Many people undergo HIV testing to see if they have this disease. When the test comes back positive, another test is performed immediately to assure that a false positive did not occur. If the second more specific test comes back positive then the person is most likely infected. If it comes back negative, then, most likely, the first test was a false positive.
Facts
Many factors may cause false positive HIV tests (see References). The general screening test for HIV uses a protein-based solution that seeks out the target. However, many times other processes going on in the body may release antibodies that fool the protein into thinking it found its target. For example, if one has certain conditions such as tuberculosis, malaria or rheumatoid arthritis or if one is taking certain antibodies such as a flu vaccination, then any of these factors may cause a false positive. The test solution changes to the color for positive because of the antibody present in the blood from the condition of the person.
Interpretation
Another cause of a false positive is the guidelines of the test itself. Since there is no standardization in the testing procedure, different drug companies may interpret the results differently. In addition, different parts of the world interpret the tests differently (see References). These different interpretations can yield a positive result from one source and a negative from another--even if they were both looking at the same sample.
Time Frame
If a person has the HIV virus, then it is imperative to seek treatment as soon as one knows of this condition. However, do not seek treatment for HIV if you have only had the general screening test, because this could have a false positive. Take the second specific test immediately after the first positive to confirm presence of the HIV or to determine if the first test is a false positive.
Types
There are two common types of testing for HIV. The general first-screening test, called Enzyme-Linked Immunosorbent Assay test, or ELISA, targets a specific subject and yields a positive if it finds the target. Western Blot tests are specific tests geared to confirming the ELISA positive test. This test detects viral components specific to HIV and sends back a positive if this detected. It is possible to get false positives with both of these tests.
Warning
When a person receives a positive result for HIV, he should immediately seek a second test called the Western Blot test. This is a specific test for the HIV virus, and if it is also positive then the person is most likely infected. The tests may be wrong even if you have two positives, so report to a health care provider for proper treatment and further testing if you do receive a positive HIV test.
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