[Question #4006] What conditions make a 12 week test non conclusive ?

31 months ago
Dear Doctor 

I had an exposure to HIV 12 weeks ago with a CSW. By reading your posts and posts on CDC, WHO, AIDSVANCOUVER, MEDHELP and BHIVA, i was able to keep myself educated and got the following tests 

Week 6 - 4th generation test ( i dont know which method ) 
Day 83 - Elisa 4th generation test 
Day 84 - CMIA 4th generation test  

I got two tests done so that it reduces my chance of a false negative. However today i understand by reading on AIDSVANCOUVER and CDC that there are conditions/diseases like immunodeficiency diseases that can delay antibody production. My questions are 

1. Under which conditions can my tests be NON-CONCLUSIVE ? 
2. How will i know if i have immunodeficiency disorders ? 
3. i catch colds and flus about 3-4 times a year and it always results in wheezing. It gets okay in about a week of time . Is that a sign of immunodefciency disorders ?
4. Do you think i need to test again ? when should i test again ?
5. My wife has forgiven me as i told her the truth. Can i resume unprotected sex with her ? My greatest fear is that i will infect her 

H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
31 months ago
Welcome to the forum. Thanks for your question.

First, the notion that immunodeficiency can make HIV testing unreliable is highly questionable with the curren ttests, including the ones you had. The warnings about it are almost enitirely theoretical, with few or no cases in which it was documented to actually happen. It may have been a real problem (rarely) with the earliest HIV antibody tests in use from the mid 1980s until around 2000. Since then, not an issue. And it's definitely not an issue with the antigen-antibody (AgAb, duo, "4th generation") tests. In the event that immune deficiency impaired development of antibody, that would actually INCREASE the amount of antigen in the blood, so that part of the test would be more likely to be positive, not less. To my knowledge, there are no proved cases of falsely negative results with the AgAb tests because of immunodeficiency of any kind -- even if reputable sources like CDC and the Vancouver area public health agencies haven't updated their advice (or might be influenced in part by excess medicolegal caution).

Second, to the extent this could be an issue with the antibody-only (3rd generation) tests, it would have to be profoundly severe immunodeficiency. In any and all such conditions, the affected individuals are chronically and usually deathly ill. These are problems that go along with several congenital immune system problems that become apparent in early childhood (and often prove fatal before adulthood); cancer chemotherapy; and high dose immunsuppressive drugs used for various conditions like autoimmune diseases.

If you are outwardly healthy, there is no chance you have any sort of immunodeficiency. The test results you report are conclusive:  you didn't catch HIV during the exposure you are concerned about. As for the exposure itself, the wording of your question implies you know for sure your partner has HIV. Is that the case? Or are you assuming it because your partner is a sex worker? Among female sex workers in western Canada, probably under 1 in a thousand have HIV, certainly under 1 in a hundred (1%). And when a woman has HIV, the average transmission risk for a single episode of unprotected vaginal sex is around 1 in 2500. If you used a condom, the chance is a hundred fold lower than that.

Those comments pretty well address all your questions, but to be explicit:

1,2) See above.

3) These events imply a strong (even somewhat overactive) immune system, not a weak one.

4) Your first test result was conclusive; the other two were superfluous. The results of all three are conclusive.

5) You could and should have resumed your normal sexual relations with your wife after your first negative test. You certainly should do so now.

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

31 months ago
Dear Doctor Hunter 

Thank you for taking out the time to give such a detailed answer. I highly appreciate it. I have a few queries but allow me to answer a few questions you asked. While i live in canada, my exposure happened on a business trip to India with a CSW. It was a hand job and a protected blowjob but i saw blood on my penis seconds after it stopped. I understand blood on mucous memberne poses a significant risk . In India, percentage of sex workers with HIV 1 AND 2 is much higher than 1 percent and which is what leads to my worries. 

The local doctor in India at MAX hospital in new Delhi mentioned i should get tested at week 6 with 4 th generation test and again at week 12 to rule out strain of hiv which do not have any antigen like HIV 2. He did not start me on PEP. I wish he had started me on PEP . i regret not insisting on this. However i cannot change the past.

Please allow me a few follow up queries.

 1. Is it true that HIV 2 and certain strains of hiv do not have antigen ? I understand that HIV 1 would be detected by my tests because of antigen incase of immunodeficiency or medicines but that wouldn't catch HIV 2. Would my week 12 tests catch the HIV 2  antibody in the extreme conditions (Chemotherapy etc )  mentioned by you ?
2. If the normal body produces antibodies by maximum week 8 as mentioned by you in previous posts , wouldn't a person in extreme conditions produce antibodies to hiv 2 by 12 weeks ? That would mean I'm safe if the body produces antibodies by week 12 no matter what.

2. Hopefully I'm not immune defficient but you mentioned certain medication might interfere with antibody tests and thus miss out hiv 2 . As mentioned to you i have a history of allergies and wheezing . Iv been taking antihistamines and benadryl every day and a steroid inhaler twice a week for the last 5 years including the last 12 weeks. Does this change my test result ?
Iv been taking antihistamines every day as I'm allergic to yeast, rice and dust. 

3. Would you say, with your knowledge, 12 week tests for HIV catch 100 percent of cases for HIV 1 AND 2 ? 

4. I also took a test for Hepatits C  (because of the exposure to blood on day 80 ) because i read a co infection with Hepatitis C delays testing to 6 months. I read this on the CDC guidelines for clinical testing. Would you say i need another hepatitis C test ? does a co infection delay hiv results ? 

Im sorry for taking so much of your time . I wish i had a better way to thank you . 

H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
31 months ago
Thanks for the additional information. You had a zero risk exposure, for all practical purposes, for HIV. I also would not have recommended PEP, and even would have advised that you did not need HIV testing except for its reassurance value. The doctor who advised you was being very careful, but entirely accurate:  in theory, if infected with HIV2 (instead of HIV1, which is far more common in India and elsewhere), it could take a bit longer to develop detectable antibody. But still, 3 months is too long and is old news, going back to older tests. With the 4th generation tests, I've never heard of anyone taking longer than 6-8 weeks to develop a positive result, even for HIV2.

1) People with HIV2 have antigen in the blood, but the standard tests do not detect it -- only HIV1 antigen.

2) The key phrase in this question is "maximum 8 weeks". That means that nobody ever requires 12 weeks. Indeed, many have detectable antigen by 8-10 days. Imagine an asymmetrical bell-shaped curve of time to antigen detection:  starting to rise at 7-8 days; peaking at 15-20 days, when 90% of infected people have detectable atngien; then rapidly dropping (as antibody appears, clearing antigen from the blood), with 95% of people having it by 4 weeks; and then a long tail that hits baseline at 6-8 weeks. Note that it is the antibody that clears the antigen out of the blood. That's why virtually every infected person has antigen or antibody (and sometimes both) in the blood, and therefore a positive AgAb test, by 4-6 weeks. 

3) It's not quite an urban myth that immunodeficiency alters HIV test reliability, but it comes close. This may have been the case with older, antibody-only HIV tests; even then, it was rare if it occurred at all.. With AgAb tests, any impairment of antibody production would mean more persistent and perhaps higher levels of antigen in the blood. Hence no effect at all on the AgAb tests. Equally imporotant, the drugs you mention have trivial immunosuppressive effects or none at all. There are NO medicines, including even the most potent immunosuppressive drugs or illnesses, that alter the reliabilty or tming of the HIV AgAb tests. And if you are outrwardly healthy, there is no chance you have any immune deficiency of importance.

4) I would say that for 6 weeks, maybe 8 weeks to add some extra caution. It probably never takes 12 weeks.

5) In theory, I suppose there could be risk of hepatitis C because of the blood. But very, very small. I recommend HCV testing -- except that everyone ought to be tested at least once. But not because of this event.

Unequivocally you do not have HIV. Don't overthink it:  there are no circumstances that can possibly come to mind that will alter this truth!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
31 months ago
No. 5 should be "I recommend against HCV testing".---
31 months ago
Dear Doctor

I understand the rules for the forum and will make this my last post .Just two quick clarifications

1. So the medications I have are only trivially immunosuppressive and not enough to delay the detection of antibody to hiv 2 - atleast not past 12 weeks ? I ask hiv 2 only because it has no antigen detection in AG AB test .

2. In regards to hepatitis c - I already got the test at 11 weeks . It was negative. Is that enough ? 
Also my original question was that in case I get hepatitis c - does it mean that I need to delay testing to 6 months ? 

31 months ago
I mean incase of a coinfection or an infection of hepatitis c in the same exposure as the possible hiv exposure  - does it delay the conclusive test to 6 months . 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
31 months ago
1) Correct.

2) Because (contrary to popular belief) hepatitis C is almost never sexually transmitted* except among gay men with traumatic (bloody) rectal sexual practices, it's really not an STD and therefore not something I have a lot of experience with in terms of testing after particular exposures. I've just never done it with my patients. But I believe an 11 week negative is conclusive.

* The most recent calculation, from investigators in the Netherlands, is that the apparent risk of HCV transmission, if one partner is infected, is once for every 190,000 unprotected vaginal sex exposures. That's equivalent to sex with an infected partner once daily for 520 years before transmission might be likely. In other words, zero for all practical purposes.

That concludes this thread. Do try to move on without worry and without any further testing!