Wastewater testing can alert public health officials to measles infections days to months before cases are confirmed by doctors, researchers said in two studies published Thursday by the Centers for Disease Control and Prevention.

Colorado health officials were able to get ahead of the highly contagious virus by tracking its presence in sewer systems, researchers wrote. And Oregon researchers found wastewater could have warned them of an outbreak more than two months before the first person tested positive.

The findings add to evidence that wastewater testing is a valuable weapon in tracking disease, including COVID-19, polio, mpox and bird flu.

But the national wastewater surveillance system, run by CDC since 2020, is newly at risk, under a Trump administration budget plan would slash its funding 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.”

The national system covers more than 1,300 wastewater treatment sites serving 147 million people. It includes six “centers for excellence” — Colorado among them — that innovate and support other states in expanding their testing.

States brace for cuts

The funding cut is still a proposal, and Congress has started pushing back against cuts to health care in general.

But state health departments say they are preparing for a potential loss of federal support regardless. Most state programs are entirely federally funded, Honein said.

Colorado started its wastewater surveillance program in 2020 with 68 utilities participating voluntarily. The program has since narrowed in its focus even as it grew to include more diseases, because it is 100% federally funded, said Allison Wheeler, manager of the Colorado’s wastewater surveillance unit.

The work is funded through 2029, Wheeler said, and the department is talking to state leaders about what to do after that.

“I know that there are other states that haven’t been as fortunate as us,” Wheeler said. “They need this funding in order to sustain their program for the next year.”

Measles found in wastewater before patients are diagnosed

In the Colorado study, which Wheeler co-authored, officials started testing wastewater for measles in May, as outbreaks in Texas, New Mexico and Utah were growing and five cases had been confirmed in Colorado.

In August, wastewater in Mesa County tested positive about a week before two measles cases were confirmed by a doctor. Neither patient knew that they had been exposed to measles. As they traced 225 household and health care contacts of the first two patients, health officials found five more cases.

In Oregon, researchers used preserved sewage samples from late 2024 to determine if sewage testing could have discovered a burgeoning outbreak.

The 30-case outbreak spanned two counties and hit a close-knit community that does not readily seek health care, the study's authors wrote. The first case was confirmed on July 11 and it ultimately took health officials 15 weeks to stop the outbreak.

The researchers found that wastewater samples from the area were positive for measles about 10 weeks before the first cases were reported. The virus concentration in the wastewater over the weeks also matched the known peak of the outbreak.

“We knew that we were missing cases, and I think that's always the case in measles outbreaks,” said Dr. Melissa Sutton, of the Oregon Health Authority. “But this 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.”

State see value in sewage tracking

Other states, such as Utah, have integrated wastewater data into their public-facing measles dashboards, allowing anyone to track outbreaks in real time.

And in New Mexico, where 100 people got measles last year and one died, the testing helped state health officials shrink a vast rural expanse. The state's system flagged cases in northwestern Sandoval County while officials were focused on a massive outbreak 300 miles (483 kilometers) away in the southeast, said Kelley Plymesser, of the state health department.

The early warning allowed the department to alert doctors and the public, lower thresholds for testing and refocus their resources. The outbreak ended in September. But because measles continues to spread across the Southwest, the state is still using the system to look for new cases.

Sutton, of Oregon, said she's hopeful federal leaders will see the power of the system, its adaptability, affordability and reach.

“The widespread use of wastewater surveillance in the United States is one of the greatest advancements in communicable disease surveillance in a generation,” she said.

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