Washington State Confirms 3rd Dairy Herd Infected With H5N1

 

#19,377

Since 2024 Washington State has seen scores of HPAI outbreaks in poultry, and more than a dozen confirmed and probable human infections related to exposure to poultry and/or wild birds. 

Eight days ago (Oct 9th), however, their WSDA confirmed their first detection of avian influenza in dairy cattle (herds=2). 

Yesterday, Washington State reported their first (reportedly mild) human infection with H5N1 derived from an (unspecified) dairy exposure.  

Details on this latest case remain scant, and yesterday's CDC FluView Report (wk 40) did not include this case, reporting: 

Novel Influenza A Virus Infections

No new confirmed human infections with a novel influenza virus were reported to CDC as of October 14, 2026.

The CDC's A(H5) Bird Flu: Current Situation webpage was updated on the 15th, showing the latest dairy-associated case (see below). Presumably we'll get an update in next week's FluView. 

In the meantime, the USDA has added a 3rd dairy herd from Washington State to their HPAI positive list.  Other than the one-line entry (below), I've seen no other information on this outbreak. 

Thus far, the genotype of the virus infecting Washington Cattle (likely either B3.13 or D1.1)  - and the recent human case - have not been announced, nor do we know exactly what kind of exposure the recent human case had. 

For more than 2 years the CDC, the USDA, and state agricultural agencies have urged the use of PPEs for farm workers, and anyone else who might be exposed to infected livestock or birds. 

While recommended, the use of PPEs has been suboptimal, particularly on farms and ranches. They can be hot, cumbersome to wear, and difficult to don and doff properly. (see MMWR: PPE Use by Dairy Farmworkers Exposed to Cows Infected with HPAI A(H5N1) Viruses — Colorado, 2024).

Over the past 30 days the number of infected backyard flocks vs. commercial flocks has run nearly 2 to 1, and over the course of the past 4+ years the number of backyard flock (n=1227) outbreaks have exceeded commercial outbreaks (n=1048). 

Although the risks of infection are believed low, we've already seen at least two fatalities (here, and here) in the United States from H5Nx following `. . . exposure to a combination of a non-commercial backyard flock and wild birds.' 

The APPA estimates `Eleven (11) million U.S. households own backyard chickens (a 28% increase from 2023)', yet a recent survey (see MMWR: Knowledge, Attitudes, and Practices Regarding Avian Influenza Among Owners of Backyard Flocks) found significant gaps in their knowledge of dealing with avian flu. 

Although it is too early to predict what kind of avian flu season we will see this fall and winter - or whether any new genotypes will be added to the mix - we are already seeing signs of increased activity.  

Which means, if you raise backyard birds, frequent live markets, or have outdoor pets, now would be a good time to familiarize yourselves with the risks of avian flu, and the things you can do to reduce those risks to you and your families.

UF/IFAS Extension: What Backyard Flock Owners Need to Know about Bird Flu (Influenza H5N1)

 

CDC Guidance on Bird Flu in Pets and Other Animals

 

Washington State Confirms Human Avian Flu Infection

 #19,376

A week ago Washington state confirmed their first detection of avian influenza in dairy cattle, and overnight it was announced by the Yakima County Health District that a local resident who was exposed to infected dairy cows has tested positive for the virus.

There is still a lot we don't know about this case, hopefully the CDC will provide more details later today in their weekly FluView.   

The full press release follows.  I'll update this report as more information becomes available.

Yakima County Resident Tests Positive for Avian Influenza

We Are Public Health

Media Release

For immediate release: October 15, 2026

Contact: Stephanie Ruiz, Communications Specialist (509) 941-7364

Yakima County Resident Tests Positive for Avian Influenza

Yakima, WA- The Yakima Health District (YHD), in coordination with the Washington State Department of Health (DOH), is reporting a confirmed case of avian influenza in a Yakima County resident who was exposed to infected dairy cattle at a Yakima County dairy. The resident has not experienced severe illness or been hospitalized. The individual is isolating at home.

The risk of avian influenza infection to the general public remains low. People at greater risk include dairy workers and others who have close or prolonged contact with infected animals or environments contaminated with the virus. Transmission of avian influenza between humans is extremely rare and has never been documented in the United States. To ensure that human-to-human spread is not occurring, public health officials are contacting anyone who has been in close contact with the patient to monitor for symptoms.

Since the initial detection of Highly Pathogenic Avian Influenza (HPAI) H5N1 in Yakima County, YHD has been in contact with the impacted dairies to protect the health of people who may be exposed to infected cattle.

YHD continues to coordinate with state and federal public health partners to provide guidance and resources to help protect exposed individuals. This includes providing tests for exposed individuals who develop symptoms to support prompt diagnosis and appropriate medical care. YHD is working with partners to connect affected dairies with appropriate personal protective equipment (PPE) for their workers.
About Avian Influenza

Avian influenza, commonly called bird flu, is caused by influenza viruses that primarily circulate among wild birds but can also infect other animals, including poultry and dairy cattle. On rare occasions, these viruses infect people and cause illness.

Most human infections with avian influenza have occurred following close or prolonged contact with infected animals or environments contaminated with the virus. People can become infected when virus enters their eyes, nose, or mouth. The severity of illness can range from mild to serious and potentially life-threatening.

Public Health Recommendations

The risk of avian influenza infection to the general public is low. However, people who work with or have contact with potentially infected animals are at higher risk and should follow workplace safety guidance and use recommended personal protective equipment. Residents should avoid touching sick or dead animals, animal waste, and surfaces that may be contaminated.

Pasteurized milk and dairy products remain safe to consume. Pasteurization inactivates avian influenza virus and other harmful pathogens. People should avoid raw milk and unpasteurized dairy products because they may contain harmful germs, including avian influenza. Do not feed pets raw milk, unpasteurized dairy products, or raw meat, including raw pet foods.

It is especially important that people who may have exposure to sick animals get a seasonal flu vaccine. While the seasonal flu vaccine will not prevent bird flu infection, it reduces the risk of becoming sick with both human and avian influenza viruses at the same time. Seasonal flu vaccine is recommended for everyone six months and older.

Symptoms of avian influenza in people can include eye redness or irritation, fever or feeling feverish, cough, sore throat, runny or stuffy nose, muscle or body aches, headache, and fatigue. More severe illness can occur.

If you work on a dairy farm and develop symptoms after potential exposure to infected cattle, contact your healthcare provider or the Yakima Health District at (509) 249-6541.
Reporting Sick or Dead Animals

Domestic Birds:Report sick/dead domestic birds using the online form, or call the Washington State Department of Agriculture’s Avian Health Program: 1-800-606-3056. Visit Avian Influenza | Washington State Department of Agriculture for more information about how to protect backyard flocks.

Wild Birds:Use an online form to report sick/dead wild birds suspected of avian influenza to the Washington Department of Fish & Wildlife.

Livestock: To report sick livestock, isolate affected animals and contact your veterinarian and WSDA at 360-902-1878 or email ahealth@agr.wa.gov.

Quote

“We are working closely with our public health partners to follow up with people who have been in close contact with this individual. We want to make sure they know what symptoms to watch for and can access testing and treatment if needed.” -Dr. Dave Atteberry, Health Officer, Yakima Health District 

Australia: H5 Bird Flu Reported on Macquarie Island

 
Macquarie Island - Credit Wikipedia

#19,375

Six weeks ago Australia announced they would soon be withdrawing their research team from remote Macquarie Island - located about halfway between Australia and Antarctica - over concerns that bird flu would arrive and decimate that island's wildlife much as it did on Heard Island last year. 

Citing `psychosocial risks' to personnel who were stationed there, DCCEEW decided to temporarily extract all personnel from the research station.

Today, Guy Barnett, Tasmanian Minister for Environment and Climate Change, announced that the evacuated research team brought back with them samples from the island which have tested positive for H5 bird flu.

15 October 2026

Guy Barnett, Minister for Environment and Climate Change

H5 bird flu has been detected in a Southern elephant seal and a kelp gull on Macquarie Island.

Samples collected from a Southern elephant seal and a kelp gull on Macquarie Island were returned with island personnel and subsequently tested returning a positive result for H5 bird flu.

This is the first recorded detection in a marine mammal in Tasmania.

As bird flu continues to be detected in Tasmania, members of the public are encouraged to continue reporting sick or dead birds. Reports play an important role in helping authorities detect and respond to potential cases.

Avoid contact with sick or dead birds and report sightings through https://nre.tas.gov.au/reportbirdflu or by calling the Emergency Animal Disease Hotline on 1800 675 888.

The Department of Natural Resources and Environment Tasmania provides regular public updates through media releases. The latest testing and surveillance figures are updated on the department's website.

More information is available at www.nre.tas.gov.au/BirdFlu.

While there are no reports of mass casualties on Macquarie Island, four months ago, in Preprint: Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island, we saw that the carnage from the Heard Island outbreak was worse than originally feared, with 76% mortality among Elephant Seal pups.

Meanwhile, Australia's bird flu count continues to rise, with the latest figure showing more than 700 confirmed events, and in excess of 63,000 hotline reports by the public. 

 

Nevada Dept of Wildlife Warns on HPAI in Multiple Flocks of Wild Geese

 
Credit Wikipedia

#19,374

We've a press release from Nevada's Department of Wildlife (NDOW) - posted late yesterday - warning the public that `multiple flocks' of wild geese in the Reno/Sparks region have tested positive for HPAI.

While there aren't a lot of specifics offered in this statement (precisely where, how many flocks, which subtype and/or genotype, etc.), they are urging the public to be careful around sick or dead birds, and how to report any findings. 

Local media, for now, are repeating the NDOW announcement, and adding little additional detail. First, the Nevada announcement, after which I'll have a bit more.

Nevada State Agencies Respond To Bird Flu Outbreak In Geese

The Nevada Department of Wildlife (NDOW) in coordination with the Nevada Department of Agriculture, and Nevada Division of Public and Behavioral Health have confirmed an outbreak of Highly Pathogenic Avian Influenza (HPAI) in multiple flocks of geese in the Reno/Sparks region. The public can help by identifying infected geese, notifying the proper officials and disposing geese safely to reduce transmission to other birds and species. HPAI is a highly contagious virus that can infect poultry, wild waterfowl, and in rare cases can infect livestock and humans.

HPAI symptoms in birds include:

• Sneezing, coughing, eye & nasal discharge, swelling or fluid accumulating around one or both eyes.
• Abnormal position of head or neck, poor balance and coordination, and/or circling.
• A buildup of fluid in the bird’s legs and patchy redness of the skin.
• Diarrhea and green discoloration of the feces.
• Weakness, lethargy, depression.
• Sudden death.

If the public encounters a dead goose, they are encouraged to:

• Notify the landowner responsible. For geese found on City or County Parks, please contact them for removal. City of Reno Parks can be reached at (775) 334-2270; Washoe County Parks phone is (775) 828-6612.
• Dispose waterfowl on your own property by double bagging it and placing it in municipal waste. Be sure to wear gloves, an N95 mask, and eye protection.
• If you encounter a dead goose and have poultry, change your clothes and shoes afterwards.

If the public encounters a sick goose, they are encouraged to:

• Leave the goose alone and contact NDOW at (775) 688-1500 to report the location of the goose. If this is on your property, someone will contact you as soon as possible.
• Keep pets and children away.
• If the public encounters a sick goose, they are encouraged to:
• Leave the goose alone and contact NDOW at (775) 688-1500 to report the location of the goose. If this is on your property, someone will contact you as soon as possible.
• Keep pets and children away.

If you have domestic birds, especially backyard poultry:

• Keep poultry in secure enclosures away from wild birds and waterfowl.
• Wear dedicated clothing and footwear when caring for poultry.
• Clean and disinfect tools and equipment after use.
• Store poultry feed securely and avoid placing wild bird feeders near poultry areas.
• Watch for unusual behavior, signs of illness or unexpected deaths in your flock.
• Avoid touching or handling sick or dead wild birds. Use gloves and protective gear when necessary.
• Contact a veterinarian if birds appear sick and report high mortality rates among domestic poultry to the NDA at diseasereporting@agri.nv.gov.

HPAI rarely spreads to livestock and humans. In wild waterfowl populations, it usually displays without any signs of illness and low mortality rates. It can cause mortality in some species of geese, raptors, and game birds. Poultry are highly susceptible to HPAI and mortality rates may exceed 90%. When HPAI does spread to humans, symptoms may include fever, cough, sore throat, difficulty breathing, eye tearing/irritation/redness, headaches, runny/stuffy nose, body aches, and/or diarrhea/vomiting. Transmission to humans may occur from contact with infected or potentially infected animals, animal carcasses, or surfaces contaminated with animal excretions without using proper protective clothing/equipment. If you or your family have been exposed to a sick/dead bird and develop any of these symptoms, contact your healthcare provider and let them know about your animal exposure.

Since H5Nx established itself in North America in 2021-2022, each fall we've seen an increase in HPAI as southbound migratory birds leave their high latitude roosting areas for warmer climes.

The $64 question (see 2025's H5Nx: Reassort & Repeat) is whether this year's bird flu will be a repeat of last year's strain (predominantly D1.1), or whether new genotypes have emerged. It can sometimes takes months before that question can be answered. 

Although this advisory is specifically for the Reno/Sparks area, HPAI can turn up just about anywhere in North America this time of year.  

Which means, if you raise backyard birds, frequent live markets, or have outdoor pets, now is a good time to familiarize yourselves with the risks of avian flu, and the things you can do to reduce those risks.

UF/IFAS Extension: What Backyard Flock Owners Need to Know about Bird Flu (Influenza H5N1)

 

CDC Guidance on Bird Flu in Pets and Other Animals

Saying Goodbye to An Infectious Disease Reporting Legend

 

#19,373

I've lost count how many times I've featured a Helen Branswell story in this blog, but it must run into the hundreds. She was, quite simply, one of the most prolific and capable infectious disease reporters in the world. 

Her loss, and legacy, are detailed in the STAT obituary, published yesterday. 

While I never got to meet Helen, we corresponded a number of times. Sometimes to share information, other times less formally.  She was exceptionally kind to this humble blogger, and I am saddened  - and Flublogia is diminished - by her passing.

BMC Public Health: 2018–2025 Serological study on avian influenza among occupationally exposed populations in the Poyang Lake area

 

#19,372

In 2025 a Chinese research study reported on testing environmental samples collected from southern and northern Chinese live poultry markets during 2019–2023 for evidence of avian influenza viruses. 

They examined > 64,000 samples, and found the incidence of H5, H7, and H9 influenza A detections substantially higher in southern provinces. Jiangxi, Yunnan, and Guangxi showed the highest level of environmental contamination, with positive rates of  82.3%, 49.41%, and 45.47%. 

Today we have a research study into the seroprevalence of  influenza A viruses among occupationally exposed individuals in the Poyang Lake area - located in Jiangxi province - which reported the highest environmental readings in the above report. 

Poyang Lake is the largest freshwater lake in China, and lies beneath the East Asian-Australasian Flyway. Poyang Lake also provides a habitat for more than a million migratory birds, including endangered Siberian cranes. 

Researchers tested blood from 2,437 poultry-exposed people around Poyang Lake, China, from 2018 to 2025 using hemagglutination inhibition assays. Predefined HI positivity thresholds were ≥ 1:20 for H3N8, H5N8, H5N1, H7N9, and H10N3 and ≥ 1:40 for H5N6 and H9N2.

Participants were mostly backyard poultry keepers and their households (90.3%) and live-market workers (9.7%). The median age was 62.  

While HI reactivity can't conclusively prove that an individual was previously infected by a specific virus (there's always a possibility of cross-reactivity with other viruses), it does suggest that a subject might have had a mild, or subclinical, infection with that virus sometime in the past. 

Admittedly, it would have been nice to see confirmatory Microneutralization (MN) testing of these samples, but they are considerably more resource intensive and technically demanding. HI titers also tend to fall faster than MN titers, and may drop below the positive cutoff within the span of a couple of years, which means that HI assays may miss older infections.  

With those limitations in mind, the authors found samples meeting the study's HI thresholds were 4.43% for H5N6 and 4.39% for H9N2, with lower rates for H7N9 (2.74%), H3N8 (1.44%), H5N8 (1.27%) and H10N3 (0.26%). 

First the link and abstract from the open-access study, after which I'll return with a postscript:

2018–2025 Serological study on avian influenza among occupationally exposed populations in the Poyang Lake area — the region with the highest environmental surveillance positive rate in China

Research Open access
Published: 14 October 2026 Cite this article
 
Download PDF
 
Chuang Nie, Yawei Li,Wenjing Xie, Ke Qian, Ting Xu, Fenglan He, Zhiqiang Deng, Wanting Wei, Yujie Hou, Xiang Tu, Tianxin Xiang & Wentao Song

We’re sharing this article early to provide faster access to peer-reviewed, accepted research. It is citable and carries a permanent DOI. This version is subject to further edits and will be replaced automatically by the final Version of Record. All legal disclaimers apply.

Abstract

Background

An avian influenza virus positivity rate as high as 82.3% has been reported in Jiangxi Province, China, underscoring this region as a potential hotspot for avian influenza virus circulation. As a crucial hub for migratory birds and a region where wild birds, domestic poultry, and humans frequently overlap, Poyang Lake provides favorable ecological conditions for cross-species transmission of avian influenza viruses. This study aimed to describe the seroprevalence of antibodies against selected avian influenza virus subtypes among occupationally exposed populations at surveillance sites around Poyang Lake from 2018 to 2025, and to provide data to inform ongoing surveillance and risk assessment.

Methods

A cross-sectional serological surveillance was conducted annually during winter and spring from 2018 to 2025 in Nanchang County (Nanchang) and Duchang and Wuning Counties (Jiujiang), Jiangxi Province. Serum samples were collected from occupationally exposed individuals, including backyard poultry keepers and their household members and live poultry market workers with direct poultry contact.

Hemagglutination inhibition assays were performed by the National Influenza Center to assess antibody reactivity against the test antigens representing H5N6, H9N2, H7N9, H3N8, H10N3, H5N8, and H5N1. Predefined HI positivity thresholds were ≥ 1:20 for H3N8, H5N8, H5N1, H7N9, and H10N3 and ≥ 1:40 for H5N6 and H9N2.

Results

A total of 2,437 valid serum samples were analyzed (1,599 from Jiujiang and 838 from Nanchang). Overall, 108 samples (4.43%) met the predefined HI positivity threshold for H5N6, and 107 (4.39%) met the threshold for H9N2. During 2018–2020, 25 of 914 samples (2.74%) met the threshold for H7N9.

During 2021–2025, 22 of 1,523 samples (1.44%) met the threshold for H3N8, including 9 of 100 samples (9.00%) collected in Nanchang in the 2024 surveillance year. Four of 1,523 samples (0.26%) met the threshold for H10N3; all four were from Jiujiang in the 2024 surveillance year. Four of 314 samples (1.27%) met the threshold for H5N8 in 2020. None of the 600 samples tested for H5N1 in the 2024 and 2025 surveillance years met the predefined threshold.

Conclusions

HI antibody reactivity varied across subtypes, surveillance locations, and years among occupationally exposed participants around Poyang Lake. The H3N8 finding in Nanchang and the H10N3 finding in Jiujiang in the 2024 surveillance year warrant further investigation. H5N6 peaks in Jiujiang in 2021 and in Nanchang in 2022; H9N2 peaks in 2021 in Jiujiang and 2023 in Nanchang. HI reactivity alone does not establish subtype-specific human infection or local virus circulation. Continued serological surveillance, interpreted alongside poultry and environmental virological data, may inform risk assessment.

        (Continue . . . ) 

We've previously looked at a number of human seroprevalence studies which have also suggested more human spillovers occur than have been reported, including:

• 2024's Nature Preprint: Serological Analysis in Humans in Malaysian Borneo Suggests Prior Exposure to H5 Avian Influenza despite no human  infections reported in the region. 

• 2018's J. Infect & Public Health: High Seroprevalence Of Avian Influenza H9 Among Poultry Professionals In Pakistan which found > 50% of 332 participants tested showed reactivity to H9.

• 2016's JID: High Seroprevalence Of H5N1 Antibodies In Indonesian Poultry Workers found 84% of sera tested positive

• In 2012, in H5N1 Seroprevalence Among Jiangsu Province Poultry Workers, we saw a study that found across three locations tested (Gaochun, Jianhu and Gaoyou counties) the percentage of workers testing positive ranged from zero (Gaochun) to 5.38% (95%CI, 2.19%–10.78%) in Gaoyou.

The good news is, this strongly suggests the 50% CFR (Case fatality rate) of H5N1 is badly overstated, since many mild infections are never counted.  

Conversely, it also suggests that novel flu infections may occur far more often than previously thought, which increases the risks of viral adaptation to a human host, and provides additional opportunities for novel/seasonal coinfection, which could lead to a reassortment. 

Either way, this is a reminder that a lot more goes on with the evolution and spread of novel flu viruses than our limited surveillance might suggest.