Syphilis is an easily spread infection caused by the bacteria Treponema pallidum.

Syphilis is an infectious disease. The bacteria that causes it spreads through broken skin or mucous membranes. It is most often spread by sexual contact.

Pregnant mothers infected with the disease can pass it to the baby developing in their womb. This is called congenital syphilis.

Syphilis is widespread in the United States. It mainly involves sexually active adults between ages 20 to 29.

Syphilis has several stages.

Primary syphilis is the first stage. Painless sores ( chancres ) form about 2-3 weeks after you are first infected. You may not notice the sores or any symptoms, particularly if the sores are inside the rectum or cervix. The sores disappear in about 4-6 weeks. For more specific information about this type of syphilis, see primary syphilis.

Secondary syphilis occurs about 2-8 weeks after the first sores form. About 33% of those who do not have primary syphilis treated will develop this second stage. For more specific information about this type of syphilis, see secondary syphilis.

Tertiary syphilis is the final stage of syphilis. The infection spreads to the brain, nervous system, heart, skin, and bones. For more specific information about this type of syphilis, see tertiary syphilis.

The symptoms of syphilis depend on the stage of the disease. Many people do not have symptoms.

In general, painless sores and swollen lymph nodes are symptoms of primary syphilis. Those with secondary syphilis may also have fever, fatigue, aches and pains, and loss of appetite, among other symptoms. Tertiary syphilis causes heart, brain, and nervous system problems.

For more information, see the article on the specific stage of syphilis.

Blood tests can be done to detect substances produced by the bacteria that causes syphilis. The older test is the VDRL test. Other blood tests may include RPR and FTA-ABS.