A study published Thursday by the Centers For Disease Control and Prevention suggests bird flu infections in humans are being significantly undercounted in the U.S.
CDC researchers tested attendees at the American Association of Bovine Practitioners veterinary conference in Ohio in 2024. 150 veterinarians from 46 states had their blood tested. None of the test subjects reported red eyes or any other symptoms of bird flu.
Three vets showed antibodies for H5N1 avian influenza in their test results. All three had worked with dairy cattle, though none of the herds were known to be infected. One of the vets had worked with poultry, and all of the vets had also worked with other animals.
Experts told The Associated Press the test results suggest bird flu in humans is being undercounted.
"This means that people are being infected, likely due to their occupational exposures, and not developing signs of illness and therefore not seeking medical care," said Dr. Gregory Gray, an infectious disease researcher at the University of Texas Medical Branch in Galveston.
If people are not reporting to hospitals or doctors' offices with symptoms, it's not possible to get a full picture of the spread of the disease in humans.
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The study is the first on H5N1 bird flu to be released during the Trump administration.
Just days after President Trump took office, the agency froze most of its external communications, including weekly reporting on infectious disease. The CDC and the U.S. Department of Agriculture also cancelled meetings with congress and with state-level health agencies.
The freeze was in place until at least Feb. 1. Health officials and experts worry such delays will deprive them of valuable time to understand where, when and how bird flu is spreading.
The risk to the public from bird flu remains low, the CDC says. But agency officials warn people who have close contact with birds, poultry and cows should continue to exercise caution, including using gloves and respiratory protection.
