[Question #2540] Syphillis

95 months ago

I am a male who received unprot oral from another male on Nov 12. Dec 3, a bump appeared on my penis. I went to an Urgent Care on Dec 10, and the practitioner said it could be syphilis. They ordered an RPR but it worried me so much I asked them to treat me presumptively and they gave me a penicillin shot (unsure if the correct type). I did the RPR on 11 Dec (4 weeks) and it came back non-reactive. I went to my doctor at 9 weeks post exp and asked him to do a treponemal test. Not sure which test it was but the result said treponema non-reactive. Tested again 11 weeks post exp for HIV, HSV, and another RPR. All negative or nonreactive. Put the incident behind me and moved on. Early in May I had very small lesion appear on my penis shaft and it was uncomfortable when it rubbed against clothes. I went to my Dermatologist and he was unsure what it was but he ordered an RPR. It was non-reactive. He did take a sample of the spot, sent to a lab and they called it an irritated verucca. In early June I had a rash on my chest and back (mostly gone after 5 weeks) which my Dr. attributed to a new medication I was taking. I also started having a burning sensation on the soles of my feet and hands with excess sweating but no rash. The Nov 12 encounter was my last sex encounter. Questions: Any chance the prozone effect is skewing my results? How common is the prozone effect? Do I need anymore syph testing? Should I ask my Dr. to treat me for syph despite the results?

H. Hunter Handsfield, MD

95 months ago

Welcome to the forum. Thanks for your question.

The bottom line is that you for sure do not have syphilis and almost certainly never did; and you have been rather seriously over tested. My reasoning: Although syphilis can be transmitted by oral sex, it's not very common. Although syphilitic chancre starts as a bump that soon ulcerates, it is probably unlikely that that was the cause of the penile bump. Accordingly, syphilis was unlikely but not impossible. But once you were treated, with a negative RPR before treatment, there was no chance your RPR would ever become positive, even if you had acquired syphilis -- so there was no point in any further RPR testing. (Once in a while, penicillin fails to cure established syhphilis. But there are no known cases in which it failed to abort the infection if given early, i.e. when blood tests were still negative.) And your later negative treponemal test -- no matter what type it was -- further confirms you do not have syphilis. There is a slim possibility you were infected and it was aborted by the penicillin treatment, but unlikely; almost certainly you were never infected. But if you were, it is gone now and you'll never have a positive blood test, it will not reactivate, and you can definitely move on with no further worry about it.

Prozone is rare; and further, most labs routinely take steps to avoid it by testing both the original and diluted blood specimen. Second, prozone only applies to RPR; there is no prozone phenomenon with treponemal tests.

So whatever the cause of your more recent symptoms, including the skin rash, it isn't syphilis. If the symptoms continue, keep working with your doctors on alternative explanation. For sure you should not have any more syphilis testing or treatment.

I hope this information has been helpful. Let me know if anything isn't clear.

Best wishes and stay safe-- HHH, MD

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95 months ago

Dr. Handsfield,

Thank you for your reply. I felt fairly confident as well but the additional symptoms planted that little seed of doubt and then I read something about prozone and decided to check in with you all here. Glad I did and I will certainly move on. This really is a valuable and important service you all offer. Thank you again.

95 months ago

Dr. Handsfield,

I do have a couple of quick follow-up's.

I had specifically asked my Dr. for a treponemal test and will ask him to clarify exactly which test it was but does the lab result of "treponema non-reactive" indicate to you that it was in fact a treponemal test?

Also, you said

"there was no chance your RPR would ever become positive, even if you had acquired syphilis -- so there was no point in any further RPR testing. (Once in a while, penicillin fails to cure established syhphilis."

I am assuming that if the treatment I received had failed further RPR testing could actually become positive. Am I correct ?

Again, thank you for your response and for the service you all provide.

H. Hunter Handsfield, MD

95 months ago

As I said above, penicillin never fails in this circumstance, so your last question is irrelevant. If through some magical process this treatment had failed, then yes, RPR eventually would turn positive. But this is not going to happen and I suggest you drop this line of reasoning and not have any further tests.

From the test wording, I would assume your last test indeed was a treponemal test of some sort.

You clearly have been alarmed by the original doctor's mention of syphilis, and perhaps by anxieties over a sexual decision you may regret. But science prevails, and the scientific facts are on your side. Don't confuse those emotions with actual risk; they aren't the same. Reread all my comments above, then do your best to suck it up and move on. OK?

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