Faecal exposure in cholera hotspots: Sanipath exposure assessment in informal settlements of Nairobi, Kenya.

Urban informal settlements are characterized by poor sanitation infrastructure, and inadequate hygiene practices, exposing residents to infectious pathogens. We conducted a study involving environmental sampling and behaviour surveys using SaniPath Exposure Assessment tool to evaluate human exposure to faecal contamination in Mukuru informal settlements, Nairobi. Environmental sampling was conducted monthly in two neighbourhoods (Mukuru Kwa Njenga and Mukuru Kwa Reuben). We analysed 9 pathways, including open drains, produce, drinking water, surface water, floodwater, public latrine surfaces, soil, shaved ice, and street food. More than 75 % of the surveyed population reported consuming street food at least once or more per week. Of the 803 environmental samples analysed for E. coli contamination, 432 (53.8 %) were positive for E. coli. All the surface water samples (29/29) had faecal contamination, and >98 % (90/91) of open drains were positive for E. coli. In both neighbourhoods, high E. coli concentrations (4.60-9.30 log10 E. coli CFU/100 mL) were detected in open drain water, flood water and surface water. Produce was the dominant pathway of exposure to faecal contamination for adults. However, among children, produce was the dominant pathway in Mukuru Kwa Reuben neighbourhood while four pathways, including produce, contributed substantially to the total faecal exposure in the Mukuru Kwa Njenga neighbourhood. The presence of E. coli in environmental samples suggests widespread faecal contamination in the environment, which may be a major driver for diarrhoeal diseases. Our findings could be used to inform the development of effective water, hygiene, and sanitation infrastructure in urban informal settlements.