Infectious Risk Assessment with Exposure to Pathogens in Floodwater—A Case Study of Manila’s Vulnerability to Climate Change

Abstract

Waterborne diseases are caused by pathogenic microorganisms that are directly transmitted when contaminated water is consumed or contacted. In the flood season, there is a higher risk of infection due to more frequent direct contact with severely polluted water over a longer period. In this chapter, we aim to characterize and quantify the human health risks associated with varying levels of exposure to pathogens present in flood water. In our analysis, exposure scenarios according to inundation levels are developed in which direct and indirect contact with polluted water is assumed to occur. The risk of gastrointestinal illness due to Escherichia coli via incidental ingestion of flood water in the City of Manila over the course of a year varies according to inundation level and age. The risk level ranges from 1 % to nearly 20 % in flood levels of l m or less to over 2 m. The highest level of risk is to the 5- to 14-year age group. However, if flood heights of more than 2 m become the norm due to climate change, and these floods occur more frequently and last longer, then the vulnerability baseline for all groups will shift accordingly. To verify the health risk estimation, data need to be collected for group behavior during floods and for the quality of the inundation water. Our purpose was to quantify climate change–related risks. In the case of illnesses caused by flooding, this quantification can be employed to make a rapid assessment of threatened areas where data, time, and resources are lacking.