{"id":569213,"date":"2025-11-21T19:13:13","date_gmt":"2025-11-21T22:13:13","guid":{"rendered":"https:\/\/revistapesquisa.fapesp.br\/?p=569213"},"modified":"2025-11-21T19:13:13","modified_gmt":"2025-11-21T22:13:13","slug":"bacteria-that-causes-leprosy-was-present-in-the-americas-before-the-europeans","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/bacteria-that-causes-leprosy-was-present-in-the-americas-before-the-europeans\/","title":{"rendered":"Bacteria that causes leprosy was present in the Americas before the Europeans"},"content":{"rendered":"

The history of leprosy in the Americas runs deeper than once thought, according to research published this May in Science<\/em>. Well over a millennium ago\u2014before European colonization\u2014the bacterium Mycobacterium lepromatosis<\/em> likely spanned the entire continent.<\/p>\n

That\u2019s a notable new finding: before the bacterium was first described in 2008, scientists recognized only one main cause of the disease, M. leprae<\/em>, which still accounts for roughly 200,000 new cases globally each year. This well-known species is believed to have reached the Americas in the late 1400s, carried by Europeans and enslaved Africans. That part of the story hasn\u2019t changed.<\/p>\n

But a new layer was added in 2018, when Argentine geneticist and bioinformatician Nicol\u00e1s Rascovan\u2014now at France\u2019s Pasteur Institute\u2014detected M. lepromatosis<\/em> in ancient DNA from a human sample excavated in Canada and stored at the Canadian Museum of History. More recently, Rascovan examined samples housed in Argentina\u2019s Museum of La Plata, taken from two Patagonian archaeological sites. With the consent of local Indigenous communities, he sequenced them and again found genetic traces of the same bacterium. Put together, the evidence suggests that a thousand years ago, M. lepromatosis<\/em> was present in both the far north and the far south of the Americas. Which makes it hard to imagine it didn\u2019t also exist across the 6,000 miles in between.<\/p>\n

\u201cWe also found M. lepromatosis<\/em> in a modern sample from Brazil using PCR,\u201d Rascovan said in an email to Pesquisa FAPESP<\/em>, \u201cthough we couldn\u2019t recover full genomic sequences. Both the new study and existing evidence from Brazilian patients hint that the bacterium\u2019s reach\u2014past and present\u2014may be far broader than thought.\u201d To close those knowledge gaps, Rascovan is calling for wide-scale mapping to chart the bacterium\u2019s genetic diversity over time. \u201cWe hope our work encourages dermatologists, hospitals, and research groups to invest more in tracking and detecting this pathogen\u2014not just in people, but in animals as well.\u201d<\/p>\n

For now, the data is insufficient to reconstruct the pathogen\u2019s migration history through the continent. The bacterium may have crossed over from Siberia with the first human settlers more than 10,000 years ago, moving south from North America. Or it may have jumped to those early Americans from animals already living here. Outside the Americas, M. lepromatosis<\/em> has only been found in red squirrels in the UK. One speculative theory is that it arrived within the last three centuries via a different squirrel species introduced from the US. \u201cOr through some other host\u2014humans included,\u201d Rascovan says.<\/p>\n

The team analyzed 389 ancient samples\u2014some newly sequenced, others drawn from public genomic databases\u2014plus 408 modern samples from leprosy patients in the US, Mexico, French Guiana, Brazil, and Paraguay. In 36 of those modern cases\u2014most from Mexico\u2014the pathogen was M. lepromatosis<\/em>. One was from Brazil\u2019s Pernambuco State.<\/p>\n

Most of the Brazilian cases were from Par\u00e1 and Amazonas, where dermatologist and leprosy specialist Claudio Salgado heads a research team at the Federal University of Par\u00e1. Salgado stresses that ongoing surveillance is key\u2014without it, they would not be able to contribute data to continent-wide studies like Rascovan\u2019s. Brazil ranks second only to India in leprosy cases. In 2023, according to the Ministry of Health, the country logged nearly 23,000 new diagnoses\u2014a 16% jump from 2022. Most cases cluster in Brazil\u2019s North and Midwest. The disease first shows itself on the skin\u2014patches, nodules, and numb areas\u2014but it can also attack the nervous system, causing overall fatigue and physical disabilities.<\/p>\n

Salgado says it\u2019s urgent to adjust diagnostic protocols so they also search for M. lepromatosis<\/em>. Scientists still don\u2019t know how symptoms might differ from those of leprosy caused by its far more common cousin, M. leprae<\/em>. For Salgado, different bacterial species could help explain why the disease looks different from patient to patient\u2014and why standard treatments sometimes fall short. He also points out that the main antibiotic regimen hasn\u2019t changed in decades. \u201cBacteria evolve. They develop resistance,\u201d Salgado warns.<\/p>\n

\"\"

Nicol\u00e1s Rascovan\u2009\/\u2009Pasteur<\/span>A tooth unearthed from an archaeological site in Argentina, used to extract ancient DNANicol\u00e1s Rascovan\u2009\/\u2009Pasteur<\/span><\/p><\/div>\n

Leprosy remains very much a neglected disease, with the burden falling largely on people living in poverty and social exclusion, says veterinarian Patricia Rosa of the Lauro de Souza Lima Institute in Bauru, S\u00e3o Paulo State, a coauthor of the study and collaborator with Salgado\u2019s team. \u201cLeprosy doesn\u2019t kill, but it\u2019s wrapped in stigma\u2014which may be why it draws so little funding,\u201d Rosa explains. \u201cThe problem is that the damage it causes to the body can become chronic.\u201d<\/p>\n

Rosa\u2019s team investigates Mycobacterium leprae<\/em> by infecting laboratory mice to determine how the disease progresses and how the body responds to treatment, and also to cultivate bacterial strains that can\u2019t be grown in artificial media.<\/p>\n

Animal studies like these also shed light on how the disease circulates. \u201cIf we don\u2019t know which other hosts are out there, we can\u2019t break the chain of transmission,\u201d Rosa notes. Across Brazil, research teams are hunting for animal reservoirs of both Mycobacterium<\/em> species. One such effort is led by epidemiologist Rita Donalisio at the University of Campinas (UNICAMP), who was not involved in the Science<\/em> paper. In a 2024 Acta Tropica<\/em> article, Donalisio\u2019s team reported on 78 armadillos collected as roadkill during a 40,000-kilometer trek across every Brazilian biome. \u201cArmadillos are a well-known leprosy reservoir,\u201d Donalisio says. She was disappointed not to find M. lepromatosis<\/em>, though M. leprae<\/em> turned up frequently in the animals. \u201cThat matters,\u201d she adds, \u201cbecause in many regions people have close contact with armadillos\u2014whether for food or to use their shells.\u201d<\/p>\n

Donalisio notes that Brazil has made little effort to test specifically for M. lepromatosis<\/em>. Because its symptoms mirror those of M. leprae<\/em>, she says, wider use of molecular diagnostics is essential. For her, the finding that M. lepromatosis<\/em> was already in the Americas before Columbus not only deepens scientific understanding of the bacterium but also strengthens the case that animal reservoirs exist and must be identified. \u201cFrom a One Health perspective, using sentinel animals in disease surveillance is a useful way to flag when a pathogen is active in a given region,\u201d she says.<\/p>\n

More than just filling in knowledge gaps, the Science<\/em> article reveals how much there is still to discover. Rascovan, of the Pasteur Institute, suspects there may be undiscovered Mycobacterium<\/em> species still circulating. \u201cIn our study we found extremely ancient and rare M. lepromatosis<\/em> lineages,\u201d he says, \u201cwhich hints that other, unidentified species could be circulating on the continent\u2014perhaps hidden in animal hosts or in places where genetic testing isn\u2019t routinely done.\u201d<\/p>\n

His team also uncovered an evolutionary split of nearly a million years between M. leprae<\/em>\u2014likely originating in Eurasia\u2014and M. lepromatosis<\/em>, which appears to have arisen in the Americas. \u201cThat forces us to rethink when and where this divergence happened, whether other species or subspecies have split off since, and where they might be hiding today.\u201d Rascovan closes with a reminder: this research confirms earlier evidence that M. leprae<\/em> arrived with Europeans and had a significant impact on Indigenous peoples.<\/p>\n

The story above was published with the title “Pre-Columbian leprosy<\/strong>” in issue 353 of July\/2025.<\/p>\n

Scientific articles<\/strong>
\nLOPOPOLO, M. et al<\/em>. Pre-European contact leprosy in the Americas and its current persistence<\/a>. Science<\/strong>. Online. May 29, 2025.
\nMONSALVE-LARA, J. et al<\/em>. Prevalence of Mycobacterium leprae<\/em> and Mycobacterium lepromatosis<\/em> in roadkill armadillos in Brazil<\/a>. Acta Tropica<\/strong>. Vol. 258, 107333. Oct. 2024.<\/p>v<\/p>\n","protected":false},"excerpt":{"rendered":"Mycobacterium leprae<\/em>, the main species, was brought over by the Europeans, but M. lepromatosis<\/em> had already been on the continent for at least 1,000 years","protected":false},"author":3,"featured_media":569218,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[159],"tags":[202,229,237,260],"coauthors":[1601],"class_list":["post-569213","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science","tag-archaeology","tag-epidemiology","tag-genetics","tag-public-health"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/569213","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=569213"}],"version-history":[{"count":2,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/569213\/revisions"}],"predecessor-version":[{"id":569832,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/569213\/revisions\/569832"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/569218"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=569213"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=569213"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=569213"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=569213"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}