500 years later, scientists discover what probably killed the Aztecs

Within five years, 15 million people - 80% of the population - were wiped out in an epidemic named 'cocoliztli', meaning pestilence

In 1545 disaster struck Mexico's Aztec nation when people started coming down with high fevers, headaches and bleeding from the eyes, mouth and nose. Death generally followed in three or four days.

Within five years as many as 15 million people - an estimated 80% of the population - were wiped out in an epidemic the locals named "cocoliztli". The word means pestilence in the Aztec Nahuatl language. Its cause, however, has been questioned for nearly 500 years.