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What Is The Window Period Of HIV PCR Test?
Question: I went for body to body massage along with hand job done. No Mouth to Kissing was done. She was in underwear, other wise naked and I was also fully naked. No penetration was done. My penis might have touched her vagina / panty: Not sure.
I went for HIV DNA PCR Test ( PCR Qualitative), P24 Anitgen Tests, HIV Antibody Tests after 18.5 days of exposure. All were non-reactive/ Negative.
However, VDRL was positive but TPHA was negative done on after 21 days.
As of now cancres/ spots on body.
What are my risks of HIV / STD? I am bit anxious.
How can I be 100 % sure that I have nothing.Any further tests required?
I went for HIV DNA PCR Test ( PCR Qualitative), P24 Anitgen Tests, HIV Antibody Tests after 18.5 days of exposure. All were non-reactive/ Negative.
However, VDRL was positive but TPHA was negative done on after 21 days.
As of now cancres/ spots on body.
What are my risks of HIV / STD? I am bit anxious.
How can I be 100 % sure that I have nothing.Any further tests required?
Brief Answer:
You seem to be safe.
Detailed Answer:
Hello. Thank you for writing to us.
I have taken note of your query and I have understood it.
As far as the nature of sexual contact is concerned it seems to be safe to me.
Hiv pcr is conclusive earliest at 2 weeks after sexual contact. The test has a short window period of 2 weeks and since you have tested negative at 19th day post sexual contact, that rules out Hiv.
Antibody based tests are not reliable before 4 weeks and may give a false negative result. Therefore you can ignore antibody tests at this stage.
P 24 antigen is detectable earliest at 2 weeks (window period is 2-4 weeks) and therefore a negative test for P 24 antigen at 19th day almost rules out Hiv. However a 4 week test would have been more reliable in ruling out Hiv.
In my view there is no need for any further testing as far as Hiv is concerned because a negative pcr test is sufficient.
At the most you may take a repeat HIV antigen/ antibody test at 4 weeks and that would be conclusive.
Tpha is more specific for syphilis and therefore a negative test for Tpha rules out syphilis.
Herpes can be acquired by skin-to-skin contact with an infected sexual partner even without the actual act of penetration i.e genital rubbing etc.
Though the risk is minimal but you may take a test for genital herpes by Hsv Elisa testing.
This test can be performed earliest at 4 weeks.
Regards
You seem to be safe.
Detailed Answer:
Hello. Thank you for writing to us.
I have taken note of your query and I have understood it.
As far as the nature of sexual contact is concerned it seems to be safe to me.
Hiv pcr is conclusive earliest at 2 weeks after sexual contact. The test has a short window period of 2 weeks and since you have tested negative at 19th day post sexual contact, that rules out Hiv.
Antibody based tests are not reliable before 4 weeks and may give a false negative result. Therefore you can ignore antibody tests at this stage.
P 24 antigen is detectable earliest at 2 weeks (window period is 2-4 weeks) and therefore a negative test for P 24 antigen at 19th day almost rules out Hiv. However a 4 week test would have been more reliable in ruling out Hiv.
In my view there is no need for any further testing as far as Hiv is concerned because a negative pcr test is sufficient.
At the most you may take a repeat HIV antigen/ antibody test at 4 weeks and that would be conclusive.
Tpha is more specific for syphilis and therefore a negative test for Tpha rules out syphilis.
Herpes can be acquired by skin-to-skin contact with an infected sexual partner even without the actual act of penetration i.e genital rubbing etc.
Though the risk is minimal but you may take a test for genital herpes by Hsv Elisa testing.
This test can be performed earliest at 4 weeks.
Regards
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Brief Answer:
Need to repeat hsv test
Detailed Answer:
Hi.
First of all the kind of secual contact that you had...It can be assumed to be safe because there was no penetration involved.
If you go through my reply that is what I said... I said you are safe as far as hiv is concerned but still i asked you to take a repeat Antigen/Antibody test at 4weeks.
There is a proper time to do a particular test. They are reliable only if performed at a proper interval after sexual contact.
I said pcr is conclusive in your case. It can be taken as reliable.
However, negative antibody test at 19th day is too early and does'nt tell anything about hiv risk from this particular exposure. It should not have been even ordered at this stage.
Antibody based tests have diagnostic value ay 4 weeks and beyond...not before that.
P24 Antigen based tests have a window period of detection of 2-4 weeks. Therefore though a negative P24 test at 19th day almost rules out hiv but a 4week test would have been more reliable...therefore i told that you may take a repeat test for Antigen/Antibody at 4 weeks.
Though your negative result with pcr is fine and rules out hiv still it is always better to have 2 negative tests by different assays to rule out hiv...
One was with pcr which was reliable at 2 weeks and therefore there is no need to repeat that. However, to be double sure you may repeat Antigen/ Antibody test at 4 weeks because previous tests were done before 4 weeks had elapsed and were not reliable.
Hsv test at 5 days post contact is too early and does not reliably rule out hsv and therefore you need to repeat this test at 2-4 weeks
Regards
Need to repeat hsv test
Detailed Answer:
Hi.
First of all the kind of secual contact that you had...It can be assumed to be safe because there was no penetration involved.
If you go through my reply that is what I said... I said you are safe as far as hiv is concerned but still i asked you to take a repeat Antigen/Antibody test at 4weeks.
There is a proper time to do a particular test. They are reliable only if performed at a proper interval after sexual contact.
I said pcr is conclusive in your case. It can be taken as reliable.
However, negative antibody test at 19th day is too early and does'nt tell anything about hiv risk from this particular exposure. It should not have been even ordered at this stage.
Antibody based tests have diagnostic value ay 4 weeks and beyond...not before that.
P24 Antigen based tests have a window period of detection of 2-4 weeks. Therefore though a negative P24 test at 19th day almost rules out hiv but a 4week test would have been more reliable...therefore i told that you may take a repeat test for Antigen/Antibody at 4 weeks.
Though your negative result with pcr is fine and rules out hiv still it is always better to have 2 negative tests by different assays to rule out hiv...
One was with pcr which was reliable at 2 weeks and therefore there is no need to repeat that. However, to be double sure you may repeat Antigen/ Antibody test at 4 weeks because previous tests were done before 4 weeks had elapsed and were not reliable.
Hsv test at 5 days post contact is too early and does not reliably rule out hsv and therefore you need to repeat this test at 2-4 weeks
Regards
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Brief Answer:
Tpha is more specific and reliable as compared to vdrl
Detailed Answer:
Hi
Vdrl is a non-specific test and can be false positive.
Tpha for syphilis is more specific and reliable test than vdrl. Since Tpha came out to be negative therefore no more testing is required.
Yes, P24 antigen and HIV antibody test at 4 weeks will be conclusive.
Yes, pcr would test for both types of Hiv.
Regards
Tpha is more specific and reliable as compared to vdrl
Detailed Answer:
Hi
Vdrl is a non-specific test and can be false positive.
Tpha for syphilis is more specific and reliable test than vdrl. Since Tpha came out to be negative therefore no more testing is required.
Yes, P24 antigen and HIV antibody test at 4 weeks will be conclusive.
Yes, pcr would test for both types of Hiv.
Regards
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Sir,
Done Hiv Antibody ( 1 &2) ,Serum Rapid,Enzyme Immunoassay Method: Non-Reactive( Done on 31 day).
Went for following Tests earlier:
1) DNA PCR Qualitative : Non-Reactive for HIV 1 ( Done on 18 days and 18 hrs), No status was given for HIV 2
2) HIV P-24 : Non-Reactive ( Done on 18 days and 18 hrs)
Still HIV P24 required? or these are conclusive.
Done Hiv Antibody ( 1 &2) ,Serum Rapid,Enzyme Immunoassay Method: Non-Reactive( Done on 31 day).
Went for following Tests earlier:
1) DNA PCR Qualitative : Non-Reactive for HIV 1 ( Done on 18 days and 18 hrs), No status was given for HIV 2
2) HIV P-24 : Non-Reactive ( Done on 18 days and 18 hrs)
Still HIV P24 required? or these are conclusive.
Brief Answer:
Enough evidence that you are negative but still I suggest P 24 Ag test
Detailed Answer:
Hi.
As most of the infected individuals have detectable antibodies to HIV at 4 weeks, therefore, antibody based test that you got done on 31 day post sexual contact is reliable and goes to show that you are HIV negative... This along with previous Negative tests like PCR can be taken as enough evidence that most likely you are safe.
However, it is a protocol to re-test for antibody by EIA at 12 weeks in case of a negative antibody test at 4 weeks...this is to cover for the window period HIV.
You can wait for that Or else you can get a P24 antigen test too today and if that is also negative it would be conclusive.
Regards
Enough evidence that you are negative but still I suggest P 24 Ag test
Detailed Answer:
Hi.
As most of the infected individuals have detectable antibodies to HIV at 4 weeks, therefore, antibody based test that you got done on 31 day post sexual contact is reliable and goes to show that you are HIV negative... This along with previous Negative tests like PCR can be taken as enough evidence that most likely you are safe.
However, it is a protocol to re-test for antibody by EIA at 12 weeks in case of a negative antibody test at 4 weeks...this is to cover for the window period HIV.
You can wait for that Or else you can get a P24 antigen test too today and if that is also negative it would be conclusive.
Regards
Note: Hope the answers resolves your concerns, however for further guidance of skin related queries consult our Dermatologist.Click here to book a consultation
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
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