A: The main cause of rapid population growth is when there are more births than there are deaths, which is referred to as a natural increase. Other causes of ... Full Answer >
Spanish flu (1918-1919). The influenza pandemic of 1918-1919 killed more people than the World War I, at somewhere between 20 and 40 million people. It has been cited as the most devastating epidemic in recorded world history. Known as Spanish Flu or La Grippe the influenza of 1918-1920 was a global disaster.
The perfect plague. The first wave was the worst, killing some 25 million in Europe alone. By 1400 â a mere 50 years after the pandemic began â various epidemics and resurgence had reduced the worldâs population from about 450 million to between 350 and 300 million, maybe less.