A crowded world: pandemics

This month the world reaches 7 billion people and as the world becomes more and more crowded and urbanised, we worry more about the whole intricate structure that is civilisation falling over.

The movie Contagion, which has just opened in Australia, plays on deep-seated fears about our crowded, interconnected world. How long would our society cope with the onslaught of a killer viral flu, it asks. But how likely is a lethal pandemic, and is it a matter of if, or when?