Swine Flu Transmission

Prior to 2009, person-to-person transmission of swine influenza viruses was rare. Most infected people had direct contact with pigs. In the 2009 outbreak, however, most cases have not had contact with pigs.

This has led the CDC to report that the swine influenza virus has changed enough to allow for person-to-person transmission. However, it is not known how easily the strain is transmitted between people.

This is a key piece of information for determining whether swine influenza will truly cause a significant pandemic.

During a normal influenza season, the human influenza virus is spread through respiratory droplets. Droplets are expelled into the air through coughing or sneezing.

They can also be spread by poor hand washing when contaminated hands touch eyes, noses, or mouths.

In March and April 2009, hundreds of cases of respiratory illness were reported in Mexico that were suspected or confirmed to be caused by swine influenza.