Inrernarional

Journal

for Parasitology.

1978.

Vol. 8. pp. 467469.

Pergamon

Press. Printed

in Great Brifain.

CHEMOPROPHYLAXIS WITH TETRACYCLINE DRUGS IN THE IMMUNISATION OF CATTLE AGAINST 7’HElLERIA ANNULATA INFECTION B. S. GILL, Y. BHATTACHARYULU, D. KAUR and A. SINGH College of Veterinary Science, Punjab Agricultural University, Ludhiana 141004, India (Received 3 November 1977) Abstract-Gru

B. S., BHATTACHARYULU Y., KAUR D. and SINGHA. 1978. Chemoprophylaxis with tetracycline drugs in the immunisation of cattle against Theileriu annulutu infection. Znrernationuf Journal for Parasitology 8: 467-469. Three-month-old fully susceptible cross-bred calves were immunised against tropical theileriosis by treating 2-tick or S-tick stabilate-induced Theileriu unnulutu infections, with 1 or 2 doses of long-acting oxytetracycline (Pfizer) at 20 mg/kg body weight injected subcutaneously, or chlortetracycline at 16 mg/kg body weight daily for 8 days given orally. The treatment began on the day of the infecticn. After 45 days, the recovered calves were given severe IO-tick homologous stabilate challenge. The reactions were evaluated by noting fever, degree of anaemia, severity of the swelling of the regional lymph node, rate of parasitization of lymphocytes in the lymph node, and of erythrocytes in the peripheral circulation. The untreated calves developed a severe form of the disease with typical symptoms, which killed 1 of 4 and 2 of 5 calves receiving 2-tick and 5-tick stabilates, respectively. A total of 30 treated calves reacted mildly or not at all. Both the treated and untreated, recovered calves resisted completely the challenge infection which killed 3 of 4 susceptible controls. The effect of 1 dose of long-acting oxytetracycline was equal to that of 8 daily treatments with chlortetracycline; 2 doses of the oxytetracycline suppressed almost all clinical responses at immunisation. INDEX KEY WORDS: Theileria unnrrlutu; immunisation; challenge; cattle; Hyufommu unutolicum unatolicum; tick stabilate; long-acting oxytetracycline; chlortetracycline; haematology, chemoprophylaxis.

INTRODUCTION

GILL, Bhattacharyulu & Kaur (1976) recently reported that calves were immunised against severe homologous challenge by tick-induced Theileria annuluta infection, treated with chlortetracycline at I6 mg/kg body weight orally for 8 days. In subse-

quent work, Gill, Bhattacharyulu, Kaur & Singh (1977) substituted the cumbersome tick infestation method of inducing infection by injecting ground up infected ticks (‘tick stabilates’). The present paper records an experiment on the chemoprophylactic immunisation of calves against T. anndata using 1 or 2 doses of long-acting oxytetracycline-a special formulation prepared by Pfizer. Eight-day treatment with chlortetracycline was included in the investigation, for comparison. MATERIALS

AND METHODS

Three-month old cross-bred

(Holstein-Friesian x zebu) male calves reared in tick-proof sheds from birth were used. The ticks, Hyulommu unatolicum unatolicum had been raised in the laboratory on rabbits for 6 generations, and were infected with the Hissar strain of T. unnulutu (Gill et al. 1976) according to the method described by

Bhattacharyulu, Chaudhri & Gill (1975). The organism had been maintained in the laboratory by serial passage in the fully susceptible calves by tick transmission. The tick stabilates were prepared from adult ticks according to the method described by Gill et al. (1977), which was essentially the same as that described by Cunningham, Brown, Burridge & Pumell (1973) for T. purvu stabilates. The immunising infections (Table 1) were initiated by 2-tick and 5-tick stabilates contained in 1 ml volumes (Groups l-4) and 2 ml volumes (Groups 5-8) respectively, injected subcutaneously at the base of the left ear. Groups receiving each type of inoculum were treated either with chlortetracycline, Cyanamid (ct.) orally at 16 mg/kg for 8 days (Groups 1 and 5), 1 dose of longacting oxytetracycline, Pfizer (1.a.t.) at 20 mg/kg (Groups 2 and 6) or 2 doses of l.a.t., 3 days apart at 20 mg/kg (Groups 3 and 7). The treatment started simultaneously with the infection. Group 4 infected with 2-tick stabilate and Group 8 with 5-tick stabilate were left as untreated controls. Forty-five days after the immunising infections all recovered animals and 4 susceptible controls were homologously challenged (Table 1) by injecting lo-tick stabilate contained in 2 ml volumes subcutaneously at the base of the right ear. The animals were kept under observation for a further period of 6 weeks. Beginning 15 days before the immunising infection and continuing throughout the experiment, rectal temperatures of the animals were recorded daily, and their blood smears

467

468

B. S.

GILL, Y. BHA~ACHARYULU,

D. KAUR and A. SIKGH

I.J.P. VOL. 8. 1978

TABLE I-CONTROL BY TREATMENT WITH CHLORTETRACYCLINE (ct.) OR LONG-ACTING OXYTETRACYCLINE (1.a.t.) OF IMMUNISING REACTTONSIN CALVES INFECTED WITH T. Unnl4lUfU, AND RESPONSE TO SUBSEQUENT HOMOLOGOUS CHALLENGE _--_

Group

_.

No. of calves

1 2 3 4 5 6 I 8 9

5 5 5 4 5 5 5 5

Infective dose (stabilate)

2-tick 2-tick 2-tick 2-tick S-tick 5-tick 5-tick 5-tick -

-

.~

._~____.__.._

Immunising infection Treatment Days to the first detection of fever

c.t. 1.a.t. 1 dose 1.a.t. 2 doses Untreated c.t. 1.a.t. 1 dose 1.a.t. 2 doses Untreated Challenge control

Challenge infection No. of Days to Deaths calves the first detection

Deaths

-.-_~~~

Iw ll(3)

-

1

71 10.8 12 11,7(3) 5.8

2

5 5 5 3 5 5 5 3

of fever -

----

-

: -.

1 -

1 -

Result

-I----Solid Immunity Solid immunity Solid immunity Solid immunity Solid immunity Solid immunity Solid immunity Solid immunity

4 5.5 3 Acute infection ~( ) indicate animals showing fever if less than total in group; average value derived from this number. examined daily for the parasite. Smears of biopsy material from the regional parotid lymph node draining the site of the infection were examined for schizonts twice a week before the infection and on alternate days afterwards. The smears were immediately dried in air, fixed in methanol and stained with Giemsa. Haemoglobin (Hb) levels were determined with a Sahli haemometer (Hellige Incorporated, Garden City, NY), and packed cell volume (PCV) by the Wintrobe method (Wintrobe, 1967)

-

twice a week. Symptoms including swelling of the regional lymph node and mortality were recorded. RESULTS Results

of the immunisations and the challenges have been summarised in Tables 1 and 2. The infection in untreated calves (Groups 4, 8 and 9) produced acute reactions, the severity of

TABLE &-RESPONSES OF GROUPS 1-9 (SEE TABLE I) TO IMMUN~SAT~ON AND

-

Infection

Tmmunising

Challenge

Group of Table I

-_-.

-__I_

Average duration of fever (days)

Average days Regional parotid to first deteclymph node tion of piroAverage Average plasms in days to proportion lymphocytes erythrocytes the swelling parasitised

(%I

-_

I 2 3 4 5 6 1 8 1 2 3 4 5 6 7 8 9 (Susceptible control)

4.5 5*3(3) 7.7 4 Z.3(3) 8.8 -.10.3

11.8 10.2 11,3(3) 8 8 11 7.2 7.8 7

O+(2) 0.5 O-S(l) 4.5 1.4 1.4 0.5 8 20

CHALLENGE

WITH

i?

aimdata

_-

.-

Average maximum erythrocytes parasitised (%I

Average Hb decrease (%I

..-

Average PCV decrease ( %)

-__-12.8 12.8 14.2 11 12.2 12.6 13.4 11 Occasional* Occasional* Occasional* Occasional* Occasional* Occasional* Occasional* Occasional* 9

0.5 0.8 o-5

8.7 0.9 0.8 0.5 I5 1-4 l-4 1.4 @S 0.8 1 0.5 0.5 47.5

16.2 Il.8 9.2 8.4 35.2 -

16.7 13.6 I.7 6.8 34.3 -

-

-

-

-

35.3

37

( ) indicate the number of animals showing the response if less than total in groups; average value derived from this number. *The animals had developed premunition as a result of the immunisation, and at the time of the challenge most of them were showing rare (