Cytomegalovirus (CMV) is a common and widespread virus. Most infections happen during childhood, and the majority of adults carry the virus by the time they’re 40. But most people infected with CMV don’t even know it.
So why worry? In most cases there’s no need to. Infected people carry the virus for life, and usually it remains dormant — rarely causing symptoms throughout their lifetime.
But for some people, generally those with compromised immune systems, there’s a greater risk of becoming very ill or of developing permanent disabilities from CMV. If you’re pregnant and have never been exposed to the virus but develop an active infection, the virus can also cause permanent disabilities in your unborn baby.
There’s no cure for CMV, but some antiviral drugs can help people with compromised immune systems and newborns, though side effects may occur. Researchers are studying new medications and vaccines to treat and prevent CMV.
Most people infected with CMV but who are otherwise healthy exhibit few if any symptoms. In fact, many people never know they have the virus. The type and seriousness of a CMV infection usually depends on your overall health.
When first infected (primary CMV), some adults may have symptoms similar to mononucleosis. Signs and symptoms of primary CMV include:
- Night sweats
- Prolonged fever
- Swollen glands or sore throat, or both
- Loss of appetite or weight loss, or both
- Muscle aches or joint pain or stiffness
- General feeling of illness, discomfort or uneasiness
When the cause of these symptoms is CMV, you still may not know you have the virus because the symptoms are usually mild and short-lived and are also common in other illnesses.
Signs and symptoms in adults with compromised immunity
In adults who have a compromised immune system (immunocompromised adults), CMV can attack specific organs. This can result in signs and symptoms in the:
- Eyes, including visual impairment and blindness
- Lungs, including pneumonia with low blood oxygen (hypoxemia)
- Gastrointestinal system, including diarrhea and ulcerations with bleeding
- Liver, including hepatitis which is most often characterized by a prolonged, unexplained fever
- Brain, including inflammation of the brain (encephalitis) with behavioral changes, seizures and coma
Symptoms in children
If you’re pregnant and become infected with CMV for the first time, you may not experience serious illness, but it’s possible to pass CMV to the fetus through the placenta. In most cases newborns don’t exhibit evidence of infection at birth. Only about three newborns in 100 who are infected with CMV during pregnancy will be ill at birth. Of this 3 percent, most will be very ill and have a significant risk of permanent disabilities.
Most babies who are infected before they’re born appear healthy at birth, but a fraction of those can develop signs over time — sometimes not for months or years after birth. The most common of these late-occurring signs is hearing loss. A small number may develop vision impairment as well.
Most babies born with CMV (congenital CMV) never have any signs or symptoms.
Immediate signs of CMV in newborns include:
- Yellow skin and eyes (jaundice)
- Purple skin splotches or a rash, or both
- Small size at birth (or low birth weight)
- Enlarged spleen
- Enlarged and poorly functioning liver
Disabilities arising from newborn CMV include:
- Hearing loss
- Eye abnormalities, including central vision loss, scarring of the retina, and swelling and irritation of the eye (uveitis)
- Mental disability
- Attention-deficit/hyperactivity disorder
- Lack of coordination
- Small head
Cytomegalovirus is in the same family of viruses as those that cause chickenpox, herpes simplex and mononucleosis. Similar to other viruses in this family, CMV cycles through periods of dormancy and reactivation. If you’re infected your body sheds the virus in its fluids when the virus reactivates. This is when the virus can be passed to a noninfected person.
Body fluids are the culprit
Infected body fluids that can spread CMV include blood, urine, saliva, breast milk, tears, semen and vaginal fluids. If you’ve been infected with CMV sometime in the past (CMV positive), you usually don’t have the virus in these fluids unless you’re experiencing reactivation. Transmission of the virus doesn’t occur by casual contact but, like HIV and hepatitis B, through exposure to blood and body fluids.
The virus can spread in a number of ways:
- Touching your eyes or the inside of your nose or mouth after coming into contact with the body fluids of an infected person. This is the most common way CMV is spread because it’s absorbed through the mucous membranes.
- Through the breast milk of an infected mother.
- Through organ transplantation or blood transfusions.
- By becoming infected during pregnancy — either for the first time or with recurrent CMV infection — when the virus is passed from mother’s blood to the fetus through the placenta or during birth.
Anyone can become infected with CMV, and healthy children and adults who contract the infection usually have few if any symptoms. However, some babies born with CMV will develop long-term disabilities, so if you’re pregnant and do not have CMV, be especially careful not to become exposed to the virus during pregnancy.
Reactivation of the virus appears to occur randomly. Research has shown that it’s possible that certain stresses result in reactivation, but because symptoms are usually absent this is difficult to determine. There’s no known way to avoid reactivations.
Some groups of children and adults are at greater risk of being severely affected if they contract CMV.
If you’re pregnant and have never had CMV, you have the greatest risk that acquiring the disease could result in an affected child. Should you acquire a primary infection during your pregnancy, your newborn has a 1 percent to 3 percent chance of having the severe form of CMV at birth. If you acquire the disease during pregnancy but your baby is born healthy, there’s still a 10 percent to 15 percent chance that your baby was infected while in the uterus. These babies are at risk of developing problems later with hearing or vision. All babies who acquire CMV infections during pregnancy should have regular vision and hearing tests.
Adults who are immunocompromised may have more severe and longer lasting symptoms from a CMV infection. A variety of conditions can cause your immune system to become weakened:
- Having HIV or AIDS
- Receiving chemotherapy
- Taking anti-rejection drugs after an organ or bone marrow transplant
If you have symptoms of CMV, tests can determine whether you have the disease. Blood tests can indicate special proteins in your blood (antibodies) that are created by your immune system when you have CMV. The virus can also be detected by cultures or by a polymerase chain reaction (PCR) test from blood or other body fluids. Rarely, exposure to CMV is suspected and a blood test during pregnancy can detect infection that causes no symptoms.
Screening and testing for your baby
Testing to determine whether you’ve ever been infected can be important if you’re pregnant. Pregnant women with antibodies have a small chance of a reactivation infecting their unborn child.
When infection is detected during pregnancy, you may wish to consider amniocentesis, in which your doctor obtains and examines a sample of amniotic fluid to determine whether the fetus has the infection. Occasionally the need for such testing arises when abnormalities that may be caused by CMV or other infectious diseases are seen on ultrasound.
If you or your doctor thinks your baby may have been born with CMV (congenital CMV), it’s important that he or she be tested within the first three weeks of birth. If you wait longer, tests won’t be conclusive for congenital CMV because it’s possible your baby could have contracted the infection by nursing or by exposure to siblings or others who may be shedding the virus.
Screening and testing if you’re immunocompromised
Testing for CMV can also be important if you have a condition that weakens your immune system. For example, if you have HIV or AIDS, and even if you don’t have an active CMV infection, the fact that you carry the CMV virus means you’ll need regular monitoring for complications of CMV, such as vision and hearing problems.
In the rare cases in which CMV causes a healthy person to become very sick, the infection may cause the following complications:
- CMV mononucleosis. This syndrome resembles infectious mononucleosis. Infectious, or classic, mononucleosis is caused by a different virus called Epstein-Barr virus (EBV). If you have symptoms that resemble mononucleosis — a sore throat, swollen glands and tonsils, fatigue and nausea — your doctor will test you for the antibody your body makes to fight off EBV. If it’s absent, there’s a good chance CMV is causing your symptoms.
- Intestinal complications. CMV infection in your intestines can result in diarrhea, fever and abdominal pain; inflammation of your colon; and blood in your stool.
- Liver complications. CMV can cause abnormal functioning in your liver and an unexplained fever.
- Nervous system complications. A variety of neurological complications have been reported as a result of CMV infection in the nervous system. These may include inflammation of your brain (encephalitis).
CMV is the most common viral disease in newborns, but there’s no cure. Once you’re infected, the virus usually remains dormant in your body for the rest of your life. Treatment for the virus generally isn’t necessary or recommended for normally healthy children and adults.
Newborns and people with compromised immune systems need treatment when they’re experiencing symptoms of CMV infection. The kind of treatment depends on the symptoms and their severity.
If treatment is needed, it’s most often in the form of antiviral drugs. Antiviral drugs slow down the virus by preventing it from dividing and creating more of itself. However, these drugs don’t cure CMV.
Treatment may also address the specific symptoms of CMV infection. Treatable signs in newborns are:
- Hearing loss
- Retinitis, an inflammation of the light-sensing layer of the eye
Careful hygiene is the best prevention against contracting CMV. Health care workers have the greatest opportunity for exposure but, because of precautions used in the health care setting, their risk is very low. If you are in frequent contact with young children, and especially if you’re pregnant, take these precautions:
- Carefully wash your hands often. Use soap and water for 15 to 20 seconds, especially if you have contact with children or their diapers, drool or other oral secretions. This is especially important if the children attend child care.
- Avoid contact with tears and saliva when you kiss a young child. A hug or a kiss on the head is adequate and may cause no risk. During pregnancy, a kiss on the cheek should be given only on clean skin.
- Avoid drinking out of the same glass. Sharing glasses and kitchen utensils can spread the CMV virus.
- Be careful with disposable items. When disposing of diapers, tissues and other items that have been contaminated with bodily fluids, be careful not to touch your hands to your face until after thoroughly washing your hands.
An experimental vaccine has been developed for women of childbearing age. The vaccine may be useful in reducing the chance that babies born to women who are infected while pregnant will suffer from disabilities. People with compromised immune systems may benefit from taking antiviral medication to prevent CMV disease.