Syphilis is a multisystem infectious disease caused by the corkscrew-shaped bacterium (spirochete), Treponema pallidum. This organism causes infection when it penetrates broken or abraded skin or mucous membranes, usually of the genitals. Transmission occurs most frequently through sexual contact, although other means of transmission are possible.
Syphilis occurs worldwide. In the United States, about 10,000 cases occur annually. The rate of syphilis is higher in urban areas (as compared to rural) and the incidence is highest in the southern states. Young adults, ages 15 to 25, are the highest risk population. There is no natural resistance to syphilis.
Because people may be unaware that they are infected with syphilis, many states require tests for syphilis prior to marriage. All pregnant women who receive prenatal care are screened for syphilis to prevent congenital syphilis, which can appear in the newborn infant of infected mothers.
Syphilis has three commonly recognized stages: primary syphilis, secondary syphilis, and tertiary syphilis. From a medical standpoint, the actual stages are primary, secondary, latent (hidden), benign late, and tertiary. Syphilis can also affect the unborn child of an infected mother (congenital syphilis).
Primary syphilis first shows as a small, painless open sore or ulcer (chancre). This ulcer typically appears 3 to 6 weeks after exposure. The often solitary ulcer that appears on the penis is easily visible. However, ulcers that occur on the labia, cervix, anal area, or in the mouth may go unnoticed because they are painless and not easily visible.
The classic-appearing ulcer or chancre is shallow with sharply defined borders and slightly raised edges. The base of the ulcer is clean and free of debris. It is typically painless and is firm to the touch (indurated). However, many syphilitic ulcers are not "classic" or typical-appearing, and any ulcer appearing on the genitalia should be suspect.
If left untreated, the chancre typically heals spontaneously within 6 to 8 weeks. It may leave behind a thin, slightly depressed (atrophic) scar. This is the end of the primary stage. The organism continues to multiply in the body, but there is little outward evidence of disease until the appearance of the second stage.
Secondary syphilis, tertiary syphilis, and congenital syphilis are not seen as frequently in the United States as they were 20 or 30 years ago because of the availability of free, government-run sexually transmitted disease clinics, screening tests for syphilis, public education concerning STDs, and prenatal screening.
