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Dr. Andrew Rynne

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How accurate is DNA PCR test for HIV?

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Dr. Vivek Chail

Radiologist

Practicing since :2002

Answered : 6519 Questions

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Posted on Tue, 5 Aug 2014 in HIV and AIDS
Question: Hi Doctor, i had unprotected sex i am scared about HIV where i am sick and infected with mouth ulscar and sore throat on 40th day i meet the doctor,where he asked me to take DNA PCR Test which went Negative. But i am scared about HIV as he wants me to take ELISA test after 13 weeks . so i want ti know how accurate is DNA PCR Test is and is there any chances of HIV positive even i got Negative in DNA PCR test after 40 days
doctor
Answered by Dr. Vivek Chail 55 minutes later
Brief Answer:
DNA PCR is more than 90 percent reliable

Detailed Answer:
Hi,
Thanks for writing in to us.

I have read through your query in detail.
Current research studies show that after possible HIV infection, proviral DNA is present within hours of infection, but reaches detectable levels around 10 days after infection. In some persons it may take up to 21 days to reach detectable levels. It means that 2-3 weeks after infection, there will be enough viral material for a positive result.

Keeping the above in mind, your tests are indicative of no HIV infection. DNA PCR is more than 99 % reliable but guidelines say HIV testing must be repeated after 12 weeks or 90 days.

ELISA is a widely employed immunological assays for serodiagnosis of HIV infection. It measures antibodies to HIV infection and is a double confirmation based on the reaction of the body to HIV infections.

The testing guidelines for HIV are to be initially tested at 3 weeks post exposure and then again at 90 days.

Since testing by one method shows negative, you may procced for another test after 13 weeks (90 days) to confirm negative.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Vivek Chail 11 minutes later
I am experincing the symptoms like sore throat, mouth ulscar, headache,sick , so i would like to know will there be chance of HIV positive result after 3+ months even after i got DNA PCR test at negative after 40 days.
doctor
Answered by Dr. Vivek Chail 2 hours later
Brief Answer:
Chance of having HIV after 40 days is almost nil

Detailed Answer:
Hi,
Thanks for writing back with an update.

There are many other conditions other than HIV which may be affecting you. Among them the commonest is seasonal infections like common cold and flu. These usually subside on taking symptomatic medications. As the rains have just started, you need to take precautions to avoid getting cold. Sore throat, headache are possible symptoms of flu. The mouth ulcer if not healing with time may need to be seen by a doctor. It is possible that you might have got sexually transmitted infections while having unprotected sex which might have involved oral contact. Doing a STD panel tests will confirm and most infections are treatable.

The chance of having HIV after 40 days is absolutely low.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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