Integrated tick and tick-borne disease control trials in crossbred dairy cattle in Malawi.

Crossbred dairy heifers on a farm in an East Coast fever (ECF) endemic area in Malawi were immunised against Theileria parva, Anaplasma spp., Babesia bigemina, Babesia bovis and Cowdria ruminantium. They were treated at infrequent intervals with chlorfenvinphos to limit infestation with adult ticks, without providing complete tick control. In one trial, which tested a threshold dipping regimen, 20 heifers were dipped only once in 6 months to control a flush of Boophilus microplus. Unimmunised controls showed serological evidence of exposure to T. parva and B. bigemina, and one died of ECF, but there were no incidents of tick-borne disease in the immunised group. In a second trial, which tested a strategic dipping regimen, 107 animals were dipped 9 times over a 6 month period. Despite heavy challenge by B. bovis and moderate challenge by B. bigemina and Anaplasma spp. demonstrated serologically, there was only a single clinical case of babesiosis. The observations provide encouragement for the introduction of integrated tick and tick-borne disease control programmes in improved cattle in ECF endemic areas.