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 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 can have serious symptoms, including blindness.
Cytomegalovirus can cause serious illness in infants who are infected before birth.
Doctors may detect 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 medications may be used.
Infection with cytomegalovirus (CMV) is very common. CMV is a type of herpesvirus (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.
Usually, CMV infection causes no symptoms. Serious infections typically develop only in infants infected before birth and in people with a weakened immune system—for example, people with AIDS or those who have received an organ transplant. In people with a weakened immune system, disease often results from reactivation of the dormant virus.
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 are particularly susceptible to CMV infection because they are given medications that suppress the immune system (immunosuppressants) 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 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.
In people with a weakened immune system, CMV can cause serious disease or death.
In people with AIDS, CMV infection is a common viral complication. The virus can 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, the following may result:
Death of the newborn
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:
Otherwise healthy people who have fever and fatigue
People who have a weakened immune system and an eye, brain, lung, or gastrointestinal infection
Newborns 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 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 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.
CMV retinitis can be identified by an ophthalmologist, who examines internal eye structures to check for characteristic abnormalities using an ophthalmoscope.
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 medicationSome Antiviral Medications for Herpesvirus Infections) 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.
Treating people who have HIV/AIDS with medications used to control HIV (antiretroviral medications) helps protect against CMV infection.
People who have had an organ transplant
