Clinical Overview

Diagnosing, treating, and monitoring children with congenital CMV can help improve their health outcomes.

Characteristics of the Virus

CMV is a member of the herpesvirus family, which includes herpes simplex virus types 1 and 2, varicella-zoster virus, and Epstein-Barr virus. These viruses share a characteristic ability to establish lifelong latency. After initial infection, which may cause few symptoms, CMV becomes latent, residing in cells without causing detectable damage or illness.

For most healthy people who acquire cytomegalovirus (CMV) after birth, there are few symptoms and no long-term health consequences. Some people who acquire CMV infection may experience a mononucleosis-like condition with prolonged fever and hepatitis. Once a person becomes infected, the virus remains latent and may reactivate occasionally. Disease from reactivation of CMV infection rarely occurs unless the person’s immune system is suppressed due to therapeutic drugs or disease.

For most people, CMV infection is not a serious health problem. However, certain groups are at high risk for serious complications from CMV infection:

  1. Infants infected in utero (congenital CMV infection)
  2. Very low birth weight and premature infants
  3. People with compromised immune systems, such as from organ and bone marrow transplants, and people infected with human immunodeficiency virus (HIV)

Transmission

CMV infects people of all ages. In the United States; nearly one in three children are already infected with CMV by age five. By the age of 40, over half of adults have been infected with CMV, most with no signs or symptoms.

CMV is transmitted by direct contact with infectious body fluids, such as urine, saliva, blood, tears, semen, and breast milk. CMV can be transmitted sexually and through transplanted organs and blood transfusions. 

CMV can be transmitted to infants through contact with the mother’s genital secretions during delivery or through breast milk. Healthy infants and children who acquire CMV after birth generally have few, if any, symptoms or complications from the infection. Although the virus is not highly contagious, it has been shown to spread among household members and young children in daycare centers.

Treatment and Management

No treatment is currently indicated for CMV infection in healthy people. Antiviral treatment is used for people with compromised immune systems who have either sight-related or life-threatening illnesses due to CMV infection. For congenital CMV treatment options, see Congenital CMV Infection.

Prevention

CMV is common in children and can be found in especially high amounts in young children’s saliva and urine. Avoiding contact with saliva and urine from young children might reduce the risk of CMV infection. Healthcare providers should follow standard precautions. Vaccines are still in the research and development stage.

Pregnant Women

In the United States, nearly half of women have already been infected with CMV before their first pregnancy. Of women who have never had a CMV infection, it is estimated that 1 to 4% of them will be infected during pregnancy.

A woman who has a primary CMV infection during pregnancy is more likely to pass CMV to her fetus than a women who has a subsequent infection during pregnancy. However, in the United States, 50 to 75% of congenital CMV infections occur among infants born to mothers who were infected with CMV before they became pregnant.

Routine screening for primary CMV infection during pregnancy is not recommended in the United States for several reasons. Most laboratory tests currently available to identify a first-time infection can be difficult to interpret.  Secondly, current tests cannot predict if the fetus may become infected or harmed by infection.  Thirdly, the lack of a proven treatment to prevent or treat infection of the fetus reduces the potential benefits of prenatal screening.

Very Low Birth Weight and Premature Infants

There are no recommendations against breastfeeding by mothers who are CMV-seropositive. However, infants born <30 weeks gestational age and  <1500g who acquire CMV from breast milk may be at risk of developing a late-onset sepsis-like syndrome. The potential benefits of human milk versus the risk of CMV transmission should be considered when making a decision about the breastfeeding of very premature babies by mothers known to be CMV-seropositive. Freezing and pasteurization of breast milk can decrease the risk of transmission; however, freezing does not eliminate the risk of transmission.