A resident of Washington state has been diagnosed with a case of bird flu, marking the first known human infection in the United States caused by the H5N5 strain of the virus. This is the first human bird flu case reported in the country since February, according to health officials.
Details of the Case and Health Response
The patient, identified as an older adult with pre-existing health conditions, remains hospitalised. State officials announced the case on Friday, confirming a preliminary diagnosis that was first reported the day before.
The individual was infected with an avian influenza virus known as H5N5. State and federal health authorities believe this to be the first documented human infection with this particular strain globally. The patient, a resident of Grays Harbor County, maintained a backyard flock of domestic poultry. Officials suspect these birds, which had contact with wild birds, are the most probable source of the infection, though the investigation is ongoing.
Expert Analysis on the Viral Threat
Leading flu experts have weighed in on the potential risk of the H5N5 virus. Richard Webby, a prominent flu researcher at St. Jude Children's Research Hospital, stated that the H5N5 virus behaves similarly to the more common H5N1 strain. "My gut instinct is to consider it the same as H5N1 from a human health perspective," Webby said.
Further insights came from Webby, who also directs the WHO Collaborating Centre for Studies on the Ecology of Influenza in Animals and Birds. He explained that the virus faces significant biological hurdles in adapting to humans. "I think it's clear it's not an easy leap for this virus to make, to switch from being a duck virus to being a human virus... It's going to take a little bit of the biological stars aligning for that to happen," he noted, adding that the exact likelihood of such an event is unknown.
The Centers for Disease Control and Prevention (CDC) has aligned with this assessment, issuing a statement that no current information suggests an increased risk to public health. The agency is awaiting a specimen from Washington to conduct more comprehensive tests.
Context and Broader Outlook
This new H5N5 case emerges against a backdrop of other avian flu activity. In 2024 and early 2025, the U.S. reported 70 human infections, primarily among workers on dairy and poultry farms. Most cases were mild, with one reported fatality.
While human cases had paused in recent months, the virus has continued to circulate in animal populations. In the past month alone, nearly 70 U.S. poultry flocks—both commercial and backyard—have been affected, impacting over 1.7 million birds. The last confirmed case in livestock was reported about a month ago in Idaho dairy cows.
The CDC maintains that the overall risk to the general public remains low. However, the risk is considered higher for individuals who have direct contact with cattle, poultry, or wild birds.
