Syphilis By Sheldon R Morris, MD, MPH, University of California San Diego Reviewed / Revised Jan 2023 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points More Information Topic Resources Syphilis—Primary (Genital... Syphilis—Primary (Anal Chancre) Syphilis—Primary (Mouth Chancre) Syphilis—Primary (Digital... Syphilis—Secondary (Body) Syphilis—Secondary (Back) Syphilis—Secondary (Hands) Syphilis—Secondary (Soles) Syphilis (Gumma) Classification of Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection.