A Comparative study of Various Testing Methodologies for the Screening of Syphilis in High Risk and Low Risk Group

INTRODUCTION: Syphilis is a chronic infectious disease caused by Treponema pallidum. It is one of the commonest STI which commonly causes adverse events during pregnancy. Since Treponema pallidum is a non cultivable bacteria, serology plays a vital role in the diagnosis. As it increases the transmission of other STI, screening of syphilis in high risk population is very important. AIMS &OBJECTIVES: 1. To evaluate the validation (sensitivity and specificity) of rapid tests for syphilis. 2. To screen the patients for syphilis with these various testing methods. MATERIALS AND METHODS: 400 cases of adults (both males and females) of high risk group and 400 cases of adults (both males and females) of low risk group attending the STI Out Patient Department, Institute of Venereology, Madras Medical College/RGGGH, Chennai – 600003 were included in the study. Detailed history including last sexual contact, extra marital contact and high risk behaviors shall be documented along with clinical examination. After adequate counselling, the blood samples are collected and tested for the presence of antibody to treponema pallidum by VDRL test, TPHA,RPR and rapid card test. RESULTS: Syphilis was most commonly seen in second and third decades of age. Males (41%) were predominantly affected than females (24%). Prevalence of syphilis was equally distributed among educated and uneducated. Most of the patients in high risk group were homosexuals. practicing both ano-receptive and insertive intercourse. Fourteen percent of the patients in high risk group were associated with other sexually transmitted infections. 2.4% of the syphilitic patients were co infected with HIV. Among the three tests done, VDRL (98.1%) was found to have a slightly higher sensitivity than RPR (93.8%) and Rapid card test (96.29%). The specificities of VDRL, RPR and Rapid card test were 97.8%, 97.5% and 97.8% respectively, which was almost equivalent. Among syphilitic patients 2.25% had primary syphilis, 4.5% had secondary syphilis and 92% had latent syphilis. CONCLUSION: The validity parameters of VDRL test, RPR test and Rapid card tests were almost similar. The choice of the screening can be made based on the available infrastructure. VDRL can be used as a screening test in tertiary centres where the adequate laboratory set up is available. There is no single best test to arrive at the diagnosis of syphilis. RPR test and Rapid card test can be considered in resource poor settings like primary and secondary health sectors in the screening of antenatal cases, mass screening, research purposes and in places where the follow up is questionable. It is mandatory to confirm the screening test results with confirmatory tests to decide about the disease activity, staging of disease and also to decide the appropriate management