Assessment of natural ixodid tick infestations in sheep

Assessment of adult female tick burden was performed on 160,151 and 150 yearling sheep in coastal Kenya at the end of three consecutive infestation periods, respectively. The main attachment sites of fully engorged female ticks were ears, head, body sides, perianal and scrotal/udder regions. Averaged over the three sampling periods, 87 percent of the ticks counted were on the ears. The correlation between tick count on the ears and total body tick count was high (0.97). The average repeatability for two recorders of tick counts on the ears and the whole body was similar and high (0.95 and 0.93, respectively). The results suggest the ear tick count is a good indicator of tick burden on sheep exposed to natural tick challenge consisting predominantly of Rhipicephalus appendicultatus and R. evertsi.