Investigation of choice for detection of syphillis in a patient after 2 course of complete therapy

Ans. is `b' i.e., VDRL To monitor the response to therapy non treponemal serological tests (RPR or VDRL) are used. Features of serological tests . Most senstive serological test in primary syphilis . First test to become positive . The test of choice for rapid serological diagnosis in a clinic or office setting . Tests for monitoring the responce of therapy . Testing of large number of sera for screening or diagnostic purpose . Tests for confirmation of the diagnosis . Measurment of Ig M in a neonate for congenital syphilis . The diagnostic test . Reagin antibodies tests (RPR and VDRL) becomes positive after 3-5 weeks of Infection (7-10 days after the appearance of primary chancre). In Lyme disease VDRL test is negative, but FTA-ABS may be positive. All serological tests may be positive (false positive) in non veneral treponematoses. eg in yaws, Pinta and endemic syphilis. . Presence of Ig M in a neonate confirms syphilis, as IgM can not cross placenta. But Ig G can be passively transfered from the infected mother to newborn. . Reagin antibody in syphilis is Ig G while reagin antibody in atopy (hypersensitivity reaction) is Ig E.