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Avatar universal

HIV Testing Assessment

Hi Docs,

I have a testing question that hopefully you can answer for me.  I had sex with a CSW at the beginning of October.  I have had multiple symptoms including fever at 3.5 weeks post exposure.  I tested negative at 2 weeks, 4 weeks, and 7 weeks using a antibody test.  I also tested negative 13.5 weeks post exposure on a PCR test.  I some Feelings of being ill, upset stomach, soft stool, sore neck, sore throat.  Here are my questions;

1.  Do I need to follow the PCR with an antibody test and do PCR tests have a lot of false negatives?

2.  My understanding is a PCR test looks for the virus itself.  Can my bodies immune response make the virus undetectable to the test?  I read after converting a persons immune system fights back against the virus.

Thanks!!
11 Responses
239123 tn?1267647614
MEDICAL PROFESSIONAL
Welcome to the forum.  Thanks for your question.

One of the most common themes on this forum -- I think I have written a version of the following 10 times in the past week -- is that the HIV blood tests are among the most accurate diagnostic tests that exist, for any medical condition.  If enough time has passed since the last possible exposure, the results are 100% reliable -- and that time is 4-8 weeks (rarely up to 3 months), depending on the specific test or combination of tests.  For those reasons, test results always overrule exposure history and symptoms.

So your test results prove with 100% certainty that you didn't catch HIV during the exposure described.  You don't describe the details of your exposure or your symptoms, so I can't really comment on them. But neither matters anyway.  Regardless of how high the risk seemed at the time, or how typical your symptoms may be for a new HIV infection, your test results show you aren't infected.  (And in any case, your symptoms are not suspicious, and almost nobody catches HIV from a single exposure to a female sex worker.)  To your specific questions:

1) There are virtually no false negative PCR tests more than 10-14 days after onset of a new HIV infection.

2) Antibodies and the immune response to HIV never entirely eliminate HIV from the blood and do not change the reliability of the PCR test.

In reply to the follow-up question below, the PCR test is very hardy.  You can almost cook the blood specimen, or immerse it in dry ice -- the test works just fine.  (PCR is the method that detects DNA in tissues of mammoths or saber toothed cats dead for 10,000 years!)

So all is well; for sure you don't have HIV. No further testing is needed.  See your doctor if any symptoms continue to bother you, but you can be sure HIV isn't the cause.

Best wishes--  HHH, MD
Avatar universal
One other thing.  I'm sure it a just paranoia but can shipping the blood to the lab in really cold weather impact the PCR test?
239123 tn?1267647614
MEDICAL PROFESSIONAL
See above.
Avatar universal
Thanks for your help!!  You put me at ease.  I just wanted to take the opportunity to ask tell you the exposure and symptoms and ask a follow up question.  The exposure was unprotected vaginal sex with a CSW in Las Vegas.  My symptoms included after 23-24 days a fever of 102, sore throat, night sweats with the fever which would go high at night and break, sore neck and collar area, loss of weight (8-10 lbs) which started earlier, appetite loss, soft stool, and white tongue (which doctor believes is a film).  My 90 day PCR test was a HIV RNA Quant by PCR.  It says "HIV-1 RNA was quantified by cobas aplified/ cobas taqman HIV-1 test, version 2.0.  The quantification range of the assay is 20-10,000,000 copies of HIV-1 RNA/ml of plasma.  An internal control was added to the specimen before viral nucleic acid extraction to rule out PCR inhibitation.  A "not detected" results and HIV-1 RNA was not detected and the internal control amplified in the specimen.  A result of "HIV-1 RNA detected, less then 20 HIV-1 RNA copies/ml" means that HIV-1 RNA is detected, but the level is below the quantifiable limit of the assay."

On this test I was not detected.

My questions are;

1.  I read that PCR tests are not diagnostic but both you and my doctor feel my results are conclusive.  Is this based on my negative antibody tests at (2, 4, and 7 weeks) combined with this result or on a stand alone basis?  Also sounds like with the described symptoms happening prior to the tests the antibody test at 25 and 50 should have been positive, correct?

2.  What exactly is the difference between the PCR DNA and RNA test and why give one vs the other?

3.  Reading the blurb on the test I believe there are theree conclusions, detected, not detected, and detected but not quantifiable, is that correct?

4.  Just for final piece of mind and to end this discussion can you tell me what all the internal control talk is in the blurb.  Sounds to me like they put an internal control in the blood before starting and in order to get a negative result the internal control must amplify (as well as no detection) which would mean the test is working as intended.

Thanks again!!  
Avatar universal
Hi Doctor, I wanted to add one last item to my above questions.  What about HIV-2 if the PCR is only detecting HIV-1, is this a concern in the U.S.?
239123 tn?1267647614
MEDICAL PROFESSIONAL
These questions are beyond the intended scope of this forum.  You don't have HIV -- that's generally as far as we go in interpreting test results.  Briefly:

1) Correct on all counts.

2) DNA and RNA testing are different technologies to achieve the same results; beyond that, it's too complex for a brief reply.  You'll have to do your own research.  

3) There are stern regulatory requirements about what package inserts can say and you can be confident that the information in them -- whether for drugs or lab tests -- are factually correct.

4) "Internal control" refers to running known positive and negative specimens along with the patient's specimen.  To my knowledge, nothing is added to the patient's specimen.

HIV-2 is virtually absent in the US.  And in your case, it doesn't matter whether the PCR will detect it.  Even without PCR, your negative antibody tests are proof you didn't catch HIV of either type.

That will end this thread.  Do your best to move on without further concnern.
Avatar universal
Since I took my PCR RNA test 13.5 weeks post and my antibody blood test 7 weeks post does that matter?  Should they have been taken simultaneously?  After this I'm moving on or at least trying to move on.  Thanks for your help.
Avatar universal
Looks like you are negative. R u still feeling ill???
Avatar universal
I have a tingling sensation in upper back, sore throat/neck, and softish stool not diarrhea, and sometimes an upset stomach.  My doctor has said my results are conclusive and so has HHH.  I think the doc and HHH are good but I just want to be certain I don't infect anybody and get treatment if necessary.  I don't want to miss anything!!  I also took a oral swab test at 17 weeks which was negative.
Avatar universal
My tongue is also still white
239123 tn?1267647614
MEDICAL PROFESSIONAL
There's no reason for the various types of test to be done the same day.  Your results prove you don't have HIV.  Believe it, stop worrying, and move on.  If you want to carry on a conversation, please take it to the community forum.  This thread is closed.
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