Washington confirms first avian influenza cases in dairy cattle

Washington state has confirmed its first cases of highly pathogenic avian influenza (HPAI) H5 clade 2.3.4.4b in dairy cattle. Two herds in Yakima County tested positive following clinical signs of illness, ending a period where over 7,000 surveillance tests in the state had returned negative results.

The U.S. Department of Agriculture (USDA) and the Washington State Department of Agriculture are conducting on-farm investigations and diagnostic testing. The affected farms have been placed under quarantine and have implemented strict biosecurity measures. While the national outbreak has affected dairy cattle in 19 states since March 2024, officials noted that the immediate risk to most households remains low and pasteurized milk is safe.

Health concerns are primarily directed toward farmworkers, veterinarians, and individuals consuming raw milk. The USDA maintains that its eradication strategy remains unchanged, emphasizing biosecurity protocols such as disinfecting vehicles, controlling visitor access, and cleaning equipment daily to prevent further spread.