The first human death from a rare H5N5 bird flu strain has been reported in Washington State, marking a significant development in the ongoing battle against avian influenza. The individual who succumbed to the virus had been hospitalized since early November and was identified as an older person with underlying health conditions who kept backyard domestic birds. Unlike the more common H5N1 strain that has caused human infections and fatalities in the U.S. since 2024, the H5N5 subtype responsible for this recent death represents a new challenge in the fight against avian influenza.
The distinction between various bird flu strains lies in the hemagglutinin and neuraminidase proteins that adorn their outer shells. While both the H5N1 and H5N5 viruses share the H5 hemagglutinin protein, they differ in their neuraminidase proteins. This unique genetic makeup of the H5N5 strain underscores the importance of ongoing surveillance and monitoring efforts to track the evolution and spread of avian influenza viruses.
Richard Webby, a virologist at St. Jude Children’s Research Hospital, emphasizes that the emergence of the H5N5 strain does not necessarily indicate a heightened pandemic risk or severity compared to the more prevalent H5N1 virus. However, the potential for genetic reassortment between different influenza viruses circulating in animals poses a concerning prospect for the creation of novel viral strains with increased transmissibility and pathogenicity.
In response to the recent fatality, public health officials are closely monitoring individuals who had close contact with the deceased person to prevent further transmission of the virus. It is crucial for individuals who raise backyard poultry to implement strict biosecurity measures, including separating domestic birds from wild populations, wearing protective gear when handling birds, and practicing proper hygiene protocols to minimize the risk of infection.
Furthermore, experts recommend getting a seasonal flu shot as a preventive measure against contracting multiple strains of influenza simultaneously, which could facilitate viral mixing and potentially lead to more severe outcomes. By staying informed about avian influenza risks and adhering to recommended safety precautions, individuals can help safeguard public health and mitigate the spread of potentially dangerous pathogens.
As we navigate the complexities of emerging infectious diseases like the H5N5 bird flu strain, it is essential to prioritize scientific research and public health interventions to combat these evolving threats. By supporting science journalism and investing in critical research initiatives, we can collectively contribute to a safer and healthier future for all.

