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Newborn Screening Ontario
Expanded Hearing Screening

CMV Detected

What does a screen positive result mean?

A screen positive result means that the baby most likely has congenital cytomegalovirus (cCMV) infection.  However, this still needs to be confirmed through other diagnostic testing.

If the baby has:

  • Hearing loss and confirmed cCMV infection – cCMV could be the cause for the baby's hearing loss


  • Normal hearing test and confirmed cCMV infection – the baby still has a ~10% risk of developing early childhood hearing loss

What happens next?

A referral from Newborn Screening Ontario will be sent to the nearest Follow-Up Centre Infectious Diseases (ID) Clinic.  Someone from NSO or the ID clinic will contact the family directly once they have received the referral to talk about the screen positive result and to arrange an appointment.

What is cytomegalovirus (CMV)?

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 (cCMV) infection.

It is estimated that >50% of adults in Canada have been infected with CMV by the age of 40 years.

The percentage of babies born in Ontario with cCMV infection is estimated to be 0.64%.  This means about 925 babiess will be born with cCMV infection each year in Ontario.  Of these only ~10-15% will have symptoms (signs of an infection) at birth.

What are the possible signs and symptoms of cCMV infection?

A baby infected with CMV prenatally (before birth) may have no signs or symptoms of the exposure (asymptomatic) or may be symptomatic at birth.  The majority of babies (~85-90%) with cCMV infection are asymptomatic.  In babies who are symptomatic, hearing loss is a common symptom of cCMV infection and this is one of the reasons expanded hearing screening is offered.  The hearing loss can be present at birth or occur later in childhood.  Some other symptoms of cCMV infection may include:

  • Vision problems
  • Development disabilities
  • Seizures
  • Small head size
  • Jaundice (yellow eyes or skin)
  • Small size during the 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 a hearing loss 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.

Is there treatment available?

If cCMV infection is found through the hearing loss risk factor blood spot screen, the baby will be checked for symptoms.  If symptoms are present, they will be followed by specialists and may be offered treatment.  If they do not have symptoms at birth, they will be offered ongoing appointments to check for hearing loss and problems with development during early childhood.  The risk of developing a problem during early childhood is about 7-15%.

Antiviral treatment, such as valganciclovir, is available for babies who are symptomatic.  The ID specialist will discuss if a baby is eligible for antiviral treatment.

What follow up is recommended for cCMV infection?

As mentioned above, babies will be checked for symptoms of cCMV infection and will have diagnostic testing (blood, urine, and/or saliva samples taken and physical examination) performed to confirm the diagnosis.  Initially, they will be seen in the ID clinic.  A number of other specialists may be involved in the assessment and ongoing care of the baby: