Health officials in Washington state have confirmed the first known human death caused by the rare H5N5 strain of bird flu, though they emphasise that the overall public risk remains low.
The patient, an older adult from Grays Harbor County with underlying health conditions, had been hospitalised since early November after developing a high fever, confusion and respiratory issues. The individual kept a backyard flock of poultry that had been exposed to wild birds.
The Washington State Department of Health said no other people connected to the case have tested positive, and there is no evidence of human-to-human transmission. Officials are monitoring anyone who had close contact with the patient.
The US Centers for Disease Control and Prevention also stated that the case does not indicate an increased threat to public health. H5N5 is not considered more dangerous to humans than H5N1, the strain linked to roughly 70 reported human infections in the US during 2024 and 2025, most of which were mild cases among dairy and poultry workers.
H5N5 and H5N1 differ in the viral protein responsible for helping the virus spread between cells.
