Diagnosis of syphilis

The demonstration of Treponema pallidum in early specimens is still the most important procedure for definite diagnosis of the disease. Nonspecific lipoidal antigen tests, as well as assays using T. pallidum antigen, are used for the detection of antibodies in sera. The techniques, the interpretation of the results, the onset and limits of reactivity, as well as the sources of error of the VDRL (RPR), FTA-ABS, TPHA (MHA-TP, AMHA-TP), IgM FTA-ABS, I9S IgM-FTA-ABS, and IgM-SPHA tests are described. The presence of 19S IgM antibodies against T. pallidum indicates activity of the disease and their disappearance is evidence of cure. Positive results in the VDRL test are also strongly suggestive of active disease but are less precise. A TPHA index for CSF of more than 100 and a positive result in the IgM-SPHA test on CSF are indicative for neurosyphilis.A haemagglutination assay is suggested for screening, if possible combined with the VDRL test. The FTA-ABS test is recommended for confirmation of the diagnosis and the response to treatment can be assessed by the IgM-SPHA test or by changes in the VDRL titre.