The U.S. Department of Agriculture says the strain of high pathogenic avian influenza found in Tennessee last week is not connected to any strains of bird flu in China.
USDA says the strain found in Southern Tennessee originated from North American wild birds.
More than 73,000 birds at the infected farm have been depopulated and nearby farms are also being tested. The strain is also different from the strain that was responsible for the 2015 U.S. HPAI outbreak.
Tennessee State Veterinarian Charles Hatcher told Politico this week “epidemiology studies are ongoing” to determine how the virus entered the farm.
He suggested the infection could be the result of a mild security breach, or wild bird feces entering the chicken house through a ventilation fan.
27 nations, along with the European Union, have temporarily blocked poultry imports from Lincoln County, Tennessee, and the site of a low pathogenic avian influenza outbreak, Barron County, Wisconsin.