Syphilis most likely originated in the Americas and arrived in Europe with Columbus’s crew in 1493. That’s the short answer, but the full story involves centuries of debate, ancient DNA, a devastating military outbreak, and a bacterium that may have evolved its sexual transmission strategy only after crossing the Atlantic.
The Naples Outbreak of 1495
The first recorded epidemic of syphilis in Europe erupted during a war. At the end of 1494, King Charles VIII of France marched into Italy with an army of 25,000 men. By February 1495 his forces had entered Naples. When Italian physicians examined French soldiers after the Battle of Fornovo in July 1495, they described something they had never seen before: a generalized eruption of pustules, spread through sexual contact, more terrifying than leprosy, and frequently fatal.
The disease tore through Europe with extraordinary speed. Both armies relied on mercenaries recruited from across the continent. Over the 30 years of fighting that followed, soldiers returned home, married, visited prostitutes, and committed sexual violence, carrying the infection with them. Within a few years, syphilis had reached virtually every corner of Europe. Early syphilis was also far more aggressive than the disease we know today. It spread faster, progressed more rapidly, and killed more often.
The Columbian Hypothesis
The timing was hard to ignore. Columbus returned from his first voyage to the Caribbean in 1493, and just two years later, a terrifying new disease appeared in Europe. This connection forms the basis of what historians call the Columbian Hypothesis: that Columbus’s crew brought a treponemal infection back from the New World.
Several lines of evidence support this idea. Unmistakable bone lesions caused by treponemal disease appear at archaeological sites throughout the Americas stretching back thousands of years. In contrast, when researchers examined large collections of pre-Columbian skeletons from Europe and North Africa, they found no definitive treponemal lesions at all. Those lesions suddenly appear in European remains only after 1493. A German woodcut dated August 1, 1496, just three years after Columbus’s return, is one of the earliest known illustrations of the disease, reinforcing how quickly it emerged.
Some earlier claims of pre-Columbian syphilis in Europe turned out to be unreliable. When radiocarbon dates on European skeletons were corrected for the marine reservoir effect (a technical adjustment needed when someone’s diet included a lot of seafood, which skews carbon dating), every confirmed case of Old World treponemal disease overlapped with or postdated 1493.
What Genetics Reveal
DNA analysis has added a powerful layer to this debate. Genetic sequencing of 21 different regions of the syphilis bacterium showed that syphilis strains diverged more recently than their non-sexually-transmitted relatives. The closest genetic relatives of syphilis turned out to be strains of yaws, a skin-to-skin tropical infection, collected from indigenous inhabitants of Guyana in South America.
A major 2024 study published in Nature pushed the story back even further. By analyzing ancient DNA from archaeological remains, researchers concluded that all genetically typed strains of the syphilis family of bacteria appear to stem from an origin in the Americas during the middle Holocene, roughly 5,000 to 9,000 years ago, possibly starting as a zoonotic infection (one that jumped from an animal host that hasn’t yet been identified). Both syphilis and yaws then underwent a dramatic increase in genetic diversity around 500 years ago, lining up precisely with the era of European contact and global exploration.
How a Skin Disease May Have Become Sexual
One of the most interesting wrinkles in the story is that syphilis may not have always been a sexually transmitted disease. In the Americas, related treponemal infections like yaws spread through casual skin-to-skin contact, typically in warm, humid climates where people wore little clothing. When Columbus’s crew carried the bacterium to Europe, it encountered a very different environment: cooler temperatures, more clothing, and less exposed skin.
Under these new conditions, the bacterium’s old transmission strategy no longer worked well. The modified Columbian Hypothesis proposes that the organism adapted by exploiting one of the few remaining routes of sustained skin-to-skin contact available in a clothed, cooler population: sex. In other words, the shift to sexual transmission may not have happened in the Americas at all. It may have been an evolutionary response to European conditions.
Everyone Blamed Everyone Else
The disease didn’t even have a fixed name for decades. Every nation blamed its neighbor. The Italians called it “the French disease.” The French called it “the Neapolitan disease.” The Russians blamed the Poles, and the Poles blamed the Germans. The name “syphilis” didn’t stick until 1530, when the Italian physician and poet Girolamo Fracastoro published a narrative poem called “Syphilis sive morbus gallicus” (“Syphilis, or the French Disease”). In the poem, a shepherd named Syphilus insults the sun god of Haiti. As punishment, the god sends a plague to the island, and Syphilus becomes its first victim. The fictional shepherd’s name eventually became the universal term for the real disease.
What the Evidence Points To
For centuries, the origin of syphilis was genuinely debatable. But modern evidence has tipped the scales heavily toward the Americas. Ancient DNA places the entire bacterial family’s origin in the Western Hemisphere thousands of years before Columbus. Skeletal evidence shows clear treponemal disease in the pre-Columbian Americas but none in Europe before 1493. Genetic analysis identifies South American yaws strains as syphilis’s closest relatives. And the first European epidemic appeared within two years of Columbus’s return, spreading outward from exactly the ports and armies connected to transatlantic contact.
The remaining uncertainty is in the details. Was the bacterium already sexually transmitted before it crossed the ocean, or did it evolve that capability in Europe? Did it arrive with Columbus’s first voyage specifically, or through other early contact? These questions are still being refined by ancient DNA research. But the broad answer is increasingly clear: syphilis came from the New World to the Old, and it transformed into the disease we know today in the years immediately following 1493.