Washington state reports presumptive human case of bird flu

Washington state has reported a preliminary human case of avian influenza in an adult from Grays Harbor County, according to health officials.

In a statement released on Thursday, health officials said the individual, an older adult with underlying health conditions, tested preliminarily positive for bird flu. Confirmatory testing is underway at the Washington State Public Health Laboratories.

The patient developed a high fever, confusion, and respiratory distress in early November. The individual was initially treated in Grays Harbor and Thurston counties and is now receiving care in King County. Officials did not release the patient’s current condition.

Health authorities are working to determine how the infection occurred, including whether the patient had contact with wild or domestic birds. Anyone who had close contact with the patient is being monitored for symptoms.

“Public health disease experts have not identified any risk to the public,” the state health department said, noting that human-to-human transmission of avian influenza is extremely rare and has never been documented in the United States.

Health officials did not specify the strain involved in the Washington case, though H5N1 clade 2.3.4.4b has been the predominant strain detected in human infections in the United States since last year.

LINK: A list of all human cases of H5N1 bird flu since 2021

If confirmed, the Washington case would be the fifth human infection with H5N1 reported in the United States in 2025. Earlier cases were detected between January and February in California, Nevada, Ohio, and Wyoming, two of which were severe.

Additional infections with this same clade have been reported in the United Kingdom and Mexico, including the death of a 3-year-old girl in Mexico. Other H5N1 cases worldwide this year have occurred mostly in Cambodia, with additional cases in Vietnam, China, Bangladesh, and India involving an older endemic strain.

H5N1’s 2.3.4.4b clade, first identified in wild birds in Asia around 2020, has since become the dominant strain globally. It spread rapidly along migratory pathways across Europe and the Americas, causing widespread outbreaks in poultry and wild birds and unprecedented spillover into mammals.