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The British, Germans and Italians called it the French disease. While the Poles called it the German disease, the Russians blamed the Poles. In France, it was named “Naples disease” because the first documented syphilis epidemic occurred during the French army’s occupation of Naples, Italy.
The origins of syphilis, a sexually transmitted infection that devastated 15th-century Europe and is still common today, remain unclear, difficult to study, and the subject of some debate.
One long-standing theory is that the disease originated in the Americas and migrated to Europe after expeditions led by Christopher Columbus returned from the New World; But a new study suggests the real story is more complex.
Genetic information about ancient pathogens can be preserved, extracted, and studied in bones, dental plaque, mummified bodies, and historical medical specimens; a field known as paleopathology.
The study, published Wednesday in the journal Nature, used paleopathology techniques on 2,000-year-old bones unearthed in Brazil to shed more light on when and where syphilis emerged. The study resulted in scientists finding the earliest known genomic evidence for the bacterium Treponema pallidum, which causes syphilis and two other related diseases, and is reliably dated to long before the first trans-Atlantic contacts.
“This study is incredibly exciting because it is the first truly ancient treponemal DNA recovered from archaeological human remains more than a few hundred years old,” said Brenda J. Baker, professor of anthropology at Arizona State University. was not involved in the study.
A complex disease caused by a complex bacterium
If left untreated, syphilis can cause physical disfigurement, blindness, and mental impairment. It has long been stigmatized as a sexually transmitted disease; hence the attempts of different populations to blame neighboring groups or countries for past epidemics.
Studying both the disease and the pathogen responsible for it is particularly complex, said Molly Zuckerman, professor and co-director of the New and Old World Bioarchaeology Laboratories at Mississippi State University, who was not involved in the research.
“This is the first time researchers have been able to culture T. p pallidum, even though we have known it is the cause of syphilis for over a century,” Zuckerman said in an email. “Working in the laboratory is still costly and demanding. “There are many reasons why, despite our best efforts, this is one of the least understood common bacterial infections.”
The timing and sudden onset of the first documented syphilis epidemic in the late 15th century has led many historians to conclude that syphilis reached Europe after Columbus’s expeditions. Others believe that the T. pallidum bacterium has always had a global distribution, but perhaps increased virulence after initially presenting as a mild disease.
Sheila A. Lukehart noted: “It is clear that Europeans decimated native populations by bringing a number of diseases (including smallpox) to the New World, so the hypothesis that the New World ‘introduced syphilis to Europe’ has appealed to some.” The professor emeritus of medicine, infectious diseases and global health at the University of Washington was not involved in the research.
Syphilis is closely related to but distinct from two other subspecies, or lineages, of treponemal disease, known as bejel and yaws, that have similar symptoms and are also the focus of the new research, non-sexually transmitted diseases.
The team behind the new study examined 99 bones recovered from the archaeological site known as Jabuticabeira II, in the Laguna region of Santa Catarina on the Brazilian coast. Some bones had characteristic signs of T. pallidum infection; The bacteria effectively ate away at the bones, leaving concave lesions.
Bone samples from four individuals provided enough genetic data for the team to analyze; One of these produced what study author Verena Schünemann, an assistant professor at the Institute of Evolutionary Medicine at the University of Zurich, described as a high-coverage genome, detailed enough for fine-grained studies. granular analysis.
The analysis revealed that the pathogen responsible for the lesions was most closely related to the modern subspecies of T. pallidium that causes bejel, a disease with symptoms similar to syphilis, found today in arid regions of Africa and the Middle East.
This finding adds strength to previous suggestions that civilizations in the Americas experienced treponemal infections in the pre-Columbian period and that treponemal disease was already present in the New World at least 500 years before Columbus set out.
Explanations from the bacterial family tree
Schünemann said the new findings do not mean that venereal syphilis, which caused the epidemic in the 15th century, came from America to Europe in the time of Columbus. A similar study previously conducted by his team found T. pallidum bacteria in human remains from the early modern period (from the early 1400s) in Finland, Estonia, and the Netherlands; This suggests that some forms of treponemal disease are already circulating, even if syphilis is not present. on the continent during Columbus’s voyages to the New World.
Moreover, the genome from the Brazilian sample provided a bacterial family tree stretching back thousands of years; This suggests that the T. pallidum bacterium first evolved to infect humans 12,000 years ago. Schünemann said the bacteria may have been brought to the Americas by early inhabitants who crossed from Asia to the continent.
“I think the story is much more complex than the Columbus hypothesis could imagine,” he said.
Mathew Beale, a senior scientist in bacterial evolutionary genomics at the Wellcome Sanger Institute near Cambridge, England, agreed with Schünemann’s assessment, saying in an email that the study “does not prove or disprove the fundamental tenet of the Columbus hypothesis – Columbus’s voyage.” “It led to the importation of Treponema and epidemics in the 1500s, followed by modern-day syphilis.”
“The main reason for this is that the sequenced bacteria are not direct ancestors of the strain that causes modern syphilis. …(I)t is a sister species. This means that various treponematoses were already very widely distributed around the world and may have appeared even before ancient migration and population in the Americas.” It could mean,” said Beale, who was not involved in the research.
“Alternatively, this could mean that many different treponematoses were present in the New World, and that one of them, only distantly related to the ancient genomes in this paper, was indeed imported by Columbus and his peers,” he added.
According to Lukehart, further research on ancient genomes from around the world could solve this mystery and elucidate which bacterial subspecies were present in Europe and the New World before Columbus’s voyages.
“The biggest scientific question now is not about syphilis, but about the worldwide distribution of the three subtypes, especially in pre-Columbian samples,” Lukehart said.
“The modern tools available to extract DNA from ancient samples, enrich treponemal DNA, and achieve deep sequencing of samples have rapidly increased our understanding of Treponema.”
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