Which test remains positive for life after syphilis infection and is used to confirm exposure to Treponema?

• A. RPR.
• B. VDRL.
• C. TP-PA.
• D. CRP.

Answer: (C)

In syphilis testing, antibodies against Treponema pallidum are detected by treponemal tests, which tend to stay positive for life even after treatment. The TP-PA is one of these treponemal assays and is used specifically to confirm exposure because its reactivity usually persists indefinitely.

Non-treponemal tests like RPR and VDRL are useful for screening and monitoring treatment, but their titers can rise and fall with disease activity and often become nonreactive after successful therapy, so they aren’t relied upon to confirm lifelong exposure. CRP is a general inflammatory marker and is not specific to Treponema pallidum, so it isn’t used to confirm syphilis exposure.