The epidemiology of onchocerciasis in Northern Nigeria

(1) The occurrence of widespread endemic onchocerciasis causing blindness in N. Nigeria is reported. (2) The distribution of heavily, moderately and lightly infected areas is recorded. (3) The relationship between the incidence of infection, reduced vision and blindness on the one hand, and age and sex on the other, is illustrated. (4) The distribution of onchocerciasis in relationship to the Simulium vector is discussed. (5) It is estimated that about one third of a million persons suffer from the disease, of whom about 20,000 are blind. (6) The association between the endemic disease and low population density is discussed.