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TROPICAL THEILERIOSIS IN INDIA
D.K. Singh

Courtesy : Festschrift - Dr. S. Ramachandran

Bovine tropical theileriosis (Theileria annulata infection), an inapparent infection of indigenous cattle and buffaloes has emerged as one of the fatal diseases of taurine cattle and their crosses since the early 1960s, due to large scale cross-breeding programmes. The disease is present in the entire Indian subcontinent, China, Pakistan, Commonwealth of Independent States (CIS), Iraq, Turkey and some of the North African countries viz., Egypt and Sudan. It is endemic in India. 

The infection was first reported during 1905-06 in hill bulls showing febrile reactions with small piroplasms in their peripheral blood smears. Subsequently, Sir Arnold Theiler confirmed occurrence of theileriosis in the Central Provinces (1). Later, several reports describing sporadic cases of the disease appeared in the literature (2,3,4). 

During the late sixties, with the implementation of large scale cross-breeding programme of cattle taken up for milk production enhancement, tropical theileriosis emerged as a serious problem (5,6). 

During 1960s, 70s and 80s tropical theileriosis was one of the major health problems of some 10 million exotic and crossbred (CB) cattle in India. Although systematic studies were not carried-out to study its incidence, out of 5454 blood smears of apparently normal CB cattle examined during the year 1989 at various centres of All India Coordinated Research Project (AICRP) of the Indian Council of Agricultural Research, 14.94 per cent had revealed T. annulata. Results of serological surveys conducted under the same project indicated that 30-60 per cent of the cross-bred cattle were positive for antibodies to T. annulata piroplasms, all over India, except in the Himalayan region, where climate is not favourable for tick activity (7).

Examination of the methyl green pyronin-stained salivary glands of ticks, randomly collected from dairy animals in Kaira district of Gujarat, during 1989, revealed that 37.50 per cent male and 48.50 per cent female Hyalomma anatolicum anatolicum adults were positive for theilerial masses, with an average of 50.50 and 80.70 per cent infected acini per male and female ticks, respectively (8). In Kaira district again, during 1988-99, of an approximate population of 40,000 exotic and CB cattle, 3800 acute cases of tropical theileriosis were recorded. Outbreaks on organized farms were also not uncommon. At the sperm Station, Ode, in Kaira district, during 1983, out of 125 cross bred pregnant heifers, 43 developed theileriosis, leading to abortion in 11 and death of 12. At a farm in Hyderabad, theileriosis had been a constant feature in Holstein-Friesian cattle, until the animals were vaccinated. At Lam Farm in Guntur district, Andhra Pradesh during 1989, in a total of 136 animals, 70 (51.89%) suffered in one outbreak of theileriosis and 19 (27%) died inspite of treatment. 

Apart from mortality, indirect losses occur from tropical theileriosis due to loss of productivity, infertility and high cost of treatment. As per one estimate annual loss due to tropical theileriosis, in a population of 6.6 million cross bred cows in India, during 1989 alone, was around $ 210 million (9). 

Research in India
The first systematic research on tropical theileriosis was initiated during late 1960s at Haryana Agricultural University, Hissar, wherein morphology, pathology and chemotherapy of the parasite were studied in large number of cases recorded at Government Livestock Farm, Hissar (10). 

Other centers also undertook extensive studies on the epidemiology, clinical pathology, haematology, transmission, serology, immunology, chemotherapy and immunization (10,11,12,13,14,15,16,17,18,19). Studies at Madras and Gujarat Agricultural Universities were mainly concentrated on vector ticks and their prevalence. 

Realising its importance, the Indian Council of Agricultural Research, in technical collaboration with University of Illinois, USA, under USAID programme operated an AICRP on Blood Protista with centres, at the Haryana Agricultural University (HAU), Hissar, Punjab Agricultural University (PAU), Ludhiana, Indian Veterinary Research Institute (IVRI), Izatnagar, Madras Veterinary College, Chennai, Veterinary College, Patna and a non-funded centre at National Dairy Development Board (NDDB), Anand. Research was undertaken at these centres, wherein major thrust had been on epidemiology, serology and vaccinology of tropical theileriosis. 

Serology 
Indirect fluorescent antibody test was extensively used for the study of incidence, epidemiology and serological response of immunized animals (20,21). Sensitive ELISA’s were developed at PAU, Ludhiana and Veterinary College, Bangalore (22,23)

Chemotherapy
Several chemotherapeutic agents were tried in clinical cases of theileriosis with partial success. The drugs used included tetracyclines in high doses, along with antimalarial, halofuginone lactate, Menoctone, Clexon (Wellcome compound 993-C), Buparvaquone (Wellcome-720-C). Buparvaquone (Butalex-Wellcome) is reported to be the most effective drug of which single intramuscular injection at the rate of 2.5 mg/kg body weight, at early stages of disease, provides recovery (24). Presently Butalex is commercially available in India, however, its use is cost prohibitive.

Immunization
Initial immunization trials were conducted by infection and treatment methods wherein the animals were infected either by attaching infective ticks or by injecting infective ground-up tick supernates and simultaneous treatment with tetracyclines as prophylactic agent (25,26). Some unsuccessful immunization trials were conducted with gamma ray irradiated sporozoites (18). 

Major emphasis on research in India has been on the development of in vitro derived culture vaccines (27,7). Published reports indicate successful experimental immunization of cattle with these vaccines (21,22,28).
However, a most exhaustive research for the development and evaluation of cell culture derived vaccine was undertaken by the NDDB, Anand and evaluated for dose response, effect of storage temperature, serological reactions and challenge reaction following infective tick challenge (29,20). Before its commercialization the vaccine was extensively evaluated under field conditions. Its technology was patented under Indian patent rules and the know-how transferred to Indian Immunologicals Ltd., Hyderabad. 

The commercial vaccine contains 5x106 lymphoblastoid cells infected with T. annulata schizonts attenuated through 150 in vitro passages. Presently, the vaccine is supplied in 2 and 5 dose vials stored in liquid nitrogen. Before use, the contents of the vials are reconstituted in a supplied diluent. All susceptible animals above two months of age can be vaccinated without any risk. Highly susceptible animals may show mild febrile reactions and marginal increase in the size of nearest superficial lymph node. Epidemiological studies of the disease and serological response of animals under field conditions suggest that animals in organized farms in the absence of routine infective tick challenge are protected for a period of three years following vaccination. Whereas, under field conditions, where infective tick challenge is common, vaccination once in a life time is adequate. 

Present research trends
There is need to develop vaccine storage technology which will eliminate the use of liquid nitrogen for the storage of the vaccine. Also research is being undertaken at NDDB and certain other laboratories for developing recombinant vaccine against the ticks, the vector of theileriosis and other protista. 

References

1. Dutta, S. (1963). Progress of Veterinary Research. In fifty years of science in India. Indian Sci. Cong. Ass., Calcutta 17. 
2. Sen, S.K. and Srinivasan, M.K. (1937). Indian J. vet. Sci. Anim. Hlth., 7: 15. 
3. Raghavachari, K. (1944). Indian Fmg., 5: 208.
4. Kathuria, J.D. (1963). Indian vet. J., 40: 357. 
5. Narshimamurthy, G. et al. (1970). Indian vet. J., 47: 357. 
6. Bali, B.D. (1970). Haryana Vet., 9: 42. 
7. Anon. (1989). Annual report of All India Coordinated Research Project of ICAR on Blood Protista with particular reference to immuno-prophylaxis and control. Project Coordinator. Haryana Agricultural University, Hisar, India. 
8. Anon. (1988-89). Annual report of Animal Disease Research Laboratory, National Dairy Development Board, Anand, India. 
9. Singh, D.K. (1991). “Theileriosis in India”. In Orientation and Coordination of Research on Tropical Theileriosis. p. 23. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India. 
10. Gautam, O.P. (1974). Theileriosis in India. 3rd Int. Cong. Parasit. Munich, West Germany. 
11. Sharma, R.D. and Gautam, O.P. (1971). Indian vet. J., 48: 83. 
12. Gautam, O.P. (1976). Theileria annutala infection in India. International Conference on Tick Borne Diseases and their Vectors. Centre for Tropical Veterinary Medicine. University of Edinburgh, U.K. 
13. Bhattacharyulu, Y. et al. (1975). Annates de Parasitologie, 50: 379. 
14. Bhattacharyulu, Y. et al. (1975). Parasitology, 71: 1. 
15. Dhar, S. and Gautam, O.P. (1977). Indian J. Anim. Sci., 47: 720.
16. Dhar, S. and Gautam, O.P. (1977). Indian J. Anim. Sci., 47: 389. 
17. Singh, D.K. et al. (1977). Res. vet. Sci., 23: 391. 
18. Singh, D.K. et al. (1978). Am. J. vet. Res., 46: 767. 
19. Singh, D.K. et al. (1979). Trop. Anim. Hlth. Prod., 11: 87. 
20. Raghav, P.R.S. et al. (1991). In Orientation and Coordination of Research on Tropical Theileriosis. p. 39. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India.
21. Dhar, S. (1991). In Orientation and Coordination of Research on Tropical Theileriosis. p. 107. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India.
22. Grewal, A.S. et al. (1991). In Orientation and Coordination of Research on Tropical Theileriosis. p. 114. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India.
23. Thimma Reddy, P.M. et al. (1991). In Orientation and Coordination of Research on Tropical Theileriosis. p. 104. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India. 
24. Singh, D.K. et al. (1993). Res. vet. Sci., 54: 68. 
25. Gill, B.S. et al. (1976). Res. vet. Sci., 21: 146. 
26. Khanna, B.M. et al. (1980). Proc. Seminar in Haemoprotozoan Diseases. Oct. 27 - Nov. 1. p. 74. Haryana Agricultural University, Hisar.
27. Gill, B.S. et al. (1976). Nature, 264: 355. 
28. Subramanian, G. (1991). In Orientation and Coordination of Research on Tropical Theileriosis, p. 112. Eds. Singh, D.K. and Varshney, B.C., National Dairy Development Board, Anand, India. 
29. Singh, D.K. (1990). Parassitologia, 37: 33. 

Authors Corresponding address: 

Dr. D.K. Singh
Sr. General Manager, R.& D., National Dairy Development Board, Anand - 388 001, India

The views expressed in this article are of the author(s), and any clarifications can be obtained from the author(s).