Human herpes viruses are highly successful intracellular parasites. With the exception of varicella-zoster virus (VZV), they cause asymptomatic or mildly symptomatic primary infection, establish latent infection, and persist lifelong. During the host's lifetime, they periodically reactivate and infect other susceptible individuals. As long as the host's immune system is not compromised, the balance between virus and host is maintained. However, immunosuppression induced by disease or therapy can alter the balance between virus and host, resulting in systemic virus infection and concomitant disease.
The human Herpesviridae includes three subfamilies (see Table 3.1). Transmission by transfusion does not appear to occur with herpes simplex virus (HSV) or VZV. Cytomegalovirus (CMV) is by far the most important herpes virus in transfusion medicine, and its relative significance increased greatly in the last two decades, due to increases in bone marrow transplantation, solid-organ transplantation and more aggressive chemotherapy for malignant disease. This chapter reviews the role of CMV and Epstein-Barr Virus (EBV) in transfusion medicine. Human herpes viruses 6, 7, and 8 (HHV-6, HHV-7, and HHV-8) are reviewed briefly but are covered in detail in the chapter on newly identified agents (Please refer to Chapter 28).
Transfusion-acquired CMV infection has been the subject of numerous reviews (Blajchman et al., 2001; Gunter and Luban, 1996; Hillyer et al., 1994; Pamphilon et al., 1999b; Preiksaitis, 2000; Tegtmeier, 1989; 2001; Wong and Luban, 2002).