Table 3.

Evolution of swine influenza A virus.

1918-1919	H1N1 pandemic also affected swine
1930	The first isolation of H1N1 in pigs
1968	H3N2 infect swine in Asia after human pandemic
1976	Outbreak of new H1N1 swine strain of A/New Jersey/1976 occurred in military personnel at Fort Dix, New Jersey
1998	Triple reassortant viruses were isolated from pigs
1958-2005	37 human swine-origin influenza were reported
2005-2009	11 sporadic triple reassortant swine influenza viruses were reported in human
2009	New quadruple reassorted swine influenza H1N1 strain(A/California/07/2009)emerged in human populations and caused global influenza pandemic