The man, an older adult with underlying health conditions, was being treated for a bird flu called H5N5 after becoming seemingly the first known human infected by the strain, according to a statement from the Washington State Department of Health on Friday.
The man from Grays Harbor County, about 125 km southwest of Seattle, had a backyard flock of domestic poultry that had been exposed to wild birds, health officials said.
“The risk to the public remains low,” the statement from state health officials said. “No other people involved have tested positive for avian influenza.”
Health officials said they will monitor anyone who came in close contact with the man, but “there is no evidence of transmission of this virus between people”.
Earlier this month, the Centres for Disease Control and Prevention issued a statement about the infection that said no information would suggest “the risk to public health has increased as a result of this case”. H5N5 is not believed to be 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 those have been mild illnesses in workers on dairy and poultry farms.
The distinction between H5N5 and H5N1 lies in a protein involved in releasing the virus from an infected cell and promoting spread to surrounding cells.
