How does one test for the HIV virus?
Once a person gets HIV infection, the antibody against HIV appears in the blood only after 3-6 months after the virus has entered the body. The routine test (ELISA) detects the antibody to HIV virus. A positive test means that the person is infected with HIV. A negative test result means that no antibodies were detected at the time of the test. This would mean that either the person is uninfected or is in the window period (The period where the HIV virus is present in the body but antibodies have not developed). If there is a strong suspicion of exposure to the virus, a repeat test may be required after few weeks to overcome the window period. Confirmation of HIV infection can be done by other tests such as Western-Blot test. To detect the virus itself, tests such as PCR tests and viral culture are available. These tests are especially useful to diagnose HIV infection in infants as they may have maternal antibodies to HIV virus in their blood, which may give a false positive ELISA test
