Non-filarial elephantiasis in the Mt. Elgon area (Kapchorwa District) of Uganda.

Following reports of a high frequency of elephantiasis in Kwen County (Kapchorwa District) on the slopes of Mt. Elgon in Uganda, a baseline survey for lymphatic filariasis was carried out in three villages in the affected area. Individuals aged 1 year and above were examined for chronic manifestations of lymphatic filariasis, and for specific circulating filarial antigens and microfilariae of Wuchereria bancrofti. Elephantiasis was observed in all age groups from 10 years and above. The overall prevalence was 4.5%, and the prevalence among individuals aged >/=20 years was 8.2%. Males and females were equally affected. However, there were only few cases of hydrocele (overall prevalence in males of 1.0%) and blood examinations were negative for W. bancrofti circulating antigens and microfilariae. Sampling of potential filariasis mosquito vectors revealed low densities of Anopheles gambiae s.l. and An. funestus, and none of these were infected with filarial larvae. In view of the low hydrocele to elephantiasis ratio, the absence of filarial infection in humans and mosquitoes, the high altitude (1500-2200 m above sea level) and the volcanic soil type, it is concluded that elephantiasis seen in this area is not of filarial origin but most likely is due to podoconiosis (endemic non-filarial elephantiasis).