First H5N5 Bird Flu Case in Human Confirmed in Washington State

What You Need to Know About the First Human H5N5 Bird Flu Case

Health officials in Washington state have confirmed the first-ever human case of the H5N5 strain of avian influenza, commonly known as bird flu. This historic case marks an important moment in public health monitoring as the virus, previously only seen in animals, has now been detected in a human.

The Patient's Condition

The infected individual, an older adult with underlying health conditions, was hospitalized in early November after developing severe symptoms including high fever, confusion, and difficulty breathing. According to health officials, the patient remains hospitalized in serious condition.

"The affected person has a mixed backyard flock of domestic poultry at home that had exposure to wild birds," stated the Washington State Department of Health in a press release. "The domestic poultry or wild birds are the most likely source of virus exposure."

Public health officials discuss the H5N5 bird flu case at a press conference. - Image from https://www.msn.com/en-us/health/other/washington-resident-is-infected-with-a-different-type-of-bird-flu/ar-AA1Qtb7y

Understanding H5N5

Unlike the more commonly discussed H5N1 strain that has infected thousands of cattle, commercial poultry, and wild birds in the past two years, H5N5 has never before been detected in humans. This makes the Washington case particularly significant for epidemiologists and public health officials.

"This is the first human case of H5N5 ever known," explained Dr. Scott Lindquist, Washington state epidemiologist. "We don't want to be the first, obviously, and we're going to be careful and make sure that we're not missing human-to-human transmission."

Public Health Response

Public health officials are conducting thorough investigations to determine exactly how the patient became infected. The Washington State Department of Health is working with local health departments and the Washington State Department of Agriculture to complete exposure and animal health investigations.

So far, no other people in the state have been identified as having H5N5. The Centers for Disease Control and Prevention (CDC) has stated they are "monitoring this situation closely" and emphasized that "there is no information to suggest the risk to public health has increased as a result of this case."

A mixed backyard flock of domestic poultry that may have been exposed to wild birds. - Image from https://duckduckgo.com/?origin=funnel_home_website&t=h_&q=backyard+poultry+with+wild+birds+biosecurity+measurs&ia=images&iax=images&iai=https%3A%2F%2Fimage.slidesharecdn.com%2Fbiosecurityagri-fisheryppt-240520004805-3ab73546%2F85%2FBiosecurity-Measure-for-Poultry-farm-PPT-1-320.jpg

Context on Bird Flu in the US

This case comes after a period of increased bird flu activity in the United States. Washington state has had dozens of detections of avian flu in wild birds, waterfowl, and backyard poultry in recent weeks, mirroring a national spike in activity.

Since March 2024, when the USDA first identified a bird flu strain affecting millions of birds across the US, there have been at least 70 confirmed human cases of bird flu in the country. Most cases have been mild, with symptoms such as red eyes and fever, but at least one person has died from the infection—a Louisiana man in January 2025.

What This Means for the Public

Health officials stress that the risk to the general public remains low. Human-to-human transmission of avian flu has not been documented in any of the US cases, including this H5N5 instance.

"Two things for the public really to understand about this is that the risk to the general public is very low and we've never had human-to-human transmission," Dr. Lindquist reassured.

For those with backyard flocks or who handle birds, health officials recommend practicing good biosecurity measures, including limiting contact between domestic and wild birds, and monitoring poultry for signs of illness.