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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

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

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

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.

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

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

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

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

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.).

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

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.)-

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,

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

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

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-

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

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

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

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

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.)

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

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

/yp /^

^p\\^\\

^^^

yi \^

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

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

" 1

pill

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.)

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

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

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

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.).

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

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.).

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

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

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

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

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.).

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

^^try^

3 '

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

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.

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.

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

Days
79-100

Days

86.9

101
199.6
250.7
279.6

Dec. 29, 1907,

to
Jan. 1, 1908

Days
181-207

Days
196.3

July 1, 1907

82-112

Jan. 29 to
Feb. 4, 1908

156^189

173.1

Aug. 1, 1907

172-221

Feb. 27 to 28,
1908

143-162

152.1

Aug. 31, 1907

230-272

Mar. 26 to
29, 1908

144-161

152.1

Oct. 1, 1907

276-288

April 29,
1908

122-173

142.8

Nov. 1, 1907

200-253

232.7

Nov. 30, 1907

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

Days
10-15

Days
5-13

Days
25-34

Males

7-9

8-10

(?)

7-14

April 4

Females

9-14

4-9

25-26

Males

8-12

—

May 23

Females

6-7

9-12

6-9

22-25

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.— Crawl 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

0 0 0 ° 0 0 «t
0 0 "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-

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

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.

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.).

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-

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.

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

• 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.).

■

hHF^ j

f j

\:-

iaaia

ifJI^^BPff'-^'.^^v '

~T^

k H^

■w

""^^

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

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

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

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

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

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

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,

Uncinaria, 281
Uncinariasis, 291

Uncinaria canina, 291
cernua, 293
radiata, 293
stenocephala, 292
trigonocephala, 291

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

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 0 1 2000
MAK 1 8 ZM/

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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"

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