A new study published by the Centers for Disease Control and Prevention shows that the H5N1 bird epidemic virus in many parts of the country may be undetected in livestock and may be infecting unknown veterinarians.
In the weekly report on morbidity and mortality at health facilities, a group of researchers from the Centers for Disease Control and Prevention, Ohio Department of Health and the American Association. Cattle practitioners reported their analysis of veterinarians from 150 cattle or cattle from 46 states and Canada.
They found three of them had antibodies to the H5N1 avian influenza virus in the blood. However, none of the infected veterinarians will recall any symptoms, including conjunctivitis or pink eyes, the most common symptom in human cases.
The three veterinarians also reported to investigators that they did not work with cattle or poultry known to be infected with the virus. In one case, a veterinarian reported that practice was conducted only in Georgia (cows) and South Carolina (on poultry), two states that have not yet reported H5N1 infection in cows.
Seema Lakdawala, a microbiologist at Emory University in Atlanta (not participated in the study), was surprised that, given that another CDC study showed that only 2% of veterinarians surveyed tested positive for antibodies, another study showed that 17% of dairy workers had been infected. But she said she was even more surprised that they didn’t know they were infected or worked with infected animals.
“These surprising results suggest that serum surveillance studies are important to inform undiagnosed infection risks,” she said. “Veters are on the frontline of an outbreak, and increased biosafety practices such as respiratory and eye protection should reduce their exposure risk.”
Jennifer Nuzzo, director of the Brown University Pandemic Center, described the study as a “good news and bad news story.”
“On the one hand, we’re seeing evidence that the H5N1 outbreak on the farm may be more than reported,” she said. “On the other hand, I guarantee there is no evidence that infections between veterinarians have been widespread. This means more work can and should be done to prevent the spread of the virus to more farms and disgusting workers.”
The analysis was conducted in September 2024. At the time, there were only four human cases, and infections were believed to be limited to cows in 14 states. Since then, 68 people have been infected – 40 have used infected cows to work – and the virus has reportedly infected herds in 16 states.
Retired American agricultural scientist John Korslund said in an email that finding H5N1 antibodies in veterinary blood is an interesting “but very inaccurate way to measure the incidence of state cattle.” But this emphasizes that “humans are vulnerable to subclinical infections and may be at risk of reclassification, which I guess we already know.”
When a person or animal is infected with multiple influenza viruses, it is reclassified, allowing the two to mix and exchange “hardware”, which may lead to a new, more toxic strain.
More importantly, he said, the D1.1 version found in Nevada cows and a person living in the state is “changing the landscape.” … [P]eople may be more susceptible to severity (or not). ”
“I believe we will find it in other states. Its behavior and transmissibility within and between herds remains a black box,” he said.
