confused over window period

[Edwin90]

The information you have provided is so helpful but there are a lot of confusion regarding window period and the use of DNA PCR as a screening tool. You cited that the window period for rapid antibody test is 3 months but here in Zimbabwe, if you go and get tested 90 days interval, you will be told to come back at 6 months and even 12 months for conclusive result. What is the actual HIV window period for antibody rapid test (Alere determine). On PCR apart from been expensive, what are the reason why it is not recommended for HIV screening.
Thank you.

[Edwin90]

Thanks Teak

[Teak]

No, they don't, you are not comprehending what you read.

[Edwin90]

Teak you haven't answered 1st part of the post because the CDC guideline gives a second window period upto 6 months

[Teak]

3 months is the guidelines.

[Edwin90]

Teak and diver58 am failing to understand this from CDC especially on the part within the 1st 3 months, does this mean before 3 months and repeat testing should be considered > 3 months can mean 6 month.

[ If the initial negative HIV
test was conducted within the first 3 months after exposure,
repeat testing should be considered > 3 months after th e
exposure occurred to account for the possibility of a false-
negative result. If the follow-up test is nonreactive, the client
is likely not HIV-infected. (Copied from CDC)

Secondly the Determine HIV 1/2 antibody, Elisa test didn't see them in the approved hiv kit list of the current update on the current HIV testing algorithm recommendation of 27/06/14 by CDC. Does this means these are not supposed to be used for screening since you disregard DNA PCR as a primary screening test.

3rdly all the guidelines seems to be subjected to USA, what about 3rd World countries, are these guidelines universal.

[diver58]

They are not the primary screening tests

[Edwin90]

Thank you for your responses. You highlighted that DNA PCR has a high rate of 'false positive'. What if the result came negative, is there any rate of 'false negative' on DNA PCR test.

[Teak]

http://www.cdc.gov/globalaids/Resources/pmtct-care/docs/TM/Module_6TM.pdf
Page 11
#4
  In an adult, a positive HIV antibody test result means that the person is infected, a person with a negative or inconclusive result may be in the “window for 4 to 6 weeks but occasionally up to 3 months

[diver58]

Though the currently available fourth generation HIV tests are capable of detecting HIV antibodies with more than 99% accuracy after 6 weeks, CDC's recommended guideline remains 3 months. 6 months is an old story and may be in your country they still follow the old guidelines.

PCR is not a screening test because it is used for monitoring and tracking of the virus and the efficacy of the treatment, along with other tests. It also has high rate of "false positive" apart of being expensive.