Assessing health risks and disease burden from waterborne pathogens across multiple urban exposure pathways

ABSTRACT Urbanization is rapidly reshaping global demographics, placing immense pressure on sanitation infrastructure and increasing microbial contamination through multiple exposure pathways. Inadequate sanitation drives fecal–oral infections, significantly contributing to the disease burden; however, comprehensive evaluations of urban sanitation interventions remain scarce. This study addresses this gap by applying a quantitative microbial risk assessment (QMRA) to estimate gastrointestinal illness incidence in a low-income area in Dhaka facing severe sanitation challenges. The QMRA, based on measured concentrations of Vibrio cholerae, norovirus Genogroup-II, and Giardia in surface water, open drains, and flood water, revealed higher infection risks for children, who are more vulnerable due to low immunity. The analysis estimated 16,276 disease episodes annually among 4,792 individuals, resulting in a burden of 2,441.4 disability-adjusted life years. Surface water contributed the most (37%), followed by open drains (34%) and flood water (29%). Giardiasis accounted for 53.3% of the burden, cholera for 33%, and norovirus gastroenteritis for 13%. This study integrates the QMRA across multiple pathways – unlike previous studies that focused on single pathways – providing insights for improving public health in urban settings. It emphasizes the need for targeted interventions to mitigate disease burdens from wastewater exposure, with methods and findings applicable to similar urban contexts worldwide.