Syphilis is also known as Syph, Pox, Bad Blood. Syphilis is spread by direct contact with a syphilis sore, during oral, anal, or vaginal sex. A mother can also transfer it to her child during pregnancy.
In the early stages, Syphilis just looks like a painless rash, but if it is left untreated it can spread diseases in other organs of the body including the central nervous system. It can cause blindness, brain damage, personality changes dementia, and even death.
The sores are the first symptoms that provide an easy route of entry into the body for other viruses like HIV.
This is one small STD that can cause big problems, so make sure you go and get tested!