H5N1 Spreads to 749 California Dairy Herds as Global Human Cases Rise Amid Ongoing Bird Flu Outbreak

This is Bird Flu Bulletin: Daily H5N1 Update. Today is Monday, October 20th, 2025. Top stories First, the California Department of Food and Agriculture reports that H5N1 has now been confirmed in 11 additional dairy herds in the past 30 days, bringing the statewide total to 749 infected dairies. Of these, 384 have recovered and are now under bi-monthly surveillance testing. Continued quarantines are in effect for active outbreak zones and the state recommends that farm workers remain vigilant in using personal protective equipment. Second, the Pan American Health Organization has confirmed another human fatality linked to H5N1 in the Americas, emphasizing the virus’s ongoing threat. Globally, the fatality rate among confirmed human H5N1 cases remains at 48 percent. Since August, there have been 76 human cases and two deaths across five countries in the Americas, part of a worldwide count of 990 cases and 475 fatalities. Health experts are concerned about further mutations and spread, especially to mammals. Third, the USDA announced new wild bird H5N1 detections in multiple states over the weekend. Recent findings include infected mallards and geese in New Hampshire, Utah, and Texas, as well as several new cases in backyard flocks in Oregon and Montana. These reports highlight active virus circulation among wild and domestic animals. Case numbers Compared to yesterday, there are ten more confirmed infected dairy herds in California. Nationally, human H5N1 cases have increased by two, and one additional fatality has been recorded in the Americas region. In the broader agricultural sector, millions of birds have already been culled to contain the spread. New guidance The California Department of Public Health maintains that risk to the general public is low but expects more human cases to be identified. CDPH urges all individuals working around infected or suspected animals to use comprehensive PPE, including N95 masks, gloves, and eye protection. The USDA continues to require pre-movement testing of dairy cattle and is increasing raw milk testing at creameries, aiming for earlier outbreak identification. Expert interview For expert insight, we spoke with Dr. Elena Ruiz, an infectious disease specialist: “The biggest concern right now is the ongoing transmission of H5N1 between species. While human risk remains low, there is a real danger that further adaptation in mammals could increase the pandemic threat. Continued surveillance is absolutely essential, especially in high-contact work environments.” Looking ahead Tomorrow, we expect an update from the Centers for Disease Control on the genetic sequencing of recent H5N1 samples. Additionally, California state officials are scheduled to hold a briefing on expanded surveillance protocols for dairy operations. Also, look for further USDA reports on wild bird detections across the Midwest and West Coast. Thank you for tuning in to Bird Flu Bulletin: Daily H5N1 Update. Please come back next This content was created in partnership and with the help of Artificial Intelligence AI.