In 1495, a mysterious disease decimated the soldiers who had emerged victorious from the French invasion of Naples. The sexually transmitted disease, which killed many and disfigured survivors, spread easily across Europe. A century later, some estimates estimated that up to a third of the population of Paris was infected, figures that are reminiscent of those of the African countries most affected by HIV today. Many Europeans called it the French disease, the French, the Italian disease, and the Arabs, the Christian disease. It is now known that the culprit of the ailment is the bacterium Treponema pallidum and it can be treated with antibiotics, but the controversy over its origin has continued.
For a long time, Christopher Columbus and his companions to the New World were held guilty of bringing the new disease with them. The Europeans carried measles or smallpox, but the Indians got their revenge through syphilis. A 2008 work by Kristin Harper, from Emory University (USA), was one of those that tried to scientifically strengthen this idea. Comparing 26 different strains of treponemes, similar to the bacteria that cause syphilis, but that cause other ailments like yaws, Harper and his colleagues found that the bacteria responsible for sexually transmitted diseases appeared recently and that their closest relatives were found in samples collected in South America. That sign pointed to voyages of discovery as the entry point for the disease into Europe.
The hypothesis that syphilis had been on this continent for some time when Columbus left the Port of Palos has been defended by researchers such as Karl Grosschmidt and Fabian Kanz, from the Medical University of Vienna. Analyzing the human remains unearthed in the cathedral square of Sankt Pölten, in Austria, the oldest from the year 1320, they concluded that some of them had suffered from syphilis before 1492.
At the end of the 16th century, in Paris, up to a third of the population had been infected by the bacteria that cause syphilis
This week, the journal Current Biology publishes a work led by researchers from the University of Zurich (Switzerland) that presents a more complex picture. The authors, led by Verena Schünemann, studied human remains found in Finland, Estonia and the Netherlands and in many of them they found bacteria as the cause of syphilis. Both molecular dating of bacterial genomes and radiocarbon testing of the samples indicate that some of these pathogens were there in the early 15th century, long before the Columbian voyages.
Schüneman and his colleagues also found an individual who had suffered yaws. This disease is transmitted by contact with the skin, although usually not through sexual penetration, and today it is usually only found in tropical regions. One of the hypotheses that have been raised about the appearance of syphilis in Europe independently suggests that the bacterium that produces yaws became sexually transmitted upon arrival in Europe, where low temperatures and increased use of clothing made it difficult to transmission through the skin.
Schüneman does not offer a definitive answer on the guilt or not of Columbus and his acolytes in the arrival of syphilis in Europe. According to her, the strains of these treponemes “were able to co-evolve and exchange genetic material before and during intercontinental contacts”. Previous studies have observed that bacteria very similar to those that cause yaws or syphilis are found in baboons, so it would not be unreasonable to think that the first humans who colonized America thousands of years ago carried this type of bacteria with them.
In their reconstruction of the Treponema pallidum family tree , the Zurich researchers calculated that the common ancestor of the modern version of these bacteria appeared about 2,500 years ago and that the one that has the capacity to be transmitted through sex could arise more than 800 years ago . In its expansion, Columbus and the first transatlantic travelers may not be the only ones responsible for the arrival of syphilis in Europe, but the human exchanges that this incipient globalization produced could facilitate the transmission and evolution of a relatively new disease.
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