Pandemic

A pandemic (from the Greek pan = all and demos = people) is an epidemic which extends to almost all of the population in one or more continents, or even in some cases the whole planet.

Humanity has been affected by several pandemics: the Black Death (or bubonic plague) which caused several million deaths in Europe between 1346 and 1350, the Spanish flu of 1918 to 1920 which caused 15 million deaths by spreading from China to Japan, Russia, Europe, and then North America.

After infecting more than 40 million people, AIDS is now considered to be a pandemic. It looks as though it is going to become the most lethal one in human history.