Biological false reactive VDRL tests: when to re-test?

ABSTRACT

Syphilis serology is a basic screening test for the workers who want to go abroad. Many countries reject migrant workers who have reactive syphilis serology. Biological false reactives warrant repeated syphilis serology. We prospectively studied 30 patients (25 males and 5 females) who had biological false reactive VDRL tests (VDRL reactive, confirmatory TPHA negative). Affirmative tests for syphilis serology for all cases were performed every two weeks. On follow-up, the expected range (95% CI) for seroconversion was between 9.25 and 10.49 weeks. Most cases (25 cases) completely returned to the VDRL non-reactive stage within 10 weeks; three cases completely returned within 6 weeks; 2 cases completely returned within 14 weeks. It is recommended that repeat syphilis serology be conducted 10 weeks after an initial biological false reactive VDRL test.