According to the study authors, the results of their genetic research reveal that the syphilis strains appeared most recently and are most closely related to strains that cause yaws in South America.
But in a twist, the study results also suggested that yaws first appeared not in the New World but in the Old World, Harper said.
In essence, she said, the theory goes something like this: Yaws appeared in Africa and eventually made its way to South America and the New World as humans migrated. Then the germs made their way to Europe with the help of sailors and may have evolved into the venereal disease known as syphilis, perhaps because of different environmental conditions.
"It's especially neat when I think about contacts between Europeans and Native Americans," Harper said. "As far as diseases go, it seemed like a one-way street: Europeans brought measles and smallpox (to the Indians). But this is an example of disease going the other way. That seems kind of fair."
The findings are published in the Jan. 15 issue of the Public Library of Science Neglected Tropical Diseases.
The new research makes sense to Dr. Bruce Rothschild, professor of medicine at the Northeastern Ohio Universities College of Medicine, who's studied the evolution of syphilis by examining skeletal remains.
"It confirms everything we've done," he said. "When you've got two sets of totally different diagnostic techniques that come up with the same answer, that really increases the power of the technique."
Learn more about syphilis from the U.S. Centers for Disease Control and Prevention.
SOURCES: Kristin Harper, graduate student, Emory University, Atlanta; Bruce Rothschild, M.D., professor of medicine, Nort
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