Cytomegalovirus is a double-stranded DNA virus that is a member of the herpesvirus family. Most people are CMV positive, with latency established in hematopoietic cells after primary infection. Immunosuppressed patients and kidney transplant recipients are particularly vulnerable. Seropositive recipients of a seropositive transplant are treated with prophylaxis, and seronegative individuals may have primary infection. Reactivation of the latent virus in the kidney transplant patient can result in a severe systemic illness, with fever, multiple organ dysfunction with associated leukopenia, and CMV in the blood.