Syphilis remains frequent worldwide and, whether misdiagnosed and mistreated, it could cause irreversible sequels. On this way, it is necessary to know what tests are more appropriated for each infection stage and to evaluate their results, as well. Nowadays, disease research is done with specific and non-specific serologic tests and most doctors usually indicated VDRL or RPR and FTA-ABD or ELISA. Most research laboratories are testing with VDRL and ELISA, because they are easier to perform than the others. These serologic tests become positive at the second week after anogenital ulcer appearance. VDRL is considered positive when titles are 1/16 or superior. Smaller titles are considered as false-positives whenever treponemal tests are negatives. However, some diseases are associated to a positive VDRL, while ELISA is negative, without a previous report of syphilis. VDRL is essential to syphilis post-treatment follow-up. This test must be done every six months, until the end of the second year. However, it can remain positive in 6.6% of patients with a primary infection, and in 8.39% of those with secondary forms, until the 30th month after the treatment. In these cases, it is necessary to exclude a re-infection by T. pallidum. In HIV-positive patients follow-up, serologic tests must be performed each three months. VDRL behavior is the same in HIV-negative or positive patients, and T CD4 lymphocytes counts have no influence. A false-positive result is 10 times more frequent in HIV-positive population, becoming negative after the 10th week, in most patients.
Syphilis; Diagnostic; Serologic tests