Long-term suppression of Mansonella streptocerca microfilariae after treatment with ivermectin

The long-term effect of a single oral dose of 150 mu g/kg of body weight of ivermectin on Mansonella streptocerca microfilariae was studied in western Uganda, Before treatment, the geometric mean microfilaria density (mf) in 93 infected persons was 2.4 mf/mg of skin (range, 0.1-42.6). One year after treatment, 43 persons (46%) were microfilaria-negative, and the geometric mean in the remaining persons dropped significantly, to 0.7 mf/mg (range, 0 .1-6.9), Thus, ivermectin is highly effective against M. streptocerca, and a single dose leads to a sustained suppression of microfilariae in skin. In Africa, ivermectin is used for mass treatment to control Onchocerca volvul us and Wuchereria bancrofti, Because these filarial parasites are often coe ndemic with M. streptocerca, the treated population may receive the additio nal benefit of suppression of M. streptocerca microfilariae.