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What is Cytomegalovirus (CMV)?
Cytomegalovirus (sigh-toe-mega-low-vie-russ), also known as CMV, is a common virus similar to viruses that cause bad colds, chicken pox, and cold sores. According to the Centers for Disease Control and Prevention (CDC), in the United States nearly 1 in 3 children have been infected with CMV by age of five, and over half of adults have been infected with CMV by age 40. Once CMV is in a person's body, it stays there for life and can become active again. Like a cold, a person can also catch CMV more than once. To find additional information about CMV, please visit Cytomegalovirus (CMV) and Congenital CMV
How is CMV transmitted?
CMV is passed from person to person by contact with body fluids including saliva, urine, semen, breastmilk, blood, and tears. The virus can also pass through the placenta during pregnancy so that the baby is born with the infection (known as congenital CMV or cCMV).
CMV is often spread by young children. People who live with or care for young children may be more likely to get CMV. Avoiding contact with saliva and urine from young children may reduce the risk of CMV infection. For additional information about CMV, go to Cytomegalovirus (CMV) and Congenital CMV
What is the difference between acquired and congenital CMV (cCMV)?
Acquired CMV is infectious and can be passed from person to person. Congenital CMV (cCMV) occurs when a pregnant person develops an active CMV infection, and the virus passes through the placenta during pregnancy. Although both are caused by the same virus–CMV–they have very different symptoms and outcomes.
What are the symptoms of acquired CMV?
Most healthy people do not know that they have had a CMV infection because the virus usually does not cause any notable symptoms. Sometimes, people will feel like they have a mild cold with:
- Sore throat
- Muscle aches
People with weakened immune systems who become infected with CMV may have more serious and even life-threatening symptoms. They may be treated with antiviral medicine.
What is congenital CMV (cCMV)?
When a baby is born with the CMV infection, it is called congenital CMV (cCMV). The virus can present itself in several ways; babies who have symptoms at birth, babies who look healthy at birth but will develop permanent hearing loss, and babies who are born without symptoms of congenital CMV and are not expected to develop symptoms. Newborn screening cannot predict which group a baby will fall into. According to the CDC:
- 1 out of every 200 babies is born with congenital CMV.
- Most babies born with congenital CMV are healthy.
- Congenital CMV is the most common infectious cause of birth defects in the United States.
- About 1 out of 4 (or 25%) of babies born with congenital CMV will have hearing loss either present at birth or develop it in childhood.
Why screen for congenital CMV?
Congenital CMV is an infection present at birth:
- In Minnesota, we expect to find CMV virus in about 300 newborns annually through newborn screening. Pilot studies suggest that the majority of the babies are expected to be asymptomatic, whereas 20% of infants diagnosed with congenital CMV results in clinical disease. Signs of this disease range from isolated hearing loss (which may occur postnatally) to systemic and severe neurodevelopmental manifestations.
- Screening for congenital CMV will help identify infants at risk for developing hearing loss and who may benefit from follow-up monitoring and early access to interventions and treatment.
What health concerns accompany congenital CMV?
Some babies with congenital CMV may have signs found at birth, such as:
- Microcephaly (small head).
- Low birth weight.
- Jaundice (yellowing of the skin or whites of the eyes, which is often seen in newborns).
- Blueberry muffin rash (purple dots seen on the skin due to abnormal blood clotting).
- Hepatosplenomegaly (enlarged liver and spleen).
- Muscle weakness.
Other concerns related to CMV:
- Need to be in the Newborn Intensive Care unit (NICU).
- May not pass newborn hearing screen.
Why is congenital CMV part of newborn screening?
Clinical testing cannot tell the difference between congenital CMV and acquired CMV, therefore, we rely on timing. Testing after the baby is 21 days old cannot distinguish the difference between infections that happened before or after birth. Detecting congenital CMV can find the virus at birth and can help find potential complications from the infection.
What happens after CMV is found by newborn screening?
If CMV is detected on the newborn screen, the next step is for the baby’s health care provider or clinic to collect urine for a diagnostic PCR test to check for the virus. The sample must be collected before the baby is 21 days old for it to be accurate.
It can be a little tricky to collect a urine sample from a newborn. Newborn urine collection is done by sticking a special bag inside the baby’s diaper to collect the urine the next time the baby pees. It may take a few attempts, but it is not invasive and does not hurt the baby.
- If CMV is not found in the baby’s urine, no more testing is needed unless the health care provider has additional clinical concerns.
- If CMV is found in the baby’s urine, more testing may be recommended, including:
- Multiple hearing tests by a pediatric audiologist.
- Eye exam by an ophthalmologist (MD who specializes in children’s eye problems).
- Ultrasound of the head, or possibly an MRI.
- Blood draw to make sure the blood is clotting well, and the liver is working.
- Regular visits to check the baby’s health and development.
- Meeting with an infectious disease (ID) specialist may also be recommended.
What intervention/treatment is available to children with congenital CMV?
Most babies with congenital CMV will not need treatment but may benefit from regular audiology exams. Some babies with signs of congenital CMV at birth may show improved hearing and developmental outcomes after getting antiviral medicine. It is important to talk with your health care provider about the risks and benefits of antiviral medication.
Other options for intervention include:
- CDC Early Intervention Services to promote healthy development.
- Referral to Help Me Grow Minnesota, for possible evaluation and early intervention services: Refer a Child: Professional Form.
- Managing current signs and symptoms.
- Monitoring for new signs and symptoms, especially hearing loss.
- Family support.
- MN Department of Health Early Intervention: Before 6 Months.