Spatio-Temporal Trends of Typhoid Fever Incidence in Kibera (2007-2015)

Abstract

Background: Typhoid fever is a bloodstream infection caused by the bacterium Salmonella typhi and transmitted either person-to-person through direct fecal-oral transmission or via environmental factors. Methods: We utilized household and clinical data from an infectious disease surveillance system in Kibera, from 2007-2015 to assess spatial and temporal patterns of typhoid fever risk in two age groups (children under 10 years of age and individuals 10 and older). We calculated incidence rate differences (IRDs) within clusters before and after a major Water, Sanitation, and Hygiene (WASH) intervention and utilized regression methods to compare risk between clusters in two age groups. Results: All clusters had declines in typhoid incidence following the WASH implementation, most with statistically significant declines. While we found that the risk between clusters was not significantly different in children under 10 years of age, we identified one cluster that exhibited elevation in risk compared to the reference in individuals 10 years of age and older (IRR = 2.80, p-value = 0.02). Conclusion: Residual risk of typhoid fever following the WASH intervention suggests that other environmental risk factors may play an important role in these areas.