Skeletal analysis shows the oldest strains of the disease came from Europe, the oldest from Greater Chesterford, Essex circa 500AD

Leprosy may have originated in Europe rather than Asia, according to the largest study to date on ancestral strains of the disease.

The study has revealed that more leprosy strains than expected were present in medieval Europe, prompting scientists to reconsider the origins and age of the devastating disease.

“For centuries there has been a question mark over where leprosy originated; most assumptions believing it started in China and the Far East,” said Helen Donoghue, a co-author of the latest work and scientist at University College London. “This latest research shows all the strains of the leprosy bacterium, were in fact present in medieval Europe, which strongly suggests leprosy originated much closer to home, possibly in the far south east of Europe, or western Asia.”

Leprosy is one of the oldest recorded and most stigmatised diseases in human history. It was prevalent in Europe until the 16th century and is still endemic in many countries, mainly in equatorial regions, with over 200,000 new cases reported annually.

Facebook Twitter Pinterest Verena Schuenemann examines the skull of a person who had leprosy the palaeogenetics laboratory at the University of Tuebingen. Photograph: Johannes Krause/University of Tuebingen

The scientists examined approximately 90 skeletons with deformations characteristic of leprosy, that were found in Europe and date to between 400 AD to 1400 AD.

From the fragments they reconstructed 10 new genomes - complete genetic codes - of medieval Mycobacterium leprae, the bacteria that causes leprosy. Previously only one or two strains were known to have been circulating in medieval Europe and newly discovered diversity suggests the disease must be at least a few thousand years old.



The new analysis also included the oldest known strain, extracted from skeletal remains found in Great Chesterford, Essex, and dated to between 415-545 AD. This strain was also revealed to be the same as that found in modern-day red squirrels, hinting that the disease may have been introduced to Britain through the squirrel fur trade.

Professor Johannes Krause, the study’s senior author and a director at the Max Planck Institute for the Science of Human History in Germany, said the team were now turning to even older skeletons in an attempt to corroborate written records of leprosy cases dating back 2,000 years. “Having more ancient genomes in a dating analysis will result in more accurate estimates,” he said.

The findings are published in the journal PLOS Pathogens.

