Cytomegalovirus (CMV)

Cytomegalovirus (CMV)

Infection with cytomegalovirus (CMV), a member of the herpes virus family, is very common. Between 50% and 85% of people in the United States have had a CMV infection by the time they are 40 years old, according to the Centers for Disease Control and Prevention (CDC).

Children typically become infected with the virus in early childhood, especially those in child-care and preschool settings. CMV infections are rarely serious in otherwise healthy children and adults; they usually cause only mild symptoms, if any. When symptoms do appear, they are similar to those seen in mononucleosis ("mono") and only last a few weeks.

CMV is mainly a problem for certain high-risk groups, including:

unborn babies whose mothers become infected with CMV during the pregnancy
children or adults whose immune systems have been weakened by disease or drug treatment, such as organ transplant recipients or people infected with HIV
Once a person has had a CMV infection, the virus usually lies dormant (or inactive) in the body, but it can be reactivated. The virus is more likely to be reactivated – and cause serious illness – in people who have weakened immune systems due to illness.

Symptoms of CMV Infections
The symptoms of a CMV infection vary depending upon the age and health of the person who is infected, and how the infection occurred.

Infants who are infected before birth usually show no symptoms of a CMV infection after they are born, although some of these infants can develop hearing, vision, neurologic, and developmental problems over time. In a few cases, there are symptoms at birth, which can include premature delivery, being small for gestational age, jaundice, enlarged liver and spleen, microcephaly (small head), seizures, rash, and feeding difficulties. These infants are also at high risk for developing hearing, vision, neurologic, and developmental problems.

Newborns can also contract CMV infection during or soon after birth by passing through the birth canal of an infected mother, consuming breast milk from a mother with the virus, or receiving a transfusion of blood donated by a person infected with CMV. Most of these infants show no symptoms of CMV infection, however, a few may develop pneumonia or other symptoms. Premature and ill full-term infants who are infected soon after birth are also at risk for neurologic and developmental problems over time.

Although CMV infections that occur in children after the newborn period usually don’t cause significant illness, some infants and young children may develop pneumonia, hepatitis (inflammation of the liver), or a rash.

Older children and teens who become infected with the virus may have mononucleosis-like symptoms, including fatigue, muscle aches, headache, fever and enlarged liver and spleen. These symptoms are generally mild, and usually last only 2-3 weeks.

In people who have received organ transplants, or in people whose immune systems are weakened, CMV can cause serious infections. In people who have AIDS or HIV, CMV infection may involve the lungs, nervous system, gastrointestinal tract, and the eye, sometimes causing blindness.

How Long Do The Symptoms Last?
If symptoms of CMV do appear, how long they last varies depending on how the infection occurs and the age and general health of the patient. For example, serious CMV infections before birth may cause developmental problems that affect a child for a lifetime. On the other hand, infection in teens may last only 2 to 3 weeks and cause no lasting problems.

How Does CMV Spread?
In the United States, about 1% of infants are infected with CMV before birth - usually only if the mother has developed a first-time CMV infection during pregnancy. As discussed above, an infected mother can pass the virus to her child before, during, or after birth.

Any person with a new or past CMV infection can transmit the virus to others, even if he or she isn’t showing any symptoms. But transmission usually requires fairly close contact; the virus can be spread through saliva, breast milk, vaginal fluids, semen, urine, and stool. The virus can also be present in blood products and donated organs, causing infection after a blood transfusion or organ transplantation.

Among kids, the virus is commonly spread in child-care centers or preschool settings, where it passes easily through indirect contact, especially though contaminated toys. Children who are infected may then spread the infection to their families.

Diagnosing and Treating CMV
In serious cases of CMV infection, doctors can make the diagnosis by detecting the virus in a cultured sample taken from a sick person's throat, urine, blood, or other body tissues or fluid. Blood is also drawn at different time intervals to measure levels of certain antibodies. These antibodies are part of the immune system's response to a CMV infection, and they can signal that an active CMV infection exists. Special viral DNA-detecting tests are also sometimes used to diagnosis CMV infection.

Currently, there is no specific treatment available or recommended for otherwise healthy people with CMV infection.

In patients where CMV infection can be life-threatening (newborn infants, organ-transplant patients, and people being treated for cancer or who have immune disorders such as AIDS), serious CMV infections may be treated with intravenous (IV) antiviral medication, usually in a hospital. Oral antiviral medication may also be used at home once the infection is under control and the patient is stable. Because these antiviral medicines may have serious side effects, doctors use them with great caution, especially in children.

In bone-marrow transplant patients, CMV-immune globulin (CMV-IVIG) and the anti-viral drug ganciclovir given intravenously can be used to fight CMV infections.

Preventing CMV Infections
Currently, there is no vaccine to prevent CMV infection. For those who have close contact with children, especially pregnant women or women who might become pregnant, handwashing is effective at reducing the risk of infection from exposure to CMV. Not sharing eating utensils with young children and avoiding kissing or intimate contact with CMV-positive individuals is also important.

A mother who has CMV infection shouldn’t stop breastfeeding, as the benefits of breastfeeding are believed to outweigh the risks of passing CMV to the infant, and the infant is unlikely to develop any symptoms if infected.

For organ-transplant patients who are at risk of getting CMV from a transplanted organ, preventive therapies are available. Blood banks have certain screening and processing procedures that help to prevent CMV from being passed in blood products.

When to Call Your Child's Doctor
Call your child's doctor if your child has any of these or other “mono-like” symptoms:

fever that lasts for several days
unusual or extreme tiredness
muscle aches
headache
If you are pregnant, ask your doctor about your risk for CMV infection and about how you can help protect your developing baby from CMV infection before birth.

If your child has had an organ transplant or has HIV, AIDS, cancer, or any disease that affects the immune system, he or she is at special risk of CMV infection. Keep in close contact with your child's doctor about signs and symptoms to watch for.

Reviewed by: Steven A. Dowshen, MD
Date reviewed: April 2006




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