Monday, August 15, 2011

Human immunodeficiency virus (HIV) Laboratory diagnosis

• Serology
Serologic tests for antibodies to HIV are the main laboratory diagnosis of HIV infection. EIA containing most HIV antigens has a sensitivity of more than 99.5% for the detection of antibodies to HIV. Although the EIA is extremely sensitive, false positives are common therefore; a positive EIA test must be followed by a confirmatory test. A Western blot assay is the most reliable confirmatory serologic test for the diagnosis of HIV infection (Talaro, 2005).
• Molecular detection
Direct virus assays (e.g. PCR for HIV RNA) are sensitive methods for detection of HIV infection. However, problems with laboratory contamination, false-positive results, and increased costs, limit their routine use. While PCR for HIV RNA is approved for use in established HIV infection, its reliability in detecting very early infection has not been determined. At present, the false-positive and false-negative rates of PCR are too high to warrant a broader role for it in routine postexposure management (Beltrami et al., 2000).

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