The presence of highly pathogenic avian influenza (HPAI) has been confirmed in a commercial layer chicken flock in Jefferson County, Wisconsin.

The confirmation was announced on March 14 by the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS).

Samples from the flock were tested at the Wisconsin Veterinary Diagnostic Laboratory, part of the National Animal Health Laboratory Network, and confirmed at the APHIS National Veterinary Services Laboratories (NVSL) in Ames, Iowa.

 The size of the flock has not yet been disclosed.

APHIS is working closely with state animal health officials in Wisconsin on a joint incident response. State officials quarantined the affected premises, and birds on the property will be depopulated to prevent the spread of the disease. 

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This marks the first case of HPAI to be confirmed in Wisconsin. With this new case, HPAI has now been found in commercial poultry in eight states. The other states to be affected are Missouri, Indiana, Kentucky, Iowa, South Dakota, Maryland and Delaware. In addition to the eight states, HPAI has also been confirmed in a commercial poultry flock in Nova Scotia, Canada.

This also marks the third case of HPAI to be confirmed in a commercial layer operation in the United States. The other two cases were in Cecil County, Maryland, and New Castle County, Delaware. Those two cases resulted in the loss of more than 1.6 million layers.

HPAI has been confirmed in all four North American flyways, but only three flyways have had confirmed cases in commercial poultry. The Pacific Flyway case involved a bald eagle in British Columbia, Canada. HPAI cases in wild birds such as that eagle should not result in any poultry trade bans, in accordance with standards set by the World Organisation for Animal Health (OIE).

To learn more about HPAI cases in North American commercial poultry flocks, see an interactive map on WATTPoultry.com.

Read our ongoing coverage of the global avian influenza outbreak.