California has become an emerging front for the ongoing highly pathogenic avian influenza outbreak in dairy cattle, with 41 herds infected in the past month and new cases appearing regularly. While the H5N1 virus has heavily impacted poultry since 2022, California’s Central Valley saw its first dairy infections in late August. Since then, the disease has spread quickly, with seven cases confirmed between September 23 and 26, according to the California Department of Food and Agriculture.
According to the CDFA, farmers are employing stringent biosecurity measures, including restricting visitors, enforcing off-site barriers, and using personal protective equipment. Dairies under quarantine have also implemented strict sanitation protocols for livestock trailers and worker uniforms.
No dairy livestock are currently being exhibited at fairs across California. Raudabaugh’s organization is distributing free PPE and providing resources to assist affected farms.
The University of California Cooperative Extension is working closely with the industry, offering webinars to share the latest research on biocontainment and virus management strategies. Despite improvements in response efforts, Raudabaugh acknowledged there will be a need for extensive after-action evaluations to strengthen future preparedness.
Nationwide, HPAI has led to the loss of over 100 million birds since 2022 and affected 239 dairy herds across 14 states as of late September. In the West, herds in Colorado, Idaho, New Mexico, and Wyoming have also been impacted.
While the risk to humans remains low, the economic toll on dairy farmers is significant. One Michigan dairy producer reported losses of $100,000 from a recent outbreak on his farm. Producers are being urged to monitor cattle for symptoms such as reduced milk production, dehydration, and fever, with officials stressing the importance of early detection and prompt treatment.
The USDA is accepting applications for assistance through the Emergency Assistance for Livestock, Honeybees, and Farm-raised Fish Program for eligible producers facing losses from H5N1.
