Syphilis in a blood bank in Argentina: Prevalence trends and risk factors

Background: Worldwide, there has been a worrying increase in the prevalence of syphilis. Blood banks have a major role in monitoring the trend of these events, despite the bias due to the altruistic donation strategy. Objectives: To determine the seroprevalence of syphilis and analyse its association with defined risk factors among blood donors at the regional blood center at Hospital Prof. Dr. J. P. Garrahan, period 2016-2022. Materials and Methods: Donor screening was performed with treponemal and non-treponemal tests to determine the prevalence of active and past syphilis. Sociodemographic characteristics of donors were analysed and the association with potential risk factors was assessed. Results: A total of 72 874 donations were processed during the study period. The overall prevalence of specific anti-Treponema pallidum antibodies was 0.69% (95% CI = 0.63-0.75). Active syphilis seroprevalence was 0.30% (95% CI = 0.25-0.33). Not active syphilis seroprevalence was 0.39% (95% CI = 0.35-0.44). Anti-T. pallidum seroprevalence among first-time donations was 1.26% (95% CI = 1.14-1.38) while in repeat donations it was 0.16% (95% CI = 0.12-0.21). In univariate analysis, we found an association between syphilis and having a history of any sexually transmitted infection (OR: 5.09, 95% CI = 2.20-11.70, p < 0.01) and being first-time donors (OR: 3.48, 95% CI = 1.70-7.09, p = 0.0001). Conclusion: Although the overall prevalence of syphilis is 0.69%, among repeat donors prevalence as low as 0.16% was found. This demonstrates the need to maintain and improve screening strategies and promotion of voluntary, altruistic and repeat donation.