TORonTO — In a presentation at IAFP’s 2023 Annual Meeting, Kali Kniel, Ph.D., from the University of Delaware Department of Animal and Food Sciences, shed light on the importance of wastewater analysis in tackling the detection challenges posed by foodborne viruses and parasites.

Throughout history, wastewater analysis has played a crucial role in monitoring and detecting various pathogens. In the 1940s, cell-culture methods were employed to track viral pathogens such as polio in sewage. In the 1980s, DNA probes were adapted for the detection of hepatitis A virus (HAV). The incorporation of PCR detection into sewage surveillance in the 1990s further enhanced detection capabilities. Notably, in 2013, sewage surveillance successfully provided early warnings for HAV and norovirus outbreaks in Sweden and prevented a potential paralytic polio outbreak in Israel.

Wastewater-based epidemiology (WBE) has also proven effective in detecting the SARS-CoV-2 virus at a local level. This method has allowed scientists to gain valuable insights into the movement of the virus through populations, filling the gaps left by clinical diagnoses that often miss unreported cases.

One significant benefit of WBE and surveillance is its potential to detect specific viruses and parasites. For instance, wastewater analysis at the KTH Royal Institute of Technology in Stockholm detected Adenovirus 41, known for causing outbreaks of gastroenteritis in children. Recent outbreaks in the United States also suggested a potential link between Adenovirus 41 and liver inflammation. Several children in Alabama, displaying hepatitis symptoms, tested negative for hepatitis but positive for Adenovirus 41. This connection prompted the U.S. Centers for Disease Control and Prevention (CDC) to investigate further.

Kniel emphasized the need for standardized reporting and the use of indicators and biomarkers to calibrate concentrations obtained from wastewater monitoring for epidemiological models.

Various detection methods were discussed during the presentation. Digital PCR, for example, enables the absolute quantification of genomic targets, offering advantages such as a lower limit of detection and not requiring standard curves or CT (cycle threshold) values. However, the current cost of digital PCR is relatively high.

To illustrate the effectiveness of wastewater analysis, a case study comparing indicators in a town and hospital’s influent, water flowing in, was presented. The town demonstrated different indicator concentrations due to various factors, including precipitation.

Hospitals were identified as crucial sites for pathogen detection, as they can serve as sentinels for environmental contamination. Understanding the processes involved in wastewater treatment and the discharge of treated water into the environment is vital for effective surveillance, Kniel said.