Study Reveals Undetected Bird Flu Infections in Dairy Veterinarians, Raising Concerns Over Broader Spread

A recent study by the Centers for Disease Control and Prevention (CDC) has uncovered that three dairy veterinarians in the US were infected with the H5N1 bird flu virus, despite not exhibiting symptoms or working with known infected cows.

These findings, based on antibody testing of 150 veterinarians across 46 states, highlight the possibility of silent, undetected infections in regions not officially reported to have bird flu outbreaks.

The veterinarians involved in the study did not recall experiencing any flu-like symptoms, and one of them had worked exclusively in states where no bird flu outbreaks had been confirmed in cows. This raises concerns about the potential spread of the virus in areas not yet identified by health authorities. Experts suggest that this suggests the virus could be infecting animals and humans in more locations than currently known.

Since the bird flu outbreak was first detected in dairy cows in March, the virus has been confirmed in over 950 herds across 16 states, with 68 human infections recorded, primarily involving those who had close contact with infected animals. However, most human cases have been mild.

The study, which took place during a veterinary conference last September, involved veterinarians who practice in diverse areas, including regions with no reported outbreaks. Of the 150 vets tested, 25 reported having worked with cows suspected of or confirmed to have bird flu. The fact that three of the vets tested positive for antibodies without recalling any exposure to infected animals further points to the possibility of missed cases in asymptomatic individuals.

The results suggest that while some veterinarians may be unknowingly exposed to the virus, it is not yet clear how the virus is transmitted to them. The findings also indicate the need for expanded testing, both among veterinary professionals and dairy farm workers, who may be at higher risk of exposure. The US Department of Agriculture (USDA) initiated a nationwide program in December to test bulk milk samples, and early testing in Nevada revealed a new strain of the virus in dairy herds.

Experts stress the importance of continued surveillance to better understand the extent of the outbreak and prevent further spread.

“This is an issue that is not going away, and we can’t ignore it,” said Dr. Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory.

As the study suggests, there may be many more undetected cases in both animals and humans, calling for heightened monitoring and testing across the country.

With input from the New York Times and STAT.