When Christopher Columbus sailed back from the New World after his historic 1492 voyage, he may have brought an enduring souvenir back with him.
So says a team of researchers who believe that syphilis first arrived in Europe on the Nina and the Pinta when Columbus and his men returned home in 1493.
The finding has so far been met with equal measures of titillation from the public and outrage from other researchers who say there is no way to conclusively make such a connection.
Still, researchers at Emory University in Atlanta, say they have managed to draw this link through the first genetic attempt to understand the history and evolution of the disease.
"Most of the previous studies on this were based on skeletal evidence, so we were trying to approach this genetically," said the study's lead investigator Kristin Harper. "And what we found was that [syphilis] came from the New World to Old World pretty recently."
"When you put that together with other documented evidence that the first European epidemic of syphilis was in 1495, it goes along with Columbian hypothesis."
The Columbian theory noted by Harper purports that syphilis was present only in the New World before Columbus' voyages and he brought it back to Europe with his crews, leading to the first recorded outbreak of syphilis in the Old World in 1495.
The other theory is that syphilis was present in the Old World before Columbus' voyage, but the disease was misdiagnosed as leprosy.
However, only a few isolated cases of pre-Columbian syphilis in the Old World have been reported, and those cases have been met with intense criticism regarding the diagnosis, dating and epidemiological context of the findings.
The Emory researchers sought to put an end to the ongoing debate on the origins of the disease by tracking where and when each of the different strains of Treponema — the pathogen that causes syphilis — evolved.
What this latest research suggests is that only the nonsexually transmitted species of Treponema existed in the Old World before Columbus' voyage to America. Columbus therefore must have first introduced the sexually transmitted syphilis strain to Europe upon his return from America.
But how could researchers have determined this? It turns out that just like the rest of us, a bacterium has genetic material. And just as we are able to take a look at our genes and trace our lineage back to our grandparents and great-grandparents, the genes in these germs can be used to trace their lineage — essentially creating a "family tree" of sorts for these bugs.
The study's investigators did just that, examining 21 genetic regions on 26 different strains of Treponema to create this family tree. They then used this template to look back in time, tracing the origins and mutation of the germ.
What they found was that the syphilis-causing strains evolved most recently of all Treponema strains and were more closely related to a strain indigenous to South America than they were to any other nonvenereal Treponema strain.
Moreover, Harper said because three out of the four genetic variants that support the relationship between the nonvenereal strains and the syphilis-causing strains were found in one small stretch of the genome, the bacterium must have mutated into the modern form of venereal syphilis in a relatively short period of time.