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Newborn Screening Ontario

Cytomegalovirus (CMV)

What is 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.


Why is it important if I am planning a pregnancy or am pregnant?

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.


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?

Some symptoms of CMV infection prenatally (before a baby is born) are:

·         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

However, there may be no signs in a pregnancy of CMV infection.


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

A baby with cCMV may be asymptomatic (no signs of the infection) or symptomatic at birth.  Most infants (~85-90%) with cCMV infection will not show any signs of infection.  Hearing loss is a common symptom of cCMV infection and one of the reasons enhanced hearing screening is offered.  The hearing loss can be present at birth or may develop later 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 a permanent 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.


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.


How can I reduce my risk?

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 your 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 ~925 infants will be born with cCMV infection each year in Ontario.  Of these only ~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 blood work, urine, and/or saliva investigations ordered to confirm or exclude the diagnosis.


In Ontario, as part of the Infant Hearing Program, babies will be eligible for expanded hearing screening.  This would involve the hearing screen and having the dried blood spot sample, obtained soon after birth, screened for presence of CMV in the Newborn Screening Ontario laboratory.


If you have concerns or questions about CMV and are pregnant or planning a pregnancy, please talk to your health care provider.

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