3 July 2020

Cytomegalovirus, or ‘CMV’, infects 85 percent of people by the age of 40, yet most will never know they have it.

In healthy children and adults, the virus might cause nothing more than a flu-like illness that lasts a few days. Others may experience no symptoms at all.

However, for certain people, including pregnant women and those with weakened immune systems (such as transplant patients), the effects can be much more serious.

In fact, CMV is the most common infectious cause of disability in babies in Australia, with about one to two babies born every day seriously affected by the virus.

“CMV rarely causes serious complications but when it does, they can be severe and permanent,” says Children’s Health Queensland Director of Healthy Hearing, Dr Rachael Beswick.

“There is no vaccine, so preventing the spread of CMV in vulnerable groups is the only way we can stop these complications happening.”

What is CMV?

CMV is a member of the herpes family of viruses and similar to the virus that causes glandular fever, herpes simplex (cold sores) and genital herpes.

Once a person has had CMV, the virus stays in their bodies for the rest of their lives and can reactivate if the person develops problems with their immune system. Reactivation can also occur during pregnancy in women who have been infected previously, with a very small risk of transmission of CMV to the unborn baby.

Babies and congenital CMV

If a woman is newly infected with CMV while pregnant, there is a risk that her unborn baby will also become infected (this is known as congenital CMV). About one in Australian 1000 babies is affected by congenital CMV.

The highest risk to the unborn baby occurs when a woman who has never had CMV before is infected with the virus for the first time during pregnancy and when infection occurs during the first half of the pregnancy.

Australian research suggests about six babies from every 1000 will have been infected in utero. Of those six infected, one to two of them will develop permanent disabilities, which can include:

  • hearing loss
  • vision loss
  • small head size
  • cerebral palsy
  • developmental delay
  • intellectual disability
  • death (rare)

How is it transmitted?

CMV is spread via bodily fluid droplets and fluids (such as saliva, mucous, urine and breast milk).

This can also include handling items that have tiny droplets on them – such as tissues, nappies or children’s toys – and then transferring it to your body by touching your eyes, nose, mouth or face.

Infection is most common in children under two years, with a high incidence of CMV among those in day care. Pregnant women who already have young children, or who work with young children, are at the highest risk of catching CMV.

Prevention

Fortunately, CMV does not spread easily, and transmission can be prevented by simple hygiene methods:

  • Wash your hands with warm soapy water before and after preparing food, after feeding a young child, after handling children’s toys, after going to the toilet or after changing a child’s nappy.
  • Wash toys, and other surfaces that come into contact with urine or saliva, with detergent and warm water.
  • Children who are unwell should stay home from childcare or school.

Pregnant women particularly, should observe strict hygiene practices to avoid contact with infectious fluids – especially around young children.

  • Do not place a child’s dummy/pacifier into your mouth.
  • Do not share a toothbrush with a young child.
  • Do not share food or drinks or eating utensils with a young child.
  • Avoid contact with saliva when kissing a young child.

More information

Congenital CMV Association of Australia
Cytomegalovirus fact sheet (Queensland Health)