Highly pathogenic avian influenza (HPAI) was confirmed in a commercial duck breeder flock in Merced County, California.

The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) stated that the presence of the virus was confirmed on February 6, and 29,100 birds were involved.

This is the first commercial flock, according to APHIS, to have a confirmed case of HPAI in California so far in 2023. However, HPAI was confirmed in a flock not identified as a commercial flock that involved 29,700 birds in the state on January 12.

Prior to that, the last commercial operation in California to be affected by HPAI was a commercial upland gamebird farm in Glenn County. That case was confirmed on December 22, 2022.


In 2022, California had 15 cases of HPAI confirmed in commercial flocks, affecting nearly 760,000 birds.

So far in 2023, commercial flocks in the following states have had confirmed cases of HPAI: Pennsylvania, Virginia, Iowa, Tennessee and Kansas. In Canada, the provinces of British Columbia and Quebec have had cases of HPAI in commercial poultry flocks in 2023.

To learn more about HPAI cases in commercial poultry flocks in the United States and Canada, see an interactive map on WATTPoultry.com. 

Read our ongoing coverage of the global avian influenza outbreak.