Farm land size and onchocerciasis status of peasant farmers in south-western Nigeria.

Concern is being raised about the economic impact of the non-blinding strain of onchocerciasis, since half of those affected with onchocerciasis in Africa live in the forest zones where the non-blinding form is prevalent. WHO's TDR programme has embarked on multi-country studies on the social and economic effects of onchocercal skin disease (OSD). Baseline data from one site, the Ibarapa Local Government Area of Oyo State, Nigeria, is presented here. Farmers were screened for signs and symptoms of onchocerciasis including palpable nodules, reactive skin lesions and self-reported severe itching. Those having two or more of these conditions were classified as having severe OSD. A matching group of farmers without any of the signs or symptoms formed a control group. Women in the area either did not farm or held only one small plot. Land size comparisons were undertaken with 51 pairs of male farmers matched for age and location within 23 small hamlets bordering the Ogun River. Farmers with OSD had significantly less farmland under cultivation (9117 m2) than those with no OSD (13850 m2). The farmers with OSD did not appear to have alternative income strategies to compensate and, consequently, they had a lower value of personal wealth indicators (e.g. iron sheet roofing, motorcycle) than those without OSD. One can conclude that although the effect of forest strain onchocerciasis is less dramatic than of the blinding from, the disease poses an important economic threat in the region.