Leprosy may have originated in East Africa, not India, as widely believed, and slave traders, not Africans, probably carried the disfiguring bacterial infection to West Africa.
Those two conclusions emerged from a new genetic analysis of leprosy bacteria, published by Colorado State University researchers and their Paris colleagues in today’s Science magazine.
“Colonialism was extremely bad for parts of the world in terms of human health,” concluded co-author Stewart Cole of the Pasteur Institute in Paris.
The bacteria that cause leprosy thrive at human skin temperature and destroy nerves, which results in muscle paralysis and skin lesions, said John Spencer of CSU, another co-author.
“You might have no control over the nerves that control your eye muscles, so your eyes will roll to the back of your head and you’ll be blind,” he said.
But those bacteria don’t jump easily from person to person, and they reproduce slowly, which has made them difficult to study in people, he said. A few decades ago, researchers discovered they could grow massive quantities of leprosy bacteria in armadillos, which have a body temperature similar to human skin temperature.
Today, CSU researchers maintain an armadillo-based database of human leprosy strains at a facility in Louisiana.
By studying tiny genetic differences among different strains of the disease, Spencer’s colleagues were able to sort out the history of leprosy, one of the oldest known human diseases.
The most ancient strain appears to be one from East Africa, they concluded. From there, the disease apparently moved to Europe and Asia, and then back to West Africa, probably carried by infected slave traders and other colonialists.
“Using modern genetic techniques, these researchers uncovered clues to the origin of a disease that, since ancient times, has been one of the most stigmatizing,” said Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, which helped fund the study.
“Their findings may help public-health officials better track and treat leprosy, which remains a significant problem in some parts of the world today,” Fauci said in a statement.
Staff writer Katy Human can be reached at 303-820-1910 or khuman@denverpost.com.