1. Human infection with influenza viruses from pigs are most likely to occur when people are in close proximity to infected pigs. Human-to-human Transmission of H1N1 Influenza A can also occur. The spread of H1N1 Influenza A is believed to be the same way as how seasonal flu spreads. Most common transmission of person to person infection is through coughing or sneezing of persons with influenza.
Notes: H1N1 Influenza A infection is contagious. Huamns with infection may be able to spread the influenza virus a day before the signs and symptoms appear and up to a week following the onset of illness.