After giving treatment for Syphilis, the response to treatment can be best assessed by -: (A) FTA- ABS, (B) VDRL, (C) TPHA, (D) Immobilization test
Answer is B. VDRL can be used for treatment monitoring as specific tests remains positive (reactive) after the treatment. A fourfold decrease in titre following therapy suggests adequate therapy, whereas a fourfold increase in titre of reaginic antibodies following therapy suggests reinfection or relapse. FTA-ABS: Treponema-specific test. First test to be positive: FTA-ABS. TPHA: After successful therapy, the hemagglutinating antibodies continue to persist in the serum for a longer time; hence this test is of no prognostic value. T. pallidum immobilization test: TPI test was the first specific treponemal test, that detects the treponemal antibodies in patient's serum, which immobilize motile virulent T. pallidum.