Here's how it would happen. Children playing along an urban river bank would spot hundreds of grotesque, bloated pig carcasses bobbing downstream. Hundreds of miles away, angry citizens would protest the rising stench from piles of dead ducks and swans, their rotting bodies collecting by the thousands along river banks. And three unrelated individuals would stagger into three different hospitals, gasping for air. Two would quickly die of severe pneumonia and the third would lay in critical condition in an intensive care unit for many days. Government officials would announce that a previously unknown virus had sickened three people, at least, and killed two of them. And while the world was left to wonder how the pigs, ducks, swans, and people might be connected, the World Health Organization would release deliberately terse statements, offering little insight.
It reads like a movie plot -- I should know, as I was a consultant for Steven Soderbergh's Contagion. But the facts delineated are all true, and have transpired over the last six weeks in China. The events could, indeed, be unrelated, and the new virus, a form of influenza denoted as H7N9, may have already run its course, infecting just three people and killing two.
Or this could be how pandemics begin.