Cytomegalovirus infections after allogeneic bone marrow transplantation

Cytomegalovirus (CMV) infection occurs in approximately 50% of all recipients of allogeneic bone marrow transplants and is seen more frequently in CMV-seropositive patients than in CMV-seronegative patients. Sources of infection include reactivation of latent endogenous virus, blood products from CMV-seropositive blood donors, and the use of marrow from a CMV-seropositive donor for a CMV-seronegative recipient. The most common and severe clinical syndrome associated with CMV infection in allogeneic transplant recipients is interstitial pneumonia, which occurs in approximately 15% of patients. Risk factors for CMV pneumonia include old age, conditioning with total-body irradiation, and severe graft-vs.-host disease. The rapid diagnosis of CMV pneumonia has been facilitated by immunochemical staining of bronchoalveolar lavage fluid or by centrifugation of cell cultures with CMV monoclonal antibodies. The treatment of CMV pneumonia remains problematic, but therapy with a combination of intravenous immune globulin (IVIG) plus ganciclovir has resulted in survival rates substantially better than those achieved in previous trials of antiviral therapy. In CMV-seronegative patients, CMV infection and pneumonia can be prevented or modified by the use of CMV-seronegative blood products and IVIG. IVIG may also have the additional benefits of preventing other infectious complications and graft-vs.-host disease in patients receiving CMV-seronegative blood products. For CMV-seropositive patients, effective prophylaxis for CMV reactivation and pneumonia has not yet been established, but a clinical trial of prophylactic ganciclovir is now under way.