Scientists have uncovered compelling evidence that leprosy, caused by the bacterium *Mycobacterium lepromatosis*, was already present in the Americas long before the arrival of European explorers and settlers. This revelation, made public in a recent study conducted by researchers from the Institut Pasteur in Paris, France, and the University of Colorado, challenges the long-accepted narrative that leprosy was introduced to the New World by European colonizers. Instead, the findings suggest that the disease had been endemic among Indigenous populations for centuries prior to contact with Europeans.
The groundbreaking discovery was made possible through advanced genetic analyses of ancient DNA samples from Indigenous remains in Argentina and Canada, as well as modern medical cases showing signs of leprosy. Researchers found that the two strains of *Mycobacterium lepromatosis* identified in these locations are genetically close within the *Mycobacterium* genome family tree, indicating that the bacterium spread rapidly across North and South America. This suggests that the disease had already established itself as a significant health concern for Indigenous peoples before European colonization.
Dr. Maria Lopopolo, the lead author of the study and a researcher at the Institut Pasteur’s Laboratory of Microbial Paleogenomics, highlighted the implications of the discovery for historical and medical understanding. “This discovery transforms our understanding of the history of leprosy in America,” she said. “It shows that a form of the disease was already endemic among Indigenous populations well before the Europeans arrived.”
Collaboration with Indigenous communities and international institutions played a critical role in the study, which involved analyzing over 800 DNA samples from ancient human remains and recent medical cases. Such partnerships allowed scientists to gain insights into the long-term presence and evolution of *Mycobacterium lepromatosis* in the region. Nicolás Rascovan, another lead author of the study, noted that the research opens new avenues for understanding the global distribution of pathogens and the potential for unknown animal reservoirs to contribute to the spread of leprosy.
The Centers for Disease Control and Prevention (CDC) provides essential information on leprosy, describing it as a chronic infectious disease that can damage nerves, skin, and eyes. While treatable with antibiotics, the disease remains relatively rare, with approximately 225 cases reported in the United States and 250,000 globally. The new findings from the study not only reshape the historical narrative of leprosy but also underscore the importance of ongoing research into the origins and evolution of infectious diseases.