What is CMV?

Cytomegalovirus (CMV), pronounced sigh-toe-MEG-uh-low-Virus, is a common virus that infects people of all ages. More than half of adults have had CMV by age 40, and nearly 1 in 3 children catch it before age 5. Once you have CMV, the virus stays in your body for life. It usually stays inactive and does not cause health problems.

CMV is part of the herpesvirus family. It spreads through contact with body fluids, such as saliva, urine, blood, tears, semen, or breast milk.

When symptoms do appear, they are usually mild and feel like a common cold:

• Feeling very tired
• Mild fever
• Sore throat
• Swollen glands (lymph nodes)
• Muscle aches

Who is at risk?

CMV is mild for most people. But two groups have a higher risk of serious problems:

Developing babies

If a pregnant person catches CMV, the virus can pass to the developing baby. This is the most serious risk from CMV.

People with weakened immune systems

This includes people living with HIV, people who had an organ or bone marrow transplant, and people getting chemotherapy. For them, CMV can seriously affect the eyes, lungs, liver, or gut.

CMV and pregnancy

When a baby is born with CMV, it is called congenital CMV (cCMV). Most of these babies grow up healthy. But some will have long-term health problems. CMV is the top cause of childhood hearing loss that is not passed down through genes.

Possible effects at birth

• Premature birth
• Low birth weight
• Yellow skin and eyes (jaundice)
• Small head size (microcephaly)

Possible long-term effects

• Hearing loss that gets worse over time
• Vision loss
• Delays in development
• Trouble with movement

CMV by the numbers

• About 1 in 200 babies is born with congenital CMV.
• About 1 in 5 of these babies will have long-term health effects.
• CMV is the top cause of childhood hearing loss that is not passed down through genes.

Testing for CMV

CMV testing can happen at two different times, and the tests are not the same. During pregnancy, testing looks for signs of infection in the pregnant person. After birth, testing checks whether a newborn has CMV.

Testing during pregnancy

Routine CMV testing is not recommended for all pregnant people. Major medical groups in the United States, including the CDC and the American College of Obstetricians and Gynecologists, advise against it. It can be hard to tell whether an infection happened long ago or recently. And if it was recent, many things affect whether the virus reaches the baby or causes problems. If you are worried, talk with your provider to see whether testing is right for you.

If testing is done, it uses a blood sample to look for antibodies, the proteins your body makes to fight a virus:

• One test shows whether you have ever had CMV at any point in your life.
• Another test looks for signs of a recent or current infection.
• If that test is positive, a follow-up test can estimate whether the infection happened recently (within the last 3 to 4 months) or long ago.

Because testing is not routine, it is usually done only in certain situations:

• You develop symptoms during pregnancy, such as an unexplained fever, strong tiredness, or swollen glands.
• A routine ultrasound shows signs that can be linked to CMV.
• You have a known exposure, or you ask for testing after talking through the risks with your provider. This is more common for people who work in childcare or have a toddler at home.

Why routine screening is not recommended

• The results are hard to read. A blood test can show a recent infection, but it cannot tell whether the virus will reach the baby or cause harm.
• Past infection does not fully protect you. If you have had CMV before, it can become active again, or a new strain can infect you during pregnancy. The risk to the baby is lower than with a first-time infection, but it is not zero.
• Prevention matters most. There is no CMV vaccine yet, and antiviral treatment during pregnancy is mostly used in specialist or clinical-trial settings. So health agencies focus on simple hygiene habits for all pregnant people, whatever their test results.

Testing your newborn

Testing a newborn for CMV is quick, painless, and very accurate.

Test within 21 days of birth

A CMV test must be done in the first 21 days after birth. A test in this window shows the baby got CMV during pregnancy, not after. If your baby fails a newborn hearing test or shows signs of infection, ask for a CMV test right away.

Here is how newborn testing works:

Newborn CMV testing is usually done when a baby fails their hospital hearing test or shows signs of infection at birth. Many newborns have mild jaundice in their first weeks because their liver is still growing, so only babies whose signs point to CMV are tested.

Babies can also get CMV after birth through close contact or breast milk. This is called postnatal CMV. It does not carry the same risk of serious, long-term problems.

Treatment and support

Finding CMV early opens the door to treatment and support that can protect your baby's development.

Antiviral medicine

Some babies are born with signs of CMV. For them, antiviral medicine started in the first month of life can protect hearing and development. Starting early makes a big difference.

New Jersey Early Intervention System (NJEIS)

New Jersey offers extra support for babies and toddlers who qualify. This can include physical therapy, speech therapy, and regular hearing checks. Learn about NJEIS.

Prevention

Young children, especially toddlers under age 3 in daycare, often carry CMV in their saliva and urine for months, even when they seem well. Simple, everyday habits can lower your risk.

• Wash your hands. Scrub with soap and water for 20 seconds after changing diapers, wiping noses, handling toys, or feeding young children.
• Do not share food or utensils. Do not share cups, straws, forks, spoons, or food with infants and toddlers.
• Keep pacifiers clean. Never put a child's pacifier in your mouth.
• Kiss on the forehead. Kiss young children on the forehead, or give a hug instead of kissing on or near the lips.
• Clean surfaces and toys. Wipe down changing tables, countertops, and toys often.

CMV in schools and childcare

Children with congenital CMV do not need to stay home from childcare or school unless they have a fever. Up to 70% of healthy toddlers carry CMV off and on without symptoms. So keeping one child with CMV home does not protect anyone. Good hygiene habits protect staff and other children.

For help deciding when to keep your child home from school when they are sick, see your local health department resources.

Did you know?

New Jersey's CMV awareness mandate: how it came to be

CMV is the most common viral infection that babies are born with in the United States. Even so, surveys show that more than 90% of people have never heard of it or talked about it with their provider.

To close this gap, New Jersey passed a law (P.L. 2021, c.413). It directs the Department of Health to run a statewide awareness campaign and keep education materials in English and Spanish.