Sewage Samples Reveal Hidden Outbreaks (Image Credits: Foodsafetynews.com)
Pennsylvania – Researchers from Penn State University and the Pennsylvania Department of Health are expanding efforts to monitor wastewater for dangerous foodborne bacteria, aiming to sharpen public health responses to outbreaks.[1][2]
Sewage Samples Reveal Hidden Outbreaks
Scientists previously demonstrated the power of wastewater testing by linking rare bacterial strains in sewage to active salmonellosis cases. In 2022, teams isolated Salmonella enterica serovar Baildon from two central Pennsylvania treatment plants, matching it genetically to patient samples from a local outbreak.[3] Nearly 20 percent of 43 Salmonella isolates recovered that June proved to be this uncommon variant, which accounts for less than 1 percent of national cases.[3]
Separate analysis uncovered Salmonella Senftenberg in the same facilities, closely related to strains from a multistate peanut butter outbreak spanning 17 states.[4] These findings highlighted underreported infections and extended outbreak timelines beyond clinical reports. Nkuchia M’ikanatha, lead epidemiologist at the Pennsylvania Department of Health, noted that such surveillance fills gaps in traditional tracking for pathogens like non-typhoidal Salmonella.[3]
The approach dates back decades – first tested in 1929 for early Salmonella strains and scaled in the 1940s for polio – but gained renewed focus during the COVID-19 pandemic through the CDC’s National Wastewater Surveillance System.[1]
Fresh Funding Powers Broader Monitoring
The U.S. Food and Drug Administration recently awarded more than $500,000 over five years to sustain and grow this initiative, building on support provided since 2016.[1][2] Ed Dudley, professor of food science at Penn State and director of the E. coli Reference Center, leads the effort alongside M’ikanatha and doctoral candidates Jie Feng and Erika Biernbaum.
Teams now sample sewage from dozens of municipal plants statewide. In Dudley’s lab, isolates undergo whole genome sequencing to pinpoint pathogens, then cross-reference with FDA platforms like GalaxyTrakr and the NCBI Pathogen Detection database.[1] Collaborators at the health department link these results to epidemiological records, tracing community spread.
“Our hypothesis is that regular sampling, combined with epidemiologic data from the Pennsylvania Department of Health, will demonstrate that foodborne pathogens can routinely be isolated from community wastewaters during outbreaks,” Dudley stated.[1]
Zeroing In on Salmonella and Listeria
The expanded program prioritizes Salmonella enterica and Listeria monocytogenes, common culprits in foodborne illnesses that sicken thousands annually.[2] Unlike targeted food tests or individual diagnostics, sewage analysis captures signals from entire populations, including asymptomatic carriers.
Dudley emphasized its advantages: “As opposed to point-of-care diagnostics and food sampling, wastewater-based surveillance provides a broader picture of the pathogens circulating within populations living in the catchment areas of wastewater treatment plants.”[1]
- Detects outbreaks early, before widespread illness reports.
- Pinpoints affected communities for targeted interventions.
- Supports whole genome sequencing for precise strain matching.
- Enhances national databases for cross-state outbreak tracking.
- Reveals contaminated food distribution patterns.
A Game-Changer for Public Health
Results promise actionable insights, refining surveillance and response tactics. Public health agencies could deploy resources faster, curb spread, and safeguard supplies. Dudley envisions widespread adoption: “I foresee a future where many domestic wastewater treatment plants contribute untreated sewage samples for monitoring evidence of various illnesses.”[3]
Key Takeaways
- Wastewater testing linked rare Salmonella strains to real outbreaks in Pennsylvania.
- New five-year FDA grant targets Salmonella and Listeria statewide.
- Whole genome sequencing enables outbreak tracing beyond clinical cases.
This evolving tool stands to transform how officials combat foodborne threats. What role should wastewater monitoring play in your community’s health strategy? Share your thoughts in the comments.
