A groundbreaking study is rewriting the history of leprosy, one of the world’s oldest diseases, revealing its presence in the Americas long before European colonizers arrived. This new research indicates that a specific form of leprosy, caused by the bacterium Mycobacterium lepromatosis, was afflicting people in North and South America over a thousand years ago, challenging the long-held belief that Europeans were solely responsible for introducing the disease to the New World and shedding new light on ancient leprosy Americas.
Unearthing a Hidden History: Mycobacterium lepromatosis in the Pre-Columbian Americas
An extensive international team of scientists conducted the research, published in the journal Science. Their findings present compelling DNA evidence of Mycobacterium lepromatosis, a more recently identified species of leprosy-causing bacteria, infecting individuals in the Americas well before the 15th century. This discovery fundamentally alters our understanding of leprosy’s transcontinental journey and its ancient roots on the American continents.
Leprosy’s, also known as Hansen’s disease, destructive reputation is well-documented, even appearing in biblical texts (though some references might describe other conditions). The bacteria responsible trigger a chronic infection targeting skin and nerve cells. Symptoms like lesions and sores can take years to manifest. Without antibiotic treatment, the infection can lead to progressive, permanent damage, resulting in lifelong disabilities and severe complications.
While Mycobacterium leprae is the primary cause of leprosy, scientists discovered in 2008 that a related species, M. lepromatosis, can also cause the disease. Leprosy stemming from M. lepromatosis is considered rarer and has been predominantly identified in North and South America. Knowledge about this particular species remains limited, partly because both types of leprosy-causing bacteria are notoriously difficult to cultivate in laboratory settings, as they replicate by hijacking host cells.
The Accidental Discovery Sparking New Questions
Nicolas Rascovan, a study author from the Pasteur Institute in Paris, France, specializing in human disease evolution, and his team embarked on a deeper investigation of M. lepromatosis following an unexpected finding. “Our interest began when we unexpectedly detected M. lepromatosis DNA in the remains of an ancient individual in North America,” Rascovan told MaagX.com. “That prompted us to ask how long this pathogen had been circulating in the continent, how much spread there was before European contact, and what diversity it might still hold today.” [internal_links]
The research team analyzed hundreds of samples, including those from modern leprosy patients and ancient DNA recovered from pre-European contact human remains in the Americas. Their analysis confirmed the presence of M. lepromatosis in three ancient samples, from individuals who lived in regions corresponding to modern-day Canada and Argentina.
Rewriting Leprosy’s American Narrative
“Leprosy has long been considered a disease brought to the Americas by Europeans, which is true for the case of M. leprae,” Rascovan elaborated. “But our study shows that at least one of the two species that causes it—M. lepromatosis—was already here centuries earlier, and probably evolved locally for thousands of years.” This finding signifies a crucial shift in comprehending the historical trajectory of leprosy in the Americas.
The advent of antibiotics and improved sanitation has made leprosy uncommon in many parts of the world; for instance, only about 200 cases are documented annually in the U.S. However, it continues to be a public health concern in several countries, with over 200,000 new cases reported globally each year. The team’s research adds new layers of complexity to both the past and potential future of this ancient ailment.
Modern Implications and an Evolving Pathogen
While a specific lineage (clade) of M. lepromatosis that recently expanded is linked to most modern cases, the researchers also identified older clades. These appear to have been evolving independently in the Americas for over 9,000 years, suggesting the bacteria may have resided in yet-unidentified animal hosts. In the U.S., the classic form of leprosy (M. leprae) has occasionally been associated with exposure to armadillos. Although M. leprae causes the majority of leprosy cases worldwide, its less-known counterpart, M. lepromatosis, possesses the potential to become a more significant threat. “Given its diversity and spread, M. lepromatosis could be an emerging pathogen with dynamics different from M. leprae,” Rascovan cautioned.
The Unfolding Mystery of a Neglected Pathogen
This study has opened up new avenues for research. The team aims to identify the animal reservoirs where M. lepromatosis might have circulated for millennia and to trace its dissemination from the Americas to other global regions. Current theories suggest a strain of M. lepromatosis was transported to the British Isles around the 19th century, where it still infects red squirrels. However, its pathway to Asia, where cases have also been documented, remains unclear. “All of this suggests that this is not just a neglected disease, but a neglected pathogen—one whose history and spread are only now beginning to be understood,” Rascovan concluded.
This pivotal research not only revises the timeline of ancient leprosy Americas but also underscores the dynamic nature of pathogens and the importance of ongoing scientific inquiry. Understanding the deep-rooted history and evolutionary path of Mycobacterium lepromatosis is crucial for addressing its potential future impact on global health. For MaagX readers keen on the intersection of history, science, and health, these findings offer a compelling glimpse into how new discoveries continue to shape our understanding of the ancient world and its enduring legacies.
