Syphilis is a sexually transmitted disease caused by a bacterium: Treponema pallidum subspecies pallidum. Its origins have been debated for many years, with some suggesting that Columbus and his crew brought the disease back to Europe from their conquests in the Americas. The disease was rampant in Europe in the late 1400s, killing as many as 5 million people.
Scientists have now reported in Current Biology, however, that syphilis, which is still a major problem today, was a problem in Europe before Columbus arrived in the Americas. Archaeological samples revealed the presence of treponematoses in human remains found in Finland, Estonia, and the Netherlands. Molecular and radiocarbon dating techniques were used to estimate the age of the microbial pathogens, which are thought to be at least 300 years old.
There are other Treponema pallidum subspecies that are pathogenic; skin infections called yaws and betel are also caused by these microbes. Yaws, which is a tropical disease that can spread through skin-to-skin contact, was also found in one of the human archaeological samples.
"Our data indicates that yaws was spread through all of Europe. It was not limited to the tropics, as it is today," noted study author Verena Schünemann, professor of paleogenetics at the Institute of Evolutionary Medicine of the University of Zurich (UZH).
Another microbe that's part of the basal treponemal lineage was identified that has not been found before and is no longer a factor in modern diseases.
"This unforeseen discovery is particularly exciting for us because this lineage is genetically similar to all present treponemal subspecies, but also has unique qualities that differ from them," said the first study author Kerttu Majander of UZH.
There seem to have been several subspecies of Treponema pallidum circulating in Europe between the 15th and 17th centuries, with some potentially overlapping in some areas, maybe even infecting the same people in some cases.
"Using our ancient genomes, it is now possible for the first time to apply a more reliable dating to the treponema family tree," said Schünemann.
A common ancestor probably began to give rise to all modern Treponema pallidum subspecies probably evolved about 2,500 years ago or more, according to this study. The common ancestor of venereal syphilis likely existed from the 12th to 16th centuries.
"It seems that the first known syphilis breakout cannot be solely attributed to Columbus' voyages to America. The strains of treponematoses may have co-evolved and interchanged genetic material before and during the intercontinental contacts. We may yet have to revise our theories about the origins of syphilis and other treponemal diseases," concluded Schünemann.
Syphilis can be treated, so some people might not be concerned about it. But it still infected about 115,000 Americans in 2018. It can cause severe organ damage and death if left untreated.
Sources: AAAS/Eurekalert! via University of Zurich, Science, Current Biology