Mapping cholera risk in Nairobi County, Kenya: a comprehensive analysis of environmental, socio-economic, and WASH factors

Abstract

 Background : Cholera, a globally prevalent waterborne disease, is closely monitored in Kenya as part of the Integrated Disease Surveillance and Response strategy. Understanding regional variations in cholera risk factors and trends is crucial, particularly in Sub-Saharan Africa. This study aimed to construct a risk map for cholera outbreaks in Nairobi County, based on the spatial-temporal dynamics of environmental and socio-cultural factors, Water, Sanitation, and Hygiene (WASH) conditions, and historical cases reported between 2009 and 2019.

Methodology : We retrospectively analyzed historical cholera cases in Nairobi, employing spatial analysis to map the spatiotemporal variations in factors associated with cholera outbreaks. A cross-sectional descriptive research design was adopted to investigate the relationship between WASH conditions and cholera outbreaks. Stratified random sampling selected 399 respondents from all 85 wards in Nairobi County. We employed descriptive statistics (percentages and frequencies) and inferential statistics (Chi-square) to assess variable relationships.

Results : Cholera cases are concentrated in densely populated, especially informal, settlements. Population size significantly correlated with cholera cases (p-value=0.03). Dumping sites in Nairobi emerged as potential cholera sources within residential areas, with the vicinity showing a slight association with reported cases. Rainfall patterns and humidity levels across Nairobi County also influenced cholera risk.

Conclusions : Areas within 400 meters of rivers and sewage lines faced elevated cholera risk. Most cases occurred in slum or regular residential areas. Proximity to dumping sites increased the risk of cholera outbreaks. These findings offer valuable insights for cholera prevention and control strategies in Nairobi County.