According to state health officials, a resident of Washington State has died from the H5N5 avian influenza, making this the first documented human case of the rare strain of bird flu and the first death attributed to this strain in the world. The individual who died was an older adult living in Grays Harbor County with undisclosed health issues, who had been hospitalized since early November as a result of high fever, respiratory distress, and confusion.
The case has attracted national attention, as worries about zoonotic disease transmission and preparedness for future public health threats have been front and center in public discussion.
The Case: H5N5, Poultry, and Patient History
Washington’s health department reported the first human case of the H5N5 strain, previously identified only in birds and a few mammals. The husbandry was located in a backyard flock comprised of various domestic poultry. Environmental sampling of the patient’s property confirmed the presence of the avian virus. Close proximity to the domestic birds or, potentially, exposure to wild birds is believed to have prompted the infection. Human-to-human transmission has been ruled out at this time. Individuals who had contact with the flock and the patient are being monitored, but there have not been any additional cases reported.
Disease Profile: H5N5 and the Avian Influenza Threat
Since being systematically studied for its capability to mutate and sometimes infect humans, avian influenza (often referred to as “bird flu”) has been on the global health watchlist for many years. In 2023, a new subtype of the H5 virus family called H5N5 was first detected in birds in Canada. The H5N5 strain possesses mutations that are thought to enhance transmissibility among mammals which has raised alarms among global health watchers and virologists.
Most of the U.S. cases of human avian flu have again primarily involved H5N1, and affected mainly farm workers, poultry workers, and other people that may have been exposed or encountered the virus through personal associations with sick birds or during culling. Most cases have been mild, although some severe cases and deaths have occurred.
In the notable case, it is more likely that the existing health problems of the patient in Washington contributed to their death after rapid hospitalization and antiviral medications.
Public Health Response and Risk Assessment.
The Washington State Department of Health (DOH) has reiterated that the risk of widespread infection remains low. Routine surveillance of individuals exposed to infected flocks—and people in close proximity to the index case, has not uncovered additional human cases to date. Bird owners have been provided with increased biosecurity and hygiene protocols, while residents are encouraged to avoid handling sick or dead wild birds, report wildlife mortality events and seek medical attention for flu-like illnesses after exposure to birds.
The U.S. Centers for Disease Control and Prevention (CDC) is working with state health officials to monitor the potential for viral changes and human-to-human transmissibility.
National and Global Implications
This fatality comes as the world is paying more attention to animal health, especially with outbreaks of avian flu within poultry, cattle, and mammals in the previous two years in North America, Europe, and Asia. Animal health experts warn that the continued recombining of avian and human populations increases opportunities for “spillover” events that could produce new more infectious or vaccine-resistant strains.
The CDC confirmed that there were at least 70 human avian flu cases (mostly H5N1) in the United States since the turn of the year in 2024, although most cases were mild flu-like symptoms, including the two deaths of which the case in Washington was one. The infrequent nature, and frequency of these cases, provide impetus for expedited identification, an improved surveillance system in animals, and a push for the accelerated development of next-generation vaccines.
Lessons and Precautions
Public health authorities emphasize the need for vigilance for those who handle backyard flocks and poultry and stress basic protective measures, wear gloves and masks, thoroughly wash hands, and separate sick birds. Case investigators want to stress that, while this is a terrible tragic death, it is an isolated case which brings back attention to the unpredictable nature of zoonotic pathogens and the ongoing need for coordination of health between humans and animals.
Researchers point out that we are better prepared to rapidly detect and sequence potential information, and that unusual symptoms after bird exposure should prompt medical evaluation.
