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Dr. Andrew Rynne

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Is the HIV DUO test done after 39 days of exposure conclusive?

Answered by
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Dr. S. Murugan

HIV AIDS Specialist

Practicing since :1974

Answered : 2789 Questions

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Posted on Mon, 12 Nov 2018 in HIV and AIDS
Question: hi doctor I had an episode of insertive oral sex on the 07th January. I did the following tests: - 39 days: duo test hiv 1,2 and/or P24 - 42 days: meia hiv1,2 - 44 days: rapid duo test alere - 44 days: duo test hiv1,2 and/or P24 they have all been done at different laboratories. I am very worried and wanted to know if it can be considered as conclusive? is it true that the CDC advocates duo test at 28 days?
doctor
Answered by Dr. S. Murugan 1 hour later
Brief Answer:
You are free from HIV 1 infection

Detailed Answer:

Hi,

The window period for HIV infection is around 6-8 weeks and may be delayed up to 12 weeks. The HIV DUO test consists of two parts. Antigen detection - may detect the infection as early as 7 days, but considered conclusive only after 4 weeks. In addition to that, this antigen detection portion can detect only HIV 1 infection and not HIV 2 infection. The other part of the test can detect both HIV 1 & 2, but can be considered conclusive only after 12 weeks post the exposure.

You had your last test 44 days after the exposure. This ruled out the possibility of HIV 1 infection and not HIV 2 infection. However, with regard to HIV 2 infection, only after 12 weeks it can be considered as conclusive. HIV 1 infection is common throughout the world except in certain parts of XXXXXXX to the extent of more than 99%, whereas the prevalence of HIV 2 infection is less than 0.5%.

Hope I have answered your query. Let me know if I can assist you further.

Regards,
Dr. S. Murugan,
HIV AIDS Specialist
Above answer was peer-reviewed by : Dr. Raju A.T
doctor
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Follow up: Dr. S. Murugan 3 hours later
I understand that I am still at risk for hiv2. if the window period is 6-8 weeks, does that not compromise my tests?
doctor
Answered by Dr. S. Murugan 7 hours later
Brief Answer:
You are free from HIV 1 infection and almost free from HIV 2 infection.

Detailed Answer:

Hi,

First of all, oral sex carries a low risk when compared to anal or vaginal sex as per CDC XXXXXXX USA.

The prevalence of HIV 2 infection is lesser than 0.5%. Transmission of HIV 2 through oral sex is unheard of.

Your HIV DUO test is a highly reliable test to the extent of more than 99% only when it has been done 12 weeks after the risk activity. Before which, the reliability would be lesser and cannot be considered as 100% conclusive. I hope you got this point. Your HIV 2 risk is very very remote!

Hope I have answered your query. Let me know if I can assist you further.

Regards,
Dr. S. Murugan,
HIV AIDS Specialist
Above answer was peer-reviewed by : Dr. Raju A.T
doctor
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Follow up: Dr. S. Murugan 2 hours later
is it possible to develop antigen after 6 weeks?
doctor
Answered by Dr. S. Murugan 39 minutes later
Brief Answer:
Antigen titre may increase during the time as they multiply!

Detailed Answer:

Hi,

Antigens are present with organisms if it enters into someone's body. The test has to recognize the same. In low quantity, it could be missed. 3-4 weeks after the entry of organisms, due to increased amounts, it would not have been missed.

Antibodies have to appear inside the body to fight this organism. It will be recognized by the body as a foreign one and produce antibodies. The body will take some more time to complete this process. This period is called a window period and may be prolonged up to 12 weeks.

Hope I have answered your query. Let me know if I can assist you further.

Regards,
Dr. S. Murugan
HIV AIDS Specialist
Above answer was peer-reviewed by : Dr. Nagamani Ng
doctor
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Follow up: Dr. S. Murugan 5 hours later
first you say that the test is conclusive. that it should have detected p24 antigen by then. then in your second message you state that the duo test is only reliable at 12 weeks. it's confusing. thereafter you state that the antibodies take more time to come up, i.e. up to 12 weeks. at 12 weeks there is no need for a duo test if it's only antibodies.
doctor
Answered by Dr. S. Murugan 1 hour later
Brief Answer:
Your HIV 2 risk is remote.

Detailed Answer:
Hi,

P24 Antigen of HIV 1 infection can be identified by the HIV DUO test as early as 7 days and becomes conclusive by 4 weeks. So your negative DUO tests have confirmed that you are free from HIV 1 infection. Regarding HIV antibodies, detection will be conclusive only by 12 weeks.

With DUO test after 12 weeks, the reliability is 99% or more whereas it would be around 97% with other types of HIV tests.

In your case, you had only oral sex and HIV 1 is already ruled out, so your risk for HIV 2 infection is very very remote.

Hope I have answered your query.

Regards,
Dr S Murugan,
HIV AIDS Specialist
Above answer was peer-reviewed by : Dr. Nagamani Ng
doctor
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