Abstract:
Tick-borne diseases are a major impediment to improved productivity of livestock in sub-Saharan Africa. Improved control
of these diseases would be assisted by detailed epidemiological data. Herewe used longitudinal, serological data to determine
the patterns of exposure to Theileria parva, Theileria mutans, Babesia bigemina and Anaplasma marginale from 548
indigenous calves in western Kenya. The percentage of calves seropositive for the first three parasites declined from initial
high levels due to maternal antibody until week 16, after which the percentage increased until the end of the study. In
contrast, the percentage of calves seropositive for T. mutans increased from week 6 and reached a maximal level at week 16.
Overall 423 (77%) calves seroconverted to T. parva, 451 (82%) to T. mutans, 195 (36%) to B. bigemina and 275 (50%) to
A. marginale. Theileria parva antibody levels were sustained following infection, in contrast to those of the other three
haemoparasites. Three times as many calves seroconverted to T. mutans before seroconverting to T. parva. No T. parva
antibody response was detected in 25 calves that died of T. parva infection, suggesting that most deaths due to T. parva are
the result of acute disease from primary exposure.
