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RPR & VDRL Tests

Dear Dr

I have a question about Syphilis testing. I need to undergo a syphilis test and I want to avoid discussing my previous infection. The institution that is requesting the test states: under  positive non-treponemal test, such as a VDRL, must be confirmed with a treponemal-specific test, such as an FTA-ABS.

My understanding is that if they perform the VDRL and its negative they will not test again.

So my question is: If my last RPR was negative will the VDRL be negative? Can you become RPR/VDRL positive again without being exposed to syphilis again (meaning that if something remained on your body)?

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Both the RPR test and the VDRL test use similar components for testing and while they give similar test results, they are not identical.  In general the RPR test tends to be slightly more sensitive than the VDRL so that if your VDRL has become negative following treatment, the RPR may still be positive.  Conversely, if the RPR becomes negative following treatment, the VRL will be as well.

In addition, in successful treated people, either test may be negative following treatment and then at a later date be slightly positive.  Thus, in answer to your question, if your RPR was negative it is likely that your VDRL will be negative as well but it is not a sure thing.  There will be residual antibodies to syphilis that remain in your body which are below the limits of detection by the RPR.

On the other hand, if you are tested with a treponemal test such as the FTA-ABS or the TPPA, these tests will most probably be positive, even if the RPR is negative.  

I hope this all makes sense. The bottom line is that further follow-up RPR or VDRL tests will probably be negative but that is not a guarantee.  EWH
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