Cytomegalovirus (CMV)

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 is therefore related to the other herpes viruses. These include 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. It is believed that CMV stays 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 (inflamed liver)

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

Babies can sometimes catch CMV within the uterus and thus be born with CMV infection (congenital CMV) which we will describe later.

Children and adults with poor immunity (for example HIV infection or on treatment for cancer) 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 (womb). 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 just 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).

Can CMV be caught from sex?

Rarely.

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 or by washing 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 snotty 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 on its own 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. The only way would be to stop the mother ever catching CMV. About half of all Australian women have had CMV by the time they are pregnant. Pregnant women can 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 without an easy answer. The risks versus benefits will be outlined by the paediatrician.

What does congenital CMV do to the baby?

The vast majority of babies with congenital CMV remain well all their life. A few develop lasting problems.

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 donning gloves and 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. Any young child could be carrying CMV. Therefore, carers should wash their hands after handling all children, not just the babies with 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 handlng any bodily secretions from babies or young children. Donning gloves during this activity in child care is recommended additional precaution.