Fall of the Aztecs

In the early 1500s, the thriving Aztec empire encompassed an impressive 25 million people. But the arrival of the Spanish Conquistadors led by Hernán Cortés marked the beginning of the end for them.

At first Cortés was forced to leave the Aztec capital, Tenochtitlán, but when he returned ten months later, it had been weakened by famine, drought, and a disease epidemic. So it didn't take much work for him to sack the city in August 1521. Historians have long speculated that the disease that killed up to 18 million Aztecs was brought by the Spanish.

Now new data further confirms this hunch. It may have been a deadly form of the bacterium, Salmonella typhi. Advances in technology have allowed scientists to develop ways to identify the bacterial DNA found among the teeth of Aztecs buried both before and after contact with Europeans.

They identified the ancient genome, enterica serovar Paratyphi C, which causes enteric fever. This pathogen existed in Europe as early as the year 1200. Enteric fever still exists today and can be life threatening. There are about 5,700 cases in the U.S. yearly, with most people acquiring the disease abroad. But enteric fever is common in developing countries, with 21 million cases yearly.

Salmonella typhi only infects people and symptoms include high fevers, weakness, stomach pain, headache, rash or loss of appetite. Without treatment, people can become delirious, motionless with exhaustion in what is called the typhoid state.

Unfortunately for the Aztecs, another epidemic also brought by Europeans, smallpox, further decimated their population.