A French genetics study comparing strains of leprosy-causing bacteria has revealed some surprises about how the pathogen evolved and how it was spread across the continents by human migrations. The research, led by scientists at the Pasteur Institute in Paris, appears in the 13 May issue of the journal Science, published by AAAS, the nonprofit science society.

The findings indicate that the world's existing leprosy infections are all caused by a single bacterial clone that has spread yet barely mutated for centuries. They also show that the disease may have begun in East Africa, as opposed to India as previously thought, and then spread to the other continents in part through European colonialism and later the slave trade.

One of the oldest known human diseases, leprosy is still a significant problem in parts of the developing world, especially India. According to the World Health Organization, roughly 500,000 new cases were detected in 2003. (http://www.who.int/lep/stat2002/global02.htm)

"Leprosy is still very real and devastating to patients who aren't treated appropriately. The better we can understand this pathogen's genome and the subtle differences among its various strains worldwide, the better position we'll be in to ultimately eliminate the disease," said Caroline Ash, Senior Editor at Science.

The ability to trace an infection back to a certain region may help public health workers monitor the movement of the disease over time and determine the geographic source of new infections, said study author Stewart Cole of the Pasteur Institute.

Historically, it's been thought that leprosy originated in the Indian subcontinent and was then introduced to Europe by Greek soldiers returning from the Indian campaign
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Contact: Jessica Lawrence-Hurt
jlawrenc@aaas.org
1-202-326-7088
American Association for the Advancement of Science
12-May-2005