Browsing by Author "Grootenhuis, J.G."
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Item Further Studies on the Immunization of Cattle against Theileria La Wrencei by Infection and Chemoprophylaxis(Elsevier, 1979) Radley, D.E.; Young, A.S.; Grootenhuis, J.G.; Cunningham, M.P.; Dolan, T.T.; Morzaria, S.P.; Veterinary Research Department, Kenya Agricultural Research Institute, Muguga; Veterinary Laboratories, Kabete (Kenya); International Centre for Insect Physiology and Ecology, Kenya; MAFF Central Veterinary Laboratories, Great Britain.Three experiments were carried out to ascertain the feasibility of immunization of cattle against Theileria lawrencei using infection and chemoprophylaxis. In the first two experiments, cattle were immunized with a combination of three theilerial strains (‘cocktail’) and simultaneous treatment with an experimental formulation of oxytetracycline. When groups of these immunized cattle were challenged with stabilates of T. lawrencei isolated from African buffalo captured in Kenya and Tanzania, many of the immunized cattle had severe reactions and 3 out of 20 died, as did 18 of the 20 controls. A paddock containing carrier buffalo which maintained a population of Rhipicephalus appendiculatus continuously infected with T. lawrencei, was used in a second and third experiments. Cocktail immunized and control cattle were exposed to this tick challenge, and 55% of the immunized animals and 91% of the controls died. The protection provided by cocktail immunization was compared with immunization using different isolates of T. lawrencei from the buffalo paddock, but little difference in the degree of protection was detected. However, a high degree of immunity was observed when cocktail immunized cattle which had undergone a T. lawrencei stabilate challenge were exposed in the paddock. Only mild reactions were seen and no deaths occurred. Field immunization of cattle against T. lawrencei may be difficult due to immunovariants of this parasite emanating from the buffalo populations.Item The incidence of Theilerial Parasites in East African Buffalo (Syncerus caffer).(1978) Young, A.S.; Brown, C.G.; Burridge, M.J.; Grootenhuis, J.G.; Kanhai, G.K.; Purnell, R.E.; Stagg, D.A.; Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research Organisation, Muguga245 buffalo from 13 areas of East Africa were examined for theilerial infections. The vast majority of buffalo (97.1%) examined had piroplasms in their erythrocytes. Theileria lawrencei was isolated from the buffalo by tick feeding and cell culture and was found to be common in most of these buffalo populations. Also over 50% of the buffalo had indirect fluorescent antibody (IFA) titres to T. lawrencei. T. mutans was only isolated from 3 buffalo populations but is probably common. Haematoxenus sp. was detected in the blood of 56% of the buffalo sampled. In the light of these results the role of buffalo as a reservoir of cattle pathogenic theilerioses in East Africa is discussed.Item Infection of Mammalian Cells with Theileria Species(1983) Stagg, D.A.; Young, A.S.; Leitch, B.L.; Grootenhuis, J.G.; Dolan, T.T.; Veterinary Research Department, Kenya Agricultural Research Institute, Muguga, P.O. Box 32, Kikuyu, KenyaExperiments were carried out to determine the susceptibility of mammalian cells to infection with different species of Theileria in vitro. Sporozoites of Theileria parva (parva), Theileria parva (lawrencei) and Theileria taurotragi were isolated from Rhipicephalus appendiculatus ticks by grinding infected ticks in medium, filtering the suspension and concentrating by centrifugation. The sporozoites were used in attempts to infect in vitro peripheral blood leucocytes harvested from 16 different mammalian species which included 12 species of Bovidae from 6 different sub-families. The technique was shown to be both sensitive and reproducible. The sporozoites of T. parva (parva) infected and transformed cells from 2 species of the sub-family Bovinae, the two cattle types and African buffalo. Theileria parva (lawrencei) infected and transformed cells from the two cattle types, African buffalo and Defassa waterbuck. Theileria taurotragi sporozoites infected in vitro cells from 11 different species of Bovidae which were members of 6 sub-families; Bovinae, Tragelaphinae, Reduncinae, Alcelaphinae, Antilopinae and Caprinae. Transformed lymphoblastoid cell lines were established from 7 of the species infected. Sporozoite attachment and infection was not observed with non-susceptible bovid host cells, nor were any of the non-bovid leucocytes infected by the parasites. The host range observed in this study corresponded to the known host range in vivo.Item Isolation of a Theileria Species from Eland (Taurotragus Oryx) Infective for Cattle(1977) Young, A.S.; Grootenhuis, J.G.; Kimber, C.D.; Kanhai, G.K.; East African Veterinary Research Organisation, Muguga, Kikuyu, KenyaTheileria infections were induced in cattle by feeding ticks on them from 3 sources:(a) adult rhipicephalid ticks obtained from the vegetation in a paddock containing an eland EAO at the Animal Orphanage, Nairobi National Park, Kenya, (b) Rhipicephalus appendiculatus adults fed as nymphs on the same eland, (c) R. pulchellus adults fed as nymphs on an eland W 68 captured in the Machakos district of Kenya. Both eland were harbouring Theileria parasites at the time nymphal ticks were fed. Mild infections were produced when adult ticks from these 3 batches were applied to cattle associated with low numbers of schizonts and piroplasms. The indirect fluorescent antibody test demonstrated that cattle recovered from infections resulting from the above 3 tick batches from eland W 68 and EAO produced antibodies which reacted with schizont antigen of the Theileria species (eland) and Theileria species (Githunguri) which had been isolated from cattle and not to antigens of other Theileria species used. The cattle recovered from the Theileria species (eland) were fully susceptible to a lethal challenge of a T. parva (Muguga) stabilate. It was concluded that the Theileria species (eland) and Theileria species (Githunguri) may be closely related and could represent a new species of Theileria infective to cattle.
