Ewwww! This will make you want to say "no" to casual vacation sex. Just giving you advanced notice. A rare sexually transmitted infection has popped up in the United Kingdom. Donovanosis is usually only found in tropical areas like Paupa New Guinea. The infection causes ulcers to spread on your private area. Eventually, the flesh starts to eat itself and your nether region can literally "rot away." It can spread with skin-on-skin contact from a bleeding ulcer. Most cases in the U.S. and U.K. happen when a person comes home after having unprotected sex in a country where the infection is prominent. That makes you think twice about stranger vacation sex, doesn't it? Admit it - when did you hook up on vacation with someone from another country?