Health Questions and Answers

Question: What causes syphilis? How is it treated?


Syphilis is caused by exposure to Treponema pallidum. The disease progresses through well-described stages. There is an initial ulcer at the point of infection, usually visible on the vulva. In contrast with genital herpes, the ulcer is painless. Systemic symptoms can appear within a year, with a characteristic rash on the palms and soles of the feet. Finally, there is late syphilis, in which systemic effects involve multiple systems including the heart and the central nervous system.

The diagnosis can be made by observing the organism microscopically using dark-field microscopy. However, the diagnosis is usually made by serologic testing for antibodies. Initial screening is performed using either the rapid plasma reagin (RPR) or the Venereal Disease Research Laboratories (VDRL) test. Either of these tests, if positive, should be confirmed with a more specific test for the organism, either the fluorescent-labeled Treponema antibody test (FTA) or the microhemagglutination assay of antibodies to T. pallidum (MHA-TP). Treatment is with penicillin. The exact regimen depends on the stage of the disease.


  1. Baldwin HE. STD update: Screening and therapeutic options Inter J Fertil Womens Med 46:79-88, 2001.
  2. Centers for Disease Control and Prevention. 1998 guidelines for treatment of sexually transmitted diseases. MMWR 47:1-111, 1998.

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