Bird Flu Detected in 1.2 Million-Bird Flock in Wisconsin

State officials have quarantined the premises and will cull the birds to contain the virus.

Published on Feb. 27, 2026

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The Wisconsin Department of Agriculture, Trade and Consumer Protection has reported the detection of bird flu in a commercial poultry flock of 1.2 million birds in Jefferson County, Wisconsin. The premises have been quarantined, and the birds will be killed to prevent the spread of the virus. This is the latest outbreak in the state, which has also seen infections in wild birds, dairy cattle, and other mammals over the past several years.

Why it matters

The continued spread of the H5N1 bird flu virus in the United States is a significant public health concern, as it has the potential to infect not only poultry and wild birds, but also other mammals, including humans. While the risk to the general public remains low, the virus poses a serious threat to those who work closely with infected animals.

The details

The U.S. Department of Agriculture is working with the state of Wisconsin to contain the virus and limit the movement of poultry products from the affected farm. A 10-kilometer control area has been established around the premises to restrict movement on or off nearby poultry operations. State and local health officials are also monitoring exposed farmworkers for possible symptoms of bird flu.

  • The bird flu outbreak was detected on February 27, 2026.
  • Last fall, two bird flu outbreaks were reported in flocks owned by Daybreak Foods, a major egg producer, also in Jefferson County.
  • In December 2024, Wisconsin reported its first and only human case of bird flu in a farmworker in Barron County.

The players

Wisconsin Department of Agriculture, Trade and Consumer Protection

The state agency responsible for overseeing and responding to the bird flu outbreak in the commercial poultry flock.

U.S. Department of Agriculture

The federal agency working with the state of Wisconsin to contain the virus and limit the movement of poultry products from the affected farm.

Daybreak Foods

A major egg producer in Jefferson County that experienced two bird flu outbreaks in its flocks last fall.

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What’s next

State and local health officials will continue to monitor the situation and exposed farmworkers for any signs of the virus spreading to humans.

The takeaway

The ongoing spread of the H5N1 bird flu virus in the United States, including in Wisconsin, highlights the need for vigilant monitoring and containment efforts to protect both animal and human health. While the risk to the general public remains low, the virus poses a serious threat to those who work closely with infected animals, underscoring the importance of robust biosecurity measures and worker safety protocols.