Evidence for the exacerbation of lymphedema of geochemical origin, podoconiosis, by onchocerciasis.

The study was conducted to investigate a variation in the distribution of endemic elephantiasis previously determined to be of geochemical origin in three neighbouring and essentially homogenous villages, Bambili, Bambui and Finge of the Bambui Health District of NW Cameroon. A total of 301 subjects were examined for onchocerciasis and lymphatic filariasis in the area using standard procedures. The onchocercal microfilarial prevalence varied from 6.5% in Bambili through 20.4% in Bambui to 60.4% in Finge. The onchocercal serological prevalence based on IgG4 detection followed a similar trend. By contrast, blood microfilariae were absent in the area as verified by use of sensitive techniques. The community prevalence of elephantiasis varied from 1.1% in Bambili to 4.4% in Bambui and 10.4% in Finge. The correlation between the parasitological prevalence of onchocerciasis and the prevalence of lymphedema in the three villages was strong (r=0.99, p<0.05). We confirm that the elephantiasis in the area is of geochemical origin and the results suggest that it is being exacerbated by onchocercal lymphadenitis.