Chemotherapy of onchocerciasis with high doses of diethylcarbamazine or a single dose of ivermectin: microfilaria levels and side effects.

Fifty adult male subjects with moderate to heavy onchocerciasis from the Liberian rain forest were selected for a double-blind placebo-controlled chemotherapy study. The effects of high doses of diethylcarbamazine (DEC) - 30 mg/kg/d - over one week preceded by a one week initial treatment with normal oral doses of DEC or DEC lotion were compared with a single dose of ivermectin (150 micrograms/kg) and placebo. During the initial treatment DEC tablets or lotion caused distinctly more frequent and severe reactions than did invermectin. The reactions to ivermectin did not differ from those of the placebo patients. High doses of DEC caused, in about half of the patients, headache, dizziness, nausea or vomiting. DEC markedly increased the number of corneal microfilariae and of corneal opacities compared to ivermectin. All changes resolved with a return to pretreatment findings two months after treatment. The three treatment groups showed no differences at the ten months follow-up. In all treated patients skin microfilaria counts fell almost to zero by the end of the two week therapy. In the ivermectin group microfilaria counts remained significantly lower than in the DEC patients at the two and ten months examinations. In summary, ivermectin was much better tolerated than DEC and had a longer lasting effect on the microfilariae in the skin. Since high doses of DEC were less effective and caused more frequent and severe side effects, this approach cannot be recommended for treatment of onchocerciasis.