HIV Tests (Cont.)

 
HIV Blood Test for Confirmation
If the sample repeatedly shows the same result or either duplicate test is reactive, the results are "confirmed" using a second HIV blood test, such as the Western blot. This more specific (and more expensive) HIV blood test can tell the difference between HIV antibodies and other antibodies that can react to the EIA and cause false-positive results. False-positive EIA results are uncommon, but can occur. A person is considered infected following a repeatedly reactive result from the EIA, confirmed by the Western blot test.
 
New HIV Blood Tests
In addition to the EIA or ELISA and Western blot, other HIV blood tests now available include:
 
  • Radioimmunoprecipitation assay (RIPA): A confirmatory HIV blood test that may be used when antibody levels are very low or difficult to detect, or when Western blot test results are uncertain. An expensive test, the RIPA requires time and expertise to perform.
     
  • Dot-blot immunobinding assay: A rapid-screening HIV blood test that is cost-effective and that may become an alternative to standard EIA and Western blot testing.
     
  • Immunoflourescence assay: A less commonly used confirmatory HIV blood test used on reactive ELISA samples or when Western blot test results are uncertain.
     
  • Nucleic acid testing: For example, viral RNA or proviral DNA amplification method. A less available HIV blood test that can be used to resolve an initial indeterminate Western blot result in certain situations.
     
  • Polymerase chain reaction (PCR): A specialized HIV blood test that looks for HIV genetic information. Although expensive and labor-intensive, the test can detect the virus even in someone only recently infected.
     
(HIV Tests Continued: Page 3)

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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD