Efficacy of ivermectin for chronic strongyloidiasis: two single doses given 2 weeks apart.

We assessed the efficacy and adverse effects of ivermectin for the treatment of chronic strongyloidiasis. Fifty patients were treated with a single dose of ivermectin at approximately 200 microg/kg, and the dose was repeated 2 weeks later. The eradication rate was 96% (48 of 50 patients) at 2 weeks after the first dose and 98% at 2 weeks after the second dose (49 of 50 patients). In the latter cases, no recurrence was noted at the end of the 4-month post-treatment follow-up period. The gastrointestinal symptoms observed most frequently before the treatment were borborygmus, constipation, and diarrhea. These symptoms improved in the majority of patients after the treatment. Side effects, including nausea and vomiting, occurred in 1 patient (2%), but these were mild and transient. Although abnormal values in laboratory tests were observed in 4 patients (8%), they were mild, and no particular clinical care was required. Thus, ivermectin showed an excellent antihelminthic effect, with little toxicity. Our results indicate that a regimen of two single doses of 200 microg/kg ivermectin, given 2 weeks apart, is clinically suitable for the treatment of chronic strongyloidiasis.