Many people say it takes 6 to 8 weeks before an individual has a diagnostic level of antibodies for a reliable serological testing for T; Pallidium antibodies (in this case a test called: "Syphilis Screen/Reflex to Rpr"). But 6 to 8 weeks from when? From: (i) exposure; (ii) initial chancre appears; (iii) initial chancre heals; (iv) something else? [Even doctor did not know.]

Welcome. Thank you for your question.---
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Doctor, thank you for the prompt + professional response, as always. I'm fine with your answer. There is a lot of overly-zealous information out there, including the idea that the test may run negative for 2-4 weeks after Chancre, which just strains credulity. See https://www.bmj.com/content/365/bmj.l4159 "The RPR test may remain non-reactive for up to four weeks after the chancre, so it is often negative in primary syphilis, but it is 98-100% sensitive in secondary syphilis.15" citing: Janier M, Hegyi V, Dupin N, et al. 2014 European guideline on the management of syphilis. https://www.iusti.org/regions/europe/pdf/2014/2014SyphilisguidelineEuropean.pdf. (The latter link is broken, but 2020 version can be found at https://onlinelibrary.wiley.com/doi/full/10.1111/jdv.12734 ) Maybe that is true for the RPR test, but the latter link does not say when an RPR turns positive at all, and says NTT STS generally positive 10-15 days after appearance of chancre, which is at least somewhat consistent with your answer, I think. Anyway, there is lack of clarity. These journal articles need better editors... How much do they pay for that?

Thanks. I'll just say that there has never been conclusive research about these issues, hence there is room for professional disagreement among experts on the time requirements. So it isn't terribly surprising that the European guideline might have a conservative perspective, based on incomplete science plus the personal expertise and opinions of those who forged the guideline. Certainly Prof. Janier, the lead author, is very highly respected internationally. And individual case reports, almost by definition, reflect atypical situations. Who knows what unknown factors might be involved in any one case (e.g. a patient to doesn't remember or admit to surreptitious antibiotic treatment prior to testing)? Of course any professional enterprise, including medical journal editorship, is imperfect. But I would not attribute any of these uncertainties to the quality of editorship at the journals or agencies that publish such guidelines or case reports.---
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