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DNA PCR Testing Question?
Doc,
I have been searching online for more info regarding DNA PCR Testing of HIV. Across the boards I have seen a negative consenus on using this test for low risk exposures.
What would be the right time window to take a DNA PCR test? The test looks for HIV virus DNA, so wouldn't be more accurate earlier than anti-body. Isn't the DNA present regardless of antibodies?
My concerns are over a 1 time unprotected vaginal sex encounter with a female friend of mine (she said she does not have HIV, she had sex 1 other time only, unprotected though, between her last HIV test (neg)). At 40 days (5 weeks,5 days) I could not deal with the stress anymore and took a anti-body test and DNA PCR test (labcorp test from www.areuatrisk.com) and both were negatvie. I have read all of the posts with time to test positive, etc. If seroconversion hadn't happened at 40 days yet, would a PCR negative results still be valid. The reason why I am posting is at 70 days post exposure I am having some pressure (not necessarily pain) on the left side of my groin (I can't tell if my lymph nodes are swollen) and have had a headache. I really want to move on from this, as I am about to buy my first home and finally start my adult life. After the negative results I was fine, but once I felt some pressure in my groin, I started to be concerned again.
If seroconversion hadn't happend yet at the time of the anti-body test, how reliable would the DNA PCR be at 40 days. Is the false positive rate and cost of the test the real downside to this testing method, but otherwise it is a very good test? there is not a lot of information online about this testing method - besides people recommending not to take it for the false positive rate.
Also, would you recommend a retest?
Thanks for all of your help!
I have been searching online for more info regarding DNA PCR Testing of HIV. Across the boards I have seen a negative consenus on using this test for low risk exposures.
What would be the right time window to take a DNA PCR test? The test looks for HIV virus DNA, so wouldn't be more accurate earlier than anti-body. Isn't the DNA present regardless of antibodies?
My concerns are over a 1 time unprotected vaginal sex encounter with a female friend of mine (she said she does not have HIV, she had sex 1 other time only, unprotected though, between her last HIV test (neg)). At 40 days (5 weeks,5 days) I could not deal with the stress anymore and took a anti-body test and DNA PCR test (labcorp test from www.areuatrisk.com) and both were negatvie. I have read all of the posts with time to test positive, etc. If seroconversion hadn't happened at 40 days yet, would a PCR negative results still be valid. The reason why I am posting is at 70 days post exposure I am having some pressure (not necessarily pain) on the left side of my groin (I can't tell if my lymph nodes are swollen) and have had a headache. I really want to move on from this, as I am about to buy my first home and finally start my adult life. After the negative results I was fine, but once I felt some pressure in my groin, I started to be concerned again.
If seroconversion hadn't happend yet at the time of the anti-body test, how reliable would the DNA PCR be at 40 days. Is the false positive rate and cost of the test the real downside to this testing method, but otherwise it is a very good test? there is not a lot of information online about this testing method - besides people recommending not to take it for the false positive rate.
Also, would you recommend a retest?
Thanks for all of your help!
Teak: I stand by my statement:
http://www.medscape.com/viewarticle/448718_8
"Diagnosis of Neonatal HIV Infection
Qualitative DNA PCR assay is the test most often recommended for neonatal diagnosis of HIV infection. However, the sensitivity of the assay during the first month of life is 50%, after which it increases to above 96%.[30] A meta-analysis of 32 studies using DNA amplification by PCR in infants reported 91.6% median sensitivity and 100% median specificity in the early diagnosis of HIV subtype B infection. Improved viral detection was noted for infants older than 1 month.[34] False-positive and false-negative rates of 1.8% were seen. Thus, DNA PCR assay may not definitively diagnose or exclude neonatal HIV infection; it should be followed by a confirmatory PCR test at 30 days of age and then by sequential PCR testing.[34] Reduced assay sensitivity may be seen in non-B viral subtype infections."
Therefore your original statement that PCR DNA tests are not diagnostic tests is false. That was the statement I was referring to.
http://www.medscape.com/viewarticle/448718_8
"Diagnosis of Neonatal HIV Infection
Qualitative DNA PCR assay is the test most often recommended for neonatal diagnosis of HIV infection. However, the sensitivity of the assay during the first month of life is 50%, after which it increases to above 96%.[30] A meta-analysis of 32 studies using DNA amplification by PCR in infants reported 91.6% median sensitivity and 100% median specificity in the early diagnosis of HIV subtype B infection. Improved viral detection was noted for infants older than 1 month.[34] False-positive and false-negative rates of 1.8% were seen. Thus, DNA PCR assay may not definitively diagnose or exclude neonatal HIV infection; it should be followed by a confirmatory PCR test at 30 days of age and then by sequential PCR testing.[34] Reduced assay sensitivity may be seen in non-B viral subtype infections."
Therefore your original statement that PCR DNA tests are not diagnostic tests is false. That was the statement I was referring to.
You can stand by it all you want, you're incorrect. If you would have looked at the link you posted you would have seen that the information was three years old. The FDA approval date for PCR-RNA was October 5th 2006. A PCR-DNA is NOT approved for a stand alone HIV diagnostic test.
If PCR DNA test is not a diagnostic test then why is it even on market(in specialized path labs) for sale. Will it be correct to say that these labs are fooling people? Why do pathologists, microbiologists give it a high regard as a diagnostic test calling it extremely sensitive. On the other hand, its PCR RNA which is not a diagnostic test as it is meant to check the viral load and do not deal in YES/NO answer. It's just so confusing and is there anything which is completely believable about HIV infection(from window period to diagnostic tests). When, we talk about 4th generation tests being almost conclusive at 6 weeks, why can't we have a combination of DNA PCR and antibody test at 6 weeks and get more reliable results. I suppose DNA PCR is more sensitive than P24 antigen test. A P24 antigen test sensitivity varies anywhere from 60-80 % and PCR DNA sensitivity is supposed to be 96% after 28 days. This all is just too varied information and can send anyone's head for a spin. There are too many factors which come along with HIV related information(financial gains for test providers, CYA attitude, mixed information regarding window period, testing strategies). Seems everyone is just exploiting fear of HIV and nobody is really bothered to to give correct/complete information varying from window period to testing strategies. seems everyone has an agenda. Superficially, it looks that everyone cares to bring and end to this disease in the world and working hard but if you go by the actions and information present in ground reality...then only God can help...
A PCR-DNA is used on people that have HIV to monitor their viral load.
The test used to monitor viral load is PCR RNA Quantitative. Teak, really, PCR DNA is used for diagnostic purposes. PCR DNA is a qualitative test and can not quantitate(measure up) the viral load. It just gives a "Yes" or "No" answer. I am no expert and I can not make you forcibly believe but this I honestly believe is the truth from what I have learned.
O_G it is not an approved as a stand alone diagnostic test.
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