They weren't Mexican pigs. The pigs belonged to Smithfield Foods and were being raised and slaughtered using cheap Mexican labor.

But still why lie about the pigs? Maybe they aren't testing them?

There was a news story stating that when this first emerged Smithfield dispatched its head of operations and PR to Mexico (may have the positions wrong but these were two very senior executives).

At this point Smithfield and the rulers of Mexico (I do not want to insult them by calling them a "government") share a joint interest in getting this story off the front pages as quickly as possible.

Mexico's interest lies in the fact that this outbreak disrupts a major source of present and future earnings with big emphasis on future earnings due to declining oil income.

The hog producer does not want to be remembered as being ground zero for something with the potential to kill millions. It doesn't help brand equity and will likely result in closer government inspection and increased regulation of all swine factories everywhere. This impacts future profits.

So I would bet a dollar there is back office somewhere providing heavy PR support to get the story out. Stories of lovable 5 year olds who were inflicted with a disease from the sky. Stories about drops in the number of dead and the number infected. Stories of a resolute and dedicated health care system that battled this slightly worrisome disease derived from alien DNA to a standstill.