Where has swine flue been?
The virus can’t flourish without a host. When enough people develop immunity it is weakened Of the three genera of influenza viruses that cause human flu, two also cause influenza in pigs, with influenza A being common in pigs and influenza C being rare. Influenza B has not been reported in pigs. Within influenza A and influenza C, the strains found in pigs and humans are largely distinct, although due to reassortment there have been transfers of genes among strains crossing swine, avian, and human species boundaries. So it lives on in one form or another, made a brief appearance in 1976, lurked in the pig until this present strain made the leap from pig to human.
