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Cytomegalovirus (CMV)

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

What is cytomegalovirus (CMV)?

Cytomegalovirus is a virus. The name means "big cell" virus. It is related to the glandular fever virus, EBV, and is a member of the family of herpes viruses. The other herpes viruses are herpes simplex (which causes cold sores), varicella-zoster (which causes chickenpox and shingles), EBV (which causes "glandular fever", also known as "infectious mononucleosis") and the virus which causes roseola (an illness with high fever and a measles-like rash in young infants).

All herpes viruses can lie dormant in the body for years after first causing an infection. They may then come back again later and cause symptoms. For example, the chickenpox virus first causes chickenpox, but may come back years later and cause shingles.

What does CMV cause?

In children and adults CMV infection may cause:

• a cold or a respiratory illness with cough and fever
• an illness with rash and fever, or
• a glandular fever-like illness with big glands and fever

All these illnesses are fairly mild. Most people who get severe CMV infection are people who do not have good immunity, such as people with cancer or with AIDS. Some women catch CMV during pregnancy and pass the CMV onto the baby across the placenta (called "congenital CMV"), fortunately, only a small number of these babies get severe and lasting symptoms.

How do you catch CMV?

CMV is a very common virus and is spread from a person with active CMV infection to a person who is "susceptible" to the virus. The mode of spread is by direct contact with secretions containing the virus e.g. saliva or other respiratory droplets. In general terms, "susceptible" people are people who have never been infected by the virus before. CMV can also cross the placenta, so some babies can be born with congenital CMV infection if their mothers get infected with CMV during pregnancy.  The incidence of this is uncommon in Australia. Congenitally infected infants excrete the CMV in high amounts in the urine for the first year or life, which is therefore a potential source of infection (eg. from a wet nappy).  Other ways of catching infection are less common. Children in day cares are at higher risk of catching the virus. Parents of these children who have never had CMV infection before are also at risk of catching the virus from this child.  People who work as carers in child care centres are particularly at risk of catching CMV infection. Hospital staff are no more likely than anyone else in the community to be infected.

Can CMV infection be prevented?

The best way to avoid catching CMV infection is by ALWAYS washing your hands before and after caring for babies and children. There is no vaccine against CMV.

What is congenital CMV infection?

A baby with congenital CMV infection is one who is born with the infection. The mother may have had her first ever infection (her primary infection) with CMV during the pregnancy or, rarely, she may have had CMV in the past and it "reactivated" or "came back" during pregnancy.

How severe is congenital CMV infection?

Most babies with congenital CMV infection are born perfectly normal and never have any problems. About one-in-ten infected children will develop lasting symptoms, of which deafness and mental development are the major concerns. Occasionally, babies with congenital CMV infection are born with a purple rash, big liver and spleen, and a small head. These babies usually have long-term problems such as delay in their development, convulsions, deafness and poor vision. Some drugs are effective in treating CMV, but they have not been shown to cure the effects of congenital CMV infection.

Who can I talk to if I am worried about CMV?

Pregnant women may be scared of catching CMV or having a baby with congenital CMV. The issues and the blood tests are quite complicated. Talk to your family doctor and ask for a referral to a specialist in infectious diseases with knowledge in this area.

• Hand washing before and after handling babies and children is the best way to avoid catching CMV infection.

The Children's Hospital at Westmead Tel: (02) 9845 3585 Fax: (02) 9845 3562 www.chw.edu.au	Sydney Children's Hospital, Randwick Tel: (02) 9382 1688 Fax: (02) 9382 1451 www.sch.edu.au	Kaleidoscope, Hunter Children's Health Network Tel: (02) 4921 3670 Fax: (02) 4921 3599 www.kaleidoscope.org.au