[Question #11269] Syphilis

15 months ago

[Question from a friend who does not have access to a credit card.]

Male received oral for 2 - 3 seconds from female SW.

21 days since exposure, no symptoms.

Doxy-Pep (200mg) taken at 60 hours post exposure.

1. How effective was the Doxy-Pep for preventing syphilis at 60 hours instead of within the recommended 24 hours?

2. What is the percentage chance syphilis was contracted from such a brief encounter combined with using Doxy-Pep at 60 hours and lack of symptoms at 21 days?

3. Should testing be done at 6 weeks?

4. Should abstinence be practiced until a test rules out syphilis?

5a. To ease anxiety, could 200mg Doxy / day be started now? If so, how long until non-contagious?

H. Hunter Handsfield, MD

15 months ago

Welcome and thanks (to your friend asking the question) for your confidence in our services. To that person:

This was a zero risk exposure for syphilis or very close to it, I would not have advised doxy-PEP in this situation. Doxy-PEP is recommended only for men who have high risk (anal) sex with other men at high risk for STI. To your specific questions:

1. Sixty hours is fine. The research on Doxy-PEP showed it to be effective against syphilis if taken within 72 hours.

2. This was zero risk for syphilis.

3,4. I see no need for testing for syphilis or for sexual abstinence.

5. No more doxycycline is necessary and I do not advise it.

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

HHH, MD

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15 months ago

Great. One more follow up.

He took a Gonorrhea and Chlamydia test 8 days post exposure and 16 days post exposure. All tests negative both times.

1. Would those tests be considered 100% conclusive?

2. Would you consider him to be 100% STI free given the circumstances and test results?

3. Is there any other STI to be concerned about?

H. Hunter Handsfield, MD

15 months ago

1. Yes, those results are conclusive.

2. Yes, definitely.

3. None.

All OK?

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15 months ago

Here is his last question as it's understood this is the 3rd and final correspondence.

Doctor, thank you for the reassurance. May you please go into a bit more detail why the risk for syphilis is zero? I am asking this to calm my anxiety. Is it because the exposure was so short? The transmission rate from oral so small? The Doxy? I believe it is a combination of many things but if you could briefly detail them that would surely help me finally move forward now.

Thank you for the help and offering this service. Take care.

15 months ago

(For the aforementioned Gonorrhea and Chlamydia tests, a real time PCR test was used with a urine collection. How accurate are RT PCR urine based tests?)

H. Hunter Handsfield, MD

15 months ago

Syphilis is rare in females in most geographic areas; although oral lesions sometimes can transmit syphilis, it's uncommon (most cases by vaginal or anal sex); and the exposure was very brief. Doxycycline is highly active against syphilis and research shows doxy-PEP to be nearly 100% effective in preventing it. All these add up to zero risk for syphilis from his exposure. He didn't even need testing for it.

The "real time" designation is marketing hype. All urine nucleic acid amplification tests (NAAT) are highly accurate. (PCR is a type of NAAT.) And these risks also were near zero from such a brief exposure. Your friend overreacted to a near zero risk situation.

As you anticipated, that concludes this thread. Best wishes.

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