Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a common virus that is usually harmless. Sometimes it causes problems in babies if you catch it during pregnancy (congenital CMV).

What is CMV?

CMV is similar to the herpes virus that causes cold sores and chickenpox.

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

Your immune system usually controls the virus and most people don’t realize they have it.

How CMV is spread

CMV is mainly spread through close contact with someone who already has CMV. 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 at nursery

the virus has “re-activated” – because you have a weakened immune system

you’ve been re-infected – with a different type (strain) of CMV

Pregnant women can pass an “active” CMV infection on to their unborn baby. This is known as congenital CMV.

CMV doesn’t always cause symptoms

Some people get flu-like symptoms the first time they catch CMV, including:

a high temperature of 38C or more

aching muscles


feeling sick

sore throat

swollen glands

See your doctor if you have flu-like symptoms