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HIV Window Period & Applicability of P24 Antigen Testing to Early D...
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HIV Window Period & Applicability of P24 Antigen Testing to Early Detection of HIV2

Dear Professor Handsfield

I had potential exposure with a black african CSW in Belfast, Ireland 4.5 wks ago. I am concerned over HIV-2 specifically due to the ethnic origin of the CSW. I received oral sex with a condom, which I know is viewed as negligible risk. However, within 2 days of the encounter I began to experience symptoms of a UTI which didn't respond to standard antibiotics. I then went to a clinic and got meds for chlamydia and gonorrhea and my symptoms resolved in 36hrs. At the time of the encounter, I had concerns about the amount of tampering she did with the condom before the act took place. It is probably paranoia, but I suspect she may have re-used a condom from a previous encounter. I have even thought that it could be a case of deliberate infection.

A statement issued on 15 March 2010 by the British Association of Sexual Health and HIV indicates that for the 'majority' of people the 4th generation HIV1/2 assays will identify infection by 28 days. Am I correct in thinking though that the so called 4th generation DUO tests would not be reliable for HIV-2 infection, since p24 is specifically affiliated with HIV-1 infection? I tested at my local clinic in Manchester UK with a 4th generation DUO test at 26 days post-exposure and the result was negative (but 2 days short of the BASHH 28-day mark!).

I have been experiencing sore throat and 'tender' glands under my arms and jawline from about 15 days post-exposure to present (now Day 31) and they don't seem to be abating. I have also lost about 11lbs over 3 weeks (probably due to worry and not eating). If my symptoms have been attributable to HIV1/2 since day 15 (i.e. associated with a seroconversion illness) is it likely that even the 26-day 4th generation DUO test would have shown 'positive' in terms of the HIV2 antibody component of the HIV1/2 test by then, assuming that p24 antigen only applies to HIV1.

Thanks in advance for any advice you can offer.

J
Tags: p24, HIV2
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239123_tn?1267651214
Welcome to the HIV forum.  The bottom line is that I agree with the BASSH statement, and you can be certain you don't have HIV.

Even if your partner was infected, you were at little or no risk.  It is unlikely she re-used a condom, but even if she did, the basic fact is that your exposure was condom-protected.  And the odds are she didn't have HIV anyway.  And remember that even with entirely unprotected sex, the average transmission risk for vaginal sex (female to male) is around once for every 2,000 exposures -- which is equivalent to having unprotcted sex once daily for 5 years and maybe never being infected.  (This is why most spouses of HIV infected people don't become infected themselves.)

HIV-2 is rare in all African countrires, and entirely absent in most of the continent.  It may be true that the p24 antigen component of the Duo test doesn't cover HIV-2 (I had never heard this before), but the antibody component does.  The large majority of newly infected people have positive antibody tests by 4 weeks, and your negative Duo test result is highly reliable.  As for your symptoms, they are not highly suspicious for HIV, especially in the absence of fever; and antibody tests are pretty much always positive within a week of onset of symptoms, so there's yet another level of reassurance.

All those factors considered, there is no realistic possibility you have HIV.  You probably will want to have another antibody test 6-8 weeks after the exposure as final reassurance; you can expect it to remain negative.  Finally, if the clinic you refer to was a GUM clinic in Ireland or th UK, you were under very expert care.  If any doubts persist, return there for their direct evaluation and advice.

Regards--  HHH, MD
5 Comments
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Avatar_m_tn
Thanks Prof Handsfield.

Your response is very re-assuring, albeit I wonder if you might clarify an element of your reply. In your response you state that "the bottom line is that I agree with the BASSH statement, and you can be certain you don't have HIV".

You will note from my original posting that I tested at the 26-day mark and not the BASHH recommended 28-mark. Is this an oversight on your part, or have you taken this into consideration in your response. In other words, is my anxiety about HIV unwarranted despite testing 2 days before the stated 28-day threshold recommended by BASHH.

Regards and thanks in anticipation.

J
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239123_tn?1267651214
Two days makes no difference.  The data on seroconversion window aren't that precise.  Your anxiety about HIV is definitely unwarranted.
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Avatar_m_tn
Dear Prof Handsfield

Just to let you know I restested at 6 weeks and the DUO result came back negative for Ab/Ag and P24.

My symptoms of enlarged sore lymph nodes and sore throat still persist (duration now 6 weeks, commencing 2 weeks post-exposure to present i.e. 8 weeks) and in the last week or so I have been feeling constantly sick. Another notable feature in the last week or so is the emergence of discrete pain centres around the backs of my arms near the elbows (epitrochlear node area), my goin area, back of neck, around the knees and I have also developed a distinct feeling of what I can only describe as a 'taught' and 'sunburnt' skin sensation around my neck and over my shoulders. I have not had fever or rash since the onset of my other symptoms 6 weeks ago.

In light of my 6-week negative test, I turned to my GP for standard blood tests, the results of which have not shed any light on the cause of my symptoms. The only episode of significance in my life in the last 8 weeks which I can attribute the cause to is my encounter with the west african CSW. In light of my concerns over HIV-2, I have read a few papers which suggest the window period for this strain may be prolonged compared to HIV-2, due to lower viral load relative to HIV-1 in the acute infection stage. I have also pretty much confirmed by research of authoritive literature and consultation with the UK Health Protection Agency that P24 antigen is really only applicable to HIV-1 early detection ahead of antibody production. In fact, the 4th generation assay test kits often specify 'HIV 1/2 and HIV-1 P24' which is a bit of a giveaway.

Could it be possible that I have had the above-mix of HIV-2 related symptoms for 6 weeks now and not produced antibodies to this strain, therefore yielding negative test results. I am 100% sure it is not HIV-1 as I had a viral load test at 22 days at my GUM clinic which came back negative - I don't believe the PCR viral load test would have detected HIV-2 as again I believe it was developed for HIV-1. I'm sure I have read similarly that there is no HIV-2 licensed vrial load test in the U.S. either.

I am off for another DUO test tomorrow (8 weeks post-exposure) to see where it takes me....specifically the HIV-2 antibody component of the test. I'll let you know how I get on.

Regards

J
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239123_tn?1267651214
Assuming no new exposure since the one described above, your test results to date prove your symptoms are not due to HIV -- and they don't sound like HIV anyway.  My understanding, in contrast to what you were told by HPA, is that the tests you had in fact are valid for HIV-2.  Either way, HIV-2 is too rare in most industrialized countries (including UK, I assume) to worry about.

The best expertise on all this in the UK can be found at any of the NHS GUM clinics.  If you continue to be concerned about all this, visit your nearest clinic for their advice.

That will be all for this thread.  I won't have any further replies.
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