Persistent lack of detectable HIV-1 antibody in a person with HIV infection--Utah, 1995.

Infection with human immunodeficiency virus (HIV) is diagnosed routinely by the enzyme immunoassay (EIA) for HIV-1 antibody; a nonreactive blood sample is designated as negative without further testing. However, one limitation of this screening algorithm is that a blood sample may be obtained from a patient with recent HIV infection before detectable HIV antibody is present ("window period"). This report describes a patient with confirmed HIV infection in whom EIAs for HIV antibody (HIV-EIAs) were persistently negative beyond the expected "window period."