I have a friend who is trying to take control of his life and went in for a routine medical check to verify that everything was alright. When we got the results of his bloodwork back it shows that he tested positive for hiv. I question the results of this test because the detection method used was a western blot. The results showed only P24 was present. White blood cell count normal. His last sexual encounter was in November of last year with a female partner of unknown health status. He believes they used protection but cannot remember. He would also qualify for the high risk group. My question is what are the odds that he is truly HIV positive. As all they did was tell us he is HIV positive and the test is 95% accurate. My research seems to indicate that this test is only 85% and indeterminate results are fairly common. Given that an uninfected individual can carry some of the antibodies it detects. No other screening methods were used. We now have to wait three weeks for a follow up test. With no counseling scheduled. Could you please help?

Hello,

Unfortunately I cannot give you a specific answer, because I cannot determine from your post exactly what tests were run and what interpretation was given.

Western Blot (WB) tests should not be used for routine HIV screening, because indeterminate test results can occur in 4% to 20% of WB assays.

The standard screening for HIV consists of an ELISA followed by a confirmatory WB if the ELISA is "repeatedly reactive." That is the only criterion for ordering a WB test. WB testing must always be coupled with ELISA screening, due to a 2% rate of false positives. A positive WB needs to have reactivity to gp120/160 plus either gp41 or p24. If your buddy only had p24, his test would be labeled indeterminate, not positive.

I see no reason to wait three weeks for a follow-up test. A rapid test will give you an answer in 20 minutes.

Good luck!

Dr. Bob