Swine flu is caused by H1N1 virus. It first spread in Mexico where lots of pigs are grown. It spread to other countries and continents. A month ago WHO raised pandemic alert level 5. Any infectious disease is called pandemic when it occurs in two countries of same region and a country in another region. Swine flu has spread in North america (US and canada) Europe (UK, Germany, France, Netherlands, Italy etc) In Asia the Virus presents in china, hongkong, thailand, japan, india, singapore, etc.
In india so far 20 persons have been identified with the virus. Apparently they were from united states and arrived and chennai, bangalore and coimbatore airports.Tami flu is the best vaccine for swine flu. But it is not available in sufficient quantities in india.