[Skip to Content]

Cytomegalovirus (CMV)

Medically reviewed by: Cedric V. Pritchett, MD, MPH

What Is Cytomegalovirus?

Cytomegalovirus (CMV) is closely related to the viruses that cause chickenpox and mononucleosis (mono). CMV infections are very common, and most of us will probably have one in our lifetimes.

Most people infected with CMV have no symptoms or only mild symptoms. In healthy kids, a CMV infection is rarely serious. Any symptoms it does cause usually are mild and temporary. But cytomegalovirus (site-uh-meg-uh-low-VY-rus) can cause problems for an unborn child whose mother has the virus and for people with weak immune systems.

What Are the Signs & Symptoms of CMV?

The symptoms of a CMV infection vary. Most babies infected before birth usually show no symptoms after delivery. But some may:

  • be born early (prematurely)
  • be a small size or have a low birth weight
  • have jaundice
  • have an enlarged liver and spleen
  • have a small head (microcephaly)
  • have feeding problems

These babies are also at risk for hearing, vision, neurological, and developmental problems. Even babies without clear symptoms are at risk for congenital hearing loss. CMV is the most common cause of non-genetic hearing loss at birth.

CMV infections that happen in kids after the newborn period usually don't cause serious illness. But some kids may develop pneumonia, hepatitis (inflammation of the liver), or a rash.

Older kids and teens who are infected may have mono-like symptoms, including tiredness, muscle aches, headache, fever, and an enlarged liver and spleen. These symptoms tend to be mild and usually last only 2–3 weeks.

CMV can cause serious infections in people who have had organ transplants or those with weak immune systems. In someone with AIDS or HIV, CMV infection may affect the lungs, nervous system, gastrointestinal tract, and the eyes, sometimes causing blindness.

How Long Does CMV Infection Last?

CMV does not always cause symptoms. If it does, how long they last can vary. This depends on how the infection happens and the age and general health of the person who has it.

For example, a serious CMV infection before birth may cause lifelong developmental problems. But cytomegalovirus infection in teens may last only 2 to 3 weeks and cause no lasting problems.

After a person has the infection, the virus stays in the body, lying dormant (not active). It can become "reactivated" (come back) weeks or years later. In people with very weak immune systems (such as people who have AIDS or who get chemotherapy), the reactivated virus may cause serious illness. Most people, though, will not get symptoms of CMV again.

Is CMV Contagious?

Yes. CMV can spread in a number of different ways. Anyone who has had a CMV infection, even without any symptoms, can spread the virus to others. But this mostly happens through close contact because the virus spreads through saliva (spit), breast milk, vaginal fluids, semen, urine (pee), and stool (poop).

In the United States, about 0.5%–1% of infants are infected with the virus before birth. This happens because the mother had a first-time CMV infection or a reactivated infection during her pregnancy. An infected mother can pass the virus to her child before, during, or after birth.

The virus also can:

  • spread in childcare centers or preschool settings, passing among kids on contaminated toys or by direct contact
  • be in blood products and donated organs, causing infection after a blood transfusion or organ transplant. But preventive therapies are done for organ-transplant patients, and blood banks have procedures to help to prevent CMV from passing in blood products.

How Is CMV Diagnosed?

Doctors diagnose a cytomegalovirus infection by testing fluid or a tissue sample from a person's throat, pee, blood, or other body tissues or fluid. Blood tests also can look for antibodies that are part of the immune system's response to a CMV infection. Sometimes other tests are used.

How Is CMV Treated?

There's no specific treatment recommended for otherwise healthy kids with CMV infection.

But an infection can be serious and even life-threatening for:

  • newborns infected before birth
  • organ-transplant patients
  • those being treated for cancer
  • kids with severe immune disorders such as AIDS

These people may be treated with intravenous (IV) antiviral medicine, usually in a hospital. Oral antiviral medicine also might be used at home after the infection is under control. These antiviral medicines can have serious side effects, so doctors use them with caution, especially in children.

In bone marrow transplant patients, the antiviral drug ganciclovir given in an IV can help fight CMV infections. In rare cases, CMV-immune globulin might be given before someone gets an organ transplant.

Can CMV Infection Be Prevented?

Currently, there's no vaccine to prevent cytomegalovirus infection. Washing hands well and often can help reduce the risk of infection. This is especially important for:

  • pregnant women and those who might become pregnant
  • childcare workers
  • anyone who has close contact with children

It's also a good idea to not share eating utensils with young kids and to avoid close contact with anyone who has the infection.

A mom who has a CMV infection shouldn't stop breastfeeding her baby. The benefits of breastfeeding are believed to outweigh the risks of passing CMV to the baby, who is unlikely to develop any symptoms if infected.

Medically reviewed by: Cedric V. Pritchett, MD, MPH
Date reviewed: May 2022