A blood test is used to detect the bacterium that causes syphilis, a sexually transmitted infection. Positive results may result in donor deferral.

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It can also be transmitted from an infected mother to her unborn child during pregnancy or childbirth, which is known as congenital syphilis. Syphilis has several stages, and if left untreated, it can lead to serious health complications.

Screening for syphilis is performed using a qualitative test that detects the presence of antibodies to the spirochete (corkscrew-shaped bacterium), Treponema pallidum, by an automated agglutination assay based on specific pattern recognition. Confirmation is performed using another serologic test for total antibodies, an EIA, as well as a test for reagin (a protein-like substance that is present during acute infection and for several months following resolution of infection).

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