Evaluation of the seroprevalence of syphilis infection among voluntary blood donors from northern Greece. Retrospective study from 2015 to 2020

Blood donation is an important procedure that saves millions of lives. However, unsafe transfusion practices carry the risk of transfusion-transmissible infections (TTIs). Screening for syphilis is mandatory for routine blood transfusions. The purpose of our study was to investigate syphilis seroprevalence in voluntary blood donors from Northern Greece. Data from blood donors were analyzed, including first-time and repeat donors, all apparently healthy, who gave blood the last six years (2015-2020). Routine blood donation data and demographics were extracted. Also the variation of the annual syphilis seroprevalence was evaluated. Serological testing was performed using the reverse algorithm, which initiates the screening with a highly sensitive treponemal test. A total of 127.413 donations were tested. Among screen positive test results, 87 (0,07%) tested positive by at least one confirmatory test. Confirmed positivity was positively associated with men of middle age (31-50 years) and blood donations from sporadic blood donors. Seroprevalence of syphilis infection did not change significantly per year. Syphilis is a disease with a low prevalence in the blood donation population of Northern Greece. Blood Centers should implement new methods and updated algorithms for detecting infections. Through syphilis screening control, they offer transfusion safety, significant benefit for public health and ongoing infectious disease surveillance.