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why is the elisa test performed before western blot and pcr
Does anyone know why the elisa is performed before the western blot, as I read somewhere that the western blots looks for all the hiv molecules and the elisa about 3 or 4. Is this correct? If so, why would the elisa be the best to do first then? Also, if the PCR test looks for the hiv virus itself, why is this test not prove someone has hiv before antibodies show up?
well you can word it how you want to but most medical practices follow the same procedure for hiv testing if you get a positive result by an rapid test then they do an elisa if positive then they follow up with a WB end of story if you go to a Drs office boohooing to him or her they may do a different route for you like
hiv rapid
hiv viral load
pcr test
then by this time you have way more money invested for nothing did you know hiv is a fragile virus to get ? anyway you keep researching in the end you will be better educated and you will find yourself passing it on to others that are not that educated about stds and hiv weird but it will happen goodluck to you for only you can find the answer that you are looking
hiv rapid
hiv viral load
pcr test
then by this time you have way more money invested for nothing did you know hiv is a fragile virus to get ? anyway you keep researching in the end you will be better educated and you will find yourself passing it on to others that are not that educated about stds and hiv weird but it will happen goodluck to you for only you can find the answer that you are looking
No, that does not answer my question at all.
You just re-state how things are and I know how things are since quite some time ago.
I wonder why can't a Western Blot result be trusted if it isn't a follow up to elisa tests.
If your WB comes back all bands positive, you have HIV.
If your WB comes back indeterminate, you should then test for antibodies at an appropiate time.
If WB comes back all bands negative, then you are negative.
If you don't trust your first result, you can always test a second time. With 2 identical results, the probability of error is 1 in 100000000%. The chance of 2 consecutive false positives would be extremely small.
That's what I would think but apparently things aren't as easy as that.
You just re-state how things are and I know how things are since quite some time ago.
I wonder why can't a Western Blot result be trusted if it isn't a follow up to elisa tests.
If your WB comes back all bands positive, you have HIV.
If your WB comes back indeterminate, you should then test for antibodies at an appropiate time.
If WB comes back all bands negative, then you are negative.
If you don't trust your first result, you can always test a second time. With 2 identical results, the probability of error is 1 in 100000000%. The chance of 2 consecutive false positives would be extremely small.
That's what I would think but apparently things aren't as easy as that.
I believe there are more false positives with the western blot,. is that true?
There are different HIV antibody tests. One test is the ELISA (enzyme-linked immunosorbent assay). If the ELISA test is positive, a second test called a Western blot is done to confirm the result. The Western blot takes longer to perform and is more expensive than the ELISA test, but it is more precise.
hope this answers your question
hope this answers your question
I never put in question Teak's information. In fact his info is as reliable as we will get.
what I question is the ability of the medical world to provide a test that looks for what it should be looking for: the HIV virus.
I wonder why don't we have a test that 100% ( or 99,8%, whatever) proves the abscence or presence of an external agent in your blood at ANY point in time, not 3 months, not 6 months and not 3 years later. If such test existed, I am sure people would pay whatever quantity to use it and get the situation over with.
everything point to the fact that a Western Blot IS that test I am asking for but for some reason, nobody should use it unless tested positive twice on an Elisa.
If I don't obey that rule and go straight to a WB test with no previous elisas and all bands come negative, why isn't that conclusive? Is the Western Blot so inaccurate that the virus could hide from it? If all bands came back positive, wouldn't that mean I have got the virus, reagrdless of previous elisas?
I'd really like to know, I suppose I am just ignorant in some of these matters. I guess there is a reason why things are like they are, I'd just like to understand.
what I question is the ability of the medical world to provide a test that looks for what it should be looking for: the HIV virus.
I wonder why don't we have a test that 100% ( or 99,8%, whatever) proves the abscence or presence of an external agent in your blood at ANY point in time, not 3 months, not 6 months and not 3 years later. If such test existed, I am sure people would pay whatever quantity to use it and get the situation over with.
everything point to the fact that a Western Blot IS that test I am asking for but for some reason, nobody should use it unless tested positive twice on an Elisa.
If I don't obey that rule and go straight to a WB test with no previous elisas and all bands come negative, why isn't that conclusive? Is the Western Blot so inaccurate that the virus could hide from it? If all bands came back positive, wouldn't that mean I have got the virus, reagrdless of previous elisas?
I'd really like to know, I suppose I am just ignorant in some of these matters. I guess there is a reason why things are like they are, I'd just like to understand.
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Teak's reply is precise yet comprehensive. PCR is not a primary diagnostic tool, and done for routine monitoring of viral load in infected people to track the efficacy of ARV medication. Western Blot is a confirmatory test, done only if ELISA reported positive.
High rate of false positive is probably the reason, why doctors do not recommend PCR for primary screening. Just imagine what will happen if you get a "false positive" PCR during a time when you are freaking, under tremendous stress and anxiety.
High rate of false positive is probably the reason, why doctors do not recommend PCR for primary screening. Just imagine what will happen if you get a "false positive" PCR during a time when you are freaking, under tremendous stress and anxiety.
to be honest I wonder the same thing.
If I want to know whether I have a virus, I should look for it, not for stuff that is produced thanks to it. If we had such a test that was 100% reliable in detecting the virus itself, this window period nonsense wouldn't exist and we would live in a decent world in regards to medical testing.
If I want to know whether I have a virus, I should look for it, not for stuff that is produced thanks to it. If we had such a test that was 100% reliable in detecting the virus itself, this window period nonsense wouldn't exist and we would live in a decent world in regards to medical testing.
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