Cholera Risk in Lusaka : A Geospatial Analysis to Inform Improved Water and Sanitation Provision

Urbanization combined with climate change are exacerbating water scarcity for an increasing number of the world's emerging cities. Water and sanitation infrastructure, which in the first place was largely built to cater only to a small subsector of developing city populations during colonial times, are increasingly coming under excessive strain. In the rapidly growing cities of the developing world, expansion does not always keep pace with population demand, leading to waterborne diseases, such as cholera (Vibrio cholerae) and typhoid (Salmonella serotype Typhi). Funding gaps therefore make targeting for efficient spending on infrastructure upgrades essential for reducing the burden of disease. This paper applies geospatial analysis in Lusaka, Zambia, in the context of the cholera outbreak of October 2017 to May 2018, to identify different water and sanitation infrastructure investment scenarios and their relative impact on reducing the risk of cholera in the city. The analysis presented uses cholera case location data and geospatial covariates, including the location of and access to networked and non-networked Water and sanitation infrastructure, groundwater vulnerability, and drainage, to generate a high-resolution map of cholera risk across the city. The analysis presents scenarios of standalone or combined investments across sewerage coverage and maintenance, on-site sanitation improvements, piped water network coverage and quality, and ensuring the safety of point source water. It identifies the investment most strongly correlated with the largest reduction in cholera risk as the provision of flush to sewer infrastructure citywide. However, it also considers the trade-offs in terms of financial cost versus health benefits and takes note of where the next highest health benefits could be achieved for a much lower cost. Finally, the analysis was done in the context of a considered restructuring of an existing World Bank investment, the Lusaka Sanitation Program. It identifies what appears to be the most efficient combined initiative as partial sanitation investment scale-up and investment in piped water in 10 priority wards where the cholera risk was highest