Leprosy, Water, Sanitation, and Hygiene: A Case-Control Study in a Hyperendemic Area of Brazil

Viable Mycobacterium leprae has been detected in the environment and there is growing evidence that the environment may play a role in transmission. Our objective, therefore, was to further explore the association of insecure water, sanitation, and hygiene (WASH) and leprosy in a hyperendemic area of Brazil. A case-control study was conducted in eastern Minas Gerais, Brazil, between June 2016 and December 2018. Individuals with newly diagnosed leprosy and controls ages 3 years or older were enrolled. A demographic and WASH questionnaire was administered, and blood and stool collected for helminth diagnoses. Descriptive, bivariate, and multivariable analyses were conducted. Seventy-nine cases and 81 noncontact controls were recruited. The mean age was 40, and 52% were male. Most (75% [n = 120]) had piped water, 112 (71%) had a household piped sewer system, and 45 (29%) used a latrine or other type of sanitation system. Leprosy was associated with larger household sizes (adjusted odds ratio [aOR] = 1.34; 95% CI: 1.07-1.68], and, unexpectedly, with an improved household sewer system (aOR = 4.67; 95% CI: 1.51-14.45). Those with leprosy were also less likely to use piped water for drinking (aOR = 0.39; 95% CI: 0.13-1.18) or to treat their water (aOR = 0.52; 95% CI: 0.25-1.06), although these did not reach statistical significance. Although the positive association with a piped sewer system was unexpected, the findings suggest that WASH factors could be related to leprosy in this context, and further investigation into potential mechanisms for exposure is warranted.