Follow-up of Military Blood Donors Who Test Positive for Syphilis

Abstract

Background Several large studies have demonstrated that syphilis carries a risk of future sexually transmitted infections (STI), such as human immunodeficiency virus. There are limited data on outcomes of syphilis infections that occur in populations that undergo universal syphilis screening, such as blood donors. Military trainees who donate blood can be followed through their military career to determine the future risk of STIs. Methods Blood donor data were gathered from the Armed Services Blood Bank Center–San Antonio for those with positive Treponema pallidum antibodies between 2014 and 2021. The medical chart of each case was compared with 6 sex- and military accession date–matched controls with negative T. pallidum antibodies to determine the risk of STI in the 3 years after donation. Results A total of 63,375 individuals donated blood during the study period. A total of 23 military trainees (0.36 per 1000 donors) had positive T. pallidum antibodies. A minority (n = 7; 30%) of cases were treated for early syphilis. Only 6 cases (26%) received a follow-up nontreponemal test within 1 year. Donors who tested positive had a significantly higher risk of developing an STI within 3 years after blood donation compared with blood donors who tested negative (relative risk, 3.8; 95% confidence interval, 1.3–10.5; P = 0.01) including gonorrhea (9% vs. 0%, P = 0.02) and syphilis (9% vs. 0%, P = 0.02). Conclusions This study shows the presence of T. pallidum antibodies in blood donors was associated with an increased risk of future STIs. These cases support the need for close follow-up and broad STI testing in blood donors with positive T. pallidum antibodies.