Public health officials can sometimes detect measles infections through wastewater testing days to months before individual cases are confirmed by doctors, according to two studies published Thursday by the Centers for Disease Control and Prevention.
The CDC’s work follows evidence that wastewater surveillance can serve as an early-warning tool for tracking disease activity, including beyond measles. Researchers involved in the studies said wastewater testing can provide signals before health care systems identify cases, potentially helping officials act sooner during outbreaks.
The studies also arrive as the CDC’s nationwide wastewater surveillance network faces uncertainty about federal support. The AP reported that under a Trump administration budget plan, the national wastewater surveillance system’s funding would be slashed from about $125 million a year to about $25 million.
Peggy Honein, director of the CDC’s division of infectious disease readiness and innovation, said the proposed funding level would “sustain some of the most critical activities” but “it would likely require some prioritization,” according to the report. The AP said the funding cut is still a proposal and that Congress had started pushing back against cuts to health care more broadly.
Despite the uncertainty in Washington, state health departments said they are planning for the possibility of reduced federal support. Honein told the AP that most state programs are entirely federally funded, the report said, adding that states have limited flexibility if national funding changes.
Colorado’s experience shows how dependent the approach can be on federal money. Allison Wheeler, manager of the Colorado’s wastewater surveillance unit, said the program started in 2020 with 68 utilities participating voluntarily, and that it later narrowed in focus even as it grew to include more diseases because it is 100% federally funded. Wheeler said the work is funded through 2029 and that the state is discussing what to do after that, the AP reported.
Wheeler also said, according to the AP, that other states have not been as fortunate as Colorado and need the funding to sustain their programs for the next year. She said Colorado’s program was able to move forward because of that support, while many states would face greater disruption if federal dollars decline.
In the Colorado study, officials began testing wastewater for measles in May as outbreaks in Texas, New Mexico and Utah were growing and five cases had been confirmed in Colorado, according to the AP report. In August, the wastewater in Mesa County tested positive about a week before two measles cases were confirmed by a doctor, the report said. Neither patient knew they had been exposed, and when officials traced 225 household and health care contacts of the first two patients, they found five more cases, the AP reported.
The Oregon study examined whether the timing of wastewater signals could help identify a developing outbreak. Researchers used preserved sewage samples from late 2024 to assess early detection during a 30-case outbreak spanning two counties. The first case was confirmed on July 11, and officials took 15 weeks to stop the outbreak, the report said.
The AP said the researchers found wastewater samples from the area were positive for measles about 10 weeks before the first cases were reported. The report also said the virus concentration in the wastewater over the weeks matched the known peak of the outbreak, suggesting the wastewater signal tracked the outbreak’s trajectory.
Dr. Melissa Sutton of the Oregon Health Authority said the wastewater results helped illuminate what she described as silent spread. She said, “We knew that we were missing cases, and I think that’s always the case in measles outbreaks,” and added that the wastewater testing “gave us an insight into how much silent transmission was occurring without us knowing about it and without our health care system knowing about it,” according to the AP.
Outside Colorado and Oregon, the AP reported that some states have already incorporated wastewater testing into their public health tracking. Utah has integrated wastewater data into public-facing measles dashboards that allow anyone to track outbreaks in real time, the report said. In New Mexico, where 100 people got measles last year and one died, wastewater testing helped officials narrow attention across a large geographic area.
The AP reported that Kelley Plymesser, of the state health department, said the system flagged cases in northwestern Sandoval County while officials were focused on a massive outbreak about 300 miles (483 kilometers) away in the southeast. Plymesser told the AP that early warning allowed health departments to alert doctors and the public, lower thresholds for testing, and refocus resources, and the outbreak ended in September. The report said New Mexico continues to use the system because measles continues to spread across the Southwest.
Sutton said she is hopeful federal leaders will recognize the system’s value. She told the AP that the widespread use of wastewater surveillance in the United States is one of the greatest advancements in communicable disease surveillance in a generation, and she cited the approach’s adaptability, affordability and reach. The AP reported that the national network covers more than 1,300 wastewater treatment sites serving 147 million people and includes six “centers for excellence,” with Colorado among them.
The AP reported that the CDC’s national system has run since 2020 and that it includes centers that innovate and support other states in expanding their testing.