Control of bancroftian filariasis in an endemic area of Polynesia by ivermectin 400 micrograms/kg

Community treatment with ivermectin was implemented in Opoa, French Polynesia from April 1991 to October 1993. All consenting inhabitants aged 3 years or more were treated with twice-yearly single doses of ivermectin, pregnant women excepted. A dosage of 100 microgram/kg was used for the 3 first treatments and then abandoned because it did not reduce the prevalence of microfilariae (mf) carriers. With a dosage of 400 micrograms/kg dosage, this prevalence decreased dramatically from 21% to 7%, and the mf level in carriers dropped to only 0.5% of its initial value after 3 treatments. The 400 micrograms/kg dosage was well tolerated and compliance was excellent. The twice-yearly single dose strategy with ivermectin at 400 micrograms/kg is safe and highly effective for filariasis control in an endemic area.