Pathogens—those selfish beasts—will do anything to stay alive and procreate. They force us to sneeze and contaminate the water supply with our own diarrhea, they turn ants into berries and make rodents lose their fear of cats, and—in the case of some sexually transmitted diseases like herpes and syphilis—they ooze out of open sores into the ripe bodies of the next host.
But an essay in the New York Times explains that STDs are careful to keep the grossness to a sustainable level. After all, pathogens have to make sure potential hosts still want to have sex with the current host—a lesson which syphilis learned after Columbus brought the disease to Europe. In those days, its sores dwarfed those caused by another fearsome disease—called “small pox” to distinguish it from syphilis, the “great pox.” The Times cites a description of syphilis from Ulrich von Hutten, written in 1519:
“Boils that stood out like Acorns, from whence issued such filthy stinking Matter, that whosoever came within the Scent, believed himself infected. The Colour of these was of a dark Green and the very Aspect as shocking as the pain itself, which yet was as if the Sick had laid upon a fire.”
Here’s a study that might 
