What is the role of cytomegalovirus (CMV) in the etiology of viral pneumonia?

Updated: Mar 24, 2021
  • Author: Zab Mosenifar, MD, FACP, FCCP; Chief Editor: John J Oppenheimer, MD  more...
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Cytomegalovirus (CMV) is a herpesvirus that is a common cause of infections, usually asymptomatic, in the general population. In hosts who are immunocompetent, acute CMV infection causes a mononucleosis-like syndrome. Transmission is primarily through body fluid contact. The virus has been found in the cervix and in human milk, semen, and blood products. The prevalence of antibodies to CMV in adults ranges from 40-100%, with higher rates in lower socioeconomic areas.

Reactivation of latent infection is almost universal in transplant recipients and individuals infected with the human immunodeficiency virus. CMV pneumonia may occur and is often fatal in immunocompromised individuals, primarily hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients. The severity of pneumonia is related to the intensity of immunosuppression. Additionally, CMV infection is itself immunosuppressive, causing further immunocompromise in these patients.

In cancer patients receiving allogeneic bone marrow transplants, CMV pneumonia has a prevalence of 15% and a mortality rate of 85%, making it the most common cause of death in this population. Acute graft-versus-host disease is the major risk factor for CMV pneumonia in these patients.

Interestingly, although CMV is a well-recognized pathogen in patients with AIDS (manifesting as retinitis, colitis, encephalitis, polyradiculitis, and/or cholangiopathy), clinically relevant pneumonia is very uncommon in this group, even if CMV is cultured from alveolar fluid and/or seen on lung histology.

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