- AIDS Serology
- AIDS Screen
- Human Immunodeficiency Virus (HIV) Antibody Test
- Western Blot Test, p24 Antigen Capture Assay
HIV Serology measures the amount of antibodies against HIV that are present in the blood. Two tests need to be positive for HIV to be diagnosed; ELISA tests for antibodies in the blood, is inexpensive and most commonly used. If ELISA is positive for the presence of HIV antibodies, this will be confirmed by the Western blot test, which is more specific to HIV infection and the results are extremely accurate. Both of these tests will be repeated after six months to confirm both positive and negative test results. HIV serology cannot detect infection before antibodies are formed against the virus, which can take up to six months to develop following infection with the virus.
There are other blood tests that are able to detect and measure the actual presence of the virus (antigens) in an infected person's blood. A p24 Antigen Capture Assay can detect viral levels very early, even before antibodies against HIV are present in the blood. This test is also used to test newborns, and is used to diagnose HIV infection prior to its conversion (seroconversion) to AIDS, and to follow disease progression when AIDS is present.
Blood tests that may also be used are Oral Mucosal Transudate (OMT), which measures levels of HIV antibodies in saliva using the same methods as ELISA; urine testing which measures HIV antibodies in the urine using the same methods as ELISA; Home HIV Testing Kits, where a small amount of blood collected and placed on a special test paper, then sent to a lab for testing. Counseling is available both before and after testing with a home kit.
Both false positives and false negatives can occur with any of the above methods.
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