Fluorescein angiographic studies of mebendazole treatment for onchocerciasis.

Mebendazole was compared to placebo treatment in a prospective double-masked study of the treatment of onchocerciasis. Twenty Ghanaian men were randomly assigned to one of two groups and received either mebendazole 2 G per day for 14 days preceded by 300 mg of levamisole in 2 doses or placebo vitamin tablets for 14 days. They were then followed for 12 months. Systemic side effects during the first 2 weeks of treatment were uncommon in each group. Similarly, ocular changes associated with a microfilaricidal action were infrequent. No fluorescein angiographic changes attributable to treatment appeared during the one-year follow up although there was progression of ocular disease in some men in each group. Skin microfilarial (mf) counts fell significantly in both groups at 1 week but returned toward pretreatment levels at 3 months and fell again by 12 months. At no time was there a difference between the placebo-treated control group and the mebendazole/levamisole group in terms of mf counts, ocular changes, clinical changes, biochemical parameters, nor was there a difference in the status of adult worms or embryogenesis assessed in nodules excised at 5 months. These results suggest that, in this study at least, mebendazole/levamisole was no more effective than placebo in treating onchocerciasis. Why mebendazole, which has been previously reported to both suppress embryogenesis and lower skin mf counts, had no effect in this study is unknown.