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Cytomegalovirus (CMV)

What is CMV?
CMV is a common virus that infects most people at some point during their lives, but rarely causes obvious illness. It is a member of the herpes virus family. Other members of the herpes virus family cause chickenpox, infectious mononucleosis, fever blisters (herpes I) and genital herpes (herpes II). Like other herpes viruses, CMV infection can become dormant and may reactivate at some point.
Who gets CMV?
Anyone can become infected with CMV. Almost all people have been exposed to CMV by the time they reach adulthood.
How is CMV spread?
Although the virus is not highly communicable, it can be spread from person to person by direct contact. The virus is "shed" in the urine, saliva, semen and to a lesser extent in other body fluids. Transmission can also occur from an infected mother to her fetus or newborn, and by blood transfusion and organ transplants.
What are the symptoms of CMV infection?
Most children and adults who are infected with CMV do not develop symptoms. Those who develop symptoms may experience an illness resembling infectious mononucleosis and have fever, swollen glands and feel tired. People with a compromised immune system (such as AIDS patients or those receiving chemotherapy) may experience more serious illness involving fever, pneumonia and other symptoms.
Is CMV infection very serious in infants?
Approximately 10 out of every 100 babies born in the United States will have CMV infection. Of these, 90% will have no symptoms, while 10% may havesignificant illness involving nervous system damage or developmental disabilities.

How soon after infection do symptoms appear?
Although most people never develop symptoms after exposure, the incubation period appears to be between 3 to 12 weeks.
How long can an infected person carry CMV?

Once infected, CMV remains in the body indefinitely. Infected people may occasionally shed the virus in urine or saliva. Several studies have found that from 3 to 11 percent of normal adults and up to 50 percent of healthy children shed virus in either urine or saliva. The virus rapidly dies once outside the body.

How is CMV diagnosed?
There are special laboratory tests to culture the virus but such testing is difficult, expensive and not widely available. Specific blood tests can be helpful to the physician in making a diagnosis or determining if a person has been exposed but the results are sometimes inaccurate.
What is the treatment for CMV infection?
In most cases, there is no treatment. An effective vaccine has not yet been developed.
Should an infected child be excluded from school or day care?
There is no reason to exclude children who have CMV.
What precautions should pregnant women take when performing patient care or child care for persons with CMV infection?
Pregnant women should practice good hygiene and carefully wash their hands after caring for patients or children. This is particularly important when handling diapers or having contact with the child's urine or saliva. The risk of CMV infection in hospital workers is no greater than others in the community, and is probably low because of careful handwashing practices. In day care centers , where handwashing practices may not be as good, there may be a greater risk of infection. In both settings, good hygiene and careful handwashing are the most important control measures. Pregnant women working in child care facilities should minimize direct exposure to saliva and avoid kissing babies or young children on the mouth. Routine blood testing during pregnancy for CMV antibody is not generally recommended. Pregnant women should consult their physician on an individual basis regarding this issue.
What can be done to prevent the spread of CMV?
  • Good handwashing is the best preventive measure.
  • Plastic disposable gloves should be worn when handling linen or underclothes soiled with feces or urine.

Last updated October 2000