There are two parts to the answer:
First, the prosaic: apparently, the current near-pandemic Swine Flu crossed to the human population at a pig farm owned by an American corporation in Mexico. So if anybody asks, it was American agribusiness, probably cutting corners on health and safety issues, that put the swine in Swine Flu.
Next, the metaphorical: The current wave of Swine Flu, having caused hundreds of deaths in Mexico and at least one in the United States, has caused a number of Americans in public life to behave like swine. These range from those who wonder aloud (and incorrectly) why swine flu outbreaks seems to happen under Democratic presidents to those whose instinct is to blame illegal immigrants for the dispersion of the disease.
The Swine Flu, to which the nation of Mexico has responded quickly and forthrightly, is being used by hatemongers across the United States to vilify, diminish and bear false witness against Mexicans as if there were some connection between the source of the influenza and the national character of the citizenry of our troubled neighbor to the south.
Tonight, President Obama had a news conference in which he actually began by telling Americans to wash their hands in order to keep from getting sick. I would add that we must wash our hands of xenophobia, jingoism and racism during the course of this wave of Swine Flu in order to keep from getting sick at heart.
--Renaissance