Summary research: Assessing microbial health risks related to floodwater is a complex undertaking, hindered by factors like the intricate nature of the microorganisms involved and the susceptibility of those exposed to them. This research contributes a framework and application that combines health risk assessment, disease burden calculation, and hydrodynamic modeling to estimate adverse health consequences of microbial pathogens in floodwater through traffic activities which is a common factor of exposure during floods. The case study is Ninh Kieu District (Can Tho City, Vietnam) located on the western side of Hau River, a Mekong tributary. The study focuses on the health risk and disease burden due to rotavirus A in floodwater in Ninh Kieu through traffic activities, especially for motorcyclist. This research is one of the first to consider the input parameter concentrations and the number of exposed people to reduce the health impact of flood risk. It reveals that mitigation measures should not only focus on reducing urban floods but also on raising awareness of the local people of microbial health risks in floodwater. The disease burden is considered the prime variable of the health indicator to represent the social dimension in the assessment of flood vulnerability.@en

Microbial pathogens in urban floodwaters pose risks to human health, potentially causing diseases such as diarrhea. However, the disease burden related to urban traffic exposure from citizens passing through floodwaters is not easily quantified and therefore not included in many studies. Notably, this problem has received little attention in low-to-middle-income countries, with frequent flood events and the heavy diarrheal disease burden. This article calculates the infection risks and disease burden, considering traffic associated with exposure to floodwater contaminated with rotavirus for the first time in Ninh Kieu District, Can Tho city. Can Tho city in the Vietnamese Mekong Delta is well known to have many flood events every year, with many diarrheal cases during the flood season. The methodology comprises two steps. First, we applied quantitative microbial risk assessment that proposes the inclusion of exposure to traffic due to rotavirus in floodwater. Second, the disease burden was expressed in disability-adjusted life years (DALYs). The exposed groups are child pedestrians, adult pedestrians, motorcyclists, and cyclists. We used video footage to monitor the traffic. The results show that total DALYs per flood event were 1.35 × 10⁴ for 63,390 exposed people (i.e., 2129 DALYs per 10,000 cases). Motorcyclists are the strongest contributors to the DALYs (95%), followed by cyclists (2.8%), adult pedestrians (2%), and child pedestrians (0.2%). The population in Ninh Kieu District may suffer from waterborne diseases through traffic activities during flooding times. Our approach can be applied in other areas worldwide and helps identify main risk groups and focus areas for interventions.

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