A person in Washington state is believed to have become the first known human to die from the rare H5N5 strain of bird flu, though health officials say the risk to the wider public remains low.
The patient, an older adult with underlying health conditions from Grays Harbor County, had been hospitalised since early November after developing a high fever, confusion and respiratory problems. According to the Washington State Department of Health, the individual had a backyard flock of poultry that had been exposed to wild birds.
State officials said no other people connected to the case have tested positive, and there is currently no evidence of person-to-person transmission. Close contacts are being monitored as a precaution.
The Centers for Disease Control and Prevention previously stated that this case does not suggest an increased risk to public health. H5N5 is not considered more dangerous to humans than the better-known H5N1 strain, which caused around 70 mostly mild human infections in the US during 2024 and 2025, largely among farm workers.
The main difference between the two strains lies in a viral protein that affects how the virus spreads between cells.
