Study on the distribution of onchocerciasis and loiasis in West Province, Cameroon

A clinical and parasitological survey of onchocerciasis and loiasis has been carried out in 38 communities in the West Province of Cameroon prior to the implementation of a mass ivermectin treatment. The highest endemicity levels of onchocerciasis were recorded in the villages located at an altitude below 1 400 m, and whose inhabitants go down to the valleys for agricultural activities. Conversely, low endemicity levels were recorded in the most populated part of the study area, which is located at an altitude above 1 400 m; in the latter communities, the residents cultivate the high ground not far from their houses and are thus less exposed to transmission of onchocerciasis. Despite relatively low microfilarial loads, the prevalences of nodules were fairly high; this demonstrates that in some epidemiological situations the latter indicator gives an erroneous indication of the intensity of infection in the population. The prevalence of loiasis is very low in most of the villages of the study area.