OLYMPIA – Oct. 26, 2026 – Washington State Department of Agriculture (WSDA) has confirmed a detection of highly pathogenic avian influenza (HPAI) H5N1 in a Benton County dairy herd. The virus was detected by the Washington Animal Disease Diagnostic Laboratory (WADDL) through routine surveillance, and the finding was confirmed by the USDA National Veterinary Services Laboratories (NVSL).
The dairy herd is under quarantine and has employed strict biosecurity measures. Veterinarians are working to treat sick cows. Pasteurized milk products remain safe for consumers, and milk supply shortages are not expected. WSDA urges dairy farmers statewide to report any clinical signs of illness to their veterinarian, including:
- Changes in milk appearance (thicker, often yellowish to brown)
- Decreased milk production
- Decline in feed intake
- Fever
- Respiratory symptoms
- Changes in manure
- Steep drop in rumination and rumen motility
If you notice any of these signs, isolate affected animals and contact your veterinarian and WSDA at 360-902-1878 or ahealth@agr.wa.gov. Most cattle affected by HPAI recover with supportive care with full herd recovery typically taking 4-6 weeks.
“Seeing the virus move to another county is disappointing but our dairy farmers are working hard to implement their biosecurity plans, share lessons learned and help each other get through this,” said Washington State Veterinarian Amber Itle, VMD, MS. This isn’t new for the country, but it is new for Washington. I’ve been in awe of how hard our veterinarians and dairy farmers work together every day to keep their cows healthy, keep their workers safe and keep operating despite all the uncertainty this virus brings with it. This detection was through routine surveillance enabling us to detect the virus before cows got sick. We hope this will help us to implement measures on farm to prevent transmission within or between other dairy or poultry facilities.”
HPAI can spread between dairy cattle through infected animals and contaminated milk, equipment, vehicles, clothing, footwear and other materials or people that move between farms. Wild birds can also carry HPAI, but they are not considered the primary source of spread of the virus that affects dairy herds.
Poultry are also highly susceptible to HPAI. Other states have reported infections in commercial and backyard poultry flocks near dairy farms affected by H5N1. Poultry owners, including those who keep backyard flocks, should remain vigilant for signs of illness and practice strong biosecurity to help reduce the risk of infection.
Protecting your herd
Follow your biosecurity plan or write one with your veterinarian to incorporate enhanced biosecurity measures:
- Limit lactating animal movement between farms unless necessary
- Do not share equipment, vehicles or workers
- Clean and disinfect footwear before entering livestock areas
- Limit visitors and require clean clothing and footwear
- Isolate new animals for 30 days before introducing them to your herd
- Separate sick or suspect cattle from healthy cattle when possible
- Practice good milking hygiene and keep milk from sick or suspect cattle out of the bulk tank
- Restrict access to open water used by wild waterfowl
- Employ wildlife, wild bird, rodent and vector control
- Minimize contact with wild birds and other animals, particularly around cattle, feed, water and equipment
Dairy product safety
Pasteurization inactivates viruses and bacteria in milk, including HPAI virus, helping ensure the safety of the dairy supply. Pasteurized milk and dairy products sold in grocery stores remain safe for consumers, and milk shortages are not expected. Look for “pasteurized” or “ultra-pasteurized” on the label.
Infected cows can shed the virus in their milk, making raw milk, cheese and other raw unpasteurized dairy products unsafe for consumption. Health officials advise consumers to avoid raw milk and raw dairy products, particularly those from infected or untested farms, because they may contain harmful viruses and bacteria.
Do not allow your pets to consume raw milk or other dairy products, or raw foods such as raw meat or dead birds.
Human health and safety
The Centers for Disease Control and Prevention (CDC) and the Washington State Department of Health (DOH) currently consider the risk to the public from avian influenza to be low. However, people who work with or have recreational contact with infected birds, cattle or other potentially infected domestic or wild animals are at higher risk and should take precautions, including wearing personal protective equipment (PPE) such as gloves, masks, eye protection and fluid-resistant coveralls or other outerwear. Additional resources
Media note: WSDA will issue a news release for each new county with confirmed HPAI in cattle. Subsequent detections in previously announced counties will be posted online.
