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Leprosy bacterium changed little in last millennium

Genome alterations probably not responsible for decline in disease prevalence

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2:49pm, June 13, 2013

A tooth from the skull of a 600 year-old Danish leprosy victim known as Jorgen_625 contained exceptionally well- preserved DNA of Mycobacterium leprae, the bacterium that causes leprosy. Researchers compiled the organism’s genome from the DNA.

The bacterium that causes leprosy still packs the same punch it did in the Middle Ages, a study of the organism’s genome reveals.

Mycobacterium leprae causes skin sores, nerve damage and skeletal disfigurement. About 200,000 people worldwide contract leprosy each year. In early medieval Europe the bacterial infection was more common, but its incidence began to wane in the 16th century.

M. leprae has a bare-bones genome that doesn’t allow the microbe to survive outside a human or animal host. About half of the organism’s genes have been disabled and no longer make proteins. Many scientists thought this genome decay contributed to the disease’s decline in prevalence, says Patrick Brennan, a microbiologist at Colorado State University in Fort Collins.

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