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Helping in the fight against avian flu

May 27, 2015 By Kelly April Tyrrell

Avian influenza has made headlines in Wisconsin and several other states in recent weeks. The University of Wisconsin–Madison and the Wisconsin Veterinary Diagnostic Laboratory (WVDL) are on the front line in responding to and understanding the virus and providing critical testing for food producers and commercial and private flock owners.

On April 11, 2015 the H5N2 virus was detected at a commercial chicken facility in Jefferson County, Wisconsin. By May 5, the virus had struck 9 commercial flocks in four Wisconsin counties, leading to the demise of more than 1.7 million chickens and turkeys. A snowy owl found dead in the wild in Oconto County also tested positive for H5N2. Nationwide, the virus has led to the deaths of more than 32 million birds.

The H5N2 virus has significantly affected the U.S. agricultural economy and will drive rising food costs for consumers. Additionally, while there are no reports of human infections in the current outbreak in the United States, similar viruses have infected more than 800 people in Asia and Europe over the last decade.

The United States Department of Agriculture and the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) State Veterinarian’s Office are managing the outbreak in Wisconsin. WVDL works with these agencies to provide ongoing testing.

The current H5N2 outbreak first appeared in a backyard poultry flock in Washington State in January 2015. At that time, WVDL, as part of the National Animal Health Laboratory Network, began preparing to test birds in Wisconsin and other states if necessary.

Kathy Kurth-Toohey, virology section head at WVDL, has led diagnostic efforts at the laboratory. The laboratory tests turkeys, chickens, and ducks twice every 14 days in the infected, buffer, and surveillance zones established by DATCP and the USDA.

Researchers at UW–Madison are also leading efforts to study the virus and reduce its harm.

Mark Berres

Animal sciences professor Mark Berres is examining the prevalence of the virus among Red Jungle Fowl, the direct ancestors of domestic chickens. Like other wild waterfowl, Red Jungle Fowl can harbor the virus but do not get sick. Berres seeks to understand how chickens lost their resistance to the virus over the course of domestication or through selective breeding.

Yoshihiro Kawaoka, professor of pathobiological sciences in the UW–Madison School of Veterinary Medicine (SVM) is testing the virus found on Wisconsin’s farms to better understand it and the impact it could have on other species. He is also studying how some chickens have survived infection, despite its nearly 100 percent mortality rate.

Yoshihiro Kawaoka


Given the incidence of similar avian influenza strains in Europe and Asia, with human mortality rates as high as 50 percent, Kawaoka says research to understand the potential for H5N2 to become transmissible from person to person is crucial. However, this work is currently prohibited due to a federal funding pause.

No birds in Wisconsin have tested positive for a strain of H5N2 since May 5 and quarantines in the state have lifted, but DATCP and WVDL warn the outbreak may not be over. Both agencies encourage flock owners to continue using proper biosecurity techniques when working with poultry.

“We are expecting that a combination of weather and wild bird migration season ending will lead to a decline or cessation in positive farms,” says Keith Poulsen, a WVDL diagnostic and case outreach coordinator and an assistant clinical professor at SVM. “But we could see more cases in the fall, when temperatures drop and wild birds migrate again.”

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