First Human Fatality from Rare Bird Flu Strain
Health officials in Washington state have confirmed what is believed to be the first human death from a rare strain of bird flu known as H5N5. The announcement was made on Friday, 22nd November 2025, with authorities moving quickly to reassure the public that the overall risk remains low.
Details of the Case and Source of Infection
The patient was an older adult from Grays Harbor County, situated approximately 78 miles southwest of Seattle, who had pre-existing health conditions. According to a statement from the Washington State Department of Health, the man was being treated for the H5N5 virus after becoming the first known human infected by this specific strain.
Investigations revealed that the man kept a backyard flock of domestic poultry. Health officials stated that this flock had been exposed to wild birds, which is the suspected source of the transmission.
Public Health Response and Risk Assessment
In their official communication, state health officials were clear in their assessment: "The risk to the public remains low." They confirmed that no other individuals involved in the situation have tested positive for avian influenza.
As a precaution, health teams will monitor anyone who had close contact with the man. Crucially, officials stated that there is no evidence of transmission of this virus between people, a key factor in containing its spread.
This case was previously flagged by the Centers for Disease Control and Prevention (CDC) earlier in the month. The federal body issued a statement confirming that the infection did not suggest an increased risk to public health.
The H5N5 virus is not currently considered a greater threat to human health than the more common H5N1 strain. The H5N1 virus was behind a wave of around 70 reported human infections in the U.S. in 2024 and 2025, most of which were mild illnesses in workers on dairy and poultry farms.
The primary distinction between the H5N5 and H5N1 viruses lies in a specific protein involved in releasing the virus from an infected cell and promoting its spread to surrounding cells.
