CMV

Cytomegalovirus, or CMV, is found universally throughout all geographic locations and socioeconomic groups, and has infected between 50% and 85% of adults in the United States by 40 years of age. CMV is also the virus most frequently transmitted to a developing child before birth.

Each year in the United States approximately 40,000 children are born with congenital CMV infection with 1 in every 150 children born with congenital CMV.

High-risk Groups

CMV infection is important to certain high-risk groups, especially pregnant women. Major areas of concern are the risk of infection to the unborn baby during pregnancy and the risk of infection to pregnant women who work with children, including mothers who have already had children.

Approximately 40-50% of college-educated, white women of childbearing age in this country currently have no protective immunity to CMV, making this group most vulnerable to contracting a primary CMV infection while pregnant and passing the disease on to an unborn baby. Young, American women of the middle and upper socio-economic classes have lower rates of natural CMV immunity because many have had minimal contact with small children prior to becoming pregnant themselves.

Transmission

CMV can be transmitted to the unborn child of a mother with a primary or a recurrent CMV infection. When a baby catches CMV prior to birth it is known as a congenital CMV infection. Approximately 90% of all infants who are infected with CMV prior to delivery are born without symptoms of the virus; however, the remaining 10% will have varying degrees of abnormalities.

Transmission of the virus is often preventable because it is most often transmitted through infected bodily fluids that come in contact with hands and then are absorbed through the nose or mouth of a susceptible person. Therefore, care should be taken when handling infants, small children and items like diapers. Simple hand washing with soap and water is effective in removing the virus from the hands.

Effects on Pregnancy

The incidence of primary (or first) CMV infection in pregnant women in the United States varies from 1% to 3%. When infected with CMV, most women have no symptoms and very few have symptoms resembling mononucleosis. It is their developing unborn babies that may be at risk for congenital CMV disease. CMV remains the most common cause of congenital (meaning from birth) viral infection in the United States. For infants who are infected by their mothers during pregnancy, two potential problems exist:

1. Generalized infection may occur in the infant, and symptoms may range from moderate enlargement of the liver and spleen (with jaundice) to fatal illness. With supportive treatment, most infants with CMV disease usually survive. However, 80% to 90% will have complications within the first few years of life that may include hearing loss, vision impairment, and varying degrees of mental retardation.
2. Another 5% to 10% of infants who are infected but without symptoms at birth will subsequently have varying degrees of hearing and mental or coordination problems.

--Adapted from the CDC's National Center for Infectious Diseases website