Among the swine flu mysteries: Why only deaths in Mexico? - CNN.com

Among the swine flu mysteries: Why only deaths in Mexico? - CNN.com:

"'Do we really know all of the cases that existed in Mexico or is this just the tip of the iceberg?' asked Louis Sullivan, a physician and former head of Health and Human Services under President George H.W. Bush.

McKenna said it's possible 'there is much more flu in Mexico than we know because it hasn't been counted. That would mean that there are mild cases there as well, but that you have to get to a certain number of cases before, statistically, you start to see the very serious ones, and the U.S. hasn't had that many cases yet.'"