H5N1 Bird Flu Hits Washington Dairy Cattle for the First Time

US agriculture authorities confirmed on 10 October 2026 that highly pathogenic H5N1 avian influenza has been detected in dairy cattle in Washington state for the first time, with two herds in Yakima County now under quarantine. The detection pushes the US dairy outbreak, first confirmed in March 2024, into another western state and brings the total number of affected herds to 1,178 across the country. From 2024 to May 2026, 71 human cases of H5N1 have been identified in the US, mostly in farm workers exposed to infected cows or poultry; the CDC assesses risk to the general public as low. Globally, however, concern is rising: a deadly H5N1 lineage that emerged in Europe in 2020 has now reached Australia and Oceania, infecting hundreds of bird and mammal species and killing critically endangered Australian sea lions. WHO this year reported a fatal human H5N1 case among a cluster of zoonotic flu variants under investigation. Washington officials are stepping up surveillance of dairy and poultry workers, offering seasonal flu shots, and reminding consumers that pasteurised milk remains safe.