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Congenital Cytomegalovirus

These are some frequently asked questions about cytomegalovirus. 

What is congenital cytomegalovirus?

Cytomegalovirus (CMV) is a common virus. Most healthy people will not have any signs or symptoms and will not know they have had it.  When a pregnant woman is infected, there is a risk of infection of the baby. When this happens, it is called congenital CMV infection, or cCMV for short.

cCMV can affect a baby’s growth and the development of a baby’s brain, inner ears, and eyes. Babies with cCMV infection can be born with symptoms or be at risk of developing health problems in early childhood. It is estimated that 1 in 5 babies with cCMV infection will develop permanent problems, most commonly permanent hearing loss (PHL).

Most healthy children and adults have no signs or symptoms of a CMV infection. Some people may develop non-specific symptoms, such as fatigue, sore throat, fever and swollen glands. As these symptoms are common in many illnesses, someone infected with CMV would not realize they were infected.

There may be no signs in a pregnancy of CMV infection. If there are symptoms, they could include:

  • Intrauterine growth restriction (baby is smaller than expected for gestational age)
  • Low amniotic fluid levels
  • Changes in the baby’s brain
  • Small head size
  • Bright area (hyperechogenicity) in the baby’s intestines on ultrasound

Most infants (~85-90%) with cCMV infection will not show any signs of the infection at birth. Permanent hearing loss (PHL) is a common symptom of cCMV infection, this is why CMV is included as part of risk factor screening for PHL. The hearing loss can be present at birth or may develop in childhood. Some other symptoms of cCMV infection can include:

  • Vision problems
  • Developmental disabilities
  • Seizures
  • Small head size
  • Jaundice (yellow eyes or skin)
  • Small size during pregnancy and at birth
  • Low platelets and/or rash from low platelets (petechial rash)

cCMV infection can cause permanent hearing loss (PHL) that might be present at birth (congenital) or might develop in childhood. It can affect one or both ears. The hearing loss may affect some or all sounds important for speech. The hearing loss can be mild to profound. In some cases, the hearing loss can worsen over time.

One of the most common ways to be exposed to CMV is through contact with children who have recently been infected with the virus. Parents of young children in childcare are at increased risk. Also, individuals who work with young children (such as childcare providers) tend to have a higher risk of exposure. Women can also be exposed to CMV through contact with body fluids during sex.

The virus can only be passed on through direct contact with body fluids (such as tears, mucus, saliva, and urine). There are ways to reduce the risk of exposure:

  • Frequently wash hands with soap and water – particularly after possible contact with saliva (feeding or wiping drool) or urine (diaper changes)
  • Avoid sharing food, drinks and utensils
  • Avoid direct saliva contact when kissing
  • Frequently clean toys and other objects (pacifiers) and surfaces that may be exposed to body fluids with soap and water

There are no vaccines available yet against CMV and there is no treatment for CMV in pregnancy that has proven to reduce the risk of infection to the baby.

Screening can be considered for pregnant people at high risk of CMV exposure to better inform them about the risk of cCMV infection.

Babies with suspected cCMV infection should have a physical examination by a doctor and further testing to confirm or exclude cCMV.

Healthcare providers can contact NSO to request the baby's CMV screening results. NSO can provide additional diagnostic analysis of the residual DBS for CMV. 

Risk factor screening for permanent hearing loss began in Ontario for babies born on or after July 29, 2019. Prior to that, beginning in May 2018, targeted CMV screening was available for babies who referred on their newborn hearing screen or had a strong risk factor recognized at birth. 

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