Around Thanksgiving 2005 a teenage boy helped his brother-in-law butcher 31 pigs at a local Wisconsin slaughterhouse, and a week later the 17-year-old pinned down another pig while it was gutted. In the lead-up to the holidays the boy's family bought a chicken and kept the animal in their home, out of the harsh Sheboygan autumn. On Dec. 7, the teenager came down with the flu, suffering an illness that lasted three days. He visited a local clinic, then fully recovered, and nobody else in his family took ill.
This incident would hardly seem worth mentioning except that the influenza virus that infected the Wisconsin lad was unlike any previously seen. It appeared to be a mosaic of a wild-bird form of flu, a human type and a strain found in pigs.
It was an H1N1 swine influenza. Largely ignored at the time, the Wisconsin virus was a step along the evolutionary tree, leading to a virus that four years later would stun the world.
Flash-forward to April 2009, and young Édgar Enrique Hernández in faraway La Gloria, Mexico, suffers a bout of flu, found to be caused by a similar mosaic of swine/bird/human flu, also H1N1. And thousands of miles away in Cairo, the Egyptian government decides pigs are the source of disease, and orders 300,000 animals in the predominantly Muslim (therefore not pork-consuming) society slaughtered.