By Laurie Garrett | NEWSWEEK
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.