The latest advances in ancient DNA analysis sometimes force to rewrite the history: a study has just disassembled that Europeans take leprosy to America by finding genetic samples of individuals from Argentina and Canada who suffered this disease centuries before European arrival.
LEPRA is a disease that continues to affect thousands of people worldwide. Approximately 200,000 new cases are registered every year. Until 2008 it was thought that the bacteria ‘Mycobacterium leprae’ was solely responsible for the disease, but that year another species was found that also caused it, ‘Mycobacterium lepromatosis’, identified in a Mexican patient in the United States and, later, in red squirrels in the United Kingdom in 2016.
Now, a study by scientists from the Pasteur Institute, the National Center for French Scientific Research (CNRS) and the University of Colorado (EU), in collaboration with indigenous communities and more than 40 international researchers, including archaeologists, says that it was this new bacterium found in 2008 the person responsible for the first infections in America centuries before the Europeans arrived.
The study, described this Thursday in the Science magazine, was based on the DNA analysis of about 800 samples, among ancient human remains (from archaeological excavations) and recent clinical cases that presented symptoms of Lepra.
“This discovery transforms our understanding of the history of LEPRA in America, demonstrating that there was a version of the disease that was already endemic between native populations before the arrival of Europeans,” says one of the authors Maria Lopopolo, a researcher at the Microbial Paleogenomic Laboratory of the Pasteur Institute in a statement in the center.
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Lepra: A very traveling disease
The researchers used advanced genetic techniques to rebuild the genomes of the ‘Mycobacterium leprae’ bacteria of individuals found in Canada and Argentina.
The results show that the ancient strains of the bacteria, which date from similar periods in both cases (approximately 1,000 years ago), were very similar from the genetic point of view despite the distance. And, for researchers, it is an indicative that the pathogen spread rapidly throughout the American continent in just a few centuries.
The scientists also identified several new lineages of the bacteria, including an ancestral branch that, despite having varied from known species more than 9,000 years ago, continues to infect humans today in North America, which would talk about an ancient and lasting diversification of the bacteria in the continent.
The analyzes show that the strains found in red squirrels in the United Kingdom in 2016 are part of an American lineage that was introduced into the British islands in the nineteenth century, where it would have subsequently spread.
With EFE information
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