Sexual Advice 101
Sexual Advice 101

HIV diagnostic tests

There are several diagnostic tests for HIV. Serological tests assay the level of antibodies against the HIV virus in the body. It may take up to 3 months after infection for the antibodies to reach a considerable, detectable level. More recent P24 assay kits can detect the HIV antigen and are faster and reliable. Common tests used to detect HIV include ELISA, western blot, urine HIV antibody tests, and rapid HIV antibody tests. ELISA involves a series of steps to detect the HIV antibody. The serum sample is added to wells containing the HIV antigen. When the antigen binds to the antibody, it causes a color change. The results of ELISA are confirmed by western blot. The HIV antigen is fractionated on a polyacrylamide gel. This is blotted onto a membrane and tested with the patient’s urine, serum. It antibodies to the virus are present; they will bind to the antigen and can be viewed using secondary antibodies with fluorescent markers. An oral mucosal transudate test uses oral fluid which may contain antibodies to the virus. A simple rapid blood test can be used to detect the HIV virus within an hour. If this test is positive, it needs to be confirmed by ELISA and western blot. Some other tests aim to assess the viral load and levels of CD4 cells in the body. These will give an idea about the progression of the disease.

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