A link to a post in the Huffington Post by David Kirby on the origins. I found it at Mex Files. It cites the Secretary of Health attributing the first case to a four-year-old boy in La Gloria, Perote, in April. This doesn't clarify much, however.
Note the article talks of the long-term complaints of people in the area of La Granja Carroll. I remember maybe two years ago we went to plant trees on Perote with a bunch of people that included an official from the department of sanitation in Xalapa. He mentioned problems of water pollution from Granjas Carroll, and dismay at the consequences.
Maybe people will start looking seriously at consequences of industrial farming practices. Whether or not the flu is traced directly to Granjas Carroll or not, there are significant pollution and animal treatment issues that we need to address.