You needn't worry at all about having syphilis, for several reasons. First, the rarity of heterosexual syphilis in the UK:  although total rates are rising and perhaps have had some media attention, still there were only ~8,700 cases in 2022 (the most recent year of publicized data) of which ~80% were in men who have sex with men, leaving only ~2,000 cases in the entire country among women and straight men. Statistically, therefore, it is extremely unlikely your sex working partner has syphilis. Second, with extremely rare exceptions, syphilis requires penile penetration to be transmitted; it is rarely if ever transmitted by hand-genital contact, so the exposure itself was risk free. (And certainly syphilis bacteria cannot survive on the hands for more than a few minutes, and is never transmitted through food, etc.) Third, your symptoms don't fit:  3 weeks is longer than usual for onset of the chancre (syphilitic ulcer) and chancres almost always are painless. Finally, your negative blood test at 5 weeks is nearly 100% conclusive.

If you remain concerned, you could consider another blood test. The standard tests are conclusive at 6 weeks, so you could be retested now if you wish. If somehow I were in your situation, I would not do it -- there's simply no need. But if you do so, you definitely can expect another negative result.

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

HHH, MD

You are way over-reading the information you found, probably online. The description of syphilis transmission skin-to-skin only distinguishes sexual skin-to-skin contact (like HPV and herpes, in addition to syphilis) from transmission by genital fluids (e.g. gonorrhea, chlamydia, and HIV). It does not mean that any and all skin contact is high risk for syphilis transmission. Only skin-to-skin sex meaning genital-genital, genital anal, or less often genital-oral exposure. Also, I would strongly advise you to be selective in your online searching. Stick with professionally run or at least professionally moderated websites and you won't be so easily misled. Especially avoid sites by and for infected persons or those at risk, like Reddit for example. Anybody can write anything they want and giant amounts of information on such sites is just plain wrong. Just like you need your day to day news from sources like BBC, CNN, The Times, The Guardian, etc and not Facebook, TikTok or other social media sites. (A word to the wise!)

Do your best to accept, understand and believe the reasoned, science-based information I have provided.

I suggest you go back and carefully re-read my replies above -- concentrate on every word! Then do your best to understand, accept and believe the reasoned, science-based advice they contain. 

That completes the two follow-up exchanges included with each question and so ends this thread. Please do not be tempted to return with more questions about these issues. There is no information you will think of that has any possibility of changing our evaluation and advice. Best wishes and stay safe.