Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a common virus that is passed on through close contact with another person. In most people it is harmless, but it can cause serious health problems for people with weakened immune systems and for unborn babies.

Key points 

  1. If you have weakened immunity, eg, from chemotherapy, or if you are pregnant, and you get flu-like symptoms, see your doctor.
  2. Most people don’t need treatment for CMV, but antiviral medicine can be used to treat people with a weakened immune system and babies.
  3. There’s currently no treatment for CMV in pregnancy and in most cases the virus doesn’t cause problems for your baby.
  4. You can limit your risk of getting CMV by following good hygiene practices. 

What causes CMV? 

CMV is a virus. It is mainly spread through being in close contact with someone who already has it. It can be passed on through body fluids including saliva, blood and urine.

CMV can only be passed on when it is ‘active’. This is when:

  • you catch the virus for the first time – young children often get CMV for the first time when they start early childhood education
  • the virus has been re-activated because you have a weakened immune system
  • you’ve been re-infected with a different strain (type) of CMV.

Once you have it, it stays in your body for the rest of your life.

What are the symptoms of CMV?

Most people infected with CMV show no signs or symptoms. That’s because a healthy person’s immune system usually keeps the virus from causing illness

Some people get symptoms similar to the flu or glandular fever the first time they catch CMV, including:

  • a high temperature of 38°C or more
  • aching muscles
  • tiredness
  • feeling sick
  • sore throat
  • swollen glands.

If you do have symptoms, they normally get better on their own within about 3 weeks. It’s rare to get symptoms again unless your immune system becomes weakened, eg, due to organ transplant or chemotherapy. It can also be reactivated during pregnancy.

People with weakened immune systems who get CMV can have more serious symptoms affecting your eyes, lungs, liver, oesophagus, stomach and intestines. 

What is congenital CMV?

Pregnant women can pass an active CMV infection on to their unborn baby. This is known as congenital CMV. Pregnant women who work closely with children or already have a young family are more at risk of catching CMV.

Most babies born with CMV infection are healthy at birth and grow up with normal health. Some babies appear healthy at birth but develop problems, such as hearing problems, later on. 

A small number of babies with congenital CMV are sick at birth and have significant signs and symptoms, including premature birth, low birth weight, yellow skin and eyes (jaundice), enlarged and poorly functioning liver, purple skin splotches or a rash or both, abnormally small head (microencephaly), enlarged spleen, pneumonia and seizures. In the most severe cases, congenital CMV can lead to stillbirth (your baby born dead) or neonatal death (dying after birth). 

Some babies with signs of congenital CMV infection at birth may have long-term health problems, such as hearing loss, developmental and motor delay and vision loss. 

How is CMV diagnosed?

See your doctor if you have flu-like symptoms and you’re pregnant or you have a weakened immune system, eg, because of chemotherapy. If your GP is worried about your or your baby’s health they will arrange tests.

How is CMV treated?

If you don’t have any symptoms, CMV doesn’t need treatment. There’s currently no treatment for CMV in pregnancy and in most cases, the virus doesn’t cause problems for your baby.

Antiviral medicine can be used to treat:

  • babies diagnosed with congenital CMV after they are born
  • people with a weakened immune system.

The treatment aims to weaken the virus and reduce the chance of serious problems – but it doesn’t cure CMV infection.

Babies born with congenital CMV need to stay in hospital until the antiviral treatment finishes.

How can I reduce the risk of CMV when pregnant?

There’s currently no vaccine for CMV. The best way to reduce your risk of catching CMV during pregnancy is with good hygiene:

  • wash your hands using soap and hot water – especially after changing nappies, feeding young children or wiping their nose
  • regularly wash toys or other items that get young children's saliva or urine on them
  • avoid sharing food, cutlery, drinking glasses or dummies with young children.

Other tips include:

  • Avoid contact with saliva when kissing a child
  • Do not put a pacifier in your mouth
  • Do not share food, utensils, drinks or straws
  • Do not share a toothbrush
  • Wash your hands after changing a diaper.

Learn more

The following links provide further information about CMV. Be aware that websites from other countries may have information that differs from New Zealand recommendations. 

A range of CMV resources CMV Action, UK
CMV fact sheet for pregnant women and parents
 Centers for Disease Control and Prevention, US
National CMV Foundation
US organisation providing information and resources about CMV, particularly congenital CMV


  1. Cytomegalovirus (CMV) NHS, UK, 2017
  2. Cytomegalovirus (CMV) and pregnancy NSW Government Health, Australia, 2017
  3. Cytomegalovirus infection Department of Health and Human Services, Victoria, Australia, 2018
  4. Cytomegalovirus (CMV) infection Mayo Clinic, US, 2017
  5. About CMV Centre for Disease Control and Prevention, US 
Credits: Health Navigator Editorial Team . Reviewed By: Dr Katie Walland, Advanced Trainee, Infectious Diseases, Waikato Hospital Last reviewed: 27 May 2019