Cytomegalovirus (CMV)

by CDC

General Information

• Between 50% and 80% of adults in the United States are infected with CMV by 40 years of age
• CMV is the most common virus transmitted to a pregnant woman's unborn child
• Approximately 1 in 150 children is born with congenital CMV infection
• Approximately 1 in 750 children is born with or develops permanent disabilities due to CMV
• Approximately 8,000 children each year suffer permanent disabilities caused by CMV
• Congenital CMV (meaning present at birth) is as common a cause of serious disability as Down syndrome, fetal alcohol syndrome, and neural tube defects

About the Virus

CMV is found throughout the world in all geographic and socioeconomic groups, but, in general, it is more widespread in developing countries and in areas of lower socioeconomic conditions. CMV is a member of the herpesvirus family, which includes the herpes simplex viruses and the viruses that cause chicken pox (varicella-zoster virus) and infectious mononucleosis (Epstein-Barr virus). CMV is found in body fluids, including urine, saliva (spit), breast milk, blood, tears, semen, and vaginal fluids. Once CMV is in a person's body, it stays there for life. Most CMV infections are "silent," meaning they cause no signs or symptoms in an infected person. CMV can cause disease in unborn babies and in people with a weakened immune system.

Transmission and Prevention

Transmission of CMV occurs from person to person, through close contact with body fluids (urine, saliva (spit), breast milk, blood, tears, semen, and vaginal fluids), but the chance of getting CMV infection from casual contact is very small.

In the United States, about 1%-4% of uninfected mothers have primary (or first) CMV infection during a pregnancy.

33% of women who become infected with CMV for the first time during pregnancy pass the virus to their unborn babies.

No actions can totally eliminate all the risks of getting CMV, but there are simple measures that can reduce spread of the disease.

Signs and Symptoms of CMV

Most healthy children and adults infected with CMV have no symptoms and may not even know that they have been infected. Others may develop a mild illness. Symptoms may include fever, sore throat, fatigue, and swollen glands. But these are also symptoms of other illnesses, so most people don't know it when they get CMV.

Most babies born with CMV (in other words congenital CMV) never develop symptoms or disabilities. When babies do have symptoms, some can go away but others can be permanent.

Examples of symptoms or disabilities caused by congenital CMV:

Temporary Symptoms

• Liver problems
• Spleen problems
• Jaundice (yellow skin and eyes)
• Purple skin splotches
• Lung problems
• Small size at birth
• Seizures

Permanent Symptoms or Disabilities

• Hearing loss
• Vision loss
• Mental disability
• Small head
• Lack of coordination
• Seizures
• Death

In some children, symptoms do not appear until months or years after birth. The most common of these late-occurring symptoms are hearing loss and vision loss. Children with congenital CMV are more likely to have permanent disabilities and symptoms that get worse if they had symptoms of CMV infection at birth. But, some children who appear healthy at birth can develop hearing or vision loss over time due to congenital CMV. For this reason, if you know your baby was born with CMV, it is important to have his or her hearing and vision tested regularly.

Testing for CMV

CMV testing during pregnancy

Although it is not currently recommended that all pregnant women be routinely tested, a blood test can help you know if you have ever been infected with CMV. This test shows if your body has developed antibodies against CMV by testing for a type of antibody called "IgG antibodies." If you are pregnant and test positive (have CMV IgG antibodies), your chance of passing the virus to your unborn baby is small unless your CMV infection occurred in the past few months. Other CMV tests (IgM or IgG avidity) can help determine whether your infection is recent, but these tests are not perfect and may not be commercially available.

If you are pregnant and test negative (have no CMV antibodies), your unborn baby has a high risk of getting CMV if you get infected during pregnancy. For more information about risk of CMV during pregnancy, please visit the CMV and pregnancy page. If you are pregnant and test negative, you should take extra care to use good hygiene (see the CDC Ounce of Prevention site) when you are around young children since they often (10%-40% of the time) have CMV in their urine and saliva.

If your doctor determines that you had a new CMV infection during your pregnancy, this does not mean that your unborn baby is infected. In many cases, you can be infected with CMV but it will not spread to your unborn baby. You would need to do more invasive tests, such as amniocentesis, to find out if your unborn baby is infected. In most cases, babies born with CMV would develop normally. For these reasons, routine CMV testing during pregnancy is not recommended. Consult your doctor about CMV testing if you are concerned that you became infected with CMV during your pregnancy.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.