A Washington state resident died from the new H5N5 strain of chickenpox

The first person infected with H5N5 bird flu has died, according to health officials in Washington.

The man, who lives in Grays Harbor County, was hospitalized earlier this month in Kings County, where Seattle is located.

Washington State Department of Health officials have not released the person’s name, age or gender. The man was considered “elderly” and had underlying health conditions, according to a news release from Grays Harbor County health officials last week. Their symptoms included high fever, confusion and difficulty breathing.

This person had a backyard flock of mixed domestic chickens.

The virus tested by the health department was “found in a flock environment … with domestic poultry, their environment, or wild birds as the most likely source of exposure for this patient.”

State health officials said they are monitoring other people who may have been exposed to the herd and the environment.

This particular strain of bird flu, H5N5, has never been seen in a person before. It first appeared in 2023, infecting birds and mammals in eastern Canada.

According to last year’s research on the new strain, some infected animals have made an important change in the virus that allows it to be easily transmitted between mammals.

Epidemiologists and virologists worry that bird flu could become a pandemic if allowed to spread and mutate. For example, the H5N1 virus circulating in dairy cattle in North America is a mutation that spreads easily between people.

Every time a bird flu virus infects someone, concerns grow that it could mutate, become more transmissible or more deadly. For example, if a sick person has another flu virus in their body, there is concern that the viruses could exchange genetic material. Just by having the opportunity to replicate and develop millions of times in the human body, it can acquire lethal mutations.

Health officials say the risk to the public is low and that no other people have tested positive for bird flu. They say there is no evidence of transmission of the virus between people, but they are monitoring anyone who had close contact with the patient.