The effect of multiple ivermectin treatments on infection of Simulium ochraceum with Onchocerca volvulus.

Ivermectin, a broad spectrum antiparasitic agent, interrupted the uptake of Onchocerca volvulus microfilariae by Simulium ochraceum from a group of human volunteers given multiple oral treatments of 200 micrograms/kg body weight. Two treatments, given at 7 month intervals, resulted in almost complete suppression of developing or infective larvae in the vector population for a 6 month period. The overall decline following 2 treatments was an order of magnitude lower than the pretreatment level. Ivermectin administration, in addition to the beneficial clinical effects, also could be useful for the control of human onchocerciasis as an independent measure or in conjunction with vector control.