Ancient DNA provides new evidence for a long-standing theory about syphilis: the origins of the “Polish disease”

The British, Germans and Italians called syphilis the “French disease.” The Poles dubbed it the German disease, while the Russians during the time of Ivan the Terrible blamed the Poles for the disease (“Polish disease”). In France, syphilis was called the “Neapolitan disease” after the French army became infected during its invasion of Naples in the first documented syphilis epidemic. The origins of syphilis, a sexually transmitted infection that devastated Europe in the 15th century and is still prevalent today, have remained obscure, 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 new research suggests the true story is more complex, CNN notes.

Genetic information about ancient pathogens can be preserved in bones, dental plaque, mummified bodies and historical medical samples, extracted and studied by specialists in a field known as paleopathology.

A study published recently in the journal Nature used paleopathology techniques on 2,000-year-old bones discovered in Brazil in an attempt to shed more light on when and where syphilis originated. As a result of the study, the scientists recovered the earliest known genomic evidence of Treponema pallidum, the bacterium that causes syphilis and two other related diseases that reliably dates back to well before the first transatlantic contact.

“This study is incredibly exciting because it is the first truly ancient treponemal DNA that has been extracted from archaeological human remains more than several hundred years old,” says Brenda Jay Baker, a professor of anthropology at Arizona State University who was not involved in the study. .

Without treatment, syphilis can lead to physical disfigurement, blindness and mental disorders, CNN recalls. As a sexually transmitted disease, it has long been stigmatized—hence past attempts by various groups to blame outbreaks on neighboring groups or countries.

It is especially difficult to study both the disease itself and the pathogen responsible for it, said Molly Zuckerman, a professor and co-director of the New and Old World Bioarchaeology Laboratories at Mississippi State University, who was not involved in the study.

“It was not until 2017 that researchers were able to culture TP pallidum for the first time, even though we have known it is the cause of syphilis for over a century,” Zuckerman said in an email. “This is still an expensive and cumbersome study in the laboratory. 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 the disease arrived in Europe after Columbus’s expeditions. Others believe that T. pallidum has always had a global distribution, but may have increased in virulence after initially manifesting as a mild illness.

“It is clear that Europeans brought a number of diseases (including smallpox) to the New World, wiping out the indigenous population, so the hypothesis that the New World ‘transferred syphilis to Europe’ was attractive to some,” noted Sheila A. Lukehart. Professor Emeritus in the Department of Medicine, Infectious Diseases and Global Health at the University of Washington, who was not involved in the study.

Syphilis is closely related to but distinct from two other subtypes or lineages of treponemal disease, non-sexually transmitted diseases that have similar symptoms known as beigeule and yaws, and were also the focus of the new study.

The team behind the new study examined 99 bones from an archaeological site known as Jabuticabeira II, located in the Laguna Santa Catarina region on the coast of Brazil. Some of the bones showed marks consistent with T. pallidum infection—the bacteria effectively eat away at bones, leaving concave lesions.

Bone samples from four individuals yielded enough genetic data for the team to analyze, with one of them showing what study author Verena Schünemann, an associate professor at the Institute of Evolutionary Medicine at the University of Zurich, describes as a high-coverage genome detailed enough for fine-grained analysis.

The analysis showed that the pathogen responsible for the lesions was most closely related to the modern T. pallidium subspecies that causes bejel, a disease found today in arid regions of Africa and the Middle East that has similar symptoms to syphilis.

This discovery confirms previous suggestions that civilizations on the American Continent encountered treponemal infections in pre-Columbian times and that treponemal disease was already present in the New World at least 500 years before Columbus sailed.

Verena Schünemann emphasizes that the new findings do not mean that venereal syphilis, which caused an epidemic in the 15th century, came to Europe from America during the time of Columbus. A similar study earlier by her team found T. pallidum bacteria in human remains from early modern Finland, Estonia, and the Netherlands (early 1400s onwards), suggesting that some forms of treponemal diseases, if not syphilis, are already were distributed on the continent during Columbus’s expeditions to the New World.

Moreover, a genome extracted from a Brazilian sample provided a bacterial family tree going back thousands of years, suggesting that T. pallidum bacteria first evolved to infect humans as early as 12,000 years ago. According to Verena Schünemann, it is quite possible that the bacteria could have been brought to America by its first inhabitants, who moved to the continent from Asia.

“I think the story is much more complex than the Columbus hypothesis ever imagined,” she said.

Matthew Beal, a senior research scientist in the department of bacterial evolutionary genomics at the Wellcome Sanger Institute near Cambridge, England, agreed with Schünemann’s assessment, saying in an email that the study “neither proves nor disproves the central tenet of the Columbus hypothesis itself – that Columbus’s voyage introduced Treponema and led to outbreaks in the 1500s and then to modern syphilis.”

“This is mainly because the sequenced bacterium is not a direct ancestor of the strain that causes modern syphilis. … She is a related species. This could mean that various treponematoses were already very widespread around the world and may even predate ancient migration and settlement of the Americas,” said Beal, who was not involved in the study.

“Alternatively, it could mean that many different treponematoses were present in the New World, and one of them, only distantly related to the ancient genomes in this paper, was actually introduced by Columbus and his colleagues,” he added.

Further research into ancient genomes from around the world may be able to solve the mystery by clarifying which subspecies of bacteria were present in Europe and the New World before Columbus’s voyages, Sheila Lukehart said. “The more important scientific question now is not syphilis, but the distribution of the three subtypes across the globe, especially in pre-Columbian specimens,” Lukehart said. “Modern tools available to extract DNA from ancient samples, enrich treponemal DNA, and obtain deep sequencing of samples have rapidly expanded our understanding of treponema.”