Definition of Syphilis - primary:

Syphilis is a frequently diagnosed sexually transmitted disease.

Causes, incidence, and risk factors:

Syphilis is a sexually transmitted, infectious disease caused by the spirochete Treponema pallidum. This bacterium causes infection when it gets into broken skin or mucus membranes, usually of the genitals. Syphilis is most often transmitted through sexual contact, although it also can be transmitted in other ways.

Syphilis occurs worldwide. Syphilis is more common in urban areas, and the number of cases is rising fastest in men who have sex with men. Young adults ages 15 - 25 are the highest-risk population. People have no natural resistance to syphilis.

Because people may be unaware that they are infected with syphilis, many states require tests for syphilis before marriage. All pregnant women who receive prenatal care should be screened for syphilis to prevent the infection from passing to their newborn (congenital syphilis).

Syphilis has three stages:

• Primary syphilis
• Secondary syphilis
• Tertiary syphilis (the late phase of the illness)

Secondary syphilis, tertiary syphilis, and congenital syphilis are not seen as often in the United States as they were in the past because of the availability of:

• Free, government-sponsored sexually transmitted disease clinics
• Screening tests for syphilis
• Public education about STDs
• Prenatal screening