Risk of Exposure to Fecal Contamination in 10 Neighborhoods Across Dhaka, Bangladesh
CL Moe, J Green, S Raj, Y Wang, N Amin, S Ali, M Rahman, I Hasan, Z Hasan, S Haque, G Joseph American Society of Tropical Medicine and Hygiene Conference (October 2018)
Dhaka, Bangladesh has experienced rapid population growth and challenges meeting sanitation service demands. Poor sanitation and fecal sludge management can lead to fecal contamination in the urban environment. To understand risk of exposure to fecal contamination, an assessment of 10 environmental pathways was conducted using the SaniPath Tool. Data were collected from 10 neighborhoods (6 low-income, 2 mixed-income, and 2 high-income) throughout Dhaka between April-June 2017. 1000 environmental samples were collected from shared latrines, public play areas, produce in markets, street food, open drains, flood waters, surface waters, bathing water, municipal water, and non-municipal water. Samples were analyzed using IDEXX-Colilert-24® Quanti-Tray/2000 to determine most probable number (MPN) of E. coli. Behavior surveys were conducted with households, school children, and community groups to understand interaction with the environment. Using Bayesian methods, the behavioral and microbiological data were used to estimate the percentage of the population exposed and mean dose of fecal exposure (E. coli) for each environmental pathway in each neighbourhood. For adults, consumption of raw produce was the dominant exposure pathway (i.e. makes greatest contribution to total exposure) in 6 of the 10 neighborhoods. The percentage of adults exposed to fecal contamination through ingestion of raw produce ranged from 78-99% and the mean dose ranged from 104.8 to 107.5 MPN of E. coli ingested/month. The most common dominant pathway of exposure amongst children (8/10 neighborhoods) was accidental ingestion of drain water from playing in, or passing through, open drains (up to 94% exposed; mean dose of 107.8 MPN of E. coli ingested/month). Ingestion of fecal contamination via produce and street food was a high risk throughout Dhaka, while exposure to fecal contamination via municipal drinking water was mainly greater risk for those living in the south of the city. These results can guide city-wide WASH programming to prioritize interventions aimed at dominant exposure pathways and increase the potential for public health impact.
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