Epidemiologic study of arboviruses in the Arba-Minch district of Ethiopia.

A yellow fever outbreak occurred in 1966 in Arba-Minch District, east of Abaya Lake, in Ethiopia. The present study was undertaken to assess the southern limits of that epidemic and to contribute to the inventory of arboviruses and potential vectors in that area. In the highlands 90 sera were collected, in the lowlands 140. With regard to Group B the sera reacted only with yellow fever, Wesselsbron and Spondweni antigens. In the highlands 17.8%, in the lowlands 22.2%, were positive for group B. In two sera only the titers against yellow fever were high. The absence of reactivity to West Nile virus was striking. A wide variety of Culicidae was present and differentiated. Potential or proven vectors were collected. At the time of the survey yellow fever was not active in the region. Because of an only partly immune human population, and of the presence of non-immune monkeys and some potential vectors, the area should, however, be considered to be receptive.