Syphilis serology in blood donors: a possible surrogate marker for human immunodeficiency virus risk

We report a preliminary study on whether syphilis serology might be reactive in some blood donors at risk for human immunodeficiency virus (HIV) infection. We retrospectively analyzed voluntary blood donations with reactive Treponema pallidum antibody (TPA) tests according to the type of donation, the presence of other safety markers, confidential unit exclusion, syphilis diagnosis, and HIV risk factors. Over 2 years (1987-1988), 1 in 8,900 regular homologous donations (n = 258,610) was TPA positive as compared with 1 in 2,200 directed donations (n = 6,685) and 1 in 300 autologous donations (n = 8,870; p less than 0.05 for both). The rate in directed donations was not significantly higher than in first-time regular donors (1 in 4,800; n = 57,000). TPA-positive donations had higher rates of antibody to hepatitis B core antigen and confidential unit exclusion than TPA-negative donations. Ten TPA-positive homologous or directed donors had latent or previously treated syphilis (1 in 26,500 such donations), and 2 of these had HIV risk factors. None of the autologous donors were determined to have active syphilis. Syphilis serology in blood donors bears further scrutiny as a possible surrogate marker for HIV risk.