Aztec ‘Black Death’ may have been caused by salmonella – research
In the 100 years following the Spanish conquest of Mexico, the native population fell from approximately 25 million to 1 million. The vast majority died in a single outbreak in the 1540s and now, new research may finally have identified why.
Most of the pathogens responsible for outbreaks in Latin America during this period remain unknown and debate in the scientific community is rife with suspects ranging from measles, smallpox and typhus to a viral hemorrhagic fever.
By extracting and sequencing the DNA from the teeth of 29 people buried at a grave site in Oaxaca, Mexico, a team of scientists from the Max Planck Institute for the Science of Human History were able to reconstruct the genome of the Salmonella enterica strain known as Paratyphi C.
Today this Paratyphi C bacterium causes enteric fever, mostly in the developing world, which can kill 10 to 15 percent of people infected if left untreated, according to Nature. However, in the 16th century, native Aztec populations would not have developed any kind of resistance to this particular bacterium.
The ‘cocoliztli,’ or ‘pestilence’ in Nahuatl, the Aztec language, that took place between 1545 and 1576 is believed to have killed between 7 and 18 million people, with researchers from the National Autonomous University of Mexico (UNAM) in Mexico City drawing comparisons to the Black Death that struck Eurasia in the 14th century.
“The epidemic of cocoliztli from 1545 to 1548 killed an estimated 5 million to 15 million people, or up to 80 percent of the native population of Mexico,” wrote Dr. Acuna-Soto, a professor of epidemiology on the Faculty of Medicine at UNAM. “In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death of bubonic plague.”
Given the chaos and societal breakdown that ensued throughout the Spanish conquest, the theory that the strain of salmonella could have killed so many people in such a short space of time has merit, as Paratyphi C is typically transmitted through fecal material.
Not everyone is entirely convinced, however, as María Ávila-Arcos, an evolutionary geneticist at UNAM, notes that the method used would not have detected a virus, for example, according to Nature.
Johannes Krause, who led the team from the Max Planck Institute, will continue the search for ancient pathogens in Caribbean burial sites which may provide more conclusive evidence to support the salmonella theory.