Rated: 21 times. Average rating 4.52
It may sound innocuous compared to war, plague and famine, but flu is in fact one of the world's biggest killers. Strains of the virus are always in circulation, but every so often a new and particularly virulent one comes along, to which we have no historic immunity - when that happens the consequences are devastating. Since the first documented pandemic of an influenza-like disease in 1580, 31 worldwide influenza outbreaks have been recorded, culminating in the pandemic of 1918, which killed an estimated 50 million.