Syphilis is a sexually transmitted disease caused by the bacterium Treponema pallidum. Primary syphilis presents as a small painless open sore 3 to 6 weeks after exposure. Although the lesion heals within 6 to 8 weeks, the untreated organism will continue to multiply unchecked, causing many complications. Infection may last for 30 years or more and result in severe neurological complications.
Review Date: 7/31/2016
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.