[Question #5184] One night stand

24 months ago
Hi there,

Unfortunately under the influence of alcohol, I had a one night stand that was unprotected (I’m a male).  The girl said she had been tested within the last two weeks and was negative and that she had no other sex partners for about a year.  Of course being paranoid, I am not sure whether or not to believe her.  That being said it was a one time exposure and it was just quick vaginal sex with nothing else.  What is my risk of exposure?  Should I get tested before being in contact with my regular sex partner?  If not how quickly can I get tested before resuming unprotected sex?  I know I screwed up and it’s not something I want to do in the future.  It all sucks, but really gives me direction as far as lifestyle choices.  Thanks for your expertise.
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
Welcome to our Forum,  I'll do my best to help.  The facts are that most people tell the truth when asked and your partner's history is relatively detailed making it somewhat more likely that she was truthful.  It is not clear to me whether she (and you) were talking only about HIV or all STIs including HIV so I'll answer as though you were asking about all STIs including HIV:
1.  Most people do not have STIs, including HIV.  If they have been tested regularly, it is still more likely that they are not infected.
2.  Even when partners have STIs and/or HIV, most exposures to infected partners do not lead to infection.  For bacterial STIs such as chlamydia or gonorrhea, your risk from a single episode of vaginal sex is about 20% per sex act (i.e. there is an 80% chance you would not be infected if she was).  for HIV the risk is even lower- the risk of infection from a single episode of vaginal sex with an infected partner is estimated to be about 1 infection per 1200 sex acts.  
3.  Thus, your risk for any STI, including HIV from the encounter you describe is low.  Testing is a personal decision. The risk form the encounter you describe is higher for bacterial STIs than for HIV.  You are far more likely to have been exposure to a bacterial STI than to HIV.  If you want to be tested for bacterial STIs such as gonorrhea and chlamydia, tests will be accurate three to 5 days following exposure.  For HIV current testing with 4th generation, combination HIV antigen/antibody tests is 99% conclusive at 4 weeks and entirely conclusive at 6 weeks.  

I hope this information is helpful.  EWH
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24 months ago
Thanks for the advice!  A few quick follow up questions.

Would it be safe to wait 1-2 weeks and if no symptoms appear, resume unprotected sex with my normal partner?

Is testing recommended without symptoms in this case for both bacterial STI’s and HIV?  

Finally, what are your thoughts on the early (9-11 days after) HIV test and how long would I wait for those to be conclusive?
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
1.  Some of the STIs I mentioned, chlamydia in particular is often asymptomatic.  Any STI can be asymptomatic.  Your risk is highest for these infections and confidential, relatively inexpensive testing is widely available from many public health clinics.
2.  See above- it is the safest course of action.  In general, the risk is low but often the consequences in terms of relationships as well as health can be serious.  Testing is always the best course of action.  
3.   The 9-11 day, HIV RNA test is good but not perfect.  A negative test at 11 days is very strong but not 100% conclusive evidence that HIV was ot acquired and should be confirmed with a combination HIV antigen/antibody test at 6 weeks. OTOH, in a relatively low risk situation such as the one you describe, for all practical purposes the 11 day test would be conclusive. 

Hope this helps.  EWH
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24 months ago
Great.  Finally what tests specifically should I get to make sure I haven’t gotten anything bacterial?  Thanks.
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
The most important tests for common STIs are for chlamydia and gonorrhea.  They can be done as a urine test or with a swab from the penis.  In some clinics, tests for trichomonas can be done on the same urine or swab specimen as tests for gonorrhea and chlamydia.  Other tests routinely offered are blood tests for syphilis which is very rare and for HIV which, as mentioned above, is not conclusive until 6 weeks after an exposure.  Your risk for gonorrhea and chlamydia is many times higher than your risk for syphilis or HIV.

Hope this information is helpful.  As I trust you know, we provide up to 3 responses for each question.  This is my 3rd response.  Thus this thread will be closed later today without further responses.  Take care.  EWH
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24 months ago
Since this hasn’t been closed yet, I was hoping to ask just one more reply.

I will get tested for ghonorea, chlamyida, and HIV using the RNA test at 11 days.  In your opinion, should I also get a syhpilis test done?  Is there an early test available that doesn’t require 3 weeks before testing?  Finally, if the three (or 4) tests result in negative, would I be safe to resume unprotected sex again.  Thank you.
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
Final answers.  Your gonorrhea and chlamydia tests are conclusive.  Most experts still suggest a follow-up six week HIV test as I suggested above but an 11 day RNA PCR test is very strong evidence that you were not infected.  There are no early syphilis tests and your risk for syphilis is very, very low.  Based on the test results you mention, I would not worry about being infected and would be comfortable resuming unprotected sex with a regular partner.

End of thread.  EWH
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