[Epidemiological status of onchocerciasis in the Congo]

Analysis of 25 surveys carried out in the Congo between 1978 and 1987 (covering nine of the ten administrative regions), during which 6,215 subjects were examined, showed that onchocerciasis is endemic in the southern part of the country. Two main foci meeting at the southern exit of Brazzaville (Pool region) were identified. One focus in the Djoué basin. The other is the zone along the Congo river stretching from below Brazzaville south west to the Zaire border. Two secondary foci were noted, one in the region of the Bouenza and the other west of the Mayombe mountains. Surveys carried out in the north of the country and in the west did not reveal any onchocerciasis. However, certain areas of primary forest in these regions were found to be endemic for Mansonella streptocerca. Simulium damnosum s.l. in the sole vector of onchocerciasis. In both the Pool foci, and in the Mayombe focus, prevalences assessed from microfilarial and cyst counts were high but the mean microfilarial densities were relatively low. In certain villages over 90% of the population aged over 14 years may present with microfilariae and nearly 70% may present cysts.