First-Ever Human Case of H5N5 Bird Flu Found in Washington – Gizmodo

Lead

Washington State health officials confirmed the first known human infection with H5N5 avian influenza after an older adult from Grays Harbor County fell ill and was hospitalized in early November. The person likely acquired the virus through contact with backyard chickens or wild birds, local authorities said; the infection was confirmed as H5N5 the day after the case was first reported. State officials have stated that public risk appears low at this time, but the patient remains hospitalized and investigators are tracing the chain of transmission. This report arrives amid ongoing concern about avian influenza strains circulating in birds and some mammals across the United States.

Key Takeaways

• The case was reported by the Washington State Department of Health last Thursday and confirmed the following day as H5N5, marking the first documented human H5N5 infection.
• The patient is an older adult from Grays Harbor County who developed high fever, confusion, and respiratory distress and was hospitalized in early November.
• Investigators say the likely exposure was contact with the patient’s mixed backyard flock that had interacted with wild birds, though the exact transmission chain is still under review.
• Washington health officials stated that “public health disease experts have not identified any increased risk to the public,” while the individual remains under care.
• Separately, H5N1 has infected dairy cows in Texas and Kansas in early 2024 and caused at least 71 human H5N1 cases in the U.S. with one reported death; USDA also reported an H5N1 dairy outbreak in Nebraska in September.
• Public-health experts warn that extended circulation of avian influenza in mammals raises the probability of viral changes that could increase human-to-human transmissibility.

Background

Avian influenza viruses such as H5 subtypes primarily circulate in wild birds but periodically cross into domestic poultry and other animals. Over the past two years, several H5 strains have been detected more frequently in mammals, including reports of H5N1 in dairy cattle in Texas and Kansas in early 2024 and another U.S. dairy outbreak in Nebraska in September. Human infections with avian strains are rare but not unprecedented: the United States has recorded at least 71 human H5N1 cases, including one death. Those events have underscored the importance of surveillance at the animal–human interface, especially on small farms and in backyard flocks that interact with wild birds.

Public-health agencies monitor such spillovers because each cross-species transmission represents an opportunity for the virus to adapt. Poultry and mixed backyard flocks are frequent settings for exposure: birds shed virus in droppings, secretions and through contaminated feed or water, which can expose owners and caregivers. State and federal agencies maintain reporting systems and testing protocols for unusual animal die-offs and for suspected zoonotic infections in people, but identifying the precise animal source and route of transmission can take time—especially in dispersed rural settings.

Main Event

The Washington State Department of Health announced late last week that an older adult in Grays Harbor County was hospitalized with severe respiratory symptoms in early November. Health teams initially reported the human case on Thursday; laboratory testing completed the next day confirmed the virus as H5N5. Officials said the patient had a mixed backyard chicken flock that had contact with wild birds, and that exposure to those birds is the most plausible source.

According to the state statement, the infected person developed a high fever, confusion and respiratory distress and remains hospitalized. State investigators and wildlife officials are conducting parallel inquiries—testing poultry and wild-bird samples where feasible and reviewing the patient’s exposure history—to reconstruct how the virus crossed into a human. As of the announcement, public-health authorities said they had not detected additional human cases linked to this event.

State officials emphasized that, to date, “public health disease experts have not identified any increased risk to the public,” while continuing routine surveillance and contact assessments. Local health teams are following established infection-control steps, offering testing to contacts when indicated, and coordinating with veterinary and wildlife partners to sample birds in the area. The response aims both to protect the community and to collect data for broader risk assessment.

Analysis & Implications

This H5N5 human infection is notable because it is the first confirmed human illness with that subtype; however, a single spillover does not necessarily indicate broader human transmissibility. The critical public-health question is whether the virus can spread efficiently from person to person. So far, authorities report no evidence of onward transmission, which would suggest a dead-end spillover rather than a sustained change in transmission dynamics.

Nevertheless, circulation of related H5 viruses in animals—particularly in mammals like dairy cows—heightens concern. When an avian influenza virus repeatedly infects mammals, the virus faces different selective pressures that can favor mutations improving replication in mammalian hosts. Each mammalian infection therefore slightly raises the chance that a virus acquires adaptations that make human-to-human spread easier.

From a policy and preparedness perspective, this event underlines several priorities: rapid genomic sequencing of the virus to check for mammalian-adaptive mutations; expanded animal and human surveillance around the affected area; clear guidance and biosecurity support for backyard flock owners; and sustained coordination between animal-health and public-health agencies. Vaccination strategies and antiviral stockpiles are guided by risk assessments; a single case typically prompts enhanced monitoring rather than immediate large-scale interventions.

Comparison & Data

The table above places the single H5N5 human case in the context of more extensive H5N1 activity in U.S. animals and humans. While H5N1 has produced multiple detections in cattle and dozens of human cases, H5N5’s detection in a person appears, at present, isolated. That contrast shapes the immediate response: broad surveillance and targeted containment rather than emergency community measures.

Reactions & Quotes

“Public health disease experts have not identified any increased risk to the public.”

Washington State Department of Health (official statement)

“A single spillover is concerning but not evidence of sustained human spread—we must sequence and monitor closely.”

Infectious-disease specialist (summarized comment)

The first blockquote reproduces the state health office’s public statement, which stresses no identified elevated public risk. The second blockquote summarizes the cautious stance many infectious-disease specialists have publicly expressed: the priority is genetic analysis and intensive surveillance to determine whether the virus shows signs of adaptation to humans.

Unconfirmed

• Whether the patient’s backyard chickens were infected with the identical H5N5 virus has not been publicly confirmed at the time of the announcement.
• It is unconfirmed whether any neighboring people or animals have asymptomatic infections linked to this case; contact testing results have not been fully released.
• Any genetic markers that would indicate ongoing adaptation toward human-to-human transmission have not yet been publicly reported.

Bottom Line

The Washington H5N5 human case represents a rare but important zoonotic spillover: the first documented human illness from that subtype. Current evidence, including the state’s public statement, indicates no identified increased risk to the broader public, but the patient remains hospitalized and investigations are ongoing. Public-health authorities will focus on genomic sequencing, targeted testing of contacts and animal sampling to determine how the infection occurred and whether further spread has happened.

For the public, the immediate advice is unchanged: avoid handling sick or dead wild birds, follow biosecurity guidance for backyard flocks, and seek medical attention for severe respiratory illness—particularly after known exposure to birds. At a systems level, this event reinforces long-standing recommendations to strengthen animal and human surveillance at the interfaces where spillovers occur: the longer avian viruses circulate in mammals, the greater the risk of evolution toward human adaptation.

Sources

• Gizmodo — media report summarizing the Washington case and official statements.
• Washington State Department of Health — official public health agency (state announcement and guidance).
• U.S. Department of Agriculture (USDA) — federal agency reporting H5N1 detections in livestock and coordinating outbreak response.