They are red and open, and are deceptively painless. Treponema pallidum , a kind of bacteria . You used to be able to get it from getting a blood transfusion, but the blood supply is cleaner nowadays. You can get syphilis from other types of intimate skin contact , too.
Mothers can pass it on to their children during childbirth.
Kissing, dry humping, petting, and foreplay involve intimate contact. First, a big, open sore called a chancre forms. It is painless, and forms exactly at the point where you had first had contact with the syphilis bacteria. On both men and women, chancres can be found on the lips, tongue, and anywhere inside the mouth. It can also be found on the eyelids, face, chest, fingers, breasts, anus, and on the perineum .