US health officials have reported what is believed to be the first human death linked to the rare H5N5 strain of bird flu, though they stress the risk to the general public remains low.
The case involved an older adult in Washington state with underlying health conditions. The patient, who lived in Grays Harbor County, was hospitalised in early November after developing high fever, confusion and respiratory symptoms. They were found to be infected with H5N5, a strain not previously known to have caused human fatalities.
State officials said 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. No other close contacts have tested positive, and there is no evidence of person-to-person transmission.
The US Centers for Disease Control and Prevention previously stated that this case did not indicate an increased risk to public health. Health authorities will continue to monitor those who had close contact with the individual.
H5N5 is not considered more dangerous than the H5N1 strain, which has caused around 70 mostly mild human infections in the US during 2024 and 2025, primarily among workers in poultry and dairy farming. The main biological difference between the two strains involves a viral protein that affects how the virus spreads between cells.
