Congenital cytomegalovirus (CMV) infection
Introduction
CMV is a common infection which is part of the herpes family of viruses. The symptoms of CMV infection in children and
adults are mild and rarely cause any significant concern. However, CMV can cause more serious problems in an unborn
baby.
CMV is spread through bodily fluids including saliva, semen, blood, urine, vaginal fluids and breast milk. Once a person is
infected the virus remains inactive in their body for the rest of their life. Congenital CMV infection occurs when a pregnant
mother who is infected with CMV passes it to her unborn baby and is thought to affect 3 per 1000 babies born in the UK.
What causes congenital CMV infection?
Congenital CMV infection is caused when the virus is passed from a mother to her unborn baby via the placenta. Most cases
of congenital CMV develop when a pregnant woman is infected by the CMV virus for the first time during, or shortly before,
pregnancy. In some cases, a previously inactive CMV infection can reoccur during pregnancy because the mother has a
weakened immune system. The mother could also be re-infected with another strain of the CMV virus causing it to be
passed on to her unborn baby.
In most cases where CMV is passed from a mother to baby the virus does not cause any damage to the baby.
If however, a large amount of the virus is spread to the baby it can interfere with the baby’s normal development, resulting in
symptoms and associated disabilities of congenital CMV
What are the signs and symptoms of congenital CMV infection?
Approximately 9 out of 10 babies born with congenital CMV have no symptoms at birth. This is known as an asymptomatic
congenital CMV infection. A small number of these babies may develop some degree of hearing loss over the first few years
of life. Loss of hearing can range from mild to total. The hearing problems can affect just one ear (unilateral hearing loss) or
can cause problems in both ears (bilateral hearing loss). Children with bilateral hearing loss are likely to experience
difficulties with speech and communication as they get older.
One in 10 babies born with congenital CMV do have symptoms at birth. These may include: jaundice – yellow-coloured skin
and yellowing of the whites of the eyes, pneumonia, a rash of small, purplish spots, an enlarged liver and spleen, a low birth
weight, seizures (fits) and small head size. Some babies will develop long-term conditions as a result of the infection. Up to
90 per cent of babies born with this more severe type of congenital CMV infection develop one or more physical or mental
disabilities. These could include hearing loss, visual impairment, blindness, learning difficulties, lack of physical co-ordination
and epilepsy – a condition that affects the brain and causes repeated seizures.
How is congenital CMV infection normally diagnosed?
Your baby will be examined by a doctor after birth for evidence of congenital CMV. If it is thought that a newborn baby may
have congenital CMV, or is at risk of congenital CMV, the virus can usually be detected by examining a sample of their body
fluids, such as their urine or blood.
How is congenital CMV infection normally treated?
Not all cases of congenital CMV need treatment. Antiviral medicines cannot cure a congenital CMV infection but can slow its
progress. The most common antiviral medicine used is ganciclovir. This treatment can cause side effects. If your baby is
confirmed as having congenital CMV and has symptoms of infection, a paediatrician will discuss with you whether or not
your baby might benefit from treatment.
Follow up
If a baby is diagnosed with congenital CMV infection but shows no symptoms their hearing and vision should be checked
regularly. If the child starts to have hearing or vision problems early detection can help their development.
All babies have a hearing check after birth (before the age of 5 weeks), but national guidelines are that all those babies who
are known to have congenital CMV should have a further hearing test at 8 months of age even if their first hearing test is
completely normal. It is important that you tell the person screening your baby’s hearing after birth if your baby is at risk of
congenital CMV so that the necessary follow up can be arranged.
If you are expecting your baby to have a further hearing test at the age of 8 months but have not received an appointment,
please contact the Newborn Hearing Screening Local Manager via Salisbury ¿´Æ¬Èí¼þ Foundation Trust hospital switchboard
who can arrange this for you.
If you have any other questions related to CMV, please speak to your midwife, obstetrician, GP or the paediatrician
examining your baby after delivery
Our staff at Salisbury District Hospital have long been well regarded for the quality of care and treatment they provide for our patients and for their innovation, commitment and professionalism. This has been recognised in a wide range of achievements and it is reflected in our award of ¿´Æ¬Èí¼þ Foundation Trust status. This is afforded to hospitals that provide the highest standards of care.
