California Department of Public Health announcements

California Investigates H5N1 Outbreaks at Three Central Valley Dairy Farms

Aug 30, 2024, 10:22 AM

California, the largest milk producer in the United States, is investigating potential outbreaks of the highly pathogenic avian influenza (H5N1) at three dairy farms in the Central Valley. The California Department of Food and Agriculture (CDFA) announced the investigation, which, if confirmed, would mark the first cases of H5N1 in dairy cattle in the state. The U.S. Department of Agriculture is conducting tests to confirm the presence of the virus. California has approximately 1,300 dairy farms and 1.69 million dairy cows, producing nearly 20% of the nation's milk. The state would become the 14th to report H5N1 infections in dairy cows if the cases are confirmed. The potential outbreaks could have significant implications for California's dairy industry, which is a major contributor to the state's economy. Pasteurization is fully effective at eliminating the virus, and 13 dairy and poultry farm workers have been infected nationally.