Treponema Pallidum

[klondike378]

In September 2012 I had a Syphilis test.  My RPR was 1:8, but I tested equivocal for Treponema Pallidum Antibodies.  After talking with a doctor I was treated with two injections of penicillin.  In late December 2012 I was retested my RPR is 1:2 but now I tested positive for Treponema Pallidum antibodies.

My question is, do I still have active Syphilis post treatment or is it normal to still test positive for Treponema Pallidum antibodies and not have an active infection?

Thank you.

[Edward W Hook, MD]

Welcome to the Forum.  Interpretation of syphilis blood tests is among the more difficult things that doctors encounter.  The blood tests for syphilis are used for both the purposes of diagnosis and for following response to therapy.


As far as your tests are concerned,  I'm a bit surprised that your initial treponemal antibody tests were equivocal, given your RPR results but it is clear when your follow-up results are also considered that you had syphilis and it sounds as though you had the recommended therapy.  The change in your RPR result from 1:8 to 1:2 indicates that you have had a good response to your therapy and your infection has been cured.  

Antibody tests, particularly the treponemal tests, can remain positive for long periods of time- sometimes a lifetime.  Please do not be concerned if your treponemal test remains positive.  At this time, if your RPR does not go up to 1:8 or more in the future you should consider yourself cured.

I hope this helps.  

[Edward W Hook, MD]

Obviously, there is no way to be sure.  Certainly antibody production does continue and accumulates over time.  EWH

[klondike378]

I wonder if the equivocal result could have been because the test was preformed not very long after my exposure to syphilis?  The person I contracted it from contacted me soon after my exposure to warn me of their positive syphilis test results.

Thank you for your assistance.