First, prozone is rare and always was. Second, it is rarely an issue anymore. Initial syphilis screening now is often done by EIA, for which prozone doesn't occur. And most labs that still do the older tests like VDRL or RPR routinely prevent it by testing the specimen in ways that prevent prozone.
Therefore, your negative test result is definitive. If your rash is continuing, you should see a doctor or clinic. But for neither syphilis nor HIV is the cause. In the meantime, if you have a regular sex partner you can continue or resume normal sexual relations without risk.
Thank you for your response. My HIV and syphilis test came back negative. I am happy with this news but had 1 more question. I read a little but about the prozone phenomenon and just wanted to know how common it was and if I should be worried that I had a false negative 7 week after exposure? Thank you for your help.
Welcome to the forum. Thanks for your question.
Syphilis is quite rare in the US and most industrialized countries, except in selected population groups. Gay men account for two thirds of all cases, and most of the rest are minorities in a few cities and geographic areas. (Syphilis is entirely absent in something like 90% of all counties in the US.)
Can you tell me more about the nature of the exposure you are concerned about and when it occurred? Statistically, it is unlikely your rash is due to secondary syphilis. If you have been at risk sexually (e.g., multiple partners, non-monogamous, or especially if your are man who has had sex with other men), that would raise the odds.
Given the infrequency of syphilis, it seems pointless to speculate before you even know you have it. If your blood test is positive, there will be plenty of time to judge when and how you were infected, and whether your past sex partners need to be contacted. I'll just say that nonsexual transmission (shaking hands, non-French kissing, etc) never transmit syphilis.
So my suggestion is that you fill in some of the gaps about your risks, and that we also wait for the blood test result -- and then take it from there.
Best wishes-- HHH, MD