A resident of Washington state has become the first person in the world to die from the H5N5 strain of bird flu, officials confirmed Friday.
The virus had previously been identified in animals but had never before infected a human.
The patient, an older adult with underlying health conditions, was hospitalized earlier this month after experiencing a high fever, confusion, and severe breathing difficulties. They were initially treated in Grays Harbor County before being transferred to a hospital in King County for specialized care.
The individual’s identity, age, and other personal details have not been released.
Laboratory testing confirmed H5N5 as the cause of infection. Public health officials said exposure to domestic or wild birds, including a backyard flock owned by the patient, was the likely source of the virus.
Two of the patient’s birds reportedly died from an unidentified illness in recent weeks. No additional human cases have been detected, and officials said there is currently no evidence of human-to-human transmission.
“The risk to the public remains low,” the Washington State Department of Health said. “Public health officials will continue to monitor anyone who was in close contact with the patient for symptoms to ensure that human-to-human spread has not occurred.”
Experts noted that while H5N5 is new to humans, it is not necessarily more infectious or severe than other strains, such as H5N1, which has caused previous human cases of bird flu, as the Daily Mail reported.
Dr. Beth Lipton, a state public health veterinarian, said the virus represents a rare occurrence rather than a broader public health threat.
“This is the first known instance of H5N5 infecting a person,” she said. “It is not a completely new virus, just a strain that has never been seen in humans before.”
Canadian virologist Dr. Angela Rasmussen emphasized the virus’s unpredictable nature.
“It’s a reassortment that put someone in the hospital,” she tweeted. “I hope epidemiologists are investigating to assess who else might have been exposed so appropriate outbreak control can be applied.”
Dr. William Schaffner, an infectious disease expert in Tennessee, echoed that the event is likely isolated.
“Infection with H5N5 bird flu virus is probably a one-off event and does not have widespread implications for the general public,” he said.
This case marks the first human bird flu infection in the U.S. in at least eight months and the first recorded in Washington state this year.
Since the 2022 outbreak, 71 people in the U.S. have been infected with bird flu, most of whom have been linked to H5N1. One previous death occurred in Louisiana.
Officials continue to monitor those who had close contact with the patient. No further infections have been identified. Authorities note that infection can occur through exposure to saliva or droppings from infected birds or handling the body of a bird that has died from the virus.
Bird flu remains widespread in U.S. wild and domestic birds, affecting tens of millions since 2022, including farmed turkeys and other poultry.
Experts warn that seasonal migration increases the risk of virus spread to new areas.
However, the Centers for Disease Control and Prevention maintains that public risk from H5N5 remains low and continues active surveillance of human exposures.
