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 epidemic threshold is crossed to some extent every year, a CDC chart shows. In the week ending December 20, nearly 7% of deaths were blamed on pneumonia and flu. That's higher than it was at the same time last year, but later on in the season, the percentage of deaths blamed on the flu generally goes higher.