Risk factors for Podoconiosis: Kamwenge District, Western Uganda, 2015

Podoconiosis, a form of non-infectious elephantiasis, is a disabling Neglected Tropical Disease. In August 2015, a non-government organization reported an increase in elephantiasis cases in Kamwenge District. We conducted an investigation to confirm the diagnosis, identify causes and risk factors, and guide control efforts. We defined a suspect case-person as a Kamwenge resident with bilateral asymmetrical swelling of lower limbs lasting ≥ 1month, plus ≥ 1 of the following: skin itching; burning sensation; plantar oedema; lymph-ooze; prominent skin markings; rigid toes; mossy papillomata. A probable case was a suspect case with negative microfilaria antigen immunological-card test results. We conducted active case-finding in affected communities. In a case-control study we compared shoe-use and feet-washing practices before disease onset among 40 probable case-persons and 75 asymptomatic village control-persons, matched by age (± 5y) and sex. We collected soil samples to characterize soil-irritant composition. Our active case-finding identified 52 suspect cases in two affected sub-counties during 1980-2015 (incidence = 2.9/100,000/year), including 40 probable cases (mean age = 47y; range: 13-80y). The annual case counts did not increase significantly over time. All case-persons had negative immunological-card test. In the case-control study, 93% (37/40) of probable case-persons and 31% (23/75) of controls-persons never wore shoes at work (OR M-H = 6.7; 95%CI = 1.7-26); 80% (32/40) of probable case-persons and 55% (39/75) of control-persons never wore shoes at home (OR M-H =4.4, 95%CI=1.5-13); 70% (27/39) of probable case-persons and 47% (34/72) of control-persons washed feet at day-end rather than immediately after work (OR = 11, 95%CI = 2.1-57). Soils samples were characterized as being rich black-red volcanic clay. The reported elephantiasis was podoconiosis, which was associated with prolonged foot exposure to volcanic soil. We recommended health education on foot protection and washing, and universal use of protective shoes.