Epidemiological aspects and economic impact of bovine theileriosis (East Coast fever) and its control: a preliminary assessment with special reference to Kibaha district, Tanzania.

A cross-sectional study based on clinical examination, inspection of herd health records and a questionnaire was designed to determine the epidemiology, economics and potential impact of immunisation against theileriosis in Tanzania. The results showed annual theileriosis costs to be US$ 205.40 per head, whereas the introduction of immunisation reduced this by 40-68% depending on the post immunisation dipping strategy adopted. Morbidity risk due to theileriosis was 0.048 in immunised and 0.235 in non-immunised cattle, and the difference was significant (chi(2)=66.7; P=0.000). The questionnaire results indicated that immunised cattle had a significantly (chi(2)=6; P=0.015) higher risk of anaplasmosis compared with non-immunised cattle, whereas the risk of bovine babesiosis did not differ significantly (chi(2)=0.06; P=0.807) between the two groups. Mortality risk due to anaplasmosis was 0.046 in immunised and 0.018 in non-immunised cattle and this difference was statistically significant (chi(2)=4.48; P=0.043). The theileriosis mortality risk was 0.203 in the non-immunised cattle, while the risk was 0.009 in the immunised cattle and these differences were also significant (chi(2)=103; P=0.000). It was concluded that farmers who have immunised their cattle may cautiously cut down acaricide application by 50% for extensively grazed herds and by 75% for zero grazed animals depending on the level of tick challenge at the herd level.