Studies on onchocerciasis in forest-savannah mosaic areas of Nigeria. I. Investigations in Gbaragu, Oji River.

Reports on onchocerciasis in Nigeria have been scanty, despite the size of the country and of the problem. A survey of the prevalence and transmission of the disease in the south-eastern communities of Nigeria was commenced, with a year-long study of the vector and the clinical manifestations of the disease in a forest-savannah mosaic area on the Oji river. Microfilaraemia was found in 76% of the population, and nodules in 62%; there were no significant differences between male and female prevalence rates. Skin and ocular lesions of onchocerciasis, including 'Sowda', were common. Flies of the Simulium damnosum complex were found breeding along the entire length of the Oji river and tributaries. Biting occurred all the year round, but peaked in the months of March, April and May.