Overview

• Ancient DNA from remains in Canada and Argentina dating to around 1,000 years ago confirms that Mycobacterium lepromatosis was infecting people in North and South America long before European contact.
• Phylogenetic reconstructions identify multiple distinct lineages of M. lepromatosis and show that most modern strains differ only slightly from their ancient counterparts.
• Genetic links trace a lineage of M. lepromatosis to British red squirrels, indicating its introduction to the British Isles in the 19th century via transcontinental movement.
• Clinical patterns of M. lepromatosis, which target blood vessels and can spread to organs, help explain why ancient skeletal remains often lack classic leprosy bone damage.
• The project’s partnership with Indigenous communities upheld data sovereignty and ethical research practices while laying groundwork for discovering unknown animal reservoirs and improving leprosy surveillance.