An Important Newsweek Letter-to-the Editor from:  Laura H. Kahn, MD – May 16, 2009  (Scroll down to third letter)   In response to the following:   The Path of a Pandemic How one virus spread from pigs and birds to humans around the globe. And why microbes like the H1N1 flu have become a growing threat. By Laurie Garrett | NEWSWEEK Published May 2, 2009 From the magazine issue dated May 18, 2009