WASHINGTON, April 25 (Xinhua) -- What is swine flu?

    Swine flue (Influenza) is a respiratory disease of pigs caused by type A influenza viruses. Outbreaks of swine flu happen regularly in pigs. People do not normally get swine flu, but human infections can and do happen. Most commonly, human cases of swine flu happen in people who are around pigs but it's possible for swine flu viruses to spread from person to person also.

    The new strain found in Mexico and the U.S. is a mixture of swine, human and avian flu viruses.