Avian flu outbreak in Stanislaus County makes 5 counties in California with the virus in commercial flocks

Stanislaus County is now the fifth county in California to report an outbreak of high pathogenic avian influenza in commercial poultry flocks.

Federal and state food an agriculture officials made the announcement Wednesday, reporting detection of the virus in two flocks of broiler chickens — combined affecting almost half a million birds.

The discovery follows the announcement a week ago of outbreaks in San Benito and Sonoma Counties, where more than 250,000 laying hens and Pekin ducks have been euthanized after the virus broke out at Sunrise Farms egg operation west of Petaluma and, earlier, at the Reichardt Duck Farm in Two Rock.

Outbreaks were reported earlier last month at two duck breeding facilities in Fresno County and in Merced, at a turkey farm in October and last February, at a duck breeding facility.

The Sonoma County Board of Supervisors on Tuesday declared a local emergency related to the outbreak. Officials said they hope to coordinate with other impacted counties to speed aid to those affected.

Avian flu has been spreading across the county since the middle of 2022 and has now affected 69 million birds in 47 states, according to the U.S. Department of Agriculture.

It is carried primarily by waterfowl and other wild birds, with incidence of the disease swelling each spring and fall, during their regular migrations.

It is transmitted in saliva droplets and can go airborne and in fecal matter. It is easily transmitted through soiled shoes and equipment if biosecurity cautions are not taken.

You can reach Staff Writer Mary Callahan (she/her) at 707-521-5249 or mary.callahan@pressdemocrat.com. On X/Twitter @MaryCallahanB.