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Cocoliztli. This is how the Aztecs called the outbreaks that have severely impacted Mexico from 1545 to 1550, and then in 1576. According to estimates, 7 million to 17 million people would have succumbed to these two epidemic waves, likely contributing to the demise of the aztec empire.

“But the identification of the pathogen responsible for this carnage has been particularly challenging for scientists, because infectious diseases leave little traces in the archaeological”, note the NPR. analysis of theDNA drawn in the teeth of ten persons who died during the first wave allowed us to identify a culprit. It is a type of salmonella, Salmonella enterica serotype Paratyphi C, which causes a fever life-threatening.

An algorithm to the rescue

The study, conducted by an international team led by Johannes Krause, a geneticist at the Max Planck institute in Germany, was published on 15 January in the online journal Nature Ecology & Evolution. According to the researchers, the use of a new algorithm dubbed Malt has been a great help, to the extent that it was possible to analyse very small fragments ofDNA and compare to a database of genomes of all known pathogens.

“It is possible, however, that some pathogens are undetectable or completely unknown.”, emphasized The Guardian. “We can’t say with certainty that S. enterica was the cause of the epidemic cocoliztli”, specifies to the british daily Kirsten Bos, one of the authors of the study, and continues :

We believe that it should be considered as a serious candidate.”

On the other hand, states NPR, “the study does not identify the source of the bacteria, which fascinates both biologists archaeologists”. indeed, It would, in the end, to know its geographical origin, and thus whether it has been imported by the Europeans or if it is a strain of mexican that have proliferated in the favour of severe droughts, as suggested by a study published in 2002.

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