Effect of ivermectin treatment on microfilarial load in patients with Onchocerca volvulus in Bebeka, Ethiopia

In April 1990, one hundred ninety people from Bebeka Coffee Plantation, Kefa administrative region, western Ethiopia, all with moderate to heavy infection with Onchocerca volvulus were treated with ivermectin (150 mcg/kg body wt.). Clinical examination and microfilarial counts in skin snips were repeated at intervals for eight months. Therapy was associated with minimal side effects. Significant difference in mean microfilarial load was observed throughout the eight months post-treatment period. Difference in repopulation of microfilariae between four and eight months was not significant in either sex and all ages. Of all cases, 71 (37.5%) maintained zero microfilarial counts after four months, while only 38 (20%) remained at zero level until the end of eight months. The merit of a yearly treatment programme is discussed.