falco  tinnuncu- 
liis  in  Egypt.    They  were  not  sure  of  its 
relationship  to  the  forms  reported  from 
chickens  in  Philadelphia,   New  York  and 
South  Africa  by  Coles  (1937),  from  chick- 
ens in  the  Punjab  by  Abdussalam  (1945), 
from  turkey  poults  in  California  by 
McNeil  and  Hinshaw  (1944),  and  from  the 
pheasant  in  Iran  by  Rousselot  (1947),  all 
of  which  they  considered  insufficiently 
described.    I  am  including  these  latter 
forms  here  as  a  matter  of  convenience, 
without  prejudice  as  to  their  final  dispo- 
sition. 


THE  PIROPLASM4lSIDA 


305 


Laird  and  Lari  (1957)  assigned  this 
species  to  the  genus  Babesia,  considering 
that  the  differences  between  the  various 
members  of  the  Babesiidae,  including 
Aegyp/iaiiella.    might  best  be  dealt  with  at 
the  subgeneric  level.    They  may  well  be 
correct.     However,  until  more  is  known 
about  the  avian  babesiids,  I  prefer  to  leave 
them  in  the  genus   Aegyptiaiiella. 

Morphology:     The  form  from  the 
chicken  described  from  Henry  (1939)  is 
0.2  to  2.  5 p.  in  diameter,  occurring  as 
Anaplasuia -like  granules,  as  small  rings 
and  as  elongate  bodies  with  a  terminal  dot 
of  chromatin  and  a  thin  tail  of  cytoplasm. 
Both  binary  fission  and  schizogony  were 
seen.    The  nuclei  of  the  schizonts  are 
either  strung  on  a  thin  cytoplasmic  ring 
or  are  at  the  angles  of  triangular  or 
lozenge-shaped  figures.     The  schizonts 
usually  produce  4  merozoites,  altho  some 
have  as  many  as  6. 

The  form  described  by  Schurenkova 
from  the  eagle  produces  4  merozoites  and 
also  has  large,  homogeneous  bodies  which 
she  took  to  be  gametocytes. 

The  form  described  by  Laird  and  Lari 
from  the  crow  has  anaplasmoid  bodies  0.2 
to  0.6/i  in  diameter,  elongate  forms  0.7 
to  0.  9  by  0, 1  jLt  composed  of  a  terminal  dot 
of  chromatin  and  a  slender  cytoplasmic 
tail,  ring  forms  measuring  up  to  2. 1  by 
1.4(i,  and  large,  solid,  oval  or  irregular 
forms  0.  9  to  5.  3  [x  in  diameter.    All  stages 
could  divide  by  binary  fission.     Cruciform 
and  fan-shaped  schizonts  were  also  present. 
Four  merozoites  are  formed. 

The  form  described  by  McNeil  and 
Hinshaw  (1944)  from  turkey  poults  was 
roundish,  oval  or  piriform,  0.  5  to  2 /j.  in 
diam.eter,  and  occurred  singly  or  in  pairs. 
They  thought  it  resembled  Sauroplasnia 
tho)}iasi,   a  blood  parasite  described  from 
a  lizard  in  South  Africa  by  DuToit  (1937). 


Life  Cycle:     Unknown. 
Pathogenesis:     Unknown. 


FAMILY   THEILERIIDAE 

Members  of  this  family  are  relatively 
small,   round,  ovoid,   irregular  or  bacilli- 
form  parasites.    They  occur  in  the  erythro- 
cytes and  lymphocytes  or  histiocytes. 
Schizogony  takes  place  in  the  lymphocytes 
or  histiocytes,  and  is  followed  by  invasion 
of  the  erythrocytes.     The  forms  in  the 
er3rthrocytes  may  or  may  not  reproduce; 
in  the  latter  case  they  divide  into  2  or  4 
daughter  cells.     Reichenow  (1940,   1953) 
maintained  that  schizogony  does  not  occur 
in  the  vertebrate  host  but  is  simulated  by 
repeated  binary  fissions.     However,  ob- 
servations on  the  protozoa  in  tissue  cul- 
ture (Tsur-Tchernomoretz,   1945; 
Brocklesby  and  Hawking,  1958)  indicate 
that  schizogony  does  occur. 

The  vectors  are  ixodid  ticks.    Binary 
fission,  schizogony  and  sexual  reproduction 
have  been  said  to  occur  in  the  tick,  but  the 
existence  of  sexual  reproduction  is  dubious, 
and  Reichenow  (1940,  1953)  believed  that 
schizogony  is  simulated  by  repeated  binary 
fissions. 

Members  of  this  family  cause  an  im- 
portant group  of  diseases,  known  collec- 
tively as  theilerioses,  in  cattle,  sheep 
and  goats.    These  have  caused  heavy 
losses  in  Africa,  southern  Europe  and 
Asia. 

This  group  has  been  reviewed  by 
Reichenow  (1953),   Poisson  (1953),  and 
most  comprehensively  by  Neitz  (1956, 
1957,  1959).    Most  authors  place  all  mem- 
bers of  the  family  in  the  genus  Theileria 
(e.g.,  Poisson,  1953),  while  some  accept 
the  genus  Cytauxzoon  as  well  (e.g. , 
Reichenow,  1953).    However,  Neitz  and 
Jansen  (1956)  divided  the  group  into  3 
genera  on  the  basis  of  biological  character- 
istics.    They  even  placed  them  in  2  fam- 
ilies in  a  new  suborder  Leucosporidea, 
but  this  latter  treatment  does  not  seem 
justified. 

In  the  genus  Theileria  as  redefined 
by  Neitz  and  Jansen,  the  forms  in  the 
erythrocytes  do  not  divide,  the  parasites 
cannot  be  transmitted  by  blood  inoculation, 
and  recovered  animals  do  not  remain  car- 


306 


THE  PIROPLASMASIDA 


riers  (i.e.,  there  is  no  premunition).    In 
the  redefined  genus  Goiuleria,  the  forms 
in  the  erythrocytes  do  divide,  the  para- 
sites can  be  transmitted  by  blood  inocula- 
tion, and  recovered  animals  remain 
carriers  for  life  (i.e.,   premunition  is 
present).    In  the  genus  Cylaitxzooii,  schi- 
zogony takes  place  in  the  histiocytes 
rather  than  in  the  lymphocytes  as  in  the 
other  2  genera,  and  the  forms  in  the  ery- 
throcytes reproduce  by  binary  fission. 

Neitz  (1959)  recognized  1  species  of 
Theileria  and  5  of  Goiider/a  in  domestic 
animals,  and  10  named  and  36  unnamed 
species  of  Theileria,  1  of  Gonderia  and  2 
of  Cytauxzoon  in  wild  animals.    The  great 
majority  occur  in  African  ruminants. 
They  are  all  tabulated  by  Neitz  (1957). 
Since  the  forms  in  the  erythrocytes  of  all 
3  genera  look  alike,  and  since  practically 
all  the  species  in  wild  animals  are  known 
only  from  these  forms,  their  assignment 
to  the  genus  Theileria  is  clearly  provi- 
sional. 


THEILERIA  PARVA 

(THEILER,   1904)  BETTENCOURT, 

FRANCA  AND  BORGES,   1907 

Synonyms:     Piroplasma  kochi,  Piro- 
plasiiia  panitui .    Theileria  kochi. 

Disease:  East  Coast  fever,  bovine 
theileriosis,  African  Coast  fever,  Rho- 
desian  tick  fever,  Rhodesian  redwater. 

Hosts:     Ox,  zebu,  water  buffalo, 
African  buffalo  {Syncerus  coffer). 

Location:     Lymphocytes,  erythro- 
cytes. 

Geographic  Distribution:     East,  Cen- 
tral and  South  Africa. 

Prevalence:     East  Coast  fever  is  one 
of  the  most  important  cattle  diseases  in  the 
regions  where  it  is  found.    According  to 
Neitz  (1959),   it  occurs  enzootically  in  the 
Belgian  Congo,  Uganda,  Kenya,   Tangan- 
yika, Nyasaland,   Zanzibar  and  Swaziland. 
It  has  been  eliminated  from  most  parts  of 
South  Africa. 


Morphology:     The  forms  in  the  ery- 
throcytes are  predominantly  (over  80%) 
rod-shaped,  and  measure  about  1.  5  to 
2.0  by  0.5  to  I.Ojlx.    Round,  oval  and 
comma-shaped  forms  also  occur.    When 
stained  with  a  Romanowsky  stain,  they 
have  a  red  nucleus  at  one  end  and  blue 
cytoplasm.    Several  parasites  are  often 
found  in  a  single  host  erythrocyte. 


Fig.  35.      Theileria  parra  in  bovine  eryth- 
rocytes.   X  2800.     (After  Nuttall, 
1913  in  Payasilology.  published 
by  Cambridge  Univ.    Press). 

Genus  THEILERIA   Bettencourt, 
Franca  and   Borges,    1907 

In  this  genus  the  parasites  multiply 
by  schizogony  (or  possibly  by  a  series  of 
binary  fissions)  in  the  lymphocytes  and 
finally  invade  the  erythrocytes.     The 
forms  in  the  erythrocytes  do  not  reproduce. 
Infection  cannot  be  transmitted  by  blood 
inoculation,  and  there  is  no  premunition. 
There  is  one  valid  species  in  domestic 
animals. 


The  multiplying  forms  occur  in  the 
lymphocytes  and  occasionally  in  the  endo- 
thelial cells.    They  are  found  especially 
in  the  lymph  nodes  and  spleen,  where  they 
are  usually  very  numerous.    They  are 
known  as  Koch's  blue  bodies  or  Koch's 
bodies,  and  are  circular  or  irregularly 
shaped  bodies  averaging  8  /i  in  diameter 
and  ranging  up  to  12  jn  or  more.    They 
may  be  intracellular  or  free  in  the  gland 
or  spleen  juice.    When  stained  with  a 
Romanowsky  stain,  their  cytoplasm  is  blue 
and  they  contain  a  varying  number  of  red 
chromatin  granules. 

Two  types  of  these  schizonts  are  rec- 
ognized.   Macroschizonts  (sometimes 


THE  PIROPLASM.4.SIDA 


307 


called  agamonts)  contain  chromatin  gran- 
ules 0.4  to  2.0 jj.  in  diameter  with  a  mean 
of  1.2 li  and  produce  macromerozoites 
2.0to2.5jLt  in  diameter.     Microschizonts 
(sometimes  called  gamonts  because  they 
are  thought  to  produce  sexual  stages)  con- 
tain chromatin  granules  0.3  to  0.8;^  in 
diameter  with  a  mean  of  0.  5  pi  and  produce 
micromerozoites  0.7  to  1.0  jj,  in  diameter. 

Life  Cycle:     The  life  cycle  of  this 
species  has  been  studied  more  than  that  of 
other  members  of  the  family,  but  its  details 
in  the  tick  are  still  uncertain.     The  most 
important  vector  is  Rhipicephalus  appen- 
diciilatus.    Other  vectors  are  R.  ayrei, 
R.  capensis,  R.  evertsi,  R.  jeaiielli,  R. 
iieavei,  R.  slmus,  Hyalonima  excavatum, 
H.  dromedaril  and  H.  truncatiim.    Trans- 
mission is  stage -to -stage  in  all  cases, 
and  not  thru  the  egg.    R.  appendictdatiis, 
for  instance,  acquires  the  infection  as  a 
larva  and  transmits  it  as  a  nymph,  or 
acquires  the  infection  as  a  nymph  and 
transmits  it  as  an  adult.    The  parasite 
will  not  survive  in  the  ticks  thru  more 
than  1  molt. 

Reichenow  (1940),  who  made  a  careful 
study  of  the  life  cycle  in  cattle  and  in  R. 
appeiidicnlafHS,   said  that  the  great  major- 
ity of  parasites  die  in  the  tick  intestine. 
A  few  succeed  in  passing  thru  the  intes- 
tinal wall  into  the  body  cavity  and  thence 
to  the  salivary  glands,  where  they  invade 
the  secretory  cells.     Here  they  lie  dor- 
mant until  after  the  tick  has  dropped  off  its 
host,  molted,  attached  itself  to  a  new  host 
and  started  to  suck  blood.    The  parasites 
then  begin  to  multiply  by  repeated  binary 
fissions,  filling  the  interstices  between 
the  secretory  droplets.    They  continue  to 
multiply,  and  finally  the  host  cell  is 
greatly  enlarged  and  filled  with  something 
over  30,  000  tiny  parasites.    This  requires 
15  successive  binary  divisions.     Very  few 
secretory  droplets  remain.    The  host  cell 
ruptures,  and  the  parasites  are  released 
into  the  lumen  of  the  salivary  ducts  and 
are  injected  into  the  host  when  the  tick 
sucks  blood.    It  takes  3  days  for  the  devel- 
opmental process  to  be  completed  in 
nymphs  and  4,  5  days  in  adult  ticks. 

The  above  process  is  completely  asex- 
ual.   Gonder  (1910,  1911),  however, 


thought  that  there  was  a  sexual  stage  in  the 
tick,  and  described  a  process  of  syngamy. 
Cowdry  and  Ham  (1932)  also  thought  that 
sex  was  involved,  altho  they  admitted  they 
found  no  proof  of  it.     According  to  their 
account  of  the  life  cycle,  two  types  of  para- 
site,  large  and  small,  emerge  from  the 
erythrocytes  in  the  tick's  gut  and  become 
applied  to  the  surface  of  the  gut  epithelial 
cells.     Cowdry  and  Ham  thought  that  fer- 
tilization probably  takes  place  here. 
They  said,  "Very  careful  search  was 
made  for  fertilisation  stages  without  con- 
spicuous success.     Large  and  small  para- 
sites were,  however,  occasionally  ob- 
served in  contact,  but  it  was  difficult  to 
tell  whether  this  was  merely  optical  super- 
position or  whether  actual  union  was  taking 
place„    Such  appearances  were  detected  in 
0. 1  per  cent  or  less  of  the  parasites.  " 

The  parasites  then  enter  the  intes- 
tinal cells,  the  small  forms  disappear, 
and  the  large  forms  grow  and  give  rise  to 
a  stage  without  distinct  nuclei  which  they 
called  a  zygote.    The  zygote  grows,  a 
nucleus  reappears  in  it,  and  also  a  central 
concentration  of  material.    This  central 
concentration  becomes  more  marked  and 
turns  into  a  large,  elongated,  nucleated 
organism  which  they  called  an  ookinete. 
The  ookinete  breaks  out  of  the  zygote  into 
the  gut  cell,  enters  the  body  cavity,  makes 
its  way  to  the  salivary  glands,  and  enters 
a  salivary  gland  cell.    Here  it  rounds  up 
and  grows,  surrounded  by  a  colorless  halo 
of  host  cell  cytoplasm,  becoming  so  large 
that  it  distends  the  host  cell.    Buds  ap- 
pear about  its  periphery  which  Cowdry 
and  Ham  called  sporoblasts;  the  parent 
cell  they  called  a  sporont.    The  sporo- 
blasts develop  rapidly  and  produce  sporo- 
zoites  about  their  periphery.    These  are 
discharged  into  the  lumen  of  the  salivary 
gland  acinus  and  are  introduced  into  the 
animal  when  the  tick  feeds  on  it. 

Reichenow  (1940)  criticized  the  work 
of  Cowdry  and  Ham  (1932)  severely.    He 
said  that  the  bodies  in  the  intestinal  cells 
(the  "zygotes"),  could  be  found  in  both 
infected  and  clean  ticks  and  were  there- 
fore not  a  stage  in  the  parasite's  life 
cycle.     He  found  no  structures  which  re- 
sembled ookinetes.     He  considered  the 
"sporonts"  to  be  degenerated  tissue  cells 


308 


THE  PIRCPIASMASIDA 


phagocytized  by  the  salivary  gland  cells, 
and  the  "sporoblasts"  to  be  masses  of 
coalesced  droplets  secreted  by  the  sali- 
vary gland  cells.    Gonder's  work  has  been 
discredited  not  only  by  Reichenow  but  also 
by  Cowdry  and  Ham,  Wenyon  (1926)  and 
others.     According  to  Cowdry  and  Ham, 
Gonder  did  not  distinguish  between  Theileria 
and  the  symbionts  which  are  present  in  all 
ticks,  and  substantiating  details  in  his  ac- 
count were  conspicuous  by  their  absence. 
Wenyon  said  that  his  "account  was  so  ob- 
scured by  such  theoretical  bias  that  it  is 
difficult  to  separate  fact  from  theory.  " 

A  definitive  study  is  badly  needed  to 
clear  up  the  life  cycle  of  T.  parra,   and 
one  may  hope  that  20  more  years  do  not 
pass  before  someone  carries  it  out.    In  the 
meantime,  Reichenow' s  account  is  the  most 
convincing. 

Pathogenesis:     T.  parva  is  highly 
pathogenic.    From  90  to  100%  of  affected 
cattle  die,  altho  the  mortality  is  lower  in 
endemic  areas.    In  East  Africa,  for  in- 
stance, immature  cattle  are  more  resistant 
than  adults,  and  the  mortality  among  calves 
varies  from  5  to  50%.    In  Kenya,  the  mor- 
tality varies  considerably  among  calves, 
but  adults  usually  die. 

The  incubation  period  following  tick 
transmission  is  8  to  25  days,  with  a  mean 
of  13  days.    The  disease  itself  lasts  10  to 
23  days,  with  a  mean  of  15  days.    Acute, 
subacute,  mild  and  inapparent  forms  of  the 
disease  have  been  described,  of  which  the 
acute  type  is  the  usual  one. 

In  the  acute  form,  the  first  sign  is 
fever.    The  body  temperature  varies  from 
104  to  107°  F;  it  may  continue  high  or  it 
may  decrease  after  7  to  11  days  and  then 
increase  again.    Other  clinical  signs 
usually  appear  a  few  days  after  the  initial 
rise  in  temperature.    The  animals  cease 
to  ruminate  and  to  eat.    Other  signs  are  a 
serous  nasal  discharge,  lachrymation, 
swelling  of  the  superficial  lymph  nodes, 
sometimes  swelling  of  the  eyelids,  ears 
and  jowl  region,  rapid  heart  beat,  general 
weakness,  decreased  milk  production, 
diarrhea,  frequently  with  blood  and  mucus 
in  the  feces,  emaciation,  coughing,  and 
sometimes  icterus.    Breathing  becomes 
rapid  and  dyspnea  is  pronounced  just  before 
death.    An  oligocythemic  anemia  is  pres- 


ent, but  there  is  no  hematuria  in  uncom- 
plicated cases. 

In  the  subacute  form,  which  is  often 
encountered  in  calves  and  sometimes  in 
adults  in  the  endemic  areas  of  East  Africa, 
the  signs  resemble  those  in  the  acute  form 
but  are  not  so  pronounced.    Affected  ani- 
mals may  recover,  but  it  takes  them  sev- 
eral weeks  to  return  to  normal. 

In  the  mild  form,   little  is  seen  but  a 
relatively  mild  fever  lasting  3  to  7  days, 
listlessness  and  swelling  of  the  superficial 
lymph  nodes.     An  inapparent  form  of  the 
disease  has  been  produced  by  injection  of 
blood,  coarsely  ground  spleen  and  lymph 
node  emulsions  or  suspensions  from  par- 
tially engorged,  infected  ticks. 

The  lymph  nodes  are  usually  marked 
swollen,  with  a  variable  degree  of  hyper- 
emia.    The  spleen  is  usually  enlarged, 
with  soft  pulp  and  prominent  Malpighian 
corpuscles.    The  liver  is  enlarged,  fri- 
able, brownish  yellow  to  lemon  yellow, 
with  parenchymatous  degeneration.    The 
kidneys  are  either  congested  or  pale 
brown,  with  a  variable  number  of  hemor- 
rhagic "infarcts"  or  greyish  white  lymph- 
omatomata.     The  meninges  may  be 
slightly  congested.     The  heart  is  flabby, 
with  petechiae  on  the  epicardium  and  endo- 
cardium.   The  lungs  are  often  congested 
and  edematous.    There  may  be  hydro- 
thorax  and  hydropericardium,  and  the 
kidney  capsule  may  contain  a  large  amount 
of  serous  fluid.     There  may  be  petechiae 
in  the  visceral  and  parietal  pleura,  adrenal 
cortex,  urinary  bladder,  and  mediastinum. 
There  are  characteristic  ulcers  2  to  5  mm 
or  more  in  diameter  in  the  abomasum, 
and  similar  ulcers  together  with  red 
streaks  or  patches  may  be  present  thruout 
the  small  and  large  intestines.    These 
ulcers  consist  of  a  central,  red  or  brown 
necrotic  area  surrounded  by  a  hemorrhagic 
zone.    The  Peyer's  patches  are  swollen, 
and  the  intestinal  contents  are  yellowish. 

Immunity:     Animals  which  recover 
from    T.  parva  infections  are  solidly  im- 
mune.   The  parasites  disappear  com- 
pletely, and  there  is  no  premunition. 
There  is  no  cross-immunity  between  T. 
parva  and  Goiidcria  »uitaiis.  but  there  is 
partial  cross-immunity  between  T.  parva 
and  G.  lawrencei. 


THE  PmOPLASIvL\SIDA 


309 


Diagnosis:     Diagnosis  is  based  upon 
finding  the  parasites  in  the  erythrocytes 
in  stained  blood  smears  or  in  stained 
smears  made  from  the  lymph  nodes  or 
spleen.    Differential  diagnosis  between 
East  Coast  fever  and  the  gonderioses  is 
not  always  easy,  however,  and  depends 
upon  knowledge  of  the  geographic  distribu- 
tion of  the  parasites,  symptomatology, 
pathology,   pathogenicity,  degree  of  para- 
sitemia, epidemiology  and  results  of  cross- 
immunity  tests.    The  last  is  the  best  test 
in  case  of  doubt. 

Cultivation:     Tsur-Tchernomoretz, 
Neitz,  and  Pols  (1957)  cultivated  T.  parva 
up  to  15  days  in  ox  spleen,  liver  or  lymph 
node  tissue  cultures.     The  Koch  bodies 
developed  during  the  first  10  days  but  then 
died  out.     Brocklesby  and  Hawking  (1958) 
also  grew  T.  parva  in  tissue  cultures,  but 
could  not  maintain  them  more  than  14  days. 
The  parasites  occurred  mostly  in  lymph- 
oid cells. 

Treatment:     No  drug  is  effective 
against  T.  parva  once  signs  of  disease  have 
appeared.    However,  chlortetracycline  and 
oxytetracycline  seem  to  prevent  clinical 
disease  if  given  repeatedly  during  the  in- 
cubation and  reaction  periods,   and  treated 
animals  become  solidly  immune  (Neitz, 
1957;  Barnett,  1956). 

Prevention  and  Control:    These  depend 
upon  tick  control  and  quarantine  measures. 
Immunization  by  intravenous  injection  of  a 
suspension  of  spleen  and  lymph  node  ma- 
terial from  affected  animals  was  practiced 
in  South  Africa  around  1912  to  1914,  but 
was  then  discontinued. 


Repeated,   regular  dipping  of  cattle  in 
arsenical  dips  has  been  found  effective, 
even  tho  some  arsenic -resistant  strains  of 
ticks  have  appeared.    Other  dips,  such  as 
lindane  and  toxaphene,  have  also  been  used. 


Quarantine  measures  are  also  effective 
in  preventing  the  spread  of  East  Coast  fever. 
In  isolated  outbreaks,  the  whole  herd  may 
be  slaughtered  and  the  farm  kept  free  of 
cattle  for  18  months  before  restocking. 


Genus  GONDERIA   Du  Toit,   1918 

In  this  genus  the  parasites  multiply 
by  schizogony  (or  possibly  by  a  series  of 
binary  fissions)  in  the  lymphocytes  and 
finally  invade  the  erythrocytes.    The 
forms  in  the  erythrocytes  reproduce  by 
binary  fission  into  2  or  4  daughter  indi- 
viduals.   Infection  can  be  transmitted  by 
blood  inoculation,  and  recovered  animals 
are  premunized. 


GONDERIA  ANNULATA 
(DSCHUNKOWSKY  AND   LUHS, 


1904) 


Synonyms:     Piruplasma  aiDiulatuin, 
Theileria  aiimilala,    Theileria  dispar, 
Theileria  liirkestanica.    Theileria  sergenti. 

Disease:    Tropical  gonderiosis,  trop- 
ical theileriosis,  tropical  piroplasmosis, 
Egyptian  fever,  Mediterranean  Coast  fever. 

Hosts:     Ox,  zebu,  water  buffalo.    In 
addition,  an  American  bison  in  the  Cairo 
zoo  died  of  a  natural  infection  (Carpano, 
1937). 

Location:      Lymphocytes,  erythro- 
cytes. 

Geographic  Distribution:     North 
Africa,  southern  Europe,   southern  USSR, 
India,  western  China. 

Prevalence:     Tropical  gonderiosis  is 
one  of  the  most  important  diseases  of  cat- 
tle in  North  Africa,   southeastern  Europe, 
southern  USSR  and  Asia. 

Morphology:     The  forms  in  the  ery- 
throcytes are  predominantly  (70  to  80%) 
round  or  oval,  but  may  also  be  rod- 
shaped,  comma-shaped  or  even  anaplasma- 
like.    The  round  forms  are  0.  5  to  1.  5/i  in 
diameter,  the  oval  ones  about  2.  0  by  0.  6|i , 
the  comma-shaped  ones  about  1.  6  by  0.  5/1, 
and  the  anaplasma-like  forms  0.  5ji  in 
diameter.     Binary  fission  with  the  forma- 
tion of  2  daughter  individuals  or  quadruple 
fission  with  the  formation  of  4  individuals 
in  the  form  of  a  cross  takes  place. 

The  Koch  bodies  in  the  lymphocytes 
of  the  spleen  and  lymph  nodes,  or  free  in 
these  organs,  are  similar  to  those  of  T. 
parva;  they  average  8  jll  in  diameter  but 


310 


THE  PIROPLASMASIDA 


range  up  to  15fi  or  even  27/1.    Two  types 
are  recognized:    Macroschizonts,  which 
contain  chromatin  granules  0.4  to  1.9/i  in 
diameter  and  produce  macromerozoites 
2.0  to  2.5/1  in  diameter;  and  microschi- 
zonts,  which  contain  chromatin  granules 
0.3  to  0.8  fi  in  diameter  and  produce  mi- 
cromerozoites  0.  7  to  1.0 /i  in  diameter. 

Life  Cycle:     The  vectors  of  G.  annu- 
lala  are  Hyalu»i»ia  delritum  (syn. ,   H. 
mai(relaniciuii)  in  North  Africa  and  the 
USSR,   H.  Irioicatum  in  parts  of  Africa, 
H.  dyuniedarii  in  Central  Asia,   H.   ex- 
cavalHDi  (syn. ,   H.  aimtuliciiui),  H.   turan- 
iciDu  (syn.,  //.   rufipes glabmm)  and  H. 
marginaliDii  (syns. ,  H.   savig)iyi,  H. 
aegypliuiit)  in  Asia  Minor,  and  H.  mar- 
ginatum in  India.    Transmission  is  stage- 
to-stage  in  all  cases,  and  not  thru  the  egg. 
Ray's  (1950)  and  Kornienko  and  Shmyreva's 
(1944)  claim  of  passage  thru  the  egg  has 
been  disproved  by  Delpy  (1949)  and  Daubney 
and  Sami  Said  (1951). 

The  life  cycle  of  G.  a)undata  has  been 
studied  in  H.  detritum  by  Sergent  et  al. 
(1936).    They  admitted  that  they  found  no 
stages  which  could  be  identified  as  macro- 
gametes  or  microgametes  and  that  they 
saw  nothing  which  could  be  recognized  as 
fertilization,  but  they  nevertheless  believed 
that  these  must  be  present  and  called  the 
subsequent  stage  a  zygote.    According  to 
their  account,  the  forms  ingested  by  the 
tick  are  gametocytes.    These  form  gametes 
in  the  tick's  intestine,  and  the  gametes  in 
turn  give  rise  to  zygotes.     The  zygotes 
enter  the  intestinal  epithelial  cells,  encyst, 
and  remain  in  the  lumen  of  the  intestine 
for  6  to  8  months  until  after  the  nymphal 
tick  has  hibernated  and  molted  to  the  adult 
stage.   (//.  detrition  is  a  2-host  tick,  with 
the  larva  and  nymph  on  one  host  and  the 
adult  on  the  other. )    At  this  time  they  leave 
the  cyst  and  enter  the  salivary  gland  acini, 
where  they  penetrate  the  gland  cells  and 
turn  into  sporonts.    These  give  rise  to 
sporoblasts  in  3  or  4  days,  and  the  sporo- 
blasts  in  turn  produce  a  multitude  of  sporo- 
zoites  which  break  out  of  the  cells,  enter 
the  salivary  ducts  and  are  injected  into  a 
new  host  when  the  tick  feeds.    This  life 
cycle  is  similar  to  that  described  by  Cow- 
dry  and  Ham  (1932)  for  T.  parva,    and  is 
subject  to  the  same  criticisms. 


Pathogenesis:     Tropical  gonderiosis 
is  similar  to  East  Coast  fever  in  most 
respects.     The  mortality  varies  consid- 
erably, from  10%  in  some  areas  to  90% 
in  others.    It  is  about  20  to  40%  in  Algeria, 
up  to  90%  in  enzootic  regions  of  the  USSR 
and  13  to  23%  in  indigenous  calves  in  India. 

The  incubation  period  following  tick 
transmission  is  9  to  25  days,  with  a  mean 
of  15  days.    The  disease  itself  lasts  4  to 
20  days,  with  a  mean  of  10  days.     Per- 
acute,  acute,  subacute,  mild  and  chronic 
forms  have  been  described.    The  acute 
form  is  the  usual  one.    The  first  sign  is 
fever,  the  body  temperature  rising  to  104 
to  107°  F.    The  fever  is  continuous  or 
intermittent,  and  persists  for  5  to  20  days. 
A  few  days  after  it  begins,  other  signs 
appear.    These  include  inappetence,  ces- 
sation of  rumination,  drooling,  serous 
nasal  discharge,  lachrymation,  rapid 
heart  beat,  weakness,  decreased  milk 
production  and  swelling  of  the  superficial 
lymph  nodes  and  of  the  eyelids.     Marked 
anemia  develops  in  a  few  days,  and  there 
may  be  hemoglobinuria.    Bilirubinemia 
and  bilirubinuria  are  always  present. 
Diarrhea  appears,  and  the  feces  contain 
blood  and  mucus.    The  conjunctiva  is 
icteric  and  may  bear  petechial  hemor- 
rhages.   Affected  animals  become  greatly 
emaciated,  and  their  erythrocyte  count 
may  drop  below  1  million  per  cu  mm. 
Death,  if  it  comes,  usually  occurs  8  to 
15  days  after  the  onset. 

In  the  peracute  form  of  the  disease, 
the  animals  may  die  in  3  or  4  days.    In 
the  subacute  form,  the  fever  is  usually 
irregularly  intermittent  and  lasts  up  to  10 
or  15  days,  after  which  the  animals  usually 
recover;  pregnant  animals  sometimes 
abort.    In  the  chronic  form,  intermittent 
fever,  inappetence,  marked  emaciation 
and  more  or  less  anemia  and  icterus  may 
persist  for  4  weeks  or  longer,  but  it  may 
take  2  months  before  the  animals  return 
to  normal;  in  some  cases,  the  acute  form 
may  suddenly  supervene  and  the  animals 
may  die  in  a  day  or  two.    In  the  mild  form, 
little  is  seen  but  mild  fever,  inappetence, 
listlessness,  slight  digestive  disturbances 
and  lachrymation  lasting  a  few  days. 
There  may  be  moderate  anemia. 


THE  PIROPLASIvL\SIDA 


311 


The  lymph  nodes  are  often  but  not 
always  swollen;  the  spleen  is  often  much 
enlarged.    The  liver  is  usually  enlarged. 
Infarcts  are  usually  present  in  the  kidneys. 
The  lungs  are  usually  edematous,  and 
characteristic  ulcers  are  present  in  the 
abomasum  and  often  in  the  small  and  large 
intestines. 


by  serial  passage  in  tick-free  cattle. 
Animals  are  vaccinated  by  subcutaneous 
injection  of  5  to  10  ml  of  citrated  blood 
collected  at  the  height  of  the  febrile  re- 
action.    The  blood  should  be  used  within 
3  days  after  collection.    The  mortality 
following  vaccination  is  usually  less  than 
5%. 


Mixed  infections  with  Babesia  and/or 
Aiiaplasma  are  not  uncommon;  the  result- 
ant signs  and  lesions  are  then  due  to  a 
combination  of  diseases  and  may  differ 
from  those  described  above. 

Immunity:     Animals  which  recover 
from  G.  aiiindata  infections  are  premu- 
nized.     There  is  no  cross-immunity  he- 
tvfeen  G.  annitlata,   G.  inutaiis  and  T. 
parva. 

Diagnosis:     This  is  based  upon  find- 
ing and  identifying  the  parasites  in  the 
erythrocytes  in  stained  blood  smears  or 
in  stained  smears  made  from  the  lymph 
nodes  or  spleen.    As  mentioned  under  T. 
parva,   differential  diagnosis  between 
theileriosis  and  the  gonderioses  is  not 
always  easy. 

Cultivation:     Tsur-Tchernomoretz 
(1945)  cultivated  the  Koch  bodies  of  G. 
anmdata  in  ox  tissue  cultures  thru  10 
subcultures  over  a  period  of  2  months. 
Brocklesby  and  Hawking  (1958)  grew  G. 
a)imilata  in  tissue  culture  for  over  59  days, 
and  the  cultures  were  infective  for  cattle 
when  tested  after  42  days. 

Treatment:     No  reliable  drug  is 
known  for  the  treatment  of  tropical  gon- 
deriosis  (Neitz,  1959). 

Prevention  and  Control:     Tick  control 
by  regular,  repeated  dipping  is  the  most 
important  control  measure.    Quarantine 
measures,  particularly  with  respect  to 
importation  of  livestock  from  endemic 
areas  into  regions  where  suitable  tick 
vectors  exist,  are  also  of  great  importance. 

Immunization  with  a  strain  of  low 
virulence  has  been  used  with  success  in 
North  Africa  and  Israel  (Sergent  et  al. , 
1945).    The  vaccine  strain  is  maintained 


GONDERIA  MUTANS 
(THEILER,   1906) 

Synonyms:     Piroplasnia  mutans, 
Theileria  mutans,    Theileria  buffeli, 
Theileria  orientalis. 

Disease:     Benign  bovine  gonderiosis, 
benign  bovine  theileriosis,   Tzaneen  dis- 
ease, Marico  calf  disease,  mild  gallsick- 
ness. 

Hosts:     Ox,  zebu.    The  water  buffalo 
and  African  buffalo  (Syncerus  caffer)  can 
be  infected  experimentally  but  without 
causing  death. 

Location:      Lymphocytes,  erythro- 
cytes. 

Geographic  Distribution:     Africa, 
Asia,  southern  Europe,   England,  USSR, 
Australia,  North  America. 

Prevalence:     G.  muta)is  is  endemic 
thruout  Africa,  in  the  great  part  of  Asia, 
and  in  many  areas  of  the  USSR  and  south- 
ern Europe.    It  has  been  reported  by 
Splitter  (1950)  in  Kansas. 

Morphology:     The  forms  in  the  ery- 
throcytes are  round,  oval,   piriform, 
comma-shaped  or  anaplasma-like.    About 
55%  are  round  or  oval.     The  round  forms 
are  1  to  2|m  in  diameter  and  the  oval  ones 
about  1.  5  by  0.  6;i .     Binary  and  quadruple 
fission  occur  in  the  erythrocytes. 

There  are  relatively  few  Koch  bodies 
in  the  lymphocytes  of  the  spleen  and 
lymph  nodes  or  free  in  these  organs.    They 
average  8ju,  in  diameter  but  may  range  up 
to  20  (Lt.     They  contain  1  to  80  chromatin 
granules  from  1  to  2|n  in  diameter,  and 
are  practically  all  of  the  macroschizont 


312 


THE  PIROPLaiSMASIDA 


type.    Merozoites  have  apparently  not  been 
seen,  but  they  must  occur. 


Life  Cycle:     The  vectors  of  G.  miitans 
in  Africa  are  Rhipiceplialiis  appendiculalus 
and  R.  everlsi.     In  addition,  Boophilus 
annulatus  has  been  found  to  be  able  to 
transmit  this  species  experimentally. 
Transmission  is  stage-to-stage. 

The  stages  in  the  tick  vectors  are  un- 
known. 


GONDERIA   LAWRENCEI 

(NEITZ,   1955) 

NEITZ  AND  JANSEN,    1956 

Synonyms:      Theileria  lawrencei, 
Gonderia  bouts. 

Disease:     Corridor  disease,  buffalo 
disease,  malignant  syncerine  gonderiosis, 
Rhodesian  malignant  bovine  gonderiosis. 

Hosts:  Cattle,  African  buffalo  {Syn- 
cerus  coffer).  The  buffalo  is  the  natural 
host. 


Pathogenesis:     G.  mutans  is  seldom 
more  than  slightly  if  at  all  pathogenic, 
altho  an  acute  form  of  the  disease  may 
develop  in  cattle  imported  into  an  endemic 
area  and  exposed  to  massive  tick  infesta- 
tion.   The  mortality  is  less  than  1%. 

The  signs,  course  of  the  disease  and 
lesions  resemble  those  of  mild  G.  anmdata 
infections.    Anemia,  if  present,  is  slight. 
Icterus  is  sometimes  present,  and  the 
lymph  nodes  are  moderately  swollen.    In 
acute  cases  the  spleen  and  liver  are 
swollen,  the  lungs  may  be  edematous,  there 
are  characteristic  ulcers  in  the  abomasum, 
and  infarcts  may  be  present  in  the  kidneys. 
Hematuria  is  absent. 

The  incubation  period  following  tick 
transmission  is  10  to  20  days  with  a  mean 
of  15  days.    The  disease  lasts  3  to  10  days 
with  a  mean  of  5  days. 

Splenectomy  may  cause  the  appearance 
of  parasites  in  the  blood,  and  indeed  Split- 
ter (1950)  first  observed  them  in  a  splen- 
ectomized  calf. 

Immunity:     Animals  which  have  once 
been  infected  with  G.  mutans  are  premu- 
nized.    There  is  no  cross-immunity  be- 
tween G.  mutans  and  G.  annulata,   G. 
lawrencei  and  T.  parva. 

Diagnosis:     Same  as  for  other  species 
of  Gonderia  and  Theileria. 


Location:     Lymphocytes,  erythrocytes. 

Geographic  Distribution:     Union  of 
South  Africa,  Southern  Rhodesia. 

Prevalence:     This  disease  is  widely 
distributed  in  Southern  Rhodesia,  both  in 
cattle  and  African  buffaloes.    In  the  Union 
of  South  Africa  its  distribution  is  much 
more  restricted,  and  it  occurs  only  in 
cattle  which  have  come  in  contact  with 
ticks  from  premune  African  buffaloes.    It 
takes  its  name  from  the  fact  that  it  was 
first  found  here  in  the  Corridor,  a  stretch 
of  100  square  miles  of  land  between  the 
Hluhluwe  and  Umfolozi  Game  Reserves 
where  buffalo  abound.    It  has  also  been 
found  around  Kriiger  National  Park. 

Morphology:     The  erythrocytic  stages 
are  oval,  round,  piriform  or  comma- 
shaped,  and  indistinguishable  from  those 
of  G.  mutans.     About  55%  are  round  or 
oval. 

There  are  relatively  few  Koch  bodies 
in  the  lymphocytes  of  the  spleen  and  lymph 
nodes  or  free  in  these  organs.    They  aver- 
age 5(i  in  diameter  but  may  range  up  to 
lOjLt.     They  contain  1  to  16  or  32  reddish 
purple  granules  0.  5  to  2):i  in  diameter  and 
are  practically  all  of  the  macroschizont 
type.    The  mature  macromerozoites  are 
2.0  to  2.  5  fx  in  diameter,  and  the  mature 
micromerozoites  are  0.7  to  1.0 /i  in  diam- 
eter. 


Treatment:     None  known. 


Prevention  and  Control:     These  de- 
pend upon  tick  control. 


Life  Cycle:     The  vector  is  Rhipi- 
cephalus  appendiculalus,   and  transmission 
is  stage-to-stage.    The  parasite  stages  in 
the  tick  are  unknown. 


THE  PIROPLASMASIDA 


313 


Pathogenesis:     Corridor  disease  is 
similar  to  East  Coast  fever  and  tropical 
gonderiosis  in  its  manifestations,    G. 
lawrencei  is  highly  pathogenic  for  cattle, 
the  mortality  being  about  80%.    African 
buffaloes,  however,  are  highly  resistant 
and  serve  as  the  reservoir  of  infection  for 
cattle. 

The  incubation  period  following  tick 
transmission  is  12  to  20  days,  with  a  mean 
of  15  days.    The  disease  itself  lasts  5  to 
15  days,  with  a  mean  of  10  days.    Peracute, 
acute,  subacute  and  mild  forms  have  been 
described.    The  acute  form  is  the  usual  one. 

There  is  usually  no  anemia,  altho 
oligocythemia  may  occur.    Icterus  may  be 
present,  but  hematuria  is  not.    The  lymph 
nodes,  spleen  and  liver  are  often  swollen, 
edema  of  the  lungs  is  pronounced,  char- 
acteristic ulcers  are  usually  present  in 
the  abomasum,  and  infarcts  are  some- 
times present  in  the  kidneys. 

Immunity:     Animals  which  recover 
from  infection  with  G.  lawrencei  are  pre- 
mune.    There  is  no  cross-immunity  be- 
tween this  species  and  G.  miitans,    but 
there  is  partial  or  complete  cross-immun- 
ity between  it  and  T.  parva. 

Diagnosis:     Same  as  for  other  species 
of  Gonderia  and  Theileria. 

Treatment:     No  effective  drugs  are 
known  for  the  treatment  of  Corridor  dis- 
ease, but  there  is  some  evidence  that 
chlortetracycline  may  suppress  the  dis- 
ease if  given  repeatedly  during  the  incu- 
bation and  patent  periods. 

Prevention  and  Control:     These  de- 
pend upon  tick  control  and  upon  prevention 
of  association  between  cattle  and  African 
buffaloes. 


GONDERIA  HIRCI 
(DSCHUNKOWSKY  AND 
URODSCHEVICH,   1924) 

Synonyms:     Theileria  hirci,   Theil- 
eria ovis  du  Toit,   1918;  non  T.  ovis 
Rodhain,  1916. 


Disease:     Malignant  ovine  and  cap- 
rine gonderiosis,  malignant  ovine  and 
caprine  theileriosis. 

Hosts:     Sheep,  goat. 

Location:      Lymphocytes,  erythro- 
cytes. 

Geographic  Distribution:     North 
Africa,  southeastern  Europe,  southern 
USSR,  Asia  Minor. 

Morphology:     The  erythrocytic 
stages  are  about  80%  round  or  oval,  18% 
rod-shaped  and  2%  anaplasma-like.   The 
round  forms  are  0.6  to  2.0jj.  in  diameter 
and  the  more  elongate  ones  about  1.6/j, 
long.     Binary  or  quadruple  fission  takes 
place  in  the  erythrocytes. 

Koch  bodies  are  common  in  the 
lymphocjrtes  of  the  spleen  and  lymph  node 
smears  or  free  in  these  organs.    They 
average  8)iji  in  diameter  but  may  range  up 
to  10  or  even  20):x .    They  contain  1  to  80 
reddish  purple  granules  from  1  to  2(i  in 
diameter.    Both  macroschizonts  and  mi- 
croschizonts  can  be  found.    These  produce 
merozoites  1  to  2;i  in  diameter. 

Life  Cycle:     The  vector  is  unknown, 
but  is  possibly  Rhipicepfialus  bursa. 

Pathogenesis:     This  species  is  highly 
pathogenic  for  sheep  and  goats,  mortal- 
ities of  46  to  100%  having  been  reported 
in  these  animals.    The  disease  is  rela- 
tively mild  in  young  lambs  and  kids  in 
endemic  areas. 

The  incubation  period  is  unknown. 
The  disease  itself  lasts  5  to  42  days. 
Acute,  subacute  and  chronic  forms  have 
been  described,  the  acute  form  being  the 
usual  one. 

The  disease  resembles  tropical  bovine 
gonderiosis  in  its  manifestations.    There 
is  fever  following  by  listlessness,  nasal 
discharge,  atony  of  the  rumen  and  weak- 
ness.   Affected  animals  are  anemic,  and 
icterus  is  frequently  present.     There  is 
often  a  transitory  hemoglobinuria.    The 
lymph  nodes  are  always  and  the  liver 


314 


THE  PIROPLASMASIDA 


usually  swollen,  the  spleen  is  markedly 
enlarged,  the  lungs  are  edematous,  in- 
farcts are  often  present  in  the  kidneys, 
and  there  are  petechiae  on  the  mucosa  of 
the  abomasum  and  irregularly  disseminated 
red  patches  on  the  intestinal  mucosa,  par- 
ticularly in  the  cecum  and  large  intestine. 

Immunity:     Animals  which  recover 
from  the  disease  are  premune.    There  is 
no  cross-immunity  between  this  species 
and  G.  ovis. 

Diagnosis:     This  depends  upon  iden- 
tification of  the  parasites  in  stained  blood, 
lymph  node  or  spleen  smears.    In  contrast 
with  G.  ovis,  the  erythrocytic  stages  are 
usually  present  in  relatively  large  num- 
bers, and  Koch  bodies  are  common  in  the 
lymph  nodes  and  spleen.    Inoculation  of 
susceptible  sheep  or  goats  may  also  be 
resorted  to. 

Treatment:     None  known. 

Prevention  and  Control:     These  depend 
upon  tick  control. 


GONDERIA   OVIS 

(RODHAIN,   1916)  LESTOQUARD,   1929 

Synonyms:  Theileria  ovis  Rodhain, 
1916;  Babesia  sergenii,  Theileria  recon- 
dita,   Theileria  sergenti. 

Disease:     Benign  ovine  and  caprine 
gonderiosis,  benign  ovine  and  caprine 
theileriosis. 

Hosts:     Sheep,  goat. 

Location:     Lymphocytes,  erythrocytes. 

Geographic  Distribution:     Africa, 
Europe,  USSR,  India,  western  Asia.     This 
species  is  much  more  widely  distributed 
than  G.  hirci. 

Morphology:     The  erythrocytic  stages 
resemble  those  of  G.  hirci  in  shape  and 
size,  but  are  much  sparser  in  infected 
animals,  less  than  2%  of  the  erythrocytes 
being  infected  in  non-splenectomized  ani- 
mals.   The  Koch  bodies  resemble  those  of 


G.  hirci,   but  have  been  found  only  in  the 
lymph  nodes  and  then  only  after  prolonged 
examination. 

Life  Cycle:     The  vectors  are  Rhipi- 
cephalus  bursa  in  the  USSR,   North  Africa 
and  Asia,  andR.  euerlsi  in  South  Africa. 
Transmission  with  OrnitJiodoros  lahoren- 
sis,  Dermacentor  silvariuii  and  Haeiiia- 
physalis  sulcata  has  been  claimed  in  the 
USSR  (Bitukov,  1953),  but  this  claim  is 
dubious  (Neitz,  1959). 

The  stages  in  the  tick  are  unknown. 

Pathogenesis:     This  species  is  non- 
pathogenic or  practically  so.    The  incuba- 
tion period  following  tick  transmission  is 
9  to  13  days,  and  the  disease  lasts  5  to 
16  days.    The  only  signs  are  fever,  swell- 
ing of  the  lymph  nodes  in  the  region  of 
tick  attachment,  and  slight  anemia.    These 
would  normally  be  overlooked  in  the  field. 

Immunity:     Animals  which  have  been 
infected  are  premune.     There  is  no  cross- 
immunity  between  G.  ovis  and  G.  hirci. 

Diagnosis:     This  depends  upon  iden- 
tification of  the  parasites  in  stained  blood 
or  lymph  node  smears.     G.  ovis  is  mor- 
phologically indistinguishable  from  G. 
hirci,    but  the  small  number  of  parasites 
present  and  their  lack  of  pathogenicity 
may  help  to  differentiate  them.     Cross- 
immunity  tests  may  be  carried  out  if  de- 
sired. 

Treatment:     None  known. 

Prevention  and  Control:     These  de- 
pend upon  tick  control. 


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The  members  of  the  class  Toxoplas- 
masida  have  been  and  still  are  a  headache 
to  taxonomists.    Their  affinities  to  other 
protozoa  are  uncertain,  and  some  people 
have  even  questioned  whether  some  of 
them  are  protozoa  at  all,  preferring  to 
assign  them  to  the  fungi.    Until  recently, 
no  relationship  was  recognized  between 
Sarcocystis  and  Toxoplasma,  the  2  main 
genera,  but  it  has  become  increasingly 
clear  that  they  have  many  resemblances 
(Manwell  and  Drobeck,   1953).     Even  the 
names  given  to  the  trophozoites  and  to  the 
order  have  been  wrong;  they  were  influ- 
enced by  the  belief  (shown  to  be  mistaken 
by  Perrier  as  long  ago  as  1907)  that  the 
trophozoites  are  spores.    Much  of  our 
difficulty  is  due  to  lack  of  information. 
As  we  learn  more  and  more,  and  as  new 
facts  fall  into  place,  our  understanding  of 
the  group  will  improve  and  we  can  expect 
that  some  of  our  present  ideas  may  change. 
The  classification  adopted  here  is  consid- 
ered reasonable  and  useful,  but  it  is  not 
necessarily  definitive. 

All  members  of  this  class  are  para- 
sitic.   They  have  no  spores.    They  produce 
cysts  or  pseudocysts  containing  many  naked 
trophozoites  (sometimes  called  schizo- 
zoites,  altho  the  existence  of  schizogony  is 
dubious,  and  often  erroneously  called 
spores  or  sporozoites).    They  are  mono- 
xenous  and  reproduce  asexually.    They 
lack  pseudopods,  flagella  and  cilia,  and 
move  by  body  flexion  or  gliding. 

There  is  a  single  order,  Toxoplas- 
morida,  with  the  characters  of  the  class. 
It  contains  2  families,  Sarcocystidae  and 
Toxoplasmatidae,  both  of  which  contain 
parasites  of  domestic  animals  and  man. 
(It  is  possible  that  the  distinction  between 
these  families  is  artificial,  but,  pending 
further  research,  it  is  probably  best  to 
retain  them. ) 


C/fapter  12 


SARCOCYSTIS 

TOXOPLASMA 

Am  RELATED 

PROTOZOA 


FAMILY   SARCOCYSTIDAE 

Members  of  this  family  form  cysts. 
They  multiply  by  binary  fission  and 


317 


318 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


perhaps  also  in  the  young  cysts  by  schi- 
zogony.   There  is  a  single  genus,  Sarco- 
cystis.    The  group  has  been  reviewed  by 
Babudieri  (1932),  Scott  (1930,   1943), 
Barreto  (1940),   Erickson  (1940),  Grasse 
(1953)  and  Eisenstein  and  Innes  (1956). 

Genus  SARCOCYSTIS 
Lankester,    1882 

In  this  genus  the  cysts  are  found  in 
the  striated  and  heart  muscles,  and  are 
usually  divided  into  compartments  by  in- 
ternal septa.    Synonyms  of  this  name  are 
Miesclieria  Blanchard,   1885  and  Balbiania 
Blanchard,  1885. 

Sarcocystis  is  common  in  many  spe- 
cies of  animals.    It  is  found  in  the  great 
majority  of  sheep,  cattle,  horses  and 
swine,  and  is  often  seen  in  wild  ducks. 
It  is  extremely  rare,  however,   in  car- 
nivores such  as  the  dog  and  cat,  and  the 
reports  of  its  presence  in  these  animals 
require  verification.    Dogs  cannot  be  in- 
fected experimentally  (Pfeiffer,   1891). 

More  than  50  species  of  Sarcocystis 
have  been  named,  but  it  is  not  at  all  cer- 
tain that  they  are  all  valid.    They  are 
differentiated  on  the  basis  of  the  host  in 
which  they  occur,  the  structure  of  the 
cyst  wall  and  the  size  of  the  trophozoites. 
However,  Sarcocystis  is  not  very  host- 
specific.    The  rat  and  guinea  pig  can  be 
infected  with  the  form  from  the  mouse, 
the  mouse,  guinea  pig,  chicken  and  duck 
with  that  from  the  sheep,  and  the  rat  and 
mouse  with  that  from  the  pig.    In  addition, 
the  same  species  does    not  look  the  same 
in  all  hosts.    For  example,  in  the  guinea 
pig  the  trophozoites  of  the  form  from  the 
mouse  are  only  half  their  former  size  and 
the  cysts  do  not  have  alveoli.     Finally, 
the  structure  of  the  cyst  wall  may  vary 
with  its  age  even  in  the  same  host.     The 
specific  names  below  are  therefore  used 
more  as  a  matter  of  convenience  and 
custom  than  from  any  conviction  that  they 
are  all  necessarily  valid. 

Morphology:     The  cysts  are  known 
as  Miescher's  tubules  and  are  easily  vis- 
ible to  the  naked  eye.    They  are  usually 
cylindroid  or  spindle-shaped,  running 


lengthwise  in  the  muscles,  but  they  may 
also  be  ellipsoidal  or  rather  irregular. 
They  vary  in  size  depending  in  part  on  the 
host.    The  ellipsoidal  cysts  in  the  sheep 
may  reach  1  cm  in  diameter,  but  consid- 
erably smaller  ones  are  the  rule.    Those 
in  the  duck  are  1  or  2  mm  in  diameter  and 
1  cm  or  more  long. 

The  cyst  wall  varies  in  appearance 
with  the  species.    There  are  3  types.    In 
one,  e.  g. ,   Sarcocystis  nuiris  of  the  mouse, 
it  is  smooth.    In  another,  e.  g. ,   S.  platy- 
dactyli  of  the  gecko,  it  has  an  outer  layer 
of  radial  spines,  villi  or  fibrils  called 
cytophaneres.    In  a  third,  e.g.,  S.  lenella 
of  the  sheep,  the  wall  is  smooth  in  the 
young  cysts,  acquires  a  layer  of  cyto- 
phaneres as  the  cysts  develop,  and  then 
loses  it  when  they  become  old. 

The  cyst  wall  of  S.   tenella  is  com- 
posed of  2  thick  layers  (Ludvik,   1958). 
The  inner  one  is  homogeneous  and  contains 
nuclei.     Extensions  from  it  form  septa  be- 
tween the  compartments  in  the  cyst.     The 
outer  layer  contains  no  nuclei  and  appears 
spongy  in  electron  micrographs.    It  forms 
the  cytophaneres.    The  inner  layer  con- 
tains RNA  and  the  outer  a  polysaccharide. 
The  cyst  wall  is  essentially  negative  to  the 
periodic  acid-Schiff  test,  altho  the  cyto- 
phaneres stain  slightly  according  to  Fren- 
kel  (1956a). 

The  cyst  wall  of  S.  »iiesclieriaiia  dif- 
fers from  that  of  S.  teiielta  in  being  com- 
posed of  only  a  single  layer  with  a  com- 
plicated surface  structure  (Ludvik,   1960). 
The  cytoplasm  of  the  wall  is  granulated, 
and  fine  septa  project  from  its  inner  sur- 
face to  divide  the  interior  of  the  cyst  into 
small  compartments.     The  outer  surface 
of  the  cyst  wall  is  spongy,  with  a  fine 
honeycomb  structure.    It  sends  numerous 
parallel,  hollow,  finger-like  projections 
or  villi  into  the  surrounding  muscle  tissue. 
These  villi  may  be  as  much  as  8  to  10 /^ 
long,  and  are  circular  or  ellipsoidal  in 
cross  section  and  about  0.  7  to  0.  8  /i  in 
diameter.     They  contain  slender,  long 
double  fibrils  100  A  thick. 

There  is  a  difference  of  opinion  as  to 
whether  the  cyst  wall  is  formed  by  the 


SARCOCYSTIS,    TOXOPLASMA   AND  RELATED  PROTOZOA 


319 


parasite  or  the  host.    A  few  authors,  such 
as  Wang  (1950),  think  that  the  host  forms 
both  layers,  but  this  view  is  probably  not 
correct.    Some,   such  as  Chatton  and  Avel 
(1923)  and  Barretto  (1940),  think  that  the 
parasite  forms  both  layers.    Others,  such 
as  Scott  (1943),  think  that  the  parasite 
forms  the  inner  layer  and  the  host  the 
outer;  still  others,  such  as  Babudieri 
(1932),  think  that  the  whole  cyst  wall  is 
formed  by  the  parasite  in  S.   ))uiris  and 
similar  species,  and  that  one  layer  is 
formed  by  the  parasite  and  the  other  by 
the  host  in  S.  teiiella  and  similar  species. 


According  to  Ludvik  (1960),  the  single- 
layered  cyst  wall  of  S.  iiiiesclieriana  is 
quite  certainly  formed  by  the  parasite,  and 
the  villi  which  project  into  the  muscle  tissue 
take  up  nutritive  material  from  the  host. 

The  trophozoites  are  banana-shaped 
when  mature,  with  the  anterior  end 
slightly  pointed  and  the  posterior  end 
rounded.     They  are  6  to  15|i  long  and  2 
to  4/i  wide,  varying  in  size  with  the  spe- 
cies.    They  move  by  gliding  or  body 
flexion,  twisting,  turning,  or  following  a 
spiral  path. 


SARCONEMES 
DISCOID   GRANULE 


CENTRAL 
GRANULES 


POLAR    RING 
TOXONEME 


PELLICULAR 
FIBRILS 


MITOCHONDRION 


POLAR  RING 


SARCONEMES 


NUCLEUS 

MITOCHONDRION 

TROPHOZOITE    OF    SARCOCYSTIS  TENELLA 


Fig.  36.      Trophozoite  oi  Sarcucyslti  tciiella.     (After  Ludvik,   1958) 


Ludvik  (1958,   1960)  described  their 
structure  in  S.  lenella  and  S.  niiescher- 
iaiia  on  the  basis  of  electron  microscope, 
cytochemical  and  light  microscope  studies. 
At  the  anterior  end  within  the  pellicle  is  a 
polar  ring  0.4  to  0.  5j_i  in  diameter,  and 
within  it  is  a  hollow,  truncate  cone  0.  3  to 
0.4|i  long  known  as  a  conoid.     From  the 
polar  ring  22  to  26  fine  fibrils  run  back- 
wards in  the  pellicle  the  full  length  of  the 
body.    In  some  individuals  short,  club- 
shaped  structures  similar  to  the  toxo- 
nemes  of  Toxoplasma  can  be  seen  in  the 
cytoplasm  beneath  the  pellicle. 

The  cell  body  is  divisible  into  3  zones. 
The  anterior  third  of  the  body,  the  so- 
called  fibrillar  zone,  is  filled  with  a  large 


number  (about  300  to  350)  of  parallel, 
equidistant  fibrils  or  perhaps  channels 
about  50  nijLt  in  diameter,  the  sarconemes. 
They  probably  arise  from  the  conoid,  and 
they  end  abruptly.    Just  under  the  pellicle 
on  the  dorsal  (convex)  side  about  the  mid- 
dle of  the  fibrillar  zone  is  a  disc-shaped 
granule  which  stains  with  Bodian  silver. 

The  middle  third  of  the  body  contains 
a  large  number  of  spherical  granules  0.4 
to  0.  5fi  in  diameter,  the  so-called  central 
granules.    They  impregnate  with  osmium 
and  stain  intensely  with  Heidenhain's  hema- 
toxylin but  not  with  Giemsa.    In  the  same 
region  are  many  minute  granules,  some  of 
which  contain  volutin  and  others  RNA. 
There  are  also  1  or  2  large  vacuoles  which 
stain  with  neutral  red. 


320 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


The  posterior  third  of  the  body  con- 
tains the  nucleus.    It  is  an  ellipsoidal 
vesicle  almost  as  wide  as  the  body,  and 
contains  a  relatively  small  number  of 
chromatin  granules  and  an  endosome  which 
stains  with  Bodian  silver.    The  nucleus  is 
surrounded  by  a  large  number  of  small 
vacuoles  and  granules,  many  of  which  con- 
tain glycogen,  and  these  extend  to  the 
posterior  end  of  the  body.    Among  them 
lie  1  to  3  serpentine  mitochondria  0. 15  to 
0.2/i  in  diameter  and  2/i  or  more  long. 

In  addition  to  the  above  structures,  a 
network  of  fibrils  forming  a  characteristic 
rectangular  pattern  can  be  seen  on  the  sur- 
face following  silver  impregnation  by  the 
Klein  or  Chatton  technics. 

Life  Cycle:     Several  differing  accounts 
have  been  given  of  the  life  cycle  oiSarco- 
cystis.     Pitfalls  in  its  study  have  been  dis- 
cussed by  Scott  (1943).    There  is  now  gen- 
eral agreement  that  the  life  cycle  is  sim- 
ple, without  sexual  stages,  and  that  no 
intermediate  host  is  involved. 

Animals  become  infected  by  ingesting 
trophozoites,   either  in  unbroken  cysts  in 
the  muscles  or  free  in  the  feces  of  other 
animals.    Smith  (1901,  1905)  was  the  first 
to  show  that  infection  took  place  by  the 
oral  route,  and  was  able  to  maintain  the 
infection  with  S.  maris  in  mice  for  7  years 
by  feeding  infected  mouse  muscle. 

The  trophozoites  presumably  pass 
thru  the  intestinal  wall,  enter  the  blood 
stream  and  are  carried  to  the  striated 
muscles,  where  they  enter  the  muscle 
cells.    They  are  found  in  the  striated  and 
heart  muscles.    They  are  especially  com- 
mon in  the  wall  of  the  esophagus,  but  are 
also  found  in  the  tongue,  masseter  muscle, 
diaphragm,  throat,  neck,  body  and  limb 
muscles,  and  even  in  the  eye  muscles  and 
Purkinje  fibers  of  the  heart  among  other 
places.    In  ducks  they  are  most  commonly 
found  in  the  breast  muscles. 

There  is  a  latent  period  of  a  month  to 
6  weeks  or  more  during  which  almost 
nothing  is  known  of  what  happens.      The 
first  stage  in  the  muscle  cell  is  a  one- 
celled,  irregularly  rounded  ("amoeboid") 
naked  parasite.    This  divides  by  repeated 


binary  fissions  (Scott,  1943)  into  a  number 
of  rounded  cells  4  to  8^t  in  diameter  which 
are  enclosed  in  a  cyst  wall.    Betegh  and 
Dorcich  (1912),  Erdmann  (1914)  and  Arai 
(1925)  thought  that  schizogony  takes  place 
at  this  stage,  but  Scott  (1943)  did  not 
agree,  and  Frenkel  (1956a)  considered  its 
existence  doubtful. 

The  rounded  cells  have  been  called 
sporoblasts,  pansporoblasts  or  prosporo- 
blasts,  but  these  names  all  carry  the  con- 
notation that  the  trophozoites  are  spores, 
and  the  cells  are  better  called  cytomeres 
(Grasse',  1953)  or  trophoblasts.    They  con- 
tinue to  reproduce  by  binary  fission,  and 
become  pressed  together  and  polygonal. 
Later  they  change  into  ellipsoidal  and  then 
into  banana-shaped  trophozoites. 

As  multiplication  proceeds,  the  cyst 
grows  and  is  divided  into  chambers  or 
compartments  by  septa  arising  from  the 
inner  layer  of  the  cyst  wall.    The  process 
continues,  new  trophoblasts  are  formed 
at  the  periphery  of  the  cysts,  produce  new 
trophozoites,  and  new  septa  are  laid  down 
and  new  compartments  formed. 

The  trophozoites  themselves  also  re- 
produce by  binary  fission.    This  process 
was  described  by  Ludvik  (1958).    The 
nucleus  first  begins  to  enlarge  and  the 
dispersed  chromatin  forms  large  granules 
and  variously  curved  structures.    The 
nucleus  is  indented  in  the  middle  of  its 
anterior  edge  and  becomes  horseshoe- 
shaped.    The  cell  loses  its  banana  shape 
and  becomes  broadly  spindle-shaped,  with 
a  rounded  posterior  end.    The  central 
granules  become  dispersed  thru  the  whole 
cell  and  diminish  in  size.    A  medial  sac- 
like structure  begins  to  be  separated  off 
from  the  posterior  part  of  the  horseshoe- 
shaped  nucleus,  and  the  central  granules 
disappear.    The  sac -like  structure  be- 
comes detached  from  the  nucleus  and 
gradually  divides  into  2  halves  which  later, 
after  the  true  nuclear  division  has  been 
completed,  disappear.    The  horseshoe- 
shaped  nucleus  divides  into  2  longitudinal 
segments.    The  conoid  and  cj^oplasm  in 
the  anterior  third  of  the  cell  also  divide 
into  2  longitudinal  halves  with  a  clear 
streak  between  them.    The  newly  formed 
nuclei  become  shorter  and  their  chromatin 


SARCOCYSTIS,   TOXOPLASMA   AND  RELATED   PROTOZOA 


321 


gradually  disperses.     Cell  division  now 
begins,  starting  from  the  conoid  at  the 
anterior  end  and  proceeding  posteriorly. 
The  nuclei  round  up,  their  nucleoplasm 
becomes  thicker,  and  they  move  toward 
the  posterior  part  of  the  newly  forming 
cells.     New  central  granules  appear  in  the 
cytoplasm  in  front  of  the  nuclei.    The 
daughter  cells  remain  attached  at  their 
posterior  ends  for  a  time  and  then  separ- 
ate entirely. 

Finally,  as  the  cyst  itself  becomes 
older,  the  trophozoites  in  the  central  com- 
partments degenerate  and  disappear. 
After  the  cyst  becomes  mature,  its  wall 
breaks  down  and  the  trophozoites  are  re- 
leased.   They  enter  the  blood  stream, 
reach  the  digestive  tract,  and  pass  out  in 
the  feces.    They  have  also  been  found  in 
the  nasal  secretions  of  sheep  (Scott,  1943). 

Quite  a  different  account  has  been 
given  by  Spindler  and  his  associates,  who 
believe  Sarcocystis  to  be  a  fungus  rather 
than  a  protozoon.    Spindler  and  Zimmer- 
man (1945)  reported  that  they  had  isolated 
an  Aspergillus  -like  fungus  from  sarco- 
cysts  from  pig  muscles,  and  that  25  out  of 
50  pigs  injected  with  or  fed  material  from 
the  cultures  had  sarcocysts  in  their  mus- 
cles 4  to  6  months  later,  while  the  control 
pigs  were  negative.    They  also  said  that 
pigs,  rats  and  mice  fed  the  cysts  passed 
yeast-like  bodies  in  their  urine  or  feces 
which  produced  a  similar  fungus  upon  cul- 
ture, and  they  found  these  bodies  in  the 
kidneys  of  infected  mice  and  in  clumps 
attached  to  the  walls  of  the  ileum  and  ce- 
cum of  infected  rats  and  mice. 

Spindler,   Zimmerman  and  Jaquette 
(1946)  were  unable  to  infect  pigs  directly 
with  sarcocysts  in  pig  muscles,  but  they 
observed  that  the  pigs  became  infected  if 
they  ate  their  own  feces.    They  fed  pork 
containing  sarcocysts  to  pigs,  dogs,  cats, 
rats,  mice  and  chickens.    These  subse- 
quently passed  a  stage  in  their  feces  and/or 
urine  which  was  infective  for  swine.    Their 
observation,  incidentally,  may  perhaps  ex- 
plain the  remark  of  Scott  (1943)  that  feed- 
ing experiments  in  sheep  indicate  that  the 
trophozoites  of  S.  tenella  must  undergo 
some  change  before  they  can  infect  other 
sheep. 


Spindler  (1947)  described  a  network  of 
jointed,   hypha-like  structures  in  cysts 
from  a  sheep  and  a  duck,  and  said  that  the 
trophozoites  appeared  to  be  exogenous 
growths  on  these  structures.     However, 
Grass^  (1953)  commented  that  his  illustra- 
tions were  not  convincing,  and  that  the 
structures  he  described  appeared  to  be  the 
result  of  marked  alterations  in  the  true 
ones.     Frenkel  (1956a),  too,  disagreed 
with  Spindler.    He  found  no  fungal  charac- 
teristics in  morphological  studies  of  or- 
ganisms from  man,  the  sheep,  mouse, 
rabbit,  squirrels  and  the  duck.     Unlike 
fungi,  the  trophozoites  and  cyst  walls  did 
not  give  a  positive  reaction  with  the  per- 
iodic acid-Schiff  stain.    Sarcocystis  from 
cottontail  rabbits  and  house  mice  failed  to 
grow  on  the  media  customarily  used  for 
fungi.     Frenkel  concluded  that  these  or- 
ganisms neither  look  nor  behave  like  fungi. 

Scott  (1943),  too,  and  others  cited  by 
him  were  unable  to  cultivate  organisms 
from  the  cysts.    Only  Ciesla  (1950)  has 
reported  positive  results.    He  observed 
"sporozoites"  in  cultures  from  cysts  from 
cattle,  and  said  that  these  eventually  turned 
into  round  corpuscles  with  a  quick,  convul- 
sive type  of  movement  which  budded  into 
branched  chains  of  mycelia. 

The  weight  of  the  evidence  thus  indi- 
cates that  Sarcocystis  is  a  protozoon  and 
not  a  fungus. 

Pathogenesis:    Sarcocystis  is  not 
generally  considered  very  pathogenic. 
However,  Scott  (1943a)  believed  that  it  is 
of  greater  economic  importance  than  is 
usually  supposed. 

Light  or  moderate  infections  produce 
no  noticeable  signs,  but  in  very  heavy  in- 
fections there  may  be  lameness,  weakness, 
emaciation,  paralysis  and  even  death. 

The  sarcocyst  destroys  that  part  of 
the  muscle  fiber  which  it  occupies,  and  as 
it  grows  it  may  cause  pressure  atrophy  of 
adjacent  cells.    Calcification  may  also 
occur.    There  is  ordinarily  little  if  any 
cellular  reaction  around  the  cysts.    Focal 
myocarditis  and  myositis  develop  when  the 
cysts  break  down.    Destombes  (1957)  des- 
cribed a  marked  inflammatory  reaction 


322 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


around  the  cysts  followed  by  necrosis  and 
calcification  in  swine,  but  saw  no  such  re- 
action in  cattle.    Spindler,   Zimmerman 
and  Jaquette  (1946)  found  that  pigs  with  40 
or  more  cysts  per  gram  of  diaphragm 
were  unthrifty  and  showed  signs  of  mus- 
cular stiffness. 

Gastrointestinal  signs  and  lesions 
may  occur  after  ingestion  of  the  cysts. 
Scott  (1943)  reported  extensive  destruction 
of  the  epithelium  together  with  a  bloody 
serous  exudate  in  the  ileum  of  young  rats 
fed  sarcocysts  from  sheep,  and  the  an- 
imals appeared  ill  and  disinclined  to  move 
about.    Spindler,   Zimmerman  and  Jaquette 
(1946)  observed  vomiting,  diarrhea,   in- 
appetence  and  temporary  posterior  paraly- 
sis in  pigs  fed  infected  muscles,  urine  or 
feces. 

The  cysts  contain  a  powerful  endo- 
toxin known  as  sarcocystin,  which  is 
highly  toxic  for  rabbits,  mice,  and  spar- 
rows, but  probably  less  toxic  for  rats, 
sheep  and  some  other  animals.    Sarco- 
cystin acts  on  the  central  nervous  system 
and  also  affects  the  heart,  adrenal  glands, 
liver  and  intestinal  wall.    It  is  filtrable, 
and  is  destroyed  by  heat.    Small  amounts 
cause  a  febrile  reaction  in  the  rabbit, 
while  large  amounts  produce  collapse, 
severe  diarrhea  and  death.    According  to 
Sato  (1926),  the  intravenous  minimum 
lethal  dose  for  the  rabbit  of  the  extract 
from  S.  f us  if  or  mis   from  the  ox  is  0.05 
mg  per  kilogram  body  weight. 

Immunity:     Animals  can  be  immunized 
against  sarcocystin  by  repeated  injections 
of  untreated  or  formalin-treated  toxin. 
The  serum  of  immunized  animals  will  pro- 
tect other  animals  against  the  toxin. 

The  close  relationship  between  Sar- 
cocystis  and  ToxoplasDui  is  attested  by  the 
fact  that  both  react  with  cytoplasm -modify- 
ing antibody  in  the  Sabin-Feldman  dye  test 
(described  below  under  Toxoplasma).    As 
a  matter  of  fact,  cross  reactions  between 
the  two  are  not  uncommon.     Muhlpfordt 
(1951)  and  Awad  and  Lainson  (1954)  found 
that  the  sera  of  laboratory  animals  fed 
S.   lenella  from  sheep  reacted  positively 
to  the  dye  test  with  Toxoplasma  tropho- 
zoites.   The  sera  of  sheep  naturally  in- 


fected with  S.  lenella  also  gave  positive 
reactions.     Awad  (1954)  went  a  step  fur- 
ther, and  developed  a  modified  dye  test  for 
Toxoplasma,  using  S.  lenella  trophozoites. 
These  trophozoites  gave  positive  results 
with  the  sera  of  animals  infected  with  either 
Toxoplasma  or  Sarcocystis. 

Epidemiology:     Seasonal  infection 
during  the  late  spring,  summer  and  early 
fall  has  been  reported  in  sheep,  swine  and 
horses  in  the  temperate  zone  (Scott,   1943). 
Repeated  infections  of  sheep  in  successive 
seasons  were  reported  by  Scott  (1943).    He 
had  the  impression  that  the  older  the  an- 
imals, the  more  heavily  they  were  para- 
sitized. 

Diagnosis:     Because  of  the  absence  of 
recognizable  signs,  Sarcocyslis  infections 
are  almost  always  diagnosed  after  death. 
The  larger  cysts  are  easily  seen  with  the 
naked  eye,  and  the  small  ones  can  be  found 
by  histologic  examination. 

Cultivation:     Sarcocystis  has  not  been 
cultivated,  unless  the  claims  of  Spindler 
and  Zimmerman  (1945)  and  Ciesla  (1950) 
are  accepted. 

Treatment:     None  known. 

Prevention  and  Control:     Since  Sar- 
cocystis infections  are  acquired  thru  fecal 
contamination  of  food  or  drink,  infections 
can  be  prevented  by  measures  designed  to 
prevent  such  contamination.    Sanitation 
and  good  management  should  be  effective. 


SARCOCYSTIS  MIESCHERIANA 
(KUHN,   1865)  LANKESTER,   1882 

Synonyms:     Synchytrium  niiescheri- 
anum . 

Host:      Pig. 

Location:     Striated  and  heart  muscles. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  ex- 
tremely common  thruout  the  world,  having 
been  reported  in  as  high  as  98.  5%  of  pigs 
examined.    Alicata  (1932)  found  it  in  75% 


SARCOCYSTIS,    TOXOPLASMA  AND   RELATED  PROTOZOA 


323 


of  180  garbage-fed  hogs  in  California. 
Jacobs,   Remington  and  Melton  (1960a) 
found  it  in  44%  of  50  pigs  from  a  Baltimore 
slaughter  house.    Musfeldt  (1950)  found  it 
in  6%  of  264  swine  diaphragms  in  British 
Columbia.    Sysoev  (1955)  reported  it  in 
9.2%  of  319,492  swine  diaphragms  in  the 
USSR. 

Morphology:     The  cysts  are  0.  5  to 
4  mm  long  and  up  to  3  mm  wide.    They  are 
compartmented,  and  their  wall  is  striated 
with  cytophaneres. 

Remarks:     This  is  the  type  species  of 
the  genus.     If  it  eventually  turns  out  that 
the  various  species  reported  from  different 
hosts  are  actually  the  same,  then  their  cor- 
rect name  would  be  S.   niiesclieriana. 


SARCOCYSTIS  FUSIFORMIS 
RAILLIET,   1897 

Synonyms:     Sarcocystis  blancliardi, 
Miescheria  cruzi. 

Hosts:     Ox,  water  buffalo. 

Location:     Striated  and  heart  muscles. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  ex- 
tremely common  thruout  the  world.    Wilson 
and  McDonald  (1938)  found  it  in  the  hearts 
of  86%  of  35  cattle  in  Virginia.    Wang 
(1950)  found  it  in  75%  of  48  cattle  in  Illin- 
ois.   Jacobs,  Remington  and  Melton  (1960a) 
found  it  in  98%  of  60  cattle  from  a  Balti- 
more slaughter  house.    Skibsted  (1945) 
found  it  in  94%  of  100  cows  and  18.  5%  of 
97  calves  in  Denmark, 

Morphology:     The  cysts  are  up  to  1 
cm  or  more  long.    They  are  compartmented 
when  mature.     The  cyst  wall  may  be  thin 
and  smooth  or  may  contain  cytophaneres. 
The  trophozoites  are  about  10  jj,  long. 


SARCOCYSTIS  TENELLA 
RAILLIET,   1886 

Synonym:      Balbiania  gigantea. 


Hosts:     Sheep,   goat,  bighorn  sheep 
(Honess,  1956). 

Location:     Striated  and  heart  muscles. 
This  species  is  especially  common  in  the 
wall  of  the  esophagus. 

Geographic  Distribution:    Worldwide. 

Prevalence:     This  species  is  ex- 
tremely common  in  sheep  thruout  the  world, 
having  been  reported  from  50  to  100%  of 
the  sheep  examined  (Scott,  1943;  Destombes, 
1957;  Grasse',  1953).    Jacobs,  Remington 
and  Melton  (1960a)  found  it  in  98%  of  86 
sheep  from  a  Baltimore  slaughter  house. 
It  is  uncommon  in  goats  (Reichenow,  1953). 

Morphology:     The  cysts  are  relatively 
ellipsoidal  and  up  to  1  cm  long.    The  cyst 
wall  is  smooth  at  first,  acquires  a  layer  of 
cytophaneres  as  it  grows,  and  loses  them 
again  as  it  ages.    The  cysts  are  compart- 
mented.   The  trophozoites  measure  8  to 
11  by  2  to  4  ^t. 


SARCOCYSTIS  CERVI 
DESTOMBES,   1957 

This  species  was  described  by  Des- 
tombes (1957)  from  an  unidentified  species 
of  deer  in  Vietnam.    Honess  (1956)  found 
Sarcocystis  in  the  mule  deer  (Odocoileus 
heniiomis)  and  elk  {Cervtis  canadensis)  in 
Wyoming.    However,  it  is  likely  that  S. 
cervi  is  a  synonym  of  S.  tenella. 


SARCOCYSTIS  BERTRAMI 
DOFLEIN,   1901 

Hosts:     Horse,  ass. 

Location:     Striated  and  heart  muscles. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  ex- 
tremely common  thruout  the  world. 

Morphology:     This  species  closely 
resembles  S.  niiesclieriana  of  the  pig.    The 
cysts  are  up  to  10  mm  long  and  are  com- 
partmented.   The  cyst  wall  has  a  layer  of 
cytophaneres. 


324 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


SARCOCYSTIS  LINDEMANNI 
(RIVOLTA,   1878) 

Synonyms:     Gregaritia  lindemanni, 
Sarcocyslis  hominis. 

Host:     Man. 

Location:     Striated  and  heart  muscles. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  name  has  been 
given  to  various  sarcocysts  of  different 
sizes  which  have  been  found  on  rare  occa- 
sions in  man.    It  is  extremely  doubtful 
that  man  has  a  species  of  his  own,  and 
these  cases  were  most  probably  infections 
with  forms  from  domestic  animals.     The 
differences  in  size  of  trophozoites  given 
in  different  reports  bear  this  out  (cf.  Kean 
and  Grocott,  1945). 

Morphology:     The  cysts  are  up  to  5.  3 
cm  long,  but  are  usually  much  smaller. 
Compartmentation  has  been  described. 
The  cyst  wall  is  apparently  smooth.    The 
trophozoites  vary  in  size;  most  are  in  the 
range  of  7  to  10  by  2  to  3 /i,  but  small  ones 
5  by  2ji  have  also  been  reported. 


SARCOCYSTIS  MURIS 
BLANCHARD,   1885 

Hosts:     House  mouse,  Norway  rat, 
black  rat. 

Location:     Striated  and  heart  muscles. 

Geographic  Distribution:     Worldwide. 

Prevalence:     At  one  time  this  species 
was  common  in  laboratory  mice,  but  it  is 
less  so  today.    According  to  Deschiens, 
Levaditi  and  Lamy  (1957),  it  is  quite  rare 
in  laboratory  mice,  and  they  did  not  en- 
counter it  in  laboratory  rats  in  France 
during  the  previous  4  years. 

Morphology:     The  cysts  are  elongate, 
range  in  length  up  to  several  centimeters, 
and  are  apparently  not  compartmented. 
The  cyst  wall  is  smooth.     The  trophozoites 
are  9  to  15fi  long  and  2.  5  to  3jn  wide. 


SAR  C  OC  YS  TIS  C  UNIC  ULI 
BRUMPT,   1913 

Synonym :     Sarcocystis  leporum. 

Hosts:     Domestic  rabbit,  cottontail. 

Location:     Striated  and  heart  muscles, 
especially  in  the  hind  legs,  flanks  and  loins. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  common 
in  cottontails.     Erickson  (1946)  found  it  in 
38%  of  78  cottontails  in  Minnesota.    It  is 
apparently  not  common  in  domestic  rab- 
bits.   Deschiens,   Levaditi  and  Lamy  (1957) 
said  that  it  is  very  rare  in  France. 

Morphology:     The  cysts  are  up  to  5 
mm  long.    They  are  compartmented,  and 
their  walls  have  a  layer  of  cytophaneres. 
The  trophozoites  usually  measure  12  to 
13  by  4  to  5  (li,  but  range  in  length  from  6 
to  16 /J,. 

SARCOCYSTIS  RILEYI 
(STILES,   1893) 

Synonyms:     Balbiania  rileyi,  Sarco- 
cystis anatina,  Sarcocystis  horwathi, 
Sarcocystis  gallinarum . 

Hosts:     Domestic  duck  and  various 
wild  ducks,  including  the  mallard,  black 
duck,  gadwall,  American  pintail,  blue- 
winged  teal  and  shoveller.    In  addition, 
this  species  has  been  found  in  the  chicken 
(Hawkins,   1943),  sage  grouse  (Salt,  1958) 
and  a  number  of  other  wild  birds.    Erick- 
son (1940)  listed  20  species  of  birds  be- 
longing to  8  orders  in  which  Sarcocystis 
had  been  found. 

Location:     Striated  and  heart  muscles, 
especially  of  the  breast,  neck  and  legs. 

Geographic  Distribution:     Worldwide. 

Prevalence:     This  species  is  especially 
common  in  surface-feeding  wild  ducks,  but 
not  in  diving  ducks.     Erickson  (1940)  re- 
ported it  from  3%  of  312  wild  ducks  in 
Minnesota.    It  is  not  uncommon  for  hunters 


SARCOCYSTIS,    TOXOPLASNM   AND  RELATED  PROTOZOA 


32S 


to  bring  infected  birds  which  they  have 
shot  to  a  diagnostic  laboratory  to  learn 
whether  they  are  safe  to  eat. 

Morphology:     The  cysts  are  several 
millimeters  long  and  are  compartmented. 
The  cyst  wall  is  smooth.    The  trophozoites 
measure  about  8  by  2  jii . 


FAMILY   TOXOPLASMATIDAE 


Members  of  this  family  form  pseudo- 
cysts, i.e. ,  the  "cyst"  wall  is  formed  by 
the  host  and  not  by  the  parasite.    A  true 
cyst  may  be  formed  as  well  (cf.  Lainson, 
1958).    Multiplication  is  by  binary  fission 
or  endodyogeny,  and  possibly  by  schizo- 
gony in  the  young  pseudocysts. 

This  family  includes  the  genera 
Toxoplasma,   Besnoitia  and  Enceplialito- 
zoon.     Its  taxonomy  has  been  reviewed 
by  Westphal  (1954),  Van  Thiel  (1956), 
Biocca  (1949,  1957),  and  Goldman,  Carver 
and  Sulzer  (1958),  among  others. 


Genus  TOXOPLASMA 
Nicolle  and  Manceaux,  1908 

In  this  genus  the  pseudocyst  wall  is 
thin.  A  single,  euryxenous  species,  T. 
gondii  is  recognized. 

Because  of  its  importance  as  a  cause 
of  human  disease,  T.  gondii  has  been 
studied  intensively  and  the  literature  on  it 
is  vast.    Eyles  and  Frenkel  (1952)  pub- 
lished a  bibliography  which  listed  920 
papers  and  then  supplemented  it  (1954) 
with  400  more.    A  great  many  more  papers 
have  been  published  since  that  time.    It  is 
obviously  impractical  to  attempt  to  refer 
to  them  all  here.    Various  aspects  of 
Toxoplasma  and  toxoplasmosis  have  been 
reviewed  by  Weinman  (1952),  Habegger 
(1953),  Jacobs  (1956,  1957),  Feldman  and 
Miller  (1956),  Siim  (1956),  Eichenwald 
(1956),  Frenkel  (1956a),  Hoare  (1956), 
Eyles  (1956),  de  Roever-Bonnet  (1957) 
and  Siim  (1960). 


TOXOPLASMA   GONDII 
NICOLLE   AND  MANCEAUX,   1908 

Synonyms:     Toxoplasma  cuniculi,   T. 
caviae,    T.  canis,    T.  musculi,    T.  ratti, 
T.  laidlawi,    T.  sciuri,   T.  pyrogenes, 
T.  hominis. 

Disease:     Toxoplasmosis, 

Hosts:     T.  gondii  was  first  found  in 
the  gondi  {Ctenodactylus  gondi),  a  North 
African  rodent,  but  it  has  since  been  found 
in  many  species  of  mammals  and  birds. 
Its  host  list  includes  the  gondi,  house 
mouse,  Norway,  black,  climbing  and 
water  rats,  squirrel,  ground  squirrel, 
vole,  guinea  pig,  chinchilla,  marmot,  the 
Chilean  rodent,   Octodon  degus,  the  Uru- 
guayan rodent,   Ctenomys  torquatus, 
rabbit,  hare,  mole,  shrew,  hedgehog,  dog, 
cat,  fox,  weasel,  ferret,  mink,  wombat, 
bandicoot,  brush-tail  possum,  marsupial 
rat,  pig,  sheep,  ox,  baboon,  chimpanzee, 
macaque  {Macaca  tantala),  whiteface  mon- 
key {Cebits  capucinus),  cotton-topped  mar- 
moset (Oedipomidas  oedipus),  squirrel 
monkey  {Saimiri  sciiirea),  man,  pigeon, 
chicken,  crow,  canary,  penguin  and  par- 
tridge {Perdrix  perdrix)  (Ratcliffe  and 
Worth,  1951;  Christen  and  Thiermann, 
1953;  Talice,  Perez-Mor^ra  and  Mossera, 
1954;  Jacobs,  1956;  Finlay  and  Manwell, 
1956;  Van  den  Akker,  Bool  and  Spitseshuis, 
1959;  Cook  and  Pope,  1959;  Benirschke  and 
Richart,  1960).    In  addition,  organisms 
which  resemble  Toxoplasma  morpholog- 
ically have  been  seen  in  reptiles;  and 
turtles,  lizards,  geckos  and  chameleons 
can  be  infected  experimentally  (Jacobs, 
1956).    On  the  other  hand,  most  of  the 
organisms  reported  as  Toxoplasma  from 
the  blood  of  -various  wild  birds  are  prob- 
ably Lankesterella. 

Location:     Toxoplasma  is  an  intra- 
cellular parasite  of  many  types  of  cells, 
including  neurons,  microglia,  endothel- 
ium, reticulum,  liver  parenchyma  cells, 
lung  and  glandular  epithelial  cells,  car- 
diac and  skeletal  muscle  cells,  fetal 
membranes  and  leucocytes.    In  acute  in- 
fections, the  parasites  may  be  found  free 
in  the  blood  and  peritoneal  exudate. 


326 


SARCOCYSTIS,    TOXOPLASMA   AND  RELATED  PROTOZOA 


Geographic  Distribution:     Worldwide. 

Prevalence:     Toxoplasmiasis  is  ap- 
parently extremely  common  in  man  and 
also  in  many  domestic  animals.    As  Jacobs 
(1957)  said,  there  is  a  sea  of  ToxoplasDia 
infection  around  us.     However,  toxoplas- 
mosis is  far  less  common.    Most  infec- 
tions are  inapparent,  and  the  disease  itself 
appears  only  under  special  circumstances, 
many  of  which  are  still  unknown. 

Most  of  the  surveys  which  have  been 
made  for  Toxoplasuia  have  been  serologic 
and  indicate  either  previous  or  present 
infections.    In  some  cases,  particularly 
in  sheep  and  other  domestic  animals  in 
which  Sarcucystis  infection  is  common 
and  in  which  the  Sabin-Feldman  dye  test 
was  used,  they  may  indicate  merely  the 
presence  of  cross-reacting  antibodies 
(Muhlpfordt,   1951;  Awad,   1954;  Awad  and 
Lainson,   1954).     Hence  surveys  in  which 
the  organism  itself  was  isolated  are  more 
reliable,  altho  much  more  time-consuming 
and  expensive. 

The  prevalence  of  antibodies  varies 
widely  in  man  in  different  geographic  lo- 
cations.    For  instance,  according  to 
Jacobs  (1957),  there  is  relatively  less  in- 
fection in  California  than  in  the  eastern 
United  States.    Feldman  and  Miller  (1956a) 
observed  positive  dye  tests  in  68%  of  121 
persons  on  Tahiti,   64%  of  266  in  Honduras, 
36%  of  104  in  Haiti,   35%  of  144  in  Pitts- 
burgh,  Penn. ,   31%  of  270  in  New  Orleans, 
26%  of  184  in  St.   Louis,   17%  of  293  in 
Portland,  Ore.,   11%  of  108  on  Iceland, 
4%  of  236  Navajo  Indians  in  Arizona,  and 
none  of  21  Eskimos  in  Alaska.    In  a  study 
of  1072  urban  and  rural  Negroes  11  to  19 
years  old  in  the  region  of  Memphis,  Ten- 
nessee, Gibson  (1956)  found  that  the 
Sabin-Feldman  dye  test  was  positive  in 
20. 4%  of  the  urban  and  18. 9%  of  the  rural 
group.    Balozet  (1955)  found  that  12%  of 
125  humans  in  Algiers  were  positive  to 
the  complement  fixation  test.    Thiermann 
and  Naquira  (1958)  found  that  the  dye  test 
was  positive  in  43%  and  the  complement 
fixation  test  in  11%  of  284  normal  medical 
students  in  Santiago,  Chile;  the  dye  test 
was  positive  in  48%  and  the  complement 
fixation  test  in  2%  of  131  blood  donors, 
mostly  over  30  years  old.    Orio  et  al. 


(1958)  found  that  the  sera  of  10.  2%  of  1139 
Africans  in  Middle  Congo  were  positive 
to  the  complement  fixation  test.    The  above 
results  give  some  idea  of  the  range  of  pos- 
itive reactions  which  may  be  expected  in 
different  surveys. 

Among  domestic  animals,  the  first 
spontaneous  case  of  toxoplasmosis  in  the 
dog  was  reported  by  Mello  (1910)  in  Turin, 
Italy.    In  reviewing  the  animal  reservoir 
of  toxoplasmosis,  Habegger  (1953)  stated 
that  only  something  more  than  50  cases  had 
been  reported  in  dogs  thruout  the  world. 
However,  more  recent  reports  have  raised 
this  figure  considerably. 

Miller  and  Feldman  (1953)  found  dye 
test  antibodies  in  59%  of  51  dogs  in  Penn- 
sylvania.    Feldman  and  Miller  (1956a) 
found  them  in  28%  of  51  dogs  from  New 
York,  30%  of  23  dogs  from  Arizona  and 
86%  of  7  dogs  from  Honduras.    Siim  (1950) 
found  that  18.  5%  of  54  dogs  in  Copenhagen 
had  dye  test  titers  of  1:250  or  more.    Often, 
Westphal  and  Kajahn  (1950)  found  that  36% 
of  84  dogs  in  Hamburg,  Germany  were 
positive  to  the  dye  test.     Borgen  and  Berg 
(1957)  found  that  44.5%  of  20  dogs  in  Norway 
were  positive  to  the  dye  test.    De  Roever- 
Bonnet  (1957)  found  that  1  of  75  dogs  in 
Amsterdam  was  positive  to  the  dye  test  at 
a  titer  above  1:100.    Makstenieks  and 
Verlinde  (1957)  found  that  14%  of  29  dogs 
from  households  in  the  Netherlands  where 
human  toxoplasmosis  existed  were  positive 
to  the  dye  test  at  1:64  or  above.     Eyles 
et  al.   (1959)  found  that  8.  3%  of  809  dogs 
from  the  Memphis  pound  or  slums  were 
positive  to  the  dye  test  at  a  titer  of  1:64 
or  above,  and  they  isolated  Toxoplasma  by 
mouse  inoculation  from  3  of  200  of  the 
dogs.    Gibson  and  Jumper  (1960)  found 
that  the  sera  of  16%  of  800  dogs  from  the 
Memphis  pound  were  positive  to  the  dye 
test  at  a  titer  of  1:16  or  above;  they  found 
Toxoplasma  by  mouse  inoculation  in  only 
2  out  of  75  of  these  animals. 

Morris,  Aulisio  and  McCown  (1956) 
found  that  25%i  of  180  dogs  in  the  Middle 
Atlantic  stages  were  positive  to  the  com- 
plement fixation  test.    Lainson  (1956) 
found  that  42.  5%  of  113  dogs  in  London 
were  positive  to  the  complement  fixation 
test.    Balozet  (1955)  found  that  30%  of 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


327 


105  pound  dogs  in  Algiers  were  positive 
to  the  complement  fixation  testo 

In  the  United  States,   Cole  et  al.  (1953) 
described  an  outbreak  of  toxoplasmosis  in 
a  kennel  of  104  dachshunds,  in  which  69 
pups  and  17  adults  (of  which  14  were 
bitches)  died.    In  another  outbreak  in  a 
kennel  of  47  chihuahuas,  14  pups  and  15 
adults  died.    They  also  found  toxoplasmo- 
sis in  11  pet  dogs,  each  owned  by  a  differ- 
ent family.     Langham  and  Sholl  (1949)  re- 
ported a  case  in  a  young  fox  terrier  in 
Michigan.    Moulton  and  Linton  (1953)  re- 
ported a  fatal  canine  case  in  California. 
Krause  (1954)  found  Toxoplasma  in  1  out 
of  30  dogs  by  inoculating  mice  with  brain 
tissue.    Seibold  and  Hoerlein  (1955)  re- 
ported a  case  of  renal  toxoplasmosis 
associated  with  distemper  in  a  puppy. 

Hulland  (1956)  described  8  fatal  cases 
of  canine  toxoplasmosis  in  Canada.    Wick- 
ham  and  Came  (1950)  reported  3  cases  in 
Australia.    Grocott  (1950)  reported  a  case 
from  the  Canal  Zone,    Sjolte  (1948)  re- 
ported the  first  case  of  canine  toxoplas- 
mosis in  Denmark.    Fankhauser  (1950, 
1951)  found  it  in  6  dogs  in  Switzerland. 
Kardevan  and  Xapp  (1957)  found  Toxo- 
plasma in  2  of  20  dogs  in  Hungary.    Bonser 
(1950)  described  a  case  of  toxoplasmatal 
intussusception  in  a  3-year-old  bitch  in 
England.    Campbell,  Martin  and  Gordon 
(1955)  found  it  by  histological  examination 
in  6%  of  268  dogs  in  Glasgow,  Scotland. 
Flir  (1954)  described  3  cases  in  dogs  in 
Germany.    Van  den  Akker,  Bool  and 
Spitseshuis  (1959)  found  it  in  a  dog  in 
Holland.    Blanc  and  Hintermann  (1948) 
reported  it  in  a  dog  in  Morocco.    Orio 
et  al.  (1959)  found  Toxoplasma  in  a  dog  in 
Brazzaville,  Middle  Congo. 

Toxoplasmosis  has  been  reported  in 
single  cats  by  Wickham  and  Carne  (1950) 
in  Australia,  Holzworth  (1954)  in  Massa- 
chusetts, Jones  (1955)  in  the  U.S.  and 
Hulland  (1956)  in  Canada.    Jones,  Eyles 
and  Gibson  (1957)  found  T.  gondii  by 
mouse  inoculation  in  24%  of  140  cats  in 
Memphis,  Tennessee,  and  in  11%  of  35 
cats  in  Columbia,  South  Carolina.    They 
reviewed  the  literature  on  isolation  of 
Toxoplasma  from  the  cat;  theirs  was  the 
tenth  report.    Gibson  and  Eyles  (1957) 


found  T.  gondii  by  mouse  inoculation  of 
brain  tissue  in  20%  of  35  cats  from  the 
neighborhood  of  a  house  in  Memphis  where 
a  newborn  child  had  died  of  congenital  toxo- 
plasmosis. 

Feldman  and  Miller  (1956a)  found  that 
33%  of  79  cats  from  Massachusetts  and  New 
York  were  positive  to  the  dye  test  for  Toxo- 
plasma.   Makstenieks  and  Verlinde  (1957) 
found  that  15%  of  33  cats  from  households 
in  the  Netherlands  where  human  toxoplas- 
mosis existed  were  positive  to  the  dye  test 
at  a  titer  of  1:64  or  above.    Havlik  and 
Hubner  (1959)  found  that  34%  of  200  cats  in 
central  Bohemia  were  positive  to  the  dye 
test  at  a  titer  of  1:16  or  above;  they  iso- 
lated Toxoplasma  by  mouse  inoculation 
from  2  out  of  23  of  the  positive  cats. 

The  first  cases  of  toxoplasmosis  in 
swine  were  reported  by  Farrell   et  al. 
(1952)  in  Ohio.    They  found  the  disease  in 
8  pigs  from  a  farm  where  an  undiagnosed 
disease  had  recurred  for  many  years. 
Sanger  and  Cole  (1955)  isolated  T.  gondii 
from  2  newborn  pigs  collected  aseptically 
from  the  vagina  as  well  as  from  the  milk 
and  heart  of  a  naturally  infected  sow  which 
showed  no  signs  of  disease.    They  also 
isolated  Toxoplasma  from  the  milk  and 
from  3  of  4  pigs  from  another  apparently 
healthy,  naturally  infected  sow.    Momberg- 
J0rgensen  (1956)  isolated  Toxoplasma  from 
a  litter  of  8-day-old  pigs  in  Norway,  6  of 
which  had  died  of  pneumonia,  enteritis, 
hepatitis,  nephritis  and  splenitis;  he  also 
found  Toxoplasma  in  tissue  sections  of 
some  18-day-old  pigs  that  had  died  of  a 
similar  pneumonia. 

In  a  serologic  survey  of  hog  sera  from 
a  slaughterhouse  in  New  Haven,  Conn. , 
Weinman  and  Chandler  (1956)  found  that 
42%  of  88  sera  were  positive  to  the  dye 
test.    Most  of  the  positive  pigs  were  from 
one  farm  where  the  pigs  were  fed  uncooked 
garbage.    Feldman  and  Miller  (1956a) 
found  that  30%  of  73  pigs  from  the  midwest 
and  New  York  were  positive  to  the  dye  test. 
De  Roever-Bonnet  (1957)  found  that  12%  of 
25  hogs  from  an  Amsterdam  slaughterhouse 
were  positive  to  the  dye  test  at  a  titer  above 
1:1000.    Eyles  et  al.  (1959)  found  that  2% 
of  178  pigs  from  Memphis,  Tenn.  slaugh- 
terhouses were  positive  to  the  dye  test  at 


328 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


a  titer  of  1:64  or  above,  and  isolated 
Toxoplasma  by  mouse  inoculation  from  1 
out  of  129  of  them.     By  inoculation  of 
mice  with  peptic  digests  of  diaphragm 
samples,  Jacobs,  Remington  and  Melton 
(1960a)  found  Tuxoplas)iia  infection  in 
24%  of  50  pigs  from  a  Baltimore  slaughter- 
house. 

Toxoplasmosis  was  first  reported 
from  sheep  by  Olafson  and  Monlux  (1942) 
in  New  York.    It  was  later  found  in  sheep 
in  Australia  by  Wickham  and  Carne  (1950) 
and  Osborne  (1959),  in  Ohio  by  Cole  el  al. 
(1954)  in  New  Zealand  by  Hartley  and 
Marshall  (1957),  and  in  England  by  Bever- 
ley and  Watson  (1959).    It  was  associated 
with  abortions  and  perinatal  mortality  in 
the  last  4  reports;  indeed.  Hartley  and 
Marshall  considered  toxoplasmosis  to  be 
the  most  wide -spread  and  probably  the 
most  important  cause  of  ovine  perinatal 
mortality  in  New  Zealand.    It  may  be  im- 
portant in  England,  too;  Beverley  and 
Watson  (1959)  found  it  in  6  of  39  aborted 
lambs  from  a  number  of  flocks  in  that 
country,  and  found  dye  test  titers  of 
1:128  or  above  in  43  of  549  ewes  from  93 
flocks,  including  22  of  158  ewes  which 
had  aborted  from  causes  other  than  viral 
or  bacterial. 

Feldman  and  MiUer  (1956a)  found  that 
5%  of  66  sheep  from  Arizona,   56%  of  9 
sheep  from  Kentucky  and  43%  of  65  goats 
from  New  York  were  positive  to  the  dye 
test  for  ToxoplasDia.     De  Roever-Bonnet 
(1957)  found  that  35%  of  23  sheep  from  an 
Amsterdam  slaughterhouse  were  positive 
to  the  dye  test  at  a  titer  above  1:100.     He 
also  (1957a)  isolated  Toxoplasma  by  mouse 
inoculation  from  the  brains  of  4  out  of  30 
slaughtered  sheep  picked  at  random.  Rawal 
(1959)  found  that  3  of  100  sheep  sera  from 
a  Sheffield,  England  slaughterhouse  were 
positive  to  the  dye  test  at  a  titer  of  1:64 
or  above.     He  found  Tuxoplas»ia  by  mouse 
inoculation  in  the  brains  of  6  out  of  21 
sheep  whose  sera  had  reacted  to  the  dye 
test  at  a  titer  of  1:4  or  above.    Jacobs, 
Remington  and  Melton  (1960a)  found  Toxo- 
plas))ia  infection  in  9%  of  86  sheep  from 
a  Baltimore  slaughterhouse. 

Sanger  ei  al.  (1953)  found  Toxo- 
plasma in  4  herds  of  cattle  in  Ohio. 


Miller  and  Feldman  (1953)  and  Feldman 
and  Miller  (1956)  found  that  19%  of  132 
cattle  from  New  York  were  positive  to  the 
dye  test.    De  Roever-Bonnet  (1957)  found 
that  6%  of  31  cattle  from  an  Amsterdam 
slaughter  house  were  positive  to  the  dye 
test  at  a  titer  above  1:100.    Jacobs,  Rem- 
ington and  Melton  (1960a)  found  Toxo- 
plasDia  infection  in  2%  of  60  beef  cattle 
from  a  Baltimore  slaughterhouse. 

Toxoplasma  has  been  found  in  lago- 
morphs  not  infrequently.     Perrin  (1943) 
found  it  in  a  laboratory  rabbit  in  Bethesda 
Md.,   Christiansen  (1948)  found  it  in  8.75% 
of  2411  hares  in  Denmark,   Lainson  (1955) 
found  it  in  the  brains  of  5%  of  113  domestic 
rabbits  in  England,   and  Orio  el  al.  (1959) 
isolated  it  from  57%  of  14  rabbits  from 
Brazzaville,   Middle  Congo,   either  from 
the  Pasteur  Institute  animal  colony  there 
or  from  the  environs  of  the  city  itself. 
Miller  and  Feldman  (1953)  found  that  5% 
of  22  laboratory  rabbits  were  positive  to 
the  dye  test,  and  Morris,  Aulisio  and 
McCown  (1956)  found  that  19%  of  107 
cottontails  from  the  Middle  Atlantic  states 
were  positive  to  the  same  test. 

Toxoplasma  has  been  found  several 
times  in  guinea  pigs.    Among  others, 
Mariani  (1941)  found  it  in  guinea  pigs  sent 
from  Italy  to  Ethiopia.    De  Rodaniche 
(1949)  found  it  in  guinea  pigs  purchased  in 
the  suburbs  of  the  city  of  Panama.    Varela, 
Martinez  and  Trevino  (1953)  found  it  in  a 
guinea  pig  in  Mexico.    Orio  et  al.   (1959) 
found  it  in  23%  of  31  adult  guinea  pigs  in 
the  Pasteur  Institute  animal  colony  at 
Brazzaville,  Middle  Congo.    Miller  and 
Feldman  (1953)  found  that  27%  of  51  lab- 
oratory guinea  pigs  in  the  U.S.  were  pos- 
itive to  the  dye  test.    Makstenieks  and 
Verlinde  (1957)  found  that  33%  of  174 
guinea  pigs  from  animal  dealers  in  the 
Netherlands  were  positive  to  the  dye  test 
at  a  titer  of  1:64  or  above. 

Toxoplasma  was  found  by  mouse  or 
guinea  pig  inoculation  of  brain  tissue  in 
over  3%  of  the  wild  Norway  rats  in  Mem- 
phis by  Eyles  (1952).     He  also  found  that 
the  dye  test  was  positive  in  20%  of  100 
rats,  but  observed  no  correlation  between 
the  dye  test  and  the  results  of  tissue  inocu- 
lation.   Lainson  (1957)  found  Toxoplasma 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


329 


in  1  of  99  wild  Norway  rats  in  England. 
Miller  and  Feldman  (1953)  found  no  posi- 
tive dye  test  reactors  among  54  albino 
rats  which  they  studied. 

Toxoplasma  has  been  found  in  labor- 
atory mice  by  Nicolau  and  Balmus  (1934) 
and  Mooser  (1950).    Gibson  and  Eyles 
(1957)  found  it  by  mouse  inoculation  of 
brain  tissue  in  6%  of  121  wild  house  mice 
captured  in  the  neighborhood  of  a  house  in 
Memphis  where  a  new-born  infant  had  died 
of  congenital  toxoplasmosis.     Lainson 
(1957)  failed  to  find  it  in  399  wild  house 
mice  in  England.     Makstenieks  and  Ver- 
linde  (1957)  found  that  none  of  4097  labor- 
atory mice  from  animal  dealers  in  the 
Netherlands  was  positive  to  the  dye  test 
even  at  a  titer  of  1:4. 

Toxoplasmosis  is  so  common  in  voles 
(J^icrotiis  agrestis  )  in  England  that  it  is 
said  to  be  a  population-limiting  factor 
(Findlay  and  Middleton,   1934;  Elton,  Davis 
and  Findlay,   1935). 

Among  other  mammals,  toxoplasmosis 
has  been  reported  in  mink  by  Hulland  (1956) 
and  Pridham  and  Belcher  (1958)  in  Canada, 
and  by  Momberg-J0rgensen  (1956a)  in 
Norway.    In  the  last  case,  a  severe  out- 
break of  distemper  was  also  present. 
Lainson  (1957)  found  it  in  a  weasel  {Miis- 
tela  nivalis),  a  ferret,  and  2  ferret-polecat 
hybrids  in  England.     Toxoplasma  was  re- 
ported in  3  chinchillas  in  Washington  by 
Gorham  and  Farrell  (1956),  and  in  3  chin- 
chilla ranches  in  Canada  by  Hulland  (1956). 

Among  domestic  birds,   Toxoplasma 
was  found  in  a  hen  in  Switzerland  by  Fank- 
hauser  (1951a),  in  a  flock  of  chickens  in 
Norway  by  Erichsen  and  Harboe  (1954), 
and  in  35  hens  from  21  flocks  in  Denmark 
by  Biering-S0rensen  (1956). 

Manwell  and  Drobeck  (1951)  isolated 
T.  gondii  from  a  pigeon  caught  in  Syracuse, 
N.  Y. ,  while  Jacobs,  Melton  and  Jones 
(1952)  isolated  it  from  4  of  80  wild  pigeons 
caught  in  Washington,  D.  C. ;  the  dye  test 
was  positive  in  7  of  these  birds,  including 
1  of  those  from  which  the  organism  was 
isolated. 


Rosenbusch  (1931)  found   T.  gondii  in 
a  canary  in  Argentina,   and  Sergent  and 
Poncet  (1954)  found  it  in  one  in  Algeria. 
Finlay  and  Manwell  (1956)  have  reviewed 
the  literature  on  Toxoplasma  in  birds. 


Fig.  37. 


Toxoplasma  gondii  trophozoites 
from  mouse  peritoneal  exudate. 
Giemsa  stain.    X  2800.    (Original) 


Morphology:     The  trophozoites  of  T. 
gondii  are  crescentic  or  banana-shaped, 
with  one  end  pointed  and  the  other  rounded, 
and  measure  4  to  8  by  2  to  4  (i.     The  nu- 
cleus is  vesicular  and  more  or  less  central. 
There  are  no  flagella,  cilia  or  pseudopods. 
Locomotion  is  by  body  flexion  whereby  the 
protozoa  follow  a  corkscrew  path,  rotate 
on  their  longitudinal  axis  or  somersault 
(Manwell  and  Drobeck,   1953),  or  by  gliding. 

The  morphology  of  the  trophozoites 
has  been  studied  following  silver  protein 
staining  by  Goldman,  Carver  and  Sulzer 
(1957,  1958)  and  with  the  electron  micro- 
scope by  Gustafson,  Agar  and  Cramer 
(1954),   Bringmann  and  Holz  (1954),   Ludvik 
(1956)  and  Meyer  and  Mendonca  (1957). 
They  resemble  the  trophozoites  of  Sarco- 
cyslis  in  a  number  of  ways.     At  the  anterior 
end  within  the  pellicle  is  a  short,  truncate, 
hollow  cone  0.15  to  0.25/i  in  diameter  and 
0.2  to  0.3  ;i  long,  called  a  conoid.    There 
is  sometimes  a  distinct,  spike-like  exten- 
sion at  the  anterior  end.    A  number  of  fine, 
longitudinal  fibrils  run  posteriorly  in  the 
pellicle  from  the  region  of  the  conoid;  they 
extend  for  about  1/5  of  the  body  length 
according  to  Ludvik  (1956)  or  2/3  of  it 
according  to  Bringmann  and  Holz  (1954). 
Running  longitudinally  in  the  body  from  the 
conoid  are  5  to  18  cylindrical  or  club-shaped 
structures  known  as  toxonemes.    They  are 
of  variable  length,  some  extending  nearly 
to  the  posterior  end  and  others  not  reaching 
the  level  of  the  nucleus;  they  become  very 
slender  and  tortuous  as  they  approach  the 
conoid,  and  seem  to  enter  its  base.    They 


330 


SARCOCYSTIS,    TOXOPLASMA   AND   REL,\TED   PROTOZOA 


are  0.02fi  in  diameter  when  they  leave 
the  conoid  and  then  thicken  to  form  a  club 
or  sausage-shaped  structure  0.08  to  0.2ju 
in  diameter.    In  addition  to  these,  there 
are  1  or  2  central  fibrils  which  frequently 
form  a  large  loop  or  run  posteriorly  in  a 
zigzag. 

The  cytoplasm  is  somewhat  vacuolated 
and  contains  a  number  of  osmiophilic  gran- 
ules about  0.5fi  in  diameter,   mitochondria 
and  often  a  cluster  of  fine  granules  around 
the  nucleus.    Goldman,  Carver  and  Sulzer 
(1958)  found  a  mass  of  argyrophilic  gran- 
ules at  the  very  posterior  end.     The  nu- 
cleus is  usually  round  or  oval,  but  lobed 
and  horseshoe  shapes  have  also  been  seen 
in  electron  micrographs.     In  the  latter, 
the  open  end  faces  anteriorly  as  in  Sarco- 
cystis.     The  nucleus  is  about  1.0  to  1.  5ji 
in  diameter  when  circular  and  up  to  2  ^  in 
diameter  when  elongated.    Inside  the  nu- 
cleus is  a  large  endosome  which  can  be 
seen  both  in  electron  micrographs  and 
after  silver  protein  staining. 

In  addition  to  the  above  structures, 
Goldman,   Carver  and  Sulzer  (1958)  des- 
cribed long,  thread-like  appendages  in 
trophozoites  treated  with  dilute  (0. 1  to 
1.0%)  formalin  in  saline  before  fixation. 
These  may  have  been  detached  pellicular 
fibrils. 

The  parasites  occur  within  vacuoles 
in  their  host  cells.    According  to  Gustaf- 
son,  Agar  and  Cramer  (1954),  there  is  a 
definite  space  between  the  parasite  and 
the  vacuole  wall.    The  space  often  con- 
tains a  filamentous  or  granular  precipitate, 
and  concentrations  of  mitochondria  are 
often  present  in  the  host  cell  at  the  edge 
of  the  vacuole. 

As  the  parasites  multiply,  they  form 
a  cyst-like  structure.     Frenkel  (1956a) 
emphasized  that  there  is  a  difference  be- 
tween the  terminal  colonies  which  repre- 
sent the  final  stage  of  parasitization  in  the 
leucocytes  and  the  cysts  which  are  found 
in  the  central  nervous  system,  eye  and 
myocardium.     The  wall  of  the  latter  is 
argyrophilic  and  weakly  positive  to  the 
periodic  acid-Schiff  stain  (PAS),  while 
that  of  the  former  is  not.    Some  authorities 
believe  that  the  wall  is  formed  by  the  host. 


so  that  the  "cyst"  is  actually  a  pseudocyst, 
but  Frenkel  and  Friedlander  (1951)  con- 
sidered it  likely  that  the  wall  is  derived 
from  the  parasite.     Lainson  (1958),  too, 
distinguished  between  the  cyst-like  struc- 
tures formed  in  the  acute  and  chronic 
stages  of  the  infection.     The  former  he  con- 
sidered to  be  pseudocysts  and  the  latter 
true  cysts. 

The  trophozoites  in  the  cysts  differ 
slightly  from  the  proliferative  ones  in  the 
pseudocysts.    They  contain  large  glycogen 
granules,  are  more  resistant  to  external 
agents,  and  multiply  slowly.    Dasgupta 
and  Kulasiri  (1959)  found  that  PAS-positive 
granules  were  abundant  in  the  stages  in  the 
"pseudocysts"  from  the  brains  of  mice, 
but  that  they  were  not  universally  present 
in  the  intracellular  and  extracellular 
trophozoites  at  all  days  of  infection. 

Life  Cycle:     Reproduction  in  Toxo- 
plasma has  generally  been  considered  to 
take  place  by  binary  fission.     However, 
Goldman,  Carver  and  Sulzer  (1958)  re- 
ported on  the  basis  of  silver  protein  stain- 
ing that  T.  gondii  reproduces  by  a  process 
of  internal  budding  which  they  named  endo- 
dyogeny.    In  this  process,  2  daughter  cells 
are  formed  within  the  parent  cell.     They 
are  small  at  first,  but  grow  until  they  des- 
troy the  parent  cell  and  are  released. 

The  natural  mode  of  infection  is  un- 
known except  in  congenital  toxoplasmosis, 
but  experimental  infections  can  be  estab- 
lished by  intravenous,  intraperitoneal  or 
any  other  type  of  parenteral  inoculation  or 
even  by  feeding.    Weinman  and  Chandler 
(1954)  transmitted  toxoplasmosis  to  swine 
and  rodents,  and  Makstenieks  and  Verlinde 
(1957)  transmitted  it  to  mice  and  a  cyno- 
molgus  monkey  by  feeding  infected  tissue 
or  peritoneal  fluid.     However,  Schmidtke 
(1956)  and  van  Thiel  and  van  der  Waaij 
(1956)  considered  that  infection  by  feeding 
can  occur  only  when  there  are  epithelial 
lesions  in  the  mouth  or  esophagus. 

Jacobs,  Remington  and  Melton  (1960) 
found  that  the  cysts  of   T.  gondii  are  not 
able  to  survive  freezing  and  drying,  but 
they  survive  as  long  as  68  days  at  4°  C. 
Proliferative  forms  are  destroyed  within 
a  few  minutes  by  artificial  gastric  juice. 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


331 


but  the  cysts  remain  infective  in  tissue  up 
to  3  hours,  while  trophozoites  liberated 
by  peptic  juice  from  isolated  cysts  sur- 
vive 2  hours.     Trypsin  destroys  the  cyst 
wall  immediately,  but  the  liberated  tropho- 
zoites survive  at  least  6  hours;  prolifer- 
ative forms  survive  at  least  3  but  less 
than  6  hours.    Thus,  parasites  encysted 
in  tissues  could  survive  the  normal  diges- 
tive period  in  the  stomach  and  should  sur- 
vive even  longer  in  the  duodenum. 

Following  experimental  inoculation, 
the  protozoa  proliferate  for  a  time  at  the 
site  of  injection  and  then  invade  the  blood 
stream  and  cause  a  generalized  infection. 
Susceptible  tissues  all  over  the  body  are 
invaded,  and  the  parasites  multiply  in 
them,  causing  local  necrosis.    The  para- 
sitemia continues  for  some  time,  until 
antibodies  appear  in  the  serum,  after 
which  the  parasites  disappear  from  the 
blood  and  more  slowly  from  the  tissues. 
They  finally  remain  only  in  pseudocysts 
or  cysts,  and  only  in  the  most  receptive 
tissues.    In  general,  the  spleen,  lungs 
and  liver  are  cleared  of  parasites  rela- 
tively rapidly,  the  heart  somewhat  more 
slowly  and  the  brain  much  more  slowly. 
These  residual  infections  may  persist  for 
a  number  of  years. 

Following  experimental  infection  of 
rats,  Ruchman  and  Fowler  (1951)  re- 
ported that  Toxoplasma  could  be  found  in 
the  blood  regularly  for  the  first  week  and 
then  occasionally  during  the  next  9  days. 
It  could  be  found  in  the  spleen  for  2  weeks, 
in  the  liver  and  lungs  for  10  weeks  and  in 
the  brain  for  2  years  after  infection. 
Other  workers  found  it  as  long  as  3  years 
after  infection  in  the  brain  of  rats,  mice 
and  pigeons,  and  10  months  after  infection 
in  that  of  the  dog  (Jacobs,  1956). 

Toxoplasma  trophozoites  have  been 
found  in  the  urine  and  feces  of  mice  and 
dogs  with  acute  toxoplasmosis,  in  the 
milk  of  mice,  dogs,  cows  and  sows,  in  a 
serous  exudate  from  the  conjunctiva  of  a 
pigeon,  and  in  the  saliva  of  mice,  rabbits 
and  man.    However,  these  are  the  prolifer- 
ative forms  and  are  very  delicate.     They 
are  rarely  able  to  infect  other  animals. 
Mice  can  be  raised  in  the  same  jar  with 
infected  mice  without  becoming  infected. 


Olafson  and  Monlux  (1942)  reported  trans- 
mission to  uninfected  puppies  caged  with 
a  littermate  dying  of  toxoplasmosis,  but 
Jacobs  (1957)  was  unable  to  repeat  this 
observation  under  similar  circumstances. 
He  was  also  unable  to  infect  rabbits  by 
spraying  large  numbers  of  proliferative 
forms  into  a  confined  space  with  them. 

Transmission  via  the  placenta  occurs 
in  congenital  toxoplasmosis.    It  is  gener- 
ally considered  to  be  an  accidental  com- 
plication of  an  inapparent  primary  infection 
of  a  pregnant  female  (Feldman  and  Miller, 
1956).    Foci  of  infection  are  set  up  in  the 
placenta,  and  the  fetus  is  infected  from 
them.    Koestner  and  Cole  (1960)  reported 
the  occurrence  of  congenital  toxoplasmosis 
in  2  consecutive  litters  whelped  by  the 
same  bitch. 

Other  than  placental  transmission,  as 
mentioned  above,  the  natural  mode  of 
transmission  is  unknown.    Weinman  and 
Chandler  (1954)  suggested  that  toxoplas- 
mosis might  be  acquired  in  the  same  way 
as  trichinosis,  by  eating  infected  pork. 
However,  the  epidemiological  evidence 
does  not  appear  to  support  this,  altho 
there  is  suggestive  evidence  that  dogs 
might  perhaps  become  infected  by  eating 
chronically  infected  rodents  (Jacobs,  1957). 
Arthropod  transmission  has  been  postu- 
lated without  any  substantiation. 

One  possibility  which  deserves  inves- 
tigation is  that  a  concurrent  disease  of 
some  sort  may  be  required  for  infection 
to  succeed.    Campbell,  Martin  and  Gordon 
(1955)  found  T.  gondii  in  6%  of  268  dogs  in 
Glasgow,  Scotland  with  clinical  evidence 
of  distemper  or  its  neurological  sequellae. 
They  found  distemper  virus  inclusion  bod- 
ies in  all  these  dogs,  mentioned  that  the 
association  of  distemper  with  toxoplasmo- 
sis had  been  noted  by  several  earlier 
workers,  and  remarked  that  they  them- 
selves had  never  seen  a  case  of  "pure" 
canine  toxoplasmosis  or  of  canine  toxo- 
plasmosis associated  with  any  infection 
other  than  distemper. 

Jacobs,  Melton  and  Cook  (1955)  studied 
experimental  T.  gondii  infections  in  dogs 
and  found  that  only  young  puppies  given 
relatively  large  inocula  succumbed.    Since 


332 


SARCOCYSTIS,  TOXOPLASMA  AND  RELATED  PROTOZOA 


it  is  hardly  likely  that  dogs  are  exposed 
to  such  enormous  numbers  of  parasites, 
they  considered  that  canine  toxoplasmosis 
is  most  frequently  subclinical  or  asymp- 
tomatic.    They  believed  that  the  chance  of 
dogs  spreading  the  disease  to  man  under 
ordinary  circumstances  is  small.     On  the 
other  hand,  Cole  et  al.   (1953),  in  a  study 
of  37  people  in  a  household  containing 
ro.vo/)/rtS»;a-infected  dogs,  found  that  the 
sera  of  9  of  them  were  serologically  pos- 
itive and  5  of  them  ranged  in  titer  from 
1:80  to  1:1024.    Of  these  5  persons,  2  had 
toxoplasmic  encephalitis  and  neuroretin- 
itis,  while  1  had  Toxoplas))ia  parasitemia. 
Makstenieks  and  Verlinde  (1957)  found 
evidence  of  concurrent  infection  in  man 
and  cats  or  dogs  in  a  number  of  house- 
holds in  the  Netherlands.    These  results 
suggest  that  there  is  a  relationship  be- 
tween toxoplasmosis  in  man,  dogs  and 
cats,  altho  there  is  no  proof  of  commun- 
icability. 

Kimball  et  al.   (1960)  found  that  44% 
of  their  obstetrical  patients  who  had  lived 
on  farms  were  positive  to  the  dye  test  as 
compared  with  only  21*^^0  of  those  who  had 
never  lived  on  farms.    They  observed  a 
significant  association  between  a  positive 
dye  test  and  contact  with  farm  animals 
(cattle,  chickens,  ducks  and  geese),  and 
suggested  that  domesticated  fowls  may  be 
an  important  source  of  human  Toxoplasma 
infections. 


febrile,  non- febrile  or  subclinical.     In  the 
first,  the  onset  may  be  acute,  with  chills 
and  fever,  or  gradual.     The  temperature 
may  last  for  2  to  4  weeks  or  even  longer. 
The  lymph  nodes  are  enlarged,  the  throat 
is  often  sore,   and  the  patients  suffer  from 
malaise.     Fatigue  may  persist  for  some 
time  following  recovery,  and  the  lymph 
nodes  remain  enlarged  for  months. 

The  main  characteristic  of  the  non- 
febrile  form  is  lymphadenitis.    Its  course 
is  benign,  but  the  lymph  nodes  remain  en- 
larged for  months.    In  the  subclinical 
form,  the  only  characteristic  is  the  pres- 
ence of  swollen  but  not  tender  lymph  nodes. 

The  second  type  of  acquired  human 
toxoplasmosis  is  a  typhus-like,  exanthema- 
tous  disease.     In  addition  to  the  exanthema, 
there  may  be  atypical  pneumonia,  myo- 
carditis and  meningoencephalitis,  and  the 
termination  is  often  fatal.     Lymphadeno- 
pathy  may  or  may  not  be  present. 

The  third  type  is  a  cerebrospinal 
form,  characterized  by  fever,  encephali- 
tis,  convulsions,  delirium,   lymphadeno- 
pathy  and  a  mononuclear  pleocytosis, 
followed  by  death.     This  form  is  quite  rare. 

The  fourth  type  is  an  ophthalmic  form, 
characterized  by  chronic  chorioretinitis. 
Hogan  (1950)  described  ocular  toxoplas- 
mosis in  detail. 


Pathogenesis:     Toxoplasmosis  may 
vary  from  an  inapparent  infection  to  an 
acutely  fatal  one.    Asymptomatic  toxo- 
plasmiasis  is  the  most  common  type. 

In  man,  the  most  common  form  of 
the  disease  is  the  congenital  type  found  in 
newborn  infants.    It  is  characterized  by 
encephalitis,  rash,  jaundice  and  hepa- 
tomegaly, usually  associated  with  chor- 
ioretinitis, hydrocephalus  and  micro- 
cephaly, and  the  mortality  rate  is  high 
(Feldman,   1953;  Feldman  and  Miller, 
1956). 

Acquired  (i.e.,  non-congenital)  human 
toxoplasmosis  has  many  different  manifes- 
tations.   Siim  (1956)  divided  them  into  4 
main  types.     The  most  common  is  char- 
acterized by  lymphadenopathy.    It  may  be 


Remington,  Jacobs  and  Kaufman 
(1960)  reviewed  toxoplasmosis  in  the 
human  adult. 

The  disease  in  domestic  animals  is 
similar  to  that  in  man.    In  dogs  (cf.  Cole 
et  al.,    1953),  the  disease  is  most  serious 
in  puppies  altho  adults  may  also  die. 
Signs  include  fever,  cough,  anorexia, 
weakness,  depression,  ocular  and  nasal 
discharges,  pale  mucous  membranes, 
dyspnea,  premature  birth  and  abortion. 
The  resistance  of  dogs  to  experimental 
infection  (Jacobs,  Melton  and  Cook,  1955) 
and  the  possible  association  of  the  disease 
with  distemper  (Campbell,  Martin  and 
Gordon,  1955)  have  already  been  mentioned. 

At  necropsy,  lesions  of  pneumonitis 
are  common.    The  liver  may  be  swollen 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


333 


and  contain  grey,  necrotic  foci.     There 
may  be  ulcers  in  the  oral,  gastric  and 
intestinal  mucosa;  this  ulceration  is  per- 
haps more  common  in  dogs  than  in  other 
animals.     Lymphadenitis,   hydrothorax, 
ascites,  nephritis,  pancreatitis  and 
vaginitis  may  also  be  present. 

None  of  the  16  cases  described  by 
Campbell,   Martin  and  Gordon  (1955)  had 
clinical  signs  which  could  be  regarded  as 
specific  for  Toxoplas»ia  infection,  altho 
the  effects  of  this  parasite  may  have  been 
masked  by  intercurrent  distemper.    They 
found  Toxoplasma  in  the  lungs  of  7  dogs, 
the  mediastinal  lymph  nodes  of  6,  the 
mesenteric  lymph  nodes  of  2,  the  heart 
muscle  of  8,  the  liver  of  4,  the  pancreas 
of  3,  the  spleen  of  4,  the  kidneys  of  3, 
the  urinary  bladder  of  3  and  the  brain  of 
10. 

Makstenieks  and  Verlinde  (1957)  re- 
ported encephalitis  in  one  infected  cat  and 
abortions  in  another.     However,  Simitch 
et  al.  (1960)  reported  that  the  cat  is  rel- 
atively refractory  to  infection.     They 
could  not  infect  adult  cats  with  3  strains 
of  T.  gondii  by  either  intravenous,  intra- 
peritoneal, subcutaneous  or  oral  inocula- 
tion, and  only  part  of  the  kittens  less  than 
2  to  3  months  old  which  were  exposed  by 
these  routes  became  infected. 

The  disease  in  swine  is  similar  to 
that  in  dogs.    Pneumonitis,  ulcerative 
enteritis,  focal  hepatitis,  nephritis  and 
splenitis  have  been  described.    Young  pigs 
are  much  more  susceptible  than  adults. 

The  disease  in  cattle  is  similar  to 
that  in  dogs,  and  may  vary  considerably 
in  its  manifestations.    In  1  herd  described 
by  Sanger  et  al.   (1953),  3  cows  developed 
nervous  signs  and  died,  and  a  fourth, 
asymptomatic  cow  which  reacted  posi- 
tively to  the  toxoplasmin  skin  test  was 
found  to  have  the  organisms  in  her  colo- 
strum, uterine  wall,  spleen  and  lung.    In 
addition,  3  of  31  calves  in  this  herd  were 
born  dead,  and  4  developed  an  obscure 
disease  of  which  2  died.    In  a  second  herd, 
45  of  78  calves  died  between  the  ages  of  1 
day  to  6  months  with  signs  of  dyspnea, 
coughing,  sneezing,  nasal  discharge, 
frothing  at  the  mouth,  trembling,  head- 


shaking,  dehydration  and  occasionally 
diarrhea  with  blood  and  mucus.     Toxo- 
plasma was  recovered  from  the  lungs  of 

1  calf.    In  a  third  herd,  a  bull  died  a  week 
after  the  onset  of  illness  characterized  by 
anorexia,  weakness,  ataxia,   prostration, 
chewing  movements  and  bicycling;  Toxo- 
plasma was  found  in  his  brain.    In  a  fourth 
herd.   Toxoplasma  was  found  in  various 
tissues  of  a  7-year-old  cow  which  had  died 

2  weeks  after  parturition  with  signs  of 
anorexia,  diarrhea,  depression,  fever  and 
mastitis.    Some  calves  in  this  herd  later 
died  of  an  undiagnosed  disease. 

In  sheep,  Olafson  and  Monlux  (1942) 
and  Wickham  and  Carne  (1950)  described 
cases  of  non-suppurative  encephalomye- 
litis with  nervous  signs.    Cole  et  al.  (1954) 
isolated  Toxoplasma  from  a  flock  of  sheep 
in  which  several  ewes  and  lambs  died  of  a 
disease  with  respiratory  and  nervous  signs. 
Hartley  and  Marshall  (1957)  found  that 
toxoplasmosis  is  an  important  cause  of 
perinatal  mortality  in  sheep  in  New  Zea- 
land.   The  overall  perinatal  mortality 
rate  in  sheep  in  this  country  is  10  to  15% 
and  at  least  1/5  of  the  deaths  are  due  to 
potentially  pathogenic  organisms.    Of 
these  Toxoplasma  is  considered  the  most 
widespread  and  important.    In  a  study  of 
30  lambs  which  died  of  toxoplasmosis  on 
15  farms,  Hartley  and  Marshall  considered 
that  2/3  died  before  birth  and  the  other 
third  died  either  at  the  end  of  an  apparently 
normal  parturition  or  a  few  hours  after- 
wards.   The  cotyledons  of  the  fetal  mem- 
branes bore  small,  necrotic  foci  which 
contained  clumps  of  proliferative  tropho- 
zoites. 

Ratcliffe  and  Worth  (1951)  described 
an  epidemic  of  toxoplasmosis  in  squirrel 
monkeys  [Saimiri  sciiirea)  in  the  Phila- 
delphia Zoo,  and  Benirschke  and  Richart 
(1960)  described  a  fulminating  acute  case 
in  a  young  cotton-topped  marmoset 
(Oedipomidas  oedipus). 

In  naturally  affected  chickens,  Bie- 
ring-Sorensen  (1956)  reported  that  emac- 
iation and  central  nervous  system  signs 
were  the  principal  signs.    Necrosis  of  the 
optic  chiasma  and  of  the  retina  with  cellu- 
lar infiltration  were  characteristic. 
Erichsen  and  Harboe  (1954)  described 


334 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


lesions  of  necrotizing  pneumonitis,  peri- 
and  myocarditis,  necrotizing  hepatitis, 
focal  necrotizing  encephalitis  and  ulcera- 
tive gastroenteritis. 

Altho  natural  infections  occur  in  the 
chicken,  Jones  el  al.   (1959)  found  that 
this  bird  is  remarkably  tolerant  to  the 
parasite.    Disease  can  be  produced  exper- 
imentally only  by  large  inocula  in  mature 
birds,  and  even  very  young  chicks  can 
survive  inoculation  of  enough  parasites  to 
kill  rabbits,  guinea  pigs  and  hamsters. 
Parasitemia  appears  in  2  to  3  days  after 
inoculation  and  disappears  spontaneously, 
seldom  persisting  longer  than  2  weeks. 
Even  when  enormous  numbers  of  para- 
sites were  injected  into  large  birds,  Toxo- 
plas»ia  was  rarely  found  in  the  tissues 
more  than  40  days  later. 

The  histopathology  of  toxoplasmosis 
has  been  reviewed  by  Frenkei  (1956a)  and 
Smith  and  Jones  (1957).    In  the  brain, 
ToxoplasDia  multiplies  in  the  neurons  and 
other  cells  and  may  cause  cellular  and 
interstitial  necrosis.    Sometimes  infarc- 
tion necrosis  causes  extensive  lesions. 
Whenever  aqueductal  obstruction  and  in- 
ternal hydrocephalus  are  present,  peri- 
ventricular vasculitis  and  necrosis  are 
generally  observed;  these  constitute  a 
lesion  unique  for  toxoplasmosis. 

Koestner  and  Cole  (1960)  studied  the 
neuropathology  of  canine  toxoplasmosis 
in  detail.    They  found  lesions  attributed  to 
Toxoplasma  in  the  central  nervous  systems 
of  47  out  of  63  experimentally  or  naturally 
infected  dogs  with  confirmed  toxoplasmo- 
sis, and  they  found  Toxoplasma  itself 
microscopically  in  the  central  nervous 
systems  of  25  of  the  animals.    The  para- 
sites themselves  were  found  in  the  cere- 
bral cortex  and  basal  ganglia  of  17  dogs, 
in  the  midbrain  of  12,  the  cerebellum  of 
9,  the  pons  of  8,  the  medulla  of  13  and  the 
spinal  cord  of  4.     Lesions  were  found  in 
the  cerebral  cortex  and  basal  ganglia  of 
47,  the  midbrain  of  28,  the  cerebellum 
of  21,  the  pons  of  20,  the  medulla  of  29 
and  the  spinal  cord  of  9.    In  acute  cases, 
the  lesions  consisted  of  vascular  damage 
and  focal  necrosis;  extracellular  troph- 
ozoites were  found  associated  with  the 
necrotic  foci.    In  chronic  cases,  glial 


nodules  and  repair  were  seen,  and  intra- 
cellular parasites  and  cysts  were  present. 
In  reactivated  latent  toxoplasmosis,  rup- 
tured cysts  and  a  hyperergic  response 
were  present. 

The  lesions  in  the  liver  consist  of 
small,  sharply  delimited  areas  of  coagu- 
lation necrosis  in  any  part  of  the  hepatic 
lobules.     The  hepatic  cells  surrounding 
them  are  apparently  normal,  and  there  is 
little  or  no  cellular  reaction.    The  lungs 
contain  small,  grey,  tumor-like  nodules 
scattered  thru  1  or  all  the  lobes.    These 
consist  of  alveoli  filled  with  large  mono- 
nuclear cells  and  leucocytes;  the  cells  of 
the  alveolar  walls  are  cuboid  or  columnar 
and  contain  aggregations  of  Toxoplasma. 
The  lymph  nodes  are  usually  involved. 
They  are  enlarged  to  several  times  their 
normal  size  and  contain  extensive  areas 
of  coagulation  necrosis.    These  areas  are 
irregular  in  outline,  with  sharply  demar- 
cated boundaries  and  slight  leucocytic  in- 
filtration around  their  margins.      Toxo- 
plasma is  present  around  these  areas,  in 
the  endothelial  cells  of  the  veins,  in  mono- 
cytes or  free  in  the  tissues.    There  may 
be  ulcers  in  the  intestine.    These  may  in- 
vade the  muscularis,   producing  chronic, 
necrotizing  lesions  followed  by  granula- 
tion.   Granulomatous  chorioretinitis  is 
sometimes  seen  in  man,  but  ocular  infec- 
tions are  apparently  rare  in  animals. 

Weinman  and  Klatchko  (1950)  found 
that  a  toxin  which  they  called  toxotoxin  is 
produced  in  the  peritoneal  fluid  of  animals 
infected  with  ToxoplasDia.    It  is  heat  sta- 
ble and  usually  kills  mice  in  1  or  2  min- 
utes following  intravenous  injection.    Cook 
and  Jacobs  (1958),  however,  found  no 
evidence  of  toxin  production  in  tissue  cul- 
tures of  the  organism. 

Immunity:     There  is  a  definite  age 
immunity  against  toxoplasmosis.     Con- 
genital infections  are  the  most  common, 
and  the  mothers  usually  do  not  show  signs 
of  disease  themselves.    Young  animals 
are  more  susceptible  than  adults. 

In  infections  acquired  after  birth, 
humoral  antibodies  appear  at  the  time  that 
the  parasitemia  disappears  and  are  prob- 
ably responsible  in  part  for  clearing  the 


SARCOCYSTIS,   TOXOPLASMA   AND  RELATED  PROTOZOA 


335 


blood  of  parasites.     Humoral  antibodies 
are  not  effective  against  intracellular 
parasites,  however. 

At  least  2  types  of  humoral  antibodies, 
complement  fixing  and  cytoplasm  modify- 
ing, are  produced  against  Toxoplasma. 
The  latter  are  revealed  by  the  Sabin-Feld- 
man  dye  test.    They  appear  earlier  in  the 
course  of  the  disease  than  complement 
fixing  antibodies  and  persist  much  longer. 

The  dye  test  was  introduced  by  Sabin 
and  Feldman  (1948)  and  has  been  des- 
cribed in  detail  by  Sabin  et  al.  (1952).    It 
is  based  on  the  fact  that  both  the  cyto- 
plasm and  nucleus  of  Toxoplasma  tropho- 
zoites stain  deeply  with  alkaline  methylene 
blue  after  incubation  with  normal  serum, 
but  that  after  incubation  with  antibody- 
containing  serum  only  the  nuclear  endo- 
some  will  stain.    According  to  Lelong  and 
Desmonts  (1952),  the  dye  test  antibodies 
act  by  producing  partial  lysis  of  the  or- 
ganisms thru  a  modified  Pfeiffer  phenom- 
enon in  which  the  parasites  lose  those 
cytoplasmic  constituents  which  are  ordi- 
narily stained  by  methylene  blue.    Kulasiri 
and  Dasgupta  (1959)  found  that  ribonucleic 
acid  disappears  during  incubation  in  a  pos- 
itive reaction,  and  suggested  that  this  is 
the  reason  the  organisms  no  longer  stain. 

The  antibody  itself  is  heat  stable,  but 
a  fairly  large  amount  of  a  heat-labile, 
complement-like  "accessory"  factor  is 
also  necessary.    This  is  apparently  a 
mixture  of  the  C2,  C3  and  C4  factors  of 
complement  plus  properdin  (Gronroos, 
1956). 

In  carrying  out  the  dye  test,  a  series 
of  serum  dilutions  is  used,  and  a  titer  of 
1:16  is  considered  diagnostic.    The  dye 
test  titer  usually  reaches  a  high  level  by 
the  end  of  the  second  week  after  infection; 
in  active  disease,  titers  above  1:1000  are 
found  in  a  month  or  more.    These  anti- 
bodies usually  persist  for  a  number  of 
years,  probably  for  more  than  a  decade, 
altho  their  titer  declines  slowly. 

The  trophozoites  used  in  the  dye  test 
can  be  obtained  from  peritoneal  exudate 
or  tissue  culture.    These  fluids  sometimes 


contain  a  soluble  antigen  in  sufficiently 
high  titer  to  block  the  test  partly  or  com- 
pletely (Jacobs  and  Cook,  1954).    Antibody 
in  mouse  peritoneal  fluid  may  give  rise  to 
false  positive  tests  (Frenkel,   1956).    In 
addition,  a  prozone  phenomenon  may  often 
occur,   so  that  a  full  range  of  dilutions  up 
to  1:1024  at  least  must  be  tested. 

The  dye  test  is  not  necessarily  spe- 
cific for  Toxoplas))ia.     Muhlpfordt  (1951) 
and  Awad  and  Lainson  (1954)  reported 
cross  reactions  with  Sarcocystis  tenella, 
and  Awad  (1954)  even  developed  a  modified 
dye  test  for  Toxoplasma,  using  S.  tenella 
trophozoites. 

On  the  other  hand,  Cathie  and  Cecil 
(1957)  were  unable  to  confirm  this  latter 
test.     Moscovici  (1954)  found  no  dye  test 
cross  reaction  between  T.  gondii  and  S. 
tenella.    Jacobs  (1956)  found  no  dye  test 
cross  reaction  between  Toxoplasma  and 
Trypanosoma  criizi,  Plasmodium  berghei, 
P.  galUnaceum,  Eimeria  tenella,  Hepato- 
zoon  sp.  in  squirrels,  or  Sarcocystis  in 
rhesus  monkeys,  but  did  observe  cross 
reactions  at  titers  up  to  1:4  between  Toxo- 
plasma and  Enceplialitozoon  in  rats  and 
up  to  1:16  between  Toxoplasma  and  Bes- 
noitia  jellisoni  in  rabbits.    Cathie  (1957) 
found  the  dye  test  to  be  specific  for  Toxo- 
plasma, for  human  sera  at  least;  the  test 
sera  should  be  inactivated. 

The  complement  fixation  test  was  de- 
veloped by  Warren  and  Sabin  (1943)  and 
Sabin  (1949).    Complement  fixing  anti- 
bodies rarely  appear  earlier  than  1  month 
after  infection,  and  decrease  relatively 
rapidly  with  time.    In  60  children  with 
congenital  toxoplasmosis  studied  by  Eich- 
enwald  (1956),  complement  fixing  anti- 
bodies had  disappeared  from  44  at  5  years 
of  age  and  from  8  more  at  7  years,  altho 
all  but  3  still  had  dye  test  antibodies.    In 
15  cases  of  active  toxoplasmosis  studied 
by  Makstenieks  and  Verlinde  (1957),  the 
complement  fixation  reaction  became  neg- 
ative in  6  to  9  months  while  the  dye  test 
was  still  positive  at  the  end  of  4  years. 

A  positive  complement  fixation  titer 
of  1:32  or  above  is  considered  to  indicate 
relatively  recent  infection. 


336 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


The  antigen  for  this  test  may  be  pre- 
pared from  protozoa  in  chicken  embryos, 
mouse  brain,  peritoneal  exudate  or  tissue 
cultures,     Eichenwald  (1956)  preferred 
chorioallantoic  membrane  or  tissue  cul- 
ture because  peritoneal  exudate  has  a 
strong  anticomplementary  activity. 

Jacobs  and  Lunde  (1957)  and  Lunde  and 
Jacobs  (1958)  reported  on  a  hemagglutina- 
tion test  for  toxoplasmosis.    It  agreed 
very  closely  with  the  dye  test  in  a  survey 
of  12  human  serum  specimens  from  Trin- 
idad; 54.  5%  were  positive  by  both  tests. 
They  considered  that  the  hemagglutination 
test  was  adequate  for  survey  purposes  but 
that  more  work  must  be  done  to  determine 
its  usefulness  in  the  diagnosis  of  acute  in- 
fections. 

A  skin  test  using  "toxoplasmin"  was 
developed  by  Frenkel  (1948,  1949).     Pos- 
itive reactions  appear  in  man,  rhesus 
monkeys  and  guinea  pigs  3  to  4  weeks 
after  infection.     However,  they  do  not 
appear  in  about  10%  of  the  individuals, 
and  the  test  remains  negative  in  most  in- 
fected rodents  and  in  humans  with  highly 
active  disease. 

Hook  and  Faber  (1957)  found  that  anti- 
genic activity  in  both  the  dye  and  comple- 
ment fixation  tests  is  associated  with  a 
protein  component  of  sonically  fragmented 
T.  gondii  which  was  precipitated  by  30% 
saturated  ammonium  sulfate  at  pH  7. 

Diagnosis:     The  most  certain  method 
of  diagnosis  of  toxoplasmosis  is  by  isola- 
tion of  the  parasites  themselves  by  inocu- 
lation of  experimental  animals.    Eichen- 
wald (1956)  considered  mice,  hamsters 
and  guinea  pigs  the  most  sensitive  ani- 
mals in  his  experience,  and  recommended 
the  administration  of  cortisone  to  the  test 
animals  for  3  to  5  days  before  inoculation 
in  order  to  increase  the  chance  of  isolating 
the  organisms.    Jones  el  al.   (1958),  how- 
ever, found  no  advantage  in  using  cortisone. 
They  recommended  intraperitoneal  inocu- 
lation of  mice.    Simitch,   Petrovitch  and 
Brodjochki  (1956)  considered  the  ground 
squirrel,  Citellus  cilelliis,  to  be  the  ani- 
mal of  choice,  while  Lainson  (1957)  found 
that  the  multimammate  rat  (Mastoniys 
coucha)  is  more  susceptible  than  the  house 


mouse  and  suggested  that  it  might  prove 
more  suitable.  After  isolation,  the  or- 
ganism should  be  identified  serologically. 

Despite  the  disadvantages  discussed 
above,  the  dye  test  still  appears  to  be  the 
most  satisfactory  serological  test  avail- 
able at  present.    Eichenwald  (1956)  con- 
sidered the  complement  fixation  test  useful 
only  as  an  adjunct  to  it,  and  the  hemagglu- 
tination test  requires  further  study.    A 
neutralization  test  was  introduced  by  Sabin 
and  Ruchman  (1942).    It  is  now  carried  out 
chiefly  in  tissue  cultures.    However,  ac- 
cording to  Eichenwald  (1956),  it  is  of  use 
primarily  as  a  research  tool  to  study  cell- 
parasite  relationships. 

Serologic  studies  with  fluorescein- 
labelled  Toxoplasma  antibody  have  also 
been  carried  out  (Goldman,  Carver  and 
Sulzer,  1957).    This  technic  shows  prom- 
ise.   The  antibody  does  not  agglutinate 
Besnoitia. 

Toxoplasma  can  also  be  found  in 
stained  smears  and  sections  of  tissues  and 
exudates.    It  must  be  differentiated  from 
similar  organisms,  including  Sarcocystis, 
Besnoitia  and  Enceplialitozoon,  and  this  is 
not  always  possible  on  morphological 
grounds  alone. 

Cultivation:      Toxoplasma  grows 
reaily  in  chicken  embryos  and  tissue  cul- 
ture.   It  was  first  cultivated  in  both  by 
Levaditi  el  al.  (1929).    Cook  and  Jacobs 
(1958)  cultivated  it  in  a  wide  variety  of 
mammalian  and  avian  tissue  cultures,  in- 
cluding various  human,  monkey,  mouse, 
rabbit,  guinea  pig,  rat,  ox  and  chick  nor- 
mal tissues,  and  in  human  and  mouse  can- 
cer cells.    They  also  reviewed  the  litera- 
ture on  the  subject. 

Eyles,  Coleman  and  Cavanaugh  (1956) 
preserved  T.  gondii  for  as  long  as  209 
days  by  freezing  it  in  the  presence  of  5% 
glycerol  and  storing  it  at  -70°  C.    They 
used  the  technic  routinely  for  preservation 
of  their  strains. 

Treatment:     No  satisfactory  treatment 
for  toxoplasmosis  is  known.     Promising 
results  have  been  obtained  by  the  use  of 
pyrimethamine  and  sulfonamides  simul- 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


337 


taneously;  the  two  drugs  act  synergistic- 
ally  (Eyles,   1956). 

For  treatment  of  human  ocular  toxo- 
plasmosis, Remington,  Jacobs  and  Kauf- 
man (1960)  recommended  that  the  patients 
receive  2  oral  loading  doses  of  200  mg 
pyrimethamine  and  2  g  triple  sulfonamides 
each  on  the  first  day  of  therapy,  and  that 
thereafter  they  be  given  25  mg  pyrimeth- 
amine and  2  g  triple  sulfonamides  twice  a 
day  for  5  weeks. 

Prevention  and  Control:     In  the  ab- 
sence of  solid  information  regarding  the 
mode  of  spread  of  toxoplasmosis,  specific 
preventive  measures  cannot  be  recom- 
mended.   The  measures  customarily  em- 
ployed to  control  infectious  diseases 
should  be  used.    In  addition,  since  many 
wild  mammals  are  apparently  reservoir 
hosts,  contact  with  them  should  be  avoided 
and  rodents  should  be  controlled.    Man  and 
his  domestic  animals  apparently  receive 
their  infections  from  the  same  source,  but 
it  is  not  clear  whether  they  can  give  it  to 
each  other. 


Genus  BESNOITIA   Henry,   1913 

In  this  genus  the  pseudocysts  are 
found  in  the  subcutaneous  and  connective 
tissues,  serosal  membranes  and  else- 
where.   They  have  a  heavy  wall  containing 
nuclei,  and  are  not  divided  into  compart- 
ments.    A  synonym  of  this  name  is  Fibro- 
cystis  Hadwen,   1922.    The  name  Globid- 
iiim  has  often  been  used  instead  oi  Besnoitia 
for  members  of  this  genus,  but  this  is  in- 
correct, since  Globidium  is  a  synonym  of 
Eimeria. 

The  "cyst"  wall  is  said  by  Pols  (1954a) 
to  be  formed  entirely  by  the  host,  so  that 
it  is  actually  a  pseudocyst.    The  wall  is 
composed  of  a  thin  inner  layer  containing 
a  number  of  flattened,  giant  nuclei  and  a 
thick,  homogeneous  or  concentrically 
laminated,  eosinophilic  outer  wall.    It  is 
positive  to  the  periodic  acid-Schiff  test, 
and  the  reaction  is  not  affected  by  salivary 
digestion  (Frenkel,   1956). 

The  trophozoites  are  banana-shaped, 
crescentic  or  elongate  oval,  and  slightly 


pointed  at  one  end.    They  move  by  body 
flexion.    They  reproduce  by  binary  fission 
or  endodyogeny;  multiple  fission  has  also 
been  described. 

This  genus  is  poorly  known  and  has 
often  been  confused  with  Ei)iieria  and  Sar- 
cocystis.     Species  have  been  found  in  cat- 
tle, horses,  reindeer,  caribou,  rodents 
and  opossums.    A  somewhat  similar  or- 
ganism described  by  Campbell  (1954)  as 
the  cause  of  Bangkok  hemorrhagic  disease 
of  chickens  in  Thailand  is  more  probably 
a  fungus. 


BESNOITIA  BESNOITI 
(MAROTEL,   1912)  HENRY,   1913 

Synonyms:     Sarcocystis  besnoiti, 
Gastrocystis  robini,   Gastrocystis  besnoiti, 
Globidium  besnoiti.     The  nomenclature  of 
this  species  has  been  discussed  by  Jelli- 
son  (1956). 

Disease:     Besnoitiosis,  olifantvel. 

Hosts:     Cattle.     Pols  (1954)  infected 
the  domestic  rabbit  experimentally. 

Location:     The  cysts  are  in  the  cutis, 
subcutis,  connective  tissue,  fascia,  ser- 
osae,  mucosae  of  the  nose,  larynx  and 
trachea,  and  other  places.    Trophozoites 
are  in  the  blood,  either  extracellularly  or 
in  monocytes,  and  in  smears  of  lymph 
nodes,  lungs,  testes,  etc. 

Geographic  Distribution:     Europe 
(southern  France,  Pyrenees,  Portugal), 
Africa  (South  Africa,  Belgian  Congo, 
Angola,  Sudan). 

Prevalence:     According  to  Hofmeyr 
(1945),  B.  besnoiti  is  endemic  in  South 
Africa  thruout  the  whole  of  the  Bushveld 
area  from  the  Western  Transvaal  to 
Potgietersrust  district  and  probably  fur- 
ther north.    He'rin  (1952)  found  it  in  about 
2%  of  the  cattle  he  examined  in  Ruanda- 
Urundi,  Belgian  Congo.     Leitao  (1949) 
discussed  its  occurrence  in  Portugal. 

Morphology:     The  pseudocysts  are 
more  or  less  spherical,  without  septa, 
and  about  100  to  500  (i  in  diameter.    The 


338 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


pseudocyst  wall  is  composed  of  a  thin 
inner  layer  containing  several  flattened, 
giant  nuclei  and  a  thick,  homogeneous  or 
concentrically  laminated  outer  wall.    The 
trophozoites  in  the  pseudocysts  are  cres- 
centic  or  banana-shaped,  with  1  end  pointed 
and  the  other  rounded.    According  to  Pols 
(1954)  the  trophozoites  in  blood,  lung  and 
testis  smears  of  experimentally  infected 
rabbits  measure  5  to  9  by  2  to  5  fi  and  are 
usually  elongate  oval  and  slightly  pointed 
at  one  end.    Banana-shaped  and  crescentic 
forms  are  found  more  rarely.    The  nucleus 
is  more  or  less  central. 

Life  Cycle:     The  natural  mode  of 
transmission  is  unknown,  but  it  is  prob- 
ably thru  ingestion.     Hofmeyr  (1945)  gave 
circumstantial  evidence  that  the  infection 
is  spread  thru  contaminated  watering 
troughs  in  South  Africa,    Jellison,   Fuller- 
ton  and  Parker  (1956)  transmitted  the  re- 
lated B.  jellisoni  to  house  mice  by  feeding 
trophozoites  from  cysts  of  infected  deer- 
mice  or  from  peritoneal  fluid  of  infected 
house  mice. 

Cuille  and  Chele  (1937),  Barrairon 
(1938)  and  Pols  (1954)  transmitted  B. 
besnoiti  to  cattle  by  intravenous  injection 
of  blood  from  cattle  in  the  primary  stage 
of  the  disease.     Pols  also  infected  an  ox 
by  intraperitoneal  injection  and  rabbits 
by  intravenous,  intraperitoneal  and  sub- 
cutaneous injection  of  blood.     He  passed 
the  protozoon  from  a  rabbit  thru  2  gener- 
ations of  cattle  and  back  to  a  rabbit. 
Later  (1954a)  he  reported  having  passed 
it  thru  19  serial  passages  in  the  rabbit. 
He  was  unable  to  infect  mice,  rats  and 
guinea  pigs. 

The  incubation  period  in  the  cattle 
infected  by  Pols  varied  from  6  to  10  days, 
and  that  in  the  rabbits  from  6  to  16  days. 
It  was  followed  by  a  thermal  reaction 
which  lasted  2  to  5  days.    Cysts  were 
found  in  the  skin  of  naturally  and  artifi- 
cially infected  cattle  6  to  28  days  after  the 
beginning  of  the  temperature  reaction. 

Pols  (1954a)  described  cyst  formation 
in  experimentally  infected  rabbits.    The 
initial  stages  were  seen  as  early  as  16  to 
18  days  after  inoculation.    When  a  tropho- 
zoite invades  a  histiocyte,  a  vacuole  is 


formed  around  it.     The  trophozoites  in 
tissue  sections  measure  about  3  by  1.  5 /i, 
and  the  vacuoles  are  about  8/j,  in  diameter. 
The  trophozoites  multiply  by  binary  fission; 
Pols  saw  a  few  cases  of  multiple  fission 
but  they  were  so  rare  that  he  considered 
them  aberrant.    It  is  possible  that  the  troph- 
ozoites may  actually  divide  by  endodyogeny, 
since  Goldman,  Carver  and  Sulzer  (1958) 
stated  that  this  takes  place  in  B.  jellisoni. 

The  nucleus  of  the  host  cell  begins  to 
divide  at  the  same  time  that  the  tropho- 
zoites do,  forming  a  multinucleate  cell. 
As  the  parasites  multiply  within  the  vac- 
uole, the  latter  becomes  larger  and  the 
host  cell  c3d;oplasm  is  compressed  to  form 
a  narrow  rim.    This  is  the  middle  layer  of 
the  pseudocyst  wall.    Within  it  is  an  inner 
membrane  which  can  be  seen  only  if  2 
trophozoites  have  invaded  the  same  host 
cell,  in  which  case  it  forms  a  thin  line  be- 
tween the  resultant  cysts;  it  is  uncertain 
whether  it  is  formed  by  the  parasite,  the 
host  or  both.    Concentric  layers  of  colla- 
genous fibers  are  laid  down  around  the  host 
cell  to  form  a  hyaline  capsule  around  the 
whole;  this  is  the  outer  layer  of  the  pseudo- 
cyst. 

Pathogenesis:     The  most  complete 
description  of  bovine  besnoitiosis  has  been 
given  by  Hofmeyr  (1945).    He  found  it  in 
cattle  of  all  ages  from  6  months  up.    Aged 
animals  were  also  affected.    He  recognized 
3  stages  in  the  course  of  the  disease: 

The  febrile  stage.    The  first  sign  of 
besnoitiosis  is  fever,  up  to  107°  F  but 
usually  lower.    The  animal  develops  a 
photophobia  and  stays  in  the  shade.    The 
hair  loses  its  luster,  especially  along  the 
buttocks,  limbs,  flanks,  lower  abdomen 
and  neck.    Marked  anasarca  develops, 
especially  along  the  lower  line  but  some- 
times over  the  whole  body.    The  swellings 
are  warm  and  tender.    The  animals  have 
a  stiff  gait  and  are  reluctant  to  move.    The 
pulse  is  fast,  respiration  is  rapid,  and 
rumination  decreases  or  ceases.    Diarrhea 
is  sometimes  present,  and  abortions  are 
not  uncommon.    The  lymph  nodes,  espe- 
cially the  prescapular  and  prec rural  ones, 
are  enlarged.     Lachrymation  and  hyper- 
emia of  the  sclera  are  present.    The  cor- 
nea is  studded  with  whitish,  elevated  specks 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


339 


which  are  Besnoitia  cysts.    The  nasal 
mucosa  becomes  bright  red  and  is  also 
studded  with  cysts.    The  mucosa  may  be 
swollen  and  there  may  be  a  rapidly  pro- 
gressive rhinitis;  it  starts  with  a  mucous 
discharge  which  later  becomes  thick, 
hemorrhagic  and  mucopurulent,  forming 
dark  brown  crusts  in  the  nostrils.    If  the 
pharynx  and  larynx  are  involved,  there  is 
a  short  cough.    This  stage  may  last  5  to 
10  days.    The  acute  stage  then  subsides 
and  the  second  stage  begins. 

The  depilatory  stage.    In  this  stage, 
the  pathologic  and  clinical  pictures  are 
dominated  by  skin  lesions.    The  skin  be- 
comes greatly  thickened  and  loses  its 
elasticity.    The  hair  falls  out  over  the 
swollen  parts,  and  the  skin  on  the  flexor 
surfaces  cracks  and  a  sero-sanguinous 
fluid  oozes  out.    Necrosis  of  the  skin  de- 
velops on  the  parts  in  contact  with  the 
ground  when  the  animal  lies  down.    Toward 
the  end  of  this  stage,  hard  sitfasts  develop 
on  the  sides  of  the  stifles,  brisket  and  el- 
bows.    The  anasarca  subsides,  leaving 
the  skin  with  typical,  broad  wrinkles  along 
the  lower  line.    The  photophobia  decreases, 
and  grazing  is  resumed  in  many  cases. 
Death  may  occur  at  this  stage.    If  not,  the 
stage  lasts  2  weeks  to  about  a  month  and 
gradually  passes  into  the  third  stage. 

The  seborrhea  sicca  stage.     In  this 
stage,  most  of  the  hair  on  the  previously 
anasarcous  skin  has  been  lost,  and  the 
denuded  parts  are  covered  by  a  thick, 
scurfy  layer.    The  sitfasts  crack  away 
from  the  underlying  tissues,  fissures  re- 
main in  the  flexor  surfaces,  the  skin 
hardens,  and  deep  scars  show  plainly. 
The  hide  resembles  that  of  an  elephant, 
and  the  animal  looks  as  tho  it  has  mange. 
The  lymph  nodes  are  permanently  en- 
larged, the  protozoan  cysts  remain,  and 
the  animal  is  listless  and  debilitated. 

In  light  infections  in  which  there  has 
been  little  hair  loss,  the  animals  become 
practically  normal  in  appearance,  but  in 
more  severe  cases  recovery  requires 
months  or  even  years,  and  the  changes  in 
the  cutis  and  subcutis  and  the  loss  of  most 
of  the  hair  are  permanent.    In  convales- 
cent animals  the  remaining  hair  forms 


patterns  resembling  the  markings  on  a 
giraffe. 

The  morbidity  in  a  herd  varies  from 
1  to  20%,  and  the  mortality  is  about  10%. 

Diagnosis:     Besnoitiosis  can  be  diag- 
nosed by  biopsy  examination  of  affected 
skin  or  other  areas.    The  spherical,  en- 
capsulated cysts  are  pathognomonic. 
There  may  be  a  severe  granulomatous  re- 
action in  young  cysts  or  those  which  have 
broken  and  released  their  trophozoites, 
but  there  is  usually  little  reaction  except 
for  the  formation  of  the  hyaline  wall 
around  the  mature  cysts. 

Trophozoites  are  often  found  in  blood 
smears,  sometimes  in  large  numbers, 
but  most  of  them  are  introduced  when  a 
cyst  is  cut  in  obtaining  blood. 

Treatment:     None  known. 

Prevention  and  Control:     Until  the 
mode  of  transmission  is  learned,  the  ap- 
propriate preventive  measures  must  re- 
main unknown.    However,  sanitary 
measures  would  prevent  the  spread  of 
besnoitiosis  if  transmission  is  by  ingestion, 
and  insect  control  would  prevent  it  if  trans- 
mission is  by  biting  insects,  as  some  be- 
lieve. 


BESNOITIA  BENNETTI 
BABUDIERI,   1932 

Hosts:     Horse,  ass. 

Location:     Same  as  B.  besnoiti. 

Geographic  Distribution:     Africa 
(Sudan,  South  Africa),  Europe  (southern 
France,  Pyrenees),  North  America 
(Mexico,  United  States). 

Prevalence:     Relatively  uncommon. 
Bennett  (1927,  1933)  recorded  this  species 
from  3  horses  in  the  Sudan,  all  of  which 
originated  in  the  Nuba  Mountains  of  South- 
ern Kordofan.    Schulz  and  Thorburn  (1941) 
found  it  in  South  Africa.    Jones  (19  57)  found 
it  in  the  skin  and  other  tissues  of  small 
burros  which  had  been  imported  into  the 


340 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


United  States  from  Mexico.  Gorlin  et  al. 
(1959)  found  it  in  the  lip  of  a  burro  of  un- 
specified origin  in  the  United  States. 

Morphology:     Same  as  B.  besnoiti. 
According  to  Bennett  (1933),  the  tropho- 
zoites measure  10  by  4 /j,. 


B. 


Life  Cycle: 
besnoiti. 


Presumably  same  as 


Pathogenesis:     According  to  Bennett 
(1933),  the  horse-owning  tribes  in  Southern 
Kordofan  know  this  disease  quite  well,  can 
differentiate  it  from  mange  and  ringworm 
and  have  given  it  a  separate  Arabic  name. 
It  was  said  that  one  tribe  which  not  many 
years  before  had  owned  600  to  800  horses, 
now  had  less  than  50  due  to  besnoitiosis. 
On  the  other  hand,  the  organism  produces 
no  grossly  recognizable  disease  in  bur- 
ros, according  to  Jones  (1957). 

The  disease  as  described  by  Bennett 
(1933)  in  horses  is  a  chronic  one,   running 
a  course  of  many  months.    Affected  ani- 
mals are  weak  and  dejected,  altho  their 
appetite  is  good.    The  skin  is  scurfy  and 
thickened,  and  contains  many  scabs  and 
whitish  scars.     The  hair  may  be  destroyed 
by  the  lesions.    The  conjunctiva  is  a  pecul- 
iar brick  red  color,  with  a  few  petechiae. 
The  temperature  is  slightly  elevated. 

The  muscles  in  advanced  cases  are 
pale  brown  and  friable,  but  contain  no 
parasites.    The  Besnoitia  cysts  are 
abundant  in  the  skin  and  may  also  be  found 
in  the  mucous  membrane  covering  the 
larynx,  nostrils,  soft  palate,  etc. 

Diagnosis:     Same  as  for  B.  besnoiti. 

Treatment:     None  known. 


BESNOITIA    TARANDI 
(HADWEN,   1922)  NOV.  COMB. 

Synonyms:     Fibrocystis  tarandi  Had- 
wen,  1922. 

Disease:     Besnoitiosis,  corn-meal 
disease. 

Hosts:     Reindeer,  caribou. 

Location:     The  cysts  occur  in  the 
fibrous  connective  tissues,  especially  in 
the  periosteum  and  on  the  surface  of  the 
tendons. 

Geographic  Distribution:     Alaska. 

Prevalence:     Hadwen  (1922)  found  this 
parasite  in  a  number  of  herds  of  reindeer 
and  in  caribou  in  Alaska. 

Morphology:     The  cysts  are  spherical 
and  100  to  450/1  in  diameter  with  a  mean 
of  275 /i.    They  are  composed  of  3  layers, 
of  which  the  outermost  is  thick  and  fibrous, 
with  concentrically  arranged  fibers,  the 
middle  layer  is  clear  and  hyaline,  and  the 
inner  layer  forms  a  thin  lining.     The  cysts 
are  not  compartmented.     The  cyst  contents 
are  dark  brown.    The  trophozoites  are 
spindle  shaped,  with  a  central  nucleus, 
and  measure  7  by  1.8|_l  in  alcohol-fixed 
material. 

Life  Cycle:     Unknown. 

Pathogenesis:     Reindeer  owners  call 
besnoitiosis  "corn-meal  disease"  because 
of  the  granular  nature  of  the  lesions.     The 
cysts  may  be  found  in  the  periosteum  of  all 
of  the  bones.    When  the  periosteum  is 
stripped  off,  small  pits  corresponding  to 
their  position  are  found  in  the  bone  itself. 
They  are  also  found  on  the  surface  of  the 
tendons,  where  they  cause  similar  pits. 


Remarks:     It  is  possible  that  the 
same  species  of  Besnoitia  affects  both 
cattle  and  horses,  and  that  B.  ben>ietti  is 
a  synonym  of  B.  besnoiti.     Until  this  is 
shown  to  be  the  case  by  cross-transmis- 
sion studies,  however,  it  is  considered 
best  to  retain  separate  names  for  the 
forms  in  cattle  and  equids. 


BESNOITIA  JELLISONI 
FRENKEL,   1955 

This  species  was  described  from  the 
deermouse,  Peromyscus  nianiculatiis, 
in  Idaho  by  Frenkel  (1955).     He  trans- 
mitted it  by  intraperitoneal  or  intravenous 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


341 


inoculation  of  peritoneal  fluid  from  acutely 
ill  animals  or  by  trophozoites  from  cysts 
of  chronically  affected  animals  to  white 
mice,  rats,  hamsters,  voles  (Microtiis), 
ground  squirrels  (Citellus)  and  chicken 
embryos,  but  not  to  guinea  pigs,  rabbits, 
the  ox,  rhesus  monkey,  baby  chick,  ca- 
nary or  pigeon  (Frenkel,  1956a).    Jellison, 
Fullerton  and  Parker  (1956)  transmitted  it 
to  mice  by  feeding  trophozoites  from  cysts 
or  peritoneal  fluid  of  affected  animals. 

The  cysts  occur  in  the  connective 
tissue  and  on  the  serosae  of  many  of  the 
viscera  organs,  including  the  intestine, 
liver,  spleen,  heart,  testes,  etc.    They 
are  spherical,  up  to  1  mm  in  diameter, 
with  thick  walls  containing  giant  nuclei. 
The  wall  is  positive  to  the  periodic  acid- 
Schiff  reaction  and  is  unaffected  by  salivary 
digestion. 

The  trophozoites  are  crescent-shaped, 
with  a  central  nucleus.    According  to 
Goldman,   Carver  and  Sulzer  (1957,   1958), 
who  studied  them  after  staining  with  Bodian 
silver  stain,  they  have  a  truncated,  cap- 
like cone  at  the  anterior  end  with  1  or 
more  rod-  or  fibril-like  structures  ex- 
tending posteriorly  from  it,  a  dark-stain- 
ing posterior  granule  and  a  nucleus  con- 
sisting of  a  larger,  less  dense  portion  and 
a  smaller,  more  compact  structure.    They 
reproduce  by  endodyogeny. 

B.  jellisoni  may  cause  an  acute,  fatal 
disease  or  a  chronic  one. 


for  a  final  decision  to  be  made.    It  differs 
from  Toxoplasma  in  that  its  trophozoites 
are  smaller  and  rod-shaped;  the  clusters 
of  trophozoites  in  the  brain  are  not  sur- 
rounded by  an  argyrophilic  cyst  wall,  altho 
they  are  said  to  form  a  pseudocyst;  En- 
cephalitozooji  stains  very  poorly  with 
hematoxylin  and  eosin  but  stains  dark  red 
with  Wright  and  Craighead's  carbol  fuchsin- 
methylene  blue  stain  (decolorized  with  37% 
formaldehyde  solution),  whereas  Toxo- 
plasma stains  well  with  hematoxylin  and 
eosin  and  stains  blue  with  carbol  fuchsin- 
methylene  blue;  Eiiceplialitozoon  stains 
black  with  Weigert's  iron  hematoxylin, 
whereas  Toxoplasma  does  not;  and  Enceph- 
alitozooii  survives  rapid  freezing  and  stor- 
age at  -70°  C  or  storage  in  50%  buffered 
glycerol  at  4°  C,  while  Toxoplasma  does 
not  (Perrin,   1943a;  Frenkel,   1956). 

Several  species  of  Eiiceplialitozoon 
have  been  named,  and  the  name  has  also 
been  mistakenly  given  to  the  Negri  bodies 
of  rabies.    However,  in  view  of  the  trans- 
missibility  of  the  organism  from  one  host 
to  another,  only  a  single  species  deserves 
recognition.    Even  this  has  been  ques- 
tioned.   Robinson  (1954)  claimed  that  the 
structures  described  under  this  name  are 
actually  ceroid  pigment  or  hemofuscin. 
Unfortunately,  none  of  the  11  photomicro- 
graphs of  tissue  sections  in  his  paper 
shows  these  structures,  so  that  there  is 
no  clear  evidence  of  what  he  was  actually 
dealing  with. 


B.  jellisoni  is  serologically  and  im- 
munologically distinct  from  Toxoplasma 
and  also  from  B.  besnoiti.     Goldman, 
Carver  and  Sulzer  (1957)  found  that  fluor- 
escein-labelled  Toxoplasma  antibody  did 
not  stain  5.  jellisoni,   and  Frenkel  (1955) 
found  that  sera  from  cows  naturally  in- 
fected with  B.  besnoiti  did  not  react  with 
B.  jellisoni  in  the  dye  test. 

Genus  ENCEPHAUTOZOON 
Levaditi,  Nicolau  and  Schoen,  1923 

This  genus  closely  resembles  Toxo- 
plasma and  may  indeed  eventually  turn  out 
to  be  a  synonym  of  it,  as  Biocca  (1949) 
believed.    It  is  too  poorly  known,  however, 


ENCEPHAUTOZOON  C UNIC ULI 
LEVADITI,  NICOLAU  AND 
SCHOEN,   1923 

Synonyms:     Encephalitozoon  negrii. 

Disease:     Encephalitozoonosis. 

Hosts:     Domestic  rabbit,  house 
mouse,  Norway  rat,  cottontail,  dog.    The 
golden  hamster  has  been  infected  experi- 
mentally.   A  few  human  infections  with 
Enceplialitozoon  have  been  reported,  but 
they  were  all  actually  Toxoplasma. 

Location:  Encephalitozoon  occurs  in- 
tracellularly  in  the  brain,  kidneys,  periton- 
eal exudate,  liver,  spleen  and  other  organs. 


342 


SARCOCYSTIS,   TOXOPLASMA  AND  RELATED  PROTOZOA 


Geographic  Distribution:     Worldwide, 

Prevalence:     Perrin  (1943) found 
Enceplialitozuon  in  the  brains  of  5  of  502 
Swiss  mice,  2  of  283  Wistar  strain  albino 
rats,  and  1  of  291  guinea  pigs  at  the  Na- 
tional Institutes  of  Health,  Bethesda,  Md. 
It  has  been  encountered  sporadically  by  a 
number  of  workers  in  laboratory  rabbits, 
mice  and  rats  (Frenkel,  1956;  Perrin, 
1943).    In  most  cases  it  has  been  found 
during  routine  histologic  examination  of 
animals  being  studied  for  some  other  pur- 
pose. 

Plowright  (1952)  described  3  cases  in 
a  litter  of  foxhounds  in  England,  and  Plow- 
right  and  Yeoman  (1952)  found  it  in  a  litter 
of  puppies  in  Tanganyika.    They  also  re- 
viewed the  literature  on  previous  reports 
of  what  may  have  been  the  same  organism 
in  dogs.    Jungherr  (1955)  found  it  in  a 
cottontail  rabbit. 

Morphology:     The  trophozoites  meas- 
ure 2.0  to  2.  5  by  0.  8  to  1.  2  fi  in  tissue 
sections  and  up  to  4.  0  by  2.  5  fx  (mean, 
2.  0  by  1 . 2  /J, )  in  smears  (Perrin,  1943a). 
They  are  straight  to  slightly  curved  rods 
with  both  ends  bluntly  rounded  but  one  end 
a  little  larger  than  the  other.    The  body 
is  sometimes  slightly  constricted  at  or 
near  its  midpoint.    Round  or  oval  forms 
occasionally  occur.    The  nucleus  is  com- 
pact, round,  oval  or  bandlike,  about  1/4 
to  1/3  the  size  of  the  parasite,  and  is  not 
central.     Pseudocysts  containing  up  to 
100  or  more  trophozoites  are  found  within 
the  nerve  cells,  macrophages  or  other 
tissue  cells.    Both  they  and  the  tropho- 
zoites are  rarely  extracellular. 

Life  Cycle:     The  mode  of  multiplica- 
tion is  unknown.    The  organism  can  be 
transmitted  from  the  mouse,  rabbit,  rat 
or  guinea  pig  to  other  laboratory  animals 
by  intracerebral,  intravenous,  intraper- 
itoneal or  other  parenteral  inoculation  of 
infected  brain,  liver,  spleen  or  peritoneal 
exudate  (Perrin,  1943a).    It  has  been 
found  in  the  urine.     Congenital  infection 
undoubtedly  occurs  in  mice  (Perrin,  1943) 
and  probably  in  rabbits  (Smith  and  Flor- 
ence, 1925)  and  dogs  (Plowright,  1952). 


Pathogenesis:     E.  cuniculi  causes 
encephalitis  and  systemic  disease  asso- 
ciated with  nephritis  in  rabbits  and  pup- 
pies, and  an  inapparent  infection  in  labor- 
atory rodents.    The  great  majority  of  cases 
in  rabbits  are  also  inapparent,  being  dis- 
covered on  histologic  examination  carried 
out  for  some  other  reason.    Its  true  im- 
portance in  dogs  is  unknown,  since  it  has 
been  seen  very  rarely  in  them. 

Encephalitozoonosis  is  usually  a  mild, 
chronic,  infection  in  rabbits,  altho  paral- 
ysis and  death  may  occur.    The  principal 
lesions  in  the  brain  are  tiny,  focal  granu- 
lomata  made  up  of  epithelioid  cells  sur- 
rounding a  tiny  area  of  necrosis.    In  fatal 
cases  there  may  be  large  necrotic  areas 
and  perivascular  lymphocytic  cuffing.    The 
parasites  may  occur  in  or  around  the  ne- 
crotic areas.    Similar  granulomatous 
lesions  may  be  present  in  the  kidneys  and 
other  organs.    In  the  kidneys  they  occur 
principally  in  the  epithelial  cells  of  the 
collecting  tubules,  which  they  distend  and 
finally  rupture,  passing  out  in  the  urine 
(Smith  and  Florence,   1925). 

In  mice  and  rats  the  principal  lesions 
are  meningoencephalitis  and,  in  experi- 
mentally infected  animals,  abdominal  en- 
largement with  ascites.    Nodular,  granu- 
lomatous lesions,  sometimes  with  central 
necrosis,  occur  thruout  the  brain.     There 
is  slight  to  moderate  focal  perivascular 
infiltration  by  lymphocytes  and  a  few  large 
mononuclear  and  plasma  cells  in  the  men- 
inges and  also  in  the  brain.    The  parasites 
may  be  either  within  or  at  the  margins  of 
the  lesions  or  even  in  normal  brain  tissue 
at  a  distance  from  them.    There  may  be 
moderate  to  marked  interstitial  lymphocytic 
infiltration  in  the  kidneys,  primarily  in  the 
cortex.    The  tubular  epithelium  may  be  de- 
generate or  proliferative  in  the  areas  of 
infiltration,  and  parasites  may  occur  either 
in  the  epithelial  cells  or  within  the  collect- 
ing tubules.    Similar  areas  of  infiltration 
may  be  seen  in  other  organs  (Perrin,  1943). 

According  to  Frenkel  (1955),  treatment 
with  cortisone  exacerbates  the  disease  in 
mice.    The  parasites  proliferate  exten- 
sively in  most  organs,  and  the  mice  may  die. 


SARCOCYSTIS,    TOXOPLASMA  AND  RELATED  PROTOZOA 


343 


In  the  litter  of  six  puppies  described 
by  Plowright  (1952),  the  principal  signs 
were  posterior  weakness  and  incoordina- 
tion, apathy,   rapid  tiring,   some  loss  of 
condition  and  signs  of  ocular  involvement. 
All  died  between  6  weeks  and  1 5  months  of 
age.    Two  puppies  were  affected  at  8  to  10 
weeks  of  age  in  the  litter  described  by 
Plowright  and  Yeoman  (1952).     Both  had 
symptoms  resembling  those  of  rabies. 
They  became  vicious  and  bit  or  attempted 
to  bite  people.    One  had  fits  of  rushing 
wildly  around,  and  died  on  the  5th  day 
with  uncontrolled  spasms  of  the  limbs  and 
jaws.    The  other  had  an  epileptiform  fit, 
became  dull  and  off  feed,  but  remained 
quiet  under  mild  sedation.    Its  retina  was 
dull  and  greyish,  with  darker  "smoke- 
wisp"  foci,  and  the  optic  disc  was  dull  and 
ill-defined.    It  died  11  days  after  the  onset. 

The  principal  lesions  in  both  litters 
were  those  of  encephalitis  or  meningo- 
encephalomyelitis  and  interstitial  or  tub- 
ular nephritis  similar  to  those  described 
above  in  rabbits  and  rodents.    Encepha- 
litozoon  was  readily  seen  in  the  lesions. 

Immunity:     According  to  Frenkel 
(1955),  there  is  no  cross  immunity  be- 
tween Encephalitozoon  and  Toxoplasma. 

Diagnosis:     Encephalitozoonosis  is 
generally  diagnosed  by  finding  the  causa- 
tive organisms  in  tissue  sections.    They 
can  be  differentiated  from  Toxoplasma  on 
the  basis  of  size,  shape  and  differential 
staining  reactions,  as  described  above. 

Cultivation:     EncepJialitozoon  has  not 
been  cultivated. 

Treatment:     None  known. 

Prevention  and  Control:     In  the  ab- 
sence of  information  on  its  mode  of  trans- 
mission, little  can  be  said  about  preven- 
tion and  control.    Sanitation  combined  with 
elimination  of  affected  litters,  and  possi- 
bly also  of  their  mothers,  may  be  helpful. 


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The  ciliates  of  domestic  animals  all 
belong  to  the  class  Ciliasida.     The  nuclei 
of  this  group  are  unique  in  the  animal  king- 
dom.    Every  individual  (except  in  a  few 
amicronucleate  strains)  has  a  micronucleus 
which  contains  a  normal  set  of  chromo- 
somes, and  a  macronucleus  which  contains 
an  indeterminately  large  number  of  sets 
and  is  actually  /;-ploid  rather  than  poly- 
ploid.    The  micronucleus  is  active  in  re- 
production, while  the  macronucleus  has  to 
do  with  the  vegetative  functions  of  the  or- 
ganism. 

The  ciliates  have  either  simple  cilia 
or  compound  ciliary  cirri  or  membran- 
elles  in  at  least  one  stage  of  their  life 
cycle.     They  also  have  an  infraciliature  in 
the  cortex  beneath  the  pellicle,   composed 
of  the  ciliary  basal  granules  (kinetosomes) 
and  associated  fibrils  (kinetodesmata). 
The  infraciliature  can  be  stained  with  sil- 
ver, forming  the  so-called  silver-line 
system.    Reproduction  is  by  transverse 
binary  fission,  in  contrast  to  the  longitu- 
dinal fission  seen  in  the  flagellates.     True 
sexual  reproduction,  in  which  gametes  fuse 
to  form  a  zygote,  is  absent,  but  conjuga- 
tion,  in  which  there  is  an  exchange  of  mi- 
cronuclear  material  between  two  individ- 
uals, may  be  present. 


Chapter  13 


THE  CILIATES 


The  great  majority  of  ciliates  are 
free-living,  but  a  number  are  parasitic. 
Their  classification  has  recently  undergone 
considerable  overhauling,  and  they  are 
now  arranged  in  26  orders  and  suborders 
belonging  to  2  subclasses  (Corliss,  1956, 
1957,   1959).     This  classification  is  based 
on  recent  work  by  the  French  school,  and 
particularly  by  Faure-Fremiet,  on  the 
silver-line  system,  and  is  more  natural 
than  the  earlier  one.    Terms  used  in  des- 
cribing the  ciliates  are  defined  by  Corliss 
(1959).    Corliss  (1961)  has  reviewed  the 
whole  group. 

The  characteristics  of  the  taxa  found 
in  domestic  animals  have  been  given  on 
pp.  34-38.    In  the  subclass  Holotrichasina, 
the  body  ciliature  is  typically  uniform  and 
simple.    Buccal  ciliature  (an  adoral  zone 


-  347 


348 


THE  CILIATES 


of  membranelles)  is  usually  absent  or 
inconspicuous.    This  subclass  contains  4 
orders  of  veterinary  interest.    In  the  order 
Gymnostomorida  ("naked  mouth"),  the  cyto- 
stome  opens  directly  at  the  surface  or  else 
into  a  slight  depression  which  has  no  oral 
ciliature.    This  order  includes  2  families 
of  which  members  occur  in  the  large  in- 
testine of  equids  or  ruminants  or  in  the 
rumen  and  reticulum  of  ruminants. 

In  the  order  Suctoriorida  only  the 
young  have  cilia,  while  the  adults  have 
tentacles.    All  members  of  this  order  are 
free-living  except  for  one  genus  which 
occurs  in  the  large  intestine  of  equids. 

In  the  order  Trichostomorida  ("hair 
mouth"),  the  cytostome  is  usually  at  the 
base  of  a  well-defined  oral  pit  or  vesti- 
bulum,  which  in  turn  may  sometimes  be 
preceded  by  an  oral  groove.    The  vesti- 
bular wall  bears  1  or  more  dense  fields 
of  adoral  (vestibular)  cilia.    The  great 
majority  of  trichostomes  are  free-living, 
but  there  are  5  families  which  contain 
parasites  of  domestic  animals. 

In  the  order  Hymenostomorida  ("mem- 
brane mouth"),  the  adoral  cilia  are  fused 
in  membranes,  the  number,  size  and  ar- 
rangement of  which  vary  in  different  gen- 
era.   The  free-living  genera  Paramecium 
and  Tetrahymena  belong  to  this  order;  the 
latter  is  occasionally  parasitic.    The  most 
important  parasite  in  the  order  is  Ichthyo- 
phthirius,  which  is  often  a  serious  patho- 
gen of  aquarium  fish,  causing  a  disease 
known  as  "ick. " 


iorida  contains  a  group  of  remarkably 
bizarre  genera  which  occur  in  ruminants 
and  equids.    In  this  order,  ciliation  may 
be  limited  to  the  adoral  zone  or  there  may 
be  1  or  more  additional  bands  or  groups  of 
membranelles.    The  internal  anatomy  is 
complex,  and  unique  "skeletal  plates"  may 
be  present.    There  are  2  families.    The 
Ophryoscolecidae  have  not  more  than  1 
"dorsal"  or  "metoral"  band  of  membran- 
elles in  addition  to  the  adoral  zone  and 
occur  in  the  rumen  and  reticulum  of  rum- 
inants.   The  Cycloposthiidae  have  2  or 
more  bands  of  membranelles  in  addition  to 
the  adoral  zone,  and  occur  in  the  large  in- 
testine of  equids  and  also  of  anthropoid 
apes. 


A.   CILIATES   OF    RUMINANTS 

A  tremendous  number  and  bewildering 
variety  of  ciliates  swarm  in  the  rumen  and 
reticulum  of  ruminants,  and  a  few  species 
occur  in  the  large  intestine.    Many  are 
holotrichs,  but  the  most  bizarre  ones  are 
ophryoscolecids.    No  attempt  will  be  made 
here  to  differentiate  all  the  species,  but 
the  genera  will  be  described  and  the  prin- 
cipal species  mentioned,  and  the  relations 
of  the  different  groups  to  their  hosts  will 
be  discussed.     Further  taxonomic  and 
morphologic  information  is  given  by  Becker 
and  Talbot  (1927),  Dogiel  (1927),  Kofoid 
and  Mac Lennan  (1930,   1932),  Chavarria 
(1933),  Polyansky  and  Strelkov  (1938)  and 
Lubinsky  (1957). 


In  the  subclass  Spirotrichasina,  the 
buccal  ciliature,  and  especially  the  multi- 
partite adoral  zone  of  membranelles,  is 
conspicuously  developed.    The  body  cili- 
ature is  typically  sparse,  and  all  the  sim- 
ple cilia  may  even  be  replaced  by  cirri;  in 
one  order,  the  Heterotrichorida,  however, 
the  body  ciliation  is  usually  complete. 

This  subclass  contains  2  orders  of 
veterinary  interest.    In  the  order  Hetero- 
trichorida the  somatic  ciliation  is  usually 
complete.     One  genus  in  this  order,   Nycto- 
therus,  occurs  in  amphibia  and  various  in- 
vertebrates, but  has  also  been  found  in  the 
feces  of  ruminants.    The  order  Entodin- 


FAMILY   BUETSCHLIIDAE 

In  this  holotrichasin  gymnostomorid 
family,  the  cytostome  is  usually  at  the 
anterior  end,  there  are  ordinarily  a  poster- 
ior cytopyge,  one  or  more  contractile  vac- 
uoles and  an  anterior  concretion  vacuole 
which  some  authors  think  is  a  statocyst. 
Cilia  are  uniformly  distributed  over  the 
body  or  are  restricted  to  certain  areas. 
This  family  includes  a  number  of  genera 
and  species,  the  great  majority  of  which 
occur  in  the  cecum  and  colon  of  equids. 
One  genus,  however,  is  found  in  the  rumen 
of  cattle  and  camels. 


THE  CILIATES 


349 


Fig.  38.      Ciliates  of  ruminants.     A.    Buetschlia  parva.    X  1090.     B.   Isolricha  prostoma. 
X  320.     C.  Isolricha  intestinalis.     X  640.     D.  Dasytricha  riDiiinantium. 
X  420.     E.    Ophryoscolex  caiidatus.    X  425.     F.    Entodinimu  bursa.    X  640. 
G.    Entodiniuni  minimum .    X  640.     H.    Entodinimu  caudatuni.    X  640.    I.    En- 
todiniuni  bicarinatum .    X  640.    J.    Entodinimu  furca.    X  640.     K.    Epidinium 
ecaudatum.    X  425.     (From  Becker  and  Talbott,   1927,  in  Iowa  State  College 
Journal  of  Science,   published  by  Iowa  State  Univ.   Press). 


Genus  BUETSCHLIA  Schuberg,  1 888 

The  body  is  ovoid,  with  a  truncate 
anterior  end  and  a  rounded  posterior  end. 
There  is  a  circular  cytostome  at  the  an- 
terior end,  but  no  cytopyge.    The  body  is 
uniformly  ciliated  except  for  long  cilia 


surrounding  the  cytostome. 
at  the  anterior  end  is  thick, 
nucleus  is  spherical. 


The  ectoplasm 
The  macro- 


Biietschlia  parva  Schahevg,  1888  is 
30  to  50^1  long  and  20  to  30 ^  wide.    B. 
neglecta  Schuberg,  1888  resembles 


350 


THE  CILIA TES 


B.  parva,  but  its  posterior  end  is  some- 
what pointed  and  has  4  indentations,  so 
that  it  looks  like. a  cross  in  cross  section; 
it  measures  40  to  60  by  20  to  SOji .    B. 
lanceolata  Fiorentini,   1890  is  lanceolate, 
with  a  collar-like  stricture  in  the  anterior 
fifth  of  the  body;  it  measures  48  by  20 p.. 
These  species  all  occur  in  cattle  but  are 
apparently  not  common,  at  least  in  the 
United  States.     Becker  and  Talbott  (1927) 
did  not  find  them  in  26  cows  they  examined 
in  Iowa. 

B.  nana  Dogiel  and  B.  oninivora  Dogiel 
are  found  in  the  rumen  of  the  dromedary. 


FAMILY   PYCNOTRICHIDAE 

In  this  holotrichasin  gymnostomorid 
family,  a  long  groove  leads  to  the  cjrto- 
stome,  which  may  lie  near  the  middle  or 
at  the  posterior  end  of  the  body.    The  body 
is  completely  ciliated.    This  family  con- 
tains 2  genera  in  ruminants  whose  names 
may  actually  be  synonymous. 


Genus  BUXTONELLA  Jameson,  1926 

The  body  is  ovoid  and  uniformly 
ciliated,  with  a  prominent  curved  groove 
bordered  by  2  ridges  running  from  end  to 
end.     The  cytostome  is  near  the  anterior 
end. 

Buxtonella  sulcata  Jameson,  1926  is 
common  in  the  cecum  of  the  ox,  zebu  and 
water  buffalo.    The  trophozoites  measure 
60  to  138  by  46  to  100  ^  with  a  mean  of 
100  by'72fi  ,  and  have  an  oval  or  bean- 
shaped  macronucleus  measuring  18  to  36 
by  10  to  18 /J,  with  a  mean  of  28.  5  by  14  jj, 
(Lubinsky,   1957). 

According  to  Lubinsky  (1957),  the 
reports  of  "Balantidium"  in  cattle  were 
actually  of  B.  sulcata. 

Infiindibulor ium  cameli  Bozhenko, 
1925,  which  was  described  from  the  diar- 
rheic  stools  of  a  camel,  may  be  the  same 
species  as  B.  sulcata.    If  so,  the  name 
will  have  to  be  changed,  since  Infundibu- 
lorium  has  priority  (Lubinsky,   1957a). 


FAMILY    ISOTRICHIDAE 

In  this  holotrichasin  trichostomorid 
family,  the  mouth  is  terminal  or  subtermi- 
nal,   and  the  pharynx  is  ciliated,  with  longi- 
tudinal striations  in  its  wall.    Somatic 
ciliation  is  complete  and  practically  uni- 
form.    This  family  contains  the  2  most 
important  holotrich  genera  of  ruminants. 


Genus  ISOTRICHA  Stein,  1859 

The  body  is  oval  and  flattened,  with 
dense,  longitudinal  rows  of  cilia.    The 
cytostome  is  at  or  near  the  anterior  end. 
Several  contractile  vacuoles  are  present. 
The  macronucleus  is  kidney-shaped;  it 
and  the  micronucleus  are  connected  to  each 
other  and  suspended  by  fibrils  which  con- 
stitute the  karyophore.     Locomotion  is 
toward  the  rear. 

Isolricha  prostoma  Stein,  1859  is  the 
most  widely  distributed  of  all  the  ruminant 
ciliates.    It  occurs  in  the  rumen  and  reti- 
culum of  cattle,  sheep  and  goats.    Becker 
and  Talbott  (1927)  found  it  in  58%  of  26 
cattle  in  Iowa.    It  measures  80  to  195  by 
53  to  85  fi,  and  its  cytostome  is  subtermi- 
nal. 

/.  intestinalis  Stein,   1859  also  occurs 
in  the  rumen  and  reticulum  of  cattle,  sheep 
and  goats.    Becker  and  Talbott  (1927)  found 
it  in  19%  of  26  cattle  in  Iowa.    It  measures 
97  to  130  by  68  to  88/i  ,  and  differs  from 
I.  prostoma  in  that  its  cytostome  and  nu- 
cleus are  more  posterior. 


Genus  DASYFRfCHA  Schuberg,  1888 

The  body  is  oval  and  flattened.    The 
cilia  are  in  spiral,  longitudinal  rows. 
There  is  no  karyophore. 

Dasytriclm  ruminantium  Schuberg, 
1888  occurs  in  the  rumen  and  reticulum  of 
cattle,  sheep  and  goats.    Becker  and  Tal- 
bott (1927)  found  it  in  38%  of  26  cattle  in 
Iowa.    It  measures  50  to  75  by  30  to  40  ja. 


THE  CILIATES 


351 


FAMILY   OPHRYOSCOLECIDAE 

In  this  spirotrichasin  entodiniorid 
family,  there  is  not  more  than  1  "dorsal" 
("metoral")  band  of  membranelles  in  addi- 
tion to  the  adoral  zone.     This  family  con- 
tains 18  or  more  genera  which  occur  in 
the  rumen  of  ruminants;  13  of  these  occur 
in  cattle  and  sheep.    The  most  important 
genera  are  Eiifodinium ,  Diplodiniuni, 
Epidiniiu)!  and  Ophryoscolex.    The  taxon- 
omy of  this  group  is  complicated.    Varia- 
tions in  structure,  even  within  a  clone, 
are  common  in  EntodiniiiDi  and  Diplodin- 
ium.     They  make  species  identification 
difficult  and  have  served  to  multiply  unduly 
the  number  of  different  species  which  have 
been  named  (Polyansky  and  Strelkov,  1938; 
Hungate,   1943;  Lubinsky,   1957,   1958). 

The  body  in  this  family  is  often  flat- 
tened, and  another  source  of  confusion 
results  from  the  fact  that  different  authors 
have  used  the  same  name  for  different 
sides  of  the  body.    Depending  on  whose 
terminology  was  used,  every  one  of  the 
four  sides  has  been  called  the  left,  right, 
dorsal  or  ventral  side.     Lubinsky  (1958) 
introduced  a  new  system  which  has  the 
advantages  of  eliminating  the  concept  of 
dorsality  and  ventrality,  which  actually 
has  no  application  in  this  group,  and  of 
making  it  possible  to  use  the  same  terms 
both  for  Entodinium  and  for  the  higher 
genera>in  the  family.    In  this  system, 
which  is  used  below,  the  observer  orients 
the  protozoon  with  its  anterior  (oral)  end 
pointing  away  from  him  (toward  12  o'clock) 
and  with  the  micronucleus  to  the  left  of  the 
macronucleus  (toward  9  o'clock).    The 
sides  are  then  designated  left  (the  obser- 
ver's left,  i.e.,  the  micronuclear  side), 
right,  upper  and  lower. 

If  this  terminology  is  accepted,  then 
the  term,  dorsal  zone  of  membranelles 
(DZM),  which  is  used  in  describing  ophry- 
oscolecids,  is  no  longer  appropriate. 
Lubinsky  used  "metoral  membranelle 
zone-'  instead. 


Genus  OPHRYOSCOLEX  Stein,  1858 

The  body  is  ovoid,  with  adoral  and 
metoral  zones  of  membranelles.    The 


metoral  zone  is  some  distance  from  the 
anterior  end  and  encircles  3/4  of  the  body 
circumference  at  its  middle,  being  broken 
on  the  upper  right  side.    There  are  3 
skeletal  plates  extending  the  length  of  the 
body  on  the  upper  right  side,   and  9  to  15 
contractile  vacuoles  arranged  in  an  anter- 
ior and  a  posterior  circle.    The  macro- 
nucleus  is  simple  and  elongate.    This 
genus  occurs  in  the  rumen  and  reticulum 
of  cattle,  sheep,  goats  and  wild  sheep. 
It  is  not  common,  and  is  seldom  present 
in  large  numbers  when  it  does  occur,  but 
is  interesting  because  of  its  size  and  ap- 
pearance. 

Ophryoscolex  inermis  Stein,  1858 
occurs  principally  in  the  goat.    It  meas- 
ures 170  to  190  by  65  to  100  (i .     Becker 
and  Talbott  (1927)  found  it  in  1  of  26  cows 
in  Iowa.    It  differs  from  the  other  species 
of  Ophryoscolex  in  having  a  rounded  pos- 
terior end,  without  spines. 

0.  purkinjei  Stein,   1858  occurs  in 
cattle.    It  measures  200  by  80 |i  and  has 
2  or  3  terraces  of  thorn-like  appendages 
or  spines  encircling  the  posterior  end  of 
the  body  except  for  a  short  gap  on  the 
right  side;  in  addition,  there  is  a  bifid 
spine  at  the  posterior  end.    Becker  and 
Talbott  (1927)  did  not  find  this  species  in 
Iowa  cattle. 

O.  caudatus  Eberlein,  1895  occurs  in 
sheep  and  cattle.    It  resembles  O.  purkin- 
jei   but  its  terminal  spine  is  long  and  not 
bifid.    Becker  and  Talbott  (1927)  found  it 
in  1  of  26  cattle  in  Iowa. 


Genus  ENTODINIUM  Stein,  1858 

The  body  is  truncate  anteriorly,  with 
the  adoral  zone  of  membranelles  at  that 
end.     There  is  no  metoral  zone  of  mem- 
branelles, and  skeletal  plates  are  likewise 
absent.    The  contractile  vacuole  is  anter- 
ior.    The  macronucleus  is  cylindrical  or 
sausage -shaped  and  dorsal.    The  micro- 
nucleus  is  anterior  to  the  middle  on  the 
upper  left  side  of  the  macronucleus.    This 
is  one  of  the  commonest  and  most  impor- 
tant genera  in  the  rumen  and  reticulum  of 
cattle,  sheep,  goats  and  other  ruminants. 


352 


THE  CILIATES 


Many  species  oi  Entodinium  have  been 
named,  but  knowledge  of  the  true  number 
and  of  their  correct  names  awaits  some 
future  exhaustive  taxonomic  study.    In  the 
earlier  papers,  great  reliance  was  placed 
on  caudal  spination  to  differentiate  spe- 
cies, but  later  it  was  found  that  this  char- 
acter varies  within  a  species.    Thus,  E. 
caudalum  was  given  its  name  because  it 
has  a  long  posterior  spine  on  the  right 
side  in  addition  to  2  short,  pointed  lobes 
on  the  left.    A  second  species,  E.  loboso- 
spinosum,   received  its  name  because  it 
has  only  a  single  lobe  on  the  left  (the  upper 
one)  in  addition  to  the  spine  on  the  right. 
A  third  species,  E.  diibardi,  has  no  pos- 
terior spines  or  lobes  at  all.    However,  it 
was  later  found  that  the  caudal  spination 
varies  all  the  way  from  the  caudatiuu  type 
to  the  dubardi  type  in  several  species,  and 
that  other  characters  are  more  constant 
and  more  valuable  in  differentiating  species. 

Six  types  or  classes  of  caudal  spina- 
tion have  been  set  off  along  this  series 
for  E.  caudatmn.     Three  of  them  have  re- 
ceived special  names,  and  workers  now 
speak  of  E.  caiidatum  forma  caudatuni , 
E.  caudatmn  forma  lobospinosum,  and 
E.  caudatum  forma  dubardi,  the  last  being 
a  form  without  a  tail  at  all!     These  same 
forma  names  are  also  used  for  E.  si7?m- 
lans,  and  some  of  them  for  E.  rectangu- 
latum  and  E.  lobospinosum  (cf.  Poljansky 
and  Strelkow,  1938;  Lubinsky,  1957). 

Entodinium  bursa  Stein,  1858  has  a 
flattened  body  which  measures  about  80  by 
&Q\x.     (Because  of  the  variation  in  caudal 
spination,  measurements  of  Entodinium 
are  made  nowadays  from  the  anterior  end 
to  the  cytopyge,  but  early  workers  usually 
gave  measurements  to  the  end  of  the  caudal 
spine. )    The  sausage-shaped  macronucleus 
is  4/5  of  the  body  length,  and  the  micro- 
nucleus  is  pressed  closely  to  it.    The  body 
surface  has  conspicuous  longitudinal  stri- 
ations.    The  contractile  vacuole  is  an- 
terior. 

E.  minimum  Schuberg,   1888  has  a 
flattened  body  which  measures  about  40 
by  22  fi.     The  right  margin  of  the  body  is 
strongly  convex  and  the  left  margin  almost 


straight.    The  body  surface  has  faint 
longitudinal  striations.    The  macronucleus 
is  about  1/3  of  the  body  length.    The  con- 
tractile vacuole  is  anterior. 

E.  caudatum  Stein,  1858  has  a  flat- 
tened body  about  30  to  over  80  p.  long.    The 
macronucleus  is  about  half  of  the  body 
length;  it  is  broader  anteriorly  than  pos- 
teriorly.   The  contractile  vacuole  is  near 
the  anterior  end  of  the  macronucleus. 
The  upper  side  of  the  body  is  hollowed  out 
to  form  a  groove  which  broadens  poster- 
iorly.   As  mentioned  above,  there  is  great 
variation  in  the  caudal  spination. 

E.  bicarinatum  Cunha,  1914  may  be 
a  synonym  of  E.  caudatum.     It  measures 
about  61  by  35^,  and  the  upper  groove  is 
not  as  deep  as  in  E.  caudatum. 

E.  furca  Cunha,  1914,  too,  may  be  a 
synonym  oiE.  caudatum.      It  has  2  unequal 
caudal  projections,  1  on  the  left  and  the 
other  on  the  right,  and  measures  about  52 
by  27,1. 

E.  dentatum  Stein,  1859  measures  60 
to  90  by  30  to  50  p,  and  has  6  incurved, 
tooth-like  posterior  projections. 

E.  rectangulatum  Kofoid  and  Mac- 
Lennan,  1930  measures  23  to  47  by  23  to 
39 /i.    Its  body  is  nearly  rectangular  as 
seen  from  above,  except  for  the  caudal 
spines.    The  macronucleus  is  about  half 
the  body  length  and  is  broader  anteriorly 
than  posteriorly.    The  contractile  vacuole 
is  about  the  middle  of  the  body  at  the  level 
of  the  esophagus,  i.  e. ,  more  to  the  left 
than  that  of  E.  caudatum.     The  upper 
groove  is  more  marked  than  that  of  E. 
caudatum ,  and  its  anterior  end  separates 
the  contractile  vacuole  from  the  macro- 
nucleus. 

E.   lobosospinosum  Dogiel,  1927  meas- 
ures 18  to  33  by  13  to  25^ .    Its  body  is 
rectangular  as  seen  from  above.    The 
macronucleus  is  about  half  the  body  length. 
The  contractile  vacuole  is  on  the  mid-line 
of  the  upper  side  of  the  body  on  the  level 
of  the  micronucleus  and  to  the  left  of  the 
broad  upper  groove. 


THE  CILIATES 


353 


E.  simulans   Lubinsky,   1957  measures 
27  to  44  by  21  to  34  (i.    Its  body  is  ovoid 
as  seen  from  above.    The  macronucleus  is 
about  half  the  body  length.    The  contrac- 
tile vacuole  is  on  the  mid-line  of  the  upper 
side  of  the  body  at  the  level  of  the  micro - 
nucleus  and  to  the  left  of  the  upper  groove. 
This  groove  is  narrow  and  long,  with  a 
slit-shaped  anterior  half. 

E.  longinucleatum  Dogiel,  1925  meas- 
ures 39  to  64  by  27  to  46 /j,  and  has  an 
ellipsoidal,  flattened  body.    The  macro- 
nucleus  usually  extends  the  whole  length 
of  the  body  from  the  anterior  end  to  the 
cytopyge.    The  contractile  vacuole  is  close 
to  the  upper  side  of  the  macronucleus, 
slightly  anterior  to  the  micronucleus. 

E.  rostratum  Fiorentini,  1889  meas- 
ures 27  to  51  by  13  to  23  ju  and  has  a 
rather  long,  slim,  flattened  body  with  a 
strongly  convex  right  side  and  a  concave 
left  side.    The  macronucleus  is  narrow, 
bandlike,  and  about  half  the  length  of  the 
body.    The  contractile  vacuole  is  directly 
anterior  to  the  macronucleus. 

E.  laterale  Kofoid  and  MacLennan, 
1930  measures  19  to  28  by  18  to  21  [i  and 
has  a  short,  fairly  broad,  truncated  ellip- 
soidal, flattened  body.    The  macronucleus 
is  broad  and  wedge-shaped,  less  than  half 
the  length  of  the  body,  and  lies  in  the  an- 
terior half  of  the  body.    The  contractile 
vacuole  is  in  the  middle  of  the  upper  side. 

E.  nanellum  Dogiel,  1922  measures 

20  to  32  by  10  to  18  p,  and  has  an  ovoid, 
flattened  body.    The  macronucleus  is 
thin,  wedge-shaped,  and  longer  than  half 
the  body  length.    The  contractile  vacuole 
is  above  the  anterior  end  of  the  macro- 
nucleus. 

E.  bimastus  Dogiel,  1927  measures 
30  to  46  by  28  to  40  (i  and  has  a  subspher- 
ical,  flattened  body.    The  macronucleus 
is  flattened,  wedge-shaped,  and  about 
2/3  of  the  length  of  the  body.    The  contrac- 
tile vacuole  is  above  the  anterior  end  of 
the  macronucleus. 

E.  exiguum  Dogiel,  1925  measures 

21  to  29  by  14  to  18  ju  and  has  an  elongate, 
oval  body.    The  macronucleus  is  rela- 


tively short  and  thick,    being  shorter  than 
half  the  body  length,  and  lies  in  the  mid- 
dle of  the  body. 

E.  dubardi  Buisson,   1923  (syn. ,  E. 
simplex  Dogiel,   1925  pro  parte;  the  true 
E.  simplex  occurs  in  the  reindeer)  meas- 
ures 30  to  50  by  20  to  29 /i  and  has  an  oval 
or  elongate  oval,  flattened  body.    The 
macronucleus  is  more  or  less  band-shaped, 
with  a  somewhat  broader  anterior  end.    It 
is  about  half  as  long  as  the  body  and  lies 
anteriorly  in  it.    The  contractile  vacuole 
is  below  the  anterior  end  of  the  macro- 
nucleus. 

E.  vorax  Dogiel,  1925  measures  60 
to  121  by  40  to  83  ji  and  has  an  oval,  plump, 
thick  body.    The  anterior  end  is  often 
smaller  than  the  posterior.    The  macro- 
nucleus  is  sausage-shaped,  about  half  as 
long  as  the  body,  and  lies  in  the  anterior 
part  of  the  body.    The  contractile  vacuole 
is  to  the  right  of  the  anterior  end  of  the 
macronucleus. 

Quite  a  few  other  species  of  Entodin- 
ium  have  been  described  from  various 
ruminants.    Among  them  are  the  following, 
which  Kofoid  and  MacLennan  (1930)  des- 
cribed from  the  zebu:    E.  ellipsoideum, 
E.  acutonuc  lea  turn,  E.  pisciculum,  E. 
biconcavum,  E.  bifidum  (Dogiel)    E. 
acutum,  E.  aculeatum,  E.  brevispinum, 
E.  laterospinmn ,  E.  ovoideum,  E.  rhom- 
boideum,  E.  gibberosum ,  E.  tricostatum, 
and  E.  indicum. 


Genus  EPIDINIUM  Crawley,  1924 

The  body  is  elongate  and  twisted 
around  its  main  axis.    The  adoral  zone  of 
membranelles  is  at  the  anterior  end,  and 
the  metoral  zone  elsewhere.    There  are 
3  skeletal  plates  with  secondary  plates. 
The  macronucleus  is  simple  and  club- 
shaped.    There  are  2  contractile  vacuoles. 
This  genus  occurs  in  the  rumen  and  reticu- 
lum of  cattle,  sheep,  goats,  camels,  rein- 
deer, elk,  and  other  ruminants. 

Epidinium  ecaudatum   (Fiorentini, 
1889)  (syn. ,  Diplodinium  ecaudatum) 
measures  82  to  173  by  36  to  70 /j,  and  has 
an  elongate  body  with  a  convex  left  side  and 


^S-1 


THE  CILLATES 


a  flat  or  slightly  concave  right  side.    This 
species  has  9  formae  which  differ  prin- 
cipally in  their  caudal  spination:    E.  ecaiid- 
atiuii  forma  ecaiidattiiu  has  no  caudal 
spines,  forma  caiidalioii  has  a  single  long 
spine  and  the  posterior  end  of  its  body  is 
narrow,    liama/io)/  has  a  single  long  spine 
and  the  posterior  end  of  its  body  is  broad, 
bulhiferiim  has  a  bulb-shaped  appendage 
instead  of  a  spine,  bicaiidaln))i  has  2 
spines,  IricaudalKiii  has  3,  quadricauda- 
tum  has  4,  catteueoi  has  5  short  ones,  and 
fasciculus  has  5  very  long  ones  with 
greatly  swollen  bases.    All  9  formae  occur 
in  the  rumen  of  cattle,  the  most  common 
being  ecaudatu)ii  and  caudalu))/.     Ecauda- 
tum,  lianiatum  and  cattaiieoi  are  found  in 
sheep,  and  the  last  in  goats  as  well. 
EcaudaluDi  and  caudatuni  also  occur  in  the 
reindeer,   caudatu>ii  and  luiDtaluni  in  cam- 
els and  caudatum  in  the  elk. 


Genus  EODINIUM 
Kofoid    and    Maclennan,    1932 

The  metoral  zone  of  membranelles  is 
at  the  same  level  as  the  adoral  zone. 
Skeletal  plates  are  absent.     The  macro- 
nucleus  is  a  straight,  rod-like  body  near 
the  left  edge.    Two  contractile  vacuoles 
are  present.     This  genus  occurs  in  the 
rumen  and  reticulum  of  cattle  and  sheep. 

E.  posterovesiculatu))i  (Dogiel,  1927) 
Kofoid  and  MacLennan,   1932  measures 
47  to  60  by  23  to  30  pt  and  has  a  relatively 
long,  flattened  body  with  rounded  ends. 
The  macronucleus  is  very  long,  straight, 
and  has  2  deep  depressions  on  its  left 
side.     The  micronucleus  lies  in  the  pos- 
terior one,  and  a  contractile  vacuole  in 
the  anterior  one.    The  second  contractile 
vacuole  is  posterior  to  the  macronucleus. 
This  species  occurs  in  cattle. 

E.  bilobosum  (Dogiel,  1927)  Kofoid 
and  MacLennan,  1932  measures  46  to  60 
by  30  to  44)ji  and  has  a  relatively  short, 
flattened  body  with  2  caudal  spines,  1 
dorsal  and  the  other  ventral.    The  nuclei 
and  vacuoles  are  similar  to  those  of  E. 
posterovesiculalum .     This  species  occurs 
in  cattle  and  sheep. 


Eodiniuiu  lobaluiii  Kofoid  and  Mac- 
Lennan,  1932  measures  44  to  60  by  29  to 
37  (i    and  has  a  narrow  body.     The  macro- 
nucleus  is  narrow  and  rod-like,  and  is 
almost  as  long  as  the  body.    It  has  3  large 
depressions  in  its  left  side;  the  micronu- 
cleus lies  in  the  middle  one,   and  the  con- 
tractile vacuoles  in  the  end  ones.     This 
species  occurs  in  the  zebu. 


Genus  DIPLODINIUM  Schuberg,  1888 

The  metoral  zone  of  membranelles  is 
on  the  same  level  as  the  adoral  zone. 
Skeletal  plates  are  absent.     The  macro- 
nucleus  is  beneath  the  upper  surface  of  the 
body;  its  anterior  third  is  bent  to  the  right 
at  an  angle  of  30  to  90".     Two  contractile 
vacuoles  are  present.    This  genus  occurs 
in  the  rumen  and  reticulum  of  cattle,  goats, 
sheep,   camels,   reindeer  and  various  wild 
ruminants. 

In  this  genus,  as  in  Entodiniuni, 
there  is  also  considerable  variation  in  the 
caudal  spination. 

DiplodiniuDi  dentatuiii  (Stein,   1858) 
Schuberg,   1888  measures  55  to  82  by  44 
to  62  ji .    Its  body  has  a  broad,  truncate 
posterior  end  with  6  large,   relatively 
heavy,  incurved  caudal  spines.    The  left 
side  is  convex  and  the  right  one  concave. 
The  macronucleus  is  25  to  50 (Lt  long;  it  is 
heavy  and  rod-like,  with  the  anterior  end 
bent  at  a  45°  angle.    The  2  contractile 
vacuoles  lie  in  the  left  rib  slightly  below 
the  midline.     This  species  occurs  in  the 
ox  and  zebu. 

D.  quinquecaudatum  Dogiel,   1925 
measures  57  to  73  by  47  to  65/i .    It  re- 
sembles D.  deu/atu)!!,  but  has  5  caudal 
spines.    It  occurs  in  cattle  and  sheep. 

D.  anacaiilhuDi  Dogiel,   1927  meas- 
ures 60  to  124  by  38  to  72 /i.     The  poster- 
ior end  of  its  body  tapers,  giving  it  a 
somewhat  conical  appearance.    The  ma- 
cronucleus varies  a  good  deal  in  length. 
Its  anterior  third  is  bent  at  an  angle  of 
about  45°.    The  2  contractile  vacuoles 
are  on  the  lower  side.    This  species  has 
7  formae  (which  Kofoid  and  MacLennan, 


THE  CILIATES 


355 


d.  disk ; 

memb \      J^,/ 

in.  d-  lip 

out.  d.   lip. rp-        I      II     j,^ 

out.  d.  fur. -/^  JeJf^ 

mcmb.  root. /'■^~-        //  I  I        ^ A 

^/f  If 

micr.  - 
cont.  vac.  - 


in.  ad.  lip 
out.  ad.  lir- 
oat  ad.  fur- 


bound,  lay. 


in.  fibril 
-•anch.  fibril 

m.  anch,  fibril 


Fig.  39.      Ciliates  of  ruminants.     A.    Dipluiliitiiini  deiitatittu.     X  850.    anch.  fibril,   an- 
choring fibril;  aiiKS.  cytopyge;  buKiid.   lay.,   boundary  layer;  cont.   vac.  con- 
tractile vacuole;  (/.  disk,   metoral  disk;  eel.  .   ectoplasm;  t';/(/.  ,  endoplasm; 
e\c.  pore,   excretory  pore;  ///.  ad.   lip.  inner  adoral  lip;  in.   d.   lip,  inner 
metoral  lip;  in.  fibril,    inner  fibril;  inacr.  ,  macronucleus;  ;/;.   anch.  fibril, 
main  anchoring  fibril;  inarg.  fibril,  marginal  fibril;  menib.  .  membranelle; 
iiicinb.    root,    membranelle  root;  iiiicr.  ,  micronucleus;  mouth,    mouth;  ocs.  . 
esophagus;  opcr.  ,  operculum;  or.  disk,  oral  disk;  out.  ad.  fur.  .   outer  adoral 
furrow;  out.   ad.   lip,    outer  adoral  lip;  out.   d.   fur.  ,  outer  metoral  furrow; 
out.  d.   lip.   outer  metoral  lip;   reel.,  rectum.     B.    Mctadiniuin  medium. 
X  425.     C.     Ostracodinium  iiiamniusiun.    X  425.     (From  Kofoid  and  Mac Lennan, 
1932) 


1930,  considered  separate  species): 
anacaiithum ,  monacantluim .  diacaiithiDii . 
tyiacaiithum,   tetracaiitJiuDi,  peiitacaii- 
tkum,   and  anisacanthutu.  with  0,   1,  2,   3, 
4,   5  and  6  caudal  spines,  respectively. 
It  occurs  in  the  ox  and  zebu. 

D.  psittaceum  Dogiel,   1927  measures 
95  to  155  by  59  to  105  jix  and  has  a  heavy, 
rounded,  posteriorly  tapering  body  with  a 
thin  ventral  spine  on  the  right  and  a  nar- 
row flaiige  on  the  left  of  the  posterior 
third  of  the  body.     The  macronucleus  is  a 
stout  rod-like  body  with  its  anterior  end 
bent  at  a  40°  angle.    The  contractile  vac- 
uoles lie  near  the  left  side.    This  species 
occurs  in  the  ox  and  zebu. 


D.  biibalidis  Dogiel,  1925  measures 
104  to  195  by  58  to  98  |u  and  has  an  oval 
body  with  its  largest  diameter  anterior,  a 
strongly  convex  left  side  and  a  slightly 
convex  right  one.    There  is  a  small,  longi- 
tudinal groove  on  the  posterior  part  of  the 
upper  surface  of  the  body,  and  a  single, 
thin  spine  on  the  right.     This  species  oc- 
curs in  cattle  and  African  antelope. 


D.  elongatum  Dogiel,  1927  measures 
177  to  205  by  73  to  IOO^l  and  has  an  elon- 
gate body  with  weakly  convex  left  and  right 
sides  and  a  narrow  groove  in  the  posterior 
end  of  the  upper  surface  of  the  body.    It 
occurs  in  the  ox. 


356 


THE  CILIATES 


D.  laeve  Dogiel,  1927  measures  77 
to  100  by  52  to  70 /i  and  has  a  roughly  tri- 
angular body  with  no  caudal  projections 
except  a  small  lobe  on  the  right.    It  occurs 
in  goats. 

D.  crislagalli  Dogiel,  1927  measures 
77  to  100  by  52  to  70  jx  and  has  a  triangu- 
lar body  with  the  lower  side  extended  pos- 
teriorly to  form  a  prominent  fan  with  2 
to  7  spines.    It  occurs  in  goats. 

D.  flabellum  Kofoid  and  MacLennan, 
1932  measures  82  to  118  by  57  to  82  ^t  and 
has  a  roughly  triangular  body  with  the 
upper  side  extended  posteriorly  to  form  a 
prominent  fan  with  5  to  7  spines,  and  with 
2  small  spines  on  the  posterior  left  side. 
It  occurs  in  the  zebu. 

Genus  EREfAOPLASTRON 
Kofoid   and  MacLennan,  1932 

The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  same  level.    There  is 
a  single,  narrow  skeletal  plate  beneath  the 
upper  surface.    The  macronucleus  is  tri- 
angular or  rod-like,  often  with  its  anter- 
ior end  bent  to  the  right.    Two  contractile 
vacuoles  are  present.    This  genus  occurs 
in  the  rumen  and  reticulum  of  cattle,  sheep, 
antelope  and  reindeer. 

Eremoplastron  rostratum  (Fiorentini, 
1889)  Kofoid  and  MacLennan,  1932  (syn. , 
Diplodinium  helseri  Becker  and  Talbott, 
1927)  measures  40  to  63  by  22  to  47  ^i  and 
has  a  proportionately  long,  compressed 
body  with  a  thick  flange  on  the  left  and  a 
large  caudal  spine  on  the  right.    The  ma- 
cronucleus is  rod-like.    This  species 
occurs  in  the  ox  and  zebu. 

E.  neglectuni  (Dogiel,   1925)  is  81  to 
124/1  long  and  has  an  elongate  oval  body 
with  the  left  side  strongly  convex,  the 
right  side  slightly  convex,  a  large  lobe  on 
the  right,  and  a  long,  rod-like  macronu- 
cleus.   It  occurs  in  cattle  and  African 
antelope. 

E.  bov is  {Dogiel,   1921)  {syn. ,  Diplo- 
dinium clevelandi  Becker  and  Talbott, 
1927)  measures  52  to  100  by  36  to  ^1  \x 
and  has  an  ellipsoidal,  compressed  body 


with  a  somewhat  flattened  right  side,  a 
more  strongly  convex  left  side,  and  a 
small  caudal  lobe.    The  macronucleus  is 
rod-shaped.    This  species  occurs  in  the 
ox,  zebu  and  sheep. 

E.  monolobum  (Dogiel,   1927)  is  58  to 
83(1  long  and  has  a  nearly  spherical  body 
with  a  prominent  right  lobe  and  a  low, 
blunt  left  lobe.    The  macronucleus  is  thick 
and  rod-shaped.    This  species  occurs  in 
cattle. 

E.  dilobum  (Dogiel,   1927)  is  73  to 
101 /i  long  and  has  an  ellipsoidal,  flattened 
body  with  1  left  and  1  right  caudal  lobe. 
The  macronucleus  is  rod-shaped.    This 
species  occurs  in  cattle  and  sheep. 

E.  rugosum  (Dogiel,  1927)  is  69  to 
90 /i  long  and  has  a  short  body  with  a  flat 
or  slightly  concave  right  side,  a  convex 
left  side,  and  a  deep  cuticular  fold  from 
the  cytopyge  along  the  left  side  of  the 
macronucleus  to  the  region  of  the  metoral 
zone  of  membranelles.    The  right  lobe  is 
laterally  compressed,  with  8  to  10  shallow 
indentations  in  its  left  border.    The  ma- 
cronucleus is  long  and  rod-like.    This 
species  occurs  in  cattle. 

E.  brevispinum  Kofoid  and  MacLennan, 
1932  measures  72  to  92  by  42  to  53  p.  and 
has  an  ellipsoidal,  flattened  body  with  2 
short  caudal  spines.    The  macronucleus 
is  rod-shaped.    This  species  occurs  in 
the  zebu. 

E.  magnodentatum  Kofoid  and  Mac- 
Lennan, 1932  measures  58  to  82  by  30  to 
50jLi  and  has  a  rectangular,  flattened  body 
with  a  large,  compressed  caudal  spine  on 
the  right  and  a  similar  caudal  spine  on  the 
left.    The  macronucleus  is  rod-shaped. 
This  species  occurs  in  the  zebu. 

Genus  EUDIPLODINIUM  Dogiel,  1927 
emend.  Kofoid  and  MacLennan,  1932 

The  metoral  and  adoral  zones  of  mem- 
branelles are  at  the  anterior  end.    There 
is  a  single,  narrow  skeletal  plate  beneath 
the  upper  surface.    The  macronucleus  is 
rod-like,  with  its  anterior  end  enlarged 
to  form  a  hook  which  opens  to  the  left. 


THE  CILIATES 


357 


The  pellicle  and  ectoplasm  are  thick. 
There  are  2  contractile  vacuoles  with 
heavy  membranes  and  prominent  pores. 

Eudiplodinium  maggii  (Fiorentini, 
1889)  measures  104  to  240  by  63  to  77  [i 
and  has  a  roughly  triangular  body  with  a 
smoothly  rounded  posterior  end.    It  occurs 
in  the  rumen  and  reticulum  of  the  ox  and 
zebu. 

Genus  DIPLOPLASTRON 
Kofoid  and  MacLennan,1932 


This  species  occurs  in  the  rumen  of  sheep, 
goats  and  cattle. 

M.  ypsilon  (Dogiel,  1925)  measures 
110  to  152  by  60  to  12  ji  and  has  an  oval, 
flattened  body  with  a  rounded  posterior 
end.    The  anterior  lobe  of  the  macronu- 
cleus  is  small,  and  there  is  no  posterior 
lobe.    The  skeletal  plates  are  fused  pos- 
teriorly.   This  species  occurs  in  the 
rumen  of  cattle. 


Genus  POLYPLASTRON  Dogiel,  1927 


The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  anterior  end.    There 
are  2  skeletal  plates  beneath  the  upper 
surface.    The  macronucleus  is  narrow  and 
rod-like.    There  are  2  contractile  vac- 
uoles below  the  left  surface,  separated 
from  the  macronucleus. 

Diploplastron  affine  (Dogiel  and  Fedor- 
owa,  1925)  measures  88  to  120  by  47  to  65jLt 
and  is  more  or  less  ellipsoidal.    It  occurs 
in  the  rumen  of  cattle,  sheep  and  goats. 

Genus  MEIADINIUM 
Awerinzew  and  Mutafowa,  1914 

The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  anterior  end.    There 
are  2  skeletal  plates  beneath  the  upper  sur- 
face which  are  sometimes  fused  poster- 
iorly.   The  macronucleus  has  2  to  3  left 
lobes.    There  are  2  contractile  vacuoles. 
The  pellicle  and  ectoplasm  are  thick. 
There  are  conspicuous  esophageal  fibrils 
beneath  the  left  and  upper  sides. 

Metadiniuni  medium  Awerinzew  and 
Mutofowa,  1914  measures  180  to  272  by 
92  to  170  |u  and  has  a  heavy  body  with 
large  membranelle  zones.    The  skeletal 
plates  are  narrow.    This  species  occurs 
in  the  rumen  of  the  ox  and  zebu. 

M.  tauricum  (Dogiel  and  Fedorowa, 
1925)  measures- 185  to  288  by  70  to  160 ;i 
and  has  a  heavy  body.    The  skeletal  plates 
are  fused  posteriorly.    The  anterior  and 
median  lobes  of  the  macronucleus  are 
large,  and  the  posterior  lobe  is  small. 


The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  anterior  end.    There 
are  2  separate  or  fused  skeletal  plates 
beneath  the  upper  surface,  and  3  longi- 
tudinal plates  with  anterior  ends  connected 
by  cross  bars  beneath  the  lower  surface. 
There  is  a  longitudinal  row  of  contractile 
vacuoles  beneath  the  left  surface,  and 
others  in  other  locations. 

Polyplastron  multivesiculatum  (Dogiel 
and  Fedorowa,  1925)  measures  120  to  190 
by  78  to  140jLt  and  has  an  oval  body  with  a 
smoothly  rounded  posterior  end.    There  is 
a  row  of  4  contractile  vacuoles  near  the 
macronucleus,  plus  2  beneath  the  left  sur- 
face, 1  beneath  the  right  surface  and  2  be- 
neath the  upper  surface.    The  2  upper 
skeletal  plates  are  separate.    This  species 
occurs  in  the  rumen  of  cattle  and  sheep. 

P.  fenestratum  Dogiel,  1927  resem- 
bles P.  multivesiculatum  except  that  the 
upper  skeletal  plates  are  partly  fused. 
This  species  occurs  in  the  rumen  of  cattle. 

P.  monoscutum  Kofoid  and  MacLen- 
nan,  1932  resembles  P.  multivesiculatum 
except  that  the  upper  skeletal  plates  are 
completely  fused  to  form  a  single  broad 
plate.    This  species  occurs  in  the  rumen 
of  cattle. 


Genus  ElYTROPLASTRON 
Kofoid  and  MacLennan,  1932 

The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  anterior  end.    There 
are  2  skeletal  plates  beneath  the  upper 


358 


THE  CILIATES 


surface,  a  small  plate  beneath  the  right 
surface  and  a  long  plate  below  the  lower 
surface.    The  pellicle  and  ectoplasm  are 
thick.    There  are  conspicuous  fibrils  be- 
neath the  left  and  upper  surfaces. 

Elytroplastron  bubali  (Dogiel,   1928) 
measures  110  to  160  by  67  to  97  ^i  and 
has  an  ellipsoidal  body  with  a  smoothly 
rounded  posterior  end.    There  are  4  con- 
tractile vacuoles  along  the  left  midline. 
This  species  occurs  in  the  rumen  of  the 
water  buffalo  and  zebu. 


Genus  OSIRACODINIOM  Dogiel,  1927 

The  metoral  and  adoral  zones  of  mem- 
branelles  are  at  the  anterior  end.    There 
is  a  broad  skeletal  plate  beneath  the  upper 
side  of  the  body,  and  a  row  of  2  to  6  con- 
tractile vacuoles  beneath  the  left  surface. 
Heavy  pharyngeal  fibrils  are  present 
which  extend  to  the  posterior  end. 

Ostracodinium  mammosuni  (Railliet, 
1890)  measures  41  to  110  by  25  to  68 fi 
and  has  a  left  caudal  lobe  and  a  right  lobe 
which  is  hollow  on  the  left  side.    The  pos- 
terior part  of  the  skeleton  extends  only 
2  3  of  the  way  across  the  upper  side. 
The  macronucleus  has  a  large,  shallow 
depression  in  the  middle  of  its  lower  side. 
There  are  3  contractile  vacuoles.    This 
species  occurs  in  the  rumen  of  the  ox  and 
zebu. 

0.  gracile  (Dogiel,  1925)  measures 
90  to  133  by  42  to  60  |i  and  has  a  roughly 
triangular  body  with  flat  right  and  lower 
surfaces  and  convex  left  and  upper  sur- 
faces, and  with  a  smoothly  rounded  pos- 
terior end.    The  skeletal  plate  extends 
across  the  upper  surface.    The  macro- 
nucleus  has  2  lobes.    There  are  2  con- 
tractile vacuoles.    This  species  occurs 
in  the  rumen  of  the  ox,  zebu,  sheep  and 
African  antelopes. 

O.  temie  (Dogiel,  1925)  measures  59 
to  76  by  28  to  38  |i  and  has  a  slender  body 
with  a  smoothly  rounded  posterior  end. 
The  skeletal  plate  extends  across  the 
upper  surface.     The  macronucleus  has  an 
anterior  and  a  median  left  lobe.    There 


are  2  contractile  vacuoles.    This  species 
occurs  in  the  rumen  of  cattle  and  an 
African  antelope. 

O.  Irivesiciilatum  Kofoid  and  Mac- 
Lennan,  1932  measures  78  to  100  by  42 
to  QO\i  and  has  a  triangular  body  with  a 
smoothly  rounded  posterior  end.     The 
skeletal  plate  extends  across  the  upper 
side.    The  macronucleus  has  a  small, 
shallow  depression  in  the  middle  of  the 
lower  side.    There  are  3  contractile  vac- 
uoles.   This  species  occurs  in  the  rumen 
of  the  zebu. 

O.  quadrivesiculatum  Kofoid  and  Mac- 
Lennan,   1932  measures  92  to  112  by  43 
to  56  (i  and  has  a  triangular  body  with  a 
bluntly  rounded  posterior  end.     The  skel- 
etal plate  extends  across  the  upper  side. 
The  macronucleus  is  elongate  and  rod- 
like.   There  are  4  contractile  vacuoles. 
This  species  occurs  in  the  rumen  of  the 
zebu. 

O.  tianum  (Dogiel,   1925)  measures 
47  to  70  by  30  to  41  jix  and  has  an  ellip- 
soidal body  with  a  slender,  right  caudal 
spine.    The  skeletal  plate  extends  between 
the  macronucleus  and  the  ventral  surface. 
The  macronucleus  is  short  and  stout. 
There  are  2  small  contractile  vacuoles. 
This  species  occurs  in  the  rumen  of  cattle 
and  African  antelopes. 

O.  gladiator  (Dogiel,  1925)  measures 
78  to  112  by  40  to  55 /i  and  has  a  slender 
body  with  a  long,  very  narrow,   right 
caudal  spine.    The  skeletal  plate  extends 
between  the  macronucleus  and  the  right 
side.    The  macronucleus  has  a  lobe  on  the 
left  anterior  end.    There  are  2  contractile 
vacuoles.    This  species  occurs  in  the 
rumen  of  cattle  and  African  antelopes. 

O.  crassum  (Dogiel,   1925)  measures 
120  to  142  by  80  to  100  ^  and  has  a  heavy 
body  with  a  smoothly  rounded  posterior 
end.    The  skeletal  plate  extends  under 
only  1/2  of  the  upper  side.    The  macro- 
nucleus  is  short  and  stout,  with  a  wide, 
shallow  depression  in  the  anterior  half  of 
its  left  side.    There  are  2  contractile  vac- 
uoles.   This  species  occurs  in  the  rumen 
of  cattle  and  the  steenbock. 


THE  CILIATES 


359 


O.  obtusuni  (Dogiel  and  Fedorowa, 
1925)  (syn.,  Diplodinium  hegneri  Becker 
and  Talbott,  1927)  measures  118  to  148 
by  55  to  80  [i  and  has  an  ellipsoidal,  only 
slightly  flattened  body,  with  a  smoothly 
rounded  posterior  end.    The  posterior 
part  of  the  skeleton  extends  across  only 
2/3  of  the  upper  side.    The  macronucleus 
is  elongate  and  rod-like.    There  are  6 
contractile  vacuoles.    This  species  occurs 
in  the  rumen  of  cattle  and  reindeer. 

O.  venustum  Kofoid  and  MacLennan, 
1932  measures  76  to  115  by  41  to  60  (n  and 
has  a  triangular  body  with  a  small  pos- 
terior right  lobe.    The  skeletal  plate  ex- 
tends beneath  the  upper  surface  between 
the  macronucleus  and  the  right  side.    The 
macronucleus  has  2  left  lobes.    There  are 
2  contractile  vacuoles.    This  species  oc- 
curs in  the  rumen  of  the  zebu. 

O.  dogieli  Kofoid  and  MacLennan, 
1932  measures  92  to  130  by  48  to  63  (n  and 
has  an  ellipsoidal  body  with  a  strongly 
convex  left  side,  a  slightly  convex  right 
side  and  a  flattened  right  lobe  lying  below 
the  cytopyge.    The  skeletal  plate  extends 
between  the  macronucleus  and  the  right 
side.    The  macronucleus  has  2  left  lobes 
(1  anterior  and  1  median).    There  are  2 
contractile  vacuoles.    This  species  oc- 
curs in  the  rumen  of  the  ox. 

O.  clipeolum   Kofoid  and  MacLennan, 
1932  measures  92  to  128  by  50  to  65 fi  arid 
has  an  ellipsoidal  body  with  a  flattened 
lobe  projecting  from  the  right  posterior 
surface  below  the  midline.    The  skeletal 
plate  extends  beneath  the  upper  surface 
between  the  macronucleus  and  the  right 
side.    The  macronucleus  has  2  left  lobes. 
There  are  3  contractile  vacuoles.    This 
species  occurs  in  the  rumen  of  the  zebu. 

O.  monolobum    Dogiel,  1927  meas- 
ures 105  to  150  by  55  to  77  jx  and  has  a 
rectangular  body  with  a  large  right  lobe. 
The  skeletal  plate  extends  under  only  2/3 
of  the  left  side.    The  macronucleus  is 
elongate  and  rod-like.    There  are  5  con- 
tractile vacuoles.    This  species  occurs 
in  the  rumen  of  the  ox. 

O.  dilobum  Dogiel,  1927  measures 
88  to  140  by  54  to  78  ^  and  has  an  ellip- 


soidal body  with  a  laterally  flattened  right 
lobe  and  a  flattened  left  lobe.    The  skeletal 
plate  extends  under  only  2/3  of  the  left  side. 
The  macronucleus  is  elongate  and  rod- 
like.   There  are  5  contractile  vacuoles. 
This  species  occurs  in  the  rumen  of  cattle. 

O.  rugoloricatiim  Kofoid  and  Mac- 
Lennan, 1932  measures  84  to  125  by  37  to 
58  \i  and  has  a  rectangular  body  with  a 
flattened  right  lobe.    The  left  side  of  the 
exceptionally  large  skeletal  plate  turns  in 
and  extends  toward  the  middle  of  the  body. 
The  macronucleus  is  straight  and  rod-like. 
There  are  3  contractile  vacuoles.    This 
species  occurs  in  the  rumen  of  the  zebu. 


Genus  ENOPLOPLASTRON 
Kofoid  and  MacLennan,  1932 

The  metoral  and  adoral  zones  of  mem- 
branelles  are  near  the  anterior  end.    There 
are  3  separate  or  partially  fused  skeletal 
plates  beneath  the  upper  and  right  surfaces 
of  the  body.    There  are  2  contractile  vac- 
uoles.   The  pharyngeal  fibrils  are  heavy. 

Enoploplastron  triloricatum  (Dogiel, 
1925)  measures  60  to  112  by  37  to  70 ju,  and 
has  an  ellipsoidal  body  with  a  smoothly 
rounded  posterior  end.    The  skeletal  plates 
are  separate.    The  macronucleus  has  a 
shallow  depression  in  the  anterior  half  of 
its  left  side.    This  species  occurs  in  the 
rumen  of  the  ox,  reindeer  and  an  African 
antelope. 


RELATIONS   OF   RUMEN   CILIATES 
TO   THEIR    HOSTS 

Ciliates  swarm  in  such  tremendous 
numbers  in  the  rumen  and  reticulum  that 
everyone  who  has  seen  them  has  specu- 
lated on  their  role  in  their  host's  nutrition. 
This  problem  has  been  reviewed  by  Hungate 
(1950,  1955)  and  Oxford  (1955,  1955a),  to 
whose  papers  reference  is  made  for  fur- 
ther details.    It  should  be  said  that  in 
these  reviews  the  name  "Diplodinium''  is 
used  for  practically  all  the  ophryoscolecids 
except  Entodinium  and  Ophryoscolex,  but 
the  other  genera  involved  can  often  be  de- 
termined from  their  specific  names. 


360 


THE  CILIATES 


The  rumen  ciliates  are  obligate  an- 
aerobes.   The  holotrichs  (Isolricha  and 
Dasytricha)  have  been  cultivated  by  Sugden 
and  Oxford  (1952),  Gutierrez  (1955)  and 
others.    Diplodinium,  Entudinimn ,  Eudi- 
plodiniimi,   Polyplastron  and  Metadiniiim 
have  been  cultivated  by  Hungate  (1942, 
1943),  Sugden  (1953),  and  others,  but 
Ophryoscolex  has  not  yet  been  cultivated. 

The  holotrichs  absorb  soluble  carbo- 
hydrates from  the  medium  and  convert 
them  into  amylopectin,  which  is  stored  in 
ovoid  granules  measuring  3  by  2)j.  and 
resembling  small  yeast  cells.    They  are 
able  to  utilize  glucose,  fructose,  sucrose, 
cellobiose,   inulin  and  levans.    In  addition, 
both  Isotriclia  iidestinalia  and  /.  prosloDia 
rapidly  ingest  small  starch  granules  and 
are  able  to  metabolize  them.    Dasytricha 
ru))iinantiiu)i  does  not  ingest  starch. 
Gutierrez  and  Hungate  (1957)  found  that 

D.  rimiuiautiii}}}  ingested  small  cocci  and 
occasionally  small  rod-shaped  bacteria; 
they  were  able  to  cultivate  this  species  in 
a  medium  containing  these  types  of  bac- 
teria, but  not  without  them.    Gutierrez 
(1958)  showed  that /so/r/cto  prostoma 
feeds  selectively  only  on  certain  rods 
among  the  many  types  of  rumen  bacteria, 
but  that  pure  strains  did  not  fulfill  all  the 
protozoon's  growth  requirements,   since 
it  divided  once  and  then  died  out  in  a 
monobacterial  culture. 

The  holotrichs  produce  hydrogen, 
carbon  dioxide,  lactic,  acetic  and  butyric 
acids,  and  traces  of  propionic  acid  (Heald 
and  Oxford,   1953;  Gutierrez,   1955). 

Many  but  not  all  species  of  Entodin- 
iuni  ingest  and  digest  starch.    According 
to  Kofoid  and  MacLennan  (1930),   E.   lon- 
ginuclealuni  and  E.  acutonucleatuni  feed 
selectively  on  pollen  grains.    Certain 
species  of  Entodi>iium  are  the  predomi- 
nant starch-ingesters  among  the  rumen 
protozoa  and  are  the  dominant  protozoa 
in  animals  on  full  feed.    Among  those 
known  to  ingest  starch  ar^  E.  caudatum , 

E.  longinucleatiun,   E.  ininiDiiuit  and  £. 
dubardi.     Almost  nothing  is  known  about 
the  products  of  starch  fermentation  by  this 
genus.    Granules  of  polysaccharide  are 
stored  in  the  outer  zone  of  the  endoplasm, 
but  they  have  never  been  isolated  and 


identified;  it  would  be  difficult  to  separate 
them  from  ingested  starch  granules. 

It  has  been  suggested  that  carbohy- 
drate metabolism  is  dependent  upon  intra- 
cellular bacteria.    Sugden  (1953)  was  un- 
able to  cultivate  E.  longinnclealH»i  in  the 
presence  of  streptomycin  except  when 
streptomycin-resistant  strains  of  bacteria 
were  present.    However,  Appleby,  Eadie 
and  Oxford  (1956),  who  found  various 
bacteria  in  disintegrated  E)iludinii(in,  con- 
cluded that  there  was  so  far  no  good  reason 
for  denying  the  existence  of  protozoan  en- 
zyme systems  concerned  with  carbohydrate 
fermentation.    Gutierrez  and  Davis  (1959) 
found  about  100  to  150  gram -positive  diplo- 
cocci  (Streptococcus  boris)  per  ciliate  in 
E.   caudatum,  E.  minimum,  E.  dubardi, 
E.   longinucleatum,  E.  bursa,  E.  nanel- 
lum,  E.   exiguum  and  E.   vorax  in  cattle 
being  fed  a  high  starch  ration.     The  cili- 
ates sometimes  ingested  starch  granules 
with  adherent  starch-attacking  bacteria. 
EntodiniuDi  species  could  be  cultivated  in 
the  presence  of  S.  bovis  but  not  without  it. 
Thus,  bacteria  are  ingested  by  Entodin- 
iiiDi  and  appear  to  be  necessary  for  its 
nutrition,  but  most  likely  as  a  source  of 
nitrogen  rather  than  of  prefabricated  en- 
zymes. 

Epidinium,  like  Entodinium,  ingests 
starch  and  also  bacteria;  its  metabolic 
products  are  also  unknown.    Gutierrez 
and  Davis  (1959)  found  that  E.  ecaudatum 
(syn. ,  DiplodiniuDi  ecaudatum  )  ingested 
not  only  Streptococcus  bovis  but  also  other 
bacteria. 

Diplodinium  and  related  genera 
(EudiplodiniuDi,  Polyplastron,  Eremo- 
plastroii,  Metadinium  )  ingest  and  digest 
cellulose  in  addition  to  starch  and  bacteria. 
Hungate  (1942,   1943)  cultured  Diplodinium 
dentatum  (syn.,  D.  deniiculatuDt),  Poly- 
plastron multivesiculatum  and  Eudiplodin- 
iuni  niaggii  in  media  containing  dried  grass 
and  pure  cellulose,  but  the  protozoa  failed 
to  grow  if  the  cellulose  was  omitted.    These 
species  and  Eremoplastron  neglectuni  all 
contained  a  cellulase.    Sugden  (1953) found 
that  Metadinium  medium  also  utilized  cel- 
lulose.   Gutierrez  and  Davis  (1959)  found 
that  E.  neglectum  and  a  large  unidentified 
species  of  ''Diplodinium''  contained  gram- 


THE  CILIATES 


361 


positive  diplococci  and  other  bacteria  on 
different  occasions.    Sugden  and  Oxford 
(1955)  found  that  a  "pure",  washed,  living 
suspension  of  Metadiniiun  ivediuni  had  no 
action  on  glucose  in  the  Warburg  apparatus. 

Diplodlnium  and  related  species  were 
found  by  Hungate  (1946)  to  produce  hydro- 
gen, carbon  dioxide  and  volatile  acids. 

The  skeletal  plates  of  all  ophryoscol- 
ecids  which  have  them  stain  brown  with 
iodine  and  are  polysaccharide  in  nature. 
According  to  Oxford  (1955),   Hirst  et  al. 
extracted  enough  of  the  storage  polysac- 
charide from  Metadinium  medium  to 
identify  it  as  of  the  "glycogen-amylopectin" 
type,  but  they  were  not  sure  whether  it 
was  pure  amylopectin. 

The  mode  of  nutrition  of  Ophryoscolex 
has  not  been  determined,  altho  it  is  known 
to  ingest  starch  granules  and  sometimes 
cellulose  fibers. 

Lubinsky  (1957b)  reported  that  acci- 
dental predation  on  smaller  protozoa  is  a 
common  trait  of  many  of  the  larger  spe- 
cies of  Ophryoscolecidae,  particularly  of 
Diplodinium  and  related  cellulose-feeding 
genera.     Predation  is  rare  in  Ophryosco- 
lex, however.    The  prey  of  these  occa- 
sional predators  consists  primarily  of 
spineless  smaller  species.    The  spines 
are  thus  of  value  in  protecting  the  smaller 
ophryoscolecids  against  ingestion.     Lubin- 
sky gave  a  table  listing  cases  of  predation 
among  ophryoscolecids  from  the  Canadian 
reindeer,  goat,  sheep  and  Indian  water 
buffalo,  which  included  8  genera  and  9 
species  of  predators  and  7  genera  and  9 
species  of  prey. 

The  role  of  the  rumen  protozoa  in 
their  host's  nutrition  is  still  not  clear. 
Young  animals  on  a  milk  diet  do  not  have 
them.    As  they  grow  older  and  begin  to 
feed  on  hay  and  grass,  they  become  in- 
fected from  protozoa  in  the  saliva  of 
faunated  animals.    This  is  the  only  way  in 
which  transmission  occurs.     There  are 
no  resistant  forms  or  cysts,  and  the  pro- 
tozoa are  killed  when  they  enter  the 
abomasum. 


The  relation  between  the  protozoa  and 
their  hosts  is  not  symbiotic,   since  the  host 
does  not  need  the  protozoa  for  survival, 
and  indeed  gets  along  perfectly  well  without 
them.     Becker,  Schulz  and  Emmerson 
(1929,   1930)  and  Winogradow  et  al.   (1930) 
killed  the  protozoa  in  the  rumens  of  goats 
without  harming  the  goats.    The  defaunated 
animals  continued  to  break  down  cellulose 
just  as  actively  as  the  normal  controls,  due 
to  the  action  of  cellulolytic  bacteria. 
Pounden  and  Hibbs  (1950)  raised  calves 
successfully  without  protozoa. 

The  fact  that  defaunation  is  not  harm- 
ful does  not  mean,  however,  that  the  pro- 
tozoa are  of  no  value  to  their  hosts.    It 
means  simply  that  they  are  not  essential. 

It  has  been  suggested  that  the  protozoa 
might  harm  their  hosts  by  excreting  am- 
monia which  may  then  not  be  utilized  by 
the  rumen  bacteria  for  protein  synthesis 
and  which  would  therefore  be  lost  to  their 
hosts;  by  robbing  the  host  of  B  vitamins; 
by  feeding  on  and  destroying  valuable  bac- 
teria; or  by  producing  lactic  acid  and  other 
undesirable  intermediate  products  of  car- 
bohydrate metabolism  which  the  rumen 
bacteria  cannot  cope  with  (see  Oxford, 
1955).    However,  there  is  no  proof  that 
they  are  actually  harmful,  and  this  is  sim- 
ply speculation. 

Rumen  protozoa  form  about  20%  of  the 
protein  which  reaches  the  abomasum 
(Hungate,   1955).     McNaught  et  al.  (1954) 
found  that  the  rumen  protozoan  and  bacter- 
ial proteins  both  had  a  biological  value  for 
rats  of  80  to  81,  which  is  higher  than  that 
of  brewer's  yeast  (72).     Furthermore,  the 
true  digestibility  of  the  protozoan  protein 
was  91%,  much  higher  than  that  of  the  bac- 
terial (74%)  or  yeast  (84%)  proteins.    Hence 
the  protozoan  protein  is  nutritionally  su- 
perior.   No  amino  acid  analyses  have  been 
carried  out  on  it. 

While  many  of  the  protozoa  store  re- 
serve starch  (amylopectin),  this  stored 
starch  is  not  of  much  importance  for  the 
host's  nutrition.    About  1%  of  the  carbohy- 
drate required  by  a  mature  sheep  is  sup- 
plied from  this  source  (Hungate,  1955). 


362 


THE  CaiATES 


The  protozoa  are  an  important  source 
of  volatile  fatty  acids.    Carroll  and  Hun- 
gate  (1954)  estimated  that  about  2.  2  kg  of 
volatile  fatty  acids  are  produced  per  100 
kg  rumen  contents  in  cattle.    Gutierrez 
(1955)  calculated  that  the  fermentation 
acids  produced  by  the  rumen  holotrichs 
would  constitute  a  little  more  than  10%  of 
this  amount.    If  the  ophryoscolecids  pro- 
duced an  equal  amount,  then  protozoa 
would  provide  about  20%  of  the  fermenta- 
tion products  available  to  their  host 
(Hungate,   1955).    As  Hungate  (1955)  re- 
marked, Gruby  and  Delafond,  who  first 
discovered  the  rumen  protozoa  in  1843, 
guessed  that  they  supplied  1/5  of  the  food 
used  by  their  hosts,  and  the  results  of 
investigations  during  the  next  110  years 
have  not  significantly  modified  that  esti- 
mate. 

Another  advantage  to  the  host  lies  in 
the  fact  that  the  holotrichs  take  up  soluble 
carbohydrates  from  the  medium  and  con- 
vert them  into  stored  starch,  withholding 
them  for  a  while  and  then  fermenting  them 
for  a  long  time.    This  smooths  out  the 
fermentation  process,  which  would  proceed 
much  more  irregularly  if  it  depended  upon 
bacteria  alone  (Hungate,  1955;  Oxford, 
1955).    Entodiniuni  and  Epidiniuni,  too, 
help  smooth  out  the  fermentation  process 
by  converting  starch  into  reserve  foods. 
In  addition,  as  Hungate  (1959)  pointed  out, 
when  animals  are  shifted  from  hay  to 
grain,  there  is  a  period  of  adaptation  dur- 
ing which  lactic  acid  is  produced  explo- 
sively by  Streptococcus  bovis  and  may  be 
extremely  harmful.    The  adaptation  period 
may  be  due  to  the  time  needed  for  Ento- 
diniuni, Epidiniuni  and  other  bacteria- 
feeding  protozoa  to  multiply  enough  to  keep 
the  streptococci  in  check. 


ventral  colon)  differs  from  that  of  the  dis- 
tal large  intestine  (the  dorsal  and  small 
colons).    Strelkov  (1939)  listed  25  species 
and  forms  in  the  proximal  fauna,  43  in  the 
distal  fauna,  and  7  common  to  both.    Mix- 
ing occurs  at  the  pelvic  flexure  of  the 
colon.    All  horses  do  not  contain  all  spe- 
cies.   Strelkov  (1939)  found  an  average  of 
7.  7  species  per  horse  in  the  proximal 
fauna  and  16.  6  species  per  horse  in  the 
distal  fauna. 

The  highest  populations  of  ciliates 
occur  in  the  left  dorsal  colon  and  the 
lowest  in  the  cecum  (Adam,   1951).    The 
ciliate  population  shows  large  daily  vari- 
ations.   Adam  (1953)  obtained  counts  rang- 
ing from  1000  to  47,000  per  ml  in  the 
cecum  and  from  14,  000  to  3,  072, 000  per 
ml  in  the  ventral  colon  of  a  single  horse 
at  different  times  and  on  different  rations. 

Almost  nothing  is  known  of  the  rela- 
tionship of  these  protozoa  to  their  host, 
but  it  is  most  likely  that  they  are  simply 
commensals.    No  cysts  have  been  re- 
ported, and  transmission  is  probably  by 
mouth.    Adam  (1953)  infected  a  horse  with 
Cycloposthium  edentatuni  and  C.   denti- 
ferum  by  feeding  fresh  colon  contents  by 
stomach  tube.     Forsyth,  Hirst  and  Oxford 
(1953)  found  that  Cycloposthium  stores  a 
polysaccharide  with  a  highly  branched 
molecular  structure  closely  similar  to 
that  of  amylopectin. 


FAMILY   BUETSCHLIIDAE 

The  characters  of  this  holotrichasin 
gymnostomorid  family  have  been  given 
above  (p.  349). 


B.   CILIATES  OF   EQUIDS 

Just  as  great  a  variety  and  number  of 
ciliates  swarm  in  the  cecum  and  colon  of 
equids  as  in  the  rumen  and  reticulum  of 
ruminants.    Hsiung  (1930)  gave  descrip- 
tions of  51  species  of  25  genera  in  his 
monograph,  while  Strelkov  (1939)  listed 
87  species  and  forms.    The  fauna  of  the 
proximal  large  intestine  (the  cecum  and 


Genus  ALLOIOZONA  Hsiung,  1930 

The  cilia  are  present  in  3  zones- - 
anterior,  equatorial  and  posterior. 

Alloiozona  trizona  Hsiung,  1930  is 
ovoid,  with  both  ends  rounded,  and  meas- 
ures 50  to  90  by  30  to  60 /i.    The  cytostome 
is  at  the  anterior  end  and  is  surrounded  by 
a  shallow  groove  provided  with  short  cilia. 
The  cytopharynx  is  funnel-shaped.    The 


THE  CILIATES 


363 


Fig.  40.      Ciliates  of  equids.     A.   Alloiozona  trizona.     B.    Ampullamla  ampulla. 

C.    Blepharoconus  hemiciliatus.     D.    Bleplmroconus  cervicalis.    E.    Bleplta- 
roconus  benbrooki.     F.    Blepharopfosthiuni  pireum.    G.    Bleplmrosphaera 
ellipsoidalis.     H.    Blepharospliaera  intestinalis.     I.    Blepharozoum  zonatuni. 
J.   Bundleia  postciliata.     K.   Didesmis  ovalis.     L.   Didesmis  spiralis. 
M.   Didesmis  qiiadrata.     N.    Holophryoides  ovalis.    O.    Paraisotrichopsis 
composita.     P.    Polymorphella  ampulla.     Q.    Prorodonopsis  coli.     R.   Allan- 
tosoma  intestinalis.     S.   Allantosoma  dicorniger .     T.   Allantosoma  brevicor- 
niger.     U.    Blepharocorys  uncinata.    V.   Blepharocorys  valvata.     W.    Bleph- 
arocorys  jubata.     X.   Blepharocorys  angusta.     Y.   Blepharocorys  curvigula. 
Z.    Blepharocorys  cardiormcleata.      AA.    Cliaronina  equi.      AB.  Paraisotriclm 
minuta.      AC.    Paraisotriclw  beckeri.      AD.    Paraisotriclia  colpoidea.     E. ,  P. 
and  AA.  ,  X  710.     All  others,  X  340.     (From  Hsiung,   1930  in  Iowa  State  College 
Journal  of  Science,  published  by  Iowa  State  Univ.  Press) 


364 


THE  CILIA TES 


cytopyge  is  on  a  knob  at  the  posterior  end. 
The  macronucleus  is  a  more  or  less  thick, 
distinctly  granular  disc,  and  is  not  con- 
stant in  position.     The  concretion  vacuole 
is  large  and  is  near  the  surface  in  the 
anterior  third  of  the  body.     There  is 
usually  a  small,  posterior  contractile 
vacuole.     Hsiung  (1930)  found  this  species 
in  the  cecum  or  colon  of  7  out  of  46  horses 
in  Iowa. 


Genus   AMPULLACULA    Hsiung,    1930 

The  body  is  flask-shaped.    Its  pos- 
terior half  is  covered  with  fine,  short 
cilia,  and  its  neck  with  longer  cilia. 

Artipidlacula  a»ipi<lla  (Fiorentini, 
1890)  Hsiung,   1930  measures  about  110 
by  40)jl.    The  cytostome  is  at  the  anterior 
end.    This  species  occurs  in  the  cecum  of 
the  horse. 


Genus  BLEPHAROCONUS 
Gassovsky,   1919 

The  body  is  ovoid.    The  cytostome  is 
small,  and  the  cytopharynx  has  rods  in 
its  wall.    There  are  cilia  on  the  anterior 
third  to  half  of  the  body  and  at  the  caudal 
end.    The  macronucleus  is  ovoid.     There 
are  3  contractile  vacuoles. 

Bleplmroconus  hemiciliatus  Gassov- 
sky, 1919  has  a  conical  body  and  measures 
83  to  135  by  45  to  65ji  .    The  macronucleus 
is  nearly  spherical.    This  species  occurs 
in  the  colon  of  the  horse. 

B.  cervicalis  Hsiung,   1930  is  ovoid, 
with  a  blunt  anterior  and  a  rounded  pos- 
terior end,  and  measures  56  to  83  by  48 
to  70 /i.    There  is  usually  a  short  neck 
which  is  formed  by  a  slight  groove.    The 
macronucleus  is  more  or  less  disc-shaped. 
The  concretion  vacuole  is  small  and  ellip- 
soidal.    Hsiung  (1930)  found  this  species 
in  the  colon  of  2  out  of  46  horses  in  Iowa. 


macronucleus  is  a  thick  disc.    The  con- 
cretion vacuole  is  large  and  ellipsoidal. 
Hsiung  (1930)  found  this  species  in  the 
colon  or  feces  of  2  out  of  46  horses  in  Iowa. 

Genus  BLEPHAROPROSTHIUM 
Bundle,    1895 

The  body  is  piriform,  with  a  contrac- 
tile anterior  half.    There  are  cilia  on  the 
anterior  half  and  at  the  posterior  end. 
The  macronucleus  is  kidney- shaped. 

Blepliaroprosthium  pireum  Bundle, 
1895  measures  54  to  86  by  34  to  52 /j.. 
The  cytostome  is  anterior.    The  cytopharynx 
is  funnel-shaped.    The  concretion  vacuole 
contains  numerous  granules  and  is  found  in 
the  anterior  half  of  the  body  close  to  the 
surface.    There  is  a  contractile  vacuole 
at  the  posterior  end.     Hsiung  (1930)  found 
this  species  in  the  cecum  of  13  and  the 
colon  of  4  out  of  46  horses  in  Iowa. 

Genus  BllPHAROSPHAlRA 
Bundle,   1895 

The  body  is  spherical  or  ellipsoidal. 
Cilia  cover  the  anterior  3/4  of  the  body, 
and  there  is  also  a  caudal  tuft  of  cilia. 

Blepliarospliaera  intestinalis  Bundle, 
1895  is  spherical  and  38  to  74 /i  in  diam- 
eter.   Its  macronucleus  is  a  thick,  ellip- 
soidal disc.     Hsiung  (1930)  found  this 
species  in  the  cecum  of  9  and  the  colon  of 
2  out  of  46  horses  in  Iowa. 

B.  ellipsoidalis  Hsiung,   1930  is  ellip- 
soidal and  measures  34  to  65  by  27  to  49  |i. 
Its  macronucleus  is  sausage-shaped. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  4  and  the  colon  of  2  out  of  46 
horses  in  Iowa. 


Genus  BLEPHAROIOUM 
Gassovsky,   1919 


B.  benbrooki  Hsiung,  1930  is  ovoid 
to  ellipsoidal,  with  a  knob-like  anterior 
end  and  a  rounded  posterior  one,  and 
measures  21  to  37  by  17  to  26 p..     The 


The  body  is  ellipsoidal,  with  an  atten- 
uated anterior  end,  and  is  uniformly  cil- 
iated.   The  cytostome  is  near  the  anterior 
tip.    There  are  2  to  4  contractile  vacuoles. 


THE   CILIATES 


365 


The  macronucleus  is  small  and  kidney- 
shaped. 

Blepharozoum  zonattiDi  Gassovsky, 
1919  measures  230  to  245  by  115  to  122  jll 
and  has  an  anterior  concretion  vacuole. 
It  occurs  in  the  cecum  of  the  horse. 

Genus  BUNDLEIA 
Da  Cunha  and  Muniz,   1928 

The  body  is  ellipsoidal,  with  a  small 
cytostome.    There  are  cilia  at  the  anter- 
ior and  posterior  ends,  the  latter  being 
much  less  numerous  than  the  former. 

Bundleia  postciliata  (Bundle,   1895) 
da  Cunha  and  Muniz,   1928  has  a  slightly 
flattened  body  with  a  sharply  tapering, 
truncate  anterior  end  and  a  truncate  pos- 
terior end,  and  measures  30  to  56  by  17 
to  32  jM.     The  cytopharynx  is  short  and 
funnel-shaped.    The  macronucleus  is  el- 
lipsoidal.   The  concretion  vacuole  is 
small  and  anterior.    There  is  a  small  con- 
tractile vacuole.     Hsiung  (1930)  found  this 
species  in  the  cecum,  colon  or  feces  of  7 
out  of  46  horses  in  Iowa. 


Genus  DIDESMIS  Fiorentini,   1890 

The  anterior  end  of  the  body  forms  a 
neck  behind  the  large  cjdiostome.    There 
are  cilia  at  the  anterior  and  posterior 
ends.    The  macronucleus  is  ellipsoidal. 

Didesmis  ovalis   Fiorentini,   1890  is 
oval  or  rectangular  and  slightly  flattened, 
with  a  blunt  anterior  end  and  a  tapering 
posterior  end.    It  measures  34  to  55  by 
27  to  40 /i  .     The  cytostome  is  at  the  mid- 
dle of  the  anterior  end,  and  the  cytopharynx 
is  short  and  funnel-shaped.    There  is  a 
short  neck  behind  the  cytostome.    The  con- 
cretion vacuole  is  near  the  anterior  end  of 
the  irregularly  oval  macronucleus.    There 
are  1  or  2  contractile  vacuoles.     Hsiung 
(1930)  found  this  species  in  the  cecum  of 
16  and  the  colon  of  6  out  of  46  horses  in 
Iowa. 

D.  quadrata   Fiorentini,   1890  resem- 
bles D.  ovalis,  but  has  a  deep,  wide, 


highly  refractive,  longitudinal  groove  on 
the  dorsal  surface.    It  measures  50  to  90 
by  33  to  Q^ii  and  has  a  spindle-shaped 
macronucleus.     Hsiung  (1930)  found  this 
species  in  the  cecum  of  8  and  the  colon  of 
3  out  of  46  horses  in  Iowa. 

D.  spiralis  Hsiung,   1929  resembles 
D.  quadrata  except  that  it  is  spirally 
shaped.    It  measures  60  to  94  by  38  to  54)i , 
The  dorsal  groove  runs  slightly  diagonally 
to  the  longitudinal  axis.     The  concretion 
vacuole  contains  less  than  10  granules. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  2  out  of  46  horses  in  Iowa. 


Genus  HOIOPHRYOIDES 
Gassovsky,   1919 

The  body  is  ovoid  and  uniformly  cil- 
iated, with  a  comparatively  large  cyto- 
stome at  the  anterior  end.     The  macro- 
nucleus  is  small  and  ellipsoidal.    The 
contractile  vacuole  is  subterminal. 

Holophryoides  ovalis  (Fiorentini, 
1890)  Gassovsky,  1919  measures  95  to 
140  by  65  to  90  ji.    There  is  an  accumula- 
tion of  ectoplasm  at  the  anterior  part  of 
the  body.     Hsiung  (1930)  did  not  find  this 
species  in  Iowa  horses. 

Genus  PARAISOTRICHOPSIS 
Gassovsky,   1919 

The  body  is  uniformly  ciliated  and 
has  a  spiral  groove  from  the  anterior  to 
the  posterior  end. 

Paraisotrichopsis  composita  Gassov- 
sky, 1919  measures  43  to  56  by  31  to  40(i, 
and  has  an  elongate  macronucleus.    Hsiung 
(1930)  did  not  find  it  in  Iowa  horses. 


Genus  POLY MORPHEILA  Corliss,  1960 

The  body  is  flask-shaped,  with  cilia 
in  the  anterior  region  and  a  few  at  the 
caudal  end.    The  macronucleus  is  disc- 
shaped, and  the  contractile  vacuole  termi- 
nal.   The  name  Polyrnorphella  replaces 
the  original  name,  Polymorpfm,   given  by 


366 


THE  CILIATES 


Dogiel  (1929)  because  the  latter  is  a  hom- 
onym of  the  names  previously  given  to  a 
foraminiferan  and  a  lepidopteran  (Corliss, 
1960). 

Polymorphella  ampulla  (Dogiel,  1929) 
Corliss,  1960  measures  22  to  36  by  13  to 
21  ^t .     Hsiung  (1930)  found  it  in  the  cecum 
of  3  and  the  colon  of  1  out  of  46  horses  in 
Iowa. 


Genus  PRORODONOPSIS 
Gassovsky,   1919 

The  body  is  piriform  and  uniformly 
ciliated.  The  macronucleus  is  sausage- 
shaped.    There  are  3  contractile  vacuoles. 

Prorodo)iopsis  co// Gassovsky,  1919 
measures  55  to  67  by  38  to  45jLt.  Hsiung 
(1930)  did  not  find  it  in  Iowa  horses. 


Genus  SUICOARCUS  Hsiung,   1935 


or  stalk.    The  macronucleus  is  ovoid  or 
spherical,  and  the  micronucleus  is  com- 
pact.    There  is  1  contractile  vacuole.    The 
cytoplasm  is  often  filled  with  small  spher- 
oidal bodies. 

Allantosoma  intestinalis  Gassovsky, 
1919  has  a  sausage-shaped  body  with  3  to 
12  tentacles  at  each  end  bearing  distinct 
suckers.    It  measures  33  to  60  by  18  to 
37 /i.    The  cytoplasm  is  filled  with  small, 
round  bodies.     The  macronucleus  is  more 
or  less  spherical.    Hsiung  (1930)  found 
this  species  in  the  cecum  of  6  and  the  colon 
of  8  out  of  46  horses  in  Iowa. 

A.  dicorniger  Hsiung,  1928  has  a  more 
or  less  cycloid  body  with  1  incurved  tenta- 
cle at  each  end,  and  measures  20  to  33  by 
10to20jLt.    The  end  of  the  tentacle  is 
somewhat  boot-shaped.    The  cytoplasm  is 
filled  with  granules.     The  macronucleus  is 
subspherical.     Hsiung  (1930)  found  this 
species  in  the  colon  of  2  out  of  46  horses 
in  Iowa. 


The  body  is  ovoid,  compressed,  with 
a  short  spiral  groove  at  the  anterior  end. 
The  cytostome  is  at  the  end  of  the  groove. 
The  cytopyge  is  terminal.    The  concretion 
vacuole  is  mid-ventral,  with  the  contrac- 
tile vacuole  posterior  to  it.    Cilia  are 
present  on  the  groove,  mid-ventral  region 
and  posterior  end. 

Sulcoarcus  pellucidiibis  Hsiung,   1935 
measures  33  to  56  by  30  to  40  fx.     Hsiung 
(1935)  found  it  in  the  feces  of  the  mule  in 
China. 


FAMILY   ACINETIDAE 

In  this  holotrichasin,   suctoriorid 
family  the  tentacles  are  capitate  and  are 
usually  arranged  in  groups.     Endogenous 
budding  occurs.    A  lorica  is  often  present, 
and  a  stalk  is  present  or  absent. 

Genus  ALLANTOSOMA 
Gassovsky,   1919 

The  body  is  elongate,  with  1  or  more 
tentacles  at  each  end,  but  without  lorica 


A.  brevicorniger  Hsiung,  1928  has  an 
elongate,  cycloid  body  with  1  short,  slen- 
der slightly  incurved  tentacle  at  each  end. 
It  measures  23  to  36  by  7  to  11  ji.  The 
distal  end  of  the  tentacle  is  rounded.  The 
cytoplasm  is  slightly  granular.  Hsiung 
(1930)  found  this  species  in  the  cecum  of  9 
out  of  46  horses  in  Iowa. 


FAMILY   BLEPHAROCORYTHIDAE 

In  this  holotrichasin,  trichostomorid 
family,  somatic  ciliation  is  reduced  to  a 
few  anterior  and  posterior  fields,  with  1  or 
2  groups  of  anal  cilia  near  the  cytopyge 
and  2  or  3  distinct  anterior  groups.    The 
cytostome  is  anteroventral,  and  opens  into 
a  long,  ciliated  cytopharynx. 


Genus  BLEPHAROCORYS 
Bundle,  1895 

There  are  3  (oral,  dorsal  and  ventral) 
ciliary  zones  at  the  anterior  end  and  1 
caudal  ciliary  zone.    There  is  a  deep  oral 
groove  near  the  anterior  end. 


THE  CILIATES 


367 


Blepharocorys  uncinata  (Fiorentini, 
1890)  Bundle,   1895  is  elongated  and  ir- 
regular in  shape,  with  a  slightly  convex 
dorsal  side,  a  slightly  concave  ventral 
side  and  more  or  less  rounded  ends;  it 
measures  55  to  74  by  22  to  30  jj,.     A  cork- 
screw-like anterior  process  which  makes 
2  turns  projects  from  the  anterior  end  and 
also  passes  thru  the  body  dorsal  to  the 
cytopharynx,  ending  just  behind  it.    There 
is  a  large,  ciliated  vestibule  at  the  anter- 
ior end  which  leads  to  a  cytostome  opening 
into  a  ciliated  cytopharynx  which  extends 
dorso-posteriad  and  then  bends  sharply 
ventrad  and  disappears  at  the  posterior 
half  of  the  body.     The  macronucleus  is 
heart-shaped.    There  is  a  single  posterior 
contractile  vacuole.    Hsiung  (1930)  found 
this  species  in  the  cecum  of  21  and  the 
colon  of  4  out  of  46  horses  in  Iowa. 

B.   valvata  (Fiorentini,   1890)  Bundle, 
1895  is  more  or  less  elliptical  and  flat- 
tened bilaterally.    It  measures  52  to  68  by 
20  to  27jLi.    The  vestibule  is  small  and 
has  a  beak-like  dorsal  plate.    The  macro- 
nucleus  is  more  or  less  kidney- shaped. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  1  and  the  colon  of  4  out  of  46 
horses  in  Iowa. 

B.  jubata  Bundle,   1895  resembles 
B.  valvata,    but  the  dorsal  plate  guarding 
the  vestibule  has  2  teeth.    It  measures  33 
to  60  by  17  to  23  |i  .    The  C3d;opharynx  ex- 
tends backward  and  upward  and  then  again 
turns  backward.    The  macronucleus  is 
more  or  less  ovoid.    Hsiung  (1930)  found 
this  species  in  the  cecum  of  22  and  the 
colon  of  4  out  of  46  horses  in  Iowa. 

B.  curvigula  Gassovsky,  1919  also 
resembles  B.  valvata,   but  its  dorsal  plate 
is  more  or  less  rhomboid.    The  long  cyto- 
pharynx extends  backward  and  upward, 
and  finally  bends  in  a  smooth,  180°  curve. 
The  macronucleus  is  more  or  less  ovoid. 
Hsiung  (1930)  found  this  species  in  the 
colon  of  12  out  of  46  horses  in  Iowa. 

B.  angiista  Gassovsky,  1919  resembles 
B.  valvata,   but  is  more  elongate,  meas- 
uring 58  to  78  by  20  to  25  )j, .    The  dorsal 
plate  is  more  or  less  rhomboid.    The  ma- 
cronucleus is  irregular.    Hsiung  (1930) 


found  this  species  in  the  colon  of  8  out  of 
46  horses  in  Iowa. 


B.  cardionucleata  Hsiung,   1930  re- 
sembles B.  curvigula,   but  its  macronu- 
cleus is  heart-shaped,  with  an  anterior 
base  and  a  posterior  apex.    It  measures 
48  to  62  by  17  to  23  fi.     Hsiung  (1930) 
found  it  in  the  colon  of  1  out  of  46  horses 
in  Iowa. 


Genus  CHARONINA  Strand,   1928 

There  are  2  caudal  and  3  anterior 
ciliary  zones,  and  an  anterior  knob  is 
present  on  the  body.    This  genus  was  or- 
iginally named  Charon  by  Jameson  (1925), 
but  this  name  is  a  homonym  (Corliss, 
1960). 

Cliaronina  equi  (Hsiung,   1930)  Strand, 
1928  is  lanceolate  and  measures  30  to  48 
by  10  to  14  fi.    The  cytostome  occupies 
nearly  the  whole  ventral  side  of  the  anter- 
ior knob  and  leads  to  a  prominent  cyto- 
pharynx which  extends  straight  down  to 
the  middle  third  of  the  body.    The  macro- 
nucleus  is  large  and  elongate.    Hsiung 
(1930)  found  this  species  in  the  colon  of  3 
out  of  46  horses  in  Iowa. 


Genus  OCHOTERENAIA 
Chavarria,  1933 

There  are  3  ciliary  zones  at  the  an- 
terior end  and  2  at  the  posterior  end.    One 
of  the  latter  is  borne  on  a  caudal  appendage 
which  arises  ventral  to  the  cytopyge.    There 
is  a  beak-like  dorsal  plate  like  that  of 
Blepharocorys. 

Ochoterenaia  appendiculata  Chavarria, 
1933  is  more  or  less  elliptical  and  is  flat- 
tened bilaterally.    It  measures  58  to  72  by 
24  to  33  jn  with  a  mean  of  66  by  28  ^ .    The 
vestibule  is  prominent.    The  macronucleus 
is  more  or  less  kidney-shaped.    Chavarria 
(1933a)  found  this  species  in  the  rectum  of 
horses  in  Mexico. 


368 


THE  CILIATES 


FAMILY   PARAISOTRICHIDAE 

In  this  holotrichasin,  trichostomorid 
family,  somatic  ciliation  is  complete, 
and  there  is  an  anterior  tuft  of  longer 
cilia.     The  mouth  is  subterminal,  opening 
just  posterior  to  the  concretion  vacuole. 

Genus  PARAISOTRICHA 
Fiorentini,    1890 

The  cilia  form  more  or  less  spiral 
longitudinal  rows.    The  contractile  vac- 
uole is  posterior. 

Paraisolriclui  colpoidea  Fiorentini, 
1890  is  ovoid,  measures  70  to  100  by  42 
to  60  fi  and  has  34  to  40  rows  of  cilia. 
The  macronucleus  is  a  thick,  ellipsoidal 
disc.     There  is  a  large  concretion  vacuole 
at  the  anterior  end.     Hsiung  (1930)  found 
this  species  in  the  cecum  of  21  and  the 
colon  of  6  out  of  46  horses  in  Iowa. 


of  a  retractile,  conical  elevation  at  the 
anterior  end.    The  adoral  zone  of  mem- 
branelles  is  conspicuous.    There  are  open 
ring  zones  of  membranelles  near  the  pos- 
terior end  on  the  dorsal  and  ventral  sides. 
The  pellicle  is  ridged.     There  is  a  club- 
shaped  skeletal  plate.    A  row  of  several 
contractile  vacuoles  runs  along  the  band- 
formed  macronucleus. 

Cycloposthiio)!  bipalniatiim  (Fiorentini, 
1890)  Bundle,   1895  is  more  or  less  rec- 
tangular, slightly  compressed  laterally, 
with  a  truncate  anterior  end  and  a  tapering 
posterior  end  with  a  tail-like  structure. 
It  measures  80  to  127  by  35  to  57  ju  .    A 
longitudinal  groove  and  a  light,  linear 
skeletal  plate  are  present  on  the  left  side. 
The  macronucleus  is  hooked  anteriorly, 
and  the  micronucleus  is  located  near  its 
middle.    There  are  4  contractile  vacuoles. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  38  and  the  colon  of  8  out  of  46 
horses  in  Iowa. 


P.  beckeri  Hsiung,   1930  resembles 
P.  colpoidea   but  has  only  11  rows  of  cilia. 
It  measures  52  to  98  by  30  to  52  fj,.     Hsiung 
(1930)  found  it  in  the  cecum  of  8  and  the 
colon  of  1  out  of  46  horses  in  Iowa. 

P.  minuta   Hsiung,   1930  resembles 
P.  colpoidea  but  has  only  20  rows  of  cilia 
and  measures  38  to  68  by  27  to  36  |i. 
Hsiung  (1930)  found  it  in  the  cecum  of  31 
and  the  colon  of  3  out  of  46  horses  in  Iowa. 


C.  dentifenoii  Gassovsky,  1919  meas- 
ures 140  to  220  by  80  to  110  (n.    It  resem- 
bles C.  bipahnatiim  but  has  a  ventral 
dentiform  projection,  and  the  anterior  end 
of  its  macronucleus  is  not  hooked.    The 
cuticle  is  not  corrugated.    A  longitudinal 
groove  is  present  on  the  left  side,  but  the 
linear  skeletal  plate  is  quite  indistinct. 
There  are  4  to  6  contractile  vacuoles. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  16  and  the  colon  of  2  out  of  46 
horses  in  Iowa. 


FAMILY   CYCLOPOSTHIIDAE 

This  spirotrichasin,  entodiniorid 
family  differs  from  the  related  Ophryo- 
scolecidae  in  that  its  members  have  2  or 
more  bands  of  membranelles  in  addition 
to  the  adoral  zone,  instead  of  1.    Most 
members  of  this  family  occur  in  equids, 
but  others  occur  in  tapirs,  rhinoceroses 
and  elephants,  which  are  related  to  them. 
One  genus  occurs  in  anthropoid  apes. 

Genus  CYCLOPOSTHIUM 
Bundle,   1895 

The  body  is  large  and  elongate  barrel - 
shaped.    The  cytostome  is  in  the  center 


C.  ishikaivai  Gassovsky,  1919  differs 
from  all  other  species  of  the  genus  in  that 
the  posterior  arches  of  membranelles  are 
nonretractile.    It  measures  230  to  280  by 
110  to  130 fj,.     Hsiung  (1930)  did  not  find 
it  in  Iowa  horses. 

C.  edentatum  Strelkov,  1928  resem- 
bles C.  bipalniatum  but  has  6  to  7  con- 
tractile vacuoles.    It  measures  146  to  230 
by  68  to  93):i .     Hsiung  (1930)  found  this 
species  in  the  cecum  of  11  and  the  colon 
of  2  out  of  46  horses  in  Iowa. 

C.  piscicauda  Strelkov,  1928  resem- 
bles C.  bipalmatii»i  but  lacks  both  the 
longitudinal  groove  and  skeletal  plate  on 
the  left  side.    It  measures  125  to  190  by 


THE   CILIATES 


369 


Fig.  41.      Ciliates  of  equids.     A.    Cycloposthium  bipalmatum.    B.    Cycloposthiiim  scuti- 
genini.     C.    Cy'cloposthium  edentatum.    D.   Spirodinium  equi.     E.     Tetratoxum 
unifasciculatum .     F.     Tripalmaria  dogieli.    G.     Triadiniuin  galea.    H.     Tri- 
adiniu))i  minimum.    I.    Triadinium  caudatum.    J.    Tetratoxum  excavatum. 
K.    Tetratoxum  parvum .    L.    Ditoxum  funinucleum.     M.    Cochliatoxum  peri- 
achtum.     X  340.     (From  Hsiung,   1930,  in  Iowa  State  College  Journal  of  Science, 
published  by  Iowa  State  Univ.  Press) 


370 


THE  CILIA TES 


44  to  80/1.    It  has  4  or  5  contractile  vac- 
uoles.   Its  posterior  end  forms  a  tail  re- 
sembling that  of  a  fish.     Hsiung  (1930) 
did  not  find  this  species  in  Iowa  horses. 

C.  scutigerum  Strelkov,   1928  differs 
from  C.  bipalmatuni  in  having  a  shield- 
like skeletal  plate  interrupted  by  2  longi- 
tudinal grooves  on  the  left  side  instead  of 
a  simple,  narrow  plate.    It  measures  132 
to  210  by  63  to  90pt  and  has  5  or  6  con- 
tractile vacuoles.     Hsiung  (1930) found 
this  species  in  the  cecum  of  24  and  the 
colon  of  4  out  of  46  horses  in  Iowa. 

C.  affinae  Strelkov,  1928  differs  from 
C.  bipalmatuni  in  having  a  heavy  skeletal 
plate  and  in  that  the  micronucleus  is  near 
the  anterior  end  of  the  macronucleus.    It 
measures  92  to  141  by  45  to  58  ji.     Hsiung 
(1930)  found  this  species  in  the  cecum  of 
3  and  the  colon  of  1  out  of  46  horses  in 
Iowa. 

C.  corrugatum  Hsiung,  1930  meas- 
ures 135  to  195  by  70  to  112(x.    It  has  a 
ventral  dentiform  projection,  and  its  cu- 
ticle is  corrugated.    The  anterior  end  of 
its  macronucleus  is  not  hooked.    The 
linear  skeletal  plate  is  quite  indistinct. 
There  are  4  or  5  contractile  vacuoles. 
Hsiung  (1930)  found  this  species  in  the 
cecum  of  7  and  the  colon  of  1  out  of  46 
horses  in  Iowa. 


Genus  SPIRODINIUM  Fiorentini,  1890 

The  body  is  elongate  and  more  or 
less  fusiform,  with  an  adoral  zone  of  mem- 
branelles  at  the  anterior  end.    An  anterior 
ciliary  zone  encircles  the  body  at  least 
once,  and  a  posterior  ciliary  arch  spirals 
half-way  around  the  body.    There  is  a 
dorsal  cavity  of  unknown  function  lined 
with  stiff  rods. 

Spirodinium  equi  Fiorentini,   1890 
measures  77  to  180  by  30  to  74 p..    Its 
macronucleus  is  elongated,  with  rounded 
ends.    There  is  a  large  contractile  vac- 
uole just  back  of  the  anterior  membran- 
elles.    Hsiung  (1930)  found  this  species  in 
the  colon  of  3  out  of  46  horses  in  Iowa. 


Genus  TftlADINIUM  Fiorentini,  1890 

The  body  is  more  or  less  helmet- 
shaped  and  compressed,  with  an  adoral 
zone  of  membranelles  at  the  anterior  end. 
There  are  ventral  and  dorsal  posterior 
zones  of  membranelles.    There  may  or 
may  not  be  a  caudal  projection. 

Triadinium  caudalum  Fiorentini,  1890 
measures  50  to  105  by  36  to  85 ;j  and  has 
a  long,  slender  tail.    The  macronucleus 
is  bent  like  a  question-mark.    There  is  a 
single  contractile  vacuole.    Hsiung  (1930) 
found  this  species  in  the  colon  of  3  out  of 
46  horses  in  Iowa. 

T.  galea  Gassovsky ,  1919  measures 
58  to  88  by  50  to  70  fi  and  lacks  a  tail.    It 
has  a  long  macronucleus  running  longi- 
tudinally along  the  left  surface,  and  2  con- 
tractile vacuoles.    Hsiung  (1930)  found 
this  species  in  the  colon  of  3  out  of  46 
horses  in  Iowa. 

T.  mmimum  Gassovsky,  1919  meas- 
ures 32  to  50  by  31  to  42  ji  and  has  a  slen- 
der tail.    The  macronucleus  is  ellipsoidal. 
There  is  a  single  contractile  vacuole. 
Hsiung  (1930)  found  this  species  in  the 
colon  of  2  out  of  46  horses  in  Iowa. 


Genus  TETRATOXUM 
Gassovsky,   1919 

The  body  is  slightly  compressed  and 
has  2  anterior  and  2  posterior  zones  of 
membranelles. 

Tetratoxum  unifasciculatum  (Fioren- 
tini, 1890)  Gassovsky,  1919  measures  104 
to  168  by  62  to  100  fi .    It  is  irregularly 
elliptical,  with  both  ends  rounded,  and  has 
7  to  9  longitudinal,  cuticular  ridges  on 
both  the  dorsal  and  ventral  surfaces  of  the 
body.    Lateral  cuticular  extensions  at  the 
posterior  end  form  2  caudal  sheaths.    The 
macronucleus  is  elongate,  with  a  short 
hook  at  the  anterior  end.    There  is  a  large 
contractile  vacuole  under  its  curvature. 
Hsiung  (1930)  found  this  species  in  the 
colon  of  2  out  of  46  horses  in  Iowa. 


THE  CILIATES 


371 


T.   excavatimi  Hsiung,   1930  measures 
95  to  135  by  55  to  90 jLt.    It  differs  from 
T.  unifasciculatum  in  having  a  deep  ellip- 
tical excavation  covered  by  a  flap  of  cuti- 
cle at  its  anterior  end,  and  its  cuticular 
ridges  are  more  prominent  and  the  adja- 
cent ones  further  apart.    Hsiung  (1930) 
found  this  species  in  the  colon  of  1  out  of 
46  horses  in  Iowa. 

T.  parvum  Hsiung,  1930  measures 
67  to  98  by  39  to  52  |Lt .    It  differs  from  the 
other  2  species  in  lacking  longitudinal 
cuticular  ridges.    Hsiung  (1930)  found  this 
species  in  the  colon  of  1  out  of  46  horses 
in  Iowa. 


Genus  DITOXUM  Gassovsky,  1919 

There  is  a  large  adoral  zone  of  mem- 
branelles  near  the  anterior  end  and  also 
anterodorsal  and  posterodorsal  zones  of 
membranelles.    The  macronucleus  is 
curved  and  club-shaped. 

Ditoxuni  fiinimicleum  Gassovsky,  1919 
is  elliptical  with  both  ends  rounded, 
slightly  flattened  bilaterally,  and  measures 
135  to  203  by  70  to  101  jm  .    It  has  a  single 
contractile  vacuole.    Hsiung  (1930)  found 
this  species  in  the  colon  of  2  out  of  46 
horses  in  Iowa. 


Genus  TRIPALMAMA 
Gassovsky,  1919 

There  is  an  adoral  zone  of  membran- 
elles at  the  anterior  end  and  also  2  dorsal 
and  1  ventroposterior  tuft-formed  zones 
of  membranelles.    The  macronucleus  is 
shaped  like  an  inverted  U.    A  synonym  of 
this  genus  is  Tricaudalla  Buisson,  1923. 

Tripalmaria  dogieli  Gassovsky,  1919 
measures  77  to  123  by  47  to  62|i.    Beneath 
the  right  side  it  has  skeletal  plates  form- 
ing a  horseshoe  with  its  open  end  directed 
posteriad.    Hsiung  (1930)  found  this  spe- 
cies in  the  colon  of  3  out  of  46  horses  in 
Iowa. 


C.   OTHER   CILIATES 
FAMILY   BALANTIDIIDAE 

This  holotrichasin,  trichostomorid 
family  was  once  considered  to  belong  in 
the  Heterotrichorida;  Faure-Fremiet 
(1955)  showed  its  proper  position.    Cilia 
are  arranged  in  longitudinal  rows  over  the 
whole  body.    The  peristome  forms  a  pouch 
with  a  triangular  opening  containing  a 
short  adoral  zone  of  membranelles.    There 
is  no  concretion  vacuole. 

Genus  BALANTIDIUM 
Claparede  and  Lachmann,  1858 


Genus  COCHLfATOXUM 
Gassovsky,    1919 

There  is  an  adoral  zone  of  membran- 
elles at  the  anterior  end  and  also  1  anter- 
odorsal, 1  posterodorsal  and  1  postero- 
ventral  zone  of  membranelles.    The 
anterior  end  of  the  macronucleus  is 
curved. 

Cochliatoxum  periachtum  Gassovsky, 
1919  is  more  or  less  cylindrical,  with 
both  ends  rounded,  and  measures  210  to 
370  by  130  to  210fi.    There  is  a  contrac- 
tile vacuole.    Hsiung  (1930)  found  this 
species  in  the  colon  of  1  out  of  46  horses 
in  Iowa. 


The  body  is  ovoid,  ellipsoid  to  sub- 
cylindrical.    The  macronucleus  is  elon- 
gated.   There  is  a  single  micronucleus. 
The  contractile  vacuole  and  cytopyge  are 
terminal. 

Many  species  of  Balantidium  have 
been  named,  based  on  the  host  in  which 
they  occur  and  on  the  size  and  shape  of 
their  body  and  macronucleus  (cf.  Hegner, 
1934;  Kudo  and  Meglitsch,  1938).    How- 
ever, many  of  these  are  probably  not 
valid.    For  instance,  McDonald  (1922) 
separated  B.  suis  from  B.  coli,    both  from 
swine,  on  the  basis  of  its  slenderer  body 
and  straighter  macronucleus,  but  Levine 
(1940,  1940a)  showed  that  Balantidium 
from  swine  changed  dimensions  upon 


372 


THE  CILIATES 


cultivation,  and  that  a  single  strain  could 
resemble  B.  cull  if  it  was  full-fed  and 
B.  sids  if  it  was  starved.     Lamy  and  Roux 
(1950)  found  boths///s  and  col i  forms  in 
clone  cultures  started  from  single  organ- 
isms and  considered  the  siiis  forms  to  be 
conjugants  and  the  culi  forms  trophozoites. 
Auerbach  (1953)  concluded  from  his  cyto- 
logical  and  cultural  studies  that  the  2 
forms  were  not  different  species. 

BALANTIDIUM  CO  LI 
(MALMSTEN,   1857) 
STEIN,   1862 

Synonym:     Balantidiwn  suis. 

Disease:     Balantidiosis,  balantidial 
dysentery. 

Hosts:     Pig,  man,  chimpanzee, 
orang-utan,   rhesus  monkey,  cynomolgus 
monkey,  other  macaques,  rarely  dog  and 
rat. 

Location:     Cecum,  colon. 

Geographic  Distribution:     Worldwide. 

Prevalence:     B.  coli  is  extremely 
common  in  swine,  having  been  reported 
in  21  to  100%  of  them  in  various  surveys 
(Kennedy  and  Stewart,   1957),  but  the 
lower  figures  may  reflect  the  examination 
technic  rather  than  the  true  incidence 
(de  Carneri,   1958).    It  is  much  less  com- 
mon in  man,  its  incidence  in  12  surveys 
comprising  24,  837  fecal  specimens  thru- 
out  the  world  being  0.  77%  according  to 
Belding  (1952).    Shookhoff  (1951)  found  it 
in  0.6%  of  approximately  3000  Puerto 
Rican  patients.    Swartzwelder  (1950)  des- 
cribed 16  human  cases  in  New  Orleans; 
these  represented  more  than  1/4  of  all  the 
available  reports  in  the  United  States. 

B.  coli  occurs  in  primates  other  than 
man,  but  is  not  common.    Habermann  and 
Williams  (1957)  found  it  at  postmortem 
examination  of  5  of  615  rhesus  monkeys 
obtained  by  the  National  Institutes  of  Health 
from  various  importers;  the  animals  had 
died  of  various  diseases.     They  did  not  find 
it  in  93  cynomolgus  monkeys  {Macaca  phil- 
ippinensis).    Cockburn  (1948)  described  an 


epidemic  of  enteritis  among  the  larger 
primates  at  the  London  Zoo  which  appeared 
to  be  due  to  Balanlidiiim.     Benson,   Frem- 
ming  and  Young  (1955)  reported  it  in  cap- 
tive chimpanzees. 

Balantidiu})i  has  been  seen  on  rare 
occasions  in  the  dog.    Dikmans  (1948)  re- 
ported a  case  in  a  dog  in  North  Carolina. 
Bailey  and  Williams  (1949)  reported  one 
from  Tennessee,  and  Hayes  and  Jordan 
(1956)  reported  one  from  Georgia. 

Bogdanovich  (1955)  found  B.  coli  in  6 
out  of  1 50  Norway  rats  in  a  Russian  slaugh- 
ter house. 

"Balantidiiim  coli"  has  been  reported 
from  the  zebu  (Cooper  and  Gulati,   1926) 
and  water  buffalo  (Priestley,   1944),  but 
Lubinsky  (1957)  considered  it  to  be  a  late 
exconjugant  of  Biixtonella  sulcata,  which 
he  had  found  commonly  in  the  zebu.    The 
longitudinal  furrow  is  inconspicuous  in 
this  stage  and  is  easily  overlooked. 


Fig.  42.      Balanlidium  coli.     A.    Living 

trophozoite.     B.    Stained  tropho- 
zoite.   C.   Fresh  cyst.    D.  Stained 
cyst.    X  450.     (From  Kudo,  R.  R.  , 
PROTOZOOLOGY  4th  Ed.  ,   1954. 
Courtesy  of  Charles  C  Thomas, 
Publisher,  Springfield,  Illinois) 

Morphology:     The  trophozoites  are 
ovoid,  with  a  subterminal  cytostome  at  the 
smaller  end,  and  measure  30  to  150  by  25 


THE   CILIATES 


373 


to  120|Li.  The  cytopyge  is  near  the  poster- 
ior end.    The  macronucleus  is  sausage- 
or  kidney-shaped,  and  the  micronucleus 
lies  near  the  center  of  1  side.    There  are 
2  contractile  vacuoles,  1  terminal  and  the 
other  near  the  center  of  the  body.     There 
are  many  food  vacuoles  containing  starch 
grains,  cell  fragments,  bacteria,  erythro- 
cytes, etc. ;  starch  is  the  most  important 
food.     The  surface  is  covered  by  slightly 
oblique  longitudinal  rows  of  cilia. 

Krascheninnikow  and  Wenrich  (1958) 
studied  the  morphology  and  division  of 
B.  coli  in  detail.    Auerbach  (1953),  Sen 
Gupta  and  Ray  (1955)  and  Lom  (1955)  re- 
ported on  cytologic  and  C3^ochemical 
studies. 

The  cysts  are  spherical  to  ovoid  and 
measure  40  to  60 |i  in  diameter.     They 
are  slightly  yellowish  or  greenish,  with 
hyaline  cytoplasm.    The  cyst  wall  is  com- 
posed of  2  membranes. 

Life  Cycle:      B.  coli  reproduces  by 
transverse  binary  fission  (Krascheninni- 
kow and  Wenrich,  1958).    Conjugation 
also  takes  place  (Nelson,  1934;  Svensson, 
1955),  and  resistant  cysts  are  formed. 

Pathogenesis:     In  the  pig,  Balanti- 
dium  coli  is  ordinarily  a  commensal  in  the 
lumen  of  the  large  intestine,  where  it  lives 
on  starcn,  other  ingesta  and  bacteria.    It 
does  not  seem  able  to  penetrate  the  intact 
intestinal  mucosa  by  itself.    Enormous 
numbers  of  Balaiitidiimi  may  be  found  in 
the  lumen  of  the  cecum  of  pigs  with  normal 
cecal  mucosae.    However,  once  some  other 
organism  or  condition  has  initiated  a  lesion, 
Balantidium  may  be  a  secondary  invader 
and  may  be  found  deep  in  the  ulcer.    It  pro- 
duces hyaluronidase  (Tempelis  and  Ly- 
senko,  1957),  which  might  help  it  to  en- 
large the  lesions  by  attacking  the  ground 
substance  between  the  cells,  altho  it  would 
not  help  it  to  initiate  the  lesions. 

Balantidium  is  pathogenic  in  man  and 
other  primates.    It  causes  diarrhea  or 
dysentery,  and  produces  undermining 
lesions  similar  to  those  caused  by  Enta- 
moeba histolytica.     The  protozoa  may  be 
found  down  to  the  muscularis  mucosae, 


the  ulcers  are  infiltrated  with  round  cells, 
and  coagulation  necrosis  and  hemorrhagic 
areas  may  be  present.    The  protozoa 
often  occur  in  nests  within  the  tissues  or 
even  in  the  capillaries,  lymph  ducts  and 
neighboring  lymph  nodes.     The  lesions  in 
the  pig  and  other  animals  are  similar. 
The  disease  in  man  has  been  reviewed  by 
Swartzwelder  (1950),  Shookhoff  (1951)  and 
Arean  and  Koppisch  (1956). 

The  infected  dog  described  by  Dikmans 
(1948)  died  of  a  severe  diarrheal  disease, 
and  ulcers  were  found  in  the  intestine  at 
necropsy.    In  the  case  reported  by  Bailey 
and  Williams  (1949),  the  animal  had  dysen- 
tery for  several  days  beginning  several 
days  after  it  ate  the  intestines  of  a  hog, 
but  it  recovered. 

Lesions  in  the  ceca  of  some  naturally 
infected  rats  were  described  by  Bogdanovich 
(1955). 

Bionomics  and  Epidemiology:     Balan- 
tidium may  be  transmitted  by  ingestion  of 
either  cysts  or  trophozoites.    The  cysts 
are  more  resistant  to  environmental  con- 
ditions.   Svensson  (1955)  found  that  the 
trophozoites  of  different  strains  of  B.  coli 
from  the  pig  differ  in  their  resistance  to 
heat  and  cooling.    Most  strains  survive 
heating  to  47°  C  for  more  than  15  minutes 
but  survive  at  room  temperature  for  less 
than  3  days.    A  cold-resistant  strain  sur- 
vived heating  for  only  5  to  10  minutes,  but 
remained  alive  at  room  temperature  for 
5  days  or  more.    B.  coli  from  man  is 
similar  to  the  latter.    The  cysts  may  re- 
main alive  for  weeks  in  pig  feces  if  they 
do  not  dry  out. 

The  pig  is  the  usual  source  of  infection 
for  man.    Contact  with  swine  has  been 
noted  in  more  than  half  the  human  cases 
reported  (Arean  and  Xoppisch,  1956),  and 
Shookhoof  (1951)  obtained  a  history  of  close 
contact  with  pigs  in  practically  all  the  cases 
he  observed  in  Puerto  Rico. 

Chimpanzees  and  other  primates  ap- 
pear to  have  their  own  infection  pool. 

Diagnosis:     Balantidium  can  be  easily 
recognized  by  microscopic  examination  of 


374 


THE  CILIA TES 


intestinal  contents  or  by  histologic  exam- 
ination of  intestinal  lesions. 

Cultivation:     B.  coli  was  first  cul- 
tivated by  Barret  and  Yarbrough  (1922)  in 
a  medium  consisting  of  1  part  inactivated 
serum  and  16  parts  of  0.  5%  sodium  chlor- 
ide solution.    It  has  since  been  cultivated 
by  many  workers.    Schumaker  (1931)  and 
Levine  (1940)  used  a  medium  consisting 
of  9  parts  of  Ringer's  solution  and  1  part 
of  horse  serum  plus  about  0.007  g  rice 
starch  per  tube  containing  10  ml  of  the 
medium.     Tempelis  and  Lysenko  (1957) 
used  an  agar  slant  of  Difco  Eutamueba 
histolytica  medium  overlaid  with  Bala- 
muth's  egg  yolk  infusion  plus  rice  starch, 
500  units  per  ml  of  streptomycin  and  250 
units  per  ml  of  penicillin;  this  medium 
was  used  successfully  to  establish  clone 
cultures  from  single  microorganisms. 

Treatment:     No  treatment  is  neces- 
sary in  swine.    Carbarsone  has  been  used 
in  man.    Young  and  Burrows  (1943)  ad- 
ministered 0.  25  to  0.  5  g  twice  a  day  for 
10  days.     However,  DeLanney  (1943)  found 
that  carbarsone  did  not  eliminate  all  the 
parasites  and  recommended  2.1  g  diiodo- 
hydroxyquin  (diodoquin)  daily  for  20  days. 
Swartzwelder  (1950)  recommended  diodo- 
quin if  carbarsone  failed.    More  recently, 
chlortetracycline  and  oxytetracycline  have 
been  found  effective  (Arean  and  Koppisch, 
1956;  Neghme  el  al. ,   1951). 

Benson,  Fremming  and  Young  (1955) 
treated  chimpanzees  with  250  mg  carbar- 
sone daily  for  10  days,  concealing  the 
drug  in  fruit  or  fruit  juices. 

Prevention  and  Control:     Sanitary 
measures  designed  to  prevent  ingestion  of 
cysts  or  feces  should  prevent  balantidial 
infections. 


FAMILY   TETRAHYMENIDAE 

In  this  holotrichasin,  hymenostomorid 
family,  the  buccal  ciliature  is  composed  of 
3  membranelles  which  lie  to  the  left  in  the 
buccal  cavity  and  a  fourth,  paroral  mem- 
brane extending  along  its  right  margin. 
One  or  more  stomatogenous  rows  of  cilia 


end  at  the  posterior  margin  of  the  buccal 
pouch. 


Genus  TETRAHYMENA  Furgason,  1940 

The  body  is  piriform  and  uniformly 
ciliated  with  17  to  42  rows  of  cilia.    The 
piriform  cytostome  is  near  the  anterior 
end.    There  is  a  single  contractile  vacuole. 

Telrahymena  pyriforniis  (Ehrenberg, 
1830)  Lwoff,   1947  (syn.,    T.geleii)  meas- 
ures 40  to  60  by  15  to  30j:i  .    It  is  extremely 
popular  in  protozoological  research.    Ac- 
cording to  Corliss  (1954,   1957a),  over 
500  papers  had  been  written  on  it  and  other 
members  of  the  genus  up  to  1954,  and  an- 
other 186  papers  were  published  in  1954 
thru  1956.     Altho  T.  pyriforniis  is  nor- 
mally free-living,  it  may  on  rare  occa- 
sions be  a  facultative  parasite.    Knight  and 
McDougle  (1944)  found  it  in  the  digestive 
tract,  infraorbital  sinuses  and  serous 
material  under  the  eyelids  of  chickens  in 
Missouri.    It  was  found  only  in  birds  with 
a  vitamin  A  deficiency. 

Thompson  (1958)  infected  chicken  em- 
bryos with  T.  pyriforniis ,   T.  corlissi  and 
T.  vorax.    He  also  infected  guppies 
(Lebisles  reliculalus)  and  tadpoles  {Rana 
paluslris)  thru  artificially  produced  wounds 
with  T.  corlissi  but  not  with  the  other  spe- 
cies.   Various  adult  and  larval  insects 
proved  excellent  hosts,  the  protozoa  teem- 
ing in  the  hemolymph  of  some  of  them. 


D.   COPROPHILIC  CILIATES 

A  number  of  ciliates  which  live  in 
water  or  soil  may  contaminate  feces  and 
develop  coprophilically.    They  are  com- 
mon in  old  feces,  especially  if  it  has  been 
in  contact  with  the  ground,  but  may  also 
appear  in  feces  taken  directly  from  an 
animal.    Cysts  ingested  by  livestock  in 
feeding  or  drinking  may  pass  thru  the  in- 
testinal tract  unharmed,  and  trophozoites 
may  emerge  and  develop  as  the  feces 
stands.    Horse  and  ruminant  feces  which 
have  been  cultured  for  nematode  larvae 
often  contain  large  numbers  of  small  cil- 
iates.   Some  of  these  are  probably  Colpi- 
dium,  Chilodonella  and  Cyclidium. 


THE   CILIATES 


375 


Nyclotlierns  faba  Schaudinn,   1899  has 
been  found  in  human  feces  on  occasion 
(Wichterman,   1938).    It  belongs  to  the 
heterotrichorid  family  Plagiotomidae.    Its 
body  is  reniform,  covered  with  cilia,   and 
26  to  23  (i  long.     The  peristome  begins  at 
the  anterior  end,  turns  slightly  to  the 
right  and  ends  in  the  cytostome  at  the 
middle  of  the  body.     The  cytopharynx  is  a 
long  tube  and  contains  an  undulating  mem- 
brane.    The  macronucleus  is  about  the 
middle  of  the  body.     It  is  spherical,  and 
its  chromatin  is  arranged  in  4  or  5  large, 
solid  bodies  on  the  nuclear  membrane, 
while  the  remainder  of  the  nucleus  is 
chromatin-free. 

Noble  (1958)  found  that  a  Nye  tot  lie  nis- 
like  ciliate  about  15  to  30 )n  long  appeared 
in  fecal  samples  from  Wyoming  sheep  and 
elk  after  storage  at  4°  C  for  about  30  days. 
A  smaller  ciliate  about  10  to  12/i  long 
also  appeared  in  the  elk  feces  at  about  the 
same  time.     The  smaller  ciliates  per- 
sisted for  a  few  weeks  and  the  Nyctotlienis- 
like  ones  for  about  twice  as  long. 

Balaiitiopliorus  iiiiimtus  Schewiakoff, 
1893  (syn.  ,  BalaiitidiuDi  niiiiiitioii  Schaudinn) 
occurs  occasionally  in  contaminated  human 
feces  (Watson,   1940,   1945,   1945a).    It  be- 
ongs  to  the  holotrichorid  family  Pleuro- 
nemidae.     It  is  ovoid,  with  the  narrow  end 
anterior  and  with  the  anterior  end  bent 
ventrad,  giving  the  ventral  surface  a  hol- 
lowed appearance.    It  measures  12  to  54 
by  7  to  33 in,  but  is  usually  25  to  45/i  long. 
The  peristome  is  in  the  middle  of  the  an- 
terior half  of  the  body.    The  adoral  zone 
of  membranelles  on  its  left,   posterior  and 
right  borders  forms  a  sac-like  structure 
which  is  conspicuous  when  expanded  but 
which  can  be  retracted  into  the  peristome 
and  become  invisible.     The  cytopharynx  is 
funnel-shaped.   The  body  is  uniformly  cov- 
ered by  12  rows  of  setiform  cilia,  of  which 
only  6  extend  anterior  to  the  peristome. 
The  macronucleus  is  central  and  ellipsoidal. 
There  is  a  posterior  contractile  vacuole. 

The  taxonomy  and  bionomics  of  these 
and  other  coprophilic  protozoa  have  been 
reviewed  by  Alexeieff  (1929)  and  Watson 
(1946).    The  latter  listed  51  species  of 
flagellates,  18  of  amoebae  and  18  of  cili- 


ates which  have  been  found  in  feces, 
many  of  these  need  further  study. 


but 


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Many  different  technics  have  been 
used  for  the  laboratory  diagnosis  of  pro- 
tozoan infections  and  for  the  study  of  para- 
sitic protozoa.     Only  the  commonest  and 
those  which  have  been  found  most  useful 
in  the  author's  laboratory  are  given  here. 
Other  routine  and  specialized  technics  are 
given  by  Craig  (1948),   Hoare  (1949),  Kirby 
(1950),  and  various  textbooks  of  human 
parasitology. 

Some  of  these  technics  are  useful  not 
only  for  protozoa  but  also  for  helminth 
eggs  or  larvae.    If  so,  their  value  for 
these  purposes  is  mentioned. 


Chapter  /4 


DIRECT  MICROSCOPIC 

EXAMINATION  OF  WET 

FECAL  SMEARS 

Place  a  drop  of  physiological  salt  so- 
lution on  a  microscope  slide.    Take  up  a 
small  amount  of  feces  on  the  end  of  a 
toothpick  and  mix  thoroughly  with  the  salt 
solution.    Do  not  make  too  heavy  a  sus- 
pension, or  it  will  be  impossible  to  see 
objects  clearly  under  the  microscope.    An 
emulsion  thru  which  newsprint  can  be  read 
is  about  right.     Place  a  coverslip  on  the 
drop.     Examine  under  the  low  and  high  dry 
powers  of  the  microscope. 

Flagellates  and  ciliates  can  be  seen 
moving  about  actively.    Amoebae  may 
move  sluggishly  or  may  remain  still. 
Oocysts  of  coccidia  and  helminth  eggs  can 
be  recognized  from  their  shape  and  size. 
Many  other  objects  will  be  seen,  some  of 
which  may  be  mistaken  for  protozoan 
parasites.    These  include  bacteria,  yeasts, 
fungus  spores,  the  fungus  Blastocystis, 
pollen  grains,  undigested  food  particles 
such  as  starch  grains  and  plant  fibers, 
and  ingested  pseudoparasites  such  as 
grain  mites  or  coccidian  oocysts  of  ani- 
mals which  have  been  eaten  by  or  have 
defecated  in  the  feed  of  the  animals  under 
examination.    In  cases  of  enteritis,  red 
or  white  blood  cells  or  epithelial  cells 
may  be  present. 


LABORATORY 

DIAGNOSIS 

OF 

PROTOZOAN 

INFECTIONS 


377 


378 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


In  examining  preparations  under  the 
microscope,   move  the  slide  systematic- 
ally back  and  forth  or  up  and  down  in 
order  to  bring  every  part  of  the  prepara- 
tion into  view. 

Iodine  Slaiiii>ig.      In  order  to  bring 
out  certain  details  which  are  not  visible 
in  the  living  protozoon,  wet  smears  may 
be  stained  with  iodine.     Prepare  a  fecal 
suspension  slightly  heavier  than  that  des- 
cribed above,  and  mix  it  with  an  equal 
amount  of  D'Antoni's  aqueous  iodine  solu- 
tion or  of  1  part  of  Lugol's  solution  dilu- 
ted with  4  parts  of  distilled  water. 


DIRECT  MICROSCOPIC 

EXAMINATION  OF 
INTESTINAL  MUCOSA 

This  technic  can  be  used  only  in  ani- 
mals which  have  been  killed  and  have  had 
their  intestinal  tracts  opened.    It  permits 
a  greater  amount  of  material  to  be  exam- 
ined on  a  single  slide  than  does  the  direct 
examination  of  diluted  feces.    It  can  be 
used  to  find  the  intracellular  and  extra- 
cellular stages  of  coccidia,  other  protozoa, 
small  nematodes  such  as  Slrongyloides  and 
Capillaria,  small  trematodes,   cestodes  or 
cestode  scolices,  and  schistosome  eggs. 

Make  a  rather  deep  scraping  of  the 
suspected  intestinal  mucosa  with  a  scalpel, 
toothpick  or  similar  instrument,  or  even 
with  the  end  .of  a  slide.     Place  the  material 
thus  obtained  on  a  microscope  slide  and 
cover  with  a  coverslip.     Press  the  cover- 
slip  down  if  necessary  to  flatten  out  the 
preparation  and  make  it  thin  enough  to  see 
thru. 

To  search  for  Trichomonas,   Giardia, 
Hexamita  and  other  motile  flagellates,  mix 
a  little  physiological  salt  solution  with  the 
scraping  before  placing  the  coverslip  on  it. 


MICROSCOPIC  DIAGNOSIS 
OF   rRITRICIIOMONAS  FOETUS 
INFECTIONS 

In  heavy  infections  of  female  cattle, 
T.  foetus  can  be  found  by  direct  micro- 
scopic examination  of  mucus  or  exudate 


from  the  vagina  or  uterus.    In  aborted 
fetuses  it  can  be  found  in  the  amniotic  or 
allantoic  fluid,  fetal  membranes,   placenta, 
fetus  stomach  contents,  oral  fluid  or  other 
fetal  tissues;  it  occurs  most  commonly  in 
the  stomach  contents  and  the  material 
around  the  base  of  the  tongue.    In  bulls, 
it  can  be  found  in  the  sheath  cavity. 

Clean  the  external  genitalia  thoroughly 
before  taking  samples  in  order  to  avoid 
contamination  with  intestinal  or  copro- 
philic  protozoa.     Take  samples  from  the 
vagina  by  introducing  about  10  ml  of 
physiological  salt  with  a  bulbed  dose 
syringe  and  washing  it  back  and  forth  sev- 
eral times  by  squeezing  the  bulb  repeat- 
edly.    Take  samples  from  the  preputial 
cavity  of  bulls  in  the  same  way,  using  a 
long,  bulbed  pipette  or  syringe,  or  intro- 
duce a  cotton  swab  into  the  cavity  and  rub 
it  around  to  obtain  a  sample  of  exudate; 
in  the  latter  case,  wash  off  the  swab  in 
physiological  salt  solution. 

Allow  the  washings  to  stand  1  to  3 
hours  or  centrifuge  them  before  examina- 
tion.   Place  a  drop  of  the  sediment  on  a 
slide,  cover  with  a  coverslip,  and  exam- 
ine under  the  microscope. 

If  trichomonads  cannot  be  found  on 
direct  microscopic  examination,  inoculate 
some  of  the  washings  into  CPLM,   PGPS 
or  Diamond's  medium,  and  examine  after 
1,  2  and  4  days'  incubation  at  37°  C. 


SPORULATION  OF 
COCCIDIAN  OOCYSTS 

In  order  to  identify  coccidia,  it  is 
often  necessary  to  allow  the  oocysts  to 
sporulate  (i.e.,  to  develop  to  the  infective 
stage).    To  permit  this,  mix  feces  con- 
taining the  coccidia  with  several  volumes 
of  2.  5%  potassium  bichromate  solution  and 
place  the  mixture  in  a  thin  layer  in  a  petri 
dish.     The  potassium  bichromate  prevents 
bacteria  from  destroying  the  oocysts. 
Oxygen  is  necessary  for  the  oocysts  to  de- 
velop, so  the  layer  of  fluid  should  never 
be  more  than  a  few  millimeters  thick.    In 
most  species,   sporocysts  and  sporozoites 
form  in  a  few  days,  but  it  is  well  to  allow 
development  to  proceed  for  a  week  (or, 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN  INFECTIONS 


379 


for  a  few  species,  even  longer).    If  it  is 
not  desired  to  study  the  sporulated  oocysts 
immediately,  the  fecal  suspension  can  be 
transferred  to  a  bottle  and  stored  in  the 
refrigerator.     The  oocysts  will  remain 
alive  for  several  months  or,   in  some  spe- 
cies, as  long  as  a  year. 

It  is  best  to  sporulate  coccidian 
oocysts  before  they  have  been  subjected 
to  refrigeration,   since  in  some  species 
(apparently  a  minority),   refrigeration  of 
the  unsporulated  oocysts  prevents  subse- 
quent sporulation  altho  it  does  not  harm 
sporulated  oocysts. 


MIF  (ME RTfflOLATE -IODINE - 
FORMALDEHYDE)  STAIN- 
PRESERVATION  TECHNIC 

This  technic  was  first  introduced  by 
Sapero,   Lawless  and  Strome  (1951)  and 
improved  by  Sapero  and  Lawless  (1953). 
It  was  designed  especially  to  permit  iden- 
tification of  human  protozoan  trophozoites 
and  cysts,  but  can  also  be  used  for  hel- 
minth eggs  and  for  parasites  of  domestic 
animals.    It  is  simple  and  relatively  cheap, 
permits  rapid  (almost  immediate)  wet- 
fixed  staining  of  the  smears,  and  preserves 
the  parasites  so  that  feces  can  be  collected 
in  the  field  or  by  untrained  persons  and 
shipped  to  the  laboratory  for  later  diag- 
nosis.   There  is  no  appreciable  loss  or 
deterioration  of  parasites  or  cellular 
exudates  for  6  months  or  more. 

A.    Direct  Examination  Technic  for  Fresh 
Fecal  Specimens. 

1.    The  MIF  stain  is  composed  of  tinc- 
ture of  1:1000  merthiolate  No.  99 
(Lilly),   Lugol's  solution  (5%)  and 
40%  formaldehyde  solution  (USP). 
Since  Lugol's  solution  is  unstable, 
it  should  be  freshly  prepared  every 
3  weeks,  and  the  amount  used 
should  be  varied  with  its  age.     The 
following  amounts  (in  ml)  are  rec- 
ommended: 


2.  Place  1  ml  of  the  stain  (sufficient 
for  25  to  30  fecal  smears)  in  a  Kahn 
tube.     Place  some  distilled  water  in 
a  second  tube.     Put  a  small  caliber 
medicine  dropper  in  each  tube. 

3.  Place  1  drop  of  distilled  water  at  1 
end  of  a  slide.  Add  a  drop  of  MIF 
stain.     Mix. 

4.  Add  a  small  amount  of  feces  and  mix. 
Do  not  use  too  much  feces,  or  fixa- 
tion and  staining  will  be  poor.     The 
finished  wet  smear  should  be  thin 
enough  so  that  the  slide  can  be  tipped 
on  edge  without  the  coverslip  sliding. 

5.  Add  a  coverslip  and  examine  at  once. 
If  it  is  desired  to  examine  the  slide 
later,   ring  it  with  petrolatum  to  keep 
the  preparation  from  drying  out. 

B.    Collection  and  Preservation  of  Fecal 
Specimens  in  the  Field  for  Subsequent 
Examination  in  the  Laboratory. 

1.    Prepare  the  following  stock  MF 
solution: 


Tincture  of  merthiolate 

200  ml 

Formaldehyde  solution 

25  ml 

Glycerol 

5  ml 

Distilled  water 

250  ml 

First 

Second 

Third 

Week 

Week 

Week 

Lugol's  solution 

10.0 

12.5 

15.0 

Formaldehyde  solution 

12.5 

12.5 

12.5 

Tincture  of  merthiolate 

77.5 

75.0 

72.5 

Store  in  a  brown  bottle 

2.  Measure  2.  35  ml  MF  solution  into  a 
standard  Kahn  tube  and  stopper  with 
a  cork. 

3.  Measure  0.15  ml  of  5%  Lugol's  so- 
lution into  another  Kahn  tube  and 
close  with  a  rubber  stopper.     (Or 
keep  the  Lugol's  solution  in  a  bottle, 
and  add  the  proper  amount  to  the 
MF  solution  just  before  adding  the 
feces  in  step  4  below. ) 

4.  At  the  time  the  fecal  sample  is  col- 
lected,  pour  the  MF  solution  into 
the  Lugol's  solution.    Within  a  few 
seconds,  add  an  amount  of  feces 
equal  to  2  medium -sized  peas  (about 
0.25  g),  and  mix  thoroughly  with  an 
applicator  stick.    Do  not  use  too 
much  feces.    Stopper  the  tube  and 
set  aside  for  future  examination. 

5.  To  examine,  draw  off  a  drop  of 
mixed  supernatant  fluid  and  feces 
from  the  top  of  the  sedimented  layer 
with  a  medicine  dropper  and  place  on 
a  slide.    Mix  thoroughly,  crushing 
any  large  particles.    Add  a  cover- 
slip  and  examine. 


380 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


PERMANENT   FIXING   AND 
STAINING  TECHNICS 

It  is  often  desirable  to  make  perma- 
nent preparations  of  fecal  smears  or  to 
make  hematoxylin-stained  slides  for  de- 
tailed study.     For  this  purpose,  smears 
must  first  be  fixed,   i.e.,  the  protozoa 
must  be  killed  by  the  action  of  a  chemical 
or  mixture  of  chemicals  which  will  pre- 
serve their  structures  as  nearly  as  pos- 
sible in  the  same  form  as  in  life. 

Many  different  technics  are  used  for 
fixing  and  staining  tissues,  cells  and 
small  organisms.    Those  given  below  are 
especially  suitable  for  protozoa.    The 
standard  hematoxylin  and  eosin  stain  used 
routinely  for  tissue  sections  is  also  valu- 
able for  protozoa  in  tissues,  but  it  is  so 
well  known  that  it  is  not  described  here. 
For  further  information  on  fixing,   sec- 
tioning,  staining  and  mounting  technics, 
any  text  or  reference  book  on  microscopic 
technic  may  be  consulted. 

FIXATION 

Schaudinn's  fluid  is  probably  the  best 
all-round  fixative  for  intestinal  protozoa, 
and  it  also  serves  well  for  other  forms. 
Smears  may  be  made  on  slides  and  stained 
in  Coplin  jars,  or  they  may  be  made  on 
coverslips  and  stained  in  Columbia  jars. 
The  latter  method  has  the  advantages  that 
smaller  amounts  of  reagents  are  necessary, 
a  neater  preparation  is  obtained  (since 
there  is  no  possibility  of  a  portion  of  the 
smear  extending  beyond  the  coverslip), 
and  in  the  completed  slide  the  mounting 
medium  is  beneath  the  smear  rather  than 
above  it,  so  that  the  microscope  objective 
can  come  closer  to  the  smear.    This  fac- 
tor may  be  of  importance  when  the  oil 
immersion  objective  is  used.     Coverslips 
are  fragile,  however,  and  greater  care 
must  be  exercised  in  handling  them  than 
in  handling  slides. 

Clean  the  coverslips  by  dipping  them 
in  95%  alcohol,  and  dry  them  with  a  clean 
cloth  before  use.    Be  careful  to  handle 
them  only  by  the  edges  in  order  not  to 
leave  fingerprints. 


Place  a  tiny  drop  of  albumen  fixative 
in  the  center  of  the  coverslip  (or  slide)  and 
smear  it  over  the  surface  with  the  little 
finger.     (The  finger  should  previously  have 
been  cleaned  and  rid  of  its  oil  by  dipping  it 
in  95%  alcohol  and  wiping  it  with  a  clean 
cloth. )    Albumen  fixative  is  used  to  make 
the  feces  adhere  to  the  glass. 

Take  up  a  small  amount  of  feces  on  a 
toothpick  (preferably  a  round,  smooth  one) 
and  spread  as  evenly  as  possible  in  a  very 
thin  layer  over  the  surface  of  the  coverslip. 
Do  not  allow  it  to  dry.    Drop  immediately 
into  a  Columbia  jar  containing  Schaudinn's 
fluid  at  room  temperature  or  37°  C.    Allow 
to  remain  about  10  minutes  and  then  trans- 
fer to  70%  alcohol. 

In  some  cases  it  may  be  necessary  to 
mix  the  feces  with  a  little  physiological 
salt  solution  in  order  to  make  it  thin  enough 
to  spread  well.    In  other  cases  the  feces 
are  so  fluid  that  if  the  coverslips  are  drop- 
ped edgewise  into  the  fixative,  all  the  ma- 
terial will  come  off.    To  prevent  this,  place 
the  fixing  solution  in  a  small,  flat  vessel 
such  as  a  petri  dish,  and  place  the  cover- 
slip  face  down  on  its  surface.    After  a  few 
seconds  it  can  be  transferred  to  a  Colum- 
bia jar. 

After  fixation,  wash  the  smear  in  2 
changes  of  70%  alcohol  for  at  least  5  min- 
utes each.    Then  transfer  to  70%  alcohol 
containing  enough  iodine  to  give  it  a  port 
wine  color.    Allow  to  remain  at  least  10 
minutes  (preferably  longer).     This  treat- 
ment takes  out  the  excess  mercuric  chlor- 
ide which  may  otherwise  form  crystals  in 
the  preparation.     Then  transfer  to  fresh 
70%  alcohol.     Fixed  material  may  be  kept 
in  70%  alcohol  indefinitely  without  injury. 

STAINING  WITH  HEIDENHAIN'S  HEMA- 
TOXYLIN 

In  order  to  bring  out  many  structures 
of  organisms  it  is  necessary  to  color  them 
with  a  dye  or  dyes.    The  best  and  most 
commonly  used  dye  employed  in  parasitol- 
ogic and  histologic  work  is  hematoxylin, 
which  is  extracted  from  logwood.     Hema- 
toxylin alone  has  very  poor  staining 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN  INFECTIONS 


381 


properties,  and  a  mordant  must  be  em- 
ployed to  make  it  effective.    Many  differ- 
ent formulas  have  been  used  for  hema- 
toxylin staining  solutions.    In  some,  the 
mordant  is  mixed  with  the  hematoxylin, 
while  in  others  it  is  used  separately. 
Many  different  compounds  are  used  as 
mordants,  the  great  majority  being  salts 
of  heavy  metals  such  as  iron,  lead,  copper, 
cobalt,  tungsten  and  molybdenum.    One  of 
the  best  hematoxylins  is  Heidenhain's 
iron-hematoxylin.    A  modification  of  this 
technic  is  given  below.    Starting  with  the 
smears  in  70%  alcohol  after  passing  thru 
iodine,  the  staining  schedule  is: 

50%  alcohol 5  minutes 

30%  alcohol 5  minutes 

Distilled  water S  minutes 

2%  aqueous  iron  alum 1  hour 

Distilled  water 1  minute 

0.5%  aqueous  hematoxylin     ....    2  hours 

Distilled  water Rinse 

Saturated  aqueous  picric  acid  .  .  .  Destain  until 
the  structures  assume  the  proper  intensity  of 
color.  This  process  should  be  controlled  by 
microscopic  examination  at  intervals.  Ten 
minutes  is  usually  good  for  intestinal  amoebae, 
but  a  longer  time  is  necessary  for  large  pro- 
tozoa such  as  Balantidhmi . 

Distilled  water Rinse --2  changes 

Tap  water Until  all  picric 

acid  has  come  out  of  the  smear.     Change  the 
water  at  intervals. 

30%  alcohol 5  minutes 

50%  alcohol S  minutes 

70%  alcohol 5  minutes 

Gradual  changes  in  alcohol  concentration 
are  used  in  all  staining  and  dehydration 
procedures  to  avoid  distortion  of  tissues. 
Hematoxylin-stained  smears  and  sections 
can  be  kept  in  70%  alcohol  indefinitely. 

In  the  classical  Heidenhain's  hema- 
toxylin staining  procedure,  the  stained 
smears  are  destained  with  iron  alum.    In 
the  above  procedure,  saturated  aqueous 
picric  acid  is  used  instead;  this  requires 
a  minimum  of  observation  (usually  none) 
during  the  destaining  process,  and  the  re- 
sultant stain  is  dark  blue  instead  of  brown- 
ish black  as  with  iron  alum. 

If  desired,  longer  mordanting  and 
staining  times  can  be  used.    The  smears 
can  be  mordanted  for  2  hours  and  stained 
for  4  hours,  or  they  can  be  mordanted  for 
4  hours  and  stained  overnight.    These  give 


a  little  more  precise  staining,  but  not 
enough  to  make  them  worthwhile  for  rou- 
tine purposes. 

COUNTERSTAINING 

If  desired,  the  smears  can  be  counter- 
stained  with  eosin  Y.    However,  this  has  a 
tendency  to  obscure  fine  nuclear  detail 
somewhat.    To  counterstain  the  smears, 
transfer  them  from  70%  alcohol  to  0.  5% 
solution  of  eosin  Y  in  90%  alcohol.    The 
pH  of  this  solution  should  be  brought  to 
5.  4  to  5.  6  by  adding  4.  0  ml  of  0. 1  N  HCl 
per  100  ml.    The  acidified  solution  will 
not  keep  more  than  10  days  to  2  weeks. 
After  that  its  pH  will  become  too  high  for 
satisfactory  use.    Stain  for  45  seconds  to 
3  minutes.    Transfer  to  95%  alcohol  to 
wash  out  excess  dye  and  then  proceed  as 
directed  below. 

MOUNTING 

Permanent  slides  are  mounted  in  a 
medium  which,  quite  fluid  at  first,  later 
becomes  hard.    Most  mounting  media  are 
immiscible  with  water,  and  many  with  al- 
cohol.   Hence,  before  mounting,  all  water 
and  alcohol  must  be  removed  from  the 
smears.    This  cannot  be  done  simply  by 
allowing  the  smears  to  dry,  for  such  de- 
hydration in  air  would  ruin  the  prepara- 
tions by  distorting  the  protozoa.    Mounting 
media  which  have  been  employed  include 
natural  resins  such  as  Canada  balsam  and 
damar,  and  synthetic  resins  such  as 
euparal,  naphrax,  permount  and  clarite. 

Starting  with  stained  coverslips  in 
70%  alcohol,  pass  them  thru  the  following 
solutions: 


95%  alcohol 5  minutes 

100%  alcohol 5  minutes 

100%  alcohol 5  minutes 

Toluene 5  minutes 

Toluene 5  minutes 

Mount  in  permount:     Place  a  drop  of 
permount  on  a  clean  slide,  place  the 
coverslip  slantingly,  smear  side  down, 
alongside  the  drop,  and  gently  lay  it  down 
on  the  drop,  taking  care  to  prevent  air 
bubbles  from  forming. 


382 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


Neutral  xylene  may  be  used  in  place 
of  toluene,  altho  it  hardens  the  tissues 
more.     Neutral  balsam  or  other  resinous 
mounting  media  may  be  used  in  place  of 
permount.    Neutralize  the  xylene  and  bal- 
sam by  placing  marble  chips  in  their  con- 
tainers.   If  this  is  not  done,  the  stains 
will  fade  more  or  less  after  months  to 
years. 

FEULGEN  STAIN 

The  Feulgen  nucleal  stain,  which  is 
used  for  the  detection  of  deoxyribonucleic 
acid  (DNA),  is  essentially  a  modification 
of  the  Schiff  reaction  for  aldehydes.    When 
DNA  is  hydrolyzed  by  hydrochloric  acid, 
aldehyde-like  substances  are  formed 
which,  when  treated  with  colorless  fuchsin 
sulfite,   stain  a  purplish  red.    Whether  the 
reaction  is  limited  to  DNA  is  doubtful,  but 
at  any  rate,  when  properly  carried  out, 
the  Feulgen  technic  produces  a  prepara- 
tion in  which  only  chromatin  is  stained. 

Not  all  samples  of  basic  fuchsin  are 
satisfactory  for  the  Feulgen  stain.     Hence, 
care  must  be  taken  to  use  dye  from  a 
batch  which  has  been  found  satisfactory 
and  which  has  been  certified  as  such  by 
the  Biological  Stain  Commission. 

1.  Fix  material  to  be  stained  by  this 
method  for  24  hours  in  a  satur- 
ated solution  of  mercuric  chloride 
containing  2%  acetic  acid. 

2.  Wash  in  running  water,  and  pass 
thru  30%,  50%,  and  70%  alcohol. 
Do  not  treat  with  iodine. 

3.  Cut  sections  in  the  usual  manner. 

4.  Before  staining,  leave  smears 
and  sections  in  95%  alcohol  48 
hours  to  remove  "plasmalogen" 
substances  which  may  take  the 
stain. 

5.  To  stain,   run  down  thru  the  alco- 
hols to  distilled  water,  and  place 
the  smears  or  sections  in  1  N  HCl 
at  60"  C  for  4  minutes. 

6.  Wash  in  cold  1  N  HCl,  then  rinse 
with  distilled  water. 

7.  Transfer  to  the  decolorized  fuehsin 
solution,  and  stain  1  to  3  hours. 

8.  Wash  thoroughly  in  water  contain- 
ing a  little  sodium  bisulfite  plus  a 
few  drops  of  HCl. 


9.    Wash  in  distilled  water. 
10.    Dehydrate  by  passing  up  thru  the 
alcohols  as  described  above,  clear, 
and  mount  in  permount. 

BODIAN  SILVER  IMPREGNATION 
TECHNIC 

This  method  is  superior  to  ordinary 
stains  for  demonstration  of  flagella  and 
other  diagnostic  structures  of  flagellates. 
The  technic  given  below  is  essentially  that 
described  by  Honigberg  (1947).    Not  all 
batches  of  protargol  are  equally  good  for 
this  stain,  and  care  must  be  taken  to  use 
a  sample  which  has  been  tested  and  found 
satisfactory. 

1.  Fix  in  Hollande's  or  Bouin's  solu- 
tions for  10  minutes. 

2.  Wash  in  50%  alcohol. 

3.  Transfer  to  30%  alcohol  and  then 
to  distilled  water. 

4.  Bleach  in  0.  5'c  aqueous  potassium 
permanganate  for  5  minutes. 

5.  Wash  in  distilled  water. 

6.  Bleach  in  5%  aqueous  oxalic  acid 
for  5  minutes. 

7.  Wash  several  times  in  distilled 
water. 

8.  Place  in  freshly  prepared  1%  aque- 
ous protargol  solution.     (To  pre- 
pare this  solution,  place  the  proper 
amount  of  distilled  water  in  a 
beaker  and  scatter  the  protargol 
powder  on  its  surface;  do  not  stir, 
heat  or  disturb  the  vessel  until  the 
protargol  has  dissolved.  ) 

9.  Keep  copper  wire  or  thin  copper 
sheeting  in  the  vessel  thruout  the 
staining  process.     Use  5  g  copper 
per  100  ml  pi'otargol  solution. 
Columbia  jars  contain  10  ml  of  so- 
lution.   If  they  are  used,  it  is  con- 
venient to  place  a  coil  of  copper 
wire  weighing  0.5  g  in  the  bottom  of 
each  jar  before  adding  the  protargol. 

10.    Stain  for  1  to  2  days  at  room  tem- 
perature or  37"  C  in  the  protargol- 
copper  solution.     The  staining  time 
and  temperature  will  depend  on  the 
material  being  stained  and  the  final 
intensity  desired.    If  staining  is  con- 
tinued for  more  than  a  day,  transfer 
to  fresh  protargol  solution  contain- 
ing fresh  copper  for  the  second  day. 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN   INFECTIONS 


383 


11.  Wash  in  distilled  water. 

12.  Place  in  a  solution  of  1%  hydro- 
quinone  in  5%  aqueous  sodium 
sulfite  for  5  to  10  minutes  to  re- 
duce the  silver. 

13.  Wash  several  times  in  distilled 
water. 

14.  Place  in  1%  (or  more  dilute)  aque- 
ous gold  chloride  for  4  to  5  min- 
utes. 

15.  Wash  in  distilled  water. 

16.  Place  in  2%  aqueous  oxalic  acid 
for  2  to  5  minutes  until  a  purplish 
color  appears. 

17.  Wash  several  times  in  distilled 
water. 

18.  Place  in  5%  sodium  thiosulfate  for 
5  to  10  minutes. 

19.  Wash  several  times  in  distilled 
water. 

20.  Pass  up  thru  a  graded  series  of 
alcohols  to  dehydrate,  clear  in 
toluene  or  xylene,   and  mount  in 
per  mount  or  balsam. 

GIEMSA  STAIN  FOR  TISSUE   SECTIONS 

The  following  technic  is  based  on  that 
described  by  Hewitt  (1940)  for  staining 
tissue  sections  with  Giemsa  stain. 

1.  Fix  small  pieces  of  tissue  in  for- 
mol-Zenker's  fluid  for  18  to  24 
hours. 

2.  Wash  in  running  tap  water  over- 
night. 

3.  Place  in  30%  alcohol,  50%  alcohol 
and  70%  alcohol  for  2  hours  each. 

4.  Treat  overnight  with  70%)  alcohol 
containing  enough  iodine  to  give  it 
a  port-wine  color.    This  removes 
the  excess  mercuric  chloride. 

5.  Place  in  fresh  70%  alcohol  for  2  to 
4  hours  or  longer  to  remove  the 
iodine. 

6.  Finish  dehydration,   and  infiltrate, 
embed,    section  and  mount  in  the 
usual  manner. 

7.  Run  the  sections  down  thru  xylene 
and  the  alcohols  into  distilled 
water,  in  the  usual  manner, 

8.  Mordant  in  2.  5%  aqueous  potassium 
bichromate  solution  1/2  to  1  hour. 

9.  Wash  quickly  in  distilled  water. 


10.  Stain  for  24  hours  in  the  following 
solution: 

0.  5%  aqueous  sodium  carbonate    .  2  to  4  drops 

Methyl  alcohol  (CP) 3  ml 

Giemsa  stain 2.5  ml 

Distilled  water 100  ml 

11.  Wash  in  distilled  water  colored 
lemon  yellow  with  2.  5%  potassium 
bichromate  to  remove  the  excess 
stain. 

12.  Differentiate  in  70%  alcohol.     This 
is  the  most  critical  step  in  the 
whole  procedure.     It  usually  takes 
30  seconds  to  2  minutes,  but  the 
time  varies  with  the  type  of  tissue 
and  the  thickness  of  the  sections. 
Liver  usually  takes  less  time  than 
enlarged,  engorged  spleen,  which 
takes  less  time  than  normal  spleen. 
Thick  sections  take  longer  than 
thin.    Stop  differentiating  as  soon 
as  the  stain  is  being  removed  in 
noticeable  quantities.    Tissues 
which  contain  a  large  amount  of 
blood  will  show  sharply  differen- 
tiated red  and  blue  areas  macro- 
scopically  when  they  are  properly 
differentiated. 

13.  Stop  the  differentiation  by  washing 
quickly  in  distilled  water. 

14.  Dehydrate  and  mount.    Alcohol 
cannot  be  used  for  the  dehydrating 
process,   since  it  will  remove  too 
much  dye.     The  simplest  and  best 
method  of  dehydration  is  to  pass 
the  sections  thru  3  changes  of  aii- 
Iiy (Irons  tertiary  butyl  alcohol  for 

5  to  10  minutes  each  (Levine,  1939). 
(Ordinary  samples  of  tertiary  butyl 
alcohol  contain  water  and  cannot  be 
used.    A  simple  way  of  determining 
whether  a  sample  is  anhydrous  is 
to  place  it  in  the  refrigerator;  its 
melting  point  is  25°  C,  and  it  will 
crystallize. ) 

Transfer  the  sections  from  the  third 
tertiary  butyl  alcohol  to  2  changes  of  xylene 
and  then  mount  in  permount  or  another  res- 
inous mounting  medium.    It  is  important 
that  the  mounting  medium  be  neutral;  if  it 
is  acid  it  will  soon  decolorize  the  prepara- 
tions. 


384 


lABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


(The  following  dehydration  procedure, 
recommended  by  Hewitt,  can  be  used  if 
tertiary  butyl  alcohol  is  not  available: 


Distilled  water 

Wash 

5%  xylene,   959<  acetone 

1  minute 

30«  xylene,   70%  acetone 

2  minutes 

70«  xylene,    30%  acetone 

2  minutes 

Xylene 

5  minutes) 

MICROSCOPIC  EXAMINATION 
OF  BLOOD 

In  searching  for  blood  protozoa, 
thick  or  thin  smears  of  the  blood  are  pre- 
pared and  stained  with  one  or  another  of 
the  Romanowsky  (methylene  blue-eosin 
combination)  stains.    Thick  smears  are 
preferable  to  thin  ones  for  mammalian 
blood  because  their  use  permits  one  to 
examine  a  relatively  large  amount  of 
blood  in  a  relatively  short  time.    How- 
ever, they  cannot  be  used  for  avian  blood 
because  of  its  nucleated  erythrocytes. 
The  protozoa  may  be  distorted  in  thick 
smears  enough  so  that  some  practice  is 
needed  to  differentiate  species,  especially 
of  the  malaria  parasites. 

Romanowsky  stains  may  be  either 
rapid  (such  as  Wright's  and  Field's  stains) 
or  slow  (such  as  Giemsa's  stain).    The 
rapid  stains  are  satisfactory  if  speed  is 
necessary,  but  they  stain  unevenly,  par- 
ticularly in  thick  smears,  and  they  are 
not  as  precise  as  the  slow  stains.    Giemsa's 
stain  is  best  for  most  purposes.     Mammal- 
ian blood  should  be  stained  at  pH  7.0  to  7.2, 
and  avian  blood  at  pH  6.  75.    These  pH's 
can  be  obtained  by  using  Clark  and  Lubs 
phosphate  buffers. 

Trypanosomes,  microfilariae  and 
most  protozoa  can  be  found  in  fresh,  wet, 
unstained  smears,  but  for  critical  study 
they  must  be  stained. 

Preparation  of  Thin  Blood  Smears. 
Clean  2  slides  by  rinsing  in  95%  alcohol 
and  wiping  with  a  clean  cloth.    Handle  the 
slides  only  by  their  edges  to  avoid  leaving 
finger  marks.     Place  a  small  drop  of  fresh 
blood  at  the  end  of  one  slide,  place  the 
other  slide  at  a  30°  angle  to  the  first  slide, 


touch  the  drop  of  blood  with  the  end  of  the 
slanted  slide  so  that  the  blood  runs  into 
the  space  beneath  it,  and  then  draw  the 
slanted  slide  rather  quickly  over  the  length 
of  the  other  slide.     The  blood  should  be 
pulled  behind  the  slide  and  not  pushed  ahead 
of  it  as  the  smear  is  being  made.    A  thin, 
even  film  of  blood  should  result.    Wave  the 
slide  in  the  air  until  it  dries  (a  matter  of  a 
few  seconds  if  the  smear  is  thin  enough). 
If  the  smear  is  to  be  stained  in  Giemsa's 
stain,  fix  it  by  dipping  in  absolute  methyl 
alcohol  (CP).    If  the  smear  is  to  be  stained 
in  Wright's  stain,  fixation  is  not  necessary, 
since  it  will  take  place  during  the  staining 
process.    If  the  smear  is  to  be  stored  for 
more  than  a  day  or  so  before  staining,  it 
should  be  fixed. 

Preparation  of  Thick  Blood  Smears. 
Prepare  slides  as  for  thin  smears.    Place 
a  medium-sized  drop  of  blood  or  several 
tiny  ones  on  the  slide,  and  mix  with  a 
toothpick  or  the  corner  of  another  slide. 
Allow  to  dry  in  air  or  in  an  incubator  at 
37°  C.    A  hair  dryer  can  be  used  to  speed 
up  the  drying  process.    Thick  smears  must 
be  laked  (i.e. ,  the  hemoglobin  must  be  ex- 
tracted) before  being  stained.     This  can  be 
done  by  placing  them  in  water  until  the 
color  has  disappeared.    If  Giemsa's  stain 
is  used  and  the  smears  are  fresh,  laking 
will  take  place  during  the  staining  process. 
If  the  smears  are  to  be  stored  for  more 
than  a  day  or  so  before  staining,  they 
should  be  laked  and  then  fixed  with  absolute 
methyl  alcohol  (CP)  before  storage,  since 
it  is  often  extremely  difficult  to  remove  the 
hemoglobin  from  smears  which  have  been 
stored  for  some  time. 

While  Leucocytozoon,  microfilariae 
and  sometimes  Trypanosoma  can  be  found 
with  the  low  power  of  the  microscope,  the 
stained  blood  smears  should  be  examined 
with  the  oil  immersion  objective  for  other 
protozoa.    The  faster  thin  smears  have 
dried,  the  less  distortion  is  produced. 
Hence,  the  most  natural  appearing  protozoa 
will  be  found  at  the  thin  end  and  around  the 
edges  of  the  smear. 

Cleaning  Immersion  Oil  Off  of  Slides. 
Stained  blood  smears  are  customarily  not 
covered  with  a  coverslip,  and  immersion 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


385 


oil  is  placed  on  them  for  examination. 
The  immersion  oil  should  be  removed 
after  the  examination  has  been  completed 
if  the  slides  are  not  to  be  thrown  away. 
Many  people  do  this  by  rubbing  the  slide 
with  lens  paper  as  tho  they  were  polishing 
silver,  a  procedure  which  removes  not 
only  the  oil  but  also  many  of  the  blood 
cells.     The  following  technic,  which  I 
first  saw  demonstrated  by  Dr.  Joseph  A. 
Long,   permits  one  to  remove  the  oil 
quickly  and  neatly  without  disturbing  the 
blood  cells.    It  can  also  be  used  for  slides 
which  have  been  covered  by  a  coverslip; 
by  its  use,  one  can  remove  the  oil  from  a 
newly  mounted  slide  without  also  removing 
either  the  coverslip  or  the  wet  mounting 
medium  beneath  it. 

Fold  a  small  piece  (about  5  cm  square) 
of  lens  paper  twice  so  that  it  is  4  layers 
thick.     Place  the  lens  paper  on  top  of  the 
immersion  oil  and  allow  it  to  take  up  the 
oil.    Pull  if  off  the  slide  sideways  in  a 
single  motion;  do  not  rub. 

Fold  a  second  piece  of  lens  paper  like 
the  first.    Place  a  drop  of  xylene  on  it. 
Place  the  wet  lens  paper  on  what  remains 
of  the  oil.     Leave  it  for  a  second  or  two, 
and  then  pull  it  off  the  slide  sideways  in 
a  single  motion;  do  not  rub.    When  the 
xylene  has  evaporated,  the  slide  will  be 
clean  and  dry.    (Sometimes  it  is  necessary 
to  repeat  this  second  step  with  a  fresh 
piece  of  lens  paper. ) 


CONCENTRATION  OF  PROTOZOAN 
CYSTS  FROM  FECES 

A  number  of  technics  have  been  devel- 
oped for  the  concentration  of  protozoan 
cysts  and  helminth  eggs  from  feces.    They 
are  of  2  general  types,  flotation  and  sedi- 
mentation.   Each  has  certain  advantages 
over  the  other. 


FLOTATION  TECHNICS 

These  technics  make  use  of  solutions 
of  higher  specific  gravity  than  protozoan 
cysts  or  helminth  eggs,  but  of  lower  spe- 
cific gravity  than  most  of  the  fecal  debris. 


When  feces  are  mixed  with  them,  the  cysts 
and  eggs  will  float  to  the  top  while  most  of 
the  fecal  material  remains  at  the  bottom. 
Flotation  technics  are  most  useful  for  coc- 
cidian  oocysts,  other  protozoan  cysts, 
nematode  eggs  and  some  tapeworm  eggs. 
They  are  not  satisfactory  for  trematode, 
acanthocephalan  and  other  tapeworm  eggs. 

Many  different  solutions  have  been 
used,  and  many  variations  in  technic  have 
been  proposed.    The  methods  described 
here  all  work  satisfactorily. 

Sugar  Flotation 

This  technic  is  preferable  for  general 
use,  but  is  not  satisfactory  for  protozoan 
cysts  other  than  those  of  coccidia.    Sugar 
solution  is  preferable  to  sodium  chloride, 
sodium  nitrate  or  other  salt  solutions  ex- 
cept zinc  sulfate.    It  does  not  crystallize 
as  readily,  and  causes  less  distortion  than 
salt  solutions,  and  it  is  just  as  efficient 
(Levine  et  al.  ,   1960).     The  following  tech- 
nic is  a  modification  of  the  DCF  (direct 
centrifugal  flotation)  technic  introduced  by 
Lane  (1923). 

1.  Make  a  rather  heavy  suspension  of 
feces  in  physiological  salt  solution 
in  a  shell  vial  or  other  container. 

2.  Strain  thru  2  layers  of  cheesecloth 
into  a  test  tube  or  centrifuge  tube, 
filling  the  tube  almost  half  full. 
The  lip  of  the  tube  must  be  smooth, 
or  an  air  bubble  will  form  under 
the  coverslip  following  centrifuga- 
tion  (#6  below). 

3.  Add  an  equal  volume  of  Sheather's 
sugar  solution,  leaving  a  small  air 
space  at  the  top.    Cover  with  a 
plastic  coverslip  or  small  piece  of 
card,  and  invert  repeatedly  to  mix. 

4.  Add  enough  additional  Sheather's 
sugar  solution  to  bring  the  surface 
of  the  liquid  barely  above  the  top 
of  the  tube. 

5.  Cover  with  a  round  coverslip. 

6.  Centrifuge  for  5  minutes.     (If  a 
centrifuge  is  not  available,  let 
stand  for  45  minutes  to  1  hour. ) 

7.  Remove  the  coverslip,  place  it  on 
a  slide,  and  examine  under  the 
microscope. 


386 


lABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


(If  desired,  Steps  2  to  4  can  be  mod- 
ified by  straining  the  fecal  suspension  into 
a  second  shell  vial,   mixing  with  an  equal 
volume  of  Sheather's  sugar  solution,  and 
then  filling  the  centrifuge  tube  with  the 
mixture.  ) 

Zinc  Sulfate  Flotation 

Zinc  sulfate  solution  has  the  advantage 
of  concentrating  the  cysts  of  protozoa  such 
as  Entamoeba  and  Giardia  without  distor- 
tion.    The  following  technic  is  a  modifica- 
tion of  that  introduced  by  Faust  el  al. 
(1938). 

1.  Make  a  suspension  of  feces  in 
physiological  salt  solution  in  a 
shell  vial  or  other  container. 

2.  Strain  4  ml  of  the  suspension  thru 
2  layers  of  cheesecloth  into  a  test 
tube  or  centrifuge  tube.     The  lip 
of  the  tube  must  be  smooth. 

3.  Add  tap  water  to  within  1  cm  of  the 
top  of  the  tube. 

4.  Mix  thoroughly  and  centrifuge  for 
5  minutes. 

5.  Pour  off  the  supernatant  fluid. 

6.  Add  a  small  amount  of  zinc  sulfate 
solution  and  mix  with  an  applica- 
tor stick.    Add  more  zinc  sulfate 
solution  until  the  tube  is  almost 
full,  cover  with  a  plastic  coverslip 
or  a  small  piece  of  card,  and  in- 
vert repeatedly  to  mix. 

7.  Add  enough  additional  zinc  sulfate 
solution  to  bring  the  surface  of 
the  liquid  barely  above  the  top  of 
the  tube. 

8.  Cover  with  a  round  coverslip. 

9.  Centrifuge  for  5  minutes. 

10.    Remove  the  coverslip,  place  it  on 
a  slide,  and  examine  under  the 
microscope. 

SEDIMENTATION  TECHNICS 

Sedimentation  technics  can  be  used 
for  concentration  of  protozoan  cysts,  and 
are  necessary  for  the  concentration  of 
trematode,  acanthocephalan  and  some 
tapeworm  eggs,  which  sink  to  the  bottom 
of  the  solutions  used  in  the  flotation  tech- 
nics.   A  few  protozoan  cysts  such  as 
those  of  Eimeria  leuckarli  also  sink  to 
the  bottom. 


Since  they  are  essentially  washing 
processes,  sedimentation  technics  may 
not  concentrate  cysts  and  eggs  as  much  as 
flotation  technics.     Many  different  sedi- 
mentation technics  have  been  developed. 
The  two  described  below  appear  to  be 
among  the  best. 

Formalin-Triton-Ether  (FTE) 
Sedimentation  Technic 

This  technic  was  introduced  by 
Ritchie  (1948)  and  modified  by  Maldonado, 
Acosta-Matienzo  and  Velez-Herrera  (1954). 
The  latter  considered  it  the  nearest  to  an 
all-round  diagnostic  procedure,   since  it  is 
highly  effective -for  the  detection  not  only 
of  schistosome,  hookworm,  whipworm  and 
ascarid  eggs  but  also  of  protozoan  cysts. 

1.  Mark  off  a  test  tube  at  the  5  ml  and 
6  ml  levels. 

2.  Place  5  ml  of  10%  formalin  con- 
taining a  drop  of  Triton  NE  in  the 
tube. 

3.  Add  1  ml  of  feces. 

4.  Break  up  the  feces  thoroughly  with 
a  wooden  applicator. 

5.  Strain  the  suspension  thru  4  layers 
of  cheesecloth  into  a  15  ml  conical 
centrifuge  tube.    Squeeze  the  cloth 
to  get  out  as  much  liquid  as  pos- 
sible. 

6.  Add  5  ml  of  commercial  ether  to 
the  suspension  in  the  centrifuge 
tube.    Cover  the  tube  with  a  plastic 
coverslip  and  shake  vigorously. 

7.  Centrifuge  (at  2000  r.p.m.  in  a 
horizontal  centrifuge  with  a  radius 
from  the  center  to  the  tip  of  the 
tube  of  8  inches;  if  another  type  of 
centrifuge  is  used,  change  the  speed 
of  centrifugation  accordingly)  for 

1  minute  after  the  centrifuge  has 
reached  its  terminal  speed. 

8.  Loosen  the  plug  of  detritus  at  the 
formalin  solution-ether  interface 
with  an  applicator  stick,   pour  off 
all  the  supernatant  fluid  rapidly, 
and,   holding  the  tube  slightly  in- 
verted, clean  its  walls  carefully 
with  a  piece  of  clean,  dry  gauze. 
This  is  done  to  prevent  the  liquid 
and  debris  on  the  walls  of  the  tube 
from  sliding  down  to  the  bottom 
and  diluting  the  sediment. 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN   INFECTIONS 


387 


9.    Add  a  drop  of  physiological  salt 
solution  to  the  sediment  to  facil- 
itate its  removal. 
10.    Take  up  the  sediment  with  a  pipette 
(a  Stoll  pipette  works  well),  place 
on  a  slide,  add  a  coverslip,  and 
examine  under  the  microscope. 

MIFC  (Merthiolate-Iodine- Formaldehyde 
Concentration)  Technic 

This  technic  was  introduced  by  Blagg 
et  cd.    (1955)  as  a  modification  of  the  MIF 
preservative  stain.     They  found  that  the 
MIFC  technic  was  positive  for  protozoan 
trophozoites  in  74%  of  110  positive  human 
fecal  specimens  as  compared  with  55% 
for  the  MIF  direct  smear;  it  was  positive 
for  92%  of  226  specimens  containing  pro- 
tozoan cysts,  as  compared  with  58%  pos- 
itive with  the  MIF  direct  smear. 

1.  Prepare  an  MIF  presei'ved  fecal 
specimen  as  described  above 

(p.   379). 

2.  When  ready  to  examine,   shake  the 
specimen  vigorously  for  5  seconds. 

3.  Strain  thru  2  layers  of  wet  surgi- 
cal gauze  into  a  15  ml  centrifuge 
tube. 

4.  Add  4  ml  cold  (refrigerated)  ether 
to  the  centrifuge  tube,  insert  a 
rubber  stopper,  and  shake  vigor- 
ously.   If  ether  remains  on  top 
after  shaking,  add  1  ml  tap  water 
and  shake  again. 

5.  Remove  the  stopper  and  let  stand 
for  2  minutes. 

6.  Centrifuge  1  minute  at  1600  r.p.m. 
Four  layers  will  appear  in  the  tube: 
(a)  an  ether  layer  on  top,    (b)  a 
plug  of  fecal  detritus,    (c)  an  MIF 
layer,    (d)  the  sediment  containing 
protozoa  and  helminth  eggs  on  the 
bottom . 

7.  Loosen  the  fecal  plug  by  ringing 
with  an  applicator  stick. 

8.  Quickly  but  carefully  pour  off  all 
but  the  bottom  layer  of  sediment. 

9.  Mix  the  sediment  thoroughly,   pour 
a  drop  on  a  slide,  cover  with 
coverslip,  and  examine. 


PROTOZOAN  CULTURE  MEDIA 

NNN  (Novy,   MacNeal  and  Nicolle)  Medium 

This  medium  was  developed  for  the 
cultivation  of  Leisli))iaiiia,  but  it  can  also 
be  used  for  trypanosomes  of  the  lewisi 
group. 

1.  Measure  or  weigh  out: 

Sodium  chloride 6  g 

Agar 14  g 

Distilled  water 900  ml 

2.  Mix,  bring  to  the  boiling  point, 
and  place  in  bacteriologic  culture 
tubes  in  5  ml  amounts.    Sterilize 
in  the  autoclave.     This  is  the 
medium  base,  and  can  be  stored 
in  the  refrigerator. 

3.  To  use,  melt  the  agar  in  the  tubes 
and  cool  to  48°  C.    Add  to  each 
tube  1/3  of  its  volume  of  sterile, 
defibrinated  rabbit  blood.     Mix 
thoroughly  by  rolling  the  tube  be- 
tween the  palms  of  the  hands. 

4.  Place  the  tube  on  a  slant  without 
leaving  a  butt  of  medium  at  the 
bottom,  and  allow  to  solidify. 
This  is  best  done  in  the  refrigera- 
tor or  in  ice,  since  more  water  of 
condensation  is  obtained  in  this 
way.    (The  protozoa  develop  best 
in  the  water  of  condensation  at  the 
bottom  of  the  slant. ) 

5.  Seal  the  tubes  to  prevent  the  water 
of  condensation  from  evaporating, 
and  incubate  at  37°  C  for  24  hours 
to  test  for  sterility  before  inocu- 
lating. 

6.  Inoculate  suspected  material  into 
the  condensation  water  and  incu- 
bate at  22  to  24°  C.    Transfer 
cultures  every  week  or  two. 

Weinman's  Trypanosome  Medium 

This  medium  was  developed  by  Wein- 
man (1946)  for  the  cultivation  of  Trypatio- 
so)}ia  gauibiense  and  T.  rliodesiense.     It 
can  also  be  used  for  other  trypanosomes o 


388 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN  INFECTIONS 


1.  The  base  medium  is  Difco  nutrient 
agar  (1.  5%),  which  consists  of: 

Beef  extract 3  g 

Bacto  peptone 5  g 

Sodium  chloride 8  g 

Agar 15  g 

31  R 

Dissolve  in  1  liter  distilled  water, 
bring  to  pH  7.  3,  sterilize  by  auto- 
claving. 

2.  To  prepare  the  culture  medium, 
heat  the  base  medium  to  melt  the 
agar.    Before  it  has  resolidified, 
add  the  following  aseptically  to 
each  75  ml  of  the  base: 

Citroted  human  plasma  previously 

inactivated  at  56   C  for  30  minutes  .    12.  5  mi 
Human  red  cells 12.5  ml 

3.  Dispense  in  Kolle  flasks  or  slanted 
in  test  tubes.    Stopper  with  rubber 
corks  or  seal  with  Parafilm  to  re- 
tard drying.    Store  in  the  refriger- 
ator until  used. 

4.  Inoculate  with  suspected  material 
and  incubate  at  room  temperature. 
The  trypanosomes  grow  on  the 
surface  as  small,  rounded,  color- 
less, transparent,  slightly  raised, 
glistening,  moist-appearing  colon- 
ies 1  to  2  mm  in  diameter;  they 
are  detectable  in  5  to  10  days  or, 
exceptionally,  in  3  to  4  weeks. 

Tobie,  von  Brand  and  Mehlman's 
Trypanosome  Medium 

This  medium  was  developed  by  Tobie, 
von  Brand  and  Mehlman  (1950)  for  African 
trypanosomes.  It  consists  of  a  solid  slant 
with  a  liquid  overlay. 

1.    Solid  slant.    Measure  or  weigh  out: 

Bacto-beef  (Difco) l.Sg 

Bacto-peptone  (Difco) 2.  5  g 

Bacto-agar  (Difco)      7.  5  g 

NaCl 4.0  g 

Distilled  water      500  ml 

Mix  the  ingredients,  dissolve  by 
bringing  to  the  boiling  point,  adjust 
to  pH  7.  2  to  7.  4  with  NaOH,  and 


3. 


4. 


autoclave  at  15  lbs.  pressure  for 
20  minutes. 

Cool  to  45°  C,  and  add  1  part  of 
inactivated,  citrated  rabbit  blood 
to  each  3  parts  of  the  above  base. 
Place  5  ml  amounts  in  test  tubes, 
slant,  and  allow  to  cool.    If  de- 
sired,  25  ml  amounts  may  be 
placed  in  flasks. 

Fluid  overlay  (Locke's  solution). 
Measure  or  weigh  out: 

NaCl 8.  0  g 

KCl 0.2g 

CaClj 0.  2  g 

KH2PO4 0.  3  g 

Glucose 2. 5  g 

Distilled  water 1000  ml 

Autoclave  at  15  pounds  pressure 

for  20  minutes. 

Place  2  ml  of  the  liquid  overlay  in 

each  tube  containing  5  ml  of  the 

base  (or  10  to  15  ml  in  each  flask), 

using  aseptic  technic. 

Inoculate  with  suspected  material 

and  incubate  at  24  to  25°  C  for  10 

to  14  days. 


RES  (Ringer's- Egg-Serum)  Medium  for 
Enteric  Protozoa 

This  medium  was  first  introduced  by 
Boeck  and  Drbohlav  (1925).  Many  differ- 
ent modifications  have  been  proposed  which 
are  as  useful  as  the  one  described  below. 
The  serum  may  be  replaced  by  egg  albu- 
men, for  instance,  or  the  Ringer's  solu- 
tion by  Locke's  solution. 

The  medium  is  essentially  a  coagu- 
lated egg  slant  overlaid  with  a  fluid  nutri- 
ent solution. 

A.    Egg  slant. 

1.  Mix  12.  5  ml  Ringer's  solution 
with  each  egg  used.     For  best  re- 
sults, mix  in  a  Waring  blendor  for 
30  seconds.    If  a  blendor  is  not 
used,  filter  the  mixture  thru 
cheesecloth. 

2.  Place  2  ml  amounts  of  the  mix- 
ture in  cotton-stoppered  test  tubes. 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN  INFECTIONS 


389 


(Other  standard  closures  for  bac- 
teriologic  work  can  also  be  used. ) 

3.  Place  the  tubes  upright  in  a  vac- 
uum desiccator.     Evacuate  the 
desiccator  slowly.    As  evacuation 
proceeds,  the  egg  mixture  begins 
to  bubble,  and  within  4  minutes  a 
dense  foam  of  egg  begins  to  climb 
in  the  tubes.    Stop  the  evacuation 
before  the  cotton  plugs  become 
wet,  and  allow  the  tubes  to  remain 
in  the  evacuated  desiccator  for  an 
hour.    The  purpose  of  this  treat- 
ment is  to  remove  the  dissolved 
air  from  the  medium.    If  it  is 
allowed  to  remain,  it  will  bubble 
out  during  subsequent  sterilization 
and  coagulation,  roughening  and 
pitting  the  slant  surface  (Levine 
and  Marquardt,  1954). 

4.  Release  the  vacuum,  pack  the 
tubes  in  baskets,  slant  them  in 
the  autoclave,  and  inspissate  and 
sterilize  them  simultaneously  at 

15  pounds  pressure  for  20  minutes. 
Best  results  are  obtained  when  no 
butt  of  medium  is  left  in  the  tubes. 
When  this  is  done,  2  ml  of  fluid 
makes  a  slant  about  1.  5  inches 
long  in  an  18  x  150  mm  tube. 

B.    Fluid  overlay. 

1.  Mix  the  following  aseptically: 

Sterile  Ringer's  solution 500  ml 

Sterile  10%  glucose  solution 10  ml 

Sterile  serum  (horse,  rabbit,  cow,  etc.).        10  ml 

2.  Add  sufficient  fluid  overlay  to 
each  egg  slant  to  cover  the  whole 
slant.      Aseptic  technic  must  be 
used  thruout.    Incubate  at  37  °  C 
for  2  days  prior  to  inoculation  to 
test  for  sterility. 


Balamuth's  Amoeba  Medium 

This  medium  was  developed  by  Bala- 
muth  (1946)  for  enteric  amoebae,  but  it 
can  be  used  for  other  enteric  protozoa  as 
well. 


1.  Mix  288  g  dehydrated  egg  yolk  with 
288  ml  distilled  water  and  1000  ml 
physiological  salt  solution.     Mix 
with  a  Waring  blendor  or  similar 
instrument  until  the  suspension  is 
smooth. 

2.  Heat  over  an  open  flame  in  the 
upper  part  of  a  double  boiler, 
stirring  constantly,  for  5  to  10 
minutes  until  coagulation  begins. 

3.  Continue  heating  over  boiling  water 
in  the  double  boiler  for  20  minutes 
until  coagulation  is  complete.    Add 
160  ml  distilled  water  to  replace 
water  lost  by  evaporation. 

4.  Filter  thru  a  muslin  bag.    When 
the  bag  cools,  squeeze  it  gently  to 
obtain  the  maximum  amount  of  fil- 
trate. 

5.  Add  enough  physiological  salt  solu- 
tion to  the  filtrate  to  bring  its  vol- 
ume to  1000  ml. 

6.  Place  500  ml  of  filtrate  in  each  of 
2  Erlenmeyer  flasks.    Autoclave 
at  15  pounds  pressure  for  20  min- 
utes. 

7.  Chill  the  flasks  by  refrigeration 
overnight  or  in  some  other  way. 

8.  Filter  while  cold  thru  2  layers  of 
Whatman  qualitative  filter  paper  in 
a  Buchner  funnel,  using  negative 
pressure.    Pour  the  mixture  thru 
the  funnel  in  small  amounts,  re- 
placing the  filter  paper  frequently. 

9.  Add  an  equal  volume  of  Balamuth's 
buffer  solution  to  the  filtrate. 

10.  Add  5  ml  of  crude  liver  extract 
(Lilly,  No.  408)  to  each  liter  of 
medium. 

11.  Dispense  in  5  to  7  ml  amounts  in 
tubes. 

12.  Autoclave  at  15  pounds  pressure 
for  20  minutes. 

13.  Add  a  small  amount  of  sterile  rice 
powder  to  each  tube.  Incubate  for 
24  hours  at  37°  C  to  test  for  ster- 
ility. (If  desired,  the  medium  can 
be  stored  in  large  flasks  in  the  re- 
frigerator after  autoclaving;  it  can 
be  kept  for  a  month  or  more  with- 
out deteriorating,  but  any  sediment 
which  forms  should  be  removed  by 
filtration  before  use. ) 


390 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


CPLM  (Cysteine-Peptone-Liver  Infusion- 
Maltose)  Medium 

This  medium  was  developed  by  John- 
son and  Trussell  (1943)  for  Trichomonas, 
but  it  can  also  be  used  for  other  enteric 
protozoa. 

A.  Liver  infusion. 

1.  Mix  the  following  thoroughly,  using 
a  Waring  blendor  if  available: 

Bocto  liver  powder 20  g 

Distilled  water 330  ml 

2.  Infuse  for  1  hour  at  about  50°  C. 

3.  Heat  with  stirring  at  80°  C  for  5 
minutes  to  coagulate  the  protein. 

4.  Filter  thru  a  Buchner  funnel. 
About  320  ml  of  liver  infusion  are 
obtained. 

B.  Preparation  of  final  medium. 

1.    Mix  the  following,  using  a  Waring 
blendor  if  available: 

Cysteine  monohydrochloride      ....  2. 4  g 

Peptone 32.0  g 

Maltose 1.6g 

Agar 1.6  g 

Ringer's  solution      960  ml 


2. 

3. 

4. 
5. 

6. 


10. 


11. 


Add  the  liver  infusion  from  A  above. 
Adjust  the  pH  to  7.0  (approximately 
20  ml  of  1.0  N  NaOH  are  needed). 
Heat  to  dissolve  the  agar. 
Filter  thru  cotton  into  a  2000  ml 
flask. 

Add  0.  7  ml  of  0.  5%  methylene  blue 
solution. 

Place  300  ml  amounts  in  500  ml 
Erlenmeyer  flasks. 
Autoclave  for  15  minutes  at  15 
pounds  pressure. 

Add  75  ml  sterile  inactivated  serum 
to  each  300  ml  flask. 
Place  7  to  10  ml  amounts  aseptic- 
ally  in  sterile,   plugged  test  tubes. 
Incubate  for  2  days  at  37°  C  to  test 
for  sterility  before  use. 


BGPS  (Beef  Extract-Glucose-Peptone- 
Serum)  Medium 

This  medium  was  introduced  by  Fitz- 
gerald,  Hammond  and  Shupe  (1954)  for  use 
in  the  diagnosis  of  Trilriclionio}ias  foelits 
infections,  but  it  can  also  be  used  for  other 
trichomonads. 

1.  Mix  the  following  in  a  3  liter  flask: 

Difco  beef  extract 3  g 

Glucose 10  g 

Bacto  peptone 10  g 

NaCl 1  g 

Agar     0.7  g 

Distilled  water 1000  ml 

2.  Dissolve  by  boiling.    After  cooling, 
adjust  the  pH  to  7.  4  with  1 .  0  N 
NaOH  solution. 

3.  Cover  the  mouth  of  the  flask  with 
heavy  paper  and  autoclave  for  30 
minutes  at  15  pounds  pressure. 

4.  After  cooling,   add  20  ml  inacti- 
vated (at  56°  C  for  30  minutes) 
beef  serum  aseptically,  and  mix 
thoroughly. 

5.  Dispense  in  10  ml  amounts  into  15 
ml  culture  tubes.     Test  for  ster- 
ility by  incubating  at  37°  C  for  2 
days. 

6.  Just  before  inoculation,  add  500  to 
1000  units  of  penicillin  and  0.  5  to 
1.0  mg  of  streptomycin  to  each  ml 
of  medium,  and  mix  thoroughly. 

7.  Pipette  the  inoculum  on  the  top  of 
the  medium  in  such  a  way  as  to 
minimize  mixing.     The  trichomo- 
nads migrate  to  the  bottom  of  the 
tube,  while  yeasts  and  molds  tend 
to  remain  near  the  top.    Incubate 
at  39°  C  for  3  to  5  days.    To  ex- 
amine, remove  a  sample  from  the 
bottom  of  the  tube  with  a  pipette. 

Diamond's  Trichomonad  Medium 

This  medium  was  introduced  by 
Diamond  (1957)  for  the  axenic  cultivation 
of  trichomonads.    It  can  be  used  success- 
fully for  more  species  than  other  media. 


LABORATORY  DIAGNOSIS   OF  PROTOZOAN  INFECTIONS 


391 


1.    Mix  the  following: 

TrypticQse  (BBL) 2.0  g 

Yeast  extract l.Og 

Maltose O.Sg 

L-cysteine  hydrochloride 0.  1  g 

Ascorbic  acid 0.02  g 

KjHPO^ 0.  08  g 

KH2PO4 0.  08  g 

Distilled  water     90  ml 


Adjust  the  pH  to  6.  8-7.  0  with  1  N 
NaOH  for  all  trichomonads  except 
T.  vaginalis  ;  for  this  species,  ad- 
just the  pH  to  6. 0  with  1  N  HCl. 
Add  0.05  g  agar. 
Autoclave  for  10  minutes  at  15 
pounds  pressure. 

Cool  to  48°  C,  and  add  the  follow- 
ing: 


7. 


Sheep  serum  (inactivated  at  56   C  for 

30  min. ) 10  ml 

Potassium  penicillin  G      100,  000  units 

Streptomycin  sulfate      0.  1  g 

(The  penicillin  and  streptomycin 
can  be  made  up  in  1  ml  distilled 
water  beforehand. ) 
Place  5  ml  amounts  of  the  medium 
aseptically  in  sterile,  stoppered 
test  tubes.    Store  in  the  refriger- 
ator up  to  14  days  or  longer. 
Prior  to  inoculation,  incubate  the 
tubes  at  35.  5°  C  for  1  hour. 


All  the  trichomonads  which  Diamond 
(1957)  cultivated  except  T.  gallinarum 
and  T.  gallinarum  -like  species  grew  well 
at  35.  5°  C;  the  latter  grew  better  at  38.  5° 
C. 

It  has  been  found  in  the  author's  lab- 
oratory that  the  phosphates  are  not  neces- 
sary for  the  growth  of  T.  foetus,   T.  suis, 
T.  gallittae,   T.  gallinarum  and  several 
other  species. 

RSS  (Ringer' s-Serum-Starch)  Medium 
for  Balantidium 

The  following  medium  is  slightly  mod- 
ified from  that  introduced  by  Rees  (1927) 
for  the  cultivation  of  Balantidium  colt. 


1.  Add  25  ml  of  horse,  rabbit  or 
bovine  serum  aseptically  to  500  ml 
of  sterile  Ringer's  solution. 

2.  Tube  in  8  ml  amounts,  using  asep- 
tic technic. 

3.  To  each  tube  add  a  5  mm  loop  of 
rice  starch  which  has  been  ster- 
ilized in  a  large  test  tube  for  30 
minutes  at  15  lb  pressure. 

4.  Incubate  at  37°  C  for  48  hours  to 
test  for  sterility.    Store  in  the  re- 
frigerator. 

5.  Before  inoculation,  warm  the  tubes 
to  37°  C  by  placing  them  in  the  in- 
cubator.   Incubate  at  37  ° .    The 
protozoa  grow  in  the  bottom  of  the 
tube. 


FORMULAE 
Physiological  Salt  Solution 

NaCl 8.  5  g 

Distilled  water 1000  ml 

D'Antoni's  Iodine  Solution 

Powdered  iodine l-Sg 

1%  aqueous  KI  solution 100  ml 

Allow  to  stand  4  days  before  use.    This  is 
the  stock  solution  and  contains  an  excess 
of  iodine.     Filter  small  amounts  before 
use.    If  tightly  stoppered,  the  filtered  so- 
lution will  keep  4  weeks  before  too  much 
iodine  has  volatilized  for  use. 

Lugol's  Iodine  Solution 

Potassium  iodide 10  g 

Powdered  iodine 5  g 

Distilled  water 100  ml 

Dissolve  the  potassium  iodide  in  the  water 
before  adding  the  iodine. 

Mayer's  Albumen  Fixative 

Put  the  whites  of  several  new-laid 
eggs  in  a  shallow  dish.    Whip  them  a  little 
with  a  fork  or  wire  egg  beater,  2  or  3 
dozen  strokes  being  sufficient.    Do  not 
beat  them  until  they  are  white  and  stiff. 


392 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


Allow  them  to  stand  for  about  an  hour, 
and  then  skim  the  foam  from  the  top  and 
pour  the  remaining  liquid  into  a  graduated 
cylinder.     Pour  in  an  equal  amount  of 
glycerol,  and  add  1  g  of  sodium  salicylate 
for  each  100  ml  of  the  mixture.    Shake 
thoroughly  and  filter  thru  paper  into  a 
clean  bottle.     Filtration  will  require  1  to 
several  weeks.    It  may  be  accelerated 
somewhat  by  pouring  a  rather  small  amount 
at  a  time  into  the  filter  and  replacing  the 
paper  every  few  days.    Keep  a  small  quan- 
tity in  a  vial  or  bottle  provided  with  a  glass 
rod  stuck  into  the  cork  and  projecting  into 
the  albumen.    A  drop  can  easily  be  placed 
on  a  slide  with  this  rod.  j 

Hollande's  Fixative 

Picric  acid 4  g 

Copper  acetate 2.  5  g 

Formalin 10  ml 

Acetic  Qcid 1.5  ml 

Distilled  water 100  ml 

Schaudinn's  Fixative 

Saturated  aqueous  mercuric  chloride     .      66  ml 
95%  alcohol 33  ml 


2.  Cool  to  50°  C. 

3.  Filter. 

4.  Add  20  ml  1  N  HCl  to  the  filtrate. 

5.  Cool  to  25°  C. 

6.  Add  1  g  dried  sodium  bisulfite 
(NaHSOs);  this  liberates  suLfurous 
acid. 

7.  Allow  to  stand  at  room  temperature 
24  hours  until  decolorized. 

8.  Store  in  the  refrigerator  in  small 
glass-stoppered  bottles  filled  to 
the  top  to  exclude  air.    The  solu- 
tion will  keep  several  weeks.    It 
should  be  straw-colored;  if  it  is 
red,  it  should  be  discarded. 

S0rensen's  Phosphate  Buffers 

To  make  M/15  Na2HP04  solution, 
dissolve  9.  5  g  anhydrous  Na2HP04  or  11.9 
g  Na2HP04  •  2  H2O  in  1  liter  distilled  water. 
To  make  M/15  KH2PO4,  dissolve  9.08  g 
KH2PO4  in  1  liter  distilled  water.    Store 
separately  in  pyrex,  glass-stoppered 
bottles. 

To  prepare  buffered  water  for  the 
Giemsa  stain,  mix  the  following  amounts 
of  the  solutions  (in  ml): 


Add  5%  acetic  acid  immediately  before 
use. 

Iron  Alum  Solution 

Ferric  ammonium  sulfate  (violet  crystals 

only) 2  g 

Distilled  water     100  ml 

Filter  immediately  before  use. 
Heidenhain's  Hematoxylin  (Stock  Solution) 

Hematoxylin 10  g 

100%  alcohol 100  ml 

Allow  to  remain  1  month  in  a  loosely  stop- 
pered bottle  before  use.    To  make  the 
staining  solution,  add  0.  5  ml  of  the  stock 
solution  to  9.  5  ml  of  distilled  water. 


pH6.8         pH7.0        pH7.2 


M/lSNojHPO               50.0 

61.  1 

72.0 

M/15  KHjPO^              50.0 

38.9 

28.0 

Distilled  water           900.0 

900.0 

900.0 

Balamuth's  Buffer  Solution 

1.0  M  K^HPO^  (174.  180  g  KjHPO^ 

in  1000  ml  distilled  water)  .,._..     4.3  parts 
1.0  M  KH2PO4  (136.092  g  KH2PO4 

in  1000  ml  distilled  water) 0.  7  ports 

This  is  the  stock  solution.    To  pre- 
pare the  final  solution  used  in  Balamuth's 
medium,  add  14  parts  of  distilled  water 
to  1  part  of  the  stock  solution. 

Ringer's  Solution 


Feulgen  Stain 

1.    Dissolve  1  g  basic  fuchsin  (certified 
as  suitable  for  the  Feulgen  stain) 
in  200  ml  boiling  distilled  water. 


NaCl 
NaHC03 
CaCl2 .  2H2O 
KCl 


NaHjPO^ • 


HjO 


Distilled  water 


6.5g 
0.2g 
0.  16g 
0.14g 
0.011  g 
1000  ml 


LABORATORY  DIAGNOSIS  OF  PROTOZOAN  INFECTIONS 


393 


Sheather's  Sugar  Solution 

Sucrose  (ordinary  cane  or  beet  sugar)  .    .    .    500  g 

Distilled  Water 320  g 

Phenol  (melted  in  water  bath) 6-  5  g 

Zinc  Sulfate  Flotation  Solution 

ZnS04.  7H2O 331  g 

Distilled  water 1000  ml 

The  specific  gravity  of  this  solution  is 
1.180. 

LITERATURE  CITED 

Balamuth,    W.     1946,     Am.   J.    Clin.   Path.      16:380-384. 
Blagg,    W.  ,    E.   L.    Schloegel,    N.   S.   Mansour  and  G.    I.    Khalaf. 

1955.     Am.   J.   Trop.   Med.    Hyg.     4:23-28. 
Boeck.    W.   C.   and  J.    Drbohlav.     1925.     Proc.   Nat.   Acad.    Sci. 

11:235-238. 
Craig,    C.    F.     1948.     Laboratory  diagnosis  of  protozoan  diseases. 

2nd  ed.     Lea  G  Febiger.    Philadelphia. 
Diamond.    L,    S.      1957.     J.   Parasit.     43:488-490. 
Faust,    E,    C,    ],    S,   D'Antoni,    V,    Odum,    M,   J,   Miller,    C. 

Peres,    W.    Sawitz    L.    F    Thomen,   ].    E.    Tobie  and  J.   H. 

Walker.      1938.     Am.   J.    Trop.   Med.     18:169    183. 
Fitzgerald,    P.    R.,    D.   M.   Hammond  and  J.    L.    Shupe.     1954. 

Vet.   Med.     49:409-412, 


Hewitt,    R     I,      1940.     Bird  malaria.     Am.   J.   Hyg.   Mon.    Ser. 

No.    15.     Johns  Hopkins  Press,    Baltimore. 
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APPENDIX 

Scientific  and  Common  Names 
of  Some  Domestic  and  Wild  Animals 


Class  MAMMALASIDA 

Order  MARSUPIALORIDA 

Dldelphis  marsupialis 

Order  PRIMATORIDA 

Alouatta  villosa 
Ateles  geoffroyi 
Cebiis  capucinus 
Ceropithecus  aethiops 
Cercopithecus  mona 
Gorilla  gorilla 
Homo  sapiens 
Macaca  irus 
Macaca  mulatta 
Macaca  pliilippinensis 
Maiidrillus  sphinx 
Pan  troglodytes 
Papio  papio 
Po)igo  pygniaeus    (syn. 

Order  EDENTATORIDA 

Dasypus  novemcinctus 

Order  LAGOMORPHORIDA 

Lepus  americanus 
Lepus  californicus 
Lepus  eiiropaeus 
Lepus  townsendii 
Oryctolagus  cuniculus 
Sylvilagus  floridanus 

Order  RODENTORIDA 


Apodemus  sylvaticus 
Cavia  porcellus 
Chinchilla  laniger 
Clethrionomys    spp. 
Cricetulus  barabensis  griseus 
Dipodomys    spp. 
Gerbillus  gerbillus 
Meriones  unguiculatus 
Mesocricetus  auratus 
Microtus    spp. 


Simla  satyrus) 


Opossum 


Howler  monkey 

Goeffroy's  spider  monkey 

Capuchin  monkey 

Green  guenon,  vervet  monkey 

Mona  monkey 

Gorilla 

Man 

Cynomolgus  macaque,  kra  monkey 

Rhesus  monkey 

Philippine  macaque 

Mandrill 

Chimpanzee 

Baboon 

Orang-utan 


Nine-banded  armadillo 


Snowshoe  rabbit 

Black-tailed  jack  rabbit 

European  hare 

White-tailed  jack  rabbit 

Domestic  rabbit,  European  wild  rabbit 

Eastern  cottontail 


Long-tailed  field  mouse  (European) 

Guinea  pig 

Chinchilla 

Red-backed  mice 

Chinese  (striped)  hamster 

Kangaroo  rats 

Lesser  Egyptian  gerbil 

Mongolian  gerbil,  clawed  jird 

Golden  hamster 

Voles 


395  - 


396 


APPENDIX 


Mus  musculus 
Neoloma  spp. 
Oryzomys  palustris 
Peromyscus  spp. 
Rattiis  )}iasto)nys 
Rattiis  norvegiciis 
Rattiis  rattiis 
Rlioiubomys  opimus 
Sciitnis  spp. 
Sigmodon  hispidus 
Spermophilus*  spp.   (syn. 
Citellus  spp. ) 


Domestic  mouse,  house  mouse 

Wood  rats 

Swamp  rice  rat 

Deer  mice 

Multimammate  mouse 

Norway  rat 

Black  rat 

Gerbil 

Tree  squirrels 

Cotton  rat 

Ground  squirrels,  susliks,  ziesels 


Order  CARNIVORIDA 


Alopex  lagopus 

Canis  dingo 

Canis  familiar  is 

Canis  latrans 

Canis  lupus 

Felis  catus 

Felis  concolor 

Lynx  canadensis 

Lynx  rufus 

Martes  ainericana 

Mephitis  mephitis 

Mustela  erminea 

Mustela  frenata 

Mustela  piitorius  furo 

Mustela  vison 

Panthera  leo 

Pa>ithera  tigris 

Procyon  lolor 

Spilogale  spp. 

Urocyon  cinereoargenteus 

Ursus  americanus 

Ursus  horribilis 

Vulpes  fulva 

Vulpes  vulpes 


Arctic  fox 

Dingo 

Dog 

Coyote 

Grey  wolf 

Domestic  cat 

Mountain  lion,  puma 

Lynx 

Bobcat 

Marten 

Striped  skunk 

Ermine 

Long-tailed  weasel 

Ferret 

Mink 

Lion 

Tiger 

Raccoon 

Spotted  skunks 

Grey  fox 

Black  bear 

Grizzly  bear 

Red  fox  (North  American) 

European  common  fox 


Order  PERISSODACTYLORIDA 


Asinus  asinus 
Equus  caballus 
Rhinoceros  unicornis 


Domestic  ass 

Horse 

Rhinoceros 


Order  ARTIODACTYLORIDA 


Suborder  SUIORINA 

Sus  scrofa 
Suborder  RUMINANTORINA 


Pig 


Aloes  alces 
Antilocapra  americana 


Moose 
Pronghorn 


APPENDIX 


397 


Bison  bison 

Bos  indicus 

Bos  taurus 

Bubalus  bubalis 

Bubalus  iSyncerus )  coffer 

Camelus  bactrianus 

Camelus  dromedarius 

Capra  hirciis 

Capreoliis  capreolus 

Cervus  canadensis 

Cervus  elaphus 

Dama  dania 

Dama  *  (syn. ,  Odocoileus ) 

liem  ionus 
Dama*  (syn. ,   Odocoileus) 

virginiana 
Lama  glama 
Mazama  americana 
Oreamnos  aniericanus 
Ovibos  moschatus 
Ovis  ammon 
Ovis  aries 
Ovis  canadensis 

Ovis  musimon 
Ovis  vignei 
Rangifer  tarandus 
Rupicapra  rupicapra 


Bison 

Zebu 

Ox 

Water  buffalo,  carabao 

African  buffalo 

Bactrian  camel,  two-humped  camel 

Dromedary,  one-humped  camel 

Domestic  goat 

Roe  deer 

Wapiti,  elk 

Red  deer  (European) 

Fallow  deer 

Black-tailed  deer,  mule  deer 

White-tailed  deer 

Llama 

Red  brocket 

Mountain  goat 

Musk  ox 

Argali 

Domestic  sheep 

Mountain  sheep.  Rocky  Mountain  big 

horn  sheep 
Mouflon 
Urial 

Caribou,  reindeer 
Chamois 


Order  PROBOSCIDORIDA 

ElepJias  indicus 
Loxodonta  africana 

Class  AVEASIDA 

Order  ANSERORIDA 

Anas  platyrhynchos 

Anser  anser   {Anser  cinereus) 

Anser  albifrons 

Branta  canadensis 

Cairina  moschata 

Cygnus  olor 

Order  GALLORIDA 


Indian  elephant 
African  elephant 


Domestic  duck,  wild  mallard 
Domestic  goose 
White-fronted  goose 
Canada  goose 
Muscovy  duck 
Swan 


Alectoris  graeca 
Bonasa  umbellus 
Colinus  virginianus 
Callus  gallus 
Meleagris  gallopavo 
Numida  meleagris 
Pavo  cristatus 
Perdix  perdix 
Phasianus  colchicus 


Chukar  partridge 

Ruffed  grouse 

Bobwhite 

Chicken 

Turkey 

Guinea  fowl 

Peafowl 

Grey  partridge 

Ring-necked  pheasant 


398 


APPENDIX 


Order  COLUMBORIDA 

Columba  fasciata 
Columha  livia 
Streptopelia  chinensis 
Streptopelia  risoria 
Streptopelia  turtur 
Zenaidura  macroura 

Order  PASSERORIDA 

Passer  domesticus 
Seriniis  canarius 

Order  STRUTHIONORIDA 
Strut  hio  came  his 


Band-tailed  pigeon 
Domestic  pigeon 
Spotted  dove 
Ringed  turtle  dove 
Turtle  dove  (European) 
Mourning  dove 


English  sparrow 
Canary 


Ostrich 


The  generic  names  Spermophilus  and  Dama  were  acceoted  rather  than  the  more  usual  Citellus  and  Odocoileus,   respectively, 
by  E.  R.   Hall  and  K.   R.   Kelson  (19S9,     The  mammals  of  North  America.     2  vols.     Ronald  Press,   New  York).     Their  book 
was  seen  too  late  for  their  usage  to  be  incorporated  in  the  text  of  the  present  volume. 


Index  and  HoshParasite  Lists 


(Numbers  in  italics  refer  to  illustrations) 


Aberrant  parasite,  definition,  5 
Abortion,  trichomonad,   84 
Acantliamoeba,  29,   131 

gallopavonis ,  131 

hyaliim,    131 

sp.  from  tissue  cultures,  131 
Accessory  filament,  definition,  82 
Achromaticus ,  see  Babesia 

gibsoni,  see  Babesia  gibsoni 
Acinetidae,  35,  366 
Adaptation  to  parasitism,   10 
Adelea,  247 
Adeleicae,  30 
Adeleidae,  30 
Adeleorina,  30,  254 
Adelina,  247 

Adoral  membranelle  zone,  defini- 
tion, 351 
Aegyptianella ,  33,  303 

moshkovskii,  304 

pullorum ,  303 
Aegyptianellosis,  303 
African  Coast  fever,  306 
African  human  trypanosomosis,   50 
Agamont,  definition,   21 
Ageledeme,  definition,  9 
Aggregatidae,  32,  246 
Albumen  fixative,  Mayer's,  391 
Aleppo  button,  69 
Allantosoma ,  35,  366 

brevicorniger ,  363,   366 

dicorniger,  363,   366 

intestinalis ,  363,   366 
Alloiozona,   34,   362 

trizona,  362,  363 
Alphamonas ,  see  Spiromonas 
Ameba  gallopavonis ,  see  Acantlia- 
moeba gallopavonis 
American  human  trypanosomosis,  58 
Amoeba  bonis,  see  Entamoeba 
bovis 

buccalis,  see  Entamoeba  gingi- 
valis 

coll,  see  Entamoeba  coli, 
E.  histolytica 

dentalis ,  see  Entamoeba  gingi- 
valis 

dysenteriae ,  see  Entamoeba 
histolytica 

gingivalis ,  see  Entamoeba 
gingivalis 

kartulisi,  see  Entamoeba 
gingivalis 

Umax,  see  Endolimax  nana 

muris,  see  Entamoeba  maris 
Amoebidae,  29,   131 
Amoeborida,  29,   130 
Amoebosis,  136 
Ampliacanthus ,   38 
Amphimonadidae ,  27,   124 
Ampullacula,  34,  364 

ampulla,  363,  364 


Anaplasma,  24 

Anas  platyrhynchos,   parasites  of 
Flagellates 

Cochlosoma  anatis,    114 
Hexamita  sp.,   117 
Protricliomonas  a>iatis,  109 
Tricliomonas  anatis,   102 
Tritricliomonas  eberthi,  94 
Amoebae 

Endolimax  gregariniformis , 

154 
Entamoeba  anatis,  143 
gallinarum  (?),  145 
Telosporasids 

Elmer ia  anatis,  233 

truncata,  230 
Haemoproteus  nettionis,21Z 
Leucocytozoon  simondi, 275 
Tyzzeria  perniciosa,  243 
Piroplasmasids 

Aegytianella  pullorum,  303 
Toxoplasmasids 

Sarcocystis  rileyi,   324 
Ancyromonas  ruminantium,   see 

Selenomonas  mm  inantium 
Anisogamy,  definition,   22 
Anser  anser,   parasites  of 
Flagellates 

Trichomonas  anseri,  102 
Amoebae 

E)idoUmax  gregariniforni  is , 

154 
Entamoeba  gallinarum  (?), 
145 
Telosporasids 

Eimeria  anseris,  231 
nocens,  232 
parvula,  233 
truncata,  230 
Haemoproteus  nettionis.2T3 
Leucocytozoon  simondi.  275 
Tyzzeria  anseris.  244 
Piroplasmasids 

Aegyptianella  pullorum.  303 
Apiosoma  bigeminum,   see  Babesia 

bigemina 
Arcellidae,  29,   130 
Astasiidae,  25,   126 
Axoneme,  definition,  20 
Axopod,  definition,  20 
Axostyle,  definition,  82 

Babesia,  33,   286 

ardeae,  see  Aegyptianella  mosh- 
kovskii 
argentitm,  295 
berbera,  294 

bigemina,  287,  288,  291,  292 
bovis,  287,   288,  291,  293 
caballi,  298 
canis,  286,  287,  300 
divergens,  291,  295 


see  B.  bigemina 


equi,   298 

felis,   303 

foliata.   297 

gibsoni,  302 

Imdsonius  bovis 

major,  296 

major,   see  also  B.  vogeli 

moshkovskii,  see  Aegyptianella 

moshkovskii 
motasi,  296 
ovis,  297 
perroncitoi,  300 
rossi,  see  B.  canis 
sergenti,  see  GoMeria  ovis 
taylori,  297 
trautmanni,  299 
vitalii,   see  B.  ca«iS 
vogeli,   289,  302 
Babesiella,   see  Babesia 

berbera,   see  Babesia  berbera 
bovis,  see  Babesia  bovis 
felis,  see  Babesia  felis 
gibsoni,   see  Babesia  gibsoni 
major,  see  Babesia  major 
ovis,   see  Babesia  ovis 
perroncitoi,   see  Babesia  per- 
roncitoi 
Babesiidae,  33,  285 
Babesiosis 

n  the  ass,  298 
n  the  cat,  303 
n  the  dog,   300,   302 
n  the  goat,   296,  297 
n  the  horse,   298 
n  man,  295 

n  the  ox,  292,  293,  294,  295,  296 
n  the  pig,   299,   300 
n  the  sheep,  296,  297 
n  the  water  buffalo,  292 
n  the  zebu,   292,   293,   294 
Balantidiidae,   36,  371 
Balantidiosis,   372 
Balantidium,   36,   371 

in  cattle,  see  Buxtonella  sulcata 

coli,   372,  372 

minutum,  see  Balantiophorus 

minutus 
suis,   see  Balantidium  coli 
Balantioplwrus ,   375 

minutus,   375 
Balbiania,   see  Sarcocystis 

gigantea,   see  Sarcocystis  tenella 
rileyi,   see  Sarcocystis  rileyi 
Balfouria  anser i>M,   see  Aegyptianella 
pullorum 

gallinarum,  see  Aegyptianella 
pullorum 
Bartonella,  24 

Basal  granule,  definition,  20 
Besnoitia,  33,  337 
bennetti,  339 
besnoiti,  337 


399 


400 


INDEX 


Besnoitia  (Continued) 
jelUsoni,    340 
tarandi,  340 
Besnoitiosis,   337 
Biliary  fever,  canine,   300 
Binary  fission,  definition,  21 
Binomial  nomenclature,  definition, 

14 
Biological  vector,  definition,   5 
Blackhead,  74 
Blastocrithidia,  26,  41 
Blastocystis,   75,  84,  377 
Blepharoconus ,  35,  364 
benbrooki,  363,  364 
cervicalis,  363,  364 
hemiciliatus ,  363,  364 
Btepluirocorys,   35,  366 
angiista,  363,  367 
cardionucleala,  363,  367 
curvigula,  363.  367 
jubata,  363.    367 
uncinata,  367 
valvata,  363,  367 
Blepharocorythidae,   35,   366 
Blepharoplast,  definition,   20 
Blepliaroprosthium,  35,  364 

pireum,  363,   364 
Blepliarospliaera,   35,  364 
ellipsoidalis ,  363,   364 
intestinalis,  363,  364 
Blepharozoum,    35,   364 
zonatum,  363,    365 
Blood,   technics  for  microscopic 

examination,   384 
Blood  smears,  preparation,  384 
Borfo,  27,    122 

caudatus,    123 
/oe/MS,  88,   123 
glissans,    88,    123 
Bodonidae,   26,    122 
Sos  indicus,   parasites  of 
Flagellates 

Callimastix  frontalis.   113 
Monocercomonas  niniinan- 

tiiim,   108 
Oikomonas  communis ,  125 
Protrichomonas  rutn  inan- 

tium.  109 
Selenomonas  ruminantium, 

113 
Tritricliomonas  enteris,  93 

/oe/)<s,   84,  91 
Trypanosoma  brucei,  47 
congolense,    54 
diniorphon,    56 
evansi,  51 
theileri,  62 
uniforme,   58 
vivax,    57 
Amoebae 

Entamoeba  bovis,  134,  145 
Telosporasids 

Eimeria  bombayansis.  175 
bovis,   168 
brasiliensis,    170 
bukidnonensis,  171 
canadensis,  171 
cylindrica,  172 
ellipsoidalis,    172 


mundaragi,    175 
zurnii,    174 

Isospora  sp. ,   235 
Piroplasmasids 

Babesia  berbera,  294 
bigemina,  287,   288, 

292 
6ot;is,  287,   288,   293 

Gonderia  ammlata,    309 
lawrencei,    312 
mutans,    311 

Theileria  parva,  306 
Toxoplasmasids 

Besnoitia  besnoiti,  337 

Sarcocvs/iS  fusiformis. 
323 
Ciliates 

Buetschlia  neglecta,  349 
parva,  349 

Buxtonella  sulcata,    350, 
372 

Dasxtriclia  ruminantium., 
350 

Diplodinium  a>mcanthutn, 
354 

bubalidis,    355 
dentatum ,    3  54 
flabellum,   356 
psittaceum,   355 
quinquecaudatum,  354 

Diploplastron  affine,    357 

Elytroplastron  bubali,  358 

Entodiniuni  aculeatum ,  353 
acutonucleatum.  353 
actitum,  353 
bicari>mlum,  352 
biconcavum,  353 
bifidum ,    3  53 
bimastus,  353 
brevispinum .  353 
bursa,  352 
caudaturn,  352 
dentatum,  352 
dubardi,  353 
ellipsoideum,    353 
exiguum,  353 
furca,  352 
gibberosum.  353 
indicum.  353 
laterale,   353 
laterospinum,    353 
lobospinosum,    352 
longinucleatum,  353 
minimum ,  352 
nanellum,  353 
ovoideum.  353 
pisciculum,    353 
rectangulatum,  352 
rlwmboideum,  353 
rostratum,  353 
simulans,  353 
tricostatum,  353 
i^ora.v,    353 

Eodinium  bilobosum,  354 
lobatum,  354 
posterovesiculatum, 
354 

Epidinium  ecaudatum,  353 

Eremoplastron  bovis,  356 


brevispinum,    356 
dilobum,    356 
magnodentalum ,  356 
monolobum,  356 
neglectum,  356 
rostratum,  356 
rugosum,  356 
Eudiplodinium  maggii,  357 
Isotriclm  intestinalis,  350 

prostoma,  350 
Metadinium  medium,  357 
tauricum,  357 
ypsilon,  357 
Ophryoscolex  caudatus, 
351 
purkinjei,  351 
Ostracodiniuni  clipeolum, 
359 

crassum,  358 
dilobum,  359 
gladiator,  358 
gracile,  358 
mammosum,  358 
nanutn,  358 
obtusum,  359 
quadrivesiculatum, 

358 
rugoloricatum ,    359 
tenue,    358 
trivesiculatum,    358 
venustum,  359 
Polyplastron  fenestratum, 
357 

monoscutuyn,  357 
multivesiculatum,  357 
Bos  taurus,  parasites  of 
Flagellates 

Callimastix  frontalis,   113 
Giardia  bovis,    121 
Monocercomonas  rum inan- 

tiutn,   108 
Oikomonas  communis ,  125 

minima,    125 
Protricliomonas  ruminan- 
tium, 109 
Selenomonas  ruminantium, 

113 
Spliaeromonas  communis, 

125 
Tricho»ionas  pavlovi,    97 
Tritricliomonas  enteris, 
93 

/oe/MS,    84,  91 
sp.,  93 
Trypanosoma  brucei,   47 
congolense,    54 
dimorphon,  56 
evansi,  51 
theileri,  62 
uniforme,    58 
fu'a.r,    57 
Amoebae 

Entamoeba  bovis,  134,  145 
histolvtica  (?),  135, 
136 
Telosporasids 

Eimeria  alabamensis.  166 
auburnensis,  167 
bovis,    168 


INDEX 


401 


Bos  taurus     (Continued) 

brasiliensis.  170 
bukidnonensis.  171 
canadensis.   171 
cylindrica,   172 
ellipsoidalis.    172 
pellita.    173 
subspherica,   173 
zurnii.   174 

Isospora  aksaica.   235 
sp. ,   235 
Piroplasmasids 

Babesia  argentina.   295 
berbera.  294 
bigemina.   287,   288, 

292 
ftoi'/s,    287.   288,   293 
divergens.    29  5 
major,   296 

Gonderia  annidata.    309 
lawrencei,  312 
mutans.   311 

Theileria  parva.  306 
Toxoplasmasids 

Besnoitia  besnoiti,  337 

Sarcocystis  fusiform  is. 323 

Toxoplasma  gondii.   325 
Ciliates 

Buetschlia  lanceolata.  350 
neglecta.  349 
parva.  349 

Buxtonella  sulcata.  350, 
372 

Dasvtricha  ruminantium , 
350 

Diplodinium  anacanthum, 
354 

bubalidis.   355 
dentatiim.  354 
elongatum.  355 
psittaceum.  355 
quinquecaiidatum .   354 

Diploplastron  affine.  357 

Enoploplastron  triloricatum. 
359 

Entodinium  bicarinatum, 
352 

bimastus.  353 
bursa.  352 
caudatum .  352 
dentatum .  352 
dubardi.  353 
exiguum.  353 
furca.  352 
laterale.   353 
lobospinosum,   352 
lo)iginucleatum .  353 
minimum.   352 
nanellutn,   353 
rectangulatum.  352 
rostratum.   353 
simulans.  353 
Dorax,   353 

Eodinium  bilobosiim.   354 
/>os  teroves  iculatum . 
354 

Epidinium  ecaudatum.   353 

Eremoplastron  bovis.  356 
dilobum.   356 


monolobum.  356 
neglecturn.   356 
rostratum.  356 
rugosum.   356 
Eudiplodinium  maggii,  357 
Isotricha  intestinalis,  350 

prostoma.   350 
Metadinium  medium.   357 
tauricum.   357 
ypsilon.  357 
Ophryoscolex  caudatus.  351 
inermis.  351 
purkinjei,  351 
Ostracodinium  crassum . 
358 

dilobum.   359 
dogieli.  359 
gladiator.   358 
gracile,  358 
mammosum .    358 
monolobum.   359 
nanum.   358 
obtusum.   359 
tenue,   358 
Polyplastron  fenestratum , 
357 

monoscutum ,  357 
multivesiculatum .  357 
Buba,   69 

Bubalus  bubalis,  parasites  of 
Flagellates 

Trypanosoma  evansi,  51 
Amoebae 

Entamoeba  bubalus.  147 
Telosporasids 

Eimeria  bovis.    168 
ellipsoidalis.  172 
zurnii.  174 
Piroplasmasids 

Babesia  bigemina.   287, 

288,   292 
Gonderia  annulata.   309 
Theileria  parva.  306 
Toxoplasmasids 

Sarcocystis  fusiformis.  323 
Ciliates 

Buxtonella  sulcata,  350, 

372 
Diplodinium  bubalidis,  355 
Elytroplastron  bubali.  358 
Buccinum  undalum.   246 
Budding,  definition,   21 
Buetschlia.  35,  349 
lanceolata,  350 
«awa.  350 
neglecta.  349 
omnivora,  350 
/)art;a,   349,   349 
Buetschliidae,   34,   348,   362 
Buffalo  disease,  312 
Buffer  solution,   Balamuth's,   392 
Buffers,  S^if'rensen's  phosphate,  392 
Bundleia.  34,   365 

postciliata,  363.   365 
Buxtonella,  35,   350 
sulcata,  350,  372 

Callimastigidae,  27,    112 
Callimastix,  27,   112 


e^Mi,   113 
frontalis.  113 
Cants  fam maris,  parasites  of 
Flagellates 

Giardia  canis.    120 
Leishmania  donovani.   66 

tropica.  69 
Pentatrichomonas  hominis, 

103 
Triclwmonas  canistomae,9Q 
Trypanosoma  bridcei,  4^,4^ 
congolense,  45,   54 
cruzi,  43,   58 
dimorphon,   45,    56 
evansi,    46,    51 
rangeli,  43,  62 
Amoebae 

Entatnoeba  caudata.    149 
gingivalis.    148 
histolvtica.  134,  135, 
136 
Telosporasids 

Eimeria  canis,  195 

ca/i,  195 
Hepatozoon  canis.   256 
Isospora  bigemina,  164,  237 
/e//s,   238 
rivolta,   239 
Piroplasmasids 

Babesia  canis. 286,  287,  300 
gibsoni,   302 
w^eZ/.   289,   302 
Encephalitozoon  cuniculi, 

341 
Toxoplasma  gondii,  325 
Ciliates 

Balantidium  coli,  372 
Capitulum,  definition,  82 
Capra  hircus.  parasites  of 
Flagellates 

Callimastix  frontalis,  113 
Cercomonas  faecicola,  123 
Chilomastix  caprae,  112 
Giardia  caprae,    121 
Monocercomonoides  caprae, 

114 
Oikonionas  communis,    125 
Selenomonas  ruminantium, 

113 
Sphaeromonas  communis, 

125 
Trypanosoma  brucei.  47 
congolense,   54 
dimorphon,   56 
evansi.  51 
theodori.   63 
uniform e,   58 
vivax,    57 
Amoebae 

Entamoeba  caprae.   151 
dilimani.   146 
oyis,   145 
wenyoni,   143 
Telosporasids 

Eimeria  arloingi,   180 
faurei,   182 
gilruthi,   182 
ninakohlyakimovae ,  184 
parva,   186 


402 


INDEX 


Capra  hircus  (Continued) 
Piroplasmasids 

Babesia  molasi,  296 
ovis,  297 
taylori,  297 
Gonderia  hirci.  313 
ovis,  314 
Ciliates 

Dasvtriclia  ruminantium . 

350 
Diplodinium  cristagalli.  356 

laeve,  356 
Diploplastron  a/fine.  357 
Entodiniutn  spp.  ,   351 
Epidinium  ecandatum .  353 
Isotricha  inteslinalis,  350 

prostoma.  350 
Metadinium  taiiricum.   357 
Ophryoscolex  inermis.  351 
Carabao,   see  Biibalus  bubalis 
Carrier,  definition,  4 
Cat,  domestic,  see  Fells  caliis 
Catarrhal  enteritis,  infectious,   115 
Cattle,   see  Bos  indicus.   Bos  taurtis, 

Bubalns  bubalis 
Cavia  porcellus.    parasites  of  (in- 
complete list) 
Flagellates 

Caviomonas  mobilis.   125 
Chilomastix  intestinalis , 
112 

wenrichi.   112 
Chilomitus  caviae.   109 

conexus.   109 
Giardia  caviae.   122 
Hexamastix  caviae,   109 

robustus,    109 
Monocercomonoides  caviae, 
114 

exilis,    114 
quadrifunilis,    114 
wenrichi,  114 
Proteromonas  brevifilla, 

124 
Selenomonas  palpitans,  113 
Sphaeromonas  communis, 

125 
Tritrichomonas  caviae,  94 
sp.,  94 
Amoebae 

Endollmax  caviae.    154 
Entamoeba  caviae,    144 
Telosporasids 

Klossiella  cobayae,  255 
Caviomonas.  24,    125 

mobilis.    125 
Cercaria  tenax.   see  Trichomonas 

tenax 
Cercomonas.  27,   123,    i23 
crassicauda,  88,   123 
eijMi,  123 
faecicola,  123 
gailinae,   see  Trichomonas 

gallinae 
heimi,    123 
hepaticum.    see  Trichomonas 

gallinae 
hominis,  see  Pentatrichomonas 
horn  inis 


intestinalis,  see  Giardia  lamblia 

longi  Cauda,    123 

sp.  of  ox  and  pig  feces,   123 
Chagas'  disease,   58 
Cliaron,  see  Cliaronitm 
Charonim.    35,  367 

e?!/!,  .?65.  367 
Chicken,  domestic,  see  Gallus  gallus 
Chiclero  ulcer,  69 
Chilodonella,  374 
Chilomastix,   27,    11       ii2 

bettencourti,    112 

caprae,   112 

cuniculi,   112 

gallinarum.   112 

hominis.  see  C.  mesnili 

intestinalis.  112 

mesnili.     111 

SMis.  see  C.  mesnili 

wenrichi,   112 
Chilomitus.  28,   109 

caviae,   109 

conexus.   109 
Chimpanzee,  see    Pa«  troglodytes 
Chinchilla  laniger,    parasites  of 

Flagellates 

Giardia  chinchillae .    122 

Amoebae 

Entamoeba  sp. ,   151 

Toxoplasmasids 

Toxoplasma  gondii,  325 
Chlamydomonadidae,   26 
Chlamydophrys.    29,    130 

stercorea,   130 
Chromatic  ring,  definition,   82 
Chromatophore,  definition,   21 
Chromulina,   125 
Chromulinidae,   24,   125 
Chrysomonadorida,   24,    124 
Ciliasida,  34,   347 
Cilium,  definition,   20 
Cirrus,  definition,  20 
Classification  of  Protozoa,   23 
Cnidosporasida,  34 
Coccidiasina,  30,    158 
Coccidiosis 

in  the  ass,    194 

in  the  cat,    195,   237 

in  cattle,   166,  235 

in  the  chicken,  202,   242,   245 

in  the  dog,    195,   237 

in  ducks,   230,   233,    243 

in  the  goat,   180 

in  the  goose,   230,  244 

in  the  horse,    194 

in  man,    241 

in  the  ox,    166,   235 

in  the  pig,    190,   236,   246 

in  the  pigeon,   233 

in  the  rabbit,    196 

in  sheep,    179 

in  the  turkey,   222,    243,   246 

in  the  water  buffalo,   168 

in  the  zebu,   166,   235 
Coccidium  bigeminum .  see  Isospora 
bigemina 

bigeminum  var.  cati,    see 
Isospora  felis 

bigeminum  var.  hominis,  see 


Isospora  hominis 
bovis,  see  Eimeria  bovis 
cuniculi,  see  Eimeria  stiedae 
globosum,  see  Eimeria  tenella 
oviforme,  see  Eimeria  stiedae 
perforans ,    see  Eimeria  per- 

forans 
pfeifferi,  see  Eimeria  labheana 
rivolta,  see  Isospora  rivolta 
tenellum,    see  Eimeria  tenella 
truncatum ,  see  Eimeria  trun- 
cata 
Cochliatoxum.     38,   371 

periachtum,   369,  371 
Cochlosoma,   28,    114 
anatis,    114 

rostratum.  see  C.  anatis 
sp.  of  turkeys,   114 
Cochlosomatidae,   28,   114 
Colpidium,  374 
Columba  livia.  parasites  of 
Flagellates 

Hexamita  columbae,  117 
Trichomonas  gallirute,  98 
Trypanosoma  liannai,  64 
Telosporasids 

Eimeria  columbae,  235 

labbeana,   233 
Haeynoproteus  columbae, 
271 

sacharovi,   273 
Leucocvtozoon  marchouxi. 

281 
Plasmodium  relictum,   269 
Toxoplasmasids 

Toxoplasma  gondii.  325 
Commensalism,  definition,  4 
Conjugation,  definition,   22 
Conoid,  definition,   319 
Contractile  vacuole,  definition,  21 
Copromastix  prowazeki,    see  Tetra- 

mitiis  rostratus 
Copromonas,    25,   126 

ruminantium,    see  C.  subtilis 
subtilis.   123.  126 
Coprophilic,  definition,   2 
Coprophilic  Protozoa 
Flagellates 

Bodo  caudatus.    123 
Cercomonas  crassicauda, 
88,   123 

faecicola.    123 
heimi.    123 
longi  Cauda.    123 
sp. ,    123 
Copromonas  subtilis.   126 
Monas  ohliqua  (?),   88 

sp. ,    126 
Pleuromonas  jaculans.  124 
Polvtoma  uvella  (?),   88, 

126 
Scytomonas  pusilla  {?),    126 
Spiromonas  angiista.  88, 

124 
Tetramitus  rostratus.   110 
Trepomonas  agilis.    122 
Tritrichomonas  fecal  is. 93 
Amoebae 

Acanthamoeba  hyalina,  131 


INDEX 


403 


Coprophilic  Protozoa  (Continued) 

Chlamydophrys  stercorea , 

130 
Entamoeba  moshkovskii, 

142 
Naegleria  gruberi,   130 
Sappinia  diploidea,   132 
Triniastigamoeba  philip- 

pinensis,    131 
Vahlkampfia  lobospinosa, 
133 

punctata.    132 
sp. ,    133 
Ciliates 

Balantiophorus  minutus, 

375 
Chilodonella   sp. ,   374 
Colpidium  sp. ,   374 
Cyclidium  sp. ,   374 
Nyctotherus  faba,  375 
sp.,   375 
Coprozoic,  definition,   2 
Corn-meal  disease,   340 
Corridor  disease,   312 
Costa,  definition,  82 
Councilmania  decumani,    see  Enta- 
moeba muris 

lafleuri,    see  Entamoeba  colt 
muris,    see  Entamoeba  muris 
tenuis,    see  Endolimax  nana 
Counterstaining,  381 
Crithidia,  26,   41 
Crithidial  form,  definition,  41 
Cryptosporidiidae,  32,    159,   244 
Cryptosporidium,  32,   245 
meleagridis,  246 
parvum,    245,   246 
tyzzeri,  211,   212,    245 
sp.  of  the  rabbit,  246 
Cryptozoite,  definition,   260 
Culture  medium,   Balamuth's,  389 
BGPS,  390 
CPLM,  390 
Diamond's,  390 
NNN,   387 

Ringer's-egg-serum,   388 
Ringer's-serum-starch,  391 
Tobie,  von  Brand  &  Mehlman's 

trypanosome,  388 
Weinman's  trypanosome,  387 
Cunhaia,  38 
Cyathodiniidae,   35 
Cyathodinium,   36 
Cyclidium,    374 
Cycloposthiidae,  38,  348,  368 
Cycloposthium,  38,  368 
affinae,  370 
bipalmatum,    368,  369 
corrugatum,  370 
dentiferum,   368 
edentatum,    368,369 
ishikawai,   368 
piscicauda,   368 
scutigerum,  369,   370 
Cyst,  definition,   22 
Cytauxzoon,    33,  306 
Cytomere,  definition,  272 
Cytophanere,  definition,  318 
Cytopharynx,  definition,  21 


Cytopyge,  definition,   21 
Cytospermium  zurnii,  see  Eimeria 

zurnii 
Cytostome,   definition,   21 

Dasytriclia,    36,  350 

niminantium,  349,   350 
Definitive  host,  definition,   5 
Delhi  boil,  69 
Deme,   definition,   9 
Derrengadera,   51 
Didesmis,  34,   365 

ovalis,  363,  365 

quadrata,  363,  365 

spiralis,  363,   365 
Dientamoeba,   29,   129,    154 

fragilis,  150,  154 

sp.  of  sheep,    154 
Diffuse  nidus,  definition,  9 
Dimastigamoeba  gruberi,    see 

Naegleria  gruberi 
Dinoflagellorida,   25 
Diplocercomonas  soudanensis,  see 

Enterotnonas  hominis 
Diplodinium.   38,   354 

anacantlmm,  354 

bubalidis,  355 

clevelandi,  see  Eremoplastron 
bovis 

cristagalli,    356 

dentatum,    354,  355 

ecaudatum ,  see  Epidinium. 
ecaudatum 

elongatum,  355 

flabellum,  356 

hegneri,  see  Ostracodinium 
obtusum 

helseri,  see  Eremoplastron 
rostratum 

laeve,    356 

psittaceuni,  355 

quinquecaudatum ,  3 54 
Diploplastron,  38,  357 

affine,  357 
Ditoxum,  38,   371 

funinucleum,  369,  371 
DitriclwmotMS ,  83,    104 

Ofis,  104 
Dog,  see  Canis  familiaris 
Dorisiella,  31 
Dourine,    53 
Duck,  domestic,   see  ^««s  platyr- 

hynclws 
Dum-dum  fever,  66 
Dysentery,  amoebic,   136 

balantidial,  372 

East  Coast  fever,   306 
Echinozoon,    33,   286 
Economic  importance  of  parasites,  13 
Ectoparasite,  definition,   5 
Egyptian  fever,  bovine,  309 
Eimeria,  31,   160,   160,   166 

acervulina,  163,   207,  211, 
212,  213 

adenoeides,  226 

aemula,  see  E.  faurei 

agnosia,    see  E.   intestinalis 

ahsata,    179 


alabamensis,    166,  i76 

awa/is,    233 

anseris,  231 

arloingi,  180,    iSS 

auburnensis,   167,  i76 

avium,    see  E.  tenella 

boehmi,  see  £.  brasiliensis 

bombayansis,   175 

bovis,    162,    168,  i76 

bracket i,    see  £.  tenella 

brasiliensis,  170 

brumpti,    see  £.  debliecki 

brunetti,    205,  2J5 

bukidnonensis,    171,  i76 

canadensis,    171,  i76 

canis,   195 

ca/j,  195 

coecicola,    162,   199 

columbae,  235 

columbarutn,  see  £.  labbeana 

crandallis,    181 

cylindrica,   172,   i76 

debliecki,   190 

dispersa,  225 

ellipsoidal  is,    172,  i76 

elongata,   200 

exigua,  see  £.  perforans 

faurei,   182,  iSS 

/e/i«a,   196 

flavescens,  see  £.  media 

gallopavonis ,  226 

galouzoi,   see  £.    ninakohlyaki- 
movae,  E.  parva 

gilruthi,  182 

granulosa,   183,  iSS 

Itagani,  210 

Iwnessi,   see  £.  punctata 

ildefonsoi.    see  £.  auburnensis 

innocua,  228 

intestinalis,   200 

intricata,    183,  iSS 

irresidua,  198 

jalina,  see  £.  debliecki 

kliurodensis,   see  £.  bukidno- 
nensis 

labbeana,   233,  254 

leuckarti,    194 

lugdunumensis,   see  E.  perfor- 
ans 

magna,  162,   197 

matsubayashii,    200 

maxima,    163,   208,  2iJ,  2i2, 
2i3 

werfic,    162,    198 

meleagridis,  222 

meleagrimitis,    223 

Wito,    209,  2ii,  2i2,  2i3 

miyairii,  162 

mundaragi,  175 

necatrix,    161,   163,  204,  2ii, 
2i5 

neoleporis,    199 

neoleporis,   see  also  £.  elongata 

nieschulzi,  160,   162,   163 

ninakohlyakimovae,    184,  iSS 

nocens,  232 

orlovi,    see  £.  brasiliensis 

pallida,    186,   iSS 

/)art^a,    186,  iSS 


404 


INDEX 


Eimeria   (Continued) 
parvula,    233 
pellita,    173 
perforans,    197 
perforans  var  magna,   see 

E.  magtta 
perminula,    191 
pfeifferi,  see  E.  labbeana 
piriformis,    199 
piriformis,    see  also  £.  intes- 

tinalis 
polita,    192 
praecox,    210 
punctata,  187 
scabra,    192 
scrofae,  192 
separata,    162 
smithi,  see  £.  ftofis 
solipedum ,  194 
spinosa,    193 
stiedae,    196 
subrotunda,  229 
subspherica,    173,  i76 
SMis,  see  £.  debliecki 
tenella,    160,  i6i,    162,    163, 

164,    165,    166,   202,    2ii,    ^i^, 

ihianethi,  see  £.  bovis 

truncata.    230 

uniungulati,    195 

utinensis,   see  Klossiella  equi 

wyomingensis,   see  £.  bukidno- 
nensis 

zurnabadensis,   see  £.  cana- 
densis 

zurnii,   164,    174,    i76 
Eimeriidae,  31,   159 
Eimeriorina,  31,    158,   159,    i59 
El  debab,   51 

Elementary  nidus,   definition,   9 
Elepliantophilus ,    38 
Elylroplastron,    38,  357 

bubali,  358 
Embadomonas,  see  Retortamonas 
Enceplmlitozoon,   34,   341 

cuniculi,   341 

negrii,    see  £.  cuniculi 
Endamoeba,  29,   133 

blattae,    133 

co/i,  see  Entamoeba  coli 

gedoelsti,   see  Entamoeba 
gedoelsti 

histolytica,   see  Entamoeba 
histolytica 

hominis,   see  Entamoeba  coli 
Endamoebidae,   29,   133 
Endodyogeny,  definition,   22 
Endoliinax,  29,    152 

caviae,    154 

cynomolgi,   see  £.  /za;w 

gregariniformis,   150,  154 

intestinalis,   see  £.  >ia/w 

janisae,   see  £.  gregariniformis 

kueneni,   see  lodamoeba  buet- 
schlii 

nana,  150,    152 

numidae,   see  B.  gregarini- 
formis 


pileonucleatus,   see  lodamoeba 
buetschlii 

ratti,  153 

SMis,  see  £.  «ana 

williamsi,  see  lodamoeba  buet- 
schlii 
Endoparasite,  definition,   5 
Endosome,  definition,   19 
Enoploplastron,   38,  359 

triloricatum ,   359 
Entamoeba,  29,   133 

amtis,    134,   143 

ftoyis,    134,  i57,    145 

bubalus,    134,    147,  i50 

buccalis,    see  £.  gingivalis 

canibuccalis,  see  E.  gingivalis 

caprae,    151 

caudata,    135,   149,  i50 

caviae,    134,   144 

chattoni,    134,   147,  i50 

cobayae,  see  £.  caviae 

coli,  133,    134,    i57,    143 

cuniculi,    134,   144 

debliecki,  see  £.  ofzs,  £.  swis 

dilimani,    134,  i57,    146 

dispar,   see  £.  histolytica 

equi,  134,    143 

equibuccalis,    135,    149,  i50 

gallinarum,     134,  iJ7,    145 

gedoelsti,    135,    149,  i50 

gingivalis,    135,    148,  i50 

gingivalis  var.  e^wi,  see 
£.   equibuccalis 

hartmanni,    134,  135,  i57,  142 

histolytica,    134,   135,   136,  i37 

maxillaris,  see  £.  gingivalis 

moshkovskii,    134,   142 

muris,    134,    144 

nana,   see  Endolimax  twna 

ovis,     134,  i37,   145 

polecki,   see  £.  sm/s,  £.  cliat- 
toni 

suigingivalis,    135,    149 

SMis,    134,  i57,    146 

tetragena,   see  £.  histolytica 

venaticum,  see  E.  histolytica 

wenyoni,   134,    143 

williamsi,  see  lodamoeba  buet- 
schlii 

sp.  from  chinchilla,   151 
Enterohepatitis,   infectious,  74 
EnteromotMS,    27,   110,  iiO 

bengalensis,  see  £.  hominis 

liominis,  110 

S(((s,  110 
Entodiniorida,  37,   348 
Entodinium,  38,  351 

aculeatum ,   353 

acutonucleatum,    353 

acutum,    353 

bicarinatum,  349,    352 

biconcavum,   353 

bifidum,    353 

bimastus,    353 

brevispinum,   353 

6!<rsa,  3/9,    352 

caudatum,  349,  352 

dentatum,   352 


dubardi,   353 
ellipsoideum,   353 
exiguum,    353 
/M>-ca,  349,   352 
gibberosum,   353 
indicum,   353 
laterale,   353 
lalerospinum,    353 
lobospinosum,   352 
longinucleatum,  353 
minimum,  349,    352 
nanellum,    353 
ovoideum,  353 
pisciculum,    353 
r e  c  /a/igi<  to  /m  w ,    352 
rhomboideum,    353 
rostratum,  353 
simplex,   see  £.  dubardi 
simulans,    353 
tricostatum,   353 
forajf,  353 

spp.  in  sheep  and  goat,  351 
Eodinium,   38,   354 
bilobosuni,  354 
lobatum,  354 
posterovesiculatum,   354 
Eperythrozoon,    24 
Epidinium,    38,   353 

ecaudatum,  349,    353 
Epiplastron,    38 
Equus  caballus,   parasites  of 
Flagellates 

Callimastix  equi,    113 
Cercomonas  equi.    123 
Giardia  equi,    121 
Leishmania  donovani,  66 
Oikomonas  equi,  125 
Triclwmonas  equibuccalis, 

95 
Tritricliomonas  equi,  93 

/oe/!<s  (?),  84,  91 
Trypanosoma  brucei,  47 
congolense,    54 
dimorphon,  56 
equinum,  53 
equiperdum,  53 
evansi,    51 
vivax,    57 
Amoebae 

Entamoeba  equi.    143 
equibuccalis,  149 
gedoelsti,    149 
Telosporasids 

Eimeria  leuckarti,    194 
solipedum,    194 
uniungulati,     195 
Klossiella  equi,   255 
Piroplasmasids 

Babesia  caballi.    298 
e?!<(,    298 
Toxoplasmasids 

Besnoitia  bennetti,    339 
Sarcocvs/;s  bertrami,   323 
Ciliates 

Allantosoma  brevicomiger, 
366 

dicorniger,   366 
intestinalis,  366 


INDEX 


405 


Eqiius  caballus  (Continued) 

Alloiozona  trizona,    362 
Ampidlacula  ampulla,  364 
Blepluiroconus  benbrooki, 
364 

cervicalis,    364 
hemiciliatus,    364 
Bleplmrocorys  aiigusta,367 
cardionucleata,  367 
curvigula.  367 
jubata,  367 
iincinata.  367 
valvata,   367 
Blepliaroprosthium  pireinn , 

364 
Blepluirosphaera  ellipsoi- 
dalis,  364 

intestinalis,  364 
Blepliarozomn  zonatum, 

365 
BiDidleia  postciliata,  365 
Cliaronina  eqiii,    367 
Cochliatoxum  periachtum , 

371 
Cyclopostliinni  affhiae.  370 
bipabuatinn,    368 
corrugatum,    370 
dentiferum,   368 
edentatum,  368 
ishikawai.    368 
piscicauda,  368 
scutigerum,    370 
Didesmis  ovalis,   365 
qiiadrata,   365 
spiralis,   365 
Ditoxum  funinucleum ,   371 
Holophryoides  ovalis,  365 
Ochoterenaia  appendicu- 

lata,    367 
Paraisotriclia  beckeri,  368 
colpoidea.   368 
m inula.   368 
Paraisotrichopsis  compo- 

sita,   365 
Polvmorphella  ampulla, 

365 
Prorodonopsis  coli,   366 
Spirodinimn  equi,    370 
Sulcoarcus  pellucidulus, 

366 
Tetratoxum  excavatum.ZlX 
parvum,    371 
unifasciculatum,  370 
Triadinium  caudatum,  370 
^aZea,    370 
minimum,    370 
Tripalmaria  dogieli,   371 
Eremoplastron,   38,  356 
bovis,    356 
brevispinum,   356 
dilobum ,   3  56 
magnodetilatum ,    356 
monolobum,    356 
neglectum,    356 
rostra  turn,     356 
rugosum,    356 
Erratic  parasite,  definition,   5 
Espundia,  69 
Euchrysomonadorina,  24 


Eucoccidiorida,   30,    158 
Eudiplodinimii ,  38,   356 

maggii,    357 
Euglenorida,   25,    126 
Euglenorina,   25 

Euryxenous  parasite,  definition,   7 
Eutricho)iiastix,  see  Monocerco- 

)>ioiias 
Evolution  of  parasites,    10 
Excretion,   organelles  of,   21 
Exflagellation,   definition,   261 
Experimental  host,  definition,   7 

Facultative  parasite,  definition,   5 
Fanapepea.  see  Chilomasttx 
Fecal  examination,  technics  for 

377,   378,   385,   386,   387 
Fe//s  catus,   parasites  of 
Flagellates 

Giardia  cati,    121 
Leislmiania  donovani,  66 
Peiitatrichomonas  hominis, 

103 
Trichomonas  felisloniae, 

96 
Trypanosoma  cruzi,  43,  58 
rangeli,  43,  62 
Amoebae 

Entamoeba  gingivalis,  148 
histolvtica,    134,    135, 
136 
Telosporasids 

Eimeria  can  is,    195 
ca^(,    195 
/e//;ia,   196 
Hepatozoon  canis,    256 
Isospora  bigemiim,    164, 
237 

/e/is,    238 
riuolta.  239 
Piroplasmasids 

Babesia  felis,  303 
Toxoplasmasids 

Toxoplasma  gondii,  325 
Fibrocystis,  see  Besnoitia 
Filopod,  definition,  20 
FLxation  technics,   380 
Fixative,  HoUande's,   392 
Fixative,  Schaudinn's,  392 
Flagellum,  definition,   20 
Flotation  technics,   385 
Food  vacuole,  definition,   21 
Foraminifera,    129 
Formol  gel  test,   68 
Francaiella,  see  Babesia 

caucasica,   see  Babesia  berbera 
colchica,   see  Babesia  major 
occidentalis,   see  Babesia  bovis 
Funis,  definition,    110 

Gallsickness,  mild,   311 
Callus  gallus,  parasites  of 
Flagellates 

Chilomastix  gallinarum, 

112 
Histomonas  meleagridis, 

74 
Monocercomonas  galli- 
narum,   109 


Pentatrichomo)MS  sp. ,  103 
Pleuronionas  jaculans,  124 
Trichomonas  gallinae,  98 

galli>iarum,  101 
Tritrichomonas  eberthi,  94 
Trypanosoma  calmettei.  64 
gallinarum,    64 
Amoebae 

Endolimax  gregariniform is, 

154 
Entamoeba  gallinarum,  145 
Telosporasids 

Crvptosporidiuni  tvzzeri, 

211,   245 
Eimeria  acervulina,    163, 
207 

brunetti,    205 
luigani,  210 
maxima,    208 
wi//(S,   209 
necatrix,    161,   163, 

204 
praecox,  210 
tenella,    160  et  seq. , 
202 
Isospora  gallinae,  2\\,   242 
Leucocytozoon  caullervi, 
280 

sabrazesi,  281 
Plas»iodiu)n  gallinaceum , 
261,   267 

juxtanucleare,  261, 
267 
Wenxonella  gallinae.   211, 
243 
Piroplasmasids 

Aegyptianella  moshkovskii, 
304 

pullorum,     303 
Toxoplasmasids 

Sarcocystis  rileyi,  324 
Toxoplasma  gondii ,    325 
Ciliates 

Tetrahymena  pyriformis, 
374 
Gambia  fever,   54 
Gametogony,  definition,   22,   162 
Gamont,  definition,  22 
Gastrocystis  besnoiti,   see  Besnoitia 
besnoiti 

gilruthi,  see  Eimeria  gilruthi 
robini,  see  Besnoitia  besnoiti 
Genus,  definition,    14 
Geographic  distribution,   13 
Ghindi,   54 

Giardia,    28,   118,   ii5 
ftoy/s,  ii5,    121 
canis,    120 
caprae,    121 
ca<i,    121 
caviae,    122 
chinchillae,    122 
duodetialis,    122 
duodenalis  race  chinchillae, 

see  G.  chinchillae 
enterica,   see  G.  lamblia 
equi,  121 

/eZ/s,   see  G.  ca// 
intestinalis,  see  G.  lamblia 


406 


INDEX 


Giardia  (Continued) 

lamblia,  119 

muris,  122 

ovis,    see  G.  caprae 

simoni,  122 
jliding,  definition,  20 
Globidium  besnoiti,    see  Besnoitia 
besnoiti 

fusiformis,  see  Eimeria  bovis 

gilruthi,   see  Eimeria  gilruthi 

leuckarti,    see  Eimeria  leuc- 
karti 
joat,  domestic,  see  Capra  hircus 
jobial,   54 
Gonderia,    33,   306,   309 

annulata,  309 

bouis,   see  G.   lawrencei 

hirci,  313 

lawrencei,    312 

mutatis,    311 

oyzs,  314 
Gonderiosis 

In  the  goat,  313,   314 

In  the  ox,   309,   311,   312 

In  the  sheep,  313,  314 

In  the  water  buffalo,  309 

In  the  zebu,  309,  311,   312 
Gonyaulacidae,   25 
Gonyaulax,   25,   107 

catanella,    107 
joose,  domestic,   see  Anser  anser 
Gregarina  Undemanni,  see  Sarco- 

cystis  Undemanni 
Gregarinasina,   30,   158 
Guinea  fowl,   see  Numida  meleagris 
Guinea  pig,  see  Cavia  porcellus 
Gymnodiniidae,   25 
Gymnodiniorina,  25 
Gymnodiniutn.   25,    107 
Gymnostomorida,   34,  348 

Haematococcus  bovis,  see  Babesia 
bovis 

ovis,    see  Babesia  motasi, 
B.  ovis 

Haemobartonella,    24 

Haeniogregarina,    31 

canis,    see  Hepatozoon  canis 
chattoni,    see  Hepatozoon  canis 
rotundata,    see  Hepatozoon 
canis 

Haemogregarinicae,  31 

Haemogregarinidae,  31 

Haemoproteidae,   259 

Haemoproleus,    32,  271,  275 
anatis,  see  H.  netlionis 
columbae,  270,  271 
hermani,  see  H.  nettionis 
maccallumi,    see//,  columbae 
meleagridis,    274 
melopeliae,  see  H.  columbae 
nettionis,    273 
sacltarovi,    273 
lurtur,  see  H.  columbae 
vilhenai,  see  H.  columbae 

Haemospororina,  32,   259 

Halteridium,  see  Haemoproleus 

Hamster,  golden,  see  Mesocrice- 
tus  auratus 


Hartmannella,   29 

hyalina,   see  Acantliamoeba 
hyalina 
Helcosoma  tropicum,   see  Leish- 

mania  tropica 
Helkesimastix  faecicola,  see  Cer- 

comonas  faecicola 
Hematoxylin  solution,  Heidenhain's, 

392 
Hemoflagellates,  40 
Hepatocystis,  32 
Hepatozoidae,   31,   256 
Hepatozoon,   31,  256 
canis,  256 
cuniculi,  257 
felis,  see  H.  canis 
griseisciuri,   258 
muris,   257 
musculi,  257 
Herpetomonas,   26,  41 
Heterogenetic  parasite,  definition, 

6 
Heterotrichorida,   37,   348 
Heteroxenous  parasite,  definition, 

6 
Hexamastix,   28,   109 
caviae,   109 
muris,   109 
robustus,  109 
Hexamita,   28,   115 
columbae,    117 
duodenalis ,   see  Giardia  duo- 

denalis 
meleagridis,    115,  116 
muris,    117 
sp.  of  duck,   117 
sp.  of  rhesus  monkey,    118 
Hexamitidae,  28,   115 
Hexamitus,  see  Hexamita 
Histomonas,  26,  74,    129,   155 

meleagridis,   74,  75 
History,   22 
Holophryoides,    35,  365 

ovalis,  363,  365 
Holophytic  nutrition,  definition,   2, 

21 
Holotrichasina,  34,  347 
Holozoic  nutrition,  definition,  2,  21 
Homo  sapiens,   parasites  of 
Flagellates 

Chilomastix  mesnili.  111 
Enteromonas  hominis,  110 
Giardia  lamblia,    119 
Leishmania  donovani,  66 

tropica,   69 
Pentatrichomonas  hom  inis , 

103 
Retortamonas  intestinalis, 

110 
Selenomonas  sputigena,  113 
Trichomonas  tenax,  95 

vaginalis,   96 
Tritrichomonas  fecalis,  93 
Trypanosoma  cnizi,    58 
gambiense,    50 
ratigeli,  62 
rliodesiense,    50 
Amoebae 

Dientamoeba  fragilis ,  154 


Endolimax  nana,  152 
Entamoeba  chattoni  (7),  147 
co/j,    143 
gingivalis,  148 
liartmanni,  142 
histolytica,  134,   135, 

136 
sz<!S  (?),    146 
lodamoeba  buelschlii,    151 
Telosporasids 

Isospora  belli,  241 

bigemim  (?),  164,  237 
hominis,    241 
natalensis,  242 
Plasmodium  cynomolgi, 
262,   263 

falciparum,  261,   262 
malariae,    261,  262 
offl/e,   261,   262 
wt;ax,  261,   262 
Piroplasmids 

Babesia  divergens,   295 
Toxoplasmasids 

Sarcocvstis  Undemanni, 

324 
Toxoplasma  gondii,  325 
Ciliates 

Balantidium  coli,   372 
Horse,  see  Equus  caballus 
Host,  definition,   1,   5 
Host  range,  definition,   6 
Host  spectrum,  definition,   6 
Host-parasite  relations,   5 
Hymenostomorida,   36,   348 
Hypermastigorida,   28 
Hyperparasite,  definition,   5 

Ichthyophthirius,  36 
Immersion  oil,   removal  of,  384 
Immunity,  definition,    12 
Immunity  against  parasites,   12 
Incidental  host,  definition,   7 
Incidental  parasite,  definition,   5 
Infection,  definition,.  5 
Infestation,  definition,    5 
Infraciliature,  definition,  347 
Infundibidormm ,  35,  350 

cameli,  350 
Injurious  effects  of  parasites,    11 
Intermediate  host,  definition,   5 
Internal  budding,  definition,   22 
lodamoeba,    29,    151 

buelschlii,  150,    151 

suis,  see  /.  buelschlii 

wenyoni,  see  /.   buetschlii 
Iodine  solution,   D'Antoni's,  391 
Iodine  solution,    Lugol's,   391 
Iron  alum  solution,   392 
Isogamy,   definition,   22 
Isospora,    31,   164,   235 

aksaica,  235 

almataensis,  237 

belli,  241 

bigemina,  164,  237,   240 

cati,  see  /.  felis 

felis,  238,   240 

gallime,   211,   242 

heissini,  243 

hominis,  241 


INDEX 


407 


Isospora  (Continued) 

lacazei,   176,   236 

natalensis,    242 

rivolta,   239,  240 

suis,    193,   236 

sp.   of  ox,    176.  235 
Isotriclia,    36,  350 

intestinalis,  349,  350 

prostoma,  349,    350 
Isotrichidae,  36,  350 

Jericho  boil,   69 

Kala-azar,  66,  67 
Karyolysidae,  31 
Karyolysus,   31 
Kinetodesma,  definition,  347 
Kinetoplast,  definition,  40 
Kinetosome,  definition,  347 
Klossia,  30 
Klossiella,  30,   254 

cobayae,  255 

egui,  255 

muris,  255 
Klossiellidae,  30,   254 

Lamblia,  see  Giardia 

cuniculi,  see  Giardia  duoden- 

alis 
intestinalis,  see  Giardia 
lafnblia 
Lankesterella,  32,  247,   259 
adiei,  247 

garnlmmi,    see  L.  adiei 
passeris,   see  L.  arf(e; 
serini,  248 
Lankesterellidae,  32,   159,   247 
Leishmania,  26,  41,  Ji,  42,  62,  65 
brasiliensis,    seeL.  tropica 
canis,  see  L.  donovani 
chagasi,    seeL.  donovani 
cunningliami,  see  L... tropica 
donovani 

infantum,  see  L.  donovani 
nilotica,  see  L.  tropica 
peruviana,    seeL.  tropica 
recidiva,  see  L.  tropica 
tropica,    69 

ivrighti,  see  L.   tropica 
Leishmanial  form,  definition,  41 
Leishmaniosis,  American  forest, 

69 
Leishmaniosis,  cutaneous,   69 
Leishmaniosis,  mucocutaneous,  69 
Leishmaniosis,  viscera^,  66 
Leptomonad  form,  definition,  41 
Leptomonas,    26,  41 
Leucocytogregarirui,  see  Hepato- 

zoon 
Leucocytozoon,    32,   275 
anatis,  see  L.  simondi 
andrewsi,    seeL.  caulleryi 
anseris,   see  L.  simondi 
canis,   see  Hepatozoon  canis 
caulleryi,    280 
marchouxi,    281 
sabrazesi,   281 

schueffneri,   see  L.  caulleryi, 
L.  sabrazesi 


simondi,   275,  276 

smithi,  276,    278 

turtur,  see  L.  marchouxi 

Life  cycle,   definition,   6 

Life  cycles,   21 

Lobopod,  definition,   20 

Locomotion,  20 

Lucetitui  bigemina,   see  Isospora 
bigemina 

cati,   see  Isospora  felis 
felis,   see  Isospora  felis 
hominis,  see  Isospora  honiinis 
rivoltai,  see  Isospora  rivolta 

Luhsia,  see  Babesia 

Macaca   spp. ,  parasites  of 
Flagellates 

Chilomastix  mesnili,    111 
Enteromonas  hominis,  110 
Giardia  lamblia,    119 
Hexamita  sp. ,    118 
Pentatrichomonas  hom inis , 

103 
Retortamonas  intesti>ialis, 

110 
Trichomonas  macacovagi- 
nae,   102 
tenax,  95 
Tritricliomonas  wenyoni, 
94 
Amoebae 

Dientamoeba  fragilis.   154 
Endolimax  nana.    152 
Entamoeba  chattoni.   147 
co/i,   143 
gingivalis,   148 
histolvtica,   134,   135, 
136 
lodamoeba  buetschlii,   151 
Telosporasids 

Plasmodium  cynomolgi, 
262,   263 
Toxoplasmasids 

Toxoplasma  gondii.  325 
Ciliates 

Balantidium  coli,  372 
Macaques,  seeA/acaca  spp. 
Macrostoma,  see  Chilomastix 
Macrogamete,  definition,  22 
Macrogametocyte,   definition,   22 
Macronucleus,  definition,   20 
Mai  de  Caderas,   53 
Malaria,  bird,   266,    270 

human,   262 
Malignant  jaundice,  canine,  300 
Man,   see  Homo  sapiens 
Marico  calf  disease,  311 
Marine  phytoflagellates,   107 
Mastigamoebidae,   26,  74 
Mastigasida,   24,  40 
Maurer's  dots,  definition,   262 
Mbori,    51 

Mechanical  vector,  definition,   5 
Mediterranean  Coast  fever,  bovine, 

309 
Megaloschizont,  definition,   276 
Megastottia  entericum,  see  Giardia 

lamblia 
Meleagris  gallopavo,  parasites  of 


Flagellates 

Chilomastix  gallinarum, 

112 
Cochlosoma    sp. ,    114 
Hexamita  jueleagridis,  115 
Histomonas  meleagridis, 

74 
Pentatricliomonas    sp. ,    103 
Trichomonas  gallinae,   98 
Triclwmonas  gallinarum, 

101 
Tritricliomonas  eberthi,94 
Amoebae 

Acanthamoeba  gallopavonis, 

131 
Endolimax  gregariniform is , 

154 
Entamoeba  gallinarum.  145 
Telosporasids 

Cryptosporidium  melea- 
gridis, 246 
Eimeria  adenoeides,    226 
dispersa,    225 
gallopavonis.  226 
innocua,  228 
meleagridis.  222 
meleagrimitis.  223 
subrotunda,   229 
Haemoproteus  meleagridis, 

Isospora  heissini,2A3 
Leucocytozoon  smithi.  278 
Plasmodium  durae,  261,  268 
Piroplasmasids 

Aegvptianella  moshkovskii 
(?),   304 

pullorum,  303 
Membranelle,  definition,  20 
Merocystis,  32 

sp.  of  pig,  246 
Merozoite,  definition,   21 
Mesocricetus  auratus,  parasites  of 
Flagellates 

Chilomastix  bettencourti, 

112 
Giardia  muris,    122 

simoni,  122 
Hexamastix  muris,  109 
Hexamita  muris,    117 
Monocerconionoides,   sp. , 

114 
Octomitus  pulcher,    118 
Pentatriclwmonas  hominis, 

103 
Trichomonas  microti,   102 
Tritrichomonas  criceti,  95 
minuta,    94 
muris,  94 
wenyoni,  94 
Amoebae 

Entamoeba  muris,  134,  144 
Metacryptozoite,   definition,   260 
Metadinium,    38,   357 
medium,  355.  357 
tauricum,    357 
ypsilon,   357 
Metoral  membranelle  zone,  defini- 
tion, 351 
Microbabesia,  see  Babesia 


-lOS 


INDEX 


Microgamete,  definition,  22 
Microgametocyte,  definition,   22 
Micronucleus,  definition,   20 
Micropyle,  definition,   160 
Microscopic  examination  of  feces, 

377 
Microscopic  examination  of  intes- 
tinal mucosa,   378 
Microspororida,  34 
Miescher's  tubule,  definition,  318 
Miescheria,   see  Sarcocystis 
MIF  stain-preservation  technic,  379 
Monas,    24,  123,    125 

communis ,   see  Spltaeromonas 

communis 
obliqua.  88 
sp.  of  ox  feces,   126 
Monocercomonadidae,  28,   108 
Monocercomonas ,    28,   108,  108 

caprae,  see  Monocercomonoides 

caprae 
cuniculi,   1Q9 
gallinarum,    109 
liominis,   see  Pentatrichomonas 

hominis 
ruminantium,   88,   108 
Monocercomonoides ,   27,   114 
caprae,    114 
caviae,    114 
exilis,    114 
quadrifunilis,     114 
wenrichi,  114 

sp.  of  Norway  rat  and  golden 
hamster,   114 
Monocystis  stiedae,    see  Eitneria 

siiedae 
Monodeme,  definition,  9 
Monogenetic  parasite,  definition,  6 
Monoxenous  parasite,  definition,  6 
Montenegro  test,   71 
Mounting  technic,  381 
Mouse,  domestic,  see  Mus  mus- 

culus 
Multiple  fission,  definition,   21 
Murrina,    51 

Mus  niusculus,   parasites  of  (in- 
complete list) 
Flagellates 

Chilomaslix  bettencourti, 

112 
Giardia  muris,    122 
Hexamita  muris,    117 
Octomitus  pulcher,  118 
Pentatrichomonas  hominis, 

103 
Trichomonas  microti,  102 
Tritrichomonas  minuta,  94 
muris,   94 
wenyoni,   94 
Trypanosoma  duttoni,  43 
Amoebae 

Entamoeba  muris,  134,  144 
Telosporasids 

Cryptosporidium  parvum, 

245,   246 
Hepatuzoon  musculi,  257 
Klossiella  muris,   255 
Toxoplasmasids 


Encephalitozoon  cuniculi, 

341 
Sarcocystis  muris,   324 
Toxoplasma  gondii,  325 

Mussel  poisoning,    107 

Mutualism,  definition,  3 

Mycoplasma  hyorhinis,   91 

Myxopod,  definition,   20 

Myxospororida,  34 

Naegleria,   29,   129,   130 

gruberi,    130 
Naegleriidae,  29,    130 
Nagana,  47,   54 
Nambiuvu,  300 
Napier's  aldehyde  test,  68 
Natural  host  spectrum,  definition, 

8 
Nicollia,  see  Babesia 
Nidality,  definition,  9 
Nidus,  definition,  9 
Nosodeme,  definition,  9 
Nuclei,   19 

Nucleolus,  definition,   19 
Numida  meleagris,  parasites  of 
Flagellates 

Histomonas  meleagridis, 

74 
Pentatrichomonas  sp. ,  103 
Triclwmonas  gallinarum , 

101 
Trypanosoma  numidae ,  46, 
64 
Amoebae 

Endolimax  gregariniformis , 
154 
Nutrition,  organelles  of,   21 
Nutrition,  types,   2 
Nuttallia,    see  Babesia 

minor,  see  Babesia  equi 
shortti,  see  Aegyptianella 
moshkovskii 
Nyctotherus,    37,  375 
faba,    375 
sp.  in  feces,  375 

Obligatory  parasite,  definition,   5 
Ochoterenaia,  35,   367 

appendiculata,  367 
Ochromonadidae,   24,    125 
Ochromonas,     125 
Octomitus,    28,    118 

columbae,   see  Hexamita  co- 
lumbae 

hominis,  see  Enteromonas 
hominis 

intestinalis,   see  O.  pulcher 

muris,   see  Hexamita  muris 

pulcher,   118 
Oikomonas,   24,   125 

communis,    125 

equi,    125 

minima,  125 
Olifantvel,  337 
Ookinete,  definition,   261 
Ophryoglenidae,   36 
Ophyoscolecidae,   38,   348,   351 
Ophryoscolex,    38,  351 


caudatus,  349,    351 
inermis,  351 
purkinjei,    351 
Opisthotrichum,  38 
Organelle,  definition,   19 
Oriental  sore,   69 
Origin  of  parasitism,   13 
Oryctolagus  cuniculus ,  pa.ra.sHes  of 
Flagellates 

Chilomaslix  cuniculi,  112 
Giardia  duodenalis ,  122 
Monocercomonas  cuniculi, 

109 
Retortamonas  cuniculi,  110 
Trypanosoma  nabiasi,   64 
Amoebae 

Entamoeba  cuniculi,  144 
Telosporasids 

Cryptosporidium  sp. ,  246 
Eimeria  coecicola,  162,  199 
elongata,   200 
intestinalis,   200 
irresidua,    198 
magna,    162,   197 
matsubayashii,   200 
media,    162,    198 
neoleporis,    199 
perforans,    197 
piriformis,    199 
stiedae,    196 
Hepatozoon  cuniculi,    257 
Toxoplasmasids 

Encepluilitozoon  cuniculi, 

341 
Sarcocystis  cuniculi,   324 
Toxoplasma  gondii,  325 
Ostracodinium,    38,   358 
clipeolum,   359 
crassum,    358 
dilobum,    359 
dogieli,  359 
gladiator,   358 
gracile,  358 
mammosum,  355,  358 
monolobum,    359 
nanum,    358 
obtusum,  359 
quadrivesiculatum,    358 
rugoloricatum .    359 
tenue,    358 
trivesiculatum,    358 
venustum,    359 
Oyis  aries,    parasites  of 
Flagellates 

Callimastix  frontalis,   113 
Ditrichomonas  ovis,    104 
Giardia  caprae,    121 
Leishmania  donovani,    66 
Protricliomonas  ruminan- 
tium,   88,   109 
Retortamotms  ovis,    110 
Selenonionas  rum  inantium , 

113 
Trypanosoma  brucei,  47 
congolense,    54 
dimorphon,    56 
evansi,  51 
melopliagium ,  63 


INDEX 


409 


Ovis  aries    (Continued) 
uniform e.  58 
vivax,  57 
Amoebae 

Dientamoeba  sp. ,   154 
Entamoeba  ovis,   145 
Telosporasids 

Eimeria  ahsata,   179 
arloi)igi,    180 
crandallis,   181 
faurei,    182 
gilruthi,     182 
granulosa,     183 
intricata,   183 
ninakohlyakimovae ,  184 
pallida.    186 
parva,    186 
punctata.    187 
Piroplasmasids 

Babesia  foUata,    297 
motasi.  296 
ot'/s.    297 
Gonderia  hirci,    313 
ODis,  314 
Toxoplasmasids 

Sarcocystis  tenella.  323 
Toxoplasma  gondii.  325 
Ciliates 

Dasvtriclm  ruminantium, 

350 
Diplodiniuni  quinquecauda- 

tum,  354 
Diplopias  Iron  affiiie.    357 
Entodinium  spp. ,  351 
Eodinium  bilobosum .  354 
Epidinium  ecaudatum,  353 
Eremoplastron  bovis,  356 

dilobum,    356 
Isotricha  intestinalis,  350 

prostoma,  350 
Metadinium  tauricum.  357 
Ophryoscolex  caudatus.  351 
Ostracodinium  gracile.  358 
Polyplastron  multivesicu- 
latum,    357 
Ovoplasma  orientate,  see  Leish- 

niania  tropica 
Ox,   see  Bos  taurus 

Pan  troglodytes,   parasites  of 
Flagellates. 

Chilomastix  mesnili,    111 
Pentatrichomonas  hominis. 

103 
Retortamo)ias  intestinalis, 
110 
Amoebae 

Eiidotimax  naiui,    152 
Entamoeba  coli,    143 
gingivalis.   148 
hisfolvtica.  134,   135, 
136 
lodamoeba  buetschlii,  151 
Telosporasids 

Plasmodium  malariae, 
261,   262 
Toxoplasmasids 

Toxoplasma  gondii,    325 


Ciliates 

Balantidium  coli,  372 
Parabasal  body,  definition,   82 
Parabasal  filament,  definition,  82 
Paraisotriclui,     36,   368 

beckeri.  363,    368 

colpoidea,  363,  368 

tn inula,  363.    368 
Paraisotrichidae,   36,  368 
Paraisotricliopsis.  35,   365 

composita,  363.    365 
Parameciidae,   37 
Paramecium,  37 
Paranagana,   54 
Parasite,  definition,    1 
Parasitiasis,  definition,  4 
Parasitism,  definition,   1,  3 
Parasitism,  economic  importance, 

13 
Parasitism,   injurious  effects,    11 
Parasitism,  origin,    1,   13 
Parasitism,   types,   3 
Paratenic  host,  definition,   5 
Paratrichomonas ,  83 
Paratrichomonas ,    see  also  Tr/- 

trichomonas 
Parasitosis,  definition,  4 
Pattonella,   see  Babesia 

gibsoni.   see  Babesia  gibsoni 
Pavo  cri status,    parasites  of 

Flagellates 

Hexamita  meleagridis,  115 
Histonionas  meleagridis, 
74 
Peafowl,   see  Payo  cristatus 
Pelta,  definition,  82 
Pentatrichomonas,    28,  83,   103 

ardin  delteili,   see  P.  hominis 

canis  auri.   see  P.  hominis 

liominis,  97,    103 

sp.  in  chicken,  turkey,  guinea 
fowl,    103 
Peridiniorina,   25 
Periodic  parasite,  definition,   5 
Peristome,  definition,   21 
Peristyle,  definition,    125 
Physiological  salt  solution,   391 
Phytomastigasina,   24,  40,   107,    124 
Phytomonadorida,   26,   126 
Phytomonas,    26,   42 
Pian  bois,  69 
Pig,   see  Sms  scrofa 
Pigeon,  domestic,  see  Columba 

livia 
Piroplasma.  see  Babesia 

annulatwn ,  see  Gonderia  an- 
nulata 

argentinum.  see  Babesia  ar- 
gentina 

australe,  see  Babesia  bigemina 

bigeminum.  see  Babesia  bigem- 
ina 

bovis.    see  Babesia  bovis 

caballi,  see  Babesia  caballi 

canis,    see  Babesia  canis 

divergens,   see  Babesia  diver- 
gens 

donovani,   see  Leishmania 


donovani 

equi,  see  Babesia  equi 

gibsoni,    see  Babesia  gibsoni 

hirci,  see  Babesia  ovis 

kochi,  see  Theileria  parva 

mutans,    see  Gonderia  niutans 

ovis,  see  Babesia  motasi,   B. 
ovis 

parvum,  see  Theileria  parva 

suis,    see  Babesia  trautmanni 

taylori,    see  Babesia  taylori 

trautmanni,  see  Babesia  traut- 
manni 
Piroplasmasida,  32,   285 
Piroplasmorida,   33,   285 
Piroplasmosis,  avian,   see  Aegyp- 

tianellosis 
Plagiotomidae,   37 
Plasmodiidae,   32,   259,   260 
Plasmodium,  32,   260 

berghei,    261 

cathemerium,    261,   269 

circumflexum,  261,   269 

cvnomolgi,  262,   263 

rfi<rae,    261,   268 

elongatum ,  261 

falciparum,    261,   262 

/a/to.v,    261 

floridense,  261 

gallimceum,  261,   267,   270 

gander i,    261 

hexamerium,  261 

fa<///,    261 

(m<(,  261,   262 

juxtanucleare,   261,   267 

knowlesi,  261 

loplmrae,  261 

malariae,  261,   262 

oya/e,    261,  262 

praecox,   see  P.   relictum 

relictum,  269,   270 

rouxi,    261 

vaugluDii,    261 

I'U'Ox,    261,   262 
Plasmosoma  jericliaense,   see 

Leishmania  tropica 
Pleuromonas,     27,   124 

jaculans,     124 
Pneumocystis,    52 
Polar  ring,  definition,  319 
Polydiniella,  38 
Polymastigidae,  27,    113 
Polymastigorida,   27,    109 
Polvmorplia,   see  Polymorphella 
Poiymorphella,   35,  J65,   365 

ampulla,    366 
Polyplastron,   38,  357 

fenestratum,   357 

moHOSCutum,     357 

multivesiculatum ,  357 
Polvtotna,    26,    126 

id'e/te,    88,    126 
Potential  host  spectrum,  definition, 

8 
Premunition,  definition,   12 
Principal  host,  definition,  7 
Prorodonopsis,    35,  366 

co/z,  56J,   366 


410 


INDEX 


Proteronionas ,   27,    124 

brevifilia,    124 
Protomastigorida,   26,   122 
Prototapirella,  38 
Prolrichomonas ,  28,   109 

anatis,   109 

ruminant ium,    88,   109 
Prowazekella,  see  Proteromonas 
Prymnesiidae,  24 
Prymnesium,    24,    107 

parviim,    107 
Pseudocyst,  definition,  337 
Pseudoparasite,  definition,   5 
Pseudopod,  definition,  20 
Ptyc}iosto77ia,   114 
Pycnotrichidae,  35,  350 
Pygolimax  gregariniformis,  see 

Endolimax  gregariniformis 
Pyrosoma  bigeminum,  see  Babesia 
bigetttina 

bigeminum  var.  canis,    see 
Babesia  canis 

Quantitative  host  range,  definition, 
7 

Quantitative  host  spectrum,  defini- 
tion,  7 

Rabbit,  domestic,  see  Oryctolagus 

cuniculus 
Rabbit,  wild  European,   see  Oryc- 
tolagus cuniculus 
Radiolaria,   129 
Rangelia,  see  Babesia 
Rat,  laboratory,  see  Rattus  nor- 

vegicus 
Rat,  Norway,  see  Rattus  norvegicus 
Rattus  norvegicus,  parasites  of 
(incomplete  list) 
Flagellates 

Chilomastix  bettencourti, 

112 
Ciardia  muris,     122 

simoni,    122 
Hexamastix  muris,    109 
Hexamita  muris,  117 
Monocercomonoides  sp. , 

114 
Octomitus  pulcher,     118 
Pentatrichomonas  hominis, 

103 
Trichomonas  microti,    102 
Tritrichomonas  minuta,  94 
muris,   94 
wenyoni,  94 
Trypanosoma  lewisi,   43 
Amoebae 

Endolimax  ratti,    153 
Entamoebae  muris,  134, 
144 
Telosporasids 

Eimeria  miyairii,  162 
nieschulzi,  160,   162, 

163 
separata,     162 
Uepatozoon  muris,   257 
Toxoplasmasids 

Enceplmlitozoon  cuniculi, 
341 


Sarcocystis  muris,  324 
Toxoplasma  gondii,  325 

Ciliates 

Balantidium  coli,  372 
Red  tide,    107 
Red  water,   107 
Redwater,  292,   293 
Reproduction,   21 
Reservoir  host,  definition,  9 
Resistance  to  parasites,   12 
Reticulopod,  definition,   20 
Retortamonadidae,  27,   111 
Relortamonas ,    27,  iiO,    111 

cuniculi,  110 

intestinalis ,    110 

oyjs,   110 
Rhesus  monkey,  see  Macaca  mulatto 
Rhizomastigorida,   26,  74 
Rhizopod,  definition,   20 
Rhizopodasina,   29 
Rhodesian  tick  fever,   306 
Rossiella,  see  Babesia 

rossi,  see  Babesia  canis 
Rumen  ciliates,  relation  to  host, 
359 

Sappinia,    29,   132 

dip  lo  idea,  132 
Saprophyte,  definition,   2 
Saprophytic  nutrition,  definition,   2 
Saprozoic,  definition,  2 
Saprozoic  nutrition,  definition,   2 
Saprozoite,  definition,  2 
Sarcocystidae,  33,  317 
Sarcocystis,  33,  318 

anatina,  see  S.  rileyi 

bertrami,   323 

besnoiti,   see  Besnoitia  besnoiti 

blanchardi,  see  S.  fusiformis 

cervi,  323 

cuniculi,  324 

fusiformis,    323 

galli>iarum,  see  S.  rileyi 

liominis,    see  i>.  lindemanni 

liorwathi,   see  S.  rileyi 

leporum,  see   S.  cuniculi 

lindemanni,    324 

miescheriana,   322 

muris,  324 

rt7e\7,  324 

tenella.  319,  323 
Sarcodasida,  29,   129 
Sarconeme,  definition,   319 
Sauroplasma  thomasi,  305 
Schellackia,   32,  259 
Schizobodo,  see  Proteromonas 
Schizogony,  definition,   21 
Schizont,  definition,   21 
Scliizotrypanum,    see  Trypanosoma 
Schizozoite,  definition,   21 
Schuffner's  dots,   definition,   262 
Scientific  names,   14 
Scytomonas  pusilla,    126 
Secondary  filament,  definition,  82 
Sedimentation  technics,   386 
Segmenter,  definition,  21 
Selenomastix  rumiiuinlium,  see 

Selenomonas  rum inantium 
Selenomonas,   27,   113 


palpitans,    113 
ruminantium,   113,   iiJ 
sputigena,   113 
Serinus  canarius,    parasites  of 
Telosporasids 

Lankesterella  serini,  248 
Plasmodium  cathemerium, 
261,   269 
Toxoplasmasids 

Toxoplasma  gondii,  325 
Serodeme,  definition,  9 
Sheep,  domestic,   see  Ofjs  aries 
Sleeping  sickness,  African,   50 
Smithia,  see  Babesia 
Sogdianella  moshkovskii,  see  ^e^y- 

tianella  moshkovskii 
Solution,  physiological  salt,  391 
Solution,  Ringer's,  392 
Solution, ,  Sheather's  sugar,   393 
Solution,   zinc  sulfate  flotation,  393 
Souma,   57 

Species,  definition,   16 
Species,  number  of  protozoan,   19 
Sphaeromoiuis,  24,    125 
communis,   125 
liebetanzi,  see  S.  communis 
maxima,  see  S.  communis 
minima,  see  S.  communis 
rossica,  see  S.  communis 
Spirodinium,    38,  370 

equi,  369,  370 
Spiromonas,    27,   124 
angusta,    88,    124 
Spirotrichasina,  37,   348 
Spore,  definition,   22 
Sporogony,   definition,   22 
Sporozoa  funtnculosa,  see  Leish- 

mania  tropica 
Sporozoite,  definition,  22 
Sporulation,  definition,   160 

of  coccidian  oocysts,  378 
Stain,   Bodian  silver  impregnation, 

382 
Stain,   Feulgen,   382,   392 
Stain,  Giemsa,   383 
Stain,   Heidenhain's  hematoxylin, 

380,  391 
Staining,   iodine,   378 
Stain-preservation  technic,  raerthi- 

olate-iodine-formaldehyde,   379 
Stenoxenous  parasite,  definition,   6 
Suctoriorida,   35,   348 
Sulcoarcus,  35,  366 

pellucidulus,    366 
Supplementary  host,  definition,  7 
Surra,   51  . 

Sus  scrofa,   parasites  of 
Flagellates 

Chilomastix  mesnili.    111 
Enteromonas  suis,    110 
Ciardia  lamblia,   119 
Tricliomonas  buttrevi,  83, 
98 
Tritrichomonas  foetus  ( ? ), 
84,  91 

rotunda,   92 
suis,    87,   89 
Trypanosoma  brucei,  47 
coiigolense,    54 


INDEX 


411 


Trypanosoma  brucei  (Continued) 
cnizi.   58 
dimorphuH,   56 
evansi,  51 
simiae,  56 
suis.   54 
Amoebae 

Endolimax  tmna,    152 
Entamoeba  coli,    133,   134, 
143 

histolvtica.    134,    135, 

136 
snigingivalis,   135,    159 
suis,    134,    146 
Ioda»weba  buetschlii,    151 
Telosporasids 

Eimeria  debliecki,    190 
permiimta,   191 
/)o/i7a,   192 
scabra,   192 
scrofae,  192 
spinosa,   193 
Isospora  almataensis,  237 

Si/is,     193,   236 
Merocystis   sp. ,   246 
Piroplasmasids 

Babesia  perroncitoi,  300 
trautmanni,  299 
Toxoplasmasids 

Sarcocystis  miescheriana, 

322 
Toxoplasma  gondii,  325 
Ciliates 

Balantidium  coli,    372 
Symbiosis,  definition,  3 
Synchytrium  miescherianum,  see 

Sarcocystis  miescheriana 
Syndyoniita  muris,   see  Hexamita 

muris 
Syngamy,  definition,   22 
Syzygy,  definition  of,   254 

Taxon,  definition,   15 

Telosporasida,   30,   158 

Testaceorida,   29,   130 

Tetrahymena,    37,   374 

geleii,    see  r.  pyrifortnis 
pyriformis,    374 

Tetrahymenidae,  37,   374 

Tetramitidae,   27,   109 

Tetramitus,  27,   110,   129 
rostratus,  110 

Tetratoxum,    38,  370 
excavatum,  369,  371 
parimm,  369,  371 
unifasciculatum,  369,    370 

Tetratrichomonas ,   see  Trichomonas 
buccalis,    see  Triclwmonas  tenax 

Texas  fever,  292 

Theileria,   33,   305,  306 

annulata,   see  Gonderia  annulata 
buffeli,  see  Gonderia  mutans 
dispar,   see  Gonderia  annulata 
hirci,   see  Gonderia  hirci 
kochi,  see  T.  parva 
lawrencei,   see  Gonderia  lawren- 

cei 
mutans,   see  Gonderia  mutans 
orientalis,    see  Gonderia  mutans 


ovis,    see  Gonderia  hirci,   G. 
avis 

parva,   306,  J06 

recondita,  see  Gonderia  ovis 

sergenti,  see  Gonderia  annulata, 
G.  ovis 

turkestanica,    see  Gonderia  an- 
nulata 
Theileriidae,  33,   305 
Topodeme,  definition,  9 
Toxoneme,   definition,   329 
Toxoplasma,   34,   325 

canis,  see  T.  gondii 

caviae,  see  T.  gondii 

cuniculi,  see  T.  gondii 

gondii,    325,  525 

hominis,  see  T.  gondii 

laidlawi,  see  T.  gondii 

tnusculi,  see  T.  gondii 

pyrogenes,  see  T.  gondii 

ratti,    see  r.  gondii 

sciuri,  see  r.  gondii 
Toxoplasmasida,  33,  317 
Toxoplasmatidae,  34,  325 
Toxoplasmorida,  33,  317 
Toxoplasmosis,  325,  332 
Transport  host,  definition,  5 
Trepomonas.  28,   122 

a^iZfs,   122 
Triadinium,  38,  370 

caudatum,  369,  370 

^a/ea,  565,  370 

minimum,  369,   370 
Triatoma,   59,   60,  62 
Tricaiidalis,  see  Tripalmaria 
Tricercomitus  runiinantium,    see 

Monocercomonas  rum inantium 
Tricercomonas,  see  Enteromonas 
Trichomastix,  see  Monocercomonas 

ruminantium,  see  Protricho- 
monas  ruminantium 
Trichomonadidae,   28,  82 
Trichomonadorida,   28,   82 
Trichomonas,    28,   83,  S5,    95 

anatis,    102 

anseri,    102 

bovinus,  see  Tritrichomonas 
foetus 

bovis,  see  T.  pavlovi,    Tri- 
trichomonas foetus 

buccalis,  see  T.  tenax 

buttreyi,  83,  50,  98 

canistomae,    96 

columbae,  see  T.  gallinae 

confusa,    see  Pentatrichomonas 
hominis 

cricetus,  see  Tritricliomonas 
criceti 

diversa,  see  T.  gallinae 

eberthi,    see  Tritrichomonas 
eberthi 

elongata,  see  r.  /eiiojc 

enter  is,  see  Tritrichomonas 
enteris 

equi,    see  Tritrichomonas  equi 

equibuccalis ,  95 

/ehs,  see  Pentatrichomonas 
hominis 

felistomae,   96 


foetus,    see  Tritrichomonas 
foetus 

gallinae,  98,   55 

gallinarum,  101 

genitalis,    see  Tritrichomonas 
foetus 

lialli,   see  T.  gallinae 

intestinalis,    see  Pentatricho- 
monas hominis 

macacovaginae,  102 

mazzanti,    see  Tritrichomonas 
foetus 

microti,   102 

parva,    see  Pentatricltomo)ias 
hominis 

pavlovi,   97 

pullorum,  see  7.  gallinarum 

ruminantium,    see  Monocerco- 
monas ruminantium 

suis,  see  TritrichomorMS  suis 

tenax,   95,  57 

utero-vagiimiis  vitulae,   see 
Tritrichomonas  foetus 

vaginalis,  96,   57 
Trichomonosis,  avian,  99 
Trichomonosis,  bovine  genital,   84 
Trichomonosis,  human  vaginal,  96 
Trichomonosis,  upper  digestive 
tract,  99 
Trichonympha,   28 
Trichostomorida,   35,   348 
Trifascicidaria,   38 
Trimastigamoeba,  29,    130 

philippinensis,     131 
Tripalmaria,   38,  371 

dogieli,  369,    371 
Triplumaria,   38 
Tritrichomonas,   28,  83,  84 

caviae,   94 

criceti,   95 

eberthi,  94,   54 

enteris,  88,  93,   55 

eg2<!,   93 

fecalis,  93 

foetus,  84,  §■;/,   91 

foetus  infection,  diagnosis  of, 
88,   378 

tninuta,   94 

muris,   82,  94 

rotunda,  90,  92 

ruminantium ,   see  Monocerco- 
monas ruminantium 

suis,    87,  89,  50 

wenyoni,  94 

sp.  of  the  guinea  pig,  94 

sp.  of  ox,  93 
Troglodytella,    38 
Trophozoite;  definition,  22 
Trypanosoma,   26,   41,  4i,   42 

aegyptum,  see  T.  evansi 

americanum ,  see   T.  theileri 

angolense,  see  T.  vivax 

annamense,  see  r.  evansi 

ariarii,   see  T.  rangeli 

avium,    46,  64 

bovis,  see  T.   vivax 

brucei,  46,    -^6,  47,  4« 

calmettei,    46,  64 

cameli,  see  r.  evansi 


412 


INDEX 


Trypanosoma  (Continued ) 
caprae,  see   T.   vivax 
cazalboui,   see  T.   vivax 
cellii,   see  T.  congolense 
classification,  43 
confusum,   see  T.  congolense 
congolense,    45,  46,   54 
cruzi,    43,  46.    58,  59 
dimorphon,  45,   56 
dultoni,    43 

elepliantis,   see  r.  evansi 
equinuyn,   46,   53 
equiperdum,   46,   -/6,   53 
evansi,    46,   51 
falshawi,   see  T.  theileri 
franki,   see  T.  theileri 
frobeniusi,  see  T.  congolense 
gallinarum,  46,  64 
gambiense,   46,   50 
giiatenialense,  see  T.  rangeli 
liannai,    46,  64 
himalayanum ,  see  T.  theileri 
hippicum,  see  r.  evansi 
ignotum,    see  T.  simiae 
indicurn,    see  T.  theileri 
lewisi,  43 

marocanum,  see  T.   evansi 
melopliagiutn ,    43,  63 
niontgotneryi,  see  T.  co)igo- 


lense 

niuktesari,   see  T.  theileri 

nabiasi,   43,   64 

nanum,  see   '/'.  congolense 

niiiae  kohl-yakimov ,  see  r. 

numidae,    46,  64 
pecaudi,  see  r.  brucei 
pecorum,    see  r.  congolense 
porci,   see  T.  simiae 
rangeli,  43,  62 
rfiodesiense,  46,   50 
rodhaini,  see  r.  simiae 
ruandae,  see  r.  congolense 
ruther/ordi,  see  r.  theileri 
scheini,   see  T.   theileri 
simiae,    45,    56 

somaliense,  see  T.  congolense 
soudanense,  see  T.  evansi 
suis,    45,   54 
theileri,    43,  J6,    62 
theodori,  63 
uniforme,    44,   58 
venezuelense,   see  T.  evansi 
viennei,   see  T.  vivax 
vivax,   44,  46,    57 
wrubleivskii,   see  T.   theileri 
Trypanosomatidae,  26,  40 
Trypanosome  form,  definition,  41 


Turkey,  see  Meleagris  gallopavo 
Type  genus,  definition,   15 
Tyzzeria,   31,    164,   243 

anseris,  164,   244 

perniciosa,    243 
Tzaneen  disease,   311 

Undulating  membrane,  definition, 

20 
Uta,   69 

Vahlkampfia,     29,    129,    132 
lobospinosa,    133,  ioO 
punctata,  132 
sp.  in  feces,    133 

Vector,  definition,    5 

Vesicular  nucleus,  definition,    19 

Wasfeia  intestinalis ,  see  Retorta- 

monas  intestinalis 
Wenyonella,  31,  243 
gallinae,    211,   243 

Xenodeme,  definition,  9 
Xenodiagnosis,   definition,   61 

Zebu,   see  Bos  indicus 
Zoomastigasina,   26,  40 
Zoonosis,  definition,   8 


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