| swine-origin influenza a (h3n2) virus infection in two children--indiana and pennsylvania, july-august 2011. | influenza a viruses are endemic in many animal species, including humans, swine, and wild birds, and sporadic cases of transmission of influenza a viruses between humans and animals do occur, including human infections with avian-origin influenza a viruses (i.e., h5n1 and h7n7) and swine-origin influenza a viruses (i.e., h1n1, h1n2, and h3n2). genetic analysis can distinguish animal origin influenza viruses from the seasonal human influenza viruses that circulate widely and cause annual epidemic ... | 2011 | 21900876 |