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Newborn Screening Ontario
Hearing Loss Risk Factor Screening

Congenital 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.

CMV 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 to develop 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).

What are the signs of CMV infection in a child or adult?                      

Most healthy children and adults have no signs or symptoms of an 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.

What are the signs of CMV infection in pregnancy?

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

What are the symptoms of cCMV infection in a baby postnatally (once the baby is born)?

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 and this is one of the reasons risk factor screening for PHL is offered.  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/ Rash from low platelets (petechial rash)

What type of hearing loss can be caused by cCMV infection?

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 only some sounds important for speech or all sounds important for speech. The hearing loss can be mild to profound.  In some cases the hearing loss can worsen over time.

What are the most common ways to be exposed to CMV?

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 child care are at increased risk. Also, individuals who work with young children (such as child care providers) tend to have a higher risk of exposure.  Women can also be exposed to CMV through contact with body fluids during sex.

Are there ways to reduce the risk of exposure?

As 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:

  • Frequent hand washing 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

Why aren’t all women who are pregnant or planning a pregnancy screened for CMV?

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

Screening can be considered in pregnant women at high risk of CMV exposure to better advise them about the risk of cCMV infection.

How many infants are expected to be born with cCMV infection in Ontario each year?

It is estimated that 0.64% of infants in Ontario are born with cCMV infection.  This means about 925 infants will be born with cCMV infection each year in Ontario.  Of these only about 10-15% will have symptoms at birth.

What can be done at birth if there is a suspected cCMV infection?

Babies suspected of having cCMV infection should have a physical examination by a doctor and further testing to confirm or exclude the diagnosis.

In Ontario, as part of the Infant Hearing Program, screening for CMV is offered for all babies born after July 29, 2019 as part of risk factor screening for PHL. Babies who screen positive for CMV will be referred to a pediatrician or Infectious Diseases Clinic for further testing.

From May 2018 until July 29, 2019, screening for CMV infection was offered for babies who had a refer result to an audiologist because they did not pass their hearing screening or because a strong risk factor for PHL was recognized at birth.

Please speak to a health care provider if there are concerns or questions about CMV.