Syphilis is a sexually transmitted infection ... Syphilis is a sexually transmitted infection (STI). There are four stages of the disease: primary, secondary, latent, and tertiary (also known as neurosyphilis). Primary syphilis is the first stage of the disease. It causes one or more small, painless sores in or around the genitals, anus, or mouth. #syphilis #usmle #kaplanmedical #medstudent A post shared by Simon R. Downes, PhD, MS2 (@med_school_radio) on Feb 14, 2018 at 8:59am PST