Water, Sanitation, and Cholera in Sub-Saharan Africa

Improvements in water and sanitation should reduce cholera risk. But it is unclear which water and sanitation access are associated with cholera risk. We estimated the association between eight water and sanitation measures and annual cholera incidence access across sub-Saharan Africa (2010-2016) for data aggregated at the country and district-level. We fit random forest regression and classification models to understand how well these measures combined might be able to predict cholera incidence rates and identify high cholera incidence areas. Across spatial scales, piped or "other improved" water access was inversely associated with cholera incidence. Access to piped water, piped sanitation, and piped or "other improved" sanitation were associated with decreased district-level cholera incidence. The classification model had moderate skill in identifying high cholera incidence areas (cross-validated-AUC 0.81 95%CI 0.78-0.83) with high negative predictive values (92.5-100.0%) indicating the utility of water and sanitation measures for screening out areas that are unlikely to be cholera hotspots. While comprehensive cholera risk assessments must incorporate other data sources (e.g., historical incidence), our results suggest that water and sanitation measures could alone be useful in narrowing the geographic focus for detailed risk assessments.