Wastewater-based Epidemiology in Wales: From COVID-19 to One Health Monitoring

Background Wastewater-based epidemiology (WBE) offers real-time public health insights by detecting pathogens, chemicals, and pharmaceuticals in communities. The 'One Health' principle acknowledges that human, animal, and environmental health are interconnected. WBE plays a crucial role in One Health by monitoring contaminants from all these sources. For infectious diseases, WBE can signal outbreaks before clinical symptoms arise, enabling swift action that benefits both humans and animals. It also tracks antimicrobial resistance genes, informing policy makers, veterinarians and medical professionals about resistance spread. By identifying environmental pollutants, WBE aids in environmental health oversight, identifying issues affecting both wildlife and humans. During the COVID-19 pandemic, the Welsh National Wastewater Monitoring Program was launched to trace disease spread. It offered an early warning system, detecting outbreaks before clinical signs appeared. Post-pandemic, its scope widened to cover markers of One Health, aiming to monitor other diseases, antimicrobial resistance, and other contaminants. The program, a collaborative effort involving Bangor and Cardiff Universities, Welsh water companies, Public Health Wales, The London Data Company & Arup, aimed to inform Welsh policy and benefit its citizens. Methods The Welsh National Wastewater Monitoring program sampled 47 wastewater-treatment works (WWtW) across the country, capturing approximately 75-80% of the national population (Figure 1). Sites were chosen based on their geographical coverage and population density, enabling a coherent and systematic approach to decision making at a local and national level. Sampling was facilitated through access and arrangements with the local water utilities, Welsh Water and Hafren Dyfrdwy. The sites were sampled 5 days per week over two years, since March 2020, with 24-hour composite samples collected and transported under refrigeration to the North Wales central processing laboratory, where they were evaluated. The wastewater samples were and processed, with the liquid fraction taken and assessed for the presence of SARS-CoV-2, Human Norovirus, Human Respiratory Syncytial Virus (RSV) and Polio. The solid fraction of the sample was then tested for the presence of antimicrobial resistance genes which were analysed by partners at Cardiff University. Results & Discussion This study over two years provided both operational guidance to the Welsh Government In real-time, the program advanced WBE research for One Health applications by analyzing wastewater for infectious diseases and AMR. This validated data reliability by correlating with sources like the UK's ONS COVID-19 Infection Survey (CIS). Fluctuations in COVID-19 were linked to lockdowns, national events, and holidays. COVID-19 data collected using WBE as validated against the CIS. This was widely considered a highly reliable source of COVID-19 infection prevalence data, individually sampling approximately 1% of the population for each data point. The wastewater data was observed to follow a similar correlative pattern to the CIS and was continued beyond the survey. This was the longest reported study used to detect COVID-19 variants using metagenomics from wastewater samples at a population level. It highlighted the prevalence of different strains and the rise of the Omicron variant BA.21 (Figure 3). It further identified the variability in variant detection with time and demonstrated how multiple variants were always circulating in the population. As the wastewater sequencing reported a week ahead of clinical sequenced cases, policymakers were provided an early indication of potential variants of concern (VOCs). Gaps in the data were generally associated with reduced reliability of the data due to insufficient viral detection in the samples, these were often attributed to periods with low viral circulation within the community such as the summer period. Beyond COVID-19 the potential for WBE extends to monitoring for other infectious diseases, both of humans and animals. Furthermore, with the infrastructure provided by the labs, sampling different sites by environmental monitoring provides the opportunity for a holistic approach to health. This was demonstrated in Wales, by monitoring different infectious diseases in the population in addition to AMR, which was a challenge faced by both human and animal populations in the country. Studying the prevalence of other infectious diseases in wastewater confirms this approach could be expanded to measure other health threats. The program studied the prevalence of NoVGI, NoVGII as human noroviruses, enterovirus-1 as a marker for Polio, influenza-A as a marker for the common flu and RSV prevalence in the population (Figure 4). Conclusions The water industry as strategic leaders on this idea can enable and support the data driven approach of harnessing WBE as a proactive means to monitor, predict, and respond to heath threats in our interconnected world. Applying the lessons learned in Wales, enables global monitoring of multiple One Health markers. This data supports the notion that WBE turns sewage into solutions, enabling us to harnessing wastewater as a valuable stream of data can help improve the health of livestock, communities, and ecosystems. When scaled across different catchments, countries and communities.