Cytomegalovirus (CMV)
Cytomegalovirus is a relative of the herpes viruses, and most people have met it by the time they are grown up.
On this page
Medicines commonly prescribed for Cytomegalovirus (CMV)
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: TABLET, 450 mgActive substance: valganciclovirManufacturer: Teva Pharma S.L.U.Prescription requiredDosage form: INJECTABLE PERFUSION, 500 mgActive substance: ganciclovirManufacturer: Hikma Farmaceutica (Portugal) S.A.Prescription requiredDosage form: TABLET, 450 mgActive substance: valganciclovirManufacturer: Cipla EuropePrescription required
Cytomegalovirus is a relative of the herpes viruses, and most people have met it by the time they are grown up. Catching it usually goes unnoticed, and afterwards the virus stays for good: it sleeps inside cells and gives nothing away for as long as the immune system keeps an eye on it. For a healthy person that arrangement changes nothing, and there is no reason to go looking for CMV. But there are two situations in which it stops being harmless: pregnancy, and an immune system that is seriously weakened. Those two are the reason to know how this virus behaves.
What a first meeting with the virus looks like
Most often it looks like nothing at all. In a minority of people the first infection resembles a cold that will not finish:
- a temperature that hangs on for a week or two with nothing much to explain it;
- heavy tiredness that sleep does not fix;
- aching muscles and joints;
- swollen glands in the neck;
- a moderately sore throat;
- nausea, no appetite, sometimes a fine rash.
Things settle by themselves within two to four weeks, though the tiredness outlasts the rest of the complaints. Blood tests taken during those weeks often show raised liver readings; they also come back to normal without treatment.
By symptoms alone CMV cannot be told apart from the glandular fever caused by the Epstein-Barr virus; only a blood test settles it. For a healthy adult the distinction changes nothing, since either way it comes down to rest and fluids. It starts to matter when there is a pregnancy involved, or an immune system weakened by illness or by medicines.
How the virus passes from person to person
Only through close contact, in body fluids: the virus is present in saliva, urine, blood, breast milk, semen and vaginal fluid. The routes are these:
- from a small child — a kiss on the mouth, a shared spoon, hands not washed after a nappy change;
- through sex;
- in blood during a transfusion, and with a transplanted organ or bone marrow;
- from mother to baby: across the placenta, during birth, and in breast milk.
For adults the main source is children in their first three years. Once a child has had the infection, it keeps shedding the virus in saliva and urine for many months more, looking perfectly well the whole time. That is why the people who meet CMV most often are parents of toddlers, nursery staff and those who work on children's wards.
Ordinary everyday contact — a handshake, a conversation, sharing a room — does not pass the virus on. A child found to have CMV needs neither isolating nor keeping away from other children: the only thing that makes any difference is hand and crockery hygiene around them.
Pregnancy, and a baby born with the virus
The riskiest situation is a woman meeting the virus for the first time while already pregnant, particularly in the first half of the pregnancy: that is when the chance of passing it to the baby is highest and the consequences are heaviest. If the virus had been in the body for years, the risk drops considerably, but it does not reach zero — it can still be passed on if the virus reactivates, or if a different strain is caught.
Even when the virus has reached the baby, most children come through it well. All the same, congenital CMV remains the commonest infection present at birth and the leading non-inherited cause of hearing loss in children. What is visible straight after delivery:
- tiny bleeds into the skin, like a scatter of dark specks;
- jaundice, an enlarged liver and spleen;
- low birth weight;
- a head circumference smaller than expected;
- seizures, floppiness, poor feeding;
- hearing loss in one ear or both;
- changes at the back of the eye picked up by an eye specialist.
The point that gets missed most often: most babies with congenital CMV have nothing wrong with them at birth, and the hearing worsens later — during the first or second year, sometimes at preschool age — and it does so gradually. A single newborn hearing screen guarantees nothing here. That is why, once the diagnosis is confirmed, hearing is rechecked on the schedule the doctor sets, and this goes on for several years. A loss caught in time means a hearing aid fitted in time and speech that develops normally; a loss that is missed turns into a delay that then takes years to make up.
A weakened immune system: where the virus really does harm
This means people who have had an organ or bone marrow transplant, those receiving chemotherapy or taking medicines that suppress immunity over a long period, and people with HIV whose count of protective cells is low. In them a virus that slept for years can wake up and damage organs. Signs that call for contacting the doctor the same day:
- floating specks, flashes, a dark patch or the feeling of a curtain across the eye, vision losing its sharpness — this is how inflammation of the retina begins, and without prompt treatment the eye loses its sight for good; there is usually no pain at all;
- diarrhoea that goes on, blood in the stool, abdominal pain, weight loss;
- pain or a sense of obstruction on swallowing;
- a dry cough and breathlessness that keeps building;
- confusion, seizures, weakness in the legs;
- a prolonged temperature with no clear cause while blood counts are falling.
The difference between calling straight away and putting up with it for a week is measured here in eyesight kept and organs left intact. For that reason transplant patients are tested for the virus in the blood at regular intervals, and treatment is started before any complaints appear, as soon as the amount is seen to rise.
What the tests actually show
There are two different approaches, and they should not be muddled up.
- Class G antibodies say only that a meeting with the virus happened at some point. A large share of adults have them, and on their own they are neither an illness nor a reason for treatment.
- Class M antibodies point to a recent infection, but they persist for a long time and give false alarms, so nothing is decided on them alone. To work out when exactly the infection happened — which matters in pregnancy — a further test is added that measures how strongly the antibodies bind to the virus.
- Finding the virus itself by PCR in blood, urine or another sample shows that it is active here and now. This is the main test in people whose immunity is weakened.
The newborn is a case of its own. Congenital infection is confirmed by finding the virus in urine or saliva, and it has to be done in the first weeks of life: later on the test can no longer separate an infection acquired before birth from one picked up afterwards. The window closes quickly, and what is missed is hard to recover later. If the virus is found in a pregnant woman, the baby's condition is assessed by ultrasound and, where needed, the amniotic fluid is examined.
What treatment can do
A healthy person with an ordinary course needs no treatment, and there is no medicine that drives the virus out of the body for good. All that current treatment can do is hold down the activity of the virus in the places where it causes harm.
- Newborns with signs of congenital infection are given an antiviral by mouth for a course of several months, starting in the first weeks of life; this improves hearing and development. Blood tests have to be checked regularly, because these medicines suppress the production of blood cells.
- People with weakened immunity are given antivirals and, where it is possible, the treatment that suppresses immunity is eased as well. If the retina is inflamed, treatment starts urgently and together with an eye specialist.
- For pregnancy the picture has changed in recent years: in a number of countries, after a first infection is confirmed early on, an antiviral is offered to lower the chance of the virus reaching the baby. The decision is made together with a specialist in infections in pregnancy.
There is still no vaccine against cytomegalovirus: work is under way, but as of today none is licensed. Which means that all the protection during pregnancy rests on simple everyday things.
What genuinely lowers the risk in pregnancy
The measures look disappointingly plain, but they are exactly the ones that work, because they go straight at the main source — the saliva and urine of small children.
- Wash your hands with soap after changing a nappy, feeding, wiping a nose, playing on the floor — not in passing, but properly.
- Kiss the child on the forehead, the top of the head or the cheek, not on the mouth.
- Do not finish off their food, drink from their cup, taste food with their spoon, or put their dummy in your mouth to clean it.
- Wash toys, teethers and the surfaces that saliva lands on regularly.
- Use a condom with a new partner — the sexual route is real for CMV too.
Keeping this up around the clock is impossible, and it is not needed either: everyday care is enough, especially if there is a child under three at home or you work with babies. There is no need to give up hugs or looking after an older child — that is not the route the virus travels. And separately: breastfeeding is not stopped because the mother has CMV, and it does a full-term baby no harm; the exception is very premature babies, and there the doctor decides.
Online consultation
Remotely you can work through what causes the most worry: what a result on a test form actually means. The doctor explains the difference between an old infection and a recent one, says whether confirmatory tests are needed and how soon to have them, and helps you see whether the raised risk in pregnancy, or when planning one, applies to you. With the parents of a child with congenital CMV it is a good way to go over how to set up the follow-up of hearing and vision and what changes to watch for between appointments. Eye, gut or chest signs in someone with weakened immunity are not handled through a screen: with those you need to be seen in person, the same day.
This material is for information only and does not replace medical advice.
Consult with a doctor about Cytomegalovirus (CMV)
Discuss your symptoms and possible next steps with a doctor online.
Online doctors for Cytomegalovirus (CMV)
Discuss your symptoms and possible next steps for Cytomegalovirus (CMV) with a doctor online.
