Window Period for HIV 2

[passive143]

Hello Doc:

I have 2 specific questions for you below:


1.
What can you tell me about the window period for HIV2?  Is it the same as for HIV1?

You answered a question for me back at the end of May 2006 (5/30 or 5/31).  The question I asked you was in reference to the likelyness that I could have HIV despite a negative 6 month test.  You gave me the probablity and it came up to be something like 1 in 100 million based on the exposure-scenario I explained to you.  


2.
Can the probablity you gave me for the chance I have HIV despite my 6 month negative test also be figured for HIV2?


Thank you,

[ConcernedNY]

Doctor,


From what I have read it seems as though most HIV-2 cases would most likely show a positive or indeterminate on an HIV-1 standard EIA screening for type 1.  Would you concur with this?   According to the CDC it appears as though there has only been around 100 reported cases in the US so in light of this does a possible exposure to a high risk individual warrant testing for both?

[Ronnie99]

no-idea: There is a test for HIV-2 available in the US but it needs to be ordered separately. That is what the testing company told me. I had both tests.

[H. Hunter Handsfield, M.D.]

Many providers and labs in the US routinely test for both HIV-1 and -2.  Last I heard, something like 40% of all tests now include HIV-2.  It also is my understanding that it's still true that no endogenously transmitted HIV-2 infections have been detected in the US, only imported cases.

HHH, MD

[raustin]

I know when I took my (3)elisa test they did not include hiv2 testing, the internet site I used said they were newer generation test but they do not even have a test for hiv2 as all cases in U.S were diagnosed here but aquired elsewhere. They counselor I spoke yold me unless I had been with someone from South Africa not to even worry about it. What do you think doc?

[Ronnie99]

As noted by the doc, HIV-2 is extremely rare in the US. As far as I understood it though regarding Elisa tests and HIV-2, there is a separate Elisa that detects HIV-2. The reason I say this is that when I was being tested they gave me an option of just the HIV-1 Elisa, or a two-for one order that had two separate tests, one for HIV-1 and one for HIV-2. Since I'm paranoid, I asked to be tested for both. I'm not 100% certain on the facts about this, but this is what the testing people gave me as options.

[Ronnie99]

As an aside for those interested, the OraQuick saliva HIV test does screen for both HIV-1 and HIV-2 (I now because I took that test and read up on it).

[H. Hunter Handsfield, M.D.]

To my knowledge, the seroconversion time (window period) is no different than for HIV-1.  The probability calculations applies even more strongly to HIV-2.  Since fewer than 1 in 1000 HIV infections in the US and most industrialized countries are HIV-2, you can take the 1 in 100 million and reduce the odds 1000-fold, i.e. to 1 in 100 billion.

HHH, MD