Unprecedented tragedy: US records first death linked to H5N5 bird flu

The person was an older adult with underlying health conditions.

Testing at the UW Medicine Clinical Virology Lab identified the virus as H5N5, making this the first recorded infection with this variant in a person globally. The result was confirmed by the Centers for Disease Control and Prevention (CDC).

However, the Health Department says the risk to the public is still low.

The department said in a news release, "No other people involved have tested positive for avian influenza. Public health officials will continue to monitor anyone who was in close contact with the patient for symptoms to ensure that human-to-human spread has not occurred. There is no evidence of transmission of this virus between people."

"The person had a backyard flock of mixed domestic birds. DOH testing identified avian influenza virus in the environment of the flock, making exposure to the domestic poultry, their environment, or wild birds the most likely source of exposure for this patient. People who had exposure to the backyard flock and environment are also being monitored for symptoms," it added.

According to the government department, Avian influenza is a disease caused by influenza type A viruses, which naturally occur in wild aquatic birds around the world.

These viruses can infect other bird species, and occasionally mammals, and can be deadly to domestic birds such as chickens and turkeys. On rare occasions, avian influenza viruses can infect people and make them sick.

Most cases have occurred in people who were exposed to sick or infected animals. Reported human cases of avian influenza in the United States have ranged from mild to severe, with one fatality.

The risk of avian influenza increases in the fall and winter because migratory birds can carry the virus and spread it to domestic animals including commercial poultry farms and backyard flocks.

Transmission of avian influenza between humans is extremely rare and has never been documented in the United States. To ensure that human-to-human spread is not occurring, public health officials are contacting anyone who has been in close contact with the patient to monitor for symptoms and provide testing and treatment as needed.