Washington state reports world’s first human H5N5 bird flu death
Health authorities in Washington state have confirmed the world’s first known human infection and death from the H5N5 strain of avian influenza, though officials stress that the risk to the general public remains low.
The patient, an older adult from Grays Harbor County with underlying health conditions, died while receiving treatment for H5N5, according to statements issued on Friday by the Washington State Department of Health.
The individual kept a backyard flock of mixed domestic birds that had likely been exposed to wild birds; environmental samples from the property later tested positive for avian influenza.
Officials said there is no indication that the virus has spread to others. No close contacts or individuals involved in managing the flock have tested positive, and there is “no evidence of transmission of this virus between people”. Public health teams will continue monitoring those who had direct contact with the patient or the backyard flock.
The US Centres for Disease Control and Prevention (CDC) earlier noted that nothing about the case suggests an increased threat to public health. H5N5 is not believed to pose a greater risk than H5N1, the strain behind more than 70 human infections nationwide in 2024 and 2025, mostly mild cases among dairy and poultry workers.
The primary genetic distinction between H5N5 and H5N1 lies in a viral protein that affects how efficiently the virus is released from infected cells and spreads within the host.
Despite the unprecedented nature of the case, health officials emphasised that the overall risk to the public remains low and confined to those who have close, unprotected contact with infected birds or contaminated environments.
Reuters
