Important note: Information in this article was accurate in 2008. The state of the art may have changed since the publication date.
Sunday Times (Johannesburg) - July 6, 2008
Susan Keenan: New Start HIV testing organisation
Rapid tests use blood samples from a finger-prick and provide results in about 15 minutes. Elisa tests require a blood sample to be taken and sent to a laboratory, providing results in about a week.
Both Elisa and rapid tests are close to 100% accurate.
Depending on where you test, you may be given one test, with another test to be given to confirm a positive result, or you may be given two tests at the same time. Rapid tests are the preferred method because they allow clients to receive their results and pre- and post-test counselling at the same time.
Both Elisa and rapid tests look for antibodies in your blood, not for the virus. When infected with HIV, the body fights back by producing antibodies.
The body, however, can take up to a month to produce these antibodies so someone who was recently infected could still test negative. This is called the "window period".
This is why clients who test negative are encouraged to take another test about a month after they might have been exposed to the virus.
The problem is that someone who is recently infected with HIV has very high amounts of the virus in the body and it is during this first six weeks after infection that an HIV-positive person is most likely to pass on the virus to others.
You may be asking yourself, why test for antibodies instead of the virus itself?
There are tests that look for HIV antigens, proteins that make up the virus, but these tests are very expensive, do not provide rapid results and are rarely used.
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