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CMV infection

What is Cytomegalovirus?

Cytomegalovirus (CMV) is a member of the Herpes virus family. It commonly infects humans - with estimates ranging from 40% upwards.

Infection may occur at different stages in life:

  • Congenital (existing from birth, due to from transmission across the placenta)
  • Neonatal (from the birth canal cervix and via breast milk)
  • Infant or pre-school child (in daycare nurseries)
  • Adolescence
  • Infant-to-parent

The manifestations of acquired CMV infections vary with the age and health of the host's immune system. Symptomless infections are most common, particularly in children. In adults, a glandular fever like syndrome - with prolonged fever and mild hepatitis - has been described.

Most at risk from this virus are those people with malignancies, who are HIV positive, or who are receiving immunosuppressive therapy for organ transplantation. Some children who are asymptomatic at birth are found in childhood to have a hearing loss or learning disability. CMV persists in latent form after a primary infection, and reactivation may occur years later, particularly under conditions of immunosuppression.

Cytomegalovirus transmission

The main method of infection between people is via saliva or urine, though all body fluids have the potential to carry the virus. This includes oral, nasal and throat secretions, cervical and vaginal secretions, breast milk, semen, tears and faeces.

Although the virus is not highly contagious, a spread of CMV in households and day care centres is well documented. In day care centres it may reach 70% in 1-2 year olds (figures from USA).

The incubation period for person-to-person spread in households is unknown, but the infection usually shows between 3 and 12 weeks after blood transfusion, and between 6 weeks and 4 months after tissue transplantation.

Pregnant women caring for small children should be aware of the risk, and maintain handwashing hygiene at all times. Infection of the foetus results in a neonatal syndrome with possibly serious consequences, including jaundice, liver damage, blindness and birth defects.

When a pregnant woman contracts the infection it is considered to be more harmful to the developing foetus during the first 12 weeks of development when the major organs and limbs are being formed.

Cytomegalovirus treatment

A range of antiviral agents may be used to treat cytomegalovirus infections. The precise types or combinations used will differ from one case to another, depending on how the virus is manifesting itself, the severity of the case, the patient's history etc. Many new treatments are being investigated.

Cytomegalovirus prognosis

As is the case with all herpes viruses, the infection lingers in the system long after the discernable symptoms of the condition pass. The virus can be detected in the blood via the presence of the antibodies fighting it. Sometimes a person develops a mild bout of the infection which is totally asymptomatic. They only discover they have the virus when, years later they have a blood test (usually for some totally unrelated reason), or suffer a relapse.

Once infected, a person can then experience relapses for the rest of their life. Flare-ups tend to occur when a person's immune system is compromised either from another infection, or through bad eating habits, exhaustion etc.

Last updated 3 April 2018