A UDSA swine Influenza researcher says the influenza A/H1N1 virus may have originated in Asia and travelled to North America via human carrier. Previously, it was thought that the new swine flu pandemic arose in swine operations in Mexico. The researchers however, emphasized that there was no way to prove the theory.
American breeding pigs are frequently exported to Asia thereby possibly leading to the mixing of flu strains. But because of disease quarantines that make it hard to import Asian pigs it is unlikely that a pig brought the new strain back West, according to the experts.
"The most likely scenario is that it came over in the mammalian species that moves most freely around the world," said Amy Vincent, a swine flu specialist at the Agriculture Department's laboratory in Ames, Iowa, referring to people.
Read more about people carrying flu virus.