Second case of bird flu in 2025 detected in Iowa in a flock in O'Brien County

The Iowa Department of Agriculture and Land Stewardship along with the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) have detected a case of highly pathogenic avian influenza in a commercial layer flock in O’Brien County in northwestern Iowa. This marks Iowa’s second detection of H5N1 HPAI within domestic birds in 2025.

The first case of 2025 affected a multi-species backyard flock in Clinton County, Iowa, in eastern Iowa. Officials said 40 birds were infected.

This strain of the viral disease can affect wild and domestic bird populations, the state Department of Agriculture reported. Wild birds may not appear sick, but the disease is often fatal to domestic bird populations, including chickens and turkeys, the department said.

H5N1 HPAI can also impact dairy cattle, and 13 cases were detected in Iowa dairy herds in June 2024. With supportive care, dairy herds recover with limited, or no mortality associated with the disease, the state Department of Agriculture said.

Nationwide, the USDA detected bird flu in 113 flocks, affecting 19.5 million birds in 2025.

Since November 2023, more than 12.1 million birds on commercial flocks have been affected in Sioux County, Iowa, alone. In flocks where bird flu is detected, all birds are destroyed to prevent the spread of the disease, according to reporting by Investigate Midwest.

Since bird flu was first reported in 2022, Iowa lost 29.9 million birds, leading the nation.

More: See where bird flu has caused the most devastation in Iowa and across America

Meanwhile, 67 human cases have been reported in the U.S. since bird flu was first detected in humans in 2024, according to the CDC, and one person died.

The state Department of Agriculture reported that eggs and poultry remain safe to consume if cooked to an internal temperature of 165˚F.

This article originally appeared on Des Moines Register: Bird flu detected in an O'Brien County, Iowa, commercial flock