Syphilis came from America went to Europe... (insert joke)

Oddly enough, research is showing that a Syphilis evolved a new transmission method in Europe: sex. In the old world it relates closely with other similar pathogens. In the New World it adapted to the environment with a new transmission method.

This means that it traveled not from Europe to America but from America to Europe.

There's a joke in here involving Europe, sex, spring break, and America... but I just can't find it.

UPDATE: Indian-giver?