Cytomegalovirus Infection

by Dr. Mas Suhaila Isa

Cytomegalovirus (CMV) is a common childhood viral infection. It is a virus of the herpes virus family. 

 

50% of people would have been infected by the time they are young adults and over 90% by 40 years of age.  Once you are infected, the virus whilst still alive, remains dormant (inactive) within your body for life. Once you recover after the initial infection, it is rare for you to get symptoms after that unless your immune system is weakened.

 

Symptoms of CMV infection 

Most children and adults who are healthy and get infected with CMV have no symptoms and may not be aware thatthey have been infected. 

 

Some may develop symptoms similar to glandular fever :

  • Tiredness

  • Sore throat

  • Swollen neck glands (lymph nodes)

  • Fever

 

People with weakened immune system may develop infection of several organ systems and complications and death.

 

How is it spread?

Humans are the only source of the virus. CMV is spread through:

  • close contact with a person excreting the virus in their saliva, nasal mucous, urine or other body fluid

  • handling children’s toys that have saliva or mucous on them, or handling contaminated items like dirty tissues or soiled nappies then touching the eyes, nose or mouth without first washing hands

  • from mother to her unborn child due to maternal infection or virus reactivation during pregnancy

  • breast milk of an infected woman who is breast feeding

  • sexual contact.

 

Congenital CMV

This happens when the virus is passed from a pregnant woman who is infected to her developing baby across the placenta.

 

Who is at risk?

A woman who is newly infected while pregnant carries a risk that her unborn baby may also become infected. The highest risk occurs when a woman is infected for the first time during the first half of pregnancy. In some cases, the virus may reactivate while a woman is pregnant, but reactivation poses a much smaller risk of transmission and harm to the unborn baby.

 

Signs and Symptoms

Some babies with congenital CMV infection have signs at birth which include:

  • Rash

  • Jaundice (yellowing of the skin or whites of the eyes)

  • Microcephaly (small head)

  • Low birth weight

  • Hepatosplenomegaly (enlarged liver and spleen)

  • Seizures

  • Retinitis (damaged eye retina)

 

They may also develop long-term health problems such as hearing loss, poor head size growth, developmental and motor delay, vision loss and seizures.

 

Some babies with congenital CMV infection who appear healthy at birth can develop hearing or vision loss over time. Hence, babies known to be infected should have their hearing, vision and development assessed regularly. 

 

Can congenital CMV be prevented?

Unfortunately, there is no current available licensed vaccine against CMV.

Pregnant women can take the following measures to lessen their risk of exposure to CMV :

  • Practice good hand hygiene. Wash hands often with soap and running water and dry them thoroughly  especially after close contact with young children, changing nappies, blowing noses, feeding a young child, and handling children's toys and pacifiers.

  • do not share food, drinks, eating utensils or toothbrushes with young children.

  • avoid contact with saliva when kissing a child.

  • use simple detergent and water to clean toys and other surfaces that have come into contact with children's urine, mucous or saliva. 

 

People who have frequent contact with young children eg preschool or childcare workers may be at greater risk of CMV infection because young children are a common source of CMV. By the age of five years, one in three children has been infected with CMV, but usually does not have symptoms. The saliva and urine of children with CMV have high amounts of the virus and can remain present for months after they were infected.

How is congenital CMV diagnosed?

Once a person has been infected with CMV, he/she will develop antibodies in their blood and this will indicate if infection has occurred recently or in the past. These antibodies will they stay in the body for the rest of his/her life. There are also tests that detect the virus particle itself, and these can also be used to determine a recent and active infection.

Testing for CMV is not routinely recommended for all women during pregnancy or for newborn babies. 

Infants born to mothers diagnosed with a primary CMV infection during pregnancy should be tested for congenital CMV infection. Congenital CMV infection can be diagnosed by testing a newborn baby’s saliva, urine, and blood. These tests should be performed within two to three weeks after the baby is born to be able to confirm a diagnosis of congenital CMV infection.

 

Can congenital CMV be treated?

Pregnant women diagnosed with primary (first) CMV infection should be referred for specialist  counselling in order to receive the latest information about the risks and benefits of the available treatments, which are currently experimental and have not shown convincing benefit to prevent passing the infection to the unborn baby.

 

For babies with signs of congenital CMV infection at birth, antiviral medications, primarily valganciclovir, may improve hearing and developmental outcomes. Valganciclovir can have serious side effects and has only been studied in babies with signs of congenital CMV infection. There is limited information on the effectiveness of valganciclovir to treat babies with hearing loss alone. This should be discussed with a specialist paediatrician.

 

References :

1.  Centers for Disease Control and Prevention, USA

2.  Red book, 2018 edition

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