A person in the United States has died after being infected with the rare H5N5 strain of bird flu, in what is believed to be the first known human fatality linked to this virus.
Health officials in Washington state said the patient, an older adult with underlying health conditions from Grays Harbor County, had been hospitalized since early November after developing high fever, confusion and respiratory symptoms. The individual kept a backyard flock of poultry that had been exposed to wild birds, which is believed to be the source of the infection.
The Washington State Department of Health said the risk to the general public remains low and confirmed there is no evidence of person-to-person transmission. No other close contacts have tested positive, though monitoring is ongoing.
The US Centers for Disease Control and Prevention previously stated that this case does not indicate an increased risk to public health.
Officials noted that H5N5 is not currently considered more dangerous to humans than the better-known H5N1 strain, which has caused around 70 human infections in the US during 2024 and 2025, mostly resulting in mild illness among poultry and dairy workers.
The main difference between H5N5 and H5N1 is a variation in a viral protein that helps the virus spread between cells.
