Acquired Immunodeficiency Syndrome, or AIDS, is the final stage of a serious and potentially fatal infection of the immune system caused by the human immunodeficiency virus or HIV. There is no cure for HIV infection and AIDS. However, with accurate and early diagnosis, the disease can be managed using anti-HIV drugs and life span of the infected individual may be prolonged considerably.
Purpose of HIV Testing
The HIV test is done to determine if the individual is infected with HIV virus or not and is recommended to individuals who have injected drugs or steroids or shared equipment such as needles with others or have had unprotected sex with multiple or anonymous partners. HIV testing may also be prescribed to homosexuals, pregnant women and to individuals with other sexually transmitted diseases, such as syphilis and chlamydia.
Patient Sample
Patient's blood is the most common sample used to diagnose HIV infection. The Centers for Disease Control (CDC) recommends that the patient should wait for at least six to eight weeks after the suspected exposure to the virus for accurate diagnosis. This is because most HIV tests detect the presence of antibodies in the blood and it can take the immune system about two to eight weeks to develop the antibodies. This period is known as window period. However, if the test detects the presence of viral genetic materials or viral proteins, the tests can be performed nine to 11 days after exposure.
Antibody Testing
The antibody tests look for the presence of anti-HIV antibodies in the patient's blood. This method of testing involves two steps - an initial screening test such as rapid test or Enzyme Immunosorbent Assay (ELISA) followed by a confirmatory test such as western blot or immunoflouroscence assay. The initial screening tests are highly sensitive and can detect the presence of small amounts of antibodies but these tests are less specific and hence, should always be validated by confirmatory tests.
According to San Francisco AIDS Foundation, the results for the rapid test are available within 20 minutes while results for ELISA, western blot and other tests are take 3.5 to four hours. However, many test centers send the patient's sample to other laboratories and hence, it may take one to two weeks for the results to be available.
Viral Component Testing
As previously stated, the presence of viral components can be tested nine to 11 days after the exposure and hence, provide results earlier. There are two common types of tests in this category. The RNA Test, or HIV Nucleic Acid Amplification Testing (HIV NAAT) test detects the presence of viral genetic material (RNA) in the test sample while the p24 antigen test detects the presence of HIV protein known as p24 protein. The New York Times reports in an April 2009 article that although antibody testing is still widely used to HIV diagnosis, the health departments in San Francisco and North Carolina have successfully used the RNA test to accurately detect dozens of cases that were not detected by antibody tests.
Home HIV Tests
Only one home based test for HIV has been approved by the FDA. The kit contains materials and the instructions for collecting a blood sample. The sample is then sent to the specified laboratory where the standard antibody tests are done. As per AIDS.gov website this test is as reliable as any other test when all the instructions are followed properly.
