Endemic elephantiasis of the lower legs in Rwanda and Burundi.

The distribution of non-filarial elephantiasis of the lower legs in Rwanda and Burundi in Central Africa has been studied in order to test the previous observation of an association between the disease and the volcanic rocks and soils on which the people live. Using the method of market counts, a total of 26,602 adults were observed in 23 markets; 189 had elephantiasis. In addition, 264 cases were observed in specially arranged clinics and a further 77 while travelling. Prevalence per thousand adults varied from 0.0 to 20.7. It was noted that the areas of high prevalence corresponded with the areas of volcanic lava. A differential market count at the edge of the red soils in two of these areas showed a raised prevalence among people living on these soils, similar to that observed in Ethiopia. The observations confirm that the disease occurs in barefooted people who dig in soil developed from volcanic rocks, under tropical conditions, at altitudes around 1500 m. It is suggested that the high proportion of iron and other transitional metals may be important as irritant or toxic to the lymphatic vessels of the legs after absorption.