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One of the oldest diseases of humanity: did leprosy develop in Europe?


Leprosy could originate in Europe

In this country, leprosy has long been considered extinct. In other regions of the world, however, the infectious disease still poses a great danger to humans. Researchers have now found indications that the origins of the disease could be in Europe.

Around 200,000 new cases every year

Leprosy was widespread in Europe until the 16th century, but today the disease is almost eradicated in countries with developed health care. In some regions of the world, however, it still poses a major health risk. Worldwide, more than 200,000 new cases are reported every year. New knowledge about the disease is still being gained. An international team of researchers recently reported on studies that showed that leprosy changed the genetic makeup of all Europeans. And now scientists from Germany and Switzerland have found evidence that the origins of the disease could be in Europe.

New clues to the history and origin of the disease

Leprosy is one of the oldest known diseases in human history. Sick people were and are exposed to severe stigmatization.

The main cause of the disease is the bacterium Mycobacterium leprae.

However, contrary to previous beliefs, not only two, but significantly more leprosy strains were common in Europe in the Middle Ages, as an international team of researchers with the participation of the Max Planck Institute for Human History and the Universities of Tübingen and Zurich found.

These results give the scientists new clues to the history and origin of the disease.

Her study was recently published in the technical journal "PLOS Pathogens".

Medieval genomes reconstructed

The oldest sequenced genome to date comes from one of the oldest known leprosy cases in Great Britain, from Great Chesterford in England, and could be dated from AD 415 to 545.

The research team from Germany and Switzerland has now examined samples from around 90 individuals from all over Europe who showed the bone deformations characteristic of leprosy.

Ten medieval genomes were reconstructed from these samples, which date from around 400 to 1400 AD. Overall, the genomes include all known strains of the leprosy pathogen, including those that occur today in Asia, Africa or North and South America.

"In some cases, we have isolated very different strains of leprosy from bone material from the same cemetery," reports the first author of the study, Professor Verena Schünemann, who recently moved from the University of Tübingen to the University of Zurich.

This demonstrates particularly well the diversity of the leprosy strains that were then circulating on the continent.

The oldest genome of a leprosy pathogen to date

"We found much more genetic diversity among leprosy pathogens in ancient Europe than expected," summarizes the main author of the study, Professor Johannes Krause, director at the Max Planck Institute for the History of Humanity and research group leader at the University of Tübingen.

"All known leprosy strains occurred in medieval Europe, which suggests that leprosy must have been widespread in Asia and Europe since ancient times, and that the disease could have its origin in western Eurasia."

The oldest reconstructed genome of M. Leprae from England belongs to the same leprosy strain that was discovered in squirrels living today.

"This supports the hypothesis that squirrels and the trade in their skins were factors in the spread of leprosy among medieval people in Europe," says Krause.

Most red squirrels in the British Isles are still infected with leprosy today.

Leprosy bacteria may have been around much longer than expected

“The dynamics of the transmission of leprosy pathogens in human history has not been fully clarified. It is also still unclear exactly where the leprosy originally came from, ”says Schünemann.

"We have written evidence of pre-Christian leprosy cases, but we have not yet had the samples to confirm this at the molecular level."

The new study results lead to the assessment that leprosy bacteria have existed much longer than expected. They are at least a few thousand years old.

“In the next step, we want to look for even older samples of bones deformed by leprosy. Well-established methods are now available for identifying potential leprosy cases, ”explains Krause. (ad)

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