Pollution source apportionment and wastewater-based epidemiology: implications and applications for public health

Faecal contamination of recreational waterbodies from various sources substantially threatens public health and water quality. Exposure to this contamination, through bathing or consuming contaminated water, may lead to a wide range of human health problems in addition to water related-diseases caused by waterborne pathogens. Protecting water quality is essential for human health, ecosystem preservation, and economic growth and development. The EU Bathing Water Directive (BWD) requires member states to assess bathing water quality according to the levels of faecal indicator bacteria (FIB) in designated bathing waters. Dublin Bay, which has five designated bathing waters, is a complex system that is subject to faecal contamination from numerous anthropogenic and zoogenic sources. To understand the main drivers of this contamination in Dublin Bay, my PhD research employed high-resolution sampling, microbial source tracking and microbial source apportionment strategies to characterise the primary biological sources of contamination onto two bathing waters, Sandymount and Merrion Strands, that have exhibited deteriorating water quality (Chapters 2 and 3). Chapter 4 describes some of the limitations of the EU Bathing Water Directive (BWD) and demonstrates that the hydrodynamic properties of a water system impact the fate and transport of faecal indicators. Viral faecal indicators should be included to improve the reliability of water quality modelling and minimise the risk of waterborne illnesses from faecal contamination.
Given that pathogens present in sewage-contaminated surface waters are derived from the local population through wastewater discharges, my PhD research addresses specific public health concerns regarding the potential environmental transmission of SARS-CoV-2. Chapter 5 provides insights into the persistence of infectious SARS-CoV-2 and its RNA in the aquatic environment and determines that transmission of the SARS-CoV-2 virus through contact with contaminated surface waters is unlikely. Finally, although wastewater contamination of surface waters is a serious public health threat, wastewater analysis can also be used as a tool to provide qualitative and quantitative information on the population from which it is derived. Chapter 6 examines how wastewater-based epidemiology (WBE) can be used to monitor viruses in the community and provides insights into the potential causes of the recent outbreak of severe acute hepatitis of unknown etiology (SAHUE) in young children. An increased prevalence of human adenovirus and adeno-associated virus 2 in the community was identified during the SAHUE outbreak. Next-generation sequencing was further employed to demonstrate how wastewater-based epidemiology could aid in the surveillance of other respiratory adenovirus species. This methodology will be essential for enhancing global health and improving disease surveillance by providing a non-invasive and cost-effective resource for monitoring public health.