Study of the area affected by onchocerciasis in Brazil: survey of local residents.

An epidemiologic survey encompassing most of Brazil's Federal Territory of Roraima and the northern tip of Amazonas State has been carried out in an effort to define the boundaries and the epidemiologic characteristics of onchocerciasis in Brazil. This article describes results relating to human infections--including discovery of a new focus at Auaris in northern Roraima and analysis of data from tests conducted there and at various other locations. These findings lead the authors to conclude that the three known Brazilian foci represent independent influxes of the disease from neighboring Venezuela, that groups of both Yanomama and Makiritare Indians have been infected, and that various factors (including proximity of these foci and the route for Brazil's Northern Perimeter Highway) indicate the disease could pose a potential danger for other areas of Brazil.