The chemotherapy of onchocerciasis. XI. A double-blind comparative study of ivermectin, diethylcarbamazine and placebo in human onchocerciasis in northern Ghana.

Fifty-nine onchocerciasis patients with ocular involvement were randomly assigned to receive either 12 mg of ivermectin in a single dose or 1300 mg of diethylcarbamazine over eight days or matching placebo capsules. Detailed standardized follow-up examination was carried out for one year. Both ivermectin and diethylcarbamazine rapidly reduced skin microfilarial counts to a similar extent over six months, after which counts increased significantly more with diethylcarbamazine. Diethylcarbamazine rapidly eliminated microfilariae from the eye, while ivermectin did so over six months. Reactions to treatment were more severe with diethylcarbamazine, which also produced clinical ocular deficiency in two patients. Ivermectin produced intra-uterine sequestration and degeneration of microfilariae in adult worms, which may account for its ability to produce prolonged suppression of skin microfilariae. Ivermectin proved superior to diethylcarbamazine in safety, tolerance and efficacy, but further work is needed to assess fully its effects in patients with heavy intraocular microfilarial loads.