Infection with the cytomegalovirus (CMV or human herpes virus 5) is generally asymptomatic in immunocompetent hosts, but can cause mild mononucleosis-like symptoms. Like all Herpesviridae infections, CMV persists for the lifetime of its host; reactivation may therefore occur. Immunocompromised individuals (e.g., AIDS, post-transplantation) are especially at risk of illness following reactivation or initial infection, which can include severe manifestations such as CMV retinitis (risk of blindness) or life-threatening CMV pneumonia. Treatment with ganciclovir or valganciclovir should therefore begin promptly on clinical suspicion of a CMV infection.
is discussed in another article.
- Prevalence of CMV infection in the general population: 40–100%
- Seroprevalence increases with age with more than 90% in individuals > 80 years
Epidemiological data refers to the US, unless otherwise specified.
- Pathogen: cytomegalovirus (CMV, human herpes virus 5, HHV-5)
- Blood transfusions
- Sexual transmission
- Transplacentaly (highest risk during the first trimester of pregnancy)
- Perinatal transmission (e.g., contact with contaminated blood/vaginal secretions during delivery or breastfeeding)
- Body fluids (e.g., respiratory droplets, saliva, urine, genital secretions)
- Transplant-transmitted infection (e.g., bone marrow, lungs, kidneys) 
- CMV binds to →; activation of → induction of cellular morphological changes → activation of signal transduction pathways; such as FAK (focal adhesion kinase) and apoptotic pathways → cell damage → clinical manifestations depending on the organ/tissue affected. 
- After primary infection resolves, CMV remains latent in mononuclear cells (e.g., myeloid cells). Reactivation can occur if the patient becomes immunocompromised. 
For information about, see the corresponding article.
In immunocompetent patients
- > 90%: asymptomatic course 
- < 10%: CMV mononucleosis 
In immunocompromised patients
One or more of the following clinical manifestations may be present:
- CMV mononucleosis
CMV pneumonia: interstitial pneumonitis ;.
- Etiology: immunocompromised patients (e.g., following bone marrow transplant or in HIV/AIDS patients with CD4 ≤ 50 cells/mm3)
- Clinical findings: fever, nonproductive cough, dyspnea
- Differential diagnoses: and other viral respiratory infections 
- CMV retinitis: floaters, photopsia, visual field defects 
- CMV esophagitis and/or CMV colitis
- CMV encephalitis: impaired cognitive function, neurological deficits 
- CBC: relative lymphocytosis with > 10% atypical lymphocytes  and sometimes pancytopenia
- Blood smear: large atypical lymphocytes with intranuclear inclusion bodies that have an owl-eye appearance
- Monospot (heterophile antibody) test: negative 
- Serological tests 
- Direct evidence of viremia: especially useful in immunosuppressed patients 
- Fundoscopy: retinal hemorrhages and cotton-wool spots (“pizza-pie” appearance) in CMV retinitis
Serological tests may be unreliable in immunosuppressed patients!
- In immunocompetent patients: No specific treatment is needed. 
- In immunosuppressed patients 
|CMV retinitis|| |
|CMV colitis|| |
|CMV pneumonia|| |
|CMV encephalitis|| |