The laboratory diagnosis of syphilis. New concepts.

Although new tests for syphilis, as well as new applications of standard tests, continue to appear, the usefulness of several of these procedures has not been determined. When the Fluorescent Treponemal Antibody-Absorption (FTA-ABS) test is used to screen for syphilis, the proportion of positive results that are true positives decreases. The value of modified FTA tests in the diagnosis of neurosyphilis and congenital syphilis remains unproved. Although not studied as extensively as the standard tests, several newer methods--the direct fluorescent antibody test for Treponema pallidum (DFATP), the Rapid Plasma Reagin (RPR) card test, and the microhemagglutination test for T. pallidum (MHA-TP)--may have certain advantages. To be of optimal diagnostic value, tests for syphilis must be selected according to the clinical situation.