[Question #1635] Hiv type 2 window period

Avatar photo
89 months ago
Hi. Doctors

Thanks for your help in advance.

I have complety ruled out HIV-1 infection after having done four, 4th Generation combo test. At ,9,10,11,12 months after condome break with a CSW.
I was the insertive male with an unkow satus female vaginal sex.
I just wanted some clarification on HIV-2 window period.
I know HIV2 is rare in USA however The CDC website doesnt have info on HIV2 window period.

1. What is the window period for HIV2 with the 4th Gen test since the P24 antigen part of the test is just for HIV-1 detection.

2.I read a post that Dr. Hunter wrote:
In theory, the test might not detect all HIV2 infections at 4 weeks, but very nearly so and in the real world a negative result at 4 weeks is considered conclusive for both HIV1 and HIV2. 

What does this mean?
Could you please explain this for me?

3. Would I be conclusive to be HIV2 negetive after 12month negative with 4th gen?

4. What is the longest window period for HIV2 that you have seen or heard of?

Avatar photo
Edward W. Hook M.D.
89 months ago
 Welcome to our forum. I will be glad to address your question.   As you point out HIV2 infections are quite rare in countries other than those of western Africa so the chances that you acquired HIV-2 are quite small.  Further, the antibody detection portion of fourth generation tests for HIV detect of HIV-1 and HIV-2.  Thus,  while it is possible, as you point out in your question, for the antigen detection portion of these tests to miss HIV-2,  each of the tests that you had performed at nine, 10, 11, and 12 months has proven that you were not infected with HIV  of any sort through the encounter did you mention.   Your test results are conclusive for both of HIV-1 and HIV-2.  It is time for you to move forward without concern. 

 I hope that my comments will help you to do that. EWH
Avatar photo
89 months ago
Thank you Doctor for your answers.
It was very helpful. I will move on from this concerns. 

Just for my personal knowledge:

1. What is the official guidelines for Hiv-2 as far as Window period. I didn't see anything in the CDC website.

2. Do you ever see the CDC change the official window period in the future to a shorter window period?
Since you have seen the results of 4th gen test not change after 4 weeks in real world situations.

3. Why are 4th gen test perferd over RNA test other than cost?

Thank you once again.

Avatar photo
Edward W. Hook M.D.
89 months ago

1. "official" guidelines for HIV 2 seroconversion are not specifically present given the rarity of the infection and the fact that the natural history of this infection is essentially the same as for HIV-1.

2.  No, the CDC will not change the "window" period.  I  have pasted in a recent explanation of this that Dr. Handsfield wrote for you to read.

" CDC developed its advice before 4th generation tests became available. The first reason is that many government agencies generally take conservative positions on prevention advice, and 3 months does that. Second and perhaps most important:  As a government agency, CDC's advice usually must be consistent with the official information provided by the test manufacturers in the tests' package inserts. That information is based on original research, before the tests were marketed, and much of that research is conducted in a way that probably underestimates the tests' true performance. In any case, that information cannot legally be changed unless and until the test manufacturer conducts and new research to justify the change, and that research is vetted and approved by the US Food and Drug Administration. That's a very expensive process and therefore is rarely done. Other research, or the clinical experience of experts using the tests in the real world, and theoretical considerations about how the tests work may not be used to justify a revised package insert or any other information provided to the public. However, independent experts do not have those restrictions and can give advice based entirely on their clinical experience and their interpretation of the science of the tests and published science. That's what we do on this forum."

3.  Because the 4th generation tests, by virtue of the fact that they detect HIV antigen as well as antibody, become positive earlier than antibody only tests.


Avatar photo
89 months ago
Last question.

I have been having recurring folliculitis for over 6 months so I wanted to check my immune system and 
I had a cd4/cd8 test done and got results back.
These were the results :

Cd4 count: 818 range 359 to 1519
Cd4 percentage 30.3 range is 30.8 to 58.5
Cd8: 621. Range 109to897
Cd8 percentage: 23. Range12 to 35
Cd4/cd8 ratio: 0.92 to 3.72
I also had an Hiv rna test Negetive after 12 months of exposure.

My cd4 percentage was low according to the labcorp report.
Could you please explain this.
Should I seek any more testing for hiv.
After having multiple hiv negetive results.

Thank you very much doctor for your help.

Avatar photo
Edward W. Hook M.D.
89 months ago

Measurement of the CD4 count is not a recommended tests for persons who do not have HIV as CD4 and CD8 concentrations may vary.  Your CD4 count is in the normal range and your CD8 count is not concerning low.  Given your test results, it certainly does not suggest HIV.  You do not have HIV and do not need further testing for the exposure you mentioned.  My advice is to put your concerns aside and try not to worry. 

I hope my comments have been helpful.  Our Forum Guidelines permit up to three answers per question. This is my third reply to you.  Therefore this thread will be closed later today.  Take care.  EWH