Theileriosis: The Exposure of Immunised Cattle in Atheileria Lawrencei Enzootic Area

Abstract

Three groups of steers were exposed to field challenge in a T. lawrencei-enzootic area of Kenya. Four out of five ECF-susceptible steers and four out of five steers immunised against T. parva (Muguga) died of theileriosis, the surviving animals experiencing severe reactions. On the other hand, all five steers immunised against T. parva (Muguga) and a strain of theileria probably homologous with the one present in the area of exposure, survived and only experienced mild reactions. These results indicated that immunisation of cattle with T. parva (Muguga) may not necessarily protect them against field challenge with certain T. lawrencei-type strains, but that immunisation with an apparently homologous strain of theileria may well do so.