When Christopher Columbus returned to Europe after discovering America, he didn't just bring back gold and other riches. He bestowed the gift of syphilis upon his native continent.

We pity Columbus Day parade organizers: How can one possibly construct a kid-friendly float with a syphilis theme?

According to research recently published in the Public Library of Science Neglected Tropical Diseases, a syphilis pandemic hit Europe after Columbus returned from his voyage. The strain resembled the type of syphilis found in South America, where Columbus and his crew had frolicked with the natives.