Release date: Jan. 15, 2008
Contact: Beverly Cox Clark at 404-712-8780 or beverly.clark@emory.edu

Analysis Gives New Clues to Origin of Syphilis

Skeletal evidence is only one piece of the syphilis puzzle, says Emory graduate student Kristin Harper.

Did Columbus and his men introduce the syphilis pathogen into renaissance Europe, after contracting it during their voyage to the New World? Or does syphilis have a much longer history in the Old World? Emory University graduate student Kristin Harper has taken the first phylogenetic approach to this centuries-old debate, heading up a groundbreaking study that provides new support for the Columbus theory of syphilis's origin.

The results of the most comprehensive comparative genetic analysis ever conducted on the Treponema pallidum family of bacteria related to syphilis were published in January by the Public Library of Science's Journal of Neglected Tropical Diseases (http://www.plosntds.org).

"We concluded that the closest relative of the modern syphilis strains of bacteria were strains collected in South America that cause the treponemal disease yaws," Harper says. "That supports the hypothesis that syphilis -- or some progenitor -- came from the New World."

Harper is a Howard Hughes Medical Institute pre-doctoral fellow in Emory's Population Biology, Ecology and Evolution program. She was assisted in her research by George Armelagos, chair of Emory's Department of Anthropology; Emory anthropology undergraduate student Paolo Ocampo (now a student in Emory's School of Medicine); and scientists from the Centers for Disease Control and Prevention, the University of Toronto, the Lakeridge Health Center in Ontario and the University of Oxford.

"Syphilis was a major killer in Europe during the Renaissance," says Armelagos, a skeletal biologist whose research put him at the forefront of the syphilis debate 30 years ago. "Understanding its evolution is important not just for biology, but for understanding social and political history. It could be argued that syphilis is one of the important early examples of globalization and disease, and globalization remains an important factor in emerging diseases."

While it is generally agreed that the first recorded epidemic of syphilis occurred in Europe in 1495, controversy has raged ever since over the origin of the pathogen.

Most of the evidence in recent years has come from bones of past civilizations in both New World and Old World sites, since chronic syphilis causes skeletal lesions.

In many cases, however, skeletal analysis is inconclusive, due to problems with pinpointing the age of the bones and the lack of supporting epidemiological evidence. Further complicating the research is the fact that the family of Treponema bacteria causes different diseases that share some symptoms but have different means of transmission. Syphilis is sexually transmitted, but yaws and endemic syphilis are tropical diseases that are transmitted through skin-to-skin or oral contact.

One hypothesis is that a subspecies of Treponema from the warm, moist climate of the tropical New World mutated into the venereal subspecies to survive in the cooler and relatively more hygienic European environment.

The phylogenetic analysis of 26 pathogenic Treponema strains indicated that yaws is an ancient infection in humans while venereal syphilis arose relatively recently. The study results are especially significant due to the large number of different strains analyzed, including two never-before-sequenced strains of yaws from isolated inhabitants of Guyana's interior. At Harper's request, the Guyana samples were collected during a medical mission by Ve'ahavta, the Canadian Jewish Humanitarian and Relief Committee.

The preliminary results won the Earnest A. Hooton Prize when Harper presented them at the 2006 American Association of Physical Anthropologists meeting.

Harper is now studying a gene identified in the phylogenetic analysis that appears to be linked to sexual transmission of syphilis. "We believe it could be used as a diagnostic tool," she says. "When a child contracts a treponemal disease, in addition to treating it with penicillin, you could determine if the child may have been the victim of sexual abuse."

Harper is also researching an outbreak of treponemal disease among baboons in Tanzania, which could provide another important genetic clue to how the disease is transmitted in humans.

Emory University (www.emory.edu) is one of the nation’s leading private research universities and a member of the Association of American Universities. Known for its demanding academics, outstanding undergraduate college of arts and sciences, highly ranked professional schools and state-of-the-art research facilities, Emory is ranked as one of the country's top 20 national universities by U.S. News & World Report. In addition to its nine schools, the university encompasses The Carter Center, Yerkes National Primate Research Center and Emory Healthcare, the state's largest and most comprehensive health care system.

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