Congenital Syphilis What is syphilis? Syphilis is a bacterial infection, caused by the bacteria Treponema pallidum. It is passed on when a person comes in contact with a syphilitic sore, known as a chancre—typically during vaginal, anal, or oral sex. What is congenital syphilis? Congenital syphilis occurs when syphilis is passed to a fetus during pregnancy. Syphilis during
