Introduction: Worldwide two strategies are followed to diagnose syphilis. One is conventional method of testing the serum by non-specific treponemal test VDRL followed by specific Treponemal Pallidum Hemagglutination Assay (TPHA). The other method is viceversa. We aim to study the percentage of syphilis case detection rate by both the methods.

Material and Methods: A retrospective cross-sectional study was conducted amongst the high risk group patients attending the STD-OP of Institute of Venereology, Chennai for a period of 12 months. The study population was divided into 2 groups. Group A with conventional screening method (i.e. VDRL followed by TPHA) and Group B with TPHA followed by VDRL.

Results: A total of 1527 cases were recruited into the study, 767 in Group A and 760 in Group B. Group A: Out of 767 cases, 90 (11.7%) were reactive by VDRL. 65 (72.2%) were TPHA positive among the 90 VDRL reactive. The case detection rate and correlation between the two tests were 11.7% and 72.2% respectively. Group B: Out of 760 cases, 263 (34.6%) were TPHA positive 166 were VDRL reactive among the TPHA positive. The case detection rate and correlation between the two tests were 34.6% and 63.1% respectively.

Conclusion: The results of comparative data clearly demonstrate that the case detection rate was higher (three times) in reverse screening than that of conventional screening method. In conclusion, consistent with recommendations, laboratories should consider implementing the reverse algorithm for the diagnosis of syphiilis.

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Thilakavathi Natesan

Associate Professor, Department of Serology, Madras Medical College, India