[Question #12972] Syphilis, Doxycycline & Infectiousness

3 months ago

Hi Dr,

Currently experiencing some slight anxiety and would like some advice. About a month ago I made a mistake and had unprotected oral and protected sex with 3 different escorts (2x with one of them). 10 days later I got an sti test for Chlam, Gonnorhea, Syphilis and HIV which all came out negative. 2 weeks after exposure I decided to take 100mg doxycycline twice a day, and am now on day 13. I also have zero symptoms so far. My questions are:

1. I read online that for doxycycline you are still contagious 7 days after finishing the course of doxycycline; in my case would it be okay to do it straight after finishing it (tomorrow).

2. I have had zero symptoms and no chancre so far - does that mean I can safely assume that I never had it in the first place? Also does transmission only occur through contact with the chancre?

3. Finally, I read a government report here in Australia that the infection notification rate for syphilis among non indigenous women is only about 10/100000. What does this mean? Does it mean that syphilis among women is so rare that it is unlikely that I had it? How likely do you think it is that I caught it? Thank you.

3 months ago

Clarification for Q1: I meant would it be okay to resume unprotected sex with my wife straight after my last dose of doxycycline end of day 14, despite the recommendation being 7 days after the last dose.

Edward W. Hook M.D.

3 months ago

Welcome to our Forum. Thanks for your questions. I'll be glad to comment. I see you are from Australia. If that's the case and your exposures were in Australian brothels, your risk if very, very low as persons working there are tested regularly and STIs are very rare. Further, your riskiest exposures (vaginal sex) were condom protected making the risk lower still. If the exposures were not in Australia the risk is still low as in most locations commercial sex workers are careful to get tested and take precautions. Further, if any of your partners were infected, most single exposures do not result in transmission of infection. Your 10 day test results confirm this, proving that you were not infected. You have little to worry about. In response to your specific questions:

1. I read online that for doxycycline you are still contagious 7 days after finishing the course of doxycycline; in my case would it be okay to do it straight after finishing it (tomorrow).

This is incorrect. Tests can remain positive after completion of therapy due to the presence of dead organisms but you were certainly not infections after completion of your doxycycline. That you had sex with your wife is not a concern.

2. I have had zero symptoms and no chancre so far - does that mean I can safely assume that I never had it in the first place? Also does transmission only occur through contact with the chancre?

Syphilis transmission occurs only with DIRECT contact to an infectious site. The doxy you took would cure syphilis if present, would prevent syphilis if exposed but the most likely thing is that you were not even exposed. Either way, you have no concerns about syphilis at this time.

I do not know what this figure means. It sounds like a syphilis rate.

I hope that this information is helpful. If anything is unclear please use your up to two follow-ups for clarification. EWH

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3 months ago

Ah I see. So just confirming I’m getting this right, it is not true that somebody with syphilis can remain infectious up to seven days after finishing treatment with doxycycline; which means that it is safe to immediately return to unprotected sex straight after day 14 of treatment? I wonder where this recommendation of not having sex for 7 days after treatment came from then as I see it a lot on government sites on management of syphilis. Also for Q2, when you say infectious site I take it you are referring to a chancre? Finally I always see conflicting information - a lot of online sources say syphilis is on the rise globally including in Australia even among women and heterosexual people, but from browsing the answers on here in getting the impression that it is actually quite rare among those who are not MSM or gay men. Can you help shed some light on this? Thank you.

Edward W. Hook M.D.

3 months ago

The recommendation for avoidance of sex is a conservative recommendation made to allow time for untreated partners to be notified and receive either curative or preventative treatment. The biology is the biology!

Yes, a chancre is an infectious site.

Both are true. Syphilis is relatively rare compared to far more common STIs such as gonorrhea and chlamydia. Nonetheless, rates are rising but are nowhere near the rates of gonorrhea or chlamydia.

You have one follow-up remaining.

EWH

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3 months ago

I see. I’m sorry for being repetitive so there’s no way I’m still infectious immediately after my last dose of doxycycline (you can just answer with a short yes or no). Should I wait at all for the last dose to work (maybe a few hours)? Otherwise I think that settles my inquiries. Thank you so much. And again I’m sorry for the repetitive questions.

Edward W. Hook M.D.

3 months ago

I’m not sure why you think the answer would change with a repetitive question. You would not be able to infect others IF you were infected ( there is no evidence you were) at the time you competed your doxycycline.

This thread is now being closed. There should be no reason to return regarding the encounters you described. EWH

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