Screening assays to find out late latent syphilis cases – which is the best one?

Abstract

The serological methods for diagnosis of syphilis are classified into non-specific (non-treponemal) such as Rapid Plasma Reagin (RPR), and specific (treponemal) such as Treponema pallidum hemagglutination test (TPHA) and Enzyme-linked immunosorbent assay IgG, IgM (ELISA IgG, IgM) tests. The aim of this retrospective study was to estimate and compare the sensitivity and specificity of RPR, TPHA and Syphilis ELISA IgG, IgM. The study was conducted on 18 799 clinically healthy persons who had visited the Outpatient clinic of Ministry of the Interior Clinical Centre, Latvia during 2 years period from August 2006 to November 2007. Patients were screened to find out possible late latent syphilis cases by using RPR, TPHA and ELISA IgG, IgM assays. The results showed the highest sensitivity indices of ELISA IgG, IgM and TPHA methods, and the lowest for the RPR test. Highest specificity
indices were observed by using ELISA IgG, IgM method followed by
TPHA method with lower values and RPR method showing the lowest
specificity. To conclude, ELISA IgG, IgM and TPHA methods should be
used for screening late latent syphilis cases and ELISA IgG, IgM for
diagnosis confirmation. RPR is not recommended for screening purposes.