A placebo-controlled double-blind trial for the treatment of Bancroftian filariasis with ivermectin or diethylcarbamazine

Abstract

Therapeutic efficacy and clinical side-effects of ivermectin (single dose of 100 μg/kg) and diethylcarbamazine (DEC) (3 mg/kg for one day, then 6 mg/kg daily for 12 d) were evaluated for microfilaricidal effect in Bancroftian filariasis. Seventy-one microfilaraemic consenting adult male patients (⩾100 microfilariae (mf)/ml) were randomly assigned to receive ivermectin, DEC or placebo and kept in hospital for 15 d. Those receiving placebo were treated with ivermectin on day 9. Ivermectin (19 ‘double-blinded’ and 22 ‘unblinded’ patients) caused an abrupt reduction in mf count to 1 · 5% of the pre-treatment level 12 h after drug administration and to 0 · 06% on day 14, with recrudescence to 1 · 8% after one month and to 9·2% after 3 months. DEC (30 patients) caused a gradual drop in mf count to 1 · 1% of the pre-treatment level on day 14, which increased to 2 · 4% after one and 3 months. The total scores of side-effects were 77 (1%), 305 (2·1%) and 311·5 (3·0%) for placebo, ivermectin and DEC respectively; the differences between DEC or ivermectin and placebo were statistically significant. Ivermectin produced lower side-reaction scores than DEC and the differences were highly significant at the 95% confidence level. Side-effects were mainly headache and body aches in the ivermectin patients, which appeared as early as 4 h after drug administration, resolved within 36 to 48 hours, and were significantly related to mf densities. Side-effects in DEC patients were mainly testicular and epididymal pain and swelling, unrelated to mf densities, which began at day 2 and continued to day 7. Single dose ivermectin was more effective in reducing microfilaraemia in Bancroftian filariasis than a 13 d course of DEC for a period of about 2 months after treatment, and side effects were of shorter duration.