Gender and ethnic differences in onchocercal skin disease in Oyo State, Nigeria

To obtain baseline data for a study of the effects of ivermectin treatment on onchocercal skin disease 1032 adults 20-70 years of age from the Ifelouju local government area of Oyo State Nigeria were examined for skin lesions and palpable nodules. 52.7% of those examined were men; 87.3% were Yoruban and 11.0% were Fulani. 48.7% had at least 1 reactive skin lesion primarily lichenified onchodermatitis (29.0%) depigmentation (27.2%) chronic papular onchodermatitis (21.6%) and acute papular onchodermatitis (15.5%). Palpable nodules were present in 61.8%. 37.5% complained of itching. In all age groups women had a significantly higher prevalence of these lesions than men. In addition the prevalence of reactive skin lesions was significantly higher among the Fulani than the Yoruba. Since the Fulani are less likely to receive childhood immunization services and guinea worm disease control interventions than the Yoruban majority steps must be taken to ensure ivermectin distribution reaches this ethnic group. These results indicate a need for further research to identify the behavioral and/or immunologic factors that produce differences in onchocercal skin disease by gender and ethnic group. Of more immediate concern however is the need to ensure that women and ethnic minorities receive equitable disease control services.