DIFFERENTIAL DIAGNOSIS OFNEMATODE OVA IN CATTLE

bv' Richard G. Crosby

Thesis submitted to the Graduate Faculty of the

Virginia Polytechnic Institute

in candidacy for the degree of

MASTER O! SCIENCE

in

Biology

~•

APPROVED: D:

L/Directorof Graduate Studies Head of Department x'

,/—-1.A

·6·7’ _ . ~/7 / {

—rDean of Agriculture Major Professor

January, 1958

Blacksburg, Virginia

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TABLE OP CONTENTS

PAGE

LIST OF TABLES . . . „„............• . . . • . . • • 3

LIST G PLATES . • •......„...„....... „ . . „ • 4

INTRODUCTION „ ............„ . . ......• • . . . S

REVIEW (F LITERATURE . . . . ...... . . . .......„ „ . 7

INVESTIGATION . . . „ . • . . • . . . . . . . . ...„.• „ • . . 10

Objective . . . . . . „ . . . . . „ . . . . . . . . . • „ . 10

Materials and Methods...................10

Results . „ • . „ . . . . . . . . . • . . . „ . „ . . . . . 11

DISCUSSION OF RESULTS • „ •..........„ • . • • „ „ . . . 18

CONCLUSIONS AND SUMMARY • . „ • • . „ „ • „ • • . . • . • . . . . . 22

ACKNGJLEDGMENTS . • • „ . „ . . „„....„ . . • • • • • • . „ „ 24

BIBLIOGRAPHY . . „ . . „ . • • „ • „ . . • „ • . „ „ • • • „ . • . 25

Literature Cited . . . . . . „ „ . „ . . . . . . . . . . . . 25

Literature Examined . „ . „ . . . . . . . ...... . . . 28

VI‘I'A..„•..•„„...„..........•...•„.•30

APPENDIX • „ . . • • „ . . . „ • . . . „ „ • • „ „ „ „ • • • • • • 31

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LIST OF TABLES

TABLE PAGE

1. Results of Experiment••Haemonchus contortus . . . . . . . . . 12

2. Results of Experiment··0stertagia ostertagi . . . . . . . . . 13

3. Results of Experiment·—Trichostrongg1us ggg; . . . . . . . . 14

4. Results of Experiment•·Cooperia oncoghora .......... 15

S. Results of Experiment—·Bunostomum phlebotomum . . . . .... 16

6. Results of Experiment•-0esoghagostomum radiatum . . ..... 17

7. Comparison of Experimental Results with the Literature . . . 21

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LIST OF PLATES

PLATE PAGE

1. Photomicrograplx X100 of Namatoda Ova

from a Sample of Cattle Faces . . . . . . . ......33

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INTRDUCTIG

Internal parasites of cattle are capable of causing great economic

loss, but the extent of this loss and the savings that can result from

control of cattle parasites have only recently received serious atten-

tion. For the past several years extension animal husbandmen and veter-

inarisns have reported with increasing frequency parasitic infections in

cattle in the State of Virginia. Hence, the Animal Husbandry Department

in conjunction with the Animal Pathology Departent of the Virginia Poly-

technic Institute initiated in the Autumn and Spring of 1953-1954 a

survey in the State to obtain information concerning the incidence of

bovine parasitism.

Three methods have been utilized in diagnosing specific parasitism

in doestic animals. Until recently the method commonly employed has

been that of post mortem exaination. In this type of examination the

various digestive organa are tied off in place and then removed for ex-

amination for specific parasites. This method, while affording positive

information on the one anial aacrificed, could not be regarded as giving

sufficient information on the living animals unless a significsnt per-

centage of animals were autopsied. The second method is fecal culture

which is usually regarded as too time consuming and involving the aer-

vices of a technician skilled in identification of infective larvae.

Lately, differential egg counts have been employed. This method has the

advantage of quick diagnoais of mixed infections withut loss of animals

to slaughter. Therefore, more animals can be examined and a better eati-

mate of the helminth population as a whole can be obtained. The principal

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disadvantage of this method lies in errurs due to mis-tdentifications of

the ova.

The 1953-1954 survey employed the differential egg count method.

The present study is an outgrowth of the problem of identifying, with

reasonable accuracy, some of the commonly eccurring species of nematede

ova found in samples of cattle feces.

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REVIEW Q LITERATURE

A number of investigatlons have been conducted involving the inei-

dence of the parasitism of cattle both in this country and abroad, and

the information thus obtained has aided in the establishent of control

measures. Among the more important reports which have brought attention

to the cattle parasite problem are those of Andrews and Maldonado (1940),

Cooperrider, Pearson, and Kliewer (1948), Porter (1942), and Roberts gg

gl (1951, 1952). For the most part, these surveys were carried out

through fecal examination.

In 1939 Shorb published a bulletin on the differential diagnosis

of sheep parasitism through the identification of specific eggs of nem-

atode parasites. He measured as many eggs as he could obtain, up to

one hundred, from thirty·two species of nematodes parasitic in domestic

ruminants of the United States. Ten of these species were secured from

cattle; the remainder were from sheep and goats. The majority of his

easurements came from dissected adult females in physlologic saline,

while ten of the species measured were from preserved material. He re-

corded the length, width, and form index and calculated the standard

deviations. He also noted thickness of shell and stage of development

and devised a key employing fifteen diagnostic characteristics based on

size and morphology of ova. In 1940 Shorb charted the egg measurements

he had obtained. By correlating egg size with the geographical distri-

bution of the species involved, he demonstrated how to differentiate

species within genera.

Rates and Shorb (1943) collaborated on a paper giving a descrip-

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tion of fifteen sheep nematode ova, supplemented by photomicrographs offourteen species of ova. Again, adult females were dissected in physi-

ologic saline to obtaln the ova.

Kates (1947) added further information to the significance of

differential diagnosis by correlatlng differential egg counts with post

mortem findings in a group of fifty—nine experimental sheep. He con-

cluded that differential egg counts could prove of value in estlmating

parasite burden if a fairly large number of animals were sampled and if

the data were conservstlvely interpreted with regard to important vari-

able factors.

Tetley (1941, 1950) has done important work on the differentia-

tion of Haemonchus and Ostertagia ova in sheep and on the differentiation

of species within genera. In his wrk on Haemcnchus in 1941 he dissected

numerous eggs from several female worms and compared the average size

with eggs measured from fresh feces. He found that the dissected eggs

were more narrow than the fresh eggs and concluded that a swelling of

the ova took place in the intestines of the animal. In 1950 he measured

and plotted the lengths and widths of Haemogchus and Ostertagia ova and

arrived at a distinct size range with little overlapping for each genus.

More recently, Cunliffe and Crofton (1953) in England have con-

ducted extensive research on egg sizes of eight species of sheep nematodes.

They measured the length and width of one hundred eggs of each species,

one egg being diasected from one female from preserved specimens. They

devised a method of egg differentiation based on the statistical chances

of eggs of different specles falling into particular size classes, andconstructed a classifying scale.

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Krug and Mayhew (1949) have done similar work in the United States

by comparing the size of ova of four nematode species commonly occurring

in cattle. They obtained five hundred measurements of length and width

of eggs by centrifuge sugar flotation of fecea of cattle having pure in-

fections and by dissecting preserved specimens. They give a maximum,

minimum, and average measurement and a description of the eggs.

Techniques of differential egg counts have been numerous and

varied. The majority, however, have been based on Sto1l's (1930) direct

centrifugal flotation method utilizing different solutions for flotation.

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INVESTIGATION

Objective

It is the purpose of this investigation to evolve an improved

method for ldentifying the species of nematode parasites commonly found

in the digestive tract of cattle by microscopic examination of the ova.

To establish such a procedure it has been necessary first to find a true

basis for comparison and subsequent identification of the ova.

Procedurel

Material for the investigation was secured at local abattoirs,

the Virginia Polytechnic Institute abattoir, and at the Animal Pathology

Laboratory. The abomasa, small intestines, and large intestines of

freshly slaughtered cattle were tled off and brought to the laboratory

for examination. Within two hours after slaughter each of the three

portions of the digestlve tract was opened separately and screened for

parasites. The abomasa, after being washed, were put in a Baermann

apparatus in order to secure as many worms as possible. Haemonchus

contortus, Ostertagia ostertagi, and Trichostrongylus ggg; were recovered

from the abomasa. Two specles, Cooperia oncophora and Bunostomum

phlebotomum, were secured from the small intestines, and one species,

Oesophagostomum radiatum, from the large lntestines.

The live female worms were washed thoroughly to remove adherring

debris, identifled as to species, and placed in 0.7 percent saline where

they were allowed to oviposit at room temerature. The eggs were removed

from the saline solution with a capillary pipette and placed on a clean

slide. Bits of broken coverglass surrounding the drop prevented distor·

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tion by pressure when the coverglass was applied. The eggs were examined

under a binocular microscope at X430 and measured with the aid of a cal-

ibrated ocular micrometer.

The lengths and widths of 100 eggs from each species were recorded.

When time was not available to measure the eggs upon oviposition they Iwere refrigerated until an opportunity was presented. A11 eggs were

measured within 72 hours after slaughter of the animal.

Results

The results are shown in tables 1-6. The lengths and widths of

the ova are given in microns, and the frequency with which these measure-

ments occur has been noted. The form index, a means of recording the

relative thickness of the egg (Shorb, 1939), has been calculated for each

egg. The form index of eggs with a length twice the width is 50. The

rounder the egg, the nearer the form index approaches 100. The mean,

deviation from the mean, and standard deviation have been calculated for

each set of figures.

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TABLE 1

Haemonchus contortua

Length Width Form Index

»~ ¤ ¤ >. »~ ¤ ¤ >. »~ ¤ ¤ >.2 32 2 I 2 82 2 2 .22 28 25 2 3 25 2 8 25 2_3 «4 E ¤· _2 -6 E ¤· u -6 E g-a ä u 8 E > u 2 °H Ü u u-

¢¤¤• u. ~« g~u u. ~6 ¤•6 m

70 -11.44 1 42 -5.44 5 47 -11.35 372 · 9.44 2 43 -4.44 17 49 - 9.35 173 - 8.44 I 3 44 -3.44 11 50 - 8.35 274 - 7.44 4 45 -2.44 8 51 - 7.35 575 - 6.44 4 46 -1.44 13 52 - 6.35 476 · 5.44 6 47 ~0.44 5 53 • 5.35 477 - 4.44 2 48 0.56 10 54 - 4.35 678 — 3.44 8 49 I 1.56 7 55 - 3.35 579 - 2.44 7 50 I 2.56 6 56 - 2.35 580 - 1.44 6 51 3.56 1 57 . · 1.35 981 - 0.44 5 S2 4.56 3 58 · 0.35 1082 0.56 9 53 5.56 1 59 0.65 683 1.56 5 56 8.56 5 60 1.65 684 2.56 6 57 9.56 3 61 2.65 485 3.56 16 58 I 10.56 I 3 62 3.65 786 4.56 6 59 11.56 2 63 4.65 787 5.56 1 I I 64 I s.6s 490 8.56 2 65 6.65 291 9.56 3 I 66 7.65 292 10.56 2 67 8.65 193 11.56 2 I 68 9.65 4

69 10.65 270 11.65 1

Mean 81.44 Mean 47.44 Mean 58.35

Standard Standard Standarddeviation 5.1 deviation 4.6

Ideviation 5.3

I

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TABLE 2

Ostertagia ostertagi

Length width Form Index

Q qäjä 5 17 Sä 5* ^ 55 5*E ..8 5 5 13*8 TIE 8M m ¤ M m ¤ M ¤ :0 ·g g ¤· _3 -4 g u- 0 -g E ¤·ea 0 M 3 E 6 M 3 Ia0 M 3~# ¤*¤ m ~« ¤ 4n an ~# cswe m

70 -9.74 2 38 -4.56 5 41 -12.38 171 -8.74 1 40 -2.56 2 44 - 9.38 172 -7.74 2 41 -1.56 24 45 - 8.38 474 -5.74 10 42 -0.56 8 48 - 5.38 375 -4.74 2 43 0.44 45 49 - 4.38 776 -3.74 1 44 1.44 4 50 - 3.38 577 -2.74 13 46 3.44 10 51 - 2.38 1478 -1.74 3 47 4.44 1 52 - 1.38 779 -0.74 21 48 5.44 1 53 - 0.38 980 0.26 2 54 0.62 1681 1.26 1 55 [ 1.62 382 2.26 16 56 { 2.62 983 3.26 4 57 3.62 184 4.26 11 58 4.62 885 5.26 2 59 5.62 286 6.26 7 60 6.62 589 9.26 2 61 7.62 2

62 8.62 263 9.62 1

Mean 79.74 Mean 42.56 Mean 53.38

Standard Standard Standarddeviation 4.2 deviation 1.9 deviation 4.2

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TABLE 3

Trichostrongglua axei

Length Width Form Index

^ G Ps A G Ps Ag E; 2 2 25 2 2 E5 2„ 2 2 2 25 2 E 25 2° E5 S' ° "E °‘

°”‘ä

°jä 6 u u °ä Ü u 3•a

Ü n g'c:¤• u. - ¢¤«~ u. - c:¤« ä

79 -9.56 1 34 -2.01 10 34 ·6.74 180 -8.56 1 35 -1.01 20 35 -5.74 281 -7.56 1 36 -0.01 45 36 -4.74 282 -6.56 2 37 0.99 17 37 -3.74 383 -5.56 1 38 1.99 5 38 -2.74 684 -4.56 10 40 3.99 1 39 -1.74 1685 -3.56 11 41 4.99 2 40 -0.74 1586 -2.56 14 41 0.26 1687 -1.56 6 42 1.26 1888 -0.56 3 43 2.26 889 0.44 11 44 3.26 790 1.44 4 45 4.26 591 2.44 8 46 5.26 192 3.44 1294 5.44 795 6.44 296 7.44 498 9.44 1

103 14.44 1

Mean 88.56 Mean 36.01 Mean 40.74

Standard Standard Standarddeviation 4.3 deviation 1.3 deviation 2.4

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TABLE 4

Coegeria encoghora

Length Width Form Index

'Q 58 Q 'TJ 55 5* ^ S8 5»6 6 6 ..6 6 E 66 65 .3 " 5 ” 8 5 "' ä·6 za? E 6 gä ·=· 6 **8 ~~¢ cxue u. ~« •g~u Ä: 5* «g~¤ Ä:

82 -12.41 2 34 -4.24 1 31 -9.96 184 -10.41 7 36 -2.24 23 33 -7.96 386 - 8.41 9 38 -0.24 52 34 -6.96 389 - 5.41 8 41 2.76 23 35 -5.96 691 - 3.41 19 43 4.76 1 36 -4.96 793 - 1.41 1 37 -3.96 594 - 0.41 10 38 -2.96 496 1.59 14 39 -1.96 498 3.59 5 40 -0.96 21

101 6.59 6 42 1.04 15103 8.59 10 43 2.04 4106 11.59 5 44 3.04 6108 13.59 2 45 4.04 3110 15.59 1 46 5.04 3115 20.59 1 48 7.04 7

49 8.04 650 9.04 2

Mean 94.41 Mean 38.24 Mean 40.96

Standard Standard Standarddeviation 7.0 deviation 1.8 deviation 4.6

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TABLE S

Bu¤ost% ghlabotg

M E B-M-*8 8 8 5* '8 E 8 5* Q 8 S 5*8 '3 8 8 E '5 8 8 E 8 8¤ ¤ ¤ n u ¤ ¤ g;—‘ä B B E ~ä §B ~ä § B aV 8 8 8 V 8 he V 8 ..

90 -8.48 1 48 -4.84 8 46 -7.8 191 -7.48 1 49 -3.84 24 47 -6.8 292 -6.48 1 50 -2.84 31 48 -5.8 893 -5.48 2 51 -1.84 3 49 -4.8 1394 -4.48 5 52 -0.84 3 50 -3.8 1595 -3.48 12 53 0.16 2 51 -2.8 1796 -2.48 1 55 2.16 3 52 -1.8 497 -1.48 7 56 3.16 2 53 -0.8 498 -0.48 24 58 5.16 6 54 0.2 299 0.52 3 60 7.16 6 55 1.2 3

100 1.52 15 61 8.16 3 56 2.2 4101 2.52 15 62 9.16 1 57 3.2 1102 3.52 5 63 10.16 1 58 4.2 2103 4.52 5 64 11.16 1 59 5.2 2104 5.52 1 65 12.16 2 60 6.2 2105 6.52 1 66 13.16 1 61 7.2 6106 7.52 1 68 15.16 2 62 8.2 3

70 17.16 1 63 9.2 264 10.2 365 11.2 268 14.2 370 16.2 1

Haan 98.48 Mean 52.84 Mean 53.8Standard Standard Standarddaviatiun 3.0 daviation 5.5 daviation 5.8

TABIZ.6

Oesoghagostcmum radiatgg

Length Width Form Index

'§ gi Ü E gÜ 2Ü ’§ gÜ Üg gs g == IE5 2 = ÜÜ 5—a . .2 —a ... .2 a *5 .v gw M ~« am M v gu p

84 -7.93 2 45 -4.76 7 45 -9.3 185 -6.93 3 46 -3.76 7 46 -8.3 186 -5.93 5 47 -2.76 2 47 -7.3 187 -4.93 4 48 -1.76 30 48 -6.3 488 -3.93 2 50 0.24 31 49 -5.3 589 -2.93 18 53 3.24 13 50 -4.3 391 -0.93 25 55 5.24 4 51 -3.3 1092 0.07 4 56 6.24 3 52 -2.3 794 2.07 16 58 8.24 1 53 -1.3 1696 4.07 8 60 10.24 2 54 -0.3 693 6.07 6 55 0.7 14

101 9.07 5 56 1.7 9103 11.07 2 57 2.7 2

58 3.7 759 4.7 160 5.7 561 6.7 162 7.7 363 8.7 264 9.7 169 14.7 1

una 91.93 Ma 49.76 Mean 54.3Standard Standard Standarddeviation 4.3 deviation 3.2 deviation 4.2

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DISCUSSION OF RESULTS

The present study has been conducted to serve two purposes: to

determine if a regional variation may possibly exist between the sizes

of nematode ova commonly found in the feces of Virginia cattle and sizes

of nematode ova reported in the literature, and to increase the accuracy

of identification.

A number of difficulties arise when making a specific diagnosis

of parasitism by egg counts. Various workers approach the subject of

differential counts from two different standpoints. One group places

emphasis on the characteristics of the ova, such as shape and color, with

egg size also a factor; the other favors a statistical approach utiliz·

ing the probability of an egg falling into a certain class or genus

depending upon its size.

Frequently, ova found in a fecal specimen may be very difficult

to differentiate. This is particularly true when the parasitic species

present in the animal have eggs that are very similar in size and appear—

ance. For instance the eggs of Haeonchus, Cooperia, and Ostertagia may

at times look much alike. Therefore, six of the species most difficult

to identify were chosen. Bunostomum and Oesophagostomum may be said to

represent one size group because they are often mistaken for each other

in mixed infections. It was found that while both have parallel sides

with blunt ends and contain an eight·celled embryo, Bunostomum averages

nearly seven microns longer and three microns wider than Oesophagostomum.

Bunostomum ova found in feces are brownish in color, may often present

a more oval shape, and appear to have a rough shell in contrast to the

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smooth shell of the freshly oviposited egg. Oesoghagostomum ova found

in feces have usually developed into the sixteen-celled stage. Differ-

entiating the genera Haemonchus, Ostertggia, and Cooperia presents the

greatest problem in mixed infections. From a study of the fresh eggs,

Haemonchus appears to assume a more nearly oval or egg shape. Cooperia

oncoghora ova are thin and elongate, and as the results indicate, the

ova of this species of Coogeria are apt to be more than ten microns

longer than the ova of Haemonchus and Ostertagia. Also, the cells are

yellowish, while those of Haemonchus and Ostertagia are colorless.

Ostertagia ova tend to be the most irregular in shape, soettmes giving

a slightly oval appearance but more frequently having parallel sidea.

The Ostertggia ova approach Haemonchus in length but average almost five

microns less in width. The eggs of all three species are in the morula

stage.

Trichostrongylus ggg;, the smallest of the stomach worms was

chosen because its ova also may be mistaken for one of the Haemonchus·

Ostertggia•Coogeria group. This species is a poor egg producer, and its

small size makes it difficult to obtain. The ova of ;. ggg; were found

to closely approximate the length of Oesophagostomum but were almost

fourteen microns less in width. One distinctive feature is shape--

almost invariably they are sharply pointed on one end, the other end

being rounded. These ova are also present in the morula stage.

The eggs were measured after normal deposition in 0.7 percent

saline, which Bremner (1955) used as an isotonic solution. In this

manner the eggs could be assumed to be mature and to have the shape

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found in fresh feces. Preserved specimens were not used because of the

possibility of shrinkage caused by the preservative. When using feces,

pure infections are éxfficult to produce, as well as the obvios disad-

vantage of maintaining a number of experimental animals.

Table 7 compares the figures given in available literature with

those of the present study. There appears to be an over·a11 agreement

except in the case of Cooperia oncophora. Here, the average length ia

greater than that given by Shorb. lg. ggggggggg, a species infecting

both cattle and sheep, shows a difference in size in the two hosts.

Present work in Australia by Roberts (1954) indicates that Haemonghgg

infecting cattle and sheep are two dlstinct species.

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TABLE 7

Comparison of Experimental Results with the Literature

Length (microns) Width (microns) Form Indexm3°° ä·~¤¤¤¤r 52 *5.5. 'aä 55 *22u u 8 u .g eg 0 u Ü u 0

{U ga wg *¤¤¤ ·0¢¤ gang2 ;·= g ·= 2 52 g 5 .55 g ··= 5 ää 2>¤ 8 E1 :1 cn·u E1 ¤n·g E2 tg ¢n·¤ cn•3

Hgggonchus cotortusShorb (1939) Sheep 100 82 65 74 2.6 46 39 43.4 1.4 70 50 58.8 4.0 HarulaTetley (1941) Sheep 743 87 66 76.6 3.8 47 34 41.3 2.2Cunliffe 8 Crofton (1953) Sheep 100 90 62.5 73.3 4.59 50 40 44.3 2.19Shorb (1939) Cattle 100 92 72 81.7 3.6 47 39 43.8 1.6 61 44 53.7 3.5 MnrulaKrug 8 Hayhew (1949) Cattle 500 102 58 78.6 59 37 42.0Present stud Cattle 100 93 70 81.4 5.1 59 42 47.4 4.6 70 47 58.4 5.3 Morula

Ostertagia ostertggiSherb (1939) Cattle 50 90 74 78.5 3.2 44 38 40.1 1.6 42 51.0 1.3 MnrulaThrelkeld (1946) Cattle 25 84 78 76 50 40Present stud Cattle 100 89 70 79.7 4.2 48 38 42.6 1.9 41 53.4 4.2 Morula

Trichostron; lus axelShorb (1939) Sheep 52 92 79 84.6 3.6 41 31 36 2.1 50 36 42.6 3.3 MorulaCunliffe 8 Crofton (1953) Sheep 100 107.5 75 86.5 5.47 47.5 30 39.5 3.34Present stud Cattle 100 103 79 88.6 4.3 41 34 36 1.3 46 34 40.7 2.4 Horula

Coo·aria onc0·horaShorb (1939) Sheep 108 92 74 83.2 3.2 44 36 39.7 2.4 43 50.5 3.7 MorulaShorb (1939) Cattle 100 95 74 85.7 3.6 44 36 39.4 1.7 37 45.9 2.7 MorulePresent stud Cattle 100 115 82 94.4 7.0 43 34 38.2 1.8 31 41 4.6 Morula

Bunost•«~» lhlebotemmShorb (1939) Cattle 100 104 88 96.5 3.4 56 47 50.3 1.3 59 47 2.4 8-10 callsKrug 8 Mayhew (1949) Cattle 700 117 79 100.8 70 47 54.1 4-8 cellsPresent stud Cattle 100 106 90 98.5 3.0 70 48 52.8 5.5 70 46 5.8 4-8 calls

Oesoehazostomum radlatumShorb (1939) Cattle 100 98 75 85.8 3.9 54 46 49.2 1.8 72 50 57.6 3.6 4-16 callsKrug 8 Mayhew (1949) Cattle 500 120 73 94.5 70 38 50.9Present study Cattle 100 103 84 91.9 4.3 60 45 49.8 3.2 69 45 54.3 4.2 8·16 cells

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CONCLUSIONS AND SUMMARY

The lengths and widths of one hundred ova each of Haemonchus

contortus, Ostertagia ostertagi, Trichostrongylus gxgi, Cooperia oncophora,

Bunostoum ghlebotomm, and Oesophagostomum radiatum from cattle were

measured in an attempt to establish a basis for comparison and identifi-

cation of ova in mixed infections.

These six species were chosen because they are important cattle

parasites in western Virginia, and are often difficult to identify in

fecal examinations. The results of the study do not differ appreciably

from the figures given in the literature. Further study is necessary to

complete the total species of cattle parasites, and it is most prominantly

illustrated in that data for only one of the three species of Cooperia

and one of the two species of Trichostrongylus are presented.

The figures obtained in the present study are offered simply as

an aid to diagnosis. The differential egg count may thus be correlated

with probable worm burden and the information used in treatment. In

utilizing these measurements the technician may, by a process of elimi-

nation, determine the probable genus. While egg sizes are important in

differentiation, other characteristics such as shape, number of calls,

and color of cells must be considered. Attempting to take measurements

of each egg is very time consuming, and quick identification must be made

by recognition and comparison after a few eggs have been measured. Thus,

the relative differences in sizes must be a fundamental objective. A

positive identification of each egg is not possible since ova of different

species often have a similar appearance. Differential counts are subject

- gg -

to consiclerable error because of normal variation in appearance and size

within species and often within the same female. However, mis-identifi-

cations of several ova in a mixed infection should to some extent cancel

out.

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ACKNOWLEDGMBNTS

I wish to express my sincere gratitude to the members of my

committee, Dr. I. D. Wilson, Dr. W. B. Bell, and Dr. J. M. Grayson,

for making this work possible, and to Dr. W. L. Threlkeld, Major

Professor, for his patience in imarting a portion of his knowledge

of the field of Parasitology.

Professor Betty V. Conner made the excellent photomicrograph.

This work is for L. S. B. and Doc.

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LITERAIURE CITED

Andrews, J. S. and J. F. Maldonado

1940 A preliminary note on the internal parasites of Puerto Rican

cattle with special reference to those species found in

calves suffering from "tropical diarrhea". Jour. Agric.

Univ. Puerto Rico 24(4): 121-132.

Bremner, K. C.

1955 Cytological studies on the specific distinctness of the ovine

and bovine "strains" of the nematode Haemonchus contortus

(kudolphi) Cobb (Nematoda: Trichostrongylidae). Australian

Jour. Zool. 3(3): 312-323.

Cooperrider, D. E., C. C. Pearson, und I. O. Kliewer

1948 A survey of the gastro-intestinal parasites of cattle in

Oklahoma. Okla. Vet. Res. Inst. Bull. T-31, 18 pp.

Cunliffe, G. and H. D. Crofton

1953 Egg sizes and differential egg counts in relation to sheep

nematodes. Parasitology 43(3,4): 275-286.

Kates, K. C.

1947 Diagnosis of gastrointestinal nematode parasitism of sheep

by differential egg counts. Proc. Helminthol. Soc. Washington

l4(1): 44-S3.

and D. A. Shorb

1943 Identification of eggs of nematodes parasitic in domestic

sheep. Amcr. Jour. Vet. Res. 4(IO): 54•60.

- 26 -

Krug, E. S. and R. L. Mayhew

1949 Studies on bovine gastro-intestinal parasltes. XIII. Species

diagnosis of nematode infections by egg characterlstics.

Trans. Amer. Microsc. Soc. 68(3): 234-239.

Porter, D. A.

1942 Incidence of gastrointestinal nematodes of cattle in the

southeastern United States. Amer. Jour. Vet. Res. 3(8):

304-307.

Roberts, F. H. S.

1951 Parasitic gastro-enterltis of cattle, with particular ref-

erence to the occurrence of the disease in Queensland.

Australian Vet. Jour. 27(10): 274-282.

, P. J. O'Su1livan, and R. F. Riek

1951 The significance of faecal egg counts in the diagnosis of

parasitic gastro-enteritis cf cattle. Australian Vet. Jour.

27(l): 16-18.

1952 The epidemiology of parasitic gastro-enteritis of cattle.

Australian Jor. Agric. Res. 3(2): 187-226.

, H. N. Turner, and M. Mckevett

1954 On the specific distinctness of the ovine and bovlne "strains"

of Haemonchus contortus (Rudelphi) Cobb (Nematoda: Tricho•

strongylidae). Australian Jour. Zool. 2(2): 275-295.

- 27 .

Shorb, D. A.

1939 Differentiation of eggs of various genera of nematodes

parasitic in domestic ruminants in the United States. U. S.

Dept. Agric. Tech. Bull. 694, ll pp.

1940 A comparative study of the eggs of various species of

nematodes parasitic in domestic ruminants. Jour. Parasitol.

26(3): 223-231.

Stoll, N. R.

1930 On methds of counting nematode ova in sheep dung.

Parasitology 22(1): 116-136.

Tetley, J. H.

1941 The differentiation of the eggs of the trichostrongylid

species Nematodlrus filicollis and Q, sgathiger. Jour.

Parasit. 27(6): 473-480.

1941 Haemonchus contortus eggs: Cmparison of those in utero

with those recovered from faeces, and a statistical method

of identifying Q. contortus eggs in mixed infections. Jour.

Parasitol. 27(5): 453-464.

1950 The differentiation of the eggs of Haemonchus contortus and

Ostertagia species of the sheep and a note on the relative

generic egg•laying rates. Parasitology 40(3,4): 273-275.

- gg -

LITERATURE EXAMINED

Cooperrider, D. E.

1954 Losses in cattle due to internal parasitism. N. Amer. Vet.

35(5): 350-353.

Goldman, M. and S. A. Johnson

1950 Deep-freeze preservation of stool specimens containing

intestinal parasites. Jour. Parasitol. 36(1): 88.

Mills, A. M.

1954 Stomach parasites of cattle. Vet. Med. 49(6): 226•228.

Roberts, F. H. S. and P. J. O'Sul1ivan

1950 Methods for egg counts and larval cultures for strongyles

infesting the gastro-intestinal tract of cattle. Australian

Jour. Agric. Res. 1(1): 99-102.

Summers, W. A.

1942 A modification of the zinc sulfate centrifugal flotation

method for recovery of helminth ova in formalized feces.

Jour. Parasitol. 28(4): 345-346.

Turner, J. H.

1951 Counting Nematodirus sgathiger eggs in sheep dung. Proc.

Helminthol. Soc. Washington l8(2): 132-135.

Whitlock, H. V.

1941 A new apparatus for counting small numbers of nematode eggs

in faeces. Jor. Counc. Sci. and Indust. Res. l4(4):

306-307.

- 29 -

Whitlock, H. V.

1942 The preparation and examination of faecal cultures for the

differentiation of larvae of sheep nematodes. Jour. Counc.

Sci. and Indust. Res. 15(l): 56-S8.

1943 A method for preventing the development of strongylid eggs

in sheep faeces during transport and storage. Jour. Counc.

Sci. and Indust. Res. 16(4): 215-216.

1950 A technique for counting trematode eggs in sheep faeces.

Jour. Hehminthol. 24(1/2): 47-52.

The vita has been removed fromthe scanned document

- 3; -

APPENBIX

The following list preeents the species of cattle nematode para-

sites likely to be found in Virginia:

Bunostomum ghlebotommCagillaria bovisCapillsria brevipesCooperia oncophoraCooggrla gectinataCoogeria gunctataDictyocaulgs vivsgorusßggggnchus contortusHggmonchus similisNematodirus filicollisNematodirus helvetiansNematodirus spathigeryeoascaris vi. tulorumOesoghagostoum radistumOatertagia lxgataOstertagia ostertagiStggggyloides gapillosisTgichostrongglus axeiggichostggggylus colubriformisQrichostrongylus vgtrigusTrichuris discolorTrichuris ovis

The egg sizes and descriptions of the genera routlnely encountered

in fecal samples are as followsz

Bunostommm phlebotomum·—90 to 106 microns long by 48 to 70 microns

wide; ye1lowish—brown to deep brown in color; thick, rough appearing

shell; 8 cells.

Capillaria sp.*··4l to 54 mdcrons long by 21 to 26 microns wide;

yellowish; two opercula.

Coogeria sp.*-~67 to 95 microns long by 29 to 44 microns wide;

parallel sides with blunt ends; yellowish; morula stage.

*Shorb, 1939.

. 32 .

Haemonchus contortus·•70 to 93 microns long by 42 to 59 microns

wide; oval; cells light or clear in color; morula.

Nematodirus sp.*••l49 to 233 microns long by 74 to 110 microns

wide; 8 dark•colored cells.

Neoascaris vitulorum*—-69 to 93 microns in diameter; round, rough

shell; 1 cell.

Oesgghagostomum radiatume-84 to 103 microns long by 45 to 60

microns wide; calls dark in color; ends of shell usually blunt; sides

parallel; 8 to 16 cells.

Ostertagia sp.*·•74 to 90 microns long by 38 to 44 microns wide;

irregular in shape but with approximately parallel sldes; light in color;

morula.

Strongyloides papillosis*--52 to 65 mdcrons long by 31 to 36

microns wide; vermiform embryo.

Trichostrongylus sp.*·—79 to 118 microns long by 31 to 52 microns

wide; shell pointed at one end; morula.

Trichuris sp.*--70 to 79 microns long by 31 co 39 microns wide;

yellowish·browu; two opercula.

Ova of the tapeworm Moniezia sp. are approximately 100 mdcrons in

diameter, usually more triangular than round in appearance, and contain

a scolex armed with six books.

Oocysts of Eimeria sp., a coccidian parasite, measure approximately

20 microns or smaller in size, are egg·shaped, and have an operculum.

*Shorb, 1939.

? ~ 33 •1

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