What is H5N5 avian influenza and is it serious?

H5N5 is a high pathogenicity avian influenza virus that infects birds. It can cause severe illness in humans, as evidenced by the first confirmed human case in Washington state which resulted in a fatality.

How did the H5N5 virus infect a human in Washington?

The exact source is unconfirmed, but the patient kept poultry exposed to wild birds, suggesting this as a likely transmission route. This is the first documented instance of H5N5 infecting a human.

Should people be worried about H5N5 bird flu spreading?

While scientists are monitoring for human-to-human transmission, the current risk to the wider human population is considered low. Most avian influenza infections in humans are isolated events.

Home / Health / First Human H5N5 Bird Flu Case Confirmed

First Human H5N5 Bird Flu Case Confirmed

30 Nov, 2025

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Summary

First human infection of H5N5 avian influenza confirmed.
The patient in Washington state sadly died from the virus.
H5N5 is a high pathogenicity bird flu strain found in wild birds.

First Human H5N5 Bird Flu Case Confirmed

A groundbreaking event in public health has occurred with the confirmation of the first human infection by an H5N5 avian influenza virus. The case, identified in Grays Harbor, Washington, involved an elderly individual with pre-existing health issues who developed severe flu-like symptoms, leading to hospitalization and eventual death. This marks a significant, albeit tragic, step in understanding the transmissibility of bird flu strains.

The H5N5 virus is classified as a high pathogenicity avian influenza, meaning it can cause severe illness in poultry and other birds. While H5N1 has been more widely reported, this H5N5 strain exhibits distinct genetic characteristics. The infected individual maintained a flock of backyard poultry, suggesting a potential link to wild birds, a known reservoir for H5N5.

Public health officials emphasize that while this case is alarming, the risk of widespread human infection from H5N5 remains low. There are currently no indications of human-to-human transmission. However, the incident underscores the ongoing need for vigilant surveillance of avian influenza viruses, especially as they continue to circulate in wild bird populations globally.