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How Reliable Is PCR Test For HIV After Fifteen Days Post Exposure? Got Negative Rapid Test And ELISA

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Posted on Fri, 7 Sep 2012
Question: helloo sir pls tell me the reliability of pcr test of hiv after 15 days post exposure which came negative,i also had rapid test and elisa for HIV at 84 days and rapid test again after 93 days all negative. i m from india i had unprotected oral and protected vaginal sex with a sexworker in Thailand.
doctor
Answered by Dr. Neelam Ashish Vanjari (22 minutes later)
Hi,

Thanks for writing in.
A PCR test (Polymerase Chain Reaction test) can detect the genetic material of HIV rather than the antibodies to the virus, and so can identify HIV in the blood within two or three weeks of infection.
False positive results are more common than false negatives due to the PCR test's sensitivity, so all positive results must be double checked using a standard antibody test.

Antibody tests are extremely accurate when it comes to detecting the presence of HIV antibodies. ELISA tests are very sensitive and so will detect very small amounts of HIV antibody.

But for you as both PCR and ELISA have come negative, so getting infected with HIV is not possible.

Most people develop detectable HIV antibodies within 6 to 12 weeks of infection; very rarely it can take up to 6 months.

To avoid false negative results due to window period, antibody tests are recommended three months after potential exposure to HIV infection.

A negative test at three months will almost always mean a person is not infected with HIV. If an individual’s test is still negative at six months, and they have not been at risk of HIV infection in the meantime, it means they are not infected with HIV.

So for your satisfaction, you can get ELISA done at interval of 3 months and 6 months.
I hope I have answered your query. Feel free to revert back for further clarification if required.
Best regards,
Dr. Neelam.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Neelam Ashish Vanjari (1 hour later)
Dear Dr XXXXXXX
thanks for the reply.
Madam the first test for HIV was PCR QUANTITATIVE TEST TEST which showed result as Below Detectable limits due to which i am getting confused.pls help me to resolve my querry i am dying due to stress.secondly i m having some painless small ulsers in my mouth.it it a symptom that i m infected.
doctor
Answered by Dr. Neelam Ashish Vanjari (16 hours later)
Hi,

I can understand your concern.
Some painless ulcer could be because of stress induced can be relieved with becasule capsules daily one.

PCR test results have come as below detectable limit means risk of Window period is there which can be of 3 months and rarely of 6 months.

The ‘window period’ means the period of time between HIV infection and the production of antibodies. During this time, an antibody test may give a ‘false negative’ result, which means the test will be negative, even though a person is infected with HIV. To avoid false negative results, antibody tests are recommended 3 and 6 months after potential exposure to HIV infection.

So it is advised to repeat ELISA antibody test at interval of 3 and 6 months.
Always remember negative test at 3 months will almost always mean a person is not infected with HIV. If an individual’s test is still negative at 6 months, and they have not been at risk of HIV infection in the meantime, it means they are not infected with HIV.

So I would suggest you do not take stress and invite stress related illness , rather wait for 3-6 months repeat test to confirm negativity of HIV infection.

I hope I have cleared your doubt. Revert back if you need further clarification.
Best regards,
Dr. Neelam.
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Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Neelam Ashish Vanjari

General & Family Physician

Practicing since :2007

Answered : 351 Questions

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How Reliable Is PCR Test For HIV After Fifteen Days Post Exposure? Got Negative Rapid Test And ELISA

Hi,

Thanks for writing in.
A PCR test (Polymerase Chain Reaction test) can detect the genetic material of HIV rather than the antibodies to the virus, and so can identify HIV in the blood within two or three weeks of infection.
False positive results are more common than false negatives due to the PCR test's sensitivity, so all positive results must be double checked using a standard antibody test.

Antibody tests are extremely accurate when it comes to detecting the presence of HIV antibodies. ELISA tests are very sensitive and so will detect very small amounts of HIV antibody.

But for you as both PCR and ELISA have come negative, so getting infected with HIV is not possible.

Most people develop detectable HIV antibodies within 6 to 12 weeks of infection; very rarely it can take up to 6 months.

To avoid false negative results due to window period, antibody tests are recommended three months after potential exposure to HIV infection.

A negative test at three months will almost always mean a person is not infected with HIV. If an individual’s test is still negative at six months, and they have not been at risk of HIV infection in the meantime, it means they are not infected with HIV.

So for your satisfaction, you can get ELISA done at interval of 3 months and 6 months.
I hope I have answered your query. Feel free to revert back for further clarification if required.
Best regards,
Dr. Neelam.