AAC member reports confirmed H5N1 in San Mateo backyard flock; quarantines and monitoring ongoing

Warren, an AAC member, briefed the committee at the Feb. 10 meeting on recent H5N1 detections in the county and state. He reported that the U.S. Department of Agriculture confirmed a case in a San Mateo backyard flock last week; that property is under a roughly 120‑day quarantine and health officials are monitoring nearby premises and people for possible exposure.

Warren also reported a confirmed H5N1 detection in a stray cat in Half Moon Bay, which officials isolated. He said state and federal authorities are treating the incidents as isolated at this point but noted that the virus is widespread in California’s animal populations and that large commercial operations—particularly dairies—have been affected in other parts of the state.

“It's widespread in the state of California,” Warren said during the report, and he urged producers to adopt biosecurity precautions such as limiting foot and vehicle traffic between operations. He said there are indemnification resources and guidance on the California Department of Food and Agriculture website, and that county staff can help livestock owners navigate available resources. Warren confirmed there are no confirmed person‑to‑person cases and said monitoring of humans and animals around the infected site continues.

No formal committee action was taken; the report was informational and committee members were offered contact information to follow up with Warren for technical assistance.