Wastewater DNA Detects Pertussis Outbreaks Weeks Before Clinical Cases Emerge

Pertussis, the bacterial infection known as whooping cough, has long been a threat to communities worldwide, particularly to infants too young to have completed their vaccination series. The disease moves through populations in waves, but public health officials have always faced the same structural problem: they learn about outbreaks only after people get sick enough to seek medical care, get tested, receive a diagnosis, and have that diagnosis reported through official channels. By then, weeks have passed. By then, the virus has already spread.

Researchers at the University of Osaka and the Osaka Institute of Public Health have now demonstrated a way to see the outbreak coming before it arrives. By analyzing wastewater across Osaka Prefecture over more than two years, they found that genetic markers associated with pertussis appeared in the sewage weeks before any cases showed up in hospitals or clinics. The signal was consistent and measurable. It was also early enough to matter.

From April 2023 through July 2025, the team collected wastewater samples weekly from four treatment plants across the prefecture. They tested each sample for DNA sequences associated with Bordetella pertussis and Bordetella parapertussis, the bacteria responsible for pertussis infection. The specific marker they tracked, called IS481, began rising in concentration during 2024. When they plotted this wastewater signal against the timeline of reported pertussis cases in the community, a clear pattern emerged: the sewage was telling the story first.

In their primary analysis, the wastewater signal led reported cases by approximately ten weeks. When the researchers ran additional statistical models, they found lead times ranging from four to sixteen weeks. Across every analysis, the same finding held: changes in the bacterial DNA in the sewage preceded changes in the official case count. The wastewater was a canary in the mine, and it was singing before anyone else heard the danger.

The advantage of this approach cuts to the heart of why traditional surveillance often fails to catch outbreaks early. Clinical reporting depends entirely on a chain of events: a person must feel ill enough to go to a doctor, that doctor must think to test for pertussis, the test must come back positive, and that result must be reported to public health authorities. Many infections never make it through that chain. People with mild symptoms may not seek care. Some infected people show no symptoms at all. Wastewater surveillance bypasses all of this. It simply measures what is actually in the community's sewage, regardless of whether the infected person ever walked into a clinic.

Dr. Daisuke Motooka of the Research Institute for Microbial Diseases at the University of Osaka framed the potential plainly: by layering wastewater surveillance on top of clinical surveillance, public health systems could detect shifts in community transmission much earlier than current methods allow. That early detection window opens possibilities that reactive systems cannot access. With weeks of advance warning, health departments could heighten clinical awareness among physicians, expand testing capacity before the surge arrives, and implement infection-prevention measures while there is still time to slow transmission.

The research points toward a fundamental shift in how public health responds to disease. Rather than waiting for outbreaks to announce themselves through rising case counts, systems could begin preparing the moment wastewater signals suggest an outbreak is building. This is the difference between reacting to a crisis and preparing for one. For a disease like pertussis, which can be severe or fatal in unvaccinated infants, that difference in timing could mean the difference between a contained cluster and a widespread outbreak. The sewage, it turns out, has been trying to tell us what is coming. We are only now learning to listen.