From the wired.com article:
Diseases carried to North America by Spanish explorers killed millions of the continent’s original inhabitants, but the trip cut both ways: scientists say Christopher Columbus took syphilis back to Europe.
In a study published in the January 14 issue of the journal Public Library of Science Neglected Tropical Diseases, Emory University geneticists studied 26 strains of treponema, the bacterial genus to which the infamous venereal disease belongs. After comparing their differences and evolutionary history, they decided that modern syphilis-causing strains most closely resembled those found in South America.
The findings give ammunition to adherents of the so-called Columbian theory of syphilis, which holds that the disease arrived in Europe with Columbus. Their opponents point to earlier European evidence, especially syphilitic lesions in skeletons from a 14th century English monastery, as absolving the notorious explorer of this particular scourge.
This probably won’t settle the debate, but both sides do agree on one basic fact: a pandemic of syphilis hit Europe shortly after Columbus’ return, and it changed the course of history.
Read the article here.