Veterinary Parasitology, 9 (1981) 151--155 151 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

Short Communication

HYALOMMA ANATOLICUM ANATOLICUM (KOCH, 1844) AS A POSSIBLE VECTOR FOR TRANSMISSION OF TR YPANOSOMA THEILERI, LAVERAN, 1902 IN CATTLE

U.V. SHASTRI and P.D. DESHPANDE

Department of Parasitology, College of Veterinary and Animal Sciences, MA U, Parbhani --431 402 (India)

(Accepted for publication 4 August 1981)

ABSTRACT

Shastri, U.V. and Deshpande, P.D., 1981. Hyalomma anatolicum anatolicum (Koch, 1844) as a possible vector for transmission of Trypanosoma theileri, Laveran, 1902 in cattle. Vet. Parasitol., 9: 151--155.

Amastigotes, sphaeromastigotes, epimastigotes and trypomastigotes of Trypanosoma theileri, Laveran, 1902 have been observed in the nymphs and adults of Hyalomma anatolicum anatolicum (Koch, 1844). These ticks were obtained from engorged larvae and nymphs collected from a cross-bred bull with detectable parasitaemia. Infection with T. theileri was established in two 6--8-month old cross-bred calves by subcutaneous inoculation of Trypanosomatid flagellates collected from ticks and by feeding of the in- fected ticks on the ears of these calves.

INTRODUCTION

O'Farrell (1913) discovered Crithidia hyalommae from the cattle tick Hyalomma aegyptium and Arifdzhanov and Nikitina (1961) detected the epimastigote forms in Hyalomma anatolicum anatolicum a three-host-tick of cattle. Hoare (1972) was of the opinion that ticks did not play any role in the transmission of T. theileri, as metatrypanosomes were neither demon- strated in the ticks, nor was any at tempt made for experimental transmission using ticks. However, Burgdorfer et al. (1973) described the stages of a trypano- some, i.e., amastigotes, epimastigotes and trypomastigotes in Rhipicephalus pulchellus and Boophilus decoloratus. All these stages of trypanosome dev- elopment have also been detected in Hyalomma anatolicum anatolicum which is a common tick pest on cattle in India. As experimental evidence that ticks are vectors of T. theileri is lacking, an a t tempt was made to trans- mit the infection of this flagellate to cattle and the results are recorded in this communication.

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MATERIALS AND METHODS

Source of infection

A two-and-half-year-old cross-bred bull (Holstein Friesian × Deoni) with a Trypanosoma theileri infection, as detected by thick-blood smear method in August 1980, was used. Several batches of larvae and nymphs of H. a. anatolicum, that had been bred in the laboratory, were fed through ear bags on this bull for a period of 15 days. The engorged larvae and nymphs were allowed to moul t in the laboratory. The moulting nymphs and adults were dissected in phosphate buffered saline (PBS) and examined under a light microscope for presence of Trypanosomatid flagellates. Of 345 adults and 207 nymphs dissected, 30 adults and 28 nymphs had a mixed populat ion of epimastigotes and trypomastigotes (Figs. 1 and 2). This tick material formed the source of infection for the present experiment.

Experimental animals

Four cross-bred male calves (Jersey X Red Kandhari) 6--10 months old

Fig. 1. Photomicrograph showing epimastigote stages of T r y p a n o s o m a theileri in the tick H. a. ana to l i cum (x 1000).

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Fig. 2. Photomicrograph showing trypomastigote stages of T. theileri in the tick H. a. anato l i cum (x 1000).

were procured from Veterinary College Dairy Unit, Parbhani, which is main-rained free of tick infestation. The experimental calves were checked for presence of T. theileri infection by dissecting two hundred laboratory reared nymphs of H. a. anatolicum following feeding the larvae on these calves and then allowing them to moult in the laboratory. All the calves were found free of T. theileri infection. Two of the calves were selected for infection (Group I) and the other two were kept as controls (Group II).

Procedure o f infection

A 20 ml crude suspension was prepared by dissecting 5 adult ticks and 10 nymphs which had trypanosomes in PBS. Ten ml of the suspension was injected subcutaneously in each of the two calves of Group I. In addition, approximately 100 unfed nymphs and 100 unfed adults collected from the cross-bred bull carrying T. theileri were also fed in an ear bag on each of the calves.

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Procedure for detecting the infection

Larvae and nymphs of H. a. anatolicum reared in the laboratory were fed on the infected as well as the control calves every week from the 1st to the 5th week post infection. The nymphs used in the trial were those that had moulted in the laboratory from the larvae fed on young cross-bred calves. The engorged larvae and nymphs thus obtained from experimental calves were kept for moulting under laboratory conditions, and the resulting nymphs and adults were dissected so as to detect the Trypanosomatid flagel- lates with a light microscope. (Minimum and maximum room temperatures during the period of s tudy being 22.5 and 32.4 C, respectively.) Smears were prepared from the positive ticks and stained by the Giemsa method for further study.

RESULTS

Large numbers of dissected nymphs and adults (200) from the control calves did not show any evidence of presence of flagellates. As shown in Table I, the infection in the inoculated calves developed in the first week. Two nymphs collected from one of the calves yielded Trypanosomatid flagellates. During the period of four weeks following infection, out of 140 adults, 48 yielded flagellates {34.28% infection). During the same period 50 nymphs out of 175 (28.57% infection) revealed the presence of Trypa- nosomatid infection.

The infective nymphs lost their infections upon feeding on the animals. All the partially engorged nymphs, fed on the calves to induce infection, did no t yield flagellates upon dissection. Similarly, adult ticks moulting from such engorged nymphs also did not have flagellate infection.

Ten larvae each from a batch fed on infected calves were dissected each day up to Day 6 after collection. It was found that the number of flagellates in these larvae gradually increased from Day 2 onwards and were seen in large numbers on Days 5 and 6. The flagellates were observed in adult ticks until Day 51 following engorgement of their nymphs on the infected calves. All the cyclical forms of development, i.e., amastigotes, sphaeromastigotes, promastigotes, epimastigotes and trypomastigotes were seen in the infected nymphs as well as in the adults. Promastigote forms were numerically very few, however, compared to other forms.

DISCUSSION

The s tudy revealed that infection of T. theileri could be established in the calves with the Trypanosomat id flagellates from the tick H. a. anatolicum. In the inoculated calves, infectivity from the ticks became apparent from the second week onwards post infection {Table I). The present findings of meta- t rypanosomes in the tick and successful establishment of infection in the

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TABLE I

Flagellates in adult and nymphal ticks collected from the infected calves

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Weeks after No. No. showing Infection (%) infection dissected flagellation

1 Adults 50 0 0 Nymphs 65 2 3.08

2 Adults 39 15 38.46 Nymphs 66 25 37.88

3 Adults 40 16 40.00 Nymphs 82 19 23.17

4 Adults 61 17 27.87 Nymphs 27 6 22.22

Total Adults 140 48 34.28 Nymphs 175 50 28.57

e x p e r i m e n t a l calves c o n t r a d i c t the op in ion o f Hoa re (1972) and s u p p o r t the v iew suggested b y W e n y o n (1926) t h a t t icks m i g h t p lay a ro le in t r a n ~ miss ion o f T r y p a n o s o m a theileri.

ACKNOWLEDGEMENTS

The au tho r s t h a n k Dr. M.A. G h a f o o r , Associa te Dean o f t he College o f Ve te r ina ry Science fo r p rov id ing the facilities. T h e y are also gra te fu l t o Mr. B.N. D e s h m u k h , the Techn ica l Assis tant , f o r he lp dur ing this s tudy .

REFERENCES

Arifdzhanov, K.A. and Nikitina, R.E., 1961. Detection of Crithidia hyalommae (O'Farrell 1913) in Hyalomma a. anatolicum (Koch, 1844) ticks. Zool. Zh., 40: 20--24.

Burgdorfer, W., Schmidt, M.L. and Hoogstraal, H., 1973. Detection of Trypanosoma theileri in Ethiopian cattle ticks. Acta Trop., 30: 340--346.

Hoare, C.A., 1972. The Trypanosomes of Mammals, Blackwell Scientific, Oxford, 136 pp. O'Farrell, W.R., 1913. Hereditary infection with special reference to its occurrence in

Hyalomma aegyptium infected with Crithidia hyalommae. Ann. Trop. Med. Parasitol., 7: 545.

Wenyon, C.M., 1926. Protozoology. A Manual for Medical Men, Veterinarians and Zoolo-gists. Bailli~re, Tindall and Cox, London.