A set of blood tests used in the diagnosis of chronic infection with human immunodeficiency virus (HIV). The HIV ELISA is a screening test in the diagnosis of HIV infection. If this test is positive, it must be confirmed with a second test called the Western Blot which is a more specific test and will confirm if someone is truly HIV positive, as there are other conditions which may give a false positive ELISA screening test (eg. lupus, lyme disease, syphilis).