Water, Sanitation, and Cholera in Sub-Saharan Africa

Improvements in waterand sanitation should reduce cholera riskthough the associations between cholera and specific water and sanitationaccess measures remain unclear. We estimated the association betweeneight water and sanitation measures and annual cholera incidence accessacross sub-Saharan Africa (2010-2016) for data aggregated atthe country and district levels. We fit random forest regression andclassification models to understand how well these measures combinedmight be able to predict cholera incidence rates and identify highcholera incidence areas. Across spatial scales, piped or "otherimproved" water access was inversely associated with choleraincidence. Access to piped water, septic or sewer sanitation, andseptic, sewer, or "other improved" sanitation were associatedwith decreased district-level cholera incidence. The classificationmodel had moderate performance in identifying high cholera incidenceareas (cross-validated-AUC 0.81, 95% CI 0.78-0.83) with highnegative predictive values (93-100%) indicating the utilityof water and sanitation measures for screening out areas that areunlikely to be at high cholera risk. While comprehensive cholera riskassessments must incorporate other data sources (e.g., historicalincidence), our results suggest that water and sanitation measurescould alone be useful in narrowing the geographic focus for detailedrisk assessments. Wequantified the relationship between high-resolution estimatesof water and sanitation access and cholera incidence and assessedthe utility of water and sanitation measures in identifying high-riskgeographic areas in sub-Saharan Africa.