Cytomegalovirus (CMV)

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What is cytomegalovirus (CMV)?

Cytomegalovirus or CMV means “big cell virus” because cells grow big when infected.  CMV is one of the viruses in the herpes virus family and therefore related to the other herpes viruses, including herpes simplex virus (HSV) (which causes cold sores) and chickenpox virus. CMV is a very common virus. 

CMV may stay in a person’s system for years, staying in certain white cells in the body. CMV can be shed in saliva or urine but the person remains well and knows nothing about it.

What sort of infections does CMV cause?

Often there is no evidence of illness, but in children and adults, CMV may cause:

  • a cold or a cough and fever
  • a rash and fever
  • an illness like glandular fever, with big glands and hepatitis (inflammation of the liver)

These illnesses are generally mild and get better on their own.

Babies can sometimes catch CMV within the uterus (womb) and can be born with CMV infection.  This is known as congenital CMV.

Children and adults with poor immunity (for example on treatment for diseases such as cancer, or are sick with infections including HIV infection) can get severe CMV infections which tend to affect mainly the lungs or the eyes. Sometimes other organs such as the brain or the gut can be affected.

How do you catch CMV?

Babies born with congenital CMV acquire the virus in the uterus. Babies with CMV infection pass large amounts of CMV in their urine in the first year of life, so anyone who has not had CMV before can catch it when changing nappies if they are not careful and do not wash their hands afterwards.

Most other CMV infections are caught from respiratory secretions (from people coughing or sneezing or exhaling the virus when breathing out).

Can CMV be caught from breast milk?

Tiny premature babies can very rarely get severe CMV infection from breast milk if their mother has had CMV infection before. The risks and benefits of breast milk for these babies should be discussed with your neonatologist (newborn specialist). Healthy term babies can get CMV from breast milk if the mother has had CMV in the past. They almost always never get any symptoms of illness

Can CMV be caught from sex?


Can CMV be caught from other children in day care?

Yes. The infection is usually mild, but the risk of catching CMV is markedly reduced by hand washing.

How can I avoid catching CMV infection?

The best way to avoid catching CMV infection is to wash your hands before and after caring for babies and children.

Pregnant women should observe good hand hygiene by using gloves and by washing their hands after every nappy change. In addition, they should wash their hands after handling any bodily fluids of other children in care e.g. a runny nose.

Can CMV infection be treated?

We do not usually need to treat CMV infection, because most people get better on their own.

We occasionally treat very severely affected babies or children.

What is congenital CMV?

Congenital CMV is when a baby is born with CMV infection, which the baby has acquired from his/her mother while in the uterus. The mother may have had her first ever CMV infection during the pregnancy, or she may have had CMV infection before and it came back during the pregnancy (“reactivation”). In some instances, it is believed that the mother may have caught another strain of CMV which is different from the one with which she was previously infected.

Can congenital CMV be prevented?

Not usually. There is no vaccine yet. The only way would be to stop the mother ever catching CMV during the pregnancy. However, as some women have “reactivation” of the virus, this is not preventable or predictable. About half of all Australian women have had CMV by the time they are pregnant. Pregnant women can often avoid changing nappies of other people’s babies and should wash their hands after caring for children.

Can congenital CMV be treated?

This is a complicated question which is not easy to answer. It would need to be discussed with a paediatrician, and the risks versus benefits would be outlined by the specialist.

What does congenital CMV do to the baby?

The vast majority of babies with congenital CMV remain well all their life.  A few develop long term problems. The most common problem, if there is one, is hearing loss. This is a specialised area and a paediatrician should be consulted.

Should babies with congenital CMV be treated differently in day care centres?

Babies with congenital CMV will excrete high amounts of CMV in their urine for the first year of life. This will decrease with time. The carer looking after a child with congenital CMV can significantly reduce infection risk with CMV by wearing gloves and with diligent hand washing after a nappy change. Just holding and cuddling a baby with congenital CMV will not increase the chance of catching CMV from a baby. It is also important that carers understand that any young child in day care may be infected with CMV. Therefore, carers should wash their hands after handling all children, not just babies known to have congenital CMV.

Who can I talk to about CMV?

A GP or paediatrician or the infectious disease team can help with any questions about CMV infection.



  • Hand washing before and after handling babies and young children is the best way to avoid catching CMV infection
  • Pregnant women can significantly reduce their chances of CMV infection by washing their hands after handling any bodily secretions from babies or young children. Wearing gloves during this activity, in addition to good hand hygiene, in child care is a recommended additional precaution
The Children's Hospital at Westmead
Sydney Children's Hospital, Randwick
Hunter New England Kids Health

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