When Columbus returned to Europe from his voyage to America, he and his crew brought news that would reshape the world. And according to recent research, they very likely brought back something else.

Researchers affiliated with Emory University have published the most comprehensive study to date on the controversial 'Columbian' theory of syphilis and have put to rest many lingering doubts on the subject. They found that the disease, which the latest World Health Organization estimate blamed for 12 million new cases in 1999, was brought to Europe on the Niña, the only one of three ships to survive Columbus' first voyage to the West Indies. According to co-author Molly Zuckerman, the results are "pretty definitive," although she cautions that "we shouldn't close the book" on the subject.

Proponents of the theory have long known that the so-called "treponemal" bacterium that causes syphilis was present in the New World at the time of first contact, and the first European outbreak occurred in 1494. That is consistent with the Columbian theory. But that evidence was regarded as circumstantial by historical opponents of the Columbian theory, some of whom thought they had identified mentions of the disease in the Classical Greek writings of Hyppocrates.

The controversy, as it stood among contemporary scientists, arose over pre-Columbian bones found in Europe with apparent signs of syphilis. But the specimens had never been studied all together, and therefore may have been evaluated under different conditions. For this latest study, researchers compiled past reports that seemed to show pre-Columbian syphilis. They looked for telltale signs of treponemal bacteria, which include pitting and swelling in the skull and long bones. Specimens without such marks were ruled out.

Co-author Kristin Harper says that "all of the skeletons that showed definite signs of treponemal disease appeared to be dated to after Columbus returned to Europe."

So what can the 500-year-old mystery teach us today?

"Syphilis was one of the first examples of a truly global epidemic," Harper told ABC News. "I think its history demonstrates how effectively a novel pathogen can spread around the world, even without the benefit of modern travel, and also how hard it is to predict where and when a novel new infection may arise and permanently take hold in a population."

Editor's note: In previous version of this article, it was unclear whether the WHO blamed syphilis for 12 million total cases or 12 million new cases in 1999. The correct figure is 12 million new cases.

