Prevalence of onchocercal skin disease and infection among workers of coffee plantation farms in Teppi,southwestern Ethiopia

In June 1996, a study on the economic impacts of onchocercal skin disease was initiated in southwestern Ethiopia. We made parasitological and clinicoepidemiological investigations among 1619 workers of a coffee plantation firm in Teppi, south-western Ethiopia. Sixty percent of the workers were included in the study. The prevalence of onchocercal skin disease (OSD) was 85.3%. Severe OSD (SOSD) was found in 17.3% of the study subjects. This was 1/5 of all OSD cases. The overall nodule carrier rate was 44.2%, which differed significantly by age classes from a rate of 12.3% to 73.0%. This rate varied by sex, 51.7% in males and 22.6% in females. Microfilarial carrier rate (MFCR) was 77.6%. This rate did not vary neither with severity of disease nor with presence or absence of pruritus or onchodermatitis. Mean microfilarial count was determined to be 38.1 per mg of skin snip or 44.4 per mg of infected skin snips. The geometric mean of microfilarial load per infected skin was 23.8. The community microfilarial load (CMFL) was estimated to be 14.0 per mg skin snip. The study showed that SOSD is prevalent in Teppi and affects a substantial number of the working population. An intervention program is called for.