This is a long read, about 6 pages. Probably one of the best articles. http://www.smithsonianmagazine.com/issues/2006/january/flu.php Interesting thing I learned: Ducks/Waterfowl can carry the virus, but they are a trojan horse. They don't die from avian flu. They just spread it around the world. From Page 4: "And then there are pigs. For many years, Webster has theorized that pigs are the mixing bowls for pandemic flu outbreaks. He has actually enshrined the theory in his house. He has a stained-glass window next to his front door that depicts what he perceives to be the natural evolution of flu pandemics. At the top of the glass, birds fly. Below them, a pig grazes. Man stands off to the left. Below all of them are circles that represent viruses and seem to be in motion. They are set in a backdrop of fever red. The pig is in the picture because its genome, perhaps surprisingly, shares certain key features with the human genome. Pigs readily catch human flu strains. Pigs are also susceptible to picking up avian flu strains, mostly because they often live so close to poultry. If a human flu strain and an avian flu strain infect a pig cell at the same time, and the two different viruses exchange genetic material inside a pig cell, it’s possible that the virulent avian strain will pick up human flu virus genes that control transmission between people. If that happens with H5N1, that will almost certainly mean that the virus will be able to pass easily from person to person. A pandemic may not be far behind. During his talk in Atlanta, Webster pointed out that this H5N1 virus was so crafty that it has already learned to infect tigers and other cats, something no avian flu has ever done. “The pig may or may not be necessary” for a pandemic to go off, Webster said. “Anyway, this virus has a chance at being successful.” He said he hoped world health officials “would keep making their plans because they may face it this winter."