[Question #3169] NAT confusion- Dr Hook?

91 months ago

I hope you can help someone feeling stressed. I am a male and had an encounter with CSW in Beijing towards the end of November. We ended up having unprotected vaginal sex for about a 1/2 hour or so. I came home and after one week started hanging symptoms. This included intense nausea and abdominal pain. This has lasted over a month now.Never had fever or much else but did after 3 weeks have a small bump on my chest that lasted half a day. I also have lost around 6% weight over a month. I was /am so worried they I have taken testing into my own hands without any Dr help. I used an online service which uses LabCorp. I tested for HIV with the duo at 20, 29, 36 days and all negative. Also, at the 29 day test I had a QUANTITATIVE Hiv-1 RNA done to(down to 20 copies Taqman). This was also negative with no hiv-1 detected. After lots of reading i see where that test(Taqman Quantitative) may miss group N,O,CRF types. The only one approved for diagnosis is the Aptima hiv-1 QUALITATIVE. I went ahead and ordered at 36 day mark and still.waiting on results.(back next week)

1)I now have a 36 day duo. How much confidence can I out in that?

2) with my 29 day negative duo and negative PCR QUANTITATIVE, How reliable is that even with symptoms?

3)the fact that I was in China and therefore different strains are prevalent than here in US, How worried should I be that the duo and the PCR(QUANTITATIVE) missed infection like group N, O, or even hiv-2 and that the results I'm waiting on next week(qualitative) coukd show different?

4) Regarding hiv-2, when is the duo conclusive?

5)with all my symptoms I don't see where it cannot be HIV, but tests missing it still. Your thoughts?

6)can you give me your take on the Quantitative PCR like I had(Roche taqman hiv-1 v2.0 vs other Qualitative pcrs thatmsy take more subtypes into account and therefore be more conclusive?

7)should I go for a six week duo if QUAL PCR

I just want this to be over however it turns out as it is constantly on my mind.

Thank you

Edward W. Hook M.D.

91 months ago

Welcome to the Forum. I'll be glad to address your questions. First things first- you did not acquire HIV from the exposure that you have described and your symptoms are due to something other than HIV. Let me provide the basis for my complete confidence in these statements.

First, following any single exposure of the sort you describe, there is little risk for HIV. Most CSWs do not have HIV, including in China. Further, even if your partner had HIV, the statistical risk of infection from a single unprotected exposure is somewhere in the range of 1 infection for every 1000-2000 exposures.

While the odds were in your favor, it is your tests that prove that you were not infected. When symptoms are present, combination HIV antigen/antibody tests are virtually always positive, as are the HIV PCR tests and yours were negative on multiple occasions. Even in persons without symptoms, at 4 weeks (28 days) the "duo" tests are 99% accurate and at day 42 they are 100% accurate. This is true for strains common in China as well.

Finally, the symptoms of the ARS/recently acquired HIV are non-specific and are mimicked by many common, every day flu-like viral illnesses. The tests do a good job of differentiating when symptoms are due to HIV and when they are not. Your negative tests prove that your symptoms are not due to HIV.

Your tests prove conclusively that you were not infected with HIV. there is no need for further testing. I hope these comments will allow you to move forward without continuing concern. EWH

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91 months ago

Good morning and thank you for your reply. Unfortunately, i think there was confusion on the timeline of testing so I will clarify. Also, I was hopeful you would detail the questions I presented. To be fair though, I would hope this is NOT considered a follow-up question and I still have two remaining.

To clarify testing:

-20 day duo negative

-29 day duo negative, hiv-1 quant PCR neg

-36 day duo negative, waiting on Qual

I will copy my original questions

1)I now have a 36 day duo. How much confidence can I put in that?

2) with my 29 day negative duo and negative PCR QUANTITATIVE, How reliable is that even with symptoms?

3)the fact that I was in China and therefore different strains are more prevalent there than here in US, How worried should I be that the duo and the PCR(QUANTITATIVE) missed infection like group N, O, or even hiv-2 and that the results I'm waiting on next week(Aptima qualitative) coukd show different? (Only Qual approved for diagnosis)

4) Regarding hiv-2, when is the duo conclusive?

5)with all my symptoms I don't see where it cannot be HIV, but tests missing it still. Your thoughts?

6)can you give me your take on the Quantitative PCR like I had(Roche taqman hiv-1 v2.0 vs other Qualitative pcrs that may take more subtypes into account and therefore be more conclusive?

7)is the CDC window 42 or 45 days for the duo, when should I repeat.

Hopefully you will give me your knowledge on the above questions.

Thank you

Edward W. Hook M.D.

91 months ago

Your questions were answered. In fact, I provided more information and context to my answers. The fact that I did not answer your questions point by point does not change the answers. This will be considered a follow-up! I will re-answer your questions now, point by point, using the information I provided earlier:

1)I now have a 36 day duo. How much confidence can I put in that?

After explaining that your exposure was very low risk to start with, I said "at 4 weeks (28 days) the "duo" tests are 99% accurate". Date do not exist on the average day-by-day performance of combination HIV antigen/antibody tests. The answer indicated that you could have more than 99% confidence in the test results.

2) with my 29 day negative duo and negative PCR QUANTITATIVE, How reliable is that even with symptoms?

As I said, "the symptoms of the ARS/recently acquired HIV are non-specific and are mimicked by many common, every day flu-like viral illnesses. The tests do a good job of differentiating when symptoms are due to HIV and when they are not. Your negative tests prove that your symptoms are not due to HIV". this answer consider both your NAT and due tests.

As I said, "at 4 weeks (28 days) the "duo" tests are 99% accurate and at day 42 they are 100% accurate. This is true for strains common in China as well" In other words, there is no reason to be concerned that the testing you had would have missed less common HIV sub-types, or HIV-2.

4) Regarding hiv-2, when is the duo conclusive?

Asking the same question again and again does not change the answer. I said "at 4 weeks (28 days) the "duo" tests are 99% accurate and at day 42 they are 100% accurate." 100% = conclusive.

5)with all my symptoms I don't see where it cannot be HIV, but tests missing it still. Your thoughts?

Answered as well: "the symptoms of the ARS/recently acquired HIV are non-specific and are mimicked by many common, every day flu-like viral illnesses. The tests do a good job of differentiating when symptoms are due to HIV and when they are not. Your negative tests prove that your symptoms are not due to HIV." Should I have underlined the word PROVE?

6)can you give me your take on the Quantitative PCR like I had(Roche taqman hiv-1 v2.0 vs other Qualitative pcrs that may take more subtypes into account and therefore be more conclusive?

See responses 2, 3, and 5 above. Commercially available PCR tests are held to the same performance standards as one another by the FDA. Quantitative tests are useful for following the course of HIV following initiation of treatment as well as diagnostically.

7)is the CDC window 42 or 45 days for the duo, when should I repeat

Our answers are evidence based and reflect CDC recommendations. When we disagree or find the CDC recommendations overly conservative we say so. Thus when I said "at day 42 they are 100% accurate.", my response reflected CDC recommendations. Just to be 100% clear, 42 days=6 weeks!

That is also the reason I said "Your tests prove conclusively that you were not infected with HIV. there is no need for further testing." I underlined the last five words so you would not miss it again.

I'm sorry the answers to your questions were not more apparent to you in my original response. That does not change the fact that your questions were answered. Hopefully having excerpted it for you will address your concerns. You have one more follow-up response. EWH

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91 months ago

Ok, sorry I just didn't know how clear I was with everything. I just need to make sure i don't pose a risk to my wife. If you would please give me your thought on these even though a few may seem duplicate.

1)at 29 days after encounter, What are the chances you could have a negative duo AND not detected viral load of <20? Could it take longer for each test?

2)is there any need to wait longer than six weeks for either hiv-1 or hiv-2 because antigen part only for hiv-1?

3)should I do a Hiv-2 DNA test?

4)I see on CDC website where they say 45 days is the window period. Is that not correct?

5)is there any reason I should not have sex with my wife?

6)I should receive the results of my hiv-1 qualitative RNA (Aptima)this week. Is there any reason to think it should show different then my other PCR and will you allow me to post results to share?

7)There would be no other testing that would be any more conclusive than I have at the moment?

I as you well understand only ask detailed questions to make sure I pose no unnecessary risk to others. I would really like to share my results I get with you and that's all(no further questions will be asked). If you would allow that I would appreciate it.

Thank you

91 months ago

My apologies as I failed to ask in bullet 1)--the viral load is as reliable diagnostically as it is when used for monitoring?

Edward W. Hook M.D.

91 months ago

1. Zero. And yes, the qualitative and quantitative PCR perform similarly for purposes of diagnosis.

2. No

3. No

4. The is no meaningful difference between the test performance at 42 and 45 days.

5. No

6. No

7. Your results are conclusive. There is no need for further testing of any sort.

I will leave this thread open for another two weeks. I am confident than any and all further testing related to the exposure you have described will be negative. My replies are now complete. EWH

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91 months ago

Good afternoon. I got the results of my Qualitative hiv-1 RNA and it came out negative. So I now have

1) 20,29, and 36 day duos negative

2)29 day hiv-1 Quantitative negative

3)36 day hiv-1 Qualitative negative

**) I can be completely confident it is not hiv-1 of ANY sort and tests are absolute and hiv-1 not missed ?

I do have a couple other relevant questions regarding testing for HIV and will not ask it here but will submit payment for additional compensation to be fair to you and others.

Thank you

Edward W. Hook M.D.

91 months ago

These results confirm our earlier assessment. You were not infected with HIV by your exposure on concern. The thread will now be closed. If you have further questions, as you note, you will need to open a new question. EWH---