A Washington state resident has been diagnosed with bird flu, the first case in the US since February. Health officials announced Friday that the case involved a different strain of bird flu than previous infections, the AP reported.
The patient, an older adult with underlying medical conditions, remains hospitalized. The preliminary diagnosis was announced on Thursday and later confirmed on Friday.
The person was infected with bird flu called H5N5, state officials said, the AP reported.
State and federal health officials said this appears to be the first known human infection with the H5N5 bird flu virus.
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This version is not considered a greater threat to human health than the H5N1 virus behind a wave of 70 reported human infections in the US in 2024 and 2025. Most of these were mild illnesses in dairy and poultry farm workers.
Expert opinions
“I think it’s clear that it’s not an easy jump for this virus to go from a duck virus to a human virus. I think that’s pretty clear, but I certainly wouldn’t put money on it not being able to make that jump,” said Webby, director of the World Health Organization’s Collaborating Center for Studies on Influenza Ecology, in Animals and Animals.
“It’s going to take some biological stars to align for that to happen. We could argue exactly how likely that is, but nobody really knows. Unfortunately, only time will tell.”
“These viruses behave similarly,” said Richard Webby, a prominent influenza researcher at St. John’s Children’s Research Hospital. Jude in Memphis, Tennessee. “My instinct is to think of it as the same as H5N1 from a human health perspective.”
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The Centers for Disease Control and Prevention issued a similar statement on Friday, saying that no information indicates that “the risk to public health has increased as a result of this case.”
The agency is awaiting a sample from Washington to conduct further tests.
The difference between H5N5 and H5N1 lies in the protein involved in releasing the virus from the infected cell and promoting its spread to surrounding cells.
A Grays Harbor County resident, who has not been identified, has a flock of poultry in his backyard that have been exposed to wild birds, health officials said. They believe domestic poultry or wild birds are the most likely source of exposure, but say they are still investigating.
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In 2024 and early 2025, infections were reported in 70 people in the US – most of them dairy and poultry farm workers. One person died, but most of those infected had mild illnesses.
While the US has not reported human bird flu infections for several months, recent cases have occurred in poultry and livestock flocks. In the past month, nearly 70 U.S. poultry flocks — both commercial and domestic — have been affected, with more than 1.7 million birds affected, according to the U.S. Department of Agriculture (USDA). The last confirmed case in livestock was about a month ago in a dairy cow in Idaho.
The CDC said the risk to the general public remains low, although it is higher for individuals working with livestock and poultry or those in contact with wild birds.
(With input from agencies)
