Illness that killed millions

Yesenia Vizguerra, Reporter

         During the 16th century, an epidemic known as “cocoliztli” caused the bleeding and vomiting in large areas of Guatemala, Mexico, and Peru. It wiped out roughly about 80% of the population, killing millions of people.

          With the ancient DNA collected from these countries in those who lived or died in the outbreak and a new technique to examine DNA, has been used to determine the cause of this mysterious epidemic that contributed to a “cataclysmic” population decline. Which refers to the violent natural event that occurred with this mysterious epidemic.

          Salmonella genomes, which cause typhoid fever, were recovered from the  DNA within the teeth of 10 skeletons buried in an undisturbed “cocoliztli” cemetery in Oaxaca, Mexico.

           This would be the first known occurrence of salmonella in the Americas, according to a new study published in the journal Nature. Typhoid fever has long been suspected due to the recorded symptoms, but this is the first identification of bacteria at the site.

            Researchers believe that this might have been brought on when Europeans came to Mesoamerica. It was known that Europeans were susceptible to typhoid fever and may have been carriers of this disease.

           “The cocoliztli is a mysterious historical epidemic, and over the years many have speculated on its cause,” says Kirsten Bos, a  study author and group leader of molecular palaeopathology at the Max Planck Institute for the Science of Human History in Germany. “This is the first time that ancient DNA has been successful in identifying a candidate pathogen for it.”

            The Teposcolula-Yucundaa’s Grand Plaza cemetery is known to be linked to this specific outbreak. The epidemic was so devastating that the city had to be relocated to a nearby valley, which allowed the cemetery to remain untouched for centuries. This, along with the thick, protective floor of the Grand Plaza, created the perfect conditions for testing and research.

            While the culprit diseases behind later epidemics, like smallpox, measles, mumps, and influenza, had been well documented, earlier epidemics in the “New World” weren’t as well-characterized, creating debate among researchers of the origin or cause.

Infectious disease pathogens don’t leave telltale marks on skeletons, according to the researchers. This is largely due to the fact that they are fast-acting and take their toll very quickly before the skeleton can be deformed in any way.

            When researchers look at skeletons like those in the pestilence cemetery, they have to search for possible causes based on what they know from historical accounts. But diseases and symptoms can vary over the years, or the symptoms can be so similar that it could be one of many causes.

           Researchers are planning to use more techniques to have more information on this disease and how it may have spread to such a large amount that killed millions of people. These new techniques may have been able to open doors to learn more about this disease.