First Human Case of New H5N5 Bird Flu Strain Detected in Washington

A Novel Strain Raises Questions About Bird Flu Transmission

Health officials in Washington state confirmed the first human case of H5N5 bird flu in the United States, marking a significant development in the ongoing avian influenza outbreak. This particular strain of the virus had previously only been detected in animals, never before in humans. The infected individual, an older adult with underlying health conditions, was hospitalized in early November with severe symptoms including high fever, confusion, and respiratory distress.

Understanding the H5N5 Threat

According to the Washington State Department of Health, the H5N5 strain belongs to the broader family of avian influenza viruses. While closely related to the more common H5N1 strain that has circulated globally for years, H5N5 represents a distinct genetic variant. This case is the 15th confirmed or probable human bird flu infection in Washington since 2022, but the first involving this specific subtype.

"This is an important scientific and epidemiologic development, but this new information does not change the public health response or guidance to the public." - Dr. Tao Sheng Kwan-Gett, State Health Officer

Investigation and Transmission Path

Public health officials are actively investigating how the patient contracted the virus. The individual owns a mixed backyard poultry flock that had contact with wild birds, with two backyard birds dying from illness weeks prior to human symptoms. Domestic or wild birds are considered the most likely source of exposure. No human-to-human transmission has been documented to date, and close contacts are being monitored.

Public Health Response and Risk Assessment

The Centers for Disease Control and Prevention (CDC) is monitoring the situation closely, emphasizing that the risk to the general public remains low. State epidemiologist Dr. Scott Lindquist reiterated: "We've never had human-to-human transmission... we don't want to be the first, and we're going to be careful and make sure we're not missing that." Health officials stress that most human cases occur after direct contact with infected animals, not through casual person-to-person contact.

Bird Flu Context in Washington and Beyond

This case comes amid continued bird flu activity across the United States. Since 2022, over 4.1 million birds have been infected in Washington alone, primarily in wild birds and commercial poultry. Nationally, approximately 70 human cases have been reported, with one confirmed death in Louisiana. The virus has increasingly spread to mammals, including dairy cows, though no livestock infections have been detected in Washington.

Safety Recommendations for the Public

Health officials issued specific guidance for residents:

• Backyard Flock Owners: Avoid contact with sick or dead birds; report illness to the Washington State Department of Agriculture (800-606-3056).
• Wildlife Contact: Report sick or dead wild animals to the Washington Department of Fish and Wildlife.
• Food Safety: Avoid consuming raw or undercooked animal products, including raw milk.
• High-Risk Individuals: Consider seasonal flu vaccination to reduce the risk of co-infection.

While this H5N5 case represents a notable virological milestone, public health authorities maintain that the current situation does not warrant widespread alarm. Continued surveillance and precautionary measures remain key to containing potential spread.