Mortality, weight loss and anaemia in Bos taurus calves exposed to Boophilus microplus ticks in the tropics of Colombia.

One hundred and sixteen pure-bred Normandy calves previously immunised against babesiosis and anaplasmosis were transported to the Caribbean Coast of Colombia where they divided into 2 equal groups and placed in separate pastures. One group sustained heavy infestation with Boophilus microplus ticks. The second group became lightly infested. The heavily infested calves suffered average losses in body weight of 38 kg and a 48% decrease in mean packed cell volume. Twenty-three (40%) died 16 to 39 days following arrival from severe ixodiasis and babesiosis. Mortality did not occur nor were significant weight losses observed in the group of lightly infested calves.