[Question #11499] RPR testing window and longevity

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14 months ago
I am a 39-year-old bisexual male who had a sexual encounter with a man in August 2020. I'm concerned about syphilis. I was tested with RPR at 26 days, 39 days, 46 days and 97 days(I'm double checking on this  last one). The clinic I went to normally tests for HIV and syphilis at the same time but I was obsessed with HIV and maybe told them to skip syphilis.

A week or so after this testing I took two weeks of doxycycline. Now, nearly four years later, I have been having all sorts of nerve pain, stiff neck, muscle twitching and a rash in various parts of my body that look like tinea versicolor (I've seen this listed as a symptom). 

So a month ago, I took another RPR test and it came back nonreactive. Would a RPR test still be good after nearly four years?

Now I'm learning that apparently there was another TPPA test I was supposed to be ordering and nobody told me! I'm trying to find it on Quest Diagnostics' website, and this is their syphilis testing guidelines:

"A presumptive diagnosis of syphilis requires use of 2 laboratory serologic tests: a nontreponemal test (ie, Venereal Disease Research Laboratory [VDRL] or rapid plasma reagin [RPR] test) and a treponemal test (ie, the T pallidum passive particle agglutination [TP-PA] assay, various EIAs, chemiluminescence immunoassays [CIAs] and immunoblots, or rapid treponemal assays).1-3 Use of only one type of serologic test (nontreponemal or treponemal) is insufficient for diagnosis and can result in false negative results among persons tested during primary syphilis"

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H. Hunter Handsfield, MD
14 months ago
Welcome back. Thank you for your continued confidence in our services.

First, your negative RPR results at those intervals conclusively showed you did not acquire syphilis. Second, doxycycline for two weeks is 100% curative of syphilis; if somehow you were infected despite the negative RPR, it was cured. Finally, the symptoms you describe do not suggest syphilis. In medicine, for 150 years syphilis has been called "the great imitator", because its symptoms and clinical findings overlap a giant number of medical conditions. For that reason, it is never useful to look at lists of symptoms, see some that correspond to syphilis, and then conclude you might have it. Your test results and the doxycycline overrule your symptoms and all other considerations.

And you also are mistaken about TPPA or other confirmatory tests and the need for two tests. With rare exceptions, a second test is not necessary or recommended if RPR is negative. The two test requirement only applies if the first test is positive, which requires confirmation with a second test. Two tests are not needed if the first is negative; you misunderstand the Quest lab statement.

So no worries at all. You definitely do not have syphilis now and never did.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD
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13 months ago
How long does the RPR show positive during a syphilis infection? At what point in the infection would it turn negative?
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H. Hunter Handsfield, MD
13 months ago
Never. Without treatment, it would be positive for life.---