Bird flu continues to spread in Washington state. What to know about the virus

Health officials continue to monitor the spread of bird flu in Washington state, where notable cases emerged over 2024.

The first human infections in the state were recorded this year, with more than a dozen people testing positive, mostly after close contact with infected poultry. The virus (H5N1) has also been found in commercially raised chickens, seals, and dairy cows, since first emerging at the beginning of the decade.

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Late last week, Woodland Park Zoo announced that a red-breasted goose died in a suspected case of bird flu. The zoo quickly isolated birds and restricted access to them. The Centers for Disease Control considers the current public health risk of bird flu to be low, but Peter Rabinowitz, the director of the University of Washington’s Center for One Health Research, says that can change.

“It’s certainly not going away and as long as it continues to circulate in farms and wild birds, it’s going to continue to pose a risk to people who have direct contact with infected animals," Rabinowitz told KUOW's Soundside.

The other issue is the potential for the virus to change, which could lead to person-to-person transmission.

“That has not happened yet, so the current public health opinion is that the risk to the general population is low," Rabinowitz said. "However, there’s definite risk to people who are working with potentially infected animals."

The H5N1 avian influenza has been around since the 1990s. It has evolved a bit since then. Earlier strains were more infectious and had higher mortality rates.

“About two years ago, a slightly different variant of H5N1 started circulating around the world in wild birds and really was notable for the extent it was moving around, and also became notable for its remarkable ability to infect mammals as well as birds," Rabinowitz said.

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“This is just unprecedented for bird flu. We’ve never seen a bird flu strain that’s able to infect so many mammals. Even more worrisome, this year, we saw another variant of the H5N1 that jumped from wild birds to dairy cattle and then spread from cow to cow, to many states, and this has infected dozens of workers in close contact with those cows.”

That's the challenge for public health officials, the agricultural industry, and workers on the ground. Rabinowitz notes that those workers are the most at risk and require significant protections.

“What happened in Washington state was that there was several commercial poultry facilities where there had been outbreaks of avian flu, then it’s necessary to depopulate a flock and that is a very hazardous procedure — to depopulate the flock and prevent any of the workers getting infected by getting any particles in their eyes or nose, mouth or throat," he said. "So there were some workers who became infected during the control operation.”

As Rabinowitz said, the virus is not going away. It spreads globally via wild birds which are difficult to manage. The best thing to do is keep the virus from jumping from birds to mammals. That's why state agencies and health researchers like Rabinowitz are watching to see if there are any changes in the virus’ patterns.

“What we’re looking for is whether the pattern changes at all," he said, "whether there is any evidence of person-to-person transmission, that would be a real game changer.”

The Washington Department of Fish and Wildlife has an online form to report sick wild birds.

Also, Washington's Department of Agriculture has a hotline to report sick domestic animals — 1-800-606-3056.

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