In March 2017, highly pathogenic avian influenza A(H7N9) was detected at 2 poultry farms in Tennessee, USA. Surveillance data and genetic analyses indicated multiple introductions of low pathogenicity avian influenza virus before mutation to high pathogenicity and interfarm transmission. Poultry surveillance should continue because low pathogenicity viruses circulate and spill over into commercial poultry.
Keywords: Alabama; H7N9; HPAI virus; Iowa; Tennessee; United States; Wyoming; backyard farm; chicken; commercial farm; farm; highly pathogenic avian influenza virus; influenza; mutation; phylogenetic analysis; poultry; respiratory infections; transmission; viruses; wild bird; zoonoses.