CYTOMEGALOVIRUS (CMV)

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What is Cytomegalovirus?

Cytomegalovirus (CMV) is a common virus that infects most people worldwide at some time during their lives but rarely causes obvious illness. It is a member of the herpes family and like other herpes viruses CMV infection can become dormant and may reactivate at some point.

How is CMV spread?

Although the virus is not highly communicable, it can be spread from person to person by direct contact. Any person with a CMV infection, even without symptoms, can pass it to others. In an infected person, the virus is present in many bodily fluids, such as urine, blood, saliva, semen, cervical secretions, and breast milk. Transmission can also occur from an infected mother to her fetus or newborn and by blood transfusions and organ transplants. CMV can spread in households and childcare centres through hand-to-mouth contact with infected bodily fluids. 

What are the symptoms?

Most children and adults who are infected with CMV do not develop symptoms. Those who do develop symptoms may experience an illness resembling infectious mononucleosis. Symptoms include high fever, chills, swollen glands, severe tiredness, a generally ill feeling, headache, and an enlarged spleen. 

Most infected newborns have no symptoms at birth, but in some cases symptoms will appear over the next several years. These can include developmental problems and vision or hearing problems. In rare cases, a newborn can have a life-threatening infection at birth. Infants and children who get CMV infection after birth have few, if any, symptoms or complications. When symptoms do occur they include lung problems, poor weight gain, swollen glands, rash, liver problems, and blood problems.

When do symptoms appear?

Most exposed people never develop symptoms. In those who do, the time between exposure and symptoms is about 3 to 12 weeks. CMV remains in the body throughout a lifetime. The duration of the illness varies depending on the type of infection and the age and health of the infected person. Serious CMV infections that were acquired at birth can cause developmental problems that can affect a child throughout life. CMV infections in immuno-suppressed individuals can be life threatening, whereas infections in young adults might cause symptoms for only 2 to 3 weeks.

Who is at risk for CMV?

Almost all people have been exposed to CMV by the time they are adults, but the virus usually does not make otherwise healthy people sick. However, the following people are at an increased risk for active infection and serious complications:

• Babies born to women who have a first-time CMV infection during pregnancy; risks to the fetus are greatest during the first half of gestation
• Pregnant women who work with infants and children
• Persons with weakened immune systems, including cancer patients on chemotherapy, organ transplant recipients and persons with HIV infection

What precautions should pregnant women take?

Pregnant women should practice good hygiene and carefully wash their hands after caring for children. This is particularly important when handling diapers or having contact with the child’s urine or saliva. Good hygiene and careful hand washing are the most important control measures. Pregnant women working in childcare facilities should minimize direct exposure to saliva and avoid kissing babies or young children on the mouth or cheek. Routine blood testing during pregnancy for CMV is not generally done. Pregnant women should consult with their physician on an individual basis regarding this issue.

For more information please contact your physician or Public Health at 519-376-9420.

Canadian Pediatric Society

Centers for Disease Control (CDC), 2006

Red Book, 2003