[Question #7738] STD Risk

53 months ago

Dear Doctors - I am a 26yo male. I left a monogamous relationship about two years ago. Since then, my sexual encounters have consisted of oral and vaginal intercourse with four women. All four are 20-something, Caucasian, and upper-middle class. I live in the southeastern United States. I have asked every girl before sleeping with them if they had any STDs; all said they did not. I did not follow up on how they knew. Two of girls I dated. In one relationship, we used condoms every time we had sex. In the other, we did not. This was probably foolish, but she assured me she did not have any STDs and she was on birth control, which is why I made the mistake of not using a condom. The remaining two girls I only slept with once. In one case, we had about five minutes of no condom sex before putting one on; in the other, we did not use a condom at all. Again, both girls assured me they were clean. The latter was my most recent encounter and happened two weeks ago. In that encounter, she bled a little. I am going to get a full STD panel soon. My questions follow. First, when should I get this panel? Second, should I be worried? I was hoping you could offer me some fact-based reassurance. Admittedly a conversation with a friend about the prevalence of HIV promoted my concerns; my friend said she knows lots of people with HIV, and that it is pretty common/easy to get. The latter seems objectively untrue, particularly among heterosexual people. Is there a significant chance given these facts that I have HIV? I thought that the odds are less than 1/1000 per sexual act of getting HIV through unprotected sex WITH someone infected; this does not even factor in the likelihood that they are not, which is substantial because most people don't have HIV. Also, I'm aware that my chances of having contracted other STIs like gonorrhea are much higher, and that I could go ahead and test for them. Thank you very much for the service you provide.

H. Hunter Handsfield, MD

53 months ago

Welcome to the forum. Thanks for your confidence in our services.

Congratulations for your high level of sexual safety. Not zero risk, of course -- but pretty darn good, as refected in relatively few partners likely at low STD/HIV risk, discussion of STD risks with them, and your usual use of condoms. That said, I would recommend you resist the temptation to sometimes forego condoms. You don't mention symptoms, but presumably none or you would said so; most males experience symptoms from most recently acquired STDs and their absence is reassuring. Your risk of HIV is especialy low, virtually zero: the chance any particular sexually active young woman has HIV is well under 1 in a thousand, probable even lower for your partners, based on what you say about them. And few people lie about HIV status when asked directly.

When to be tested? Any time now for gonorrhea/chlamydia testing (valid any time more than 4-5 days after the last potential exposure). Blood tests for HIV and syphilis any time 6 or more weeks after the last exposure. I recommend against any other testing. The other tests in many labs' typical "STD panel" are either entirely useless or potentially misleading and usually not worth the effort, cost, and false security they might provide -- which especially is the case for people with the sexual lifestyle and exposures you describe.

Your friend is misinformed about HIV transmission risk. The average transmission risk for unprotected vaginal sex with an infected female partner has been calcuated to be around 1 in 2,500. (The 1 in 1,000 figure is for male to female transmission.)

Finally, by far your main risk for bacterial STD is chlamydia, and it commonly causes asymptomatic infection. That's the single most important test you should have. Gonorrhea is less likely, although still pretty common. However, you describe partners at very low risk for gonorrhea, and >95% of infections cause obvious (often very painful) symptoms in men. The chance you have it is nearly zero. Indeed, low enough that you really don't need testing for it. However, the standard tests for gonorrhea are embedded with chlamydia testing, so a urine test will include both.

For all those reasons, you can expect negative results. I would further add advice that, assuming your sexual lifestyle continues more or less as it is, you have no symptoms, and you are not notified by a partner that she is infected, you plan on regular testing from time to time, like maybe once a year, and not after any particular exposure.

I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD

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53 months ago

Thank you very much for the prompt, detailed reply, Dr. Handsfield!

I'm sorry I forgot to mention - no symptoms; I feel great!

Your response addressed all my questions, but could I clarify a few things?

You said that the infection risk of HIV for a male with an infected female partner during a single incident of unprotected vaginal sex is 1/2500. Am I correct in stating that the risk of getting HIV under the same facts except changing HIV status from infected to unknown is extraordinarily lower, since most women don't have HIV? (using your figures something like 1/2500 * 1/1000). Does menstruating increase chances of transmission of HIV?

I will get the testing as you suggested. If I did have chlamydia, would a treatment protocol of antibiotics knock it out?

Finally, thank you for the suggestions for going forward. I will abide by your recommendations.

H. Hunter Handsfield, MD

53 months ago

Thanks for the thanks.

Your analysis is exactly right. I've often offered exactly that sort of calculation to forum users concerned about HIV. In decimal terms, 0.0004 x 0.001 = 0.0000004 risk of infection from a single episode of unprotected vaginal sex, i.e. odds 4 in 10M, or 1 chance in 2.5 million. If condom efficacy is added to the mix at an estimated 99% effectiveness, it comes to 1 chance in 250 million.

There are somewhat conflicting data on enhanced transmission risk during menstruation, but most analyses indicate little or no effect. Which makes sense, since HIV levels are similar in infected persons genital fluids and blood. But even if this say doubled the risk, the odds calculated above remain extremely low.

Chlamydia is easily and effectively treated with antibiotics, especially doxycycline or azithromycin.

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53 months ago

Thank you so much, Dr. H! You have answered all my questions, alleviated my concerns, and provided great guidance going forward. Please feel free to close the thread.

H. Hunter Handsfield, MD

53 months ago

I'm glad to have helped. Best wishes and stay safe.---