Dr McGowan,

You answered a question today and included the following advice regarding hiv testing,'Generally by 6 months the test should be positive'. It is widely accepted that the window period with modern testing is 3 months, by the CDC as well as every European country, Canada and Australia, and has been for quite some years now - in fact it is documented in the British hiv testing guidelines published in Sept 08 that,'Although fourth generation tests shorten the time from exposure to seroconversion a repeat test at three months is still recommended to definitively exclude HIV infection'. It is frustrating that even though the US government advise the population that a 12 week negative test is definitive and conclusive, answers like this continue to be given and continue to cause unnecessary worry for people who deserve to be told accurate and up-to-date information.

I can understand the frustration in your question.

I practice in New York State. The current recommendation for HIV testing after potential exposure as recommended by the New York State Department of Health AIDS Institute is: "Sequential confidential HIV testing should be obtained at baseline, 1, 3, and 6 months post-exposure even if PEP is declined." This recommendation was last revise January 2008 (www.hivguidelines.org). The CDC recommendations for HIV testing after non-occupational exposure are in line with this recommendation: "All patients seeking care after HIV exposure should be tested for the presence of HIV antibodies at baseline and at 4--6 weeks, 3 months, and 6 months after exposure to determine whether HIV infection has occurred." (Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5402a1.htm). This recommendation was re-iterated in the CDC guidelines (released August 2008) for potential exposure to HIV in a mass casualty situation (available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5706a1.htm?s_cid=rr5706a1_e).

While it is true that the vast majority of conversions will occur sooner it is still the standard recommendation to test up to 6 months and that is the advice I would provide.

Thanks for your question.

Joe