What is Cytomegalovirus CMV infection

Cytomegalovirus or CMV is a virus that is common in the environment and the majority of adults have antibodies (an indication of previous infection) to it in their blood by age 40. However, CMV produces no symptoms usually, though it can present with symptoms similar to glandular fever.

However, serious systemic CMV infections can occur in people with impaired immunity (immunocompromised host), such as those with AIDS, organ transplant and bone marrow transplant recipients, and people receiving chemotherapy or other immunosuppressive treatments.

In addition, CMV infection can affect the developing fetus during pregnancy causing similar teratogenic effects to rubella.

Infections with CMV can include: CMV pneumonia, CMV gastroenteritis, CMV retinitis, and CMV encephalitis (brain infection).

Statistics on Cytomegalovirus CMV infection

Most humans are exposed to this virus in their lifetime, but typically only individuals with weakened immune systems become ill from CMV infection. Congenital CMV infection affects approximately 0.4% of UK pregnancies, though not all suffer adverse effects.

Risk Factors for Cytomegalovirus CMV infection

CMV is most commonly an opportunistic infection in the immunocompromised.

For Example:

  • recipients of bone marrow transplant transplants.
  • solid-organ transplants.
  • in patients with AIDS
  • CMV infection can be a primary infection, as well as a re-activation. Congenital CMV infection can occur in both cases.

Progression of Cytomegalovirus CMV infection

Postnatal infection: The infection is usually symptomless. It persists for life, usually as a latent infection. Infection may be spread by kissing, sexual intercourse or blood transfusion, and transplacentally to the fetus.

Immunocompromised: Disseminated fatal infection with widespread visceral involvement may occur in the immunocompromised and may cause encephalitis, retinitis, pneumonitis and diffuse involvement of the gastrointestinal tract.

Congenital: The majority of affected children show no adverse effects, though it can lead to neurological problems (microcephally), liver and blood abnormalities.

How is Cytomegalovirus CMV infection Diagnosed?

Laboratory abnormalities include:

  • Liver function test abnormalities.
  • FBC: increased white cell count (with increased lymphocytes).

Prognosis of Cytomegalovirus CMV infection

CMV infection in the immunocompromised host can be life-threatening, and the severity of the disease is dependent on the strength of the individual’s immune system. Individuals who have undergone bone marrow transplant have been shown to have the highest mortality risk.

About 7% of affected infants develop severe generalised disease, in which the brain is almost always involved. Otherwise milder effects are more common.

How is Cytomegalovirus CMV infection Treated?

  • In healthy individuals, no specific treatment is required.
  • In immunocompromised patients, ganciclovir (5mg/kg daily for 14-21 days) reduces retinitis and gastrointestinal damage and can eliminate CMV from blood, urine and respiratory secretions.
  • Foscarnet and cidofovir can be used where there is drug resistance to ganciclovir in some AIDS patients, however, as they are nephrotoxic, their use should be restricted to severe cases of the disease.

Cytomegalovirus CMV infection References

  1. Kumar P, Clark M. Clinical Medicine. Fourth Ed. WB Saunders, 2002.
  2. MEDLINE Plus.
  3. Timbury MC., Notes on Medical Virology, 11th Ed. Churchill Livingstone 1998.