• Clinical science

Cytomegalovirus infection

Abstract

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.

Congenital CMV infection is discussed in another learning card.

Epidemiology

  • 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.

Etiology

References:[1][2][3]

Pathophysiology

  • CMV binds to integrins → activation of integrins → induction of cellular morphological changes → activation of transduction pathways such as FAK (focal adhesion kinase) and apoptotic pathways → cell damage → clinical manifestations depending on the organ/tissue affected.

Clinical features

CMV infection is usually asymptomatic. Severe manifestations occur in immunocompromised states (e.g., following organ transplantation, AIDS).

In immunocompetent patients

In immunocompromised patients

Among HIV-positive patients, manifestations of CMV disease usually occur when the CD4 count is ≤ 50!

One or more of the following clinical manifestations may be present:

References:[2][4][1][5][6][7][8][9]

Diagnostics

  • CBC: relative lymphocytosis with > 10% atypical lymphocytesand 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
    • PCR to detect CMV DNA in bodily fluids
    • Indirect immunofluorescence assay: pp-65 CMV antigens
  • Fundoscopy: retinal hemorrhages and cotton-wool spots (“pizza-pie” appearance)

Serological tests may be unreliable in immunosuppressed patients!

References:[2][1][4][5]

Treatment

CMV infection Regimen Duration
CMV retinitis
  • At least 3–6 months
CMV colitis
  • 21–42 days
CMV esophagitis
CMV pneumonia
  • Until CD4 count > 100 cells/mm3 and symptoms improve
CMV encephalitis

References:[2][1][8]