Highly pathogenic avian influenza (HPAI) appears to be ramping up in California, with several cases confirmed in large commercial poultry operations over the past week. Several other states are also reporting the virus in commercial operations as the virus continues to spread nationwide. The total number of birds affected in the 2022-2023 U.S. outbreak has now reached 69.5 million, USDA’s Animal and Plant Health Inspection Service numbers show.

Two broiler operations in California—one with 239,900 birds and the other with 254,400 birds—were both located in Stanislaus County. A third broiler operation in Stanislaus County was listed on USDA’s website Friday but the number of birds was not yet reported. A commercial egg laying operation of 270,000 birds in Sonoma County is also being depopulated.

In Arkansas, a broiler operation of 109,000 birds in Johnson County and a turkey operation of 33,300 birds in Carroll County recently confirmed the virus.

Meanwhile, turkey operations of 40,800 birds in McPherson County, South Dakota; 56,200 birds in Hamlin, South Dakota; 113,800 birds in Barron County, Wisconsin; 64,200 birds in Todd County, Minnesota; and 26,700 birds in Otter Trail County, Minnesota, are being depopulated after discovering the virus.

Post Holdings reported Dec. 7 that approximately 10% of Post’s controlled supply of eggs has been impacted by avian flu. Michael Foods’ third-party contracted egg-laying flocks in Iowa and Ohio recently tested positive for avian influenza, resulting in the depopulation of 4.2 million layers, the company said.

Canada also continues to see a growing number of cases. In an update provided to Feedstuffs, the Canadian Food Inspection Agency said 67 commercial poultry operations have been impacted since September 2023. However, since an initial onset of the virus in December 2021, the total estimated number of birds impacted in Canada is 10.14 million.

Analysis of the North American outbreak has shown that the spread has been primarily from wild migratory waterfowl. The virus can spread through the droppings or the nasal discharge of an infected bird, both of which can contaminate dust and soil. As such, commercial and backyard flock owners should prevent contact between their birds and wild birds. Sick birds or unusual deaths among birds should be immediately reported to state or federal officials.