Onchocerciasis in field workers at Baya Farm, Teppi Coffee Plantation Project, southwestern Ethiopia: prevalence and impact on productivity.

A survey of onchocerciasis in male field workers was conducted in Baya Farm, Teppi Coffee Plantation Project, southwestern Ethiopia, in order to determine the prevalence rate of onchocerciasis in that population and to measure the effect of the disease on work productivity. A total of 196 study subjects were examined both clinically and parasitologically. Parasitological diagnosis was based on bilateral skin biopsies from the calf, buttock, and scapula. It was found that the prevalence rate of onchocerciasis (82.7%) and the intensity of infection were very high. No study subject had any detectable visual impairment, and other chronic manifestations were few. Based on a twelve month retrospective review of labour cards, workers with onchocerciasis were significantly more likely to be absent from work due to illness and other reasons, and earned significantly less wages, than workers without onchocerciasis, thus suggesting that non-blinding onchocerciasis has a negative impact on work productivity.