Overview

• DNA extracted from 1,000-year-old human remains in Canada and Argentina confirms Mycobacterium lepromatosis was endemic across North and South America before Europeans arrived
• Phylogenetic reconstructions show M. lepromatosis diverged from other lineages over 9,000 years ago leading to multiple distinct branches on the American continent
• Detection of an ancient lineage in modern clinical samples indicates that one ancestral branch has persisted in North American populations to the present day
• Analyses trace the M. lepromatosis strain found in British red squirrels to a 19th-century introduction from the Americas, demonstrating intercontinental spread
• The research was conducted in partnership with Indigenous communities, ensuring respect for data sovereignty and ethical handling of ancestral remains