Spatio-temporal pattern and risk factors associated with cholera outbreaks in selected high-risk areas of Kenya.

Background: Cholera is a public health challenge in Kenya. This study aimed at identifying the spatio-temporal pattern of cholera and its associated risk factors in high-risk areas to optimize resource use for targeted control.

Methods: The study was conducted in Mukuru, an informal settlement, Dadaab refugee camp and counties bordering Lake Victoria. Cholera line list data from 32 subcounties (2013-2022) was sourced from Kenya's Ministry of Health. Population and water, sanitation and hygiene data came from the 2019 census. Space-time scan statistic (SaTScan) were used to carry out spatio-temporal analysis and a zero-inflated negative binomial regression model evaluated cholera risk factors.

Results: A total of 7316 cholera cases were reported across 22 (69%) subcounties, the highest numbers in 2015, 2016 and 2022 affecting 21, 12 and 3 subcounties, respectively, and none in 2014. Five high-risk space-time clusters encompassing 15 subcounties were identified, with Dadaab and Fafi showing persistent outbreaks. Improved sanitation was the only variable that suggested significant protective effects to cholera control (relative risk 0.9445, p=0.001).

Conclusions: Dadaab and Fafi subcounties were extremely high-risk and improved sanitation significantly reduced cholera outbreaks. These data inform cholera intervention policies in vulnerable regions.