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Full text of "Parasites and parasitosis of the domestic animals, the zoölogy and control of the animal parasites and the pathogenesis and treatment of parasitic disease"

all|p ©• B. Bill Siihraru 

Nartli (Earoltna ^talr 



OH 



I 





This book was presented by 

MILTON M. LEONARD, D.V.M. 

TO THE 

VETERINARY MEDICAL LIBRARY 



This book is due on the date indicated 
below and is subject to an overdue 
fine as posted at the circulation desk. 



EXCEPTION: Date due will be 
earlier if this item is RECALLED. 




200M/06-99-991212 



PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 



THE MACMILLAN COMPANY 



MACMILLAN & CO., Limited 



THE MACMILLAN CO. OF CANADA. Ltd. 

TORONTO 



PARASITES AND PARASITOSIS 

OF THE 

DOMESTIC ANIMALS 



THE ZOOLOGY AND CONTROL OF THE ANIMAL 

PARASITES AND THE PATHOGENESIS AND 

TREATMENT OF PARASITIC DISEASES 



BY 

B. M. UNDERHILL, V.M.D. 

PROFESSOR OF PARASITOLOGY AND INSTRUCTOR IN ZOOLOGY AND 
HISTOLOGY, SCHOOL OF VETERINARY MEDICINE, UNIVER- 
SITY OF PENNSYLVANIA, ZOOLOGIST, DIVISION OF 
LABORATORIES, PENNSYLVANIA STATE 
BUREAU OF ANIMAL INDUSTRY 



WITH 180 ILLUSTRATIONS 



THE MACMILLAN COMPANY 

1920 

All rights reserved 



COPYKIGHT, 1920 

By the MACMILLAN COMPANY 



Set up and printed. Published April. 1920 



PREFACE 

In the preparation of this work the author has aimed to present 
clearh', concisely, and in orderly manner such matter pertaining to the 
subject at hand as seems most essential to the needs of the student and 
the practitioner. Notwithstanding its elementary character, the present 
rapid advances in parasitology have necessitated numerous changes and 
additions to the manuscript during its preparation. New species and 
unsettling facts and theories as to some which are not new are, in these 
days of intensive research, frequently l^eing brought to light and re- 
ported upon. Some of these findings represent or lead to a distinct 
advance and, though the observations be in certain cases upon obscure 
and in themselves unimportant species, they may, by analogy, shed 
valuable light upon life histories and modes of infection of related forms 
known to be injurious to domestic animals and man. So frequent are 
these steps forward that it might almost seem better to leave compara- 
tive parasitology at the present time to the fragmental attention it has 
mainly received, and possibly it is to this view that the lack of a recent 
American volume upon the subject may be attributed. Be that as it 
may, this book is not intended to be comprehensive, and it contains but 
little discussion, historical or otherwise, of investigations in the field of 
medical zoology, — limitations which ma.y, in measure, contribute to it a 
longer period of usefulness in its present form than could be hoped for 
in an exhaustive treatise. With but few exceptions, the parasites con- 
sidered are those most likely to be met with and as to which most of the 
facts pertaining to their biologv and pathogenicity have lieen well 
established. 

The treatment of the subject is based upon the advantages of pre- 
senting it with at least a rudimental attention to the biologic principles 
involved in parasitism, a knowledge of which is requisite to the proper 
conception of parasitology and certainly essential to intelligently 
applied measures of control. The direct and lucid style of the text 
throughout will, it is hoped, bring these briefly considered fundamentals 
before the reader in their true bearing upon the whole subject and render 
the book particularly acceptalile to the general practitioner as well as to 
the student. 

Teachers will appreciate that laboratory work should supplement the 
class-room method of study. Of course the student should in every 
case see the parasite under consideration in so far as this is possible. 
Methods of labomtor}" technique and the selection of type specimens for 



vi PREFACE 

dissection should, in the author's opinion, be left to the teacher, who 
should certainly be the one best qualified to fornnilatc the course adapted 
to his needs. No general outline, therefore, as to laljoratory methods 
has been attempted. 

If, as has been said, orighiality is not the best reconnnendation for a 
work of this kind, the author feels quite sure that its defects cannot to 
any great extent be attributed to that source. His observations in the 
field and laboratory have been utilized in the preparation of the book, 
but contribute nothing to its pages that is advanced or aggressively 
critical. Excluding the first three chapters, so much of the sul)ject- 
matter has been drawn from the published results of the labors of others 
that the numerous sources cannot well be enumerated here. Acknowl- 
edgments are especially due to bulletins and articles upon various topics 
of parasitolog}' written by workers in federal and state bureaus of ex- 
perimental research. Other sources which have been relied upon and 
freely used are: 'M. Neveu-Lemaire's Parasitologic des Animaux Domes- 
iiques; Herms' Medical and Veterinary Entomology; Riley and Johann- 
sen's Handbook of Medical Entomology; Calkins' Protozoology; Neumann's 
Parasites and Parasitic Diseases of the Domesticated Animals; Bi-aun's 
Animal Parasites of Man; The Journal of Parasitology; The American 
Edition of Hutyra and Marek, and Osborn's Economic Zoology. 

The author wishes to express his sincere appreciation and thanks to 
his laboratory coworker. Dr. Fred Boerner, Jr., for his assistance in the 
collection of specimens and in the examination of pathologic material; 
also to Dr. William J. Lentz for his reading and valuable criticism of 
parts of the manuscript, and to Dr. C. P. Fitch for his helpful suggestions 
as to sources of reference. 

Illustrations for a work of this character will ])e an aid to the text in 
proportion as they are exact and well chosen. For the study of mor- 
phologic characteristics photographs of actual specimens are often too 
obscure in detail, and accurate drawings or line sketches are, as a rule, of 
greater service. It will be observed that man}' of the figures in this 
book are taken from publications issued by the United States Depart- 
ment of Agriculture. Probably no better drawings of these subjects have 
been produced, and the privilege granted to use them is esteemed as a 
helpful favor of much value to the work. In this connection the author 
would especially express his gratitude to Dr. L. 0. Howard. Chief of the 
Bureau of Entomology, to Dr. John R. ]\Iohler, Chief of the Bureau of 
Animal Industry, to Dr. Herbert Osborn, to Dr. Howard Crawley, and 
to Dr. B. H. Ransom. Finally, thanks are due to Dr. W. H. Hoedt of 
Philadelphia, for his skill and interest in preparing the photomicro- 
graphs and many of the drawings. 

B. ]\I. U. 

Philadelphia, Pa. 



CONTENTS 

PART I 

PRELIMINARY CHAPTERS 
THE EXTERNAL PARASITES 

CHAPTER I 

PAPE 

Introduction 1 

Origin of parasitism; Influences inhibiting organic multiplication; The 
struggle for existence; The sheltered mode of life; Its effect; Phases of the 
symbiotic relationship; Example of mutualism; Examples of commensalism ; 
True parasitism; Adaptive and degenerative modifications of the parasite; 
Faculties of parasitic and predatory animals compared; Simplicity, primitive 
and degnerative; The Tunicata; Functions involved in adaptation to para- 
sitism; The reproductive process in MeJophagus ovinus; Development oi the 
reproductive function in parasites; Parasitism of Gaslrophilus inteslinalis; 
Alternation of hosts in life cycle of parasites; The complicated cycle of the 
liver fluke; The tapeworm as an example of extreme parasitism; Deductions 
as to the systematic position of parasites through comparison with free-living 
forms. 

CHAPTER II 

Forms of Parasitism and Influence upon the Host 7 

Terms used in parasitology; Symbiosis; Mutualism; Commensalism; 
Helotism; Parasitism; Phytoparasites; Zooparasites; Optional occasional 
parasites; Obligate occasional parasites; Determinate transitory parasites; 
Permanent parasites; Fixed parasites; Erratic parasites; Determinate 
erratic parasites; Monoxenous parasites; Heteroxenous parasites; Trans- 
migration; Incidental or stray parasites; Ectoparasites; Entoparasites; 
Helminthes; Terms used in the designation of parasitic diseases; Preda- 
cious and parasitic animals; Factors governing injuiy to the host by para- 
sites; General etiologic factors. 

CILIPTER III 

Phulum I. Arthropoda 13 

Characteristics of the Arthi'opoda; Characteristics of the class Insecta; 
Insect methods of reproduction; Duration of life of insects. 



viii CONTEXTS 

CHAPTER I\- 

PAGE 

Mosquitoes and Gnats ... 23 

Characteristics of tlic order Diptera; Dipterous iiarasitisni; Charactis- 
tics of the family Culicida^; Range and prevalence of mosquitoes; Their 
breeding habits; Their pathologic importance; Tlie transmitter of malaria; 
Methods of distinguisliiug between Anopheles and Culex; The transmitter of 
yellow fever; Characteristics and habits of the species Atles caloirus; Effect 
of mosquitoes upon live stock; Mosquito control; Characteristics of the 
family Simuliida;; The Southern bufTalo gnat; Effect of its attack upon live 
stock; Control: Protection and treatment. 

CHAl'TER y 

The Flies 35 

Characteristics of the family Tabanidse; Horse-flies; Gad-flies; Effect of 
their attack; Protection; Characteristics of the family Muscida; The 
house-fly; Habits of the house-fly and its relation to the transmission of 
disease; Its control; Protective measures; The horn fly; Its habits; Effect of 
its attack; Its control; The tsetse flies; Characteristics of th£ genus Glossina; 
Distribution and habits of tsetse flies; Their relationship to trypanosomiasis; 
Investigations by Bruce and others; Tsetse fly control; Characteristics of 
the family Hippoboscidaj; The "sheep tick" or "louse fly;" Its effect; 
Treatment. 

chapti:r \T 

The Dipterous Larv.f, 50 

Myasis; The "screw worm fly;" Its habits; Effect of its attack; Pro- 
tective measures; Treatment; The flesh flies; The blowfly; Its habits; 
Protective measures; Characteristics of the family CEstridae; The horse 
bot flies; Gastrophilus inteslinnlls; Its habits and life history; Effect of the 
fly and larva) upon horses; The red-tailed bot-fly; Its habits and effect; The 
chin fly; The ox bot or warble flies; Tlunr life history; Their economic im- 
portance; The sheep bot fly; Its habits and life history; Effect of the at- 
tack of the fly and its larva>; Protection and treatment. 

CHAPTER VII 

The Fleas 65 

Characteristics of the order Siphonaptera; The dog, cat, and human fleas; 
Differentiation of species; Life history; Relation of fleas to the transmis- 
sion of infectious diseases; Treatment and control, 

CHAPTER VIII 

The Lice 70 

The sucking lice; Characteristics of the order Siphunculata; The biting 
lice; Characteristics of the order Mallophaga; Pediculosis of domestic ani- 



CONTENTS ix 

PAGE 

mals in general; Pediculosis of the horse; Pediculosis of cattle; Pediculosis 
of the sheep and goat; Pediculosis of the hog; Pediculosis of the dog and 
cat; Pediculosis of man; Control and treatment of pediculosis. 

CHAPTER IX 

Lice of Poultry; The Bedbug 82 

Prevalence and effect of poultry lice; Species infesting chickens; Species 
infesting turkej-s; Species infesting ducks and geese; Species infesting 
swan; Species infesting pigeons; Control and treatment of poultry lice; 
Characteristics of the order Hemiptera; Characteristics of the family Cimi- 
cida); The common bedbug; Its habits and effect of its bite; The bedbug as 
a pest of poultry; Control. 

CHAPTER X 

The Mites 94 

Characteristics of the class Arachnida; Characteristics of the order Acar- 
ina; Parasitism oi the Acarina; Acariasis; Characteristics of the family Ga- 
masidse; The gamasid mites of poultry; Habits and effect of their attack; 
Control; Characteristics of the family Trombidiidse ; The harvest mites, 
chiggers, or red bugs; Habits and effect of their attack; Treatment; The 
mange, scab, or itch mites; Characteristics of the family Sarcoptidaj; The 
genera Sarcoptes; Notoedrcs, Otodectes, Cnemidocoptes, Laminosioptes, 
Cj'toleichus, Psoroptes, and Chorioptes; Their respective characteristics, 
hosts, and modes of attack; Characteristics of the family Demodecidse; 
Mange and scabies of the various domestic animals; Sarcoptic mange; De- 
modectic or foUicular mange; Notoedric or head mange of the cat and rab- 
bit; Otodectic or auricular mange; Psoroptic scabies; Auricular scabies oi 
the rabbit; Chorioptic or leg scabies; Symptoms, development, lesions, diag- 
nosis, and transmission of mange and scabies. 

CHAPTER XI 

Treatment of Mange and Scabies 120 

General considerations; Treatment of sarcoptic mange ot the horse; Of 
the dog; Of the goat; Of the sheep; Of cattle; Treatment of notoedric mange 
of the cat and rabbit; Treatment of demodectic mange; Treatment of oto- 
dectic mange; Treatment of psoroptic scabies of the sheep; of cattle; Of 
the horse; Of the rabbit, Treatment of chorioptic scabies of the horse; Of 
cattle. 

CHAPTER XII 

Mange of Poultry 132 

The burrowing mite of poultry-; Leg mange or "scaly leg"; Its course 
and treatment; The depluming mite; The deep-seated acariases of birds; The 
family Cytoleichidse ; The connective tissue mite; The air passage mite. 



X CONTENTS 

CHAPTER XIII 

PAGE 

The Ticks 136 

Structure of ticks in general; Characteristics of the superfamily Ixo- 
doidea; Characteristics of the family Argasidte; The fowl tick; Its habits and 
effect upon the host; Control; The spinose ear tick; Its habits and effect upon 
the host; Treatment; Characteristics of the family Ixodidse; Description of 
genera; Species found upon domestic animals in the United States; The 
Texas-fever or Southern cattle tick; Biological data established by the Zool- 
ogical Division of the United States Bureau of Animal Industry; Life his- 
tory of the Texas-fever tick; Its nonparasitic development; Its parasitic 
development; Loss occasioned by the Texas-fever tick; Progress made in its 
eradication; The order Linguatulida; Lingualula rhinarin of the nasal cavi- 
ties of mammals. 



PART II 

THE INTERNAL PARASITES 
CHAPTER XIV 

Phylum II. Platyhklminthes; The Flukes and Tapeworms 155 

Classification of the parasitic worms; Characteristics of the Platyhelm- 
inthes; Characteristics of the class Trematoda; The liver flukes; Their life 
history; Prevalence of fascioliasis; Infection; Migration of flukes within the 
definitive host and pathogenesis; Fascioliasis of the sheep; Fascioliasis of 
cattle; Control and treatment; The blood fluke; Bilharziosis; Characteristics 
of the class Cestoda; Characteristics of the family Tseniidfp; Life history of 
tapeworms; Their parasitism. 

CHAPTER XV 

T^niasls 174 

General consideration of the effect of tapeworms upon their hosts; Tape- 
worms of the horse; Tapeworms of cattle, sheep, and goats; Tapeworms of 
the dog; Dog tapewomis in relation to human infection; Tapewonns of 
the cat; Tapeworms of the rabbit; Characteristics of the family DiphyUo- 
bothriidae; Occurrence of species; Treatment of tseniasis of the dog; Pre- 
vention; Treatment of tseniasis of the cat; Treatment of tseniasis of sheep, 
goats, and cattle; Treatment of ta?niasis of the horse. 



CHAPTER XVI 

Tapeworms of Chickens 189 

Characteristics of species; Investigations as to their relative occurrence; 
Symptoms; Control; Treatment. 



CONTENTS xi 

CHAPTER XVII 

PAGE 

The Tapeworm Larv^ 194 

Pathologic importance; Forms and their characteristics, Cysticercosis 
or measles; Beef measles; Its occurrence; Degeneration and vitality of the 
cysts; Pork measles, Its occuri'ence; Degeneration and vitality of the cysts; 
Measles of the sheep; Ccenurosis or gid; Its occurrence; Its development; 
Its post-mortem appearance; Its sj-mptoms; Control and treatment; Echin- 
ococcosis or hj'datid disease; Structure of the echinococcus cyst; Its de- 
velopment; Post-mortem appearance in echinococcosis; Sj-mptoms; Con- 
trol. 

CHAPTER XVIII 

Phylum III. Ccelhelminthes; The Smooth and Segmented Roundworms . . . 216 
Characteristics of the Ccelhelminthes; Characteristics of the class Xe- 
mathelminthes; Characteristics of the order Xematoda: Parasitism of the 
nematode worms in general; General considerations as to treatment. 

CHAPTER XIX 

Nematoda; Family I. AscARro^E; The Large Roundworms of the Intestine 229 
Characteristics of the Ascaridse; Investigations as to life history; Ascar- 
iasis; Ascarids of the horse; Occurrence of equine ascariasis; Its etiology, 
control, and treatment; Characteristics of the famih- Oxjairidse; Oxyuriasis 
of equines; Ascarids of the dog and cat; Ascarids of the hog and -sheep; As- 
carids of the ox; The family Heterakida) and heterakiasis of poultry. 

CHAPTER XX 

Nematoda; Family IV. Filariid^e; The Thread-like Worms 244 

Characteristics of the Filariida?; Parasitism; Filaria of the horse; Their oc- 
currence; Effect of filariasis upon equines; Filaria of sheep and cattle; Filaria 
of the dog; Hematic filariasis; Filaria of the hog; Filaria of poultry. 

CHAPTER XXI 

Nematoda; Family V. Strongylid^e; Subfamily I. Metastrongylin^ 

Worms of the Respiratory Tract 255 

Characteristics of the Strongylidse ; Parasitism; Strongylosis; Characteris- 
tics of the JNIetastrongj-linse; Parasitism; Bronchial and pulmonary strongy- 
losis of the sheep and goat; Its symptoms, course, and prognosis; Bronchial 
and pulmonary strongylosis of cattle; Its symptoms, course, and prog- 
nosis; Bronchial and pulmonary strongylosis of the pig; Its occurence and 
sj-mptoms; Bronchial and pulmonary strongjdosis of the horse; Cardio- 
pulmonary strongj'losis of the dog; Pulmonary strongylosis of the cat; Post- 
mortem appearance in bronchial and pulmonary strongj'losis; Develop- 
ment, etiology, control, and treatment of bronchial and pulmonary strongj'- 
losis. 



xii CONTENTS 

CHAPTER XXII 

PAGE 

Nematoda; Subfamily IT. Trichostroxgylin.e; Worms of the STOiiACH 

AND Intestine 268 

Characteristics of the Trichostrongylinse ; Parasitism; Gastro-intestinal 
strongylosis of the sheep and goat; Its occurrence; Its symptoms; Gastro- 
intestinal strongylosis of cattle; Its occurrence; Its symptoms; Post-mortem 
appearance in gaslro-intestinal strongylosis, Development, etiology, con- 
trol, and treatment of gastro-intestinal strongj'losis. 



CHAPTER XXIII 

Nematoda; Subfamily III. Stroxgylin.e; Worms of the Large and Small 

Intestines; Other Strongyles 280 

Characteristics of the Strongylinae; Parasitism; Nodular strongylosis of 
the sheep and goat; Its occurrence; Its development; Its post-mortem ap- 
pearance; Its symptoms; Treatment; Nodular strongylosis of cattle; Nodu- 
lar strongylosis of the hog; Strongylosis of the large intestine of the sheep and 
goat; Strongylosis of the intestines of the horse; Its development; Its symp- 
toms; Its post-mortem appearance; Intestinal strongylosis of the dog and 
cat; Other Strongyhnse; Tracheal strongylo.sis of chickens; The kidney 
worm of the hog; Family Eustrongylidse and eustrongylosis. 



CHAPTER XXIV 

Nematoda; Family VII. Trichinellid.e 299 

Characteristics of the Trichinellidae ; The "whip-worms" of the large 
intestine; Tnchinclla spiralis and trichinosis; Life history of Trichinella 
spiralis; Intestinal trichinosis; Muscular trichinosis; Degeneration of the 
trichina cyst; Infection; Symptoms of intestinal and muscular trichinosis in 
hogs; Trichinosis in rats and mice; Prophylaxis. 

CHAPTER XXV 

The Thorn-headed Worm; The Leeches 306 

Characteristics of the order A(;anthocephala; The thorn-headed worm of 
the intestines of the hog; Its life history; Its occurrence; Its pathogenicity; 
Symptoms produced; Treatment; Characteristics of the class Annelida; 
Characteristics of the order Hirudinea; The horse leech; The medicinal 
leech; Sources of infestation by leeches; Their effect upon the animal at- 
tacked; Treatment. 



CONTENTS xiii 

PART III 

■THE PATHOGENIC PROTOZOA 

CHAPTER XXVI 

PAGE 

PHYLrji IV. Protozoa 311 

General consideration of the Protozoa; Characters differentiating Pro- 
tozoa from Metazoa; Ameba, its main features for study; Parasitism of 
the Protozoa; Progress of research; Relationship of arthropods to infection 
with protozoal diseases; Evolution of pathogenicity in Protozoa; Methods 
of reproduction in free and parasitic forms; Life history of the malaria or- 
ganisms; The schizogonic or asexual cycle; The sporogonic or sexual cycle; 
Classification of pathogenic species. 

CHAPTER XXVII 

The Protozoan Subgroups; Diseases Due to Protozoa 324 

Characteristics of the class Rhizopoda; Infectious entero-hepatitis of tur- 
keys; Amebic dysentery of man; Characteristics of the class Flagellata; 
Characteristics of the order Spirochetida; Spirochetosis of poultry; Char- 
acteristics of the order Trypanosomatida; Parasitism; Transmission of 
the infecting organisms; Nagana or "fly disease;" Surra, Mai de Caderas; 
Dourine; Trypanosoma aviericanurn; Characteristics of the class Sporozoa; 
Characteristics of the order Coccidia; Coccidiosis; Eimeria stiedce; Cocci- 
diosisof rabbits; Diplospora bigemina; Coccidiosis ot dogs; Coccidium zurni; 
Red dysentery of cattle; Eimeria avium; Coccidial enteritis of chicks; Char- 
acteristics of the order Hemosporidia; Piroplasma higeminum; Texas-fever 
of cattle; Its occurrence; Exposure and development; Its symptoms; The 
acute type; The chronic type; Prevention and treatment; Characteristics of 
the order Sarccsporidia; Sarcosporidiosis; Mode of infection. 

Glossary 353 

Index 359 



LIST OF ILLUSTRATIONS 

FIG. PAGE 

1. Diagram of an insect 16 

2. Diagram of internal parts of an insect 16 

3. Diagram of insect's heart 17 

4. Mouth parts of a biting insect 17 

5. Diagram showing tracheal system of an insect 18 

6. Abdomen of locust, showing spiracles IS 

7. Head of bee, showing compound eyes, ocelli, and antennse 19 

8. Metamorphosis of the house fly 19 

9. Diagram of segments of arthropod, showing leg muscles, etc 19 

10. Eggs and larvse, of Culex mosquito 2-4 

11. Pupa, of Culex and Anopheles mosquitoes 26 

12. Culex pungens, male and female 27 

13. Anopheles quadrimaculatus, male and female 28 

14. Position of Anopheles and Culex at rest 28 

15. Breathing position of larva, of Anopheles and Culex 29 

16. Eggs of Anopheles 30 

17. The Southern buffalo gnat 32 

18. Larva of Southern buffalo gnat 33 

19. Pupa of Southern buffalo gnat 33 

20. The black horsefly 36 

21. The green-head fly 36 

22. The stable or stinging fly 39 

23. The horn fly 42 

24. Tsetse fly 44 

25. The "sheep tick." 47 

26. The screw worm fly 51 

27. Metamorphosis of the flesh fly 52 

28. Horse botfly, showing eggs, larva, and adult 54 

29. Ox botfly, Hypoderma Uneata 58 

30. Ox botfly, Hypoderma bovis 59 

31. Eggs of Hypodemia lineata 59 

32. Larval stages of Hj^poderma lineata _,. 61 

33. The sheep botfly, showing larva, pupa, and adult 63 

34. The dog flea, anterior portion of body 66 

35. The human flea, anterior portion of Ijodj- 66 

36. The dog flea, showing development and mouth-parts 67 

37. Larva of flea 68 

38. Sucking louse of horse, Hsematopinus asini 73 



<vi LIST OF ILLUSTRATIONS 

IG. PAGE 

39. Biting louse of horse, Trichodectes parumpilosus 73 

40. Sucking louse of cattle, Ha?matopiuus eurysternus 74 

41. Sucking louse of calves, Linognathus (Haematopinus) vituli 75 

42. Biting louse of cattle, Trichodectes scalaris 75 

43. Sucking louse of sheep, Linognathus (Hsematopinus) pedalis 76 

44. Biting louse of sheep, Trichodectes sphiprocephalus 77 

45. Sucking louse of hog, Hsematopinus suis 78 

46. Sucking louse of dog, Linognathus (Hsematopinus) piliferus 78 

47. Biting louse of dog, Trichodectes latus 79 

48. Louse of the cat, Trichodectes subrostratus 79 

49. Louse of chicken, Goniocotes gigas (G. abdominalis) 83 

50. Louse of chicken, Lipeurus caponis (L. variabihs) '. . 83 

5L Louse of chicken, Menopum trigonocephalum (Menopon pallidum) . 83 

52. Louse of turkey, Goniodes stylifer 85 

53. Louse of turkey, Lipeurus meleagridis (L. poly trapezius) 85 

54. Louse of turkey, Menopum (Menopon) biseriatum 85 

55. Louse of duck, Lipeuris anatis (L. squalidus) 85 

56. Louse of ducks and geese, Trinotum (Trinoton) luridum 87 

57. Louse of swan, Philopterus (Docophorus) cygni 87 

58. Louse of swan, Ornithonomus (Ornithobius) cygni 87 

59. Louse of pigeon, Goniocotes conipar 87 

60. Louse of pigeon, Goniodes damicornis 87 

6L Bedbug, adult female, mouth-parts etc 91 

62. Diagram of the anatomy of a spider 95 

63. Gamasid poultry mite, young and adult 98 

64. Mange mite of horse 104 

65. Mange mite burrow in human skin 105 

66. Colts affected with sarcoptic mange 106 

67. Leg scab mite of horse 109 

68. Scab mite of sheep, female Ill 

69. Scab mite of sheep, male HI 

70. Follicular mange mite 116 

71. Mange mite of cat and rabbit 118 

72. Auricular scab mite of rabbit 118 

73. Portable dipping vat for sheep 127 

74. Mite of scaly leg of poultry, male and female 133 

75. Foot of fowl affected with scaly leg 134 

76. Capitulum of tick 137 

77. Capitulum, scutum, and fore leg of Texas fever tick 137 

78. Stigmal plates of ticks Margaropus, Ixodes, and Dermacentor. . . . 138 
78a. Photomicrograph of stigmal plate of Texas fever tick 138 

79. Fowl tick, adult and larva 139 

80. Spinose ear tick, nymphal form 141 



LIST OF ILLUSTRATIONS xvii 

FIG. PAGE 

81. The castor-bean tick 143 

S2. The American dog or wood tick 144 

83. Linguatula rhinaria 153 

84. Planarian wonn 156 

85. Liver fluke, Fasciola hepatica 157 

86. Reproductive organs of liver fluke 158 

87. Fasciola hepatica, F. americanus, Dicrocceliuni lanceatum 161 

88. Life history of Hver fluke 162 

89. Blood fluke, male and female 168 

90. Segment of Taenia saginata, showing sexual organs 171 

91. Tapeworms of the horses 175 

92. Tapewonn of cattle and sheep, Moniezia expansa 176 

93. Fringed tapeworm of sheep, anterior segments 177 

94. Tapewonn of dog, Dipjdidium caninum ISO 

95. Rostellum of Dipylidium caninum 180 

96. Egg packet and Cysticercoid of Dipylidium caninum 180 

97. Tapeworm of dog. Taenia hydatigena 180 

98. Tapeworm of dog, Taenia pisiformis 180 

99. Tapewonn of dog, Echinococcus granulosus 180 

100. Rostellum of tapewonn of cat. Taenia taeniaeformis 184 

101 . Diphyllobothriimi latum 186 

102. Tapewonn of chicken, Clioanotsenia infundibulifonnis 189 

103. Scolex of Choanotaenia infundibulifonnis 190 

104. Scolex of Davainea tetragona of chicken 190 

105. Scolex of Davainea echinobothrida of chicken 190 

106. Tapeworm of man, Taenia saginata 196 

107. Diagram of Cysticercus 198 

108. Fragment of beef muscle, showing cysts of Cysticerus bovis 198 

109. Scoleces of Taenia solium, T. saginata, and DiphA'llobothrivun Latum . . . 199 

110. Eggs of Taenia saginata and T. solium 200 

111. Alature segments of Taenia saginata and T. solium 200 

112. Stages in tapeworm development 201 

113. Portions of adult gid tapeworm, Multiceps multicejis 205 

114. Diagrammatic section of Multiceps (Coenurus) cyst 206 

115. Brain of lamb, showing furrows produced by young gid bladderwonn. . 206 

116. Gid bladderwonn, showing immature tapewonn heads 206 

117. Diagram of Echinococcus hydatid 211 

118. Echinococcus granulosus, showing hydatid with brood capsules 214 

119. Transection of Ascaris equi 217 

120. Posterior extremit^^ of male nematode worm 218 

121. Cephalic extremity' of an ascarid worm 229 

122. Ox^vuris equi 236 

123. Belascaris marginata, showing head and male and female 238 



xviii LIST OF ILLUSTRATIONS 

FIG. PAGE 

124. Egg of Ascaris lumbricoides 240 

125. Ascaris lumbricoides, male and female 240 

126. Heterakis perspicillum, male and female, and H. vesicularis of poultrj^ 242 

127. Setaria labiato-papillosa, male and female 245 

128. Gong5donema scutata, anterior and posterior views 247 

129. Dirofilaria imonitis, male and female 249 

130. Lung wonn of sheep and goat, Dictj'-ocaulus filaria, male, female, and 

eggs 257 

131. Lung wonn of sheep, goat, and rabbit, Synthetocaulus rufescens, male 

and female 257 

132. Lung worm of cattle, Dictyocaulus viviparous 259 

133. Lung worm of pig, Metastrongylus apri, male and female 260 

134. Stomach worm of sheep, goat, and cattle, Hsemonchus contortus, 

female 269 

135. Hsemonchus contortus, anterior portion of body 269 

136. Hsemonchus contortus, enlarged posterior extremity of male 269 

137. Cooperia curticei, male and female 270 

138. Cooperia curticei, enlarged anterior portion 270 

139. Ostertagia marshalli, male and female 270 

14Q. Trichostrongylus instabiUs, male and female 271 

141. Ostertagia ostertagi, male and female 273 

142. Ostertagia ostertagi, posterior extremity of male enlarged 273 

143. Nematodirus fihcollis, male and female and enlarged anterior portion . . 274 

144. Cooperia oncophora, male and female 274 

145. (Esophagostomum columbianmn, male and female 282 

146. QEsophagostomum columbianum, enlarged anterior portion 282 

147. (Esophagostomum colmnbianum, enlarged bursa of male 283 

148. (Esophagostomum venulosum, male and female 283 

149. (Esophagostomum venulosum, enlarged anterior portion 283 

150. (Esophagostomum venulosum, enlarged bursa of male 283 

151. (Esophagostomum radiatum, male and female 286 

152. (Esophagostomum radiatum, enlarged anterior portion • 286 

153. (Esophagostomum radiatum, enlarged bursa of male 286 

154. Chabertia ovina, male and female 287 

155. Strongjdus equinus, male and female 288 

156. Hook-worm of dog and cat, Ankylostoma canina, male and female . . 292 

157. Bunostomum phlebotomum, male and female 293 

158. Tracheal wonn of poultry, Syngamus trachealis, male and female. . 294 

159. Dioctophjine renale, male 297 

160. Trichuris ovis, male and female 300 

161. Trichuris ovis, egg 300 

162. Trichinella spiralis, male and female 301 

163. Trichinella spirahs, encysted larva in muscle 302 



LIST OF ILLUSTRATIONS xix 

FIG. PAGE 

164. Trichiuella spiralis, microphotograph of cyst 304 

165. The thorn-headed wonii, Gigautorhjnichus hirudinaceus 307 

166. Cephalic extremity of thorn-headed wonn 307 

167. The horse leech 308 

168. Anieba proteus 312 

169. Spirocheta palhda 327 

170. Hen sufTering from acute spirochetosis .• 328 

171. Piroplasma bigeminum 348 

172. Fonns of Sarcosporidia, shown in infected muscle 351 

Plates. Page 

I. Texas fever tick, male and female, with details 146 

II. Texas fever tick, stages of engorgement and details 147 

III. Evolution of the parasite of kala-azar 317 

IV. Life cycle of the malaria parasite 321 

V. Various species of Trypanosoma 331 

YI. Percheron stallion before and after development of dourine 338 

VII. Percheron mares, sho\\'ing chronic dourine and last stage 340 

VIII. Coccidian life cycle 344 

TABLES 

Classification of parasites of the class Insecta 20 

Life history of horse botfly, Gastrophilus equi 55 

Life history of sheep botfly, (Estrus ovis 63 

Classification of parasites of the class Arachnida 96 

Sunmaary on nonparasitic periods in de^•elopment of Texas fever tick 149 

Sunmiary on parasitic periods in development of Texas fever tick 150 

Life histories of dog tick and Texas fever tick compared 151 

Classification of parasites of the phylum Platyhehninthes 157 

Life history of liver fluke, Fasciola hepatica 163 

Life history of beef tapewonn. Taenia saginata 172 

The principal tapewomis, with their larvfe and hosts 173 

Synopsis of tapewonn larvse 194 

Life history of the gid tapewonn, Multiceps multiceps 207 

Life history of Echinococcus granulosus 213 

Classification of parasites of the phylum Coelhelminthes 222 

Life history of Trichinella spiralis 303 

Classification of parasites of the phylum Protozoa 322 



PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 



PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 

PART I 

PRELOIIXARY CHAPTERS 

THE EXTERNAL PARASITES 

CHAPTER I 
INTRODUCTION 

The earth's vast hiboratory of hvmg matter inchides a flora and fauna 
in which all of the hiohly diversified forms encomiter conditions operating 
to restrict their miiltiphcation and to govern the predominance of cer- 
tain forms over others. These contUtions are constituted, first, by 
topographic and climatic variations rendering certain localities more or 
less inhospital)le to some organisms, while others may be uninfluenced or 
perhaps benefited. Second, there is the behavior of living things toward 
one another; this may l)e relatively harmonious or there may be an 
intense rivalry in which organisms encroach or prey one upon the other, 
the least fit for the strife being driven to less favorable habitats, progres- 
sively dwarfed, or ultimately becoming extinct. Though most of these 
inhibitive influences are not apparent to cursory observation, the}' are, 
nevertheless, numerous and varied as well as constant in their operation, 
constituting a prime factor in the evolution and specialization of organic 
forms. 

There is, then, a perpetual struggle for existence, which may lead to 
the seeking of shelter from the conflict in a changed and often degenerate 
mode of life to which the organism becomes adaptively modified. Thus, 
through such uifluences, a terrestrial animal may be driven to an ar- 
boreal, or even an aquatic or semiaquatic, existence. A defenseless Httle 
member of the Insectivora burrows and becomes subterranean, while 
another finds protection in the nocturnal habit; others seek the shelter 
of caves or rock crevices, and we often find creatures, usually somewhat 
degenerate, in places which seem to us quite unfavorable to their sup- 
port. While in such cases the animal continues to lead a free and in- 



2 PARASITES OF THE DOMESTIC ANIMALS 

dependent, often solitary existence, on the other hand, a communion of 
life's interests may be estabhshed between two organisms which, it is 
surmised, is founded upon some nmtual advantage in the strife. To 
such association the general term s>Tiibiosis has been applied and each 
of the organisms concerned is referred to as a SAaubiont. Though there 
is by no means a uniformity in the appHcation of terms referring to the 
symbiotic relationship, a usage is adopted here that seems best defined, 
and by which s>mibiosis is subdivided into the three categories, (1) mu- 
tualism, (2) commensalism, and (3) parasitism. In the first there is a 
reciprocal advantage derived from the union; in the second but one 
s\Tnbiont is benefited though the other suffers no harm, while in the 
third division one receives an advantage to the detriment of the animal 
or plant which it invades. There is, however, no sharp line of demarca- 
tion between these three states of living together, and it may be difficult 
to determine in some cases whether one or both symbionts receives 
benefit from the union, or whether one is or is not injured by it. 

One of the more obvious examples of mutualism is the case of the- 
hermit crab and the sea anemone. This crab selects a shell, as that of 
the whelk, for its habitation, from the opening of which it projects only 
its head and claws. On the surface of the shell may often be found a sea 
anemone fastened near the opening with its mouth and tentacles in the 
vicinity of the crab's head. The anemone in this position not only in a 
measure serves to conceal the hermit crab from its enemies, but the 
creature that would prey upon the crab must first reckon with the 
dangerous stinging threads with which the tentacles of the anemone are 
armed. The anemone, in its turn, is benefited by being carried about 
by the crab and aided in this way in obtaining its food. 

Such associations are not always of mutual advantage, and maj' be 
more in the nature of an invasion of one animal upon or within the 
body of another, the invading animal alone deriving benefit, while the 
animal upon which the association is forced, though not benefiting, 
ma}^ in no way suffer from it. A familiar form of this living together 
(commensalism) is the little crab so commonly found in the shell of the 
oyster. The oyster is not harmed by its presence, but the crab is bene- 
fited by the protection which the shell affords. Another more curious 
example of such association is afforded among the vertebrates by the 
species of Remora, or suck fishes, which have the first dorsal fin modified 
into a sucking disk on top of the head. By means of this disk it attaches 
itself to a shark or other large fish, and is thus carried about, detaching 
itself only to secure food. Its benefit from such association is in being- 
carried to new feeding grounds without effort of its own, and in the 
shelter from its enemies which the body of the larger fish may afford. 
The host, on the other hand, cannot be benefited, nor does it seem to 
suffer by the presence of its uninvited guest. 



INTRODUCTION 3 

AVhether this relationship between different species is of reciprocal 
advantage or of benefit to but one, neither of the s\anbionts lives upon 
or at the expense of its co-sjnnbiont, and neither has entirely renounced 
its independence. In true parasitism the invading animal lives upon the 
tissues of its host, deprives it of a portion of its nourishment; or is in 
other wa3'S injurious to it. There are many examples of this form of 
symbiosis, and students of animal life are familiar with the conditions 
that seem always to attend it, such as the degenerative and adaptive 
modifications occurrmg in the parasite. 

It is the common habit of many animals, however, to prey upon the 
bodies of other animals, and we should distinguish, so far as we may, 
between those which are predatory and those which are parasitic. The 
former are free and exercise their powers of sense and cunning in snarmg 
or chasing their pre}', while the latter, in fully acquired parasitism, live 
on or in the bodies of their victims, often burrowing into and consummg 
the bod}' tissues, leading a lazy, beggarly existence in which all of the 
faculties of special sense and prowess, so highly developed m predatoiy 
animals, become degenerate and atrophied. 

Parasitism is found throughout the range of animal life from the 
unicellular to the vertebrate, and, though a sharp distinction between 
predaceous and parasitic animals may not be made, in view of the de- 
grading influence of the parasitic habit, the difference between the 
simplicit}^ of degeneration and the simplicity of primitiveness should be 
clearly defined. In the development of a primitively simple animal the 
young stages are more simple than in the adult and it has only simple 
ancestors. In the degenerate animal, on the other hand, the ancestors are 
often more complex and the young stages are of a higher grade than the 
stage of the adult. The adoption of any mode of life which withdraws 
from the activities necessar}^ to survival in a free existence seems to 
bring about this condition of degradation. Of this we have a remarkable 
example outside of the realm of parasitism in the Tunicata. These 
aberrant animals, in the stage of the free-swimming larva, have a chordal 
axis which in nearly all of the different species becomes entirely lost 
before they reach maturity. After passing the "tadpole" stage there 
follows an extreme specialization to the fixed habit which most tunicates 
retain throughout their adult life, becommg what are commonly known 
as sea squirts, mere attached, plant-like sacs, emitting a jet of water 
when disturbed, and from Avhich all chordate features have been entirely 
lost. 

The degenerative changes which a parasite undergoes concern mostly 
the nervous system, the organs of locomotion, and those of nutrition, the 
nervous system becoming reduced to the most indispensable portion, 
while of the sense-organs nothing may be left except those of touch. The 
locomotor apparatus may become modified into claws or hooks for 



4 PARASITES OF THE DOMESTIC ANIMALS 

clasping the hairs of the host, or it may ahiiost if not completely dis- 
appear and be replaced b}^ such organs of fixation as sucking-disks. As 
the contents of the alimentary canal or tissue fluids of the host upon 
which the verminous parasite is nourished need scarcely any digestion, 
the digestive organs become simplified or may be quite lost, the absorb- 
tion of nutriment in the latter case taking place entirely through the 
body integument, as in some of the worms which infest the intestines of 
man and other animals. The degree of decadence will depend upon the 
degree of dependence upon the host. In this latter respect the parasitism 
may be optional, as in the case of the mosquito, which may live upon the 
juices of plants but prefers a meal of warm blood, or it may be obligate, 
depending upon another for its means of subsistence, though such 
obligate parasites as the biting flies, fleas, and bedbugs may also live 
free and only occasionly visit their hosts, a form of parasitism which 
may be accompanied by little modification of the adaptability to a free 
life'. 

In the event of the parasite becoming progressively degraded into one 
which not only seeks its host for food, but has become dependent upon 
it for both its nutrition and place of abode, all of the above mentioned 
phenomena of adaptation become more conspicuous. There is furnished 
a very good example of such a transformation in the sheep tick (Melo- 
phagiis ovinus), not a true tick, however, but a fly which, originally an 
occasional visitor, has, like the louse, taken permanent abode upon its 
host. No longer taking the aerial flight of its discarded free life, this 
fly has become wingless, and, furthermore, is enabled to pass its entire 
life cycle upon the body of the host animal by a remarkable method of 
reproduction involving the retention of the eggs in the oviducts until 
development has passed through the larval stage. It is not until ready to 
pass into the stage of the pupa that the larva? are extruded, the pupal 
case then being attached to the individual wool fibers. From this case 
the young insect, on becoming sufficiently developed, makes its escape 
and proceeds to feed and grow, thus rounding out a complete parasitic 
cycle. 

While the easy life of the parasite tends to degeneration, the perpetua- 
tion of the species becomes more precarious, and the organs of reproduc- 
tion undergo a marked development. If a host animal dies most of its 
parasites, especially those existing in the interior of its body, die with 
it, and, were it not that the eggs find lodgment in a new host, the parasitic 
species would in a short time become extinct. The transmission of but 
few of these eggs is successfully accomplished, and in compensation they 
must be produced in enormous numbers, well protected from the many 
elements of destruction which they encounter. The mode of reproduc- 
tion is one of the principal factors determining the conditions of par- 
asitism, and, while the above modifications pertain more to those 



INTRODUCTION 5 

dwelling continuously upon or within the bodies of their hosts, we have 
in the ffistridse, among the dipterous insects, a cycle involving internal 
parasitism duruig the larval stage, a familiar example being the common 
horse botfly (Gastrophilus intestinalis) , the development of which is 
given on page 54. It is plain that a very small percentage of the eggs 
deposited by this fly can reach the horse's mouth, and that, having got 
thus far, many of the larvae must be destroyed or pass entirely through 
the intestinal tract without having succeeded in becoming fixed to the 
mucous membrane. For this there seems to be compensation in the 
large number of eggs deposited by the persistent female. 

While in some cases the complete life cycle of a parasite requires but 
one host, often, for reasons stated in the foregoing, two successive and 
generally specifically different hosts are required. A rather compli- 
cated example of the latter case is the life history of the common liver 
fluke (Fasciola hepatica), one of the flat worms infesting in its adult 
state the livers of Herbivora. It will be noted in referring to the cycle of 
this parasite, given in detail elsewhere (page 160), that it is a very 
hazardous one, and that its completion must depend upon the co- 
operation of numerous favorable conditions. The eggs, of which each 
individual fluke is capable of producing in the neighborhood of one 
hundred thousand, must reach the exterior amid surroundings favorable 
to their hatching. If hatched, the larva must escape its many aquatic 
enemies and within a few hours find a suitable snail host. Providing the 
snail is not eaten by a duck, or does not otherwise perish during this 
phase of the cycle, it issues from its host as the free-swimming cercaria, 
when it is again liable to fall prey to various small aquatic animals. 
Escaping this and })ecoming encysted, the chance of any herbivorous 
animal coming along and swallowing it is very small. The relation of 
the enormous number of eggs, and the number of individuals which one 
egg may produce, to the survival of the species amid conditions fraught 
with such dangers seems quite evident. 

In general it may be said as to the propagation of parasites that their 
prodigious fecundit}^ and the great vital resistance with which most of 
them are endowed enables species to survive and perpetuate their kind 
amid varied destroying influences which otherwise would bring about 
their extermination. The tapeworms inhabiting the intestines of man 
and other animals, afford another example of extreme parasitism accom- 
panied by this remarkable development of the reproductive function. 
Here is a creature so altered to its degenerate existence that it has be- 
come devoid of mouth and intestine, the body consisting of a scolex, 
usually referred to as the head, from which are give off segments which 
remain united until there is formed, as in Tcenia saginata of man, a 
band-shaped colony of from twelve hundred to thirteen hundred or 
more, passing back from the worm's attachment to a length which may 



6 PARASITES OF THE DOMESTIC ANIMALS 

exceed twenty feet. After about the six hundredth, each segment is a 
mature and sexually complete individual, which later, as it is pushed on 
by new segments formed at the head, becomes filled with fecundated 
eggs. By the successive detachment of these "ripe" segments and their 
passage from the body of the host, it has been estimated that Taenia 
saginata might throw off in a year as many as one hundred and fifty 
million eggs, of which but an infinitesimal number, as is quite evident, 
will reach the bodj' of their proper bovine host for larval development. 
Again, having been so fortunate, it is improbable that the larvae will, 
while living, reach the intestines of the human host necessary for their 
further development into adult worms. 

Here, then, is an animal well showing the degree of degeneration 
which may be reached in extreme parasitism; there are no organs of 
locomotion, no organs of special sense, no organs of digestion, no organs 
of respiration, and none of true circulation. The body consists of a long 
band of connected segments, each, when mature, bisexually complete 
and in itself a sort of independent reproductive individual, the entire 
energy of the organism concentrated upon the function of reproduction 
that the perpetuation of the species may be insured amid the perils with 
which this process is beset. 

In many forms permanently parasitic there is an early period of 
development in which organs of locomotion are distinctly present, but, 
as the animal matures, these fail to develop or become lost. If it is 
assumed that this gradual loss of organs, change of structure, and protec- 
tive transmission of the embryo to an intermediate host is due to the 
parasitic life, it seems reasonable to conclude that all of the parasitic 
groups have been derived from free-living forms, and that, as parasitism 
became a more fixed habit, such structural changes were in the course of 
time brought about as would make this mode of life obhgatory. A re- 
view of the observed facts, then, in their biologic relationship, leads to 
the conclusion that symbiosis, of which parasitism is a form, has its 
causative basis in the struggle for existence, the symbiotic association in 
more or less measure mitigating the hazards to one or both symbionts. 
It further follows that, though some forms have undergone an extreme 
modification, through related contemporary free-living types, their true 
systematic position may be established. 



CHAPTER II 

FORMS OF PARASITIS:^I AND INFLUENCE UPON THE HOST 

Forms of Parasitism 

The student of parasitology will be greatly aided by an orderly and 
progressive pursuit of the subject, an elementary' requisite to which is a 
broad conception of what is implied b}' the various terms used in the 
chapters which are to follow. Those below are not given with the recom- 
mendation that the}' be memorized as to the exact wording set forth in 
their definitions; more essential is such an understanding that examples 
can readily be picked out, a typical illustration always being in mind for 
application to the tenn at hand. With such a conception the student 
should be able to fonnulate his own definitions, and this will be of more 
advantage to him than accepting those set forth according to the con- 
ceptions of another. 

Though some of the following tenns have been treated of in foregoing 
introductory remarks, the}^ are here included for more concise definition 
and to make the list inclusive. 

Symbiosis is the more or less pennanent living together of two plants, 
two animals, or an animal and a plant, the union being in a measure 
beneficial to both, or to one with or without hami to the other. 

Symbiont, — one of two organisms partaking of symbiotic relationship. 

Mutualism is a fonn of sjmibiosis in which both sjTubionts are in 
more or less measure benefited by the union. 

Commensalism is that form of s^inbiosis in which but one sjinbiont 
is benefited, while its co-s\anbiont is neither benefited nor harmed by 
the union. 

Helotism is a form of s}^nbiosis in which one organism appears to 
enslave the other, enforcing it to labor in its behalf. The term is applied 
to such association in certain insects. 

Parasitism is that form of sjanbiosis in which one symbiont, for pur- 
poses of procuring food, or food and shelter, visits briefly, or takes up 
its abode temporarily or pennanently, upon or within the bodj' of its 
co-s>inbiont which is harmed by the union. The sAinbiont receiving 
the advantage is known as the parasite, to which the one injured is the 
host. 

Phytoparasites are parasites which belong with the vegetable 
kmgdom. 



8 PARASITES OF THE DOMESTIC ANIMALS 

Zooparasites are parasites which belong with the animal kingdom. 

Optional Occasional Parasites are those which only fleetingly visit 
their hosts to obtain nourishment, but are not dependent upon them for 
either nourishment or shelter. Example, mosquitoes. 

Obligate Occasional Parasites are those which do not permanently 
live upon their hosts, but are dependent upon them for nourishment and 
to some extent for shelter. Examples, fleas, bedbugs. 

Determinate Transitory Parasites are those in which the parasitism 
is hmited to a definite phase or phases in their Hfe history, during which 
time the parasitism is ol:)ligate and continuous. Examples, botflies, 
ticks. 

Permanent Parasites are those in which the parasitism extends from 
the hatching of the egg to the stage of reJDroduction in the adult. Exam- 
ples, lice, many entozoa. 

Fixed Parasites are those which cannot pass spontaneouslj^ from 
one host to another. Examples, larvae of botflies, Linguatula, helmin- 
thes. 

Erratic Parasites are those which in their adult state may pass 
readily from one host to another of the same or different and widely 
separated species. Examples, mosquitoes, biting flies, ticks, leeches. 

Determinate Erratic Parasites are those which may pass from one 
host to another of the same species, or a species closely allied to the one 
abandoned. Examples, lice, psoric Acarina. 

Monoxenous Parasites are (a) those the eggs of which are expelled 
by the host, the embryos, while still within the eggs, passing to a new 
host where hatching and development to the adult occurs. Example, 
Ascaris. 

(b) The eggs having been hatched, the larvae are noiu'ished in suitable 
conditions of moisture and temperature, but cannot imdergo further 
development until they have reached the body of their host. Example, 
Hemonchus contortus. 

Heteroxenous Parasites are (a) those which pass to their definitive 
host by an intermediate or transitory host, in which they cannot attain 
their complete development; consequently, a reciprocal transmission 
between these hosts is essential to the development and propagation of 
the parasite. Examples, tapeworms, Plasmodium of malaria. 

(b) The eggs of the parasite are hatched in the Ijody of the host, the 
embryos invading the tissues of the same individual host and not at^ 
taining the adult state until they have reached a second host. Example, 
Trich ineUa sp ira lis. 

Transmigration is a term applied to the passing of heteroxenous 
parasites from one host to another. 

Incidental or Stray Parasites are those which under natural condi- 
tions are occasionally found in unusual hosts. Examples, Gigantorhyn- 



FORMS OF PARASITISM 9 

chus hirudinaceiis (specific in pig, incidental in man) ; Fasciola hepatica 
(specific in Her])ivora, incidental in man). 

Ectoparasites (Epizoa) are those which are parasitic to the surface 
of the body, whether burrowing into the integument, living upon it, or 
only occasional visitors. Examples, scab mites, ticks, and other Acarina, 
lice, flies. All of the arthropodal parasites with scarcely an exception. 

Endoparasites (Entozoa) are parasites which enter the body of their 
host, inhabiting its alimentary canal, blood, and other tissues. Exam- 
ples, Linguatula, larvae of the botflies, and almost all of the helminths. 

Helminthes is a term under which are grouped all of the worms 
generally jiarasitic, with the exception of a small number in which the 
body is annulated. The group is not a natural zoological one and is 
used mostly in parasitology. 

In terms used to designate parasitic diseases it is customary to apply 
the name of the genus, or other group name to which the parasite be- 
longs, as the root, to which is added the suffix asis or osis. As for ex- 
ample : 

Pediculosis, the condition produced l)y the presence of lice upon 
the skin; Acariasis, the condition produced by the presence upon the 
skin of mites and other Acarina; Filariasis, the condition produced by 
Filaria. And thus we have Ascariasis from Ascaris, Oxyuriasis from 
Oxyuris, Strongylosis from Strongylidae, Trichinosis from Trichinella, 
Taeniasis from Tseniidae, Fascioliasis from Fasciola, Helminthiasis from 
Helminthes, and Trypanosomiasis from Trypanosoma. 

In view of the many factors to be considered, the formulation of 
exact and limiting interpretations of terms bearing upon kinds of par- 
asitism is scarceh^ possible. It cannot be claimed for the above series, 
therefore, that it is entirely satisfactory as stated and defined. For our 
conceptions we must rely upon the ])ehavior of the typical rather than 
the isolated or synthetic, and be content to regard anj^ grouping based 
upon modes of parasitism as more convenient than exact. It is difficult 
to circumscribe parasitism ; while we speak of the parasitic mode of life 
as a form of symbiosis, it may well be questioned whether such insects as 
mosquitoes and biting flies bear a true sjanbiotic relationship to their 
hosts; their fleeting visits certainly do not constitute the living together 
as usually implied by the term. Again, we may not be able to draw a 
distinct fine between certain predaceous and certain parasitic forms. 
From the more general viewpoint, however, it may be repeated that all 
predaceous animals voluntarily, by the exercise of their powers of stealth 
and cunning, seize upon and aim to destroy their prey at once, feeding 
upon the body. There are parasites which use a degree of stealth in 
approaching their victims, as certain parasitic Diptera, though the 
invasion of the body of its victim by the parasite is more often passive 
than voluntaiy. While the parasite may appropriate a share of the 



10 PARASITES OF THE DOMESTIC ANIMALS 

nutriment of its host or feed upon its host's tissues, it is detrimental to 
the parasite's welfare to destroy its host. To destroy the body of the 
animal harboring it would mean the sacrifice of the parasite's means of 
subsistence as well as in most cases its shelter. When the host animal 
dies its internal parasites die with it, and, if it were not for the previously 
occurring transmission of their offspring to new hosts, the species would 
rapidly perish. Serious disturbance or death of the host due to its 
parasites is usually brought about by their presence in large numbers, 
in which case there is the operation of numerous pathogenic factors. 
A fatal termination may follow rapidly, but more often there are afebrile 
morbid phenomena running a prolonged course. In no case is the victim 
at once destroyed and wholly or in part devoured. 

The parasite is always smaller and weaker than its host, and in many 
cases its influence upon the latter is not observable. It may be said in 
general that the degree of injury will depend upon the following prin- 
cipal factors: 

Influence Upon the Host 

1. The Number of Parasites Present. — ^A tapeworm or one or two 
ascarids in the intestines may not produce a noticeable effect upon the 
host. If these parasites are numerous there may be serious disturbances 
in the host resulting from the deprivation of nutriment which has been 
appropriated by the infesting worms, from the toxins which they elab- 
orate, or a more acute effect may be brought about through obstruction 
of the bowel by large numbers of the parasites in mass. 
* 2. Their Location. — An encysted larva of the beef or pork tapeworm 
in its usual location will do no observable harm to its host, but if it 
should lodge in the eye or central nervous system it might give rise to 
serious disorders. As a rule, intestinal parasites are less harmful than 
those which invade the blood or respiratory tract, while of the external 
parasites, those which burrow into the integument are more injurious 
than those living upon the surface. 

3. The Nature of their Food. — Any parasite which feeds upon the 
tissues of its host is more harmful than one which merely appropriates 
a share of the latter's ingested nutriment. The blood-sucking worms, 
when present in considerable numbers, bring about serious depletive 
disturbances, while such worms as the adult ascarids, nourishing mainly 
upon the residue of food materials, are, in general, less harmful. Sucking 
lice, armed with piercing mouth parts, are more disturbing to the animal 
harboring them than the biting lice which feed upon cutaneous debris 
and the products of their irritation. 

4. Their Movements. — Serious pathologic conditions may be 
brought about by the migrations of parasites or their change from a 
usual to an unusual position. Muscular trichinosis, the collective 



INFLUENCE UPON THE HOST 11 

effect of the movement of myriads of embryos of Trichinella spiralis, is a 
typical instance. An otherwise relatively harmless parasite may work 
its way into a duct, or, findmg lodgment in an unusual organ, set up 
inflannnatory changes and abscess formation. Again, by verminous 
wandering, fistulous connnunications may be established between 
contiguous organs normally possessing no direct connection. 

5. Age of Host. — Young animals are predisposed to endoparasitic 
invasion. To forms which penetrate or are more or less migratory, the 
more tender tissues of the young offer less resistance than in older 
animals. Verminous broiichitis is a form of strongylosis observed almost 
exclusively in animals which are immature. The reduced vitalitj- of 
old age invites the invasion of both external and internal parasites; 
there is not only a lessened ability to defend from attack, but reduced 
activities and secretions of the intestines, skin, and other organs de- 
crease the capability of eliminating either ecto- or entozoa. 

Such external parasites as mosquitoes, flies, ticks, and bedbugs are of 
greatest pathologic importance as disseminators of infectious diseases, 
acting either as direct carriers or as intermediate or definitive hosts of 
the infecting organism. Malaria, Texas fever, and forms of trypan- 
osomiasis are among diseases which are known to be spread only b}' this 
means, while the possibilities as carriers of typhoid and other malignant 
infections engendered by the habits of the connnon house fly are well 
known. 

That Helminthes elaborate materials toxic to their host has been 
demonstrated in experiments mth the isolated poisons. It is obvious 
that, in cases of heavy infestation especially, this toxic effect must be 
considerably contributed to by the products of decomposition of dead 
worms. 

Etiology. — So varied are the conditions that surround the propaga- 
tion and existence of parasites that the consideration of the causes of 
parasitic diseases is best embodied in chapters devoted to their particular 
occurrence. However, certain circumstances favoring parasitism may 
be here briefl}' considered. 

Crowded and miclean housing favors the propagation and spread of 
parasites of both man and domestic animals. For this reason lice and 
scab mites find their most favorable season in the winter months, when 
their transmission from animal to animal is facilitated and the reduced 
activities of the skin offer less resistance to their invasion. Pediculosis 
and the scab acariases are seldom seen, however, in stables that are 
well kept, or among animals where due attention is paid to cleanliness of 
the skin. The sunnner, on the other hand, is the season of attack by 
adult parasitic Diptera, and it is during the months at pasture that 
ticks most rapidly propagate and crawl upon their hosts. 

In helminthiasis the influences of environment as an etiologic factor 



12 PARASITES OF THE DOMESTIC ANIMALS 

are more subordinate to the mode of development of the infecting 
species. Sheep grazing upon low, marshy land and in the vicinity of 
ponds are more exposed to infestation with flukes, because there are 
present conditions essential to the molluscan intermediate host in which 
the fluke at the stage of the miracidium must find lodgment. Infestation 
of the pig or the ox with the larvae of the tapeworms of man is most 
likely to occur where untreated human excrement is used as a fertilizer, 
or where their food may otherwise be directly or indirectly contaminated 
with such material, while invasion of the human host with the adult 
worm only occurs after ingestion of the tissues of the larval host. The 
majority of ova of worms expelled by the host fail to find a new host, or 
meet with unfavorable conditions and are lost. Some, as those of 
ascarids, are very resistant and may find their proper host after months 
of exposure to destructive influences. Migration is facilitated to some 
extent where hatching takes place with the laying of the egg, as in the 
strongyles of the respiratory tract and in Trichinella. 

While much remains to be determined as to the life histories of many 
of the internal parasites, clinical experience indicates that low and wet 
pasturage, with access to stagnant collections of water, is a strong 
etiologic factor in helminthiasis, either as harboring possible aquatic 
intermediate hosts of the worms, or as a vehicle which, directly or by 
drainage, spreads infestation by dissemination of their germs. 



CHAPTER III 

PHYLUM I. ARTHROPODA 

While there are advantages in arranging a description of parasites 
according to their location, as those of the skin, those of the intestines, 
those of the liver, those of the circulation, etc., the fact that so many 
in their life histories pass certain stages in different organs and different 
species of hosts makes such an arrangement somewhat confused. It 
seems better, therefore, to treat of the natural history of each parasite 
in the parasite's order, essentially including such anatomical and zoolog- 
ical migrations as may be involved, while at the same time considering 
its pathogenic influences in these varying locations. 

Aside from the phytoparasites, which are not included in this work, 
the parasites infesting man and domestic animals are distrilnited among 
four grand divisions or phyla of the animal kingdom, which, in the order 
of their zoological grade, are Protozoa, Platyhelminthes, Coelhelminthes, 
and Arthropoda. The last named group contains most all of the external 
parasites and is the first to be considered in the pages to follow. 

As a foundation for the scientific control of parasitism and for the 
recognition of adaptations to its various forms, at least an elementary 
knowledge of the structure and habits peculiar to the phylum and its 
subdivisions to which the parasite belongs is of essential importance. 
Only the more prominent structural features upon which the separation 
of the different groups and their subgroups is based will be given here. 
For more detailed study the student is referred to an advanced text-l:)Ook 
in zoology. 

The phylum Arthropoda includes such animals as the craj^fish, crabs, 
lobsters, spiders, centipedes, and insects. The body is provided with a 
hard or leathery external chitinous skeleton divided into a number of 
segments demarcated externally by constrictions, each segment in the 
adult, or a certain number of the segments, bearing jointed appendages 
(Fig. 1). There are usually two or more body regions distinguished by a 
special modification of the constituant segments. In order that move- 
ments may take place between the segments of both the body proper 
and of the appendages, the cuticle at these points is thin and delicate 
(Fig. 9), forming joints which are protected by an overlapping of the 
heavier chitinous armor. 

All arthropods periodically molt, the process consisting of the break- 
ing and casting off of the chitinous cuticle after it has loosened from the 



U PARASITES OF THE DOMESTIC ANIMALS 

underlying tissue and a new cuticle has been formed. While the cuticle 
is at first thin and soft, later it becomes hard and unyielding, therefore 
the moltings are necessar}- for the accommodation of growth and occur 
periodically as long as this growth continues. Chitin, to which the 
firmness of the cuticular exoskeleton is due, is an organic substance in 
which lime salts may be deposited, as occurs in the Crustacea. The 
skin is never ciliated, nor do ciliated cells occur in any other organs of 
the body. 

The musculature (Fig. 9) consists of a large number of separate 
muscles passing from one segment to another and attached at their 
extremities to the mner side of the skin, their contraction bringing about 
movements of the segments of the body and appendages one upon the 
other. They may be attached by so-called tendons, which consist of 
invaginations of the cuticle surrounded by a corresponding invagination 
of the epidermis. The muscle fibers are striated and multinuclear. 

The digestive tract (Fig. 2) passes directly, or with little flexion, 
through the bodj^, the mouth being at the anterior end and usually 
ventral, the anus posterior. Accessory organs, as salivary glands and 
liver, may or may not be present. 

Of the circulatory system (Figs. 2 and 3) the most constant portion is 
the heart, which is usually tubular and located dorsally. On each side of 
the organ are openings provided with valves through which the blood 
passes to be propelled forward. From the large arteries the blood may 
pass directly into blood sinuses, or it may course through capillaries and 
veins, though the vascular system is never entirely closed. The blood is 
usualty a colorless fluid with colorless amoeboid corpuscles. 

In aquatic forms (Crustacea) respiration is b}' gills, while in the air- 
breathers it may be by tracheae (Figs. 5 and 6), consisting of tubular 
ramifications from without to within the body, or by peculiar infolding 
modifications of the integument functioning as lungs. In some of the 
lower forms respiratory organs are entirely absent, the function in such 
cases being diffused over the entire body surface. 

In various spaces within the bodies of Arthropoda are frequently 
found fat bodies, a connective tissue the cells of which, richly laden with 
fat, serve as a store of nourishment. The fact that products of tissue 
metabolism, such as uric acid, have been found m the fat body, leads to 
the conclusion that it also acts as a place of storage for substances of 
excretion before their elimination by the excretory organs, which latter 
greatly vary in the different groups. In insects and arachnids these 
organs are represented by the Malpighian tubes, long glandular canals 
which open into the posterior portion of the digestive tract. 

The nervous system consists typically of a ventral chain of ganglia 
connected by a double longitudinal nerve cord. In well-developed seg- 
ments the ganglia are large, and a pair of ganglia to each segment might 



ARTHROPODA 15 

be expected, as in the annelid worms. In the Arthropoda, however, 
there are differences due to fusion of the segments, in which case there 
is also fusion of their ganglia. Such fusion is usually accompanied by 
more or less shortening of the body, an example of which is afforded b}^ 
the spiders and crabs where the whole ventral chain unites in a single 
ganglionic mass. From the most anterior of the ventral ganglia there 
spring two nerve cords which pass on either side of the esophagus to 
unite above it with the paired cerebral ganglion or brain, Ijong in the 
head. This ganglion remains distinct, its dorsal position preventing its 
fusion with ganglia of the ventral chain. 

Of the sense organs the most highly developed are the eyes, which are 
compound (Fig. 6), or appear as simple ocelli. In many arthropods 
there are both of these forms, while others are provided only with ocelli, 
and in some arthropods eyes are absent. In the compound eyes the 
cuticle covering them is divided into hexagonal facets, the number of 
which varies with different groups from a dozen to two thousand or 
more, each of these areas corresponding to a small chitinous lens. The 
compound eyes are two in number, while the number of oceUi varies. 
The latter are very small and have their highest development in the 
spiders. 

With rare exceptions the sexes are separate, and reproduction is 
generall.y by fertilized eggs, though parthenogenesis occurs, in some 
cases having a certain relationship to the life history. Usually the sexes 
can be readily distinguished by the difference in size and by various 
modifications of the appendages. 

Of the subgroups of the phylum Arthropoda only those containing 
parasitic species of medical interest will be considered in this work. 
These are included in the two classes Insecta and Arachnida, which, 
with scarceh' an exception, contain all of the external parasites. It is 
not correct, however, to say that the arthropodal parasites are exclusively 
external, as certain insects and arachnids pass a phase of their develop- 
ment within the bodies of their hosts. 

Class I. Insecta 

Arthropoda (p. 13). — In number of species the insects constitute 
the largest of all animal groups. The body is essentially segmented, and 
is di\'ided into three regions, — head, thorax, and abdomen, which are 
distinctly marked off from each other (Fig. 1). 

The head is usuall}- freely movable at its jmiction with the thorax, 
and typically bears on each side a compoimd eye (Figs. 1 and 7), be- 
tween which there may be a varying number of simple ocelli. 

Arising from the head are a pair of antennae which consist of seg- 
ments varying in size, shape, and number according to species. 



16 



PARASITES OF THE DOMESTIC ANIMALS 



The mouth parts (Fig. 4) undergo great modification, though all may 
be referred to a common type. This is well presented in its primitive 

condition by the grasshopper, 
in which we have the labrum, 
or upper lip, represented b}' a 
broad unpaired plate situated 
in front of the mouth. Under 
the labrum is a parr of strong- 
jaws, the mandibles, each con- 
sisting of a single unsegmented 
piece with a cutting innei' edge, 
the two having a lateral move- 
ment. Following the mandibles 
is the first pair of maxillae which 
are prehensile and gustatory in 
function. These have a num- 
ber of joints and bear curved 
and segmented palpi. The sec- 
ond pair of maxillae are fused 
to form a single plate, — the la- 
bium, which is accessory in func- 
tion to the first pair of max- 
illae, and, like the latter, bear a 
pair of segmented palpi. The 
labium forms the posterior and 
the labrum the anterior bound- 
ary of the mouth. 

The thorax (Fig. 1) has three 
a middle, — the. mesothorax, 




Fig. 1. — Diagram of an Insect, with Head and 
Thoracic Segments Disarticulated: a, head, 
bearing compound eyes, simple ocelli, and 
antennae; b, prothorax; c, mesothorax; d, meta- 
thorax; e, abdomen; f, ovipositor. The pro-, 
meso-, and metathorax each bear a pair of legs; 
the meso- and metathorax each a pair of wings. 
1, Coxa; 2, trochanter; 3, femur; 4, tibia; .5, tar- 
sus, terminating in a claw (after Orton, by 
Dodge; Copyright, 1894, by Harper & Brothers). 

segments, an anterior, — the prothorax 




Fig. 2. — Diagram of the Principal Internal Anatomical Parts of an 
Insect: m, mouth; or, crop; st, stomach; i, lower portion of intestine; 
a, anus; h, heart; s, salivary glands; c, cerebral ganglion; n, ventral 
ganglion; Mp, Malpighian tulDules; o, ovaries; g, genital aperature (after 
Boas, by Kirkaldy & Pollard). 



and a posterior, — the metathorax. 
somewhat fused. 



The last two of these are usuallv 



ARTHROPODA 



17 



There are three pairs of legs, each thoracic segment l^earing one pair 
(Fig. 1). The leg is divided into five articulated parts, — coxa, trochanter, 
femur, tibia, and tarsus. The attachment to 
the bod}' is by the short coxa, to which is joined 4, 
the trochanter which is also short. Following •'^Cr^<f7^'~>r~>''~^ 
the trochanter are two long segments, — the fe- v ^ 

mur and tibia, the former considerably thicker fig. 3.— Diagram of In- 
than the latter and contaming the muscles. The sect's Heart: c, constriction 

tarsus, or foot, follows the tibia, and consists of between two chambers; V, 
', „ , , , , • valves (after Boas, bj' Kirk- 

a number ot short segments, the last bearmg aidy & Pollard), 
hook-like structures, or claws. 

Usualh' there are two pairs of wiiigs arising dorsally from the meso- 




FiG. 4. — Mouth-parts of Locust, a biting insect: Labruni, or upper-lip, 
above, on each side of which are the mandibles, or upper pair of jaws. 
Labium, or under lip, with labial palpi below. Ma.xillae, or lower pair of 
jaws, with maxillary palpi, to right and left (from photomicrograph of 
mounted specimen, by Hoedt). 

and metathorax (Fig. 1). They consist, when fully developed, of two 
closely apposed chitinous outgrowths, between which are extensions of 



18 



PARASITES OF THE DOMESTIC ANIMALS 



the blood sinuses and tracheae. Sometmies the anterior, sometimes the 
posterior pair is the larger, and both may be flexible and adapted for 
flight. In some insects (beetles) the anterior pair is modified to form 
wing-shields, or elytra, which are hard, but 
slightly flexible, structures serving to cover 
and protect the posterior wings during rest. 
Some insects possess but one pair of wings 
(dipterous), while in others wings are entirely 
absent (apterous). 

The abdomen is segmented, the number of 
segments varying with different groups. Each 
segment consists of two cuticular plates (Fig. 6), 
the dorsal tergite and the ventral sternite, 
which are united laterally by a softer mem- 
brane, the pleurite. There are no abdominal 
limbs or limb-like appendages. 

Respiration is by tracheae (Fig. 5), a system 
of tubes containing air. These communicate 
with the outside by 
the spiracles (Fig. 
6), small s>anmet- 
r i c a 1 1 y disposed 
openings located 
laterally, one pair 
on the meso- and 
one pair on the 
metathorax and a 
pair on each of the 
abdominal segments 
except the most posterior. Just inside of the spiracles the tracheae are 
usually united by longitudinal trunks from which are given off fine 
branches which ramify and anastomose within the body. Respiration 
is effected by abdominal movements of contraction and expansion. 

Insects are mostly oviparous. In some the developed embryo is 
released from the egg while still within the body of the parent, or this 
may occur just as the egg is extruded. There are also pupiparous forms 
where the young pass from the body of the female ready to enter the 
pupal stage in their development. 

In order that the newly hatched larvae may be supplied with nourish- 
ment, the eggs are generally deposited where suitable food is present. 
In many insects oviposition occurs by means of an ovipositor, a tube- 
like organ which is developed from the posterior abdominal segments 
and which may project free from the body or may be retracted into it. 
In the Hjmienoptera the ovipositor may be modified to serve as a sting, 





Fig. 5. — Diagram show- 
ing the chief trunks of the 
tracheal system of an in- 
sect (after Boas, by Kirk- 
aldy & Pollard). 



Fig . 6. — Abdomen of Lo- 
cust, s howing Spiracles 1, 2,13, 
4, 5, 6, 7 and 8, one on each side 
of each of the abdominal seg- 
ments; A, auditory sac (drawn 
in part from Packard's Zool- 
ogy). 



ARTHROPODA 



19 




Fig. 7. — Head of 
the bee, showing 
compound eyes, the 
three ocelH, and the 
antennae. — Magni- 
fied (after Orton, by 
Dodge; Copyright, 
1894, by Harper & 
Brothers) . 



a weapon of defense provided with poison glands. From its nature the 
sting is essentially onh' possessed by the females. 

Some insects on leaving the egg develop directly to the adult stage, 
the larva in most cases differing from the adult prin- 
cipalh' in the absence of wings. In such cases there 
is a slight change of form with successive molts, 
the wings being ultimateh' acquired. Here the meta- 
morphic process is not thorough, and is therefore 
referred to as mcomplete metamorphosis. The ma- 
jorit}^ of insects when hatched from the egg bear 
no resemblance to the adult, and there is no observ- 
able gradual approach to this form. The larva is 
characteristically worm-like and an active and vora- 
cious feeder, a number of molts occurring with the 
increase in size during this stage. There then 
intervenes between the larval and adult stages a 
period of pupation, during which the animal is quies- 
cent and a series of changes 

occur in the body. At the 

conclusion of these changes the pupal case 

splits and the imago emerges, which, with 

the unfolding of the ap- 
pendages and hardening 

of the cuticle, has in all 

essentials developed into 

the complete sexual 

adult. In this form 

of development the 

changes are distinct, and 

the process is referred 

to as complete meta- 
morphosis (Fig. 8). 
The duration of life 

in insects, including the 

stages of the egg, larva, 

pupa, and adult, usually 

does not extend bej^ond 

a year. With quite a 

number it is much 

shorter than this, while 

with others it maj' be a 

matter of several years, 

an extreme example of 

larval longevity being 





Fig. 9. — Diagram of termi- 
nal segments of arthropod leg, 
with muscles, a, articulation; 
f, flexors; e, extensors Cafter 
Boas, by Kirkaldy & Pollard). 



Fig. 8. — Metamor- 
phosis of the House Fly, 
showing oval, larval, 
pupal, and adult stages. 
On the right is an en- 
largement of the foot; 
on the left, the foot pad, 
showing sticky, glandu- 
lar hairs; on upper left, 
a tsetse fly (from photo- 
graph of drawing by 
author). 



20 PARASITES OF THE DOMESTIC ANIMALS 

afforded by the seventeen-year cicada. Most of the insect Hfe is occupied 
bj' the larval stage, during which the greatest growth takes place. With 
a few exceptions, as honey bees and ants, the period of the adult is short, 
in some cases a few daj^s or even hours. The life of the adult is de- 
voted to the activities concerned in reproduction, and the insect usualh'' 
dies when this is accomplished. 

Of the class Insecta the five following orders contain parasites of 
medical importance: 

Order I. Diptera — Flies, gnats, and mosquitoes. 

Order II. Siphonaptera — Fleas. 

Order III. Siphunculata — Sucking lice. 

Order IV. Mallophaga — Biting lice. 

Order V. Hemiptera — Bedbugs and allies. ^Vv^^s-a.^ 

Classification of Parasites of the Class Insecta 

Phylum I. Arthropoda. P. 13. 
Class A. Insecta. P. 15. 
Order 1. Diptera. P. 23. 

Family (a) Culicidse. Mosquitoes. P. 24. 
Genus and Species: 

Culex pungens. Pp. 25, 26. 
Anopheles quadrimaculatus. P. 26. 
A. pmictipennis. P. 28. 
Ades calopus. P. 29. 
Family (b) Simuliida?. Buffalo gnats. P. 31. 
Genus and Species: 

Simulium pecuarum. Animals attacked, equines and cattle. 
P. 32. 
Family (c) Tabanidse. Horseflies, gadflies. Animals attacked, 
equines, cattle. P. 35. 
Genus and Species: 

Tabanus atratus. P. 35. 
T. lineola. P. 36. 
Family (d) Muscidse. House fly and allies. P. 37. 
Genus and Species: 

Musca domestica. Injurious to man and domestic animals 

by irritation and contamination. P. 37. 
Stomoxvs calcitrans. Animals attacked, equines and cattle. 

P. 39! 
Lyperosia irritans. Animals attacked, cattle. P. 41. 
Glossina palpalis. Animals attacked, man, and domestic 

and wild animals. P. 44. 
G. morsitans. Animals attacked, same. P. 44. 
G. longipalpis. Animals attacked, same. P. 44. 



ARTHROPODA 21 

Chiysomyia macellaria. Larvae attack flesh and mucous 

surfaces of man and lower animals. P. 50. 
Sarcophaga sarraceniae. Larvae attack fresh meat and 

wounds of animals. P. 52. 
Calliphora vomitoria. Larvae attack fresh and decomposing 
meat and wounds. P. 52. 
Family (e) Hippoboscidae. P. 47. 
Genus and Species: 

Melophagus ovinus. Host, sheep. P. 47. 
Family (f) CEstrida?. Botflies. P. 53. 
Genus and Species: 

Gastrophilus intestinalis. Host, equines. P. 53. 
G. hemorrhoidalis. Host, equines. P. 57. 
G. nasahs. Host, equines. P. 57. 
Hypoderma lineata. Host, cattle. P. 57. 
H. bovis. Host, cattle. P. 58. 
CEstrus ovis. Host, sheep. P. 62. 
Order 2. Siphonaptera. P. 65. 

Family (a) Pulicida?. Fleas. P. 65. 
Genus and Species: 

Ctenocephalus canis. Host, dog. P. 65. 
C. felis. Host, cat. P. 65. 
Pulex irritans. Host, man. P. 65. 
Order 3. Siphunculata. Sucking lice. P. 70. 
Family (a) Pediculida^. P. 70. 
Genus and Species: 

Haematopinus asini. Host, equines. P. 73. 
H. eurysternus. Host, cattle. P. 74. 
Linognathus vituli. Host, cattle. P. 74. 
L. pedalis. Host, sheep. P. 76. 
L. stenopsis. Host, goat. P. 77. 
Ha?matopinus suis. Host, hog. P. 77. 
Linognathus piliferus. Host, dog. P. 78. 
Pediculus humanus. Host, man. P. 79. 
P. corporis. Host, man. P. 79. 
Phthirius pubis. Host, man. P. 79. 
Order 4. Mallophaga. Biting lice. P. 7L 
Family (a) Philopterida?. P. 71. 
Genus and Species: 

Trichodectes equi. Host, equines. P. 73. 

T. pilosus. Host, equines. P. 73. 

T. scalaris. Host, cattle. P. 75. 

T. sphaerocephalus. Host, sheep. P. 76. 

T. chmax. Host, goat. P. 77. 



22 PARASITES OF THE DOMESTIC ANIMALS 

T. latus. Host, dog. P. 78. 

T. subrostratus. Host, cat. P. 79. 

Goniocotes gallinae. Host, chicken. P. 82. 

G. gigas. Host, chicken. P. 82. 

Lipeurus caponis. Host, chicken. P. 83. 

L. heterographus. Host, chicken. P. 83. 

Goniodes styhfer. Host, turkey. P. 84. 

Lipeums meleagridis. Host, turkey. P. 84. 

Philopterus icterodes. Hosts, ducks and geese. P. 84. 

Lipeums anatis. Hosts, ducks and geese. P. 84. 

Philopterus C3'gni. Host, swan. P. 86. 

Ornithonomus cygai. Host, swan. P. 86. 

Goniocotes compar. Host, pigeon. P. 86. 

Goniodes damicornis. Host, pigeon. P. 86. 

Lipeurus columbse. Host, pigeon. P. 86. 
Family (b) Liotheidse. P. 71. 
Genus and Species: 

Menopum trigonocephalum. Host, chicken. P. 83. 

M. biseriatuni. Host, turkey. P. 83. 

Trinotum luridum. Hosts, ducks and geese. P. 84. 

T. lituratuni. Hosts, ducks and geese. P. 86. 
Order 5. Hemiptera. P. 89. 
Family (a) Cimicidse. P. 90. 
Genus and Species: 

Cimex lectularius. Hosts, man, poultry, etc. P. 90. 



CHAPTER IV 

MOSQUITOES AND (iXATS 

Order I. Diptera. — Insecta (p. 15). The dipterous insects have only 
the anterior pair of wings developed, the posterior pair being repre- 
sented b}' rudimentary structures called halteres, or balancers, which 
are supposed to function as organs of balance. In some parasitic forms 
(sheep '4ick," bat fly) wings are entireh' wanting. 

The head, thorax, and abdomen are sharply defined. The mouth 
parts are adapted for sucking, the haustellum, or sucking tube, being- 
formed by the labium and labrum, within which lie the mandibles and 
maxillae, which may be modified into blade-like structures for piercing. 
With this structure the insect sucks the juices of plants or penetrates the 
skin of animals and feeds upon their blood. In the flies the antennae are 
short, consisting of but three well-developed joints. The three thoracic 
segments are frequently fused, and the tarsi have five segments. 

Metamorphosis is complete. The larvae are apodal grubs, maggots, 
or wrigglers, the latter aquatic (mosquitoes). 

Parasitism. — The dipterous group of insects includes a number of 
species varying in their grade of parasitism from optional occasional to 
obligate occasional and permanent. They are chiefly of importance 
from the medical viewpoint as carriers of bacterial and animal parasitic 
infection, investigations within recent 3'ears well establishing the fact 
that certain serious and often fatal diseases of man and domestic animals 
are spread by these insects either as essential hosts or as direct carriers 
of the infectrtig organism. As essential hosts a part of the development 
of the pathogenic organism must essentially be undergone in the insect. 
As direct carriers they may inoculate directly into the blood with con- 
taminated piercing or biting mouth parts, or the}-- may simply trans- 
port disease germs upon their bodies and appendages, contaminating 
wounds, food, or any object upon which they may alight. 

As blood-sucking pests and sources of torment in the habitations of 
man and in the fields and stables of his live stock, many of these two- 
winged insects are of veiy considerable economic as well as pathologic 
importance. In view of all that at the present time can be charged 
lip against them, the}' are well worthy of the increasing attention they 
are recei\'ing with a view to their more effectual control. 

Of the families of the order Diptera containing parasitic species, six 
are here considered, as follows: 



24 PARASITES OF THE DOMESTIC ANIMALS 

Family I. Culicidse — Mosquitoes. 
Family II. Simuliidse — Buffalo gnats. 
Family III. Tabanidae — Horseflies. 
Family IV. Muscidae — House fly and allies. 
Family V. Hippoboscidae — Sheep "tick." 
Family VI. (Estridae— Botflies. 

Family I. Culicid^; Mosquitoes 

Diptera (p. 23). — The mosquitoes are slender-bodied Diptera with 
narrow wings which have a distinctive fringe of scale-like hair upon 
their margins, and in most cases also on each of the wing veins. In the 
female the prol)oscis is long, slender, and adapted for piercing. The 




Fig. 10. — Egg-mass of Culex pungens, above; young larva, greatly enlarged, at right; 
young larvae, less enlarged, below; enlarged eggs above at left (after Howard, Bui. No. 4, 
Bureau of Entomology, Dept. of Agr.). 

males do not suck blood, differing from the females in the absence of 
the piercing stylets and in the possession of plumose antennae. 

Mosquitoes have an adaptation to a very wide range, flourishing 
equally as well in the frigid regions of the Arctic and Antarctic as in the 
humid heat of the tropics. Until comparatively recent years few species 
Avere known, but more intensive study, in view of their importance as 
carriers of disease and as pests of man, has brought the mosquito fauna 
of the world up to about one hundred genera including seven hundred 
species, of which there are about fifty known in the United States. 

Breeding Habits. — In the larval stage all the known mosquitoes 
are aquatic, l^ut such differences occur in their life histories and habits 



MOSQUITOES AND GNATS 25 

that 110 one species will serve as typical of the group. In observations 
conducted by L. O. Howard at Washington, D. C. (1900 Rept.), upon 
the species Cidex pungens it was determined that the eggs were laid upon 
the water surface in masses of a variety of shapes, often described as 
boat-shaped because a common form is that of a pointed ellipse (Fig. 10). 
The number of eggs in each mass varied from two hundred to four hun- 
dred, all arranged perpendicularl}' and in longitudinal rows. The in- 
dividual eggs are slender, somewhat pointed at the tip, and at the bottom 
broader and blunt, having a length of 0.7 mm. and a diameter of 
0.16 mm. at the base. 

It has been demonstrated that under the advantageous conditions 
of the warm summer months eggs may hatch in less than a day from the 
time they are deposited. The larvae, issumg from the 'under side of the 
egg mass, are elongate, with head, thorax and alxlomen distinct, the 
head bearing prominent antenna? each consisting of a single segment. 
About the mouth is a mass of prehensile filaments. The abdomen is 
segmented, and respiration is by tracheae which open at the apex by 
means of the anal siphon. They appear to undergo four molts, and, 
under favorable conditions, may be transformed into pupae in about 
seven days. Studied at a period when the larva is nearly full grown, 
it is seen to remain near the surface of the water with its respiratory 
tube at the exact surface and its mouth below receiving food which is 
directed to it by the rotary movements of the mouth filaments. Occa- 
sionly the larva descends below the surface, but, by a series of wrigglings, 
quickly returns. The return is only accomplished by considerable 
exertion, as, once below the surface, the tendency of the larva is to sink 
rather than to rise. If, therefore, for any reason it is unable to suffi- 
ciently exert itself to again reach the surface, it will perish. The eflficacy 
of the film of oil spread upon the water may be thus explained; it not 
only prevents access to the air, but, by its deleterious effect, renders the 
larva unable to exert sufficient muscular force to recover the position 
necessary for respiration and buoyancy. 

The transformation to the pupal stage, occurring under favorable 
conditions aljout the seventh day, is marked by a great enlargement of 
the thoracic segments (Fig. 11). Here the reverse of the just described 
physical phenomena obtains; the pupa is lighter than water, and, unlike 
the larva, effort is required to sink rather than to rise. It remains mo- 
tionless at the surface, when disturbed descending to the bottom by 
violent wrigglings. As soon as these exertions cease it will again grad- 
ually rise. The differential structure of the pupa is noticeable in the 
tnlargement of the thorax, and in that the air tubes no longer open at 
the abdominal apex, but through two ear-like processes on the thorax, 
the pupa remaining ujiright at the water's surface instead of head down- 
ward as in the larval stage. Since the adult insect emerges from its 



26 



PARASITES OF THE DOMESTIC ANIMALS 



pupal case at the thorax, there is an apparent adaptability in this re- 
versal of position. 

The common house or ''rain barrel" mosquito of the Northern 
United States, Culex pimgens (Fig. 12), breeds throughout the summer, 
broods developing wherever there may be standmg water, as in pools, 
troughs, cans, discarded bottles, gutters, etc. The adults of this species 
may pass the winter in the shelter of darkened retreats, such as the 
cellars of houses, behind furniture, outbuildings, and wood piles, 
emerging from their hibernation in the spring to deposit their eggs. 
Many first spring broods in temperate climates hatch from eggs that 
have been carried over the winter months, the eggs seeming to stand 
desiccation in dry locations to promptly hatch in pools left by the spring 




Fig. 11. — Pupa of Culex pungens at left; pupa of Anopheles quad- 
rimaculatus at right — greatly enlarged (after Howard, Bui. No. 25, 
Bureau of Entomology, Dept. of Agr.). 



rains, or even in water from melting snow during the warmer days of 
late winter. 

In refutation of the assertion often made that mosquitoes cannot 
ovulate without a meal of warm blood, it has been demonstrated in 
experiments upon some of our common blood-sucking species that fe- 
males as well as males can not only be kept alive for a long period when 
given access only to plants, but will, under such conditions, repeatedl}^ 
breed. 

Pathologic Importance. — While their preference for blood has made 
them of primary general interest as pests in the habitations of man, 
mosquitoes are of the greatest importance medically, not only as possible 
direct transmitters of disease, but as specific bearers of infection, bring- 
ing about such diseases as malaria, yellow fever, and possibly filariasis. 
There have been many convincing demonstrations that malaria is 
transmitted exclusively by the bite of mosquitoes, only, however, by 
species belonging with the anopheles group, of which Anopheles quadri- 



MOSQUITOES AND GNATS 




Fig. 12. — Culex pungens: a, fomalo, from side; b, male, from above; c, front 
tarsus of same; d, middle tarsus; e, hind tarsus; f, genitalia of same, i, scales from 
hind border of wing; h. scales from disk of wing — enlarged (after Howard, Bui. 
No. 4, Bureau of Entomology, Dept. of Agr.). 



28 



PARASITES OF THE DOMESTIC ANIMALS 



m-aculatus (Fig. 13) and A. punctipennis have been most often observed 
in the United States. While elaborate keys and tables are necessary even 
to the entomologist for more exact differentiation, it is not a difficult 
matter to decide whether a mosquito is or is not a transmitter of malaria, 




Fig. 13. — Anopheles quadrimaculatus: Adult: male at left, fe- 
male at right — enlarged (after Howard, Bui. No. 25, Bureau of 
Entomology, Dept. of Agr.). 

the two genera Ciilex and Anopheles being readily distinguished by the 
following more prominent characteristics : 

The adult Culex, when at rest upon a wall, usually holds the body 




Fig. 14. — Anopheles at left, Culex at right — enlarged (after Howard, Bui. No. 25, 
Bureau of Entomology, Dept. of Agr.). 

parallel with the wall, or with the abdomen slightly inclined toward it, 
the angle formed by the abdomen with the head and thorax giving a 



MOSQUITOES AND GNATS 



29 



hunchback appearance. The proboscis projects forward but not suffi- 
ciently so as to be on a line with the axis of the body (Fig. 14). The 
palpi in the female are short, in the male usually long. The wings, as a 
lule, are without spots. 

Adults of the anopheles group when thus at rest hold the body at an 
angle of about forty-five degrees with the wall's surface, the abdomen 
directed outward (Fig. 
14) . The proboscis 
projects forward on a 
line with the axis of 
the body. In both 
sexes the palpi are 
about as long as the 
proboscis. The wings 
are usually spotted. 

The larva of Culex, 
when at the surface 
of the water, rests in 
an oblique or vertical _ 
position with the re- 
spiratory tube at the 
exact surface (Fig. 15). 

The resting larva of 
Anopheles floats in a 
horizontal position just 
beneath the surface. 
There is no respiratory 
tube, the spiracles 
opening on the eighth 
abdominal segment 
which is applied to 
the surface (Fig. 15). 

Eggs of Culex are de- 
posited upon water in 
masses, the rafts of eggs 
often being more or less 
boat-shaped (Fig. 10). 

Anopheles lay their eggs upon water unmassed, the eggs floating 
singly by lateral expansions (Fig. 16). 

The mosquito breeding in our Southern States which carries yellow 
fever from man to man, ^Edes calopus iStegomija calopiis, S. fasciata), 
is rather peculiarly marked. Upon each side of the thorax is a broad, 
silveiy, curved line, between which there are two parallel median lines 
and a slender discontinuous line, the whole pattern presenting somewhat 




Fig. 15. — At top, half grown larva of Anopheles in 
breathing position, just beneath the surface film. At 
bottom, half grown larva of Culex in breathing position 
— greatly enlarged (after Howard, Bui. No. 25, Bureau 
of Entomology, Dept. of Agr.)- 



30 



PARASITES OF THE DOMESTIC ANIMALS 



the shape of a lyre. At the base of each abdominal segment is a narrow, 
silvery band, while on each side there is a silvery spot. At the base of 
each segment of the black legs there is a distinct white band. 

Highly domestic, this species will breed in collections of water about 
and within the habitations of man, the larvae often being found in small 
household water receptacles, such as flower pots, vases, etc. Of its 
habits acquired by long association with man, Howard thus speaks: "It 
approaches stealthily from behind, retreating upon the slightest alarm. 




Fig. 16. — Group of eggs of Anopheles quadrimaculatus as they appear resting 
naturally on the surface of the water— enlarged (after Howard, Bui. No. 25, 
Bureau of Entomology, Dept. of Agr.). 

The ankles and, when one is'sittmg at a table or desk, the under side of 
the hands and wrists are favorable points of attack. It attacks silently, 
whereas other mosquitoes have a piping or humming note. The warning 
sound has doubtless been suppressed in the evolutionary process of its 
adaptation to man. It is extremely wary. It hides whenever it can, 
concealing itself in garments, working into the pockets and under the 
lapels of coats, and crawling up under the clothes to bite the legs. In 
houses it will hide in dark corners, under picture moldings and behind 
the heads of old-fashioned bedsteads. It will enter closets and hide in 
the folds of garments." 



MOSQUITOES AND GNATS 31 

Effect upon Live Stock. — That mosquitoes are a source of much 
annoyance and actual suffering to live stock can be attested to by stock- 
men. Horses and cattle pasturing upon low lands and amid vegetation 
where the insects abound are especially exposed to attack, the pests 
often hovering about them in clouds, while upon the bodies of the 
animals large numbers may be seen with abdomens engorged with the 
blood of their victims. Loss of condition and the falling off of produc- 
tiveness in dairy herds must essentially follow this interference with 
their pasturage and comfort. 

Control. — The most effectual preventive measures dealing with mos- 
quitoes are those directed against the larvie. The abolition of breeding 
places being of first importance, all receptacles for standing water, such 
as rain barrels, cans, vaults, gutters, etc., should be removed, covered, or 
otherwise made impossible to access and propagation of mosquitoes. 
Pools should be drained, or, if this is not feasible, ma^- be treated with 
kerosene; or small fish, which feed upon the larvae, may be introduced 
into the mosquito-breeding ponds. The quickest and most satisfactory 
way to destroy larvae and pupae is by the formation of the kerosene 
film upon the water's surface. The oil is best applied for this purpose 
as a spray, or, if but a small area is to be treated, it may be thrown upon 
the surface and the water then vigorously stirred. About one ounce of 
kerosene to fifteen square feet of water surface will be sufficient, and this 
application should be repeated at intervals of about three weeks. 

Such measures are directed only against local species, and, essentially, 
there must be community action for it to be effective. Migratory forms, 
such as are bred in the marshes near our coasts, cannot thus be reached, 
their eradication constituting a problem demanding state control. 

For indoor protection in mosquito-infested districts, screening is of 
course essential. In spite of the most thorough screening, however, 
mosquitoes will enter in various ways, as through openmg doors and upon 
the clothing of persons passing in. As remedies against those which 
have gained access to houses various kinds of repellents are used. Burn- 
ing pyrethrum powder will often rid a room of mosquitoes, a convenient 
method being to sprinkle the powder upon a heated shovel; or small 
cones may be molded from the dampened powder and, after drying, 
burned. Oil of pennyroyal or citronella applied to handkerchiefs or 
lightly touched to the hands and face, though objectionable to some, 
will usually insure a ]5eaceful night against the pests. 

Family II. Simuliid.e 

Dipt era (p. 23). The flies of this family are known as black flies, 
black gnats, or buffalo gnats, the latter name derived from their peculiar 
humpback appearance. They are dark colored, with short thick body, 



32 



PARASITES OF THE DOMESTIC ANIMALS 



short eleven-segmented antennae, no single eyes, broad wings, and stout 
legs. Only the females are provided with piercing mouth parts. 

The larvae, so far as known, are aquatic. The eggs are deposited in a 
compact layer upon some object, usually rock, near the surface of a 
flowiiig stream. Upon hatching the larvae drop into the stream and live 
attached to sticks, stones, or other objects under the surface of swiftly 
running water. They may detach themselves and move about in a 
looping manner similar to that of the measuring worm, or they may 
be carried by the current for considerable distances. Respiration is 
carried on by gill-like processes. 

SiMULIUM PeCUARUM 

The Southern Buffalo Gnat (Fig. 17). Simuliidae (p. 31). The adult 
female is nearly a quarter of an inch in length, the male somewhat 

smaller. The color of the body is 
black, and it is covered with light 
brown hairs which are arranged upon 
the thorax in such a manner as to give 
a longitudinal striped appearance, the 
abdomen showing upon its dorsal side 
a broad grayish stripe widening out 
toward the abdominal apex. The 
male notably differs from the female 
in that the eyes are much larger and 
join each other in the middle line. 
The individual facets on the' upper 
part of the eye are considerably larger 
than those of the female. 

The larva (Fig. 18) agrees in gen- 
eral appearance with that of other 
species of Simulium. It is about 
three-eighths of an inch in length, 
twelve-segmented, somewhat con- 
stricted in the middle, enlarging to- 
ward both ends. The posterior end 
is the larger and is somewhat club- 
shaped. In addition to the mouth, 
the head possesses two fan-shaped bodies which are prehensile in func- 
tion. On the top of the last abdominal segment there are rows of 
booklets, while in the vicinity of the rectum are organs of respiration 
consisting of three tentacles to which the large tracheae lead. 

The pupa (Fig. 19) has a peculiar tuft of respiratory filaments starting 
from each side of the thorax. The upper portion of the pupal case is 
open, exposing the head and permitting the respiratory filaments to 




Fig. 17. — Simulium pecuarum, female 
— enlarged (after Osborn, Bui. No. 5, 
Bureau of Entomology, Dept. of Agr.). 



MOSQUITOES AND GNATS 



33 





have free access to the water. The pupa is firmly attached to sticks, 
leaves, or other submerged objects. On emerging from the pupal case 
the fly at once rises to the surface and, expanding its 
wings as it runs upon the water for a short distance, flies 
swiftly away. 

Occurrence and Efifect. — The buft'alo gnat has been 
found in Alaska and throughout the Eastern United 
States, but appears in greatest numbers in the South, 
especially about the mouths of rivers and creeks. During 
the worst years the whole of the Lower Mississippi Valley 
as far north as St. Louis may be invaded. 

The attacks b\' swarms of this bloodthirsty and vic- 
iously active insect upon southern live stock is a source 
of serious injury and loss. Cattle and horses will mani- 
fest the presence of the swarms by frantic efforts to de- 
fend against the attack, cattle rushing wildly about and 
horses and mules trying to escape by running awa^-. 
The most destructive raids of the fly usually occur in 
the months of March and April. They are exceedingly 

swift in their flight, darting at their pj^ 
victims in search of a suitable place to muiium pecua- 
draw blood, and in their bite instilling J"''™' ,^f Y"^"!"' 

, T • 1 1 • /• larged (after Os- 

a poison. Many ammals die irom ex- born, Bui. No. 5, 
combmed with the 



haustion, combmed with the toxic Bureau of Ento- 
effects of the poison from the bites. ™°J°^^'' ^^p*- °^ 
Bronchitis and pneumonia, resultmg 
from the inhalation of large numbers of the insects 
from which the exhausted animal becomes totally 
unable to defend itself, may also contribute to the 
conditions leading to its miserable death. 

Control. — Outbreaks in heavily infested districts 
may be lessened in frequence and severity by the 
clearing out of logs and other debris in the beds of 
streams, thus reducing the number of objects for 
attachment of the larvse. Unlike those of the mos- 
quito, the larvae of Simulium thrive best in swiftly 
running and well aerated water, therefore the re- 
moval of any submerged object causing shallow and swift h' moving 
water reduces the possibilities for breeding at this point. 

Protection. — The black gnat dislikes smoke, therefore, as prevention 
against its attacks in fields and barnyards, the mamtenance of smudges 
is of value. Other repellents, such as fish oil, oil of tar, or other oleagin- 
ous and resinous substances, either singly or in combination, are 
applied to the surface of the body, affording a measure of protection 



Fig. 19. — Simulium 
pecuarum, pupa — en- 
larged (after Osborn, 
Bui. No. 5, Bureau of 
Entomologv, Dept. of 
Agr.). 



34 PARASITES OF THE DOMESTIC ANIMALS 

from attacking swarms. The most effectual protective measure is the 
sheltering of animals in a cool dark stable during the hours of the day 
when the swarms are most active. 

Treatment. — Animals weakened by the bites may be given a dif- 
fusive stimulant and have the parts locally treated with a solution of 
bicarbonate of soda or ammonia water. 



CHAPTER V 
THE FLIES 

Family III. Tabanidae. — Diptera (p. 23). This family includes 
the so-called horseflies or gadflies. The head and e3'es are large, the 
latter often of a brilliant color. The third segment of the antennae has 
four to eight rings. The proboscis of the female is adapted for piercing 
the skin of animals. The males do not attack animals; their mouth 
parts are less powerful than those of the females and are adapted for 
feeding upon the juices of plants. The bod}- has fine hairs; there are no 
bristles. The flight is strong and swift and is accompanied with a 
tormenting buzzing noise. 

The eggs of Tabanidae are deposited in masses upon vegetation grow- 
ing in wet marshy ground. The larvae are carnivorous and are aquatic 
or live in moist earth. 

Tabaxus Atratus 

Tabanidae (p. 35). This is the common large black horsefly, having 
a M'ide distribution in the United States. It is one of the larger species 
of the family, measuring an inch or more m length and having a body so 
uniformilv black as to attract attention even when it is upon the wing 
(Fig. 20)." 

The eggs are deposited in masses, usually upon the stems of plants or 
grasses growing in the vicinity of water. In about seven to ten days 
there is hatched a large cylindrical larva which tapers to a point at both, 
ends and has an integiunent that is somewhat transparent (Fig. 20, a). 
At this stage it lives mostl}^ in moist earth into which it burrows actively, 
feeding mainly upon worms and the larvae of other insects. While the 
period of larval life is long, in some observed cases lasting several months 
to a year, the stage of the pupa (Fig. 20, b) is short, the fly emerging from 
its case after a few daj-s of pupation. It is probable that the broods are 
carried over the winter in the larval stage. 

Effect. — The black horsefly is common throughout the summer 
months, attacking cattle and horses usualh' in the open sunny pasture, 
and inflicting with its long piercing mouth parts a painful wound. For- 
tunately it does not attack in swarms as does the buffalo gnat, nor does 
it instill with its bite as much poison. There is evidence of the severity 
of its wound, however, in the drop of blood which wells up from the seat 
of puncture after the insect has left its victim. While there is little 



36 PARASITES OF THE DOMESTIC ANIIVIALS 

after-effect from the bites of these flies they are a source of much tor- 
ment to Hve stock, not only in the pain produced by their punctures, 
but in their pecuhar buzzing, which often terrorizes nervous animals, 

their frantic and heed- 
less efforts to escape not 
infrequentlj^ resulting 
in injury. 

There can be no 
doubt that the Taba- 
nidae are concerned in 
the transmission of cer- 
tain blood diseases of 
live stock. It is signif- 
icant as to their possi- 
bihties as carriers of 
anthrax that their at- 
tack seems to be more 
commonl}'- d ir e c t e d 
against cattle than 
horses. 

Protection. — Little 
can be done toward 
repelling the attacks of the flies. Horses at work are protected in a 
measure by covering them with nets. Where the flies are numerous and 
especially tormenting it is advisable to remove pasturing animals to a 
well-shaded retreat during the warmer and sunnier parts of the day. 




Fig. 20. — Tabanus atratus: a, larva; b, pupa; c, adult 
(after Osborn, from Riley, Bui. No. 5, Bureau of Ento- 
mology, Dept. of Agr.). 



Tabanus Lineola 

Tabanidffi (p. 35).— The Green-head Horsefly (Fig. 21). This is the 
most widely distributed species in North America. It is about five- 
eighths of an inch in length. E^^es large and bril- 
liant green, abdomen brown, with a conspicuous 
grayish line running longitudinally on its dorsal 
side. It is from this marking that its specific 
name is derived, while the peculiar coloring of the 
eyes gives to it the common name "Green-head." 

The oval, larval, and pupal stages are passed uneok (after Osbom; 
in moist places, and in other respects the life cycle from Packard, Bui. No. 5, 
is similar to that of Tabanus atratus, though the 
larval period is probably not so long. 

The Green-heads appear in especially large numbers in marsh}^ dis- 
tricts during the brightest and hottest days of the summer. They 
attack in greater numbers than the Black Horseflies, and, especially 




Fig. 21. — Tabanus 



Bureau of Entomology, 
Dept. of Agr.). 



. THE FLIES 37 

during warm and sunny weather, their harassing bites cause much 
torture to horses and cattle. They do not fly in cloudy weather, and 
they perish with the frosts of earl}^ autumn. 

Family IV. Muscid.e 

Diptera (p. 23). — These flies are small to moderately large, with bodies 
thinly covered with hairs or bare. The bristles of antennae are feathery. 
The abdomen is four-segmented and smooth except for bristles near the 

The larvae are apodal maggots, feeding upon decaying animal or veg- 
etable matter. 

MUSCA DOMESTICA 

The common house fly (Fig. 8). Muscidae (p. 37). — The mature in- 
sect is 02ie-fourth to five-sixteenths of an inch in length; dorsal region of 
thorax grayish in color and bearing four longitudinal stripes; abdomen 
yellowish. The mouth parts are trumpet-shaped, adapted for sucking 
up liquids but not for piercing. 

Life History. — In about ten days after emerging from the pupal 
case the female fly seeks suitable material upon which to deposit her 
eggs. This may be any decaying vegetable matter, though usually 
horse stable manure. About one hundred eggs are deposited at each 
laying, of which there are several at intervals of three to five days. In 
eight to twentj^-four hours a white, footless larva is hatched. After 
five daJ^s to one week of feeding and and growing, during which period 
it undergoes two molts, the larva enters the pupal stage, the larval skin 
serving as its puparium. Before entei'ing this stage the maggot may 
crawl away from its breeding place and burrow for a short distance 
into the adjacent ground, or find lodgment under a board, stone, or 
dried crust of manure. The stage of pupation lasts from five days to 
one week, and at its termination the adult fly emerges. 

According to the longer periods given, the time required for develop- 
ment from the egg to the imago is fifteen days. This time, however, is 
greatly influenced by temperature, under the most favorable conditions 
of which the period for complete metamorphosis may be reduced to ten 
days; a fact always to be reckoned with in dealing with control of the fly 
through the regiilar and systematic removal of stable manure or other 
material which may serve as its breeding bed. 

In the warm midsummer season adult flies may live for six to eight 
weeks, though it is probable that the average period will not exceed 
thirty days. The}' may survive the winter in a state of hibernation, 
seeking their retreats in the late fall months, and coming forth with the 
warm da^'s of early spring to crawl upon the windows as they seek the 
warm sunlight or exit from houses. 



38 PARASITES OF THE DOMESTIC ANIMALS 

Habits and Relation to Disease.— While, so far as known, the 
house fly is not an essential host to pathogenic organisms of man and 
the mammalian domesticated animals, it is, by its structure and filthy 
habits of feeding, one of the most dangerous of disease-transmitting 
insects. Omniverous in habit, it will feed upon decaying vegetable and 
putrid animal matter, excrement, vomit, sputum, or other revoltingly 
filthy material. Direct from such sources of infection it may pass to 
the food upon our tables to which it is equally attracted, leaving a 
trail of contamination wherever it may drag its filthy parts. 

From the viewpoint of the bacteriologist it would seem superfluous to 
discuss the house fly as a carrier of disease-producing bacteria. The 
form of its proboscis, habit of regurgitating its food, its six bristly feet 
(Fig. 8), each terminated by a sponge-like structure secreting a stick}'- 
substance, together with the vile material which it visits, make it both 
by structure and habit an ideal transmitter of such infectious diseases as 
typhoid fever, dysentery, cholera, glanders, anthrax, and ophthalmia. 
Furthermore, positive evidence of the degree to which this insect is a 
carrier of bacteria has been well set forth by laborator}^ experiment. 

Control. — As a widely disseminated menace to public health the 
house fly presents a problem that can only be successfully dealt with by 
community action. The measures taken should look to control rather 
than elimination, the latter, however desirable, being scarcely possible 
under present conditions. While it prefers horse manure, it is known 
that almost any fermenting material will serve as a breeding place, and 
it therefore follows that, in order to successfully combat this pest through 
its sources of propagation, all such material must be systematically re- 
moved, screened off, or so treated as to render it unsuitable for the 
development of the larvae. Manure should be removed at least once a 
week, and if possible at once spread upon the fields. Kitchen garbage 
should be likewise removed, and in the meantime kept in tightly closed 
receptacles. Access of flies to the vaults of outhouses can be prevented 
by their proper structure and screening. 

Protection. — As to measures of protection to the household against 
flies, there is little to be said that is not of common knowledge. The 
first of these to be mentioned is the thorough screening of doors and 
windows. Kitchens being especially attractive to flies, they should be 
doubly protected by screening the back porch, the screen doors at these 
locations being well fitting and made to withstand their frequent use. 
Flies that have gained entrance are best gotten rid of by burning pyre- 
thrum powder. A good method for the treatment of a room is to sprinkle 
the powder upon a hot shovel after first closing the doors and windows; 
if the kitchen, the powder may be sprinkled over the stove. It is best 
applied at night, leaving the room tightly closed. In the morning the 
flies will be found lying about dead or stupefied, when they may be 



THE FLIES 39 

swept up and Ijurnod. The use of poisonous liquids set around in dishes 
has but httle efficacy and for other reasons is not to be reconunended. 
Sticky .fly paper, to be most effectual, should be placed in parts of the 
room where there is most sunlight, as in the vicinity of windows. 

In this connection it should be borne in mind that adult house flies 
and their allies seek the light, while their larvse avoid it, characteristics 
referred to in the first case as light positive and in the second as light 
negative. This habit as to light is to be reckoned with and taken ad- 
vantage of in measures looking to fly control. 

Stomoxys Calcitrans 

Strotnoxys stabulans. Sta])le fly; stinging fly. Muscidse (p. 37). 
About the size of the house fly. The ciplor is brownish gray; proboscis 
black, slender, bent near its base, and extending forward from the head, 
fitted for piercing. The thorax bears four longi- 
tudinal stripes which may be more or less broken. 
The abdomen is stout, grayish, and spotted dor- 
sally. The wings hyaline, and when at rest widely 
spread apart at the tips. The fly rests with its 
head well elevated and- with wings sloping later- 
ally downward and outward (Fig. 22). 

The eggs are about one nun. in length, cur^'ed 

., , -i. • 1 r • 1 J. , Pig. 22. — btomoxys cal- 

on one side, on the opposite side straight and eitrans, enlarged. 
grooved. The larva resemble those of the house 

fly. They ma>' be differentiated by the posterior stigmal plates, 
which in the larviP of the house fly are large, irregularly oval, and close 
together, while in Stomoxys they are smaller, round or triangular, and 
much farther apart. 

Life History. — The life-cycle of the stable fly is considerably longer 
than that of the house fly; like the latter it breeds in horse manure, but 
not to the same extent. Manure well mixed with straw is that most 
sought. Ideal for the deposition of its eggs are damp and fermenting 
collections of such material as cut grass, alfalfa, hay, grain, or piles of 
weeds. The eggs are deposited deep into the fermenting mass, and, 
under favorable conditions of temperature, will incubate in about three 
days. The larvae are active feeders and complete their growth in from 
twelve to thirty days. As in related flies, the puioarium is formed by 
the hardenhig of the last larval skin. The duration of the pupal stage 
will again vaiy according to weather, lasting from six to twenty days, or, 
if cool, it may be much longer. About twelve days may be taken as an 
average period. The time required for complete development may 
accordingly be set down as from twenty-five to thirty days under 
ordinarih' favorable conditions. It is proi)able that the species is car- 
ried over the whiter months in our Northern States in the larval and 




40 PARASITES OF THE DOMESTIC ANIMALS 

pupal stages. Development with the appearance of adult flies will 
occur in warm stables during this season. 

Occurrence and Effect. — The stable fly is of world-wide distribution, 
and is connnonly mistaken for the house fly, the term "biting house 
fly" being often applied to it from its habit of entermg our houses durmg 
damp, rainj^ Vv^eather and in the cooler days of early autumn. It may 
quickly be distinguished from the common house fly, however, bj^ its 
elevated head when at rest, its protruding, baj'onet-like proboscis, and 
its wings, which are widely spread apart at the tips. 

Though commonly called the stable fly, Stomoxys is found in far less 
numbers about stables than is the house fly, and, as it will not visit such 
filth as does the latter, it is not such an offender agamst the cleanliness 
of dairy and other food products. Both sexes of Stomox^'s, however, 
are vicious blood-suckers, and their bite is especially a source of torture 
to thin-skhmed, sensitive animals. Typically an out-of-door fly, it is 
most likely to enter stables in the cooler days of late summer or early 
autumn when it will attack horses and cattle, attaching itself by prefer- 
ence upon the legs. Their sharp sting is manifested by the stamping, 
kicking, and general restlessness of the victims. The punctures are 
often followed by the formation of papules which may coalesce and 
rupture, leaving a scaly, more or less thickened skin with hairs scant, 
lusterless, and erect. To the dairy they are a source of loss in milk 
production through the worry and unrest caused by their attacks. 

Relation to Disease. — The possibilities of the stomoxys fly as a 
disseminator of infectious diseases have in recent years received con- 
siderable attention. Its habit of visiting a number of hosts before 
becoming engorged with blood, together with its deep puncture, war- 
rants us in charging agamst this species possibilities in the transmission 
of anthrax in cattle and glanders in horses. By some authors it is re- 
garded as a carrier of the trypanosome {Trypanosoma evansi) which 
produces surra of horses. Of this, however, there is no conclusive experi- 
mental evidence. As to the responsibility of the stable fly for the spread 
of infantile paralysis, it will be suflficient here to quote Riley and Johann- 
sen, who, after reviewing the evidence, thus state their conclusions 
(1915): "The evidence at hand to date indicates that acute anterior 
pohomyelitis, or infantile paralysis, is transmitted by contact with 
infected persons. Under certain conditions insects may be agents in 
spreading the disease, but their role is a subordinate one." 

Control. — Control measures consist in removing materials which 
afford favorable breeding places for the fly. Collections of moist and 
fermenting feed material, such as have been mentioned, should be re- 
moved and scattered in a layer suflficiently thin to insure thorough 
drying. It will then be unsuitable for the development of stomoxys 
larvae, as they require considerable moisture. Manure in which there is 



THE FLIES 41 

mixed considerable straw affords a favorable niediuni for the propaga- 
tion of this fl}^ — a further reason for its systematic removal to be at once 
spread upon the fields, as stated in control measures for the house fly. 
It should be borne in mind, however, that stables are not predominant as 
breeding places of the fly under consideration, as is the case with the 
house fly. Stomoxys is attracted to stables because the animals from 
which it obtains its meal of blood are contained there. The favorite 
material for the deposition of its eggs is likely to be found elsewhere. 
These flies like the open, and chstricts far from stables may be overridden 
with them. 

Protection. — Little can be done in the way of direct protection of 
live stock against the attacks of stable flies beyond thorough screening, 
the effectiveness of which is much lessened by the frequent opening of 
doors customary about stables. Means of keeping them out should be 
especially looked to in cloudy, damp weather, and in the cool mornings 
of early autumn, at which times they are most likely to seek the interior 
of stables and houses. 

Lyperosta Irritaxs 

Hcematohia serrata.— The horn fly (Fig. 23). Muscids (p. 37). About 
half as large as the house fly and like it in shape and color. The mouth 
parts are adapted for piercmg and sucking blood, but differ from those 
of the stable fly in that the palpi are almost as long as the proboscis and 
are slightl}' spatulate. 

The eggs (Fig. 23, a) are about L25 mm. in length, irregularly oval, and 
reddish brown in color. They are deposited in the fresh dung of cattle, 
and, under favorable conditions of temperature, will hatch in about 
twenty-four hours. 

Life History. — Newly hatched larvae are about 2.5 mm. in length, 
and pure white. When full grown they are about 7 mm. in length and 
somewhat darker in color. The larvae burrow into the dung and reach 
their full growth in about four days (Fig. 23, b). When ready to trans- 
form into the pupal stage the larvse descend into the dryer parts of the 
dung, or for a short distance into the ground beneath it. The puparium 
(Fig. 23, c) is about 4.5 mm. in length, irregularly ellipsoidal, and dark 
brown in color. The pupal stage occupies from five to ten days, therefore 
the time for full development from the deposition of the eggs will be, 
according to the above, from ten to fifteen days. 

Occurrence and Habits. — The horn fly is an importation from 
Europe, making its first appearance in the vicinity of Philadelphia about 
the year 1886. It was first noticed as a pest to cattle in this country in 
1887, from which tune it has spread rapidly and at present is found in 
practically all parts of the United States and the greater part of Canada. 

The popular name ''horn fly" is derived from the habit peculiar to 



42 



PARASITES OF THE DOMESTIC ANIMALS 



this species of clustering about the base of the horn, though this only 
occurs when they are quite abundant. Their purpose in collecting here 
seems to be for rest in a location where they are not liable to be dis- 
turbed. There is a somewhat prevalent belief that the flies damage the 
horn by eating into it, depositing eggs, and developing maggots which 
may penetrate to deeper structures, etc. This is a popular error for 
which there is no foundation, for, beyond "fly specking," it has not been 
observed that the flies do any injury to the horn. 

Field study will show that this insect assumes two characteristic posi- 
tions. In the resting position, as they are found when upon the horns. 




Fig. 23. — Lyperosia irritans: a, egg; b, larva; c, puparium; d, adult in biting 
position — all enlarged (after Osborn, from Riley and Howard, Bui. No. 5, Bu- 
reau of Entomology, Dept. of Agr.). 

the wings are held nearly flat down the back, overlapping at their bases 
and moderately diverging at their tips. The proboscis is extended for- 
ward, and the legs are not widely spread. When active and feeding, on 
the other hand, the wdngs are slightly elevated and held almost at right 
angles to the body, while the legs are spread. The proboscis is nearly 
perpendicular in position, and penetrates the skin of the animal at- 
tacked. To secure this position it works its way to the skin, and is 
usually observed more or less covered by the hairs. In damp, rainy 
weather they may be noticed as particularly abundant beneath the 
hairs of the ventral surface of the body. 

Effect. — Horn flies appear early in May and become most abundant 
in July and August. With the coming of cold weather they disappear, 



THE FLIES 43 

their full period depending uiDon season and latitude. During the time 
of their activity they are a veritable pest to cattle, causing interference 
with their grazing and disturbance of their rest, with consequent un- 
thrift and serious loss in productiveness. Horses do not escape their 
annoyance, but cattle seem to be the special object of their attack. 
Though the damage done is chiefly through their torment, the con- 
siderable amount of blood extracted from the animal by the large 
swarms which feed upon it must seriously contribute to the weakening 
effects. Further, as in all blood-sucking Diptera visiting cattle, we are 
justified in inferring that this fly may be a transmitter of infectious blood 
diseases, such as anthrax, though as to this there has as yet been little 
if any investigation. 

Control. — In control measures two lines of procedure should be fol- 
lowed, one looking to prevention of multiplication, the other directly 
protecting cattle from attack. Of these the former is most effective and 
involves, such treatment of breeding places as will prevent larval develop- 
ment. As eggs are deposited in fresh dung, which must remain moist for 
the proper nourishment of the hatched larvae, any treatment of the 
droppings which will cause them to rapidly dry out will prevent or 
greatly inhibit larval development. Scattering or thinly spreading this 
manure, as may be done by a rake or by drawing })rush across the fields, 
will accomplish this; the latter method, more economical in time and 
labor, is best adapted for large pasture areas. Hogs running with cattle 
will serve to scatter the manure to a large extent. The use of lime, which 
may be applied by simply throwing it over the droppings in the pasture, 
is very effective in destroying the larvae. While piles of cow manure, 
especially those containing considerable straw, afford good breeding 
places for the stable fly, the horn fly will not seek this material to any 
great extent for the deposition of its eggs. 

Protection. — For the direct protection of cattle a number of oleagin- 
nous repellents are recommended. A mixture of fish oil and tar, equal 
parts, applied to the regions most attacked, is one in general use. Almost 
any oily or greasy substance is of value, though causing the animal to 
become somewhat unsightly from adhermg collections of dust and dirt. 
Sprays of kerosene emulsion (page 48) may be used with advantage, 
though the effectiveness of such treatment is very transient. The 
following mixture is recommended by the Kansas Experiment Station: 
resin (pulverized), one part; shaved soap, one part; water, one-half part; 
fish oil, one part; oil of tar, one part; kerosene, one part; water, three 
parts. The resin, soap, fish oil, and one-half part water are boiled to- 
gether until the resin is dissolved, then the three parts water are added, 
and finally the kerosene and oil of tar. The mixture should be thor- 
oughly stirred and lioiled for fifteen minutes. This preparation when 
cool and applied as a spray will act as an effective repellent for twenty- 



44 



PARASITES OF THE DOMESTIC ANIIVIALS 



four to forty-eight hours. It is necessar}-, therefore, to regularly repeat 
the application if the animals are to be continuously protected. Re- 
pelling agents are best applied in the evenmg when cattle are stabled or 
yarded. 

Tsetse Flies 

Genus Glossina.— Muscidge (p. 37). The tsetse flies (Fig. 24) are 
about the size of house flies, or may be somewhat larger. The general 
color is light brown. When at rest the proboscis projects in front of the 
head. At the base of the proboscis is a bulbous enlargement, arista 




Fig. 24.— Tsetse fly. 

plumose above. The resting wings are folded scissors-like over the back. 

These flies are found only in certain areas in Africa. 

Glossina Palpalis.— Glossina (p. 44). This species is 8 to 9 mm. 
(5/16 to 3/8 of an inch) in length. The color is brown dusted with gray. 
The antennae are black. All segments in the hind tarsi are black. The 
fourth and fifth segments of the fore tarsi are black. The halteres are 
white. 

Glossina Morsitans.— Glossina (p. 44). About the same size and 
color as G. palpalis. The antennae are dark. The first three segments 
of the hind tarsi are yellow, the fourth and fifth segments black. The 
fourth and fifth segments of the first and second pairs of tarsi are black. 
^ Glossina longipalpis is a species which in characteristics and distribu- 
tion is almost identical with G. morsitans. 

Breeding Habits and Habitat.— The Glossina deposit hatched larva 
among roots of tropical vegetation. When deposited the larvae are well 



THE FLIES 45 

advanced and within a few hours enter upon the pupal stage which re- 
quires from six to eight weeks. Occurring only in Africa, they are most 
abundant in heavily wooded districts penetrated by water courses. 
Both sexes are blood-sucking, and it is in such locations that they are 
most likely to find the wild animals upon which they feed. 

Relationship to Trypanosomiasis. — As transmitters of trypanoso- 
miasis to man and domestic aniinals, tsetse flies maj' be regarded as the 
world's most dangerous insects. The first observation of trj'panosomes 
in the blood of mammals was made b}^ Lewis, who in 1877 described a 
trypanosome {Trypanosoma lewisi) of the blood of a rat. Three years 
later another trj^panosome (7". evansi) was studied as the cause of surra 
in horses. When Bruce in 1894 demonstrated the relationship between 
tsetse fly disease of horses in Africa, the cause of which was unknown, 
and nagana, trypanosomes received much more attention as to their 
pathogenic importance. The further investigations of Bruce as to the 
part played by the tsetse fly in the transmission of this disease are best 
given in his own account, from which the following is an excerpt: 

"When it was once established that the two diseases were the same, 
experiments were made to And out how the animals became infected, 
whether the fly was the carrier or the mere concomitant of the low-lying, 
mihealthy district, and, if a carrier, if it was the only carrier of the disease 
from sick to healthy animals. Horses taken down into the fly country, 
and not allowed to feed or drink there, took the disease. Bundles of 
grass and supplies of water, brought from the most deadly parts of the 
fly country to the top of Ubombo and there used for fodder for healthy 
horses failed to convey the disease. Tsetse flies caught in the low country 
and kept in cages on top of the mountain, when fed on affected animals, 
were capable of giving rise to the disease in healthy animals up to forty- 
eight hours after feeding. Tsetse flies brought up from the low country 
and placed straight way upon healthy animals were also found to give 
rise to the disease. The flies were never found to retam the power of 
infection for more than forty-eight hours after they had fed upon a sick 
animal, so that if wild tsetse flies were brought up from the low country, 
kept without food for three days, and then fed on a healthy dog, they 
never gave rise to the disease. In this way it was proved that the tsetse 
fly, and it alone, was the carrier of nagana. Then the question arose as 
to where the tsetse flies obtained the trypanosomes. The flies lived 
among the wild animals, such as buffaloes, koodoos, and other species of 
antelopes, and naturally fed on them. It seemed that, in all probabilitj^, 
the reservoir of the disease was to be found in the wild animals. There- 
fore, all the different species of wild animals obtainable were examined 
both by the injection of their blood into healthy susceptible animals, 
and also by direct microscopic examination of the blood itself. In this 
way it was discovered that manv of the wild animals harbored this 



46 PARASITES OF THE DOMESTIC ANIMALS 

trypanosome in their blood. The parasites were never numerous, so 
that it was only after a long search that they could be discovered by the 
microscope alone. The wild animals did not seem to be affected by the 
trypanosomes in any way; they showed no signs or sjanptoms of the 
disease, and it, therefore, appeared probable that the tiypanosomes lived 
in their blood as harmless guests, just as the trypanosome of the rat lives 
in the blood of that animal." 

As Trypanosomu brucei is now known to be the organism causing the 
fatal nagana of horses and mules of Africa, so T. gamhiense is known to 
be the cause of sleeping sickness of man. The relationship of the tsetse 
fly to human trypanosomiasis was shown in a way very similar to that 
by which Bruce reached his conclusions. While the tsetse species 
Glossina morsitans and G. longipalpis are especially concerned in the 
transmission of nagana, and G. palpalis likewise related to sleeping sick- 
ness, it has been shown by students in the field of protozoology that not 
only biting flies, but mosquitoes, lice, and leeches may carry trypano- 
somes from one vertebrate host to another. 

Experiment has shown that the trypanosomes adhering to the pro- 
boscis of the biting fly after it has fed upon the blood of an infected 
animal rapidly lose their vitality, becoming sufficiently attenuated 
within fortj'-eight hours to be noninfective. The fl}', therefore, can 
only inoculate mechanicalh^ that is by the puncture of its soiled pro- 
boscis," within a few hours after it has become a carrier of the infecting 
organism. It is now known, however, that trypanosomes taken into 
the stomach of the fly with its meal of blood pass through a metamor- 
phosis involving sexual forms, and that at the end of about twentj'-eight 
days the fly may again become infective. At this time the parasites 
have reached the salivary glands and here they remain during the re- 
mainder of the life of the fly. How long such a fly may retain its power 
to infect is yet a question, though it has been found by the Sleeping 
Sickness Commission to be at least three months. The duration of the 
life of the tsetse fly has only been observed upon specimens in captivit}^, 
but it is probable that it is about four to six months. 

Control. — Measures looking to the control of the breeding of the 
flies are limited practically to exclusion owing to the fact that the larval 
period is passed within the body of the female, hence offers no opportu- 
nity for attack through sources of larval food supply. The fact that 
tsetse flies seek the vicinity of water courses surrounded by wooded 
areas may be taken advantage of in excluding them from locations of 
settlement. With a view to this it has been recommended that clearings 
be made over an area of six hundred to eight hundred yards at some 
distance from streams of water, the water supph' l^eing obtained from 
wells. The difficulties presented, however, in the control of the fly are 
numerous and in many features seem unsurmountable. The ultimate 



THE FLIES 



47 



solution of the problem probably lies in innnunization against the 
tsetse fly diseases, as to which little progress has yet been made. 

Family V. Hippoboscid^ 

Diptera (p. 23). — The body is flattened. Wings are present or absent. 
The wing veins are crowded toward the anterior margin. The head is 
sunk into an emargination of the thorax; the antennae inserted in pits 
near mouth; mouth j:)arts adapted for piercing and sucking blood. 
The legs are stout, terminated by .strong claws. The abdomen is large 
and sacular with segments indistinct. 

The Hippoboscidse are pupipai'ous, the eggs being hatched and 
nearly the whole of the larval stage passed within the body of the parent. 
The larvae are extruded only when nearly ready to transform into pupae. 

All are parasitic upon birds and mannnals. Hippohosca equina is a 
winged species occurring upon the horse, and known in England as the 
forest fly. 

^NIelophagus Ovixus 

The sheep "tick." — Hippoboscidae (p. 47). Three-si.xteenths to one- 
quarter of an inch in length. The color reddish or grayish brown. 
The wings and halteres are ab- 
sent. The head is small and 
sunken into the thorax; ab- 
domen large, sac-like, and 
covered with short spines 
(Fig. 25). 

Life History. — INLatured lar- 
vs are extruded from the body 
of the female and at once enter 
upon their pupation, the red- 
dish brown pupae adhering to 
the wool fibers. The pupal 
stage occupies three to six 
weeks according to season and 
temperature, the shorter jieriod 
occurring during the sunnner. 
At sexual maturity the deposi- 
tion of pupae begins, each fe- 
male depositing from eight to 
ten. Probably the life of the 
tick will not exceed four to five 
months. 

Occurrence. — The sheep tick is distributed over all parts of the 
workl where sheep are kept. Its parasitism is continuous, the pupiparous 




Fig. 25. — Melophagus ovinus (from photo- 
graph of mounted specimen, by Hoedt). 



48 PARASITES OF THE DOMESTIC ANII^L\LS 

habit of bringing forth its 3'oung adapting it to spend its whole hfe upon 
the host from which it never migrates miless to attach to another animal 
of the same species. It is probable that this migration occurs principally 
at the time of shearing when the ticks leave the sheared sheep and crawl 
upon the lambs. Off the host the ticks will not survive longer than a 
few days, probably all will be dead within a week. 

Effect. — All breeds of sheep are ahke subject to attack, the presence 
of the "tick," or "louse," as it is commonly called, and the injmy which 
it causes, being a matter of common knowledge to sheep breeders. Sheep 
are not materially affected by a few, but if in larger numbers, their 
presence will be manifested by rubbing, scratching, and biting at the 
fleece. Loss of flesh and general unthriftiness will occur in badly in- 
fested animals. Where the ticks are prevalent lambs may be attacked 
by large numl^ers at shearing time, in which condition many will die 
unless promptly relieved. 

Treatment. — In the winter months, when the long wool will not 
permit of other treatment, the ticks may be greatly reduced in number 
by the use of pyrethrum powder which should be freel}^ blown deep into 
and upon the fleece over all parts of the body. The most effectual treat- 
ment is best applied after shearing and consists of the application by 
dipping or as a wash of such remedies as creolin, zenolium, lysol, or 
cresol, used in two to three per cent, strength. Decoction of tobacco, 
in strength of three to four per cent, is also used, but, to avoid danger of 
nicotine poisoning, should not be applied to all parts of the bodj^ at once. 
Kerosene emulsion, which has a wide range of usefuhiess in the treat- 
ment of external parasites, is another of the numerous dips resorted to 
in this connection. The emulsion may be made either with milk or soap 
according to the following formulae : 

Milk emulsion. — To one part milk add two parts kerosene and churn 
by a force pump or by other means of agitation. Dilute the resulting 
emulsion with eight to ten times its bulk of water. 

Soap emulsion. — Dissolve one-half a pound of hard soap in one gallon 
of hot water and, while still at near boiling point, add two gallons of 
kerosene. Emulsify b}^ use of force pump or other means of agitation. 
Dilute one part emulsion with eight or ten parts water. 

These emulsions maj^ be used in the proportions given as a spray, 
wash, or dip. 

None of these dips will kill the pupae, and, therefore, keepmg in 
mind the life histor}' of the parasite, the treatment should be re- 
peated in about twenty-four daj^s. If the dipping has been done in 
the cooler weather of autumn, this interval should be accordingly 
prolonged. 

As the movement of the ticks from the sheep to the lambs takes place 
principally at the time of shearing when the insects are removed from 



THE FLIES 49 

their host with the fleece, it is well at this time to keep the lambs at 
some distance from the stored wool. This precaution should be ob- 
served for at least a week from the time of shearino-, at the termination 
of which period the ticks which have l)een removed with the wool will 
be dead. 



CHAPTER VI 

DIPTEROUS LARV^ 

Flesh flies, blowflies, botflies. — The larvae of these flies produce a 
form of parasitism to which the term myasis (also myiasis, and myiosis) 
is appHed. Various forms of myasis are recognized according to the 
location of the larvae, as cutaneous, muscular, nasal, gastric, and intes- 
tinal. With certain species, as those of the family CEstridse, or true 
botflies, the larval parasitism is obligate upon or within a living host 
anhnal, while the larvae of the flesh and blowflies of the family Muscidae 
may attack either living or dead, usually decomposing, tissue. 

Chrysomyia Macellaria 

Compsomyia macellaria; Cochliomyia macellaria, Screw worm fly. — 
Muscidae (p. 37). Three-eighths to half an inch in length; color bluish 
green with metallic reflections. There are three longitudinal black 
stripes upon the thorax. The head is reddish or yellowish brown; 
thorax and abdomen covered with stiff black hairs (Fig. 26) . 

The eggs are about 1 mm. in length, white and cylindrical. They 
are deposited in masses of three hundred to four hundred upon dead 
and decaying flesh and upon wounds, sores, or within the nostrils or 
other natural mucous openings of man and lower animals. Hatching 
may occur in from one to twelve hours from the time the eggs are 
deposited. 

The larvae are white, apodal, slender, and quite active. The head 
and segments are provided with spines which facihtate their burrowing 
into the living or putrefying flesh upon which they feed, a habit which 
gives to the mature insect its common name of screw worm fly. Under 
most favorable conditions the full larval growth is reached in three days, 
at which time they may be half an inch or more in length. When mature 
they leave the flesh upon which they have been feeding and bury them- 
selves in the earth near by, in which location they enter upon pupation. 

The pupae are 6 to 9 mm. in length, somewhat barrel-shaped, and 
dark brown in color. The pupal stage may last from six to twelve days. 

Occurrence and Effect. — The screw worm fly is widely distributed, 
being found throughout North and South America. In the United 
States it is especially abundant in the South, where it is responsible for 
the most serious cases of human myasis occurring in this country. It 
begins to attack in June, but has its greatest period of activity in the 



DIPTEROUS LARVAE 



51 



three months which follow. In its attacks upon man it usually deposits 
its eggs in the nostrils or mouth while the individual is sleeping. It is 
especially attracted if the parts are unclean, as from the discharge of 
nasal catarrh or collections of vomit about the lips. Persons in a drunken 
stupor are especially liable to attack. For the same reason open sores 
contaminated by collections of pus or blood are equally attractive to it. 

The fl3''s greatest injury as a pest to domestic animals in the United 
States occurs in the Southwest, where cattle are the greatest sufferers 
from its ravages. In these animals the flies are attracted to wounds of 
operations, such as dehorning, branding, castrating, etc., and to injuries 
such as may result from hooking or 
barbed wire. In fact any open 
wound or exposed mucous mem- 
brane, especially if soiled with an 
odorous discharge, is a favorite seat 
of attack. 

Upon hatching, the larvae at once 
proceed to attack the tissues and 
maA' rapidly produce a serious de- 
struction and mutilation. Thej^ grow 
rapidly as they consume the tissues 
adjacent to them, and in locations, 
as parts of the limbs where there is 
little fleshy covering, the bones may 
be laid bare. 

Protection.-As most of the fatal ^^^ 26.-Compsomyia macellaria-en- 
cases of myaslS m man from this larged (after Osborn, from Francis, Bui. 
cause are due to deposition of eggs ^o. 5, Bureau of Entomology, U. S. Dept. 

in the nostrils while the person is ° " ^^ 

sleeping, the first measure of precaution is to protect from attack by the 
use of netting. Those sleeping out of doors in infested regions are most 
exposed, but sleeping rooms should also be thoroughh' screened. Open 
jiores and wovmds should of course be kept free from collecting discharge 
and covered with clean, drj' dressing. The same precautions as to 
(ileanliness of wounds and exposed mucous membranes applies to domes- 
tic animals. The vulvae of cows recently fresh, especially if there has 
been a retention of the placenta, and the navels of calves offer favorite 
points for attack and should particularly be guarded. 

Treatment. — Where sores and exposed mucous membranes have 
already become infested with worms a disinfecting wash, such as a one 
to three per cent, solution of carbolic acid, should be used. For injection 
into regions where the maggots have penetrated, the injection of carbolic 
acid or creolin in about five per cent, strength will destroy worms with 
which it comes in contact. Chloroform diluted to a strength of about 




d 




52 PARASITES OF THE DOMESTIC ANIMALS 

twenty per cent, is also recommended for this purpose. An ordinary 
machinist's oiler affords a practical method of applying such agents. It 
has the advantage of deep application without waste of the material. 
For deeply infested wounds a final packing of oakum and oil of tar should 
be applied, and this should be covered by a protective dressing of tar 
and oakum as a prevention from further attack. 

Sarcophaga SaRRACENIvE 

A flesh fly.— Muscidse (p. 37). In markings somewhat similar to the 
house fly, but considerably larger. The general color is light gray; eyes 
reddish brown. Body spiny. 

The female deposits larvae upon fresh meat, or in the wounds of living 
animals. Under favorable conditions the larval stage is completed in 

about six days. The 
mature larvae crawl to 
a convenient shelter 
where they undergo a 
.- A, . . • wi fl 1 fl /c I > pupation from which 

Fig. 2/. — Metamorphosis of the flesh fly (Sarcophaga) : , , , • • r- 

a, eggs;b , young larva just hatched; c, d, full-grown larvae; the adults ISSUC Ul trom 

e, pupa; f, imago (after Ortoii, by Dodge; Copyright, 1894, twelvC to fourteen 

by Harper & Brothers) . ^j^,^,^ (p.g_ 27) . 

Protection. — The flesh flies are of world-wide distribution, and are 
of most importance as they affect fresh meats in the household or meats 
in storage. As a protection in such cases the flies should be screened off 
at some distance, as larvae which have been deposited in the vicinity of 
meat will crawl to it, though it may not be accessible to the flies. 

To prevent their attack upon wounds, the same general procedure 
may be adopted as recommended for the preceding species. 

Calliphora Vomitoria 

Blowfly. — Muscidse (p. 37). Somewhat larger than house fly; eyes 
brownish in color; abdomen bluish green with metalic luster and usually 
pollinose. 

The eggs are oval, white in color, and are deposited upon decomposing 
animal and vegetable matter and in wounds of animals. Hatching may 
occur in from a few hours to one or two days, the shorter periods occurring 
in hot weather. After from three to nine days of feeding, the matured 
larvae seek the ground, become buried for a short distance, and in this 
location enter upon their stage of pupation. The time required for the 
entire life cycle, including a prepupal period of several clays, may be 
from two to five weeks, depending greatly upon temperature. Under 
ordinary conditions it would piobably occupy al^out three weeks. 

The blowfly agrees with the flesh fly in its habits, with the exception 



DIPTEROUS LARVyE 53 

that it deposits eggs instead of living larvae. After hatching the manner 
of attack and the effect upon infested meat and wounds is much the 
same and calls for the same treatment. 

Family VI. CEstrid^ 

Diptera (p. 23). Botflies, warble flies. The head is large, bearing two 
faceted eyes widely separated, antennae short and sunken into pits in 
the front of the head. The mouth parts are rudimentary, most all of the 
flies living in the adult stage without food. The body is heavy and 
somewhat hairy. The coloration is usually inconspicuous. 

The larvai are thick and twelve-segmented, the first two segments 
not alwaj^s distinctly separated. There is no demarcation into body 
regions, only a cephalic and anal end can be distinguished. The body- 
segments are frequently provided with rows of spines. Buccal hooks 
may or may not be present. Tracheal openings are at the posterior 
extremity. 

The larvae are parasitic in the stomach and intestines, mucous mem- 
branes, subcutaneous connective tissue, nasal passages, and sinuses of 
facial bones of mammals ; other parts are also invaded by their migrations. 
When completely developed the larva leave these locations in the host 
and pass to the ground where they enter the pupal stage. 

The flies of the family QCstridae are of world-wide distribution. 

Gastrophilus intestinalis {G. equi). Qilstridae (p. 53). The horse 
botfly (Fig. 28, h). The body of the female is one-half to five-eighths of 
an inch in length and is very hairy. The head, thorax and abdomen are 
brown. The wings are transparent with dark spots, those near the center 
passing entirely across the wing transversely. The abdomen is rather 
long and tapers to a point. In the males, which are rarely seen, the 
abdomen is light brown or yellow, and it is not tapering. In other re- 
spects the males closely resemble the females. 

The larvae (Fig. 28, c, d and g) when full grown are about three- 
fourths of an inch in length. At the head extremity are two buccal 
hooks by which attachment is made to the gastric mucosa (Fig. 28, e). 
The body-segments are bordered by short spines (Fig. 28, d). 

Habits. — Like other members of the Q^stridae, the horse botfly at 
matuiity is extremely active, flying chiefly during the warmest and 
bi-ightest days of the summer, and generally frequenting pastures in 
the vicinity of woods. It is the habit of the female to hover near the 
horse with its long, pointed abdomen bent downwaid and forward. The 
fly then darts toward the horse, deposits its egg, retreats, and again 
hovers until ready to repeat the operation. The eggs (Fig. 28, a and b) 
are yellow in color, about one-sixteenth of an inch in length, and tapering 
toward the attached end, the free end being provided with an operculum 
which is set obliquely and gives to this end somewhat of an obliquely 



54 



PARASITES OF THE DOMESTIC ANIMALS 



cut off appearance. The}' are generally deposited upon the hairs of the 
anterior parts of the body, as upon the forelegs, breast, shoulders, and 
under side of the body, regions which are most readily reached by the 
lips of the horse. It is not uncommon, however, for eggs to be attached 
to the sides of the neck, lower jaw, cheeks, mane, and other parts, the 
larvae in such cases reaching the mouths of horses by their licking or 
nipping at each other. 

Life History. — The eggs are deposited rapidly with their free ends 
down, and adhere to the hairs by a viscid substance which quickly dries 




Fig. 28 — Gastrophilus intestinalis: a, egg — enlarged; b, egg — natural size; c, young larva; 
d, young larva — much enlarged, showing spiny armature; e, oral hooks; f, body spines; g, 
full-grown larva — twice natural size; h, adult female (after Osborn, Bui. No. 5, Bureau of 
Entomology, U. S. Dept. of Agr.). 

and gives them a firm attachment. At this time they contain larvae 
which have undergone a more or less advanced development. 

Observations upon the botflies during recent years have been some- 
what disturbing to conclusions formerly held and apparently necessitate 
a certain revision of the life histories which have generally been given for 
them. According to the observations of Roubaud (1917) upon Gas- 
trophilus intestinalis, the eggs of the fly do not open spontaneously, and 
the larvae may not escape from them for several weeks. The opening 
of the operculum and freeing of the larva probably occurs when the 
horse rubs an itching or irritated area with his nose or bites it with his 
teeth, the horse rarely hcldng itself. By experiments with bot larvae on 
guinea-pigs Roubaud demonstrated that when the hatched larva is 
brought in contact with the buccal mucosa it at once burrows into this 
membrane and lies parallel to its surface. In two or three days it dis- 
appears, but he notes that one was seen traveling along the side of the 



DIPTEROUS LARV.E 55 

tongue for nine daj's, during which time it grew to three times its first 
dimensions. Before leavmg the buccal mucosa the larvae probably 
undergo a molt and then proceed to the stomach. These observations 
indicate that the larvae of the botfly escape from the eggs when the horse 
bites at his skin or rubs it with his lips, and that the}' burrow into the 
buccal mucosa where they undergo a degree of development before 
passing to the stomach. 

Within the stomach cavity the larva fixes itself to the walls bj- its 
buccal hooks. Later the head becomes deepl}' mserted into an alveolus 
which is formed mider the influence of the irritation to the mucosa. In 
this position the larva feeds upon the tissue juices and the products of 
the irritation which it sets up, becoming fully grown in about ten months. 
The period of larval development usually terminates from May to 
August, more especially in June, due to the fact that the deposition of the 
eggs occurs most actively in the month of August. At this time the 
larva becomes detached from the gastric mucosa, passes to the intestines, 
and with the mtestinal contents leaves the body of its host. 

The change into the pupal stage is made either in the horse manure 
or after the larva has burrowed for a short distance into the ground. 
At the termination of pupation, which lasts from four to six weeks, the 
matured fly creeps out, and, after fertilization by the male, proceeds to 
deposit ova for another generation. 

Tabular Review of Life History of Gastrophilus Intestinalis 
L Adult Flv. — (August.) 

I 

2. Eggs . — Attached to hairs of horse (Aug. and Sept.); 

I approximately 2 weeks. 

3. Young Larvae. — Upon or within mucosa of horse's 

I mouth. 

4. Larvae (Bots). — Attached to wall of horse's stomach. 

I Stages 3 and 4 approximateh' 10 

I months. 

5. Pupae . — Free (June) ; approximately 6 weeks. 

6. Adult Fly.— (August.) 

Effect. — The degree of injury due to the presence of the larvae of 
this botfl}' will depend upon their number and location. .That the 
stomach may be invaded by a considerable number of bots without 
apparent disturbance to this organ is probably due to the fact that they 
most commonly attach to the esophageal portion, this region of the 
horse's stomach havhig a less important part in the function of digestion 



56 PARASITES OF THE DOMESTIC ANIMALS 

than that toward the pyloris. Where they occupy the glandular right 
half, especially if in large numbers, they interfere with the digestive 
secretion and its proper contact with the gastric contents. In excep- 
tional cases they may be sufficiently numerous about the pyloris to 
form an obstruction to the passage of food material into the small intes- 
tine; or even the duodenum itself may be invaded. Under these latter 
conditions the larvae bring about nutritive disturbances and may cause 
attacks of acute indigestion with its accompanying manifestations of 
pain. When we consider, however, the large number of horses essentially 
harboring the larvae of the horse botfly, as indicated by the widespread 
prevalence of the insect, we must conclude that they are comparatively 
inoffensive, for in most cases there is an entire absence of any apparent 
disturbance and, with the exception of the voiding of the bots, nothing 
during the life of the animal which would lead to suspicion of their 
presence. 

Treatment. — The larv« of Gastrophilus are so resistant that treat- 
ment having in view their destruction or expulsion has been generally 
unsatisfactory. Such agents as preparations of tar, benzine and turpen- 
tine, which are sometimes used for this purpose, add irritation to an 
already irritated gastric mucosa and, for this reason, in connection with 
their general ineffectiveness, the advisability of their use is questionable. 
AVhere the presence of the bots in sufficient numbers to cause disturbance 
to the health of the animal is suspected, gastric irritation may be allayed 
to some extent by feeding mucilaginous materials, such as flaxseed meal. 
Hay in such cases is best fed chopped, and a substantial nutritive diet 
should be looked to as compensatory to the loss of nutriment. 

A treatment recommended by Peroncito and Bosso (1894) consists 
in the administration of carbon bisulphide to adult horses in gelatin 
capsules, each containing 8 to 12 grams (2 to 3 drams). After fasting for 
twelve to twenty hours, the horse is given one capsule ; after one hour a 
second capsule is given, and after another hour a third. As carbon 
bisulphide is strongly irritant, care should be taken in the administration 
of the capsules that the cap does not become detached and that they do 
not become crushed in the mouth. 

In so far as clinical observation can determine the presence of bots, or 
lead to the conclusion that a remedy has caused the expulsion of any 
considerable number of them in proportion to the infestation, this treat- 
ment is said to be generally satisfactory. It seems reasonable to con- 
clude that an agent sufficiently active to cause the expulsion of these 
robust larvae from their secure attachment would have a severely irritant 
effect upon the gastric mucosa, though this membrane of the stomach 
appears to have a greater tolerance for such assaults than that of other 
regions of the alimentary tract. 



DIPTEROUS LARV.E 57 

Gastrophilus Hemorrhoidalis 

The red-tailed botfly.— CEstridse (p. 53). Somewhat smaller than 
6'. intestinalis. Dark brown color, yellowish hairs upon the face; trans- 
verse black band upon thorax. The abdomen is covered with fine hairs 
which in the middle are dai-k and posteriorly oranp;e-red. The wings are 
clear. 

This species of horse botfl}^ is found in common with (t. intestinalis in 
North America and Europe. 

The females attach their ova to the hairs of the horse, preferably 
those about the lips. The hatched larvae cause an irritation which 
impels the horse to pass its tongue about its lips, thus carrying the 
parasite into the mouth. In other respects its life history is essentially 
the same as that of G. intestinalis. The larvae differ from those of the 
latter in being somewhat smaller and in their dark-red color. There is 
also some difference in their habitat in that they attach usually to the 
pyloric portion of the stomach, and when fully developed pass on to the 
rectum where they remain for some time, assuming a green color before 
l)eing voided. 

Effect. — The presence of the larvae of this fly in considerable num- 
bers in the folds of the i-ectal mucous membrane may cause an anno\'ing 
irritation, inducing violent efforts at defecation. Such cases, however, 
are extremely rare, and, as a rule, little or no evidence is given by the 
animal of their presence. 

Gastrophilus nasalis. — (EstricUe (p. 53). This species, connnonly 
called the chin fly, is about 1 cm. ('Vs of an inch) in length. The body is 
hairy and yellowish red in color. The wings are without spots. 

Law describes the larvae as "furnished with a row of spines on each 
ring from the second to the ninth on the dorsal surface, and as far as the 
tenth on the ventral. There is an unarmed part in the center of the 
eighth and ninth rings on the dorsal surface." 

The fly deposits its eggs about the lips and nostrils. Th<> larvae attach 
to the mucosa of the upper part of the small intestine. 

Fitch states (1918), as to New York State, that from examination of 
the larvae it would seem that Gastrophilus nasalis is quite as frequent 
as G. intestinalis. 

Hypoderma Lixeata axd H. Bovis 

The ox botflies; warble flies (Fig. 29).— CEstridae (p. 53). Hypodernia 
lineata is about five-eights of an inch m length. The general color is 
black; body more or less covered with hairs. The front, sides, and back 
of the head, sides of thorax, and last segment of the abdomen are covered 
with long yellowish white hairs. 

This fly is found in all parts of the United States, but more especially 



58 



PARASITES OF THE DOMESTIC ANIIVLVLS 



ill the southern portion as far north as Illinois, Iowa, and Nebraska. 
It makes its appearance in the spring or earty summer and is at once 
attracted to cattle, depositmg its eggs on the hairs, frequently upon 
those about the heel, a habit which gives to the ^y its southwestern 
name "heel-fl}'." 

The entire length of the egg is 1 mm. and its width 0.2 mm. In color 
it is a yellowish white. The eggs are firmly attached to the hairs by 

means of a clasping projec- 
tion which connects with 
the egg proper by a short 
pedicle (Fig. 31). Usually 
they are deposited upon 
the hairs in groups of four 
to six. 

Hypoderma Bovis. — (Es- 
tridse (p. 53). This species 
is commonly referred to as 
the European warble fl.y, 
though it occurs also in 
Canada and the United 
States. It is, in fact, said 
to be more common in some 
pai-ts of this country than 
H. lineata. Its length, ex- 
clusive of the ovipositor, as 
stated by Neumann, is 13 
to 15 mm. {}/2 to % of an 
inch), which is 1 to 2 mm. 
longer than H. lineata. The 
general color is black, face 
gra}^; abdomen black; head, 
thorax, and abdomen hairy. 
The hairs from the base to the tip of the abdomen vary in color from 
white or 3^ellow to black; orange red at posterior third. The legs are 
black, yellow at their terminations; wings somewhat brown. 

As to the differentiation of the larvse of these two species, Herms 
writes as follows: "The life history of the two species is very similar. 
The larvse are different enough to distinguish them readily. The fully 
grown larva of H. bovis is longer, 27 to 28 mm., H. lineata about 25 mm. 
The two species are distinguished on the basis of their spiny armature. 
In H. lineata each segment of the larva is provided with spines except 
the last, the ring upon which the stigmata are located, while in H. bovis 
all except the last two are armored." 

Life History. — Dr. Cooper Curtice, from his researches in 1890, 




Fig. 29. — Hj^poderma lineata (after Osborn, from 
Insect Life, Bui. No. 5, Bureau of Entomology, U. S. 
Dept. of Agr.). 



DIPTEROUS LARV.E 



59 





k: 


/yp /^ 


^p\\^\\ 


^^^ 


yi \^ 


J 


\ 



concluded that the larv£e of Hypoderma lineata are taken into the mouths 

of cattle by licking the parts where the eggs are attached, the eggs under 

this influence hatching at once. 

From the mouth the larva, according 

to this investigator, is carried to the 

esophagus, the walls of which it 

penetrates. While lodged in the 

esophagus it molts, and the body be- 
comes ciuite smooth. For a period 

of several months thereafter it 

wanders through the connective 

tissue beneath the skin or between 

muscles, and ultimately reaches a 

point beneath the skin of the back. 

Here the larva again molts and the 

spiny processes reappear upon its 

body. It now cuts a small opening 

through the skin, and places its 

anal spiracle near this orifice in order to get air. In this location the 

larva lives upon the products of the inflammation which its presence 

sets up, such as bloody serous exudate and pus. It now develops rapidly 

and again. molts, at which time the grub is fat, yellowish-white in color, 
and an inch or more in length. Reaching the 
maturit}^ of its larval period (Fig. 32, g and i), 
which lasts about ten months, it works its wa}' 
out of the orifice at the summit of the tumor 
and drops to the ground, into which it may 
burrow for a short distance. Here it enters 
upon the pupal stage, the hardened larval skin 
becoming the protecting case for the pupa 
within. After about four to six weeks of 
pupation the adult fly escapes by pu.shing off 
the cap at the end of the pupal case. 

Dr. Sevmour Had wen, in notes on ''The 



Fig. 30. — Hypoderma Ijovis (after Os- 
born, from Brauer, Bui. No. 5, Bureau of 
Entomology, U. S. Dept. of Agr.). 




PfFiG 



T Life History of Hypoderma bovis and H. linea- 
turn'' based on observations made at Agassiz, 



-Eggs of Hypo- 
derma lineata, showing clasp- 
like processes — much enlarged 
(after Osborn, Bui. No. 5, 
Bureau of Entomology, U. S. 
Dept. of Agr.). 



British Columbia (Journal of the American 

Veterinary Medical Association, June, 1917) 

summarizes as follows: 

'^Hypoderma lineatum lays its eggs as early 

as April 15th, but the usual laying period 
is during the month of May. At Agassiz they have never been cap- 
tured later than May 30th. Hypoderma bovis (Fig. 30) begins in the 
early part of June and continues up to the beginning of August. 



60 PARASITES OF THE DOMESTIC ANIMALS 

Between the last appearances of H. lineatum and the first of H. hovis 
there is usually a period of ten days when the cattle are immune from 
attack of either species. H. hovis frightens cattle much more than 
H. lineatum. The eggs take about a week to hatch; the larvae bore 
through the skin in the coarser porous parts, taking several hours in the 
process; at this stage they are rather less than 1 nun. long. The lesions 
resulting from this penetration are caused partly l)y bacterial invasion 
and partly by anaphylactic reactions; those produced by H. lineatum 
being more severe. For the skin lesions I have proposed the name of 
hypodermal rash. At this point there is a hiatus in the life history as it 
is not positively known how the larvae reach the esophagus, where they 
are subsequently found, most likely in the loose connective tissues under 
the skin up to the region of the throat and into the esophagus where the 
muscles bifurcate. Passing down the esophagus they follow the sub- 
mucosa and are almost always found lying along the long axis of the 
canal. Whilst in the esophagus small edematous swellings are found 
surrounding the grubs, these are sterile and are anaphylactic in char- 
acter, the exudate contains large numbers of eosinophilic leucocytes but 
no pus cells. The earliest record made at Agassiz was on August 15th, 
when a larva 3.4 mm. was found and several slightly larger. According 
to Carpenter, continental observers have found them smaller than this. 
H. lineatum makes its appearance in the backs of cattle about Decem- 
ber 15th and H. bovis about a month later. The larvae at this time have 
grown to about 1.5 cm. and are of the same size in the neural canal and 
under the skin which they have just reached. At this age it is difficult 
to separate the larvae of the two species, but Mr. F. C. Bishopp has, I 
believe, discovered good distinguishing marks between the species. The 
life histories overlap at this period making it difficult to follow the 
migration, but in the latter part of the season (the middle of March) 
the last larvae to leave the gullet are at the paunch end. They pass out 
under the pleura and go to the neural canal either up the crura of the 
diaphragm or up the posterior border of the ribs, entering the canal by 
the posterior foramen, from there they descend the canal under the 
dura mater, emerge again through the foramen and reach the back, 
forming the characteristic swellings commonly called warbles. The 
larvae follow connective tissue exclusively and no larvae have been dis- 
covered in muscular tissue. The mature larvae leave the animals' backs 
from the early part of the year up to the first days of July. The periods 
for the two species have not been fully worked out, but judging from 
what records we have of the pupal period and the time of year the flies 
are about, H. lineatum begins to emerge in February and finishes about 
May 1st. H. bonis begins about May 1st and ends approximately on 
July 1st. The average pupal period for H. bovis is 32.5 days and for 
H. lineatum a little less. The duration of the life of the flies is short 



DIPTEROUS LARV.E 



61 




re . T. -^ 



62 PARASITES OF THE DOMESTIC ANIMALS 

seeing that they cannot feed. This hfe history apphes to Agassiz, 
British Cohunbia; doubtless in other countries variations will be noticed, 
but the period spent by the larvae within the host must be of the same 
duration, seeing that animals' temperatures are the same the world over." 

Effect. — Cattle seem to be much annoyed by the attacks of these 
flies in depositing their eggs, and in the endeavor to escape will often 
enter mire holes or injure themselves in other ways. Probably the most 
important damage from the insect is that to hides, these being dis- 
counted from twenty-five to fifty per cent, according to the number of 
punctures by the grubs. 

Treatment. — Treatment is best applied in the months of January 
and February when the grubs have become sufficiently developed that 
the small tumors in which they are lodged may be felt by running the 
hand along the back of the animal. The application at this time of a 
little kerosene or mercurial ointment to the summit of the swelling will 
destroy the grub. By March the tumors may be distinctly seen as 
prominent lumps upon the skin of the back. The orifice at the summit is 
now large enough to permit of the forcing out of the grub by careful 
pressure. Grubs thus removed should be at once destroyed to prevent 
the possibility of their finding favorable conditions for development 
into the adult fly. 

QllsTRUS Ovis 

The sheep botfly (Fig. 33, 1 and 2) .— CEstridce (p. 53). About one- 
half an inch in length ; yellowish-gray color ; slightly hairy. The abdomen 
is spotted with white and yellow; posterior portion covered with fine 
hairs. The wings are transparent. 

Occurrence and Life History. — This species is of world-wide dis- 
tribution, and is the most important insect pest with which sheepmen 
have to deal. The flies make their appearance with the coming of warm 
weather from early June to July, like other (Estridae, flying on bright 
and warm days and ceasing their activities about the month of October. 
The female, which is difficult to observe owing to its small size and rapid 
flight, deposits living larvae in the nostrils of the sheep. At this time 
the larva is creamy-white in color and about one-sixteenth of an inch 
in length (Fig. 33, 6). Later it becomes darker, and at maturitj^ reaches 
a length of about three-quarters of an inch (Fig. 33, 4 and 5). Upon the 
cephalic segment there are two hooklets the points of which are curved 
downward and backward. With the aid of these the larva at once pro- 
ceeds to work its way upward through the nasal passages until it reaches 
the frontal sinuses where it attaches by its hooklets to the lining mem- 
brane. Here it feeds upon mucus and serous exudate induced by the 
irritation of its presence. 

The larva remains in this location about ten months, at the end 




c. 


2 


" 1 


^ 


pill 


i 



DIPTEROUS LARV.E 63 

of which tmie, having reached its larval maturity, it detaches from the 
mucous membrane and passes to the nasal passages from which it is 
expelled by the violent sneezing which it excites in its host. Having 
reached the ground, it quickly buries itself, contracts withm its smooth 
dark shell, and enters upon its pupal stage (Fig. 33, 3). After from four 
to six weeks of pupation the mature insect emerges. 

Effect. — Both sheep and goats suffer from the attacks of this fly. 
Sheep are especially disturbed by it, and in their efforts to avoid its 
attack will toss the head, thrust the nose into the ground, or dash about 
in frenzy. The grubs cause much 
irritation to the sensitive mem- 
brane which lines the cavities of 
the head both by the booklets 
with which they make their at- 
tachment and by the spines cov- 
ering the ventral region. Further- 
more, if numerous, and the mucus 
secreted is not sufficient for their 
nourishment, the grubs will feed 
upon the membrane itself. The 
disturbance to the host will be 
manifest accordmg to the number 
of grubs present; if there are but 
few, there may be no more than 
a slight catarrhal discharge with 
occasional sneezuig. In heavy 
infestation there is a profuse 
muco-purulent nasal discharge with frequent sneezing and tossing of the 
head, the respiratory passages in some cases becoming so filled as to 
bring the animal to the verge of suffocation. The appetite is lost, and 
emaciation and weakness may progress until there is inability to rise, 
death in such cases soon following. 

Tabular Review of Life History of (Estrus Ovis 

1. Adult Fly. — (June to October.) 

I 

2. Hatched Embryos. — Deposited in nostrils of sheep. 

\ 

3. Larvse. — Attached to lining membrane of sinuses of 

I sheep's head. Stages 2 and 3 approximately 

I 103^ months. 

4. Pupse. — Free; approximately 6 weeks. 



Fig. 33. — CEstrus ovis: 1 and 2, adult fly; 
3, pupa; 4, full-grown larva, dorsal view; 
5, same, ventral view; 6, young larva. 1 and 
2 natural size, the others enlarged (after 
Osborn, from Riley, Bui. No. 5, Bureau of 
Entomology, U. S. Dept. of Agr.). 



5. Adult Fly 



64 PARASITES OF THE DOMESTIC ANIMALS 

Treatment. — The location of the grubs and the tortuous extremity 
of the canals leading to such regions render the application of remedies 
looking to their dislodgment but partly effective at best. Benzene ap- 
plied by lifting the head and pouring a teaspoonful into each nostril, 
has been recommended. As one side is treated the head should be 
held elevated and the nostril held shut for half a minute. The remedy 
is then likewise applied to the other side. In severe cases a few of the 
grubs ma.y be dislodged by a feather dipped in turpentine which is 
passed as far as possible up the nasal passage and rotated so as to apply 
it to as much of the surface as can be reached. Valuable breeding 
animals showing severe infestation may be treated by trephining the 
sinuses. 

Prevention. — To prevent the fly from depositing its larvae the noses 
of the sheep ma}^ be smeared with tar. For the convenient application 
of this preventive remedy many flock owners use salt logs in their pas- 
tures. Into these logs two-inch holes are bored at intervals of about 
six inches in each of which a little "salt is kept during the fly season. 
Two or three times a week tar is smeared with a brush around these 
holes in such manner as to smear the noses of the sheep as they en- 
deavor to reach the salt. The logs should be of sufficient length to enable 
all the sheep to get to them. 



CHAPTER VII 
THE FLEAS 

Order II. Siphonaptera. — Insecta (p. 15). Members of this order 
have the body compressed laterally, and the color is usually dark brown. 
The head is small, generally bearing a single ocellus on each side, com- 
pound eyes are absent. The mouth parts are suctorial but differ from 
those of the order Diptera in that the true haustellum is lacking, the 
sucking structure consisting of the ventrally grooved labrum and the 
two mandibles, which form a half-open tube (Fig. 36, e and £). The 
maxillae are sharp and serve to puncture the skin. The three thoracic 
segments are distinct, each bearing a pair of well-developed legs, the 
posterior pair being especially long, powerful, and adapted for leaping, 
which is the principal mode of progression. 

Metamorphosis is complete. The larvae are long, slender, without 
feet, and somewhat hairy. When mature the larva spins a cocoon and 
enters upon a distinct pupal stage. During this stage the pupa takes 
the form of the adult with the appendages enveloped in a hard pupal 
case. At no stage in the metamorphosis are there traces of the supposed 
ancestral wings. It is probable, however, that the fleas have descended 
from winged forms, and they are usually considered as being closely 
related to the Diptera. 

There are many species of fleas, most of them inhabiting various wild 
birds and mammals. It will be sufficient here to consider the following 
three of the family Pulicidse : 

1. Ctenocephahis cam's, the dog flea. 

2. Ctenocephahis felis, the cat flea. 

3. Pulex irritans, the human flea. 

The two species of Ctenocephahis can easily be distinguished from 
Pulex by the presence in the former of comb-like spines on the lower 
margin of the head and on the hinder margin of the prothorax. These 
spines are dark colored, stout and closely placed (Figs. 34 and 35). 
The dog and cat flea have long been placed together under the one 
species Pulex serraticeps, but a later classification recognizes a specific 
difference based principally upon the form of the head. In Ctenoceph- 
alus cams the head, when seen from the side, is rounded in front and 
somewhat less than t\vice as long as high. The head of C. felis, seen from 
the side, is more acute angled in front and is long, being fully twice as 
long as high. The head of Pulex irritans, with its absence of spines, is 



66 



PARASITES OF THE DOMESTIC ANIMALS 



more regularly rounded than that of the dog flea, and bears two bristles, 
one low, in the vicinity of the maxilla, the other below the eye. 

Life History.— In their life history the fleas undergo a complete 
metamorphosis. The eggs are oval, 0.5 mm. in length, and in color 
pearly white (Fig. 36, a). They are deposited loosely and unattached 
among the hairs of the host, dropping off readily during the movements 
of the animal. The period required for the eggs to incubate may be 
from one to four days or longer, depending much upon temperature. 

The larvae are white, elongate, apodal, and have thirteen segments, 
each provided with bristles (Fig. 37) . They are very active and, avoiding 
the light in every way possible, seek such shelter as is afforded by crev- 





FiG. 34. — The dog flea, anterior 
portion of body (after Osborn, Bui. 
No. 5, Bureau of Entomology, 
U. S. Dept. of Agr.). 



Fig. 35. — The human flea 
(Pulex irritans), anterior por- 
tion of body (after Osborn, 
Bui. No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



ices in the floor, carpets, rubbish, or bedding of kennels, such material 
containing fecal or other organic matter upon which they feed, being 
especially favorable for their development. 

The length of the larval stage varies considerably under the influence 
of temperature. It may be from seven to thirty days, during which 
time there are two molts. Just before entering the pupal stage the 
larva spins a white silken cocoon within which the pupa (Fig. 36, c) is 
lodged (Fig. 36, b). Transformation to the fully developed imago — 
again depending upon temperature and moisture — will occupy from 
five to ten days. The time required for the development of the mature 
insect from the deposited egg is, therefore, from thirteen to forty-four 
days, with twenty-eight days as probal^ly a fair average under our 
ordinary climatic conditions. 

Habits and Relation to Disease. — Nearly all species of fleas have 
some one host upon which they prefer to live, but they will often live 
and thrive upon other animals. The human flea will infest dogs and 



THE FLEAS 



67 




PARASITES OF THE DOMESTIC ANIMALS 



cats and may be found upon these animals in common with the species 
usually infesting them. As a pest of the household the human flea is 
more commonly found in Europe and the western part of the United 
States, while in the eastern United States houses may be rendered un- 
inhabitable for a time by the presence of the dog and cat flea. 

Fleas are of importance as tormenting parasites of man and domestic 
animals, but of late have received greater attention in the field of med- 
icine as carriers of disease. It is known that bubonic plague, which 
during recent years has made its appearance on the Pacific and Gulf 
coasts of the United States, is transmitted by these insects. Tseniasis 
of the dog, due to the presence of Dipylidium cani- 
num, may be conve\^ed to humans as well as to dogs 
through the intermediation of the dog flea, while a 
disease of infants known as kala azar, occurring 
in countries bordering on the Mediterranean, is 
thought to be transmitted by fleas. 

Usual Hosts. — Our larger domestic animals, such 
as horses, cattle, and sheep, are rarely attacked b,y 
fleas. Hogs are somewhat less free from them, but, 
if occurrmg in these animals, the infestation is most 
always light and causes little disturbance. Dogs, 
cats, rabbits, fowls, and pigeons are especial ob- 
jects of attack. Yomig dogs and those chamed 
up are more likely to be infested as they live amid 
conditions favorable to the breedmg of the insects 
from the laying of the eggs to their full develop- 
ment, which is particularl}-^ favored by litter and 
wooden floors. Unlike lice, fleas do not pass their 
entire cycle upon the host, nor are they limited to a particular species. 
The dog and cat flea will readily attack man, and in this country is more 
troublesome to him than the human flea. 

Vitality. — When feeding upon blood, which is the only food taken 
by the adults, fleas will live from several months to a year. Off a host 
the dog and cat flea will not survive longer than about two months, the 
length of life under such conditions being considerably shortened if the 
w^eather be hot and dr}-. 

Treatment and Control. — Where habitations are infested by these 
insects it is of first importance as a measure of control that dogs, cats, 
and other domesticated animals kept about the premises receive treat- 
ment that will rid them of the parasites. The harbormg animals maj' 
be dusted with Persian insect powder (pyrethrum), the remedy being 
applied liberally and driven well under the hair, preferably after the 
skin has been slightl.y moistened. This will not kill the fleas but will 
stupify them, in which condition they will drop off or may be combed 




Fig. 37.— Pulex irri- 
tans, larva. 



THE FLEAS 69 

from the hairs. It is well to place the animal while undergoing this 
treatment upon a large sheet of paper which may later be rolled up and 
burned with the collected fleas. In severe cases creolin or lysol solutions 
in two per cent, strength may be used. Quite effectual, but more expen- 
sive, is the preparation consisting of Peruvian balsam, ten parts; creolin, 
two parts; alcohol, one hundred parts which is recommended in the 
treatment for lice and scab mites upon small animals. In the treatment 
of cats, puppies, and chicks the powder is preferable to the last men- 
tioned preparations. 

Following treatment animals should not ])e permitted to re-enter 
their sleeping quarters until all litter has been removed and burned. 
In order that this cleanhig up process may be effectual every detail 
must be looked to. Collections of dirt and dust between floor boards 
must be removed, as well as every particle of bedding or rubbish that 
may harbor a flea brood. After this preparation the quarters should be 
thoroughly cleaned with hot, soapy water and, when drj'^, sprayed with 
kerosene or kerosene emulsion (formulae, page 48) as an additional pre- 
caution. For kennels a bedding should be used which can be frequently 
replaced, as shavings or straw. Carpet or matting should never be used 
for this purpose. 

Household Infestation. — In dealing with household infestation it is 
first necessary to exclude flea-bearing animals from the premises or 
destroy the adults which are producing the eggs upon these hosts. Flea 
larvse find excellent conditions for development under tacked-down 
carpets or matting and in spaces between floor boards. The floor 
covering, whatever it may be, should be removed, beaten, and thor- 
oughly aired. The floors may then be swept and the dust, which con- 
tains many eggs and larvae, collected and burned. Kerosene should 
then be applied with a mop in such manner that it will penetrate all 
cracks and crevices in the floor and beneath the baseboards. Benzene 
is often advised for this purpose, but, owing to the extreme danger of 
ignition, its use, excepting under the most careful supervision, is not 
to be recommended. 

Following these eradicative measures the floor coverings may be re- 
placed, but before doing so it is well, as an additional precaution, to 
sprinkle the floors Avith pyrethrum powder. This will work into the 
fabric and make the carpet or matting an unfavorable harbor for any 
larvai or adults which may have escaped the eradicative measures. 
Where the floors are oiled and rugs used instead of carpets or matting, 
the problem of getting rid and keeping rid of such an infestation is much 
lessened. 



CHAPTER VIII 

THE LICE 

There has been much disagreement among various authors as to the 
systematic arrangement of the hce. The classification given here, if 
faulty, will perhaps at least serve the purposes of this work until exacting 
systematists have better settled the matter. 

Order III. Siphunculata. — Insecta (p. 15). The Sucking Lice. — The 
lice of the order Siphunculata have the suctorial mouth parts at the 
anterior border of the head, the movable proboscis being formed of the 
upper and lower lips (Fig. 38). Within this is the sucking-tube which is 
projected beyond its sheath and buried in the skin when used to aspirate 
blood. The eyes are two simple ocelli, one on each side. The antennae 
are short. The thorax is usually broader but shorter than the head, with 
indistinct division into three segments. The legs are short and thick, the 
tarsi terminatrng in a single claw. There are no wings. The abdomen 
is large and generally elliptical in outline. The last abdominal segment 
is rounded in the male with an opening for the penis. Li the female 
this segment is notched and has two small terminal appendages. The 
female is from L5 to 5 mm. in length, the male somewhat smaller. 

Life History. — The metamorphosis is incomplete. The young, which 
leave the eggs by an operculum, have the shape of the adults but do not 
acquire the adult color and consistency until after several molts. 

jhe eggs as they are extruded from the female are glued fast to the 
hairs of the host by means of a viscid secretion. In this position they 
are commonh^ referred to as nits, which, with the aid of a hand glass, 
will be observed to have somewhat the shape of a barrel with the at- 
tached end rounded and a blunt free extremity (Fig. 40, e). 

Hatching occurs in from five to six days, the young in general re- 
sembling the adults excepting in size. They become mature in about 
four weeks. 

The sucking lice come into one family, the Pediculidse. All are per- 
manent parasites, the entire life cycle being spent upon the host. All 
are limited to a specific host, and will only accidentally inhabit a host of a 
different species. Therefore if the host is known, the specific identity 
of the parasite is readily determined. 

The characteristics of the species are here given under their respective 
host animals. It may be said of the sucking lice in general that the head 
is inserted directly on the thorax, their antennae are five-segmented; the 



THE LICE 71 

segments of the abdomen numlier eight or nine, and their tarsi are 
terminated by a single claw. 

Order IV. Mallophaga 

The Biting Lice. — Insecta (p. 15). The members of the order of 
biting lice resemble the sucking lice in general form, but differ from them 
mainly in that they are nuich smaller and have the mouth parts adapted 
for biting and mastication. They may be at once distinguished by the 
head and mouth parts; the head is usually rounded, triangular, squared, 
or crescent-shaped, and is broader than the thorax (Fig. 39). Upon the 
under side of the head are located the mandibulate mouth pieces adapted 
for cutting and feeding upon epidermic scales, hairs, feathers, and 
other cutaneous products. The eyes are simple ocelli located back 
of the short antennae and are often indistinct. The thorax is generally 
narrow, the prothorax being distinct, the two posterior segments fused. 
The legs are adapted for either clasping or running; in the first case the 
tarsi terminate in a single claw (Philopterida?), in the second the tarsi 
are long and terminate in two claws (Liotheidae). Wings are absent. 
The abdomen is generally elliptical; it may be elongate, or short and 
broad, approaching a globular outUne. Their relatively small size and 
hard, flattened bodies facilitate their movement among the hairs close 
to the body. 

In their breeding habits and life history the Mallophaga agree with 
the preceding order. 

Although the order has been variously subdivided, it will be sufficient 
here to place the biting lice according to their hosts in the two families 
Philopteridse and Liotheidae, the former including the biting lice of 
mammals and birds, the latter the lice of birds only. 

Biting lice, like the suctorial, are limited to a specific host, which as a 
uile they do not voluntarily leave unless it is to crawl upon another 
host of the same species, in which case the migration is ordinarily ac- 
complished when the bodies of the host animals are in contact. Lender 
conditions of severe infestation among poultry some of the parasites 
may pass to the roosts and nests and, by contact, even to the bod}' of a 
mannnalian host, but they will not survive such migrations for more than 
a few hours. 

Pediculosis of Domestic IMammals 

The condition commonly known as lousiness is medically referred to 
as pediculosis, a term correctly applied whether the condition be due 
to the presence of either the sucking or the biting species. The term 
phthiriasis should properly be restricted to infestation with the genus 
Phthirius in particular. 

Lousiness is usually- accompanied by an unthrifty condition, not 



72 PARASITES OF THE DOMESTIC ANIMALS 

necessarih' resulting from, but rather predisposing to the attack, the 
reduction in the functional activity of the skin in such condition afford- 
ing an inviting habitat for the parasites. Herbivorous animals which 
have been kept for a prolonged period upon dry feed, as during the 
winter months, are those most likely to be infested, lice rarely being 
found upon these animals after they have been turned upon more 
succulent food and the winter coat has been shed. 

There is, in fact, little valid excuse for the presence of these parasites 
upon our domestic animals at any time. Infestation is usually the 
accompaniment of uncleanly, impoverished, and crowded conditions of 
stabling or yarding. Well housed, well fed, and regularly groomed 
animals offer no attractions to lice, and animals so cared for will not 
have them. Excepting in accidental and transient incidents, their pres- 
ence upon man or domesticated beast reflects upon man in either case. 

Whether the degree of discomfort and injury to an animal due to the 
presence of lice upon its l)ody is slight or serious in its consequences will 
depend upon the number present and the group to which thej^ belong. 
The sucking lice, piercing the skin and feeding upon the blood and 
exudate, cause a much more intense pruritus than that occasioned by 
the biting lice which, in their habit of feeding upon surface epidermic 
products and debris, have more the nature of scavengers. 

The presence of the lice, as well as their location, is indicated by the 
pruritus, by their eggs or nits upon the hairs, and the debris of their 
molts. The irritation of the itching and rubbing, together with the loss 
of blood if suctorial lice are numerous, results in emaciation and general 
unthriftiness of an animal likely to have ])een in poor condition before 
becoming infested. 

While the presence of lice may be unmistakably evident, it should 
be made quite sure that there is not also present a form of acariasis. 
Lice fi-equently invade animals suffering from scabies, and the pruritus, 
with the accompanying scaly and scabby condition of the skin, may be 
due to scab mites, which, minute and deeply located, may be readily 
overlooked. The presence of these can only be determined with cer- 
tainty by examination of epidermic scrapings from beneath the scabs. 
For their detection and examination the microscope is necessai;;y'. They 
are, however, often difficult to discover, and the material is best sub- 
mitted to a laboratory for examination if such is available. More de- 
tailed methods of diagnosis and treatment of this condition are given 
elsewhere under the discussion of the scab mites. 

Pediculosis of the Horse 

Horses, mules, and asses harbor one species of sucking louse, Hcema- 
topinus asini, and two species of biting lice, Trichodectes equi and T. 
pilosus. 



THE LICE 



73 





38. — Hsematopinus 
asini (after Osborn, from 
Comstock. Bui. No.^ 5, 
Bureau of Entomology, U. 
S. Dept. of Agr.). 



1. Haematopinus asini (H. macrocephalus).— PediciilidiB (p. 70). 
Head long and narrow; antenna attached at lateral protuberances be- 
hind which are notches lodging the eyes. Anterior to this the head is 
more narrow with borders parallel, terminating 
in a blunt point. The thorax is much shorter 
than the head and widens posteriority. The 
abdomen is oval, with stigmata placed in the 
middle of lateral protuberances on the margins 
of segments. The general color is yellow, the 
thorax brownish. The female is 3 to 3.5 mm., 
the male 2.5 mm. in length (Fig. 38). 

2. Trichodectes equi (T. parumpilosus). Phil- 
opteridie (p. 71). — Head slightly longer than 
broad and semicircular in front of the antennae 
which are set well back. The abdomen is oval 

and bears eight trans- 
verse dark bands, each 
upon the anterior por- 
tion of a segment and 
extending from the 
middle line about half- 
way to the margin. 

The general color of the abdomen is yellowish, 
the head, thorax, and legs chestnut (Fig. 39). 
3. Trichodectes pilosus. Philopteridae 
(p. 71). — Somewhat smaller than the preced- 
ing species. Head broader than long, rounded 
in front, and slightly widened at the temples. 
The anteimse are inserted well forward, almost 
on a line with the head's anterior border, in 
which respect it markedly differs from T. equi. 
The abdomen tapers posteriorly and has upon 
the middle ofthe first seven segments darkened 
spots, less conspicuous than the bands simi- 
larly located upon T. equi. The head, thorax, 
legs, and abdomen are hairy on both surfaces. 
The general color is yellow. 

Pediculosis caused b}- suctorial lice upon the 
horse is usuall}' located at the base of the mane 
and forelock, and at the root of the tail. The hairs about these parts 
are likely to be scant, broken, or the skin entirely denuded, due to 
the rubbing against anything within reach. During the act of rubbing 
the animal has a peculiar habit of protruding the upper lip, or, if in 
reach of another animal, will gently bite it. 



Fig. 39. — Trichodectes 
parumpilosus (after Osborn, 
Bui. Xo. 5, Bureau of Ento- 
mology, U. S. Dept. of Agr.). 



74 



PARASITES OF THE DOMESTIC ANIMALS 



Biting lice are less common upon horses than suctorial. They are not 
often found on the upper parts of the body, more frequently occupj'ing 
the regions of the neck, breast, and between the fore and hind legs. 
They cause less pruritus than the sucking lice, though the animals will 
frequently rub bare places at the regions infested. Both forms may 
coexist upon the same animal. 

Pediculosis of the Ox 

Two species of suctorial lice inhabit the ox, Hcematopinus eurysternus, 
— the short-nosed ox louse, and Linognathus vituli, — the long-nosed ox 
louse. Of the biting species there is but one, Trichodectes scalaris. 

1. Haematopinus eurysternus. Pediculidse (p. 70). — Head relatively 
short and broad, rounded in front; thorax about twice as wide as long, 




Fig. 40. — Haematopinus eurysternus: a, female; b, rostrum; c, 
ventral surface of the last segments of male; d, same of female; e, egg; 
f, surface of same greatly enlarged (after Osborn, Bui. No. 5, Bureau 
of Entomology, U. S. Dept. of Agr.). 

widest posteriorly. The abdomen is oval and much larger than that of 
the sucking louse of the horse. On the lateral margin of each abdominal 
segment is a slightly colored tubercle. In the female two black blotches 
are laterally located on the terminal segment. The general color is 
yellowish gray. The female is 2 to 3 mm., the male 2 mm. in length 
(Fig. 40). 

2. Linognathus vituli (Haematopinus vituli). Pedicuhda? (p. 70). — 
Somewhat smaller than the preceding. The head is long and narrow 
and somewhat sunken in the thorax, as in a notch. The thorax is about 
as broad as long. The abdomen, like the head, is long and narrow, 
giving to the entire insect a long and slender appearance. The general 
color is a deep chestnut. The female is 2.5 to 3 mm., the male 2 to 2.5 
mm. in length (Fig. 41). 



THE LICE 



75 





This species is found upon calves, though it will also, — probably as 
frequently, — infest adults. 

3. Trichodectes scalaris. Philopterida^ (p. 71). — Head cone-shaped, 
rounded at the temples and in front, about as broad at the temples as 
long. The antennoe are inserted well back 
and are usually directed backward. The al)- 
domen is not so tapering as in the ])iting louse 
of the horse, and the median spots are larger, 
forming bands which are quite distinct. The 
general color is white. It is somewhat smaller 
than the species uifesting the horse (Fig. 42). 
This is a very common and widely dis- 
tributed species, frequently found upon cattle 
in cohabitation with the sucking lice. 

Pediculosis of 
the ox, caused 
by either the 
short or long- 
nosed species, 
is most likely 
to be found 
about the ears, 

base of the head, and along the dorsal 
line of the neck, back, and loins. The 
intense itching causes the animal to rub 
against any convenient object, and there 
is frequent licking of the parts which can 
be reached with the lough tongue. As a 
result of this rubbing large patches of 
skin may be entirely denuded of hair, 
and the skin itself in severe cases may 
become pustular and scabby. 

Contrary to what has been observed 
in the horse, biting lice probably occur 
more frequently upon the ox than the 
sucking species, therefore lousiness of 
cattle is usually accompanied by less 
itching. As to their location the l)iting lice of cattle do not limit them- 
selves, usually spreading to all parts of the body. They may frequently 
be observed crawling out upon the hairs and, when one is removed and 
examined with a hand glass, one or more hairs will often be found in the 
clutch of its claws. 



Fig. 41. — Hsematopinus 
vituli: female, under surface 
of last segments of abdomen 
of same (after Osborn, Bui. 
No. 5, Bureau of Entomol- 
ogy, U. S. Dopt. of Agr.). 



Fig. 42. — Trichodectes scalaris 
(after Osborn, Bui. No. 5, Bureau 
of Entomology, U. S. Dept. of 
Agr.). 



76 



PARASITES OF THE DOMESTIC ANIMALS 



Pediculosis of the Sheep 

This animal has one suctorial louse, — Litiognathus pedalis, and one 
biting louse, — Trichodedes splicer ocephalus. 

1. Linognathus pedalis (Hsematopinus pedalis). Pedicuhdae (p. 70). 
— Has the same general shape as the short-nosed ox louse, but is 
somewhat more slender. It is also much lighter in color, giving it a 
somewhat immature appearance (Fig. 43). 




Fig. 43. — Hsematopinus pedalis: a, adult female; b, ventral view of terminal seg- 
ments of same; c, terminal segments of male; d, egg (after Osborn, Bui. No. 5, Bu- 
reau of Entomology, U. S. Dept. of Agr.). 

This species is rare. It is said to occur only where the hair is short 
upon the legs and feet, especially about the dew-claws. It is from this 
location that it gets its common name, "sheep-foot-louse." 

2. Trichodectes sphaerocephalus. Philopterida (p. 71). — Head 
broad as long, giving the rounded appearance from which the specific 
name is derived. The abdomen is elliptical, each segment having a 
median band which is somewhat rounded upon its anterior border. 
The general color is white (Fig. 44). Of rather rare occurrence. 

The common so-called "louse" of sheep is not a true louse, but the 
degenerate fly Melophagus ovinus, described elsewhere under the par- 




THE LICE 77 

asites of the order Diptera. Pediculosis, properly so called, is seldom 
met with in sheep. While the sucking lice are localized to the lower 
parts of the legs, the biting lice lie deep in the wool, close to the body, 
seriousl}'- altering the fleece by cutting the fibers with 
their mandibles. Their location makes the condition 
rather a difficult one to contend with. 

'Pediculosis of the Goat 

Goats have one suctorial species, — Linognathus steno])- 
sis. The biting louse, — Trichodectes climax, is fairly com- 
mon and is the only species of this genus upon goats that 
is well established. _Tn- 

1. Linognathus stenopsis (Hsematopinus stenopsis). ehodeotes spha?- 
Pediculidae (p. 70). — Head long, narrow, and rounded in rocephaius (af- 
front; there are two lateral notches, below which are tf ^f °r„S!!I: 
widened temples, r rom these the head narrows rapidl}' of Entomology, 
and becomes deeply fitted into the thorax. The thorax U. s. Dcpt. of 
is widest posteriorly where it is somewhat concaved upon ^^''' 

the abdomen. The abdomen in outline is an elongated oval with stig- 
mata near lateral margins of segments. The female is 2 mm.; the male 
1.5 mm. in length. 

2. Trichodectes climax. Philopteridse (p. 71). — Head quadrangular 
in shape and broader than long. The abdomen is oval with median 
dark bands upon the segments. The head and thorax are reddish 
brown ; the abdomen is pale yellow. 

During the winter months especially', goats are apt to harbor lice in 
rather large numbers. As in other animals the sucking louse produces 
the greater irritation. The skin ma}'^ become bare in places with numer- 
ous inflamed and ulcerated areas covered with crusts. In Angora goats 
especially, the biting louse causes a great depreciation from its habit of 
cutting the hairs with its mandibles. 

Pediculosis of the Hog 

Domesticated and wild hogs have one species of louse, Hcematopinus 
suis (H. urius). This is the largest known member of the suctorial 
group. The head is very long and narrow, cone-shaped, and rounded 
in front; just posterior to the attachments of the antennae are horn-like 
protuberances, forming deep notches. The thorax is somewhat broader 
than long; dark, transverse bands may be noted upon the legs. The 
abdomen is oval in outline, with distinct segment borders; the stigmata 
are upon prominent lateral protuberances. The thorax is brownish 
red in color; the head and abdomen yellowish gray. The female is 5 
mm.; the male 4 mm. in length (Fig. 45). 

This louse is a very active blood sucker, living upon hogs of any age 



78 



PARASITES OF THE DOMESTIC ANIMALS 




or condition and everywhere where these animals are found. The 
intensity of the pruritus produced is proportionate to the parasite's 
size, the skin, as they increase in nuniberS; becoming covered with 
papules and scales. The constant itching and worry, which. seems to 

be most severe at night, is evidenced 
by the restlessness of the animals 
and their violent scratching against 
any available object. Such a con- 
dition seriously interferes with the 
growth and fattening of hogs, and 
young pigs especially will often 
succumb to loss of blood and ex- 
tensive irritation and excoriation 
of the skin. 

Pediculosis of the Dog 

Dogs have one sucking louse, 
Linognathus piliferus and one biting 
louse, Trichodectes latus. 

1. Linognathus piliferus (Haema- 
topinus piliferus). Pediculidae 
(p. 70). — Head thick, about as wide 
as long, rounded 
in front. The 
thorax anteri- 
orly is but slightly wider than the head; abdomen 

elongate oval in outline, the margins of the segments 

appearing somewhat rounded ; stigmata marginal and 

distinct. The general color is yellowish white. The 

female is 2 mm. ; the male L5 mm. in length (Fig. 46). 
2. Trichodectes latus. Philopteridae (p. 71). — 

Entire insect broad and short; more than half as 

broad as long. The head large, slightly rounded in 

front, and broader than long. The abdomen of the 

female is broad and somewhat globular in outline. 

The median abdominal bands or spots are absent. 

The general color is bright yellow (Fig. 47). 

Dogs do not seem to be as seriously affected as Bureau of Entomoi- 

other animals by the presence of lice. The sucking °^^' ^- ^- ^^p*' °^ 

louse is the more tormenting, and is usually found 

about the chin, under part of the neck, and breast, though, with the 

biting louse, it may be found on any part of the body. The biting 

species is most often found upon puppies. 

The biting louse infesting dogs is particularly of medical interest in 



Fig. 45. — Haematopinus suis (from 
jDhotograph of mounted specimen, bv 
Hoedt). 




Fig. 46. — Haemato- 
pinus piliferus (after 
Osborn, Bui. No. 5, 



THE LICE 



79 



being a larval host of the common tapeworm of the dog, Dipylidium 
cajiinum, as is also the dog flea, Ctenoceyhalus canis. Infection of the 
louse by the larva {Cysticercus trichodedes) is readily brought about 
through ingestion of the eggs of the tapeworm which may have col- 
lected about the anus or in the litter of the kennel. 
This tapeworm is occasionally found to be present in 
the intestines of human beings, particularly children. 
It is quite conceivable how such infestation might 
occur in the fondling of lousy or flea-infested dogs, 
especially if the person's food be about at the same 
time to act as a vehicle for the insects containing the 
larva. 

Pediculosis of the Cat 

Trichodectes subrostratus, the only louse harbored Fig. 47. — Tri- 
by the cat, is about the same length as the biting louse ^'\°^f°^t1- ^^^^^ 
of the dog (1 to 1.3 mm.), but is not so 
broad, and is distinguished by its pointed 
head, which is slightly longer than broad. 
The abdomen is oval, with median bands. 
The head and thorax are bright yellow in color, the abdo- 
men whitish (Fig. 48). 

Lousiness is not often met with in the cat; when it does 
occur it is usually the accompaniment to a debilitated 
condition in young animals. 





(after Osborn, from 
Denny, Bui. No. 5, 
Bureau of Ento- 
mology, U. S. Dept. 
of Agr.). 



Fig. 48.— 
Trichodectes 
subrostratus 
(after Os- 
born, Bui. 
No. 5, Bu- 
reau of En- 
tomology, 
U. S. Dept. 
of Agr.). 



Pediculosis of Man 

Three species of pediculi infest man, Pediculus humanus 
{P. capitis), the head louse, P. corporis (P. vestimenti), the 
body louse, and Phtkirius pubis (P. inguinalis) the pubic 
or so-called "crab-louse." 

1. Pediculus humanis. Pedicuhdae (p. 70). — The head 
is somewhat diamond-shaped, short, and about as broad 
as long. The abdomen has seven distinct segments, each 

bearing stigmata laterally placed. Color gray with darkened margins. 

The color is said to vary from light to dark according to the color of 

the skin or hair of the host. The female is 2.5 to 3 mm. ; the male about 

2mm. in length. 

2. Pediculus corporis. Pedicuhdae (p. 70). — Resembles preceding 
species, of which it is regarded by some authorities as merely a variety. 
It is slightly larger. The color is grayish-white. It lives upon the 
clothing of its host, crawhng upon the body to feed. 

3. Phthirius pubis. Pediculidae (p. 70). — Distinctly differs in ap- 
pearance from the two preceding. The head is short and thick, fitting 



80 PARASITES OF THE DOMESTIC ANIMALS 

into a broad concavity in the thorax. The thorax is broad and appar- 
ently fused with the abdomen, the two forming a somewhat heart- 
shaped body with base anterior. The first pair of legs is much more 
slender than the second and third which are stout and terminated by 
powerful claws fitted for clasping the hairs. The female measures about 
1.5 mm.; the male about 1 mm. in length. It infests the hairs of the 
pubic region and of the armpits, rarely passing to other parts. 

Of these three species Pediculus humanus is the most widely dis- 
tributed. 

Pediculosis, Control and Treatment 

Contagion in pediculosis is due to the rapid succession of generations 
of lice, their passage from host to host being facilitated by close associa- 
tion, grooming utensils, blankets, harness, bedding, etc. It is possible 
for domestic animals of different species to infect each other. Such 
migrations, however, are usually of an accidental nature, and the 
parasites will not as a rule remain to multiply upon a host foreign to 
them. 

Long hair, especially if combined with unclean conditions, predis- 
poses to lousiness. If in addition there is debihty, the etiologic factors 
become ideal. Plenty of nutritive food and a thorough cleaning up of 
animals and their surroundings are, therefore, essential to success, what- 
ever measures of eradication may be appHed. 

After the removal and burning of litter the stables, kennels, etc., may 
be treated with boiling water and afterward whitewashed or washed with 
a three to five per cent, creolin solution. For spraying interiors an 
emulsion of kerosene (formuhie, page 48), or the lime-sulphur prepara- 
tion (page 125) may be used. 

Clipping of long-haired animals, which may include the horse and 
ox, greatly simplifies their treatment. The Melophagus infesting sheep 
is removed with the fleece at time of shearing, the anunal soon ridding 
itself of any which may have remained upon the skin. 

Among the considerable number of insecticide agents used upon the 
bodies of infested animals but one or two of those most effectual and 
most commonl}^ emploj^ed need be mentioned here. A decoction of 
tobacco, one ounce to the quart of water, as a local application answers 
well for all animals. In using this preparation the possibihty of nicotine 
poisoning should be kept in mind. Large areas of the body should not 
be dressed at the same time. 

Horses may be treated with creolin two to three per cent., or kerosene 
emulsion. Brushes and combs, after having been disinfected by scald- 
ing, may have a Httle kerosene sprinkled upon them as thej^ are used. 
Preparations of kerosene should not be applied to sweating animals or 
while they are exposed to hot sunshine. Friction with fatty substances, 



THE LICE 81 

as linseed oil, will kill by asphyxia lice with which it comes in contact. 
This treatment is more effectual if kerosene be shaken up with the oil 
in the proportion of one of the former to two of the latter. A mixture of 
kerosene, sulphur, and lard, equal parts, is also quite useful for this pur- 
pose. 

These treatments will apply to cattle as well as to horses. Where 
large numbers of cattle are affected resort must be had to spraying with 
kerosene emulsion or dipping. For the latter purpose ordinary sheep 
dip or a lime-and-sulphur preparation may be used. 

The large sucking louse of the hog is found principally inside, behind, 
and in front of the ears, on the breast, and on the inner side of the el- 
bows. For this animal the stronger preparations of the insecticides 
should be used, as creolin five per cent, or kerosene and oil equal parts. 
The kerosene, sulphur, and lard mixture is quite a suitable one for these 
animals. It is well also to treat their wallows with a three to five per 
cent, solution of creolin. 

For dogs creolin in two per cent, strength is quite satisfactory. Long- 
haired dogs, especially if heavily infested, should be clipped before 
treatment. For small house animals, as toj^ dogs and cats, pyrethrum 
powder, apphed to the moistened skin as for fleas, is most suitable. 

Whatever insecticide is used it is well to apply vinegar in conjunction 
with it. This may be added to the fluid preparations in the proportion of 
about ten ounces to the quart, or it may be applied separately diluted 
with twice its quantity of water. The vinegar has a destructive action 
upon the eggs which may survive the ordinary remedies used to destroy 
the insects. 

Sodium fluoride, which is recommended in the treatment of lice of 
poultry, all of which are biting lice, should also be effective for the biting 
lice of mammals, though experience with it up to the present time is not 
sufficient to have established its value in such cases. In its application 
it should be rubl)ed into the hair over all parts of the body. The treat- 
ment is only applicaljle to biting lice. 

All measures used for the eradication of lice, whether in the quarters 
or upon the bodies of their hosts, should be repeated at least three times 
at intervals of eight to ten days. This is necessary to destroy the hce 
which may emerge from remaining eggs. 



CHAPTER IX 

LICE OF POULTRY. THE BEDBUG 

Birds under the usual conditions of domestication are especially- 
prone to lousiness; there are, in fact, few fowls entirely free from them. 
Though, relative to their numbers, lice upon poultry probably do less 
harm than the blood-sucking ticks, their rapid multiplication, and the 
fact that they pass their entire cycle upon the bodies of their hosts, 
make it probable that any degree of infestation will become a destruc- 
tive nuisance. The constant annoyance due to their crawling upon 
the skin and among the feathers, with the energy expended in the efforts 
to be rid of them, causes fowl to droop and become ready victims to other 
diseases commonly affecting poultry. Flesh and egg production, under 
such conditions, must essentially be retarded to a degree commensurate 
to the infestation. 

Young chicks are especially apt to succumb. The}^ give evidence of 
the presence of lice by drowsiness, refusal to eat, and an emaciated 
body. The symptoms are generally accompanied by a loss of feathers, 
especially about the head and lower part of the neck. Chickens hatched 
in an incubator should be free from them, and they will remain so unless 
placed with a lousy hen or put in infested quarters. 

The head and upper part of the neck afford a protective location for 
the lice, as they cannot here be reached by the beak. They may, how- 
ever, especially in older birds, be found upon all parts of the body. 

The biting species with which birds are infested belong with either the 
Philopteridse or Liotheidse, the former containing species harbored by 
both mammals and birds, the latter lice of birds only. 

Lice of Chickens 

The Philopteridse of chickens are Goniocotes gallince, G. gigas, Lipeurus 
caponis, and L. heterographus. 

\. Goniocotes gallince {G. hologaster). — Head broad as long; anterior 
border rounded; angular at temples. Abdomen sac-like in outline, hav- 
ing curved bands upon lateral l^orders of segments; transverse patches 
in double row. General color dirty yellow. Female about 1 mm. in 
length. 

A common species. 

2. Goniocotes gigas (G. abdominalis) . — Head rounded, circular in 
front. Thorax narrow. Abdomen large and but slightly longer than 



LICE OF POULTRY. THE BEDBUG 



83 



broad; each segment marked laterally by long tongue-shaped spots. 
The general color is yellowish. The female is 3 to 3.5 mm. in length, a 
size exceptional in this genus (Fig. 49). 

About as common as the preceding species. 

3. Lipeurus caponis (L. variabilis). — In all members of this genus the 
body is elongated and narrow. Head longer than broad and rounded in 
front. Abdomen long and slender with black margins. Color yellowish 
white. Female about 2 mm. in length (Fig. 50). 

By its long and slender appearance this species can easily be dis- 
tinguished from others mfesting the chicken. It is not very common. 

4, Lipeurus heterographus. — Head more narrow in front and body 
much stouter than in preceding species. Abdomen elongated oval in 






Fig. 49. — Gonio- 
cotes abdominalis 
(after Osborn, from 
Denny, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 



Fig. 50. — Lipeu- 
rus variabilis (after 
Osborn, from 
Denny, Bui. No. .5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 



Fig. 51. — Menopon 
pallidum (after Os- 
born, from Denny, 
Bui. No. 5, Bureau 
of Entomology, U. 
S. Dept. of Agr.). 



outline with median spots on each ring. General color pale yellow. 
Female 2 nun. in length. 

This species has not been often observed in this country. It is said 
to also occur upon certain species of pheasants. 

Of the Liotheidffi chickens are hosts to two species, Menopum trig- 
onocephalum and M. biseriaium. 

5. Menopum trigonocephalum (M. pallidum; Menopon pallidum). — 
Head somewhat triangular, rounded in front and at the temples. Abdo- 
men of female elongated oval in outline, in male longer and narrower. 
Legs stout and hairy. Color light yellow. Female about 1.5 mm. in 
length (Fig. 51). 

This is the most prevalent of all of the hen lice. It is an active runner 
and passes readily to other species of birds. 

6. Menopum biseriatum (Menopon biseriatum). — Head somewhat 
crescent-shaped. Legs stout. Abdomen elongate. Has the same gen- 



84 PARASITES OF THE DOMESTIC ANIMALS 

eral color as M. trigonocephalum, but is larger. Female about 2.5 mm. in 
length (Fig. 54). 

Less common than preceding species. It attacks young chicks, espe- 
cially about the head and anus. It may also be found upon turkeys and 
peafowl. 

Lice of Turkeys 

The Philopteridse of turkeys are Goniodes stylifer and Lipeurus 
meleagridis. 

1. Goniodes stylifer. — Head broad as long, well rounded in front, with 
posterior angles projected backward into pomts which are terminated bj^ 
strong bristles. Thorax angular and narrowed anteriorly. Legs slender 
and hairy. Abdomen broad, with tongue-shaped bands on the sides. 
Hairs are numerous and long on both surfaces. Color yellowish white. 
Female about 3 mm. in length (Fig. 52). 

This is a large species common upon turkeys everywhere. 

2. Lipeurus meleagridis (L. polytrapezius) . — Head longer than broad, 
romided in front and at the temples. Thorax and abdomen narrow and 
elongate; last abdominal segment in female deeply notched. Color pale 
yellow. Female about 2.8 mm. in length (Fig. 53). 

Also quite common. 

The Menopum of the turkey is M. hiseriatum (Fig. 54), referred to 
under the Liotheidae of chickens. 

Lice of Ducks and Geese 

Of the Philopteridse ducks and geese harbor two species, Philopterus 
icterodes and Lipeurus anatis. 

1. Philopterus icterodes {Docophorus icterodes). — Head longer than 
broad, rounded m front; lower portion expanded and rounded. Abdo- 
men oval in outline, white in center, and with dark lateral bands. Color 
brownish red. Female 1 mm. in length. 

Of common occurrence. 

2. Lipeurus anatis (L. squalidus). — Head longer than broad, cone- 
shaped, rounded in front. Thorax and abdomen elongate with dark 
borders. On the abdomen the border is broken into patches correspond- 
ing with the segments. General color light yellow. Female about 4 mm. 
in length (Fig. 55). 

Frequently found upon both domestic and wild ducks. 
The Liotheidae of ducks and geese are Trinotwn luridum and T. 
lituratum. 

3. Trinotwn luridum (Trinoton luridum). — Head as wide as long, 
somewhat triangular m shape, with rounded corners. Thorax longer 
than head. Abdomen long and narrow, with dark bands upon the 



LICE OF POULTRY. THE BEDBUG 



85 




Fig. 52. — Goniodes stylifer 
(after Osborn, Bui. No. 5, Bu- 
reau of Entomology, U. ^S 
Dept. of Agr.). 





Fig. 53. — Lipeurus polytrapezius 
(after Osborn, from Piaget, Bui. No. 5, 
Bureau of Entomologv, U. S. Dept .'of 
Agr.). 




Fig. 54. — Menopon biseriatum (after 
Osborn, Bui. No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



Fig. 55. — Lipeu- 
rus squalidus (after 
Osborn, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 



86 PARASITES OF THE DOMESTIC ANIISIALS 

segments. Entire insect long and narrow. General color grayish. 
Female 4 mm. in length (Fig. 56). 

A common species. 

4. Trinotum lituratum (Trinoton lituratum). — Shorter and smaller 
than the preceding species, with head, thorax, and abdomen relatively 
broader. Legs broad and stout. Abdommal segments bordered by 
darkened spots. Color white. 

This species occurs upon domestic geese. 

Lice of Swan 

Philopterus cygni and Ornitlionomus cygni are species of Philopteridse 
harbored by swan. 

1. Philopterus cygni (Docophorus cygni). — Head about as broad as 
long, rounded in front. Thorax short and narrow. Abdomen sacular, 
white in center, darkened at sides. Head, thorax, and legs reddish 
brown. Female 1 mm. in length (Fig. 57). 

This is the "Little Red Swan Louse." It is quite common. 

2. Ornithonomus cygni {Ornithobiiis bucephalus; 0. cygni). — Head 
massive and nearly as broad as long. Thorax about the same length as 
head. Abdomen narrow oval, tapering toward apex; black points on 
outer margins of four of the abdominal segments. The bodj' is trans- 
parent and much flattened. General color white. Female 4 mm. in 
length (Fig. 58). 

Occurs in great abundance on all species of swan. 

Lice of Pigeons 

The more common Philopteridse of pigeons are Goniocotes compar, 
Goniodes damicornis, and Lipewus columbce. 

1. Goniocotes compar. — Head large, nearlj' as broad as long, rounded 
in front. Thorax narrow. Abdomen broad oval. Color dirty yellow. 
Female about 1.3 mm. in length (Fig. 59). 

Found quite frequenth'. 

2. Goniodes damicornis. — Head about as broad as long, rounded in 
front, angular behind. Legs stout. Abdomen broad and short. Color 
t)rown. Female 2 mm. in length (Fig. 60). 

Not as common as preceding species. 

3. Lipeurus columbce (L. baculus). — Characterized by its extreme 
slenderness. Head long and narrow, as is also the thorax and abdomen. 
Upon the abdominal segments are brownish patches. Head and thorax 
brownish red in color; abdomen dusky. The female is 2 mm. in length. 

Occurs abundantlv. 



LICE OF POULTRY. THE BEDBUG 








Fig. 56.— Trino- 
ton luridum (after 
Osborn, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 




Fig. 57. — Docophorus 
cygni (after Osborn, Bui. 
No. 5, Bureau of Ento- 
mology, U. S. Dept. of 
Agr.). 



M 


w 



Fig. 5)S. — Ornithobius cygni 
(after Osborn, Bui. No. 5, Bureau 
of Entomology, U. S. Dept. of 
Agr.). 



^^try^ 




,M 


3 ' 








1 




T~~- — ^— 





Fig. 59. — Goniocotes corn- 
par (after Osborn, Bui. No. 5, 
Bureau of Entomology, U. S. 
Dept. of Agr.). 




Fig. 60. — Goniodes dani- 
icornis (after Osborn, Bui. 
No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



88 PARASITES OFfcTHE DOMESTIC ANIMALS 

CONTROL^AND TREATMENT 

In dealing with lice of poultry we should first discriminate between 
the lice and the ticks, bearing in mind that the latter do not breed upon 
their hosts. According to whether they be one or the other the treatment 
will be modified somewhat, though certain measures of eradication may 
be suitable for either. All species of lice, without a known exception, 
passing their transformation upon the host, there may be confidence in 
attacking them that there are no eggs and young developing in some 
out-of-the-way retreat, as in the case of ticks or bedbugs. 

As a means of controlling bird lice the dust bath should receive first 
attention. The fine dust particles enter the spiracles of the insects, 
killing them by suffocation, therefore, of whatever material it may con- 
sist, the dust will be most effectual when fine and penetrating. Road 
dust is usually quite suitable; it will be the more efficient if powdered 
tobacco be added in the proportion of about one of tobacco to five of 
dust. Fine ashes, in which powdered sulphur is mixed, make an ex- 
cellent dust wallow. A mixture of road and lime dust, with the addition 
of a cupful or two of sulphur, may be used with as good results. The 
dust baths should be in deep and roomy boxes placed where they will be 
sheltered from the rain. 

As an insecticide for the individual treatment of badly infested birds, 
any oleaginous substance is effectual. As with dust, the principle upon 
which its use is based is that of suffocation, the unctuous agent serving 
to plug the breathing pores of the insect. A mixture of lard and sulphur 
answers well for all birds. It should especially be applied at the throat, 
upper neck, bases of the wings, and at the base of the tail feathers. If a 
powder is used, as pyrethrum, the skin should be first moistened with 
soapy water or equal parts of glycerin and water and the powder then 
blown well under and through the feathers. 

Investigations by the United States Bureau of Entomology with 
sodium fluoride have demonstrated that lice infesting poultry may be 
readily destroj-ed by the application of a small quantity of this powder. 
It may be used in the powdered form or as a dip. Applied by the former 
method, it should be sprinkled under the feathers of the neck, breast, 
back, tail, below the vent, and upon the under side of each wing as these 
are spread. If used as a dip, this may be prepared by adding one ounce 
of commercial sodium fluoride to the gallon of water. The solution 
should be made tepid and the entire body of the fowl, excepting the 
head, immersed in it. For the treatment of one hundred fowl, about one 
pound of the powder will be required. 

As the lice are likely to be dislodged from their hosts to be harbored 
for a time about nests, roosts, etc., it is essential that the eradicative 
measures be also applied to the quarters of infested birds. The louse 



LICE OF POULTRY. THE BEDBUG 89 

most commonly fomid upon the hen, Menopum trigonocephalum, is an 
especially active runner, readily passing to other species of birds or to 
any object with which the infested animal is in contact. It is said that 
horses kept in the vicinity of chicken houses harboring this louse are 
often seriously troubled by it. 

In this connection the measures recommended for the eradication of 
the lice of mammals and poultrj'-infesting bedbugs will in general 
apply here. All nesting material and litter must, of course, be cleared 
out and burned or buried. A washing down with five per cent, creolin 
or carbolic acid solution should follow, the usual whitewashing in such 
cases adding to the probability of a complete destruction of the lice. 
The lime and sulphur mixture (page 125), apphed as a spray to all parts 
of the interior, is penetrating and gives satisfactory results. 

As a simple agent for the killing of lice or mites in the hen house and 
dovecot the cloud of lime dust is said to be of much value. In the appli- 
cation of this method the birds should be absent and the quarters closed. 
A few handfuls of finely powdered lime are then thrown against the roof 
and walls, producing a cloud of dust. This will settle upon the roosts, 
nest compartments, and floor, and into the crevices, destroying many of 
the exposed vermin. Afterward the place should be swept out and the 
sweepings buried, burned, or otherwise destroyed. 

Fumigation is commonly resorted to, and may have value as a con- 
tributory measure. The sulphur fumigation, applied as recommended in 
the eradication of bedbugs, will serve here as well. 

Observations made as to the length of time required for the hatching 
of the eggs, while not complete, indicate that for species of bird lice in 
general, five to six days are necessary at least. Therefore, in repeating 
treatments intended to kill individuals hatched from remaining eggs, 
there should be an intervening period of about ten days. 

Order V. Hemiptera 

Insecta (p. 15). — This group includes the cicadas, plant lice, and true 
bugs. The mouth parts are suctorial, the mandibles and maxillae being 
modified into bristle-Hke structures for puncturing and extracting the 
juices of plants or the blood of animals. The labium is usually jointed 
and forms a sheath for the piercing bristles. There are usually four 
wings, some fomis having the first pair thickened and leathery at the 
base, while only the tips are membranous and elastic. It is from this 
" half-winged " structure that the order derives its name. In some of the 
lower forms (bedbugs) wings are absent. A characteristic of the order is 
the presence of stink glands, which in the adult open ventrally on the 
metathorax. The secretion from these glands has a disgusting odor, 
probably originally of defensive service to the insect though in parasitic 
forms rather serving to reveal their presence and location. The meta- 



90 PARASITES OF THE DOMESTIC ANIMALS 

morphosis is incomplete, the immature insect resembling the adult ex- 
cept in the absence of wings. 

Family Cimicid^ 

Hemiptera (p. 89). Bedbug and allies. — The body is much flat- 
tened and is ovate in outline. The adults are reddish brown in color ; 
young yellowish white. AVhen full grown they are from one-sixth to one- 
fifth of an inch in length. The mouth parts inclose long slender stylets 
(Fig. 61, d). Ocelli are absent. Wing-covers rudimentary (Fig. 61, c). 

CiMEx Lectularius 

Acanthia lectularia. The common bedbug. (Fig. 61). — Cimicidse 
(p. 90). The body is covered with short hairs; rostrum short; third 
and fourth joints of antennae much thinner than first and second; second 
segment of antennae shorter than third. 

The eggs are oval, pearly-white, and about a millimeter in length. 
The young leave the egg by a small operculum at the end. The female 
deposits from one hundred to two hundred eggs in cracks, crevices, and 
seams of beds and bedding, beneath loose portions of wall-paper, base- 
boards, floor spaces, and similar retreats. 

Hatching occurs in about one week. Development from the nymphal 
to the adult stage will, under favorable conditions, occupy about six 
weeks. The time required for the development of adults from deposited 
eggs under such conditions may, therefore, be approximated at from 
seven to eight weeks. 

Habits and Effect of Bite. — In their feeding habits bedbugs are 
nocturnal, hiding in their darkened retreats during the day and coming 
forth at night to crawl upon the legs, arms, neck, or other unprotected 
parts of their victims, where they will feed to repletion. After this en- 
gorgment the insects will retreat to their usual haunts to remain for 
several days, during which time the meal is digested. 

The effect of the bite of the bedbug varies, depending upon the sus- 
ceptibihty of the one attacked. In some it produces marked irritation 
with more or less sweUing; others may not be made aware of its presence. 
The inflammation experienced by sensitive persons seems to result 
mainly from the puncture of the skin. The biting organ is like that of 
other hempiterous insects; there are four piercing filaments within the 
labium which is closely applied to the point of puncture as the blood is 
drawn up. 

The degree to which the insect may injure other animals than man is 
somewhat obscure. Probably the same or closely allied species to those 
attacking man attack animals in the same manner. Chickens are es- 



LICE OF POULTRY. THE BEDBUG 



91 




92 PARASITES OF THE DOMESTIC ANIMALS 

pecially likely to be their hosts, the usual quarters of poultry affording 
an ideal harbor for such pests. 

Control. — Bedbugs may be easily carried upon clothing, therefore 
puljlic conveyances and places where people of all sorts and conditions 
of living may congregate, afford a common means for their dissemina- 
tion. They are highly prolific, and the introduction of a single egg- 
bearing female may be sufficient to start a colony of bedbugs within a 
few months. 

Eradication is made somewhat difficult by the parasite's habit of 
seeking hiding places during the day, therefore anything used for this 
purpose must be of such a nature that it will penetrate into cracks, 
crevices, joints of bedsteads, mattress seams, and all such places where 
the gregarious insects are in the habit of assembling and depositing 
their eggs. Powders, such as pyrethum, are of practically no value as 
they are not sufficiently penetrating. One of the best remedies is kero- 
sene, applied with a feather, or, better, with an ordinary machine oiler. 
Benzene is as effectual and will volatilize more readily, but must be 
used with great caution against ignition. A solution of corrosive sub- 
limate in alcohol may also be used with good results. Fumigation is of 
doubtful value, though flowers of sulphur, two pounds to each one 
thousand cubic feet of room space, has been recommended for this pur- 
pose. The sulphur should be placed in a heap in a pan, a depression 
made in the top, and a small quantity of alcohol poured into this to 
facilitate burning. The container should be placed in a larger pan and 
surrounded by water as a precaution against fire. During fumigation 
the room should, of course, be tightly closed. Fumigating with 
formaldehyde gas is as useless against bedbugs as it is against other 
insects. 

Whatever remedy may be applied, thoroughness is essential to success. 
Beds and bedding should be inspected daily, and all places where the 
bugs may have found a hiding place repeatedly treated. There will be 
less difficulty if brass and iron bedsteads are used, the old-fashioned 
wooden bedsteads furnishing many retreats into which the bugs can 
force their flat, thin bodies. 

In infested chicken houses the parasites usually secrete themselves 
around the ends of the roosts and in the nests. Their attack upon the 
chickens at night results in a loss of flesh with reduced egg production. 
In heavy infestation chickens will often die from emaciation and loss 
of blood. If the propagation of the bugs in the chicken houses is not 
checked, they may spread to nearby buildings to become a source of 
annoyance to other live stock. 

Control measures in such cases consist in thoroughly renovating the 
chicken house. Roosts in wooden fittings should be taken down, and 
all loose lumber, useless boxes, straw, or other material affording hiding 



LICE OF POULTRY. THE BEDBUG 93 

places removed and burned. Possible breeding places remaining should 
be sprayed with kerosene or kerosene emulsion (page 48). Scalding 
hot water or whitewash will destro}- both the insects and the eggs. The 
kerosene application should be repeated at frequent intervals to insure 
the eradication of followmg generations. 



^ 



^OJuy^ 



CHAPTER X 

THE MITES 

Class II. Arachaida. Arthropoda (p. 13). — The arachnids may at 
once be distinguished from the insects by the relationship of the body 
parts and the number of ambulatory appendages, as to be described. 

The regions of the body are more or less fused, the head being com- 
monly fused with the thorax to form the cephalothorax (Fig. 62) , 

The abdomen is in some forms segmented (scorpions), in others un- 
segmented and separated from the thorax by a deep construction (true 
spiders). 

Sometimes the cephalothorax and abdomen are fused into one un- 
segmented body (ticks and mites) . 

In the adult there are four pairs of locomotor appendages, usually 
seven-jointed, attached to the cephalothorax. There are no wings. 

Antennae are absent. 

The mouth parts are paired chelicerse and pedipalpi, the first in front 
of the mouth, the second to the side. 

The chelicerse are short, consisting of two or three joints. The last 
joint may have a claw-like termination for piercing and introducing 
poison into prey (spiders), or it may be in the form of small chelae (scor- 
pions). 

The pedipalpi are longer and more like the appendages for locomo- 
tion. The terminal segment may be strongly chelate (scorpions). 

The eyes are located anteriorly upon the cephalothorax and consist 
of a varying number of ocelli. The eyes are never compound. 

The skin is of a leathery consistency and is not so hard as in insects. 

Respiration is either by tracheae or by so-called book-lungs, the latter 
consistmg of a series of invaginations of the skin closely applied like the 
leaves of a book. Either one or both of these forms of respiratory organ 
may occur in a single individual. 

Most arachnids are oviparous. In aberrant forms, as Linguatulida and 
Acarina, certain adult appendages are acquired after a molt. 

The class Arachnida includes the scorpions, spiders, ticks, and mites. 

The two parasitic orders are Acarina, which includes the ticks and 
mites, and Linguatulida, containing the species Linguatula rhinaria. 

Order I. Acarina. Ticks and Mites. — Arachnida (p. 94). These are 
small, freciuently microscopic, arachnids iii which there is generally no 
distinct demarcation l^etween the cephalothorax and abdomen, the body 
regions being massed into one. 



THE MITES 95 

Due to parasitism, the mites have undergone considerable modifica- 
tion, the scab mites are without ej-es or organs of respiration, and gener- 
ally the tips of the feet are terminated by suckers or bristles. 

In the larval stage, the Acarina have but three pairs of legs, the fourth 
pair appearing behind the third after a molt. 

The mouth parts are modified into a beak-like structure for piercing 
and sucking. 

The sexes are separate and reproduction is by eggs which are extruded 
from the genital pore situated, as in other Arachnida, anteriorly on the 
ventral surface of the abdomen. In the scab mites (Sarcoptidse) the fe- 
males are provided with a second genital opening, the copulating vagina, 

G J M 




Fig. 62. — Diagram of the anatomy of a spider: a, anus; b, cecum of 
mesenteron; b', its anterior end; b", branches of cecum extending into 
legs; c, cerebral ganglion connected with ventral ganglionic mass; d, 
mesenteron; e, poison glands; g, heart; h, chelicerae; i, pedipalpi; j, liver; 
k, hepatic duct; 1, lung sac; m, Malpighian tubules; n, dilation of rectum 
into which Malpighian tubules open; o, eyes; ov, ovaries; p, female 
genital pore; q, large and small silk glands; r, opening of tracheal system; 
s, spinnerettes (after Boas by Kirkaldy & Pollard). 

which is located posteriorly just in front of the anus. It is at this open- 
ing that spermatozoa are received during copulation, the anterior open- 
ing serving as the pore of the oviduct. 

In their development the Acarina undergo a succession of stages. The 
larvae are usually provided with but three pairs of legs (hexapodal), and 
have no definite sexual characters. After molting a fourth pair of legs 
appears, and the acarus enters upon its njanphal stage. Following 
further molting the genital organs are acquired, and it has then reached 
the pubescent stage, or stage of sexual maturity. After copulation the 
female undergoes a further transformation, l^ecoming an egg-bearing, 
or ovigerous female. 

Parasitism. — The majority' of the Acarina are parasitic, though, as 
to this habit, there is much diversity, some being semiparasitic, others 
essentially so and restricted to definite hosts. 

The order contains a number of families of which the following are 
here considered: 



96 PARASITES OF THE DOMESTIC ANIMALS 

Famil}^ I. Gamasidae. — Poultry mites. 

Family II. Trombidiidae. — Harvest mites or chiggers. 

Family III. Sarcoptidse. — Mange and scab mites. 

Family IV. Demodecidae. — Follicle mites. 

Family V. Cytoleichidse. — Deep seated mites of birds. 

Superfamily Ixodoidea. — The ticks. 

Family I. Argasidce. — The fowl tick and ear tick. 

Family II. Ixodidge. — The cattle tick and other ticks. 

Each of these contains species parasitic upon mammals or birds with 
the exception of the Demodecidae, which, so far as known, have only 
been found upon mammals. 

The condition produced upon the host by the presence of parasitic 
Acarina is designated medically as acariasis. Differing in their grade 
of parasitism, the numerous species bring about a varying degree of 
disturbance to the skin which they inhabit. Accordingly there is dis- 
tinguished sarcoptic and psoroptic acariasis, the former produced by 
species which burrow and form subepidermic galleries in which they 
deposit their eggs, the latter by species living upon the skin's surface. 
The term mange is limited by most writers to acarises caused by species 
of the genus Sarcoptes and its near alKes, or by Demodex, both living 
beneath the skin's surface, the last named in the hair follicles and se- 
baceous glands. The psoroptic form, in which there is deep scab for- 
mation, constitutes true scabies or scab, although these latter terms are 
frequently used in a general sense relative to the condition produced 
by the mange and scab mites. Acari belonging with the families Ga- 
masidae, Trombidiidae, and the superfamily Ixodoidea do not cause 
mange or scab. 

Classification of Parasites of the Class Arachnida 

Class B. Arachnida. P. 94. 
Order I. Acarina. P. 94. 
Family (a) Gamasidae. P. 98. 
Genus and Species: 

Dermanyssus gallinae. Host, poultry. P. 98. 
Family (b) Trombidiidae. P. 99. 
Genus and Species: 

Trombidium holosericeum. Larvae attack man and lower 
animals. P. 100. 
Family (c) Sarcoptidae. Mange and scab mites. P. lOL 
Genus and species: 

Sarcoptes scabiei var. Equi. Host, equines. P. 104. 
S. scabiei var. 'Ovis. Host, sheep. P. 112. 
S. scabiei var. Bovis. Host, cattle. P. 114. 
S. scabiei var. Suis. Host, hog. P. 114. 



THE MITES 97 

S. scabiei var. Canis. Host, dog. P. 115. 
Notoedres cat! var. Cati. Host, cat. P. 118. 
N. cati var. Cuniculi. Host, rabbit. P. 118. 
Psoroptes communis var. Equi. Host, equiiies. P. 108. 
P. communis var. Ovis. Host, sheep. P. 109. 
P. communis var. Bovis. Host, cattle. P. 113. 
P. comnmnis var. Cuniculi. Host, rabbit. P. 118. 
Chorioptes commimis var. Equi. Host, equines. P. 108. 
C. communis var. Ovis. Host, sheep. P. 112. 

C. communis var. Bovis. Host, cattle. P. 113. 
Otodectes cynotis var. Canis. Host, dog. P. 117. 

0. cynotis var. Cati. Host, cat. P. 117. 
Cnemidocoptes mutans. Host, poultr}-. P. 132. 
Cn. gallinae. Host, poultry. P. 133. 

Family (d) Demodecidae. Folhcular mange mites. P. 103. 
Genus and Species: 

Demodex folliculorum var. Ovis. Host, sheep. P. 112. 

D. folhculorum var. Suis. Host, hog. P. 115. 
D. folliculorum var. Canis. Host, dog. P. 116. 

Family (e) Cytoleichidae. P. 134. 
Genus and Species: 

Cj'toleichus nudus. Host, poultry. P. 134. 
Laminosioptes cysticola. Host, poultry. P. 134. 
Superfamily Ixodoidea. Ticks. P. 139. 
Family (a) Argasidse. P. 139. 
Genus and Species: 

Argas miniatus. Host, poultry. P. 139. 
Otobius megnini. Hosts, equines, cattle, etc. P. 140. 
Family (b) Ixodidse. P. 141. 
Genus and Species: 

Ixodes ricinus. Hosts, cattle, equines, dog, etc. P. 143. 

1. hexagonus. Hosts, cattle, dog, etc. P. 143. 
Dermacentor variabilis. Hosts, cattle, dog, equines, etc. 

P. 143. 
D. reticulatus. Hosts, cattle, equines, etc. P. 143. 
Margaropus annulatus. Hosts, cattle, equines. P. 144. 
Amblvomma americanum. Hosts, cattle, dogs, equines, etc. 
P. i45. 
Order 2. Linguatulida. P. 153. 
Family (a) Linguatulidse. P. 153. 
Genus and Species: 

Linguatula rhinaria. Host, dog. P. 153. 



98 



PARASITES OF THE DOMESTIC ANIMALS 



Family I. Gamasid^e 

Acaiiiia (p. 94). — The gamasid mites. The mouth parts are] ar- 
ranged for piercmg and sucking, maxillae fused into a tube, maxillary 
palps five-segmented and provided inwardly with secondary palps. 
The legs have six segments, the tarsi terminating b,y two booklets. 
There are two stigmata located near the insertion of the posterior legs. 
The cephalothorax and abdomen are fused into one body. The integu- 
ment is of a leatherv texture. Eves are absent. 



Dermanyssus Gallin.e 

Poultry mite; chicken "tick" (Fig. 63). Gamasidse (p. 98). — Body 
somewhat egg-shaped with larger end posterior, slightly flattened from 
above to below. The lower half of the body is provided with short, 




Fig. 63. — Dermanyssus gallinae: a, adult; b, tarsus; c, mouth- 
parts; d and e, young — all enlarged (after Osborn, Bull. No. 5, Bureau 
of Entomology, U. S. Dept. of Agr.). 

well-separated bristles. The color is Hght gray with dark patches 
showing through the skin; when engorged with blood the color is a 
distinct red. The ovigerous female is rather less than 1 mm. in length. 

Occurrence and Habits. — The little poultry mite, found everywhere 
where chickens are kept, is one of the most persistent and injurious pests 
that the poultry raiser has to contend with. Remaining in darkened 
retreats about the henhouse during the daytime, these acari come forth 
at night to swarm upon the fowls and suck their blood. Their attack, 
however, is not confined entirely to the night, and hens may be driven 



THE MITES 99 

from their nests by the activity of the pests which the warmth of their 
bodies creates. 

The Demianyssiis does not hmit itself to birds, but may attack 
mammals, including man, though these animals, being accidental hosts, 
the invasion is usually limited in its extent and duration. Horses kept 
in the vicinity of infested henhouses are likely to be tormented by the 
mites, the litter about stables so located affording a harbor to which 
they readily migrate. 

The eggs are deposited in vast numbers in the daytime retreats. 
Under ordinary conditions about five days are required for the hatching 
of the hexapodal larvae which do not wait for maturity to attack the 
chickens. They may, however, remain for months without a host upon 
which to satisfy their appetite for blood. Extremely prolific, they 
especially thrive upon filth, and large colonies may be found wherever 
such material has collected. 

Effect. — ^Fowls suffer not only from the extreme irritation and an- 
noyance of the attack, but additionally from the extraction of a consider- 
able amount of blood. Prolonged infestation must essentially brine; 
about a progressive emaciation and weakening which may end in death, 
young chicks especially being likely to succumb. In any event egg 
production is retarded, and the chickens, in their unthrifty condition, 
are unprofitable for marketing. 

Control. — Cleanliness and plenty of sunlight are especially antago- 
istic to the Dermanyssus. The cleaning up measures set forth elsewhere 
for the eradication of the parasites of the henhouse need not be repeated 
here. Kerosene emulsion (page 48) is serviceable, but should only be 
applied after the entire interior has been stripped to the boards of every- 
thing movable and all crevices, joints, and roost insertions exposed. 
It is well to drench cracks and the ends of roosts with pure kerosene or 
scalding water. The ends of roosts, before being replaced, should be 
dipped in coal tar, and this spread along the roosts for about six or eight 
inches from their supports in such manner that the mites will be obliged 
to cross the tar before reaching the fowls. Pyrethrum powder, alone or 
mixed with lime dust, should be shaken through the fresh nesting mate- 
rial. The dust bath, as recommended in the treatment for lice, should 
always be accessible. 

In order to insure continued freedom from the vermin it is necessary 
that the control measures be repeated at least three times at intervals 
of about ten days. 

Family II. Trombidiid^ 

Harvest mites; chiggers, or red bugs. Acarina (p. 94). — The body is 
red in color and covered with bristles or fine hairs. The mandibles are 
chelate; palpi prominent. The legs have six to seven segments pro- 



100 PARASITES OF THE DOMESTIC ANIMALS 

vided with bristles or fine hairs, the tarsi terminating in two hooklets. 
Respiration is by tracheae. There are two eyes, one located upon each 
side of the cephalothorax. 

Trombidium Holosericeum 

Trombidiidse (p. 99). — Body red and nearly square; slightly narrower 
posteriorly where the terminal border is slightly concaved; body and 
legs covered with bristly hairs. Eyes pedunculated. About 1 mm. in 
length. 

Habits and Effect. — In the adult stage the Trombidium is free- 
living, feeding upon the juices of plants and small insects. It is only 
parasitic in its larval condition, in which stage it will inhabit insects 
and attack warm-blooded animals as well. Living in the tall grass and 
upon the under side of the leaves of weeds, they are brushed off upon 
the hands or clothing of people and upon the bodies of animals as they 
pass through the vegetation. They then proceed to burrow into the 
skin, setting up a most exasperating itching with the formation of 
reddened patches often covering considerable areas. This phase of 
the mite's parasitism is pecuhar in that it invariably perishes in the act 
of entering the skin. It is likely to be most troublesome during the late 
summer and autumn, the name Leptus autumnalis, under which the 
larval stage of the mite has been described, being derived from this fact. 

Man is most often attacked about the lower parts of the legs and upon 
the hands. Among domestic animals, those which frequent locations 
densely covered with vegetation are the most likely to suffer. Hunting 
dogs especially are exposed, and on returning from the field will often 
exhibit symptoms of great itching about the face, paws, inner thighs, 
and belly, the parts most often attacked. Horses will be affected prin- 
cipally below the knees and hocks. 

Treatment. — As the larval mites die upon entering the skin, the 
source of the irritation is soon eliminated and the intense itching will 
usually rapidly subside, leaving areas of epithelial exfoliation over the 
parts affected. Recently exposed animals will be relieved somewhat by 
frictions with a cloth sprinkled with benzene, or by the application of a 
mixture of equal parts of hme-water and hnseed oil, or sulphur ointment 
may be used. Sponging with a solution of carbolic acid at about three 
per cent, strength in water to which a little glycerin has been added, 
will do much toward reheving the itching. Ammonia-water, or a solu- 
tion of bicarbonate of soda are both of value for this purpose. 

Persons working or passing through infested districts will, in con- 
siderable degree at least, be protected from attack by applying a mix- 
ture of kerosene and glycerin to the hands and ankles. 



THE MITES 101 

Family III. Sarcoptid^ 

Mange, scab, or itch mites. Acarina (p. 94). — The body has the 
cephalothorax and abdomen fused ; it is white or reddish in color. The 
ciiticular surface is transversely striated and provided with bristles, 
sometimes with short dorsal spines. The mouth parts are beak-like, 
extending forward, and covered by the protruding labrum; chelicerae 
scissors-hke; maxillary palpi small and three-segmented. The legs are 
short and stout, have five segments, and are disposed in two groups of 
two pairs each, the anterior pairs, usually the larger and near the mouth 
parts, the posterior pairs near the abdomen. The tarsi commonly ter- 
minate in one or two booklets; they may temiinate in a long bristle or 
an ambulator}^ sucker, often upon a stalk which may be segmented. 
Respiratory organs are absent; respiration cutaneous. There are no 
eyes. All are scarcely visible without the aid of magnification. 

There are frequently well-marked sexual differences. ]Males are con- 
siderably smaller than the females. In some males the fourth pair of 
legs is very small, and there may be plate-like copulatory suckers at 
the base of the abdomen with abdominal prolongations. As to the 
presence or absence of bristles or stalked suckers, the tarsi ma}^ ter- 
minate differently in the two sexes. 

Development. — As already stated in the general reference to the 
Acarina, the Sarcoptidae have three distinct stages in the development of 
the male, four in the female. After sexual maturity and fertihzation of 
the female, the male usually dies. Following fertilization the female 
molts and enters upon her fourth or ovigerous stage, — the egg-bearing 
stage, recognizable by the presence of the genital pore upon the anterior 
ventral surface of the abdomen, through which the eggs are extruded. 

The rapidit\' with which these acari breed is very great. It has been 
estimated that one female sarcopt will produce in a subepidermic gallery 
about fifteen individuals, from which, after ninety days, there may be 
1,500,000 descendants constituting the sixth generation. 

The family includes a number of genera differing in their mode of 
attack and location upon the host. All are permanently parasitic. Of 
these, sLx, nameh" Sarcoptes, Psoroptes, Chorioptes, Notoedres, Cnem- 
idocoptes, and Otodectes are considered here. The characteristics and 
habits of the principal genera met with follow. 

Sarcoptes (Fig. 64). Sarcoptidae (p. 101). — The body is rounded or 
slighth' oval; the mouth parts short and about as broad as long. Upon 
the dorsal surface of the body are a number of cone-like prominences 
and twenty spines, the latter short, thick, and grouped as follows: four- 
teen upon the abdomen, seven to the right and seven to the left side; 
six upon the cephalothorax, three to the right and three to the left. 
The legs are thick and conical, the posterior pair being nearly or quite 



102 PARASITES OF THE DOMESTIC ANIMALS 

concealed beneath the abdominal margin when the acarus is in dorsal 
view. In the female the first two pairs of legs are terminated by stalked 
ambulatory suckers; the posterior pairs by bristles. In the male all 
of the legs are provided with stalked suckers but the third pair which 
terminates in bristles. The anus is located upon the posterior dorsal 
margin of the abdomen. Just anterior to this in the female is the copu- 
lating vagina (receptaculum seminis). Upon the ventral side at the 
median anterior border of the abdomen of the ovigerous female is the 
genital pore. The males have no copulatory suckers or abdominal ex- 
tensions. 

The Sarcoptes live upon man and practically all of the domestic 
mammals. In the latter animals they seek the parts of the body where 
the hair is short, while in man their preference is for places where the 
skin is thin, as about the kimckles, between the fingers, and in the bend 
of the elbows and knees. A peculiarity of their attack is the habit in 
the female of cutting tunnels beneath the epidermis, in the bottom of 
which she deposits her eggs (Fig. 65), a circumstance that renders this 
form of acariasis relatively difficult to cure. 

The Sarcoptes inhabiting the skin of various animals cannot be said 
t o exhibit differences of specific importance. They may, therefore, be 
placed in a single species — Sarcoptes scahiei — which may give rise to 
varieties according to host, as Sarcoptes scahiei, var. homi7iis of man, var. 
equi of the horse, and var. suis of swine, etc. The slight difference in 
these, as in other Sarcoptidae, is mainly one of size. 

Psoroptes (Figs. 68 and 69). Sarcoptida (p. 101).— The body is 
oval, the mouth parts elongated and in the form of a cone. The legs 
of the anterior pairs are thick, the posterior pairs more slender; all four 
pairs extend beyond the margin of the body. In the female the first 
two pairs of legs and the fourth pair are terminated by ambulatory 
suckers carried on long, three-segmented stalks, the third pair being 
terminated by bristles. The male has copulatory suckers serving for 
fixation to the female, and short posterior al^dominal prolongations 
terminated by bristles. The first three pairs of legs are terminated by 
stalked suckers; the fourth pair is stunted. 

Psoroptic scabies, the form produced by the members of this genus, 
is the most common and has been longest known. Unlike Sarcoptes, 
Psoroptes seek the parts of the body where the hair is long; they do not 
burrow beneath the epidermis, but attack the skin upon its surface, 
their punctures being followed by the formation of thick crusts. Under 
these they live in colonies which may coalesce and eventually cover 
areas of the bod}-- more or less circumscribed. Psoroptic scabies is most 
often observed upon animals with bodies covered wholly or in part by 
long hair, as the sheep, ox, and horse. 

As with Sarcoptes, the difference in host inhabited by Psoroptes 



THE MITES 103 

coincides with varieties which have unimportant and scarcely dis- 
tinguishable differences. There is, therefore, but one species, Psoroptes 
communis, designated according to host as variety ovis of the sheep, 
var. bovis of the ox, var. equi of the horse, var. cuniculi of the rabbit, 
etc. 

Chorioptes (Symbiotes; Dermatophagus) (Fig. 67). Sarcoptidae 
(p. 101). — The body is oval. The mouth parts are about as broad as 
long and somewhat dome-shaped. The legs are long and visible beyond 
the sides of the body. The ambulatory suckers are large and carried on 
short, unsegmented stalks. In the female all of the legs are terminated 
by suckers excepting the third pair, these are terminated by bristles. 
The male has copulatory suckers and abdominal prolongations ter- 
minated by leaf-like processes. The fourth pair of legs is stunted; all of 
the legs are provided with suckers. 

Chorioptic mites live, as do psoroptic, in colonies upon the skin where 
the hair is long and among the crusts which they form. There is one 
species, Chorioptes communis (Symbiotes communis, Chorioptes symbiotes, 
Dermatophagus communis). This infests the lower parts of the legs, 
especially of horses with long hairs upon the fetlocks, though in the ox 
this form of scabies generally has its seat at the base of the tail. 

Cnemidocoptes (Sarcoptes). SarcoptidiP (p. 101). — The body is 
rounded in outline. The mouth parts are short, broader than long, and 
rounded. In the female the legs are conical and very short; they are 
without suckers or bristles, terminating in two unequal booklets. In 
the male the legs are somewhat longer and all four pairs are terminated 
by stalked suckers and bristles. 

This genus contains a burrowing mite, Cnemidocoptes mutans (Fig. 74), 
which produces "scaly leg" in fowls; also a species known as the de- 
pluming mite, Cnemidocoptes gallince, which attacks the skin of fowls 
near the insertion of the feathers. 

Of the genera Notoedres (Fig. 71) and Otodectes, the former infests 
small mammals, and the latter lives in the external ear of the dog and 
cat. 

Family IV. Demodecid.e 

Acarina (p. 94). Follicular mange mites (Fig. 70). These are verj' 
minute and worm-like. The body is distinctly divided into cephalo- 
thorax and abdomen, the latter elongated and transversely striated. 
The anus is on the anterior ventral border of the abdomen, probably 
serving in the female for both, copulation and ovulation. The legs are 
three-segmented, short and stumpy. The mouth parts are suctorial. 
Respiration is cutaneous. There are no e.yes. The length is about 
0.3 mm. 

They undergo the same stages of development as other acari. 



104 



PARASITES OF THE DOMESTIC ANIIVIALS 



There is but one species, Demodex follicidorum (Fig. 70), which in- 
habits the hair folhcles and sebaceous glands of several manunalian 
species. Its size differs somewhat with its habitat, the difference in 
dimensions authorizing a division into varieties according to host. 

Scabies of the Horse 
Horses, asses, and mules are affected with 'one form of mange and two 
of true scabies, as follows : 

1. Sarcoptic mange, due to Sar copies scabiei var. equi. 

2. Psoroptic scabies, due to Psoroptes communis var. equi. 

3. Chorioptic scabies, due to Chorioptes communis var. equi. 
Sarcoptic Mange of the Horse. — In the majority of cases acariasis of 

the horse is caused by Sarcoptes (Fig. 64). It begins most frequently 




Fig. 64. — Sarcoptes scabiei var. equi, female; dorsal (left) and ventral 
(right) surface. 

about the head, sides of the neck, or at the withers, extending, if neg- 
lected, over large areas of the body, involving in some cases even the 
lower parts of the legs. In its initial stage sarcoptic mange is somewhat 
slow in development, the small number of acari at the beginning not 
giving rise to s\miptoms readily observable. In from three to six weeks, 
however, the multiplication of the parasites has sufficiently progressed 
to clearlj' reveal the affection. 

Symptoms. — The first sjanptom is itching, more or less intense, 
which the animal seeks to relieve by rubbing itself against anything 
available, or by biting affected parts of the body which it can reach. 



THE MITES 



105 



When groomed with the brush or currycomb it will manifest its pleasure 
by protrusion and movements of the upper lip, at the same time leaning 
toward the brush. This action is not peculiar to mange, however, as it 
may be observed in any itching skm affection of the horse. The pruritus 
seems to be greater at night and is always intensified by an increase in 
the warmth of the body, as hy a warm stable or warm clothing. This is 
probably due to the greater activity of the parasites under such condi- 
tions. 

Lesions.^ — The first changes in the skin will be the formation of 
small nodules, which ma}'- be felt by the hand as it is passed over the 
skin's surface. At these locations small crusts are formed about the 
tufts of 2natted hairs, which are easily removed, leaving a moist and 
reddened surface. From the nodules small papules develop, the epider- 
mis being raised by the subepidermic serous effusion. These rupture, 
and the desquamated surface gradually dries, leaving a scaly formation 
upon the skin. With the extension of these lesions the hair falls out in 
patches, the affected areas becoming confluent and covered by dry 




Fig. 65. — Burrow of sarcopt in human skin, with eggs and mite (after 
Osborn, from Furstenburg and Murry; Bureau of Entomology, U. S. Dept. 
of Agr.). 

epidermic scales and thin crusts. Soon following upon this stage the 
skin thickens and forms into folds, especially over the parts where it is 
freely movable, as about the throat, neck and breast. When these 
folds are separated the skin between them is found to be in a raw and 
purulent condition, bleeding at the slight touch of an instrument or 
of the finger nail. In neglected cases the body may become almost 
entirely denuded of hair and the thickened skin covered everywhere with 
crusts, bleeding fissures, and ulcers, the animal presenting a most 
miserable appearance (Fig. 66). The alterations m the skin are not all 
directly brought about bj' the parasites, being contributed to by the 
violent rubbing of the animal in its efforts to relieve the itchmg. Excoria- 
tions with the formation of hemorrhagic exudations and ulcers are often 
an accompaniment from this cause. 

Diagnosis and Development. — AVith these symptoms in their early 



106 



PARASITES OF THE DOMESTIC ANIMALS 



or late stages, the diagnosis of sarcoptic mange may be made positive 
by the recovery of the Sarcoptes. This should be looked for as soon as 
the presence of mange is suspected, as it is important to know with what 
form of the disease we have to deal. The nymphte and pubescent males 
and females live upon the body surface and among the crusts over all 
affected parts. Innnediately after they become impregnated the oviger- 
ous females burrow galleries beneath the epidermis in which they deposit 
their eggs and live for a time with the young larva? (Fig. 65) . In man the 
course of the galleries is marked by fine red lines from 8 to 15 mm. or 
more in length, but in the horse these cannot be seen owing to the 
thickness and pigmentation of the epidermis. The sarcopt is usually 
lodged at the extreme end of the channel in the course of which her eggs 




Fig. 66. — Colts affected with advanced sarcoptic mange (from author's i)hotograph) 



are distributed. It has been estimated that approximately fifteen in- 
dividuals will be produced in each of these subepidermic burrows, and 
that about fifteen days are required, under average conditions, for their 
full development and the appea^rance of the next succeeding generation. 
The larvae issuing from the eggs live in the gallery for some time before 
finally making their exit along its course, while the parent female soon 
dies after ovulation is completed. Copulation takes place upon the 
skin beneath the crusts, the males dying after the performance of this 
function. As the males are also relativeh^ less in number, it is the fe- 
males which are more often met with. 

To secure the parasite for examination the crusts should be removed 
and skin scrapings taken in such a manner as to include a portion of 
serous exudate with the epidermic scales. The material should be taken 
from a part showing evidences of recent attack, the mites being more 
hkely to be found there than in the older lesions. This material, to- 



THE MITES 107 

gether with a few flakes from the deeper portion of the crust, may then 
be placed upon a gkiss and teased in glycerin. After having been 
sufficiently divided and spread by the needles, it is ready for examination 
under the low power of the microscope, or by a strong hand lens. It is 
often necessary to thoroughly search several preparations before finding 
the acarus. The material can be more easily teased and cleaned up if 
submitted for an hour or two to the action of a five to ten per cent, 
solution of caustic soda. 

A method commonly used in the Laboratory of the Pennsylvania 
State Bureau of Animal Industry for the detection of scab acari is as 
follows: Cover the material with a ten per cent, solution of sodium 
hydrate and set aside for one or two hours. Heat to boiling and cen- 
trifuge for twenty minutes. The liquid is then carefully drawn off, 
water added, and the sediment shaken up. This is agam centrifuged, 
water drawn off, and fresh water added in which the sediment is again 
washed and centrifuged. The sediment is then thinly spread upon 
slides and examined under low power. By this treatment the scabs and 
crusts are thoroughly disintegrated. Some of the mites may also be 
fragmental, but not to such an extent as to prevent recognition of the 
species. 

Prognosis. — Owing to its great contagiousness and the difficulty in 
reaching the parasites, sarcoptic acariasis is the most serious of the 
three forms which may affect the horse. Early in its course the con- 
stantly tortured and unpresentable animal becomes unfit for work, and, 
when the disease is advanced, the skin lesions are accompanied bj^ 
anaemia, emaciation, and a general debility that may terminate in death. 
As in other parasitic skin diseases, vigorous animals in good condition 
are more resistant and are more easily cured than those unthrifty or old 
and emaciated. 

Transmission. — The transmission of mange from horse to horse or 
to asses and mules takes place by contact of individuals and by numerous 
ways in which the parasite can be transported, as by litter, grooming 
utensils, harness, clothing, or any object upon which the affected animal 
has rubbed. Its contagion is modified considerably in relation to the 
stage of the disease. Early in its course the acari have little tendenc}^ 
to leave their host, but after one or two generations, with the formation 
of the typical skin lesions, they emigrate readily, either directly or in- 
directly, from one animal to another. 

Mange of the horse can be transmitted to man and, reciprocally, 
that of man to the horse, though such cases are rare. In either event the 
parasite does not find a favorable soil for its multiplication, and the 
invasion is but transient, such affection as it produces usually yielding 
promptly to treatment or spontaneously disappearing in a few weeks. 
It is doubtful whether this mange can be commimicated to other animals; 



108 PARASITES OF THE DOMESTIC ANIMALS 

varieties of the sarcopt accidentally conveyed from their natural to a 
foreign species of host meet with an unfavorable habitat and, if cutaneous 
manifestations follow, it may be assumed that they must in any case be 
slight and of relatively short duration. 

Psoroptic Scabies of the Horse. — Psoroptic scabies generally appears 
about the regions of the longest hair, as at the base of the forelock, mane, 
and tail. It at once gives rise to pruritus, which is accompanied by 
rubbing and matting of the hairs as in mange, with which form it is 
somewhat similar as to its course and alterations. It spreads much 
more slowly, however, and rarely involves the whole surface of the 
body. 

The psoropt does not burrow beneath the skin's surface as does the 
sarcopt, therefore it can be more easily found. The methods recom- 
mended for securing the Sarcoptes will apply to the Psoroptes as well, 
though to obtain the latter it is not necessary to go quite as deeply for 
the material. In this connection it should be borne in mind that two 
or all three forms of scabies may coexist on the horse. It is advisable, 
therefore, in certain cases to look for the mite in material obtained from 
various affected regions of the body, as from the base of the mane, fore- 
lock, or tail, from the cheeks and breast, and from the lower parts of the 
legs. 

Lesions. — While the local alterations in psoroptic scabies are severe, 
the pruritus intense, and the scabs generally thicker than in the sarcop- 
tic form, it is a less serious affection in that the mites do not burrow, 
and the lesions remain much longer localized. More easily and promptly 
cured, it is not so frequently epizootic, and it is not as likely to spread to 
other horses upon the same premises. 

Transmission. — As to its transmissibility from the equine species to 
other animals, what has been said relative to this of the Sarcoptes 
applies also to the Psoroptes. 

Chorioptic Scabies of the Horse. — This form of scabies begins on 
the extremities, most often the hind feet about the fetlocks and pasterns. 
From here it spreads to the hocks, or to the knees if from the fore feet, 
sometimes extending further, but rarely as far as the bod}^ Like the 
psoroptes, these mites seek the parts covered by long hair, therefore 
horses with long fetlocks are predisposed to attack. 

Symptoms. — The first symptom of the invasion is itching, which 
the hoi'se manifests by stamping, kicking the side of the stall, efforts to 
bite the legs, or rubbing them one against the other. This irritation 
is especially noticeable upon the animal's return from work and at night 
in a warm stable. Its true caiise is frequently overlooked in considering 
it a vicious habit. 

Chorioptic scabies is slow in development, and is most troublesome in 
winter. This is probably due to the fact that the feet of horses at this 



THE MITES 



109 



time of the year are more exposed to mud and slush, bringing about a 
macerated and inflammator}^ condition of the skin that favors the 
multipHcation of the mites. 

Lesions. — Shortly after the invasion an abundant epidermic des- 
quamation is noticed among the hairs and over the skin. Tufts of 
hair are easily pulled out, and patches appear where the skin is bare and 
smooth. Later crusts form over a thickened and exudmg skin, which 
in the hollow of the pastern becomes fissured and bleeding. 

Diagnosis. — In view of the special seat of chorioptic scabies, other 
parts not bemg involved, it is scarcely nec- 
essary to confirm its differentiation from 
other forms by the recovery of the mite. It 
is important, however, to know whether 
the case is truly one of scabies, and this 
diagnosis can only be established with cer- 
tainty by findmg the parasite. If present 
it will be easih' found among the deeper 
parts of the crusts and epidermic scales. 

Prognosis and Transmission. — Foot 
scab is less infectious and is accompanied 
by less itching than the other forms. The 
prognosis is also more favorable, since, ex- 
ceptmg in rare cases, the disease is confined 
to the lower parts of the legs and usually 
to the hind legs onl}'. Again, unlike other 
scabies, it has little if any general effect 
upon the animal. It yields readily to suit- 
able treatment, and it is not hkely that 
horses recei\'ing proper care as to cleanli- 
ness of the hair and skin will be attacked, 
even though exposed to the infection. Its 
transmission from animal to animal in the 
same stable is usually bv bedding and 
grooming utensils in the hands of careless 
attendants. 




Fig. 67. — Chorioptes communis 
var. equi, female; ventral view. 



Scabies of the Sheep 



Sheep may be affected with the following forms of scabies, the first 
mentioned being by far the most important in this animal : 

1. Psoroptic scabies, due to Psoroptes communis, var. ovis. 

2. Sarcoptic mange, due to Sarcoptes scabiei, var. ovis. 

3. Chorioptic scabies, due to Chorioptes communis, var. ovis. 

4. Folhcular mange due to Demodex follicidorum, var. ovis. 
Psoroptic Scabies of Sheep. — Through its exten.sive prevalence 



no PARASITES OF THE DOMESTIC ANIMALS 

among sheep, psoroptic scabies may be regarded, from an economic 
standpoint, as the most important of all scabies affecting live stock. 
That the disease has been known for many centuries is evident through 
references to it in early writings, including the Bible. The relationship 
of the mite to the disease, however, was not determined with certainty 
until the nineteenth century, during the first half of which the complete 
life cycle of the parasite was demonstrated. It was shown that mites, 
like larger animals^ are the offspring of ancestors and are not of sponta- 
neous origin or accidental occurrence. It was further proven by animal 
experimentation that the mites were not present as a result of the scab, 
as had been supposed by some, but that the scab resulted from the 
presence of the mites and could be produced in no other way. 

The psoropt of sheep scab (Figs. 68 and 69) lives upon the surface of 
the body where it is most thickly covered with wool, as the back, sides, 
and shoulders. From their seat of invasion the colonies will spread and 
these areas may coalesce, involving large patches, though the regions of 
short wool, as the belly and front of the chest, are rarely attacked. 

Symptoms and Lesions. — The first indications of the disease are 
rubbing and gnawing at the wool and general unrest caused by the itch- 
ing. As the changes in the skin progress loosened tufts become raised 
over the surface of the fleece. These tags are soon rubbed or pulled 
away by the sheep, and the fleece over the affected parts becomes ragged 
and matted, the skin finally becoming more or less bare and showing 
at this stage a thickened, furrowed, and bleeding condition. 

If the skin is examined before the shedding of the wool there will be 
seen small yellowish nodules and papular elevations of the epidermis. 
The latter with their serous exudate dry up, forming an accumulation 
of fatty yellowish scales upon the skin and among the deeper parts of 
the hairs. The papules are closer together as the punctures of the psoropt 
become more numerous. As they become confluent the skin thickens, 
and the drying exudate and papular debris form a massive yellowish 
crust. This, as it increases layer by layer, envelopes and mats the 
wool, lifting the fibers from their follicles and raising large bunches 
above the surface of the fleece. These detached patches will soon fall 
away, the denuded skin showing a variation of lesions common to 
scabies. It will be thickened, cracked, and scabby, and there may be 
here and there excoriations, with perhaps sloughing and ulcerated areas. 
The acari forsake the more central and older lesions for the periphery 
of the denuded patch where they may be found in large numbers at 
the roots of the incrusted wool which in its turn will fall away. Due to 
direct exposure to the atmosphere, old denuded or sheared areas dry 
out and become uniformly covered with a dry parchment-like crust 
beneath which the skin is thickened and fissured. 

Course and Prognosis. — The course and termination of the disease 



THE :mites 



111 



will be influenced by age, condition, character of fleece, and the con- 
ditions under which the sheep are kept. Animals debilitated from age, 




Fig. 68.— PsoroiJt 
(right) surface. 



fpmalo; dorsal (left) and ventral 



or other cause, offer little resistance, while lambs, due to the tenderness 
of their skin and their dense fleece, are apt to be attacked more severely. 
Sheep with a close wool, as the pure or grade merino, afford an ideal 
habitation for the rapid multiplication of the parasites. The contagion 




Fig. 69. — Psoroptes communis var. ovis, male; dorsal (left) and 
ventral (right) surface. 

of any form of acariases in sheep is facilitated by their habit of living 
in flocks. The disease is, therefore, much more serious in winter when 
the animals are huddled together, especially making rapid progress if 



112 PARASITES OF THE DOMESTIC ANIMALS 

the quarters in which they are collected are damp and hot. In summer, 
after shearing and turning upon pasture, it rapidly subsides, in some 
cases even seeming to disappear. 

Psoroptic scabies in sheep, if unchecked, will have a fatal termination. 
Death is preceded by denudation of the greater part of the body, emacia- 
tion, anaemia, and a progressive weakness. The course is often rapid 
in stabled sheep and those predisposed; within one or two months it 
may have spread over the greater part of the body, while, on the other 
hand, the disease may last in a more or less severe form for a year or 
more. 

Transmission. — Sheep scab cannot be transmitted to other animals, 
nor can psoroptic scabies of other animals be transmitted to sheep. 

Sarcoptic Mange of Sheep. — Sheep are rarely affected with this 
form. When it occurs it can at once be distinguished from psoroptic 
scab by its location, which is exclusively upon parts of the body covered 
with short hair. It usually has its beginning about the upper lip or 
nostrils, extending from here to other parts of the face and to the eye- 
lids and ears. In cases of long standing it may spread to the belly and 
inner sides of the front and hind legs. 

Prognosis. — The course of the disease with its typical skin altera- 
tions has already been described under Sarcoptic Mange of the horse. 
It is much less serious in sheep than in the horse, however, and if taken 
before it has spread extensively, yields easily to treatment. 

Transmission. — Sheep and goats transmit sarcoptic mange recipro- 
cally. It has been reported as having been conveyed from these animals 
to man, but such cases, if ever occurring authentically, should be ex- 
tremely rare. 

Chorioptic Scabies of Sheep. — As in the horse, chorioptic scabies of 
the sheep begins in the hind fetlocks and pasterns where it is charac- 
terized by a redness of the skin and the presence of fine epidermic scales. 
There is considerable itching, causing the animals to stamp their feet 
and bite at the infected parts. Later yellowish crusts appear which 
thicken, and the skin becomes cracked and bleeding, especially about 
the folds of the pastern. Only rarely does the affection pass to the fore 
legs or upward to the udder in the ewe, or to the scrotum in the ram. 

Prognosis and Transmission. — Again, as in the horse, the Chorioptes 
are not inclined to migrate, and the scabies they produce is but sHghtly 
contagious. It yields promptly to cleanliness and proper treatment, 
subsiding almost entirely when the flock is turned upon grass in the 
spring. 

Follicular Mange of Sheep. — -The follicular mite occasionally in- 
vades the eyelids of sheep. Few such cases have been recorded, however, 
and, in this country at least, follicular mange is of little importance to 
flock owners. 



THE MITES 113 

Scabies of the Goat 

Goats may l^e affected by three forms of scabies, — sarcoptic, psoroptic, 
and chorioptic. The first mentioned is the most frequenth' met with in 
these animals, having its seat, as in sheep, mainly about the face. The 
other forms are rarely met with in goats. Psoroptic scabies attacks the 
external ear, forming dark-colored, fungus-Uke scabs. Chorioptic scabies 
is said to have its beginning on the sides of the neck and withers and 
along the back. 

Scabies of Cattle 

Three forms of scabies affect cattle. These are as follows: 

1. Psoroptic scabies, due to Psoroptes communis, var. botis. 

2. Chorioptic scabies, due to Chorioptes communis, var. boms. 

3. Sarcoptic mange, due to Sarcoptes scabiei, var. boiis. 

Scabies is less frequent in cattle than in horses and sheep, in North 
America being most often met with in the range herds of the West and 
Northwest. In this country the psoroptic is probably the most fre- 
cjuent form. 

Psoroptic Scabies of Cattle. — This usually has its l)eginning upon 
the sides of the neck and shoulders, at the base of the horns, or it ma\' 
be at the root of the tail. From these points it usually advances along 
the back, passing to the sides, and in severe cases eventually involving 
the greater part of the body. In its s^^nptoms, course, and skin altera- 
tions it is in all essential respects analogous to the same form of scabies 
in the horse. The pruritus is intense, the animal rubbing and scratching 
itself in every way possible, often causing Ijloody excoriations of the 
skin. As the disease advances an extreme cachexia sets in, and the 
anaemic and much weakened animal may die in a most miserable con- 
dition. 

Such cases are most likely to occur al^out the close of the winter 
months, especially in cattle stabled or herded together in wami quarters. 
While upon grass, though the infection may remain, its symptoms sub- 
side, and in the falling away of the scabs with renewal of the coat, may 
even seem to have entirely disappeared. 

Calves, yearlings, and two-year-olds suffer most, and it is among 
these that there is more likely to be a fatal termination. 

Chorioptic Scabies of Cattle, — This form in cattle is commonh- 
known as tail mange. It generally appears in the depressions at the 
base of the tail where as a rule it remains localized. If neglected it may 
spread to the loins, perineum, and inner surface of the thighs, or even 
over a considerable surface of the body, though such cases are rare. It 
is exceptional for mange to appear in the feet of cattle. 

Its course is the usual one of chorioptic scabies. The itching is mod- 



114 PARASITES OF THE DOMESTIC ANIMALS 

erate, and the skin becomes covered with fine, dry scales, later becoming 
denuded, fissured, and scabby. 

It is but slightly contagious and, except in cases of extreme neglect, 
has little tendency to spread upon the body. Where it seems to progress 
beyond the limits usual to the choriopt, it should be determined whether 
or not psoroptic scabies is coexisting with it — a condition which is 
quite possible. If this is suspected, material from several affected 
locations should be examined for recognition of the infecting species. 

Sarcoptic Mange of Cattle. — Mange of the ox due to Sarcoptes need 
be no more than mentioned here. Probably in every case where it has 
occurred it has been by transmission from animals more likely to har- 
bor this species, as the horse or goat. In bovine animals the disease is 
usually of short duration, showing less tendency to spread and yielding 
more promptly to treatment than in the horse. It affects chiefly the 
skin about the eyes and cheeks and may extend to the sides of the 
neck. 

Mange of the Hog 

Two kinds of mange affect the hog. These are as follows : 

1. Sarcoptic mange, due to Sarcoptes scabiei var. suis. 

2. Follicular mange, due to Demodex folliculorum var. suis. 
Sarcoptic Mange of the Hog. — Sarcoptic mange is considered to be 

the most common form in these animals. The infecting sarcopt is the 
largest variety of the species and may be seen with the unaided eye as a 
minute moving speck among the removed cutaneous debris. 

Symptoms. — The presence of the disease is first shown upon the 
skin about the eyes and ears, from which points it spreads to the back 
of the neck, withers, shoulders, and back, later, if unchecked, invading 
the greater surface of the body. The pruritus is extremely severe and is 
especially aggravated in animals subjected to the body heat of crowded 
pens. With the extension of the itching nodules the bristles fall out, 
and the skin becomes wrinkled and covered with brownish or dark 
gray crusts. Within the folds the skin presents the morbid changes 
usual to sarcoptic mange; it is fissured and bleeding and there may be 
ulcerations. 

Young pigs and those with a thick curly growth of hair suffer the 
most. The condition j-etards development and fattening, and severe 
cases may lead to general debility and death. 

Transmission. — Contagion is by contact of the animals with each 
other, essentially facilitated when crowded together in pens or lots. 
Because of the habit these animals have of rubbing their bodies, ob- 
jects upon which infected hogs have scratched are especially a source of 
transmission. 

This mange of the hog may be transmitted to man and to the dog and 



THE MITES 115 

possibly also to the horse, but the eruption produced iu such cases dis- 
appears spontaneously in a few days. 

Follicular Mange of the Hog. — Demodex being more difficult to 
recognize, its j^resence in the skin of pigs probably occurs more often 
than is generally supposed. The skin alterations which the follicular 
mites bring about in these animals is comparativeh' slight and, as a rule, 
are not such as to perceptibly interfere with general health or growth. 
The primary seat of invasion is usually the skin about the snout. The 
lesions may extend to the cheeks and even to the neck and chest, though 
such spreading of follicular mange in the pig is not often observed. 

Maxge of the Dog 

There are three forms of canine mange, as follows: 

1. Sarcoptic mange, due to Sarcoptes scahiei var. canis. 

2. Follicular mange, due to Demodex folliculorum var. canis. 

3. Auricular mange, due to Otodectes cynotis. 

Sarcoptic Mange of the Dog. — Sarcoptic is considered the most 
conmion mange affecting the dog. Though it may first appear upon 
any part of the body, it generally begins about the nmzzle, especially 
upon the bridge of the nose or, not infrequently, around the eyes, at the 
base of the ears, or upon the breast. As it spreads the ventral surface, 
axilla, and thighs become involved, the morbid process extending with 
such rapidity that by the end of a month it may cover the greater part 
of the body. 

Symptoms, Course, and Lesions. — In its symptoms, course, and 
alterations sarcoptic mange of the dog is shnilar to that of the horse. 
It is first manifested upon thin and unpigmented skin by little red points 
which are soon converted into papules. These rapidly increase in num- 
ber and, as they rupture and exude their serous contents, deposit a 
scaly accumulation upon the skin followed by the formation of yellowish 
gray crusts. As the disease progresses the denuded skin becomes 
thickened, wrinkled, and excoriated, the cheeks, neck, and breast 
especially exhibiting deep folds. The itching, always intense, is much 
aggravated by an increase in the ])ody tempei-ature, as may be brought 
about b}' running or warm quarters. 

Where large areas of the body are involved in the disease, emaciation 
and genei-al debility set in, the animal at times giving off an offensive, 
mouse-like odor. Finally, if the animal is neglected or treatment is 
unsuccessful, death will ensue by the end of two or three months from 
the beginning of the invasion. 

Transmission. — The facts of contagion pertaining to sarcoptic mange 
of other animals apply to this disease of the dog as well. Young dogs 
and those debilitated are predisposed to infection, though dogs of any 
age or condition will supj^ort the sarcopt and readily develop the disease. 



116 



PARASITES OF THE DOMESTIC ANIMALS 



Follicular Mange of the Dog. — Demodectio mange, or the so-called 
red mange of dogs, is of frequent and world-wide occurrence. The 
lanciform mites enter the orifice of the hair follicle where they multiply 
and occupy the follicle and sebaceous gland in large numbers, lying 
closely pressed together and almost invariably with the mouth parts 
directed toward the bottom of the folHcle (Fig. 70). In this location 
they may be found in all stages of development, from eggs to sexually 
mature individuals and ovigerous females. As a result of this con- 
stant increase there is a dilation of the hair follicle and gland, the pres- 
sure and irritation producing degenerative 
changes in the lining epithelium of the 
follicle and hair papilla which causes the 
hair bulb to become loosened from its 
attachment. 

Symptoms and Course. — The degree of 
irritation and extension of the -inflamma- 
tory process to the surrounding tissue will 
be influenced by the number and activity 
of the mites. There may be no more man- 
ifestation of their presence than a hyper- 
secretion of sebaceous material. Where, on 
the other hand, these causative factors are 
sufficient to produce an acute inflammation 
involving the surrounding derma, there 
will be a dilation of the contained blood 
vessels with increased formation of epi- 
dermic cells. Increased desquamation of 
the surface cells follows, and later there is 
an invasion of pyogenic organisms into the 
inflamed and dilated follicles, resulting in 
the formation of pustules and in some cases large abscesses. 

Though follicular mange, owing to its resistance to treatment and 
general septic intoxication, frequently terminates in death, its course 
at the commencement is very slow. In its early manifestations there are 
merely somewhat reddened areas, usually of the skin about the eyes, 
breast, elbows, or it may be at the toes. As the hairs fall away small 
papules are observed, and the affected patches become covered with 
fine, powder-like scales. The infection is extended by the mites aban- 
doning the originally invaded follicles and entering the surrounding 
healthy ones, the spreading being aided somewhat by the rubbing and 
licking of the animal. As new parts are invaded the skin becomes de- 
cidedly red and, especially about the cheeks and breast, thickened, 
wrinkled, and crusty; the eyelids are swollen and covered at their borders 
by a purulent discharge. 




m 



Fig. 70. — Demodex folliculo- 
rum: a, mite greatly enlarged; b, 
mites in hair follicle and seba- 
ceous gland — enlarged (after Os- 
born, from Murry, Bui. No. 5, 
Bureau of Entomology, U. S. 
Dept. of Agr.). 



THE MITES 117 

The disease finally becomes generalized, the skin everywhere ex- 
hibiting the lesions in their various stages, and, with it all, exhaling a 
disgusting odor. The pruritus increases, though it remains somewhat 
intermittent, and at no time is as severe as in sarcoptic mange. With 
the generalization of the malady its effect upon the whole animal or- 
ganism is well estal)lished. The appetite is lost and emaciation ad- 
vances, the subsequent marasmus leading to a fatal termination. 

Transmission. — Due to the intra-cutaneous location of the parasites, 
follicular mange is not as contagious as other forms; furthermore a pre- 
disposition is necessary for its development, and this is fomid in young 
and short-haired animals. Adult dogs with healthy skins are rarely 
attacked. 

Whether the dermatitis in follicular mange is primarily due to the 
presence of the Demodex may be questioned. The assumption that this 
mite is present in the hair follicles of all dogs needs the support of 
further investigation. Accepting it from clinical observation as a proba- 
bility — and with the predisposing factors of other forms of acariasis in 
mind — there seems good reason to suppose that the mites, living, we 
may say, as commensals, find in erythematous and eczematous skins 
surroundings favoring their nutrition and more rapid multiplication, 
thus bringing about the secondary severe dermatitis of follicular mange, 
the pyodermatitis resulting from subsequent intra-follicular invasion 
by pyogenic organisms. 

Auricular Mange of the Dog. — Otacariasis is of comparatively fre- 
quent occurrence in dogs, by reason of its contagiousness, being most 
often met with in hounds kept in packs. Symptoms of the presence of 
the mites are frequent scratching and flapping of the ears, which may 
be accompanied by whining and howling. Epileptiform seizures are 
not infrequently an accompaniment, these especially likelj' to occur 
when the animal is running. On examination the auditory canal is 
found to contain an adherent, soot-colored powder and a fetid wax 
which may be in sufficient abundance to produce deafness by obstruc- 
tion of the canal and pressure upon the t^nnpanum. An examination of 
this material mider magnification will reveal the Otodectes in large 
numbers. 

Prognosis. — Otacariasis yields readily to treatment, but if neglected 
may have serious consequences. The animal may die during an attack 
of con\'T.i]sions or, if it survive, be rendered useless as a hunter. 

Mange of the Cat 

The cat may be affected with the two following forms of mange : 

1. Notoedric mange, due to Notoedres cati var. cali. 

2. Auricular mange, due to Otodectes cynotis. 



118 



PARASITES OF THE DOMESTIC ANI]\L\LS 



Notoedres cati, var. cati (Sarcoptes minor var. cati, Fig. 71), the 

dwarf sarcopt, is a small species having the body nearly spherical. The 

dorsal folds of the integument are circular. The anus is dorsal. There 

are six anterior dorsal spinules and but twelve 

^ r 1 posterior. The arrangement of the stalked 

u \ j^ suckers is the same as in Sarcoptes scabiei. 

^ «|b^^ A<^ Course and Diagnosis. — Notoedric mange 

/^d^^^Hkfi^ of the cat usuall}^ begins about the ears and 

^^^^^^^^^ upper part of the neck, extending over the 

^^^^^^^^H forehead and then over the head generally. 

^^^^^^^^H As a rule it remains limited to these regions, 

^^^^^^^^^V"^ rarely passing to the body. The disease fol- 

y^^^H^^^^ lows the usual course and alterations of sar- 

f^^Ktl^^ \ Coptic mange, the cat giving evidence of the 

I / \ \ intense itching by frequently shaking the head 

/ \ \ and wiping it with its paws. In neglected 

I cases animals may become much emaciated 

Fig. 71.— Genus Notoedres. and may die in a few months. 

Due to the wrinkled, papular, and crusty 
skin and its persistency of location upon the head, the diagnosis of 
this mange on the cat is not difficult. Its differentiation from other 
itching skm diseases may be made certam by the discovery of the para- 
site, which is readily obtained in 
material scraped from beneath the 
crusts. 

Auricular Mange of the Cat. — 
Auricular mange seldom occurs in 
the cat. It is caused by the same 
species of mite causing auricular 
mange of the dog and is similar in 
its symptoms and course. 

Scabies of the Rabbit 

Two species of scab mites afflict 

the rabbit, — Notoedres cati var. cuni- fig. 72.— Psoroptes communis var. 

■culi and Psoroptes communis var. cunicuii (from photomicrograph of 

.CUnicidi (Fig. 72), the latter CaUS- counted specimen, by Hoedt). 

ing auricular scabies or psoroptic otacariasis. 

In the rabbit notoedric mange most often has its beginning about the 
nose, from which it extends to the upper part and sides of the head where 
it remains localized. Its location, symptoms, and course are similar to 
those of the same form of mange in the cat. 

Auricular scabies of the rabbit commences deep in the concha, grad- 
ualty involving the skin of the entire inner side. Its presence is first 




THE MITES 119 

indicated by the pruritus which the animal indicates by tossing its head 
and scratching the ears with the hind feet. If the deeper parts of the 
ear are examined early in thfe disease there will be found a yellowish, 
fetid matter in which many of the mites may be seen with the aid of a 
hand lens. At the end of a few months the greater part of the inner 
side of the ear becomes covered with a thick layer of scabs in which the 
Psoroptes are literally swarming. Usually they remain localized to the 
ear, rarely invading surrounding parts. 

In prolonged cases of auricular scabies rabbits lose their appetites 
and become emaciated, diarrhea sets in, and the animals finally die in 
an advanced state of cachexia. 



CHAPTER XI 

TREATMENT OF MANGE AND SCABIES 

General Considerations. — Methods of treatment of scabies will vary 
according to the form of the disease to be dealt with and also according 
to the kind and number of animals to be treated. As a general rule the 
application of acaricides should be preceded by clipping the hair from 
either a part or the whole of the body, dependmg upon whether the 
affection is localized or general. The crusts should then be softened and 
removed by washing with warm soapsuds and a stiff brush, after which 
the remedy chosen may be applied. 

The whole process is to be repeated in ten to fourteen days in order to 
destroy mites from eggs which escaped the first treatment. It is im- 
portant that there should be clean surroundings and, especially where 
emaciation is an accompaniment, an abundance of nutritious food. 
Sarcoptic mange will require more energetic remedies than other 
forms where the mites live upon the surface and among the crusts of 
the skin. 

Internal medication is of little or no value. A cure can only be reached 
by the destruction of the acari, accomplished by the local application of a 
suitable acaricide. In the use of such agents their irritant or possible 
toxic effects upon the animal treated are to be borne in mmd. To avoid 
a sudden and general checking of the cutaneous functions, oiatments 
and oleaginous materials are not to be spread over the entire body at 
one application, nor should the body be dressed over more than one- 
fourth to one-half of its area with preparations containing carbolic acid, 
creosote, cresol, tobacco, or other such ingredients. Those containing 
mercury or arsenic, in addition to these limitations, should never be 
used upon animals such as cattle, dogs, and cats as these animals will 
lick the dressed parts. 

Where large numbers of animals are affected in a flock or herd, in- 
dividual treatment involvmg clipping, scrubbing, and the application 
of remedies by hand, is not practicable. In such cases a method of 
dippmg must be resorted to. It is essential to the success of the treat- 
ment that thorough disinfection measures be applied to surroundings 
and to such portable paraphernalia as may serve as a means of reinfec- 
tion. In this connection it should be borne in mind that the mites may 
live from two weeks to a month or more ofT a host, the longer periods 
usually amid favorable conditions, such as warm stables and blankets. 



TREATMENT OF MANGE AND SCABIES 121 

The treatments given l^elow deal successiveh' with the chfferent forms 
of the disease and embody such modifications as may be required for 
the various domestic mammals. 

Treatment of Sarcoptic ^Iaxge 

Treatment of Sarcoptic Mange of the Horse. — Affected animals 
should be isolated in quarters where they will not be in contact with 
each other. Unless the disease is distinctly localized it is better to clip 
the hair from the entire body; its removal will often reveal the lesions 
over areas otherwise unsuspected. The clipping is not to be done in 
the stable or in a wind that will scatter the hairs about. All of the 
hairs should be carefully collected and burned. 

The next procedure is the removal of the crusts in order that the 
remedy- used may be applied directly to the skin. This is best accom- 
plished by the use of soft soap well rubbed upon the scabby surface. A 
thick lather is then formed by the application of a limited quantity of 
warm water. This should be well worked into the crusts with a brush 
and allowed to remain for an hour. The softened crusts may then be 
removed with a brush or, better, a wooden scraper and warm soapy 
water, and the body finally rinsed with clear tepid water applied with a 
sponge. The scraping process should be done gently and in a manner 
that will add as little irritation as possible to an already inflamed 
skin. After the skin has Ijecome perfectly dry it is ready for the remedy 
which is to be applied with a view to the destruction of the parasites. 

There are a number of such remedies in the use of which practitioners 
have had a varied experience. Creosote is among the most effectual. 
It may be used in any of the following combinations: (1) Creosote one 
part, oil sixteen to twenty parts; (2) creosote one part, oil of tar and soft 
soap of each ten parts; (3) creosote five parts, alcohol five parts, water 
twenty parts. With either of these not more than half of the body 
should be dressed at alternate periods of six days until the entire body 
has had two or three applications. It should be applied by rubbing. 

Other remedies which have given satisfactory results are: (1) Lime 
and sulphur dip (Formula No. 1, page 125), two or three applications at 
intervals of one week; (2) creolin and soft soap, of each one part, alcohol 
eight parts. Rub upon one side of the body on alternate days; after the 
body has had three applications rest three days and repeat ; (3) decoction 
of tobacco five per cent. Apply over one-fourth to one-third of the body 
each da^-; repeat three or four times at intervals of one week. 

Unctuous and oily preparations are to be preferred to the more fluid 
ones as they are more penetrating and, adhering to the skin, their action 
is prolonged. For this reason they are especially better suited for the 
treatment of sarcoptic mange. The lime and sulphur preparation is, 



122 PARASITES OF THE DOMESTIC ANIMALS 

however, much used and is said to give excellent results. Cure will 
not be complete until all of the mites have been destroyed. Animals 
should therefore be kept under careful observation for some time after 
treatment for the detection of suspicious sjanptoms, such as itching. 
Such cases may be checked at their inception by less drastic measures 
than at first employed. Often a few applications of mercurial ointment, 
or equal parts of oil and oil of tar containing ten per cent, of carbolic 
acid, rubbed over the limited area, will be sufficient. 

To prevent the reappearance of the disease it is obviously essential 
that harness, clothing, groommg utensils, and all other articles which 
may act as vehicles for reinfection, be disinfected. This is best done 
with boiling water. Articles which might be injured by this treatment 
may be washed with a strong solution (ten per cent.) of lysol or creolin. 

Treatment for mange given at the close of the winter months should 
be repeated in the fall, even though the disease has been apparently 
cured. This is a precautionary measure to destroy the few mites which 
may have survived upon the animal during the summer, and which 
may again produce the disease under the more favorable conditions for 
their reproduction which prevail during the fall and winter months. 

Treatment of Sarcoptic Mange of the Hog. — Where but few animals 
are to be treated they should first be thoroughly cleaned by scrubbing 
with soap and warm water and the skin rinsed and dried. 

The following ointments have been recommended for application 
to the skin after it has been thus prepared: (1) Sublimed sulphur two 
parts, potassium carbonate one part, lard eight parts (Helmerich's 
pomade); (2) creosote one part, lard twenty-five parts; (3) sulphur ten 
parts, lard thirty parts. These applications are to be repeated three 
times at intervals of about five days. 

Such methods, however, are out of the question where a large number 
of animals is involved. In such cases dipping in a liquid preparation 
is the only practical form of treatment. For this purpose the following 
lime and sulphur formula is recommended by the United States Bureau 
of Animal Industry: 

Flowers of sulphur 24 lbs. 

Unslaked hme 10 lbs. 

Water 100 gals. 

Prepare as under lime and sulphur formulae for scab in sheep (page 
125). 

The hogs should be kept away from wallows for several days before 
and after dipping. Each animal should be kept in the dip long enough 
for the liquid to be well rubbed into the skin with a stiff brush, care being 
taken that all parts of the body, including the head and ears, are reached 
by the remedy. Animals should not be dipped in cold weather. 



TREATMENT OF MANGE AND SCABIES 123 

Essentially, pens and yards must be cleaned up and all litter burned. 

Treatment of Sarcoptic Mange of the Dog. — Dogs should be clipped 
and the skin covered with a thick lather. A good apphcation for this 
purpose is green soap dissolved in an equal quantity of alcohol. Let 
this remain two to four hours, then remove the crusts with a brush and 
warm soapy water. Rinse and allow the skin to become dry. One of 
the following remedies may then be applied: (1) Creosote one part, oil 
fifteen to twenty parts; (2) creosote one part, green soap and alcohol of 
each eight parts; (3) subhmed sulphur two parts, potassium carbonate 
one part, lard eight parts (Helmerich's pomade); (4) creolm one part, 
alcohol fifteen parts; (5) Peruvian balsam two parts, creolin one part, 
alcohol twenty parts; (6) naphthalin two parts, vaseline eight parts, 
oil of th\ane and oil of lavender of each one part. 

The last named mixture is soothmg to the skin, agreeable, and quite 
suitable for small house dogs. It is not to be depended upon, however, 
in old and generalized cases. To avoid a too generally irritant or toxic 
effect the acaricide should be applied to not more than one-fourth to 
one-third of the bodj^ each da^^ It should be applied freely and energet- 
ically and left on for three or four days. It may then be washed off 
with tepid soapy water. At the end of three or four days the application 
is to be repeated m the same manner, and again repeated until there is 
no further itching or formation of scabs. The animal should be pre- 
vented from licking by fitting it with a broad collar or by binding the 
mouth with tape. 

Preparations of tar had better not be used upon dogs. Remedies con- 
taining carbolic acid, mercurj", tobacco, and other poisons are also to be 
avoided, as any measure adopted to prevent licking is liable to be de- 
feated by the dog and a serious poisoning result. 

The usual precautions as to cleaning up of surroundings should of 
course be adopted here. 

Treatment of Notoedric Mange of the Cat. — Cats rebel against and 
actually suffer from washmg, therefore treatment of these animals is 
limited to the use of ointments. The hair should be clipped from the 
affected parts and a small amount of vaseline applied which may be 
removed in an hour or two by rubbing with dry bran and a cloth, re- 
moving in this operation as many of the crusts as possible. 

The acaricide ointment best adapted to the cat is that of Helmerich, 
consisting of sublimed sulphur two parts, potassium carbonate one part, 
lard eight parts. The application of this is to be repeated at intervals 
of four to six days until scab formation and itching have ceased. It 
may be removed by rubbing in the manner already stated. Peruvian 
balsam is perhaps more effective, but in cats may cause severe cerebral 
disturbance followed by stupor and even death. If used at all it should 
be with extreme caution. 



124 PARASITES OF THE DOMESTIC ANIMALS 

Due to the usual location of notoedric mange of the cat upon the 
head, the dressing is inaccessible to licking, though the pads of the feet 
are likely to be applied to it and afterward licked. It is scarcely neces- 
sary to say that preparations containing tobacco, carbolic acid, and 
other poisons should be strictly avoided in the treatment of cats. 

Treatment of Notoedric Mange of the Rabbit. — Remove the hair 
from the affected area and for a considerable margin around it, apply a 
lather of soft or green soap, allow to remain an hour or two, wash off, 
and repeat as necessary to remove scabs. When the parts have be- 
come dry, treat with the ointment of Helmerich as for mange of 
the cat. 

Treatment of Sarcoptic Mange of the Goat. — Clip the hair and 
prepare the parts with soapy lather as directed for other animals. Treat 
with a sulphur ointment or a preparation of creosote, as creosote one 
part, oil fifteen parts. Repeat as previously directed. 

Owing to the intractability of goats, dipping is attended with difficul- 
ties and, furthermore, is badly borne b}^ these animals. 

Treatment of Sarcoptic Mange of Sheep. — Remove crusts after 
softening with a lather of soft or green soap, dry, and apply (1) creosote 
one part, oil of tar and soft soap of each twenty parts; (2) sublimed sul- 
phur one part, lard four parts, or (3) the ointment of Helmerich may be 
used. Repeat as directed for other animals. 

Treatment of Sarcoptic Mange of Cattle. — After clipping and prep- 
paration of the skin by removal of the crusts as has been repeatedly 
stated, apply the lime and sulphur mixture as given and prepared under 
scab of sheep, repeating three or four times at intervals of five days. 
Good results may also be obtained by the use of sulphur in the form of 
an ointment, as one part of sulphur to four parts of hog's lard. Prepara- 
tions containing such agents as creosote, lysol, or creolin are best limited 
to cases confined to the head and upper parts of the neck, regions in- 
accessible to the tongue. They may be used in the following combina- 
tions: (1) Creosote one part, oil fifteen parts; (2) creosote one part, 
oil of tar and soft soap of each fifteen to twenty parts; (3) creolin and 
soft soap of each one part, alcohol eight parts; (4) lysol in five per cent, 
solution. 

All of these are to be washed off with soapy water after three days 
and the treatment repeated as necessary. 

Treatment of Psoroptic Scabies 

Treatment of Psoroptic Scabies of the Sheep. — Proper hygienic 
conditions and an abundance of substantial nourishment will do much 
to protect sheep from the contagion of scab, but where it has made its 
appearance in a flock such measures are only to be relied upon as con- 



TREATMENT OF MANGE AND SCABIES 125 

tributing to a rational treatment designed to rid the sheep of the disease 
by killing the parasites. The application l)y hand of either ointments, 
fluid preparations, or powders for this purpose is practically useless. 
The acaricide chosen for the treatment of psoroptic scabies of sheep 
should be applied by dipping. It is better not to consume time, energy, 
and patience upon remedies which are not or cannot be used by this 
method. 

Lime and Sulphur Dip. — Many formulae for dips have been pub- 
lished, most of them containing lime, sulphur, tobacco, or arsenic as 
their base. The term "lime-and-sulphur dip" does not refer to an 
exact formula but includes a large number of formulae containing the 
lime and sulphur in different proportions. While the ingrediants of a 
dip should be in such proportion as to make it a reliable parasiticide, it 
is essential that it should cause little or no harm to the sheep or fleece. 
The subject of dips has been carefully gone into by the United States 
Bureau of Animal Industry and the conclusion reached that probably 
the most effective dips are those containing sulphur and tobacco, and 
sulphur and lime of such strength that they are not injinious to the sheep 
and of minimum damage to the fleece. Among the formulse for lime and 
sulphur dips mentioned bv the Bureau are the following (Farmer's 
Bull. No. 159) : 

No. 1 

Flowers of sulphur 24 lbs. 

Unslaked lime 8 lbs. 

Water 100 gals.. 

No. 2 

Flowers of sulphur 33 lbs. 

Unslaked lime 11 lbs. 

Water 100 gals. 

For fresh scab, formula No. 1 will act as well as those with a greater 
amount of lime. In old cases with parchment-like scab a stronger dip, 
as formula No. 2, is to be preferred. 

The following method of preparing the mixture is recommended l)y 
the Bureau: 

"A. Take eight to eleven pounds of unslaked lime, place it in a mortor 
box, kettle, or pail of some kind, and add enough water to slake the lime 
and form a 'lime paste' or 'lime putty.' 

"Many persons prefer to slake the lime to a powder, which is to l)e 
sifted and mixed with sifted sulphur. One pint of water will slake three 
pounds of lime, if the slaking is performed slowly and carefully. As a 
rule, however, it is necessary to use more water. This method takes 
more time and requires more work than the one given above, and does 



126 PARASITES OF THE DOMESTIC ANIMALS 

not give any better results. If the boiled solution is allowed to settle, the 
ooze will be equally as safe. 

"B. Sift into the lime paste three times as many pounds of Flowers 
of sulphur as used of lime, and stir the mixture well. 

"Be sure to weigh both the lime and sulphur. Do not trust to measur- 
ing them in a bucket or guessing at the weight. 

"C. Place the sulphur-lime paste in a kettle or boiler with about 
twenty-five to thirty gallons of boiling water, and boil the mixture for 
two hours at least, stirring the liquid and sediment. The boiling should 
be continued until the sulphur disappears, or almost disappears, from 
the surface, the solution is then of a chocolate or liver color. The longer 
the solution boils the more the sulphur is dissolved, and the less caustic 
the ooze becomes. Most writers advise boiling from thirty to forty 
minutes, but the Bureau obtains a much better ooze by boiling from 
two to three hours, adding water when necessary. 

"D. Pour the mixture and sediment into a tub or barrel placed 
near the dipping vat and provided with a bung hole about four inches 
from the bottom, and allow ample time (two to three hours, or more if 
necessary) to settle. 

"The use of some sort of a settling tank provided with a bung hole 
is an absolute necessity, unless the boiler is so arranged that it may be 
used both for boiling and settling. An ordinary kerosene oil barrel 
will answer very well as a small settling tank. . To insert a spigot about 
three to four inches from the bottom is an easy matter. Draining off 
the liquid through a spigot has the great advantage over dipping it out, 
in that less commotion occurs in the liquid, which therefore remains 
freer from sediment. 

"E. When fully settled, draw off the clear liquid into the dipping 
vat and add enough water to make 100 gallons. The sediment in the 
barrel may then be mixed with water and used as a disinfectant, but 
under no drcumstances should it be used for dipping purposes." 

There are a number of good proprietary dips upon the market which 
will l)e found convenient and effectual. No dip should be used, however, 
unless the ingredients and their exact proportion are known to the user. 
Secret formulse put out by irresponsible parties should be avoided. 

Dipping Vats. — Where but few sheep are to be treated the dipping 
arrangements may be quite simple. A tub or trough to which a draining 
platform is attached will serve the purpose. A small vat, suitable for 
dipping small flocks, may be constructed of wood or concrete. It should 
be about nine inches wide at the bottom, four feet deep, and two feet 
six inches wide at the top. Its length will depend upon the number of 
sheep to be treated. A convenient length is nine feet at the top, the 
floor having a length of four feet. From one foot above one end of the 
floor an incline with cross cleats rises to the top end of the vat. From 



TREATMENT OF MANGE AND SCABIES 127 

here the incHne may lead to a drippmg platform which maj' easily be 
improvised for the purpose. This should be so constructed and applied 
that the drip will flow back into the vat. 

Plans for more elaborate dipping plants, suitable for large flocks, may 
be obtained from bulletins issued by the Bureau of Animal Industr}', 
United States Department of Agriculture. 

To obtain the best results sheep should be sheared before dipping, 
and the dip used at a temperature of 100° to 110° F. Keep each sheep 
submerged two minutes by the watch, forcing the head under at least 
once just before the animal comes out. The dips should be freshly 




Fig. 73. — .\ small portable dipping vat for .small flock.s (from Bull. No. 21, 
Bureau of .\n. Ind., Dept. of Agr.). 

prepared for each dipping; if permitted to stand for repeated treatment 
failures and possibly injurious effects may result. 

Other Dips. — Tobacco dips, used either with or without sulphur, 
are now nnich in use and give excellent results. Owing to the poisonous 
character of nicotine, the active principle of tobacco upon which these 
dips depend for their action, the exact nicotine content of the dip should 
be known before it is used. This, according to the Bureau of Animal 
Industry, should not exceed 0.07 of one per cent. Owing to the variation 
of the percentage of nicotine in different kinds of tobacco and the added 
reason that tobacco dips are somewhat tedious and disagreeable to 
make, it is better to use a reliable tobacco extract, which may be ob- 
tained upon the market, and exactly follow the instructions given for 
the making of the dip. 

Tobacco dip is not injurious to the wool, therefore it has an advantage 
foi- use upon sheep which nuiy require treatment at a time when they 



128 PARASITES OF THE DOMESTIC ANIMALS 

cannot be safely or profitably sheared. Its disadvantages are that it 
sometimes causes a setback in the sheep by sickening them, and that it 
also occasionally sickens persons who work with it, especially if they are 
not tobacco users. 

Dips containing carbolic acid are easily made and rapid in their action, 
but soon evaporate from the body, leaving the sheep unprotected from 
reinfection. Furthermore, in the strength at which it must be used as a 
reliable acaricide, it causes the sheep to receive a greater setback than 
they do with either the tobacco or lime and sulphur preparation. 

After Treatment. — The dipping is to be repeated upon the entire 
flock in twelve to fourteen days. Where it is necessary to place the 
sheep in the same pasture which they occupied before being dipped, 
sulphur should always be an ingredient of the dip. This remains upon 
the skin and wool and protects from reinfection during the period that 
the acari may remain infective. In any case it is better to place the 
flock after the second dipping in a pasture which they have not been 
upon for at least five weeks previous to their treatment. 

Treatment of Psoroptic Scabies of Cattle. — As psoroptic scabies of 
the ox may become generalized or remain localized upon parts of the 
body easily reached by the tongue, mercurial preparations or those 
containing other poisons which may be licked off should not be em- 
ployed. Where one or two animals are affected upon limited areas of 
the body, ointments of sulphur, such as flowers of sulphur one part, 
lard four parts, may be used with good results. The remedy should 
be preceded by the usual preparation of the skin. After three days it 
can be washed ofT with soap and tepid water and the application re- 
peated. 

As a convenient, safe, and effective remedy probably the lime and 
sulphur dip will give better satisfaction than any other for the treat- 
ment of this form of scab in the ox. It should be prepared with the 
proportion between lime and sulphur somewhat reduced, as by the 
following formula: 

Flowers of sulphur 24 lbs. 

Unslaked lime 12 lbs. 

Water 100 gals. 

Mix according to directions given under lime and sulphur formulae 
for scab in sheep (page 125). 

Where a small number of animals are to be treated the dip may be 
applied as a spray or with a brush, working it at the same time well 
into the scabs. In larger herds this method is not practical, and the 
animals must be treated by dipping. Even though few in the herd 
give evidence of the disease, it is safer to dip all, as it is probable that a 
number of the apparently healthy have become infected. 



TREATMENT OF MANGE AND SCABIES 129 

Plants for dipping cattle range from the simple to the elaborate after 
various plans. Directions and estimates for the construction of such 
plants, together with much other valuable detail as to dipping, ma}' be 
obtained from the Bureau of Animal Industry, United States Depart- 
ment of Agriculture, upon application for bulletins relating to the sub- 
ject (Bull. No. 152). 

The temperature of the dip when used should be from 102° to 108° F. 
Each animal should be kept m it two minutes and be completely sub- 
merged before coming out. The treatment is to be repeated in twelve 
to fourteen days. 

After dipping the precautions against reinfection, already referred to 
in connection with sheep scab, are to be observed. 

Treatment of Psoroptic Scabies of the Horse. — The treatment of 
this scabies of the horse does iiot differ materiall}^ from that given for 
mange in the same animal. From the fact that the mites do not burrow 
and thus obtain a degree of protection from the acaricide, it is easier to 
control than the latter form. 

The preliminary application of soap and water, as directed in the 
treatment of mange, should be followed here, after which the same 
general acaricide treatment may be employed. The lime and sulphur 
preparation is probably of more use for this form of scab in the horse 
than for the sarcoptic. It is prepared according to the formulae given 
for scab in sheep (page 125), either formula No. 1 or formula No. 2 being 
used, according to the age and extent of the lesions. It can be applied 
as a spray or with a brush, being at the same time well worked into 
the scabs. The treatment should be repeated at intervals of eight to 
ten days until all indications of the presence of the mites have disap- 
peared. 

The precautions against reinfection, mvolving disinfection of harness, 
clothing, stalls, etc., as given under equine mange, are to be observed. 

Treatment of Chorioptic Scabies 

Treatment of Chorioptic Scabies of the Horse. — Clip the hair from 
over the affected parts, usually from the hocks down. It is well in any 
case to treat the fore legs m the same manner as these may have been 
infected. A portion of the scales and crusts may be removed with a 
brush, after which the parts are to be rubbed with a lather of soft or 
green soap. Let this remain for an hour, then rinse with tepid water, 
scrape, and allow to dry. 

The acaricides mentioned for the treatment of other forms of scabies 
ui the horse will apply here as well. The fact that the affected area in 
chorioptic scabies is usually limited to the lower parts of the legs per- 
mits of the use of remedies which would not be safe for application over 



130 PARASITES OF THE DOMESTIC ANIMALS 

lai'ger surfaces of the body. Strong tobacco decoctions, benzene, or oil 
of turpentine may be used, the latter shaken up in an equal quantity 
of linseed oil. Equal parts of kerosene and linseed oil also give good 
results. Two or three applications of the remedy applied several days 
apart usually suffices to bring about a complete cure. 

The usual precautions against reinfection should be observed. The 
bedding is to be burned and utensils disinfected. Animals should have 
their legs regularly and carefully groomed, and attendants should 
be on the lookout for sjanptoms of a return of the affection. 

Treatment of Chorioptic Scabies of Cattle. — The curative procedure 
for this scabies does not materially differ from that for bovine mange. 
As chorioptic scabies appears upon parts which may be reached by 
the tongue, preparations containing active poisons should be avoidecl. 
Probably an ointment of sulphur, as sulphur one part, lard four parts, 
or sulphur two parts, potassium carbonate one part, lard eight parts, 
is most suitable for such cases. 

Treatment of Follicular Mange 

Treatment of Follicular Mange of the Dog. — Owing to the intra- 
cutaneous location of the parasites, successful treatment of this mange 
is made very difficult. The prospects for eventual success will depend 
much upon patience and perseverance. It is important that the general 
condition of the animal be built up as much as possible by nutritious 
food and thoroughly sanitary surroundings. Such treatment as may 
be adopted must be prolonged and often repeated if carried out to 
effectiveness. The remedies given below for the destruction of the 
mites are among those which have been tried. The best that can be 
said for them is that they have sometimes given good results. 

(1) Peruvian balsam 2 parts, creolin 1 part, alcohol 20 parts. An 
objection to this remedy is its expense in view of the prolonged treat- 
ment required. (2) Creosote 1 part, olive oil 15 to 20 parts; (3) benzine 
1 part, olive oil 4 parts; (4) creolin 1 part, green soap and alcohol of 
each 3 parts; (5) repeated applications over limited areas of tincture of 
iodine. (6) In the clinic for small animals at the School of Veterinary 
Medicine, University of Pennsylvania, some encouraging results have 
been obtained from the use of ichthyol, prepared with lard or lanolin 
in the proportion of one to seven. 

Fleming advises that the topical treatment be accompanied by the 
internal administration of sulphur in frequent and large doses; the sul- 
phur being excreted to some extent by the skin. 

Treatment of Follicular Mange of Swine. — Treatment of this form 
of mange in the pig is rarely called for. If there are perceptible indica- 
tions of its presence a treatment as recommended for dogs may be tried, 



TREATMENT OF MANGE AND SCABIES 131 

though, due to the intractability and habits of pigs, there is probablj- 
even less prospect of a complete destruction of the mites. The presence 
of Demodex, however, is rarely recognized in pigs, and the effects it 
may produce are far less serious than in dogs. 

Treatment of Otacariasis of the Dog, Cat, and Rabbit 

Clean the ears of dogs and cats thoroughly and deeply with olive oil. 
It may be applied with a bit of cotton rolled upon a probe which should 
be rotated as it enters the deeper parts. Nocard's treatment, as stated 
by Neumann, is as follows: Naphthol 1 part, ether 3 parts, olive oil 
10 parts. Inject into the external auditory canal each day. After in- 
jecting close the canal for ten to fifteen minutes with a pledget of cotton. 
This is to prevent the evaporation of the ether. The ether causes the 
remedy to penetrate the wax>' Iming of the canal which contains the 
parasites. 

In the treatment of ra))bits the scabs are first to be softened by a 
thick lather of soft or green soap which should be allowed to remain for 
an hour, rinsed, and repeated as ma}' be necessary for deep crust forma- 
tion. The deeper parts of the ear ma}' then be cleaned with olive oil 
and cotton as directed for dogs and cats. 

As an acaricide, the same treatment may be employed as recommended 
for otacariasis in dogs and cats, applying the remedy with a pledget 
of cotton over the whole inner surface of the concha as well as injecting 
it into the auditory canal. An ointment of sulphur, or a liniment com- 
posed of benzene and olive oil equal parts may also be used, either to 
be applied with a pledget of cotton rolled upon the end of a probe or 
stick. 

It is a good precautionary measure to treat the ears of all rabbits 
which have been exposed, as there ma}^ be infections of a latent char- 
acter which will later bring about another outbreak of the disease. 



CHAPTER XII 

MANGE OF POULTRY 

The acari-prodiicing mange of fowls belong with the genus Cnemi- 
docoptes, the characteristics of which are described on page 103. There 
are two species, — Cn. mutans (formerly Sarcoptes mutans), which pro- 
duces the condition known as scaly leg, and Cn. gallince {Cn. Icevis) 
which attacks the skin at the attachment of the feathers. 

Mange of the Legs (" Scaly Leg "). — The burrowing mite of leg 
mange most often attacks the feet and legs of chickens of the heavier 
breeds, as the Brahma, Dorking, and Cochin China, less frequently 
turkeys, pheasants, and pigeons. 

The mites live under the epidermic scales from the tarsal joint down- 
ward, including the upper part of the toes. In this location iYiey deposit 
their eggs and multiply, the irritation of their presence soon being 
manifested by the formation of a white powdery matter which elevates 
the scales. Due to the exuded serum, this matter assumes a lardaceous 
nature, adhering to and soon covering the foot. Gradually rough crusts 
are formed in the lower layers of which numerous mites may be found. 
The scabs adhere closely to the skin, and, when removed, reveal an 
irritated and bleeding surface (Fig. 75). 

The course of the disease is slow, running several months to a 3'ear. 
There is a moderate pi-uritus which the fowl indicates by restlessness 
and picking at the scabs with the beak. As the crusts increase there 
is a mechanical interference with flexion of the joints which makes 
either moving about or standing difficult. As a consequence the animal 
often squats down with the legs extended and remains in this position 
with infrequent efforts to rise. In such severe cases arthritis is likely to 
appear, and one or even all of the toes may drop off. When the disease 
has advanced over several months we have the usual systemic accom- 
paniment of prolonged mange; there is loss of appetite, cachexia, and 
stupor which is usually followed by death. 

Treatment. — Treatment must begin with softening of the scabs with 
soft soap, appHed by hand or by soaking in warm soapj^ water. They 
may then be removed by manipulation with the hands or with a brush, 
care bemg taken in this operation to cause as little'injury to the skin as 
possible. When the parts are dr,y, apply Peruvian balsam, either alone 
or made up in the proportions of balsam 2 parts, creolin 1 part, alcohol 
20 parts. The ointment of Helmerich, as recommended for scabies in 



IMANGE OF POULTRY 



133 



other animals, is one of the best remedies for this scab. Others perhaps 
as effectual are (1) creosote 1 part, lard 20 parts; (2) benzene 1 part, 
olive oil 10 parts; (3) carbolized vaseline (5%), or (4) an ointment of 
carbolic acid 1 part, lard 20 parts. The stronger acaricides should not 
be used upon young chicks. For these the ointment of Helmerich or 
Balsam of Peru are quite suitable. The application may be washed off 
and repeated as necessary'. 

To prevent contagion and reinfection, diseased fowls should be re- 
moved from the healthy and the quarters subjected to cleaning up and 
disinfection, especial attention bemg given to roosts and other places 
where the fowls are in the habit of perching. 




Fig. 74. — Cnemidocoptes mutans, male and female (after 
Osborn, Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 



Mange of the Body, or Depluming Mange. — The depluming mite, 
Cnemidocoptes gallince, is closely related to the mite of foot mange and 
it may easily be mistaken for the same species where the two forms of 
mange coexist. The Ijody form usually has its begmning on the back, 
near the msertion of the tail-feathers. More rarely the head and upper 
part of the neck are first attacked. From these regions it spreads to 
adjacent parts of the body. 

The disease is accompanied by the production of an abundance of 
epidermic scales, irritation, and itching which impels the fowl to pluck 
at the feathers. These easily drop out or are broken off, leaving a bald 
or partly denuded skin which is but little thickened and remams normally 
smooth and elastic. 

The acaricide treatment employed may be the same as for foot mange. 
AVhere a numljcr of birds are affected they may be treated by dipping 
for several successive days m a sulphur bath. The same precautions 
against contagion and remfection are to be observed as for the leg form. 
In this connection it is well to repeatedly disinfect the feet of roosters. 



134 



PARASITES OF THE DOMESTIC ANIIMALS 



Cytoleichus nudus. 



as the disease is readily conveA^ed from the l^ack of one hen to another 
in treading. 

Family V. Cytoleichid^ 

Acarina (p. 94). — This family contains two genera, Cytoleichus and 
Laminosioptes, each with one species causmg a deep-seated acariasis m 
birds. 

C3^toleichidse (p. 134). — The body is rounded, 
almost bald, and whitish in color. The 
mouth parts are conical. The legs have five 
articles and are strong and elongated; all 
terminate by a simple stalked sucker. The 
ovigerous female is 500 to 600 microns long 
by 350 to 400 microns broad. She may pro- 
duce either larvae or eggs. 

Colonies of these parasites live in the air 
passages and air sacs of fowl. 

Laminosioptes cysticola. Cytoleichidae 
(p. 134). — The body is twice as long as 
broad; color grayish. On the dorsal surface 
are several pairs of bristles, a long pair ex- 
tending from the posterior extremity. The 
mouth parts and the two first pairs of legs 
are carried upon the anterior third of the 
body which is separated from the posterior 
portion by a transverse furrow. The legs 
are short, smooth, and provided with 
suckers, which are not permanent upon the 
anterior pair. The ovigerous female is 250 
to 260 microns long b^' 100 to 110 microns 
broad. 

Parasitic in subcutaneous connective tis- 
sue of fowl. 

The C3'toleichus species enter the respir- 
atory passages and pass to the deeper air 
channels, even to the air canals in the bones. 
From their relatively large size and whitish 
color they may be readily seen with the naked eye, usually in colonies 
of more or less number. Ordinarily these parasites do not cause suf- 
ficient disturbance to betraj' their presence during the life of their host. 
If in exceptionally large numbers they maj' cause attacks of coughing 
by irritation of the bronchial mucosa. 

Laminosioptes cyUicola lives m the subcutaneous connective tissue, 
especially in regions where this is loose, as the neck, breast, sides, and 




Fig. 75. — Foot of fowl affected 
with scaly leg. 



IMANGE OF POULTRY 135 

thigh. Where nian}^ are present they cause irritation with the forma- 
tion of yellowish, oval nodules. These are about 0.5 mm. by 1 mm. 
in dimensions, and a large number of them may cover a small area. They 
are soft, granular or calcareous, and may contam the dead parasites. 
The health of the host does not appear to l)e affected by the lesions 
which these parasites produce. 



CHAPTER XIII 

THE TICKS 

There has been considerable difference of opinion among various 
authors as to the S3'stematic arrangement of the ticks. They have 
been brought into one family, — Ixodidae, in which two subfamilies are 
distinguished. — Argasinse and Ixodmse, and, again, these two subgroups 
have been considered as distinct families. The arrangement adopted 
here, which raises the ticks to the rank of a superfamily, is that of Banks 
(1894) and as followed by Salmon and Stiles (1901). 

Structure of Ticks in General. — The proper study and differentiation 
of the ticks requires some knowledge of the external parts and an under- 
standing of the teclmical terms which are used m reference to them. 
Conformmg to the general characteristics of the order Acarma to which 
they belong, the ticks have a body in which the cephalothorax and 
abdomen are not demarcated and this bears certain structures possessing 
variations as to location and form which serve as defining characters 
for the various subgroups and species. The parts more commonly 
referred to with their technical names follow : 

1. The Capitulum (Fig. 76) is the "head," ''false head," or rostrum, as 
it is variously termed. It projects from the anterior extremity in the 
Ixodidae. In the Argasidae, except in the larval stage, it is upon the 
under surface of the anterior extremity. The structure consists of a 
number of parts, as follows : 

(a) The Basis Capitidi (Fig. 76, b) is the hard base of the capitulum; 
the basal ring or mouth shield. 

(b) The Hijpostome (Fig. 76, h) or "labium" or "radula" of various 
authors is a median ventral structure rising from the basis capituli and 
bearing recurved teeth. 

(c) The Chelicerce (Fig. 76, c), "mandibles," or "jaws" are paired 
elongate structures, one on each side of the median line, lying dorsal 
to the hypostome. Dorsal to these is the hood or sheath of the chelicerse. 

The hypostome, chelicerse, and hood constitute the haustellum, or, as 
it is commonly called, the "beak," and it is these structures which pen- 
etrate the skin of the animal upon which the tick attaches. 

(d) The Palpi (Fig. 76, p) are articulated structures, one on each 
side of the haustellum, and inserted antero-laterally upon the basis 
capituh. 

2. The Scutum (Fig. 77), or dorsal shield — present in the Ixodidae, 



THE TICKS 



137 




Fig. 76. — Capitulum (rostrum), 
of an argasid tick: h, hypostome; 
c, chelicerae; p, palpi; b, basis 
capituli. 



absent in the Argasidae — is a hard, plate-Hke structure located inmie- 
diately posterior to the capituhim. In the male it usually covers the 
entire, or almost the entire, dorsal surface, 
in n\nnphs it covers the anterior portion; 
while in the adult female it is much smaller 
and confined to the anterior portion of the 
liody. 

3. Dorsum. — This term refers to the 
whole dorsal surface of the body. 

4. Festoons (Fig. 82) are uniform rect- 
angular areas into which the posterior mar- 
gin of the body is divided up. Usually 
eleven may be more or less distinctly rec- 
ognized. They are most distinct in unfed 
specimens, but almost or entirely disap- 
pear in distended females. They are not 
present m all forms. 

5. Punctations are circular depressions 
upon the integument from which fre- 
quently issue hairs. 

6. Ornamentation refers to enamel-like coloration which may be pres- 
ent on the scutum, capitulum, or other parts. Ticks upon which this 
coloration occurs are re- 
ferred to as ornate. 

7. Venter. — This term 
refers to the whole ventral 
surface of the body. 

8. The Spiracles (Figs. 
78 and 78, a) — also called 
stigmata, stigmal plates, 
and peritremes — are two 
respiratory organs sit- 
uated ventro-laterally. In 
the Ixodidse they are sit- 
uated posterior to the 
attachment of the fourth 
pair of legs; in the Arg- 
asidae they are ))etween 
the third and fourth pairs. 
The entire structure may 
be considered as the 
stigmal plate or peritreme 
with an opening known as 
the spiracle or stigmal aperture. The stigmal plates vary in form and 




Fii;. 77. — Capitulum (head), .•scutum (.shield), and 
foreleg of Margaropus annulatu.s (from photomicro- 
graph of mounted specimen, by Hoedt). 



138 



PARASITES OF THE DOMESTIC ANIMALS 



structure in different species; they may be circular, oval, or comma- 
shaped. 

9. The Genital Pore is a transverse ventro-median slit, situated ante- 
riorly between the at- 
tachments of the first 
three pairs of legs. 

10. The Anus is in the 
ventro-median line, pos- 
terior to the attachment 
of the last pair of legs. 

11. The Anal Shields 
are four elongate struc- 
tures lateral to the anus. 

They are present only in males of certain genera. 

12. Legs. — There are four pairs of legs in the adult males and females 
and in the nymphs (octopod). In the larvae there are three pairs (hex- 




FiG. 78. — Stigmal plates of ticks: 1, Margaropus 
Ixodes; 3. Dermacentor. 




Fig. 78A. — Stigmal plate of Margaropus annulatus (photomicro- 
graph of mounted specimen, by Hoedt). 

apod). The pairs are numbered I to IV from before to behind. They 
are composed of six articles or segments which are united by articul- 
ations. 

13. The Coxa or first article is an immovable portion which lies flat 
upon the body and upon which the first movable article is articulated. 



THE TICKS 



139 



14. Bifid Coxce bear two spurs and are deeply incised. When tren- 
chant they have a knife-hke margin. 

Several stages are passed through in the development of the ticks. 
From the eggs are hatched the six-legged (hexapod) larvce, often referred 
to as the "seed ticks" (Plate II, Fig. 6). These are very small but 
may be seen without the aid of magnification. The legs are relatively 
much longer than in the adults. 

The nymph stage is reached after molting, when a fourth pair of legs 
appears posterior to the third pair (octopod). 

The change from the nymphal to the adult stage is marked by another 
molting, and sexual maturity is reached. 

After fertilization b}^ the male, the female slowly enlarges and be- 
comes the ovigerous or egg-containing female. Upon repletion she drops 
to the ground and proceeds to deposit her eggs. 

Superfamily Characteristics. Acarina (p. 94). — The Ixodoidea are 
all blood-sucking parasites on animals. They have a movable capitulum 
consisting of a basal portion (basis capituli), protrusi})le serrate chel- 
icerse, a rigid serrate hypostome, and a pair of palps. The breathing 
apertures are situated posteriorly. 

The superfamily Ixodoidea is divided into two families, — Argasidae 
and Ixodidse. 

Family I. Argasid^ 

Ixodoidea (p. 139). — The ticks belonging with this family have little 
sexual dimorphism as compared with the Ixodid*. The capitulum, 
instead of being terminal, occupies in adults the ventral face of the 




■^^^ 




Fig. 79. — Argas miniatus: Fig. 3, dorsal view; 3a, ventral view; 3c, larva (after Os- 
born, from Marx, Bui. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 

cephalothorax. The palps are leg-like, the articles very movable on 
each other. The scutum is absent. The coxa^ are unarmed; tarsi with- 
out ventral spurs. 

The family has two genera, — Argas and Otobius. 

1. Argas miniatus (A. americanus) (Fig. 79). The Fowl Tick. Ar- 
gasidae (p. 139). — The lK)dy is ovoid, flattened, with edges very thin. 



140 PARASITES OF THE DOMESTIC ANIMALS 

Depending on the stage of engorgment, the color varies from Hght 
reddish to dark brown. The capitulum has four long hairs, all directed 
forward. The adult females are about 8.5 mm. (5/16 of an inch) in 
length. The males are slightly smaller, but are not easily distinguish- 
able. 

Occurrence and Habits. — Commonly called the "fowl tick" or 
" adobe tick," this species is widely distributed. It is a parasite of fowl in 
Europe, Asia, Africa, and Australia, in Mexico and the Southern United 
States. In its habits it is comparable to the bedbug, commg out to 
feed upon its host at night and retreating after engorgment to cracks, 
crevices, or other darkened hiding places to remain during the day. In 
these retreats the females deposit large, reddish brown eggs, usually 
several layings, in masses containing up to a hundred or more eggs in 
each. Herms (1915) gives the further life history as follows: "Hatching 
takes place in from three to four weeks. The larvee are six-legged and 
very active, attacking a host apparently as readily by day as by night. 
Once attached the larvae feed for about five days, occasionally longer, 
remaining firmly attached during this time. At the end of this feeding 
period the larvae detach themselves and then crawl away from their 
host, hiding in some convenient crevice near by. The larvae molt in 
about a week, when the fourth pair of legs appears and they are now in 
the first nymphal stage, appearing like miniature adults. Nocturnal 
feeding now takes place and in ten or twelve days another molt 
occurs and the second nymphal stage is reached. Again the tick at- 
taches itself, being now able to engorge itself in about an hour; again 
after the expiration of something over a week a third molt takes place 
and the adult stage is reached. The adults are able to engorge them- 
selves in from twenty to forty-five minutes." 

Effect. — When attacking in large numbers these parasites extract 
large quantities of blood and, furthermore, cause much irritation and 
unrest among the flock. As a result the animals become unthrifty, 
weak, and nonproductive. 

Argas miniatus has been proven to be the carrier of the spirochete 
(Spirocheta gaUinarum) causing fowl spirochetosis or Brazilian sep- 
ticemia of fowls (p. 327). 

Control. — For the eradication of this pest the same general methods 
may be taken as recommended for bedbugs of the hen house (p. 92). 
The ends of roosts should be repeatedly covered with tar or wrapped in 
waste soaked Avith crude oil. Nesting and trash should be burned and 
the interior sprayed with kerosene. All woodwork about the buildings 
should be free from bark, as this affords a favorable hiding place for the 
ticks. It is well to repeat the treatment with kerosene at least once a 
month during the season that the ticks are active, 

2. Otobius megnini (Ornithodorus megnini, Fig. 80). The Spinose 



THE TICKS 



141 



Ear Tick, Argasidse (p. 139). — The boch' is oval, broader anteriorly than 
posteriorly. The female is 5-6 mm. (V4 of an inch) in length and about 
3 nmi. (Vs of an inch) in breadth. The nymphs are covered with nu- 
merous spines, a fact which has given to this species the common name 
''spinose ear tick." 

Occurrence and Habits. — This tick occurs in the ears of horses of 
]\Iexico and the Southwestern States. Its attack is not confined to 
horses and mules; it also attacks the ears of cattle and occasionally other 
domestic animals and man. The larval ticks reach the head of the graz- 
ing host animal from weeds or other vegetation upon which they have 
crawled immediately after 
hatching. Having gained en- 
trance to the ear, they attach 
deeph' in the folds where the}- 
feed for about five days. 
They then molt and, as 
n\Tnphs with spinose bodies, 
contmue to infest the ear and 
feed for several weeks. The 
minphs then leave the host, 
again molt, and becoming 
unspmed adults, the females 
are fertilized and soon begin 
depositing their eggs. 

Effect. — In their attach- 
ment to the lining of the 
conchse the spinose ticks 
cause much irritation which 
the animal indicates by shak- 
ing its head, or it may be 
wrought up to a high degree of nervous excitement. The ticks are said 
to be responsible for much deafness among domestic annuals, and, 
especially among young animals, they are considered as a cause of se- 
rious illness and even death. 

Treatment. — Good results have been obtained by flooding the ear 
with carbolized oil. This closes the breathing apertures of the ticks and 
causes them to release their attachment, after which they may be re- 
moved with a cotton swab or forceps and destroyed. 




Fig. 80. — Otobius megnini: dorsal and ventral 
view of nymphal form, with details (after Osborn, 
from IVIarx, Bull. Xo. 5, Bureau of Entomology, 
U. S. Dept. of Agr.). 



Family II. Ixodid.e 

Ixodoidea (p. 139). — The most prominent differential character by 
which these ticks may be distinguished from those of the family Ar- 
gasidse is the presence of a scutum, located inunediately posterior to 



14-2 PARASITES OF THE DOMESTIC ANIMALS 

the capitiiluin, which is terminal and not upon the ventral face of the 
cephalothorax as in the Argasidse. Sexual dimorphism is marked, the 
dorsal surface of the males being almost covered by the scutum. In 
the distended female the scutum appears as a small shield directly be- 
hind the capitulum. Only the females are capable of great distension. 
The spiracles are posterior to the fourth coxae. The eyes, if present, are 
situated laterally upon the scutum. 

Nine genera have been described under the famity Ixodidae, as fol- 
lows: Ixodes, Hsemaphysalis, Dermacentor, Rhipicentor, Rhipicephalus-, 
Margaropus, Boophilus, Hyalomma, and Amblyomma. 

Four of the above, — Ixodes, Dermacentor, Margaropus, and Am- 
blyomma, — -contain species occurring upon cattle and other animals in 
the United States. The generic characteristics of these are given by 
Nuttall and Warburton (A Monograph of the Ixodoidea, 1911) as 
follows: 

1. Ixodes. — Inornate, without eyes and without festoons; spiracles 
round or oval; palps and basis capituli of variable form; coxae either un- 
armed, trenchant, spurred, or bifid; tarsi without spurs. Sexual di- 
morphism pronounced, especially with regard to the capitulum. In 
the male the venter is covered by non-salient plates: one pregential, 
one median, one anal, two adanal and two epimeral plates. Anal groove 
surrounding anus in front. 

2. Dermacentor. — Usually ornate, with eyes and festoons; with 
short, broad or moderate palps and basis capituli rectangular dorsally. 
In some species coxae I to IV of the male increase progressively in size; 
in all species coxa IV is much the largest ; the male, moreover, shows no 
ventral plates or shields. Coxa I bifid in both sexes. Anal groove con- 
touring anus behind. Spiracles suboval or comma-shaped. 

3. Margaropus. — Inornate, with eyes, but without festoons, with 
short palps and capitulum intermediate between that of Rhipicephalus 
and Boophilus; highly chitmized; the unfed adults of large size. The 
female with very small scutum. Coxae conical, unarmed but for a small 
spine posteriorly on coxa I. The male with a median plate prolonged 
in two long spines projecting beyond and to either side of the anus; 
with coxae similar to those of the female; legs increasing progressively 
in size from pair I to IV, the articles, especially of leg-pair IV, greatly 
swollen. When replete, the male shows a caudal protrusion. Anal 
groove obsolete. Spiracles rounded or short oval in both sexes. 

4. Amblyomma. — Generally ornate, with eyes and with festoons. 
With long palps; of which article II is especially long, basis capituli of 
variable form. The male without adanal shields, but small ventral 
plaques are occasionally present close to the festoons. Anal groove 
contouring anus behmd. Spiracles subtriangular or comma-shaped. 

Six species are found upon cattle and other domestic animals in this 



THE TICKS 



143 



countiy, the following brief descriptions of which are taken principally 
from those given by ^lohler (Bull. No. 78, Bureau of Animal Industr}-, 
1905; Farmers' Bull. No. 569, 1914). The parts described are those of 
the adult female. 

1. Ixodes ricinus (Fig. 81). The Castor-bean Tick. Ixodes (p. 
142). — The body is ovoid in shape, narrower anteriorly than posteriorly; 
lead colored, with a diversity of 3'ellowish red, brown, or gray. Festoons 
are absent. The mature female is three-eighths to seven-sixteenths of 
an inch m length. The legs are thin and dark brown in color. The 
capitulum and scutum are a shiny dark brown or' chestnut brown; 
scutum pentagonal with prominent lat- 
eral borders. The palpi are well de- 
veloped and extend outward upon each 
side. 

This tick has been collected from sheei\ 
goats, cattle, horses, deer, dogs, foxes, 
cats, rabbits, birds, and man. It i- 
widely distributed in the United States. 

2. Ixodes hexagonus. The European 
Dog Tick. Ixodes (p. 142).— The body 
is oval in shape and of an ashy color; 
festoons absent. The legs are longer and 
more robust than those of the cattle tick. 
The capitulum and scutum are brownish 
red in color and similar to those of 
Ixodes ricinus in shape. The palpi are 
longer and more prominent than in the 
cattle tick and, like those of Ixodes ridniis, extend outward. 

This species has been collected from dogs, cattle, sheep, foxes, rabbits, 
squirrels, gophers, cats, birds, man, and other hosts in the Eastern 
United States, but is less common in this country than the other species 
here described. 

3. Dermacentor reticulatus (D. occidentalis). The Net Tick. 
Dermacentor (p. 142). — The body is oblong oval, five-eighths of an inch 
long, and of a deep brown or slate color. The legs are brown and of 
moderate length. There are eleven festoons about the posterior margin 
of the ])ody which in the adult become shallow or effaced. The scutum 
has a silveiy-white metallic rust extending along the two sides and 
posterior portion. 

Found on man, cattle, horses, sheep, and deer. In this country it 
seems to be most common in the West, especially in California, Texas 
and New^ Mexico. 

4. Dermacentor variabilis (D. electus, Fig. 82). The American 
Dog Tick or Wood Tick. Dermacentor (p. 142). — This tick resembles 




Fig. cSl. — Ixodes ricinus — enlarged 
(after Osborn, Bull. No. 5, Bureau 
of Entomology, U. S. Dept. of Agr.). 



144 



PARASITES OF THE DOMESTIC ANIMALS 



D. reticulatus so closeh^ that a hand lens is necessary to distinguish be- 
tween them. The body is oblong oval in shape and may measure as 
much as three-fifths of an inch in length. It can be distinguished from 
the Texas-fever tick by the capitulum and scutum which are longer and 
broader. Extendmg anteriorly along each side of the scutum there are 
lines of yellowish white rust, separated by a central brownish area. 
There are eleven festoons on the posterior margin of the body, most 
distmct in the 3'oung female. 

This tick has been found on man, cattle, dogs, horses, and other an- 
imals, especially in the Eastern United States. 




Fig. 82. — Dermacentor variabilis: male — enlarged (after Os- 
born, Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 

5. Margaropus annulatus (Boophilus annulatus, B, bovis). The 

Texas-fever or Cattle Tick. Margaropus (p. 142). — This tick may be 
distinguished from the other five by the small size and the color of the 
capitulum and scutum, the lateral borders of which are straighter and 
more parallel. These parts are short and relatively broad and in color 
reddish brown or chestnut brown. The body is oblong oval in shape 
and may reach a length of one-half an inch. The color may be dull 
yellow or olive brown. Often it is mottled with irregular areas of 
yellow and brown or streaked with wavy lines of these colors. Festoons 
are absent. The legs are brown, moderately long, and very slender. 

This tick is found principally on cattle, less frequently on horses, 
mules, and asses. 



THE TICKS 145 

6. Amblyomma atnericanum. The Lone Star Tick. — Amblyomma 
(p. 142). — The body is oval and in color yellowish gray or brown. 
When not distended, the body-surface is rough and puckered. Festoons 
are present. The scutum extends backward a short distance to form a 
triangle, at the apex of which is a white or yellowish spot, from which 
the tick derives its name "Lone Star." The mature female may reach 
a length of one-half an inch. The legs are long and thin. 

This species has been found on cattle, dogs, horses, sheep, goats, hogs, 
and man. It is very widely distril)uted in the United States. 

All of these ticks show longitudinal grooves ujion the dorsal surface 
of the body which are most distinct a few days after the tick's repletion 
and removal from the host. These furrows vary considerably in different 
members of the same species and, though some authors appear to attach 
importance to them, they can hardly be considered of much value as an 
aid in recognition. Color is also unreliable in the identification of 
genera and species, as this varies with the stages in the tick's develop- 
ment and may change variously in adult ticks of the same species. 

The Texas-fever Tick. — Kilborne, of the Bureau of Animal Industry, 
proved conclusively by field experiments conducted in 1889 and 1890 
that it is only through the bite of this tick that Texas-fever can be 
naturally transmitted. Economically, therefore, Margaropus annulatus 
(Plates I and II), the Texas-fever tick, is the most important for con- 
sideration. Other ticks not concerned in the transmission of Texas- 
fever have been mentioned here as occiu'ring upon cattle, all having 
the same successive stages in their development, namely, oval, larval, 
nymphal, and adult male and female. Before molting and transforming 
from one stage to the other these ticks fall from their host, after the 
transformation seeking a new host. That this is not true in the case 
of the Texas-fever tick was shown by Dr. Cooper Curtice, of the Bureau 
of Animal Industry, in 1891. He established the fundamental facts 
in the life history of this tick and showed that it remains upon its host 
from the time that it attaches as a larva until it drops to the ground 
replete and ready to deposit its eggs (Tables, p. 151). Careful observa- 
tions by the Zoological Division of the Bureau have supplied valuable 
data relative to the biology of this tick, and much detailed information 
has been published by the Bureau pertaining to this and to tick control 
and eradication. In this connection, it may be of service to mention 
here the following titles, any of which can be obtained upon application 
to the Superintendent of Documents, Government Printing Office, 
Washington, D. C. 

Texas Fever, Methods for its Prevention, by John R. Mohler. Bull. 
No. 78 (1905). 

Texas or Tick Fever and its Prevention, l)y John R. Mohler. Farmers' 
Bull. No. 258 (1906). 




Plate I. — Margaropus annulatus: 1, Male, dorsal view; 2, Female, dorsal view; 3, 
Male, ventral view; 4, Female, ventral view; 5, Claw and pulvillus; 6, Lower surface of 
first, second, and third segment of leg; 7, Stigmal plate. (After Osborn, from Curtice, 
Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 




4 4a 






Plate II.— MarRaropus anruilatus: 1, Front foot, showing single spur; la, Supposed 
sense organs; 2, Hind foot, showing double spur; 3, Head of female; 4, 4a, 4b, 4e, Fcrnale 
ticks, natural size, shown at different stages of feeding; 5, Egg; G, Larval or "seed" tick; 
7, Dorsal surface of the mouth parts of female — a, mandible; b, labrum; c, palpus; d, 
mouth ring; e, spots covered with papilla; S, Labium and mandibles; 8a, Papilla; enlarged; 
9, Mandible-X-Busk's organ, use unknown; 10, Mouth parts of young tick. (After Osborn, 
from Curtice; Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 



148 PARASITES OF THE DOMESTIC ANIMALS 

The Cattle Tick in its Relation to Southern Agriculture, b}^ August 
Mayer. Farmers' Bull. No. 261 (1906). 

Proceedings of a Conference of Federal and State Representatives 
to Consider Plans for the Eradication of the Cattle Tick. Bull. No. 97 
(1907). 

Methods of Eradicating Cattle Ticks, by Louis A. Klein. Cir. No. 
110 (1907). 

Studies on the Biologv of the Texas-fever Tick, bv H. W. Gravbill. 
Bull. No. 130 (1911). 

Methods of Exterminating the Texas-fever Tick, by H. W. Graybill. 
Farmers' Bull. No. 498 (1912). 

Progress and Prospects of Tick Eradication, by Cooper Curtice. 
Cir. No. 187 (1912). 

Texas or Tick Fever, by John R. Mohler. Farmers' Bull. No. 569 
(1914). 

Life History; the Nonparasitic Development. — The following data 
as to the life histor}^ of the Texas-fever tick is taken from Graybill 
(Studies on the Biology of the Texas-fever Tick, 1911). The non- 
parasitic development is considered bj^ this author under five periods, 
namely, the preoviposition period, the oviposition period, the incu- 
bation period, the hatching period, and the longevity period of the 
larva? . 

The period of preoviposition extends from the time the female tick 
drops until she begins to deposit her eggs. In a series of investigations 
carried out at Auburn, Ala., m 1907-8 it was observed that the average 
duration of this period ranged from three to forty-nine and three-tenths 
daj^s, depending largely upon temperature, the shorter average period 
occurring in August, the longer in December. 

The average oviposition or egg-Iaymg period for different months of 
the year ranged from eight and three-tenths daj^s for June to one hun- 
dred and twenty-seven and five-tenths daj^s for November. The 
maximum period noted was one hundred and fift^^-two days, observed 
in November, and the mmimum three days, observed in June. The 
maximum number of eggs deposited by a female tick was 5105, minimum 
357, with an average ranging from 1811 to 4089. 

The incubation period was found to range from nineteen days in the 
summer to one hundred and eighty days beginning in the fall. The 
conditions essential to development and hatching are moisture, such as 
supplied bj^ sufficient atmospheric humidity to prevent eggs losmg 
moisture by evaporation, and a favorable temperature. 

The hatching period is taken as the time required for all of the eggs to 
hatch after hatching begins, the eggs deposited by a female hatching 
approximately in the sequence in which the,y are laid. The average 
period was found to range from ten and six-tenths days for Jul.v to 



THE TICKS 



149 



thirty-six days for Octoljer. The maximum period observed was forty- 
nine da^'s for October, the minimum four days for July. 

The longevity period is stated to depend on individual vitahty, 
humidity, and temperature. It was noted, especially in eggs laid during 
the winter, that some larvse do not have sufficient vitality to disengage 
themselves from the eggshell and die partly inclosed within it ; also that 
others die veiy soon after emerging. Cold, it is stated, prolongs longev- 
ity because of the fact that the tick remains quiescent with resulting 
conservation of bod.y fluids and nourishment. The fact that the larvae 
respond negatively to light is an additional factor promoting longevity. 
In places exposed to the sun they collect on the under side of leaves and 
other vegetation, thus protecting themselves from loss of bodj^ moisture 
through the direct heat of the sun. In observations made it was deter- 
mined that the average maximum longevity for larvae hatched from a 
number of lots of eggs in July was thirtj'-eight and six-tenths days. 
From eggs hatched in October the average maximum period was one 
hundred and sixty-seven and four-tenths days. The shortest period 
was four days for larvae hatched in July, the longest two hundred and 
thirty-four daA'S for larvae hatched in October. 

The following summary' is given of the data on the nonparasitic 
period : 

Total Time from Dropping of Female until all Resulting Larvce are Dead 



Date engorged 

females were 

collected 


Number 

of engorged 

females 


Range of 
entire- 
time 
periods 


Average 

of 
periods 


Date engorged 

females u-ere 

collected 


Number 

of engorged 

females 


Range of 
entire- 
time 
periods 


Average 
periods 


June 1, 1907 


7 


Days 
79-100 


Days 

86.9 

101 
199.6 
250.7 
279.6 


Dec. 29, 1907, 

to 
Jan. 1, 1908 


3 


Days 
181-207 


Days 
196.3 


July 1, 1907 


7 


82-112 


Jan. 29 to 
Feb. 4, 1908 


7 


156^189 


173.1 


Aug. 1, 1907 


7 


172-221 


Feb. 27 to 28, 
1908 


2 


143-162 


152.1 


Aug. 31, 1907 


6 


230-272 


Mar. 26 to 
29, 1908 


9 


144-161 


152.1 


Oct. 1, 1907 


7 


276-288 


April 29, 
1908 


14 


122-173 


142.8 


Nov. 1, 1907 


7 


200-253 


232.7 










Nov. 30, 1907 


3 


187-249 


217 











The Parasitic Development. — The parasitic development has three 
stages, the larval, the nyniphal, and the adult. In the experiments car- 



150 



PARASITES OF THE DOMESTIC ANIMALS 



ried on upon this portion of the tick's life history tick-free animals were 
infested at nine different times from July, 1907, to May, 1908. It was 
found that the minimum larval period ranged from five to seven days; 
the minimum nymphal period of females, nine to eleven days; the adult 
period, from a minimum of five to a maximum of thirty-three days. 
The table which follows is given to show the range of the periods ob- 
served upon larvae which were marked after they had become attached 
and then kept under observation from day to day. 



Le7igth of Period and Total Duration 


of Parasitic Development 


Date larvce applied 


Sex 


Length 

of larval 

period 


Length 

of nymphal 

period 


Length 

of adult 

period 


Duration 

of parasitic 

period 


1908 
Feb 29 


Females 


iT 


Days 
10-15 


Days 
5-13 


Days 
25-34 






Do 


Males 


7-9 


8-10 


- 








Do 


(?) 


7-14 


- 


- 


_ 






April 4 


Females 


7 


9-14 


4-9 


25-26 






Do 


Males 


7 


8-12 


- 


— 


May 23 


Females 


6-7 


9-12 


6-9 


22-25 






Do 


Males 


5-8 


8-13 


— 


_ 







As to the importance of the foregoing data, Graybill says: ''The dura- 
tion of each of these stages and the duration of a single infestation upon 
cattle during different portions of the year are of great practical im- 
portance. Upon the duration of an infestation depends the time anmials 
must be kept on tick-free fields in order to become free from the ticks." 



THE TICKS 151 

Life Histories of the Dog Tick and Texas-Fever Tick Compared 
IN Tabular Review (note italics) 

dermacentor variabilis 
Ovigerous Female. — Engorges upon host, drops to ground, 
I and deposits eggs. 

Eggs. — Deposited upon ground in mass. 

I 
Larvae. — Bunched upon grass from which the}^ reach 

I first host. 

First Molt, Larvae to Nymphs. — ?7joon ground, after drop- 

I ping from first host. 

Nymphs. — Crawl from grass upon second host. 

Second Molt, Nymphs to Adults.— ?7?j0/i ground, after 
I dropping from sec- 

I ond host. 

Males and Females.— C rawl from grass upon third host; 
I mate. 

Ovigerous Females. — Engorge upon host. 

Ovigerous Females. — Drop to ground and deposit 
eggs. 

MARGAROPUS ANNULATUS 

Ovigerous Female.— Engorges upon host, drops to ground. 
I and deposits eggs. 

Eggs. — Deposited upon ground in mass. 

Larvae. — Bunched upon grass from which they reach 
I host. 

First Molt, Larvae to Nymphs. — Upon host. 

Second Molt, Nymphs to Adults. 
Males and Females. — Upon host; mate. 

Ovigerous Females. — Engorge upon host, 

Ovigerous Females. — Drop to ground and deposit 
eggs. 

Loss Occasioned by Cattle Ticks.— According to estimates published 
in 1914, the main sources of loss occasioned by the cattle tick may be 
summarized as follows: 



1.52 PARASITES OF THE DOMESTIC ANIMALS 

The parasitic life of the ticks, together with the blood-destroying 
properties of the protozoan parasites with which they inoculate their 
hosts, causes a loss of flesh and lack of development in southern cattle 
conservatively estimated at $23,250,000. 

The lower price which southern cattle from infested districts bring 
in northern stockyards averages at least $1.50 per head. It is estimated 
that the loss upon animals marketed under these conditions, including 
stock, beef, and dairy cattle, will sum up to $1,057,500 annually. 

The shrinkage in milk production of cattle infested with many ticks 
will average about one quart per day. Upon an estimate of 875,000 
ticky dairy cattle out of more than 4,000,000 dairy cattle below the 
quarantine line, the loss thus occasioned, reckoned at three cents per 
quart, would amount to $26,250 per day, or, counting three hundred 
milking days for each cow to the year, $7,875,000 annually. 

The loss among nonimmune southern cattle in tick-free pastures- 
through contracting Texas-fever when exposed to the tick has been 
estimated at $5,812,500 per annum. 

The deaths from Texas-fever of pure-bred or high-grade cattle im- 
ported from the North for breeding purposes amount to about sixty 
per cent, among such cattle which have not been immunized by blood 
inoculations, and to about ten per cent, among those which have had 
such immunization. Since these are usually expensive animals, the 
loss in such cases is often excessive. 

Considering additional losses, direct or indirect, as published by the 
United States Department of Agriculture in 1914, it will be found that 
the Texas-fever tick is responsible for a loss of about $40,000,000 an- 
nually, in addition to which it is responsible for lowering the assets of 
the infested country to the extent of $23,250,000. 

Progress in Eradication. — Methods of dipping and pasture rotation 
for the control of the cattle tick have been fully set forth in bulletins 
and circulars published by the United States Department of Agriculture 
(Farmers' Bull. No. 498). These are freely available to all interested in 
details of the subject which need not be repeated upon these pages. 

Eradicative measures carried on by the Federal Government in 
cooperation with the states affected by the cattle tick have seen in 
progress since 1906. Up to 1911 twenty per cent, of the infested area, 
mostly along the northern boundary, had been cleaned through this- 
systematic cooperative work. At the. present time (1918), through the 
continuation of this work, fifty-two per cent, of the tick-infested area 
has been released from quarantine, and it is authoritatively predicted 
that five years hence the cattle tick will be entirely eradicated from the 
South. 



THE TICKS d 

Order II. Lixguatulida 



15S 




Arachnida (p. 94). — The iiiombers of this group are arachnids which 
have become extremely altered in consequence of their parasitic mode 
of life. Due to their worm-like body and endoparasitic habits, they were 
formerly placed with the helminths. 

The body is elongated, annulated, and somewhat flattened. The 
bodj' regions are not defined from each other. With the exception of 
two pairs of articulated hooks 
surromiding the mouth, re- 
garded by some as vestigial 
legs, the adult body is entirely 
without appendages (Fig. 83). 

The mouth is anterior, and 
the intestine passes directly 
through the body, opening by 
the posterior anus. 

There are no circulatory or respiratory organs 
general surface of the bod.y. 

The nervous system is reduced, consisting of the esophageal ring, 
which gives off filaments to the cephalothorax region. Eyes are absent. 

The sexes are separate; the male much smaller than the female. From 
the eggs there hatches an ovoid embr^'o, constricted at its posterior 
extremity, and provided with two pairs of jointed legs. Anteriorly it 
has a perforating apparatus by means of which it bores through the 
intestinal wall of its host and reaches the liver, or other organ, in which 
it becomes encysted. 

The adult Linguatula (L. rhinaria) infests the nasal cavities of mam- 
mals, usually the dog. The larvae infest the visceral organs of herbivor- 
ous animals. 



Fig 83. — Linguatula rhinaria, adult (after 
Osborn, from Packard; Bull. No. 5, Bureau of 
Entoniologj-, U. S. Dept. of Agr.). 



Respiration is by the 



PART II 
THE INTERNAL PARASITES 

CHAPTER XIV 

PHYLUM 11. PLATYHELMINTHES. THE FLUKES AND 
TAPEWORMS 

With but few exceptions all of the metazoan internal parasites come 
into the old division \>rmes, which brings together animals generally 
worm-like, though widely differing in many respects. Compared thus 
as a whole with animals usually rated below them in the zoological 
scale, .worms are readih' distinguished in possessing differentiated 
anterior and posterior extremities, the anterior directed toward their 
forward movement and involving a head which contains a ganglionic 
mass of nerve cells or, as it ma}' be called, a rudimentary brain. Fur- 
thermore, the body is bilaterally similar, and there is a dorsal and 
ventral surface. The annulated worms, which include the higher 
representatives, differ from the Arthropoda mainly in the absence of 
articulated appendages to their body-segments, while the lack of a 
notochord and gill-slits distinguishes them from certain lowly members 
of the Chordata. Beyond these few points there is little to be said as 
to the characteristics of the worms considered as a whole. 

The including in a single phylum of all invertebrates generally elongate 
and without articulated appendages is systematically faulty in that it 
brings together animals with structural differences of grand division 
importance, though agreeing in an external form generally worm-like. 
In most of the present-day systems of classification the worms are dis- 
tributed into three, or at least two, phyla, the older class division 
Platyhelminthes, or flat worms, being given grand division distinction. 
Many authors also place the smooth-bodied Nemathelminthes and the 
annulated worms in separate phyla, while another division, — the 
Molluscoidea, has been created to dispose of the more or less related 
moss-like Pol^'zoa (Bryozoa) and the mollusc-like Brachiopoda. An 
objection to such arrangement is that groups poor in species, some of 
them mainh' of parasitic interest, are placed on the same basis as such 
large and very important divisions as the chordates and arthropods, 
thus giving them an undue prominence in a general consideration of the 
animal kingdom. 



156 PARASITES OF THE DOMESTIC ANIMALS 

The classification adopted here places the smooth roundworms and 
the annulated worms together in the phylum Ccelhelminthes, an ar- 
rangement based upon the presence of a coelom or bod}^ cavity, which 
is a structural feature clearly defuiing these worms from the Platyhel- 
minthes and establishing a relationship between the smooth round and 
annulated forms of primary importance. 

The Platyhelminthes includes worms which are flattened dorsoven- 
trally, the two surfaces uniting in more or less sharp margins. There is 
no body cavity, the various organs being embedded in a mass of con- 
nective tissue and muscle fibers. The aHmentary tract is a simple or 
bifurcated, sometimes branching, pouch having no anal opening (Fig. 85), 
the inouth serving as both inlet and vent. In some parasitic 
forms (t|ipeworms) alimentary organs are entirely wanting. 
A true circulatory system is absent. There is a series of ex- 
cretory tubes which ramify throughout the body, usually 
opening to the outside near the posterior extremity. The 
nervous system consists of ganglia located above the esoph- 
agus, where this is present, and the lateral nerves which these 
give off. Most all are hermaphroditic, the sexual organs 
being distributed over a large portion of the body. 

As is true of the worms in general, free living forms are 
found in fresh and salt water. They may often be revealed 
clinging to the under side of rocks (planaria. Fig. 84) and 
upon the moist soil, some of these specimens being nearly 
transparent. The largest members of the division are the tapeworms. 
^^'hich may reach a length of thirty feet or more. 

The phylum contains two parasitic classes, as follows: 
Class I. Trematoda. — The flukes. 
Class II. Cestoda. — The tapeworms. 

Class I. Trematoda 

Platyhelminthes (p. 156). — All of the members of this group are 
parasitic, living either as ecto- or entoparasites. The body is usually 
leaf-like, often much like a pumpkin seed in form (Fig. 87), and is pro- 
vided anteriorly with suckers by which attachment is made to the host. 
In most of those entoparasitic (Distomese) two suckers are present, one 
anterior and surrounding the mouth, and a second larger one just 
posterior to the mouth on the mid-ventral line. In the ectoparasitic 
species (Polystomese), which are usually parasitic upon the gills and 
skin of aquatic animals, the suckers are more numerous. 

The alimentary tract leads by a short gullet to a bifurcation, forming 
two elongated blind sacs which may or may not give rise to lateral 
secondary pouches (Fig. 85). Eye spots occur in some of the ectopara- 
sitic species and in the larvae of the entoparasitic. 




PLATYHELMINTHES 



157 



Most of the Trematoda are hermaphroditic. At maturity the sexual 
organs reach a high degree of development adaptive to the mode of 
parasitism (Introduction, p. 5). The male sexual organs consist of 
tube-like testes, from which spermatic ducts take origin. These unite 
in a large seminal vesicle, the terminal portion of 
which is usually inclosed in a pouch. The ovary 
is also branching and tube-like. With the oviduct 
there unite ducts from the vitellaria or yolk-glands, 
this union being followed bj' the much convoluted 
uterus which receives the eggs and terminates by 
the side of the male sexual opening (Fig. 86). 

The entoparasitic trematodes undergo a compli- 
cated life histor}', invohang alternation of hosts 
and, within the intermediate host, multiplicative 
generations. A typical example of this cycle is 
given further on in reference to the species Fasciola 
hepatica. 

Most of the trematode parasites of mammals 
live in the liver, producing the affection known as 
hepatic fascioliasis (distomiasis), or commonly as 
liver rot. Others invade the blood, lungs, and 
stomach, causing, accordingly, vascular, pulmonary, 
and gastric fascioliasis. The latter forms are rarely 
met with in the United States. 

The species to be considered come imder three 
families, as follows: 

Famih' I. Fasciolidae. — The common liver flukes. 

Family II. Amphistomidse. — Of the rumen. 

Familv III. Schistosomidae. — The blood fluke. 




Fig. So.— Sketch of 
Fasciola hepatica, 
showing bifurcated and 
branching alimentary 
tract: si, mouth and 
anterior sucker; s2, 
posterior sucker; t. a., 
alimentary tract, — en- 
larged (after Boas, by 
Kirkaldy and Pollard, 
from Thomas). 



Classification of Parasites of the Phylum Pl.\tyhelmixthes 

Phylum II. Platyhelminthes. P. 155. 
Class A. Trematoda. Flukes. P. 156. 
Order 1. Distomese. P. 156. 
Family (a) Fasciolidae. P. 160. 
Genus and Species: 

Fasciola hepatica. Hosts, sheep, cattle, etc. P. 160. 
Dicroca^lium lanceatum. Hosts, same. P. 160. 
Fasciola americanus. Hosts, same. P. 160. 
Family (b) Schistosomidae. P. 168. 
Genus and Species: 

Schistosoma bovis. Ho.sts, cattle, sheep. P. 168. 
Family (c) Amphistomidse. P. 167. 



1.58 PARASITES OF THE DOMESTIC ANIMALS 




Fig. 83. — Reproductive organs of liver fluke: f, female aperature; s. v., seminal \'esicle 
y. g. 1., diffuse yolk glands; sh. g., shell gland; v. d., vas deferens; T., testes; ov, ovary 
(dark); ut, uterus; c. s., cirrus sac; p, penis; m, mouth; g, anterior lobes of gut (after 
Thomson, from Sommer). 



PLATYHELMINTHES • 159 

Genus an(J Species: 

Ainphistomiim cervi. Hosts, niniinants. P. 167. 
Class B. Cestoda. Tapeworms. P. 169. 
Order 1. Polyzoa. 

Family (a) Taeniidae. P. 170. 
Genus and Species: 

Anoplocephala perfoliata. Host, equines. P. 174. 

A. mamillana. Host, equines. P. 175. 

A. plicata. Host, equines. P. 175. 

Moniezia expansa. Hosts, cattle, sheep, goats. P. 176. 

M. alba. Hosts, same. P. 176. 

M. planissima. Hosts, same. P. 176. 

Thysanosoma actinioides. Host, sheep. P. 176. 

Dipyhdium caninum. Hosts, dog, cat, man. P. 178. 

Larva, Cryptocystis trichodectes. Hosts, flea, louse. 
P. 178. 
Taenia hj-datigena. Host, dog. P. 178. 

Larva, Cysticercus tenuicollis. Hosts, ruminants and 
hogs. P. 179. 
T. pisiformis. Host, dog. P. 179. 

Larva, Cysticercus pisiformis. Host, ral)])it. P. 179. 
T. ovis. Host, dog. P. 204. 

Larva, Cysticercus ovis. Host, sheep. P. 203. 
Multiceps multiceps. Host, dog. P. 179. 

Larva, Multiceps nuilticeps. Host, Herbivora. P. 179. 
M. serialis. Host, dog. P. 179. 

Larva, Multiceps serialis. Hosts, rabbit and other 
rodents. P. 180. 
M. gaigeri. Host, dog. P. 181. 

Larva, Multiceps gaigeri. Host, ruminants. P. 181. 
Echinococcus granulosus. Hosts, dog, cat. P. 181. 

Larva, Echinococcus granulosus. Hosts, riuninants, hog, 
etc. P. 181. 
Taenia taeniaeformis. Host, cat. P. 184. 

Larva, Cysticercus fasciolaris. Hosts, rat, mouse. P. 184. 
Cittotaenia denticulata. Host, chicken. P. 185. 
Choanota^nia infundibuliformis. Host, chicken. P. 189. 

Larva, a cysticercoid. Host, house fly. P. 189. 
HjTiienolepis carioca. Host, chicken. P. 190. 
Davainea tetragona. Host, chicken. P. 190. 
D. cesticillus. Host, chicken. P. 190. 
D. echinobothrida. Host, chicken. P. 191. 
D. proglottina. Host, chick(>n. P. 191. 
Larva, a cvsticercoid. Host, snail. P. 191. 



160 PARASITES OF THE DOMESTIC ANIMALS 

Taenia saginata. Host, man. P. 195. 

Larva, Cysticercus bovis. Host, ox. P. 195. 
T. solium. Host, man. P. 199. 

Larva, Cysticercus cellulosse. Host, hog, etc. P. 199. 
Family (b) Diphyllobothriidse. P. 185. 
Genus and Species: 

Diphyllobothrium latum. Hosts, man, dog, cat. P. 185. 
Larva, a plerocercoid. Host, fish. P. 185. 



Family I. Fasciolid^ 

1. Fasciola hepatica (Distomum hepaticum). The Liver Fluke 

(Fig. 87). Trematoda (p. 156). — ^The body is flattened, pale brown in 
color, oval in shape, and broadest in front, where it is terminated by 
a conical process bearing at its apex the oral sucker which surrounds 
the mouth. A larger ventral sucker is situated about 3 mm. behind 
the oral. The cuticle is studded with minute spines directed back- 
ward. The bifurcations of the ahmentary tract have ramifying 
branches. The vulva is situated beside the male opening or a little 
behind it. 

Length, 20-30 mm. {%-\H inches); width, 10-13 mm. (73-3^ an 
inch). 

The eggs are brown or greenish-yellow, provided with an operculum 
a,t one end. They are oval and 130-145 microns in length. 

2. Dicrocoelium lanceatum (Fasciola lanceolata). The Small Liver 
Fluke (Fig. 87). Trematoda (p. 156).— The body is slender and 
lancet-shaped, mottled brown by contained ova. The integument is 
smooth and semi-transparent. The intestine has two nonramifying 
branches. 

Length, 4-9 mm. (3/16-3/8 of an inch); width, 2.5 mm. (1/8 of an 
inch) . 

The eggs are oval, brownish in color, 37-40 microns in length, and 
provided with an operculum. 

3. Fasciola magna (F. americana, Distomum americanum, D. mag- 
num). The Large American Liver Fluke (Fig. 87). Trematoda 
(p. 156). — Similar to F. hepatica, but larger, measuring 25-33 mm. 
(1-13^ inches) in length and 12-17 mm. (J^-^) of an inch in 
width. 

Life History of Fasciola hepatica. — The eggs leave the uterus be- 
fore the beginning of embryonic development and pass to the outer 
world by way of the bile ducts and intestines. In heavy infestation 
enormous numbers may be passed by a single host animal, one mature 
fluke producing in the neighborhood of one hundred thousand eggs. 




PLATYHELMINTHES 161 

After a period of embryonal development, which will only occur pro- 
viding the eggs have reached water and suitable conditions of tempera- 
ture, the larva escapes by the lifting of the operculum of the shell. It 
is then in the stage of the miracidium (Fig. 88, 2), an infusorian-like 
organism, cihated, elongated, broader in front, and about 130 microns in 
length. During its free-swimming period it must meet with a suitable 
host within a few hours or it will perish. This host is a small snail, 
usually of the genus Limnjea (L. 
humilis) into which the larva 
bores its way by a perforating 
rostrum at its anterior extremity. 
If it escapes its aquatic enemies 
during this free stage and arrives 
at a suitable location within the 
snail, usually the pulmonary 
chamber, the larva loses its cilia 
and digestive tube and becomes 
transformed into a sporocyst (Fig. yig. 87.-Left to right, Fascioia hepatica, 

88, 3) — a sort of reproductive sac, F. americanus, Dicroccelium lanccatum; 

ovoid in form and acquiring a l^^^lf ^'^^ ^'^'■''^^^"" ^'""^ ^"*^°'"'^ ^p^"" 
length of about 0.5-0.7 mm. The 

cyst now becomes filled with germ-cells which are disposed in masses 
(morula) ordinarih' five to eight in number. 

The masses of germ-cells become transformed into so manj- redice 
(Fig. 88, 5 and 6) which may be seen in different stages within the cyst. 
The rediae are cylindrical in form and have a simple intestine and 
pharynx with lips turned out like a sucker. When they have attained 
a certain stage of development the rediae become actively motile, finally 
rupturing the maternal cyst and passing to another organ of the snail, 
usually the liver, in which location Xhey grow to a length of 1.3-1.6 mm. 
Within the body of the redia are germ-cells formed into six to ten cellular 
masses which are to be transformed into so many daughter rediae, or 
directly into fifteen to twenty cercarice (Fig. 88, 7). Both daughter 
rediae and cercariae leave the mother redia by a birth-opening located 
anteriorly. 

The developed cercaria has an oral and ventral sucker, a muscular 
pharynx, and a bifurcated intestine which is as yet without lateral 
branches. It has a flat oval body about 0.28 mm. in length, provided 
with a long actively vibratile tail. The cercariae escape from the snail 
and swim about energetically ui the water, eventually finding their way 
to an aquatic plant or grass stalk. Here the tail is lost and the cystoge- 
nous cells of the body form a mucoid substance which serves both to 
encyst the cercariae and to attach them to the grass. The cysts may be 
observed upon the specimens of vegetation as little white points about 



162 PARASITES OF THE DOMESTIC ANIMALS 



the size of an ordinary pin-head. An encysted cercaria will remain alive 
for an extended period as long as the grass upon which it is lodged is 




Fig. 88. — Life history of liver fluke: 1, egg containing de- 
veloping embryo; 2, free swimming miracidium; 3, sporocyst; 
3a, snail of the genus Limnaea; 4, division of sporocyst; 
5, sporocyst containing developing redise; 6, redia with cer- 
carise or more redise developing within it; 7, cercaria; 8, young 
fluke (after Thomson, from Thomas). 

supplied with moisture. Drought probably destroys it, though the 
length of time it may survive such conditions is undetermined. 
When plants bearing these cysts are eaten by grazing animals the 



PLATYHELMINTHES 163 

cysts, upon reaching the stomach, are dissolved, setting free the par- 
asites which, passing to the intestine, enter the bile ducts and there 
become mature. After laying their eggs the majority of the flukes pass 
down the bile ducts to the mtestine where, under the hifluence of the 
digestive juices, they shrivel and die. 

The period of time occupied ])y the entire cycle is so influenced by 
climatic conditions that no definite estimate as to it can be given. 
As a rough approximation, twelve weeks may be given as about the 
time required under such favorable conditions as usually prevail during 
the summer season. 

The life histories of Dicrocoelium lanceatum and Fasciola magna are 
probably essentially similar to that of F. hepatica, but are as yet not 
definitelv known. 



Tabular Review^ of Life History of Fasciola Hepatica 
Adult Fluke. — In bile duct of liver of rmninant. 

I 
Egg.— Free. 

I . 
^liracidium. — Free. 

I 
Sporocyst. — In puhnonarj' chamber of snail. 

I ^1 

Sporocysts 5 to 8 Redise. 

[ I 
Redise. — In liver or other organ of snail. 

Daughter Rediae 15 to 20 Cercarise 

Cercarise. — Free. 



I 
Cvsts. — Upon grass stalks or other vegetation. 

Adult Flukes. — In bile duct of Uver of ruminants after 
ingestion of c^'sts. 

Prevalence. — The loss from hepatic fascioliasis in England was for 
a time in the neighborhood of three million head of sheep annually. 
It was principally for this reason that investigations were made by 
which the life history of the parasite was determined, and by which 
was revealed the essential alternation between the sheep and snail 
host. This pointed the way for measures of control consisting mainly 
in the elimination of snails by the drainage of pastures or in the limiting 



164 PARASITES OF THE DOMESTIC ANIMALS 

of the sheep to pastures free from standmg water or overflow. Since 
the adoption of such preventive measures the loss from this source in 
England and other European countries has been greatly reduced. 

While fascioKasis has not been as prevalent in the United States as in 
Europe, there are a sufficient number of cases to demonstrate the pos- 
sibility of its becoming so unless such precautions are taken as are in- 
dicated by the life historj^ of the fluke. Probably the freedom from such 
destructive prevalence has been largely due to the fact that in this 
countrj', more generally than in Europe, it is the practice to turn sheep 
upon higher and diyer pasturage. 

The three species of flukes which have been mentioned mfest the 
liver, therefore the hepatic form of fascioliasis is the most important. 
As would be concluded from the mode of infection, herbivorous animals 
are most often affected, those which crop the grass close to the ground, 
as sheep and goats, being for this reason especially susceptible. Horses, 
swine, Carnivora, and even man may be invaded incidentally by flukes, 
though in such cases they are rarely present in such numbers as to produce 
perceptible disturbance. The giant fluke {Fasciola magna) is most often 
found in the liver of deer or cattle in the Southwestern portion of the 
United States. It is supposed to be a species native to wild rummants 
before the introduction into this country of those in domestication. 

Infection. — While infestation of sheep most frequently occurs from 
the ingestion of plants upon which the encysted cercarise are attached, 
water contaminated with detached cercariae may infect directly, or by 
vegetation over which it has washed. It is probable that many cases 
in cattle in the United States result from the introduction of the flukes 
by the latter means. Cattle are not as close grazers as sheep, but the}- 
drink more frequently, often from shallow collections of water which 
may contain larvae derived from the excrement of sheep or rabbits. 

As many encj^sted cercariae survive the frosts even of the late fall, 
the season during which infection may take place is somewhat extended, 
some investigators claiming that it may occur at any time of the year. 
However, warmth being highly favorable to the development of the ova, 
it is essentially during the summer and early autumn that animals are 
most likely to become invaded. It is obvious that the most numerous 
and most severe cases would occur in seasons of copious rainfall, more 
elevated pastures at such times affording by their collections of water 
and overflow favorable conditions for the development of the parasites. 
The flukes may be introduced into lands previously free from them 
by new stock, or by wild herbivorous animals, such as deer and rabbits. 
After infestation has once taken place, it will, through successive in- 
fections, mcrease in degree the longer the pasture is used. 

Migrations and Pathogenesis. — It is probable that the migration 
of the parasites from the small intestine into and along the bile ducts 



PLATYHELMINTHES 165 

is accomplished by the extending forward of the parasite's anterior 
end, with alternate fixing of the oral and ventral sucker.- The majority 
remain in the bile ducts, though some upon reacliing the smaller ducts 
break through and pass into the liver tissue where they msiy excavate 
and destroy large areas. Such migrations may extend through Ghsson's 
capsule to the serous covering of the organ and thus give rise to per- 
itonitis in addition to the inflammation of the hepatic parenchj-ma. 
They do not essentially remain confined to the liver, but may pass 
through the capsule and serosa into the peritoneal cavity. Others may 
reach the ramification of the portal vein and set up an endophlebitis 
with accompanying thrombosis and embolism; or the hepatic veins may 
be involved and some flukes be carried by the blood current to the 
thoracic organs. 

The destruction of liver tissue in hepatic fascioliasis is largely the 
result of direct irritation due to the spiny processes covering the par- 
asites. During the first few weeks after being taken up by the host the 
flukes are small and do not cause a serious irritation. Later the}' set 
up an acute inflammatory condition of the bile ducts and liver tissue, 
the hepatitis remaining more or less localized or becoming generalized 
according to the number of parasites present and the extent of their 
migrations. In certain cases there is abscess formation, or hemorrhages 
may occur due to the breaking down of the walls of blood vessels. The 
inflammation running a chronic course is associated with connective 
tissue prohferation, causing a thickening of the walls of the ducts. Later 
this process extends to the interlobular connective tissue and brings 
about cirrhosis of the liver. 

Flukes which have remained in the bile ducts pass back into the 
duodenum soon after the reproductive function has been accomplished. 
It is thought by certain investigators that the period of time which 
the}' remain in the ducts does not exceed nine to twelve months. Within 
the intestines they are much altered b}' the intestinal juices and pass 
from the host with the excrement. z 

6 -' 

Fascioll\sis of Sheep ^^---^ 

Symptoms and Course. — An animal harboring but few flukes will 
give no evidence of functional disturbance. This can be readily dem- 
onstrated in sheep-slaughtering establishments where moderately in- 
fested livers have been repeatedly found in sheep in prime condition. 
In heavier infestations a developing period of about three to six weeks 
intervenes between the taking up of the flukes and the appearance of 
s>'mptoms. 

In sheep usually the first s\aiiptom to be noticed is dullness, man- 
ifested b}' slowness of movement and an inclination to lag behind the 



166 PARASITES OF THE DOMESTIC ANIMALS 

flock. On examination of the visible mucosae (conjunctiva) and inner 
surface of the ears they will be found to be paler than usual, and there 
ma}' already be edematous swelling of the eyelids and under the brisket. 
Notwithstanding the anaemia, the general phj'sical condition of the 
animal may still be good; there is, in fact, a tendenc}^ to fatten, which 
ma}^ be explained phj'siologicalh' in the increased assimilation of the 
fat-forming elements of the food, brought about by the stimulationim- 
parted by the flukes to the flow of bile. 

This stage, however, is soon followed b}- a marked increase in dullness 
and a disinclination to take food. The animal ruminates slowly and 
irregularly, the fleece becomes chy and brittle, and in places may loosen 
and drop out ; the skin and mucosae are whitish-yellow in color, the puffy 
conjunctiva forming a prominent ring about the cornea. Though the 
gheep ma}' still be fat, weakness and disinclination to resist handling 
become moi'e pronounced. With progressiveh' diminished appetite, 
however, there is loss of flesh, and the edema of the dependent parts 
increases, involving the lower part of the neck, throat, and cheeks. The 
presence of ascites is evinced upon percussion of the pendulous abdomen, 
and the respiration becomes labored and frequent. 

With these s\anptoms, which generalh' appear about the third month 
after infestation, the disease is at its maximum, usually reached in the 
early winter inonths. The anaemia, edema, and cachexia have now 
become more pronounced ; in most of the advanced cases there is diarrhea 
by which large numbers of eggs may be distributed about. Finally, 
in a condition of extreme emaciation and weakness, the animal dies. 

Prognosis. — ]\Iost of the losses from fascioliasis of sheep are among 
the lambs. Older animals and those but moderately infested gradually 
recover with the passage of the flukes from the liver into the intestine, 
this usually occurring in the early spring. With the disappearance of 
the edematous swellings and the return of the appetite, the animal re- 
sumes a good physical appearance and seems to completely recover. 
The hver lesions, however, will not entirely heal, and, impairing the 
function of the organ, will eventually have a deleterious effect upon 
the animal. 

, Fascioliasis of Cattle 

In cattle fascioliasis presents the same s\'mptoms as in sheep. Due 
to the greater resistance of these animals, however, the effects are much 
less severe and maj^ often pass unperceived. If the flukes are numerous 
there maj^ be digestive disturbances manifested b}- loss of appetite, 
diarrhea, and t^-mpanites; very rarely there are edematous swellings in 
the dependent parts of the body. Fatalities from fascioliasis are rare 
among cattle. When they occur it is usualh' among calves which have 
reached an advanced emaciation. 



PLATYHELMIXTHES 167 



Family II. Amphistomid.e 

Amphistomum cervi {A. conicum) is a species belonging with this 
family not infrequently found in the rumen of domestic ruminants of 
this and other coimtries. Specimens collected in the Penns3'lvania State 
Laboratory measure 6 to 7 mm. (3/16 to 1/4 of an inch) in length. The 
body is conical m form, thick, attenuated anteriorh', gradually en- 
larging posteriorly, the posterior end being obtuse and a little curved 
ventral ly. The mouth is terminal and surrounded by a small sucker. 
At the thickened posterior extremity there is a second and much larger 
sucker. The color is white or reddish, darker at the attenuated anterior 
portion. Hermaphroditic; genital orifices ventral and median, situated 
in the anterior third of the body. Its development is not known. 

This fluke is a parasite in the rumen of the ox and other domestic 
and wild ruminants. It fixes itself by means of its posterior sucker 
between the papillae of the rumen. Being very easily overlooked in its 
resemblance to the papillae, it is quite probable that it is more prevalent 
than would appear from our present records. 

The parasite has been considered as inoffensive to the health of the 
host animal. 

Control of Fascioll\sis 

In sections where fascioliasis has appeared a prophylactic measure 
of first importance is the avoidance of pastures which are wet or contain 
collections of water affording habitation for snails. The following direc- 
tions formulated b}' Thomas — as stated by Neumann — for limiting the 
ravages of fasciohasis are here quoted m part : 

"a. Destroy the diseased sheep and bury them. 

"b. Only put on dvy pastures affected sheep intended for the butcher, 
as the fluke ova they evacuate cannot develop in the absence of humidity. 

"c. As hares and rabbits — which are sometimes bearers of distomes — 
may infest pastures, they should not have access to those on which 
sheep graze. But this recommendation cannot well be carried out. 

"d. Drain wet pastures, or, if this cannot be accomplished, dress 
them with salt or lime. The latter in solution — 0.75 per cent. — will 
destroy fluke embryos as well as the snails. With regard to salt, we are 
indebted to Perroncito for some precise notions as to its action. Erco- 
lani had for a long time observed that water slightly impregnated with 
salt killed the cercariae, and in acting on these and on the encysted 
larvae of the Limncea palustris. Perroncito found that in a 2 per cent, 
solution these parasites died in less than five minutes; in a 1 per cent, 
solution they rolled themselves up at the end of two to seven mmutes, 
and perished after twenty to thirty-five minutes. The same happened 
in 0.64 per cent, solutions: and in those of 0.25 per cent, they were still 



168 



PARASITES OF THE DOMESTIC ANIMALS 



alive after more than twenty hours. The period when salt or lime 
should be spread on the pastures should coincide with the time when 
the embryos of the distomes and the cercarise abound — that is, June 
and July for the first, and August for the second." 

If it is impracticable to keep sheep from land upon which conditions 
are favorable for the development of flukes, they should each be given 
in the morning daily two drams of salt mixed with feed. When possible, 
the salt may also be given in their drinking water in the proportion of 
0.5 per cent. The salt is fatal to the ingested cercarise and tends to 
fortify the sheep b}' favoring digestion and assimilation. 

Treatment. — No effective therapeutic agent for fascioliasis has as 
yet been found. Owing to the remote location of the parasites, it is 
hardly likeh' that anything could be given which would affect them. 



BiLHAKZIOSIS 

This name has been given to a disease of cattle and sheep caused by 
the blood fluke Schistosoma hovis {Bilharzia bonis; B. crassa) of the family 
Schistosomidse. 

In this trematode (Fig. 89) there is presented the pecuharity of sep- 
arate sexes. The female, longer and much nar- 
rower than the male, is filiform, 18-20 mm. {% 
of an inch) in length, and has a buccal and ven- 
tral sucker. The male is cylindrical, about 14 mm. 
{}/2 an inch) in length, and has two suckers. It 
carries the female in a ventral furrow formed by 
the two sides of the body which are broad and 
reflected inward. Both male and female genital 
apertures are situated immediately behind the 
ventral sucker. 

The eggs are elongate, and at one pole termi- 
nate in a pyriform point. They pass from the 
host with the feces and urine, and, in the presence 
of water, set free a ciliated embiyo. 

This parasite has been found in the portal and 
abdominal veins of cattle of tropical and sub- 
tropical countries. The parasites themselves 
seem to do but little injury. The eggs, however, 
by their accumulation and sharp points, may 
rupture the capillaries. If these are of the 
genito-urinary system, the chief s\nnptom is a bloody urine. Where 
the eggs have accumulated in the capillaries of the bladder, they rup- 
ture these and, passing through the mucosa, fall into the cavity of the 
organ. The resulting cystitis is manifested In' the hsematuria and the 




Fig. 89. — Schistosoma 
bovis, male and female, — 
enlarged. 



PLATYHELMINTHES 169 

pain which accompanies micturation. If the parasites are contained 
in the veins of the rectum, there are similar lesions in this organ; the 
feces may be stained with blood, and there is a condition somewhat re- 
sembling piles. 

Diagnosis is best made by a microscopic examination of the urine 
to determine the presence of the eggs which may be readily recognized 
by their characteristic elongate shape and polar termination in a sharp 
point. 

As the lesions are produced by the eggs, the severity of the symptoms 
will essentially depend upon the number of parasites present. In the 
majority of cases the infection is light and may give rise to no more than 
a slight chronic C3^stitis. In the more rare cases of severe infection death 
may ensue from rupture of the bladder or from uraemia accompanying 
an acute nephritis. A heav}^ intestinal infection may bring about an 
exhausting and fatal dysentery. 

It is probable that infection has its source in contaminated drinking 
water. Therefore, where bilharziosis has made its appearance, the water 
should, as a preventive measure, be filtered, or the cattle removed to an 
un contaminated supply. 

Treatment can only be applied to the relief of sjaiiptoms as they 
appear. 

Class II. Cestoda 

Platyhelminthes (p. 156). — An important character of the cestodes 
is that, as a result of their advanced parasitism, they have lost the last 
trace of an alimentary canal, and obtain their nourishment by absorp- 
tion through their integument of the partly digested food of the host. 
Also markedl}^ distinguishing them are the two developmental stages, — 
the bladder worm (Fig. 112, h and c) and the mature worm (Fig. 107) 
with its sexuall}^ developed segments, the first living usually in tissues, 
such as muscular, liver, nervous, and serous, of the intermediate host; 
the second in the alimentary tract of the definitive host. The adult is, 
in its general form, band-like, and consists of two parts, — the scolex 
(Fig. 109), which is generally referred to as the head, and a series of 
segments which are formed from the scolex asexually by longitudinal 
growth and transverse segmentation. It is due to this fact that an 
animal is not rid of its tapeworm so long as the head is retained in the 
intestine. As the segments are pushed on by the formation of younger 
segments at the scolex, they become progressively wider and longer, 
the width of the younger ones usually much exceeding their length, 
while the oldest, which are those most distant from the scolex, may 
become longer than wide. Each mature segment is hermaphroditic, 
the uterus usuall}^ containing a large numl)er of eggs. In the Taeniidae 
the genital pores (sexual openings) are on the margin or margins of the 



170 PARASITES OF THE DOMESTIC ANIMALS 

individual segments. In the Diphj'llobothriidae they are on the flat 
ventral surface. The number of segments varies from three or four 
(Echinococcus granulosus) to several thousand (Diphyllobothrium latum), 
a fact which gives to some species an enormous size. In the head is a 
cerebral ganglion from which two principal nerves run backward, 
usualh' near the lateral margins of the segments. An excretory, or so- 
called water-vascular system, extends through the whole length of the 
worm by two principal trunks which may be connected by vessels 
running across the posterior margin of each segment, the system ter- 
minatmg at the hinder edge of the last. 

Of the Cestoda, two families are to be described as containing species 
parasitic to domestic animals and man. These are as follows: 

Family I. Taeniidse. 

Family II. DiphyllolDothriidae. 

Family L T.exiid.e 

Cestoda (p. 169). — With rare exception, this family includes all of 
the tapeworms of domestic animals and man in the United States. Its 
members have the head furnished with four round or oval cup-like 
suckers of muscular structure (Fig. 109), which, by their contraction, 
produce a vacuum affording a close attaclmient to the intestinal mucosa 
of the host. These suckers may surround a prominence, — the rostellum 
(Fig. 95), or in other cases a depression more or less marked. The 
rostellum may or may not be contractile, and may or may not be armed 
with hooks. 

As a typical, though not constant, arrangement of the reproductive 
organs, those of the species Tcenia saginata, a tapeworm of man, are here 
described. Each sexuall}' mature segment (Fig. 90) of this worm has 
at its margin a protruding genital pore, which, from segment to segment, 
is irregularh' upon alternate sides. This protuberance contains a 
cloaca-like cavity into which open the vas deferens and vagina, both of 
which extend laterally to the middle of the segment. Here the vas 
deferens divides into a number of seminal ducts which are distributed 
through the supporting tissue and serve to carry the semen from the 
small spherical testes which are located almost everywhere in the seg- 
ment. As it approaches the lateral cloacal sac, the duct becomes con- 
voluted and much distended with the accmnulated seminal fluid. In the 
vicinitA' of the cloaca it develops into a cirrus (penis) which is inclosed 
in a muscular sheath. 

The vagina bends downward as it passes toward the center of the 
segment where it unites with the paired wing-like ovaries which are 
rather large organs consisting of branched tubules. In the posterior 
and middle portion of the segment is a single organ, hkewise of branched 



PLATYHELMINTHES 



171 



° «t 
"o •: 



tubular structure, — the viteUarium or yolk-gland, the secretion from 
which surrounds the eggs in the cavity of the shell-gland, the latter a 
small bod}^ consisting of compacth' arranged gland-cells and located 
just above the vitelline gland. From the shell-gland the eggs pass 
through a narrow duct into the uterus, a simple tubular organ ascending 
directly in the middle of the segment and closed at its distal end. The 
uterus becomes much dis- 

l 



tended from the accumulation 
of eggs and develops nu- 
merous lateral branches to 
which the other sexual organs 
gradually give place until lit- 
tle remains of them but ves- 
tiges of the vas deferens and 
vagina. The egg-engorged 
organ, with its lateral cecal 
pouches, may rupture, or the 
integument of the segment, 
itself may give wa}', permit- 
ting the eggs to escape directly 
into the intestinal contents. 
A§ a rule these terminal or 
''ripe" segments are passed 
to the outside of the body of 
the host with the feces where, 
by their disintegration, the 
eggs are set free. 

The eggs of cestodes are 
globular or more or less oval 




11 ^/<j^ 







Fig. ',)0. — SeKineut of TiPnia saginata, with 
sexual organs matured. Ovaries in lower portion 
to right and left; yolk gland in extreme lower 
portion; shell gland between yolk gland and ova- 
ries; uterus, tubular organ extending upward; 
vagina, extending from glands to genital pore at 
left margin; testis, bodies distributed throughout 
segment; vas deferens, convoluted organ extend- 
ing laterally to genital pore. Excretory vessel 
united by transverse commisures. Lateral longi- 
tudinal nerves shown by heavy lines. 



in shape and are provided with shells of variable thickness (Figs. 96 
and 110). Beneath the shell is a translucent yolk which surrounds an 
inner covering containing the onchosphere (hexacanth) or six-hooked 
embryo (Fig. 112, a). In some forms the eggs as found in the feces 
often have the outer shell absent. 

Life History. — Species of Taeniidse in which the development is 
known undergo a complex series of metamorphic changes, involving 
larval and sexually mature parasitism in hosts of differing species. 
After the egg, either free or with the segment entire, has been ingested 
by a proper larval host, the shell and embryonic envelope are digested 
away by the gastric juices, and the onchosphere is freed (Fig. 112, a). 
At this stage the embrA'o is provided with three pairs of booklets by 
which it penetrates the intestinal wall and, probably by blood and 
l>auph currents, may be carried to certain parts of the body specifically' 
essential to its further development. Thus passively lodged, it loses 



172 PARASITES OF THE DOMESTIC ANIMALS 

its booklets and commonly becomes smTOunded by a capsule formed by 
proliferation of the connective tissue of the host, though this does not 
occur in all of the larval forms. 

At this stage the larva, which is now a mere vesicle containing more 
or less fluid and as yet without a head, is referred to as the acephalocyst 
(bladder-cyst), from which there may, in certain forms (echinococcus), 
develop multiple daughter cysts (Fig. 117). By a process of budding 
from the germinal wall, the acephalocyst now develops a further stage, — 
the cephalocyst (proscolex. Fig. 112, b and c), containing one (cysticercus, 
Fig. 107) or more (coenurus. Fig. 114) heads which conform with the 
scolex of the adult worm except that the larval head is invaginated. 

If the larva while still living at this stage is conveyed to the digestive 
canal of a suitable host for the adult worm, the head is evaginated from 
the vesicle (Fig. 112, c), becomes detached from it, and, passing to the 
intestine, fixes upon the mucosa by means of its suckers, to which attach- 
ment the crown of hooks contributes if this is present. By a process of 
budding, the scolex now proliferates a series of segments, each to be- 
come bisexually complete (Fig. 90) . 

Sexual maturity of the segments marks the stage of the adult worm 
which, with its entire series, constitutes the chain, or, as it has been 
called by most writers, the strobila, a term which, with that of proglottid 
for segment, is discarded in this work. 

Tabular Review of Life History of T^nia Saginata 
Adult Tapeworm in intestine of man 

I 
Egg. — Expelled from intestine. 

1 
Hexacanth. — Freed from egg in digestive tract when 

I ingested by ox. 

Acephalocvst. — ^In striated muscle of ox. 

I 
Cephalocyst (Cysticercus) .^ Same. 

Scolex. — Attached to mucosa of intestine of man 

I after ingestion of cephalocyst. 

Adult Tapeworm in intestine of man. 

Parasitism. — The tapeworms afford an example of extreme para- 
sitism. So far as known, their existence is wholly dependent upon 
alternate cystic and adult hosts, their development exhibiting no free- 
living stage. So advanced is their degeneracy that there is little of 
organization remaining excepting the procreative, and this has acquired 



PLATYHELMINTHES 173 

a hyperdevelopment adaptive to the hazards encountered in the worm's 
life history. 

The classification of the tapeworms has been somewhat more artificial 
than S3'stematic in that it has not sufficiently taken into account mode 
of development, a factor which should furnish the basis for their true 
natural affinities. Their larvae may, with reference to method of develop- 
ment, be placed in the five following forms: 1. Cijsticercus (Fig. 107); 
2. cotnurus (Fig. 114); 3. echinococcus (Fig. 117); 4. cysticercoid (Fig. 
96); 5. plerocercoid (Fig. 112,-e). The first three are found in organs 
or serous cavities of Herbivora and Omnivora, occasionally in Carnivora; 
the fourth lives mostlj' in invertebrates, and the fifth in the musculature 
of fishes. The more recent tendency in cestode nomenclature is to con- 
fine the generic name Taenia to those tapeworms which have a cysticercus 
stage in their life history. 

The cystic forms enumerated above, with the conditions which cer- 
tain of them produce in their hosts, are taken up further on in the con- 
sideration of the cestode larvae. 

The accompanying tabular arrangement of the principal tapeworms 
considered in this work, with their adult and C3'stic hosts, is inserted 
for convenient reference. 



CHAPTER XV 

T.^NIASIS 

As to the effect of tapeworms upon their hosts, it may be said in gen- 
eral that serious disturbances are most hkely to be manifest when the 
worms are numerous, in which case the morbid effect is brought about 
by the operation of several factors. There may be a reduction or com- 
plete occlusion of the intestinal lumen with the usual inflammatory and 
toxic disturbances or displacements following interruption in the move- 
ment of the intestine's contents. While, as a general statement, in- 
vasion of the bile duct by tapeworms may be said to be rare, the fringed 
tapeworm of sheep {Thysanosorna actinioides) frequently enters this 
organ and therefore constitutes a more serious tseniasis in these animals 
than that from the Moniezia species. Armed tapeworms, by the irrita- 
tion from their hooks, will, essentially, set up an inflammation of the 
mucosa proportionate to their number. Further, where the worms are 
numerous, their appropriation of nourishment contributes to the mal- 
nutrition of a catarrhal enteritis. In heavj^ infestations the toxins 
elaborated by the worms undoubtedly play a considerable part in the 
general systemic effect. 

The cystic forms of certain tapeworms have an important bearing 
upon the sanitary control of meat food products. In our own country 
this is especially true of the cysticerci of the two tapeworms of man, — 
Tcenia saginata and T. solium, the cysts of the former being harbored 
in beef, those of the latter in pork. The presence of these cysts in the 
muscles or other parts of the bod}^ constitutes the disease known as 
measles, to which affection the terms ''measly beef" and "measly pork" 
have reference. While observed most frequently in the animals men- 
tioned, measles may appear in sheep {Cysticercus tenuicollis, C. ovis), 
and man is occasionally auto-infected by larvae (Cysticercus cellulosce) 
of Tcenia solium which he harbors. 

Cestodes of the Horse 

Three species of tapeworms occur in the Equidae. In all the cephalic 
armature and neck are absent, and all have a genital pore on the same 
side in each segment. Nothing is known of their larval forms. 

1. Anoplocephala perfoliata (Taenia perfoliata). Fig. 91. Tseniidse 
(p. 170). — The head is large, rounded, and provided with well-developed 



.\dult 


Hosts 


Armature 


Anoplocephala perfoliata 


Horse and ass 


Unarmed 


Anoplocephala mamil- 
lana 


Horse and ass 


Unarmed 


Anoplocephala plicata 


Horse and ass 


Unarmed 


Moniezia expansa 


Cattle, sheep and 
goats 


Unarmed 


Moniezia alba 


Cattle, sheep and 
goats 


Unarmed 


Moniezia planissima 


Cattle, sheep and 
goats 


Unarmed 


Thysanosoma actinioides 


Sheep 


Unarmed 


Dipylidium caninum 


Dog, cat, man 


Armed 


Ta;nia hydatigena 


Dog 


Arnied 


Taenia pisiformis 


Dog 


Armed 


Multiceps multiceps 


Dog 


Armed 


Multiceps serialis . 


Dog 


Armed 


Multiceps gaigeri 


Dog 


Armed 


Echinococcus granulosus 


Dog, cat 


Armed 


Tania taniajformis 


Cat 


Armed 


Cittotaenia denticulata 


Rabbit 


Unarmed 


Choanotsenia infundibu- 
lit'ormis 


Chicken 


Armed 


Hymenolepis carioca 


Chicken 


Armed 


Davainea tetragona 


Chicken 


Ai-med 


Davainea cesticillus 


Chicken 


Armed 


Davainea echinobothrida 


Chicken 


Ai-med 


Davainea proglottina 


Chicken 


Armed 


Taenia saginata 


Man 


Unarmed 


Taenia solium 


Man 


Armed 


Ciphyllobothrium latum 


Dog, cat, man 


Unarmed 



Hosts 


Parts Infested by Larva 






























Flea, louse 


Body-cavity 


Ruminants and hogs 


Peritoneum 


Rabbit 


^Mesentery and omentum 


Herbivora 


Central nervous system 


Rabbit and other ro- 
dents 


Connective tissue 


Ruminants 


Central nervous system and 
connective tissue 


Ruminants and hog 


Liver and lungs 


Rat and mouse 


Liver 






House fly 




















Snail 




Ox 


Connective tissue of muscles 


Hog and other animals 


Connective tissue of muscles 


Fish 


Muscles 



T.^NIASIS 



175 



suckers; it is prolonged behind by rounded flaps on the upper and lower 
side. The segments are very short, but wide, the width increasing 
toward the middle of the length of the body. 

Length, 2.5-3 cm. (1 inch); width, 3-15 mm. (1/8-5/8 of an inch). 

The eggs, by mutual pressure, are polygonal. The shell, as in other 
Anoplocephalinae, is prolonged by a pyriform point. They are 70-80 
microns in length. 

It lives in the small intestine and ceemn, more rarely in the colon. 

2. Anoplocephala mamillana (TaBnia mamillana). Fig. 91. 
Tsniidse (p. 170). — The head is small, somewhat angular, and has a 
central lineal depression from before to 
behind. It is provided with oval suckers 
located upon the side. The segments are 
nuich wider than long, progressively in- 
creasing in width from the head. Their 
length increases toward the posterior ex- 
tremity, the last segments being about 
half as long as broad. 

Length, 1-5 cm. (3/8-2 inches); width, 
4-6 mm. (i<4 of an inch). 

The eggs are elongated and about 88 
microns in length. 

It infests the small intestine. 

3. Anoplocephala plicata (Taenia 
plicata). Fig. 91. Ta^niidse (p. 170).— 
The head is rather large, broader than 
long, slightly concaved in the center. 
The four suckers are strong and are di- 
rected forward. The segments progres- 
sively increase in breadth and length to 
the posterior extremity. 

Length, 8-12 cm. (3 1/8-4 ^ inches); 
width, 8-20 mm. (5/16-^^ of an inch). 

The eggs are polygonal or round and 50-60 microns in length. 

It lives in the small intestine and has been found in the stomach. 

Occurrence. — Horses rarel}' harbor tapeworms. They are said to 
be most often found in the horses of Russia and to some extent in 
Germany and other European countries. The most common species is 
Anoplocephala perfoliata, while of the other two mentioned, Anoplo- 
cephala plicata is the luore rare. 

Symptoms. — The presence of tapeworms in the intestines of the 
horse is seldom accompanied by perceivable symptoms. Those general 
to intestinal helminthiasis, as chronic digestive disturbances, with per- 
haps anaemia and general unthrift, may accompany the infestation, 






Fig. 91. — Tapeworms of the horse. 
Left to right: Anoplocephala mamil- 
lana, A. perfoliata, A. plicata, nat- 
ural size. 



176 



PARASITES OF THE DOMESTIC ANIMALS 



though it can only be assumed that these symptoms are caused by tape- 
worms, even though the presence of the worms is made certain by the 
voiding of the segments. 



Cestodes of Cattle, Sheep, and Goats 

Cattle harbor three species of tapeworms. In all the heads are un- 
armed. Their larval forms are unknown. 

The three species of tapeworms of cattle also occur in sheep and^ 
goats. 

1. Monieziaexpansa (Taenia expansa). Fig. 92. Tseniidae (p. 170). 
The head is small, generally pear-shaped. The 
suckers are slightly salient and slit-like. The an- 
terior part of the chain is filiform. The first seg- 
ments are very short, those which follow becoming 
longer, but always much broader than long. The 

Is = ^ broadest segments may reach a breadth of 2 cm. 
= = (3<£ of an inch). The genital pores are double 
M = ^ and located on the lateral margins of the seg- 
ments. 

The length varies considerably; it msiy be 15-30 
feet or more. 

The eggs are globular or polygonal and are 50-90 
microns in diameter. 

2. Monieziaalba (Taenia alba). Tseniidse (p. 170). 
— The head is larger than that of the preceding 
species and is provided with large oval suckers. 
The neck is short and the segments are longer and 
narrower than in M. expansa; some may be slightly 
Moniezia longer than broad. The width of the broadest 
segments is about 1 cm. (3/8 of an inch). There 
are two genital pores in each segment. 
Its maximum length is about eight feet. 
The eggs are cuboidal and 48-58 microns in breadth. 
3. Moniezia planissima. ' Tseniidse (p. 170). — The head is nearly 
square and has slightly elongated suckers. The segments are much 
broader than long, the ripe ones having a width of 12-26 mm. (3^-1 
inch). These segments are very thin and semitransparent. Each seg- 
ment has two genital pores. 
Length, 3-6 feet. 

The eggs are about 63 microns in diameter. 

Thysanosoma actinioides (Taenia fimbriata). Tseniidse (p 170.). — 
This is a species occurring in sheep, but has not been reported in other 
domesticated Herbivora. The head is without hooks or rostellum. The 




Fig. 92. 
expansa, portions of 
adult, reduced (after 
Railliet). 




T.EXIASIS 177 

segments are broader than long, having the uterus transverse and the 
genital pores double or irregularly alternate. The segments have long 
fringes on their posterior borders (Fig. 93). 

Length, six inches or more. 

Its larval form is unknown. 

Occurrence and Symptoms. — All of these worms live in the small 
intestine. As nothing is yet known of their cystic forms, the mode of 
infection remains undetermined. Cattle are rarely disturbed in health 
by the presence of tapeworms. In exceptional cases there may be 
malnutrition and digestive disturbances accompanied by bloating. 
Again, it is difficult to with certainty assign these nonspecific condi- 
tions to the presence of tapeworms. As in all intestinal helminthiases, 
there is to be borne in mind the possibility of the worms passing to 
unusual locations, as the bile ducts, and of 
interference with the movement of the in- 
testinal contents by massed worms. 

Of the domesticated herbivorous animals, 
probably sheep most frequently harbor tai^e- 
worms. A species often found in those of 
the United States is Thijsanosoma aclinioidcs 
Avhich, as is true of other species infesting 
sheep, is most prevalent among the flocks of Fig. 93.— Thysanosoma ac- 
the Western States. The worms may be tinioides, anterior segments,— 
found at an}' time of the year, though more ^^ ^'^^^ 
often during the season of grazing, a fact pointing to the probability 
that the encysted larvae are taken up with the grass. Thysanosoma 
actinioides, when brought to certain parts of the Eastern United States, 
does not multiply. It may be assumed that this is attributable to 
absence of the proper intermediate host, whatever that may be. In 
parts of the west it constitutes a form of taeniasis much more severe than 
that from ]\Ioniezia. This is due mainly to their invasion of the bile 
duct, a habit which is exceptional with other tapeworms, but with the 
fringed tapeworm it is the rule rather than the exception. 

Lambs born in the winter and turned upon grass during the rains 
and moisture of spring are the more likely to suffer from tapeworm 
invasion. In such cases, or in hea\y infestation, anaemia is indicated 
by paleness of the \asible mucosae, and this may be accompanied by 
loss of vivacity and more or less emaciation with arrest in development. 
Straining and ineffectual efforts at defecation, with prolonged elevation 
of the tail, are noticed, the feces later becoming unformed or even fluid 
and containing the segments. 

Death ma}' ensue in advanced emaciation and weakness, or before 
reaching this stage if the intestine becomes obstiiicted by the worms 
in mass or there are other resulting complications. Such a course is 



178 PARASITES OF THE DOMESTIC ANIMALS 

rare in aged sheep. Where fatahties occur, they are usually among the 
grazing lambs. 

Cestodes of the Dog 

Of the tapeworms of the dog, nine are considered here, among which 
there is a wide variation as to frequency and importance. The first 
eight of the species to be mentioned belong with the family Taeniidae; 
the ninth is referred to under the Diphyllobothriidse. In all but the 
last the head is provided with the crown of hooks, and in all the life 
history is known. 

1. Dipylidium caninum (Taenia cucumerina) . Fig. 94. Taeniidse 
(p. 170). — The head is small and has a protractile rostellum surrounded 
by the four suckers (Fig. 95). There are three to four rows of small 
thorn-like hooks. The neck is slender, succeeded at first by narrow 
trapezoidal segments. The nature segments are longer than wide and 
shaped somewhat like a cucumber seed. They have a genital pore on 
each lateral margin. 

Length, 15-40 cm. (6-16 inches). 

Eggs globular, 43-50 microns in diameter and grouped in small cap- 
sules (Fig. 96). 

The larva of this worm is a cysticercoid {Cryptocystis trichodedes) 
found in the body-cavity of the biting louse of the dog, — Trichodedes 
latus (Fig. 96). Lice are not sufficiently prevalent upon dogs, however, 
to account for the frequent occurrence of this worm; in fact, later in- 
vestigations have determined that the dog flea, Ctenocephalus cams, 
and the human flea, Pidex irritans, harbor its larva, and it is probable 
that the flea is its more common host. 

2. Dipylidium sexcoronatum. Tseniidse (p. 170). — Hall and Wigdor 
(Journal of the American Veterinary Medical Association, June, 1918) 
refer to this tapeworm as follows: "Dipylidium sexcoronatum has been 
reported from dogs in the United States at Bethesda, Md., and Detroit, 
Mich., by Hall (1917). We find it fairly often here at Detroit and our 
impression is that it is as common here as D. caninum. The strobila is 
much narrower than D. caninum. Some of the specimens with a narrow 
strobila appear to have only five rows of hooks and should be studied 
with a view to determining whether D. sexcoronatum has sometimes five 
rows of hooks, as well as six rows, or whether this material belongs to a 
new species." 

3. Taenia hydatigena (T. marginata). Fig. 97. Taeniidse (p. 170). — 
The head is small, but little broader than the neck. The hooks are 
large, 170-220 microns long, and number 30-34. The mature segments 
are wider than long, the distal segments elongated. The gravid seg- 
ments have a median longitudinal groove terminating in a notch pos- 



TiENIASIS 179 

teriorly. The number of segments is about 400. The gravid uterus has 
5-10 branches on each side. 

Length, 1.5-2 meters (57-76 inches). 

Eggs nearly spherical and 31-36 microns in diameter. 

The larva is a cysticercus (Csyticercus tenuicollis) found in the per- 
itoneum and, more rarely, in the pleura of loiminants and hogs. It has 
also been reported from rotlonts and monkeys. 

4. Taenia pisiformis (T. serrata). Fig. 98. Tseniidse (p. 170). — 
The head is small, but little broader than the neck. The hooks are 
large, 225-294 microns long and 34-38 in number. The segments are 
at first narrow and much shorter than broad; those mature are approx- 
imatel}' square. The distal segments are elongated (10-15 mm. by 
4-6 mm.). The posterior margins of the segments project laterally, 
giving to the lateral margins of the chain a serrated appearance. The 
genital pores are prominent, and the utenis in gravid segments has 8-14 
lateral branches on each side. 

Length, 0.5-2 meters (19-76 inches). 

Eggs oval, 36-40 microns long, 31-36 microns wide. 

The larva is a cysticercus (Cysticercus pisiformis) which develops in 
the mesentery and omentum of rabbits, and has been found in the mouse 
and beaver. 

5. Multiceps multiceps (Taenia coenurus). Fig. 113. Tseniidse 
(p. 170).— The head is small and bears 22-30 hooks. Larger hooks have 
a handle equal in length to that of the blade and wavy in outline. The 
segments of the middle portion of the chain arc approximately square. 
The distal segments are elongated (8-12 mm. long by 3-4 mm. wide). 
The ripe segments are broader at their middle, narrowing toward their 
ends which gives them somewhat the appearance of a cucumber seed. 
The genital organs are well developed, 15-20 cm. (6-8 inches) from the 
head, or toward the 125th segment. The genital pores are irregularly 
alternate. The uterus has 16-25 lateral branches on each side. 

Length, 40-60 cm. (16-23^ inches). 

Eggs nearly spherical and 31-36 microns in diameter. 

The larva is a coenurus (Multiceps multiceps; Coenurus cerebralis) 
which develops in the cerebral cavity and, more rarely, in the spinal 
canal of herbivora, usually sheep (Figs. 114 and 116). 

6. Multiceps serialis (Taenia serialis).— Tseniidse (p. 170). The 
head is a little wider than the neck and bears 26-32 hooks. The small 
hooks have a short blunt handle; the larger hooks a wavy handle as 
long or a little longer than the blade. The segments are similar to those 
of M. multiceps, the form of the uterus in gravid segments also being the 
same. 

Length, 44-74 cm. (17-293^ inches). 

Eggs oval, 34 microns long, 27 microns wide. 





Fig. 96. — Egg packet of Dipylidium 
caninum (left); Cysticercoid (right). 



Fig. 95. — Head of 
Dipylidium caninum, 
with I'ostellum pro- 
jected. 



Fig. 94.— Dipyli- 
dium caninum, por- 
tions of adult,— ^ 
natural size. 





Fig. 9S. — Taenia pisiformis, 
portions of adult, — natural size. 



Fig. 97. — Tsenia hydati- 
gena, portions of adult. — nat- 
ural size. 



T.ENIASIS 181 

The larva is a coeniirus (Multiceps serialis; Ccenurus serialis) found 
in the connective tissue of rabbits and other rodents. 

7. Multiceps gaigeri. Taeniidae (p. 170). — This is a species found 
in India and Ceylon, and described b}' Hall (Journal of the American 
Veterinarj'^ Medical Association, November, 1916), the larva of which 
develops m the central nervous system and also in the connective tissues 
and serous surfaces of ruminants. Thus in its cystic host this species 
combines the location of M. multiceps and M. serialis, the larva, as in 
that of the latter, forming an adventitious capsule. 

The material for examination (Bureau of minimal Industrj^, Hel- 
minthological Collection) consisted of specimens of tapeworms from 
the dog and the ccenurus from the goat. From his stud}' of these, Hall 
(1916) regards this species as more closeh^ related to the gid tapeworm, 
M. multiceps, than to M. serialis. 

8. Echinococcus granulosus (Taenia echinococcus). Fig. 99. 
Taeniidae (p. 170). — The chain is but 4-6 nun. (3/16-1/4 of an inch) in 
length, and is composed of a head and three segments. The head is 
provided with 28-50 small hooks arranged in two rows. The first and 
second segments from the scolex are incompletely developed, but one 
segment at a time becoming gravid, — the third, when its length almost 
reaches that of the rest of the worm. 

Eggs oval, 32-36 microns long, 25-26 microns broad. . 

The larva is an echinococcus {Echinococcus granulosus; E. polymor- 
phus) found in the internal organs, usually the liver and lungs, of rumi- 
nants and hogs, and also in man (Fig. 117). 

Occurrence. — It follows from their habits that dogs should more 
frequently harbor intestinal parasites than other domestic anunals. 
Probably over fifty per cent, are infested with varied species, frequently 
in considerable number. Of these, tapeworms predominate, several 
species of which often inhabit the intestine of a single individual. 

The intermediate hosts of Dipylidium caninum — fleas and lice, the 
former ubiquitous in relation to canine existence, — would account for 
the greater frequenc.y of this tapeworm than any other in dogs. Dogs 
which have access to butchers' offal are, in addition to this species, 
readily infected with Echinococcus gramdosus, Tcenia hydatigena, and 
Multiceps multiceps, the cystic forms of which are harbored in organs 
of the principal meat-food animals, sheep, hogs, and cattle. Hunting 
dogs and those which roam afield are the most exposed to invasion with 
TcBnia pisiformis and Multiceps serialis, these having their larval devel- 
opment in rabbits. In an}^ case, young dogs are more susceptible to 
intestinal helminthiasis than those which are older. 

Symptoms, — Notwithstanding their frequent presence in large num- 
bers, tapeworms seem, as a rule, to have little deleterious influence 
upon the health of dogs. As is tme of intestinal worms in general, 



182 PARASITES OF THE DOMESTIC ANIMALS 

their accumulation may bring about obstruction with attendant dis- 
placement and degenerative changes in the intestinal walls; and, again, 
there ma}'' be a serious and even fatal result from their unusual location. 
Such consequences of taeniasis are, however, exceptional in dogs. In 
general, the s\miptoms are those of chronic gastro-intestinal catarrh. 
The capricious appetite varies between extreme voraciousness and com- 
plete anorexia. Regardless of the amount of food consumed, there is a 
noticeable emaciation which may become well marked, young dogs 
especially becoming pot-bellied and stunted in growth. More char- 
acteristic is restlessness, straining, and itching about the anus, the latter 
manifested by agitation of the tail and a peculiar squatting and dragging 
of the hind parts, sometimes referred to in the expressive, but highly 
untechnical term, ''rough-locking." 

With increasing uneasmess, the development of intestinal pains, 
howling, and an inclination to bite, which is perhaps conjoined with a 
dull or wild expression, there are presented symptoms somewhat similar 
to those of rabies. In such cases convulsions may set in and the animal 
may die during an attack, or it may gradually succumb after sinking 
into a cataleptic condition. 

Pathogenesis. — Necropsies upon dogs which have suffered from 
taeniasis generally show the worms lodged in the small intestine only. 
Probably as a result of post-mortem wandering, they may also be found 
in small numbers in the large mtestine or stomach. The inflammation of 
the mucosa is especially extensive and of aggravated character in in- 
festation with Echinococcus. This is a tapeworm of the dog which, 
though relatively very small, sets up the greatest irritation bj'- reason 
of the vast number of individuals present, w^hich, firmly implanted by 
their hooks, may completely cover the intestinal lining over large areas. 
Where obstruction occurs in taeniasis, it is generally brought about by 
the presence of the larger tapeworms massed in coils. Dipylidium 
caninwn, though smaller than some other species inhabiting the dog, is 
most likely to be found the offending agent in such conditions because 
of its prevalence and the presence of numerous individuals in the 
same host. The projecting rostellum of this species, sinking deep 
into the mucosa, is also a factor increasing its capabilities for dam- 
age. Tcenia hydatigena and T. pisiformis are much larger, but less 
common, while Midticeps multiceps and M. serialis have thus far 
been found more commonly in European countries than in the 
United States. 

Contributing to the systemic effects of tapeworm invasion, there is, 
as in other helminthiases, the operation of toxins elaborated by the 
worms." In cases of heavy infestation this factor must be a considerable 
one, especiallj' when combined with that of poisons derived from the 
dead and decomposing bodies of the parasites. 



TiENIASIS 183 

Diagnosis. — The presence of tapeworms may in most cases be recog- 
nized b}" the passing of segments, or fragments of the chain, with the 
feces; occasionally these may also be expelled with vomited matter. 
Often the fragments may be arrested near or partly protrude from the 
anus, causing a pruritus in this region which the animal endeavors to 
relieve by rubbing the parts upon the ground. 

Diagnosis may be assisted in doubtful cases by the administration 
of a laxative, in the operation of which detached portions of the chain 
will be expelled if present. Echinococcus, however, on account of its 
small size, is likely to escape observation in the ordinary means of 
examining fecal matter. 

Dog Tapeworms in Relation to Human Infection. — Two species of 
tapeworms harbored by dogs — Echinoccocus granulosus and Dipylidium 
caninum — are especially of medical interest in that they ma}' also 
infect man. The first mentioned produces in its larval development a 
condition known as hydatid disease, or echinococcosis, in man as well 
as in numerous lower animals. 

The larval or, as it is called, the hydatid form of this tapeworm occurs 
usually in the liver, lungs and kidneys of these animals, and may pro- 
duce from the original cyst numerous daughter cysts, the growth going 
on indefinitely and evolving bladders as large or even much larger than 
an orange (Fig. 117). Due to its pressure, necrotic degeneration of 
tissue, and also to secondary infection by bacteria, this growth gives 
rise to serious disturbances in the organ in which it is lodged. In man 
the condition is often fatal, less so in the lower animals, probably owing 
to the fact that their term of life is shorter, or they are likely to be 
slaughtered before sufficient time has elapsed for the full development 
of the slow-growing hydatid. 

A more detailed reference to the echinococcus c.vst is given further 
on in the special consideration of the cestode larvse (p. 210). 

The connnon tapeworm of the dog, Dipylidium caninum, may find 
adult hostage in the human intestine. According to Hall (Bull. 260, 
U. S. Dept. of Agriculture, 1915), seventy-six cases of this tapeworm 
in man, mostly children, have been reported, a number of these from 
the United States. It has been found in an adult thirty-eight years old, 
and it is stated that as many as two hundred and fifty-eight of these 
worms have been found in a single person. 

Considering the privileges which are allowed dogs, it is quite apparent 
that a flea or louse containuig the Cryptocystis might pass from the dog 
to the human mouth by the dog licking the face, or through the inter- 
mediation of food, especially sticky candy to which the insect readily 
adheres. Children give little attention to incidental contamination 
of their food, which is frequently partaken of in intimate proximity to 
their canine companions, the dog often sharing in the feast — perhaps 



184 PARASITES OF THE DOMESTIC ANIMALS 

from the same plate. It follows that human mfection with this tape- 
worm occurs more often among children than among adults. 

As in tseniasis of other animals, the presence of a few of these worms in 
man is not likely to occasion serious disturbance, though to the human 
conception, the presence of a tapeworm in the intestine is anything 
but a pleasant thing to contemplate. Where they are numerous, the 
irritation, possible obstruction, and other secondary compHcations which 
may arise, make it, as in lower animals, a more serious condition. 

Prevention calls for restraint in the liberties of dogs, especially about 
children. Children should not be permitted to handle vagrant and 
neglected dogs. Those kept about the premises as pets should be ob- 
served for indications of the presence of tapeworms, and their bodies 
should be kept free from fleas and lice. 

Cestodes of the Cat 

Of the tapeworms harbored by cats, onl}^ the species Tcenia tcenice- 
formis is of importance as affecting their health. Others which have 
been found are: Dipylidimn caninum, Echinococcus granulosus, and 
Diphyllobothrium latum, the first two described under 
the Tseniidse of the dog. These latter forms do not 
appear to cause disturbance to the animal. 

Taenia taeniseformis (T. crassicollis). Tseniidse 
(p. 170).— The head (Fig. 100) is rounded, has four 
prominent suckers and a strong rostellum provided 
with 26-52 hooks. The neck is as wide as, or wider 
than, the head, and there is no intermediate constric- 
FiG. 100.— Head of tion. The segments follow immediately from the head, 
Taenia taeniaeformis, increasing in size to a length of 8-10 mm. (5/16-3/8 

Length, 15-60 cm. (6-23i^ inches). 

Eggs globular, 31-37 microns in diameter. 

The larva is a cysticercus (Cysticercus fasciolaris) inhabiting the 
liver of rats and mice. 

Occurrence and Symptoms. — This tapeworm is not uncommon 
in the cat, often infesting the small intestine in large numbers and 
seriously affecting the animal. 

There is in the beginning a diminution of appetite which gradually 
passes to refusal to take any food whatever. Diarrhea, at first slight,, 
later severe, is succeeded by constipation; there is salivation, and in 
some cases vision and hearing are seriously affected. Colic is a frequent 
accompaniment during the attacks of which the animal may rush about 
in a frantic manner, apparently heedless of or unable to see objects with 
which it may come in contact. 




T.ENIASIS 185 

Finally, as a manifestation of the nervous disturbance, there are 
convulsions; there is much prostation and emaciation, and the animal 
dies, usually during or shortly after an epileptiform attack. 

Cestodes of Rabbits 

Tapeworm infection is said to frequently appear enzooticall}' among 
the wild hares of foreign countries. In domestic rabbits such infection 
is rare. The species here described is occasionally found. It is unarmed, 
and its life history is unknown. 

Cittotaenia denticulata (Moniezia denticulata). Tseniidse (p. 170). — 
The head is small, with fiat suckers. The neck is as broad as the head. 
The larger segments may be 10 mm. (3/8 of an inch) in width, always 
wider than long. The genital pores are on the posterior fourth of the 
border of the segment. 

It may reach a length of 8 cm. (3 inches). 

There is little clinical experience with taeniasis of rabbits. In general, 
what has been said as to such infection in other animals will apply as 
well to them. Diagnosis can be made by finding the segments in the 
feces, or by destroying and examining one or two suspected animals. 

Family II. Diphyllobothriid.e 

The best known representative of this family is DiphyUobothrium 
latum (Dibothriocephalus latus, Bothriocephalus latus). The head is 
oblong or lanceolate, unarmed, and has two deep slit-like depressions, 
one dorsal, the other ventral, which serve as suckers (Fig. 109). The 
neck is not well demarcated from the first segments which are scarcely 
visible. The segments gradually increase in length and breadth; the 
largest are 4-5 mm. long and may be 2 cm. wide (3/16 by 3/4 of an 
inch). The gravid segments become much narrower as their genital 
organs atrophy and the eggs are discharged, these being expelled in 
greater part before the separation of the segments from the chain. In 
sexually mature segments the rosette-shaped uterus may be seen in the 
middle line. The genital pores are special orifices for ovulation, located 
in the middle of the ventral surface of the segments (Fig. 101). 

The length of the entire worm may be 2-7 meters (6-22 feet). It 
may reach a length of 20 meters (Neumann). The segments may 
number 3,000 or more. 

The eggs are oval, operculated, and 68-70 microns long. In the 
presence of water a ciliated embryo escapes from the egg by the lifting 
of the operculum and swims about until it enters the body of a iresh- 
water fish, said to be especially the pike. In the muscles of this host it 
develops into the worm-Hke plerocercoid (Fig. 112, e). After the 



186 



PARASITES OF THE DOMESTIC ANIMALS 



definitive host has eaten fish containing the hving kirvse, the tapeworms 
develop rapidly, becoming mature in about four weeks. 

Occurrence. — This species is sometimes called the broad Russian 




IS^'f i lUBtti 





Fig. 101. — Sections of Diphyllobothrium latum, — natural size (after Boas, by Kirkaldy 
and Pollard, from Leuckart). 

tapeworm. It infests man and fish-eating dogs in Russia, Switzerland, 
Japan, Finland, Sweden, and other foreign countries. It is extremely 
rare in the United States, and is of little medical or economic importance 
here. 

Teeatment of T^niasis 

Treatment of Taeniasis of the Dog. — Therapeutic measures for the 
expulsion of tapeworms have two consecutive objects in view; first, the 
bringing about of a torpid condition or weakening of the worm; second, 
the expulsion of the entire worm from the host. The first is attained in 
part by depriving the parasite of its nourishment, and by the adminis- 
tration of a vermifuge which should sufficiently further weaken it to 
cause its detachment from the mucosa; the second by a purgative which 
will expel the detached worm with the evacuations. 

As preparatory to the action of the vermifuge, all food should be kept 
from the animal for at least twenty-four hours immediately preceding 
its administration; at the same time the cleaning out process will be 
considerably aided if a mild laxative is given. Some advocate a milk 
diet for several days, but in any case the fasting should be absolute for 
a period of one day. 

Of the vermifuge agents, those which have been found most reliable 
as taeniafuges are: (1) male fern (aspidium); (2) areca nut; (3) kusso; 
(4) kamala. Of these male fern is particularly serviceable. Depending 
upon the weight and age of the animal, the oleoresin of aspidium may 
be given to dogs in doses of fifteen minims to one dram. It can be 
advantageously combined with small doses of areca nut (one grain per 
pound of body- weight) , and conveniently administered in capsule. 
Aspidium should never be given with oil as this favors its absorption, 
and it is a local action which is sought. After three to four hours the 



T.ENIASIS 187 

dose may be repeated, and twelve hours after the first dose a purgative 
should be given. 

The dog should be kept where its evacuations can be conveniently 
examined, and, if it is found that the head of the tapeworm has not been 
expelled, the treatment is to be repeated in a week to ten days. The 
expulsion of the worm may be aided somewhat by rectal injections of 
warm soapy water. 

If areca nut is used uncombined, it may be given in doses of two 
grains for each pound of body-weight. It can be conveniently adminis- 
tered shaken up in a little milk. Areca nut in itself is laxative or purga- 
tive according to dosage. If purgation has not followed within a few 
hours after its administration, a full dose of castor oil should be given 
ten to twelve hours later. 

Kusso has an advantage in being quite safe even in excessive doses. 
Small dogs take of the fluid extract one-half to one dram; large dogs, 
two to four drams. It can be given in milk and repeated three times at 
intervals of one hour. Vomiting, which sometimes follows the adminis- 
tration of kusso, may be prevented by previously giving a medicament 
having an anesthetic action upon the stomach. 

Kamala is given to dogs in doses of one-half to two drams in honey or 
syrup. In cases where heavj^ infestation is suspected it should be re- 
peated in eight hours. Kamala has some purgative action and may 
also nauseate; the latter effect can be corrected by the same means as for 
kusso. 

Other taeniafuges sometimes used are: (1) Pumpkin seeds, fed crushed 
and macerated or as an infusion, and (2) turpentine, one-half to one 
dram, given with the yolk of an egg and repeated mitil three doses have 
been administered twenty-four hours apart. Turpentine, however, on 
account of its irritant effect upon the kidneys, should be used with 
caution. 

^^'hatever form of taeniafuge medication may be chosen, the chances 
of success will depend much upon a brisk purgative action following 
upon its operation. At best there is often failure to secure the head of 
the worm, in which event a repetition of the whole treatment is called 
for in the course of one to several weeks. 

Prevention. — To prevent the spread of taeniasis, all expelled tape- 
worms and their fragments should be destroyed by burning. Dogs 
known to be infected had best be isolated and all of their excrement 
burned. Dogs which have their meat cooked, and those which are not 
allowed access to the viscera of slaughtered animals and rabbits, are 
not so likely to be infected, though such precautions will not protect 
them from the common species Dipylidium caninum, freedom from fleas 
and lice, and prevention from association with dogs less fortunate in 
this respect, being essential to avoidance of infection Iw this species. 



188 PARASITES OF THE DOMESTIC ANIMALS 

Treatment of Taeniasis of the Cat. — For tseniasis of the cat the same 
procedure may be followed and the same remedies used as for the dog. 
The dosage, however, should be reduced and proportioned according to 
the weight and age of the animal. 

Prevention consists in restraining the animals from feeding upon 
rats and mice, — the intermediate hosts of their most common tape- 
worm, — Tcenia tceniceformis. 

Treatment of Taeniasis of Sheep and Goats. — For several days pre- 
ceding treatment of these animals it is advisable to feed moderately 
upon green succulent food, avoiding bulk, as fodder and hay. Imme- 
diately before giving the vermifuge all food should be withheld for a 
sufficient time to make the animals quite hungry. Powdered areca nut 
may then be given in one to two dram doses according to weight. It 
can be administered mixed with bran or bran and chopped beets which 
the sheep, made ravenous by their preliminary fast, will eat greedily. 
Three hours afterward a purgative should be given and the evacuations 
of each individual kept under observation for the appearance of tape- 
worms. 

Other vermifuges reconmi ended are: (1) Oil of turpentine, one to two 
drams, given in one-half to one ounce of linseed, cottonseed, or olive 
oil, and (2) kamala, forty-five grains to one and one-half drams in thin 
syrup or water, the dose to be repeated once at an interval of four hours. 

Treatment of Taeniasis of Cattle. — Where treatment is indicated for 
the expulsion of tapeworms of cattle the animals should be dietetically 
prepared as recommended for sheep. As a vermifuge, tartar emetic is 
quite suitable for these animals. It may be given in one and one-half to 
two and one-half dram doses in gruel. Oil of turpentine, three ounces 
in a pint of linseed oil, makes a reliable remedy. Arsenic in daily 
ascending doses for a period of fifteen days has also been recommended. 
The vermifuge treatment should be followed by a purgative of glauber 
salts. 

Treatment of Taeniasis of the Horse. — The existence of tapeworms 
in the horse generally remains unrecognized during life. The symptoms 
are those general to intestinal helminthiasis of horses, and the treat- 
ment is quite the same as that for ascariasis (p. 234). The animal is to 
be removed from work, kept from hay, and fed only upon mashes. After 
at least twenty-four hours of such preparation, give two to four ounces 
of oil of turpentine, and one dram of oleoresin of aspidium in a pint of 
linseed oil. Tartar emetic is also quite effectual. It should be given 
in two doses of three drams each at an interval of twelve hours. It 
may be mixed with a gruel of linseed meal. 



<^' 



CHAPTER XVI 

TAPEWORMS OF CHICKENS 

Though tapeworms are comparativelj' frequent in chickens and other 
domestic fowl, they have not up to quite recent times been the subject 
of anj' considerable investigation in this country. In our hterature upon 
the parasites in general, if not neglected entirely, but one or two species 
are as a rule described, and these generall}' in an incomplete manner. 

With the exception of but one species, what is at present known as 
to the larval forms has been determined from studies upon poultry 
cestodes in foreign countries. Thus far in these investigations the life 
C3'cle of but one chicken tapeworm — Davainea proglottina — has been 
experunentally demonstrated, the only one among the six here described 
which has not been reported in this country. The remaining five have 
been found infesting chickens in various parts of the United States. 

1 . Choanotaenia inf undibulif ormis iDrepanidotama injimdi- 
buUformis) (Fig. 102)— The head (Fig. 103) is small, globular 
or conical, and bears a crown of 16-20 hooks. The suckers 
are prominent, may be projecting. The neck is very short. 
The first segments are short; those following are infundibuli- 
form, with anterior border narrower than the posterior. The 
genital pores are irregularly alternate. 

The length varies from 2-23 cm. {%-^\^ inches). 

Grassi and Rovelli, comparing cysticercoids which they had 
found in flies (Musca domestica) with the adult Choanotcenia 
inf undihidif ormis, noted a stmctural agreement from which 
they inferred that the larvae were the intermediate stage of 
this species. No experiments were carried on by these in- 
vestigators, however, to demonstrate this connection. 

Guberlet, of Oklahoma Agricultural and Mechanical Col- 
lege, in a series of investigations upon chicken cestodes (1912- Fig. 102. 
1914) seems to have conclusively demonstrated that the ^nia^^'Jnl 
cysticercoid of Choanotcenia infundihidiformis occurs in the fundibuli- 
common house fly. Briefly stated, his results were obtained formis, — 
by raising cysticercoids in the flies by feeding them on the 
eggs of the tapeworm. These flies were fed to three of six chicks 
which had been removed from chance infection as soon as hatched. 
Three weeks after such feeding all of the chicks were killed, and two were 
found to be infested with Choanotcenia infundibuUformis. The three 
birds used as a check on the experiment contained no worms. 



190 



PARASITES OF THE DOMESTIC ANIMALS 



2. Hymenolepis carioca. — The head is piriform with retractile 
rostelhim. It is unarmed. The segments nmiiber about 500, all much 
wider than long; terminal segments measure 0.5-0.8 mm. The genital 
pores are unilateral. The worm is very fragile and delicate. 

Length, 3-8 cm. (1^-3 1/8 inches). 
The life history is unknown. 

3. Davainea tetragona( Tce/na tetragona). — The head (Fig. 104) is 
small and tetragonal; rostellum armed with a crown of 100 hooks. The 
suckers are oval and armed with 8-10 circlets of small hooklets. The 
short neck is followed by short trapezoid segments, those terminal 




Fig. 103.— Choano- 
tsenia infundibulifor- 
mis, scolex much con- 
tracted, — enlarged 
(after Guberlet, in 
"Transactions of the 
American Microscopi- 
cal Society"). 



Fig. 104.— Scolex of 
Davainea tetragona, — 
enlarged (after Guber- 
let, in "Transactions 
of the American Mi- 
croscopical Society".) 



Fig. 105. — Scolex of Davainea 
echinobothrida, — enlarged (after 
Guberlet, in "Transactions of the 
American Microscopical Society".) 



generally longer than wide. Their length varies between 1-4 mm. The 
genital pores are unilateral. 

The length varies between 1-25 cm. (3/8-10 inches). 

Investigations of Plana point to certain little snails {Helix carthu- 
sianella and H. maculosa) as the probable larval hosts of this species. 

4. Davainea cesticillus {Tmnia cesticillus) . — ^The head is globular 
and has a rostellum scarcely salient or depressed. It is armed with a 
double crown of 400-500 hooklets which are loosely attached. The 
suckers are small and unarmed. There is no neck. The first segments 
are short and much wider than the head; the last are about as long as 
broad. The genital pores are irregularly alternate. 

Length, 1-4.5 cm. (3/8-1 3/4 inches). By some authors it is said to 
attain a much greater length (10-13 cm.). 



TAPE^YORMS OF CHICKENS 191 

According to Grassi and Rovelli the intermediate host is a lepidop- 
terous or coleopterous insect. 

5. Davainea echinobothrida (Tcenia echinohotJirida). — The small 
head (Fig. 105) presents an infundibulum provided with a double crown 
of about 200 hooks. The suckers are armed with 8-10 circlets. There 
is no neck. The segments gradually increase in Avidth, the largest being 
1-4 mm. The genital pores are irregularh' alternate. 

Length, 5-25 cm. (2-93^ inches). 

Nothing is known of its larval development. 

This species has a characteristic pathological effect in that the scolex. 
with its accessoiy armature about the suckers, bores through the in- 
testinal mucosa, producing large nodules or ulcers. The condition in 
fowls is termed "nodular tteniasis" and is described b}' Moore (Bureau 
of Animal Industry, Cir. No. 3, 1895). The nodules are often mistaken 
for other diseases showing similar features. 

6. Davainea proglottina (Tcenia proglottina) . — The head is quad- 
rangular, slightly rounded. The rostellum is armed at its base with 
80-95 hooks. The chain is composed of 2-5 segments. The terminal 
and largest segments have a tendency to detach and develop separately 
in the intestine. These free segments maj- acquire a length exceeding 
that of the entire chain. The genital pores are irregularly alternate. 

Length, 0.5-1.55 mm. 

Grassi and Rovelli have demonstrated that the larva of this species 
is a cysticercoid which inhabits several species of snail — Limax cinereus, 
L. agrestis, L. variegatus. 

The species has not as yet been reported in this country. 

Occurrence. — Guberlet, in a report of his investigations carried on 
in Nebraska (Journal of the American Veterinary INIedical Association, 
]\Iay, 1916), sets forth some significant data as to the prevalence, in 
parts of the LTnited States at least, of chicken cestode infection. Dining 
1912-13 he examined sixty-eight birds collected mostly from Nebraska 
and Illinois. From this material he obtained 1,561 tapeworms, specif- 
ically distributed as follows: Davainea tetragona, 598; D. cesticillus, 582; 
ChoanoUenia infundibuliformis, 17Q; Hymenolepsis carioca, 154; Davainea 
echinobothrida, 51 . The worms were present in numbers per host varv-ing 
from 1-35. (The author is informed by Dr. Guberlet that he has since 
found as many as 115 in a single animal.) Most of the birds examined 
ranged in age from fouf to six months. 

Symptoms. — As a rule it is only in moderate to heavy infection that 
tapeworms bring about morbid conditions in fowl. In any case the 
symptoms are not well defined. They may vary in different individuals 
having an equal degree of infestation, age especially having an influence, 
young birds being much more affected than adults and exhibiting the 
sATiiptoms more definitely. The following are among the more usual: 



192 PARASITES OF THE DOMESTIC ANIMALS 

There is an abnormal desire for food, in spite of which the heavih' 
infested chickens emaciate and become anaemic, as manifested by pale- 
ness of the comb and wattles. The feathers become erect, ruffled, and 
dull, and the birds have a tendency to isolate themselves, often in 
drooping attitudes, or the constantly hungry creatures may seem never 
to be at ease, but are constantly running about, this probably accounting 
in part for the loss of flesh. In such aggravated cases there is often ad- 
vanced emaciation, and, completely exhausted, the bird may die. 

Diagnosis. — A reliable diagnosis can onl}^ be made by finding the 
segments in the feces, or by killing and examining one or two of the 
birds showing suspicious symptoms. When the latter method is adopted 
the intestine should be removed and slit open under water. After 
gentle stirring to remove the contents, it may be transferred to a basin 
of clean water, when the worms, if present, will usually be seen attached 
to the mucosa. 

Control. — As in other forms of helminthiasis, control measures are 
most effectually applied to the parasites in their stage of larval develop- 
ment. Until more is known of the life histories of the chicken tapeworms 
little can be done in the way of prevention other than that based by 
analogy upon what has already been demonstrated. It is scarceh' 
practical to keep poultry from eating such possible intermediate hosts 
as worms and insects. Means may be taken, however, to restrict their 
access to flies, snails, and the lower crustaceans of stagnant water, 
though such precaution cannot well be applied to birds running at large. 
A more feasible accessory measure is the prevention of the larvae from 
reaching the intermediate hosts by isolating the infected birds in screened 
quarters where their droppings may be collected and made sterile by 
burning or other means. 

Treatment. — Vermifuges may be administered in the form of pills 
made up with bread. Probably the most suitable is areca nut which 
can be given to adult chickens in doses of from ten to twenty grains 
according to weight. Young animals may take from three to five 
grains. After three days the treatment should be repeated. Other 
remedies used are male fern, kamala, turpentine, and pumpkin seeds, 
the dosage being proportionate to weight. 

Such a method of treatment has a disadvantage in that each bird 
must be treated individually. Where the infection occurs in large 
flocks the repeated handling of each bird involves such an amount of 
time and patience as to put it practically out of the question. Again 
we are indebted to Guberlet for experiments which seem to point the 
way to a more practical method. Bearing upon this department of his 
work, his report is here quoted in part. 

"Fifteen birds which showed symptoms of tapeworm infection were 
placed in a cage which was insect-proof and were given the following 



TAPEWORMS OF CHICKENS 193 

treatment : A gallon of a mixture of wheat and oats, to which was added 
a small tablespoonful of concentrated Ij-e, was cooked slowh' for about 
two hours and allowed to cool. The birds were fasted for alDout fifteen 
hours and were then given as much of the mixture as they would eat, 
with plenty of water. Twelve hours later one of the birds was killed 
and an examination of the small intestine was made. It was found 
that nearly all of the worms in the intestine were loose, the scolices being 
detached from the wall, and were also apparently dead. The rest of 
the birds were given a second dose twenty-four hours after the first. 
INIan}' worms had passed with the droppings in from twenty-four to 
twenty-six hours after the first feeding. ^Nlost of the worms in these 
droppings were dead, but in all probability the embryos were still alive 
in the mature proglottids. Twelve hours after the second dose was 
given another bird was killed and it was found that only a few worms 
were left and all of these were detached and dead. The intestine was 
filled with a peculiar gray-colored, slimy substance composed mainly 
of mucus. ]\Iany entire worms and fragments were passed with the 
droppings during the period of feeding. The lye acted to some extent 
as a purgative. 

"The birds were given normal diet again, and in a few daj's they 
showed no s\nnptoms of infection. Eight days after the second dose had 
been given two more birds were killed and examinations made. One 
possessed a small fragment of a tapeworm and the other was entireh^ 
free. 

"This remedy has been known to many poultry raisers for some time, 
but they have neglected to use it, mainly on account of the fact that 
heretofore no definite evidence has ever been presented concerning its 
actual working possibilities. It may not, and in all probability will not, 
remove all of the worms, but it does remove most of them so that they 
are not serious and can be controlled in the flock as a whole." 



CHAPTER XVII 



THE TAPEWORM LARV.E 



Certain tapeworms are to be considered as to their pathogenicity 
from two important points of view. They are not only parasites in their 
adult state in the intestines of domestic carnivores and man, but, in the 
larval stage live as somatic parasites in animals used as food by man 
and it may be in man himself. Depending much upon their numbers 
and form of cyst, these cause no disturbance to their host, or, through 
their growth, pressure, and inaccessibility, may constitute a menace to 
health far more serious than that of the adult worms in the intestines. 

Three forms of cestode larvae are principallj^ concerned in this connec- 
tion, — cysticercus (Fig. 107), coenurus (Fig. 114), andXechinococcus 
(Fig. 117). A brief synoptical arrangement of these, including the 
cysticercoid and plerocercoid, follows: 

I. Larva having a caudal vesicle. Cystic 

A. Larva of large size. Liquid in caudal 
vesicle abundant. Found in tissues 
and closed cavities of Herbivora and 
Omnivora, occasionally in Carnivora. 
1. Vesicle and head single, i. e., cyst 
monosomatic and monocephalic. 

Cysticercus 
{Cysticercus 
-pisiformis, larva of 
Tcenia pisiformis) 



2. Vesicles multiple, each having a 
single head, i. e., polysomatic and 
monocephalic. 



3. Vesicles multiple, having many 
heads in each, i. e., polysomatic 
and polycephalic. 



Multiceps 

(Multiceps multicepSf 
larva of M. multiceps) 



Echinococcus 

(Echinococcus granu- 
losus, larva of E, 
granulosus) 



THE TAPEWORM LARV^ 



195 



B. Larva small. Little or no liquid in 
caudal vesicle. 



1. Larva firm, 
like process. 



terminating in a tail- 



Cysticercoid 

{Monocercus Davainece 
tetragonce, larva of 
Davainea tetragona) 



Cryptocystis 

(Cryptocystis tricho- 
dedes, larva of Dipy- 
lidium caninum) 



IL Larva without caudal vesicle. 

A. Larva worm-like. Found in muscles 
of fish. 

Plerocercoid 
(Larva of 
DiphyUobothrium 
latum) 

Cysticercosis (Measles) 

The presence of cysticerci in the connective tissue of muscles and 
other parts of the animal organism constitutes the condition commonly 
known as measles (cysticercosis). The disease is mainly of importance 
from the viewpoint of food sanitation, in view of the fact that measly 
beef or pork, imperfectly sterilized by cooking, when consumed by man, 
is likely to infect him with one or more tapeworms. 

The cysticerci of medical interest are, in their order of frequency: 
Cysticercus bovis of the ox, the cystic form of Tcenia saginata of man, 
Cysticercus ceUulosce of the pig (also of the dog, cat, and occasionally 
man), the C3^stic form of Tcenia solium of man, and Cysticercus tenuicollis 
of the sheep (occasionally of the ox and pig), the cystic form of Tcenia 
hydatigena of the dog. 

For the development and structure of the cysticerci the reader is 
referred to the Life History of the Taendiise (p. 170). 



Measles of the Ox 

Taenia saginata (T. mediocanellata). Fig. 106. Tsniidae (p. 170). — 
This species, commonly known as the beef tapeworm, of which Cysti- 
cercus bovis is the larval form, lives exclusively in the intestine of man. 
The head (Fig. 109, B) is small, pear-shaped, and has four elliptical 
suckers which are frequently pigmented. There are no hooks, and in 
place of the rostellum there is a sucker-like depression. The neck is 



196 



PARASITES OF THE DOMESTIC ANBIALS 



long and narrower than the head. The segments, which may nmnber 
from one thousand to one thousand three hundred or more, are at first 
much wider than long. The complete development of the generative 
organs occurs at about the six hundredth segment, at which location 
the segments are about as long as broad. Segments containing the 
mature embryos reach a length of 15-20 mm. (5/8-3/4 of an inch) and a 
breadth of 5-7 mm. (1/4 -5/16 of an inch). The distal margin of each 
segment is somewhat swollen and surrounds the base of the following 
segment. The genital pores are irregularly alternate and protrude from 
the margins more and more markedl}' as the segments approach the 
distal end of the chain. The median trunk of the gravid uterus has 
twenty to thirtj'-five delicate lateral branches on each side, and these 
give off shorter secondary branches. 

The length of the entire chain may be from 3 to 12 meters (9-38 feet), 
or it may reach a much greater length. 




Fig. 106. — Taenia saginata, portions of adult, — natural size (after Boas, by Kirkaldy 
and Pollard, from Leuckart). 



The eggs (Fig. 110) are more or less globular, the shell frequently 
carrying one or two filaments. As found in the feces, the eggs often 
have the outer shell absent. 

Next to a small species — Hymenolepis nana — this is the most common 
tapeworm of man in the United States, and, in fact, with the exception 
of Diphyllohothrium latum in a few districts, is the most prevalent 
species infesting man in other parts of the world. It is not found 
adult in other animals, and its cysticercus lives almost exclusively in 
the ox. 

Occurrence of Beef Measles. — That the beef tapeworm and its cj-sts 
(Cysticercus bovis) are more commonl}^ met with in the United States 
than the pork tapeworms is probably due to the fact that beef is more 
often eaten rare in this countrj- than is pork. Beef measles, therefore, 
is, in its relation to food sanitation, of the greater importance. Estimates 
made upon cattle slaughtered under Federal inspection indicate that 
nearly one per cent, of all the cattle slaughtered in the United States 



THE TAPEWORM LARV.E 197 

are affected, which, m addition to the exposure of human beings to 
tapeworm infection, is a matter involving considerable economic loss 
in the condemnation of beef otherwise of perfectly good food value. 

When it is considered that the gravid segments of the beef tapeworm 
each contain in the neighborhood of ten thousand eggs, and that eight 
to ten of these segments are usually passed by the human host each day, 
it is quite evident that, under certain not unusual conditions, the in- 
fected person could be responsible for the presence of the cj'sticerci in a 
large number of cattle. The chances for such transmission will be in 
relation to the location and habits of the carrier of the tapeworm. If 
it is his custom to defecate about stables or barnyards, the chance that 
some of the many thousands of voided embryos will reach their bovine 
hosts is obviously much increased. Where human excrement is used 
for soiling without its first having been made non-infective by special 
treatment, cysticercus infection among cattle and hogs is especially 
frequent. 

Measles is more often found in young than in aged animals. This is 
probably explained by the fact that beef animals are usually slaughtered 
young and are more susceptible to infection during the first two years of 
their life when the tissues offer less resistance to the migration of the 
embrj'os. In aged animals the cysts are likely to be in a state of ad- 
vanced degeneration or entireh' absorbed. 

Location and Appearance. — The cysticerci may be found in any 
organ, but are more especially to l^e looked for in the interfascicular 
connective tissue of striated muscle (Fig. 108). Of the nmscles invaded, 
the first to be mentioned in order of frequenc}^ are those of mastication, 
chiefly the pterygoids and masseters; following these are the heart — 
which is probably as frequently infested as the masticatory muscles — 
the muscles of the neck, intercostals, and muscular portion of the 
diaphragm. In any case it is unusual to find the cysts numerous through- 
out the muscle, though cases occur of general invasion involving most 
of the organs of the body. 

The size and appearance of the cysts vary in relation to their age and 
stage of development. Experimental infections have shown that in 
seventeen to twenty-five days they measure 2-4 mm. (3/32-3/16 of an 
inch) in length and 1.5-3 mm. (1/16-1/8 of an inch) in breadth. They 
are grayish white in color, the outer connective tissue envelope inclosing 
a fluid which surrounds the clear vesicle or bladder worm. This is 
0.5-1.5 mm. (1/32-1/16 of an inch) in diameter, and has at one point a 
yellowish white spot indicating the location of the invaginated scolex 
which will evaginate on pressure upon the vesicle. 

Experiments by Hertwig have demonstrated that the cysts become 
fully developed in eighteen weeks after the occurrence of infestation. 
At this time he found the entire dimensions of the larger cysts to be 



198 



PARASITES OF THE DOMESTIC ANIMALS 




Fig. 107. — Diagram of 
Cysticercus. 



7 by 4.5 mm. (9/32 by 3/16 of an inch), while those of the bladder were 

6 by 4 mm. (1/4 by 3/16 of an inch). 

Degeneration. — After a period of time, depending somewhat upon 

their location, the cysticerci undergo caseous degeneration followed by 

calcareous infiltration. That these changes may 

set in early has been shown in the experiments 

of Hertwig, who found them four weeks after 

infestation. Commonly the degenerative changes 

do not occur until full development is reached or 

for some time after. The cysticerci most likely 

to undergo early degeneration are those located 

in the heart, while those of the muscles of 

mastication probably survive the longest. If 

they are found degenerated in the latter muscles, 

therefore, it is not likely that cysticerci in other 

parts of the body will be living unless they are from a later infection. 
The degenerated cysts may be recognized by their yellowish, or some- 
times greenish color. They may be semisolid or quite gritty; pus may 
be present as a result of pyogenic or- 
ganisms gathered by the embryos in 
their migrations. The caseation, how- 
ever, may not always involve the para- 
site. In such cases the scolex is likely 
to be found just under the cyst wall with 
its usual characteristics retained, though 
the caudal bladder is apparently absent. 
As cysts when dissected away and ex- 
posed to the air tend to shrink by evapo- 
ration, their structure is more easily 
made out if they are kept moistened 
with a drop or two of water during the 
examination. 

Vitality. — The cysts of beef measles 
naturally disintegrate at about three 
weeks after the death of the host, there- 
fore meat kept in cold storage for this 
Fig. 108.— Fragment of beef mus- period will not be likely to Contain living 

cle, showing cysts of Cysticercus larvse. In fresh beef all will be killed 




bovis, — natural size (after Neveu 
Lemaire, from Railliet). 



by the apphcation of sufficient heat (60- 
70° C. = 140-156 F.) to cook the meat 
until its cut surface presents a uniform gray color throughout. Freezing 
for a number of days will destroy them, but this method has a disad- 
vantage in that decomposition of the meat follows rapidly, making it 
necessary that it be quickly used. Based upon experiments by Ran- 



THE TAPEWORM LARV.E 



199 



som relative to this method, Federal meat inspection regulations provide 
that beef carcasses showing a slight degree of infestation may be passed 
for food if held for six days at a temperature not exceeding 15° F. 
(-9.44° C), as an alternative to the requirement of retention for twenty- 
one days. 

Symptoms. — Symptoms in bovine measles are practically nil. There 
is rarely a history of disturbance from the presence of the cysts, and it is 
extremely exceptional for the condition to be recognized before the 
animal is slaughtei-ed. 

Measles of the Pig 

Taenia solium. — Tieniidae (p. 170). This species, to which Cysticercus 
cellulosce gives rise, also lives in the human intestine and is commonly 
referred to as the pork or armed tapeworm. It is smaller than T. sag- 
inata. The head (Fig. 109, A) is glolnilai' and loss than I mm. in diam- 




Fn;. 109. — "Head" of Taenia solium (A), of T. saginata (B), and Diphjl- 
lobothrium latum (C). (After Boas, by Kirkaldy and Pollard). 

eter; the rostellum is short and provided with a double crown of hooks. 
The neck is long and slender. The first segments are very short, grad- 
ually increasing in length and lireadth. At about one meter (39 inches) 
from the head they are as long as broad and have the generative organs 
fulh' developed. Toward the distal end of the chain they measure 10- 
12 mm. (3/8-1/2 an inch) in length and 5-6 mm. (1/4 of an inch) in 
breadth. The total number of segments is fi-om 800 to 900. The genital 
pores are more i-egularly alternate than in T. saginata. The median trunk 
of the gravid uterus has 7 to 12 ti'oe-like lateral branches on each side. 



200 



PARASITES OF THE DOMESTIC ANIMALS 



The entire length of the worm is 2-3 meters (6-9 feet), though it 
may be longer. 

The eggs (Fig. 110) are oval and provided with a very delicate shell. 
The shell surrounding the onchosphere is globular and thick. 

This tapeworm is much more rare in the United States than is T. 
saginata. In general, its distribution may be said to correspond Avith 
that of the domestic pig, correlated with the custom of eating the flesh 
of this animal raw or unperfectly cooked. The cysticercus not only 
infests the pig, but may find lodgment in man himself if the eggs from 
an adult worm infesting his intestine find their way to his stomach. 






Fig. 110.— Egg of Tsenia 
saginata, with outer shell and 
filaments; embryo, with em- 
bryonal shell, in center. Egg 
of T. solium (above), show- 
ing embryo with embryonal 
shell. 



Fig. 111. — Mature segment of Taenia 
saginata (left) and T. solium (right) , showing 
laterally branched uterus. 



For this reason, with the added one that the 
larvae may become established in the central 
nervous system or eye, Tcenia solium consti- 
tutes a much more serious infestation than 
does T. saginata. 

A simple method for determining to which 
of these two species the infecting tapeworm 
belongs consists in clearing up a voided segment, pressing it between 
two clean slides, and observing the form of the gravid uterus as the 
specimen is held before a strong light. If the median trunk shows 
numerous delicate lateral branches on each side (20-35) it indicates 
that the infection is with Tania saginata. If these branches are less 
numerous (7-12) and more robust, it may be concluded that the seg- 
ment belongs to T. solium (Fig. 111). 

If treatment has resulted in the expulsion of the entire worm, an 
exact differentiation can be made by examination of the head under low 
power magnification. The pork tapeworm will show the cephalic arma- 
ture which in the beef tapeworm is absent. 

Occurrence of Pork Measles. — While the larvse of the unarmed 
tapeworm of man live only in cattle, those of the armed tapeworm may 



THE TAPEWORM LARV.E 



201 



develop in almost an}- mannnal to which the}' find access. The hog, 
however, is the most common host, and, from the point of view of public 
health, the most important. 

As has been noted, the cysticercus of Tcenia solium (Cysticercus cel- 
lulosce) is a more dangerous parasite than that of T. saginata, as it may- 
lodge in organs such as the brain or eye with serious consequences. 
Man can readily become a victim by auto-infection from his own armed 
tapeworm, the eggs of which may reach his stomach by way of the 
pyloris, or in being conveyed to the mouth by unclean fingers. By the 
latter means, moustache twirlers and nail biters are especially exposed. 

Fortunatel}', the United States is favored by the rarity of the pork 
tapeworm and consequently its cysts. Pig measles is most prevalent in 




Fig. 112. — Stages in tapeworm larval development: a, six-hooked larva K;"| 
(hexacanth or onchosphere) of Taenia solium; b, cystic stage of same; c, same p-.^ 
with head evaginated; d, ciliated larva of Diphyllobothrium latum; e, plero- \J 

cercoid of same — all enlarged (after Boas, by Kirkaldy and Pollard, from 
Lcuckart). 

districts of foreign countries where Ijad hygienic conditions pi-evail; 
where pigs are kept near dwellings, and their flesh is eaten raw or im- 
perfectly cooked, conjoined with the practice of depositing human 
excrement in the open or spreading it upon the fields as fertihzer. In 
countries where sanitary control is of a more advanced standard the 
prevalence of the ])ork tapeworm has been greatly- reduced. 

Location and Appearance. — The muscles most often invaded by the 
cysts are those of the tongue, neck, and shoulder, then, in order of 
frequencA', the intercostals, abdominal, psoas, the muscles of the thigh, 
and those of the posterior vertebral region. Organs less often infested 
are the liver, kidneys, heart, lungs, brain and eye. 

While the cysts may be scattered and few in number, the}^ are, on 
the other hand, sometimes present in certain locations in enormous 
numbers. Kuchenmeister in one case found one hundred and thirtA'- 



202 PARASITES OF THE DOMESTIC ANIMALS 

three in a piece of meat weighing seventeen grammes (260 gr.), — propor- 
tionately eight thousand per kilogramme (2 lbs). 

More delicate and transparent than those of beef measles, the cysts 
are elliptical in form, 6-15 mm. long by 5-10 mm. broad (1/4-5/8 by 
7/32-3/8 of an inch). The wall enveloping the vesicle is a thin semi- 
transparent connective tissue membrane which, in loose connection with 
the surrounding tissue, when removed, leaves a reddened alveolar pit. 
Pressure upon the caudal vesicle causes the evagination of the larval 
head which, on examination by low magnification, is seen to be te- 
tragonal and to possess, in addition to the four suckers, a double crown 
of twenty-two to thirty hooks, — characters defining it as the larval 
head of Tcenia solium. 

At about twenty days from infestation the cyst shows as a delicate 
vesicle about the size of a pin head, with the rudimentary head indicated 
by a cloudy point, and as yet without enveloping connective tissue mem- 
brane. At the age of one hundred and ten days all of the cysts are 
approximately of equal size; the scolex is developed and lies invaginated 
into the caudal bladder. When located in organs such as the lungs, 
liver, and spleen, they often appear as grayish, caseous, calcareous, or 
purulent nodules somewhat reseml^ling those of tuberculosis. Differen- 
tiation can be made by careful examination which will reveal the hooks 
and often the larval heads. 

In some cases a diagnosis can be made while the animal is still living 
Ijy examination of the inferior surface of the tongue. If cysts are present 
in that organ, they will be near the base and at the sides of the frsenum, 
where they may be seen as semi-transparent, round or oval vesicles 
protiiiding beneath the mucous membrane. 

Degeneration. — Degeneration of the cysts may begin at any stage 
of their development, though those in the visceral organs are the first to 
undergo these changes. The process begins Avith the connective tissue 
envelop and later involves the scolex. The caseous cysts present a 
gray color, while those which have become calcified are white. In the 
older degenerated cysts the changes have advanced to transformation 
into small calcareous bodies without fluid, constituting the "dry 
measles " as termed by the butcher. In such cases the larvae are un- 
doubtedly dead. 

Vitality. — The cysticercus of pork measles is slightly more resistant 
to heat than is that of beef measles. Under post-mortem conditions it 
survives much longer. Ostertag found living larvge in pork forty-two 
days after it had been slaughtered. Preservation in cold storage as for 
beef measles, therefore, will not be efTe.ctual. All cysts will be rendered 
harmless if the pork is cooked until its cut surface presents a uniformly 
whitish color. 

Symptoms. — Ordinarily measles of the pig. as in the ox, presents 



THE TAPEWORM LARV.E 203 

no recognizable symptoms, and, unless the cysts can be seen beneath 
the visible mucous membranes, the condition is only observed post- 
mortem. If the cysticerci become lodged in nerve centers, there may be 
such manifestations as circling movements, grinding of the teeth, or, 
possibly, convulsions and opisthotonos; symptoms which can no more 
than suggest measles as a possible cause. ^ / ^^\/Uf^, ! ' 

Measles of the Sheep 

Tcenia hydatigena, of which Cysticercus tenuicollis of the sheep is the 
larval form, has been described under Cestodes of the Dog (p. 178). 

Occurrence. — Cysticercus tenuicollis has its development under serous 
membranes of the sheep principally, but it may also appear in other 
ruminants and in the pig. Infestation is by food and water bearing 
ova which have been spread about by dogs harboring the adult worm. 

Experiments have shown that the majority of the embryos reach the 
peritoneal cavity by way of the liver. Ten days after infestation tor- 
tuous hemorrhagic trails may be found upon the surface of this organ 
under the capsule of Glisson. These are produced by the migrations of 
the parasites, and are in close relation, usually at their extremities, with 
vesicles 0.5-3.5 mm. in diameter. The head is fully developed about 
the fortieth day, and the vesicle reaches its full growth at about the 
seventh month, when it may have a diameter of 1.5-5 cm. (5/8-2 inches), 
often about the size and form of a pigeon's egg. 

These cysts ("water-balls") may be found in var>'ing numbers, their 
size and location depending upon the age of the infestation. Their 
seat, especially in young animals, is usually beneath the serous capsule 
of the liver, though, particularly in old infestations, large bladders may 
])e found in most any part of the peritoneal cavity. 

As it relates to food sanitation, this cysticercus of sheep is of little 
importance. The location and size of the cysts render them easy of 
elimination from parts used as human food. 

As a mattei- of control, it is obvious, in reference to the life history of 
the tapeworm, that offal containing such cysts should be inaccessible 
to dogs. 

Symptoms. — Sheep measles can rarely be recognized until after the 
death of the animal. 

Cysticercus ovis. — Muscular cysticercosis in sheep has been shown 
by investigations within the past few years to be more common than 
had been suspected. It has been determined by Ransom that the 
cysticercus is derived from a tapeworm having its adult development in 
tiie dog, and not to a tapeworm of man as had been supposed. 

The following data in regard to this form of measles are quoted from 
Hall (Bulletin No. 260, U. S. Dept. of Agriculture): 



204 PARASITES OF THE DOMESTIC AXI^LVLS 

"Ransom's investigations showed that under careful inspection the 
percentage of afTected sheep in this countrj- has amounted to two per 
cent, or more, and that approximately twenty thousand sheep carcasses 
were retained in 1912 in abattoirs under Federal inspection on account 
of sheep measles due to this parasite. 

''The bladder worm, Cysticercus ovis, in the meat of sheep is oval and 
ranges in size from about one-third of a centimeter (one-eighth of an 
inch) to almost a centimeter (three-eighths of an inch) in length. Inside 
of this bladder there is a single tapeworm head, in which respect, as well 
as in size, this cysticercus differs from a hydatid or a coenurus. Numer- 
ous C3'sts, however, may be scattered through the musculature, so that 
in their numbers there is a compensation, so to speak, for their small 
size and lack of multiplicity' of heads. Inasmuch as the presence of these 
cj'sts calls for condemnation of a part or all of the infested carcass, ac- 
cording to the degree of the infestation, and the number of carcasses 
amounts to twenty thousand a year, this parasite has considerable 
economic interest for this countiy, and never more than at the present 
time when the "high cost of living" is such a vital topic. 

"When one of these cysticerci from mutton is ingested by a dog, the 
tapeworm head passes undigested to the dog's intestine and develops 
into a fairh' large tapeworm, comparable to the gid tapeworm. Sim- 
ilarly, this tapeworm, Toenia ovis, produces eggs which are passed 
out with the feces of the dog, and which are ingested by sheep as 
they graze over range or pasture or drink water contaminated by these 
feces, 

"The parasite has been found in Europe, Africa, and New Zealand. 
It has been found thus far in seven States in this country. It appears 
to be particular!}^ prevalent in the AVest, a fact that is possibly related 
to carelessness on the part of the western sheepmen as regards disposal 
of carcasses of sheep d^dng on the range." 

Control. — ^Measures of prevention consist in restraining dogs from 
access to the flesh of affected sheep unless it is rendered non-infective 
by cooking. Homeless dogs should be destroyed, and others going 
about where their excrement may contaminate the food and water of 
sheep should be kept free from tapeworms as a precuation, not only 
against this, but other tapeworm larvae infesting sheep. 

CcExuRosis, Gid 

Gid, turnsick, or staggers are popular terms applied to a disease of 
the brain or spinal cord, caused by the presence in these locations of 
the gid parasite Midticeps multiceps {Ccenwnis cerebralis), the coenurus 
or larval stage of the tapeworm of the dog Multiceps multiceps, Fig. 113 
(p. 179). 



THE TAPEWOR^I LARA\E 



205 



It is observed most often in sheep, more rarely in cattle, goats, and 
other ruminants. It has been reported in the horse. 

Occurrence. — Gid is a common disease in Europe where it has l)een 
known for mam- j-ears. The parasite has been observed in this country 
at least as early as 1901, though symptoms which were undoubtedly 
those of gid were authentically reported from our far western fiocks 
during at least ten years preceding. 
In 1909 Taylor and Bo^^lton found 
an outbreak in a flock of sheep about 
forty miles from Ithaca, New York. 
Necropsies in these cases revealed 
the presence of the gid parasites 
from which, by feeding to dogs, 
they claim to have raised the adult 
tapeworm. This is the first authen- 
tic instance of gid in the Eastern 
United States, and the first account 
of it was given by Dr. James Law, 
of Cornell University, in a paper 
read before the New York State 
Veterinar>^ Medical Society' in the 
same year. 

In view of the large number of 
sheep and dogs which have been 
brought to the United States from 
countries where gid prevails, it is 
somewhat remarkable that the dis- 
ease has not been more often ob- 
served here. It is probable that nu- 
merous cases have occurred which 
have passed unrecognized and con- 
sequently unrecorded, the SAaiiptoms Fig. 113.— Portions of adult gid tape- 
being ascribed to other causes. It is worm (Multiceps multiceps), — natural size 




(after Ransom, from Railliet, Bull. Xo. ^ 
Bureau An. Ind., U. S. Dept. of Agr.). 



certain that it now has a foothold in 
this country, in view of which fact, 
and the further one that in other countries it is one of the most de- 
structive parasitic diseases of sheep, veterinarians and sheep raisers 
should be on the lookout for it and take proper preventive precautions. 
The Coenurus. — The completely developed coenurus (Figs. 114 and 
116) consists of a membraneous vesicle which may vary in size from that 
of a hazelnut to that of a hen's egg. When located on the brain it tends 
to assume a spherical form; when on the cord, which is more rare, it 
becomes adaptively elongated. The wall is thin, translucent, and dis- 
tended by a colorless fluid. On the surface of the vesicle there are little 



206 



PARASITES OF THE DOMESTIC ANIMALS 



white, irregTilarh' grouped spots, each representing an invaginated larval 
tapeworm head. These vary in degree of development and in nmnber 
from four hundred to five hundred, and herein lies an essential differ- 
ence between coenurus and cj-sticercus, the latter containing but one 




Fig. 114. — Diagrammatic section of C'cx'iiuius: a, normal dis- 
position of scolex; b, c, d, e, diagrammatic representation to show 
the homology between cysticercus and coenurus (after Ransom, 
from Railliet, Bull. No. 66, Bureau An. Ind., U. S. Dcpt. Agr.). 




Fig. 115. — Brain of lamb, showing the furrows pro- 
duced by the migration of the young gid bladderworms, 
taken at a time immediately following the period of 
invasion — i. e., from fourteen to thirtj'-eight days after 
infestation, — natural size (after Ransom, from Leuck- 
art, Bull. No. 66, Bureau An. Ind., U. S. Dept. Agr.). 



Ik IK) ( id b! iddciworm 
■^ho^Mng niimatuic tapeworm 
heads, — natural size (after 
Ransom, from Railliet, Bull. 
No. 66, Bureau An. Ind., U. S. 
Dept. Agr.). 



head. In some cases the heads may be found evaginated to the surface 
of the vesicle (Davaine), when the cerebral disturbance by pressure is 
contributed to by the direct irritation from the booklets. 

Development. — Animals susceptible to gid become infested by eggs 
of the tapeworm Midticeps multice'ps which is harbored by dogs. The 
eggs and gravid segments, spread about as they are, will, in the presence 



THE TAPEWORM LARV.E 207 

of moisture and favorable temperature, retain their power to infect 
for several weeks. In dry locations and under the influence of a hot 
sun the period of their vitality is reduced, probably to a few days at 
most. Eggs, through the mediation of food and water, reaching the 
digestive juices of sheep and cattle have their shells dissolved, setting 
free the contained eml^ryos which, on reaching the intestine, penetrate 
its walls by means of their booklets. From here it is probable that they 
are passively carried to other parts of the body by the blood and hnnph 
currents. With rare exception, only those embryos which reach the 
brain or spinal cord continue their development. 

The central nervous system is reached by the embryos about the 
eighth day after the occurrence of infection, upon the arrival at which 
location they lose their booklets and transform into small cysts. In the 
course of their burrowings along the surface of the brain they leave 
small sinuous tracks which may be found three to five weeks after in- 
fection, often marked by a yellowish purulent material (Fig. 115). At 
the termination of these furrows the young bladderworms become 
stationaiy, and their development proceeds. 

In five to six weeks the cysts are about 1 cm. (3/8 of an inch) in diam- 
eter and the heads have begun to appear, these attaining their full 
development in ten to thirteen weeks. The cj'sts continue to grow 
until they have reached a diameter of from 3 to 5 cm. (1 3/16 to 2 inches), 
during which time new heads are in process of formation (Fig. 116). 
Heads in various stages of development, therefore, may be found in the 
same vesicle. 

Tabular Review of Life History of Multiceps Multiceps 
Adult Tapeworm in intestine of dog. 

Egg. — Expelled from intestines. 

Hexacanth. — Freed from egg in digestive tract when 

I ingested by sheep. 

Acephalocyst — In brain or cord of sheep. 

Coenurus (Polycephalic cyst). — Same. 

Scolex. — Attached to intestinal wall of dog after in- 

I gestion of cyst. 

Adult Tapeworm. — In intestine of dog. 

Post-mortem Appearance. — In chronic cases there are usually one 
or more cysts, rarely as many as six, though cases are recorded in which 



^208 PARASITES OF THE DOMESTIC ANIMALS 

there were more than twice this number. The lesions produced will 
differ according to the development attained by the parasites at the 
time of the examination. Primarily the lesions are disseminated, and 
the small cysts may be found at various places upon the convex surface 
of the brain, surrounded by a yellowish exudate, granules, and cal- 
careous particles, while, in the vicinity, there may be a small hem- 
orrhagic area. In cases which have presented the characteristic symp- 
toms of turnsickness, or gid properly so-called, but one large vesicle of 
advanced development is ordinarily found (Fig. 116). Such cysts are 
usually located upon the surface of the cerebral hemisphere, where, 
by their pressure, they produce an ansemia and softening of the cortical 
substance. In old cases with large cysts situated upon the brain's sur- 
face the constant compression upon the roof of the cranium may, by 
absorption, bring about thinning of the bone to such a degree that it 
will yield to even comparatively slight pressure of the fingers. 

Exceptionally, the coenurus may be found free in an excess of fluid 
in a lateral ventricle, and, again rarely, exploration of the vertebral 
canal will reveal a cyst in the lumbar or cervical region, or it may be 
at the medulla oblongata. Such cysts are much elongated, and usually 
there is but one. At the cyst's location the medullary substance is 
atrophied and softened. Such muscles as may be secondarily involved 
show the alterations of atrophy and cachexia. 

Symptoms. — As may be inferred from the foregoing, the symptoms 
presented in coenurosis will be conditional upon the age of the infection 
and the size attained b}^ the cysts, and also upon their location, the 
latter factor furnishing the two forms of the affection, — the cephalic, 
when located in the brain, and the medullary if in the vertebral canal. 

If the parasites are few in number, there will be no symptoms during 
the early stages, or the^^ may be slight and unnoticed. If there is a 
heavy invasion the cerebral disturbances caused by the migrations of the 
parasites may be manifested as stated below. According to Moller, 
however, these primary symptoms are not observed in four-fifths of 
the cases. 

Early in the infestation there is dullness, somnolence, inappetence, 
and usually a rapid loss of flesh. Visual disturbance is soon noticed, the 
animal colliding with objects which it is apparently unable to see. 
Examination of the eyes at this time will show a congestion of the 
sclera; later there is strabismus with either convergence or divergence, 
and the pupils may be unequally dilated. There are concomitant 
troubles of motility, and, as the disease progresses, the animal frequently 
falls down or may assume a recumbent position for the entire day. 
If it becomes unable to rise, it is probable that death will soon follow. 

When these early symptoms occur, they generally first appear ten 
to twenty days after infection and persist for a variable period of two 



THE TAPEWORM LARV.E 209 

to ten days. The}- then subside, and, during a following latent period 
of four to six months, it is only by close observation that anything 
abnormal about the animal can be detected. The ocular disturbances 
already referred to then appear; the head is held in a peculiar position, 
and the animal turns in circles or it ma^' stagger and stumble about, 
repeatedly falling. The movements are made in an impulsive manner, 
with feet lifted high, and the turning may be to the right or to the left, 
usually toward the side on which the brain is compressed. Other move- 
ments than turning may be exhibited, and, in fact, their character will 
depend upon the part of the brain affected by the cyst. 

These s^inptoms are not continuous, appearing several times during 
the day with intervals of comparative repose. In three to six weeks 
from their onset the animal passes into a state of complete paralysis 
and dies from exhaustion, or it may be in convulsions. 
• Such characteristic phenomena of gid are of the final stage, and are 
due to the pressure of the fully developed coenurus upon the brain and, 
in part also, to direct irritation from the booklets of the partly evag- 
inated larval tapeworm heads. It is only at this stage that the turning 
movements appear, therefore the disease does not truly merit the name 
of gid or turnsickness until these manifestations are reached. 

In gid of the spinal cord the parasite is usually located in the lumbar 
region. The chief symptom is a gradually increasing weakness and 
paralysis of the hind quarters (hydatic paraplegia). The bladder and 
rectum become involved and the animal becomes progressively weaker 
and emaciated. Death occurs in general debility and exhaustion after 
a course of one to three months. 

The s^anptoms of gid in other animals are of the same general char- 
acter as those in sheep. 

Control. — Reviewing the knowledge possessed as to the etiology of 
gid, the measures to be followed for its eradication are suggested. 
Chance infection of dogs by the tapeworm should be removed by burn- 
ing the heads harboring the cj'sts, or by cooking the affected brains if 
they are to be fed to these animals. Dogs kept in the vicinity of animals 
susceptible to gid should be given tseniafuge treatment every three 
months (p. 186). During the operation of this treatment they should 
be confined and the expelled worms, fragments, and feces collected and 
burned or deeply buried. 

Gid is a further contribution to the accumulating reasons why un- 
cared for and unnecessarj' dogs — numerically limitless in most connnu- 
nities — should be destroyed. 

Treatment. — On account of the inaccessible location of the parasites, 
treatment, except by surgical means, is useless. The operative measure 
consists in trephining the cranial cavity and removing the coenurus, 
but this can only be advised as practical in the case of animals having 



210 PARASITES OF THE DOMESTIC ANIMALS 

an especial value. Cold packs upon the head or continuous irrigation, 
accompanied by purgatives, have been recommended for the acute 
stage, but such treatment can be no moi'e than palliative, and is scarcely 
practical unless under exceptional conditions. 

In general, it is better, from considerations of economy, to slaughter 
animals upon the first evidence of gid. 

Echinococcosis 

Hydatid Disease. 

Hydatid disease is caused by the presence of Echinococcus granulosus 
{E. polymorphus, E. multilocularis, etc.) or so-called hydatid, the cystic 
stage of the tapeworm of the dog, — Echinococcus granulosus (Tcenia 
echinococcus), elsewhere referred to under the cestodes of that animal 
(p. 181). It occurs in man and all of the domestic mammals, the hy-" 
datids usually located in the organs of the abdominal or thoracic cavit}', 
most often the liver, though not infrequently the lungs, spleen, serous 
membranes, and other organs, several of which may be affected in the 
same animal. The disease is as cosmopolitan as dogs and their par- 
asites, therefore it is of world-wide prevalence. 

The Echinococcus (Fig. 117). — While the echinococcus is the largest 
of the tapeworm cysts, the dog tapeworm, of which it is the larval form, 
is but 5 mm. (3/16 of an inch), or thereabouts, in length, and consists 
of a head and three segments. When uninfluenced by pressure, the 
echinococcus cyst is more or less spherical in shape and presents a com- 
plex structure, the parts of which may be set forth for study as follows: 

1. An external cuticular membrane (hydatic membrane). 

2. An internal germinal membrane. 

3. The fluid which distends the vesicle. 

4. The proligerous vesicles, which contain the larval tapeworm heads. 

5. The daughter vesicles. 

Surrounding the whole is a capsule formed from the connective 
tissue of the organ in which the structure is lodged. 

1. The cuticular membrane limits the echinococcus externally. It 
is whitish in color, concentrically laminated in structure, and in large 
vesicles may attain a thickness of 1 mm. 

2. The germinal membrane is much thinner than the cuticular, 
usually not exceeding 20-25 microns in thickness. On its internal sur- 
face there appear groups of small papilke, representing the beginning 
development of the proligerous vesicles. 

3. The hydatic fluid is colorless or yellowish and in reaction is neutral 
or slightly acid. It may contain a number of substances, mostly de- 
rived by endosmosis from the blood and lymph of the organ invaded. 

4. The proligerous vesicles appear on the internal surface of the 



THE TAPEW0R:M LARV.E 



211 



germinal membrane when the mother vesicle has developed to a suffi- 
cient size. At first papillary, each has a cavity that gradually enlarges, 
and the vesicles thus formed have an attachment to the germinal mem- 
brane by a short pedicle. Within each there develops a variable num- 
ber — usuallv five to twentv or moi-e — of little oval bodies. These are 




Fig. 117. — Diagram of EchiuDcocus liydatid: cu, thick cuticu- 
lar monibrane; gr, germinal ni("iiil)raiic; a. b., development of 
proligerous vesicle; c, development of the heads according to 
Leuckart; d, development of heads according to Moniez; e, fully 
developed brood capsule with heads; f, brood capsule has ruptured 
and the heads hang into the lumen of the hydatid; g, liberated 
head floating in the hydatid; h, i, k, 1, m, formation of secondary 
exogenous daughter cyst; n, o, p, formation of endogenous cyst, 
after Kuhn and Davaine; cj, daughter cyst with one endogenous 
and one exogenous grand-daughter cyst; r. s., formation of en- 
dogenous daughter cysts, after Xaunyn and Leuckart; r, at ex- 
pense of head; s, from brood capsule; t, constricted portion of the 
mother cyst (copied from Osborn's "Economic Zoology," after 
R. Blanchard; Bureau An. Ind., U. S. Dept. Agr.) 

the lar\'al tapeworm heads. When completely formed the heads meas- 
ure slightly more than 0.1 mm. and show the suckers and double crown 
of hooks. 

5. Daughter or secondary vesicles sunilar in character to the mother 
vesicle have origin in the hydatic membrane which they distend and 
finally rupture, faUing into or outside of the mother vesicle. In the 
first case they are termed endogenous vesicles., in the second exogenous 



212 PARASITES OF THE DOMESTIC ANIMALS 

vesicles. The exogenous vesicles are capable of implantation upon 
organs somewhat remote from the primary vesicle. This occurs more 
commonly in the pig and ruminants than in man. 

The daughter vesicles may, in the same manner, give off grand- 
daughter vesicles which, like the parent vesicles, maj^ be endogenous 
or exogenous. 

All of these vesicles develop proligerous vesicles and consequently 
the larval tapeworm heads, or they may remain sterile, in which case 
they are referred to as acejjhalocysts. 

It will be noted from the foregoing that one onchosphere ma}^ develop 
hundreds of tapeworm heads. 

The echinococcus is usually considered as one species, though there 
is a form which has received the name of Echinococcus multilocularis 
{E. alveolaris), thought to be due to a tapeworm -.hffering slightly from 
E. granulosus. Its main distinguishing character is the size of the 
vesicles, which does not exceed that of the pea. They have a honey- 
comb arrangement, and are filled with a gelatinous material, the majority 
of the cysts remaining sterile. The mass of vesicles may grow to the 
size of a child's head, and constitutes a verj^ fatal form of echinococcosis. 
It has been found in the ox and pig, but more frequently in man. 

Development. — Embryos finding their way to the intestine with 
food or water that has been contaminated Avith egg-containing excrement 
of dogs are probably carried to the liver by the portal system. Four 
weeks after infecting pigs, Leuckart found small white nodules about 
1 mm. in diameter, each with a capsule derived from the hepatic con- 
nective tissue, and containing within it the globular echinococcus. At 
about five months the cysts were the size of a hazelnut, and each con- 
tained a thick-walled whitish-colored vesicle, — the mother vesicle. 

The development of the echinococcus is slow. It may remain simple 
and its growth be limited to increase in volume and thickening of the 
cuticular membrane, in which case it may reach a diameter of 15 cm. 
(6 inches) . Generally its size does not exceed that of an orange, and its 
growth is attained by the formation of secondary vesicles. Where these 
pass to the inside of the mother vesicle this becomes dilated in an irreg- 
ular manner, influenced somewhat by the compression of the adjacent 
organs of the host (Fig. 117). 

As regards the formation of the daughter vesicles, the process has 
usualh^ been described as a normal one following the complete develop- 
ment of the hydatid. Deve, in a paper upon this subject (1917), states 
that every multivesicular cyst is one which has had its vitahty menaced, 
and that the endogenous vesicles are the result of a defense reaction. 
The simple cyst with its brood capsules, according to this authority, 
represents the normal Iwdatid. 



THE TAPEWORM LARV.E 213 

Tabular Review of Life History of Echinococcus Granulosus 
Adult Tapeworm. — In intestine of clog. 

Egg. — Expelled from intestines. 

I 
Embryo . — Released from egg in digestive tract after 
I ingestion by pig, ruminant, or other 

1 mammal. 

Mother Vesicle (Hydatid).— In liver or other organ of 
I I same. 

Daughter Vessicles 

Scoleces. — ^Attached to intestinal wall of dog 
i after ingestion of brood capsules con- 
1 taining larval heads. 
Adult Tapeworms. — In intestine of dog. 

Regarding the longevity of the hydatids, such information as is pos- 
sessed is furnished mainly by cases of hydatid disease occurring in man. 
A case is recorded of the persistence of an echinococcus cj^st in a horse 
for seven years. Usually when found in lower animals it is in those 
slaughtered for food, and in most such cases the animals are not old 
enough for the hj^datids to have reached their full development. It is 
probably for this reason that the disease is clinically unobserved or is 
much less serious in these animals than in man where the hydatid devel- 
opment remains uninterrupted. 

The hmnan evidence seems to indicate that the longevity of the cyst 
may be only limited by that of its host, for a case is recorded where it 
had existed for thirty-five years and another where the swelling had 
gradually spread over the face for fortj^-three years, and when operated 
upon had attained the size of a child's head. 

Post-mortem Appearance. — Hepatic echinococcosis is accompanied 
by considerable alteration. When the cyst is large the liver becomes 
hj^pertrophied and its weight may be increased as much as ten times 
that of normal. The increase in volume may compress neighboring 
organs, hindering their function and displacing them. The diaphragm 
especially is crowded and pressed forward upon the lungs. The surface 
of the liver has protruding elevations of various size and number, and 
Glisson's capsule is noticeably thickened, perhaps forming adhesions 
with contiguous organs. Section of the organ reveals cavities of un- 
equal size from which the hydatic liquid with contained vesicles flows 
out. The connective tissue capsules of the cysts will vary in thickness 
from 3 to 10 mm. (1/16 to 3/8 of an inch). These capsules are structurally 



!14 



PARASITES OF THE DOMESTIC ANIMALS 



somewhat compact, and are generally little adherent to the wall of the 
hj'-datid. 

Old liA'datids may become considerabty modified or completely 
destro3'ed. In such cases the walls are much thickened and show 
degenerative changes. The fluid diminishes and disappears with the 
contraction of the cavity, the degenerative material in the walls be- 
comes more dense, there is calcareous infiltration, and, finally, the 
h3'datid may be transformed into a calcareous mass. 

Symptoms. — The symptoms of hepatic echinococcosis in lower 
animals are, as a rule, too vague for recognition of the specific affection; 




Fig. 118. — Echinococcus granulosus, with fibrous sac laid )Dacl<, showing 
with brood capsules (after Leuckart). 



,-datid 



it usually remains for post-mortem examination to establish the diagno- 
sis. Pulmonary echinococcosis is generally accompanied by the hepatic 
form, and may exhibit respiratory disturbances, as accelerated respira- 
tion and dyspnoea, — sjanptoms which may be contributed to by pressure 
•of the enlarged liver upon the diaphragm. In the region invaded by tlie 
hydatid the vesicular murmur is lessened or wanting, while in parts 
nearby it is increased. Percussion will generally definitely establish 
its location. 

Hydatid disease rarely progresses to a fatal termination in lower 
animals. 

Control. — As the tapeworm from which the echinococcus is derived 



THE TAPEWORM LAR\ .E 215 

is harbored by the dog, rarely the cat, infection of man and domestic 
animals is by the dissemination of the eggs of this tapeworm with the 
excrement of its hosts. It follows that all hydatic viscera in slaughter- 
ing establishments or elsewhere should at once be destroyed bv burning, 
thus preventing the larval tapeworm heads from reaching the intestines 
of dogs and cats. Where the disease has appeared it is a good precau- 
tionary measure, though often impractical, to administer tceniafuge 
treatment (p. 186) at repeated intervals to all dogs in the vicinity. 
During the treatment the animals should be confinetl where their feca! 
material can be caiefully collected and burned. 



CHAPTER XVIII 

PHYLU:\I III. CCELHELISIIXTHES 

The Smooth and Segmented Roundworms 

The Ccelhelniinthes are distinguished from all of the worms thus far 
considered by the presence of a coelom, or bodj' cavity located between 
the outer body wall and the intestine. With the exception of the thorn- 
headed worms, the digestive tract is complete, and there may or may 
not be a closed blood circulation. Excretory vessels connect the cavity 
of the bodj^ with the outside. The body muscles are ''epithelial muscle 
cells" developed from the outer epithelial wall of the coelom. Sub- 
groups exhibit distinct differences in the character of the coelom. In 
the Annelida, to Avhich the earthworms belong, it is segmented, the 
segments (somites) corresponding to the annulations or ringing of the 
body wall. In the Nemathehninthes, which includes most of the par- 
asitic species, there is no segmentation of the body cavity or annulation 
of the body wall. In the Hirudinea, the annulated group which con- 
tains the leeches, the coelom is but shghtly developed, and usually the 
annulations outnumber the somites. 

The phylum Coelhelminthes has the two classes named below for 
discussion in this work, the first containing all of the endoparasitic 
worms which remain to be considered, while of the second, only the 
leeches are of direct parasitic interest. 

Class I. Nemathehninthes. — Body without external or internal seg- 
mentation. 

Class II. Annelida. — Body with" external and internal segmentation. 

Class I. Nemathelminthes 

Coelhelminthes (p. 216). — This group contains the roundworms, or 
so-called threadworms, though not all are filiform. There are both 
free and parasitic forms, examples of the former living under stones 
and in other moist places. The parasitic species are by far the more 
numerous and important. 

The bod}^ is elongated, and, in being cylindrical, differs from that of 
the Platyhelminthes which is flat, while the absence of annulations and 
segmentation distinguishes it from that of the Annelida. 

The class includes two parasitic orders. The first contains the typical 



CCELHELMINTHES 



217 



representatives of the class and, with the exception of the thorn-headed 
worms, all of the species of medical interest. 

Order I. Nematoda. — Alimentary canal present. 

Order II. Acanthocephala. — Thorn-headed. Alimentary canal ab- 
sent. 

Order I. Nematoda 

Xemathelminthcs (p. 216). — The order Nematoda includes numerous 
species having a wide distribution as parasites of animals and plants. 
The outer surface of the 
body is covered by a 
tough chitinous cuticle 
which is secreted b}' an 
underlying layer corre- 
sponding to the epithe- 
lium and derma. The 
cuticular surface may be 
plain, striated, or more or 
less mottled. Transverse 
section of the body wall 
shows four thickenings — 
two median and two 
lateral — corresponding to 
the dorsal, ventral, and 
lateral lines which are 
cUsposed longitudinally. 
Within the lateral thick- 
enings are contained the 
two excretory vessels 
which, in the vicinity of 
the head, unite by a 
transverse commissure 
reaching the exterior on 
the ventral surface. The 
muscles are a layer of 
vesicular cells derived 

from the epithelium of the outer coelomic wall. They are divided by 
the lateral and median lines into four fields, and so project into the 
coelom as to occupy considerable of its space (Fig. 119). 

The digestive system is simple and complete, beginning with the 
anterior terminal mouth and ending in an anus which is ventral and 
close to the caudal extremity of the body, A muscular esophagus suc- 
ceeds the mouth, soon expanding to form a bulbous sucking organ 
lined throughout with a cuticular layer. From this point to 




Fig. 119. — Transection of t)ody of Ascaris equi (fe- 
male), showing cuticular wall, muscle cells and proto- 
plasmic processes extending into ccclom, transversely 
cut portions of ovary and uterus, and intestinal canal in 
center (from microphotograph by Hoedt). 



the 



218 



PARASITES OF THE DOMESTIC ANIMALS 



anus the alimentary canal is usually a uniform tube with little or 
no flexion. 

The nervous system consists of a nerve ring surrounding the esophagus, 
and of the nerves given off from this ring passing forward and back, 
the largest of which are in the dorsal and ventral lines. Along the course 
of these nerves there are ganglionic cells, but there is no massing to form 
true ganglia as occurs in the Annelida. 

The sexes are usually separate, hermaphroditic forms occurring 
among free-living species. In general, the females attain a distinctly 

greater length and thickness of 
the body than do the males, and 
in other respects they can easily 
be distinguished. The males are 
usually provided with chitinous 
copulatory organs known as 
spicules. These are curved, 
spine-like structures which lie 
in a sheath close to the anus, 
and they can be protruded or 
retracted through the cloacal 
opening (Fig. 120). They are 
usually two in number, but 
there ma}^ be but one. The 
character of the spicules often 
serves as a guide in the estab- 
lishment of relationships of cer- 
tain groups. Surrounding the 
spicules there is, in some forms, 
a membraneous expansion which 
is referred to as the caudal bursa 
or pouch. This structure is best 
developed in the Strongylidse, 
where its varied characteristics 
furnish an aid in the recognition 
of species. The bursa is a clasp- 
ing organ used in copulation, while- the spicules serve to direct the course 
of the semen. In the female there is a special genital opening,— the 
vulva, located on the ventral anterior half of the body, or it may be to- 
ward the anus, its position varying according to species. The cylindrical 
body is usually more or less distended with eggs, and frequently the 
egg-packed uteri can be distinctly seen under low magnification and 
transmitted light. 

The internal reproductive systems of the male and female are much 
alike. In both they are long tubular organs, coiled forward and back. 




Fig. 120. — Posterior extremity of male nema- 
tode; diagrammatic longitudinal section: cl, 
cloaca; d, intestine; m, retractor muscle of 
spicule; s, sheath of spicule; w, body-wall (after 
Boas, by Kirkaldy and Pollard). 



C(ELHELMINTHES 219 

and lying loosely in the coelomic cavity. In the nial(> this genital tract 
is always single, the finer part of the tube constituting the testis, the 
heavier remaining portion serving as a seminal vesicle and terminating 
in the duct. The ovaries and uteri are likewise continuous structures, 
the former being constituted by the finer portions, while the uteri are 
usually much distended (Fig. 119). In certain forms there is but one 
genital tube in the female, but in most all there are two which unite 
close to the external opening to form the vagina. There is no distinct 
vitellarium as in the flatworms, the ovary assuming the function of this 
gland. 

The eggs are usually globular or ovoid in shape; as there is copulation, 
they are fertilized in the uterus. Following this the development may 
or may not take place while the eggs are retained. 

As to the terms oviparous and ovoviviparous. frequentl}' used in 
summarizing the characteristics of parasitic groups, it may be well to 
direct attention here to their correct application. 

The term oviparous is properly applied to the oviposition of eggs 
which undergo incubation after they have been oviposited, or to the 
oviposition of eggs which have been incubated within the genital cavity 
of the female and at the time they are oviposited contain enil)ryos more 
or less developed. 

The word ovoviviparous is commonly used hi reference to the oviposi- 
tion of eggs containing embryos developed and ready to emerge at the 
time the eggs are extruded, as might be in the last-stated case. It is 
more correctly applied where the embryos, having been developed, 
escape from the eggs while these are still within the body of the female. 

In other words, the escape of the embryos from the eggs occurs out- 
side of the body of the parent in the oviparous method, within the parent 
body in the ovoviviparous. 

The term viviparous, often applied in biology for ovoviviparous, 
has reference to the typical mammalian method of giving birth, where 
the egg is not concerned in this process, and there is consequently no 
hatching. 

Parasitism of the Nematodes in General . 

In most of the nematode parasites there is a post-embryonic free 
existence, the infection of the host being direct and necessary to the 
parasite's sexual maturity. A notable exception is furnished by Trich- 
inella, where there is no period of free life, the transfer from host to 
host being accomplished by the ingestion of food containing the encysted 
larvae. 

The degree of injury to their hosts by the nematodes varies consider- 
ably and is frequently not characteristic. In general, it may be said 
to depend upon the number of the parasites present, but the seriousness 



220 PARASITES OF THE DOMESTIC ANIMALS 

of their effect does not depend upon this wholly. A relatively light 
invasion with forms which elaborate toxins possessing a high degree of 
toxicity may have a more deleterious influence upon the health of the 
animal than a heavier infestation with worms from which the elimina- 
tions are less toxic. Again independent of numbers, adult worms or 
their larvae can, by their migrations, set up in their unusual locations 
serious inflammatory and degenerative changes which may be of an 
infective character due to the bacteria which they transport. 

Intestinal worms which attach to the mucosa are far more capable 
of producing serious effects than those which live free in the intestinal 
contents. The former live upon the tissues of their host and cause at 
their attachment a wound through which infection may readily enter, 
while the latter obtain their nourishment from the partly digested 
alimentary material and do not directly lacerate the mucosa. 

Location is a main pathogenic factor. This may be accidental by 
active or passive migration, as in the case of adult or larval filarise, 
which seem capable of wandering to most any part of the body, or it 
may be specific, certain nematodes normally infesting only the intestines, 
others the respiratory tract, while some occupy the blood vascular 
system in their larval state or both as larvae and adults. Again, Trich- 
inella spiralis causes its most serious disturbance during the migration 
of the embryos through the musculature of its host. In general, it may 
be said that nematode invasion of the intestines is less serious than that 
of the respiratory tract. The injurious effects from verminous parasitism 
of the blood are usually due to injury to the vascular walls, or, if the 
worms are numerous and massed, to interference with the blood flow. 
Following upon this there may be the production of a thrombus and 
formation of emboli with the subsequent development of aneurism. 
AVhile parasites in the blood in any case constitute a serious infection, 
the greater number of specific conditions due to such parasitism are 
caused by blood-invading Protozoa. 

The specific limitations as to host of the parasitic worms is probably 
much influenced by the character of the nutriment with which they are 
supplied in each particular case. Certain hosts having no more than a 
class relationship may harbor intestinal worms of the same species, but 
are more likely to do so if there is a measure of similarity in the char- 
acter of the hosts' alimentation. This is exemplified in the distinctly 
omnivorous animals, man and the pig, each furnishing hostage for the 
intestinal worms Ascaris lumbricoides (A. suis) and Gigantorhynchus 
hirudinaceus, while, again, the carnivorous dog and cat both harbor 
Belascaris marginata and Anktjlostoma canina. 

Opportunity is also a factor. Animals of similar diet are alike exposed 
to infection by food specific for or most likely to be contaminated with 
larvae or eggs of certain species of parasites. Such parasitism as the 



CCELHELMINTHES 221 

invasion of the intestines of man by the thorn-headed worm of the pig 
{Gigantorliynchus hirudinaceus) is regarded as straj" or accidental, ])iit 
if the grub of the May beetle, the larval host of this worm, constituted 
a choice morsel of diet for man as it does for the pig, it is probable that 
the thorn-headed worm would much more frequently inhabit man's 
intestines. 

Adaptive modifications from a free to a parasitic life, and adaptations 
of the parasite to differing host environments, or to new locations taken 
up in the body of the same host, are best exemplified in the Protozoa. 
In the more complexly organized wo^ns the faculty of adaptation is 
possessed in less degree; though undoubtedl}- the parasitic forms have 
without exception passed through at least the first of the gradations 
mentioned. The adult nematodes infesting the respiratory tract, as 
Didyocaulus filaria of sheep, and those infesting the blood vascular 
system, as Dirofilaria immitis of the dog, have probabl.y reached these 
regions from a priniar}' parasitism in a less obscure part of the body, 
the adaptivitj' having become sufficiently fixed that the conditions 
supplied by the location later acquired are now specifically essential 
to their sexual development and reproduction. 

Treatment in General. — Treatment in nematode helminthiasis has 
in view primarily the expulsion of the worms, and secondarih' the 
building up of the general health of the animal. Anthelmintics act by 
destroying or in some way so affecting the worms that they are easily 
expelled from the body. An agent capable of killing the parasites may 
have a like effect upon the host if used without due precaution; in any 
event it is likel}- to be too drastic and cause an acute disturl)ance more 
serious than the subacute one which it is sought to remedy. In the 
case of intestinal worms, remedies which reduce them to a sufficiently 
passive state that they may be readily swept out by the action of a 
purgative are to be preferred; and here the effect of the vermifuge 
upon the host, as compared with that of a true vermicide, is one 
of degree, and the tolerance of the patient is to be taken into con- 
sideration. 

Essentially the success of vermifuge treatment will ])e influence 1 by 
the location of the worms; only those in tubular organs in communica- 
tion with the outside can be reached by such medication, while its action 
will be hampered in the case of those which burrow into and attach 
upon the mucous lining. 

It has been said that it may be taken as an axiom in helminthology 
that each worm in the body develops from an egg or larva which has 
entered from without. Worms do not go on multiplying indefinitely 
with the production of new adult generations in the same host. The 
degree of the infestation, therefore, depends primarily upon the degree 
of contamination of food or water taken in by the animal, and secondarily 



2^12 PARASITES OF THE DOMESTIC ANIMALS 

upon the susceptibility and favorable hostage offered by the individual 
to the parasite. 

It follows that preventive measures should be based upon the life 
history of the species to which such measures are applied. Where 
this is known and intelligently taken advantage of, the problem of the 
eradication of the parasites becomes much easier of solution than it 
otherwise would be. For the same reason, more detailed reference to 
control is reserved for application to particular cases in the pages to 
follow. 

The nematode parasites are to be considered under seven families 
having marked differences as to parasitic habit and also as to degree 
of injury which they cause in their hosts. These are as follows: 

Family I. Ascaridae. 

Family II. Oxjau'idae. 

Family III. Heterakidse. 

Family IV. Filariidse. 

Family V. Strongjdida?. 

Family VI. Eustrongylidae. 

Family VII. Trichinellidse. 

Classification of Parasites of the Phylum Ccelhelminthes 

Phylum III. Coelhehninthes. P. 216. 

Class A. Nemathelminthes. Smooth-bodied roundworms. P. 216. 
Order 1. Nematoda. P. 217. 
Family (a) Ascaridae. P. 229. 
Genus and Species: 

Ascaris equi. Host, equines. P. 233. 
Belascaris marginata. Host, dog, cat. P. 237. 
Toxascaris limbata. Host, dog. P. 238. 
Ascaris lumbricoides. Hosts, man, hog, sheep. P. 239. 
A. vitulorum. Host, cattle. P. 241. 
Family (b) Oxjairidse. Seat worms. P. 235. 
Genus and Species: 

Oxyuris equi. Host, equines. P. 235. 
Family (c) Heterakid^. P. 242. 
Genus and Species: 

Heterakis perspicillum. Host, poultry. P. 242. 
H. vesicularis. Host, poultry. P. 242. 
Family (d) Filariidge. P. 244. 
Genus and Species: 

Set aria labiato-papillosa. Host, equines. P. 244. 
Habronema megastoma. Host, equines. P. 245. 
H. microstoma. Host, equines. P. 246. 



CCELHELMIXTHES 223 

Gon^ylonema scutata. Hosts, sheep, cattle. P. 247. 

Filaria labiato-papillosa. Hosts, cattle, deer. P. 248. 

Dirofilaria iinmitis. Host, dog. P. 248. 

Spiroptera sangiiinolenta. Host, dog. P. 250. 

Ardiienna strongylina. Host, hog. P. 251. 

Physocephahis sexalatiis. Host, hog. P. 252. 

Dispharagus spiralis. Host, poiiltiy. P. 254. 

D. hamulosiis. Host, poultry. P. 254. 

D. nasiitus. Host, poultiy. P. 254. 

Tetrameres fissispina. Host, poultry. P. 254. 
Family (e) Strongylida. P. 255. 
Genus and Species: 

Stephanurus dentatus. Host, hog. P. 295. 
Subfamily (a) Metastrongylins AVoi-ms of the respiratory tract. 
P. 256. 
Genus and Species: 

Dictj'ocaulus filaria. Hosts, sheep, goat. P. 256. 

Synthetocaulus rufescens. Hosts, sheep, goat. P. 257. 

S. capillaris. Hosts, sheep, goat. P. 258. 

Dictyocaulus yiviparous. Host, cattle. P. 259. 

jMetastrongylus apri. Host, pig. P. 260. 

M. breyiyaginatus. Host, pig. P. 260. 

Dictyocaulus arnfieldi. Host, equines. P. 261. 

Htemostrongylus yasorum. Host, dog. P. 261. 

Synthetocaulus abstrusus. Host, cat. ?. 262. 
Subfamily (6) Trichostrongylina. Woi-ms of the stomach and 
intestine. P. 268. 
Genus and Species: 

Hiemonchus contortus. Hosts, sheep, goat, cattle. P. 268. 

Cooperia cui'ticei. Hosts, sheep, goat. P. 268. 

Ostertagia nuu-shalli. Host, sheep. P. 269. 

Trichostrongylus Lnstabilis. Hosts, sheep, goat. P. 271. 

Ostertagia ostertagi. Host, cattle. P. 272. 

Nematodirus filicollis. Hosts, cattle, sheep, goat. P. 273. 

Cooperia oncoi;)hora. Hosts, cattle, sheep. P. 275. 
Subfamily (c) Strongylinae. Worms of the large and small in- 
testines. P. 280. 
Genus and Species : 

Q^sophago.stomum columbianum. Hosts, .sheep, goat. P. 
281. 

O^. yenulosum. Hosts, sheep, goat. P. 282. 

(E. radiatum. Ho.st, cattle. P. 285. 

(E. subulatum. Host, hog. P. 287. 

Chabertia oyina. Host, sheep. P. 287. 



224 PARASITES OF THE DOMESTIC ANIMALS 

Strong3'lus equinus. Host, equines. P. 288. 
St. edentatus. Host, equines. P. 289. 
St. vulgaris. Host, equines. P. 289. 
Cylicostomuni tetracanthum. Host, equines. P. 289. 
Ankvlostoma canina. Hosts, dog, cat. P. 291. 
Uncinaria stenocephala. Host, dog. P. 292. 
Bunostomum trigonocephalum. Host, ruminants. P. 293. 
B. phlebotomum. Host, cattle. P. 293. 
S3aigamus trachealis. Host, fowl. P. 293. 
Sj-n. bronchialis. Host, water fowl. P. 293. 
Family (f) Eustrongylida?. P. 296. 
Genus and Species : 

Dioctoph\ane renale. Hosts, dog and other animals. P. 296. 
Family (g) Trichinellidffi. P. 299. 
Genus and Species: 

Trichuris ovis. Host, ruminants. P. 299. 
T. crenatus. Host, hog. P. 299. 
T. depressiusculus. Host, dog. P. 300. 
Trichinella spiralis. Hosts, hog, rat, mouse, and other 
mammals. P. 301. 
Order 2. Acanthocephala. P. 306. 

Family (a) Gigantorhynchidae. P. 306. 
Genus and Species : 

Gigantorhynchus hirudinaceus. Host, hog, man. P. 306. 
Class B. Annelida. Annulated worms. P. 307. 
Order 1. Hirudinea. Leeches. P. 307. 
Family (a) Gnathobdellidse. P. 308. 
Genus and Species : 
Hirudo medicinalis. Medicinal leech. P. 309. 
Hsemopis sanguisuga. Horse leech. P. 308. 

With slight omissions, the following descriptions of superfamilies 
and their subdivisions are transcribed from a work upon the nematode 
parasites of small mammals by Maurice C. Hall (1916). 

''Esophagus consists of a chitinous tube which is embedded along 
the greater part of its length in a chain of single cells. The anterior 
portion of the body, occupied by the esophagus, usually very slender; 
the posterior portion, occupied by the intestine and reproductive 
organs, more or less swollen, or at least thicker than the anterior portion. 
Anus terminal or subterminal. Male with only one spicule or with no 
spicule. One testis. Female with one ovary. Vulva situated at the 
junction of the anterior and posterior portion of the body. Oviparous 
or ovoviviparous. In digestive tract or adnexa or in urinary bladder 
as adults. Life history usually simple. Larva of at least one intestinal 



CCELHELMINTHES 2^25 

form penetrates to and enc>'sts in the musculature of the host of the 
adult worm. 

Superfamily Trichmelloidea Hall, 19 IG. 

Type-family Trichinellidae Stiles and Crane, 1910. 

"Male without spicule. Female ovoviviparous; the spherical egg is 

suri-ounded with a delicate membrane and is without a true eggshell. 

Worms in the intestine of the host animal. 

Subfamily Trichinelliuie Ransom, 1911. 
Type-genus Trichinella Railliet, 1895. 
"Male with one spicule, or, exceptionally, with onlj- a copulatory 
sheath. Eggs lemon-shaped, the apertures at each end closed with 
opercular plugs. Development, so far as known, direct and without 
intermediate host. Egg development often slow. Eggs with thick shell; 
•do not hatch until swallowed by a suitable host. 

Subfamily Trichurinse, Ransom, 1911. 
Type-genus Trichuris, Roederer, 17G1. 
"Mouth connnonly provided with two or three prominent or incon- 
spicuous lips which are often supplied with papilke, but the mouth 
may be of variable shape and without lips. When three lips are present 
one is median and dorsal, the others are submedian and are approximated 
in the ventral line. Buccal capsule is not present. Males are provided 
with one or two spicules, rarel}' with none. Female with two ovaries, 
oviparous, rarely, as in Oxyuris vivipara, viviparous. As a rule develojj- 
ment is direct and without intermediate host; exceptionall}' (as in 
ascarids of fish) there is an intermediate host. 

Superfamily Ascaroidea, Railliet and Henry, 1915. 
"Mouth with three prominent lips supplied with joapillffi, the dorsal 
lip being median and the two other submedian and approximated in 
the ventral line, or with three main lips and three relativeh' prominent 
and inconspicuous intermediate lips (interlabia). Male usually with 
two spicules. Caudal extremity of female terminates conically and 
fairly abruptly. 

Type-family Ascaridse, Cobbold, 1864. 
Type-genus Ascaris, Linnaeus, 1758. 
"Mouth provided with two or three lips or without lips and of va- 
riable shape. Esophagus cylindrical or club-shaped, often followed by 
a distinct bulb. Males with a preanal sucker, which may be limited 
by a chitinous ring or a delicate cutaneous membrane, or formed by a 
simple longitudinal depression; this sucker is not present in Seuratum. 
Two spicules, one or l)oth of which may tend to atrophy or show im- 
perfect chitinization, and with accessory piece present or absent. 'S'ulva 
near middle of body. 

Family Heterakidip, Railliet and Henrj', 1914. 
"Mouth with three well-defined lips; esophageal bulb present or 



226 PARASITES OF THE DOMESTIC ANIMALS 

absent; preanal sucker neaiij^ circular and limited by a chitinous ring; 
spicules equal or unequal. 

Subfamily Heterakinse, Railliet and Henry, 1912. 

Type-genus Heterakis, Dujardin, 1845. 

"Mouth with simple, usually inconspicuous Hps. Male usually with 

one spicule, at times reduced, imperfectly chitinized or absent. Caudal 

extremity of female much elongated and sublobate. Vulva anterior. 

Eggs characteristically flattened on one side. 

Family Ox;ynaridse, Cobbold, 1864. 

Subfamily Oxjiirinse, Hall, 1916. 

Type-genus Ox^auis, Rudolphi, 1803. 

''Males with a well-developed caudal bursa supported by rays; in 

forms near the outer limit of the superfamily the bursa is occasionally 

verj^ small and the rays atj^pical, or the bursa may be lacking altogether. 

Esophagus without posterior bulb. Mouth naked or with a buccal 

capsule and six papillae, distinct or indistinct. Male usually with two 

spicules and female usually with two ovaries. Oviparous or viviparous. 

Superfamily Strongyloidea, Weinlancl, 1858. 

"Buccal capsule present. Bursa highly developed, with a typical 

system of supporting rays consisting of one or two dorsal raj'S and two 

lateral ray systems of six rays each. Male with two spicules and female 

with two ovaries. Vulva at times anterior to the middle of the body, 

but usually posterior of the middle. Oviparous, eggs segmenting when 

laid. Development, so far as known, direct. Embryo rhabditiform. 

In digestive, rarely in respiratory system. 

Type-family Strongylidae, Cobbold, 1864. 

"Buccal capsule present. In digestive, occasionally in respiratory, 

system. Development direct, at tunes complex, involving cutaneous 

infection, nodular development or other embryonic or larval migration. 

Subfamily Strongylinae, Railliet, 1893. 
Type-genus Strongylus, Mueller, 1780. 
"Simple mouth without a buccal capsule. Parasitic only in the di- 
gestive system. Development direct and simple, involving in all cases 
known only the possibility of infection by ingestion. 

Family TrichostrongyUda), Railliet, 1915. 
' ' Body straight or curved, but not regularly coiled in a spiral . Females 
with two ovaries. 

Subfamily Trichostrongylinse, Leiper, 1908. 
Type-genus Trichostrongylus, Looss, 1905. 
"Buccal capsule present or absent. Bursa present or absent; when 
present, frequently atypical in structure and number of rays. Ovip- 
arous, with eggs in variable stages of segmentation when oviposited, 
or viviparous. Embrj'o not rhabditiform. Usually in respiratory and 
circulator}' S3^stems, rarely in digestive sj-stem. 



COELHELMINTHES 227 

Family ]\Ietastrongylidse, Leiper, 1908. 
''Buccal capsule absent. ]Male with two equal spicules and female 
with two ovaries. Eggs in van-ing stages of development when ovipos- 
ited. Embiyo not rhabditiform. Parasitic in the respiratory and cir- 
culator}' systems. 

Subfamih' Metastrongj-linte, Leiper, 1908. 
T3'pe-genus Metastrongylus, Molin, 1861. 
"Body usually very long and slender. Mouth with two lips or with- 
out lips and surrounded with circumoral papilla?. Esophagus slender, 
without posterior bulb. Anus subterminal. INIale with a single spicule 
or with two unequal spicules. Tail provided with papillae, usuall}^ 
curved spirally, and with bursal alse present or absent. Female larger 
than male. Vulva present, or, less often, absent in gravid females; 
when present, usually anterior to the middle of the body or near the 
middle, rarely near posterior extremity. Oviparous, ovoviviparous, 
or viviparous. Development in many cases, perhaps in all, requires 
an intermediate host. 

Superfamily Filarioidea, Weinland, 1858. 
''Body long and filiform. Alouth without lips. Male with two 
spicules, usually quite dissimilar. Vulva near the anterior extremity of 
the body. Adults subcutaneous, in blood, or on serous surfaces. 

Tj^pe-family Filariidse, Claus, 1885. 
"Vulva anterior, near mouth. Spicules quite dissimilar. Inter- 
mediate stages, so far as known, occur in blood-sucking arthropoda. 

Subfamily Filariina?, Stiles, 1907, 

Type-genus Filaria, Mueller, 1787, 

"Mouth with two lips; or without lips in forms where vulva is near 

posterior extremit}' of body, Male with posterior extremity of body 

commonly expanded and alate. Female with \'nlva usually in middle 

portion of body, exceptionally near posterior extremit}^ 

Family Spiruridae, (Erly, 1885. 
Type-genus Spirura, E. Blanchard, 1849. 
"Bod}' long and filiform. Anterior portion of bod}' ornamented with 
cuticular bosses. In the median lines, immediately behind the mouth, 
are two semilunar depressions sinmlating suckers. The vulva is sit- 
uated a short distance anterior of the anus. 

Subfamily Gongyloneminse, Hall, 1916. 
Type-genus Gongylonema, Mohn, 1857. 
"Females with two uteri and with \ailva in the middle portion of 
the body, not close to anterior or posterior extremities. Pharjmx with- 
out cuticular rays or spirals. 

Subfamily Spirurinae, Railliet, 1915, 

Type-genus Spirura. E. Blanchard, 1849. 

"INIouth with two lips leading into a pharynx which is strengthened 



228 PARASITES OF THE DOMESTIC ANIjVIALS 

by cuticular ridges in the form of rings or spirals. Spicules unequal, 
the longer several times the length of the shorter. Four pairs of preanal 
papillae. Eggs containmg embiyos when oviposited. 

Subfamily Arduenninse, Railhet and Henry, 1911. 
Type-genus Arduenna, Railhet and Henry, 1911. 



CHAPTER XIX / 

NEMATODA. FAIMILY I. ASCARID.E 

The Large Rouxdworms of the Intestine 

Xematoda (p. 217). The nematodes of this family have the body- 
relatively thick (Fig. 125). The mouth is commonly provided with 
three lips which may be prominent or inconspicuous and often bear 
papillse. When three lips are present one is dorsal, the other two sub- 
median, touching on the ventral median hne (Fig. 121). The males 
are somewhat smaller than the females and usually have the caudal 
extremity curved ventrally in the form of a hook. There may be one 
spicule or two. The females have two ovaries and they are oviparous. 
So far as known, development in all which are parasitic in warm-blooded 
animals is without intermediate host and infection is direct. 

All of the ascarids live as parasites in the intestines of their hosts, 
though they may be found in other organs and in the body cavities 
reached by their migrations. They hve free in the in- 
testinal contents, obtaining their sustenance by absorp- 
tion of the partly digested nutriment of their host 
through their smiple alimentary tube. 

Investigations as to Life History. — Investigations 
by Capt. F. H. Stewart (F. H. Stewart On the Life 
Histor}' of Ascaris lumbricoides, British Medical Jour- 
nal, 1916, Vol. 2, No. 2896) have brought results of 
great importance bearing upon the hfe histoiy of Ascaris Fig. 121.— Dor- 
lumhricoides and closely related forms. In these experi- fj ^xtremity^^of 
ments Stewart found that if rats or mice were fed ascarid, showing 
Ascaris eggs, the eggs hatched in the alimentaiy tract superior median 
and the embr3'os migrated to the hver, spleen, and lungs, lateral lips. 
During these migrations they passed through certain 
developmental changes, and man}- of them finally again reached the 
alimentary tract b}^ way of the lungs, trachea, and esophagus. Within 
the alimentary tract they did not continue their development and were 
soon expelled with the feces, so that rats and mice surviving the pneu- 
monia commonh' caused by the invasion of the lungs became free of 
the parasites as earh' as the sixteenth day after infection. 

From these findings Stewart concluded that in infection with Ascaris 
lumbricoides it is necessary in the life cycle for the eggs to be swallowed 
by rats or mice, and that the embryos hatching from the eggs undergo 




230 PARASITES OF THE DOMESTIC ANIMALS 

certain migrations and changes of development, after which they may 
be carried in the feces or saHva of the rats or mice to food or other 
materials which may be ingested by human beings or pigs, thus ulti- 
matelj^ reaching their final host. 

This conclusion is contrary to the opinion usually accepted that 
Ascaris infects man or the pig directly through the ingestion of the eggs 
of the parasite. In a preliminary note upon the life history of Ascaris 
lumhricoides and related forms Ransom and Foster, of the Zoological 
Division of the Bureau of Animal Industry, state that in a repetition 
of Stewart's experiments in feeding rats and mice with Ascaris eggs 
they obtained results agreeing very closely with those which he had 
recorded, also that further investigations have shown that guinea pigs 
as well as rats and mice may be similarly infected by feeding Ascaris 
eggs. Their negative or uncertain results from attempts to infect pigs 
with Ascaris by feeding the eggs agreed with the experience of Stewart 
and other investigators, nevertheless they did not feel justified in accept- 
ing these results as evidence against the hypothesis of a direct develop- 
ment without an intermediate host. They note that Epstein in care- 
fully controlled experiments with feeding eggs of Ascar'is lumbricoides 
used very young subjects and that the positive results which he obtained 
can scarcel}^ be explained upon any other assumption than that a direct 
development of the parasites occurred following feeding of the eggs. 
The failures of others to infect adult human beings and the unsuccessful 
attempts to infect pigs several months old in the same way are considered 
as suggesting the possibility that age is an important factor influencing 
the susceptibility of human beings and pigs to infection with Ascaris. 
In support of this, and in agreement with the migration of larvse which 
occurs in rats and mice, they cite an instance of a pig about six weeks 
old which, dying from unknown causes, revealed on examination an 
Ascaris larva in a fragment of lung and numerous immature ascarids 
in the intestine, the largest about two inches long. 

In order to test the possibility of infecting very young pigs these 
investigators used two young pigs from a sow which was found by fecal 
examination to be free from egg-producing ascarids. At the age of 
about two weeks one of these pigs was given a large number of Ascaris 
eggs containing motile-vermiform embryos. One week after feeding 
the eggs this pig died; the other pig continued in good health. ''Exam- 
ination of the dead pig," the authors state, "revealed a pneumonia, 
with numerous petechial hemorrhages in the lung tissue. Numerous 
ascarid larvse, varying in length from 0.7 to 1.2 mm. in length, were 
found in the lungs, trachea, and pharynx; none in the liver, spleen, 
esophagus, small intestine, or large intestine." As to conclusions the 
authors are further quoted as follows: 

"Stewart's very important discoveries concerning the behavior of 



ASCARID.E 231 

Ascaris larvae in rats and mice, the various contributions of other in- 
vestigators toward the sohition of the problem of the life history of 
Ascaris lumbricoides and related parasites, and our own experiences, 
appear to justify certain conclusions, some of which in anticipation of a 
more extended statement in a future paper, may be briefly given as 
follows : 

"The development of Ascaris lumbricoides and closely related forms 
is direct, and no intermediate host is required. 

"The eggs, when swallowed, hatch out in the alimentary tract; 
the embrj'os, however, do not at once settle down in the intestine, but 
migrate to various other organs, including the liver, spleen, and lungs. 

"Within a week, in the case of the pig Ascaris, the migrating larvse 
may be found in the lungs and have meanwhile undergone considerable 
development and growth. 

"From the lungs the larv£e migrate up the trachea and into the 
esophagus by wa}' of the pharynx, and this migration up the trachea 
ma}^ already become established in pigs, as well as in artificiall.y infected 
rats and mice, as early as a week after infection. 

"Upon reaching the alimentar}^ tract a second time after their passage 
through the lungs, the larvae, if in a suitable host, presumably settle 
down in the intestine and complete their development to maturity; 
if in an unsuitable host, such as rats and mice, they soon pass out of 
the bod}' in the feces. 

"Heavy invasions of the lungs by the larvae of Ascaris produce a 
serious pneumonia which is frequently fatal in rats and mice and ap- 
parenth' caused the death of a young pig one week after it had been 
fed with numerous Ascarid eggs. 

"It is not improl)able that ascarids are frequently responsible for 
lung troubles in children, pigs, and other young animals. The fact 
that the larvae invade the lungs as well as other organs bej'ond the 
alimentary tract and can cause a serious or even fatal pn^monia in- 
dicates that these parasites are endowed with greater capacity for harm 
than has heretofore been supposed. 

"Age is a highly important factor in determining susceptibility to 
infection with Ascaris, and susceptibiUty to infection greatly decreases 
as the host animal becomes older. This, of course, is in harmony with 
the well-known fact that it is particularly children and young pigs 
among which infestation with Ascaris is common, and that Ascaris is 
relativel}' of rare occurrence in adult human beings and in old hogs." 

ASCARIASIS 

Ascariasis occurs most frequently in young animals, those matured 
rarely harboring the worms in such numbers as to bring about symptoms 



232 PARASITES OF THE DOMESTIC ANIMALS 

by Avhich the condition can be recognized. Where there is a heavy in- 
festation they cause injury by their irritation to the intestinal mucosa. 
In such cases they may become massed and constitute an obstruction 
to the intestinal lumen sufficient to cause stasis of the contents and de- 
generative changes in the intestinal walls. 

The ascarids are active worms, and have a tendency to wander to 
unusual locations; one or two may find lodgment in accessory organs of 
the intestines b}-- way of their ducts and, by the consequent continuous 
irritation, bring about results of a serious nature. Verminous fistulae 
may be thus established, or there iliay be abscess formation with dis- 
charge of pus into the peritoneal cavity, followed by peritonitis. In 
dogs and cats especially, the worms when numerous often pass to the 
stomach in considerable numbers, setting up more or less gastric dis- 
turbance and consequent vomiting, tha expelled material generally 
containing from one to several worms. 

Certain foreign investigators, having demonstrated the presence of 
blood in ascarids, have concluded from this that these worms are blood 
suckers. Hall, in an article upon the parasites of the dog in Michigan 
(Journal of the American Veterinary Medical Association, June, 1917), 
states that an ascarid which he collected from the feces of a dog showed 
a pronounced red color in the intestine, evidently due to blood. As 
post-mortem examination of the dog the same day revealed a severe 
hemorrhagic enteritis, he concludes that this was evidently the explana- 
tion for the blood in the intestine of the ascarid. The conditions found 
in this case suggest the possibility of similar conditions in cases regarded 
as evidence that these worms are blood suckers, — a conclusion that cer- 
tainly has no support in the structure of the ascarid's mouth. 

There seems reason to doubt that ascarids feed upon epithelial cells, 
as stated by some authors. Their simple intestinal tube is restrictively 
modified to the primary function of absorption of nutriment already 
made in a certain state of solution by the digestive juices of the host, 
and it is unlikely that such digestive powers as are retained by the 
parasites would be adapted to a diet of epithelial cells. In view of the 
fact that free epithelial cells and their debris are contained in the alimen- 
tary contents of the host, it follows that such material would be in- 
gested along with the alhnentary matter by the worms and would be 
found in their intestinal contents. 

Aside from the mechanical injury caused by the ascarids, there are 
to be considered the effects of toxic products elaborated by their bodies. 
These may be practically nil or considerable according to the character 
and degree of the infestation. The loss of condition in heavy invasions 
can probably be attributed to the systemic effect of these poisons com- 
bined with that of the catarrhal enteritis. It seems reasonable to con- 
clude that the deprivation of nutriment, which has been appropriated 



ASCARIDiE 233 

by the horde of parasites in the ahmentary canal, is also a morbid factor. 
^Manifestations of the toxemia are often of a nervous character; there 
is hyperrefiex irritability, and con^^.llsions are a not infrequent accom- 
paniment. 

In general, it may be said of the ascarids that, while the}^ often in- 
habit the intestines without perceptible indications of their invasion 
other than their occasional expulsion with the feces, their presence con- 
stitutes a condition calling for treatment. They should be expelled by 
the administration of a vermifuge, in most cases followed bj' a purgative, 
and their bodies collected and burned. Not only should the treatment 
be carried out for considerations pertaining to the health of the host, 
but to prevent the spreading about of the worms with their eggs and 
embrvos to infest other animals. 



Ascarids of the Horse 

One species of ascarid inhabits the intestine of the horse, ass, and mule. 

Ascaris equi (A. megalocephala, A. equorum). Ascaridse (p. 229). — 
This is the largest species of the family. The bod}' is yellowish white, 
about the thickness of a lead pencil, and somewhat rigid. The head 
is distinct and bears three lips. The caudal extremit}- of the male is 
bordered laterall}' by two small membranous wings, and ventralh' on 
each side there are 80-100 papilla. The female is considerably longer 
and thicker than the male. The vulva is situated toward the anterior 
quarter of the bod}'. 

Length of female: 15-30 cm. (6-12 inches), or it may be somewhat 
longer. 

Eggs globular, 90-100 microns in diameter. 

The species is found only in Equida?, and lives in the small intestine, 
occasionally found in oth(>r organs by migration. 

Occurrence and Symptoms. — The large ascarid is verj' common in 
the small intestine of the horse. Unless numerous, they do not, as a 
rule, perceptibly affect the health of their host, often the only evidence 
of their presence being the voiding of one or more of the wornis with 
the feces. Young annuals do not bear the parasitism so well, and in 
moderate to hea^y infestations are likely to manifest serious disturb- 
ances of a local and systemic character. 

As a result of the irritation to the mucosa there is a chronic intestinal 
catarrh, and this may be accompanied by a diarrhea which is persistent, 
or alternating with a hard dr}- feces covered with slimy mucous material. 
Colic is a not infrequent s\nnptom, and there may be intervals of more 
or less tympany. The worms, when massed in large numbers, are 
capable of bringing about an obstruction with all that follows such a 
condition, possibly involving intussusception and even rupture. 



234 PARASITES OF THE DOMESTIC ANIMALS 

Young animals, as a result of aggravated ascariasis, lose condition 
and there is arrest in their development. Due largely to the accumula- 
tion of gas, they are likel}^ to become more or less pot-bellied, the activity 
of the skin is reduced, and the coat takes on a dry, harsh, and erect 
appearance. The alertness and inclination to play, natural to foals and 
young horses, is lost, and the animals maj' stand about looking more or 
less dejected. 

Nervous disturbances are occasionally exhibited by vertigo or, 
rarely, by epileptiform or tetanic symptoms. They may be due to reflex 
irritation or to toxic products from the bodies of living worms, to which 
is added toxins from the bodies of worms which are dead and decompos- 
ing. 

Etiology. — Infection occurs by the introduction of eggs and embryos 
into the alimentary canal with food and water. Development takes 
place after the eggs have left the body of the host and is favored by 
factors of warmth and moisture, such as is suppHed by moist earth and 
a temperature of about 37° C. (98° F.). AVhile segmentation will not 
proceed under low temperature conditions, the eggs will retain their 
fertility in unfavorable surroundings for a comparatively long period 
and will develop upon reaching a favorable environment. Embryos 
within the eggs appear to possess considerable resistance, since they 
have been observed to retain their vitality in dried horse manure for 
six months. It is probable that infection is by eggs, and that few em- 
br3^os are released until the intestinal contents of the equine host is 
reached. 

Control. — Considering the persistent vitality of the eggs and em- 
bryos, it is especially important as a prophylactic measure that as man}^ 
as possible of the expelled worms be collected and burned. If they are 
permitted to find their way to the manure pile or to be scattered about, 
some of the myriads of eggs contained in their bodies will meet with 
conditions favorable to their development and infect other horses. 
Precaution should be taken that the drinking water for horses does not 
receive contamination from collected manure, and that it be as pure and 
free from surface drainage as possible. 

Treatment. — Treatment should be preceded by the withholding of 
all bulk}^ food for twenty-four to fortj'-eight hours. During this time 
the animal should be at rest and may be given bran mashes, to which a 
moderate amount of grain may be added during the first twenty-four 
hours if the preparation is to be for the longer period. 

While the preliminary fasting of the host for a daj^ or two probably 
will not sufficiently "starve" the parasites to be of any value as an aid 
in their expulsion, it permits the removal of the bulky portion of the 
intestinal contents and prepares for a diffuse action of the anthelmintic 
which otherwise would not be possible. 



ASCARID.E 235 

Following the period of fasting, give two to four ounces of oil of tur- 
pentine and one dram of oleoresin of aspidiuni, in a pint of linseed oil. 
If necessary, follow twelve hours later with an additional pint or two of 
linseed oil. 

Tartar emetic in two to three dram doses, repeated once at an interval 
of twelve hours, is also an effectual cxpellant. This is best administered 
with linseed meal which may be stii-red into a small bran mash. 

These doses are for aged horses of average size, and are to be modified 
according to age and somewhat as to weight. 

The vermifuge is in most cases to be followed twelve to twenty-four 
hours later by a purge, preferabl}' oleaginous, but this should not be 
given if there is diarrhea, and may not be necessary if the animals are 
upon grass. 

Sulphate of iron and arsenic are remedies which have also been recom- 
mended. If arsenic is used, it should be given in the form of powdered 
arsenous acid in increasing doses for about two weeks. 

Family II. Oxyuridae. Xematoda (p. 217). — This family is consid- 
ered by many authors as belonging with the Ascaridse. Conspicuous 
characteristics of the group are the curved anterior portion of the body 
and the elongated and attenuated caudal extremity of the female. The 
males usually have but one spicule, and this may be reduced and im- 
perfectly developed. The vulva of the female is anterior. 

Oxyuris equi (O. curvula, O. mastigodes). Oxyuridse (p. 235). — 
The body is generalh' white, somewhat thickened, and curved. The 
mouth is provided with three lips. The male is much smaller than the 
female, and has an obtuse caudal extremity which bears several papillse, 
the largest of which sustains a caudal bursa. There is but one spicule 
and this is straight and slender. In the female the anterior portion of 
the body is thickened and curved, while the posterior portion is at- 
tenuated to a point. The \ailva is about 8-10 nun. (3/8 of an inch) from 
the mouth. The body may have its posterior attenuated portion of 
variable length (Fig. 122) ; in some individuals this is very much pro- 
longed and filamentous. This difference has led some authors to 
describe two species of Ox>in'is of the horse — O. curvula and 0. 7nasti- 
godes, the latter including those with the extended caudal extremity. 
Railliet has demonstrated that forms exist possessing all intermediate 
gradations between those with very short and those with very long tail 
extremities, and that there is not, therefore, a difference of true specific 
character. 

Length of female, 4-15 cm. (1 5/8-6 inches) ; male, al^out 1 cm. (3/8 of 
an inch). 

Eggs oval and operculated; 85-95 microns long, 40-45 microns wide. 

The species inhabits all of the large intestine of the horse, ass, and 
mule. 



236 PARASITES OF THE DOMESTIC ANIMALS 

Occurrence. — Oxyuris equi is a common inhabitant of the large intes- 
tine of the horse. The condition produced by these worms is usually 
referred to as oxyuriasis, and they are commonly known as seat-worms 
or pin-worms. Often they are observed projecting from the margin of 
the anus to which they adhere while depositing their eggs. By means 
of a sticky substance the eggs attach about the skin of the anus and 
perineum and develop embryos within two to three days. | Later the 
substance by which they are fixed to the skin dries and the eggs drop 




Fig. 122. — Oxyuris equi, showing varj'ing lengths of posterior 
attenuated portion. 

to the ground where, through scattered manure, they contaminate the 
pasturage, or, if the animal is in the stable, the feed ma}" be contam- 
inated in the same manner. 

The eggs are provided at one end with a sort of operculum which, on 
reaching the stomach, is digested away. The released embrj^os are then 
carried with the alimentar}" material to the large intestine where they 
reach maturity. 

Effect. — The offense of the oxyurids is mainly one of unsightliness. 
The}' produce itching about the anus which may become intense, causing 
the animal to rub the parts and thus bring about a denudation of the 



ASCARID^ 237 

tail and skin. The tail is frequently agitated, and annojdng habits of 
"switching" and "line-hugging" may have origin from this source. 

In aggravated cases there may be loss of flesh due to the constant 
irritation to which the animal is subjected. The anus becomes swollen, 
flacid, and, on defecation, the mucous membrane is noticed to be a deep 
red. 

The condition is readily diagnosed in observing the protruding or ex- 
pelled worms. The sticky yellowish-colored deposit about the anus and 
perineum, together with denudation of the skin and base of the tail 
by rubbing, indicates the presence of the worms. 

Treatment. — Treatment is mainly per rectum. Previous to the ad- 
ministration of vermifuge cnemata the bowel should be emptied by an 
injection of glycerin and water or of warm soap.y water. As an expellant, 
either of the following may be used: (1) Infusion of quassia, one to two 
quarts; (2) infusion of tobacco, one ounce to one quart of water; (3) 
vinegar in soapy water; (4) one quart of a one per cent, solution of 
lysol; (5) one to two ounces of oil of turpentine shaken up in a quart of 
Ume water and linseed oil; (6) mercurial ointment repeatedly applied 
to the borders of the anal orifice is also of service. The injections are 
best given through a rubber siphon. 

As developing worms from ingested eggs ma}' be in the intestines too 
far forward to be acted upon by the enemata, it is well to supplement 
this treatment with the administration of a vermifuge as recommended 
for the large ascarids of the small intestine. 

Treatment is to be repeated at intervals of four to six days until 
indications of the presence of the worms have disappeared. 

The adhering deposit about the rectum and perineum should be 
regularly removed and so disposed of that the contained eggs cannot 
reinfect. 

AsCARIDiE OF THE DoG AXD CaT 

One species of ascarid is connnon in the dog and cat, although some 
authors recognize two— Belascaris marginata of the dog, and B. mystax 
of the cat. Other than being a little smaller, the ascarid of the cat 
scarcely differs from that of the dog, and at the present time the ma- 
jority of helminthologists consider the difference as one of variety only. 

A much less conuuon species infesting dogs in this country is Tox- 
ascaris limhata. 

Belascaris marginata (Ascaris marginata, A. mystax, Belascaris 
mystax, B. cati). Ascaridee (p. 229).— The body is white, or reddish 
white. The head is usually curved and is provided on each side with a 
membranous wing, giving the appearance of an arrow-head (Fig. 123). 
On the curved tail of the male there are two small membranous 
lateral wings and twenty-six papillae on each side. The \'ulva of the 



238 



PARASITES OF THE DOMESTIC ANIMALS 



female is situated toward the anterior quarter of the body. The tail 
is obtuse. 

Length of female, 9-14 cm. (3 1/2-5 1/2 inches); male, 5-10 cm. (2-4 
inches). 

Eggs globular, 75-80 microns in diameter. 

Infests the small intestine. 




Fig. 123. — Belascaris marginata: A, 
male; C, female, natural size. 



head, enlarged; B, 



Toxascaris limbata (Toxascaris marginata). Ascaridse (p. 229). — 
The body is firm and whitish or pale red in color. The cephalic wings 
are long, narrow, and somewhat lanceolate. The spicules of the male 
are not quite equal. 

Length of female, 6.5-10 cm. (2 1/2-4 inches) ; male, 4-6 cm. (1 1/2- 
2 3/8 inches). 

The eggs are 75 to 85 microns in diameter. 

Parasitic in the intestines of the dog. 

Occurrence in the Dog. — Belascaris marginata is most often found 
in young dogs of three to four months. It is probable that about thirty 
per cent, of all puppies harbor the worms in more or less numbers in 



ASCARID^ 239 

their small intestine. The}' frequently enter the stomach and cause 
vomiting, the expelled material often containing several worms. Other- 
wise the S}iiiptoms are much hke those caused by the presence of tape- 
worms. There is emaciation, enlarged abdomen, and irregular appetite. 
There may be diarrhea or constipation, and, finall}', epileptiform or 
rabiform seizures. B^^ massing in the small intestine, they may induce 
invagination and fatal obstruction to the alimentary matter. 

Necropsies upon dogs which have died from ascariasis reveal the 
lesions of an intense hemorrhagic enteritis, with tumified mucosa, show- 
ing small ulcerative points and involvement of the submucous tunics. 

Treatment. — (1) Powdered areca nut, two grains to each pound of 
bod^'-weight, ma^' be given shaken up in a little milk. (2) Santonin is 
one of the most frequently used remedies. The dosage should be care- 
fully graded, giving one-eighth of a grain per pound of body-weight, the 
dose in no case to exceed three grains. It ma}' be administered sus- 
pended in milk or combined with one-fourth to two grains of calomel, 
made into a pill. (3) Fifteen minims to one dram of oleoresin of as- 
pidium, singly or combined with a grain of areca nut, per pound of body- 
weight, may be given in capsule. (4) Benzene, in fifteen drop to one 
dram doses in oil, has been recommended. 

The anthelmintic should be administered in the morning after a 
twelve hours' fast. If the bowels are not ah'eady freely active, it is 
well to follow the remedy a few hours later with a purgative of castor 
oil or syrup of buckthorn. Care should be taken in the administration 
of these drugs to to}' puppies. Santonin, especially, should not be given 
until they are at least eight weeks old; under that age, a simple laxative 
will often bring away quite a number of the worms. 

If vomiting occurs after giving the medicine, allow an interval of 
two or three days before repeating; then precede by a stomach sedative 
of bismuth or a small dose of cocaine. 

Occurrence in the Cat. — Ascariasis of the cat does not sufficiently 
differ from that of the dog to merit a special description. As in the dog, 
the worms are more likely to infest young animals, though cats seem 
to bear the invasion better. 

Remedies recommended for the dog will serve as well for the cat, 
though the peculiar intolerance of these animals should be taken into 
consideration in the selection and dosage. (1) Cusso, fifteen to thirty 
grains, is relativel}- safe, but is likeh' to cause vomiting. (2) Oleoresin 
of aspidium, minims fifteen to twenty, may be given in milk. 

ASCARID.E OF THE HoG AND ShEEP 

Ascaris lumbricoides (A. suis, A. suum, A. ovis). Fig. 125. 

Ascaridse (p. 229). — The head has three strong lips, the lateral sides of 



240 



PARASITES OF THE DOMESTIC ANIMALS 




Fig. 124 
Ascaris lumbricoides, 
with shell and albu- 
rn i n o u s envelope 
(copied from Braun's 
"Animal Parasites of 
Man"). 



which are generally 
denticulate. The body 
is white, firm, and elas- 
tic. The males have 
two spicules and numer- 
ous papillae anterior and 
posterior to the anus. 
The vulva of the female 
is situated toward the 
Egg of anterior third of the 
body. 

Length of female, 20- 
25 cm. (8-10 inches); 
male, 15-17 cm. (6-6 3/4 
inches) . 

Eggs, oval, 60-75 microns long by 40-58 
microns wide. The shell is mammillated. 

In its adult state this worm lives in the 
intestines of the hog and sheep, and also of 
man. 

The ascarid of the hog and sheep and 
that of man so closely resemble each other 
that a number of authors now consider 
them as one species; others distinguish a 
specific difference, claiming that the ascarid 
of the pig differs from the human ascarid 
in being thinner, having the longitudinal 
strise closer, spicules less sharp, and ova 
smaller. It would seem, however, that such 
slight differences should be regarded as of 
no more than varietal importance. 

Heavy invasions of these worms in the 
intestines of hogs bring about the con- 
ditions such as have alread,y been described 
in aggravated intestinal helminthiasis. In 
young pigs especially, there is general un- 
thrift, and emaciation may become quite 
advanced. There is usually a cough, and 
this is likely to be accompanied by occa- 
sional vomiting. The pig shows a pecu- 
liar restlessness, wandering about without 
apparent motive and emitting cries indica- 
tive of colicky pains. The lumen of the 
intestines may be obstructed by the 




Fig. 125. — - Aseari 
coides, male at right, 
left, natural size. 



i luml^ri- 
female at 



ASCARID.E 241 

worms in mass with the usual sequence of localized inflammatory 
changes. 

Invasion of the Ijile duct of pigs with these ascaiids is of frequent 
occurrence and may often bring about a fatal result. Autopsies at the 
Pennsylvania State Laboratories upon pigs dead from this parasitism 
have in some cases revealed the common bile duct literally packed and 
occluded with the worms. 

Treatment. — Treatment is mainly proph.vlactic. Thorough clean- 
ing up, Ixuning of litter, and a liberal application of disinfectants is 
essential, and the source of water supply and drainage should be looked 
to. Infested pigs should be isolated and precautions taken against 
reinfection. 

Medicine is best administered in milk, or other semi-fluid media, fed 
to the pigs as a whole, the dosing of individual pigs being a somewhat 
discouraging task. It is better to separate the pigs for this purpose into 
groups of not more than ten of nearly equal size, otherwise the largest 
and most aggressive will get more than their portion. 

As a vermifuge, pulverized areca nut may be usetl, the dose being 
approximately one grain to each pound of body-weight. This should 
l^e followed by a pui'gative, preferably saline, the dose graded according 
to size of pigs, and administered as al)ove. Benzene, in one to three 
dram doses mixed with the food, has been recommended as effective. 

When individual treatment of young pigs is resorted to, one to five 
grains of calomel, given in milk and followed by castor oil, will in many 
cases be sufficient to dislodge the worms. For older pigs it is better to 
follow the calomel with a saline evacuant. 

Ascariasis of Sheep. — Ascarids are rarely found in sheep. In the 
Bureau of Animal Industiy Collection there are specimens of ascarids 
obtained from sheep at Blairsville, Pa., Brookings, South Dakota, and 
Bethesda. Aid. (Bulletin 127. 1911.) 

ASCARID.E OF THE Ox 

Ascaris vitulorum. Ascaridse (p. 229). — The head is small and has 
three lips which are somewhat enlarged at the base. The body is white 
or may be reddish white. The caudal extiemity of the male has two 
rows of papillae, 10-15 in each ; these are lateral and pre-anal. The vulva 
of the female is situated toward the anterior sixth of the body. 

Length of female, 22-30 cm. (8 1 '2-1 1 3/4 inches) ; male, 15-20 cm. (6- 
7 3/4 inches). 

Eggs, 75-80 microns in diameter. 

Lives in the intestine of calves; rare in adult cattle. 

This worm is most frequently met with in parts of Southern Europe, 
where it is found hi rather large mmibers in the small intestine of calves 
slaughtered for veal. 



242 



PARASITES OF THE DOMESTIC ANIMALS 



Heterakiasis of Chickens 

Family III. Heterakidae. Nematoda (p. 217).— This family, like 
the Oxyuridae, is placed by some authors with the Ascaridse. The 
t3Te-genus is Heterakis, of which two species infesting chickens are to 
be described. 

1. Heterakis perspicillum (H. inflexa). Fig. 126. Heterakida 
(p. 242).— The mouth has three lips of unequal size, the dorsal lip the 
largest. The body is yellowish white. The caudal extremity of the 




Fig. 126. — Heterakis perspicillum: a, female; b, male; 
c, Heterakis vesicularis. All natural size. 

male terminates obliquely, and is provided on each side with a mem- 
branous wing and ten papillae. The two spicules are nearly equal. 
On the ventral surface anterior to the anus there is a rounded sucker. 
The caudal extremity of the female is straight, conical, and terminates 
in a point. The vulva is located in the anterior part of the body. 

Length of female, 6-12 cm. (2 1/2-4 3/8 inches) ; male, 3-8 cm. (1 1/4- 
31/8 inches). 

Eggs, elliptical, 75-80 microns in length by 45-50 microns in width. 

The species is common in the small intestine of the chicken, turkey, 
and guinea fowl. 

2. Heterakis vesicularis (H. papillosa). Fig. 126. Heterakidae 
(p. 242). — The mouth has three small lips of equal size. The body is 



ASCARID^ 243 

white and attenuated at its two extremities. The caudal extremity of 
the male is straight, with lateral wings, and twelve papillae. The spicules 
are unequal. The caudal extremity of the female is very slender. The 
vulva is posterior to the middle of the body. 

Length of female, 10-15 mm. (3/8-5/8 of an inch); male, 7-13 nmi. 
(5/16-1/2 inch). 

Eggs, elliptical, 63-71 microns in length by 38-48 microns in width. 

This species — nmch smaller than the preceding — is also common, 
and lives in the cecum of the chicken, turkey, guinea fowl, pheasant, 
pea-fowl, duck, and goose. 

Symptoms. — Heterakiasis of chickens is usually caused by Heter- 
akis perspicillum. In general, the presence of the worms is indicated 
by dullness and an indisposition to move about. Though the appetite 
may be preserved, there is more or less emaciation, the feathers become 
erect and lusterless, and the wings droop. If the condition is aggravated 
the symptoms progress, diarrhea sets in, the appetite dwindles, the 
comb becomes pale, and the creature, with eyes half closed, remains 
huddled up and unmovable until death comes to its relief. 

In such cases necropsy will reveal the lesions of a subacute enteritis, 
and frequently the presence of numerous tapeworms as well as round- 
worms. 

Intestinal helminthiasis in fowls is often an accompaniment to diseases 
presenting somewhat similar spnptoms, therefore care should be taken 
that a coincidence does not mislead, and that such causes of high mortal- 
ity as fowl-cholera be not overlooked. 

Treatment. — Sick birds should be isolated in clean bright quarters 
and their droppings fvequentl}' removed and destroyed. As medicinal 
treatment, probably areca nut is most effectual. This may be given to 
full-grown birds in doses of eighteen to twenty-four grains, administered 
in bolus made up with Hnseed meal or bread. Calomel, one to two grains, 
given in the same manner, has also been recommended. 

Essentially, thorough cleaning up and disinfection are necessary to 
the successful eradication of the parasites. 




CHAPTER XX 
NEMATODA. FAMILY IV. FILARIID^ 

The Thread-like Worms 

Nematoda (p. 217). — The nematodes of this family have the body 
long and filiform (Figs. 127 and 129). The shape of the mouth varies; 
it may be provided with lips or it may be surrounded with papillae. 
The esophagus is slender, without posterior bulb. The males may have 
one spicule or two unequal spicules, and the tail is generally spirally 
rolled. The females have two ovaries; vulva usually anterior to the 
middle of the body. The embryonal development is usualty within the 
body of the female. 

Parasitism. — The filarise live as parasites chiefly in serous cavities 
of the body, blood and lymph channels, and in the submucous and sub- 
cutaneous connective tissues. They may be found in most any part of 
the body, but do not commonly inhabit the lumen of the alimentary 
canal. 

The parasitism of the filariae produces a condition in their hosts known 
as filariasis. 

FiLARIID.E OF THE HORSE 

1. Setaria labiato-papillosa (Filaria equina). Fig. 127. Filariidse 
(p. 244). — ^The Iwdy is long, white, filiform, and attenuated at both 
ends. The integument has fine transverse striations. The mouth is 
small, circular, and provided with a chitinoiis ring, the border of which 
is divided by four salient papilla?. Outside of this on each side are two 
small papillae in the form of small spines. The tail of the male is rolled 
up spirally and presents on each side four preanal and four or five 
postanal papilla?. There are two spicules. The tail of the female is 
slightly spiral and is terminated by a papilla. The vulva is situated 
near the anterior extremity. 

Length of female, 9-12 cm. (3 1/2-4 3/4 inches); male, 6-8 cm. 
(2 3/8-3 1/8 inches). 

Newly hatched embryos are about 280 microns long by 7 microns in 
breadth. The embryonic development is within the body of the female. 

Occurrence. — This species is most often met with in the peritoneal 
cavity — more rarely in the pleural cavity of the horse, ass, and mule. 
The worms are especially fitted for migrations by their slender and 
attenuated bodies, and, from their location in serous cavities, may pass 



FILARIID.E 



^245 



to the subperitoneal and subpleural connective tissues or to the mus- 
cular septa, scrotum, or other parts of the body. The small filarise 
occasionally found in the anterior chamber of the eye are considered 
l)y most authors to belong to this species. 

Efifect. — Unless present in exceptionally large numbers, these worms 
do not produce serious disturbance. Their presence in the eye may 
cause inflammation with bulging and opacity of the 
cornea for the relief of which operative measures must 
be resorted to. 

Nothing definite is known as to the evolution of 
this nematode; the fact that the embryos have been 
olDserved in the blood of the horse, points to the 
probability that they pass to the body of a blood- 
sucking insect. 

2. Habronema megastoma (Spiroptera megas- 
toma). Filariidae (p. 244). — This is a small nematode 
with whitish colored body attenuated at the extremi- 
ties. The cephalic portion is separated from the 
remainder of the body by a constriction, and is pro- 
vided with four chitinous lips. The mouth is con- 
tinued by an infundibuliform pharynx. The caudal 
extremity of the male is rolled and bears two lateral 
wings, each sustained by four preanal and one pos- 
tanal papillae. There are two spicules. The tail of 
the female is straight and obtuse; vulva situated to- 
ward anterior third of the body. 

Length of female, 10-13 mm. (3/8 of an inch); 
male, 7-10 mm. (1/4- 3/8 of an inch). 

Eggs, elongate, 33 microns long by 8 microns in 
breadth. Development and hatching are within the 
body of the female (ovoviviparous). The liberated 
embr3'os measure 600-700 microns in length. 

The life history is not known. 

This species infests the submucosa of the stomach 
of the horse. They are usually in the right sac, and 
their presence may be recognized l)y oval or rounded 
prominences varying in size from that of a hazel nut 
to that of a walnut. The mucous membrane covering the tumors is 
unaltered with the exception of a number of perforations at the summits 
which communicate with the contained cavities. Within the.se cavities 
are lodged the worms which, on pressure upon the tumor, are extruded 
together with a purulent matter. 

It is probable that the worms reach their subnmcous lodgment as 
embrA^os b}' way of the gastric ciypts, the irritation of their presence 




Fig. 127. — .Setaria 
labiato-papillosa.male 
at loft, female at right. 



246 PARASITES OF THE DOMESTIC ANIMALS 

setting up proliferative changes with the formation of prominences. 
Outwardly the tumors are limited by the muscular layers of the stom- 
ach, the connective tissue involved being that of the submucosa. In 
old tumors the walls become of a dense fibrous character, taking some- 
what the consistency of cartilage. In these no worms may be found, or 
there may be a few of their disintegrated bodies contained in a small 
amount of purulent material. 

Essentially the presence of such parasites can only be revealed post- 
mortem. The tumors are not as a rule numerous, and do not seem to 
cause any serious disturbance. 

The manner of infestation by the worms is not known, nor is it known 
whether they multiply within the tumors. 

3. Habronema microstoma (Spiroptera microstoma). Filariidse 
(p. 244). — This species is larger than the preceding and may also be dis- 
tinguished from it by the absence of the constriction behind the cephalic 
extremity. The mouth presents a notch on each side, and there are two 
lateral lips. The tail of the male is rolled spirally, has two lateral wings, 
and a varying number of papillse. There are two spicules. The vulva 
of the female is situated near the anterior third of the body. 

Length of female, 12-27 mm. (1/2-1 inch); male, 10-20 mm. (3/8-3/4 
of an inch). 

The eggs are elongate and truncated at their extremities. They are 
45-49 microns long by 16 microns wide. Development and hatching 
are within the body of the female (o vo viviparous) . The hberated em- 
bryos measure 90-98 microns in length. 

The life history is not known. 

Occurrence. — Post-morten inspection of the interior of the horse's 
stomach will occasionally reveal the presence of these worms in such 
quantity as to cause an undulating movement of the contents of the 
organ, due to their active motion. While most of the worms are free, 
many may be found with their heads inserted in the gastric crypts of 
the right sac. More or less inflammatory disturbance of the mucosa 
may thus be set up, in some cases involving ulceration. 

As in the case of the preceding species, infestation with these worms 
can only be revealed when they are brought to light after the death of 
the host. Where a chronic gastric disturbance is suspected to be due 
to parasites of the stomach, one or two ounces of oil of turpentine may 
be given in two or three pints of linseed oil. 

FiLARiiD^ OF Sheep and Cattle 

1. Gongylonema scutata (Spiroptera scutata). Fig. 128. Filariidse 
(p. 244). — The body is long and filiform, white or yellowish white, 
striated transversely^, and slightly attenuated toward the extremities. 



FILARIID.E 



247 



The mouth has two lateral and four smaller submedian papilla. On 
the anterior 1 to 3 mm. of the body are rounded or oval cuticular tuber- 
cles arranged more or less regularly in rows. The tail of the male is 
rolled up and has two asynunetrical wings and two spicules. The \ailva 
of the female is situated in front of the anus. 

Length of female, 8-14 cm. (3 1/8-5 1/2 inches); male, 3-5 cm. (1 1/4 
2 inches). 

The eggs are oval. Embrj-onal development is within the body of 
the female. 

Occurrence.— This is a common species found in a large percentage 



.5 <^l 









Fig. 128. — Gongyloncma scutata: a, anterior portion of body, 
dorsal view; b, posterior extremity of female; c, posterior ex- 
tremity of male, ventral view; d, same viewed obliquelj^ from 
left side, — all enlarged (after Ransom, from Neumann, Bull. 
No. 127, Bureau An. Ind., U. S. Dept. Agr.). 



of sheep and cattle slaughtered in the abattoirs of this country and 
Europe. It has also been observed in the horse and in the mouth and 
pharynx of pigs. It inhabits the mucosa of the esophagus, usually in the 
thoracic portion where it is lodged just l^encath the epithelium. Its body 
runs parallel to the long axis of the organ and is disposed in a spiral man- 
ner, givmg somewhat the appearance of the wool-fiber of a merino sheep. 
There is no apparent effect upon the health of animals harboring this 
worm. Its only economic importance seems to be in rendering the 
esophagus undesirable for use in meat food products. 



248 PARASITES OF THE DOMESTIC ANIMALS 

Experiments by Ransom and Hall have shown that dung beetles and 
croton bugs fed upon the eggs of Gongylonema scutata become infested 
with an encysted larval stage of the parasite. Evidence is thus furnished 
that the mammalian hosts of the worm become infested as a result of 
swallowing insects bearing the encysted larvse. 

2. Filaria labiato-papillosa (F. cervina). Filariida^ (p. 244). — This 
species resembles Setaria labiato-papillosa of the horse, but differs from 
it in the absence of transverse striations of the integument and in the 
caudal papilla of the female, which form a terminal cluster of small 
blunt points, anterior to which are two thick conical papillae. 

Length of female, 6-12 cm. (2 3/8-4 3/4 inches); male, 4-6 cm. 
(1 1/2-2 3/8 inches). 

Development and hatching is within the body of the female (ovovi- 
viparous). The freed embryos are 140-230 microns in length. 

This nematode of the ox and deer is found almost exclusively in the 
peritoneal cavity. It does not appear to have any effect upon the health 
of its hosts. A worm occasionally found in the eye of the ox is con- 
sidered as belonging with this species. 

FlLARIID^ OF THE DoG 

1. Dirofilaria immitis (Filaria immitis). Fig. 129. Filariidae 
(p. 244). — The body is white, long, decidedly thread-like, with ends 
having an obtuse appearance. The mouth is small and surrounded by 
six indistinct papilla?. The posterior extremity of the male is slender, 
rolled spirally, and bears two small lateral wings. There are two 
spicules. The posterior extremity of the female is obtuse. 

The female is 25 to 30 cm. in length and about 1 mm. in diameter 
(9 3/4 inches by 1/32 of an inch). The length of the male is 12-18 cm. 
(4 3/4-7 inches). 

The embryos are developed and hatched in the body of the female 
(ovoviviparous). As they enter the circulation they measure 285- 
295 microns in length and have a diameter of about 5 microns. The 
anterior extremity is obtuse, the posterior extremity attenuated and 
slender. 

Occurrence. — Hematic filariasis of dogs, produced by this species, 
has been most frequently met with in China and Japan, about fifty 
per cent, of all dogs in the latter country, it is estimated, being affected. 
It occurs also in other countries, including North America. 

The usual seat of invasion is the blood-vascular system, particularly 
the right ventricle of the heart, the pulmonar}^ arteries being more 
rarely involved. Not infrequently mature filarrae are found in the sub- 
cutaneous connective tissue. In the heart and large arteries the worms 
may be found in a tangled mass containing hundreds so interlaced as to 
make it difficult to extricate single individuals. 



FILARIID.E 



249 




Pathogenesis. — The disturbances caused l)y the presence of the 
mature filarial are principally mechanical. Dependinjj: upon their 
number, they more or less interfere with the circulation, in some cases 
forming- a thrombus which may give rise to emboli in the branches of 
the pulmonaiy artery. In such cases necrotic 
areas in the lungs with abscess formation may 
result. 

The larvae, probably- by their toxic protlucts. 
bring about anaemia with a leucocytosis which, 
depending upon the number of the parasites 
present, may be more or less pronounced. As 
a result of the invasion of the heart, local mani- 
festations of endocarditis are to be looked foi-. 
The heart's action is variouslv disturbed, lead- 
ing to dropsical conditions accompanied l)y 
cough and dyspnoea. Nephritis and convul- 
sions may develop as a later complication. If 
the condition terminates in death, it is usually- 
from paralysis of the heart or a general weakness 
followed by complete paralysis. 

Diagnosis. — The parasites ma}- be present 
without causing observable manifestations, 
while, on the other hand, no line of clinical 
symptoms can with certainty be attril)uted to 
such invasion. A more precise diagnosis can 
usually be made by microscopic examination of 
the blood for demonstration of the jiresence of 
the larvae. Under low magnification, a drop of 
infected blood placed between a slide and a 
coverslip will reveal fine worm-like larvae in 
snake-like movements between the corpuscles. 
It is claimed by most investigators that they 
appear in greatest numbers in the peripheral 
circulation during the night, and, therefore, that 
amination is best drawn during these hours. 

Infection. — The manner of natural infection with this parasite has 
not yet been satisfactorily determined. Manson concluded from his 
investigations that the larvae of Filaria bancrofti (F. sanguinis hominis) — 
a blood parasite of man resembling the species under consideration — 
pass into the digestive tract of a mosquito (Culex) when it sucks the 
blood of an affected person. Later the mosquito, after depositing its eggs 
upon the water, dies, the body disintegrates, and the lai-val filariae are lib- 
erated, man becoming infected by drinking the water thus contaminated. 
It has been held that Dirofilaria immitis has a similar development. 



Fig. 129. — Dirofilaria im- 
mitis; male at loft, female at 
right, — natural size (after 
Railli.'t). 

blood for such ex- 



250 PARASITES OF THE DOMESTIC ANIMALS 

According to Noe, some of the larvae are taken with the infected blood 
into the bodies of blood-sucking insects. From the intestine they 
migrate to the Malpighian tubes where they undergo a certain degree of 
development. In about twelve days from the time they entered the 
body of the insect they pass through the walls of the Malpighian tubes 
and enter the mouth parts. If the piercing organ of the insect is broken 
during the act of sucking blood, the animal becomes infected, and the 
larvse are carried with the blood or l>anph to the heart where they attain 
sexual maturity. 

Grassi demonstrated by his investigations that nearly all of the larvse 
of the filaria of man die in the intestines of mosquitoes, and that the dog 
filaria cannot live in other parasitic insects harbored by dogs. He con- 
cluded, therefore, that the larvse from affected animals reach the water 
directly. 

The prevalence of the disease in low marshy locahties points to the 
transmission of hematic filariasis through contaminated water. The 
larvse from affected animals may reach the water with the excrement, the 
urine, or, occasionally, with blood from wounds. In such case infection 
may be direct or after the larvse have undergone a further development 
in an intermediate small crustacean, as cyclops, the parasites gaining 
entrance to the mammalian host by way of the alimentary canal and 
from here reaching the blood stream to be carried b}^ the venous blood 
to the right heart. 

Treatment. — -Therapeutic measures in this form of filariasis, espe- 
cially where there is pronounced disturbance of nutrition and circula- 
tion, is unsatisfactory. Nutritious food and the avoidance of exertion, 
conjoined with the administration of heart stimulants and prevention, 
so far as possible, of reinfection, may bring results if the parasites are 
not too numerous or the disturbances occasioned by them are not too 
far advanced. 

2. Spiroptera sanguinolenta (Filaria sanguinolenta) . Filariidae 
(p. 244). — ^The most prominent characteristic of this worm is its blood- 
red color. The tail of the male is obtuse, spiral, and has two lateral 
wings. There are two spicules. The tail of the female is obtuse and 
slightly curved. The vulva is situated 2 to 3 mm. behind the mouth. 

Length of female, 6-8 cm. (2 3/8-3 1/8 inches); male, 3-5 cm. (1 1/4- 
2 inches). 

The eggs are thick-shelled, elliptical, and about 30 microns long by 
12 microns in width. 

Occurrence and Pathogenesis. — This nematode of the dog is usually 
found lodged in tumors of the esophagus and stomach, though it is 
occasionally met with in large blood vessels, the lungs, and in lymph 
nodes. The tumors varj^ in size from that of a hazel nut to that of a 
pigeon's egg, and usually but few are present. They lie beneath the 



FILARIID.E 251 

mucosa, which is unaltered with the exception of an opening at the 
tumor's sunnnit. Outwardly, they are limited by the muscular coat. 

Upon incision of the hardened tissue of the tumor it is found to contain 
cavities which, on pressure, yield a purulent fluid with which are ex- 
truded the parasites. A varying number of worms may be found coiled 
up in these chambers, generally from two or three up to twenty. 

Symptoms and Course. — The most characteristic symptom of the 
presence of this worm is persistent vomiting. A fatal termination may 
be brought about from inanition resulting from the repeated vomiting, 
or the gastric tumors may rupture upon the peritoneum and cause a 
fatal peritonitis. 

Development. — Railliet has demonstrated that the eggs retain their 
shells in their passage through the intestines of the dog and reach the 
outside with the excrement. Researches of Grassi have shown that the 
embryos then pass into the body of a cockroach, probably' by its feeding 
upon the egg-containing excrement of infected dogs. In the bodj^-cavity 
of this insect he found large cysts containing larval nematodes agreeing 
in color with this species. The cysts were fed to dogs which, after two 
weeks, showed on necropsy the young parasites alread}^ embedded in 
the mucosa of the esophagus. Natural infection of dogs probably 
occurs by their eating the roaches containing these cj^sts. 

Treatment. — In the absence of precise symptoms indicating the 
presence of these worms, the diagnosis in practicalh' all cases being made 
post-mortem, there is little to be said as to the treatment of the affec- 
tion. Bismuth or small doses of cocaine may be given as palliative 
treatment for the relief of the recurrent vomiting, 

FlLARIID^ OF THE HoG 

1. Arduenna strongylina (Spiroptera strongylina). Filariidae (p. 
244). — The body is subcylindrical and often curved ina semicircle. The 
anterior portion is attenuated, the posterior somewhat broader. The 
cuticle is densely striated transversely. The mouth has two lateral 
lips, each with three lobes leading into a small buccal capsule which is 
followed by a cylindrical pharynx marked with cuticular ridges forming a 
series of spirals. The caudal end of the male is curved, has two unequal 
wings, and five pairs of stalked papillae asymmetrically arranged. The 
spicules are long and very unequal. The vulva of the female is slightly 
anterior to the middle of the body. 

Length of female, 16-22 mm. (5/8-7/8 of an inch); male, 10-15 mm. 
(3/8-5/8 of an inch). 

The eggs are oval, 34-39 microns long by 20 microns wide. They 
have thick shells and contain well-developed embryos at the time of 
oviposition. 



252 PARASITES OF THE DOMESTIC ANIMALS 

The species is parasitic in the stomach and small intestine of the hog. 

2. Physocephalus sexalatus (Spiroptera sexalata). Filariidie (p. 
244). — The body is subcylindrical and slightly'- tapering anteriorly. The 
head is made distinct by a cuticular inflation extending to the posterior 
end of the pharynx. The mouth has two three-lobed lips, each lobe 
having a rounded papilla and leading into a small buccal capsule. The 
cylindrical pharynx has a spiral band which usually breaks up into 
separate rings in the middle of its course and again becomes spiral toward 
the posterior end. The body of the male is nearly uniform in diameter. 
The caudal extremity is twisted spirally and has narrow membranous 
wings which are symmetrical. There are eight pairs of papillae, of which 
four pairs are preanal and stalked, the postanal papillae small, with 
short stalks, and close to the tail. The spicules are very unequal. The 
body of the female is thickest near the anus, terminating abruptly in a 
blunt point furnished with a small conical tip. The vulva is posterior to 
the middle of the body. 

Length of female, 13-19 mm. (1/2-3/4 of an inch). In the region di- 
rectly anterior to the anus the width is 333-450 microns. The male is 
6-9 mm. (3/16-11/32 of an inch) in length. 

The eggs are oval, 34 by 15 microns, slightly flattened at the poles, 
and thick-shelled. They contain well-developed embryos at the time of 
oviposition. 

The species is parasitic in the stomach and small intestine of the hog. 

In neither of these two species is the life history known. The thickness 
of the egg-shell indicates that the embryos are not released until this is 
acted upon by the gastric juice of the host, and, therefore, that develop- 
ment occurs without an intermediate host. 

In a report upon his investigations of these worms published in 1912, 
Foster, of the Zoological Division of the Bureau of Animal Industry, 
gives the following summary: 

"Two species of roundworms belonging to the family Filariidae, of 
particular interest to helminthologists and veterinarians on account of 
their wide distribution and frequency of occurrence in American swine 
and the possibility thai they may cause serious injury to their host, are 
given special consideration in this paper. 

"One of these species, identified as Spiroptera strongylina, has re- 
cently been placed in a new genus, Arduenna, of which it is the type, 
and several errors regarding the anatomy of this parasite have been 
corrected. Another species, Arduenna dentata, has been found in China 
associated with Arduenna strongylina, and, although not yet reported in 
American swine, is mentioned in this connection, as further investiga- 
tion may reveal its presence in this country. 

"Arduenna strongylina is much more common in American swine than 
it is said to be in European swine, and has been found abundantly in 



FILARIID.E 253 

the slaughterhouses of St. Louis, Chicago, South Omaha, and Kansas 
City, and has also been collected at Benning, D. C, and Bethesda, Md. 

"Specimens of hogs' stomachs received from Chicago showed the 
worms deeply fastened in the submucosa or embedded in necrotic tissue 
near which were deep ulcers. The condition suggested infection with 
Bacillus necrophorus, the inoculation with which might easily result from 
the burrowing of the worms; however, owing to the sterile condition of 
the specimens received, this could not be satisfactorily demonstrated. 
A similar diseased condition of the stomachs of hogs in Europe is attril)- 
uted Iw Von Ratz to infection with Arduenna strongylina. Under the 
circumstances the worm should be regarded with grave suspicion, and 
general prophylactic measures foi- the prevention of the spread of the 
infection are suggested. 

"Commonl}^ associated with Arduenna strongylina in this country is 
another worm, identified as Physocephalus sexalatus, first described by 
Molin from specimens from the peccary {Dicotyles labiatus) from Brazil; 
also found by him associated with Arduenna strongylina from the wild 
boar in Germany. It is also reported by A'on Listow (who apparentl>- 
mistook this species for Arduenna strongylina) and Plana, from Europe, 
and by Railliet and Henry from Madagascar and Indo-China, in the 
former case associated with a severe gastritis. Seurat (1912) has re- 
cently reported this species from the ass and dromedary in Algeria, but 
his statements would seem to I'equire confirmation. 

"According to the writers' experience, Physocephalus sexalatus is 
almost as widely distributed as Arduenna strongylina, since out of eight 
lots of specimens of the latter species, specimens of Physocephalus sexala- 
tus were found in all but one. In a mixed infection, however, it has 
never been found as abundantly as Arduenna strongylina. This worm 
has apparently the same habit of injuring the mucosa as has Arduenna 
strongylina, as both species were found in the same necrotic tissue in a 
hog's stomach. It must therefoi-e be considered only less dangerous 
because it is less abundant, and should be subject to the same treatment 
suggested for infestation with Arduenna strongylina.'" 

Control. — As that part of the parasite's life history external to the 
host is not known, no more than general preventive measures can be 
recommended. The author quoted above suggests the following: 

"1. Hogs suffering from loss of appetite oi- failing to fatten undei- 
proper food and hygiene should be examined for evidence of infection b>- 
killing one or two and looking in the stomach for worms; or, where 
practicable, the feces of the entire herd may be examined microscopically. 

"2. Those swine found infested with stomach worms should be 
isolated from noninfected or presumably noninfected swine in clean 
pens, and the dung removed daily and mixed with quicklime or dis- 
posed of by carting it to places to which hogs do not have access. 



254 PARASITES OF THE DOMESTIC ANIMALS 

"3. The noninfected swine should not be allowed to remain in the 
same pens formerly occupied by the infested animals, but should have 
clean quarters. The old pens should be thoroughly disinfected with lune 
after removing the clung and burning over the ground where feasible." 

Treatment. — Treatment in such infection is mainly prophylactic. 
As a medicinal remedy, probably benzine is one of the best. It may be 
given in two to four dram doses in milk, administered as recommended in 
the treatment for ascarids. Areca nut, one grain per pound of body- 
weight, may be given in the same manner. 

FiLARiiD^ OF Chickens 

Of the filariae harbored by poultry, four species may be mentioned 
here. As to the first three at least, there is little of record in this country. 

1. Dispharagus spiralis. Filariidse (p. 244). — The body is generally 
rolled spirally. There are three papillse around the mouth. The tail 
of the male is spiral and is provided with wings. There is but one 
spicule. The female is 9 mm. (3/8 of an inch) and the male is 7 nun. 
(5/16 of an inch) in length. 

This species lives in the wall of the esophagus and intestines of poultry. 

2. Dispharagus hamulosus. Filariid® (p. 244). — The body has 
eight denticulated longitudinal wings. The female is 16-25 mm. (5/8- 
1 inch) and the male is 14 mm. (9/16 of an inch) in length. 

This worm has been found in Brazil and in Italy. It is parasitic in 
the gizzard of fowls. 

3. Dispharagus nasutus. Filariida? (p. 244).— The body is slightly 
attenuated at its extremities. There are two long terminal papillse 
on each side of the mouth, from which two fiexuous wings have their 
beginning. These pass to a distance of 0.6 mm., then curve forward. 
The male is filiform, with caudal extremity spiral. There are two 
unequal spicules. The vulva of the female is in the anterior portion of 
the body. The female is 5-9 mm. (3/16-3/8 of an inch) and the male 
is 5 mm. in length. 

It inhabits the gizzard of fowls. 

4. Tetrameres fissispina (Tropisurus fissispinus). Filariidse (p. 244). 
— This species is characterized by a marked sexual dmiorphism. The 
male is white, slender, 3-6 mm. (1/8-1/4 of an inch) in length, and bears 
upon the median and lateral hues spines forming four longitudinal series. 
The body of the female is subglobular, 2 mm. in length by 1-2 mm. (in 
width; reddish in color; tail short and conical. 

The species is found in the proventriculus of the domestic duck where 
it inhabits submucous cysts and may set up a serious inflammation of 
these parts. It is said to be quite common in parts of New York State, 
and it is probable that it exists in other localities. 




chapter xxi 

xe:\iatoda. fa:mily v. stroxgylid.e. subfa:\iily i. 
:^ietastroxgylix.e 

AVORMS OF THE RESPIRATORY TrACT 

Xematoda (p. 217). — The most prominent character by which this 
family may be recognized is the caudal bursa of the male which is usually 
well developed. The body is elongate, cylindrical, and in some cases 
filiform. A buccal capsule may be present or absent and ma}' be armed 
with teeth in its interior. The esophagus is more or less enlarged poste- 
riorly. The males have a more or less well-developed caudal bursa, 
usually divided into lateral lobes, each supported by ra^'-like chitinous 
thickenings. There are two equal or unequal spicules. The \ailva of the 
female may be posterior or anterior to the middle of the body, usually 
posterior, in some cases near the anus. 

Parasitism. — While these worms in their adult form mostly infest 
the lumen of the alimentar}- and respiratory tracts, other organs may be 
primarily or secondarily- involved. The subserous larval phase of in- 
testinal invasion b}- the genus (Esophagostomum and the vascular 
larvae of Strongylus vulgaiis may be mentioned in this connection, while 
other organs are not uncommonly invaded by migration. The term 
strongylosis is a general one which has been applied to any helminthiasis 
produced by strongyles. It is more precisely used when qualified by 
terms indicating the seat of invasion, as gastric, intestinal, bronchial, 
vascular, or renal strongylosis. 

Being responsible for some of the most depletive and fatal forms of 
parasitism, the strongyl worms have especially demanded study and 
investigation; this has established important advances in knowledge 
as to their pathogenicity, though much remains to be revealed as to 
their life histories and consequently as to effectual means for their 
control. In general it may be said that low marshy pasturage and wet 
seasons favor infestation with strongyles, which would indicate that the 
ova and embr^-os of some forms at least are spread by water, and that 
contaminated water and herbage are the vehicles by which the parasites 
reach their hosts. 

As in other parasitic invasions, age and physical condition have a 
decided influence in predisposition to strongylosis. Young ruminating 
animals are especially susceptible to the broncho-pulmonary form, 
while in all animals which mav be affected both vouth and senilitv favor 



256 PARASITES OF THE DOMESTIC ANIMALS 

intestinal infestation. Again, the general rule applies that resistance is 
always reduced in animals in low physical condition, while, essentially, 
crowding and general unsanitary conditions favor the transmission and 
spread of the parasites. 

Of the Strongylidae three subfamilies may be distinguished, viz: 

Subfamily I. Metastrongylince. 

Subfamily II. Trichostrongylinae. 

Subfamily III. Strongylinae. 

Subfamily I. Metastrongylix^ 

Strongy-lidse (p. 255). — This subgroup comprises the strongyles 
parasitic in the respiratory system and some in the circulatory system. 
The buccal capsule is absent or very slightly developed. The bursa of 
the male is frequently atypical in structure and number of rays. There 
are two equal spicules. The eggs are in varying stages of development 
when deposited. 

The life history is as yet unknown. It is probable that infection is 
without intermediate host. Romanovitch and Slavine (1914) found 
that eggs of Didyocaulus filaria when placed in water formed embryos. 
Two moltings followed, the cuticle being retained and encapsulating the 
larvae, and these when fed to sheep produced infection with the adult 
worms. This would indicate direct development and infection by the 
worms of this group. 

Bronchial and Pulmonary Strongylosis of the Sheep and Goat 

Three species of Metastrongylinse invade the respiratory tract of the 
sheep and goat; a fourth, — Metastrongylus apri — described under 
broncho-pneumonia of the hog, is exceptionally found in the sheep. 

1. Dictyocaulus filaria (Strongylus filaria). Fig. 130. Meta- 
strongylina? (p. 256). — The body is white, filiform, slightly tapering at 
posterior extremity. The anterior extremity is obtuse, without wings; 
mouth circular and without papillae. The bursa of the male is notched 
in front; spicules short, thick, brown in color, and provided with mem- 
branous wings. The caudal extremity of the female is straight and 
conical; vulva somewhat posterior to the middle of the body. 

Length of female, 5-10 cm. (2-4 inches); male, 3-8 cm. (1 1/8-3 1/8 
inches). 

The eggs are oval, 112-135 microns in length by 52-67 microns in 
breadth. They contain developed embryos which are liberated in the 
bronchi as the eggs are deposited. 

The embryos are 540 microns long ]:)y 20 microns in diameter, tapering 
to a blunt point behind. 



:\IETASTRONGYLIX.E ^.57 

The worm is parasitic in the respiratory organs of the sheep, goat, 
camel, and deer. 

2. Synthetocaulus rufescens (Strongylus rufescens). Fig. 131. 
INIetastrongyHnse (p. 256).— The body is thin and hair-hke, brownish 
red in color. The mouth has three papilliform lips. The bursa of the 
male is notched in front and has two small lateral indentations. The 
spicules are striped transversely and rounded at their ends. The poste- 
rior extremity of the female terminates in a blunt point; vulva imme- 
diately in front of the anus at the base of a small pre-anal elevation. 



B 






Fig. 130. — Dictyocaulus filaria: a, female; b, male, 
natural size; c, anterior extremitj-; d, eggs, — enlarged. 

Length of female, 25-35 nun. (5/8-1 3/8 inches) ; male, 18-28 mm. 
(3/4-1 1/2 inches). 

The eggs are oval, 75-120 microns in length by 45-82 microns in 
breadth. Segmentation has advanced at the time they are deposited, 
after which the embryos develop rapidly and are liberated in the pul- 
monary alveoli. From the alveoli the}' pass to the bronchi and trachea 
from whence they are expelled to the outside where they have a strong 
vitalitj' and are capable of resisting desiccation for a long time. 

As found in the trachea and larger bronchi, the embryos measure 
300-400 microns in length by 16-18 microns in breadth. 

The worm is parasitic in the respiratory organs of the sheep, goat, and 
rabbit. 



258 PARASITES OF THE DOMESTIC ANIMALS 

3. Synthetocaulus capillaris (Strongylus capillaris). Metastrongy- 
linse (p. 256). — This worm like the preceding is thin and brownish in 
color. The mouth has six papillae and the caudal extremity is pointed. 
The caudal extremity of the male is curled spirally; bursa small and sup- 
ported by seven ribs; spicules dentate. The vulva of the female is just 
in front of the anus. 

Length of female, 20-22 mm. (7/8 of an inch); male, 14 mm. (9/16 of 
an inch). 

The eggs are brownish in color. The embryos develop after the eggs 
are deposited and are liberated in the pulmonary alveoli and bronchi. 
After depositing the eggs the adult worms invade the lung tissue where 
they die and become encapsulated. 

The worm is parasitic in the respiratory organs of the sheep and goat. 

Bronchial and pulmonarj- strongylosis of sheep and goats is due to 
the presence of these worms together with their eggs and larva) in the 
air passages and alveoli. The affection is usually a broncho-pneumonia, 
though the S3anptoms presented will be somewhat subordinate to the 
infecting species. If the infection is with Dictyocaulus filaria, or this 
dominates a pulmonary species coexisting in the same animal, the 
bronchial si-niptoms will be the more prominent. On the other hand, 
in an abundant infestation with Synthetocaulus rufescens the pulmonary 
symptoms are likely to predominate. 

Symptoms. — Bronchial strongylosis of sheep and goats is usually 
due to the presence of adults of the species Dictyocaulus filaria in the 
larger air passages, and in most all cases the pulmonarj^ form is asso- 
ciated with it. In general, the symptoms are those of a bronchial 
catarrh. There is a short dry cough which at first is at long intervals. 
Later this is more frequent and may become paroxysmal and accom- 
panied by distressing attacks of dyspnoea. The bronchial secretion 
expelled through the mouth and nostrils is frequenth^ lumpy and usually, 
though not always, contains the worms with their eggs and embryos, 
the latter found by examination of the material with the microscope. 
At first the liveliness and appetite of the animal are retained and there 
is no appreciable loss of flesh. If the number of the parasites remains 
small there will continue to be little or no manifestation of their presence. 
Relative to the degree of infestation, the symptoms may pass through 
the gradations above given to extreme difficulty in respiration, emacia- 
tion, pallor, and edema of the larynx, muzzle, and ej^elids, the brisket 
and other dependent parts of the body in some cases also becoming 
edematous. Finally, in extreme weakness, the animal is unable to get 
upon its feet and, in a condition of complete prostration, succumbs. 

Symptoms occasioned by the presence of strongyles in the pulmonary 
air spaces and alveoli are in themselves less prominent than those of 
verminous bronchitis. Attentive percussion over the thorax may reveal 



METASTROXGYLIN.E 259 

dullness in circumscribed areas, but as a rule it shows nothing abnormal. 
Usually symptoms are only observed upon the appearance of cachexia 
and weakness following the development of punalent areas in the lung 
tissue, this finally bringing about the death of the anmial. 

Course and Prognosis. — The duration of broncho-pulmonarj^ stron- 
g3'losis varies according to the number of parasites present and the 
toleration of the affected anmial. In the majority of unfavorable cases 
the disease will run a course of two, three, or four months. In the very 
young this period may be much shortened, the animal succumbing in a 
few days from the first observation of sj-mptoms. Strong adult animals, 
on the other hand, are likely, unless there is reinfection, to gradually 
recover during a course of six to eight months. In any case where the 
symptoms are well marked a fatal termination is to be looked for. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Bronchial axd Pulmonary Strongylosis op Cattle 

Dictyocaulus viviparous (Strongylus micrurus). Fig. 132. ^Nleta- 
strong3'hna3 (p. 256). — The body is long, slender, and attenuated at both 
extremities. The head is rounded and without wings; 
mouth circular and nude. The bursa of the male is 
small, without lobes, and is supported by five ribs. 
There are two short and strong spicules. The tail of 
the female terminates in a sharp point; vulva near the 
posterior sixth of the body. 

Length of female, 6-8 cm. (2 3/8-3 1/8 inches); 
male, 3.5-i cm. (1 3/8-1 5/8 inches). 

The eggs are oval, 85 microns in length by 35 mi- 
crons in breadth. Embryos are developed within the 
body of the female and are liberated at the time the 
eggs are deposited. 

The liberated embiyos are 256 microns long by 25 
microns in thickness. The}^ pass from the bronchi 
to the trachea from which they are expelled to the 
exterior. 

Symptoms. — In light infestations no symptoms 
may be observed save an occasional cough. When iQo_n- 

the parasites are more numerous the cough becomes tyocaulus ' Vi-v-ipar- 
more frequent and sonorous, and, in the further course, ous; male at right, 
paroxysmal, the animal extending the head, protmding urTri^se^* ^^^*' °^*' 
the tongue, and freely sahvating during the attacks. 
The paroxysms are accompanied by dj'spnoea and suffocation, with 
beating flanks, quickened pulse, and injected conjunctiva. In severe 




260 PARASITES OF THE DOMESTIC ANIMALS 

cases with violent attacks occurring several times a day, the gasping 
animal may fall prostrated and die from asphyxiation. 

The mucus expelled by the coughing is frequently streaked with 
blood and contains the worms which are often collected in masses. It 
is to these masses obstructing the large bronchi that the suffocation is 
due. 

Course and Prognosis. — What has been said as to influences gov- 
erning the duration and intensity of the malady in sheep will, in general, 
apply to cattle also. The prognosis, especially in calves, is usually 
unfavorable. Death is generally brought about in three to six months 
by asphj^xia or extreme cachexia and exhaustion. 

For Post-mortem Appearance, Development and Etiolog}^, Control, 
and Treatment, refer to pp. 262-265. 

Bronchial and Pulmonary Strongylosis of the Pig 

Two strongyles are met with in the respiratory tract of the hog. 

1. Metastrongylus apri (Strongylusapri; St. paradoxus). Fig. 133. 

Metastrongylinse (p. 256).— The body is white or brown. The mouth 
has six hps. The bursa of the male is bilobate, each lobe 
sustained by five ribs. The spicules are slender and very 
long, measuring about 4 mm. (3/16 of an inch) and each 
terminated in a barb. The tail of the female terminates 
b}^ a short hook-like process. The vulva is on a slight 
eminence immediately in front of the anus. 

Length of female, 2-5 cm. (3/4-2 inches); male, 1.2-2 
cm. (1/2-3/4 of an inch). 

The eggs are oval, 57-100 microns in length by 39-72 
microns in breadth. They contain developed embryos at 
the time they are deposited and these are liberated in 

M?tastron'^us *^^® bronchi. 

apri; male at The embryos at the time of their liberation measure 
right, female at 220-250 microns in length and 10-12 microiis in thickness. 
left, — natural rpj^^ worm is parasitic in the respiratory tract of do- 
mestic and wild hogs, occasionally of sheep. 

2. Metastrongylus brevivaginatus. Metastrongylina3 (p. 256). — 
This species has for a long time been confounded with the preceding 
under the name of Strongijlus paradoxus. It differs from it in the shape 
of the bursa and in the spicules which are short, each terminating in 
two barbs. 

The worm is parasitic in the respiratory tract of domestic hogs. 

Occurrence and Symptoms. — While the presence of strongyles in 
the bronchi of pigs has been known for a long time, it is not as frequently 
observed in these animals as in sheep and calves. Heav}'- infestations 



METASTRONGYLIX.E 261 

with Metastrongylus apri sonietinies occur with high mortaHt}^ among 
pigs. Such cases take a course similar to that in sheep and calves. In 
the milder cases there ma}- be disturbances of nutrition and occasional 
cough, though usually in light invasions nothing is observed to cause 
suspicion of the presence of the worms which are onlv revealed on 
examination of the respiratory passages after slaughtering. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Broxchial axd Pulmoxary Stroxgylosis of the Horse 

Dictyocaulus arnfieldi (Strongylus arnfieldi). — ^Metastrongj'linse 
(p. 256). — The body is white and filiform and the mouth is nude. The 
bursa of the male is short, with faint lobulation. The spicules are 
slightly arched, 200-240 microns in length, and have a net-like marking. 
The tail of the female is short, slightly curved, and terminates in a 
blunt point. The \T.ilva is situated somewhat posterior to the middle 
of the body and is not prominent. 

Length of female, 4.3-5.51 cm. (1 11/16-2 3/16 inches); male. 2.8- 
3.6 cm. (1 1/8-1 7/16 inches). 

The eggs are oval and measure 80-100 microns in length l)y 50-60 
microns in breadth. The}- contain developed embryos at the time they 
are deposited, and these are liberated in the respiratory passages of the 
host. 

The liberated embryos measure 400—490 microns in length and have 
a thickness of 14-18 microns. 

The worm is parasitic in the bronchi of the horse and ass. 

Bronchial strongylosis of equines seldom occurs. Clinically it is 
manifested by symptoms similar to those of verminous bronchitis in 
other animals. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Cardio-Pulmoxary Stroxgylosis of the Dog 

Haemostrongylus vasorum (Strongylus vasorum). ^letastron- 
gylinie (p. 256). — The body is filiform, whitish or reddish in color, and 
has longitudinal striations. The mouth is nude. The bursa of the male 
has two lobes, each sustained by four ribs. The vulva of the female 
is situated in front of the anus. 

Length of female, 18-21 nun. (3,4-13/16 of an inch); male, 14-18 nun. 
(9yl6-3/4of aninch). 

The eggs are oval and measure 70-80 microns in length by 40-50 
microns in breadth. Segmentation occurs after they are deposited. 



262 PARASITES OF THE DOMESTIC ANIMALS 

When freed from the eggs the embiyos measure 300-360 microns in 
length by 13 microns in thickness. 

The worm Hves in the right heart and ramifications of the piihnonary 
artery of the dog. 

Cardio-puhiionary strongylosis of the dog is due to the presence of 
these parasites, together with their eggs and embryos, in the right 
ventricle of the heart and small ramifications of the pulmonary 
artery. 

Symptoms. — Symptoms in this form of strongylosis of the dog are 
obscure, and generally the disease is not recognized until post-mortem 
examination of the animal. Respiratory disturbances occur in some 
cases, and there may be the development of ascites. The attacks of 
respiratory difficulty may disappear after a few days, or the}^ may lead 
to asphyxia and the death of the animal. 

For Post-mortem appearance, refer to page 263. 

Pulmonary Strongylosis of the Cat 

Synthetocaulus abstrusus (Strongylus pusillus). Metastrongylinse 
(p. 256). — The body is filiform and the mouth is without papillae. The 
bursa of the male is short and slightly festooned. The spicules are slen- 
der, long and recurved. The caudal extremity of the female terminates 
in a blunt point; vulva immediately in front of the anus. 

Length of female, about 10 mm. (3/8 of an inch); male about 5 mm. 
(3/16 of an inch). 

The eggs are oval or subglobular, 60-85 microns in length by 35-80 
microns in breadth. Segmentation occurs after they are deposited. . 

The liberated embryos are 370^50 microns in length by 16-18 
microns in diameter. 

The worm is parasitic in the lungs of the cat. 

Symptoms. — Verminous pneumonia of cats produced by the ova and 
embryos of this worm not infequently occurs without symptoms by 
which it may be recognized. On the other hand, the animals may have 
a frequent cough accompanied by vomiting. Where emaciation and 
diarrhea follow upon such symptoms, death will usually result after a 
course of two to three months. 

Post-Mortem Appearance in Bronchial and Pulmonary 
Strongylosis 

Animals which have died as a result of strongyles in the respirator}^ 
passages will, upon necropsy, show an abundant collection of mucoid 
and mucopurulent material in the bronchial tubes which is frequently 
streaked with blood and contains the adult worms, ova, and embryos. 



:\IETASTRONGYLIN.E 263 

The worms may be in masses sufficient to obstruct the medium-sized 
or larger bronchi which in places may present sac-like dilations con- 
taining bundles of worms together with more or less purulent mucus. 
The mucosa of the heavil}- infested bronchi is edematous and may show 
hemorrhagic streaks. In the vicinity of bronchial dilations especially 
there is proliferation of connective tissue, the air-containing tissue 
being compressed and obliterated and at the periphery sometimes 
showing localized pleuritic adhesions. 

In pneumonia due to the presence of strongyles three forms have 
been distinguished, viz: 1. A lobar pneumonia due to the presence of 
the adult worms in the ramifications of the bronchi. 2. A diffuse pneu- 
monia due to ova and embryos which invade the pulmonary tissue in 
large numbers. 3. A nodular or pseudo-tuberculous pneumonia due 
to the accumulation of eggs and embryos in circumscribed parts of the 
lungs. The last is the most common form and is characterized by the 
presence of small, hard, grajdsh yellow centers from the size of a millet 
seed to that of a pea which may be more or less confluent. Most of 
these nodules are found toward the periphery of the lungs, particularl}^ 
at the margins and just beneath the pleura. Generally they adhere 
closely to the surrounding tissue, var^'ing in color from yellow, grayish 
yellow, reddish brown, violet, or black according to their age and the 
character of the inflammatory process. All of the centers become caseous 
and finally undergo calcareous infiltration. 

In addition to the bronchial and pulmonary lesions there are presented 
in severe cases the evidences characteristic of ansemia and cachexia, 
involving subcutaneous edema and serous exudate in the cavities of the 
body. 

Dogs which have suffered from cardio-pulmonary strongjdosis will, 
on necrops3% reveal adult worms {Hcemostromjylus vasorum) in the right 
heart and branches of the pulmonary artery. The lungs at the bases of 
their lobes show circumscribed granular areas in which the tissue is 
gra\', compact, and heavier than water. The granules are hardly the 
size of a pin's head, semi-transparent, and give a roughened aspect to 
the surface. About the eggs and embryos lodged in the small arterioles 
there are found small pseudo-follicles which, on histological examina- 
tion, will exhibit three zones, — (1) a central consisting of a giant cell 
containing a segmented egg or embryo; (2) a middle of epithelial cells; 
and (3) a peripheral consisting of embryonal tissue elements disposed 
circularly. Larger nodules may be found, usually in close relationship 
to a clot in a branch of the pulmonary artery in the vicinity of which 
there is an accumulation of adult strongyles. 

Development and Etiology. — The lungworms deposit their eggs in 
the respiratory passages of their host and the freed embr^'os are either 
expelled directly with the bronchial secretion or, passing to the pharynx, 



264 PARASITES OF THE DOMESTIC ANIMALS 

are swallowed and reach the outside with the feces. Further than this 
little is known as to their life history. The larvae do not appear to pass 
through any stages of development in the bronchi of their host, the first 
phases of their existence probably requiring that they be expelled from 
the animal. 

Having reached the outside, if the larvae encounter sufficient warmth 
and moisture, they molt and this is later followed by a second molting 
after which they retain their coverings and in this condition may resist 
desiccation for a long thne. It is probable that the larvae find their 
way to a host with the wet grass and, especially in the case of sheep, 
with collections of water upon the pastures which the animals drink. 
The view as to direct development and infection is supported by the 
investigations of Romanovitch and Slavine (p. 256), and it seems 
probable that in all cases of bronchial and pulmonary strongylosis the 
infection is direct. Some authors, however (Cobbold, Leuckart), be- 
lieve that a portion of the larval stage is lived in an invertebrate host, as 
an earthworm, larval insect, or mollusc. 

The larvae are usually taken up by the host animals in the spring, 
though it is probable that infection may occur at any time during the 
pasture season." That infection cannot occur directly from animal to 
animal has been demonstrated by Leuckart, Herms and Freeborn and 
others who were not successful in bringing it about l^y the introduction 
into the respirator3^ passages and stomach of bronchial mucus containing 
numerous embryos. 

The course of the larval worms in reaching the l^ronchi after natural 
infection by way of the digestive organs has not been demonstrated. 
Based upon the function of rumination and the peculiar susceptibility 
of ruminating animals, the invasion of the air passages has been attrib- 
uted to the regurgitation of contaminated food, the worms passing 
from the pharynx to the larynx and trachea. But this hypothesis seems 
to have no more than plausibility in its support, and certainly cannot 
well apply to the case of the non-ruminating hog. 

Control. — In districts where bronchial and pulmonary strongylosis 
prevails, low, marshy and wet pastures or parts of pastures should not 
be accessible to susceptible animals. Drainage and a liberal covering 
of the ground with lime phosphates will do much to destroy the larvae. 
Bearing in mind that young animals are more susceptible to attack than 
older ones, it is advisable where the disease prevails to give them feed 
and water each day before they are turned upon pasture. This will in a 
measure prevent them from going to pools and marshy places for water 
where they are likely to linger and graze unless their night's fast has 
been previously somewhat broken. Where hogs and cattle are con- 
cerned the pens, stables and drinking places should be repeatedly cleaned 
and disinfected. Sputum, feces and bedding are not to be placed 



METASTRONGYLIN.E 265 

with manure to be spread upon the fields, but should be collected and 
burned as should also the infected respirator}?- organs of slaughtered 
animals. 

Treatment. — ^Treatment with a view to attacking the worms by way 
of the digestive tract with remedies supposed to act by their excretion 
through the lungs can at most be but mildly successful. Administered 
in this way, a sufficient quantity of the anthelmintic to be effectual would 
probably include the host in its destructive effect. 

Fumigation with various substances has been recommended and 
widely practiced. This procedure has more to reconnnend it than the 
first mentioned in that the remedy reaches the worms directly, having 
such a deleterious action upon them that the}' are more readity expelled 
in the coughing induced by the irritant smoke and vapors. Again an 
objection to the method is the intensity of application required for its 
success, this demanding that the animals be subjected to the fumes until 
they are dangerously close to asphyxiation. 

AVhere the fumigation treatment is resorted to it should be carried 
out in a tightly closed building to accommodate not more than fifty 
lambs at a time. Among the various substances which have been used 
to generate the fumes are tar, creolin, asafetida, horns,- hoofparings, hair 
and the vapor of heated oil of turpentine. The intensity and duration 
of the treatment should be governed by the size and vigor of the animals 
and according as they become accustomed to it. At first it should not 
be applied for more than a few minutes each day; later two or three 
treatments of ten or more minutes duration each may be given daily. 
During the fumigation the animals should l)e closol}' watched for evi- 
dences of asphyxiation. 

Of agents for creating the fumes, tar, sulphur and turpentine may l^e 
mentioned as prol)ably among the best. These may be placed upon 
hot coals contained in a pot suspended by a chain from the ceiling in 
such manner that it will be just l)cyond the reach of the animals' heads. 
The fumes should fill the entire enclosure and can be maintained by 
adding more of the ingredients as required. 

A more successful method of treatment is by tracheal injections of 
liquids which will kill the worms or reduce their vitality to a sufficient 
degree that they may be easily expelled. This procedure is espe- 
cially to be reconmiended for calves and is equally effectual for lambs, 
though where flocks of considerable size are involved, it is not so 
practicable. 

The measure of success attauied by such treatment will depend largely 
upon the degree to which the worms and their larvae have penetrated to 
the deeper parts of the respiratory organs. The solutions used must 
reach their destination l)y gravity, aided somewhat In- the currents of 
inspired air, so that ultimately they will probably pass no further than 



266 PARASITES OF THE DOMESTIC ANIMALS 

to the anterior portions of the lungs, the more deeply lodged parasites 
remaining unaffected. Furthermore, where an air passage is occluded 
by a mucus plug and mass of worms, the remedy will not pass beyond 
the obstruction and, therefore, cannot reach the further ramifications of 
the passage. 

Probably aqueous solutions for intratracheal injection have an ad- 
vantage in more readily becoming diffused. Oily preparations do not 
penetrate so deeply nor do they mix with the mucus. On the other hand, 
it is to be said in their favor that they are not so readily absorbed as 
aqueous solutions and remain in the air passages longer. The use of 
both aqueous and oily mixtures conjointly might well be recommended. 

Among the numerous formulae for intratracheal injection the following 
may be mentioned; (1) Iodine two parts, iodide of potassium ten parts, 
distilled water one hundred parts. Mix and inake into an emulsion with 
equal parts of oil of turpentine and olive oil. Give one to two drams to 
each sheep; calves three to four drams. Two injections with an interval 
of two days may be sufficient. (2) One per cent, aqueous solution of 
carbolic acid. Sheep one to one and a half drams, calves three to five 
drams. Inject once daily for several successive daj^s. (3) Creolin five 
parts, oil of tupentine and olive oil of each fifty parts. Sheep one to 
one and a half drams, calves three and a half to five drams. Inject once 
daily for three successive da5'^s. (4) Creosote twenty parts, oil of amyg- 
dala one hundred parts. Calves one to one and a half drams. Inject 
once daily for four days. 

The intratracheal injections should be made slowly with a curved 
needle of large caliber or with a curved trochar. Previous to the opera- 
tion the wool should be shaved or closely clipped from the region. The 
needle should enter between the tracheal rings, preferably after a small 
incision has been made in the skin. 

Based on experiments which they carried on for over one year (1914), 
involving about two hundred and fifty animals, Herms and Freeborn 
concluded that chloroform administered nasally is, under proper condi- 
tions, a valuable method of treatment. The chloroform is introduced 
first into one nostril, then into the other, with an all glass syringe or 
medicine dropper in doses sufficient to nearly anaesthetize the animal, or, 
in other words, until it becomes "groggy." The dosage required for 
this will depend upon the animal's susceptibihty, and therefore cannot 
be exactly given. It is stated as varying from twenty-three to forty-six 
drops for angora goats, and from sixty to one hundred and sixty-five 
drops for calves, one-half the quantity in each nostril. The treatment is 
to be repeated at five or six day intervals until recovery, which, under 
good conditions of food and shelter, should not require more than three 
injections. Experiments by the investigators mentioned have shown 
that, while the worms were not killed immediately, death and disin- 



METASTRONGYLIN^ 267 

tegration of most of them occurs a few hours after the administration of 
the chloroform when large numbers are expelled in coughing. 

Whatever procedure maj^ be adopted in the treatment of bronchial 
and pulmonary strongylosis, or if treatment is not attempted, it is highly 
important that the animals receive plenty of nourishing food and that 
they be well sheltered against cold and wet weather. 



CHAPTER XXII 
NEMATODA. SUBFAMILY II. TRICHOSTRONGYLINiE 

WOEMS OF THE StOMACH AND INTESTINE 

Strongylidse (p. 255). — These strongyles are parasitic only in the 
ahmentary canal. The mouth is simple and without a buccal capsule 
(Fig. 135). The body is generally straight or it may be somewhat 
curved. The eggs are generally segmented at the time they are de- 
posited. Development is direct, and infection, so far as known, is only 
b}^ ingestion. 

Gastro-Intestinal Strongylosis of the Sheep and Goat 

1. Haemonchus contortus (Strongylus contortus). Fig. 134. 
Trichostrongylinse (p. 268). — The body is filiform, attenuated at the 
extremities, and red or white in color. The integument is striated 
transversely. Near the anterior extremity there are two lateral tooth- 
like papillae directed backward. The bursa of the male has two long 
lobes and a small lobe accessory to the right (Fig. 136); there are two 
spicules. The tail of the female is acutely pointed; anterior extremity 
more gradually attenuated ; vulva toward posterior fifth of the bod^'. 

Length of female, 18-30 mm. (11/16-1 3/16 inches) ; male, 10-20 mm. 
(3/8-3/4 of an inch). 

The eggs are elongated oval and measure 70-95 microns long by 
43-54 microns wide. According to Railliet they contain developed 
embryos at the time of deposition. Hatching probably takes place in 
water, the embryo at the time of its release measuring 300-400 microns 
in length by 17-21 microns in breadth. Infection is probably b}' drinking 
water and contaminated pasturage bearing the larvae. 

The worm is parasitic in the abomasum and duodenum of sheep, 
goats, and cattle. 

2. Cooperia curticei (Strongylus ventricosus; St. curticei). Fig. 
137. Trichostrongylinse (p. 268).— The anterior end of the body is 
usually coiled spirally. The cuticle at the region of the head is striated 
transversely; cuticle of remainder of the body exhibits fourteen to six- 
teen longitudinal lines. The mouth is small and not well defined. The 
bursa of the male has two lateral lobes and a small median lobe. The 
spicules are short. The vulva of the female is close to the posterior end 
of the body. Tail slender and acutely pointed. « 



TRICHOSTRONGYLIN.E 



269 





nv.l. 

Fig. 136. — Hsemonchus contortus, — enlarged, 
Posterior extremity of male, dorsal Aaew; d. 
dorsal ray supporting the asymmetrically 
situated dorsal lobe of bursa; e. d., externo- 
dorsal ray; e. 1., externo-lateral ray; gub., 
gubernaculum; 1. v., latero-ventral ray; m. 1., 
medio-lateral ray; p. 1., postero-lateral ray; 
sp., spicule; v. v., ventro-vcntral ray (after 
Ransom, Bull. No. 127, Bureau An. Ind., U. S. 
Fig. 134.— l:S::^^}^m, Dept. Agr.). 

Hsemonchus con- i c c i i / / 

tortus, female. Fig. i35.-Ha5mon- Length oi tcniale, about 6 mm. (1/4 
*Vuiva. x5. (Af- chus contortus, an- of an inch); male about 5 mm. (3/16 

ter Ransom, Bull, terior portion of 



No. 127, Bu 
An. Ind., U. S 
Dept. Agr.). 



body, — enlarged: c. 
p., cervical papilla; 
es., esophagus; int., 
intestine; n. r., nerve 
ring (after Ransom, 
Bull. No. 127, Bu. 
An. Ind., U. S. Dept. 
Agr.). 



of an inch). 

The eggs are oval, 63-70 microns in 
length by 30-32 microns in width, seg- 
mented at time of deposition. 

The worm is parasitic in the small 
intestine, more rarely the abomasum, 
of the sheep and goat. 
3. Ostertagia marshalli. Fig. 139. Trichostrongylinae (p. 268). — 
The mouth is small and surrounded b\' six indistinct papillae. The 
cuticle has twenty-five to thirty-five longitudinal ridges appearing as 
lines. Cervical papillae 340-415 microns from anterior end of the body. 
The bursa of the male is bilobate; spicules short and similar, yellowish 
brown in color. The tail of the female is slender, gradually tapering, 
and rounded at the tip. The \ailva is a transverse slit located near the 
tail extremitv. 



270 



PARASITES OF THE DOMESTIC ANIMALS 





Fig. 137. — Cooperia curticei; male at 
right, female at left. *Vulva. xl5. 
(After Ransom, Bull. No. 127, Bureau 
An. Ind., U. S. Dept. Agr.). 




Fig. 139. — Ostertagia marshalli; male at right, female at 
left, enlarged (after Ransom, Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 



m 



Fig. 138.— Co- 
operia curticei, 
anterior portion 
of body, lateral 
view. x300. (Af- 
ter Ransom, BuU. 
No. 127, Bureau 
An. Ind., U. S. 
Dept. Agr.). 



TRICHOSTRONGYLIN.E 



271 



Length of female, 12-20 mm. (1/2-3/4 of an inch); male, 10-13 mm. 
(3/8-1/2 an inch). 

The eggs are oval, 160-200 microns in length by 75-100 microns in 
breadth. 

The worm is parasitic in the abomasum, rareh^ the small intestine, 
of the sheep. It was first collected by Dr. H. T. Marshall and Prof. 
V. K. Chestnut in Montana. 

4. Trichostrongylus instabilis (Strongylus colubrif ormis ; St. in- 
stabilis). Fig. 140. Trichostrongylina? (p. 2r)S).^The body is small, 
slender, gradually attenuated forward from 
posterior fifth; color reddish. Cuticle trans- 
versely striated ; longitudinal lines and cer- 
vical papilla3 absent. The bursa of the 
male is large and laterally lobed; spicules 
short, spatulate, and appearing as though 
twisted. The body of the female is but 
slightly thinner toward the anus; behind 
the anus it suddenly narrows to form a 
sharp tail; vulva near middle of posterior 
half of the body. 

Length of female, 5-6 mm. (1/4 of an 
inch) ; male, 4-5 mm. (3/16 of an inch). 

The eggs are oval, 73-76 microns 
length by 40-43 microns in breadth. 

The worm is parasitic in the duodenum 
of sheep and goats of North Africa, Europe, 
Japan, and United States. In Egypt it 
has been observed in man. 

Other species which may be found in 
sheep and goats are Nematodirus filicollis 
and Cooperia oncophora which are referred 

to under gastro-intestinal strongylosis of som, Bull. No. 127, Bureau An. 
cattle. Ind..U.S.Dept.Agr.). 

Occurrence. — Gastro-intestinal strongylosis of sheep and goats is 
generally caused by the presence of Hccmonchiis contortiis which may 
be in association with one or more other species. This stomach worm 
is recognized as one of the most serious of the numerous pests with 
which the sheep raiser has to contend. Animals of all ages become 
infected, but the most serious effects are observed in lambs and kids. 
Occurring mostly in wet marsh}' districts and in seasons of frequent rain 
— conditions favorable to the propagation of the lung as well as the 
gastric worms — the affection is frequently associated with the respiratory 
form of strongylosis. 

In the United States the stomach worm of sheep, goats, and cattle 




Fig. 140. — Trichostrongylus in- 
stabilis; male at right, female at 
left.—* Vulva. xl5. (After Ran- 



272 PARASITES OF THE DOMESTIC ANIMALS 

is especially prevalent in the Mississippi Valley, in the region of rivers 
tributar}^ to the Mississippi, and in the Gulf States. In parts of the 
Middle AVest and South the parasite has been such a source of discour- 
agement as to cause the sheep industry to be almost completely aban- 
doned. 

Pathogenesis. — Taken up as larvte with ingested plants or drinking 
water, the worms attack the mucosa of the fourth stomach and feed 
upon the blood of their host. The degree of disturbance which they 
cause will be proportionate to their number. Heavy infestations are 
accompanied by disorders of digestion and lead through loss of blood 
to anemia, dropsy, and emaciation, the general morbid effect being 
contributed to b}^ the toxins elaborated by the parasites. 

Symptoms. — The symptoms are those of a pernicious anaemia. The 
infected animal becomes dull and spiritless and there is arrested develop- 
ment. The appetite is diminished and depraved, and the animal fre- 
quently seeks water to quench an intense thirst. The anaemia is revealed 
in the paleness of the skin and visible mucous membranes and in the 
edematous swellings in dependent parts of the body, often under the 
lower jaw. Later in the course of the disease a diarrhea appears with 
Avatery dark discharge of putrid odor. In some cases the toxic disturb- 
ances may be manifested by convulsions or paralysis. Finally, after a 
course of several months, the animal dies in a state of extreme emacia- 
tion and weakness. 

The cause of these symptoms of a progressive anaemia can often be 
no more than suspected, and, where the condition prevails in flocks, a 
more certain diagnosis may be made by killing an affected animal and 
examining the fourth stomach. 

For Post-mortem Appearance, Development, Control, and Treat- 
ment, refer to pp. 275-279. 

Gastro-Intestinal Strongylosis of Cattle 

Several species of strongyles may occur in the abomasum of cattle- 
Of these the most important are Hcemonchus contortus, described under 
gastro-intestinal strongylosis of sheep, and the encj^sted stomach worm, 
Ostertagia ostertagi. 

1. Ostertagia ostertagi (Strongylus ostertagi). Fig. 141. Tricho- 
strongylinae (p. 268). — The body is filiform with attenuated extremities. 
The mouth is small and surrounded by six indistinct papillae; cervical 
papillae present. The cuticle has 25 to 35 longitudinal lines or ridges. 
The bursa of the male is comparatively small and has two lateral lobes 
united bj' a small median lobe (Fig. 142). The spicules are short, each 
having two slender barbed processes coming off from the inner side in 
the posterior half. The vulva of the female is a transverse slit covered 



TRICHOSTROXGYLIX.E 



273 



\n^ i-s/x 



.p.bp. 





Fig. 142. — Ostertagia ostertagi. 
Posterior extremity of male with 
bursa spread out: d, dorsal ray; e. d., 
externo-dorsal ray; p. 1., postero- 
lateral ray; m. 1., medio-lateral ray; 
e. 1., externo-lateral ray; 1. v., latero- 
ventral raj-; v. v., vontro-ventral ray; 
p. b. p., pre-bursal papilla; sp., spi- 
cules. xloO. (After Ransom, from 
Railliet, Bull. No. 127, Bureau An. 
Ind., U. S. Dept. Agr.). 

b}' a prominent cuticiilar flap; it is located 
close to the caudal extremity of the body. 
The tail tapers gradually and ends in a slen- 
der tip. 

Length of female,, 8-10 mm. (5/16-3/8 of 
an inch) ; male, 7-8 mm. (1/4-5/16 of an inch.) 

The eggs are oval, 65-80 microns in length 
by 30-40 microns in breadth. 

The worm is parasitic in the wall and cavity of the abomasum of 
cattle. 

2. Nematodirus filicoUis (Strongylus filicoUis). Fig. 143. Tricho- 
strongylinae (p. 268). — This is a white hair-like worm, very thin in front, 
thicker behind. The cuticle has eighteen longitudinal ridges. The 
bursa of the male is bilobate; there are two very long and slender spicules 
united by a membrane posteriorly which forms a spatulate enlargement 
at the tip. The \iilva of the female is a transverse slit located about 
one-third of the length of the body from the caudal e.xtremity. At this 
location the bodv has its maximum thickness which is suddenly reduced 



Fig. 141. — Ostertagia oster- 
tagi; male at right, female at 



left, 
som, 
Ind. 



* Vulva. xl5. (After Ran- 
BuU. No. 127, Bureau An. 
U. S. Dept. Agr.). 




Fig. 143. — Nematodirus filicollis; male in center, female at left. * Vulva. xl5. At 
right, enlarged anterior portion of body. (After Ransom, Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 




Fig. 144. — Cooperia oncophora; male at right, female 
at left. * Vulva. xl5. (After Ransom, Bull. No. 127, 
Bureau An. Ind., U. S. Dept. Agr.). 



TRICHOSTRONGYLIX.E 275 

just behind the vulva. The tip of the tail is truncate and bears a short 
bristle-like process. 

Length of female, 10-24 mm. (3/8-15/16 of an inch); male, 8-13 nmi. 
(5/16-1/2 of an inch). 

The eggs are elongated oval, 110-113 microns in length b}' 64-70 
microns in breadth; segmented at time of deposition. The further 
development is not known. 

The worm is parasitic in the small intestine of cattle, sheep, and goats. 

3. Cooperia oncophora (Strongylus oncophora). Fig. 144. Tricho- 
strongylina' (p. 268). — The head is rounded, without well-marked papil- 
lae; mouth cavity small and not well defined. The cuticle in the region of 
the head is transversel.y striated; cuticle of remainder of body with 14- 
16 longitudinal lines or ridges; cervical papillae absent. The bursa of 
the male, when spread, is large and has two lateral lobes and a small 
median lobe; border of median lobe incised. The spicules are short 
and of comparatively simple structure. The vulva of the female is in 
the posterior fourth of the body. At the region of the vulva the body is 
much enlarged. The tail is slender with rounded tip; terminal portion 
of tail marked with annular striations. 

Length of female, 6-8 mm. (5/16 of an inch) ; male about the same. 

The eggs are oval, 60-80 microns in length by 30 microns in width. 

Inhabits the small intestine of cattle and sheep. 

Occurrence and Symptoms. — Haemonchus contortus is frequently 
found in the al)omasum of cattle. When the infestation is heav}', which 
usually occiu's in young pastured animals, they bi'ing about the sjniip- 
toms of a pernicious anaemia as descriljed in the infestation of sheep. 
The cattle become infected ])y grazing upon pastures which are contam- 
inated by the di'oppings of infected sheep, goats, or other infested cattle. 

The s\Tuptoms caused by the presence of Ostertagia ostertagi, or the 
cncj^sted stomach worm, are similar to those produced Ijj" Hcemonchus 
contortus. It lives in small cysts in the mucosa of the abomasum and 
is also found free in the contents of this organ. When numerous, they 
cause a catarrhal condition and disturbances of digest-ion. 

For Post-mortem Appearance, Development, Etiology, Control, and 
Treatment refer to pp. 275-279. 

Gastro-Intestixal Strongylosis. Post-AIortem Appearance 

Examination of the contents of the abomasum and duodenum from 
an animal which has been heavily infested with stomach strongyles 
will reveal undulating movements of the fluitl produced by the active 
wriggling a})Out of the worms. Large num])ers will also be found deeply 
adhering to the mucosa which will show the lesions of a subacute or 
chronic catarih. Further than this, the pernicious anaemia is evidenced 



276 PARASITES OF THE DOMESTIC ANIMALS 

in the paleness of the body tissues, edematous swelHngs, exudate into 
the serous cavities, and cachexia. 

Where Ostertagia ostertacji are present in the abomasum of cattle they 
will be found both free in the stomach contents and embedded in the 
subepithelial tissue of the mucosa in small round cysts about the size 
of a pin-head or slightly larger. When numerous, the same lessions are 
shown as in the attack upon the mucosa of a heaw invasion with Hcemon- 
chiis contortus. 

Gastro-Intestinal Strongylosis. Development and Etiology 

The eggs of Hoemonchus contortus passed in the feces of the host will 
hatch in a variable time according to the conditions of temperature and 
moisture. When these are favorable it may occur in a few hours, while, 
under more adverse conditions, it may take several days or weeks. 
Drj^ness or a freezing temperature kills the embryos and newly hatched 
larvae in a short time. Upon hatching the larva feeds upon the fecal 
matter with which it is surrounded. Later it becomes enveloped by a 
chitinous sheath, in this condition probably receiving nourishment 
from food material stored within its body. At this stage the larva can 
survive freezing and drying for long periods and is motile at temperatures 
above 40° F., becoming more active with increase in temperature. Where 
there is sufficient moisture, as from dew or rain, it crawls upon a blade 
of grass or other vegetation and gradually makes its way to a position 
well removed from the ground. In this position it is taken up by the 
grazing ruminant host and, reaching the abomasum, becomes mature in 
two to four weeks. If the eggs or newly hatched larvce are ingested 
they apparently do not undergo further development. It seems, there- 
fore, that only the ensheathed larvae are infective. 

Control. — As stated in the foregoing, moisture favors the develop- 
ment of the embryos, while dryness kills them at their early stages. 
High pasture ground, therefore, with good natural drainage greatly 
reduces the chances of the larvae reaching the infective stage. Further- 
more, larvae which have become infective are more motile in the presence 
of moisture such as is supplied by the heavy dews and fogs occurring 
over low land; crawling, then, out upon the wet blades of grass, the 
worms are more likely to be taken up by the grazing animals. 

If the temperature remains constantly at about 95° F. the infective 
larval stage is reached in three to four days after the eggs have passed 
from the body of the host. At 70° F. one to two weeks are required, 
while three to four weeks are necessary at about 50° F. At temperatures 
below 40° F. the eggs are dormant and the larvae remain inactive. Under 
the usual climatic conditions of the northern part of the United States, 
therefore, there is little possibility of new infection from placing in- 



TRICHOSTRONGYLIN^ 277 

fectecl and noninfected animals together in clean fields from the first 
of November until March. 

During the warmer months the best means of controlling the parasite 
seems to be by the rotation of pastures, keeping each pasture free from 
sheep and cattle for at least a 3'ear, by which tmie the larvffi will be dead. 
As to this method Ransom (U. S. B. A. I., Cir. No. 102) suggests the 
following: "Infested and nonmfested sheep which have been kept to- 
gether in clean fields from November to March or later, according to 
weather, if moved then to another clean field may remain there nearly 
the entire month of April before there is danger of infection. From the 
first of Ma}' on through the summer the pastures become infectious much 
more quickly after infested sheep are placed upon them, and during 
May it would be necessary to move the sheep at the end of every two 
weeks, in June at the end of everj^ ten days, and in July and August at 
the end of each week, in order to prevent the noninfected sheep from 
becoming infected from the worms present in the rest of the flock. 
After the first of September the period maj^ again be lengthened." 

The difficulties and inconveniences of this method consist in the num- 
ber of small pastures and subdivisions of pastures which it requires; 
furthermore, it imposes limitations upon the size of the flock. It is, 
however, probably the most effective system thus far devised for the 
eradication of this parasite. 

Where it can be convenientl.y practiced, it is a good precautionarj^ 
measure to burn over the pastures in the early spring or fall. This will 
destroy most of the eggs and larvae which are lodged upon the grass or 
upon the ground. 

Treatment. — Experiences recorded with the use of drugs for the 
expulsion of stomach worms are somewhat varied. The success attained 
by such treatment has not equaled expectations based upon experiments 
made with the agents upon worms outside of the bod}'- of a host. It is 
probable that this is mainly due to the fact that drugs administered to 
ruminants by the mouth do not pass directly to the abomasum, but must 
first mix with the ingesta of the rumen and reticulum, passing from the 
latter by way of the omasum to the abomasum and intestine. Hence, 
before reaching the worms the drug become sufficiently diluted or mixed 
with the bulky ingesta to greatly reduce its effectiveness. Treatment 
for the expulsion of Hcemonchus contortus gives better promise for success 
than that for the smaller stomach strongjdes, as Ostertagia ostertagi, 
owing to the protected position of the latter within the nmcosa. 

Animals which are to be treated should be taken up in the afternoon 
of the day previous to treatment and all food withheld from them for 
eighteen to twenty-two hours. The remedy should be given the following 
morning either with a long-necked bottle or, better,, with a drenching 
tube consisting of about three feet of one-half inch rubber tubing with 



278 PARASITES OF THE DOMESTIC ANIMALS 

a funnel inserted at one end and a four to six inch piece of metal tubing 
inserted in the other end, the metal tube to be placed in the animal's 
mouth between the molar teeth. The funnel may be held by an assistant 
or fastened to a post while receiving the liquid, the flow of which may be 
controlled by pinching the rubber tube near the insertion of the metal 
piece. The dosage for each sheep should be carefully measured accord- 
ing to age, and care taken to lower the head at once upon entrance of 
the liquid into the larynx, this often a result of holding the head too high 
and indicated by coughing. 

Among the remedies used for the expulsion of stomach worms may 
be mentioned (1) copper sulfate, (2) gasoline, and (3) coal-far creosote. 
An objection to the last named is its variable composition, the substance 
not infrequently sold under the name of coal-tar creosote being quite 
unreliable for the purpose here considered. Copper sulfate has received 
high recommendation and is extensively used in the sheep flocks of 
South Africa. It ma}^ be prepared and given as follows: 

Dissolve 1/4 of a pound (avoirdupois) of clear blue crystals of copper 
sulfate in one pint of boiling water, having first crushed the crystals in 
a mortar to a fine powder. In making the solution use a porcelain or 
enamel-ware vessel as the bluestone will corrode most metals. Add to 
this solution enough cold water to make it up to three gallons, using 
non-metallic receptacles. This will make an approximate one per cent, 
solution, and, allowing for waste, will be enough for the treatment of 
about one hundred adult sheep. 

The dosage is to be graded according to age as follows : 

Lambs 3 months to 1 year old 5 drams to 11/2 oz. (20-50 cc). 

Sheep over 1 year old 2 to 3 oz. (64 to 96 cc). 

Calves 3 to 4 oz. (96 to 128 cc). 

Yearling cattle 6 oz. (192 cc). 

The annuals should receive no water at any time during the day the^' 
are dosed. 

"NMiere the stomach worm exists in a fiock, it has been suggested as a 
control measure to give 50 cc of a one per cent, solution of copper 
sulfate every month or so except during the winter in climates where 
the winter is freezing. 

Gasohne has afforded a convenient remedy, but, for reasons which 
need not be gone into here, the commercial gasoline of the present time 
is unsuitable for this purpose. Under such conditions onty the official 
purified gasoline (benzinum purificatum, U. S. P.) should be used. At 
best, however, gasolme is probably less satisfactory for the purpose 
than copper sulfate; furthermore, to be effectual, the gasoline treatment 
must be repeated upon three consecutive days. 

In the preparation for the administration of gasoline withhold water 



TRICHOSTRONGYLIN.E 279 

as well as feed. The following morning give the gasoline in milk, linseed 
oil, or flaxseed tea, mixing the dose for each animal according to age as 
follows : 

Lambs 2 drams (8 cc). 

Sheep 4 drams (16 cc). 

Calves 4 drams (16 cc). 

Yearling cattle 1 oz. (32 cc). 

Three hours later allow feed and water. At night again confine the 
animals without feed and water. The next morning give the second 
dose, the third morning the third dose, the treatment before and after 
dosing being the same in each case. Gasoline should not be given in 
water, nor should it be given soon after the animals have taken water. 

Coal-tar creosote may be given in solution of one per cent, strength. 
The solution is made by shaking together one ounce of coal-tar creosote 
and ninety-nine ounces (6 pints and 3 ounces) of water. The doses of 
this as recommended by Stiles are as follows: 

Lambs 4 to 12 months old 2 to 4 ounces 

Yearling sheep and above 3 to 5 ounces 

Calves 3 to 8 months old 5 to 10 ounces 

Yearling steers 1 pint 

Two-3' ear-olds and above "... 1 quart 

If a good qualitA' of coal-tar creosote is used, good results may l)e 
obtained from a single dose of this one per cent, solution. 

Other remedies, such as lysol and arsenic, have been recommended 
by various authors, but probably the most effectual will come within 
those which have been particularly mentioned. 

The treatment should be administered to the entire herd, since an- 
imals which may be but lightly infested will remain a source of reinfec- 
tion to others. 

The general condition of the animals should be built up and main- 
tained by a generous supply of nourishing food and thoy should receive 
a plentiful supply of salt. 



CHAPTER XXIII 
NEMATODA. SUBFAMILY III. STRONGYLIN^ 

Worms of the Large and Small Intestines; Other Strongyles 

These worms are parasitic in the digestive tract, rarely in the respi- 
ratory organs. The buccal capsule is present. The bursa of the male 
is well developed and has one or two dorsal rays and two lateral ray 
systems of six rays each. There are two spicules. The vulva of the 
female is usually posterior to the middle of the body, but may be anterior 
to the middle. There are two ovaries. 

The eggs are segmented at the time they are deposited. The embryos 
are rhabditiform. The development, so far as known, is direct. In 
some forms the development is complex, involving a nodular phase or 
larval migration. 

Based mainly upon the formation of the bursal rays and the location 
of the vulva, the Strongylinse have been grouped by Railliet and Henry 
into five tribes, as follows : 

Tribe I. OEsophagostomese 

Tribe II. Strongyleae (Ankylostomese) 

Tribe III. Bunostomese 

Tribe IV. Cylicostomese 

Tribe V. Syngameae 

I. (Esophagostomeae. Strongyhnae (p. 280). — The bursa of the male 
has two lateral lobes united by a smaller median lobe. In each lateral 
lobe there are six rays. The ray of the median lobe divides into two 
main branches, each of which again divides into two. The vulva of 
the female is situated a short distance in front of the anus; uteri diver- 
gent. The tribe includes three genera, as follows : 

Genus I. (Esophagostomum 
Genus II. Chabertia (Sclerostomum) 
Genus III. Agriostomum 

II. StrongyleaB. Strongylinse (p. 280). — The ventral and latero- 
ventral rays of the lateral bursal lobes are close together and parallel. 
The medio-lateral and postero-lateral rays are not close together and 
parallel. The dorsal raj^ ends in tridigitate terminations. The vulva 
of the female is situated in the posterior third of the body; uteri diver- 
gent. The tribe includes four genera, as follows: 

Genus I. Strongylus 

Genus II. Ankylostoma 

Genus III. Uncinaria 

Genus IV. Characostomum 



STROXGYLIX.E] 281 

III. Bunostomeae. Strongylinae (p. 280).— The ventral and latero- 
ventral rays of the bursal lobes are close together and parallel. The 
medio-lateral and posterolateral rays are not close together and are 
not parallel. The dorsal ray ends in a bifurcation. The vulva of the 
female is situated in the middle of the body or a httle anterior to the 
middle; uteri divergent. The tribe includes four genera, as follows: 

Genus I. Bunostomum 
Genus II, Gaigeria 
Genus III. Bathmostonunn 
Genus IX. Grammocephalus 

IV. Cylicostomeae. Strongyhnae (p. 280).— The ventral and latero- 
ventral raj's of the bursal lobes are close together and parallel. The 
medio-lateral and postero-lateral raj's are not close together and parallel. 
The dorsal and externo-dorsal rays originate separately. The vulva 
of the female is situated close to the anus; uteri convergent. The tribe 
includes four genera, as follows: 

Genus I. Cylicostomum 

Genus II. Q^sophagodontus 

Genus III. Gyalocephalus 

Genus IV. Triodontophorus 

Y. Syngameae. Strongylinse (p. 280). — The bursa is obhquely trun- 
cated. The anterior and middle rays are cleft, the posterior tridigitate. 
The vulva of the female is situated in the anterior quarter of the body; 
uteri divergent. The tribe includes one genus — Syngamus. 

XODULAR StROXGYLOSIS OF THE ShEEP AND GOAT. CEsOPHAGOSTO- 

MIASIS 

1. (Esophagostomum columbianum. Fig. 145. Strongylinse (p. 
280). — The thickness of the body is nearly uniform over its greater 
portion; attenuated toward ends. The anterior portion is usually 
curved in the form of a hook. The cuticle surroimding the mouth is 
inflated to form a collar which has ahnost the shape of a hemisphere. 
Six circum-oral papillse penetrate this mouth collar. In front of the 
middle of the esophagus there is a transverse groove with accompanying 
cuticular fold extending around the body to the lateral lines. There are 
two cervical papillae in front of the middle of the esophagus. Posterior 
to the cervical groove are two lateral membranes which extend well 
back along the lateral lines. The bursa of the male has two lateral lobes 
united by a small median lobe. The spicules are 750-850 microns in 
length, slender and pointed. The ^^lva of the female is naked, trans- 
versely elongated, and situated a short distance in front of the anus. 

The length of the female is 14-18 mm. (9/16-11 16 of an inch); male, 
12-15 mm. (1 '2-19 '32 of an inch). 



28^2 



PARASITES OF THE DOMESTIC ANIMALS 




Fig. 145. — -ffisophagostomum columbianum; male 
at left, female at right. * Vulva. x5. (After Ran- 
som, Bull. No. 127, Bureau An. Ind., U. S. Dept. 
Agr.). 




The eggs are oval, 65-75 microns in Fig. 146. 
length by 40-45 microns in breadth, "'"'^i^^""^- 



ffisophagostomum col- 
Anterior extremity, 
ventral view, — enlarged: c. g., cer- 

Segmentation occurs while thej^ are within vical groove; c. p., cervical papilla; 

the uterus. ^^•' esophagus; int., intestine; 1. m. , 

mi i- 1 1 ^r>^ • lateral membrane; 1. p., lateral cir- 

The freed embiyos measure 230 mi- eumoral papilla; m. c, mouth collar; 

crons in length. n. r., nerve ring. (After Ransom, 

Parasitic in the large intestine of the ?"ii- i^o- 127, Bureau An. Ind.. 

, , ^ ^ U. S. Dept. Agr.). 

sheep and goat. 

2. CEsophagostomum venulosum. Fig. 148. Strongylina? (p. 280). 

kJ^ — The thickness of the body is nearly uniform over its greater portion, 

' \.--' attenuated toward ends. The anterior end is usually straight. The 

^J^ height of the cuticular collar about the mouth is about one-third of its 

diameter. The cuticle of the neck is inflated between the mouth collar 

and the cervical groove. The lateral membranes extend well back but 

.are very narrow. The bursa of the male has two lateral lobes united by a 

small median lobe. The spicules are 1.1-1.5 mm. long. The vulva of 

the female is naked and located just in front of the anus. From a short 

distance in front of the vulva the body tapers, terminating in a sharply 

pointed tip. 

The female is 18-24 mm. (23/32-15/16 of an inch) in length; male, 
12-16 mm. (15/32-5/8 of an inch). 

The eggs are oval, 90 microns in length by 55 microns in breadth. 



STRONGYLIN^ 



283 




Fig. 147. — CEsophago.sto- 
mum columbianum. En- 
larged bursa of male viewed 
from right side: d, dorsal 



e. 1., extenio-lateral 
1. v., latero-ventral 
m. 1., medio-lateral 
p. 1., postero-lateral 
V. v., ventro-ventral 
(After Ran.som, Bull. 

No. 127, Bureau An. Ind., 

U. S. Dept. Agr.). 



raj'; 
ray; 
ray; 
ray; 
ray; 
ray. 




Fig. 150. 



Fig. 148.— (Esopha- 
gostomum venulosum ; 
male at right, female 
at left. * Vulva. x5. 
(After Ransom, Bull. 
No. 127, Bureau An. 
Ind., U. S. Dept. Agr.). 



Fig. 150. — GEsopha- 
gostomum venulosum. 
Enlarged bursa of male 
viewed from right side: 
d., dorsal ray; e. d., ex- 
tcrno-dorsal ray; e. 1., 
oxterno-lateral ray; m. 
1., medio-lateral ray; 
p. 1., postero-lateral ray; 
sp., spicules; v. v., ven- 
tro-ventral ray. (After 
Ransom, Bull. No. 127. 
Bureau An. Ind., U. S. 
Dept. Agr.). 




Fig. 149. — CEsopha- 
gostomum venulosum. 
Anterior portion of 
body — enlarged, ventral 
view: c. g., cervical 
groove; c. i, cervical in- 
flation; c. p., cervical 
papilla; es., esophagus; 
int., intestine; 1. m., 
lateral membrane; 1. p., 
lateral circumoral pa- 
pilla; m. c, mouth col- 
lar; n. r., ners'e ring. 
(After Ransom, Bull. 
No. 127, Bureau An. 
Ind., U. S. Dept. Agr.) 



Parasitic in the large intestine, more rarely in the small intestine, of 
the sheep and goat. The species has been collected in Europe and in the 
United States. It is much less common in this country than (Esophagos- 
tomum columbianum. 

Occurrence and Development. — Nodular disease of the intestines 
of sheep caused by (Esophagosotomwn cohimhianum is common in the 



284 PARASITES OF THE DOMESTIC ANIMALS 

United States. The nodules are due to the larvae which live embedded in 
the connective tissue of the submocosa, to which they at once penetrate 
after being taken up by the host. According to Marmotel, after six to 
seven months of development in this location, they pass to the intes- 
tinal lumen where they become sexually mature and the female, after cop- 
ulation, deposits her eggs. The eggs pass from the host animal with the 
feces and promptly hatch if they meet with favorable conditions of heat 
and moisture. The further development outside of a host is not known. 

Natural infection probably takes place by food and water from wet 
marshy pastures. If it occurs during August and September the larvae 
will pass from the nodules into the intestinal lumen during March and 
April, here attaining maturity and copulating in July and August. 

Post-mortem Appearance. — The nodules are most commonly found 
in the wall of the cecum and colon, but they may occur in the small 
intestine and at times on the liver and other abdominal organs. They 
may be isolated, but are frequently massed in hundreds and thousands. 
In size they vary from that of a pinhead to that of a pea, or they maj^ 
be considerably larger. Their color varies from blackish in the smaller 
ones to grayish white in the larger. The connective tissue capsule of 
the nodule is thick, and, as the nodule increases in size, it becomes filled 
with a greenish cheesy or purulent material, later becoming calcareous. 
Only the younger noclules contain the larvae. 

Symptoms. — Light infestations, with the presence of a few nodules, 
are not, as a rule, accompanied by perceptible symptoms, the condition 
in such cases being observed only after slaughtering. Relative to their 
degree, heavier invasions may be accompanied by diarrhea without a 
considerable loss of condition, or the diarrhea may be im controllable and 
accompanied by progressive emaciation and anaemia. Such cases usually 
terminate fatally after a course of two or three months, the animal 
succumbing in a state of coma. The effect of the invasion will depend 
considerably upon the age and vitality of the animals infested. 

Importance. — The fact that many slaughtered sheep that were ap- 
parently perfectly healthy show these nodules tends to lead to the im- 
pression that they are of little importance and has perhaps caused them 
to be overlooked as a primary cause of death. Cases of nodular disease 
submitted to the laboratory of the Pennsylvania Bureau of Ani- 
mal Industry indicate that the disease may assume an enzootic char- 
acter of severe type occasioning numerous losses. Usually where 
there is high mortality there is heavy infestation with large areas of 
massed nodules, though there are several factors which render this un- 
necessary to a fatal termination. Lighter invasions may have this 
result when by worms with a relatively high degree of virulence; when 
the invaded animal has a low degree of resistance, or when other worms 
are present to contribute to the morbid effect. Furthermore, these 



STRONGYLTX.E 285 

worms may infect the blood and lymph with organisms which cause 
other diseases through acting as direct carriers in penetrating the in- 
testinal wall, or by the wounds which they create affording portals of 
entrance. In such cases a comparatively slight infestation with ffisopha- 
gostomum would be sufficient for what might prove a fatal secondary 
effect. 

Treatment. — Xo effective curative treatment is known. Preventive 
measures consist in keeping the sheep from low wet areas. Where the 
disease is prevalent, lambs may be protected from serious infestation 
by placing them in a dry uncontaminated lot and feeding and watering 
them from racks and troughs sufficiently elevated that the contents 
cannot be soiled by droppings from the nursing ewes. 

Nodular Strongylosis of Cattle. Q^soPHAGOsTO\nAsis 

CEsophagostomum radiatum «E. inflatum). Fig. 151. Stron- 
g3'linse (p. 280). — The thickness of the body is nearh' uniform over its 
greater portion; attenuated toward ends. The anterior portion is 
usually curved in the form of a hook. The cuticular inflation about the 
mouth (mouth collar) is disk-like, its height a little more than one- 
fourth of its diameter. The mouth capsule is bordered by a circle of 
numerous small triangular denticles. The cervical groove and fold are 
well developed and the cuticle between it and the mouth collar is in- 
flated. This inflation has a slight constriction at about one-third of the 
distance from the cervical groove to the mouth collar. The lateral 
membranes begin at the cervical groove and extend well back along the 
bod}^; near their beginning are two cervical papillae. The bursa of the 
male has two lateral lobes united by a small median lobe; spicules 700- 
800 microns in length. The vulva of the female is transversely elongated 
upon an eminence located just in front of the anus. From the vulva the 
body i-apidly tapers, terminating in a tip which is usualh' somewhat 
bent in a ventral direction. 

The female is 16-20 mm. (5/8-3/4 of an inch) in length; male, 14-16 
mm. (9/16-5/8 of an inch). 

The eggs are oval, 75-80 microns in length by 38-43 microns in 
breadth. Their segmentation occurs within the body of the female. 

Parasitic in the small and large intestines of cattle. 

While the nodular larval stage of CEsophagostomum columhianum of 
sheep is usually found in the large intestine, that of CEsophagostomum 
radiatum of cattle is often found in the small intestine, the nodules 
usually occurring in the terminal portion with involvement of the region 
of the ileo-cecal valve and the cecmu. 

In other respects what has been said as to nodular disease of sheep 
will, in its essentials, apply to that of cattle. 



28fi 



PARASITES OF THE DOMESTIC ANIMALS 





Fig. 151. — ffisophagostomum 
radiatum; male at right, female 
at left. * Vulva. x5. (After Ran- 
som, Bull. No. 127, Bureau An. 
Ind., U. S. Dept. Agr.). 




Fig. 152. — CEsophagostomum 
radiatum. Enlarged anterior por- 
tion of bodj% ventral view: c. a ., 
annular groove surrounding cervical 
inflation of cuticle; c. g., cervical 
groove; c. i., cervical inflation; c. p., 
cervical papilla; e. p., excretory pore; 
es., esophagus; int., intestine; 1. m., 
lateral membrane; m. c, mouth 
collar; n. r., nerve ring. (After Ran- 
som, Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 




Fig. 153. — ffisophagostomum radiatum. Enlarged 
bursa of male, viewed from left side: d., dorsal ray; 
d. h., dorsal projection of trunk of lateral rays at base 
of postero-lateral ray; e. d., externo-dorsal ray; e. 1., 
externo-lateral ray; 1. t., trunk of lateral rays; 1. v., 
latero-ventral ray; m. 1., medio-lateral ray; p. 1., postero- 
lateral ray; t. d., terminal branch of dorsal ray; v. v., 
ventro-ventral ray. (After Ransom, Bull. No 127, Bu- 
reau An. Ind., U. S. Dept. Agr.). 



STRONGYLIN.E 



287 



Nodular Stroxgylosis of the Hog. (Esophagostomiasis 

CEsophagostomum subulatum (CE. dentatum). Strongylinfie (p. 
280). — The body is straight and attenuated at both (wtreniities. The 
circular mouth is surrounded by a horny ring furnished with a crown of 
converging bristles. Upon a cutaneous ridge surrounding the crown of 
bristles are six papillae. There are no lateral membranes. The bursa of 
the male has two lateral lobes united by a small median lobe; spicules 
slender. The vulva of the female is just in front of the anus and is sur- 
rounded by a prominent ring. 

The female is 12-15 nmi. (1/2-9/16 of an inch) in length; male, 8-12 
mm. (5/16-1/2 an inch). 

The eggs are oval, 60-80 microns in length by 35-45 microns in 
breadth. 

This species is found in submucous nodules and in the lumen of the 
large intestine of the hog. Considerable numbers may be present with- 
out causing serious disturb- 
ance. If the infestation is 
unusually heavy — especially 
if associated with the thorn- 
headed worm — there may be 
diarrhea, loss of appetite, 
and general unthrift. Such 
cases may be given treatment 
as reconnnended for other 
roundworms of the intestines 
of the hog. 

Strongylosis of the Large 

IXTESTINE OF THE ShEEP 

AND Goat 

Chabertia ovina ( Sclero- 
stomum hypostomum ) . Fig. 
154. Strongylina^ (p. 280).— 
The body is almost uniform 
in thickness. The head is 
slightly globular and is ob- 
liquely ti'uncated anteriorly, 
the mouth facing antero-ventrally. The buccal capsule is large; l)order 
of mouth armed with a double crown of small triangular denticles. Lo- 
cated ventrally, just in front of the excretory pore, is a short transverse 
cervical gi-oove. The bursa of the male is short and has an obliquely 
cut-off appearance; spicules long and slender. The vulva of the female 




Fiu. 1.54. — Chabertia oviiia; male at right, female 
at left. * Vulva, xo. (After Ransom, Bull. No. 
127, Bureau An. Ind., U. S. Dept. Agr.). 



288 PARASITES OF THE DOMESTIC ANIMALS 

is situated a little in front of the anus. From in front of the vulva the 
body gradually attenuates, the tail terminating behind the anus in a 
sharply pointed tip which is bent dorsally. 

The female is 17-20 mm. (11/16-3/4 of an inch) in length; male, 13- 
14 mm. (1/2 an inch). 

The eggs are oval, 90-100 microns in length by 50 microns in breadth. 
They are segmented within the body of the female. The eggs have 
similar characters to those of other sclerostomes, and it is probable that 
the evolution external to a host is the same. 

Occurrence. — Strongylosis of the large intestine of sheep due to this 
species is probably more prevalent in Europe than in the United States. 
In reference to the species, Hutyra and Marek state that it is often 
found in the colon of sheep, goats, and deer, inducing in some cases 
intestinal hemorrhage and diarrhea followed by anaemia and emaciation 
which may cause considerable loss among the young animals. 

Neveu-Lemaire speaks of strongylosis of the large intestine of sheep 
as at times ravaging certain flocks in the form of an epizootic. 

Ransom, in United States Bureau of Animal Industry, Bulletin No. 127 
(1911), refers to Chahertia ovina as follows: "This species appears to be 
comparatively harmless. Its food consists of the vegetable material in 
the contents of the large intestine. The buccal capsule is commonly 
found filled with such material." 



Strongylosis of the Intestines of the Horse. Sclerostomiasis 

1. Strongylus equinus (St. armatus; Sclerostomum equinum). 

Fig. 155. Strongylinie (p. 280). — The body is straight, rigid, and finely 

striated transversely; color gray or grayish brown, or 

^ r\ ^^ ^^^y ^-*^ shaded with red according to the amount 

i 1/ o of ingested blood. The mouth is distended by several 

chitinous rings the innermost of which are provided 
with an armature of fine teeth, while the outermost 
have six papillae. The buccal capsule has three teeth 
at its base. The bursa of the male has two lateral 
lobes between which is a smaller median lobe ; spicules 
long and slender. The vulva of the female is located 
near the posterior third of the body. The tail is obtuse. 
The length of the female varies from 20-55 mm. (3/4 
to 2 3/16 inches) ; that of the male from 18 to 35 mm. 

T. 1.. .. (11/16 to 1 3/8 inches). 

Fig. 155— Stron- ^ ' ' i „o • • i -i-i, i r < • 

gylus equinus; male The eggs are oval, 92 microns m length by 54 mi- 
at right, female at crons in breadth. Segmentation commences at the 
left, — natural size ^- £ ^j j^. ^leposition. The hatched embryos meas- 

(drawn from speci- . • i i 

mens). ure 340-500 microns in length. 



STRONGYLIX.E 289 

2. Strongylus edentatus (Sclerostomum edentatum). Strongylinae 
(p. 280).— The head is globular. The Ixiccal capsule is goblet-like, and 
teeth are absent. The bursa of the male is similar to that of Strongylus 
equinus. The vulva of the female is near the posterior third of the body. 

The female is 33-36 mm. (1 5/16-1 7 16 inches) in length; male, 23- 
25 mm. (7/8-1 inch). 

The eggs are oval and in dimensions about as in Stro7igylus equinus. 

As adults these worms are parasitic in the cecum and colon of the 
horse; as larvie in the abdominal and thoracic organs. 

3. Strongylus vulgaris (Sclerostomum vulgare). Strongylinse (p. 
280). — The buccal capsule is shallow and has a single tooth at its base, 
prominent projections causing the tooth to appear as two. The bursa 
of the male has three lobes, the median one overlapped by the two 
lateral. The vulva of the female is near the posterior third of the body. 

The female is 24 mm. (15/16 of an inch) in length; male, 15 mm. 
(5/8 of an inch). 

The eggs are as in the preceding species. 

Parasitic as adults in the cecum and colon and in immature stages in 
the mesenteric blood vessels of the horse. 

4. Cylicostomum tetracanthum (Sclerostomum tetracanthum). 
Strongylime (p. 280). — A white or reddish wiiitc worm, attenuated 
antcriorl}', the mouth surrounded l)y a cuticular fold. The buccal 
capsule is armed Avith a crown of triangular teeth. The vulva of the 
female is just anterior to the anus. 

The female is 10-18 mm. (3/8-11, 16 of an inch) in length; male, 8- 
12 mm. (5/16-1/2 an inch). 

The eggs are oval, 100 microns in length by 47 microns in breadth. 

Parasitic in the cecum and colon of the horse. 

Development. — The worms causing sclerostomiasis of the horse 
were formerly grouped under the name Strongylus armafiis. According 
to Looss (1902) it is the innnature stages of the species Strongylus vul- 
garis (Looss, 1900) which are concerned in the production of verminous 
aneurysms in the mesenteric arteries of the horse. M. Neveu-Lemaire 
(Parasitologic des Animaux Domestiques, 1912) describes the worm 
responsible for these lesions under the name Strongylus equinus. 

This worm when mature lives in the cecum and colon where it firmly 
attaches to the mucosa by its Ijuccal armature. In its agamous state it is 
found in subnuicous cysts of these organs and in aneurysms of the 
mesenteric artery. According to the investigations of Railliet the eggs, 
which are deposited in the cecum and colon and expelled with the feces, 
may develop in a few days if they meet with moisture at a temperature 
of 12° to 25° C. (53° to 77° F.). The hatched embryos, if they continue 
amid favorable conditions, grow, molt, and acquire a great vitality. It 
is at this stage that they are ingested by the equine host with the drink- 



l/ 



290 PARASITES OF THE DOMESTIC ANIMALS 

ing water or perhaps with green forage. Reaching the intestines, they 
penetrate the mucosa from which probably the majority of them reach 
the circulatory system where the}^ become lodged in the visceral arteries, 
as the trunk of the great mesenteric. After a variable time in this 
location they again enter the blood stream and, reaching the cecum, 
oecome encysted in the submocosa where their development proceeds. 
Within the cyst they possess a buccal capsule and a caudal bursa, but 
the generative organs are not as yet developed. 

Finally they pass to the lumen of the bowel where they attach to the 
mucosa and acquire all the characters of the adult. Copulation then 
takes place, the eggs are deposited, and a new generation repeats the cycle. 

Symptoms. — The symptoms brought about by the presence of these 
worms — a condition generally known under the name of sclerostomiasis — 
are not characteristic and vary according to the location of the parasites. 
The presence of the adults upon the mucosa of the cecum, even in con- 
siderable numbers, rarely .causes serious disturbance, diarrhea and 
occasional attacks of colic resulting in exceptional cases. 

Sclerostomiasis produced by the larvae is of a much more serious 
nature. Their most frequent location in this state is in the large arteries 
where they bring about the formation of verminous aneurysms, usually 
at the origin of the great mesenteric. Fragments of the clot within the 
aneurysm may be carried by the blood to form emboli in the arterial 
ramifications leading to the intestines, that portion of the intestine 
supplied by an artery in which an embolus is lodged being deprived of its 
normal supply of blood. As a result there is suspension of secretion and 
peristaltic movements in this section, the walls of a portion of which 
become dark and tumified with the presence of hemorrhagic infarct. 
One or more portions of the intestine may be thus affected, the arrested 
contents fermenting and producing an abundance of gas, while in the 
healthy portions of the intestines there are abnormally energetic con- 
tractions which cause a severe enteralgia and may lead to invagination, 
displacement, and even rupture. The rupture may be of the paralyzed 
intestine, or it may be of the stomach or diaphragm, brought about by 
the accumulation of gas generated from the stagnated and fermenting 
intestinal contents, the violent movements of the animal often con- 
tributing toward this termination. 

Post-mortem Appearance. — The adult worms are fixed to the 
mucosa, usually that of the cecum, where they nourish fi-om the blood of 
their host and produce at their point of attachment a small dark prom- 
inence. Immature worms may be found in submucous nodules of the 
cecum, or of both the cecum and colon. These nodules vary in size from 
that of a pinhead to that of a hazelnut and contain a small quantity of 
pus or sero-purulent material in which the worm, if present, is rolled up. 
The worms escape from the nodules by a central orifice to the lumen of 



STRONGYLIN^ 291 

the intestine where they attach and are sexually mature, the sexes often 
being found coupled in this location. Before their intranodular existence 
the larval worms live in the blood-vascular system, having gained this 
location through the intestinal wall innnediately after their ingestion. 
It is at this stage that they produce the aneurysms as found in the vis- 
ceral trunks of the posterior aorta. These aneurysms are usually some- 
what elongate, with tunica media much thickened, and with fibrin 
deposit upon the iiitima, on which a number of reddish tinted strongyls 
are likely to be fixed. The aneurysm may, however, be entirely free 
from worms, in which case they have probably passed with the blood- 
current to the intestinal wall. 

Where death has occurred from thrombo-embolic colic due to ver- 
minous aneurysm, the most prominent alterations found are those which 
have already been described in reference to this complication. The 
intestines are usuallj' much distended bj^ gas, or, if rupture has occurred, 
this, with more or less intestinal contents, will be in the abdominal 
cavity. Extensive darkly discolored areas are usually observed in the 
intestinal walls, and there are likely to be evidences of degeneration if 
the course of the attack has been sufficiently prolonged. Owing to the 
great engorgment of the mesenteric vessels, it is often difficult, without 
the most searching examination, to discover the location of the embolus. 
Rarely the immediate cause of death may be found to have been due to 
rupture of the aneurysm and internal hemorrhage. 

Treatment. — For the strongyles in the intestine the same treatment 
may be employed as has been reconnncnded for the ascarids, though, 
owing to the firm attachment of the former to the mucosa, their expul- 
sion is difficult. Oil of turpentine has been recommended as particu- 
larly valuable. It may be given in two to four ounce doses in oil. 

In prophylaxis clean water is a main factor. This should be filtered or 
quite pure and free from drainage contamination. , ^^ 



Strongylosis of the Intestine of the Dog and Cat. 
Ankylostomiasis 

1. Ankylostoma canina (Dochmius trigonocephalus; Uncinaria tri- 
gonocephala; U. canina). Fig. 156. 8trongylinae (p. 280). — The body 
is whitish in color and slender; slightly enlarged at the anterior extremity. 
On the ventral surface of the buccal capsule are two chitinous plates, 
each having three recurving teeth. The bursa of the male is three-lobed, 
two large lateral and a small median. There are two long and slender 
spicules. The vulva of the female is situated near the posterior third 
of the body. 

The female is 10-20 mm. (3/8-3 4 of an inch) in length; male, 9-12 
mm. (11/32-1/2 an inch). 



292 PARASITES OF THE DOMESTIC ANIMALS 

The eggs are oval, 74-84 microns in length bj^ 48-54 microns in 
breadth. 

Parasitic in the small intestine of the clog and cat. 

2. Uncinaria stenocephala (Dochmius stenocephalus ; Ankylosto- 
mum stenocephalum) . Strongylinse (p. 280). — The body is very 
slender, and the anterior extremit}'- is much narrower than in the pre- 
ceding species, being somewhat attenuated. The buccal 
capsule is conical and has two pairs of small teeth on the 
ventral side. The bursa of the male is similar to that of the 
preceding species. The vulva of the female is situated near 
y the posterior third of the body. 

Fig. 156— The female is 8-10 mm. (5/16-3/8 of an inch) in length; 
Ankylostoma male, 6-8 mm. (1/4-5/16 of an inch). 

malJ'atHght, ^^^ ^^gs are oval, 63-76 microns in length by 32-38 
female at left microns in breadth. 

(drawn from Parasitic in the small intestine of the dog. There is no 
specimens), authentic report of its occurrence in this country. 

Occurrence and Development. — Ankylostomiasis (dochmiasis; un- 
cinariasis) is a severe affection of dogs caused by the presence of Ankylo- 
stoma canina. The condition is analogous to ankylostomiasis or hook- 
worm chsease of man, caused by the species Anktjlostoma duodenale. 

The worms fix themselves to the mucosa of the small intestine where 
they extract blood. Hunting dogs confined in kennels are those which 
most often suffer, especially if their quarters are damp. Cats are not 
often affected. 

The development of the parasite is rapid. The eggs are segmented 
within the body of the female and, when expelled to moist earth, develop 
embryos in three to six days. These become encysted and, probably 
through the medium of contaminated water, reach the intestine of the 
dog where they mature. 

Post-morten Appearance. — Necropsies upon dogs which have died 
in the advanced stages of ankylostomiasis show the alterations of 
anaemia and cachexia. The mucosa of the small intestine is thickened 
and marked by numerous hemorrhagic areas. Small ulcerations are 
present as a result of the irritation from the attachment of the worms, 
and the intestinal contents may be hemorrhagic. 

Symptoms. — The symptoms are those of anaemia, debility, and 
emaciation. There is depression and indifference, and hunting dogs 
lose their zest. The skin becomes dry and scaly and the coat harsh 
and lusterless. The legs swell intermittently at first, later the edema 
is greater in extent and becomes permanent. There is a muco-purulent 
discharge from the nostrils and this may be streaked with blood. Later 
there may be attacks of nasal hemorrhage. There is at first constipation, 
later a dysenteric diarrhea. Emaciation and general debility progress, 



STROXGYLIX.E 



293 



and the SAnnptoms are finalh' terminated bj- death in a state of coma or 
it may be in conAiilsions. 

Treatment. — As the disease usually attacks hunting packs in ken- 
nels, and there is constant reinfection, treatment is, as a rule, not suc- 
cessful. It is most important that care be exercised as to cleanliness of 
the kennel. Where possible, the sick should be removed to other quar- 
ters. Water and food should be given from buckets or troughs which 
are thoroughly flushed out after each meal, and the j-ards should be 
kept free from pools and nmd. As medicinal treatment, the usual 
vermifuges reconunended for dogs may be tried. 

Other Strongylinae. — Two other strongylines occasionalh' found in 
sheep and cattle may be mentioned. 

1. Bunostomum trigonocephalum (Uncinaria cernua; Dochmius 
cernuus). StrongyliniP (p. 280). — Yellowish or reddish in color; 
cuticle transversely striated. The 
buccal capsule has a long dorsal tooth 
projecting forward. The mouth is 
surrounded by six papillae; cephalic 
extremity curved dorsall}-. The 
vulva of the female is near the middle 
of the body. 

The female is 20-28 mm. (3/4-1 1 '8 
inch) in length; male, 15-18 mm. 
(5/8-11/16 of an inch). 

Para.sitic in the small intestine of 
rimiinants, particularh' sheep and 
goats. 

2. Bunostomum phlebotomum 
(Uncinaria radiata; Dochmius radi- 
atus). Fig. 157. Strongylime (p. 
280).— Dark in color. The dorsal 
buccal tooth is short; two ventral 
buccal teeth and two subventral 
buccal teeth or lancets. The cephalic 
extremity is curved. 

The female is 24-28 mm. (15/16-1 1/8 inch) in length; male, 10-16 mm. 
(3/8-5/8 of an inch). 
Parasitic in the small intestine of cattle. 





Fig. 157. — Bunostomum phlebotomum; 
male at right, female at left. * Vulva. 
x5. (After Ransom, Bull. No. 127, Bu- 
reau An. Ind., U. S. Dept. Agr.). 



Teacheal Strongylosis of Chickens. Syngamosis 



Tm-o species of strongylines invade the trachea and bronchi of fowl, — 
Syugamus trachealis and Syn. bronchialis. The last named is somewhat 
the larger and inhabits the air passages of water fowl. 



294 PARASITES OF THE DOMESTIC ANIMALS 

Syngamus. Strongyliiifie (p. 280).^ — Members of this genus have a 
slender bod}' of reddish color. The month is surrounded by a strong 
chitinous capsule. The female is much larger than the male and is 
usually found with the male firmly attached at the vulva which is sit- 
uated near the anterior quarter of the body. This permanent coupling 
gives to the pair a forked appearance from which the worm has derived 
its common name of "forked worm" (Fig. 158). The attachment of 
male and female is less constant with the species Syn. hronchialis. 

The female of Syngamus trachealis is 5-20 mm. (3/16-3/4) of an inch 
in length; male, 2-6 mm. (1/16-1/4 of an inch). 

The eggs are elliptical, measuring 85 microns in length by 50 microns 
in breadth. In the uterus of the female they undergo a variable degree 
of development, containing when freed a segmented mass or 
a developed embryo. The eggs are not laid but escape from 
the body by its rupture, which ordinarily occurs from decom- 
position, though, according to Railliet, eggs contained in 
the vagina may pass through the \ailva and from under the 
bursa of the male to the outside. 

Occurrence and Development. — The condition produced 

Fig. 158. in fowl by syngami is commonly known in England and the 

—Syngamus United States as gapes. It is widely prevalent, practically 

male (at- all of our domestic birds and many wild birds, especially 

tached at those in captivity, suffering from it. 

malef " ^^' ^ peculiar feature in the evolution of Syngamus trachealis 
is the fact already noted that, due to the covering of the 
vulva by the permanent attachment of the male, the eggs cannot be 
extruded and are only liberated by the rupture or disintegration of the 
mother worm. This may occur within the air passages or after the 
worm has been expelled. If the eggs meet with water or moist earth 
the embryos develop and are hatched in seven to forty da3'S according 
to temperature. Birds may become infested by ingesting eggs or em- 
bryos, often by eating the worms expelled by infested members of the 
flock. From the digestive tract the larvse migrate to the air passages 
where they mature. 

Lesions. — The worms are generally found covered with mucus and 
in greatest number near the division of the trachea into bronchi. The 
mucosa, to which they are firmly fixed by their buccal capsule, exhibits 
at each point of attachment a small purulent tumor, or there may have 
developed an abscess sufficiently large to obstruct the trachea. The 
number of coupled worms present may be three or four or twenty to 
thirt}'-, the smaller numbers being quite sufficient to cause death by 
asphyxiation, though this will be influenced somewhat by age and the 
diameter of the trachea. 

Symptoms. — Young birds suffer most from syngamosis, those in 



STRONGYLIX.E 295 

good condition being equally susceptible with others. A typical symp- 
tom of the affection is a peculiar stretching of the neck accompanied 
by a yawn-like opening of the beak from which movement the disease 
derives its name "gapes." The birds repeatedly shake their heads, 
sneeze, and expel tenacious masses of mucus which may contain one 
or more pairs of the worms. The appetite, at first voracious, diminishes, 
and the birds become dull and inactive with feathers erect and lusterless. 

Emaciation progresses, the mouth is filled with frothy saliva, respira- 
tion becomes increasingly difficult, and the animal dies from exhaustion, 
or it raaj' be from asphyxia before such advanced symptoms are reached. 
Recovery is rare in young l)irds. Older ones sometimes survive if the 
infestation is light. 

Treatment. — A method of treatment commonh' practiced is to strip 
a feather of its barbules to within a short distance of its tip and inserting 
this into the trachea with a rotary movement, attempt to detach and 
elevate the worms. Only such worms as are not firmly fixed to the 
mucosa are removed by this process and, in view of the danger of its 
causing suffocation, it is a questiona])le procedure unless as an urgent 
palliative measure. 

A better treatment is to give with the food certain substances of strong 
odor eliminated in the respiratory passages and having a deleterious 
effect upon the parasites. As such agents garlic and asafetida have 
been employed with success. According to Neumann, Megnin has had 
good results with a mixture of equal parts of asafetida and powdered 
gentian root incorporated in a cake and given in the proportion of eight 
grains per bird each day. 

Another method reconnnended is the injection into the trachea of 
about fifteen drops of a five to eight per cent, solution of salicylic acid. 
The injection should be made slowly with a small syringe and canula. 

Fumigations with such agents as sulphurous acid or tobacco smoke, 
resorted to by some, involve such risk of accident from suffocation as 
to make their use unadvisable. 

As prevention, affected birds and those apparently health}- should 
be removed to clean and separate quarters and the infested yards 
cleaned and sprinkled with a one to one thousand solution of sulphuric 
acid. The bodies of dead birds are to be buried deeph' or burned. 
Food and water should be fresh, given from clean utensils, and not per- 
mitted to stand about. As an aid in prevention the addition of fifteen 
grains of salicylate of soda to the quart of drinking water has been 
recommended. 

The Kidney \\'orm of the Hog 

Stephanurus dentatus. StrongyHdse (p. 255). — This worm is at 
present of somewhat uncertain position in the classification of the 



296 PARASITES OF THE DOMESTIC ANIMALS 

strong3des. The body is thick, cyHndrical, and has a mottled appear- 
ance, due to the intestine and reproductive organs showing through 
the semi-transparent integument. Both extremities are somewhat 
blunted; the mouth terminal with six small teeth. The bursa of the male 
is formed of five tongue-like parts united by a membrane; there is but 
one spicule. The obtuse caudal extremity of the female is curved; 
^^ilva near the middle of the body. 

The length of the female is 30-40 mm. (1 3/16-1 9/16 inch); male, 
22-30 mm. (7/8-1 3/16 inch). 

Parasitic in fat surrounding abdominal viscera, especially that of the 
sublumbar region in the vicinitj^ of the kidneys. 

The kidney-worm is found in hogs of the United States — especially 
those of the South — and in South America, the species being first dis- 
covered in Brazil. Its presence may cause the formation of cysts up 
to the size of a pigeon's egg in the adipose tissue, these on incision usually 
revealing one or two of the worms and a small amount of pus. Rarely 
the worms penetrate the capsule of the kidney or enter the suprarenals. 
Indurated fistulous tracts, liver lesions, and peritoneal effusion have 
been observed as a result of the presence of these parasites, though it 
may be said of them that they rarely cause perceptible disturbance 
unless in unusual locations in the abdominal cavity. 

Due to their location, treatment can be of no value. 



FAMILY VL EUSTRONGYLID.E 

EUSTRONGYLOSIS 

This is a condition produced by a giant nematode, — Diocioplujme 
renale (D. visceralis; Eustrongylus visceralis; Eu. gigas), which is some- 
times met with in the kidney and peritoneal cavity of dogs and other 
domestic animals. It has also been reported in man. 

Diodophyme r-enale (Nematoda, p. 217) is of somewhat uncertain 
position among the nematodes. It has been commonly placed with the 
family Strongylidae, but it does not conform to all of the characteristics 
of this family. Neveu-Lemaire describes the genus Eustrongylus under 
the separate family Eustrongylidse. 

The worm is the largest of all the nematodes, the female attaining 
a length of one meter (39 inches) and a thickness of a centimeter (3/8 
of an inch); the males a length of forty centimeters (15 inches). The 
body is blood-red in color, somewhat thinner toward the anterior ex- 
tremity than posteriorly. The bursa of the male is collar-like, entire, 
and without rays. Within its base is located the anus. There is a single 
slender spicule (Fig. 159). The tail of the female is obtuse. There is a 
single ovary; vulva near the mouth. 



EUSTRONGYLID^ 



297 



The eggs are 64-68 microns in length by 40-44 microns in width. 
They are brownish in color and have numerous round depressions on 
their surface. The}^ develop in a moist medium. 

The embryos are tapering at the extremities and about 240 microns 
in length by 40 microns in breadth. They have a 
great vitalitj^ and may survive within the eggs for 
a year or more. 

Attempts at direct infection have been unsuc- 
cessful. An intermediate host is evidently re- 
quired, and the fact that the worm is found para- 
sitic in the seal and otter points to the probability 
that it lives a portion of its life in a fish. 

The eustrongyle is much more frequent in Car- 
nivora, especially the dog, than in other animals, 
but it is rareh' met with. In the Journal of the 
American Veterinary Medical Association, June, 
1917, Hall states that from Riley's and his own 
record of cases reported it appears that this worm 
has been found at least forty or fifty times in the 
United States. How and in what form it finds its 
wa}^ into the body of its host is not known. It is 
most frequentl}^ found in the pelvis of the kidney 
where it grows to an enormous size, producing a 
purulent inflammation from which destruction of 
the renal tissue follows. Eventually the kidney 
becomes a mere thick-walled cyst containing a 
bloody purulent material within which the worm 
is coiled up. But one kidney is invaded, usually- 
by a single worm, though in rare cases two have 
been found in the kidney pelvis. The uninfestcd 
kidney is usually found to have undergone a com- 
pensatory hypertrophy. The worm has been 
met with in other parts of the urinary organs, as 
in a part or the whole of the lu'eter and in the 
bladder. Where it is found outside of the urinary 
organs, as in the peritoneal cavity', it is probable 
that it did not reach such location until after 
primary development in the urinary passages. 

Symptoms. — The symptoms are not characteristic and in some cases 
may not be observed. Horses and cattle especially are said to show 
little disturbance from the presence of the worm, while dogs, on the 
other hand, suffer severe pain, are restless, and sometimes exhibit a 
lateral curvature of the vertebral column, the concavity corresponding 
to the affected side. ^Nlicturation may be painful and with effort, and 




Fig. 1.59.— Diocto- 
phyme renale; male, — 
natural size (after Rail- 
liet). 



298 PARASITES OF THE DOMESTIC ANIMALS 

the urine may be purulent and bloody. An exact diagnosis can only 
be made in the living animal by finding the characteristic eggs of the 
eustrongyle in the urine. 

In view of the location and size of the worm, treatment is imprac- 
ticable. 



chapter xxiv 
xe:\iatoda. family vii. trichixellid.e 

Xematoda (p. 217j. 

The nematodes of this faniil}' have a very slender and elongated 
anterior portion of the body, containing only the esophagus. The pos- 
terior portion is more or less enlarged and is occupied h)y the intestine 
and reproductive organs. The mouth is rounded and nude. The anus 
is terminal or nearly so. The males have a single testis and but one 
spicule or the spicule may be absent. The females have a single ovary. 
The vulva is located at the junction of the smaller with the larger por- 
tion of the bodj'. They are oviparous (Trichuris) or ovoviviparous 
(Trichinella). 

The worms of this group to be described come under two genera, — 
Trichuris and Trichinella. Of those but one species, — Trichinella 
spiralis, is of pathologic importance. 

Trichuris ovis fTrichocephalus affinisj. Fig. IGO. Trichinelhdse 
(p. 299). — The esophageal portion of the body is very long and slender; 
the posterior portion, containing the reproductive organs, much thicker. 
The head is sometimes provided with two transparent wing-like en- 
largements. The posterior extremity is more or less blunt and rounded. 
The body is transversely striated. The posterior portion of the body 
of the male is rolled dorsally in a spiral. The spicule is verj- long, 
measuring 5-7 mm. (7/32-9/32 of an inch) and terminating in a sharp 
point. 

The female is 50-70 mm. (2-2 3/4 inches) in length, the esophageal 
portion constituting about two-thirds of the total length. The male is 
50-80 mm. (2-3 1/8 inches) in length, the esophageal portion in the 
same proportion to the total length as in the female. 

The eggs are lemon-.shaped, 70-80 microns long, and have an opercular 
plug at each end. Development is direct. 

This species is a common para.site in the large intestine of ruminants, 
particularly the sheep and goat. Leuckart has demonstrated that it 
develops directly from the egg without intermediate host and without 
a free hving stage. When the eggs are taken into the intestine of the 
nmiinant host the embr>'OS are freed and attain their adult development 
in about sixteen daj's. They are usually found attached firmly to the 
mucosa, but apparently cause littlo if any trouble. 

Trichuris crenatus ' Trichocephalus crenatus). Trichinellidae (p. 
299). — The esophageal portion of the body is very slender, the posterior 



300 



PARASITES OF THE DOMESTIC ANIMALS 




Fig. Itil. — Trichuris ovis. Egg. 
x600. (After Ransom, Bull. No. 127, 
Bureau An. Ind., U. S. Dept. Agr.). 



Fig. 160, 
at left. * Vulva, xo 
tice, Bull. No. 127, 
Dept. Agr.). 



portion enlarged. The female 
measures 35-50 mm. (1 3/8-2 
inches) in length, the anterior 
slender portion constituting 
about two-thirds of the total 
length. The length of the male 
is 33-40 mm. (1 5/16-1 9/16 
inch), the anterior part about 
five-eighths of the total. 

The eggs are 52-56 microns 
in length. 

The worm lives in the large 
intestine of domestic and wild 
hogs. Infestation occurs as in 
the preceding species. Ap- 
parently little disturbance is 
caused by its presence. 

Trichuris depressiusculus 
( Trichocephalus depressiuscu- 
lus). Trichinellidse (p. 299).— 
The male and female are 45- 
75 mm. (1 3y^4-3 inches) in 
length, the slender esophageal 
portion constituting the ante- 
Trichuris ovis; male at right, female rior three-quarters. The spe- 



(After Ransom, from Cur- 
Bureau An. Ind., U. S. 



cies resembles Trichuris ovis of 
ruminants and Tr. dispar of 
man. The spicule of the male 

may reach the length of 10 mm. (3/8 of an inch) and terminates in a 

sharp point. 

The eggs are 70-80 microns in length. The development is similar 

to that of the preceding species. 

This parasite inhabits the large intestine, usually the cecum, of the 

dog. Eggs taken up by dogs release their embryos within the digestive 

tract where they attain full development. The worms are often found 



TRICHINELLID^ 



301 



in the cecum of clogs suffering from ankylostomiasis, but have an in- 
significant secondary part to Ankylostoma canina as a cause of this 
affection. 

Trichinosis 

Trichinella spiralis (Trichina spiralis). Fig. 162. Trichinelhdse 
(p. 299). — A veiy small worm with bod}' somewhat thicker posteriorly, 
but without abruptly demarcated fila- g 

mentous anterior as in the Trichurinae. 
The mouth is round and unarmed. The 
esophageal portion extends to about one- 
half of the length of the body, the esoph- 
agus embedded in a chain of single cells. 
The portion of the body posterior to the 
esophageal contains the intestine which 
ends in a terminal anus. The single 
testis of the male originates posteriorly- 
and extends forward to the esophagus 
where it turns back and becomes the 
seminal vesicle which terminates at the 
anal aperture. The cloaca thus formed 
has on each side of its opening two pro- 
jections which serve to clasp the female, 
the cloaca being extmded in copulation. 
There is no spicule. The single ovary 
of the female begins posteriorly and, ex- 
tending forward for a short distance, be- 
comes the uterus. The vulva is about 
one-fifth of the length of the body from 
the anterior end. 

The female is 3-4 mm. (1/8-5/32 of an 
inch) in length; male, 1.4-1.6 mm. (1/16 
of an inch). 

The embrs^os are developed within the 
uterus and are hatched there by breaking 
through the delicate membrane sur- 
rounding the egg. From the uterus and 
vagina they pass from the bod}' of the 
mother worm through the vulva. The 
hatched embryos are 100-160 microns 
long by 9 microns thick, the anterior end 
somewhat thicker than the posterior. 

Parasitic as adults in the small intestine and as larvae in the muscula 
ture of hogs, rats, mice, and other mammals, including man. 




Fig. 162. — Trichinella spiralis; 
male at left, female at right, — 
much enlarged. 



30^ 



PARASITES OF THE DOMESTIC AXi:\L\LS 



Life History. — When flesh containing encapsulated living trichinae 
is taken into the stomach of a suitable animal, the capsule is digested 
and they are liberated within eighteen to twenty-four hours. The 
larvae then enter the small intestine and are sexually mature in two to 
five daj-s. The females with the males are pressed into the crypts of 
Lieberkijhn where, a week to ten days after the infection, the female 
deposits living embryos. There is at first an equal number of males 
and females in the intestine; later the males gradually disappear, so 
that ten to fourteen daj's after infection almost all of the worms will be 
females. These live five to eight weeks, a single female, according to 
Leuckart, depositing not less than fifteen hundred embryos; according 
to Braun, the nmnber may reach ten thousand. 

From Lieberktihn's glands the embryos penetrate the mucosa and, 
reaching the lymphatics, are probably carried to the blood by wa}^ of 
the thoracic duct. With the blood they are distributed to various parts 
of the body, passively in greater part, though it is 
probable that their ultimate lodgment is influenced 
somewhat by their activity. Embryos deposited by 
capillary blood in striated muscle with sarcolemma 
are amid conditions favorable to their further develop- 
ment. From the capillaries the trichinae force their 
way through the sarcolemma and into the plasma of 
the muscle-fiber, where, at first actively motile, they 
pass to a state of rest and proceed to develop into 
the larval stage at which, if ingested, they may infect 
other animals. 

In about three weeks after the occurrence of the 
infection the larvae in their muscular location have 
attained a length of eight-tenths to one millimeter, 
and their growth is completed. At this time they 
are usual Ij' curved in the form of a sickle, later becom- 
ing coiled spirally (Fig. 163), from which characteristic 
they derive their specific name, though they may be 
found in various looped and curved forms. The an- 
terior portion of the larva is now the thinner; the pos- 
terior thicker and rounded at its extremity. 
As a result of this invasion the muscle-fibers undergo certain changes; 
the transverse striation is lost, there is degeneration of the sarcoplasm, 
and the nuclei increase in number and size, each becoming surrounded 
by a granular mass. The irritation to the surrounding tissues caused 
by the presence of the parasites results in the formation of cysts which 
enclose the trichinae and are fulh' developed at the end of the thu'd 
month. The long axis of the capsule is parallel to that of the muscle- 
fiber. The capsules are usually oval in shape and more or less drawn 




Fig. 163.— Tri- 
chinella spiralis. 
Encysted larva in 
muscle (after Leuc- 
kart). 



TRICHINELLID^ 303 

out at the i^oles, giving them somewhat the shape of a lemon. Their 
dimensions vaiy with the thickness of their walls. In general, they 
are about four-tenths of a millimeter in length by twenty-five one- 
hundredths of a millimeter in })readth, but their length may be from 
three-tenths to eight-tenths of a millimeter and their breadth from 
two-tenths to four-tenths of a millimeter. After the formation of the 
cysts they are often made more recognizable to the unaided eye by the 
deposition of fat cells innnediately around their poles. Within each 
cyst there is usuallj- one, more rarely two or more, larva?. 

Tabular Review of Life History of Trichinella Spiralis 

Mature Womis. — In intestines of hog, rat, etc. Period of 
I intestinal trichinosis. 

Embrvos. — In intestinal crvpts of same. 

Embryos. — In lymph and blood currents after pene- 

I trating intestinal wall. 

Embryos. — ]\Iigrating within fibers of voluntary mus- 

I cle. Period of muscular trichinosis. 

Encysted Larvae. — ^At rest within voluntary muscle- 

I fibers. 

Larvae. — Freed from C3^sts after ingestion by hog, rat, 

I man, etc. 

Mature Worms. — In intestines of same. 

Degeneration. — After a varj-ing jx'riod of time the trichina cyst 
undergoes fatty and calcareous degeneration. In the first there api)ear 
within the cyst cells small fat granules which rapidly increase in number 
and are soon set free to invade the whole of the C3'st. Later there is a 
deposition of carbonate and phosphate of lime, the calcification involving 
the capsule and the tissues of the trichina, though the latter often es- 
capes the process, and perfectly intact trichinae ma}' be found in cysts 
entirely calcified and opaque. 

Calcification of the capsule begins about the seventh month after in- 
fection and is completed in from fifteen to eighteen months, though ex- 
ceptions give to these periods but a general application. Ostertag 
states that completely calcified trichina capsules were found in two 
hogs nine and twelve months old, and, according to the same author, 
Dammann reported a case in which after eleven years the trichina cap- 
sules were not completely calcified and contained trichina still capable 
of producing experimental trichinosis. 

Location. — Encysted trichinae are found in striated muscle in which 
the fibers have a sarcolemma. Thev are not found in the muscle- 



304 PARASITES OF THE DOMESTIC ANIMALS 

fibers of the heart. Certam muscles are pecuharly liable to invasion 
by the parasites, and these in the order of frequency may be listed as 
follows, — pillars of the diaphragm, muscles of the larynx and tongue, 
abdominal and intercostal muscles, psoas muscles, and muscles of the 
back. They are usually found in greatest number toward the extrem- 
ities of the muscles in the neighborhood of tendons, a fact probabh' to 
be accounted for in the arrest offered by these locations to their migra- 
tions. 

The nmuber of cysts which an infested individual may harbor is 

capable of reaching an enormously high figure. Neumann states that 

Leuckart has counted between twelve hundred and fifteen hundred in a 

gram (15.43 grains) of muscle, while Fielder, 

jJBHIIjjHj according to the same author, estimated the 

^^^^B^^^H number found in the body of a young woman 

^^HflH^^^S as ninety-four million. 

l^^^^^^^^B^ Occurrence. — Adult trichinae are only found 
J^^H^^^^^ in the intestines, especially the upper part of 
^^i^H^^l^J^^JI the small intestine, of mammals and birds which 
^^^ Wm^ have recently- eaten flesh containing the en- 
^ I cysted larva?. In fishes and other cold-blooded 



Fig. 164. — Trichinella vertebrates the trichina cysts are not acted 
spiralis. Cyst in human ^jpon by the digestive canal and thev pass 

muscle (from micropho- . , i • , i , i r^t- l^ • i" 

tograph by Hoedt). through Without change. Ui the animals com- 

monly used for human food only the hog harbors 
muscle trichinae by natural infection, and trichinosis of man is usually 
acquired by eating the trichinosed flesh of this animal. Rats are peculiarly 
susceptible to trichina, and probably one of the most frequent sources 
of the infection of hogs is by eating trichinous rats. Transmission to 
herbivorous animals, as cattle, sheep, and horses, is difficult. After 
experimental feeding of flesh containing the cysts to these animals 
there is usually a development of intestinal trichinae but no muscle 
trichinae. Intestinal trichinae have been experimentalh^ developed in 
birds, but birds do not harbor the encysted larvae. 

Only encysted living larvae are capable of producing trichinosis in 
their suitable hosts. Ingested larvae which are unprotected b}^ a cyst 
are destroyed in the stomach by the direct action of the gastric juice. 

Symptoms in Hogs. — Sj'mptoms of trichinosis by natural infection 
are rarely observed in hogs, though where a considerable quantity of 
the cysts have been ingested it is probable that such s\anptoms follow, 
their true cause being unrecognized. Feeding experiments have shown 
that after massive infestation intestinal trichinosis is manifested by 
the third to the eighth day. There is then depression, loss of appetite, 
grinding of the teeth, and a disposition to remain crouched in the 
bedding or to stand about with back arched and abdomen retracted. 



TRICHIXELLID.E 305 

A persistent diarrhea follows whicli is at first liunp\-, then watery and 
of bad odor. With these symptoms there may also be those of colic. 
In general the symptoms are those of an entero-peritonitis and they 
continue over several weeks during which time the animal may die. 

In from one to two weeks the larvae are penetrating the muscular 
tissue, and muscular trichinosis has set in. The animal now lies upon its 
side, or, if it moves about, it is in a stiff, halting, and painful manner. 
The respiration is superficial, the voice husky, and chewing and swallow- 
ing difficult. 

With the coming to rest and encapsulation of the larvie the animals, 
in most cases, gradually' recover. Where there has been exceptionally 
heavy infestation edema may appear in various parts of the body; 
such a development is usually followed by death. 

Prophylaxis. — IVIost all cases of infection of man with trichina are 
from eating trichinosed pork, the swine usually becoming infected by 
eating the trichinous flesh of other swine or that of affected rats and 
mice. Knowing these facts, prevention is made relatively simple. 
Places where hogs are kept should be freed from rats, and the flesh of 
animals subject to nuiscular trichinosis should not be fed to hogs un- 
less it has been thoroughh- cooked. According to Leuckart, trichinae 
are killed at a temperature between 62° and 70° C. (143°-158° F.). 
These degrees of heat nuist be continued sufficiently to penetrate the 
entire piece of meat, a white or light gray cut surface indicating that the 
cooking has been sufficient. 

Treatment.— Treatment is ineffectual. In the case of such an ex- 
tremely rare occurrence as the early diagnosis of intestinal trichinosis, 
the administration of anthelmintics followed ])y purgatives might be 
of some value, but the deep location of the mature worms in the crypts 
of the mucosa affords them a high degree of protection against such 
agents. 



CHAPTER XXV 

THE THORN-HEADED WORM. THE LEECHES 

Order II. Acanthocephala. Nemathelminthes (p. 216). — Essential 
differences separating this order from the Nematoda are the absence of 
a digestive tube and the possession of a protractile rostrum provided 
with hooks. The body cavity contains a fluid in which are the sexual 
organs. The sexes are separate. 

One species is of suflficient pathologic importance for consideration. 
This is the large intestinal roundworm of the hog, Gigantorhynchus 
hirndinaceus of the family Gigantorhynchidge, more commonly described 
under the name Echinorhynchus gigas. 

Gigantorhynchus hirudinaceus (Echinorhynchus gigas). Fig. 165. 
Acanthocephala (]3. 306). — The body is white, cylindrical, transversely 
wrinkled, and often expanded at several points. The rostrum is almost 
globular, retractile, and has five or six rows of backward-curving hooks 
(Fig. 166). The caudal extremity is somewhat tapering. The males 
are smaller and thinner than the females and have a bell-shaped caudal 
bursa. The caudal extremity of the female is rounded. 

The female is 20-35 cm. (8-13 inches) in length by 4-9 mm. (5/32- 
11/32 of an inch) in breadth. The male is 6-10 cm. (2 3/8-4 inches) in 
length and in breadth 3-5 mm. (1/8-7/32 of an inch). 

The eggs are oblong, measuring 87-100 microns. When developed 
they are surrounded by three envelops. The embryos are formed within 
the body of the female. 

The adult worm is parasitic in the small intestine of the hog; excep- 
tionally it occurs in man. The larva lives encA'sted in the white grub 
of the May-beetle and probably some other invertebrates. 

The eggs of Gigantorhynchus, discharged to the ground with the 
feces of the hog and eaten by the larva of the May-beetle, are hatched 
in the digestive canal, and the embryos, by burrowing through the in- 
testinal wall, find their way into the bod3'-cavity where they become 
encysted. In this state they may continue to live through the larval 
and pupal stages and even after the maturity of the insect. If the hog 
eats the May-beetle in any of these stages containing the cyst, the cyst 
Avail is digested away and the freed larval worm attaches by its cephalic 
hooks to the intestinal mucosa whei'c it attains full development. 

Occurrence, Pathogenesis and Symptoms. — The giant intestinal 
worm of the hog is quite common in the United States, especially so in 



THE THORN-HEADED WORM. THE LEECHES 307 



the southern portion. The miplantation of the worms upon the in- 
testinal wall b}' means of their hooked rostrum causes limited infiam- 
mator}' areas of red or 3'ellowish color. The 
tumifaction of the wall causes the serosa to 
be pushed out in the form of nodules which 
may be of yellowish color and somewhat 
tubercular in appearance. Exceptionally it 
has been observed that the parasite has bored 
through the walls of the intestine and given 
rise to a purulent peritonitis. 

As applies to helminthiasis in general, the 
disturbances which these worms produce will 
be in proportion to their number. Pain may 
be evidenced b}' continual grunting and rest- 
lessness, and there is the general derangement 
of digestion and the unthrift usual to hea\y 
invasion of the intestines by worms. Young 
pigs suffer most and, in these particularh', 
there may be nmscular twitchings and epilep- 
tiform seizures, such s\nuptoms usually l^eing 
followed by death. 

Treatment. — Due to the 
firm attachment of the 
worms, little or nothing can 
be accomplished by treat- 
ment. If this is attempted, 

the same remedies may be used as recommended for the 
ascarids (p. 241). 





Fig. 165. — Gigantorhynchus 
hirudinaceus, — natural size 
(drawn from specimen). 



Class II. Annelida 



Fig. 166. — 
Armed cephalic 
extremity of Gi- 
gantorhynchus hi- 
rudinaceus, — en- 
larged. 



Coelhelminthes (p. 216). — The annulated worms differ 
from those of the class Nemathelminthes in having a 
segmented body cavity with corresponding ringing or 
annulation of the body wall. The earthworm is usually 
taken for type study of the group. 
Order Hirudinea. Annelida (p. 307). — This order includes the 
leeches which differ in many respects from typical annelids. The body 
is flattened doiso-ventrally and lacks the appendages for locomotion 
(setae) characteristic of other forms. Locomotion is accomplished by 
two suckers, one at the posterior end, used only for locomotion and 
attachment, the othei- surrounding the mouth, used for locomotion 
and attachment and also for sucking the food. In moving from place 
to place the head end is thrust forward and attached by the sucker. 
The hind sucker is then released and brought close to the anterior sucker 



308 



PARASITES OF THE DOMESTIC ANIMALS 



by a looping up of the bod}-, the anterior sucker being again advanced 
and the process repeated. They can also swim freely by snake-like 
movements in the water. The body surface i? transverseh' striated, 
gi^dng the appearance of a large number of segments. The striations, 
however, are in excess of the true segmentation representing the somites, 
the primitive segment rings being divided bj^ secondary- striations. 
The alimentary canal has a nmnber of paired sac-like protuberances 
var3'ing in number according to species. When the leech gorges itself 
these sacular pockets are filled with blood upon which the animal maj^ 
live for some time before again feeding. The bod}- cavity is reduced by 
the connective tissue and musculature to a number of tubular sinuses. 

The leeches are hermaphroditic and copulate reciprocal^ (cross 
fertihzation). As in the earthworms, certain of the somites at the time 
of reproduction develop into a clitellum which secretes porous cocoons 
in which the eggs are deposited. 

The leeches to be considered come under one family, the Gnathobdel- 
lidse, which have the pharynx provided with three semicircular chitinous 
plates or jaws, each armed on its free edge 
with numerous teeth. The Rhynchobdellidse 
are without jaws. This family contains species 
which attack fishes and invertebrates and occa- 
sionally water fowl. 

1. Haemopis sanguisuga. The horse leech. 
(Fig. 167). Hirudinea (p. 307).— Dorsally this 
leech is greenish brown or sometimes reddish 
in color; ventrally dark gray, reddish gray, or 
black. Generally the body has four to six longi- 
tudinal rows of closely set dark points which 
may be somewhat indistinct. The body is 
widest in the middle, gradually narrowing an- 
teriorly, and is composed of ninety-five to 
ninety-seven segments. It is rounded dorsally, 
flattened ventrallj^, soft, viscid, and capable of 
great extension and retraction. The oral sucker 
is slightly concave, having at its center the 
mouth which is in the form of a three-rayed 
star (Fig. 167). Each of these ray-like sHts 
permits the passage of a jaw, the teeth of which wound the mucous 
membrane and thus enable the leech to suck blood while it holds on 
by means of the oral sucker. There are ten indistinct eyes located 
anteriorly on the dorsal surface. The \"ulva is a transverse slit located 
five rings behind the male orifice, or between the twenty-ninth and 
thirtieth rings. 

In fecundation two individuals come together l^v their ventral sur- 





FiG. 167. — Haemopis san- 
guisuga. Oral sucker of 
same at right. 



THE THORN-HEADED WORM. THE LEECHES 309 

faces in opposite directions, each having the part of male and female. 
After the cross fertilization is accomplished there forms around the part 
of the body where the sexual organs are located a clitellmn Avhich is a 
sort of girdle secreting the capsules with which the eggs become sur- 
rounded. The leeches then bury themselves in damp ground where the 
eggs are deposited and incubation proceeds, this process occupying 
about twenty-eight days. 

2. Hirudo medicinaiis. The medicinal leech. Hirudinea (p. 307).— 
This species is a little smaller than the horse leech. The dorsal surface 
is darker than the ventral and is usually marked with six longitudinal 
reddish stripes. The ventral surface is usually olive green and may 
be more or less spotted. 

This leech was once extensively employed in medical practice for the 
abstraction of blood. 

All of the domesticated animals and man are attacked by Haemopis, 
probably the horse most frequently. The leeches live in ponds and 
springs where the animals are likety to drink and are conveyed to the 
mouth with the water. Those taken up are usually the young ones, 
these keeping near the surface of the water, while the adults usually 
lie in the mud at the bottom. Having thus gained access to the nmcous 
membranes, they fix upon the lips, cheeks, pharjmx, or other parts of 
the mouth. They may enter the nasal cavities through the nostrils 
direct, or they may attach to the eyelids. While holding fast in these 
positions by their oral and caudal suckers, the leeches lacerate the 
mucous membrane with their cutting jaws and become gorged with 
blood. They then detach and pass from their host, or they may attach 
to another part of the mucous membrane and renew their feeding. 

The effect of the infestation will depend upon the number of leeches 
present, and this is extremely variable. It is estimated that a single 
leech when engorged will hold about eight cubic centimeters (two drams) 
of blood. The host suffers an additional loss from the fact that there is 
considerable hemorrhage from the wounds after the engorged leeches 
have become detached. Heavy invasions, therefore, are capable of 
bringing about considerable depletion with evidences of anaemia, as 
paleness of visible mucous membranes, edemas, and emaciation. A 
fatal asphyxia may develop from edema of the pharynx which may be 
contributed to by the mechanical obstruction offered by the leeches in 
this location. 

Treatment. — AVhere exploration of the mouth or nasal passages 
reveals the presence of leeches, those which are accessible may be re- 
moved by forceps or with the hand wrapped in a towel. Vinegar, or a 
strong solution of common salt repeatedly applied with a view to causing 
them to release their hold, is recommended by some, but the effective- 
ness of such treatment can only apply to the leeches with which the liquid 



310 PARASITES OF THE DOMESTIC ANIMALS 

comes in contact, many of which maj'^ be so far back in the passages as 
not to be reached. 

A method which is probably better than the syringe in the appHca- 
tion of this treatment consists in firmly attaching a small sponge to 
the end of a probe, such as a piece of rigid rubber tubing. The sponge 
is saturated with salt solution and, preferably with the use of a mouth 
speculum, passed back over the soft palate and pharynx. In the same 
manner it may be apphed deeply into the nasal passages, the tube being 
inserted slowly and with a rotary movement. 



n 



PART III 
THE PATHOGENIC PROTOZOA 

CHAPTER XXVI 

PHYLUM IV. PROTOZOA 

This division includes the most primitive organisms belonging to the 
animal kingdom. While some can be detected b.y sharp eyes as tiny 
swinmiing specks, most all are so small that they can only be seen with 
the aid of the microscope. The individual animal is constituted by a 
single cell, which, with a difference in development, characteristicall}^ 
distinguishes the Protozoa from other animal groups. In most cases 
they live independently of each other, but not rarely a number are 
associated in colonies. Each individual in such a colony is, as a rule, 
physiologically complete, that is, performing within itself all of the 
functions necessary to its life and reproduction. The colonization, 
however, tends to a degree of differentiation and interdependence, and 
in certain cases there are morphological and physiological differences 
among the individuals so grouped, these usually being related primarily 
to the functions of nutrition and reproduction. 

The protozoan colony may be said to differ from the metazoan in that 
each cell of the colony represents an animal which may live unassociated 
with other cells, while in the metazoan the individual is comprised l\v 
the aggregation of cells among which there is a morphological differentia- 
tion corresponding to special functions which are distributed among 
adaptively specialized cell-groups; the bod\'-cells are not capable of free 
existence and they can only live as integral parts of the metazoan. 
The Protozoa being single-celled animals, there is a further fundamental 
difference in their development, since it essentially follows that there is 
no formation of germ layers as occurs in all Metazoa. The division or 
budding of the protozoan cell results directlj' in a new generation and 
not in the development of germinal tissue layers, though the new cells 
may remain aggregated to form a colony. 

While the Protozoa are referred to as the most simple rejiresentatives 
of the animal kingdom, they present, nevertheless, considerable differ- 
ences in form and modification of the cytoplasm, the functions of mo- 
tion, alimentation, excretion, and reproduction being performed by a 



312 PARASITES OF THE DOMESTIC ANIMALS 

much greater specialization in some than in others. While a nucleus is 
not easily demonstrable in certain of the Protozoa, most have one or 
more distinct nuclei, in this, as in other respects, possessing the essential 
parts of a typical cell. 

Ameba. — A simple representative of the Protozoa is the Ameba 
(Fig. 168) which may be found in .most any still water, most readily in 
the ooze ujion the bottom or adhering to leaves or other submerged 




Fig. 168. — -Ameba proteus (after Crawley, from Doflein; Cir. 
No. 194, Bureau An. Ind., U. S. Dept. Agr.). 

objects. Search of such material under the low power of the microscope 
will reveal this organism as a minute protoplasmic particle which slowly 
changes its shape and location by a peculiar flowing and extension of 
the cytoplasm at one or more points, forming irregular, often finger-like, 
projections, — the pseudopodia. These may be withdrawn or the whole 
substance of the animal may appear to flow into one of the projections; 
by this manner of locomotion it may slowly pass out of the microscopic 
field. Close study of the organism will reveal two distinct regions, an 
outer hyaline, — the ectoplasm (ectosarc), and a central more granular 
and less transparent part, — the endoplasm (endosarc) . Within the latter 
may be seen the food vacuoles which are rounded or oval, of varying 



PROTOZOA 313 

size, and inclose granules of food material. At intervals clear globules 
may be seen to gradually form within the cytoplasm and then suddenly 
contract and disappear. These are the contractile vacuoles which on 
contracting empty their fluid contents to the exterior. They are rudi- 
mentary cell organs for the elimination of injurious substances and differ 
from the food vacuoles in having a definite place in the cell as well as in 
their approximately constant number. Young amebae usually have 
within the endoplasm a single nucleus but they may early become 
multinucleate. All of the vital functions appear to be under the con- 
trol of the nucleus; experimental removal of the nuclei has shown that 
Protozoa thus treated cannot properly perform their functions and soon 
perish. 

In feeding the ameba merel}^ flows around the ol)jcct which it is to 
use as food; becoming thus inclosed in the cj'toplasni the nutritive 
elements are digested and assimilated. Circulation is limited to the 
streaming movements of the cj'toplasm, and respiration is carried on by 
absorption of oxygen from the surrounding water. 

Reproduction in ameba is by fission or budding. Before division of 
the cell changes occur in the nucleus involving a separation of the 
nuclear parts with the formation of two distinct nuclei. These separate 
and during the process the cell constricts, finally dividing completely 
with each part inclosing one of the new nuclei. In some cases the cell 
becomes spherical and secretes a protecting mem])rane around itself 
before division; the outer membrane becomes hard and adapted to re- 
sist drying and extremes of temperature, the organism assuming in this 
condition a resting or encysted stage. Encysted individuals usually 
divide into more than two; there may be four, eight, or even hundreds 
of small amebae resulting from the reproductive process. In multi- 
nucleate forms it frequenth' happens that the division is into as many 
parts as there are nuclei. 

Parasitism of the Protozoa 

In 1881 Laveran, a phj'sician in the French army, distinctively 
directed attention to the Protozoa as a cause of disease in animals by 
his discovery that the cause of malaria in man is a protozoan which, 
entering the red blood cells, destro^vs them and in this way causes the 
anaemia characteristic of the disease. Later it was demonstrated that 
this malarial organism is transmitted b}^ a mosquito and that this is the 
only way that the disease can be acquired. This discovery served to 
indicate lines of research looking to insects and other arthropods as 
essential carriers of other forms of pathogenic Protozoa, in which field 
much has already been accomplished. 

Theobald Smith, in 1892, found that Texas fever of cattle is caused 



314 PARASITES OF THE DOMESTIC ANIMALS 

by a protozoan which, though not identical with it, is allied to the 
malarial parasite, and, like it, enters and destroys the red blood cells. 
In this case the infecting organism has been found to be conveyed from 
animal to animal by a certain species of tick {Margaropus annulatus, 
p. 144), and it is now known that the presence of the tick is essential to 
such transmission. 

Trypanosomes were first studied in mammahan blood by Lewis in 
1877, who observed them in the blood of a rat. Three years later 
Trypanosoma evansi was studied as the cause of surra, a disease of horses 
of Asiatic countries, the transmitting agent of which is thought to be a 
blood sucking fly (Tabanus, p. 332). 

Bruce, in 1894, demonstrated that a trypanosome {Trypanosoma 
hrucei) was the specific organism causing the fatal nagana or tsetse 
fly disease of horses and other domestic animals of Africa. He showed 
conclusively that blood-sucking invertebrates, mainly the tsetse flies 
(Glossina, p. 44), are responsible for its transmission from the blood of 
wild immune to the blood of susceptible domesticated animals. 

The relationship of the tsetse fly to human trypanosomiasis was shown 
in much the same way as that followed in the researches of Bruce. 
African sleeping sickness of man was originally confined to the West 
Coast; it has spread eastward and is now a serious menace to the develop- 
ment of Central Africa. In 1902 the infecting organism of this fatal 
disease was discovered to be a trypanosome {Trypanosoma gambiense) 
carried from host to host mainly by a tsetse fly. Students of protozool- 
ogy have since shown that mosquitoes, lice, and leeches may carry 
trypanosomes, and that piercing flies, therefore, may not alone be 
responsible for the spread of the diseases which are caused by these 
Protozoa. 

The instances above cited will serve to direct attention to the im- 
portance of the Protozoa from the viewpoint of their pathogenicity both 
in its economic relation and as regards disease in man. Up to the present 
time the Protozoa as disease-producing organisms have not received 
the attention in the United States that has been given them by inves- 
tigators in Africa and Europe. This is probably due to the fact that, 
though this country is not free from pathogenic trypanosomes, it has 
thus far escaped the ravages of the trypanosomiases of Africa, Asia, 
and South America, to which countries sleeping sickness, kala-azar 
(leishmaniasis), nagana, surra, and mal de caderas have to the present 
time confined their plague. A sHght acquaintance with the subject, 
however, is sufficient to dispel a feeling of security based upon the 
erroneous impression that these diseases are restricted to tropical 
countries or that their spread depends upon the presence of a certain 
kind of fly. It has already been noted that the African trypanosomiases 
may not depend wholly upon the tsetse flies for their existence and 



PROTOZOA 315 

spread; surra and mal de caderas certainly do not, as these are diseases 
of Asia and South America respectively, and tsetse flies are not found in 
either of these countries. There is, in fact, no reason to doubt that any 
blood-sucking fly can transmit trypanosomes from the blood of one 
host to that of another. In view of this the horse and stable flies, so 
common in North America, would, in the presence of trypanosomiasis, 
amply supply the means for its sprej^d. 

In recent years important advances have been made in the study 
of the role of arthropods in the spread of disease. Common knowledge 
as to its powers for carrying bacterial infection has condemned the 
fly to the swat, but it is as essential hosts, and not as purely mechanical 
carriers, that these invertebrates furnish the greatest field for research. 
Much has already been accomphshed in working out the life histories 
of the parasites of insects and ticks, including parasites which have no 
api^arent connection with diseases of higher animals, for these, po- 
tentialh' at least, may not be so harmless to higher animals as may at 
first appear. Change of habitat, as from one part of the body to another 
in the same host, or from a host of one species to that of another, fre- 
quently leads to great alteration in the mode of life of an organism 
which, relatively harmless in the insect, may in the vertebrate evolute 
into more harmful parasitism with the development of pathogenicity'. 
The newer a parasite is to the animal harboring it, the less it is in har- 
mony with its environment. Protozoa which produce acute forms of 
disease have less adaptation to their environment than those producing 
a chronic type of malady. This discord between parasite and host is 
manifested by acute disturbances which maj' result in the death of the 
infected animal. Such parasitic diseases of a chronic course are usually 
correlated with a greater degree of adaptation of the parasite to its 
host and also with acquired resisting powers of the host to the specific 
action of the parasite. 

The scale of evolution through the saprophytic, parasitic, and patho- 
genic is thus exhibited by certain groups. The Spirochetida, long, 
delicate Protozoa with a corkscrew-formed body, may be found as in- 
habitants of the body-cavities, of normal mucous surfaces, of inflamed 
mucous surfaces, as parasites which have penetrated the tissue, and as 
blood parasites. This series is sufficient to show how parasitism may 
evolute by various gradations from harmless commensalism to distinct 
parasitism and pathogenicity, ^^^len the habit of living in inflamed or 
ulcerated tissues is reached the power of penetrating healthy tissues 
soon follows which, with the multiplication of the spirochetes in such 
situations, causes destruction of invaded tissue and local disturbances. 
The products of this tissue destruction, together with those coming from 
the dead bodies of the parasites, form toxins which, getting into the 
blood, produce the general toxemic symptoms. The final stage of 



316 PARASITES OF THE DOMESTIC ANIMALS 

malignant parasitism is reached when the spirochetes acquire the habit 
of Uving in the blood. In this case it is evident that, except under cer- 
tain conditions of contact, the transfer from host to host cannot be direct, 
but that the intervention of an intermediate host is necessary. This must 
be a blood-sucking invertebrate, and, in certain known cases of spiroche- 
tosis of domestic animals, has been found to be a tick, as the tick Argas 
miniatus, the carrier of Spirocheta galUnarum which causes a spiroche- 
tosis in fowls, and the cattle tick Boophilus decolomtiis, the inter- 
mediate host of Spirocheta theileri, the cause of a disease among South 
American cattle. 

The malaria parasites afford stud}- in the evolution of pathogenicity 
of other Protozoa. These organisms indicate in their morphology' and 
development that they are closely allied to the Coccidia, which are 
protozoan cell parasites attacking and entering tissue cells, especially 
epithelimii, of arthropods and vertebrates. There is little doubt that 
the malaria parasites were originall}' Coccidia of insects that, with 
change of hal3itat, developed increased pathogenicity toward the new 
host. 

Granting this, we have, then, in the malaria parasites an example 
of the evolution of disease m the past, while disease in the making is 
evidenced to-day more especiall}' in the case of certain parasitic flag- 
ellates of the genus Herpetomonas. 

The introduction of herpetomads into vertebrates by the latter 
swallowing infected insects, or b}' the wa}' of wounds of the skin, has 
been shown to result in pathogenic effects in the vertebrate host. A 
series of experiments extending over some six years (Fantham and 
Porter, Journal of Parasitology, June, 1916) have shown that certain 
herpetomads normally parasitic in insects, when introduced into ver- 
tebrates will produce a condition resembling kala-azar, an infectious 
disease of man common in certain regions of India, China, and countries 
bordering on the Mediterranean, caused by the herpetomad Leishmania 
(Herpetomonas) donovani. The sjinptoms developed and the mor- 
phology of the parasite found in the vertebrate host show that here at 
least are examples of kala-azar in process of evolution. 

Plate III. — Evolution- of the Parasite of Kala-Azar. Figs. 1 to 5. Parasites of 
kala-azar. 1. Isolated parasites of different forms in the spleen and liver. 2. Di%asion 
forms from liver and bone marrow. 3. Mononuclear spleen cells containing the parasites. 
4. Groups of parasites. 5. Phagocjiiosis of a parasite by a polynuclear leucocyte. Figs. 
(3 to 15. Parasites from cultures. 6. First changes in the parasites. The protoplasm has 
increased in bulk and the nucleus has become larger. 7. Further increase in size. Vacuoli- 
zation of the protoplasm. S. Di%-ision of the enlarged parasite. 9. Evolution of the 
flagella. 10. Small piriform parasite showing flagellum. 11. Further development and 
division of the parasite. 12. Flagellated trj-panosome-like form. 13, 14. Flagellated 
forms dividing by a splitting-off of a portion of the protoplasm. 15. Narrow flagellated 
parasites which have arisen by the type of division shown in Figs. 13 and 14. (After Craw- 
ley, from Mense's "Handbuch," after Leishman, Cir. Xo. 194. Bu. An. Ind., U. S. Dept. 
Agr.). 



^ f% ^ 



? i % ^ I 



2 






• f 






''^' ® • Ik 







318 PARASITES OF THE DOMESTIC ANIMALS 

A brief review of these conclusions, drawn from the results of ex- 
perimental research, will be sufficient to direct attention, not only to 
the powers which insects have as carriers of disease, but to their poten- 
tial powers in the making of disease as well. 

Methods of Reproduction. — Sexual and asexual methods of repro- 
duction alternate in free forms of Protozoa, but the asexual method is 
usually limited to simple division or budding. Parasitic forms, on the 
other hand, have acquired a more prolific means of multiplication, the 
simple division and budding being replaced by asexual spore formation 
as exemplified among the Sporozoa. In the parasitic Protozoa, there- 
fore, two kinds of spores may be present, the one occurring asexually 
during the vegetative life in the host and giving rise to auto-infection 
in the same host, the other sexual, occurring at the end of the vegetative 
life of the parasite, preparing its germs to withstand the unfavoral^le 
conditions of an external environment, and giving rise to infection of 
new hosts. 

The asexual method of multiplication, taking place during the veg- 
etative life in the host, is termed schizogony or schizogenesis, while the 
term sporogony or sporogenesis has been given to reproduction by the 
sexual method. The first is sometimes referred to as the multiplicative, 
the second as the propagative cycle. 

Life History of the Malaria Organisms. — AVith a view to an ele- 
mental conception of these reproductive and infective processes in the 
Sporozoa, the life history of the organisms producing malaria in man 
affords a clear example for stud3^ 

Malaria was the first of the human diseases in which it was proved 
that a protozoan is the direct cause, and by 1901 the disease was as 
thoroughly understood as perhaps any other due to a germ. The malaria 
parasites belong with the genus Plasmodium, so named from their early 
supposed resemblance to some of the plasmodia-forming fungi. They 
are usually considered under three forms with which three well-marked 
types of malaria are associated. These may be briefly summarized as 
follows : 

1. Plasmodium vivax. — Cause of tertian fever; paroxysms occur every 
forty-eight hours; incubation period about two weeks. Temperate cli- 
mates, also in tropics and subtropics. 

2. Plasmodium falciparum (P. prcecox). — Cause of estivo-autumnal 
fever; paroxysms every twenty-four hours; incubation period usually 
from ten to twelve days. Tropics and subtropics. 

3. Plasmodium malarice. — Cause of quartan fever; paroxysms every 
seventy-two hours; incubation period about three weeks. Tropics and 
subtropics. 

Two distinct cycles are involved in the life history of the malaria 
organisms. The first takes place in the blood of the human patient and 



PROTOZOA 319 

is known as the asexual or schizogonic cycle, during which the plasmodia 
niultipty by the asexual method or schizogony. The second occurs in 
the body of a mosquito and is the sexual or sporogonic cycle, involving 
reproduction b}' the sexual method or sporogony. A third phase is to 
be recognized during which the female gametocj'tes sporulate without 
fertilization. This is referred to as the parthenogenetic cycle. It is' 
passed within the body of the human host and explains the recurrence 
of malaria after more or less prolonged periods of latency. 

The Schizogonic or Asexual Cycle. — The asexual cycle begins with 
the infection of the human })lood with the sporozoites by the bite of a 
mosquito of the genus Anopheles (p. 26). The sporozoite is spindle- 
shaped and on entering the blood at once penetrates a red corpuscle 
where it takes a ring-like form, referred to as the signet ring stage, Liv- 
ing at the expense of the corpuscle, the organism grows rapidly until it 
more or less fills the corpuscle. At this stage it is known as the schizont, 
which is the period of its ameboid movement and highest vegetative ac- 
tivity. As the schizont matures its nucleus breaks up into a number of 
daughter nuclei, each becoming surrounded by a spherical portion of 
protoplasm to form a small reproductive element. — the merozoite, or 
asexually formed spore. Finally the corpuscle is broken down and the 
swarm of merozoites is liberated in the ])lood-plasma. Coming from the 
same original brood, the parasites all sporulate and become liberated in 
the blood at the same time; this results in the constantly increasing 
number of merozoites l)eing li))erated at stated intervals with corre- 
sponding intervals of paroxysm in the host. The general toxic effect 
upon the malaria patient is contributed to by the accumulated waste 
products of the parasite's metabolism which pass into the plasma with 
the liberation of the merozoites. Each liberated merozoite now enters 
another corpuscle, and the asexual cycle is repeated in from twenty- 
four to seventy-two hours according to the species of the infecting or- 
ganism. 

This process of multiplication may continue for an indefinite tune 
or, by analogy with other parasitic Protozoa, until the vitality is ex- 
hausted. Asexual merozoites are greatly in the majority, but certain of 
them are potentially sexual and i-equire a longer time to fully develop 
into males and females when they are known as male and female game- 
tocytes. Up to this time they are still intracorpuscular and, in the 
estivo-autumnal or pernicious type of fever, appear as large crescents. 
The female crescent (macrogametocyte) has numerous pigment gran- 
ules collected in the center; the male (microgametocyte) is the mother 
cell of the male reproductive elements (microgametcs). The nucleus 
of the male cell divides into a number of daughter nuclei which migrate 
to the periphery and become the nuclei of the flagelliform microgametes. 
These bodies are constantlv in the l)lood after the first few paroxysms. 



320 PARASITES OF THE DOMESTIC ANIMALS 

If the blood is now di-awn by an anopheline mosquito further changes 
take place-. 

The Sporogonic or Sexual Cycle. — In the intestine of the mosquito 
the female gametocyte undergoes certain nuclear changes preparatory 
to fertilization; the cell becomes rounded or oval in form, and is now 
known as the macrogamete. From the male gametocyte there are ex- 
truded from three to six fiagelliform filaments corresponding in number 
to the peripheralh' disposed daughter nuclei. These filaments detach 
from the mother cell to become the actively motile microgametes, which 
are analogous to the spermatozoa of higher animals. Thus the flag- 
ellated parent body maj' be referred to as a microgametoblast; produc- 
ing the male sexual elements or microgametes. 

Fertilization of the macrogamete is brought about by its penetration 
by one of the microgametes. The fertihzed macrogamete now becomes 
the ookinete or zj-gote, in which stage it passes by a vermiform move- 
ment into and through the epithelium of the mosquitoe's mid-intestine 
and comes to rest just beneath the outer lining membrane. Here it 
rapidly grows, the nucleus divides, and by the third to the fifth day it has 
formed a cyst in which there are many nuclei, each to become the nucleus 
of a minute body, — the sporoblast. The sporoblasts, by division, form a 
number of germs, — the sporozoites, spindle-shaped, nucleated bodies 
which are mature after a period of ten to fourteen days in the body of 
the mosquito. On reaching maturity, the sporozoites are liberated into 
the body cavity of the insect where they are carried about b}^ the body 
fluids, collecting eventual^ in the salivary glands. From here they 
pass to the piercing proboscis from which, with the next bite of the mos- 
quito, many may pass into the blood of another human victim to begin 
the asexual cvcle. 



Plate IV.^ — Life Cycle of the Malaria Parasite. 1. Free sporozoite, either in 
salivary glands of the mosquito or in blood of man. 2. Penetration of the sporozoite into a 
red blood corpuscle. 3 to 6. Growth of trophozoite. 7, 8. Division of trophozoite which 
brings about destruction of the blood corpuscle and the release of the merozoites in the 
blood stream. The free merozoites then enter new blood corpuscles, and this cycle may 
be repeated many times. Finally, however, the sexual cj'cle is initiated as follows: 9a to 
12a. Growth and differentiation of female cell. 9b to 12b. Growth and differentiation of 
male cell. 1.3a, 13b. The male and female cells are swallowed by a mosquito. 14a. Matu- 
ration of female cell. 14b. Formation of microgametes. 15b. Free microgamete. 16. 
Fertilization. 17. Ookinete. 18, 19, 20. The ookinete attacks and penetrates a cell of 
the intestine of the mosquito, and passes completely through the epithelium, coming to 
rest in the peri-intestinal tissue. (There is not, in life, the reduction in size indicated by 
the figure.) 21 to 25. Stages in the development of the cyst and formation of the sporozo- 
ites. 26. Migration of the sporozoites. 27. Sporozoites in the salivary glands of the 
mosquito. 13c to 17c. These figures portray the cycle which is supposed to account for 
cases where malaria is latent for a longer or shorter period. Ordinarily, unless removed Ijy 
a mosquito, the differentiated male and female cells (12a and 12b) die, but under certain 
conditions the latter may continue to live in the blood, to give rise to a renewal of the 
disease. (After Crawley, from Mense's "Handbuch," after Grassi and Schaudinn, Cir. 
No. 194, Bu. An. Ind., U. S. Dept. Agr.). 



3^22 PARASITES OF THE DOINIESTIC ANIMALS 

In the parthenogenetic phase, which occurs in the human host, the 
female gametocyte sporulates without fertiHzation. After months of 
latency these spores may pass into the blood current and enter the 
corpuscles, bringing about a recurrence of malaria after its apparent 
cure. 

It should be noted in the sexual cycle that the formation of the spo- 
roblasts is similar to the formation of corresponding reproductive cen- 
ters of the Coccidia, which pass a portion of their cj^cle external to a host 
and which are elsewhere referred to (p. 337). The sporoblasts of the Plas- 
modia, however, differ from those of the Coccidia in having no protect- 
ing membrane or capusle, in the absence of which protection, the spo- 
rozoites are unfitted for existence outside the body of a host animal. 

Classification. — Accorchng to their mode of life, Calkins divides the 
parasitic Protozoa into the following groups. The arrangement is not 
a natural one and is merely for descriptive purposes: 

1. Enterozoic. — Living in the lumen of the digestive tract. 

2. Coelozoic- — Living in the coelomic cavities of the body. 

3. Cytozoic. — Living throughout the vegetative period as intracel- 
lular parasites. 

4. Caryozoic. — Passing into the cell to find lodgment in the cell nu- 
cleus. 

5. Hematozoic. — Living in the blood plasma. 

In some cases the parasite may pass through a number of these modes 
of life. Thus the plasmodia of malaria are hematozoic in the blood 
current, cytozoic in the blood corpuscles, enterozoic in the digestive 
tract of the mosquito, and coelozoic w^hen they pass as sporozoites into 
the body cavit.v of this insect. 

In the arrangement of the classification of the Protozoa which follows, 
only those groups containing species of parasitic importance are given. 

Classification of Paeasites of the Phylum Protozoa 

Phylum IV. Protozoa. P. 311. 
Class A. Phizopoda. P. 324. 
Order 1. Lobosa. P. 324. 
Genus and Species: 

Ameba meleagridis. Host, turkey. P. 325. 
Entameba histolytica. Host, man. P. 326. 
E. coli. Host, man. P. 326. 
Class B. Flagellata. P. 326. 
Order 1. Spirochetida. P. 327. 
Genus and Species: 

Spirocheta gallinarum. Host, fowl. P. 327. 
Order 2. Trypanosomatida. P. 328. 



PROTOZOA 323 

Genus and Species: 

Trypanosoma theileii. Host, cattle. P. 329. 

T. brucei. Hosts, equines, cattle, etc. P. 330. 

T. evansi. Hosts, equines, camel. P. 332. 

T. equinum. Host, equines. P. 332. 

T. equiperdum. Host, equines. P. 333, 

T. americanum. Host, cattle. P. 330. 

Trvpanoplasma. P. 329. 
Class C. Sporozoa. P. 336. 
Order 1. Coccidia. P. 337. 
Genus and Species: 

Eimeria stiedse. Host, rabbit. P. 342. 

Diplospora bigemina. Host, dog. P. 342. 

Coccidium zurni. Host, cattle. P. 343. 

Eimeria avium. Host, chicken. P. 345. 
Order 2. Hemosporidia. P. 347. 
Genus and Species: 

Piroplasma bigeminum. Hosts, cattle, tick. P. 347. 

Plasmodium vivax. Hosts, man, mosquito. P. 318. 

PI. falciparum. Hosts, man, mosquito. P. 318. 

PI. malaria. Hosts, man, mosquito. P. 318. 
Order 3. Sarcosporidia. P. 350. 
Genus and Species: 

Sarcocystis miescheriana. Host, pig. P. 351. 

S. tenella. Host, sheep. P. 351. 

S. blanchardi. Host, cattle. P. 351. 

S. bertrami. Host, equines. P. 351. 



CHAPTER XXVII 

THE PROTOZOAN SUBGROUPS. DISEASES DUE TO 
PROTOZOA 

Class I. Rhizopocla. Protozoa (p. 311). 

The Protozoa of this group lack permanent structures for locomotion 
and nourishment, these functions being performed by the undifferen- 
tiated protoplasm. For this reason they are considered to be the lowest 
in position of the Protozoa. The class name — Rhizopoda — has ref- 
erence to the extension of the cytoplasm in root-like processes or feet, — 
the pseudopodia or false feet. It is in this manner that the anmial flows 
over and engulfs its food, the movements serving for locomotion as well. 
This type of locomotion is known as ameboid, it having been first 
accurately studied in the Ameba. It differs from that of higher Pro- 
tozoa in that it is not accomplished by constant cell organs, as ciha and 
fiagella. A pseudopodium is formed when the cytoplasm streams to a 
point of the body, the process extending more or less beyond the gen- 
eral body surface; the body may then be drawn after it or appear 
to flow into it, the protrusion disappearing and new pseudopodia being 
formed at other points. By repetition of this process a slow change 
in the position of the organism occurs, and if particles of nourish- 
ment are encountered in such wandering they are engulfed by 
the cytoplasm within which they become surrounded by a certain 
amount of liquid, presumably of a digestive nature, to form the food 
vacuole. 

The form of the pseudopodia varies, and this serves as a factor in the 
separation of the rhizopods into different groups. In the Ameba (Fig. 
168) they are thick and finger-like, while in certain other forms they are 
of such delicacy as to appear like fine threads. 

Reproduction in Rhizopoda may be accompanied with the formation 
■of flagellate spores, the ameboid method of motility being exchanged 
for that of the flagellated Protozoa. In this stage the body becomes 
oval and the flagellum develops at the end containing the nucleus, 
where it persists during the spore stage. 

The parasitic Rhizopoda belong with the order Lobosa which is the 
only one considered here. The characteristics of this group have been 
sufficiently referred to in the description of the type genus Ameba 
(p. 312). There are but few parasitic species known, and these are 
included in the two genera Ameba and Entameba. 



THE PROTOZOAN SUBGROUPS 325 

Lnfectious Entero-Hepatitis of Turkeys 

This disease — connnonly known as blackhead — has l^een attributed 
to an organism found by Theobakl Smith in the necrotic Hver of affected 
turkeys and named by him Ameba meleagridis. That this is an ameba, 
however, has been questioned. Certain other investigators consider 
the organism described by Smith as a form in the development of in- 
testinal Coccidia, the acceptance of which conclusion would place the 
disease among the coccidioses. 

The term "blackhead" has been used to designate a numl)er of dis- 
eases of fowls, among which, in addition to entero-hepatitis, are 
cholera, helminthiasis, intestinal coccidiosis, and, in general, any dis- 
ease which may be accompanied by dark discoloration of the comb and 
wattles. 

Symptoms. — It has been shown that entero-hepatitis can be trans- 
mitted directly from diseased to healthy turkeys, natural hifection prob- 
ably taking place through food and water contaminated with the 
droppings from the affected animals. At the expiration of the incuba- 
tion period, which is usually within one month, the disease is initiated 
by loss of appetite and a drooping listlessness which is soon followed 
by diarrhea, the fluid discharge l)eing yellowish in color and of exceed- 
ingly offensive odoi\ Weakness and emaciation have already set in, 
and the comb and wattles show th(> blackish discoloration from which 
the disease takes its name, — blackhead. 

Death usually occurs after a course of from five to eight days. The 
mortality is highest in young animals, among which it is estimated to 
be eighty to ninety per cent. Adults are more likely to recover, though 
usually only after a long period of emaciation duiing which there may 
be a relapse. 

Post-mortem Appearance. — The changes observed on necropsj^ are 
those of necrotic degeneration of the cecal mucosa and liver. The walls 
of the ceca are thickened, the nmcous membrane ulcerated and covered 
with fibrous memljranes and exfoliating necrotic tissue. The liver is 
much enlarged and shows on its surface numerous yellowish areas with 
the centers softened. These areas may be quite small or up to 15 mm. 
(5/8 of an inch) or more in diameter. Other portions of the digestive 
tract are not affected. 

Examination in hanging drop of enuilsified tissue of the cecal mucosa 
and the necrotic foci of the liver will reveal the amebae. The organisms 
found in the liver occur as rounded or oval cells measuiing 6-14 microns 
and having a comparatively small nucleus. Smith concluded from his 
investigations that the parasites were not intracellular but lived in the 
tissue spaces. In the liver they are thought to occupy the spaces of the 
necrosed and disappearing liver cells. 



826 PARASITES OF THE DOMESTIC ANIMALS 

Control. — The sick animals should be at once separated from those 
which are apparenth' not infected and the pens and runs subjected to 
thorough cleaning up and disinfection as recommended in other forms 
of poultry parasitism. It is important that the yards be kept dry and 
that the droppings be promptly removed and so disposed of that thej^ 
cannot be a source of reinfection. 

Treatment is of little value. As paUiative, intestinal antiseptics, as 
eucalyptus or listerine, may be tried. 

Amebic Dysentery in Man. — This is a disease occurring in tropical 
and subtropical, and at times in temperate regions, the cause of which 
is regarded bj' pathologists to be an ameba, — Entamha histolytica. Ar- 
tificial production of amebic dysentery has been brought about in dogs 
and cats by rectal introduction of human feces containing the amebae. 
It has been shown in such cases that the parasites invade the glandular 
crypts of the intestinal mucosa from which they penetrate to the sub- 
mucosa and give rise to a hemorrhagic enteritis. In its further course the 
affection is accompanied by thickening and destructive ulceration of the 
mucosa. 

The diagnosis of amebic dysentery is by demonstration of the ame- 
bae in the stools. They may be differentiated from Entameba coli, an 
intestinal species which is considered to be a harmless commensal, by 
their definite and relatively firm ectoplasm which gives a rigid character 
to the pseudopodia, enabling the parasites to force their way between 
the epithelimn of the crypts and into the more deeply lying tissues. The 
nucleus of E. histolytica varies in shape and position with the activities 
of the cytoplasm; it has little chromatin, and no nuclear membrane is 
apparent. The nucleus of E. coli is usually spherical and shows little 
change in position. 

Class II. Flagellata (Mastigophora) 

Protozoa (p. 311). 

As has been stated, there are certain forms among the Rhizopoda in 
which the pseudopodia disappear from time to time to be replaced by 
one or more flagella; in other cases there maj^ even be permanent fla- 
gella contributing to the pseudopodia in their function of locomotion and 
prehension. Such flagellate rhizopods are transitional to the Flagellata 
and serve to prevent the drawing of a sharp line of demarcation between 
the two groups based upon the possession of flagella. In general it maj^ 
be said of the Flagellata that they are permanently flagellate, the fla- 
gella serving for locomotion and feeding. Thej' exhibit a great diversity 
of form which is to a large extent correlated with the number and loca- 
tion of the flagella. A degree of complexity' is exhibited by some free- 
living forms in the possession of a mouth and cytopharynx. but all par- 



THE PROTOZOAN SUBGROUPS 



327 



asitic forms, and most of those which are free-hving, obtain their nour- 
ishment by absorbtion through the general surface of the body. 

The parasitic flagellates come within two orders. — Spirochetida and 
Trypanosomatida . 

Order I. Spirochetida 

Flagellata (p. 326). 

The spirochetes are of somewhat uncertain position because of in- 
complete knowledge of their flagella and life history. They multiply by 
longitudinal di\'ision, or it may be by transverse division as do bacteria, 
and many wiiters have placed 
them with the latter organisms. 
They range from one to two 
hundred microns in length, and 
the body is filamentous and 
spiral in form (Fig. 169). Deli- 
cate flagella may be present at 
one or both ends. Nuclei can- 
not be distinctly demonstrated ; 
the nuclear material is prob- 
ably distributed as granules 
throughout the protoplasm as 
in bacteria. Motility is exhib- 
ited by rotatory movements, 
and the progression may be in 
either direction. 

Excepting in poultry, the spirochetes are not, so far as known, seriously 
pathogenic in the domestic animals. The extreme pathogenicity of 
certain spirochetes in man, however, indicates the disease-producing 
possibilities of the group and rates it, potentially at least, as a dangerous 
one to all higher animals. 




l-'iu. IG'.).— Spirocheta pallida (after Craw- 
ley, from Doflein, after Sohaudinn, Cir. No. 194; 
Bu. An. Ind., U. S. Dept. Agr.). 



Spirochetosis of Fowls 

This disease was first described Ijy Marchoux and Salimbeni who, 
working in Brazil, noted that special varieties were more susceptible 
and suffered more severely from the attack than common fowls. The 
condition was originalh- termed fowl septicemia, or Brazilian septicemia 
of fowls, and is now considered to be due to the presence of the spirochete 
Spirocheta gallinanim (S. marchoiixi) which lives in the l)lood. is 15-20 
microns in length, and is carried from host to host l)y the tick Arqas 
miniatus. 

The investigators above mentioned distinguish an acute and chronic 
form of the disease, the former characterized by emaciation, drooping. 



3^28 



PARASITES OF THE DOMESTIC ANIMALS 



diarrhea, and anaemia. Toward the end weakness has so far advanced 
that the affected birds are completely helpless and lie with their heads 
upon the ground. Those which survive are said to be immune to fur- 
ther attack. The spiroochete sometimes penetrates the red blood 
cells; it has also been found in the eggs and in the embryonal epithelium 
of the chick. 

It is not known with certainty that the disease exists in this country. 
It is not unlikely, however, that some of the as yet obscure diseases 




Fig. 170. — Hen suffering from acute spirochetosis (after Crawley, from Balfour, Cir. 
No. 194, Bu. An. Ind., U. S. Dept. Agr.). 

of poultry may be found to be due to members of the spirochete group, 
— a sufficient reason for mentioning the Brazilian spirochetosis here. 



Order II. Trypanosomatida 

Flagellata (p. 326). 

A number of classifications have been proposed for these organisms, 
Salmon and Styles placing them in the order Monadida (Moore, 1906). 
Calkins (1909) classifies them as follows: Subphylum Mastigophora; 
class, Zoomastigophora; subclass, Lissoflagellata; order, Trypanosoma- 
tida; typical genera, Tiypanosoma and Trypanoplasma. The same 
author thus describes the order in tabulation: "Organisms of elongate, 
usually pointed form, and of parasitic mode of life; with one or two 
flagella arising from a special "motor" nucleus, and with an undulating 
membrane provided with myonemes running from the kinetonucleus 
to the extremity of the cell; one of the flagella is attached to the edge 



THE PROTOZO.IN SUBGROUPS 329 

of this membrane throughout its length, and may terminate with the 
membrane or be continued beyond the body as a free lash." 

All species of the genus Trypanosoma show a general morphologic 
similarity. In general thej^ may be said to measure from 15-45 microns 
in length, including the flagellum, and 1-5 microns in thickness. As 
typical of the group, T. theileri, living exclusively in the blood of cattle, 
may be taken for brief description. The body is spindle-shaped, more 
or less serpentine, and pointed at the ends, from one of which there pro- 
jects a vibratile flagellum. The flagellum is continued as a marginal 
cord toward the opposite end of the body where it takes origin in a 
minute granule (blepharoplast). In close relation to this granule is a 
deeply staining body which, because of its connection with the motile 
elements of the cell, has been designated the kinetonucleus. Arising 
from the kinetonucleus, the flagellum passes along the body on the 
border of a delicate protoplasmic membrane — the undulating mem- 
brane--toward its free extremity. Centrally located is the tropho- 
nucleus, the nucleus concerned with the vegetative processes of the cell. 
This is clearly defined and usualh' has the chromatin in the form of 
granules of definite number. The endoplasm is granular and may 
appear vacuolated. Reproduction in the blood of the vertebrate host 
is by longitudinal division following division of the blepharoplast, 
kinetonucleus, and trophonucleus. In some cases the daughter cells 
remain together for a longer or shorter time in a sort of rosette forma- 
tion. 

The members of the genus Trypanoplasma (Cryptobia) have two 
flagella. They are mostly parasitic in fishes; so far as known there are 
no species which attack higher animals. 

Transmission. — The Trypanosoma are parasites of the blood, 
IjTuph, or cerebrospinal fluid of vertebrates, and, with one known ex- 
ception, their transfer is accomplished by the intervention of an inter- 
mediate carrier which is either essential and indirect, or mechanical 
and direct. In the former case a blood-sucking fly becomes infected 
by feeding upon the blood of an animal harboring the trypanosomes. 
In the body of the fly the trypanosomes undergo certain changes, 
probably of a revitalizing nature, and for a period of time the fly remains 
noninfective. When this period has elapsed the tiypanosomes within 
the fly resume their ability to infect any host whose blood is reached by 
the piercing mouth parts of the fly. Furthermore, such flies remain 
infective for an indefinite period, probably for the remainder of their 
lives. 

By the direct or mechanical method of transfer the fly, after having 
bitten an infected animal, very shortly afterward visits a healthy one 
and may inoculate it directly with its contaminated proboscis. If the 
fly draws the blood of a sick animal and then successively visits two 



330 PARASITES OF THE DOMESTIC ANIMALS 

healthy ones, the second of the latter will not usualty contract the 
disease. This is due to the fact that the proboscis of the fly, charged 
with the trypanosomes from the blood of the sick animal, becomes 
cleaned of the organisms in biting the first of the healthy ones. Any 
biting arthropod may transmit by the direct method; the abilit}'^ to 
infect is usually limited to a few hours from the time of biting an in- 
fected animal, though under experimental observation it has been re- 
tained for a considerably longer time (see Glossina, p. 44). 

Nagana 

The fundamental work upon this disease was carried on in Zululand 
by Bruce who, in 1895, discovered that nagana, or the so-called tsetse 
fly disease, was caused by a trypanosome which, after its discoverer, 
has been named Trypanosoma brucei. 

"Nagana, or fly disease," Bruce writes, "is a specific disease which 
occurs in the horse, mule, donkey, ox, dog, cat, and many other animals, 
and varies in duration from a few days or weeks to many months. It 
is invariably fatal in the horse, donkey, and dog, but a small percentage 
of cattle recover. It is characterized by fever, infiltration of coagulable 
Ijaiiph into the subcutaneous tissue of the neck, abdomen, or extrem- 
ities, giving rise to swelling in these regions, by a more or less rapid 
destruction of the red blood corpuscles, extreme emaciation, often 
blindness, and the constant occurrence in the blood of an infusorial 
parasite." 

Nagana is a Zulu word which, according to Bruce, refers to the state 
of depression and weakness characteristic of the disease. 

Nagana exists, particularly in low and humid regions, throughout 
Africa with the exception of Tunis, Algeria, and Morocco, and most of 
the countr.y south of the Tropic of Capricorn. The disease is supposed 
to be transmitted mainly the by the tsetse fly Glossina morsitans, though 
other species probably play an equal part in this respect. Etiologic 
reference to nagana has already been made in the review of the work of 
Bruce under the suljject of Glossina (p. 44) and need not be repeated 
here. 

Plate V. — Variou.s Species of Trypanosoma. 1. Trypanosoma lewisi, of the rat. 
2. Trypanosoma lewisi, multiplication rosette. 3. Trypanosoma lewisi, small form re- 
sulting from the disintegration of a rosette. 4. Trypanosoma brucei, of nagana. 5. 
Trypanosoma equinum, of caderas. 6. Trypanosoma gambiense, of sleeping sickness. 
7. Trypanosoma gambiense, undergoing division. 8. Trypanosoma theileri, a harmless 
trypanosome of cattle. 9. Trypanosoma transvaliense, a variation of T. theileri. 10. 
Trypanosoma avium, a bird trypanosome. 11. Trypanosoma damonioe, of a tortoise. 
12. Trypanosoma solese, of the flat fish. 13. Trypanosoma granulosum, of the eel. 14. 
Trypanosoma rajae, of the skate. 15. Trypanosoma rotatorium, of frogs. 16. Cryptobia 
borreli, of the red-eye (a fish). (After Crawley, from Laveran and Mesnil; Cir. No. 194, 
Bu. An. Ind., U. S. Dept, Agr.) 



5 ^^ 6 



of ^n 










332 PARASITES OF THE DOMESTIC ANIMALS 

Surra 

This name has been given to a disease of horses, camels, and dogs of 
Asia caused by Trypanosoma evansi, which in 1880 was found by Evans 
in the blood of affected horses. Surra occurs in Southern Asia, the 
East Indies, the Philippines, Korea, Australia, and among the drome- 
daries in Northern Africa where it is known under the name of mbori. 

Symptoms. — In its constant and progressive anaemia and cachexia 
the disease closely resembles nagana. At its outset there is a rise of tem- 
perature which in some cases may be followed by an urticarial eruption. 
Edema appears under the skin of the belly and limbs, and the eyelids 
become puffy with conjunctiva congested. The appetite is usually re- 
tained, but in spite of this there is loss of flesh and strength. Later the 
appetite is lost, there is great weakness, and the wasted and enfeebled 
animal may fall and be unable to again get upon its feet. 

Course. — Horses invariably die in from one to several months after 
the onset of the disease, though in some cases death may occur suddenly 
in the early stages. In camels the disease runs a much longer course. 
Cattle, though they may harbor the parasites in their blood, generally 
resist the disease. 

Infection. — A specific carrier of the organism causing surra is not 
known. Tsetse flies are not found in Asia, but it has been determined 
that the stable fly {Stomoxijs calcitrans) and the horsefly (Tabanus stri- 
atus) of Asiatic countries can transmit the disease by their bite. It is 
believed by some that the horsefly is the principal carrier. So far as 
known the flies carry the disease from animal to animal directly by means 
of contaminated mouth parts, and are unable to infect for more than 
one or two days after having drawn the blood of an infected animal. 

Mal De Caderas 

Mai de caderas (disease of the hip) is a trypanosomiasis occurring in 
horses throughout the greater part of South America, caused by Ti^y- 
panosoma equinum, which was discovered by Elmassian in the blood of 
horses in Argentina in 1901. The occurrence of the disease by natural 
infection is almost exclusively among horses and mules, the former of 
which are the more susceptible. A number of other mammals may be 
successfully inoculated, among them the hog, rabbit, guinea pig, rat, and 
mouse. 

Symptoms. — Following a statement that, owing to its great ravages 
in certain parts of South America, cattle have to be used for riding purpo- 
ses, Laveran and Mesnil (Trypanosomes and Trypanosomiases, Eng- 
hsh edition) describe the symptons of the disease as follows : 

"The first sign of the disease in horses is wasting, which rapidly pro- 



THE PROTOZOAN SUBGROUPS 333 

gresses in spite of a good appetite. The temperature is often raised to 
104° to 105.8° F. After a varible time it is noticed that the hind quar- 
ters are weak, and that the animal drags its legs, the hoofs grazing the 
ground. These sj-mptons increase and become characteristic, so that 
when the animal is made t > walk it staggers along, the hind quarters 
swaying from side to side. On account of this sympton the name liial 
de caderas, or disease of the hind quarters, has been given to the disease. 
There comes a time when the animal is unable to stand; if in the stable, 
it leans up against a wall or seeks other support; if in the open, it stag- 
gers and falls. After thus falling to the ground an animal may still live 
for several days if it be fed; otherwise the inevitably fatal end is 
hastened bj' inanition." 

Infection. — The mode of natural infection is not as yet known. The 
observed fact that horses separated from affected animals only by a 
fence remain healthy in spite of the presence of piercing flies, would indi- 
cate that these insects are not the transmitters. Until something definite 
is established as to the transmitting agent, no certain preventive meas- 
ures can be adopted. 

DOURINE 

Dourine is an infectious disease of the horse and ass affecting prima- 
rily the genital tract. It is due to Trypanosoma equiperdum, transmitted 
from animal to animal in the act of copulation. The disease is vari- 
ously^ named "maladie du coit," " el dourine," or " dourine," according 
to the country in which it is found, dourine, which is from the Arabic for 
"unclean," being the term most commonly employed for it in the United 
States. It is supposed to have been introduced into Continental Eu- 
rope early in the nineteenth century by horses imported for breeding, 
especially those from the Orient where the disease has long existed. 

In the United States dourine first appeared in Illinois where it was 
recognized b}^ Dr. W. L. Williams in 1886. The source of the infection 
was found to be imported Percheron stallion, and it had been dissemi- 
nated for some time before the true nature of the malady became known. 
By the application of rigid preventive measures, the disease was eradi- 
cated from Illinois in 1888, but it had been carried by a stallion to Ne- 
braska, where an investigation of an outbreak in 1892 by an inspector of 
the Bureau of Animal Industry revealed that upward of two hundred 
mares and stallions in the northwestern part of that state were aflfeeted 
with the disease. Measures taken by the federal authorities brought this 
outbreak under control for a time, but a few 3'ears later the infection 
again appeared in the same part of the state. In 1901 there was an out- 
break in the Pine Ridge and Rosebud Indian Reservations of South 
Dakota, and in 1903 the disease was reported in Van Buren County, 
Iowa. It was again found in Taylor County. Iowa, in 1911. Thus dour- 



334 PARASITES OF THE DOMESTIC ANIMALS 

ine has appeared at various times within certain Hmits in the United 
States. 

Infection. — Dourine is a pecuhar trypanosomiasis in that there is 
no intermediate carrier of the trypanosome specifically responsible for 
it. Like the spirochete of human syphilis, it is inoculable by contact, the 
infection usually occurring during the act of copulation, though reported 
cases of the disease in geldings and in mares which have never had the 
stallion would indicate that its transmission is not entirely by copulation. 
It may be artificially transmitted to horses and to other susceptible 
animals, as dogs and rabbits, by inoculation with blood from animals 
affected. Sexual intercourse is, however, by far the most common means 
of natural infection, the trypanosome reaching the blood by penetrat- 
ing the intact mucosa of the genital tract. 

Symptoms. — The symptoms of dourine as given by John R. Mohler 
(Bureau of Animal Industry, Bulletin No. 142, 1911) are, with some 
omissions, here quoted. 

"There are many variations in the symptoms of dourine, and this is 
particularly true of the disease as it occurs in this country. Two dis- 
tinct stages may be noted which vary somewhat from those described 
in textbooks, but probably no more than could be expected when 
differences of climatic conditions and methods of handling are taken 
into consideration. 

"The first stage chiefly concerns the sexual organs, and therefore 
differs somewhat in the male and female. In the second stage symptoms 
indicating an affection of the nervous system are more prominent and 
are not dependent on the sex of the animal. 

"Following a variable period of incubation of from eight days to two 
months, there is seen in the stallion an irritation and swelling about 
the penis first noticed in the glans. This swelling extends throughout 
the organ, and the penis may be continually protruded and frequent 
ei-ections noticed. The edematous swelling also involves the groin, 
with enlargement of the adjacent inguinal glands, and extends forward 
along the abdomen. In a few days small vesicles or blisters appear on 
the penis, which break, discharging a yellowish serous fluid and leaving 
irregular raw ulcers. Where primary ulcers are in proximity to each 
other there is a marked disposition to coalesce, a large raw surface with 
irregular border resulting. The ulcerative process may form a wound 
extending almost entirely around the penis. The ulcers show a tendency 
to heal rapidly, leaving white cicatrices which are permanent. In some 
cases the urinary meatus is very red and swollen, and according to some 
observers, especially European, more or less thick catarrhal exudate 
is discharged from its oriface. This condition, however, has been rarely 
seen in cases in this country, a more or less continuous dripping from 
the urethra of a yellowish serous-like discharge alone being present. 



THE PROTOZOAN SUBGROUPS 335 

The stallion retains his full genetic instinct and becomes veiy amorous 
when brought in the vicinity of mares. If allowed access to mares in 
season, service is often impossible, due to the fact that a complete 
erection of the penis does not occur. The testicles may be involved and 
tender to pressui'e, and abscess formation may occur with sloughing. 

"In the mare the first s>nnptoms may be so slight as not to be noticed 
by the owner. The disease being the result of copulation, begins with 
swelling and inflannnation of the vulva and vagina. The labia are 
continuall}' everted, exposing the clitoris, which is constantly in a state 
of erection. There will also be a muco-purulent discharge like that 
coming from the penis of the male, which may be slight or profuse in 
quantity. The mare will switch the tail, appear uneasy, and urinate 
frequently. Shortly papules and vesicles appear on the external vulva, 
as well as on the mucosa of the vulva and vagina. These vesicles soon 
rupture, but before doing so the contents undergo a change from a 
transparent to a purulent fluid. The rupture of these pustules is the 
initial stage in the formation of deep, angry ulcers. These ulcers show 
a tendency to heal rapidly, but invariably leave a cicatrix. On the dark 
skin of the external vulva the scars will always be white. This de- 
pigmentation is permanent. 

'"Sometimes, especially in the mare, the above-described lesions tend 
to disappear gradually, and in case the mare is not served again the 
disease may remain in abeyance for months or a j-ear. The apparent 
recovery, however, is not permanent, and any excessive work or excite- 
ment may set up the disease anew. In case an affected mare conceives, 
she is liable to abort at any time during her term of pregnancy. When 
the fetus is carried to full term, it occasional^ is a weak or imperfectly 
developed foal, but in this country many fine colts have been born to 
affected mares. 

"The nervous or constitutional disturbances of the second stage may 
not come on for months or even a year after the appearance of the local 
lesions, and are similar in both male and female. They consist of a 
general nervous disorder with staggering, swaying gait, especially in 
the hind limbs. The animal becomes extremeh' emaciated, particularly 
in the hind quarters, and the abdomen assumes a "tucked-up" appear- 
ance. The first indication of paralysis will be noted in traveling, when 
the animal fails to pick up one of the hind feet as freely as the other. 
There is a tendency to drag the foot partially. This condition may 
shift from one hind foot to the other, or both may become affected 
simultaneously. Twitching of the superficial muscles has been noticed 
in several instances. Urticarial eruptions or plaques may break out 
over various parts of the body, and there may be noticed pruritus of 
the skin, which causes the animal to rub itself frequently. The tem- 
perature of the animal seldom goes above 101° or 102° F. When the 



336 PARASITES OF THE DOMESTIC ANIMALS 

paralysis of the hind Hmbs starts to appear, it usually progresses rapidly, 
the horse goes down, is unable to rise, and dies in a short time from 
nervous exhaustion." 

Control. — As dourine is transmitted and spread only by copulation, 
its eradication is a less difficult problem than in trypanosomiases which 
may be carried by flies. So little benefit is to be derived from medicinal 
treatment that in this country, where the disease has appeared only 
in restricted areas, it is not advisable. While cure may be possible, 
an apparently cured animal may carry the trypanosomes for months 
in the sexual organs, and relapses are likely to occur. In areas where 
the disease appears measures of eradication must be based upon the 
prevention of infected animals from breeding. 

To confine the losses to the minimum, therefore, the prompt castration 
of affected stallions and the destruction of diseased mares is essential. 
Spaying of such mares is not a sufficient precaution from the fact that 
they may be sold and an attempt made to breed them, thus infecting 
the stallion and through this source spreading the disease. Restrictions 
in the movement of horses in infected districts and frequent reinspection 
are further state and federal measures for confining an outbreak so far 
as possible to its original limits. 

Trypanosoma americanum. — This trypanosome is found in cultures 
of blood from healthy American cattle. It deserves mention here on 
account of its common occurrence, though it appears to be harmless. 
A report by Crawley upon his extended study of this organism will be 
found in Bureau of Animal Industry Bulletin No. 145 (1912). 

Class III. Sporozoa 

Protozoa (p. 311). — The Sporozoa are all parasitic. Though without 
motile organs, they are capable of moving from place to place, in some 
cases by means of pseudopodia. Reproduction is mainly by spore 
formation, either asexual or sexual. There are a number of forms, 
however, in which simple reproduction occurs, and the group comprises 
organisms with life histories as yet not fully known. The Sporozoa, 
therefore, is a division to be regarded as provisional, containing at pres- 
ent organisms which when their life histories are fully made out may 
be more accurately placed with other divisions of the Protozoa. 

Based upon the belief that the Sporozoa are polyphyletic; that is that 
all have not the same ancestral history, they have been placed in two 
divisions, — Telosporidia and Neosporidia, the former regarded as 
descended from the flagellates, the latter from the rhizopods. Of the 
Telosporidia but two orders are to be considered here, — Coccidia and 
Hemosporidia. The Neosporidia has one order, — Sarcosporidia, con- 
taining parasites of domestic animals. 



THE PROTOZOAN SUBGROUPS 337 

Order I. Coccidia 

Sporozoa (p. 336). — The Coccidia are cytozoic or cell-infesting para- 
sites, attacking epithelium of in\-ertebrate and vertebrate animals. Re- 
production is by schizogony and by sporogony, the asexual and sexual 
generations alternating in the life cycle. In species parasitic to domestic 
animals the fertilized cell produces sporoblasts covered by a sporo- 
cyst membrane. 

Life History. — The life cycle is similar to that of the malaria organ- 
isms except that no arthropod intermediate host is required for the 
sexual reproduction. Infection with Coccidia is with the encysted stage 
(oocj'st) by way of the mouth. Hence the parasites are almost exclu- 
sively found in the epithelium of the aliment ry canal and organs con- 
nected with it. Reaching the stomach and duodenum, the oocyst is 
acted upon by the digestive juices and the sporozoites contained in the 
cyst are hberated. These enter the epithelial cells of the mucosa. Within 
the cells they lose their spindle form and enter the stage of the tro- 
phozoite in which they grow to a size depending somewhat upon that 
of the invaded cell. By the process of schizogony the trophozoite di- 
vides into a number of small protoplasmic masses which are the mero- 
zoites or asexually formed spores. These invade other cells and in the 
same manner grow into another generation of merozoites. Bj^ many 
repetitions of this cycle a large number of cells are invaded and de- 
stroyed, and the death of the host animal may follow as a result. After 
a number of asexual cycles some of the merozoites do not grow and di- 
vide into another generation of merozoites, but develop into stages which 
begin the sporogonous or sexual cycle. In this process the female tro- 
phozoite instead of dividing develops into an egg or macrogamete. The 
male trophozoite, by division, forms minute male repi-oductive elements 
or microgametes. By their motility the microganietes reach and fer- 
tilize the macroganietes which, becoming surrounded by a resistant 
membrane, arrive at the stage of the oocyst. Within the oocj'st a num- 
ber of spores may be formed, each inclosed in a protecting membrane 
and constituting a sporocyst. By division each sporocyst forms two 
or more sporozoites, and thus the sexual cycle is completed. Where the 
parasites are in the epithelium of the alimentary tract or its comaiiu- 
nicating organs, the oocysts pass to the exterior with the feces. In other 
cases it may be that they can only reach the outside after the death and 
disintegration of the host. 

The effect of coccidiosis upon the animal is brought about by the ex- 
tensive destruction of cells resulting from the repeated production of 
merozoites by schizogny. This progressive reproduction and cell de- 
struction would in every case result in the death of the animal were it 
not that the number of schizogonous generations is limited. The cell 




Plate VI, Fig. 2. 



Plate VI. — Fig. 1. — Percheroii stallion, showiiifi condition at the time of purchase. 
Fig. 2. Same stallion after dourine luul developed. Spot.s on side and croup give location 
of plaques. (After Mohler, Bui. Xo. 142, Bu. An. Ind., U. S. Dep Agr.). 





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Plate VII, Fig. 




Plate VII, Fig. 2. 



Plate VII. — Fig. 1. — Perclicron marc, showing chronic dourinc. Observe the "tucked 
up" abdomen and emaciation, the mare having lost over 700 pounds in the previous four 
months. Fig. 2. — A mare in the last stage of dourine. Notice the position of the off hind 
foot and the straightened hock joints. (After Mohler, Bui. No. 142, Bu. An. Ind., U. S. 
Dept. Agr.). 



342 PARASITES OF THE DOMESTIC ANIMALS 

destruction ceases with the beginning of the sporogonous C3'cle, and, if 
the acute stage of the disease is survived, the animal tends to recover, 
the destroyed cells being replaced more or less completel}^ by newlj' 
formed ones. Thus it maj^ be said that the disease is self-limiting. 
Eimeria stiedae. — Coccidia (p. 337). — This coccidian, also known 
as Coccidium oviforme and C. cuniculi, is the species commonlj^ found 
in the Hver of domestic rabbits. Most frequently it attacks the epithe- 
lium of the bile ducts where it causes destruction of cells and pathologic 
changes in the Uver by which the secretion of bile is reduced. The con- 
dition affects rabbits seriously and deaths occur as a result of it. 

Eimeria stiedce is considered by some authors as a cause of coccidiosis 
in man. 

Diplospora bigemina (Isospora bigemina). Coccidia (p. 337). — In 
a report upon their work with this coccidian Hall and Wigdor (Journal 
of the American Veterinary Medical Association, April, 1918) state that 
in two hundred dogs examined at Detroit, Michigan, it was found in 
fifteen, or slightly over seven per cent. From this finding they suggest 
that the parasite may be more common in American dogs than our pres- 
ent lack of information would indicate. 

In reference to the pathogenesis of Diplospora bigemina, these au- 
thors may be further quoted from the same article as follows : 

"As regards the pathological significance of D. bigemina, we have 
but Httle information, but the following notes may serve some purpose: 
Dog No. 130 presented a clinical picture of distemper and died of pneu- 
monia, probably due in part to distemper and partlj' to an accident 
in drenching. The small intestine showed diffuse hemorrhagic points, 
most pronounced in the ileum, especially the lower ileum near the valve. 
Scrapings of the mucosa showed the coccidia to be most abundant in the 
ileum, less so in the jejunum and least so in the duodenum. These 
findings of increasing numbers of coccidia with increasing severity 
of lesions may be correlated, but in the absence of sections indicating 
the relation of the coccidia to the hemorrhage, we do not care to hazard 
a definite opinion. Dog No. 173 showed numerous fine petechiae in the 
intestinal mucosa, and these were especally numerous in the Peyer's 
patches, giving these a uniformly dark appearance. No sections were 
made and this dog had shown no oocysts in the feces for fortj^'-five days. 
Dog No. 127 showed innumerable pinpoint petechiae in the ileum, but 
it would be unsafe to draw conclusions based on this one dog, as the 
animal figured in other experiments. The intestine of dog No. 223 was 
macroscopically normal except for the presence of hook-worm petechiae. 
In view'of the fact that coccidia are destructive to epithelial tissue and 
that some species fairly closel}^ related to D. bigemina are known to be 
highly pathological, it would seem reasonable to suppose that D. big- 
emina might be distinctly pathological at times, though the apparent 



THE PROTOZOAN SUBGROUPS 343 

?i;ood health and lack of post-mortem lesions in other do^s makes it cer- 
tain that it often does no visible damage." 

Coccidium zurni. Coccidia (p. 337). — Red dysentery of cattle is 
attributed to this coccidian. The disease occurs in Europe, generally 
among young animals as an enzootic. The attack of the parasites upon 
the cells of the intestinal mucosa causes extei^sive hemorrhage, the red 
diarrhea resulting fi-om the mixture of the blood with the feces. Mild 
cases, particularly in adult animals, ma\' soon recover. Severe cases, 
occurring particularly in young animals, may run a hyperacute course 
and terminate fatally within two da\'S, or an acute course of five to ten 
days may precede this termination. 

In the report of the Committee on IVIedicine and Surgery submitted 
at the meeting of the Pennsylvania State A'eterinary ^Vledical Associa- 
tion, held in January, 1918, Dr. W. J. Uentz, of the University of Penn- 
sylvania, called attention to cases of intestinal coccidiosis of cattle 
which had come under his ol:)servation in the State of Delaware. His 
report as published in the Journal of the American \'eterinary ]\Iedical 
Association for November, 1918, follows: 

"Was asked to consult with a vetermarian on an interesting condition 
in a herd of grade Holsteins. Owner had lost four or five heifers over a 
period of about two weeks, ranging in age from six months to eighteen 
months. All presented similar s\anptoms. There was first noticed a 
serous, fetid, black diarrhea. Fever was rarely in evidence at any time. 
The diarrhea after a few days changed to mucus, with the passage of 
blood clots with the mucus and feces from time to time. Straining was 
very marked. Appetite somewhat impaired but. nevertheless, partook 
of some food, but finally, in about six to eight days, became very dull, 
refused food, emaciated rapidly, rectum became relaxed, temperature 
subnormal, pulse hardly perceptible, and these sjnnptoms of collapse 
were soon followed by death. On arrival at the farm found six to eight 
calves and one adult cow presenting some of the s\nnptonis mentioned, 
and, inasmuch as one was about to die, it was destroyed and posted. 
Lesions were confined to the large intestine. No apparent pathological 
change in anj- other organ. The mucous membrane of the large in- 
testine, which was almost empty, was red brown in color, soft and 
spong}', and everywhere coated with a bloody nmcus. The back of the 
knife, after the intestine was slit open, was passed over the mucous 
surface and the bloody mucus scraped off, when it was noticed that 
large superficial ulcers, white in color, and about the size of one's palm, 
were present throughout the whole extent of the large intestine from 
the cecum to the anus. Some of the mucous patches were scraped off 
and collected in a bottle, also some of the blood and feces. On micro- 
scopic examination, coccidia were detected. A diagnosis of "intestinal 
coccidiosis," or "red dvsentery," was therefore made. Treatment 



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Plate VIII. Fig. 2. 



THE PROTOZOAN SUBGROUPS 345 

Plate VIII. — Coccidian Life Cycle. — Fig. 1. 1. Sporozoite released in intestine of 
host. 2. Penetration of sporozoite into epithelial cell. 3, 4. Growth of sporozoite into 
trophozoite. 5, 6, 7. Schizogonous cycle. Nuclear division, followed by division of 
entire trophozoite into a large number of merozoites. 8. Free mcrozoites, which for an 
indeterminate number of generations merely repeat the schizogonous cycle, behaving 
precisely as do the sporozoites. Eventually, however, the sporogonous cycle is initiated, 
which proceeds as follows: 9a. Undifferentiated female cell. 9b. Undifferentiated male 
cell. 10a. Differentiated female cell. 10b. Differentiated male cell. 11, 12. Formation 
of the microgametes, one male cell producing many microgametes. 13a. Macrogamete. 
One female cell produces but one macrogamete. 13b. Ripe microgamete. 14. Fertiliza- 
tion. 15, 16, 17. The zygote. 18. Beginning of spore formation. 19. Completion of 
spore formation. 20. Formation of the sporozoites within the spores. 21. Release of the 
sporozoites in the intestine of the host. Fig. 2. — Introduced for comparison with the 
more typical cycle shown in Fig. 1. Here the parasite penetrates and comes to rest in the 
nucleus instead of the cytoplasm, and there is se.xual differentiation in the schizogonous 
cycle as well as in sporogony. (After Crawley, from Mense's "Handbuch," after 
Schaudinn, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 

suggested: Pearson's creolin well diluted with milk or water, also large 
doses of camphorated tincture of opium, and rectal injections, using 
garden hose and funnel, of a two per cent, creolin solution, alternating 
night and morning with a one per cent, alum solution. A week later 
received word that all were doing nicely and no deaths." 

In Europe outbreaks of red dysentery similar to that of cattle have 
occurred in sheep. 

CocciDiAL Enteritis of Chicks 

The use of the name "white diarrhea" for this coccidiosis tends to its 
confusion with bacillary white diarrhea, which is a fatal septicemia of 
chicks caused by Bacterium pulloruni. Coccidial enteritis or coccidiosis 
of chicks is caused hyEimeria avium (Coccidium tenelhim), which attacks 
the epithelium of the intestinal mucosa, usually that of the ceca. Occa- 
tionally the infection is found in other organs. The disease is usually 
seen in chicks from two to ten weeks old. 

Symptoms. — The symptoms are merely suggestive of coccidiosis as 
they do not materially differ from those of some other diseases of poul- 
try. The affected chicks droop and are inclined to stand about by them- 
selves with eyes closed and feathers ruffled. In most all cases there is a 
diarrhea with whitish-colored discharge which stains and mats the 
feathers below the vent; a bloody diarrhea gives evidence of coccidial 
infection. If the discharge is examined under the microscope large 
numbers of circular or slightly oval oocysts may be found. Death usually 
occurs after a course of three to four da3'S. 

Post-morten Appearance. — Post-mortem examination reveals the 
ceca much enlarged. Their contents may be normal or they may be 
packed with a yellowish white or bloody semiliquid material. The 
conclusion that the chicks are not infected with coccidia should not be 
made from the absence of enlarged ceca, as occasionally there is no 



346 PARASITES OF THE DOIMESTIC ANIMALS 

enlargement of these organs nor abnormal appearance of their contents. 
Not infrequently the enteritis involves the entire length of the intestines. 
For a positive diagnosis microscopical examination of the intestinal 
contents or of the sectioned intestinal wall is necessary. Spreads of 
scrapings from the cecal mucosa examined under the microscope will 
reveal epithelial cells much distended by the development of the par- 
asites within them. It is as a result of this invasion that the cells finally 
break down and separate from the underlying stroma to become a part 
of the pasty catarrhal exudate which characterizes the fecal discharge. 

Infection. — Though the fatalities are usually among the young 
chicks, the coccidian which causes the disease may be found in chickens 
of all ages and it ma}^ be spread from this source. Infection is by food 
and ingested soil or water contaminated by droppings which contain 
the cysts. It has been demonstrated that the cysts may remain infective 
for a year or more, therefore chickens may become infected if allowed 
access to yards where those harboring the parasites were kept the year 
previous. 

Control. — There are no drugs which have been found to be of value 
in treating the disease, therefore control is the essential consideration in 
contending with it. Morse states (Bureau of Animal Industrj^ Cir- 
cular No. 128, 1908) that this must begin with the eggs used for hatching. 
"These," he writes, "should be thoroughly and antiseptically cleaned 
bj^ wiping in ninety-five per cent, alcohol. If artificial incubation is 
used (and in this method lies the great hope of success), the incubator, 
if used before, should, previous to receiving the eggs, be carefully washed 
with antiseptic solutions and exposed to the sun. The egg tray should 
be scalded or flamed. The floor of the nursery should be movable, so 
that it may be taken out and sterilized, and if made of burlap the old 
piece should be torn off and a new piece mounted on the sterilized frame. 
The same precautions should be used with the brooders. The soil to 
which the chicks have access should be well covered with lime, dug up, 
and exposed to the drying effects of the sun and air. If natural in- 
cubation is practiced the hen for a week or two before being set should 
be treated with one-quarter to one-half grain doses of sulphate of iron 
daily, with occasionally an active purgative, such as calomel, one grain, 
or castor oil, one-half teaspoonful containing five to ten drops of tur- 
pentine. The eggs, cleansed as directed above, should be placed in a 
perfectly fresh nest, which may be sprinkled from time to time with a 
little hme. After hatching, the hen with her chicks should be placed 
upon ground that has been thoroughly sterilized, as described above, 
and at least every few days moved to fresh ground which has been 
treated in the same way and from which all chickens have been de- 
barred." 

Further preventive measures are the removal of visibly sick chicks 



THE PROTOZOAN SUBGROUPS 347 

from the flock, either keeping them isolated or killing and burning them. 
It is better to put all of the chickens on new ground if possible, other- 
wise the ground should be covered with lime and spaded so that it may 
be exposed to the drying effect of the sun and air. All litter and nesting 
should be burned and a thorough cleaning up of the quarters followed 
by the application of a strong disinfectant solution. After drying, 
the floors may be protected from rccontamination somewhat b,y covering 
them with shavings, chopped bedding, or other absorbant material, 
which is to be cleaned up and burned dail}'. Boards should be placed 
beneath the roosts to receive the droppings for convenient daily removal. 
Contamination of feeding and drinking vessels can in a measure be pre- 
vented b}^ elevating them somewhat from the grountl. They should at 
all times be kept clean; daily treatment with scalding water or flaming 
followed by exposure to the sun will do much to eliminate the soiu'ce 
of the infection. 

Order II. Hemosporidia 

Sporozoa (p. 336). — The Hemosporidia are Sporozoa which dwell in 
the blood where they invade the corpuscles, hence are cytozoic. Flag- 
ellated stages appear in their life history, and many protozoologists 
suspect that the entire group has been evolved from the flagellated 
Protozoa. Comparing the life history of the malaria organisms (p. 318) 
with that of the Coccidia (p. 337) a distinct difference will be noted in 
the method of infection, the hemosporidian, as is true of others of the 
group, being transmitted from the blood of one animal to that of an- 
other by means of a known intermediate host, while the Coccidia infect 
directly, usually by food or water bearing the cysts. In diseases caused, 
by Hemosporidia, the infection, due to the activities of the intermediate 
host, is more widel}^ disseminated, and large numbers of animals may 
be seriously and fatally attacked. As blood parasites, therefore, the 
Hemosporidia may be rated with the tiypanosomes in pathologic im- 
portance. 

Texas Fever 

Tick fever. Splenic fever. 

Smith and Kilbourne in 1893 foimd small parasites in the red blood 
corpuscles of cattle suffering with Texas fever. Due to their frequent 
occuri-ence in pairs, the}' were given the specific name higeminum, and the 
genus was named Pyrosoma. The later generic name Piroplasma was 
derived from their often assuming a pear-like form, and the name now 
generalh' used for the hemosporidian causing Texas fever is Piroplasma 
higeminum (Fig. 171). 

The medium by which the organism is transmitted is the cattle tick 
Margaropus annulafus. which crawls upon its host as a larva, attaches, 




348 PARASITES OF THE DOMESTIC ANIMALS 

and here undergoes its complete development. (Ref . Margaropus annul- 
atus, Life History, p. 148.) For a number of days following her fer- 
tilization the female tick engorges with the blood of her host and then 
drops to the ground where a few clays later she deposits her eggs and, 
having completed her cycle, soon dies. The parasites contained in the 
blood upon which the tick has fed reach the eggs and 
are present in the larval ticks when these are hatched. 
Thus the larvae have the power to infect any susceptible 
animal to which they attach. 

In the first stage of development after gaining the 
circulation the piroplasma is within the red corpuscle 
as a single body near the corpuscle's margin. Later it 
Piroplasma^ Tig- "^^^^i^^^^s into two bodics which remain slightly connected 
eminum (after by a Small filament. A single corpuscle may contain as 
Crawley, from many as four or even six parasites. The doubled bodies 

Doflem, Cir. No. i • • n i i i i j 

194, Bu. An. ind. enlarge, assummg a spmdle-shaped and later a pear- 
u. s. Dept. Agr.) shaped appearance. Finally, as a result of this invasion, 
the corpuscles break down, and the parasites become 
free bodies in the plasma. That a multiplicative stage occurs within 
the bovine host is evidenced from the fact that inoculation of sus- 
ceptible cattle with a small quantity of virulent blood will produce the 
disease with the development of myriads of the parasites in the blood of 
the inoculated animals. 

Occurrence. — Numerous attempts have been made to produce Texas 
fever in other species of animals by inoculating them with infected blood 
from cattle. That all of these experiments have proved negative in- 
dicates that the disease is one purely bovine. All bovine animals that 
have never been exposed are susceptible, and in all cases natural in- 
fection with the protozoan causing the disease is due to puncture by 
the cattle tick. 

The disease exists in European and Asiatic countries, Africa, Australia, 
and the Philippine Islands. It was probably introduced into the United 
States by cattle brought over by the early Spanish settlers. The terms 
" Texas fever " and " southern cattle fever " are misleading to some in 
giving the impression that the disease is confined to the Southern States. 
Southern cattle carrying the infecting organism in their blood, though 
themselves possessing degrees of immunity to Texas fever, disseminate 
it through ticks from their bodies among cattle in the North or among 
those of the South which are susceptible to the disease in a virulent 
form. 

Exposure and Development. — The period from exposure to tick in- 
fested pastures or pens to the appearance of the disease depends upon 
the time which elapses from the dropping of the female ticks from the 
southern cattle to the hatching of the larvae from their eggs, and this 



THE PROTOZOAN SUBGROUPS 349 

will be influenced by climatic conditions. If the larval ticks are already 
present and at once attach to the exposed animals symptoms of the fever 
may develop ten to twelve days later. Where the susceptible animals 
are placed upon pastures, in pens, or other places immediately after 
these have been infected with ticks from southern cattle, a period must 
intervene covering egg-laying and hatching of the larvae before the 
northern animals become inoculated. In sununer this period may oc- 
cupy from twenty to forty days; in cooler weather it takes longer for the 
eggs to hatch, and under such conditions sixty daj'S or longer may be 
required before the infective generation of ticks appears. Thus, de- 
pending upon season and temperature, the disease may appear in twelve 
days to two or three months after exposure (see life histor>' of Texas 
fever tick, page 148). 

Symptoms. — Two distinct types of Texas fever are presented, — an 
acute fatal and a chronic form, from the latter of which the animals 
usually recover. Whether the fatal or the milder type appears will de- 
pend upon season and the susceptibilty of the animals. When northern 
cattle and those raised in tick-free districts in the South are attacked in 
the hot weather of summer, the acute form occurs. If the susceptible 
animals are affected in the latter part of autumn the milder chronic spn- 
ptoms appear, and it is bj' this type of the disease that partly immune 
southern cattle are affected at any season, the fatal form rareh' attack- 
ing these animals. 

The Acute Type. — In this form of the disease the onset of the symp- 
toms is rapid. The animal is depressed and stands or lies down apart 
from the held, there is loss of appetite and rumination ceases. The tem- 
perature rises within twenty-four to forty-eight hours to 107° or 108° F., 
the fever accompanied by increase in the rate of pulse and respiration. 
During the early stages of the disease there is constipation which 
is generally followed by diarrhea. The hemoglobin released by the 
disintegration of the corpuscles causes a blood-stained urine (hemoglobi- 
nurea), from which symptom is derived the name "red water," some- 
times given to the disease. Cerebral disturbances, exhibited by stag- 
gering, disorders of vision, or delirium, may appear in some cases. A 
conclusive diagnosis may be made upon finding the parasites within the 
corpuscles by microscopic examination of the blood. 

A fatal termination is usually reached within three or four days. If 
recovery occurs, it is much prolonged, due to the time required for the 
generation of new corpuscular elements to replace those destroyed. 

The Chronic Type.— The difference in the symptoms of the chronic 
type of the disease from those of the acute is one of degree. Further, 
there is a seasonal difference, the milder chronic form usually appearing 
in the late fall and early winter, the acute in the hot sununer months. 
The temperature does not go as high, remaining at about 103° F. and 



350 PARASITES OF THE DOMESTIC ANIIVIALS 

not exceeding 105° F. The anaemic condition is indicated by the paleness 
of the visible mucosae, and the extended course brings about great 
emaciation. In these cases hemoglobin is not usually passed with the 
urine, hence hemoglobinurea or ''red water," typical of the acute form, 
is absent. 

Death rarely occurs in this type of the disease, though, due to its 
prolonged course and the excessive loss of flesh, much loss is sustained 
in the productive valuation of the animal. 

Prevention and Treatment. — Prevention is by measures dealing 
with the cattle tick Margaropus annulatus, which is the specific carrier 
and transmitter of the protozoan causing the disease. As study of the 
life histoiy of this tick has shown that it will not mature except upon a 
bovine or equine host, it follows that it can be exterminated from in- 
fested pi-emises by keeping cattle and horses off of such premises until 
the larval ticks, unable to find a host, have perished. With this purpose 
in view, systems of pasture rotation have been devised additional to 
methods directed toward the destruction of ticks on the cattle (Ref. 
Margaropiis annulatus, p. 145). 

Medical treatment of animals sick with Texas fever has not proved 
satisfactory. In the milder type of cases the constipation may be re- 
lieved somewhat by Epsom salts. Repeated doses of digitalis during 
the excessive anaemia and the administration of tonics, such as gentian 
and nux vomica, during the stage of convalescence, have been recom- 
mended as beneficial. The recovering animal should have free access 
to pure water and a generous supply of nutritious food. 

Order III. Sarcosportdia 

Sporozoa (p. 336). — The Sarcosporidia are parasites in striated 
muscle cells of vertebrates. Sporulation takes place during the develop- 
ment of the trophozoite which becomes surrounded by a protective 
envelope. 

These muscle parasites are found in man, in domestic and wild birds, 
and are common in domestic mammals. The muscles more commonly 
invaded are those of the upper part of the esophagus, larynx, the body 
wall, the diaphragm, and the psoas muscles. 

Development. — Within the muscle fiber the parasite first appears as 
a minute body in which stage it is known as Miescher's tube. As the 
young ti'ophozoite develops it becomes multinuclear and surrounded by 
a membrane, while groups of spores form in the center of the proto- 
plasmic body. With the continuation of the spore formation the cyst 
enlarges, causing such distension of the muscle fiber as to result in its 
rupture, releasing the cyst which ultimately bursts, the spores thus 
becoming scattered to infest new muscle cells. By repetitions of this 



THE PROTOZOAN SUBGROUPS 



351 



auto-infective process the entire skeletal musculature may become 
affected. More or less destruction of muscle tissue is thus brought 
about which necessarily is relatively injurious to the host; furthermore, 
the effect is contributed to by the extremely toxic nature of the parasites 
themselves. 

Importance of Sarcosporidiosis and Mode of Infection. — Hosts show- 
ing high incidence of infection with Sarcosporidia among domestic 
animals are pigs, sheep, cattle, and horses, the infecting species in each 
case being Sa7-cocys(is miescheriana occurring in pigs, S. tenella in sheep. 





Fk;. 172. — Various foini.s of Sarcospoiiilia. _'. S:iii(h\ >tis lilani-hanli. Longidtudinal 
section of an infected muscle with yount; iiidi\i(lual (after Ciawley, from Doflein, from 
VanEeckc, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 3. Sarcocystis tenella in a 
Purkinje cell of the heart of a sheep (after Crawley, from Doflein, from Schneidemuhl, 
Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 4. Sarcocystis tenella in the wall of the 
esophagus of a sheep (after Crawley, from Doflein, from Schneidemuhl, Cir. No. 194, Bu. 
An. Ind., U. S. Dept. Agr.). 5. Sarcocystis muris in muscles of mouse (after Crawley, 
Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 

S. hianchardi in cattle, and S. berirami in horses. In these animals the 
infection has been considered as of little pathologic importance; the 
sarcosporidiosis is apparently never fatal, and it is rare to find an animal 
visibly affected. This conclusion, however, may be modified somewhat 
by further study of the parasite, warranted b}' its prevalence, toxicity, 
and possibly greater pathologic import than at present supposed. 
Up to the present time little has been brought to light as to the life his- 



352 PARASITES OF THE DOMESTIC ANIMALS 

toiy of the Sarcosporidia or as to the mode by which they infect. They 
are known to be fatal to mice, and it has been found that when mice are 
fed upon the flesh of other mice containing Sarcosporidia they become 
infected. Hence the conclusion follows that natural transmission occurs 
in these animals through their habit of nibbling at their dead; but this 
method of transfer can hardly be considered in the case of sheep, cattle, 
and horses, and the mode of infection in these animals remains a prob- 
lem. 

In an article upon the Sarcosporidia encountered in Panama (Journal 
of Parasitology, March, 1915), Darling suggests that these muscle 
parasites of vertebrates are aberrant forms of the Neosporidia of in- 
vertebrates, and points to the facility with which herbivora may in- 
g3st Neosporidia with leaves and other vegetation bearing infected 
invertebrates and their droppings. "Is it not possible," Darling writes, 
"that Sarcosporidia may be sidetracked varieties of some of the Neo- 
sporidia of invertebrates which have invaded the musculature of a 
hospitable though b}^ no means definitive host and are unable to con- 
tinue further their life cycle and escape from a compromising and aber- 
rant position?" The high incidence of infection among sheep, cattle, 
horses, and swine is evidence favoring this explanation. 



GLOSSARY 

Aberrant. In botany and zoiilogy, differing in some of its characters from the group 

in which it is placed. 
Acari. Arthropods of the order Acarina; mites and ticks. 
Acaricide. A medicinal agent used to destroy acari. 
Agamous. In zoology, having no distinguishable se.xual organs. 
Amorphous. Without definite form; shapeless. 
Ambulatory. Formed or adapted for walking. 
Ametabolic. Pertaining to insects and other animals which do not undergo a 

metamorphosis. 
Anorexia. Loss or absence of appetite. 

Antenna. A segmented process on the head of insects, myriapods, and crustaceans. 
Anthelmintic. A medicinal agent used to destroy or expel worms from the intestinal 

tract. 
Apodal. Without feet. 
Apterous. Without wings. 
Aquatic. Growing in or frequenting water. 
Arboreal. Attached to or frequenting trees. 
Arista. A tactile filament at the end of the antenna of an insect. 
Article. A segment or part of the body connected by a joint with another segment 

or part. 
Asexual. Having no sex. 

Basis capituli. Basal portion of the capitulum or head of a tick. 
Biiid. Cleft or divided into two parts. 

Bisexual. Having the organs of both sexes in one individual. 
Buccal. Pertaining to the cheeks or mouth cavity. 
Budding. A method of reproduction by which a protuberance from the parent 

organism develops into a new organism. 
Bursa. A sac or sac-like cavity. 
Capitulum. The head of a tick. 

Caryozoic. Pertaining to parasites which live in the cell nucleus. 
Catalepsy. Suspension of sensibility and voluntary motion. 
Caudal. Pertaining to the tail. 
Cephalic. Pertaining to the head. 

Cephalothorax. The fused head and thorax of arachnids. 

Chelae. Pincer-like terminations of certain of the limbs of crustaceans and arachnids. 
Chelate. Terminated by chela?. 
Chitin. The horny substance forming the harder part of the integument of insects 

and other arthropods. 
Cilia. Hair-like processes, as of a cell, capable of vibratory movement. 
Coelom. The body-cavity, as distinguished from the intestinal cavity; the periaxial, 

perivisceral, or perienteric space. 
Ccelozoic. Pertaining to parasites which live in the ccclomic cavities of the body. 



354 GLOSSARY 

Coxa. The hip or hip joint. In insects and other arthropods the first segment of 
the leg from the body, articulating with the second segment or trochanter. 

Cystogenous. Producing or bearing cells. 

Cytozoic. Pertaining to parasites which live within the cell cytoplasm. 

Dentate. Having a toothed margin or tooth-like projections. 

Denticulate. Having very small tooth-like projections. 

Dimorphism. The pi'operty of assuming or of existing under two distinct forms. 

Dipterous. Having two wings; belonging to the insect order Diptera. 

Dorsum. The dorsal surface or back of an animal. 

Ecdysis. The process of casting the skin; molting. 

Elytra. The fore-wings of beetles, serving to cover the hind wings. 

Enterozoic. Pertaining to parasites which live in the lumen of the digestive tract. 

Epimeron. One of the side-pieces in the segment of an arthropod animal. 

Facet. A smooth, flat, circumscribed surface. 

Fauna. The aggregate of the animals of a given region or geological period. 

Femur. The thigh bone. The third segment of the leg of an insect, articulating 
proximally with the trochanter and distally with the tibia. 

Filiform. Thread-like. 

Fission. Reproduction by division of the body into two parts, each of wliich be- 
comes a complete organism. 

Flagellum. A whip-like appendage or process of a cell. 

Flora. The aggregate of the native plants of a given region or period. 

Gamete. A sexual cell or germ cell. 

Gametocyte. An adult parasite, as in the Plasmodium of malaria, when in its 
reproductive form. 

Granular. Consisting of grains or granules. 

Gregarious. Inclined to gather together, as to live in flocks or herds. 

Habitat. The natural abode of an animal or plant. 

Halteres. The rudimentary hind wings of Diptera; balancers. 

Haustellum. A proboscis adapted to take food by suction, as in many insects. 

Hematozoic. Pertaining to parasites which live in the blood. 

Hemelytra. The partially thickened anterior wings of certain insects. 

Hermaphroditism. The union of the two sexes in the same individual. 

Hexacanth. The sLx-hooked tapeworm embryo; the onchosphere. 

Hexapod. A six-footed animal; a true insect. 

Hyaline. A glassy or transparent substance or surface. 

Imago. The final or adult stage of insects. 

Infundibuliform. Having the form of a funnel. 

Labium. In insects, the lower lip, formed by the second pair of maxillae. 

Labrum. In insects, the upper lip. 

Lobe. A somewhat rounded projection or division of an organ or part. 

Macrogamete. The large female gamete or germ cell. 

Macrogametocyte. The female gametocyte. 

Mandibles. In arthropods, the anterior pair of mouth parts which form biting jaws. 

Marine. Living in the sea. 

Maxillae. In arthropods, paired appendages behind the mandibles, usually serving 
as accessoiy jaws. 

Merozoites. Asexually formed spores of the malaria parasite. 



GLOSSARY 355 

Mesothorax. The middle segment of the thorax of an insect. 

Metabolism. The processes concerned in the building up of protoplasm and its 

destruction. 
Metamere. One of a series of segments composing the body, as in many worms 

;iii(l in arthropods. 
Metamorphosis. Change of form or structure, as in the larval, pupal, and imago 

stages of an insect's development. 
Metaphyta. Plants consisting of many cells; all plants above the Protophyta. 
Metathorax. The posterior segment of the thorax of an insect. 
Metazoa. Animals which, in an embryonic condition, possess at least two distinct 

germinal layers; all animals above the Protozoa. 
Microgamete. The male germ cell consisting of a detached flagelliform process of 

a niirrogametocyte. 
Microgametocyte. The parent male cell. 

Micron. One thousandth of a millimeter; a unit of microscopic measure. 
Molting. The shedding of the hair, feathers, or outer layer of the skin, which are 

replaced by new growth. 
Morphology. The science of the outer form and internal structure of animals and 

l)Iants. 
Myasis. A disease caused by the presence of the larvte of flies in or on the body. 
Myiasis. Same as myasis. 
Myiosis. Same as myasis. 

Ocellus. A small simple eye of many invertebrates. 
Octopod. Having eight feet, as in adult arachnids. 
Onchosphere. The tapeworm embryo; the hexacanth. 
Ookinete. Same as zygote. 
Oospore. Same as zygote. 
Operculum. A lid-like process or part. 
Ovum. An egg cell or egg. 
Ovigerous. Egg bearing. 
Oviparous. Producing eggs that hatch after they have passed from the body of the 

l)arent. 
Oviposition. The laying of eggs, especially applied to insects and arachnids. 
Ovipositor. A specialized organ, as in certain insects, for depositing eggs. 
Ovoviviparous. Producing eggs that have a well developed shell or covering, as in 

oviparous animals, but which incubate within the body of the parent. 
Ovulation. The formation of eggs in the ovary; the discharge of the egg or eggs 

from the ovary. 
Palpi. Appendages, usually organs of touch or taste, attached to the mouth parts 

of insects and other arthropods. 
Papilla. A small nipple-like or pimple-like projection. 
Parasiticide. A remedy that destroys parasites. 
Parthenogenesis. The production of individuals from ova without fertilization by 

tlic male element. 
Pedipalpi. Leg-like or pincer-like appendages of arachnids, located on each side of 

the mouth. 
Phylogenic. Pertaining to the ancestral history of an animal or plant. 
Phytozoon. A colony of animals resembling a plant. 



356 GLOSSARY 

Plasmodium. A mass of protoplasm formed by the union of two or more amebiform 

bodies or individuals. 
Plumose. Feathery; plume-like. 

Pollenose. Bearing a powdery or pollen-like substance. 
Predacious. Living bj' prej-ing on other animals. 
Prehensile. Adapted for gi-asping. 
Proboscis. The tubular process of the head, especially of insects and arachnids, 

adapted for sucking or piercing. 
Proglottid. The segment of a tapeworm. 
Pro thorax. The anterior segment of the thorax of an insect. 
Protophyta. The division of unicellular plants. 
Protozoa. The phylum consisting of the unicellular animals. 
Pruritus. An intense degree of itching. 
Pseudopodia. Processes of the protoplasm of a cell which may be protruded or 

retracted, as for locomotion or for taking food. 
Pubescent. Arrived at puberty, or the earliest age at which the reproductive func- 
tion can be performed. 
Puparium. The case in which an insect is enclosed between its larval stage and 

the state of full development or imago. 
Pupiparous. Pertaining to insects in which the young are born ready to become 

pupse, as in the sheep tick. 
Quiescent. At rest. 

Rostellum. A small beak or hook-like process. 
Rostrum. A beak-like process or appendage. 

Saproph5rte. Any vegetable organism living on dead or decaying organic matter. 
Schizogenesis. Reproduction by fission. 
Schizogony. Same as schizogenesis. 
Schizont. A malaria parasite of the asexual generation. 
Scolex. The head of a tapeworm, either in the larval or adult stage. 
Scutum. The dorsal shield or plate, present in certain ticks. 
Serrate. Notched or toothed on the edge. 
Somatic. Pertaining to the body as a whole. 
Somite. One of the longitudinal segments into which the body of annelid worms, 

arthropods, and vertebrates is divided. 
Spiracle. A breathing orifice, as in the tracheal openings of insects. 
Spore. A germ or seed of one of the lower animals or plants. 
Sporocyst. A case or cyst containing many spores. 
Sporogenesis. Reproduction by means of spores. 
Sporogony. Same as sporogenesis. 
Sporozoite. One of the young active spores of a sporozoan produced by division of 

the passive spores contained in the sporocyst. 
Sporulation. Spore formation. 
Stigmata. Small spots or marks; usually applied to the respiratory openings of 

insects; spii-acles. 
Strobila. An adult tapeworm. 
Suctorial. Adapted for sucking. 
Tarsus. In insects, the small segments forming the distal termination of the leg 

and articulating with the tibia. 



GLOSSARY 357 

Tergum. In zoology, the back. 

Terrestrial. Of or inhabiting the land or ground in distinction from trees, water, etc. 

Tibia. In insects, the fourth segment of the leg, articulating proximally with the 

femur and distally with the tarsi. 
Tracheae. The air-conveying tubules forming the respiratory system of insects and 

other arthropods. 
Trenchant. Sharp; cutting. 
Trochanter. In insects, the second segment of the leg, ai-ticulating proximally with 

the coxa and distally with the femur. 
Vacuole. A cavity or vesicle in cell protoplasm. 
Vermicide. A substance which kills worms; a drug to kill parasitic worms of the 

intestines. 
Vermifuge. A medicine that expels worms from the bodies of animals. 
Verminous. Infested with worms, or caused by worms, as verminous diseases. 
Viviparous. Producing living young by true birth, as in mammals, and not by 

hatching from eggs, as in oviparous and ovoviviparous animals; often applied 

to the bringing forth of young which have been hatched from eggs within the 

body of the parent. 
Zoophyte. Same as phytozoa. 
Zygote. The encysted stage of certain sporozoans after fertilization by a sperm 

cell and before division into spores. 



INDEX 



Acanthia lectularia, 90 
Acanthocephala, 217, 224, 300 
Acariasis, 96 
Acarina, 94 

parasitism of, 95 
Ades calopus, 29 
Agriostomum, 280 
Amblyonima, 142 

americanuni, 145 
Ameba,312,324 

budding, 313 

ectoplasm, 312 

encystation, 313 

endoplasm, 312 

fission, 313 

method of feeding, 313, 324 

morphologic characteristics, 312 

motility, 312, 324 

nucleus, 313 

pseudopodia, 312, 324 

reproduction, 313, 324 

respiration, 313 

streaming of cytoplasm, 312, 313, 
324 

vacuoles, 312, 313 
Ameba meleagridis, 325 
Amebic dj'sentery, 326 

in man, 326 
American dog tick, 143 
Amphistomidse, 157, 167 
Amphistomum cerv'i, 167 
Ankylostoma, 280 

canina, 291 

duodenale, 292 
Ankjdostomeae, 280 
Ankylostomiasis, 291 
Ankylostomimi stenocephalum, 292 



Annelida, 224, 307 
Anopheles, 26, 320 

maculipennis, 26 

punctipemiis, 2S 

c^uadrimaculatus, 26 
Anoplocephala mamillana, 175 

perfoliata, 174 

plicata, 175 
Anthelmintics, use and action 

of, 221 
Apterous insects, IS 
Arachnida, 94 

classification of, 96 
Arduenna, 228 

strongylina, 251 
Arduenninae, 228 
Argasidae, 97, 139 
Argas americanus, 139, 327 

miniatus, 139, 327 
Arthropoda, The, 13 

circulatory system, 14 

digestive system, 14 

excretory organs. 14 

musculature, 14 

nervous system, 14 

reproduction, 15 

res]Dirator}' system, 14 

sense organs, 15 

structure in general, 13 
Arthropoda as transmitters of infec- 
tious diseases, 313, 315 
Arthropoda, parasitic subgroups of 15 
Ascariasis, 229, 231 

importance of treatment, 233 

location of wonns, 229, 232 

occurrence, 231 

pathogenic influences, 232 



360 



INDEX 



Ascariasis of the cat, 237 

occurrence, 239 

treatment, 239 
Ascariasis of the dog, 237 

occurrence, 238 

post-mortem appearance, 239 

treatment, 239 ■ 
Ascariasis of the hog, 239 

effect, 240 

treatment, 241 
Ascariasis of the horse, l33 

control, 234 

etiology, 234 

occurrence, 233 

sj-mptoms, 233 

treatment, 234 
Ascariasis of the ox, 241 
Ascariasis of the sheep, 241 
Ascaridffi, 222, 229 

parasitism of, 229, 231 
Ascaris, 225, 229 

equi, 233 

equorum, 233 

lumbricoides, 229, 239 

marginata, 237 

megalocephala, 233 

mystax, 237, 239 

ovis, 229, 239 

suis, 229, 239 

suum, 229, 239 

vitulorum, 241 
Ascaroidea, 225 

Auricular mange of the cat, 118 
Auricular scabies of the rabbit, 118 



B 

Bacillary white diarrhea of chicks, 345 
Bacterium pullorum, 345 
Bathmostomum, 281 
Bedbug, The 8, 90 

as a pest of poultry, 90 

control, 92 

effect of bite, 90 



habits, 90 

reproduction and development, 90 
Beef measles, 174, 194, 195 

degeneration of cyst, 198 

development, 197 

federal regulations in regard to, 199 

influence of temperature, 198 

location and appearance, 197 

method of infection, 197 

occurrence, 196 

vitality of larvae, 198 
Beef and pork tapeworm, methods of 

differentiation, 200 
Beef tapeworm, 170, 195 
Belascaris marginata, 237 

mystax, 237, 239 

cati, 237, 239 
Bilharzia bovis, 168 

crassa, 168 
Bilharziosis, 168 
Black gnat, 31 
Blackhead of turkeys, 325 
Black horse fly, 35 

as a transmitter of disease, 36 

effect, 35 

life history, 35 

protection from, 36 
Blood fluke, 168 
Blow fly, 50, 52 

effect, 53 

reproduction and development, 52 
Bluebottle fly, 52 
Body louse, 79 
Body mange of poultry, 132 
Boophilus, 142 

annulatus, 144, 145, 314, 347 
bovis, 144, 145, 314, 347 
decoloratus, 316 
Bot flies, 53 
Bot, horse, 5, 53, 57 
Bothriocephalus latus, 185 
Brachiopoda, 155 

Bronchial and pulmonary strongylosis 
of cattle, 259 



INDEX 



361 



control, 264 

course, 260 

development, 263 

etiology, 263 

post-mortem appearance, 262 

prognosis, 260 

symptoms, 259 

sjTnptoms, duration of, 260 

treatment, 265 
Bronchial and pulmonary strongylosis 
of the horse, 261 

occurrence, 261 

symptoms, 261 
Bronchial and pulmonary strongylosis 
of the pig, 260 

occurrence, 260 

symptoms, 260 
Bronchial and pulmonary strongylosis, 
post-mortem appearance, 262 

control, 264 

development, 263 

etiology, 263 

treatment, 265 
Bronchial and pulmonary strongylosis 
of the sheep and goat, 256 

control, 264 

course, 259 

development, 263 

etiology, 263 

post-mortem appearance, 262 

prognosis, 259 

symptoms, 258 

treatment, 265 
Buffalo gnat, 31, 32 

control, 33 

effect, 33 

life history, 32 

occurrence, 32 

protection from, 33 

treatment, 34 
Brazilian septicemia of fowl, 327 
Bruce, investigations of, 45, 315, 330 
Bryozoa, 155 
Bunostomeae, 281 



Bunostomum trigonocephalum, 293 
phlebotomum, 293 



Calliphora vomitoria, 52 
Cardiac filariasis of the dog, 248 
Cardio-pulmonary strongylosis of the 
dog, 261 

post-mortem appearance, 263 

symptoms, 262 
Castor-bean tick, 143 . 
Cattle tick, 144, 145, 314, 347 
Cestoda, 159, 169 
Chabertia ovina, 287 
Chiggers, 96, 99 
Chloroform as ti-eatment for lung 

woi-ms, 266 
Choanotainia infundibuliformis, 189 
Chorioptes, 103 

parasitism, 103 

species, 103 
Chorioptes communis, 103 

var, bovis, 113 

var. equi, 108 

var. ovis, 112 
Chorioptic scabies of cattle, 113 

course, 113 

location, 113 

treatment, 120, 130 
Chorioptic scabies of the horse, 108 

course, 108 

diagnosis, 109 

lesions, 109 

prognosis, 109 

symptoms, 108 

transmission, 109 

treatment, 120, 129 
Chorioptic scabies of the sheep, 112 

course, 112 

prognosis, 112 

symptoms, 112 

transmission, 112 
Chrysomyia macellaria, 50 



INDEX 



Cimex lectularius, 90 

Cimicidffi, 22, 90 

Citto taenia denticulata, 185 

Classification of the Arachnida, 96 

Classification of the phylum Ccelhel- 

minthes, 222 
Classification of Insects, 20 
Classification of the phylum Platy- 

helminthes, 157 
Classification of the plyhun Protozoa, 

322 
Cnemidocoptes, 103, 132 

species of, 103, 132 
Cnemidocoptes gallinse, 103, 133 

mutans, 103, 132 
Coccidia, 322, 323, 337 

infection, 337 

life cycle, 322, 337 

parasitism, 337 

pathogenicitj^, 337 

reproduction, 337 
Coccidial enteritis of chicks, 345 

control, 346 

diagnosis, 345 

differentiation from bacillary white 
diarrhea, 345 

infection, 346 

post-mortem appearance, 345 

symptoms, 345 
Coccidiosis of the dog, 342 

investigations bj^ Hall and Wigdor, 
342 
Coccidiosis of cattle, 343 

of chicks, 345 

of the dog, 345 

of man, 342 

of the rabbit, 342 
Coccidium cuniculi, 342 

oviforme, 342 

tenellum, 345 

zurni, 343 
Cochliomyia macellaria, 50 
Ccelhelminthes, 216 

classification of, 156, 216, 222 



Coelom, 216 

Coenurosis, 204 

Coenurus, 173, 194, 204, 205 

Colic, thrombo-embolic, 288, 290 

Commensalism, 2, 7 

example of, 2, 7 
Compsomyia macellaria, 50 
Connective tissue mite of poultry, 

134 
Cooperia curticei, 268 

oncophora, 275 
Cryptobia, 329 
Cryptocystis, 178, 195 
Ctenocephalus cards, 65, 79 

felis, 65 
Culex and Anopheles, differentiation, 

28 
Culex pungens, 26, 28 
Culicidse, 20, 24 
Cylicostomese, 281 
Cylicostomum, 281 
Cysticercoid, 173, 178, 195 
Cysticercosis, 174, 195 
Cysticercus, 173, 174, 194, 195 

bovis, 174, 195, 197 

cellulosEe, 174, 195, 199, 202 

ovis, 203 

tenuicollis, 174, 179, 195, 203 

trichodectes, 79, 178, 183 
Cytoleichidffi, 134 
Cytoleichus nudus, 134 

D 

Davainea cesticillus, 190, 191 

echinobothrida, 191 

proglottina, 189 

tetragona, 190, 191 
Degeneration, parasitic, 3, 4 
Demodecidae, 96, 97, 103 
Demodectic mange, 96, 104 

of the dog, 116 

of the hog, 115 

of the sheeji, 112 



INDEX 



363 



Demodex foUiculorimi, 10-i 

var. canis, 104, 116 

var. ovis, 104, 112 

var. snis, 104, 115 
Depluming mange of poultry, 133 
Deplimaing mite, 101, 133 
Dermacentor, 142 

electus, 143 

occidentalis, 143 

reticulatus, 143 

variabilis, 143 
Dibothriocephalus latus, 185 
Dibothrium latum, 185 
Dicrocoelium lanceatum, 160, 163 
Dictyocaulus arnfieldi, 261 

filaria, 221, 256 

viviparous, 259 
DioctophjTiie renale, 296 

\'isceralis, 296 
Diphyllobothriasis, 185 

occurrence, 186 
Diphyllobothriidae, 160, 185 
Diphyllobothrium latum, 185 
Diplospora bigemina, 342 
Dipping vats, 126 
Dips, 48, 120, 125 
Diptera, 18, 20 

parasitic families of, 23 

parasitism of, 23 
Dipterous insects, 18, 23 
Dipylidium caninum, 68, 79, 178, 181, 

^183 
Dirofilaria inmiitis, 221, 248 
Dispharagus hamulosus, 254 

nasutus, 254 

spiralis, 254 
Distomese, 156, 157 
Distomiasis, 157, 163, 165 

of cattle, 166 

of the sheep, 165 
Distomvun americanum, 160 

hepaticum, 160 

lanceolatum, 160 

magnvun, 160 



Dochmiasis, 291, 292 
Doclmiius cernuus, 293 

radiatus, 293 

stenocephalus, 292 

trigonocephalus, 291 
Docophorus cygni, 86 

icterodes, 84 
Dourine, 333 

control, 336 

federal control of outbreaks, 333 

infection, 333, 334 

stages in, 334 

sjTiiptoms, 334 
Drepanidotsenia infundibulifomiis, 189 
D3^sentery of cattle, 343 



Earthwonn, 216 
Ecdysis, 13 

Echinococcosis, 183, 210 
Echinococcus, 173, 181, 183, 194, 210 

alveolaris, 212 

granulosus, 181, 183, 184, 194, 210 

multilocularis, 210, 212 

pohiiiorphus, 181, 183, 210 
Echinorh^^lcllus gigas, 306 
Ectozoa, 9 
Eimeria avimn, 345 

stiedse, 342 
El dourine, 333 
Endoparasites, 9 
Entameba, 326 

coli, 326 

histolytica, 326 
Entero-hepatitis of turkeys, 325 
Entozoa, 9 
Erratic parasites, 8 
Esophageal and gastric filariasis of the 
dog, 250 

course, 251 

development, 251 

occurrence, 250 

pathogenesis, 250 



364 



INDEX 



symptoms, 251 

treatment, 251 
Esophageal filariasis of cattle, 246 

of the dog, 250 

of the sheep, 246 

of the horse, 247 
European dog tick, 143 
EustrongyUdffi, 224, 296 
Eustrongylosis, 296 

occurrence, 296 

symptoms, 297 

treatment, 298 
Eustrongylus gigas, 296 

visceralis, 296 
Exoparasites, 9 



Fasciola americana, 160, 163 

hepatica, 5, 160 

lanceolata, 160, 163 

magna, 160, 163 
Fasciola hepatica, life history of, 5, 160 
Fasciola lanceolata, life history of, 163 
Fasciola magna, life history of, 163 
FascioHasis, 157, 163, 165 
Fascioliasis of cattle, 166 

control, 167 

symptoms, 166 

treatment, 168 
Fascioliasis of the sheep, 165 

control, 167 

course, 165 

prognosis, 166 

symptoms, 165 

treatment, 168 
FascioHdae, 157, 160 
Filaria, 227 

bancrofti, 249 

cervina, 248 

equina, 244 

immitis, 248 

labiato-papillosa, 248 

sanguinis hominis, 249 

sanguinolenta, 250 



Filariae of cattle, 246 

of the dog, 248 

of the hog, 251 

of the horse, 244 

of poultry, 254 

of the sheep, 246 
Filariasis of cattle, 246 

effect, 247, 248 

occurrence, 247, 248 
Filariasis of the deer, 248 
Filariasis of the dog, 248 

diagnosis, 249, 251 

occurrence, 248, 250 

pathogenesis, 249, 250 

theories as to infection, 249 

treatment, 250, 251 
Filariasis of the hog, 247, 251 

control, 253 

occurrence, 252 

treatment, 254 
Filariasis of the horse, 244 

effect, 245, 246 

occurrence, 244, 245, 246 

treatment, 246 
Filariasis of poultry, 254 
Filariasis of the sheep, 246 

effect, 247 

occurrence, 247 
Filariidse, 222, 244 

parasitism of, 244 
Filarioidea, 227 
Fixed parasites, 8 
Flagellata, 322, 326 
Fleas, 65 

as carriers of disease, 66 

control, 68 

habits, 66 

household infestation, 69 

reproduction and development, 
65,66 

species, differential characters of, 65 

treatment, 68 

usual hosts, 66 

vitality, 68 



INDEX 



365 



Flesh flies, 50, 52 

protection from, 52 

reproduction and development, 52 
Flies, 11,23,35 
Fluke, liver, 5, 156, 160, 163 
Fly, house, 11,37, 189 
Follicular mange of the dog, 116 

course, 116 

symptoms, 116 

transmission, 117 

treatment, 130 
Follicular mange of the hog, 115 

occurrence, 115 

treatment, 130 
Follicular mange mite, 103 
Follicular mange of the sheep, 112 

location, 112 

prevalence, 112 
Forked worm of fowl, 293 
Fowl septicemia, 327, 345 
Fowl tick, 139 

control, 140 

development, 140 

effect, 140 

habits, 140 

occurrence, 140 
Fumigation treatment in venninous 
bronchitis, and pneumonia, 265 



Oaigeria, 281 
Gamasidse, 96, 98 
Gamasid mifes, 96, 98 
Gastric filariasis of the dog, 250 
Gastric filariasis of the horse, 245, 246 
Gastric and intestinal filariasis of the 

hog, 251, 252 
Gastro-intestinal strongylosis of cattle, 
272 

control, 276 

development, 276 

etiology, 276 

occurrence, 275 



pasture rotation, 277 

post-mortem appearance, 275 

symptoms, 275 

treatment, 277 
Gastro-intestinal strongylosis of the 

goat, 268 
Gastro-intestinal strongylosis of the 
sheep, 268 

control, 276 

development, 276 

etiology, 276 

occurrence, 271 

pasture rotation, 277 

pathogenesis, 272 

post-mortem ap])earance, 275 

sjin])toms, 272 

treatment, 277 
Gastrophilus equi, 5, 53 

hemorrhoidalis, 57 

intestinalis, 5, 53 
Gid of cattle, 205, 209 
Gid of the sheep, 204 

the coenurus, 205 

control, 209 

development, 206 

occurrence, 205 

post-mortem appearance, 207 

symptoms, 208 

treatment, 209 
Gigantorhynchus hirudinaceus, 306 
Glossary, 353 
Glossina, 44, 314 

longipalpis, 44, 46 

morsitans, 44, 46, 330 

palpalis, 44, 46 
Gnat, buffalo, 31, 32 
Gnathobdellidc^, 224, 308 
Gnats, 31 
Gongylonema, 227 

scutata, 246 
Gongylonemina', 227 
Goniocotes abdominalis, 82 

compar, 86 

gallinre, 82 



366 



INDEX 



gigas, 82 

hologaster, 82 
Goniodes damicornis, 86 

stylifer, S4 
Grammoceplialus, 281 
Green-head fly, 36 
Gyalocephalus, 281 

H 

Habronema megastoma, 245 

microstoma, 246 
Haemaphysalis, 142 
Hcematobia serrata, 41 
Hsematopiims asini, 73 

eurj-stermis, 74 

macroeephalus, 73 

suis, 77 

urius, 77 
Hsemonchus coutortus, 268 
Hsemopis sanguisuga, 308 
Harvest mites, 99 

effect, 100 

habits, 100 

protection from, 100 

treatment, 100 
Heel fly, 57 
Hehninthes, 9 
Helotism, 7 
Hematic filariasis of the dog, 248 

diagnosis, 249 

occurrence, 248 

pathogenesis, 249 

theories as to infection, 249 

treatment, 250 
Hematic filariasis of man, 249 
Hemiptera, 22, 89 
Hemosporidia, 323, 347 

dift'erence in m:de of infection from 
Coccidia, 337, 347 

relationship to other groups, 336, 
347 

relative pathologic importance, 347 
Hepatic coccidiosis of rabbits, 342 



Herpetomads, 316 

experiments -with, 316 
Herpetomonas donovani, 316 
Heterakiasis of poultr}-, 242 

sj-mptoms, 243 

treatment, 243 
Heterakidse, 222, 242 
Heterakinse, 226 
Heterakis, 226 

inflexa, 242 

papillosa, 242 

perspicillum, 242 

vesicularis, 242 
Heteroxenous parasites,[S 
Hippoboscidse, 21, 47 
Hirudinea, 224, 307 
Hirudo medicinahs, 309 
Hook wonn, 291, 292 
Horn fly, 41 

control, 43 

effect, 42 

habits, 41 

life histon,', 41 

occurrences, 41 

protection from, 43 
Horse bot flies, 5, 53 

effect of bots, 55 

habits, 53 

life historj', 54 

treatment, 56 
Horse leech, 308 

efi'ect, 309 

mode of infestation, 309 

occurrence, 309 

treatment, 309 
House flj', 11, 37, 189 

as a transmitter of infectious dis- 
eases, 11, 38, 189 

control, 38 

habits, 38 

life historj', 37 

longevity, 37 

protection from, 38 
Hvalomma, 142 



INDEX 



367 



Hydatid disease, 173, ISl, 1S3, 194, 210 

control, 214 

development, 212 

the echinococcus, 210 

longe\'ity of cyst, 213 

occurrence, 210 

post-mortem appearance, 213 

sj-mptoms, 214 
Hjinenolepis carioca, 190, 191 
HjTnenoptera, 18 
Hypoderma bo-\ds, 58 

lineata, 57 



Imago, The, 19 
Incidental parasites, 8 
Infectious entero-hepatitis of turkeys, 
325 

control, 326 

course, 325 

infection, 325 

post-mortem appearance, 325 

symptoms, 325 

treatment, 326 
Insecta, 15 

classification of, 20 
Insects, 15 

development, 18 

duration of life, 19 

growth, 19 

lar\'2e, 18 

metamorphosis, 18 

mouth parts, 16 

parasitic subgroups, 20 

reproduction, 18 

structure, 15 
Internal parasites, 155 
Intestinal strongj'losis of the cat, 291 

of cattle, 272, 285 

of the dog, 291 

of the goat, 268, 281, 287 

of the hog, 287 

of the horse, 288 

of the sheep, 268, 281, 287 



Intratracheal injections, 265 
Introduction, 1 
Isospora bigemina, 342 
Itch mites, 101 
Ixodes, 142 

hexagonus, 143 

ricinus, 143 
Ixodidjp, 96, 97, 136, 141 
Ixodoidea, 96, 97, 136, 139 

K 

Kala-azar, 316 

Kerosene emulsions, 48 

Kerosene in mosquito control, 25, 

31 
Kidney womi of the dog, 296 
Kidney worm of the hog, 295 



Laminosioptes cysticola, 134 
Lan'se, dipterous, 50 
Lar\'3e, insect, 18 
Leeches, 216, 307 
Leg mange of poultrj-, 132 
Leishmania donovani, 316 
Leptus autumnalis, 100 
Lice, 70 

biting, 71 

sucking, 70 
Lice of poultry, 82 

control, 88 

occurrence, 82 

treatment, 88 
Life, degeneracj' in mode of, 1 
Life history of beef tapeworm, tabular 

re\iew, 172 
Life histories of dog tick and Texas 

fever tick compared, 151 
Life historj' of Echinococcus granu- 
losus, tabular review, 213 
Life historj' of gid tapeworm, tabular 
review, 207 



368 



INDEX 



Life history of horse botfly, tabular 

review, 55 
Life history of liver fluke, tabular 

review, 163 
Life history of sheep botfly, tabular 

review, 63 
Life history of Trichinella spiralis, 

tabular review, 303 
Lime and sulphur dips, 122, 125 

method of preparing, 125 
Linguatula rhinaria, 94, 153 
Lin;uatulida, 153 
Linguatulidse, 97 
Linognathus pedalis, 76 

piliferus, 78 

stenopsis, 77 

vituli, 74 
Liotheidse, 22, 71 
Lipeurus anatis, 84 

baculus, 86 

caponis, 83 

columbae, 86 

heterographus, 83 

meleagridis, 84 

polytrapezius, 84 

squalidus, 84 

variabilis, 83 
Lissoflagellata, 328 
Liver flukes, 5, 156, 160 

infection, 160, 164 

life history, 5, 160 

losses from, 162 

migrations and pathogenesis, 164 

prevalence, 162 

prevalence in United States, 164 
Lobosa, 322, 324 
Lone star tick, 145 
Lousiness, 71 
Lung worms, 256 

control, 264 ' 

development, 256, 263 

method of infection with, 256, 
263 
Lyperosia irritans, 41 



M 



Maladie du coit, 333 
Malaria, 26, 318 
Malaria, latent, 322 
Malaria organisms, the asexual cvcle, 
318, 319 
the gametocytes, 319 
hberation of the merozoites, 319 
the macrogametocyte, 319 
the merozoites, 319 
the microgametes, 319 
the microgametocyte, 319 
relation of liberation of merozoites 

to chill, 319 
repeating of cycle, 319 
the schizont, 319 
the signet ring stage, 319 
the sporozoites, 319, 320 
Malaria organisms, life history, 318 
Malaria organisms, the parthenoge- 

netic phase of, 322 
Malaria organisms, the sexual cycle, 
320 
fertilization of the macrogamete, 

320 
fomiation of cyst, 320 
formation of macrogamete, 320 
formation of the microgametes, 

320 
fonnation of the sporoblasts, 320 
formation of the sporozoites, 320 
liberation pf the sporozites, 320 
the microgametoblast, 320 
migration of ookinete, 320 
the ookinete or zygote, 320 
passage of sporozoites to salivary 

glands of mosquito, 320 
relationship of anopheline mosquito 
to, 26, 313, 319, 320 
Mai de caderas, 332 
infection, 333 
occurrence, 332 
symptoms, 332 



INDEX 



Mallophaga, 21, 71 
Mange, 96, 101, 102, 103, 104, 112, 
113, 114, 115, 116, 117, 118 

cnemidocoptic, 132 

follicular, 102, 112, 115, 116 

notoedric, 118 

sarcoptic, 102, 104, 112, 114, 121 
Mange of the body of poultry, 
133 

course, 133 

symptoms, 133 

treatment, 133 
Mange of the cat, 117 

course, 118 

diagnosis, 118 

treatment, 120, 123 
Mange of cattle, 114 

treatment, 120, 124 
Mange of the dog, 115, 116 

course, 115, 116 

lesions, 115, 116 

symptoms, 115, 116 

transmission, 115, 117 

treatment, 120, 123, 130 
Mange of the goat, 1 13 

treatment, 120, 124 
Mange of the hog, 114, 115 

sjTnptoms, 114, 115 

transmissions, 114 

treatment, 120, 122, 130 
Mange of the horse, 104 

control, 122 

development, 105 

diagnosis, 105 

lesions, 105 

prognosis, 107 

symptoms, 104 

transmission, 107 

treatment, 120, 121 
Mange of the legs of poultry, 132 

course, 132 

symptoms, 132 

treatment, 132 
Mange mites, 96, 103, 132, 134 



Mange of poultry, 132, 134 
Mange of tlie rabbit, 118 

treatment, 120, 124 
Mange and scab mites, 96, 101, 102, 
103, 117, 132, 134 

development, 101, 103 

reproduction, 101, 103 
Mange of the sheep, 112 

treatment, 120, 124 
Margaropus, 142, 145 

annulatus, 144, 145, 314, 347 
Mastigophora, 322, 326 
Measles, 174, 194, 195 

ofman, 174, 194, 195 

of the ox, 174, 195 

of the pig, 174, 195 

of the sheep, 174, 195 
Medicinal leech, 309 
Melophagus ovinus, 4, 47, 76 
Menopon biseriatum, 83 

pallidum, 83 
Menopum biseriatum, 83 

pallidum, 83 

trigonocephalum, 83 
Metamorphosis, insect, 19 

complete, 19 

incomjjlete, 19 
Metastrongylidae, 227 
Metastrongylina>, 223, 256 

life history, 256, 263 
Metastrongylus, 227 
Metazoa, 311 
Miescher's tube, 350 
Mites, 94 
MoUuscoidea, 155 
Molting, 13 
Moniezia alba, 176 

denticulata, 185 

expansa, 176 

planissima, 176 
Monoxenous parasites, 8 
Mosquitoes, 11, 24 

breeding habits, 24 

control, 31 



370 



INDEX 



Culex and Anopheles, differentia- 

• tion, 28 

development, 25 

effect upon live stock, 31 

lan-se, 24 

pathologic importance, 26 

protection against, 31 

pupse, 25 

range, 24 

relationship to filariasis, 26 

relationship to malaria, 26, 313, 320 

relationship to yellow fever, 26, 29 
Multiceps gaigeri, 181 

multiceps, 179, 194, 204, 206, 207 

serialis, 179 
Musca domestica, 11, 37, 189 

vomitoria, 52 
Muscidffi, 20, 37 
MutuaHsm, 2, 7, 

example of, 2, 7 
Myasis, 50 



Nagana, 45, 314, 330 

etiology, 45, 314, 330 

investigations by Bruce, 45, 314, 
330 

occurrence, 330 
Nemathehninthes, 155, 216, 222 
Nematoda, 217, 222, 
Nematode worms, parasitism in gen- 
eral, 219 

adaptabilitj' to changed environ- 
ment, 221 

factors influencing injury to host, 
220 

host limitations, 220 

infection, 219, 220 

treatment in general, 221 
Nematodirus fiUcollis, 273 
Neosporidia, 336, 350 
Net tick, 143 
Nodular disease, 281 



Nodular strongylosis of cattle, 285 

of the goat, 281 

of the hog, 287 
Nodular strongylosis of the sheep, 281 

development, 283 

importance, 284 

occurrence, 283 

post-mortem appearance, 284 

sjTiiptoms, 284 

treatment, 285 
Notoedres, 101, 117 

var. cati, 117, 118 

var. cuniculi, 118 

parasitism of, 103 
Notoedric mange, treatment of, 120, 
123, 124 



Obhgate parasites, 8 

Ocular filariasis of the horse, 245 

of the ox, 248 
(Esophagostomese, 280 
(Esophagostomiasis of cattle, 285 

of the goat, 281 

of the hog, 287 

of the sheep, 281 
CEsophagostomum, 255, 280 

columbianum, 281 

dentatiun, 287 

inflatum, 285 

radiatimi, 285 

subulatum, 287 

venulosum, 282 
(Estridse, 21, 53 
(Estrus o\as, 62 
Optional parasites, 8 
Organic multiplication, influences re- 
stricting, 1 
Ornithobius bucephalus, 86 
Ornithodorus megnini, 140 
Ornithonomus CA'-gni, 86 
Ostertagia marshalli, 269 

ostertagi, 272 



INDEX 



371 



Otacariasis of the cat, 118 
occurrence, 118 
treatment, 131 
Otacariasis of the dog, 117 

occurrence, 117 

prognosis, 117 

sjTnptoms, 117 

treatment, 131 
Otacariasis of the rabbit, 1 18 

course, 118 

sjinptoms, 119 

treatment, I'M 
Otobius megnini, 159 
Otodectes, 101, 103, 115, 117 

parasitism, 103 
Otodectes cynotis, 115, 117 
Oviparous, application of the term, 

219 
0^^position, 18, 219 
Ovipositor, 18 
Ovo\aviparous, application of the 

term, 219 
Ox bot flies, 57 

effect of bots, 62 

life history, 58 

occurrence, 57 

treatment, 62 
Ox warbles, 53, 57 
Oxyuriasis, 236 

effect, 236 

occurrence, 236 

treatment, 237 
Oxyuridffi, 222, 235 
OAjoirinse, 226 
Oxynris, 226 

curv'ula, 235 

equi, 235 

mastigodes, 235 



Parasites, alternation of hosts in, 5, 
Parasites, determinate transitory, 8 

determinate erratic, 8 

erratic, 8 



fixed, S 

heteroxenous, 8 

incidental, 8 

monoxenous, 8 * 

optional occasional, 8 

permani nt, 8 

stray, 8 
Parasites, development of patho- 
genicity in, 315 
Parasites, external, 9 

internal, 9 
Parasites, factors influencing injury 
by, 10, 315 

age of host, 11 

location, 10, 315 

movements, 10 

nature of food, 10 

number present, 10 
Parasites, influence upon host, 10, 315 
Parasites, systematic position of, 6 
Parasitic diseases, terms used in, 9 
Parasitism, 2, 3, 7, 315 

adaptation to, 3, 4, 315 

degeneration in, 3, 4 

factors leading to, 1, 6, 315 

forms of, 7 

functions involved in adaptation 
to, 3 

range of, 3 

reproductive function in, 4 
Parasitism, evolution of, 315 
Parthenogenesis, 15, 322 
Pathogenic Protozoa, 311, 324 

arthropods as carriers of, 23, 315 
PedicuHdse, 21, 70 
Pediculosis of the cat, 79 

control, 80 

occurrence, 79 

treatment, 81 
Pediculosis of cattle, 74 

control, SO 

indications of, 75 

location, 75 

treatment, 81 



372 



INDEX 



Pediculosis of the dog, 78 

control, 80 

effect, 78 

location, 78 . 

treatment, 81 
Pediculosis of the goat, 77 

control, 80 

effect, 77 

occurrence, 77 

treatment, 80 
Pediculosis of the hog, 77 

control, 80 

effect, 77 

occurrence, 77 

treatment, 81 
Pediculosis of the horse, 72 

control, 80 

indications of, 73 

location, 73 

treatment, 80 
Pediculosis of mammals, 71 

complications, 71 

effect, 72 

indications of, 72 

predisposing factors, 71 

treatment, 80 
Pediculosis of man, 79 
Pediculosis of poultrj^, 82 

control, 88 

dust bath in, 88 

effect, 82 

indications of, 82 

occurrence, 82 

parts attacked, 82 

sodium fluoride in treatment of, 
88 

treatment, 88 
Pediculosis of the sheep, 76 

control, 80 

occurrence, 77 

treatment, 80 
Pediculosis, control and treatment, 80 
Pediculus capitis, 79 

corporis, 79 



humanus, 79 
vestimenti, 79 
Permanent parasites, 8 
Pharyngeal filariasis of the hog, 247 
Philopteridse, 21, 71 
Philopterus cygni, 86 

icterodes, 84 
Phthiriasis, 71, 79 
Phthirius inguinalis, 79 

pubis, 79 
Physocephalus sexalatus, 252, 253 
Phytoparasites. 7 
Piroplasma bigeminum, 313, 347 
Plasmodium, 313, 318 

falciparum, 318 

malarise, 318 

prsecox, 318 

yivax, 318 
Platyhelminthes, 155, 157 

classification of, 155, 157 
Plerocercoid, 173, 195 
Polystomese, 156 
Polyzoa, 155, 159 
Pork measles, 174, 195, 199 

degeneration of cyst, 202 

development, 202 

diagnosis, 202 

influence of temperature upon larvse, 
202 

locatin and appearance of cysts, 
201 

method of infection, 201 

occurrence, 200 

symptoms, 202 

vitality of larvse, 202 
Pork tapeworm, 195, 199 
Poultry mite, 98 

control, 9 

development, 99 

effect, 99 

habits, 98 

occurrence, 98 

reproduction, 99 
Predaceous animals, 3, 9 



INDEX 



373 



Protozoa, 311 

carj'ozoic, 322 

coelozoic, 322 

colonization of, 311 

cytozoic, 322 

differentiation from Metazoa, 311 

enterozoie, 322 

hematozoic, 322" 

investigations as to patiiogenicity, 
313, 315 

investigations as to pathogenicity in 
the United States, 314 

natural classification of, 322 

parasitism, 313 

pathogenicity, 313, 315 

pathogenic classificarion of, 322 

specialization in, 311 
Protozoa, classification of, 322 
Protozoa, methods of reproduction in. 
313, 318, 327, 329, 336, 337 

asexual method, 318, 319, 337 

multiplicative cycle, 318, 319, 337 

propagative cycle, 318, 320, 337 

sexual method, 318, 320, 337 

sporulation, 318, 319, 320, 336, 337 
Pseudopodia, 312, 324 
Psoroptes, 101, 102 

parasitism, 102 

species of, 103 

varieties, 103 
Psoroptes conmiunis, 103 

var. bovis, 103, 113 

var. cuniculi, 103, 118 

var. equi, 103. lOS 

var. ovis, 103, 109 
Psoroptic scabies of cattle. 113 

course, 113 

s\nnptoms, 113 

treatment, 120, 128 
Psoroptic scabies of the goat, 113 
Psoroptic scabies of the horse, 108 

lesions, 108 

transmission, 108 

treatment, 120. 129 



Psoroptic .scabies of the rabbit, 118 

course, 118 

sjinptoms, 119 

treatment, 120, 131 
Psoroptic scabies of the sheep, 109 

after-treatment, 128 

course, 110 

historical, 110 

lesions, 110 

prognosis, 110 

SNinptoms, 110 

treatment, 120, 124 
Pubic louse, 79 
Pulex irritans, 65 

serraticeps, 65 
Pulicida^, 21, 65 
Pulmonary strongylosis of the cat, 262 

.s\ini)toms, 262 
Pupation, 19 
Pyrosoma bigeminum, 313 

R 

Red bugs, 99 

Red dysentery of cattle, 343 

Red mange of the dog, 104, 116 

Red-tailed bot fly, 57 

Remora, 2 

Reproduction, oviparous, 18, 219 

ovoviparous, 18,219 

pupiparus, 4, 18 

viviparous, 18, 219 
Respirator^' mite of fowl, 134 
Rhipicentor, 142 
Rhipicephalus, 142 
Rhizopoda, 322, 324 

reproduction in, 324 
Rhvnchobdellidsp. 308 



Sarcocystis bertrami, 351 
blanchardi, 351 
miescheriana, 351 
tenella, 351 



374 



INDEX 



Sarcophaga sarraceiiise, 52 
Sarcoptes, 101 

parasitism, 102 

species of, 102 

varieties, 102 
Sarcoptes minor var. cati, US 

minor var. cuniculi, 118 

mutans, 132 
Sarcoptes scabiei, 102 

var. boA-is, 114 

var. canis, 115 

var. equi, 104 

var. o\as, 112 

var. suis, 114 
Sacroptic mange, 101, 102 

of cattle, 114 

of the dog, 115 

of the goat, 113 

of the hog, 114 

of the horse, 104 

of the sheep, 112 
Sarcoptidse, 96, 101 
Sarcosporidia, 323, 336, 350 

development, 350 

muscles commonl}^ invaded, 350 

parasitism, 350 

pathologic importance, 351 

theorv^ as to source and mode of 
infection, 351 

toxicity, 351 
Sarcosporidiosis, 350 

mode of infection, 352 
Sarcosporidiosis of cattle, 351 

of the horse, 351 

of mice, 352 

of the pig, 351 
of the sheep, 351 
Scabies, 96 
Scab mites, 94, 96 
Scaly leg of poultry, 132 
Schistosoma bovis, 16S 
Schistosomidse, 157 
Schizogony, 318, 319, 337 
Sclerostomiasis, 288 



Sclerostomum edentatum, 289 
equinum, 288 
hypostomum, 287 
tetracanthum, 289 
vulgare, 289 
Scorpion, 94 
Screw womi fly, 50 
development, 50 
effect, 50 
occurrence, 50 
protection from, 51 
reproduction, 50 
treatment, 51 
Sea anemone and hermit crab, 

mutualism of, 2 
Septicemia of chicks, 345 
Setaria labiato-papillosa, 244 
Sheep bot fly, 62 
effect of bots, 63 
life liistory, 62 
occurrence, 62 
prevention, 64 
treatment, 64 
Sheep measles, 174, 195, 203 
Sheep measles, muscular, 203 
control, 204 
derivation, 203 
development, 204 
economic importance, 204 
occurrence, 203 
Sheep measles, \dsceral, 203 
control, 203 
development, 203 
method of infection, 203 
occurrence, 203 

relation to food sanitation, 203 
sjTiiptoms, 203 
Sheep staggers, 204 
Sheep "tick," 4, 47 
control, 48 
effect, 48 
life history, 4, 47 
occurrence, 47 
treatment, 48 



INDEX 



375 



Simplicity, primitive and degenera- 
tive, 3 
Simuliidte, 20, 31 
Simulium pecuarmn, 32 
Siphonaptera, 21, 65 
Siphunculata, 21, 70 
Sleeping sickness, 46, 314 
Southern cattle fever, 145, 313, 347 
Southern cattle tick, 144, 145, 347 
Spider, 94 
Spinose ear tick, 140 

development, 141 

effect, 141 

habits, 141 

occurrence, 141 
Spirocheta gallinarum, 327 

marchouxi, 327 

theileri, 316 
Spirochetida, 315, 322, 327 

as blood parasites, 315, 316 

evolution of pathogenicity in, 315 

pathogenicity, 315, 327 

transmission, 316 
Spirochetosis, 315, 327 

of fowl, 327 
Spiroptera megastoma, 245 

microstoma, 246 

sanguinolenta, 250 

scutata, 246 

sexalata, 252 

strongylina, 251 
Spirura, 227 
Spiruridse, 227 
Spirurinse, 227 

Splenic fever of cattle, 145, 313, 347 
Sporogony, 318, 320, 337 
Sporozoa, 323, 336 

relationship to other forms, 336 

reproduction in, 318, 322, 336, 337 
Stable fly, 39, 332 

control, 40 

effect, 40 

life historj^, 39 

occurrence, 40 



protection from, 41 

relation to infectious diseases, 40 
332 
Staggers of sheep, 204 
Stegomya calopus, 29 

fasciata, 29 
Stephanurus dentatus, 295 
Sting, insect, 18 
Stomach wonns, pasture rotation 

in eradication of, 277 
Stomach worms of cattle, 272 

of the goat, 268 

of the sheep, 268 
Stomoxys calcitrans, 39, 315, 332 
Stray parasites, 8 
Strongjdea, 280 
Strongj'les of the resj^iratory system, 

255, 256 
Strongj'lidcc, 223, 255 
]3arasitism of, 255 
Strongj'linse. 223, 280 
Strongyloidca, 226 
Strongj'losis, 255 

bronchial, 256 

gastric, 268 

intestinal, 268, 280 

pulmonary, 256 

renal, 295, 296 

vascular, 289 
Strongj'losis, bronchial and pulmonary 

of cattle, 259 

of the goat, 256 

of the horse, 261 

of the pig, 260 

of the sheep, 256 
Strongylosis of the intestines of the 

cat, 291 
Strongylosis of the intestines of the 
dog, 291 

development, 292 

occurrence, 292 

post-mortem appearance, 292 

sjTiiptoms, 292 

treatment, 293 



INDEX 



Strongylosis of the intestines of the 
horse, 288 

development, 289 

post-mortem appearance, 290 

sjTiiptoms, 290 

treatment, 291 
Strongylosis of the large intestine of 

the goat, 287 
Strongylosis of the large intestine of 
the sheep, 287 

occurrence, 288 
Strongylosis, pulmonary of the dog, 
261 

of the cat, 262 
Strongylosis, tracheal, of poultry, 293 
Strongylus, 226, 255 

annatus, 288 

arnfieldi, 261 

capillaris, 258 

colubrifonnis, 271 

contortus, 268 

curticei, 268 

edentatus, 289 

equinus, 288 

filaria, 256 

fiUcollis, 273 

instabilis, 271 

micrurus, 259 

oncophora, 275 

ostertagi, 272 

paradoxus, 260 

pusillus, 262 

rufescens, 257 

vasorum, 261 

ventricosus, 268 

vulgaris, 255, 289 
Strongyl worms, importance of, 255 

infestation, conditions favoring, 255 
Struggle for existence, 1 
Subcutaneous mite of fowl, 134 
Summaries on development of Texas 

fever tick, 149, 150 
Surra, 314, 315, 332 

course, 332 



flies as carriers of, 314, 315, 332 

infection, 332 

occurrence, 332 

sjinptoms, 332 
Symbiosis, 2, 7 

phases of, 2 
Symbiotes, 103 

communis, 103 
Sjaigameae, 281 
Syngamosis, 293 
Syngamus, 281, 294 

bronchialis, 293, 294 

trachealis, 293, 294 
Synopsis of tape wo mi larvse, 194 
Synthetocaulus abstrusus, 262 

capillaris, 258 

rufescens, 257 



Tabanida", 20, 35, 332 
Tabanus atratus, 35 

lineola, 36 

striatus, 332 
Table of principal tapeworais and 

larvae, 173 
T»nia, 173 
Taenia alba, 176 

cesticillus, 190 

coenurus, 179 

crassicoUis, 184 

cucumerina, 178 

echinobothrida, 191 

echinococcus, 181, 210 

expansa, 176 

fimbriata, 174, 176, 177 

hydatigena, 178, 195, 203 

mamillana, 175 

marginata, 178 

mediocanellata, 195 

ovis, 204 

perfoliata, 174 

plicata, 175 

proglottina, 191 



INDEX 



377 



saginata, 170, 174, 195 

serialis, 179 

serrata, 179 

solium, 174, 195 

tsenisefomiis, 184 

tetragona, 190 
Ta^niasis, 172, 174 

prevention, 187 

treatment in general, 186 
Tffniida", 20, 159, 170 

life history of, 169, 171 
Tail scab of cattle, 113 
Tapeworm larvae, 173, 174, 194 

synopsis of, 194 
Tapeworms, 5, 169 

classification of, 159, 173 

cystic fonns, 173, 194 

degeneration of, 5, 172 

parasitism of, 5, 172 
Tapewonns of the cat, 184 

occurrence, 184 

symptoms, 184 

treatment, 188 
Tapewonns of cattle, 176 

occurrence, 177 

symptoms, 177 

treatment, 188 
Tapewonns of chickens, 189 

control, 192 

diagnosis, 192 

investigations as to, 189 

occurrence, 189, 191 

sjTnptoms, 191 

treatment, 192 
Tapewonns of the dog, 178 

diagnosis, 183 

occurrence, 181 

pathogenesis, 182 

prevention, 187 

relation to human infection, 183 

s\inptoms, 181 

treatment, 186 
Tapewonns of the horse, 174 

occurrence, 175 



symptoms, 175 

treatment, 188 
Tapewonns of the rabbit, 185 

diagnosis, 185 

occurrence, 185 
Tapewonns of the sheep, 176 

occurrence, 177 

symptoms, 177 

treatment, 188 
Telosporidia, 336 
Tetrameres fissispina, 254 
Texas fever, 11, 145, 313, 347 

acute type, 349 

chronic tjije, 349 

development of the piroplasma, 348 

distribution, 348 

infecting organism of, 347 

influence of climate upon, 349 

occurrence, 348 

l)eriod from exjiosure to develop- 
ment, 348 

prevention, 350 

relationship of the tick to transmis- 
sion, 145, 314, 347 

sjinptoms, 349 

treatment, 350 
Texas fever tick, 11, 144, 145, 314, 347 

losses occasioned by, 151 

progress in eradication of, 152 

publications relative to, 145 
Texas fever tick, life history of, 148, 347 

adult period, 150 

hatching period, 148 

incubation period, 148 

larval period, 150 

longevity period, 149 

nonparasitic development, 148 

njinphal period, 150 

oviposit ion period, 148 

parasitic development, 149 

preoviposition jieriod, 148 

summary of nonparasitic periods, 
149 

summary of parasitic jieriotls, 150 



378 



INDEX 



Thorn-headed womi, 306 
Thorn-headed womi of the hog, 303 

life history, 306 

occurrence, 306 

pathogenesis, 306 

symptoms, 306 

treatment, 307 
Thj^sanosoma actinioides, 174, 176, 

177 
Tick fever, 365, 145, 313, 347 
Ticks, 136 

classification of, 136 

stages in development of, 139, 145 

structure of, 136 
Tick, Texas fever, 144, 145, 314, 

347 
Toxascaris limbata, 238 

marginata, 238 
Toxins, parasitic, 11, 174, 220 
Tracheal injections, 265 
Tracheal strongjdosis of fowl, 293 

development, 294 

lesions, 294 

occurrence, 294 

prevention, 295 

symptoms, 294 

treatment, 295 
Transmigration, 8 
Trematoda, 156, 157 
Trichina spiraHs, 220, 299, 301 
Trichinella, 225 
Trichinella spiralis, 220, 299, 301 

degeneration of cyst of, 303 

development of cyst of, 302 

life liistory, 302 

location of cysts of, 303 

migration, 220, 302 
Trichinellidse, 224, 299 
Trichinellinffi, 225 
Tricliinelloidea, 225 
Trichinosis, 220, 301 

intestinal, 302 

method of infection, 302, 304 

muscular, 302 



occurrence, 301, 304 

prophj-laxis, 305 

symptoms in the hog, 304 

treatment, 305 
Tricliinosis in man, 304. 
Trichocephalus affinis, 299 

crenatus, 299 

depressiusculus, 300 
Trichodectes clmiax, 77 

equi, 73 

latus, 78 

panmipilosus, 73 

pilosus, 73 

scalaris, 75 

sphserocephalus, 76 

subrostratus, 79 
Trichostrongylidae, 226 
Trichostrongylinse, 223, 268 
Trichostrongjdus, 226 

instabilis, 271 
Trichurinse, 225 
Trichuris, 225 

crenatus, 299 

depressiusculus, 300 

o\as, 299 
Trinoton lituratum, 86 

luridum, 84 
Trinotum lituratum, 86 

luridum, 84 
Triodontophorus, 281 
Trombidiidffi, 96, 99 
Trombidium holosericeum, 100 
Tropisurus fissispinus, 254 
Trypanoplasma, 328 
Trypanosoma, 328 

americanum, 336 

brucei, 314, 330 

equinum, 332 

equiperdum, 333 

evansi, C14, 332 

gambiense, 314 

le^visi, 314 

theileri, 329 
Tiypanosomatida, 322, 328 



INDEX 



379 



Trypanosomes, 314, 32S 

classification of, 322, 32S 

morphology of, 328, 329 

parasitism of, 314, 329 

reproduction, 329 

transmission, 314, 329 

transmission by flies, 45, 314, 329 
Trypanosomes, flies as carriers of, 
45, 314, 329 

leeches as carriers of, 314 

lice as carriers of, 314 

mosquitoes as carriers of, 314 
Trj'-panosomiasis, 11, 45, 314, 328 

human, 46, 314 

investigations by Bruce, 45, 314, 330 
Tsetse flies, 44, 314, 330 

control, 43 

method of reproduction, 44 

relationship to trypanosomiasis, 45, 
314, 330 
Tsetse fly disease, 44, 314, 330 

investigations by Bruce, 44, 314, 
330 
Tunicata, 3 
Tumsick, 204 
Typhoid fever, 11, 



U 



Uncinaria, 281 
Uncinariasis, 291 



Uncinaria canina, 291 
cernua, 293 
radiata, 293 
stenocephala, 292 
trigonocephala, 291 

V 

Vermes, 155 

Vermicides, use and action of, 121, 186 
Vermifuges, use and action of, 121, 186 
Verminous bronchitis and pneumonia 
of cattle, 259 

of children, 231 

of the goat, 256 

of the horse, 261 

of the pig, 231, 260 

of the sheep, 256 
Vi\'iparous, application of the term, 
219 

W 

Warble flies, 53, 57 
White diarrhea of chicks, 345 
Wood tick, 143 
Wo mis, 155 

classification of, 155, 157, 173 



Zooparasites, 8 



Printed in the United States of America 




JUL 1 2000 
MAK 1 8 ZM/