The Wisconsin Department of Agriculture, Trade and Consumer Protection confirmed on Thursday, November 12, 2026, that highly pathogenic avian influenza has struck a backyard poultry flock in Rusk County, Wisconsin. The Wisconsin bird flu case ended with every bird on the property being euthanized, and state officials say the birds will not enter the food system. How the flock became infected is not yet known; state and federal authorities are investigating.

Key Points

• Wisconsin officials confirmed on Thursday, November 12, 2026, that highly pathogenic avian influenza (HPAI) was found in a backyard poultry flock in Rusk County.
• All birds on the property were euthanized, a step officials call depopulation, and the birds will not enter the food system.
• Officials did not say how the flock became infected; state and federal authorities are investigating the source.
• When HPAI is confirmed in a backyard flock, officials may set up a 10-kilometre surveillance zone around the property, without movement restrictions for nearby poultry premises.
• The state agriculture department urges strict biosecurity: wash hands, disinfect equipment, restrict access to animals and keep new birds separate for at least 30 days.

What Happened

The announcement came from Madison, where the Wisconsin Department of Agriculture, Trade and Consumer Protection, known as DATCP, said it had identified a case of highly pathogenic avian influenza in a backyard poultry flock in Rusk County, in the northwest of the state. The department confirmed the case on Thursday, November 12, 2026; the birds had been depopulated.

Depopulation is the term officials use for the humane killing of an infected flock, the standard response to a confirmed HPAI case in domestic poultry, because the virus spreads fast and is often fatal to birds. DATCP said the birds will not enter the food system. Officials did not say how many birds were in the flock, and the source is under investigation. When HPAI is diagnosed in a backyard flock, a 10-kilometre surveillance zone may be put in place, without movement restrictions for surrounding premises, and owners can use DATCP's mapping tool to check whether their birds sit inside an active zone. Read our report on the bird flu death in Yakima County, Washington, the first US fatality of 2026.

Background and Context

Highly pathogenic avian influenza is caused by influenza type A viruses. In domestic poultry it is highly contagious and often fatal. It spreads through contact with infected birds, wild birds or their droppings, and contaminated equipment or clothing. The current wave has circulated in North American wild and domestic birds since December 2021, according to DATCP, and has since affected other species, including mammals. The department works with the USDA on testing and biosecurity.

The Wisconsin case follows other American outbreaks this year. In Washington state, a person died on Sunday, November 1, 2026, after exposure on a dairy farm in Yakima County, the first US bird flu death this year and the third since 2024. About 40 herds were infected across Washington state, most in Yakima County, and the CDC says there is no evidence of person-to-person spread and the risk to the general public remains low. An H5N1 outbreak was also reported this autumn on a Utah mink farm.

Wisconsin Bird Flu: What Rusk County Flock Owners Should Do Now

DATCP's message to flock owners is blunt: tighten biosecurity now, before the virus reaches your birds. The department urges all livestock owners to wash their hands, disinfect equipment, restrict access to their animals and separate new additions for at least 30 days. Poultry owners are asked, when possible, to keep their birds indoors.

The department also reminded Wisconsin livestock owners to register their premises. State law requires all livestock owners to register where their animals are kept, and poultry counts as livestock. Owners who notice increased deaths or illness among birds, dairy cattle or other animals should contact DATCP through its Animal Disease Reporting page. The advice matters most for small flocks, where birds roam, equipment is shared and new birds arrive from sales.

Reactions and Official Guidance

DATCP announced the case in a statement issued on Thursday, November 12, 2026. "Birds on the premises were depopulated and will not enter the food system," the department said. It added: "DATCP continues to urge all livestock owners to implement strong biosecurity measures to protect their flocks and herds from the disease."

The statement did not name the property or the owner, and it reported no human illness connected to the flock. It said the department continues to work with the USDA on testing, biosecurity and producer support. No further details about the investigation have been released, and officials have not said when the surveillance zone decision will be made.

Why It Matters

The Rusk County case matters because backyard flocks are everywhere, and they are the hardest part of the poultry world to protect. Commercial farms have fences, footbaths and controlled entry. Backyard keepers have a coop, a run and a routine that often involves wild birds overhead, shared feeders and neighbours dropping by. When the virus reaches a backyard flock, the whole flock is lost.

It matters too because the virus has proved so persistent. Nearly five years after it began circulating in North America, HPAI is still killing poultry and still spilling into mammals. The Yakima County death this month showed the human risk, while low for the general public, is real for farm workers. For consumers, the reassurance is that the depopulated birds will not enter the food system. Read our report on US measles cases rising to 5,182 nationwide.

What Happens Next

State and federal investigators will now try to trace how the Rusk County flock became infected, looking at wild bird activity, feed and water sources, equipment movements and recent additions to the flock. DATCP will decide whether to implement the 10-kilometre surveillance zone, and nearby owners can check the department's mapping tool to see whether they fall inside it.

DATCP will keep updating its HPAI in Poultry page, and owners are asked to report unusual deaths or illness in their birds promptly, since early reporting lets officials contain an outbreak before it spreads. More positive flocks in the coming weeks would signal autumn migration carrying the virus into new areas.

Frequently Asked Questions

What is highly pathogenic avian influenza? A highly contagious form of bird flu caused by influenza type A viruses. It is often fatal to domestic poultry and has circulated in North American wild and domestic birds since December 2021.

Were the birds killed? Yes. All birds on the property were euthanized, a step officials call depopulation, and they will not enter the food system.

Can bird flu spread to people? It has infected people who work closely with infected animals, including a dairy-farm worker who died in Yakima County on November 1, 2026. The CDC says there is no person-to-person spread and the risk to the general public remains low.

What should flock owners do? Wash hands, disinfect equipment, restrict access, separate new birds for 30 days, keep birds indoors when possible, register the premises and report illness to DATCP.