Cytomegalovirus Infections 

Cytomegalovirus (CMV) is a common viral infection that usually causes no symptoms or mild flu-like symptoms in infected children and adults. CMV is a member of the herpes virus family. It is most common in young children. 

About half of pregnant women have had CMV in the past and most do not need to be concerned about it during pregnancy (1). However, an infected woman can pass the virus on to her baby during pregnancy and breastfeeding. Most infected babies have no serious problems from the virus (1, 2). In a minority of cases, though, infected newborns develop serious illness or lasting disabilities, or even die. 

How is CMV spread? 

CMV can be passed from person to person through contact with infected body fluids, such as saliva, mucus, urine and blood. It also can be transmitted sexually or through infected blood products. 

Pregnant women can pass the virus to their babies before or during birth. Breastfeeding moms can pass the virus to their baby through breastmilk. However, babies who become infected from breastfeeding rarely have any serious problems from the virus (1, 2). 

How does  CMV affect an adult? 

Infected adults occasionally develop a mononucleosis-like illness, which can include symptoms such as sore throat, fever, swollen glands and fatigue. CMV can cause serious illness, such as pneumonia and sight-threatening eye infections, in individuals with AIDS and other immune-system disorders and in organ-transplant recipients. 

How common  is CMV in newborns? 

CMV is  the most common congenital (present at birth) infection in the United States (1). Each year about 1 in 150 babies  is born with congenital CMV infection (1). About 8,000 children each year develop lasting disabilities caused by congenital CMV infection (1). 

How does congenital CMV infection affect the baby? 

Most babies are not harmed by the virus. About 90 percent of babies who are infected with CMV have no symptoms at birth (1, 2). However, about 10  to 15 percent of infected babies develop one or more lasting disabilities (such as hearing loss, vision loss or learning problems) during  the first few years of life (1, 3). For this reason, all babies born with congenital CMV infection should have regular hearing  and vision tests (1). 

About 10  percent of infected newborns show symptoms of CMV at birth (1, 2). Symptoms may include (1, 2): 

• Enlarged spleen 
• Liver problems 
• Jaundice (yellowing of the skin  and eyes) 
• Distinctive rash 
• Small size 
• Seizures 

Up to 20 percent of babies with CMV symptoms die (3, 4). About  80 to 90  percent of survivors develop serious disabilities, such as mental retardation, cerebral palsy, or vision and hearing loss (1). 

Some studies suggest that treatment with antiviral drugs, such as ganciclovir, may help prevent or reduce the severity of hearing loss and other disabilities  in babies with symptomatic congenital CMV (3, 5). Ganciclovir is used to treat adults with AIDS or other immune-system problems who have CMV-related eye infections. However,  the drug can have strong side effects, so it only should be used in infants with severe congenital  CMV (1). 

Which women are at highest risk of passing  CMV on to their babies? 

A woman who contracts CMV for the first time during pregnancy has about a 1-in-3 chance of passing the virus on to her fetus (1). A woman can pass CMV on to her baby at any stage of pregnancy. However, studies suggest that babies are more likely to develop serious complications when their mother  is infected in the first 20 weeks of pregnancy (2). 

Like other viruses in the herpes family,  CMV stays in the body after symptoms disappear. Occasionally the disease reactivates. However, only about 1 percent of fetuses become infected when their mother has a recurrent  infection (1, 5). When these babies do become infected, they rarely develop any serious CMV-related problems (5). 

How is CMV diagnosed? 

In adults, CMV usually is diagnosed  with blood tests that look for certain CMV-fighting antibodies. In newborns, providers diagnose CMV by identifying  the virus in body fluids within 3 weeks of birth (1, 2). 

Can CMV be diagnosed before birth? 

If a pregnant woman is diagnosed with CMV, her provider  can test her fetus for the infection using amniocentesis. In amniocentesis, the provider inserts a thin needle through the pregnant woman’s abdomen to withdraw a small amount of amniotic fluid. The lab tests the fluid for CMV. This test, however, cannot tell whether a fetus has severe symptoms of the disease. For this reason, providers use an ultrasound to identify brain abnormalities and other signs that a fetus may  be severely affected. 

Is there treatment for CMV infection  in pregnancy? 

Recent studies suggest that treating infected pregnant women  with immune globulin (disease-fighting antibodies) may help prevent or lessen symptoms in their babies (3, 5, 6). This treatment is experimental, and more studies on its effectiveness are needed. No other treatments are currently available. 

How can  a pregnant woman help prevent  CMV infection? 

Women can help reduce their risk of CMV by practicing careful hygiene. This  is especially important for women with young children at home or those who work with young children (such as child care workers). As many as 70 percent of children between 1 and 3 years of age who attend day care may have the virus in body fluids and  can pass it on to their families or caretakers (2). 

To help prevent CMV, pregnant women should (1): 

• Wash their hands thoroughly after any  contact with urine, nasal secretions and saliva of young children,  including after changing diapers, wiping noses  or drool, and picking up toys 
• Avoid kissing young children on  the mouth or cheek 
• Avoid sharing food, drinking glasses and eating utensils  with young children 

Pregnant health care workers who may be in contact with infected patients, including newborns, also should practice good hygiene. They should follow the universal precautions recommended in medical settings for handling potentially contaminated materials. Medical or child care workers may want to get tested before pregnancy to see if they have had  CMV in the past. If they have already had CMV, they have little cause for concern during pregnancy. Child care workers who have never been infected (or have not been tested), should try to limit close contact with children younger than 2½ years of age (1). Routine screening for all pregnant women is not recommended (1). 

Is the March of Dimes conducting research on CMV? 

March of Dimes grantees and other researchers are developing and testing vaccines that may help protect babies against CMV. March of Dimes grantees are learning more about this virus and how it multiplies and spreads in the fetus, in order to develop effective drugs that can help prevent birth defects in infected babies. One grantee is seeking to determine whether treatment with ganciclovir or other anti-viral drugs during pregnancy can prevent congenital CMV infection in infants of infected mothers. 

Notes: Dr. M. Kristine Schlossberg

[Watch page ]

EditText of this page (last edited February 27, 2010)