Evaluation of Syphilis Screening Results in Donors Applying to a Transfusion Center of a Tertiary Hospital

Abstract

Aim: In blood banking, the significance of diagnosing syphilis, a condition caused by Treponema pallidum, cannot be overstated. It necessitates the adoption of the most appropriate algorithm for catching possible cases among donors, thereby minimizing donor loss. The World Health Organization in 2003, and the European Centre for Disease Prevention and Control in 2010, advised starting syphilis screenings with Treponemal tests. This study aimed to investigate the outcomes of confirmatory tests conducted on blood donor candidates with reactive Enzyme-Linked Immunosorbent Assay (ELISA) test results in syphilis screening. Material and Methods: In this retrospective study, 69,127 donors who applied as blood donors to the blood bank of a Training and Research Hospital between 2014 and 2021 were examined. Specimens from donor candidates who tested reactive in the syphilis screening test were dispatched to the Microbiology Reference Laboratory of the Turkey Public Health Institution for verification tests. The Fluorescent Treponemal Antibody Absorption (FTA-ABS) or Treponema Pallidum Hemagglutination Assay (TPHA) tests were utilized as the verification tests. Results: Reactive test results were obtained repeatedly in 128 donors (0.18%). As a confirmatory test, TPHA was administered to 32 donors, resulting in 11 positive outcomes (34.3%) (False positivity ratio = 65.7%). FTA-ABS was performed as a verification test on 96 donors, with 59 (61.4%) testing positive (False positivity ratio = 38.6%). Out of 48 donors with an ELISA signal-to-cutoff ratio above five, the FTA-ABS test was conducted on 42, yielding 41 positive and one negative result. Conclusion: The study suggests that using FTA-ABS as a confirmatory test for ELISA-reactive donors improves syphilis detection accuracy.