Are HIV tests accurate?

Jake asked: I’ve done some reading and according to the Centers for Disease Control and Prevention, the tests don’t look for HIV, rather, they look for antibodies.
“Once HIV enters the body, the immune system starts to produce antibodies – (chemicals that are part of the immune system that recognize invaders like bacteria and viruses and […]

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added by World's Best with 5 comments.
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HIV
Jake asked:


I’ve done some reading and according to the Centers for Disease Control and Prevention, the tests don’t look for HIV, rather, they look for antibodies.

“Once HIV enters the body, the immune system starts to produce antibodies – (chemicals that are part of the immune system that recognize invaders like bacteria and viruses and mobilize the body’s attempt to fight infection). In the case of HIV, these antibodies cannot fight off the infection, but their presence is used to tell whether a person has HIV in his or her body. In other words, most HIV tests look for the HIV antibodies rather than looking for HIV itself.”

http://www.cdc.gov/hiv/topics/testing/resources/qa/tests_work.htm

According to what they’re saying, if you have antibodies present in your body when you get tested, your test will come out positive.

Since the same antibodies are used to fight off other virus’ and bacteria, how can the tests give accurate results?
In response to Jay Jay: Here is an example:

http://news.xinhuanet.com/english/2007-12/06/content_7211617.htm
I’ve done more research and found out that ELISA tests and Weston blot tests only test for non-specific virus’/bacteria. And on top of this, the methods used in the tests are controversial:

http://www.virusmyth.com/aids/hiv/rgelisa.htm

This has raised a huge red flag on the validity of the tests.
To Flowerman:

I thought we all have HIV antibodies? Doesn’t the test done in the last link confirms this?
Correction to my previous edit; the ELISA test only looks for non-specific proteins, which is why the presence of antibodies sets it off.

According to the test done in http://www.virusmyth.com/aids/hiv/rgelisa.htm, everyone will show up positive if their blood is not diluted a certain way. This suggests that everyone has HIV, but to certain degrees. This would also explain why someone who might test positive in the US but not in another country. There is no “global gold standard” dilution of the blood when doing this test. It could be 1:400 in the US, but 1:800 in Australia, which would make it twice as hard to be positive in Australia (this isn’t fact, just an example).


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Written by World's Best on February 4th, 2008 with 5 comments.
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Get your own gravatar by visiting gravatar.com Jay Jay
#1. February 4th, 2008, at 8:22 AM.

I DON’T KNOW BUT SO FAR THEY ARE PRETTY ACCURATE I MEAN HOW OFTEN DO YOU HEAR ABOUT SOMEONE BEING TOLD THEY HAVE IT AND YEARS LATER FINDIN OUT THEY NEVER EVEN HAD IT???

Get your own gravatar by visiting gravatar.com Snout
#2. February 4th, 2008, at 1:41 PM.

Yes they are, if used correctly.

Antibodies are proteins produced by the immune system. They have all differently shaped tips, called antigen binding sites. Each type is specifically shaped to fit a particular antigen, (usually a protein or polysaccharide), on the target virus or microrganism, like a key with a lock. For example, the p24 antibody is shaped to fit the p24 antigen, and the hepatitis B surface antibody is shaped to fit the hep B surface antigen protein, and so on.

The antibodies tested for in an HIV test are antibodies that specifically fit antigens on the HIV virus particle, not just any antibodies that happen to be circulating in the blood.

—————————————————-

From your link:

“I can only remember one or two cases in the world about people claiming themselves to be HIV negative several years after they tested positive,” said [chief scientist] Shao. “And scientists still harbour doubts over those cases,” he said.

False positives can occur with any testing process, but they are extremely rare with HIV antibody tests done according to correct protocols.. There are more than two cases out of the many millions of tests done so far, but not many more than that.

The false positive rate is generally between 0.0004% and 0.0007% of tests done according to the protocol necessary to make a diagnosis of HIV infection (repeatedly positive ELISA plus positive Western Blot).
(and check the links for the actual research)

It is one of the most accurate tests in medicine.

Get your own gravatar by visiting gravatar.com Erki T
#3. February 4th, 2008, at 7:19 PM.

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Get your own gravatar by visiting gravatar.com Jen
#4. February 8th, 2008, at 5:01 AM.

Your body develops specific antibodies to fight off each individual infection it contracts, it’s not a “one antibody fights all” situation. So if you have antibodies to HIV in your blood, it means that you DO have HIV. The only time this may be false is in newborn babies - if they have a mother who is HIV positive, they will have her antibodies in their blood stream for up to 18 months after birth. At 18 months old they should be tested for HIV, not before.

Get your own gravatar by visiting gravatar.com flowerman
#5. February 11th, 2008, at 2:21 PM.

As with any testing there is always room for error. HIV testing is 99.6% accurate. As for the antibodies there are medical conditions that will give a false positive, Lupus is one illness that will do this. And there is always human error, but the two items are very rare.

When you body develops antibodies, they are very specific to an illness.

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