[Question #2994] STD/HIV Risk Assessment

39 months ago
Doctor Handsfield and/or Hook,

   First thank you for everything you do!  Here is my situation and follow-up questions.

    I am a 39 year old heterosexual, circumcised male in the United States.  About 36 days ago, I met up with an old girlfriend (37 year old from California) and during a drunken night, engaged in unprotected vaginal and oral sex (giving and receiving).  She told me she was STD free before we engaged in sexual activity, so I proceeded without a condom.  I never do that (alcohol got the better of me), so over the next couple days, I began to worry about STDs.  She has a pretty adventurous sexual history, so being a child of the 80s, the mantra of sleeping with every person your partner slept with went through my mind.

   At 21 days post exposure, I tested negative for chlamydia/gonorreha via a urine test.

   At 30 days post exposure, I tested negative for HIV on a 4th generation blood test taken via vein.  Additionally, I tested negative for trichomoniasis via a urine test.

   I went through a similar situation three years ago, but I see guidance has changed, and now 6 weeks is conclusive for an HIV test, as opposed to the previous 4 week guidance. So needless to say, I started worrying again.  So here are my questions.

    1.  I am a numbers guy, I realize that you can’t say I’m conclusively free of HIV, but what is my remaining risk?  Of note, I’ve taken my temperature everyday since exposure and never had a fever, nor any other ARS symptoms.

    2.   What other further testing should I undertake?  I have had no ulcers, lesions or sores on my penis.  Additionally, I’ve been previously vaccinated for Hepatitis A and B.

    Thanks for your time and putting things into context for me!
Edward W. Hook M.D.
Edward W. Hook M.D.
39 months ago
Welcome to the Forum and than you for your confidence in our services.  I'll be glad to comment.  As you poiint out, your tests for  gonorrhea and chlamydia prove that you did not acquire these more common STIs.  As far as HIV, your risk is very close to zero as well.  You are correct that the CDC has recently changed its guidance on HIV tests and now suggests that six weeks should pass before on can be entirely confident that they were not infected.  Earier today Dr. Handsfield provided additional information and two references addressing this issue in his response to question 2993, you might take a look.  To make a long story short however, the reason for the chance in guidance is related to the fact that a very small number of cases (less than 1% of those found to be infected in several reports) combination HIV antigen/antibody tests took a week or two longer than 28 days to become possible.  Thus, to be absolutely sure one was not infected, testing should be done after 6 weeks (42 days) have passed however for all practical purposes, after 4 weeks (28 days) over 99% of the small proportion of exposed persons who actually acquire infection have positive tests.  Neither of us on this Forum have ever had a patient who did not have a positive combination test before 4 weeks had passed. 

Further, remember the context of your exposure:
1.  Irrespective of her adventurous past, only a fraction of 1% of American women have HIV. Many of those who do have used IV drugs.
2.  the risk of infection from vaginal sex is 1 infection for every 1000-2000 encounters.
3   She told you she did not have STIs. Why would she not tell you if this was the case?

Thus, in answer to your specific questions:
    1.  I am a numbers guy, I realize that you can’t say I’m conclusively free of HIV, but what is my remaining risk?  Of note, I’ve taken my temperature everyday since exposure and never had a fever, nor any other ARS symptoms.
See above, considering her probability of infection, the probability of infection from vaginal sex (no known risk from giving or receiving oral sex form a woman), and your negative tests so far, I would estimate your risk for infection as being less than 1 in 10 million. 

    2.   What other further testing should I undertake?  I have had no ulcers, lesions or sores on my penis.  Additionally, I’ve been previously vaccinated for Hepatitis A and B.
If I were you, I would not feel the need for further testing. If you want to be absolutely sure you did not acquire HIV rather than 99.999%, you could have another combination HIV test at some time beyond 6 weeks after your exposure.

I hope that these comments are helpful.  Take care.  EWH
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39 months ago
Dr Hook,

    Thank you for the prompt, concise and informative reply, I really appreciate it.  Your response really helped me put things in perspective.

     Again,  thanks for all the great work you and the other doctors put in at this forum.  Your knowledge and counsel are of great value to all of this coming to the forum that are going through difficult situations.
Edward W. Hook M.D.
Edward W. Hook M.D.
39 months ago
I'm pleased my response was helpful.  EWH---