Cytomegalovirus (or CMV) is a common virus that can infect people of all ages. Just about everyone will be infected sooner or later in their life. Infection with CMV is usually quite harmless, but unborn babies and people with weakened defenses can get sick and/or suffer serious long-term consequences. Because pregnant women can pass on the virus to their (unborn) child, it is important to avoid infection during pregnancy.
How is CMV distributed?
The cytomegalovirus belongs to the herpes viruses such as herpes labialis, herpes zoster (zona),herpes simplex, herpes genitalis (STD), varicella (chikenpox) and Epstein-Barr virus (glandular fever). The CMV virus occurs in our bodily fluids, such as urine, saliva, bowel movements, breast milk, blood, tears, sperm and vaginal fluid. You can become infected with CMV when you come into contact with these bodily fluids.
From person to person, it can therefore be transmitted through personal contact: kissing, sexual contact, or by transferring saliva or urine from an infected person through hands to your own nose or mouth. Toddlers or older children who have CMV can pass the virus on to their mother through their urine or saliva.
Pregnant women are usually infected by intensive contacts with an infected child. Especially in places where small children live/play together intensively (manger, kindergarten classes, homes, …), we see a strong spread of the CMV among children from 1 to 4 years old.
The risk of infection via blood transfusions and organ transplants is very small in developed countries.
CMV can also be passed on to the baby at the time of birth through contact with vaginal fluid or later through breastfeeding. An infection contracted at birth or any time after birth is called an acquired CMV infection. In healthy full-term babies, contracting a CMV infection in this way usually does not cause problems.
CMV is not transmitted by air. So you cannot get CMV by staying in the same room as an infected person, unless you come into contact with this person’s bodily fluids.
Approximately 1/3 of women infected by CMV for the first time during pregnancy pass the virus through the placenta to their unborn child. This is called a congenital CMV infection. Women who were already infected before pregnancy can also pass the virus on to their unborn child, but this is rare.
How does a CMV infection work?
Most children and adults infected with CMV have no symptoms and usually do not even know that they are infected. Others can get a little sick. Symptoms include fever, sore throat, fatigue and swollen glands, a disease very similar to glandular fever.
Even if symptoms appear as a result of a CMV infection, healthy children and adults will always heal and will not suffer long-term consequences. However, unborn babies and people with weakened immune systems may become ill and/or suffer serious long-term consequences.
What health problems does a congenital CMV infection cause in newborns?
Fortunately, most children show no signs of their CMV infection at birth. However, 10-15 % will have problems. Common problems are:
- stunted growth,
- coagulation abnormalities manifested in small red spots under the skin (petechiae) and lung, liver or spleen problems (enlarged liver or spleen, jaundice). These symptoms can go away on their own.
- More serious and permanent problems may also occur: a small head, calcifications in the brain, convulsions, abnormal muscle tension, hearing problems, vision problems
- These children may later show a general developmental delay, both mentally and physically.
- Approximately one in ten of the children who are normal at birth will still develop hearing problems (mild or severe) or vision abnormalities (rare) in the first months of life.
- Learning disabilities and developmental delays can also occur later.
How can you avoid CMV during pregnancy?
Pregnant women should take the necessary precautions when contacting young children. A child who is infected at a young age may not show any symptoms but can spread the virus. Especially young mothers, who already have 1 or more young children in the house, will have to be extra careful. Especially contact with saliva and urine of young children should be avoided as much as possible. You can never 100 % avoid getting CMV during pregnancy, but you can take a number of precautions that reduce the risk of spreading CMV:
- Wash hands often with soap and water, especially after diaper change or contact with saliva and nasal secretions.
- Do not wear rings, bracelets or timepieces. This makes good hand hygiene more difficult. Germs settle in and under jewels.
- Do not give kisses on the mouth or cheek to children under 5 to 6 years of age. You can give them a kiss on the forehead or a big hug.
- Do not eat from the same plate or drink from the same glass as young children, nor share their eating utensils (spoons, forks). If you have professionally intensive contacts with small children (for example, because you work in a daycare), then you need to be extra careful.
- Respect strict hand hygiene when in contact with the children.
The usefulness of antiviral medication or the administration of antibodies during pregnancy is investigated, but is not yet generally accepted. Vaccines to prevent CMV infection are still in the research and developmental stage.
Can you get tested for CMV?
Through laboratory tests you can check whether you have already experienced a CMV infection. It is desirable that this is determined before you become pregnant. However, these tests do not predict whether the baby will have health problems if a CMV infection is detected during pregnancy. In the baby, the diagnosis of congenital CMV infection is made by examination of the urine (saliva or blood are also useful), within the first 2 weeks after birth. When the examination is done after the first 2 weeks of life, finding the virus can also indicate an infection, caught during or after birth.
For newborn babies (under 1 month) with a high risk of hearing problems, there is a drug treatment. However, there are a number of possible side effects in the short and long term. Therefore, it is not simply offered to every baby with congenital CMV infection. The (pediatric) doctor will discuss with you whether your baby is eligible for this treatment.
Follow-up of babies with congenital CMV
For babies with proven congenital CMV infection, a number of examinations are planned after birth in a reference center: a blood test, MRI scan, ultrasound of the brain, a hearing test and an eye examination. Most children with congenital CMV infection (approximately 85-90%) do not show any abnormalities at birth. A small number (10-15%) still has mild to severe, possibly progressive hearing problems or (rather rare) vision abnormalities in the first months of life up to -years.
Even after the first examinations, the child is therefore still closely monitored, until the age of 6 years.