Thanks as always for this service. It is refreshing to have people calm anxieties with data and probabilities than stoke anxieties with overblown risk estimates that some physicians can do.

15 days ago I performed oral sex on a man. He came in my mouth and I swallowed it. I noted after that I had a sore throat from some kind of garden variety bacteria/virus that I picked up the week before on vacation. The sore/“raw” throat is what has me concern about hiv risk. The partner said he is clean, and I have no reason to not believe him even though I don’t really know him.

I know you estimate 1/10,000 risk for performing oral sex, but does that change with a sore or “raw” throat? Should I be overly concerned and do I need testing? Am I ok to have unprotected sex with my wife?

The website stdcheck.com that writes orders for lower cost std testing at labcorp, etc. has listed that the testing window for HIV using the 4th gen antigen/antibody test is that the test can be taken and relied on after 21 days after exposure. Is this true? Can I/should I test at 22 days, or do I need to wait until 6 weeks. I know that sometimes advances in testing do not get updated fda approval, so I’m curious if you were aware of the 4th gen test being reliable at 3 weeks? 

Do I need testing? And when would be the best time to test? 3 weeks, 4 weeks, 6 weeks?!?

Thanks, again!

Your question is a good one.  Acquisition of HIV from performing oral sex on an infected, untreated sex partner is so rare that there are no good studies describing factors which might modify risk so we have to generalize from what we know about HIV acquired through ano-genital or genital-genital exposures.  Available data suggest that the presence of inflammation may facilitate risk for acquisition of infections somewhat so, from a theoretical perspective that you had a sore throat at the time of your exposure 15 days ago might be associated with increased risk.  That said your risk is miniscule.  The net effect of inflammation is modest and the estimate of 1 in 10,000 exposures may well be overly conservative.  Even if your sore throat doubled your risk however, and IF your partner had untreated HIV (unlikely) then your risk might be 1 in 5,000 (in other words, chances are greater that 99.9% you would not be infected if exposed).  I would not be concerned.

Assurances that 4th generation tests provide reliable results at 21 days are optimistic.  AT 4 weeks/28 days more than 99% of persons who have recently acquired HIV will have positive tests and results are totally conclusive at 6 weeks.  FYI, neither of us has ever seen or heard of a person with a negative test at 4 weeks who went on to develop a positive test in the next two weeks.  

I you want to test, I'd do so at 4 weeks. if results are negative at that time, give the low, low risk of the exposure you describe, I would accept that as conclusive and move forward even though the "official" recommendation is to have a final test at 6 weeks or beyond.

I hope this information is helpful.  EWH

1. How conclusive is  RPR at 4 weeks? I’m going for my 4 week testing (for all std’s).  I’ve read that 4 wks, the RPR would pick up 90% of all infections.  Is this enough of a % in my case to not be concerned about syph based on my event? U have said U’ve never seen a neg hiv duo test at 4 wks go pos after. Can a similar thing b said for syph, or is it not really like that? Should i retest after this 4 week test, if yes, would it be for purely peace of mind, or 2 mitigate a material risk that I might have caught it from my exposure.

2 Ive seen that starting treatment b4 a sore appears, such as doxy 100/twice daily/14 days wld prevent an infection from taking hold, and U wld be unable to infect anybody else? R U only contagious if and when a sore appears and not B4 then? Ie if there’s a potential exposure and U start the doxy like 2-3 days after, could U consider yourself 100 safe from having or spreading it? 

3 I admit that my anxiety got the best of my and I started doxy yesterday and take 3 so far.  I know that it is past the before 10 days that infection wld take hold and prob pointless, but it’s been done. Will 3 pills already neg affect my 4 week test, or is it the case that if I had caught it, 28 days without doxy is enough time 2 have the RPR to still be around 90%, or have I royally screwed that up?

 4 if my only exposure was orally, then the only way 2 infect someone else would be via my mouth. In other words, a theoretical infection this early on (<30 days) there wld be no risk of the 2 times we had penis-vag unprotected sex - no oral sex?

1.  Syphilis following performance of oral sex is not common.   Although the textbooks will say that it can take up to three months for a syphilis blood test to become positive, in truth, virtually all are positive be about the 6 week time point.  I think the 90% estimate at 4 weeks is accurate.  If I were you, I would not re-test beyond 4 weeks, particularly if you are taking doxycycline (see below)

2.  Doxycycline 100 mg twice daily for 14 days would certainly prevent syphilis if it was in the incubating stage and cure it if infection had been established.  It is the recommended alternative for syphilis treatment in persons who cannot take penicillin.

3.  See above.  You "screwed up' You almost certainly did not need treatment but now that you have started it, it could alter development of a positive test and delay conclusive results.  AT this point, given your level of anxiety, you might as well complete the treatment 

4.  Correct.  Syphilis is transmitted only through direct contact

EWH