The chemotherapy of onchocerciasis IX

Abstract

Forty male patients with onchocerciasis who were treated with diethylcarbamazine (DEC) were entered into a double-blind study using prednisone plus cyproheptadine or matching placebo to try to alleviate the reactions to treatment. Patients received either both active drugs or both placebo preparations. Prednisone was given in a dose of 20 mg t.i.d. for three days starting one day before DEC (200 mg day⁻¹ for ten days). Cyproheptadine was given in a dose of 4 mg t.i.d. for two days. The reactions to treatment were quantitated using a recently described scoring system.

The mean (±S.D.) microfilarial count in the placebo group prior to therapy was 421·2±43·4 and in the active treatment group was 417·8±52·6. Prednisone and cyproheptadine had no significant effect on the overall severity of the Mazzotti reaction over the eight days of the study. However, the reaction scores on Day 1 and Day 2 were significantly less in the active treatment group than in the placebo group (P<0·001). Thereafter the reaction scores were greater in the active treatment group. The major effects of prednisone and cyproheptadine were seen on the cardiovascular, febrile and glandular aspects of the Mazzotti reaction. No major effect was seen on the skin rash or pruritus.

Prednisone significantly reduced the efficacy of DEC in killing microfilariae but the effects were only seen at 24 hours and 48 hours after starting DEC. One week after starting DEC microfilarial counts were similar in both groups.

We conclude that cyproheptadine does not have any beneficial effect in alleviating the severity of the Mazzotti reaction. In this study prednisone therapy was stopped too soon and there was a rebound in the reaction score after 48 hours. We suggest that prednisone (20 mg t.i.d.) is given for three days before being decreased over the next four days. This dosage scheme should alleviate most of the reactions to treatment while at the same time interfering as little as possible with the destructive effect of DEC on the microfilariae.