Bird flu strikes flock of 4.2 million chickens in Sioux County • Iowa…

Avian influenza that is very transmissible and lethal for domestic birds has been detected in a flock of 4.2 million egg-laying chickens in Sioux County, according to the Iowa Department of Agriculture and Land Stewardship.

It is the first confirmation of highly pathogenic avian influenza in a commercial or backyard poultry flock this year in Iowa. IDALS reported it Tuesday.

Entire flocks are culled — and their carcasses isolated — to prevent the spread of the virus to other flocks.

The virus outbreak has been ongoing since early 2022 and is primarily driven by migrating birds, which can be contagious without showing symptoms.

In the past month, Minnesota is the only neighboring state of Iowa that has had infected flocks, according to the U.S. Department of Agriculture. Five of those confirmations happened about two weeks ago. They included four commercial turkey operations and one commercial egg-layer flock that totaled about 1.5 million…