As near as anyone knows, the recent outbreaks of swine flu in the United States have been the result of Americans, returning to America, from Mexico, to where they live, in America. This makes a certain sense -- the larger outbreak is in Mexico, American tourists often travel to Mexico, most prefer to return home at some point. On the other hand, however, the swine flu might actually be THE NEXT WAVE OF THE RECONQUISTA, SOUND THE ALARMS!
Media Matters, has produced an entertaining little mashup, chronicling the swine flu angle from that point of view, where illegal immigrants are not just the "perfect mules" for influenza -- they are the "perfect mules" for terrorism! "What better way to sneak a virus in this country than to give it to Mexicans?" asks Neil Boortz, apparently unaware that the answer to his question is "Virtually all the other ways you can think of."
Anyway, this is compelling stuff, so long as you haven't even a passing understanding of how epidemiology and disease vectors work.