Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Rokitansky on 12/05/2004 23:18:38
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We had a scandal in Belgrade, few days ago. A kid who recived a blood transfusion had been infectid with AIDS. The blood had been provided by a national transfusion centar, and some people who had tested it are going to be trialed.
However, the other option has also been mentioned. Is it possible that tests on AIDS are not efficent enough to descover the virus if a blood donor was infected with it recently? Tests which has been used are the standard tests reccomended by the WHO. So, how long is a "blind" period in which a presence of virus can not be detected?
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i thought it was up to 6 months?
and then do an ELISA (enzyme linked immunoabsorbant assay) test?
then if that's positive, double check with a Western Blot test just to make sure.
Also the tests may give false negatives and false positives? - iam not too sure but that maybe having both tests eliminates this.
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It is pretty stupid drawing out some blood, putting it into freezer,
testing people who gave blood after 6 months, and then using that
blood for transfusion.
I belive there are some faster tests.
Anyway, I think there was a human error in national transfusion center.
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When I've had surgery, I added a no blood clause to my permission form. I think it encourages them to be careful. If I was worried about needing blood, I would bank my own first. Admittedly there's not much you can do if you are brought in unconscious, or in various other situations.
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Yes, it is always better not to recieve transfusion unless it is absolutly neccessary. However, in my country there is no such thing as a permission form.[:(]
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I thought the ELISA test was more famous for false positives than false negatives. But then again, no test if foolproof. There's always risk with a blood transfusion.
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When I've had surgery, I added a no blood clause to my permission form. I think it encourages them to be careful. If I was worried about needing blood, I would bank my own first. Admittedly there's not much you can do if you are brought in unconscious, or in various other situations.
We can ask for our own blood for something like this?
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Tests which has been used are the standard tests reccomended by the WHO. So, how long is a "blind" period in which a presence of virus can not be detected?
HIV is diagnosed in two ways:
- serologically, which means looking for the presence in the blood of antibodies made against the virus, and antigens made by the virus
- via molecular biology, which involves using the polymerase chain reaction to look for the genetic sequence of the virus, indicating that it is present in the body.
All tests are subject to what is called a "window period"; this is the time after exposure when a patient is infected but before a test becomes positive. This occurs because, initially following infection there may not be sufficient virus antigen, genetic information or antibody present to register on a test.
In the case of serological tests for HIV, these are usually reliably positive 3 months following infection; prior to this time the results may be unreliable and prone to false negatives.
Molecular tests tend to be more sensitive (though not exclusively), and have an earlier pickup-time. For HIV this can be by 6 weeks post-infection.
It is owing to this "window period" that patients are often repeat tested with the tests a reasonable duration apart to ensure that the result is accurate.