Syphilis is a sexually transmitted disease caused by infection with the Treponema pallidum bacteria. Transmitted through personal contact, it usually first appears in the genitals or on other parts of the body that have had contact with an infected person.

Syphilis can be successfully treated with antibiotics. However, if left untreated, it can eventually infect the heart, brain and central nervous system.

Syphilis progresses in three stages. Primary syphilis, the first stage of the disease, often appears as a single non-painful ulcer or sore on the genitals. Secondary syphilis may appear weeks later and can present with a variety of symptoms, including rashes, wartlike areas, swollen lymph nodes and hair loss.

For both primary and secondary syphilis, symptoms disappear without treatment. However, it is important to note that people are still infected and can transmit the disease at this time. Every person with these stages of syphilis does not progress to the succeeding tertiary stage. After the secondary stage, syphilis enters a latent period, which may last for years or decades.

Tertiary syphilis, when it appears, includes symptoms that affect many body systems and can lead to loss of mental functioning (dementia) and death. Treatment at this stage can stop the infection, but cannot reverse damage to the organs.

Syphilis can also be transmitted during pregnancy or childbirth from an infected mother to her unborn infant (congenital syphilis). The disease may cause miscarriages or stillbirths. In surviving infants, complications of congenital syphilis may include blindness, deafness, neurological problems and abnormalities of the teeth and nose.

Once the disease is diagnosed, typically by examination of tissue samples and blood tests, and the stage of the disease is determined, syphilis is treated and cured with antibiotics. The risk of syphilis transmission can be reduced by using safe sex practices, such as using latex condoms and avoiding multiple sex partners or high-risk sex partners.