Overview, Causes, & Risk Factors

Cytomegalovirus is a virus that causes different illnesses in different groups of people.

What is going on in the body?

Cytomegalovirus, also known as CMV, is a common infection. Although lifelong, the virus usually remains quiet in the tissues of the body after the initial infection. It can, however, be shed in the mouth, urine, and genital tract, serving as a source of infection for other people. CMV can also cause a second, more severe infection if the immune system becomes weak for any reason.

What are the causes and risks of the disease?

Most people have been infected with CMV by the time they are adults. People with who are at risk for severe disease include:

Symptoms & Signs

What are the signs and symptoms of the disease?

Symptoms primarily depend on the age of the person and the strength of his or her immune system.

CMV may infect a healthy unborn baby while it is still in the womb. Roughly 5% of infants who get CMV this way have serious birth defects. These can include brain damage, growth failure, blindness, and other defects. This problem usually occurs when a pregnant mother gets a CMV infection for the first time during pregnancy.

When CMV happens in early childhood, it usually causes no symptoms at all. This is thought to be the most common form of CMV infection.

During the teenage and young adult years, infection with CMV can cause a syndrome called infectious mononucleosis, or "mono." Mono generally causes symptoms of sore throat, fatigue, fever, and swollen glands. These symptoms can last for weeks or even months. Most people recover without treatment.

CMV can cause serious problems in people with weakened immune systems. This problem is most common in people with AIDS or those taking drugs to suppress the immune system. People with widespread cancer or people who receive an organ transplant are commonly affected. Infection may be due to a first-time infection or, more often, a reactivated infection. People with AIDS often get an infection of the back of the eye, called the retina. This type of infection is called retinitis. This may cause problems with vision. In transplant and cancer patients, CMV usually is the cause of pneumonia or a gastrointestinal infection that causes diarrhea.

Diagnosis & Tests

How is the disease diagnosed?

The virus can be detected in various human tissues and even grown from these tissues in the laboratory. Because most people have CMV in their bodies, the significance of finding CMV depends on the situation. For example, CMV found in a baby in the first 2 weeks of life usually means the baby was infected inside the womb. A positive CMV result at any other time in life could mean a new infection or a reactivation of old CMV. Special tests may be useful in some cases to determine whether or not a CMV infection is new or old. A CMV infection of the eye can often be diagnosed by its appearance in people with AIDS.

Prevention & Expectations

What can be done to prevent the disease?

Frequent, thorough hand washing and personal hygiene should limit a few of the new cases spread from a person shedding CMV. Because CMV is so common, however, prevention is quite difficult. Special blood filters and testing of donated organs may prevent a few cases.

What are the long-term effects of the disease?

For most healthy people, a CMV infection has no long-term effects.

An unborn baby who is infected in the womb may have:

An eye infection in a person with AIDS may result in blindness. CMV pneumonia or gastrointestinal disease in transplant patients may cause death.

What are the risks to others?

People who shed CMV can pass it to others. For most people who get CMV, however, the infection is not serious.

Treatment & Monitoring

What are the treatments for the disease?

Otherwise healthy people who have CMV do not usually need therapy. For people with severely swollen tonsils, a medicine such as prednisone can be used to reduce the swelling and inflammation.

Antibiotics such as ganciclovir and foscarnet are used to treat active CMV in people with weakened immune systems. These medicines are designed to stop the virus from multiplying, rather than killing it.

What are the side effects of the treatments?

All medicines may have side effects. These may include allergic reactions, stomach upset, and other problems. A low white blood cell count is the most common side effect of ganciclovir. Other side effects depend on the medicines used.

What happens after treatment for the disease?

People who are healthy and get treatment can return to their usual activities once they recover. No further monitoring is generally needed. People who have weakened immune systems may need more careful monitoring for long periods of time, possibly for the rest of their lives.

How is the disease monitored?

For a CMV infection of the eye in people who have AIDS, repeated exams of the eyes and vision testing are needed. Affected people should report any change in their vision. For people with pneumonia or gastrointestinal disease, symptoms, a physical exam, and other blood and X-ray tests are commonly used for monitoring. Any new or worsening symptoms should be reported to the doctor.