[Question #420] advice needed - 6 week negative HIV test done in Australia

92 months ago
Hello to all the experts,

Firstly I would like to thank you for bearing with all of us through our most worrisome times. I am sure it gets somewhat tiring reiterating the same information over and over. Your time spent is truly appreciated and there is no such service available in my home country of Australia.

I had a possible high risk exposure on November 10, 2015. The male I slept with removed the condom without my knowledge during penetrative sex and subsequently came inside me. He also made me bleed (so I imagine his semen had direct route into my bloodstream). I state that it is high risk as he travels for work all over the world (not just developed countries) and clearly has no issues with having unprotected sex as he removed the condom.

I tested negative at both 4 weeks and 6 weeks post exposure. I did a lab test where they drew blood. I am not sure what generation the test is as it only states 'HIV 1/2 Antigen and Antibody'. I am deeply concerned the test will turn positive when I test at 12 weeks post exposure. I never experienced many ARS symptoms, so I am worried I am a delayed seroconverter (hence likelihood of turning positive close to 12 weeks?).  As I am in Australia could this mean the tests they used are of lesser quality than the tests you are experienced with? 

Every authority here has told me nothing is conclusive until 3 months post exposure. It will be 9 weeks this Tuesday and I wish to test again, then at 12 weeks post exposure. 

Thank you for your time. 

H. Hunter Handsfield, MD
92 months ago
Welcome to Ask the Expert. Thank you for your kind opening words.

At this point, you really need not be worried at all about HIV. First, heterosexually transmitted HIV is rare in Australia; when it happens, it is highly restricted in particular social and ethnic groups. The overall epidemiology of HIV is very similar to the US in this regard -- I don't know the details about Australia, but I'm sure you could confirm this with a little online searching of public health website(s) -- or your nearest sexual health centre (more about which below).

Second, even with bleeding (e.g. during menstruation), the average risk of HIV transmission by unprotected vaginal sex is around once for ever 1,000 exposures -- so even if your partner had HIV, the odds are very heavily in your favor.

Most important, you had a 4th generation test (antigen-antibody combination), which is conclusive any time 4 weeks or more after the last possible exposure. Some experts and public health agencies in Australia and elsewhere may still advise later testing, but that's from a very conservative perspective. The concept of "delayed seroconversion" does not apply to the 4th generation tests:  "seroconversion" refers to development of measurable antibody; if somehow that doesn't happen on schedule, the antigen component of the test picks it up. That's why the 4th gen/duo tests are a major advance over previous tests; they eliminate any concern about delayed seroconverion. In the several years since they became available, I hhave never heard even a rumor of someone whose positive test was delayed beyond 4 weeks.

For that reason, I'm quite confident that even if you speak with "every authority" and ask specifically if they have ever seen someone become positive on a 4th gen test after being negative at 4 weeks, the answer will be no.

To put this in personal terms, if I were somehow in your shoes -- or if I were counseling someone close to me (I can imagine my daughter in a situation like this a few years ago) -- I would not have any further testing at all, once a 4th gen test was negative at 4+ weeks.

Finally, as implied above, in my opinion Australia's network of federally funded sexual health centres is the world's very best network of STD/HIV prevention clinics. You will be guaranteed expert (and reassuring) advice at any SHC. (If you happen to be in or near Sydney or Melbourne, the SHCs there are the best of the best.) I'm confident they would confirm most if not all my perspectives above.

So you can relax and enjoy the new year. If you go ahead with still more HIV testing, you can rest assured the result will remain negative.

I hope this has been helpful, but let me know if anything isn't clear. Best wishes and happy new year--

92 months ago
Dear Dr Handsfield,

Your prompt response has been deeply, deeply appreciated by myself who has been in near constant panic for the last few weeks. I would go as far as to say that the time you doctors spend answering our questions is a lifeline, and in our most desperate hours of net trawling and restless nights, reputable voices such as your own are beyond appreciated.

My next line of questioning would be that I'm aware the medical statistics for the antigen/antibody test I took at 6 weeks are about 99% accurate. How can my test indeed be conclusive if there is a 1% chance of it changing? Are you saying not to test again based off perceived risk? He very may well have had unprotected sex with women from high prevalence countries. 

I have spoken with both the Melbourne and Sydney Sexual Health Centers, who have advised me that although a negative at 6 weeks is promising, it is not conclusive until 3 months. The slip from the pathologist company (Douglass Hanley Moir) even advises to test at 3 months too. Is there any possibility this test is not as sensitive as other antigen/antibody tests?

Do I need to be concerned that a co-infection with hepatitis a, b or c has delayed the window period of my HIV test?

I sincerely hope you don't take offence to my obsessive questioning undermining your experience and authority, but the anxious mind is so very consuming.

Thank you again 

H. Hunter Handsfield, MD
92 months ago
No offense at all -- we never take offense at reasonable questions. Don't confuse signs of exasperation at repetative or nonsensical questions (not yours!) with offense.

There is obviously some disagreement between my views and the conservative stances taken by the SHCs and the lab person you spoke with. I consider the duo test conclusive at 4 weeks and beyond, and this is what the scientific data supports. The 99% figure of test performance is an estimate, not based on firm scientific fact. I repeat that I am unaware of any HIV/AIDS physician who has ever seen a patient with negative duo at 4+ weeks who later turned out to be infected. (There may be rare exceptions in people who took post-exposure prophylactic drugs that didn't work, but I'm not even sure about this.)

But let's assume the real test performance is "only" 99%. That doesn't mean that there is a 1% chance you have HIV. Even before you were tested, I would put your risk of having been infected at something like 1 in a million. (That comes from 1 chance in 1000 your parther had HIV, and 1 in 1000 you caught it if he did:  0.001 x 0.001 = 0.000001, one in a million). A test that detects 99% of infections misses 1 in 100. Thus, the actual chance you have HIV and that a later test will become positive is not 1%, but 1 in 100 million. That's zero for any practical purposes.

As for viral hepatitis, hepatitis A and C are zero risk. Contrary to popular opinion, they are rarely sexually transmitted -- once in a while in gay men, virtually never in hetersosexuals -- and hep B also is very unlikely. I would have recommended against testing for any of them. But the negative results are valid at 6 weeks.

Do whatever you feel you need to do in terms of additional HIV testing. If you do it, you can be sure the result will be negative. In the meantime, I would advise you to stay off the internet and otherwise stop asking for more opinions. Like many anxious persons, it seems you are being attracted to information that inflames your fears and having trouble understanding or absorbing the reassuring bits. It isn't worth it. I also suggest you go to a mirror, look yourself in the eye, repeat "You do not have HIV" 10 times, then kick back and treat yourself to a nice dinner with a bottle of fine wine. (Something from the Barossa or McLaren Vale might be suitable....)

H. Hunter Handsfield, MD
92 months ago
I mistakenly deleted your last follow-up comment -- typed a reply then by error clicked on the wrong button. My apologies!

As I recall, you asked whether yoru hepatitis testing was too early -- maybe tested at 4 weeks? Since there was essentially no risk for viral hepatitis, it really doesn't matter. But if you really feel you need a definitive test result, 6 weeks is conclusive.

You also asked aboutthe risk from some of the details of your exposure: 1) Receiving cunnilingus: probably zero risk for HIV; no cases have ever been reported. 2) Brief fellatio on your partner, without ejactulation: probably zero risk; even with more prolonged exposure, the average transmission risk penis to mouth has been estimated at 1 chance in 10,000, which is equivalent to giving BJs to infected men once daily for 27 years before transmisison might be considered likely. 3) Vaginal fingering: no risk; no known transmissions ever reported. And remember I also guesstimating the chance your partner had HIV as 1 in a thousand. So you can discount whatever risk there was from these events by that figure.

My apolgy again for mistakingly deleting the question, but I'm pretty sure that covers it. However, I'll leave the thread open a bit longer in case I missed something.

92 months ago
Hi Dr Hansfield,

My only concern with the hepatitis was that if you were somehow infected with hepatitis A, B or C and HIV during the same exposure...this could mean that my test results for HIV were not accurate? (Because I have read if you are infected with both at the same time, it can delay the bodies response to producing HIV antigens/antibodies).

The only other concern from my deleted response you didn't address was my fear that some of his precum may have come into contact with shaving cuts on my vagina. Irrational to get tested after this secondary encounter? (Given I tested negative at 4 and 6 weeks after the unprotected penetrative sex encounter).

Thanks again 
H. Hunter Handsfield, MD
92 months ago
There are no medical conditions that interfere with HIV testing, especially with the duo/4th generation tests. (If anything delays antibody production, it INCREASES the positivity of the antigen part of the test.)

Sorry I missed the last bit. There has never been a known HIV transmission through contact of sexual secretions with skin, even with shaving nicks. No worries and you don't need any further testing.

That winds up this thread. Do your best to relax about all this. In nearly 12 years of doing this forum and my previous one at MedHelp, with thousands of question, nobody ever turned out to have caught HIV from an exposure they were worried about. You won't be the first. If and when that happens, I expect it to be from a true high risk exposure, which you definitely did not have.

Best wishes and stay safe.