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Mystery behind the Cause of Colonial Mexican Epidemic Resolved

A new research has been conducted by an international team of researchers from the Max Planck Institute for the Science of Human History (MPI-SHH), Harvard University and the Mexican National Institute of Anthropology and History (INAH).

They used the ancient DNA and a new data processing program and identified a pathogen called as Salmonella enterica Paratyphi C. This pathogen has been spotted as the cause of enteric fever in the skeletons of victims of the 1545-1550 cocoliztli epidemics in Mexico. As part of their study the scientists examined ancient DNA extracted from 29 skeletons excavated at the site. They put to use a new computational program to characterize the ancient bacterial DNA. This technique enabled the scientists to search for all bacterial DNA present in their samples, without a need to specify a particular target in advance. This screening method unveiled strong evidences of S. enterica DNA traces in 10 of their samples. Later, a DNA enrichment method especially designed for this study was used. This helped the scientists to reconstruct full S. enterica genomes, and 10 of the individuals were found to contain a subspecies of S. enterica that causes enteric fever. It is the first time scientists have recovered molecular evidence of a microbial infection from this bacterium by using ancient material from the New World. Typhoid fever is a variety of enteric fever. In the present day it causes high fevers, dehydration, and gastro-intestinal complications. This disease is considered a major health threat all over the globe. It has caused approximately 27 million illnesses in the year 2000 alone. However, it is found that very little is known about its past severity or worldwide prevalence.

By: Anuja Arora