Between the years 1545-1550 a mysterious epidemic hit Mexico and it has been called the “Cocoliztli Epidemics.” But up until now researchers have been uncertain as to just what the cause of the epidemic was. Dozens of epidemics hit Mexico with the arrival of the Spanish because the native people how no immunity to pathogens the Spanish brought with them. This was also the case thought the Americas and for the same reason. However, the unidentified cocoliztli epidemics hit Mexico especially hard as it affected large portions of Mexico and Guatemala including Oaxaca, Mexico.
This epidemic caused millions of death in Mexico killing about 80% of the population. It was one of the worst epidemics in human history to say the least. It has been estimated that anywhere between 5 million and 15 million people died and that is astounding! But this pestilence wasn’t finished yet because 30 years later it returned and wiped out half of the remaining native population between 1576-1578. A Spanish Franciscan friar who witnessed the pestilence wrote that New Spain (as the Spaniards called Mexico at the time) “was left almost empty.” He went on to write that in the cities and towns large ditches were dug “and from morning to sunset the priests did nothing else but carry the dead bodies and throw them into the ditches.”
Researchers have pondered just what these epidemics were that killed so much of Mexico’s native population with some suspecting it may have been smallpox, measles, or some type of hemorrhagic fever brought to Mexico by the Spanish conquerors. Sadly, nothing for certain was ever identified as the real cause behind these epidemics until recently when scientists used DNA from a graveyard from that era to identify possible causes. It appears that Salmonella enterica was the cause. This pathogen causes enteric or typhoid fever.
This information comes to us from researchers from the Max Planck Institute for the Science of Human History, Harvard University, and the Mexican National Institute of Anthropology & History who recently concluded a study on the human remains found in the mass graves. Another point of interest is that up until now we’ve had to rely on historical descriptions from the times pertaining to symptoms, etc which were often biased and inaccurate. Further, most infectious diseases are very hard to track on the DNA of skeletal remains but these researchers developed a new computer program and were able to analyze ancient DNA from the teeth of 29 skeletons found in the mass graves at a burial site in the Mixtec town of Teposcolula-Yucundaa in Oaxaca, Mexico.
It’s interesting to also note that after the epidemics this town was relocated to a neighboring valley, leaving the mass graves at the cemetery pretty much untouched. The new computer program is being called MALT and it allows scientists to screen broadly for all bacterial DNA in the extracted samples without specifying a target organism beforehand. The program allows researchers to filter out all environmental DNA like fragments of plants or fungi. When the researchers used the program and matched up the DNA fragments with a large database containing all known environmental and pathogenic bacterial genomes they were able to find traces of Salmonella enterica Paratyphic C in 10 of the skeletal remains.
Unfortunately, the study doesn’t identify the exact source of the deadly bacteria and they can’t be certain if the pathogen was brought into Mexico by the Spanish conquerors or if it originated locally and flourished with the social changes brought on by the Spanish when they arrived in Mexico. However, what scientists do know is that this particular strain already existed in Norway long before it broke out in Mexico.
A physician in New Spain at the time named Dr Francisco Hernandez described “cocoliztli” based on autopsies he performed on the dead during the epidemics. He noted that the fevers were “contagious burning, and continuous” and mostly deadly. “The tongue was dry and black,” Dr Hernandez continued, “Enormous thirst. Urine of the colors sea-green, vegetal-green, and black sometimes passing from the greenish color to the pale.” He also noted that the pulse of the patients was fast, small, and weak or wasn’t even detectable at all. This stage was apparently followed by delirium and seizures and then hard painful nodules would appear behind the ears accompanied by chest and abdominal pain, tremors, great anxiety, and dysentery. Dr Hernandez also noted that the patient’s blood “flowed when cutting a vein had a green color or was very pale and dry.”
Researchers say that since they only study remains from one site more work needs to be don on specimens from other mass grave sites to determine is their deaths can be traced to Salmonella enterica as well. This study marks a “first step” towards understanding the diseases that caused these epidemics in Spanish colonial Mexico and elsewhere and the MALT program can also be used to identify causes of other mass deaths in other parts of the world and from other times as well.
I think this new computer program MALT is fantastic! It’s going to help us solve some of the mystery deaths seen throughout human history that up until now have been mysteries to us.
Typhoid is a horrendous disease and these epidemics in colonial Mexico do not stand alone. In 430 BC a plague hit Athens, Greece which some suspect was typhoid fever and killed 1/3 of the population. Some historians think that the English colony of Jamestown in Virginia was hit with typhoid that killed more than 6000 settlers in the New World between 1607-1624. Further, although it has long been thought that US President William Harrison died of pneumonia recent studies suggest he actually may have died from typhoid and typhoid may have been a contributing factor in the death of President Zachary Taylor as well due to the unsanitary conditions of the time in Washington DC. Also, during the US Civil War over 81,000 Union soldiers died of typhoid or dysentery which is far more than the number who died from wounds in battle. Finally, a woman named Mary Mallon is believed to have been the first person in the US to carry typhoid and, thus, she earned the nickname Typhoid Mary!!