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About CMV

Español: Información general

Cytomegalovirus (pronounced sy-toe-MEG-a-low-vy-rus), or CMV, is a common virus that infects people of all ages. In the United States, nearly one in three children are already infected with CMV by age 5 years. Over half of adults by age 40 have been infected with CMV. Once CMV is in a person's body, it stays there for life and can reactivate. A person can also be reinfected with a different strain (variety) of the virus.

Most people infected with CMV show no signs or symptoms. That’s because a healthy person's immune system usually keeps the virus from causing illness. However, CMV infection can cause serious health problems for people with weakened immune systems, as well as babies infected with the virus before they are born (congenital CMV).

Pregnant women at a class

Signs & Symptoms

Most people with CMV infection have no symptoms and aren’t aware that they have been infected. In some cases, infection in healthy people can cause mild illness that may include

  • Fever,
  • Sore throat,
  • Fatigue, and
  • Swollen glands.

Occasionally, CMV can cause mononucleosis or hepatitis (liver problem).

People with weakened immune systems who get CMV can have more serious symptoms affecting the eyes, lungs, liver, esophagus, stomach, and intestines. Babies born with CMV can have brain, liver, spleen, lung, and growth problems. Hearing loss is the most common health problem in babies born with congenital CMV infection, which may be detected soon after birth or may develop later in childhood.

Transmission and Prevention

People with CMV may shed (pass) the virus in body fluids, such as urine, saliva, blood, tears, semen, and breast milk. CMV is spread from an infected person in the following ways:

  • From direct contact with urine or saliva, especially from babies and young children
  • Through sexual contact
  • From breast milk
  • Through transplanted organs and blood transfusions
  • From mother to child during pregnancy (congenital CMV)

Regular hand washing, particularly after changing diapers, is a commonly recommended step to decrease the spread of infections, and may reduce exposures to CMV.

Healthcare providers should follow standard precautions. For more recommendations in healthcare settings, see the Guide to Infection Prevention for Outpatient Settings.


Blood tests can be used to diagnose CMV infections in people who have symptoms.


Healthy people who are infected with CMV usually do not require medical treatment.

Medications are available to treat CMV infection in people who have weakened immune systems and babies who show symptoms of congenital CMV infection.

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