A person in Washington state is believed to be the first human to die from the rare H5N5 strain of bird flu, though health officials say the risk to the general public remains low.
The patient, an older adult with underlying health conditions from Grays Harbor County, was hospitalized in early November after developing a high fever, confusion and breathing problems. They were treated for H5N5, a strain not previously known to have infected humans.
Health officials said the person had a backyard flock of domestic poultry that had been exposed to wild birds. No other people who were in contact with the individual have tested positive, and there is no evidence of person-to-person transmission.
The Centers for Disease Control and Prevention said earlier this month that there was no indication the public health risk had increased because of this case. Authorities will continue to monitor close contacts as a precaution.
Experts said H5N5 is not believed to pose a greater risk to humans than H5N1, which has caused around 70 mostly mild human infections in the US during 2024 and 2025, largely among farm workers.
The main difference between H5N5 and H5N1 lies in a viral protein that affects how the virus is released from infected cells and how it spreads to nearby cells.
