Transmission of Onchocerciasis by local black flies in the rain forest of Tai, Cote d'Ivoire, before massive flow of Refugees.

Several studies have been carried out on the transmission of Onchocerciasis by Simulium damnosum s.l. in the forest zone of Cote d'Ivoire. This study carried out in 1979-7980 was devoted to determine the risk of onchocerciasis transmission inside and outside the rain forest of Tai (5 degrees 50' N -7 degrees 25' W) We present the vectorial capacity of S. sanctipauli in the region of Tai before massive flow of refugees from areas of Liberia without any control Programme. The results of micromorphological technics for determination of S. damnosum adults showed that mainly females of S. sanctipauli were present. The studied populations had low parturity rates: 39.2% outside and 30.9% of parous flies inside the rain forest. The parasitic rates (0.4% of infectious females outside and 0.1% inside) and their parasitic loads (15 and 3 infective larvae per 1000 parous female respectively outside and inside the rain forest) were low, consequently their vectorial capacity with Onchocerca volvulus was almost non-existent in natural conditions. Before massive flow of refugees including persons carrying microfilariae, there were no problem of Onchocerciasis within and outside the rain forest of Tai: However the massive flow of refugees and the deforestation for growing crops can create situations favourable to the installation of more efficient vectors, increase man/vector contact and contribute to more intense Onchocerciasis transmission. The monitoring of onchocerciasis transmission is necessary.