Western Blot Accuracy

I received a negative Western blot test (no bands) two months following a low risk exposure in March of 2010. I knew little about the various testing methods at the time I took my test, so the only reason the WB test was ordered without an ELISA was because I specifically asked my GP for it. Having actually done some research since, I understand that WB tests are almost always used as confirmatory tests following a positive ELISA. Regardless, I was wondering if I could consider this test definitive, as it was taken 8 weeks following my potential exposure.

Information regarding HIV testing guidelines on the internet can be pretty convoluted -- some sites claiming that the WB test takes longer to become positive than other antibody tests. However, I've come to understand (I think, hence this question!) by reading through this forum that all HIV tests taken 8 weeks following a potential exposure are considered definitive. Would love to know if this is the case in my situation.

Thanks in advance.

[H. Hunter Handsfield, M.D.]

Welcome to the forum.

It was a mistake for you to insist on the Western blot.  Had you come to my clinic, we would have refused your request.  A negative ELISA, by itself, is 100% proof against HIV if done mor ethan 6-8 weeks after the last possible exposure.  WB was not designed as a primary test -- it's only value is in confirming a positive ELISA.

And yes, "this is the case in [your] situation" -- since it is the case in everybody's "situation".  You can be 100% certain you do not have HIV.

Regards--  HHH, MD

[testquestion123]

Thanks, Dr. Handsfield. I really appreciate your timely response. The work both you and Dr. Hook do here is very much appreciated.

1) Just to clarify, though -- why is it I can rely on this test result, considering I used it as a primary test (at 8 weeks) and that "it's only value is in confirming a positive ELISA," which I never had.

[H. Hunter Handsfield, M.D.]

WB performance has never been formally studied as a primary screening test.  However, the biology and technology of the test indicate the result should be completely reliable.