Christopher Columbus and his men may have introduced syphilis into Renaissance Europe after contracting it during their voyage to the New World, a study suggests.
However, scientists from the Emory University, Atlanta, USA, say that it will take further research to solidify the conclusion.
Researchers involved in the study called it the most comprehensive genetic analysis yet done comparing treponemes members of the bacterial family that causes syphilis and related diseases such as yaws.
Debate has raged for centuries over whether Columbus' voyages were responsible for introducing Europe to syphilis, a common venereal disease. At one time a major killer, untreated syphilis can lead to complications including mental illness and heart damage.
The first known epidemic on record of the disease then known as "evil pocks" occurred in 1495 in Europe, two years after Columbus returned from his first New World voyage.
Kristin Harper approached this centuries old debate by using phylogenetics, the study of the evolutionary relatedness between organisms, to study 26 geographically disparate strains of treponemes.
The venereal syphiliscausing strains originated most recently, and their closest relatives were strains collected in South America that cause the treponemal disease yaws.
"That supports the hypothesis that syphilis or some progenitor came from the New World," Harper says.
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 modes of transmission. Syphilis is sexually transmitted, but yaws and endemic syphilis are tropical diseases that are transmitted through skintoskin 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, syphiliscausing subspecies to survive in the cooler and relatively more hygienic European environment.
The phylogenetic analysis 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 neverbeforesequenced 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.
"Syphilis was a major killer in Europe during the Renaissance," says coauthor George 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," he added.
The study is published in PLoS Neglected Tropical Diseases