VDRL test is used for -

Ans. is 'd' i.e., Syphilis Laboratory diagnosis of syphiliso Lab. diagnosis of syphilis consists of: -A) Demonstration of spirochetes under microscopy# Microscopy is applicable only in primary & secondary stage as spirochetes are abundant during primary, and secondary stage (maximum number of spirochetes and infectivity). Microscopy used are Dark field microscopy, and immunofluorescence microscopy (Direct fluerecent antibody test - DFA-TP).B) Serological tests# These tests form the mainstay of laboratory diagnosis. Serological tests are: -1) Non-specific tests (reagin antibody or standard tests):- Kahn test, VDRL, Rapid plasma reagin (RPR), automated VDRL-ELISA, Washermann test. These test measure IgG & IgM against cardiolipin.2) Group specific test: - CFT3) Species specific tests: - Treponema pallidum particle agglutination (TPPA) test, Treponema pallidum immobilization (TP1), Triponema pallidum hemagglutination assay (TPHA), ELISA.o Specific treponemal tests (FTA-ABS, TPHA, TPI) are of little value as indicators of clinical cure, as they tend to remain positive inspite of Treatment. Non treponemal tests (eg VDRL) will become nonreactive or will be reactive at lower titers after therapy, so can be used for monitoring patient's response to treatment These tests usually become negative 6-18 months after effective treatment of syphiliso A four fold or greater decrease in antibody titre indicates response to therapy