Persistent Lack of Detectable HIV-1 Antibody in a Person With HIV Infection—Utah, 1995

HIV Infection Infection with — human Continued 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.”* Case Investigation In October 1995, the Utah Department of Health referred to CDC blood samples obtained from a man who had had onset of persistent fatigue and malaise during January 1995. During January–June 1995, he had sought medical care at several clinics. When he was admitted to a hospital in June because of respiratory illness and recent weight loss of 27 lbs, HIV-EIA was negative. In August, he was admitted with lung-biopsy–confirmed Pneumocystis carinii pneumonia (PCP) and a CD4+ count of 129 cells/µL; an HIV-EIA again was negative. The patient reported frequently donating