Technical reports
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Browsing Technical reports by Author "Cunningham, M.P."
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Item A Note on the Susceptibility of Sheep and Goats to East Coast Fever(1974) Purnell, R.E.; Radley, D.E.; Cunningham, M.P.; East African Veterinary Research Organisation, P.O Box 32, Kikuyu, Kenya.In East Africa, where cattle, sheep and goats are commonly herded together, all three are regularly infested with Rhipicephalus appendiculatus ticks (Yeoman, 1966), the vectors of East Coast fever of cattle. Sheep and goats, while they are known to be susceptible to other species of Theileria (T. ovis and T. hirci) in various parts of the world, have never been shown to be infected with T. parva, the causative organism of East Coast fever, although there has always been speculation as to their potential ability to act as reservoirs of the parasite. Since we now have a number of low temperatures preserved stabilates of T. parva (Muguga) in this laboratory (Cunningham, Brown, et al, 1973), we decided to attempt to infect a new-born lamb and a new-born kid using relatively massive doses of T. parva infective material. A pregnant sheep and a pregnant goat, both of local native breed, were obtained. The sheep was shown to harbour occasional intra-erythrocytic piroplasms morphologically identified as T. ovis, whilst the goat apparently had no intra-erythrocytic parasites. Four hours after birth, the lamb was bled for serology and then inoculated subcutaneously in front of the right. Supported by a grant from the Pfizer Corporation, New York. shoulder with 10 ml of T. parva (Muguga) stabilate, two control cattle each receiving 1 ml of the stabilate. The kid was similarly bled and innoculated 23 hours after birth. Five cattle, which acted as controls on the infectivity of the stabilate inoculated into the kid, had each received 1 ml of the stabilate the previous week. The viability of the stabilate was also confirmed 11 weeks later when five cattle were each fatally infected by the inoculation of 1 ml. The rectal temperature of each animal was recorded daily. Giemsa-stained biopsy smears from the local drainage prescapular lymph nodes were examined daily after inoculation, and Giemsa-stained blood smears examined from the 10th day after inoculation, for the following month. Although local drainage lymph nodes of both animals, particularly that of the lamb, became hyperplastic and enlarged, no theilerial parasites were observed in the nodes or in the blood. All control cattle, except one which died of intercurrent disease, died of East Coast fever. Comparison of pre-inoculation and 28 days post inoculation serum samples, using the indirect fluorescent antibody test with a bovine conjugate (Burridge and Kimber, 1973), revealed no antibody response to T. parva antigens in the lamb or the kid. We conclude therefore, that neither animal was susceptible to infection with T. parva (Muguga) even when challenged with a dose of infective material much greater than they would encounter in an ECF enzootic area.
