chance of false negative result

[elei]

I talked to my docotor today,got the name of my tests,  the first screening test was Elisa, which was positive, the second one was western blot which shows negative.. Doc said I need to get tested again... Could anyone tell me what is the chance for a false negative western blot test after 5 month exposure?

[michaeljackson]

Hi, I recently got a positive ELISA and Negative WB twice in 30 days.  I was negative for ELISA back in November and May 1.  But I recently got a vaccination (Gardisil) in May and I took another ELISA Test May 30 and it was positive and the WB was negative.  Do u think that had something to do with it?

[WorriedT]

I second what Dobber has said.

Ainxtein actually found a report from a Chinese website of someone testing in this way (positive for ELISA, negative with Western blot) for beyond 3 years.

In the end, the Western Blot is more specific. Asking Dr H what to do is a good way forward.

[dobber21]

I don't think that's accurate, but I'm not entirely sure, ,and more importantly I'm not a doctor! I think you should ask this question in Dr Handsfield's forum because he is the expert.

What I do know is that the ELISA is extremely sensitive, which gives it a high rate of false positives. It detects HIV ANTIBODIES, but sometimes is so sensitive that it will detect antibodies to other conditions as well.That is why it is never used to confirm HIV infection. Certain conditions can result in a positive ELISA even when HIV is not the cause; I think Lyme's disease is one, lymphoma another, even recent  immunizations can cause a positive ELISA.

Have you been recently immunized?

Bottom line; it's the negative WB that counts, if you receive another positive ELISA followed by a negative WB I'd let this go. But only you can do that.

I really would ask Dr. H about this:)

[mike_no]

okay, c'mon cheer up, girl, elisa can some times pick up false positive however you've got your western blot negative thats the end of all your worries, it's very very unlikely that your third test result would change.

[tarikida]

elie, kimoz is correct on elisa and western blot testing. So you are safe. If you do one more test for elisa, it might show negative. That is the characteristic of elisa test

[anxious76]

From all of the information I have read, false positives are more common than false negatives, which rarely occur.  The majority of people that produce false negatives are likely testing in the window period.  Another cause would be late seroconversion, but I believe that only occurs when your immune system has been compromised through something such as heavy doses of chemotherapy.

Best of luck!

[dobber21]

You could take ten more elisas, they could all be positive, but if the WB is negative, that means your negative. Lots and lots of things cause false positive Elisas, I know that a Hep B vaccination can be one of them. There are many others.

Basically if you have a negative WB you're home free.

But test again by all means if it will put your mind at rest:)

[elei]

thanx to all.. I sure feel a lot better after i know it was western blot test ... but still quite worried abt this......hope all the worries will be over next week... God bless me!!..

just wondering what if th next test is still postive on Elisa, negative on WB... do i have to keep get tested untill they are both negative? cuz the doc told me they both have to be negative, or the test is inconclusive

[Alex73]

OK, fasle positives can be very hard to deal with. I have experienced one myself and was an emotional wreck. I kept testing for months after.

I don't want you stress out like me, as far as HIV testing goes no test is more specific than Western Blot. It is the "gold standard"as far as confirmatory testing goes.

Therefore you are negative. But as has been suggested have another Elisa to quell your anxiety, if it is negative, stop all testing. This would mean whatever was interfering with your results has been resolved. If it is positive, don't panic, have another WB which will be negative and then forgot abot this whole episode.

stay safe

[WorriedT]

You should believe the Western blot. The reason why is that Western blot USES highly specific Abs to detect actual HIV proteins, while the ELISA detects the body's own Abs to HIV. It means that you can get interference with an ELISA test as the body is making new Abs to infections all the time, some of which can be relatively non-specific.

It's very, very unlikely your Western blot will be a false negative.

[kimoz]

From what I heard, if you have negative western blot after 5 months of exposure, then you are probably negative. Elisa does sometime pick up other things and shown false positive, as it is very sensitive but western blot is more specific, which is why 2 test is need for a conclusive result.