H1N1 or Swine Flu

The H1N1 virus also known as swine flu is a contagious acute respiratory disease of pigs (a type of swine) caused by one of several swine influenza A viruses (most commonly of the H1N1 subtype, but other subtypes - like H1N2, H3N1, and H3N2 - also circulate in pigs).  Many countries routinely vaccinate swine populations against these viruses, as outbreaks among pigs are known to have occurred in several countries around the world.  Until recently, transmission to humans was occasionally reported.  In early 2009, several cases of human infection with swine influenza A (H1N1) were reported, the first of which occurred in Mexico, followed by several other countries, including the U.S.  Confirmed deaths due to the disease have also been reported.  Clinical presentation of swine influenza infection in humans resembles seasonal influenza and other acute upper respiratory tract infections but presentation of the disease can also range broadly from showing no symptoms of infection to severe pneumonia resulting in death.  A novel vaccine for H1N1 is currently under development and is expected to be available in the fall of 2009, according to the Centers for Disease Control and Prevention (CDC), and there are other basic preventive measures that can also be taken.