50+ History Of Pandemics Graph Pics. A graph showing the huge increase in deaths during the great plague of london in 1665 and 1666. A pandemic is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of people.

A pandemic is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of people.

Here are 20 of the worst epidemics and pandemics, dating from prehistoric to modern times. By julie tabouli | source: The history's worst known infectious disease outbreak of the spanish flu occurred in 1918. As human civilizations rose, these diseases struck them down.