Cytomegalovirus

Cytomegalovirus (CMV) is a common virus that is part of the herpes family of viruses.

CMV is spread through bodily fluids such as saliva and urine, and can be transmitted from person to person through close bodily contact.

Like most other herpes-type viruses, once you're infected by CMV it will remain dormant in your body for the rest of your life.

There is no cure for CMV. A possible vaccine for CMV is currently being researched and used in clinical trials but it's unlikely that a vaccine will become publically available before 2012 at the earliest.

Types of CMV

The three main types of CMV infections are:

• Acquired (or primary) CMV: a CMV infection that is contracted for the first time.
• Reoccurring CMV: a previously dormant CMV infection that reoccurs due to a weakened immune system.
• Congenital CMV: a CMV infection that develops in pregnancy and can affect the unborn baby.

How common is CMV?

CMV is one of the most common viral infections. It's estimated that 40-80% of all adults aged 40 or over have been infected by CMV. Most people develop a CMV infection during their early childhood.

Outlook

Unlike other viral infections, CMV causes no, or very few, symptoms. Most people will be unaware that they've developed an infection.

CMV only presents a public health problem when a CMV infection develops, or reoccurs, in certain vulnerable groups of people. There are two main groups of people who are at risk from CMV. They are:

• People with a weakened immune system , particularly those with HIV or who have recently received an organ or bone marrow transplant.
• Unborn babies.

HIV

People with advanced HIV, who have a severely weakened immune system, can sometimes experience a reoccurrence of a CMV infection, which can lead to organ failure. Eye damage which can cause blindness often occurs in these cases.

These types of infections were widespread in the 1980s, but are much less common now due to the more effective anti-HIV medicines introduced during the 1990s.

Organ transplants

In order to prevent their body rejecting a donated organ, people who have recently undergone an organ transplant often have to take medicines that suppress their immune system (immunosuppressants).

In many cases, a previously dormant CMV infection can reoccur as a result of a person’s weakened immune system, and can lead to organ damage.

Anti-viral medicines are often given to people who have had an organ transplant as a precaution against CMV.

Unborn babies

If a woman who was previously uninfected by CMV becomes infected during pregnancy, there's a risk that she may pass the infection on to her unborn baby. This is known as a congenital CMV. It is estimated that one in every 200 babies will be born with congenital CMV.

Only 10% of babies who are born with congenital CMV will have symptoms at birth. But these symptoms can be serious and may lead to long-term complications such as learning difficulties.

A further 10% of babies who are born with congenital CMV will have no symptoms at birth, but will experience hearing loss in later life.

See Prevention, above, for more information about how to prevent a CMV infection during your pregnancy.

Immune system

Brain

Swelling

Coma