[Question #6946] Are my results conclusive?

11 months ago
Hello gentleman,

My potential exposure was a single instance of unprotected vaginal sex (condom broke) about a month and a half ago with a girl around my age, mid 20's. I took an HIV RNA test at 2wks following the exposure, as well as both 4th generation AgAb tests and Syphilis RPR's  at 4wks and 41 days, all negative. Do my results conclusively rule out Syphilis and HIV 1&2?

Thank you for your time and for this invaluable service you provide.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
11 months ago
Welcome to the forum. Thanks for your confidence in our services and your kind words about the forum.

All these lab results are 100% conclusive. For HIV, it's the combination of results that's important:  the AgAb tests become 100% conclusive at 6 weeks, so your 41 day result was a day early. However, the 4 week and 41 day results plus negative RNA testing at 2 weeks together are conclusive. Indeed you probably were over tested. If you're in the US, the frequency of both HIV and syphilis is so low in most mid-twenties women is near zero -- although there are exceptions, depending on geography, social background, race/ethnicity and so on. I hope you also were tested for gonorrhea and chlamydia, which are far more common than either HIV or syphilis. If not, I would recommend urine testing for both.

I hope these comments are helpful. If you'd like to provide more information about where you are and the nature of your relationship with the partner you are concerned about, I might be able to say more about risk levels and so on. In the meantime, I hope these comments are helpful.

HHH, MD
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11 months ago
Thank you sir, great to hear. I'm in the southeastern US although she was from NYC, and we're both white. I was concerned about HIV2 only because I know the very few cases in this country seem to center around NY. 
Also, I double-checked and my last 4th gen test was in fact on day 42, not 41. Not that that makes much statistical difference I suppose.
In regards to chlamydia and gonorrhea, I haven't been tested but I was put on a short course of doxycycline as a preventative measure following a tick bite-would this have cleared any infection by either of those?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
11 months ago
Assuming your partner doesn't use drugs by injection and not likely to have had sex with bisexual men, the chance she has HIV (either type) probably is no higher than 1 in a thousand. And the average risk of transmission, female to male, for a single episode of unprotected vaginal sex is around 1 in 2,500. So even before testing, your risk can be cacluated as being in the ballpark of 1 chance in 2.5 million. Your risk may have been even lower, depending on time from recognizing the condom failure and withdrawal.

But in any case, your results are conclusive; and the AgAb test by itself is considered conclusive at 42 days. But you're right this doesn't make any statistical difference.

Assuming you took doxycycline at least a week, it definitely would cure incipient chlamydia. Probably gonorrhea as well, but 20-30% of gonorrhea is resistant to doxy. On the other hand, absence of symptoms (urethral discharge, painful urination) is strong reassurance against gonorrhea. So I agree that at this point, testing is optional. The chance you have aysmptomatic gonorrhea is probably on the order as the odds you have HIV, i.e. zero for practical purposes.
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11 months ago
Thank you Dr, I actually just got back from the lab, figured I'd get tested anyway. And that's also correct, I've exhibited no symptoms for any of the above mentioned. Thanks for helping to alleviate my fears.
11 months ago
I do have just one final question-I know it isn't exactly realistic to worry about here in the US, but are my 4th Gen results at 6wks conclusive for HIV2? I only ask because the test only detects antibodies for HIV2, and the 3rd gen antibody only tests aren't conclusive until later (8wks?).
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
11 months ago
For practical puroses, the AgAb tests are considered conclusive for HIV2 at 6 weeks. The current antibody tests (of the sort used in the combo tests) detect antibody far sooner than older tests. The third generation tests (antibody only) are officially conclusive by ~8 weeks, but almost no persons take more than 6 weeks to develop detectable antibody. Putting it in similar mathematical terms as before, if 1% of HIV in the New York area is HIV2, then my risk calculations above become 100-fold even less risky. If we assume the antibody component of your test detects "only" 99% of infections at 6 weeks, you're still looking at one chance in billions that you have HIV2. In other words, zero for all practical purposes.

For people at the low risk end of the exposure spectrum, like you, I like pointing out that the National Safety Council says the average American has 1 chace in 1,756 of dying accidently in the next 12 months (auto accidents, drownings, falls, house fires, etc, etc). That means your risk of accidental death in the coming year is thousands of times higher (maybe millions?) than the chance you have HIV.  Don't forget your seatbelt, and check those smoke alarm batteries!

That completes the two follow-up exchanges included with each question and so ends this discussion. I'm glad to hear it has been useful -- that's why we're here.
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