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HIV Test
Past an HIV-infection the immune system produces antibodies to fight against the infection. These antibodies can be detected by an “HIV-test”. The test consists out of two parts:
- Screening test: ELISA
- Confirmation test: Western blot, Immuno blot
One should keep in mind that it takes a couple of weeks after the infection for the production of antibodies. This means that during the first weeks after the infection, the HIV-test may show a negative result, although an infection is already present. This is called the “diagnostic gap”. Normally, an HIV-test will be positive around 3-6 weeks after the infection, but in rare cases it can also take 3-6 months.
Course of the HIV-test
First of all, the screening test "ELISA" will be applied. A negative result means that no antibodies against HIV were detected. An HIV-infection can be ruled out if the last risk contact was more than six months ago.
If the ELISA test shows a positive result, antibodies against HIV were detected. To exclude a possible wrong positive result, a confirmation test is applied, called Western blot. This test detects different antibodies against HIV-typical proteins. If this test also shows positive results, the suspicion that an HIV-infection is present is substantiated. To rule out a possible mix-up of the blood samples or a laboratory mistake, a second test with another blood sample should be carried out.
PCR
In rare cases, in which it might be
necessary to exclude an infection with HIV very early, a PCR-test is the best choice
for an early detection.