American Scientific A person in the Washington State has died of avian influenza. It’s the first human death from bird flu in the U.S. since January—but the infection was of a different strain than the one that has been devastating poultry farms and wild animals for the past several years.
The Washington State Department of Health announced the death on Friday, noting that the person who died had been hospitalized since early November. The agency identified them as an older person with underlying health conditions who had backyard domestic birds. It also confirmed that the virus was of the subtype H5N5—not the H5N1 strain that has caused 70 human infections and one death in the U.S. since 2024, as well as countless deaths of wild and domestic animals since it arrived in North America in late 2021. Many influenza viruses are identified by two classes of proteins that appear on their outer shells, hemagglutinin and neuraminidase. Each of these proteins comes in multiple forms, and different combinations of these two protein types are referred to as “subtypes” of virus. The long-circulating H5N1 virus and the H5N5 virus responsible for the recent human death have the same hemagglutinin protein (H5) on their outer shells but different neuraminidase proteins.
The fatality is not a reason to panic and does not suggest the risks of bird flu are larger than scientists have believed, says Richard Webby, a virologist at St. Jude Children’s Research Hospital. “We don’t have any reason to suspect H5N5 has more or less of a pandemic risk than H5N1, and similarly, we don’t have any reason to suspect, as a whole, it causes more severe disease,” he says. “Most people’s exposure to the H5 viruses is still going to be to the H5N1 just because there’s so much more of that in the bird population.”