Leprosy still afflicting humans, relatively unchanged

Five medieval skeletons, recovered from Scandinavia and Britain, have provided information on leprosy’s trajectory over the last millennia. Apparently, the disease hasn’t changed all that much.

A group of international researchers used the human remains to reconstruct entire genome sequences of Mycobacterium leprae. The researchers compared those results to 11 strains found in modern biopsy samples and learned that only about 800 mutations occurred among the 16 studied ancient and modern genomes.

A recent Huffington Post article examines the findings and their implications. It quotes Arizona State University professor Anne Stone, a specialist in anthropological genetics.

“This study provides insight into how the European strains of leprosy (now extinct) relate to those found in other parts of the world,” says Stone. “Surprisingly, it appears to have ‘jumped’ into humans [from other animals] relatively recently.”

It appears that all strains probably shared a common ancestor sometime in the last 4,000 years. Currently, around 200,000 people become infected annually.

Another discovery is that the DNA of M. leprae degrades slower than human DNA. This is possibly due to the thick, waxy cell wall of the bacteria. The slow degradation suggests that it may be possible to extract and study samples of M. leprae DNA from the time of the disease’s origin.

Stone, who is a professor in the School of Human Evolution and Social Change in the College of Liberal Arts and Sciences, oversees the Laboratory of Molecular Anthropology. One of the lab’s foci is researching the co-evolutionary history of mycobacteria and human and non-human primates.