First, the climate. Next, plagues. Bill Gates's career switch from entrepreneur and philanthropist to crusading author is developing nicely. It is just over a year since he published How To Avoid A Climate Disaster. Now he sets out to explain How To Prevent The Next Pandemic.

Both books consider what might be described as human-created natural disasters. Some disasters - hurricanes, earthquakes, tsunamis - are purely natural. The best people can do when dealing with these is to anticipate them through things like warning systems, planning codes and reinforced buildings. Others, such as war, have human causes. They may sometimes have a natural trigger, such as a drought that sets populations on the move. But human beings inflict the damage.