The facility was immediately quarantined by the California Department of Food and Agriculture. The
Tests at labs in Iowa and California confirmed the presence of the H5N8 virus, a strain that is not known to spread among humans. However, the strain is highly likely to cause disease among birds.
Avian flu has been detected at various sites in the U.S. and Canada since late 2014, but the outbreak at the Foster Farms ranch is the first time a commercial flock has become infected.
On Jan. 5, the USDA found a wild duck in Butte County with the same strain of avian flu as the outbreak at Foster Farms, according to state agriculture officials.
In Oregon, a backyard flock of geese, ducks and guinea fowl was euthanized in late December after the H5N8 virus was found there.