Health officials in Washington State reported the death of an older adult on 21 November 2025 after confirmation of the first human infection with the H5N5 avian influenza strain. The case marked a significant zoonotic event and prompted intensified surveillance across regional medical facilities and public health networks.
Note that the individual was from Grays Harbor County. H5N5 is a subtype of the influenza A virus that causes avian influenza or bird flu. It occurs in wild aquatic birds and can infect other bird species. The subtype is considered a highly pathogenic avian influenza, but human cases are still considered rare. The Grays Harbor resident is the first known case.
The Washington State Department of Health said the patient maintained a backyard flock that included domestic birds. Some of which died during early November. Environmental testing confirmed avian influenza material nearby. This reinforced assessments that direct exposure represented the most plausible transmission route for the fatal infection.
Report indicates that the patient developed high fever, respiratory distress, and confusion before hospital admission in early November. Medical teams initiated antiviral therapy and diagnostic sequencing. H5N5 avian influenza was then confirmed. Officials stated that underlying conditions likely influenced the clinical progression during hospitalization.
Health authorities monitored more than 100 health care workers and contacts who may have experienced unprotected exposure. Officials reported no secondary infections as of November 22. Surveillance teams continue symptom checks and lab assessments to identify anomalies that might suggest undetected transmission from the index case.
Federal data indicated that 70 human infections with H5N1 avian influenza were confirmed across the United States during 2024 and 2025. Most of these human cases involved agricultural workers with direct contact with infected livestock. Health agencies stated that evidence does not show that H5N5 poses greater danger than the H5N1 avian influenza strain.
Global monitoring records showed that H5N5 circulated primarily among wild birds and poultry in North America, Europe, and Asia before 2025. Researchers noted that viral evolution through reassortment remained a concern due to the spread among animal populations. The Washington case emphasized risks associated with avian influenza subtypes.
Public health agencies urged residents who maintain backyard flocks to report sick or dead birds, limit direct contact, and prevent pets from approaching affected animals. Officials recommended vaccination with seasonal influenza formulations to reduce the likelihood of co-infection that might facilitate the development of reassorted influenza variants.
Officials reiterated that the risk to the general public remained low as of November 22 because no human-to-human transmission has been detected. They emphasized that surveillance, rapid diagnostic platforms, laboratory networks, and transparent reporting systems remain critical tools for preventing the wider spread of novel avian influenza strains.
FURTHER READINGS AND REFERENCES
- Washington State Department of Health. 21 November 2025. “Grays Harbor County Resident Dies From Complications of Avian Influenza.” Washington State Department of Health. Available online
- Washington State Department of Health. 14 November 2025. “H5N5 Avian Influenza Confirmed in Grays Harbor County Resident.” Washington State Department of Health. Available online