Human immunodeficiency virus: Diagnostic approach.

First descriptions of acquired immunodeficiency syndrome appeared in 1981. Four years later the causative agent was cultured which lead to development and production of tests that helped healthcare providers to identify persons living with HIV. Currently, diagnosis of HIV is performed with fourth generation immunoassays (those that detect p24 antigen together with IgM and IgG antibodies to HIV-1 and -2) which if positive need to be followed by an assay that can differentiate between HIV-1 and HIV-2 viruses. The Western blot is no longer used to confirm HIV infections per CDC guidelines. In case there is a positive fourth generation assay but negative differentiation assay, nucleic acid testing for HIV-1 should be performed. This algorithm allows for detection of acute infections. Alternatively, the World Health Organization has algorithms that use rapid testing for diagnosis of HIV infections. This review will describe the evolution of tests and diagnostic algorithms from the 1980s to the current state. Special situations regarding diagnosis will also be discussed.