HIV and AIDS Testing

The following laboratory tests are used to diagnose human immunodeficiency virus (HIV), which is the cause of acquired immunodeficiency syndrome (AIDS). Common tests used to determine the presence of antibodies to HIV include ELISA, Western blot, and Immunofluorescence assay (IFA).

• A single reactive ELISA test by itself cannot be used to diagnose HIV and should be repeated in duplicate with the same blood sample; if the result is repeatedly reactive, follow-up tests using Western blot or IFA should be performed.
• A positive Western blot or IFA results is considered confirmatory for HIV.
• A positive ELISA result that fails to be confirmed by Western blot or IFA should not be considered negative, and repeat testing should take place in 3 to 6 months.