The infection was discovered in America a thousand years before Columbus arrived.

One of the biggest mysteries in the history of epidemics is whether syphilis was introduced to Europe after Columbus’s first voyage to the Americas. Now research has confirmed the presence of a treponematous disease called bejel (a syphilis-like disease) in South America at least 1,000 years before Columbus arrived. Its existence suggests that the family of bacteria that causes these diseases dispersed before the European expeditions of the 15th and 16th centuries.

This international study involves researchers from the University of Valencia and the Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (Fisabio) of the Ministry of Health and was published in the journal Nature. oldest known genome Treponema pallidum, bacteria that cause treponematoses, in prehistoric human remains from Brazil. This work, carried out from Switzerland by the University of Basel, the University of Zurich and ETH Zurich, contributes to elucidating the origins of this group of diseases.

Treponematoses are infectious diseases caused by bacteria. T. pallidum. Although endemic forms such as yaws and bejel are generally found only in developing countries, syphilis persists as a global infection. These infections have re-emerged in recent years and are largely resistant to azithromycin, which is used as an alternative treatment to penicillin, with subsequent impacts on public health.

The four bacterial genomes obtained and analyzed for this study were recovered from approximately 2,000-year-old human remains found on a burial mound in the Santa Catalina region of Brazil.

archaeogenetics

Until now, the identification of bacterial species that have caused serious infections and epidemics in the past has been mainly based on data in bone samples. Nowadays, thanks to recent advances in methods for studying ancient DNA, such as the one used in this study, it is possible not only to reconstruct ancient genomes, but also to identify the specific subspecies causing the infection. These surprising discoveries, such as the identification of a prehistoric bedel agent in a coastal American environment, highlight the potential of ancient DNA beyond inferences based on modern pathogen genomes or purely archaeological interpretations.

Discoveries like the one made in this study demonstrate the potential of studying ancient DNA to advance knowledge about modern pathogens. So much so that when analyzing one of the infectious agents discovered in Brazil, it was found to bear such a close resemblance to modern bejel strains (T. pallidum endemicum) that this subspecies appears to have remained virtually unchanged to this day.

Ancient genomes that speak to the present

“Although we cannot pinpoint the exact timing of these events, our analyzes help clarify what the evolution of these pathogens must have been, since bacteria are able to transfer genes from one to another (horizontal gene transfer or recombination) and this affects its structure. This fact therefore allows us to understand the contact that different subspecies of the same treponemal bacteria had and helps us understand their evolutionary path,” explains Marta Pla Diaz, one of the first authors of the study and a doctoral student at the Fisabio Foundation. and the University of Valencia, and is currently a researcher at the University of Basel.

In her PhD thesis in Valencia, Marta Pla developed methods for analyzing evolutionary processes such as selection, recombination and horizontal gene transfer in the genomes of ancient and modern bacteria, facilitating the study of complex data such as those included in this study.

“Including ancient genomes in the analysis is necessary to understand what factors and evolutionary processes were at work in the past, and in the case of T. pallidum“How, when and, hopefully, where, this led to the emergence of a new pathogen that, over the last five centuries, has caused a pandemic as serious as syphilis,” explains University of Valencia professor Fernando González Candelas, who is also Marta Pla’s thesis supervisor. .

As research continues and estimates improve, the goal of uncovering the origins of syphilis moves one step closer. “The origins of syphilis are still unknown, but at least we now have no doubt that infections caused by Treponema bacteria were not alien to the inhabitants of the Americas, who lived and died centuries before the first European explorers arrived on this continent.” , adds González Candelas, who also signed the article.