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 bacteria causes infection when it gets into broken skin or mucus membranes, usually of the genitals. It 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, rather than rural, areas, and the number of cases is rising most rapidly 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 are screened for syphilis to prevent the syphilis infection from passing from the mother to the newborn (congenital syphilis).

Syphilis has three stages:

• Primary syphilis
• Secondary syphilis
• Tertiary syphilis

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-run sexually transmitted disease clinics, screening tests for syphilis, public education about STDs, and prenatal screening.