Table 2. Influenza A viruses identified in swine in Chile and Mexico.

Introductions into swine in Chile and Mexico of influenza A viruses from North American swine (classical H1 and H3-IV viruses) and humans (pandemic H1N1 viruses and seasonal H1N1/H3N2 viruses). § One of these introductions is a singleton (A/sw/Mexico/8935602/2012/H1N1) with little evidence of onward transmission. ¶ It remains unclear whether one of these introductions (Chile H3 human II, A/sw/Chile/9313892/2012/H3N2) represents a separate introduction of seasonal H3N2 viruses from humans, or represents dissemination via swine of a previously described introduction of human H3N2 viruses into swine in Brazil.

	Classical H1 (North American swine)	H3-IV (North American swine)	Human pandemic H1	Human seasonal H1	Human seasonal H3
Chile	0	0	5	2	2¶
Mexico	2§	1	7	0	1