The Syphilis Exception

No one doubts today that European bacteria and viruses had a ruinous effect on the Americas. So, too, did African diseases like malaria and yellow fever when they arrived. The question inevitably arises as to whether there were any correspondingly lethal infections from the Americas, payback to the conquistadors. One candidate was long ago nominated: syphilis.

Syphilis is caused by Treponema pallidum, a wormlike bacterium that writhes in corkscrew spirals on microscope slides. The disease occurs in four different forms, and syphilis researchers disagree about whether the various forms are caused by different subspecies of Treponema pallidum or whether Treponema pallidum is not actually a single species but a brace of slightly different species, each responsible for a different set of symptoms. One form of infection is bejel, which creates small, coldsore-like lesions inside and around the mouth; it mainly afflicts the Middle East. The second, yaws, found in tropical places worldwide, infects cuts and abrasions and causes long-lasting sores. Neither disease spreads to bone or nerves, and they rarely kill their victims. Syphilis, the third form, is another matter. Passed on mainly by sexual contact, it inflicts genital rashes and sores before it apparently disappears, relieving sufferers but silently—and often fatally—infecting their hearts, bones, and brains. (The fourth form, which exists mainly in Mesoamerica, is pinta, a mild skin infection.)

The first recorded European epidemic of syphilis erupted in late 1494 or early 1495. In the former year, Charles VIII of France led fifty thousand vagabond mercenaries from every alley of Europe to attack Naples, which he desired to rule. (He used mercenaries because even at the dawn of the sixteenth century most European states did not have the resources to support a standing military.) Charles conquered the city only to learn after he had occupied it for a few months that the various Italian statelets were massing against him, aided by a big contingent of Spanish troops. Struck with fear, the king ignominiously fled with his men in the spring of 1495. Both entry and exit were accompanied by sack, pillage, wanton slaughter, and mass rape. Somewhere along the way Treponema pallidum wriggled into the bloodstream of Charles’s retreating mercenaries. The most widely suggested source is their Spanish attackers, with transmission occurring via the women violated by both sides. Whatever the case, Charles’s army disintegrated as it fled, shedding companies of venereal soldiers along the way. A more effective means for spreading syphilis over a large area is hard to imagine. Within a year cities throughout Europe were banishing people afflicted with the disease.

Did Columbus bring the disease from the Americas, as the timing of the first epidemic suggests? There are three main arguments to support an affirmative answer to this question and an equal number against it. The first on the pro side is the sheer deadliness of the disease—early records indicate that syphilis then was even more ghastly than it is now. Green, acorn-size boils filled with stinking liquid bubbled everywhere on the body. Victims’ pain, one sixteenth-century observer noted, “were as thoughe they hadde lyen in fire.” The fatality rate was high. Such deadliness fits in with the notion that Treponema pallidum was new to Europe. Orthodox Darwinian theory predicts that over time the effect of most transmissible diseases should moderate—the most lethal strains kill their hosts so fast they cannot be passed on to other hosts. Thus syphilis, then wildly virulent and lethal, acted like a new disease.

A second argument is that Europeans at the time believed that the disease had “its origin and its birth from always in the island which is now named Española [Hispaniola],” as the prominent Spanish doctor Ruy Díaz de Isla put it in 1539. Díaz claimed that he had observed and tried to treat syphilis in the crew from Columbus’s first voyage, including, it seems, the captain of the Pinta. Apparently the man picked up the parasite in Hispaniola, brought it back to Europe, and died within months—but not before passing it on to some luckless bedmate. Díaz de Isla’s testimony was backed by the pro-Indian cleric Bartolomé de Las Casas, who was in Seville when Columbus returned.

Syphilis seems to have existed in the Americas before 1492—the third argument. In the mid-1990s Bruce and Christine Rothschild, researchers at the Arthritis Center of Northeast Ohio, in Youngstown, inspected 687 ancient Indian skeletons from the United States and Ecuador for signs of syphilitic disease. Up to 40 percent of the skeletons from some areas showed its presence. To nail down the chain of transmission, they subsequently discovered—working in concert with researchers from the Dominican Republic and Italy—that syphilis was equally common in Hispaniola when Columbus arrived. Indeed, the disease seemed to date back about two thousand years—it may have originated as a mutated form of yaws on the Colorado plateau.

The three main counterarguments against the America-as-origin theory are, first, that Treponema pallidum may have existed in Europe before Columbus. Archaeologists have turned up a few medieval skeletons, most of them in Britain, carrying what look like the marks of syphilis. Although pre-1492 syphilitic skeletons exist in the Americas, even a few European exemplars would undermine the Columbus-as-Typhoid-Mary case. Indeed, some medical researchers propose that syphilis has always existed worldwide, but manifested itself differently in different places. Second, the 1495 outbreak may not have been the introduction of a new disease but the recognition of an old one, which until then had been confused with Hansen’s disease (or, as it was known, leprosy). Descriptions of syphilis during and after the 1494–95 epidemic and Hansen’s before it are surprisingly similar; both were “treated” with mercury. In 1490 the pope abolished all of the leprosaria in Europe, allowing hordes of sick people to return home. Could that humanitarian gesture also have unleashed a storm of syphilis? At least some researchers think it likely.

The third counterargument is psychological. In part, as Alfred Crosby admitted, he initially devoted attention to the possible American origin of syphilis “because I was uneasy about so many diseases crossing west over the Atlantic and none going east.” He thought there must be some sort of “epidemiological-geographical symmetry.” Other historians followed suit. Later Crosby realized that examining the evidence in the hope of redressing the infectious balance was a mistake. “They want pox in Europe to balance the scales for smallpox in Mexico,” Vine Deloria Jr. told me. “They’re all hoping to find there’s a real Montezuma’s Revenge.”

Yet even if syphilis did originate in the New World, the scales would not be balanced. Syphilis is fascinating, “like all things venereal,” Crosby wrote in 2003, “but it was not a history-maker” like smallpox. Treponema pallidum, awful as it was and is, did not help topple empires or push whole peoples to extinction. “There was little symmetry in the exchange of diseases between the Old and the New Worlds,” Crosby said, “and there are few factors as influential in the history of the last half millennium as that.”