[Question #8350] HIV test

45 months ago

Dear Doctors，

Thanks for your service on this website!

I amd a male live in the UK(Scotland). I have unprotected(stupid , I know) sex with a couple of female CSWs about three months ago in London. Most of them are asian but one of them is from Africa. Then somewhat I searched on the internet and started to feel anxious and decided to test for HIV.

At 59 and 101 days after the last exposure, I went to the scotland NHS sexual clinic in Glasgow and tested for HIV, syphilis, gonorrhoea and chlamydia and everything is negative. I checked these results via an automatic phone line which only says everything is “negative “.

They call the HIV test just a “blood test” and says it’s accurate after 45 days. They draw blood from my arm and sent it to a lab. I don’t know what kind test they use. On their website they state that they use a “fourth generation test”.

As one of the CSWs is from Africa, I am concerned about HIV-2. My questions are as follows:

What is (by definition)a fourth generation test? Does it test for HIV-2? On the NHS website they just say “HIV” and my test results say nothing about HIV1 or HIV2, just says “your hiv blood test is negative”. I fear that the test just “ignore” HIV-2 because it is too rare.
Is my day 101 test conclusive for both HIV-1 and HIV-2?

Thanks for your help!

H. Hunter Handsfield, MD

45 months ago

Welcome. Thanks for your confidence in our services.

Among our most consistent advice -- which you can find on innumerable threads -- is that the current HIV blood tests are among the most accurate diagnostic tests ever developed, for any medical condition. The definition of a 4th generation test is that it detects both HIV antigen (i.e. traces of the virus itself) and antibody to HIV, instead of antibody alone. Therefore, the proper terminology currently is just antigen-antibody (AgAb) test, which is the same as 4th generation. My understandings is that these tests are the ones done routinely at the UK NHS sexual health clinics, and the clinic's comment about 45 days being conclusive is the standard window period for the AgAb tests. (I assume the same standards apply at the Scotland clinics, as in England -- with which I am more familiar.)

Therefore, your negative HIV test results are conclusive; indeed, the second test at 3+ months wasn't necessary. The negative results are valid for both HIV1 and HIV2. (And by the way, just being from Africa doesn't necessarily raise the possibility of HIV2, which is primarily localized only to relatively limited areas of Africa -- tropical East Africa, e.g. Cameroon). Your negative results mean you can entirely ignore the level of risk at the time of exposure. It probably was low, since heterosexual transmission of HIV is so inefficient. I'm also glad to hear of your negative syphilis, chlamydia and gonorrhea results: you were at much greater risk for those STIs than for HIV.

I hope these comments are reassuring. Let me know if anything isn't clear.

HHH, MD

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45 months ago

Thanks very much for your reply!

So you mean that a standard 4th generation test indeed do detect HIV-2? This might not be a meaningful question but: are there exist 4th generation tests which only test for HIV-1 but not HIV-2? Or just any antibody-antigen tests are valid for both? I fear that somewhat they use a test specifically for HIV-1 but still call it 4th generation.

At this point, because of covid the clinic is still not operating normally. And there are only limited number staffs doing “no talk” tests. So it’s not easy to find a reliable doctor to consult. I truly appreciate your help!

H. Hunter Handsfield, MD

45 months ago

For all AgAb tests, the antibody portion of the test detects HIV2. Some experts recommend somewhat later testing if HIV2 is a concern -- but even there, you're covered by your negative 3 month result.

As for specialists to consult, genitourinary medicine (GUM) is a standard specialty in UK (unlike the US, for example). If you look up GUM specialists, I'm sure you can find someone highly expert in HIV and STDs, if you would like in person care and the NHC GUM clinic remains closed for in-person consultation (especially if you're in a good sized metropolitan area).

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45 months ago

Thanks very much for your help. That’s really helpful!

This’ll I wanted to ask. Have a nice day!

H. Hunter Handsfield, MD

45 months ago

Thanks for the thanks -- I'm glad to have helped. That's why we're here.---