Sewage monitoring may provide earlier warning of pertussis outbreaks

Pertussis, or whooping cough, continues to cause periodic outbreaks worldwide and can be especially dangerous for infants who have not completed vaccination. Yet conventional surveillance depends on people seeking medical care, being tested, diagnosed, and reported, which can delay recognition of changes in community transmission.

Researchers at the University of Osaka and the Osaka Institute of Public Health have now shown that wastewater surveillance may provide an earlier signal. By monitoring sewage across Osaka Prefecture for more than two years, the team found that increases in pertussis-associated DNA appeared before increases in reported cases.

From April 2023 to July 2025, wastewater was collected weekly from four treatment plants and analyzed for DNA markers associated with Bordetella pertussis, the bacterium that causes pertussis, and Bordetella parapertussis. The concentration of the B. pertussis-associated marker IS481 began increasing in 2024 and showed a temporal pattern similar to reported pertussis cases.

In the main cross-correlation analysis, the wastewater signal preceded reported cases by 10 weeks. Other analyses showed lead times ranging from 4 to 16 weeks, consistently indicating that changes in wastewater appeared earlier.

Wastewater surveillance has an important advantage. It does not depend on whether infected people seek medical care or undergo testing. It may therefore capture broader community-level trends, including mild or asymptomatic infections that are not fully represented in clinical reports.

"By combining wastewater surveillance with clinical surveillance, we hope to detect changes in community transmission earlier," says Dr. Daisuke Motooka of the Research Institute for Microbial Diseases, the University of Osaka.

The findings suggest that wastewater monitoring could complement clinical surveillance and support earlier public health preparedness, including heightened clinical awareness, expanded testing, and infection-prevention measures. This could support a shift from a reactive to a proactive public health approach. By building a system that detects and responds to early signs of an outbreak, rather than acting only after it has begun, the researchers aim to help limit the spread of infection within communities.