date:Oct 18, 2013
1, the United States of America reported a cluster of cases of human infection with a swineorigin influenza A(H3N2) variant virus H3N2v containing the matrix (M) gene from the 2009 H1N1 pandemic virus (A(H1N1)pdm09). In 2012, 309 influenza H3N2v virus infections in humans were identified in the US and 12 cases in 2013. Most of the human infections occurred in persons that had contact with live pigs at county fairs, especially children.
Swine are an important host in influenza virus ecology sinc