Wastewater Surveillance: A Novel Approach in Tracking Infectious Diseases

A Revolutionary Approach to Disease Surveillance

In the battle against infectious diseases, an unexpected ally has emerged: wastewater. The study of pathogens in sewage is aiding scientists to track outbreaks of infectious diseases and intervene before they escalate. This method, known as wastewater surveillance, has been crucial in tracking deadly pathogens like poliovirus, Vibrio cholerae, and Salmonella typhi.

In the wake of the Covid-19 pandemic, studying sewage material has become a real-time method of monitoring a wider variety of infectious diseases. This includes respiratory pathogens such as influenza, SARS-CoV-2, and RSV. The concentration of pathogens in sewage is valuable for tracking the rise or decline of diseases, providing an early warning of disease prevalence.

Wastewater Surveillance in Action: Tracking COVID-19

A study titled 'Wastewater Surveillance of SARS-CoV-2 in Minnesota' demonstrated the use of wastewater-based epidemiology to assess the prevalence of COVID-19 in a sewer service area. The researchers measured SARS-CoV-2 RNA in 44 wastewater treatment plants in Minnesota, investigating linear regression models to predict the weekly case count from SARS-CoV-2 RNA concentrations. The relationship between COVID-19 incidence and SARS-CoV-2 RNA in wastewater was found to be treatment plant-specific, indicating the potential of localized disease surveillance.

Detecting Variants of Concern

It's not just the presence of SARS-CoV-2 that can be detected in wastewater, but also its variants of concern. A study at The Ohio State University found that three such variants, Alpha, Delta, and Omicron, were detected in indoor dust samples collected from buildings on campus. The results support the hypothesis that dust can be used to track COVID-19 variants in buildings, further extending the surveillance potential of non-traditional sources.

Technological Advancements in Pathogen Detection

With the onset of the Covid-19 pandemic, researchers like Christopher Mason of Cornell University have shifted their focus to monitoring the presence of the virus in transit systems and wastewater. The pandemic has accelerated the development of new technologies for pathogen detection, such as environmental DNA surveillance and wastewater monitoring. The ultimate goal is to create an early warning system to detect and contain potential disease outbreaks before they occur, particularly in high-risk areas where humans and animals interact.

Global Monitoring Networks: A Potential Future

Major airports are intercepting and analysing waste from planes to detect dangerous new arrivals of pathogens, including Covid, polio, Ebola, and yellow fever. There are ongoing discussions about establishing a global monitoring network to track novel virus variants, and feasibility studies have been conducted in the UK. However, there are limitations to the wastewater programmes, such as dependence on toilet use and the inability to identify individual infections.

Wastewater Surveillance: A Tool for Public Health Intervention

Sewage analysis can also play a crucial role in local health interventions. In one case, a South Bay urgent care clinic detected an increase in gastrointestinal illness believed to be caused by heavy rain pushing raw sewage across the border from Tijuana. The clinic's testing showed the presence of nine different pathogens among 28 of 54 patients, with E. coli bacteria being the most commonly detected cause of gastrointestinal symptoms. This kind of local data can inform public health interventions and funding decisions.

Despite the challenges and limitations, wastewater surveillance presents an innovative approach to detect, monitor, and predict the prevalence of infectious diseases. As technology platforms continue to evolve, the efficiency and effectiveness of this method are likely to improve, making it an increasingly valuable tool in the fight against current and future pandemics.