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Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a common virus that can affect anyone. Almost 1 in 3 children have CMV by age 5.

Some people get sick when they are first infected, but many do not. CMV stays in your body for life. It usually does not cause problems. But, if your immune system is weak, the virus can become active and cause illness. Bone marrow transplant patients have a high risk of problems due to CMV.

Doctors may use blood tests to monitor CMV.

Symptoms of CMV

Most people with CMV have no signs or symptoms and do not know they have the virus. Some people with CMV may have:

  • Fever
  • Sore throat
  • Fatigue or loss of energy
  • Swollen glands in the neck

CMV sometimes affects the eyes, liver, stomach, or lungs. These problems are more likely to happen in patients with weak immune systems.

Less common symptoms of CMV include:

  • Blurry vision
  • Diarrhea
  • Belly pain
  • Trouble breathing
  • Cough

How to test for CMV

Doctors can do a blood test to look for the virus. Since most people with CMV don't have symptoms, doctors can only find it by doing a test.

Treatment for CMV

Your child's doctor may prescribe medicines called antivirals to fight the virus. Medicines used to treat CMV include:

  • Ganciclovir
  • Alganciclovir
  • Foscarnet

Your child’s care team will decide what treatments are needed.

Illustration of washing hands with soap and water.

Washing your hands with soap and water helps flush the virus down the drain.

How CMV spreads

CMV spreads through body fluids such as urine or saliva (spit). It can also spread through blood transfusion or organ transplant.

CMV is not highly contagious. It does not spread as easily as some other germs. But it is quite common and can spread through close contact. CMV is common in areas where young children are present, such as homes and childcare centers.

Your child does not need to isolate if a blood test shows that CMV is present. To help avoid spreading CMV and other illnesses:

  • Wash your hands well and often.
  • Wear gloves when you change diapers or touch body fluids such as urine, vomit, or saliva.

CMV and bone marrow transplant

Transplant patients are at higher risk for illness due to CMV infection. CMV may become active after a bone marrow transplant and cause health problems that affect recovery. For example, CMV can affect the lungs, stomach, eyes, and liver.

A healthy immune system usually keeps CMV from causing problems. During bone marrow transplant, a patient gets immunosuppressive therapy. This treatment weakens the immune system. It involves high doses of chemotherapy and other medicines to keep the body from rejecting a transplant. During this time, CMV may cause sickness.

  • The patient and donor are tested for CMV before a bone marrow transplant. This helps the care team know the patient’s risk of getting sick during transplant. Patients who already have CMV have a higher risk of getting sick from CMV.
  • After the bone marrow transplant, staff use lab tests to monitor CMV. Doctors test for CMV at least once a week through day 100 or longer after transplant. This blood test looks for the exact amount of virus in the blood. Your doctor may suggest treatment based on the blood test’s results.


  • Cytomegalovirus (CMV) is a common virus.
  • CMV stays in your body for life, but it usually does not cause problems.
  • A patient with a weak immune system from a bone marrow transplant is more likely to get sick from CMV.
  • Your child's doctor may do blood tests to monitor CMV.

Reviewed: July 2022