Ohio State University: As bird flu spreads to cows and infected people, here’s what to know about the latest avian flu strains

[Commonground]

February 26, 2025

A dominant strain of avian flu, or “bird flu” (H5N1) has jumped species, spreading to numerous animals, including dairy cattle and even to human farm workers.

Avian influenza isn’t new, but the virus continues to evolve and is likely here to stay, says Andrew Bowman, DVM, PhD, a molecular epidemiologist in the Department of Veterinary Preventive Medicine at The Ohio State University.

“When we’ve dealt with highly pathogenic avian influenza in the U.S. before, it usually died out in wild birds, and we managed to control it in poultry,” explains Dr. Bowman, who studies influenza in animal populations. “This one is hanging on in wild birds and continues to spread. It’s just always there with a constant threat of spillover; I think that’s what’s different today.”

Continued: https://vet.osu.edu/news/bird-flu-sp...an-flu-strains

[Commonground]

Excerpt from Post #1:

“You don’t know which strain might come across and be able to do that,” Dr. Bowman says. “We also don’t really know what happens when the virus sticks around in other species for a long time. Like with dairy cattle, if the virus keeps spreading from cow to cow, does that make it more adapted to mammals and potentially more capable of transmitting human to human?

“It certainly gives me concern. We are in a very different influenza situation than we’ve ever been in before.”

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What we know about bird flu cases in people


The risk to humans remains low, according to the federal Centers for Disease Control and Prevention.

Isolated cases with infected farm workers started showing up in April 2024. Ohio had its first human case in February 2025.

One isolated case of a non-farm worker resulted in death in the U.S. The person had underlying health issues and was exposed to wild birds and a backyard flock of poultry.

“What’s important to know is that fatal cases in humans are different H5 strains than the cattle strain,” Dr. Bowman says. “That might be too broad of a term when we’re talking about the risk to humans. The human cases, while tragic, aren’t totally unexpected.”