[Question #6528] Accuracy of RPR testing on testing for latent (tertiary) syphilis

13 months ago
I have been tested for syphilis twice - both times used the RPR test (both negative) - I am male who only had sex with females, they however were prostitutes in my late twenties - I always used a condom, never had a chancre or any real symptoms of the disease - but I am terrified of stds and thought I had put this behind me years ago, but my anxiety came back today.    My question is this - my risk factors were many years before the test - maybe 10-15 years and I read that sometimes the RPR test is not as accurate (70%) or something in testing for latent syphilis and my fear is that my two tests were actually false negatives because in tertiary syphilis sometimes the RPR test might not be accurate.  My fear is I actually could have tertiary syphilis and not know it.  I have read answers from both Dr. Hook and Dr. Handsfield (who I actually asked this question of once) - but I can't find his answer in your logs and I have terrible anxiety and hypochondria that I can't always control and thus I am asking again.  Are my two negative RPR tests definitive proof that I do not have syphilis even though I was tested 10 years or so after the supposed risk encounters with female prostitutes?  Do I need to have a reverse algorithm test or is my RPR tests conclusive?  I am terrified of starting all this up again and having another test so I am hoping my RPR tests are definitive.  Also are two negative tests proof also that the prozone effect wouldn't be an issue.  I ask now because lately I have been having migraines and visual auras which are terrifying me........it could be because of extreme stress because I just was diagnosed with sarcoidosis and had to wait for the biopsies (fear of cancer) and that is what started the migraines - but they are now still happening.  That is what has started this RPR fear up again.  Are my two negative RPR tests conclusive that I don't have syphilis even though the tests where 10 years after my supposed incidents?
Edward W. Hook M.D.
Edward W. Hook M.D.
13 months ago

Welcome to our Forum and thanks for your question.  I'll do my best to help.  Believe your RPR results.  I'm not sure where you heard that the sensitivity of the RPR for late latent or active tertiary is only 70% but that is inaccurate, particularly if you are testing related to symptoms.  Syphilis is a rare disease, the exposures you describe condom protected vaginal sex), and the absence of a chancre or other sign serve to confirm that syphilis is just not a realistic concern.  I see no need for further syphilis testing related to your sarcoidosis or your migraine headaches. 

The prozone reaction is likewise rare and is described only in persons in the relatively early stages of infection who are symptomatic.  I would not worry and as I've already said, I see no medical need for further testing

I hope that this comment is helpful.  EWH

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13 months ago
thank you so much - so RPR is accurate no matter how far removed from any exposures - whether it was 6 months or 15 years - if the RPR is negative - you are negative for Syphilis - correct?  Thanks again Dr. Hook
Edward W. Hook M.D.
Edward W. Hook M.D.
13 months ago
If you had active syphilis at any stage beyond the very earliest stages, the RPR would be positive.  The old literature from the era before penicillin was even widely available suggested that a small proportion of persons with syphilis actually cure themselves and in those, it is hypothesized that their RPR may go to non-reactive.  You have no reason to worry. EWH
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