Timeline: The secret history of swine flu - health - 29 October 2009 - New Scientist

Timeline: The secret history of swine flu - health - 29 October 2009 - New Scientist: "Six months ago, swine flu emerged as a massive threat to global health. It seemed to come out of nowhere, but our timeline explains how the origins of the H1N1 pandemic go back more than a century"

This is a great post on how the current evolved over time.