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

ABSTRACT

Introduction: 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. Methods: 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. Results: 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 (ORM-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 (ORM-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. Conclusion: 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