Effects of repeated ivermectin treatment in onchocerciasis.

A group of 87 onchocerciasis patients from a hyperendemic area without vector control was treated with a single dose of 150 micrograms/kg ivermectin. A second, third and fourth dose was administered 5, 12 and 17 months later to 44, 35 and 25 patients. Skin snip loads reduced substantially following each consecutive dose. However, after three doses 44% of the patients remained skin snip positive. Side-effects decreased from 32.2% requiring medical treatment at the first dose to none after the fourth dose. From this study it was concluded that a complete eradication of microfilariae in skin snips in severely infected persons living in a hyperendemic area without vector control is probably not feasible. Medical supervision for the observation of side-effects after the third dose can be limited.