Cytomegalovirus (CMV) Infection

Cytomegalovirus (sye-tuh-MEH-guh-lo-vy-rus), or CMV infection is very common and usually causes no symptoms. It poses little risk for healthy people, but it can lead to serious illness in people with weak immune systems.


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Epstein-Barr virus

Herpes simplex virus


Immune deficiencies


Varicella zoster virus

What Is CMV?

CMV is part of the herpesvirus (her-peez-VY-rus) family, which also includes the viruses that cause herpes * , chicken pox, and mononucleosis * . As with other members of the herpesvirus family, once CMV enters a person's body, it remains there for life. CMV infection can bring about flulike symptoms when a person is first infected, but many people have no symptoms at all. The virus usually becomes dormant after it enters the body, meaning that it remains "hidden" and does not cause symptoms of illness. The virus can emerge at a later time, however, and produce illness in people with weakened immune systems, such as people who have cancer or AIDS or those who have received organ or bone marrow * transplants. CMV is a risk for pregnant women because of the danger that it can be transmitted to their babies. The disease is the leading cause of mental retardation and hearing defects in newborns in the United States as a result of congenital (kon-JEH-nih-tul) infection, that is, infection that is present at birth.

How Is CMV Spread?

CMV is contagious and can spread through bodily fluids, including blood, saliva, semen, breast milk, tears, and urine. The virus can be transmitted by sexual contact, by close person-to-person contact, or from mother to baby during pregnancy or birth or while breast-feeding. It often spreads among children in day care or preschool or among family members. In the United States, as many as three of every five adults have been infected with CMV by the time they reach age 40. CMV infects people all over the world and is even more widespread in developing countries and those with poor living conditions.

What Are the Symptoms of CMV?

Most people who have been infected with CMV never show symptoms. In some people, the virus causes mild symptoms that mimic the flu or infectious mononucleosis, such as fever, chills, body aches, headache, swollen lymph nodes * , sore throat, and fatigue. Newborns who contract CMV infection in the womb may be born with jaundice * , microcephaly * , signs of brain damage, and a serious inflammation of the eyes known as retinitis * . Others seem healthy when they are born but later have growth problems and signs of hearing loss or mental retardation.

* herpes (HER-peez) is a viral infection that can produce painful, recurring skin blisters around the mouth or the genitals, and sometimes symptoms of infection elsewhere in the body.

* mononucleosis (mah-no-nu-klee-O-sis) is an infectious illness caused by a virus that often leads to fever, sore throat, swollen glands, and tiredness.

* bone marrow is the soft tissue inside bones where blood cells are made.

* lymph (LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

* jaundice (JON-dis) is a yellowing of the skin, and sometimes the whites of the eyes, caused by a buildup in the body of bilirubin, a chemical produced by the liver. An increase in bilirubin may indicate disease of the liver.

* microcephaly (my-kro-SEH-fah-lee) is the condition of having an abnormally small head, which typically results from having an underdeveloped or malformed brain.

* retinitis (reh-tin-EYE-tis) is inflammation of the retina, the nerve-rich membrane at the back of the eye on which visual images form.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses,

* DNA, or deoxyribonucleic acid (dee-OX-see-ry-bo-nyoo-klay-ik AH-sid). is the specialized chemical substance that contains the genetic code necessary to build and maintain the structures and functions of living organisms.

How Are CMV Infections Diagnosed and Treated?

Most cases of CMV infection are never diagnosed because they produce few or no symptoms. When doctors do suspect CMV, they often base the diagnosis on symptoms, physical examination, and blood tests for antibodies * to the virus. They also will rule out other diseases that cause similar symptoms, such as infectious mononucleosis caused by the Epstein-Barr virus. Sometimes blood tests show evidence of past infection with CMV but do not indicate active infection. A test known as the polymerase (pah-LIM-er-ace) chain reaction, or PCR, can test specifically for active CMV infection by finding traces of DNA * from the virus in body fluids. People with healthy immune systems who contract CMV infection usually do not require medical treatment. When people with weakened immune systems develop CMV infection, doctors often prescribe medication made to fight viruses. These antiviral medicines may need to be given by injection, and patients sometimes have to take them for months or even years. Symptoms of initial CMV infection usually last 2 to 3 weeks in healthy people. After that, the virus remains in the body for life. Flare-ups of illness from CMV in healthy people are rare and typically occur when the immune system has been stressed by fighting another illness.

Once inside the human body, the cytomegalovirus can invade many organs and systems. In this microscopic image, viral components are visible in the lining of the stomach. If the virus becomes active in the stomach, it can produce ulcers. Visual Unlimited
Once inside the human body, the cytomegalovirus can invade many organs and systems. In this microscopic image, viral components are visible in the lining of the stomach. If the virus becomes active in the stomach, it can produce ulcers.
Visual Unlimited

What Are the Complications of CMV Infection?

CMV infection can cause more severe illness in people with weakened immune systems, such as pneumonia * and retinitis. If it is untreated, retinitis can lead to blindness. CMV also can cause severe inflammation of the esophagus and colon, leading to difficulty in swallowing, long-lasting diarrhea, and weight loss. It also can affect the brain or nerves. Infants born with CMV infection may have jaundice, poor growth, problems with vision and hearing, and other disabilities, including slow development and mental retardation.

How Is CMV Infection Prevented?

The best way to help prevent the spread of CMV is to wash the hands regularly, especially after changing diapers or touching bodily fluids. Doctors advise women who are pregnant and people who work in child care to be particularly careful. Patients scheduled to have organ or bone marrow transplants typically receive medication before the operation to prevent CMV disease from developing, as the transplant process weakens their immune systems.

* pneumonia (nu-MO-nyah) is inflammation of the lung.

See also
AIDS and HIV Infection
Congenital Infections
Herpes Simplex Virus Infections
Immune Deficiencies
Laboratory Tests
Mononucleosis, Infectious



U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC offers information about cytomegalovirus infection at its website.
Telephone 800-311-3435

U.S. National Institute of Allergy and Infectious Diseases (NIAID), Building 31, Room 7A-50, 31 Center Drive MSC 2520, Bethesda, MD 20892-2520. The NIAID, part of the National Institutes of Health, posts fact sheets on cytomegalovirus at its website.
Telephone 301-496-5717

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