Risk of Diarrhoea from Multiple Water Sources Used in Households

摘要

Piped water is intermittently supplied (3-4hours/week) in the Kathmandu valley. Therefore, local residents depend also on varieties of alternative water sources. Groundwater, one of the major alternative water sources in the valley, was polluted with faecal coliform bacteria. Incident of diarrhoea among under 5 years was 50% in Nepal. In addition, Gorkha earthquake occurred in April 2015. This study aimed to estimate the annual infection risk from enteropathogenic Escherichia coli in the Kathmandu Valley and confirm the impact of the earthquake on the risk. The risk was calculated based on the water supply areas. Water ingestion was determined for each water source from the questionnaire collected from over 1000 households during dry seasons of 2015 and 2016. A set of probability distribution of microbial concentrations in each water source was also determined from the measurement of water samples collected in the valley. The estimated risk from drinking was significantly higher than that from bathing. Comparison of the risks among areas indicated the possibility of regional disparity. The impacts of the earthquake were also examined; the number of household drinking only safe water increased and the estimated risk significantly decreased after the earthquake in the correspondent areas.