Syphilis is a sexually transmitted disease (STD) caused by the bacteria Treponema pallidum. A syphilis infection is spread through contact with a syphilic sore, also called a chancre, usually during vaginal, anal, or oral sex. Syphilis can also be spread from a parent to a fetus in pregnancy or to an infant during childbirth. If not treated appropriately, syphilis may cause severe damage to internal organs.
Testing for syphilis is used in patients who have symptoms suggestive of this infection. Syphilis testing is also recommended to screen for syphilis in certain groups of people at an increased risk of infection or of transmitting the infection to others. Syphilis testing can be conducted using a sample of blood, a swab of fluid taken from a sore, or a sample of spinal fluid.