The current swine flu virus contains several blocks of known influenza viruses. Below is the swine flu virus and a human influenza virus.
It is suspected that the emergence of the current swine influenza as follows expired. There is probably a person with the flu pigs infected with a pig.
Then the virus mutates and the new swine flu (also called flu Mexico or Mexican flu called) arose.

The emergence of swine flu but no case demonstrated how closely the swine flu is concerned, nobody can say at present.

Maybe on a pig with swine flu and simultaneously infected with a human version of the flu.
After that, then the virus mutated and the new swine flu has emerged.

In any case, since the emergence of the swine flu virus to humans receive and thus infect other people.
This was not the case. When a man, swine flu, could they not be further extended to other humans.

More information about the emergence of the swine flu can be found on this website. (jumi [* 5] [formation])