Double-blind study of ivermectin and diethylcarbamazine in African onchocerciasis patients with ocular involvement.

In a randomised double-blind study, ivermectin was compared with diethylcarbamazine (DEC) and placebo in the treatment of onchocerciasis in 30 male patients from Mali with moderate to heavy Onchocerca volvulus infections and ocular involvement. 10 patients received a single oral dose of ivermectin, 12 mg, 10 received DEC daily for eight days (total dose 1.3 g), and 10 received matching placebo. Patients were examined periodically for twelve months. Punctate keratitis disappeared in 6 of 7 ivermectin patients but increased in DEC patients. Numbers of O volvulus microfilariae (mf) in the anterior chamber decreased slowly and eventually disappeared in most ivermectin patients during the six months following treatment; anterior chamber mf disappeared more rapidly in some patients after DEC, but reappeared within six months of stopping treatment. Both ivermectin and DEC caused a prompt decrease in mean skin mf density; density then increased in both groups over the twelve month observation period, reaching 9% of pretreatment values in ivermectin patients and 45% in the DEC group. Analysis of adult O volvulus from nodules excised at three and twelve months post treatment showed no effect of either drug on viability; however, there was evidence of degeneration of intra-uterine developing mf in the ivermectin group. Side-effects were less frequent and less severe in ivermectin patients than in DEC patients. Ivermectin as a single oral dose appears to be a more effective microfilaricidal drug than DEC in onchocerciasis.