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 stays 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 when in 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. Severe infections 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 have been infected with the virus while in the uterus (womb). Babies with CMV infection pass large amounts of CMV in their saliva and in their urine in the first year of life. Anyone who has not had CMV before can catch it if they come in contact with saliva from these babies e.g. kissing on lips or sharing eating utensils or when changing nappies if they are not careful and do not wash their hands afterwards.
Most other CMV infections are caught mainly from respiratory secretions e.g. from CMV infected people coughing or sneezing and people then coming in contact with the secretions after.
Can CMV be caught from breast milk?
Tiny, very premature babies can occasionally 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 also 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?
Rarely.
Can CMV be caught from other children in day care?
Yes. The infection is usually mild. The risk of catching CMV is strongly 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 practice good hand hygiene 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 their 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 has 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 that she was previously infected with.
Can congenital CMV be prevented?
The only way that congenital CMV can be prevented is to stop a woman who has never had CMV before ever catching CMV during the pregnancy. Women who already have CMV infection in the past may get infected by a new CMV strain or may have "reactivation" of their past virus, this is not preventable nor predictable. About half of all Australian women have had CMV by the time they are pregnant. Pregnant women should minimise their chances of catching CMV by not changing nappies of other people’s babies, always washing their hands after caring for children, avoid kissing children on the lips and not share eating utensils.
What does congenital CMV do to the baby?
Most babies with congenital CMV are born without problems and most will stay symptom free all their life. A few are born with symptoms and 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.
Can congenital CMV be treated?
This is a complicated question which is not easy to answer. It needs to be discussed with a paediatrician, and the risks versus benefits would be outlined by the specialist.
Should babies with congenital CMV be treated differently in day care centres?
Babies with congenital CMV will excrete high amounts of CMV in their saliva and in the urine for the first year of life. This will decrease with time. The child carer looking after a child with congenital CMV can reduce infection risk with CMV by wearing gloves and washing hands well 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 who 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.
Remember:
- Hand washing before and after handling babies and young children is the best way to avoid catching CMV infection.
- Avoid sharing eating utensils and kissing young children on the lips.Pregnant women can reduce their chances of CMV infection by washing their hands after handling any bodily secretions from babies or young children.
- Wearing gloves for nappy changes as well as good hand hygiene for child carers in child care is recommended.
