ADVANTAGES OF IVERMECTIN AT A SINGLE-DOSE OF 400 MU-G KG COMPARED WITH 100 MU-G/KG FOR COMMUNITY TREATMENT OF LYMPHATIC FILARIASIS IN POLYNESIA/

In April and October in 1991-1993, 5 supervised single doses of iverme ctin were given to inhabitants aged greater than or equal to 3 years i n a Polynesian district: the first 3 treatments were with 100 mu g/kg and the 2 latter with 400 mu g/kg. At each treatment, about 97% of the eligible population (899) were treated and blood samples were collect ed just before treatment from 96% of the 613 inhabitants aged greater than or equal to 15 years. Following the 5 successive treatments, adve rse reactions were observed in, respectively 23.8, 13, 6.2, 13.6 and 7 .9% of the microfilariae (mf) carriers, and in less than 1% of amicrof ilaraemic subjects. Neither the frequency nor the intensity of adverse reactions was significantly different between single doses of 100 mu g/kg and 400 mu g/kg. Although the geometric mean microfilaraemia (GMM ) was reduced, the mf carrier prevalence remained unchanged before and after 3 mass treatments with 100 mu g/kg (21.4 and 20. 7% respectivel y), and the mf recurrence rate 6 months after each dose of 100 mu g/kg was roughly stable (respectively, 34.3%, 21.6% and 31.2% of the initi al GMM) In contrast, after one dose round of 400 mu g/kg, the mf carri er prevalence decreased significantly to 14. 9% (P<10(-6)), and the mf recurrence rate dropped to 9. 9% (P<10(-3)) of the initial GMM. These results confirm the safety and the effectiveness of 400 mu g/kg of iv ermectin for lymphatic filariasis control.