Syphilis is a bacterial infection that is passed on through either having sexual contact with a person who has a syphilis sore (ulcer) or through unsafe injecting practices. You can catch syphilis by direct contact with a syphilis sore or “chancre” (commonly a more or less distinct ulcer or sore with a hard base) through anal sex, vaginal sex, oral sex, rimming and fisting. Using condoms and gloves reduces the risk of transmission, but does not eliminate it, as they may not cover the sore. You can also catch syphilis via blood, such as sharing needles or equipment when injecting drugs.