A Washington state resident has been hospitalized in critical condition with a dangerous and “unpredictable” strain of bird flu never before detected in a human being — a development infectious-disease experts are calling deeply alarming.

Health officials confirmed that the unidentified older man, who lives in rural Grays Harbor County on Washington’s Pacific coast, tested positive for H5N5, a subtype of avian influenza until now found only in wild birds and domestic poultry. The patient arrived at the hospital earlier this month with high fever, respiratory distress, and confusion, and has remained hospitalized as investigators race to identify how the virus jumped to a human host.

According to the state Department of Health, the man kept a mixed backyard flock of chickens and other domestic birds. Several of his birds had recently died, and wild waterfowl — especially ducks and geese known to carry H5N5 — frequented the property. Officials believe exposure to either group is the “most likely” source of infection.

So far, no secondary infections have been found, and both the state and federal Centers for Disease Control and Prevention are stressing that the general public risk remains low. There is currently no evidence of human-to-human transmission.

But experts caution that the virus’s behavior cannot be predicted.

“Viral evolution can be unpredictable,” the Department of Health warned, a reminder as scientists continue to monitor mutations in other avian flu strains circulating through the country.

H5N5 differs from the more common H5N1 strain in its surface protein structure, but both viruses originate in wild bird populations and have crossed into U.S. poultry with increasing frequency since 2022. H5N1 has already infected dairy cattle and caused sporadic human cases, including 71 U.S. infections since 2024. Most were mild, but a Louisiana resident died in January after catching the virus from backyard chickens exposed to wild birds.

As for the Washington patient, state officials say he remains in the hospital as teams continue environmental testing and flock surveillance to determine the precise route of transmission.

The case marks the first documented human infection of H5N5 anywhere in the world, and public-health agencies are now watching closely to determine whether this incident remains isolated, or signals a new chapter in the ongoing clash between avian influenza and human vulnerability.

(YWN World Headquarters – NYC)