Syphilis is a chronic infectious disease caused by the bacterium (microorganism) treponema pallidum. It is transmitted by direct contact with an infected lesion, usually through sexual intercourse. When untreated, syphilis progresses through primary, secondary and latent stages. The early stages of syphilis may not have any detectable symptoms. In some cases, symptoms can remain dormant for years. Eventually any tissue or vascular organ in the body may be affected.
Syphilis may also be acquired by the fetus in the uterus (congenital syphilis). Syphilis, especially when detected early, may be cured with appropriate treatment.