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.
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.”
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.”
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.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
FILE - A sign is seen outside a clinic with the South Plains Public Health District, Feb. 23, 2025, in Brownfield, Texas. (AP Photo/Julio Cortez, File)
A federal appeals panel on Thursday reversed a lower court decision that released former Columbia University graduate student Mahmoud Khalil from an immigration jail, bringing the government one step closer to detaining and ultimately deporting the Palestinian activist.
The three-judge panel of the 3rd U.S. Circuit Court of Appeals didn’t decide the key issue in Khalil’s case: whether the Trump administration’s effort to throw Khalil out of the U.S. over his campus activism and criticism of Israel is unconstitutional.
But in its 2-1 decision, the panel ruled a federal judge in New Jersey didn’t have jurisdiction to decide the matter at this time. Federal law requires the case to fully move through the immigration courts first, before Khalil can challenge the decision, they wrote.
“That scheme ensures that petitioners get just one bite at the apple — not zero or two,” the panel wrote. “But it also means that some petitioners, like Khalil, will have to wait to seek relief for allegedly unlawful government conduct.”
Thursday’s decision marked a major win for the Trump administration’s sweeping campaign to detain and deport noncitizens who joined protests against Israel.
Tricia McLaughlin, a Homeland Security Department spokesperson, called the ruling “a vindication of the rule of law.”
In a statement, she said the department will “work to enforce his lawful removal order” and encouraged Khalil to “self-deport now before he is arrested, deported, and never given a chance to return.”
It was not clear whether the government would seek to detain Khalil, a legal permanent resident, again while his legal challenges continue.
In a statement distributed by the American Civil Liberties Union, Khalil called the appeals ruling “deeply disappointing."
“The door may have been opened for potential re-detainment down the line, but it has not closed our commitment to Palestine and to justice and accountability," he said. "I will continue to fight, through every legal avenue and with every ounce of determination, until my rights, and the rights of others like me, are fully protected.”
Baher Azmy, one of Khalil's lawyers, said the ruling was “contrary to rulings of other federal courts."
“Our legal options are by no means concluded, and we will fight with every available avenue,” he said.
The ACLU said the Trump administration cannot lawfully re-detain Khalil until the order takes formal effect, which won't happen while he can still immediately appeal.
Khalil’s lawyers can request that the panel's decision be set aside and the matter reconsidered by a larger group of judges on the 3rd Circuit Court of Appeals, or they can go to the U.S. Supreme Court.
An outspoken leader of the pro-Palestinian movement at Columbia, Khalil was arrested last March. He then spent three months detained in a Louisiana immigration jail, missing the birth of his first child.
Federal officials have accused Khalil of leading activities “aligned to Hamas,” though they have not presented evidence to support the claim and have not accused him of criminal conduct. They also accused Khalil, 31, of failing to disclose information on his green card application.
The government justified the arrest under a seldom-used statute that allows for the expulsion of noncitizens whose beliefs are deemed to pose a threat to U.S. foreign policy interests.
In June, a federal judge in New Jersey ruled that justification would likely be declared unconstitutional and ordered Khalil released.
President Donald Trump's administration appealed that ruling, arguing the deportation decision should fall to an immigration judge, rather than a federal court.
Khalil has dismissed the allegations as “baseless and ridiculous,” framing his arrest and detention as a “direct consequence of exercising my right to free speech as I advocated for a free Palestine and an end to the genocide in Gaza.”
New York City’s new mayor, Zohran Mamdani, said on social media Thursday that Khalil should remain free.
“Last year’s arrest of Mahmoud Khalil was more than just a chilling act of political repression, it was an attack on all of our constitutional rights,” Mamdani wrote on X. “Now, as the crackdown on pro-Palestinian free speech continues, Mahmoud is being threatened with rearrest. Mahmoud is free — and must remain free.”
Judge Arianna Freeman dissented Thursday, writing that her colleagues were holding Khalil to the wrong legal standard. Khalil, she wrote, is raising “now-or-never claims” that can be handled at the district court level, even though his immigration case isn't complete.
Both judges who ruled against Khalil, Thomas Hardiman and Stephanos Bibas, were Republican appointees. President George W. Bush appointed Hardiman to the 3rd Circuit, while Trump appointed Bibas. President Joe Biden, a Democrat, appointed Freeman.
The two-judge majority rejected Freeman's worry that their decision would leave Khalil with no remedy for unconstitutional immigration detention, even if he later can appeal.
“But our legal system routinely forces petitioners — even those with meritorious claims — to wait to raise their arguments," the judges wrote.
The decision comes as an appeals board in the immigration court system weighs a previous order that found Khalil could be deported to Algeria, where he maintains citizenship through a distant relative, or Syria, where he was born in a refugee camp to a Palestinian family.
His attorneys have said he faces mortal danger if forced to return to either country.
Associated Press writers Larry Neumeister and Anthony Izaguirre contributed to this story.
FILE - Palestinian activist Mahmoud Khalil holds a news conference outside Federal Court on Tuesday, Oct. 21, 2025 in Philadelphia (AP Photo/Matt Rourke, File)
