Comparative study of Treponemal and non-Treponemal test for screening of blood donated at a blood center

Abstract

The non-Treponemal tests such as Rapid Plasma Reagin test (RPR) or the Venereal Disease Reference Laboratory test are the most commonly used test for screening of syphilis in the blood centers in India. Now, with the availability of Enzyme-linked immunosorbent assay (ELISA) and Immunochromatographic assays in the market, we decided to evaluate these assays in comparison with Treponema pallidum Haemagglutination Assay (TPHA) which was considered as a gold standard for this study. A total of 8 685 samples of voluntary blood donors were tested on Trepolisa 3.0 and then the initially reactive samples were retested in duplicate on the same assay as well as on Omega Pathozyme, RPR, RAPHA (Rapid Anti-Treponema pallidum Assay), and TPHA. Of the 158 initially reactive samples, 104 were repeatedly reactive on the same assay, 85 were reactive with RPR, 77 were reactive with RAPHA, 60 were reactive on Omega, and 53 were confirmed reactive on TPHA. 48 (56.4%) of the results on RPR were biological false positive, while 21.9% of results were false negative on RPR. We evaluated that Omega Pathozyme was quite in agreement with TPHA as compared with Trepolisa 3.0, RAPHA, and RPR. We concluded that Omega Pathozyme (ELISA) can be considered as a suitable test for screening of syphilis in a blood center.

Rapid plasma reagin test: High false positivity or important marker of high risk behavior

“…One of the study[ 4 ] from western region of our country showed 56.4% false positivity of RPR in blood donors as compared with 60% in our study further indicating impact of RPR on the discard rate of the blood bank.…”

Screening for lower genital tract infections in women of reproductive age group attending a tertiary care hospital

“…8 The sensitivity of TPHA is 85 to 100% and the specificity is 98 to 100%. 9 In females, the asymptomatic Chlamydial infection, if left untreated leads to Pelvic Inflammatory Disease (PID), infertility and its complications. Henceforth, screening women for Chlamydia trachomatis helps in prevention of PID, ectopic pregnancy and infertility.…”

The evaluation of the reverse algorithm for syphilis screening in blood donors

“…Many comparative studies on this subject have suggested that there are many advantages of using a reverse algorithm, in which the screening starts with a treponemal test (7)(8)(9)(10)(11). The use of treponemal immunoassays for syphilis screening eliminates biologically false positives due to the presence of anticardiolipin antibodies in certain diseases (12)(13)(14). In addition, immunoassays can be automated, their results are objective, and they reduce labor costs and increase laboratory efficiency (3, 7-10).…”