Another case of highly pathogenic avian influenza (HPAI) was confirmed in Pennsylvania on May 23.

According to the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), the virus was found in a commercial duck breeder flock in Berks County, Pennsylvania. The recently affected flock included 4,700 ducks.

Berks County has now had eight confirmed cases of HPAI. Of those eight, six have affected commercial duck operations. The county has also had HPAI appear in a commercial table egg layer operation and a commercial table egg breeder operation.

Pennsylvania, so far in 2022, has had 16 cases of HPAI with almost 4.3 million birds affected. Half of those have been in Berks County, while the other half have been in Lancaster County. The Lancaster County cases have involved ducks, broilers, broiler breeders and layers. The state so far has not had any backyard flocks affected by avian influenza.

The only other HPAI case confirmed by APHIS on May 23 occurred in a backyard flock in Bayfield County, Wisconsin. This is Bayfield County’s first case, but in accordance with World Organisation for Animal Health (OIE) standards, this should not have an impact on international poultry trade.


The HPAI outbreak has caused havoc for U.S. duck, egg, broiler and turkey producers in 2022, having affected an estimated 37,258,200 birds in the country to date, according to information from APHIS and other animal health agencies.

In addition to Pennsylvania, HPAI has been confirmed in the following states: Michigan, Wisconsin, Oklahoma, Minnesota, North Dakota, South Dakota, Nebraska, Kansas, Iowa, Missouri, Kentucky, Indiana, Colorado, North Carolina, Delaware, Maryland and Utah. The virus has also been found in commercial game bird operations in Texas, New York and South Dakota.

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

Read our ongoing coverage of the global avian influenza outbreak.