ONCHOCERCA-VOLVULUS - STRIKING DECREASE IN TRANSMISSION IN THE VINA VALLEY (CAMEROON) AFTER 8 ANNUAL LARGE-SCALE IVERMECTIN TREATMENTS

The impact of repealed ivermectin treatments on the transmission of On chocerca volvulus was evaluated in the Vina valley, northern Cameroon, by comparing the prevalence and intensity of infection observed in un treated 5-7 years old children living in the treated communities befor e and after 7-8 successive annual rounds of ivermectin treatment of th e general population of those communities. The villages studied were N goumi and Babidan, where the initial community microfilarial loads (CM FL) were 83.7 and 216.4 microfilariae per skin snip, respectively In 1 995, after 8 annual treatments, the prevalence and intensity in Ngoumi had decreased by more than 90%, compared with the pretreatment values , and the prevalence continued to decrease between 1992 and 1995. In B abidan, after 7 annual treatments, the prevalence and intensity had al so decreased significantly, but less than in Ngoumi. The study demonst rated that repeated treatments brought about a notable reduction in th e transmission of O. volvulus in the Vina valley, despite unfavourable factors such as mean drug coverages below 60% and the good vectorial competence of Simulium damnosum s.s. and S sirbanum.