Fatal adult case of severe lymphocytopenia associated with reactivation of human herpesvirus 6

It has been suggested that immunosuppression associated with human herpesvirus 6 (HHV-6) infection is a result of functional impairment or direct destruction of immunological cells. The ability of the virus to infect and destroy lymphocytes may cause progressive immunodeficiency in an infant with primary HHV-6 infection. An adult patient is described who had a fatal cytomegalovirus (CMV) infection due to severe and prolonged lymphocyte depletion associated with HHV-6 reactivation. The HHV-6 antibody titers were increased significantly after reactivation, and the virus was isolated from his peripheral blood mononuclear cells. The quantity of both HHV-6 and CMV DNA was determined by using real-time PCR in plasma samples collected serially. HHV-6 DNAemia persisted for 1 month, which started just 1 week after the onset of lymphocytopenia. In contrast to HHV-6, CMV DNAemia was detected in the terminal phase of the illness. Thus, HHV-6 reactivation may have been the cause of the severe lymphocyte depletion and fatal CMV infection.