Cytomegalovirus (CMV)

What is CMV?

CMV is a virus related to the herpes virus group of infections. Like herpes, it is inactive at times, but it is incurable and is a life-time infection. CMV is the most common congenital viral infection. It is also called congenital cytomegalovirus or cytomegalovirus inclusion disease.

What causes CMV?

CMV without symptoms is common in older babies and young children. It is found in saliva, urine, semen, and other body fluids. The virus is easily spread in households and in daycare centers. It can be transmitted to the fetus during pregnancy (called congenital CMV) and to the baby during delivery or in breast milk.

Why is CMV a concern?

Over half of women of childbearing age are infected with CMV prior to becoming pregnant. There appear to be few risks for complications of CMV for this group, and only a few babies have the infection at birth. These babies appear to have no significant illness or abnormalities.

According to the CDC, 1% to 4% of women have primary infections with CMV during pregnancy. When a woman's first infection occurs during pregnancy, there is a higher risk that after birth the baby may have CMV-related complications. About 1 in 150 babies with congenital CMV will have signs of the infection at birth. Of these, about half will have serious complications including hearing loss, visual impairment, developmental delay, or epilepsy.

Unlike congenital CMV, transmission at time of delivery or through breast milk does not typically cause illness in the baby.

What are the symptoms of CMV?

Most babies with congenital (present at birth) CMV do not have symptoms of the infection at birth. Symptoms may include:

  • Premature birth

  • Low birthweight

  • Liver enlargement and jaundice

  • Lung infection

  • Anemia

  • Hearing loss

The symptoms of CMV may look like other conditions or medical problems. Always consult your baby's doctor for a diagnosis.

How is CMV diagnosed?

Most infections with CMV in the mother are not diagnosed because the virus produces few symptoms. A mother who has had CMV infection before may have antibodies present in her blood stream. The virus can also be cultured from the throat or urine of the mother or baby.

Treatment for CMV

Research is underway to find antiviral drugs that might be effective against CMV. Other antiviral drugs and immunoglobulins may be of help in certain cases.

Prevention of CMV

Although an infected person may transmit the virus at any time, proper hand-washing with soap and water is effective in removing the virus from the hands. Research is also underway to develop a vaccine to provide immunity to CMV.

Related Resources

Congenital CMV Infection Trends and Statistics, CDC
Cytomegalovirus: Protect Your Baby, CDC
Cytomegalovirus Infection and Disease in Newborns, Infants, Children and Adolescents, UpToDate

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