MSD Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Cytomegalovirus (CMV) Infection


Kenneth M. Kaye

, MD, Harvard Medical School

Reviewed/Revised Dec 2023
Topic Resources

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.

Infection with cytomegalovirus (CMV) is very common. CMV is a type of herpesvirus Overview of Herpesvirus Infections Some common viral infections are caused by a group of viruses called herpesviruses. Eight different types of herpesviruses infect people: Three herpesviruses— herpes simplex virus type 1, herpes... read more (herpesvirus type 5). Blood tests show that 50 to 90% of adults have had a CMV infection at some time.

CMV may cause symptoms soon after infection. Also, it remains dormant (inactive) in various tissues for life. Various stimuli can reactivate the dormant CMV, resulting in virus growth which can sometimes cause disease. The lungs, gastrointestinal tract, brain, spinal cord, or eyes may be infected.

Transmission of CMV

Infected people may shed cytomegalovirus in their urine or saliva intermittently. The virus is also excreted in mucus in the cervix (the lower part of the uterus), 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. People who have received an organ transplant Overview of Transplantation Transplantation is the removal of living, functioning cells, tissues, or organs from the body and then their transfer back into the same body or into a different body. The most common type of... read more are particularly susceptible to CMV infection because they are given medications that suppress the immune system (immunosuppressants Suppression of the Immune System ) to prevent rejection of the transplant.

Symptoms of CMV Infection

Most people infected with cytomegalovirus have no symptoms.

A few infected people feel ill and have a fever.

Infection with CMV, like that with Epstein-Barr virus (EBV, a type 4 herpesvirus), can cause a type of infectious mononucleosis Infectious Mononucleosis Epstein-Barr virus causes a number of diseases, including infectious mononucleosis. The virus is spread through kissing. Symptoms vary, but the most common are extreme fatigue, fever, sore throat... read more Infectious Mononucleosis in adolescents and young adults. Both CMV and EBV mononucleosis cause fever and fatigue. But EBV also causes a severe sore throat. CMV does not.

An uninfected person who receives a transfusion of blood containing CMV and becomes infected can have a fever, and sometimes liver inflammation develops 2 to 4 weeks later.

If a pregnant woman transmits CMV to the fetus, the following may result:

In newborns, CMV infection may cause extensive damage to the liver or brain. Newborns who survive may have hearing loss and intellectual disability.

Diagnosis of CMV Infection

  • In newborns, urine culture

  • Blood tests

  • In people with a weakened immune system, often biopsy

Cytomegalovirus infection may not be recognized immediately. Diagnosis of CMV infection is often unnecessary in healthy adults and children because treatment is unnecessary. However, doctors consider the possibility of CMV infection in the following people:

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 sending a sample of urine to a laboratory to grow (culture) and identify the virus.

Blood tests that detect antibodies to CMV can confirm a new infection if the person did not previously have these antibodies. (Antibodies Antibodies One of the body's lines of defense ( immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more Antibodies are produced by the immune system to help defend the body against a particular attacker, such as CMV.) But these tests cannot confirm whether disease is present.

The presence of CMV in body fluids and tissues does not always indicate disease and may merely represent viral shedding. CMV disease can be caused by reactivation of the virus, as in people with a weakened immune system. In these people, a biopsy of affected tissues is often necessary to confirm CMV disease.

Blood tests to estimate how many viruses are present may also be done and may be helpful because an elevated or rising CMV viral load is often highly suggestive of invasive disease.

Treatment of CMV Infection

  • For serious infections including CMV retinitis, antiviral medications

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

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

When the infection threatens life or eyesight, an antiviral medication Antiviral drugs A virus is composed of nucleic acid, either DNA or RNA, surrounded by a protein coat. It requires a living cell in which to multiply. A viral infection can lead to a spectrum of symptoms from... read more (valganciclovir, ganciclovir, cidofovir, foscarnet, maribavir, or a combination) may be given. These antivirals may be given by mouth or by vein. When CMV retinitis is very severe, the medications may also be injected directly into the eye. These medications have serious side effects (see table ) and do not cure the infection. However, treatment slows the disease's progression and may preserve sight.

Antivirals 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 medication), the infection usually subsides when the immune system recovers or the medication is stopped.

quiz link

Test your knowledge

Take a Quiz!