Wastewater monitoring has long been used as a tool for disease surveillance, dating back to its initial use in the 1940s to monitor for polio. Recognizing its effectiveness, the U.S. Centers for Disease Control and Prevention (CDC) established the National Wastewater Surveillance System in 2020 to support monitoring for SARS-CoV-2. Now, a recent study by scientists from Penn State and the Pennsylvania Department of Health has demonstrated that wastewater surveillance can also be valuable in detecting foodborne pathogens.
In a study published in the Journal of Clinical Microbiology, researchers found Salmonella enterica bacteria in samples from two wastewater treatment plants in central Pennsylvania. Salmonella is a common cause of gastroenteritis globally, but surveillance for the disease is often inadequate. By evaluating the utility of wastewater monitoring, the researchers aimed to enhance surveillance for this foodborne pathogen.
Wastewater testing can detect traces of infectious diseases circulating in a community, even in asymptomatic individuals, providing an early warning system for potential outbreaks. While healthcare providers are required to report cases of salmonellosis, many infections go undetected. Salmonella, which is primarily transmitted through contaminated food, causes millions of infections, hospitalizations, and deaths annually in the U.S.
During the study, raw sewage samples were collected from the two treatment plants and tested for non-typhoidal Salmonella. The researchers recovered 43 Salmonella isolates, with nearly 20% belonging to a rare type called Salmonella Baildon. Genetic analysis revealed that Salmonella Baildon isolates from wastewater were indistinguishable from bacteria found in a patient associated with a salmonellosis outbreak in the same area.
This study highlights the value of sewage monitoring in supplementing traditional surveillance methods for Salmonella infections. By using whole genome sequencing, researchers were able to identify genetic links between bacteria in wastewater and patient samples. The findings suggest that wastewater monitoring could serve as an early warning system for foodborne disease outbreaks, allowing health officials to trace the source of contamination and reduce the number of affected individuals.
Looking ahead, the researchers envision a future where domestic wastewater treatment plants contribute samples for monitoring various illnesses, creating a collaborative network between public health agencies, academia, and federal entities. This proactive approach to disease surveillance could lead to quicker responses to outbreaks and ultimately improve public health outcomes.
The study, led by Nkuchia M’ikanatha and Ed Dudley, sheds light on the potential of wastewater monitoring as a valuable tool in detecting foodborne pathogens and preventing outbreaks. By leveraging sewage surveillance alongside traditional surveillance methods, healthcare providers and public health agencies can work together to identify and address infectious diseases in communities.
