H5N1 Accelerates in Iowa, California

17 Dec 2024

LINCOLN, Neb. (DTN) -- The spread of highly pathogenic avian influenza H5N1 has accelerated in Iowa in recent weeks, with the state reporting three new cases in three counties on Monday, including a commercial layer flock in Sioux County, a commercial turkey flock in Worth County, and a backyard mixed-species flock in Monona County.

The Iowa Department of Agriculture and Land Stewardship reported this week the state now has 11 detections of the strain in poultry in 2024. Most of the state's cases this year were reported in December.

Over the weekend, the state reported it had detected an HPAI case in a commercial layer flock in O'Brien County. On Dec. 11, 2024, Iowa reported HPAI in a commercial turkey flock in Sac County.

Two days earlier, a commercial layer flock in Sioux County tested positive, and on Dec. 8, HPAI was found in a commercial turkey flock in Palo Alto County. On Dec. 6, a commercial-layer chicken flock tested positive also in Sioux County.

Nationally, the number of birds affected by the virus has grown from about 70,000 in September to about 11.7 million in December, according to USDA's Animal and Plant Health Inspection Service (APHIS).

The vast majority of the cases have been confirmed in California, where about 7.3 million birds and 25 commercial flocks have tested positive since the outbreak started in 2022.

In December alone, California has reported new poultry cases in 14 counties, according to APHIS, involving about 5.1 million birds.

In Michigan, the state reported on Monday its first HPAI-positive test in an Ottawa County commercial poultry facility since May 2024.

It is Michigan's second case in a commercial flock since the disease was detected in 2022, according to the Michigan Department of Agriculture and Rural Development.

"As the weather remains cold and HPAI continues to circulate in wild bird populations, conditions are ideal for the virus to thrive and spread," said Michigan State Veterinarian Nora Wineland.

"It is critical to prevent the introduction of disease by taking measures such as keeping domestic animals away from wild birds and cleaning and disinfecting equipment between uses."

Also on Monday, APHIS confirmed HPAI in a backyard non-poultry flock in Bossier Parish, Louisiana, which is the first case found in domestic birds in the state.

Earlier this month, APHIS announced the start of its national milk testing program, which requires raw milk samples to be collected nationwide and shared with USDA for testing.

USDA continues to stress the importance of good biosecurity practices to combat the H5N1 virus in all livestock, poultry and humans.