The Washington State Department of Health has confirmed the first-ever case of the rare H5N5 bird flu strain in a resident of Grays Harbor County. The patient, an older adult with pre-existing health conditions, is hospitalized after exhibiting influenza-like symptoms in early November. The infection is believed to have originated from exposure to a mixed backyard flock of poultry, which had contact with wild birds. Health officials note that while H5N5 has been reported in animals, this is the first known instance in humans.
Public health experts have not found any increased risk to the general population, according to the press release. The Centers for Disease Control and Prevention and the Washington State Department of Health currently consider the risk to the public from avian influenza to be low. Officials have recommended that poultry owners, wildlife handlers, and others who have contact with animals take precautionary measures such as avoiding contact with sick or dead birds and using appropriate protective gear.
The DOH is urging individuals to report suspected sick wildlife or domestic animals to the Washington State Department of Agriculture (WSDA). The release also emphasizes that while the seasonal flu vaccine does not prevent bird flu infections, it is important because infection with both viruses could result in the emergence of an avian influenza virus that is more easily transmitted from person to person.
The case also marks the country’s first human bird flu diagnosis since February. Previously, the CDC declared the bird flu emergency officially over, citing declining animal infections and an absence of human cases since February. The agency’s emergency response to H5N1 bird flu, which was activated in 2024, was deactivated on July 2, according to Reuters. While H5N1 has caused human illness — and even deaths — for years, H5N5 has mostly been limited to birds until now, per health officials.
Experts note that although H5N5 and H5N1 both originate from birds and share part of their genetic code, H5N5 has a different ‘end piece’ of its structure that changes how it behaves. This distinction means the virus’s potential for human-to-human transmission and the development of more transmissible strains remains under scientific scrutiny. The ongoing investigation into the source and spread of H5N5 underscores the importance of monitoring wildlife and domestic animal interactions to prevent future outbreaks.