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Cytomegalovirus (CMV) Infection

By Craig R. Pringle, BSc, PhD, Professor Emeritus, School of Life Sciences, University of Warwick

Cytomegalovirus infection is a common herpesvirus infection with a wide range of symptoms: from no symptoms to fever and fatigue (resembling infectious mononucleosis) to severe symptoms involving the eyes, brain, or other internal organs.

  • This virus is easily spread through sexual and nonsexual contact with body secretions.

  • Most people have no symptoms, but some feel ill and have a fever, and people with a weakened immune system or an infected fetus can have serious symptoms, including blindness.

  • Doctors may diagnose the infection by culturing a sample of infected body fluid, such as urine.

  • Often, no treatment is required, but if the infection is severe, antiviral drugs may be used.

Infection with cytomegalovirus (CMV, herpesvirus 5—see Herpesvirus Infection Overview) is very common. Blood tests show that 60 to 90% of adults have had a CMV infection at some time.

CMV spreads very easily. Infected people may shed the virus in their urine or saliva for months. The virus is also excreted in cervical mucus, semen, stool, and breast milk. Thus, the virus is spread through sexual and nonsexual contact. If a pregnant woman is infected, the fetus may acquire the infection during the pregnancy, or the baby may acquire the infection during delivery. CMV infection may develop in people who receive a transfusion of infected blood or an infected organ transplant.

CMV may cause symptoms soon after infection. Also, it can remain dormant (inactive) in various tissues for life. Various stimuli can reactivate the dormant CMV, resulting in disease.

Usually, this infection causes no symptoms. Serious infections typically develop only in infants infected before birth (see Some Infections in Newborns : Cytomegalovirus (CMV)) and in people with a weakened immune system—for example, people with AIDS or those who have received an organ transplant. People who have received an organ transplant are particularly susceptible to CMV infection because they are given drugs that suppress the immune system (immunosuppressants) to prevent rejection of the transplant. In people with a weakened immune system, disease often results from reactivation of the dormant virus.


Most people infected with CMV have no symptoms. A few infected people feel ill and have a fever. CMV infection in adolescents and young adults can cause an illness with symptoms of fever and fatigue that resembles infectious mononucleosis (except mononucleosis causes a severe sore throat and CMV does not—see Infectious Mononucleosis). If a person receives a transfusion of blood containing CMV, fever and sometimes liver inflammation may develop 2 to 4 weeks later.

If a person with a severely weakened immune system becomes infected with CMV, the infection may be severe, sometimes resulting in serious disease or death. In people with AIDS, CMV infection is a common viral complication. The virus tends to infect the retina of the eye. This infection (CMV retinitis) can cause blindness. Infection of the brain (encephalitis), pneumonia, or painful ulcers of the intestine or esophagus may also develop.

If a pregnant woman transmits CMV to the fetus, miscarriage, stillbirth, or death of the newborn may result. Death is caused by bleeding, anemia, or extensive damage to the liver or brain. Newborns who survive may have hearing loss and intellectual disability.


  • In newborns, urine culture

  • Blood tests

  • In people with a weakened immune system, often biopsy

CMV infection may develop gradually and not be recognized immediately. Diagnosis is often unnecessary in healthy adults and children because treatment is unnecessary. However, doctors always consider the possibility of CMV infection in people who have fever and fatigue or who have a weakened immune system and an eye, a brain, or a gastrointestinal infection. CMV infection is also suspected in newborns who have a fever or who seem sick.

Once CMV infection is suspected, a doctor conducts tests to detect the virus in body fluids or tissues.

In newborns, the diagnosis is usually made by culturing the urine.

Blood tests that detect antibodies to CMV can confirm a new infection but cannot confirm disease caused by reactivation of the virus, as often occurs in people with a weakened immune system. In these people, a biopsy of affected tissues is often necessary to confirm CMV infection.

Blood tests to estimate how many viruses are present may also be done.

CMV retinitis can be identified by an ophthalmologist, who examines internal eye structures to check for characteristic abnormalities using an ophthalmoscope.


  • For CMV retinitis, antiviral drugs

  • For people with HIV/AIDS, drugs used to treat HIV infections

Mild CMV infection is usually not treated. It subsides on its own.

When the infection threatens life or eyesight, an antiviral drug (valganciclovir, ganciclovir, cidofovir, foscarnet, or a combination) may be given. These drugs have serious side effects (see Table: Some Antiviral Drugs for Herpesvirus Infections) and may not cure the infection. However, treatment slows the disease's progression and may preserve sight.

Antiviral drugs are used to treat other severe symptoms due to CMV but are less reliably effective than when used to treat retinitis.

If CMV infection occurs in people whose immune system is temporarily weakened or suppressed (by a disorder or drug), the infection usually subsides without treatment when the immune system recovers or the drug is stopped.

People who have had an organ transplant are often given antiviral drugs (such as ganciclovir, valganciclovir, or foscarnet) to prevent CMV infection.