Lead
Washington state health officials confirmed in early November that an older adult with underlying conditions tested positive for H5N5 avian influenza, marking the first human bird flu case in the U.S. in nine months. The patient was hospitalized after developing high fever, confusion and respiratory distress and is under medical care. Testing identified H5N5, a subtype previously seen in animals but not previously documented in humans. Authorities say the risk to the general public is low while an investigation into exposure pathways continues.
Key Takeaways
- Washington state reported a human H5N5 infection in early November; the patient is an older adult with preexisting health conditions and was hospitalized.
- Laboratory testing confirmed the strain as H5N5, a subtype previously reported in animals but not before in humans.
- Health officials report no evidence of sustained human-to-human transmission; public risk is considered low at this time.
- The patient keeps a mixed backyard flock that had contact with wild birds, making poultry or wild birds the likely exposure source under investigation.
- The case is the first human bird flu case in Washington this year and the first confirmed U.S. human case in nine months.
- Federal data show at least 70 confirmed human infections in the U.S. earlier in 2024, mostly tied to animal exposures; one human death was reported in January.
- Public health teams are tracing close contacts and coordinating with local providers to monitor for additional cases.
Background
Avian influenza viruses have circulated in bird populations for decades, but in recent years some strains have crossed into a wider range of mammal species. In early 2024 USDA and animal health partners reported that an avian influenza strain linked to mass poultry illness had been detected in several mammal species, prompting expanded surveillance. State and federal authorities subsequently documented animal infections and isolated events of human exposure linked to agricultural work and close contact with infected animals.
Human infections in the U.S. earlier in 2024 were largely associated with direct contact with infected livestock, poultry or culling operations; most were mild, presenting with conjunctivitis or fever. A small number progressed to more serious illness, and a death was confirmed in January in an older patient with underlying conditions. These developments have led public health agencies to increase testing and contact tracing around animal-related exposure events.
Main Event
Washington state announced that an older adult living with underlying health conditions developed severe symptoms in early November and was admitted to hospital. The Washington State Department of Health reported that testing identified H5N5, a subtype not previously confirmed in humans. Officials withheld personally identifiable details about the patient, including name, precise age and sex, citing privacy protections and ongoing investigation needs.
Investigators are focusing on the patient s backyard flock of mixed domestic poultry, which had known exposure to wild birds. State epidemiologists say the domestic birds or wild birds are the most plausible sources, and samples from animals and the environment are being collected and analyzed to establish a link. Public health teams are also identifying and notifying people who had close contact with the patient to monitor for symptoms and offer testing as needed.
The Washington State Department of Health emphasized that the case is being treated as an isolated zoonotic spillover while authorities search for any evidence of onward human transmission. Hospital infection control measures and local health department protocols are in effect to limit any potential spread. Coordination with federal agencies, including CDC and USDA, is ongoing to align laboratory testing and risk assessment steps.
Analysis & Implications
The detection of H5N5 in a human for the first time raises questions about viral evolution and the boundaries between animal and human infections. While single zoonotic spillovers are not uncommon, they do provide opportunities for viruses to adapt; public health experts therefore pay close attention to the genetic sequences and clinical patterns. Sequencing results and comparative analysis with animal isolates will be essential to determine whether the virus shows any markers associated with increased human infectivity.
From a public-health perspective, the immediate implication is increased surveillance around people with animal exposures, particularly agricultural workers and backyard flock owners. The majority of recent U.S. human cases were linked to contact with infected cattle or poultry, and most produced mild illness, but serious outcomes have occurred in people with comorbidities. Targeted outreach, testing availability and protective measures for at-risk groups remain high priorities.
Economically and operationally, additional human infections tied to agricultural settings can complicate outbreak control in animal populations and affect supply chains. Federal and state animal health responses aim to limit further spread among birds and mammals, reducing the reservoir for spillover into humans. Internationally, a novel human H5N5 detection may prompt updates to travel health guidance and cross-border surveillance coordination, though current evidence does not suggest community transmission.
Comparison & Data
| Metric | Count |
|---|---|
| Confirmed U.S. human cases prior to Washington report | 70 |
| Washington H5N5 human case documented | 1 |
| U.S. human cases including Washington case | 71+ |
| First U.S. human bird flu death (Jan 2024) | 1 |
The table summarizes counts reported by federal and state authorities: at least 70 confirmed human infections were recorded earlier in 2024, mostly linked to animal exposures, with one human death in January. The Washington case adds a new subtype, H5N5, to the list of avian influenza subtypes detected in people in the U.S. Ongoing laboratory work will refine these figures if additional cases are confirmed or reclassifications occur.
Reactions & Quotes
State health officials sought to reassure the public while indicating the investigation remains active.
Two things for the public to understand are that the risk to the general public is very low and we have never had human-to-human transmission. We do not want to be the first, and we are taking steps to ensure we are not missing anything.
Dr. Scott Lindquist, State Epidemiologist, Washington State Department of Health
The Washington State Department of Health also stressed routine public health actions are underway to trace contacts and test potential exposures.
There is currently no identified risk to the general public, and we are coordinating with local health departments and health care facilities to support the investigation.
Washington State Department of Health (official statement)
Unconfirmed
- Whether the household poultry are laboratory-confirmed positive for H5N5 remains pending public release of animal test results.
- No evidence of sustained human-to-human transmission has been found, but genomic and epidemiological analyses are ongoing to confirm that status.
- The precise route of the patient’s exposure, including whether contact was direct with infected birds or via environmental contamination, has not yet been determined.
Bottom Line
The Washington H5N5 case appears to be a zoonotic spillover that public health authorities are treating with caution but without immediate alarm. Current evidence and official statements indicate the risk to the general public is low and there is no confirmed human-to-human spread, yet enhanced surveillance and contact tracing are necessary to confirm those assessments.
For people with direct exposure to poultry or livestock, standard precautions and prompt testing for symptoms remain the primary safeguards. Authorities will continue laboratory sequencing and coordinated federal-state response activities; those results will shape any changes to guidance or control measures in the coming days and weeks.
Sources
- ABC News — media report summarizing the Washington case and health officials remarks
- Centers for Disease Control and Prevention — federal public health guidance on avian influenza in humans (official agency)
- Washington State Department of Health — state health agency announcements and statements (official)
- USDA APHIS: Avian Influenza — federal animal health information and notices (official agency)