Aid in the detection of EBV infections (infectious mononucleosis). IgG antibodies to EBV nuclear antigen (EBNA) do not appear during the acute phase of infection, but rather appear 2-4 months after the initial clinical presentation and typically persist for life. The presence of EBNA IgG antibodies in healthy people usually indicates previous immunological exposure to EBV, but false positive results can occur. Furthermore, only about 5-10% of people infected with EBV develop EBNA IgG antibodies. Tracking EBV antibody patterns may aid in the diagnosis of EBV infection due to the complex relationship that exists between the EBV virus/host reaction and clinical manifestation. Individual levels of specific antibodies are not always indicative of disease status, but when tracked as an antibody response profile, they can be diagnostic.