Studies on onchocerciasis in the United Cameroon Republic. III. A four year follow-up of 6 rain-forest and 6 Sudan-savanna villages.

After an interval of four years the same observers used the same standardized techniques to re-examine 1,016 people in 12 heavily infected rain-forest and savanna villages in Cameroon. The changes in the number of nodules and in the concentration of microfilariae in the skin and eye are described. These latter changes are correlated with the development and/or deterioration of eye lesions and visual impairment. In both the rainforest and the savanna there was a strong association between the development of eye lesions and a high concentration of microfilariae, not only in the eye but also in the skin, and more so at the shoulder than at the buttock. The importance of these findings for the prevention of blindness is discussed.