In a comprehensive genetic study, scientists have found what they say is the strongest evidence yet linking the first European explorers of the New World to the origin of sexually transmitted syphilis.
The research, they say, supports the hypothesis that returning explorers introduced organisms leading, in probably modified forms, to the first recorded syphilis epidemic, beginning in Europe in 1493.
The so-called Columbus hypothesis had previously rested on circumstantial evidence, mainly the timing of the epidemic. It was further noted that earlier traces of syphilis or related diseases had been few and inconclusive in Europe. Yet nonvenereal forms of the diseases were widespread in the American tropics.
Leaders of the new study said the most telling results were that the bacterium causing sexually transmitted syphilis arose relatively recently in humans and was closely related to a strain responsible for the nonvenereal infection known as yaws. The similarity was especially evident, the researchers said, in a variation of the yaws pathogen isolated recently among afflicted children in a remote region of Guyana in South America.
Researchers who conducted the study and others familiar with it said the findings suggested Columbus and his men could have carried the nonvenereal tropical bacteria home, where the organisms may have mutated into a more deadly form in the different conditions of Europe.
In the New World, the infecting organisms for nonvenereal syphilis, known as bejel, and yaws were transmitted by skin-to-skin and oral contact, more often in children. The symptoms are lesions primarily on the legs, not on or near the genitals.
Kristin N. Harper, a researcher in molecular genetics at Emory University who was the principal investigator in the study, said the findings supported “the hypothesis that syphilis, or some progenitor, came from the New World.”
The examination of the evolutionary relatedness of organisms associated with syphilis was reported on Monday in the online journal Public Library of Science/Neglected Tropical Diseases.
Ms. Harper, a doctoral student in the Emory department of population biology, ecology and evolution, was the lead author. Her co-authors included George J. Armelagos, an Emory anthropologist who has studied the origins of syphilis for more than 30 years, and Dr. Michael S. Silverman, a Canadian infectious diseases physician who collected and tested specimens from yaws lesions in Guyana, the only known site today of yaws infections in the Western Hemisphere.
The researchers said their study “represents the first attempt to address the problem of the origin of syphilis using molecular genetics, as well as the first source of information regarding the genetic makeup of nonvenereal strains from the Western Hemisphere.”
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