Chrysops silacea and C. dimidiata: fly densities and infection rates with Loa loa in the Chaillu mountains, Congo Republic.

The densities, infection rates with Loa loa, and parous rates of Chrysops silacea and C. dimidiata were studied in various ecological zones throughout the Chaillu mountains in the People's Republic of the Congo. In the rainy season, C. dimidiata was the major vector in the forest, whereas C. silacea was predominant in the cleared forest zones. Fly densities were higher in the forest (natural forest or palmgrove) than in the villages. Parous and infection rates varied according to the ecological zone. The infection rate of parous females was related to the microfilarial rate in the human population, indicating that the Chrysops populations were extremely stable in the rainy season.