Antibody tests (serology)Ñthese tests detect antibodies in the blood and sometimes in the cerebrospinal fluid (CSF). Two general types are available for syphilis testing, nontreponemal and treponemal (derived from the name of the bacterium). Either type may be used for syphilis screening but must be followed by a second test that uses a different method to confirm a positive result and to diagnose active syphilis:
- Immunofluorescent Assay (IFA)
- The FTA-ABS is a specific treponemal assay to detect antibody to t. Pallidum. The FTA-ABS becomes reactive 4-6 weeks after infection. Unlike the nontreponemal tests, once the FTA-ABS test becomes reactive, it will remain reactive for many years. Since the reactivity found with the FTA-ABS does not indicate response to therapy, it is not suitable for monitoring treatment. The FTA-ABS test does not distinguish between syphillis and other treponematoses such as yaws, pinta and bejil.
- Treponemal pallidum, Fluorescent Treponemal Antigen, Syphilis