Leprosy’s Roots Traced to East Africa, Not India

A genetic study of leprosy has found that the bacterium behind the disfiguring disease probably originated thousands of years ago in East Africa, rather than India, as previously assumed.

The study, in the current issue of the journal Science, looked at 175 samples of the leprosy microbe from 21 nations.

The researchers found that leprosy had changed little over thousands of years -- all cases fit into four subtypes. By tracking the subtypes, the team of researchers from around the world was able to construct a rough map of how the disease spread.

Leprosy is an ancient disease of the skin and nervous system. It passes from person to person through sustained close contact. Half a million cases were detected worldwide in 2003.

Historians had originally thought that the disease was carried out of India and into Europe by Greek soldiers returning from Alexander the Great’s Indian campaign about 325 BC.

But the geographic distribution of subtypes strongly suggested that the disease instead traveled from East Africa to Europe and North Africa via traders and colonists, said lead author Marc Monot, a researcher at the Pasteur Institute in Paris.

Leprosy probably reached West Africa through commerce and colonialism within the last 500 years, the researchers said.

The slave trade brought the disease to the Americas in the 18th century, the study said.