In people with normal immune systems, CMV infection is often asymptomatic or manifested as infectious mononucleosis-like syndrome (fever, lymphadenopathy, and atypical lymphocytosis).
In immunocompromised people (patients with AIDS and transplant recipients), disease manifests with fever, bone marrow suppression, and tissue-invasive disease such as pneumonia, hepatitis, colitis, nephritis, and retinitis.
In an immunologically-naive fetus, CMV infection may lead to cytomegalic inclusion disease, characterised by severe neurological abnormalities, mental retardation, and hearing defects.
Tests for diagnosis include: viral culture, serology, pp65 antigenaemia test, histopathology, and nucleic acid amplification and detection systems, most commonly quantitative PCR-based assays.
In immunocompetent people, infection is usually self-limiting; therefore, treatment is usually not indicated.
In patients with compromised immune function, the treatment of choice is intravenous ganciclovir or oral valganciclovir. Intra-ocular administration of ganciclovir, and less commonly fomivirsen, is also used in CMV retinitis. Intravenous foscarnet and cidofovir are less preferred agents.
Cytomegalovirus (CMV) is a ubiquitous beta-herpes virus that infects the majority of humans. Primary infection in individuals with normal immune function is usually asymptomatic. After primary infection, CMV establishes a state of lifelong latency in various host cells, with periodic sub-clinical re-activations that are controlled by a functioning immune system. When re-activation (or primary infection) occurs in patients with severely compromised immune function (transplant patients, or AIDS patients with CD4 count <50 cells/microlitre), uncontrolled CMV replication often ensues, which leads to the clinical manifestations characterised by fever, bone marrow suppression, and tissue-invasive disease.  
Multi Organ Transplant Program
Toronto General Hospital
AH has done consultancy work for Astellas, Chimerix, and Roche.
Dr Atul Humar would like to gratefully acknowledge Dr Raymund R. Razonable, a previous contributor to this monograph. RRR is an author of a number of references cited in this monograph.
Department of Family Medicine
University of Maryland School of Medicine
GHT declares that he has no competing interests.
HIV and Sexual Health
Chelsea and Westminster Hospital
SB has been funded by GlaxoSmithKline and Gilead for speaking at scientific meetings.
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