Cytomegalovirus Infection
Cytomegalovirus is a common herpesvirus that generally causes disease only in infants infected before birth and in people who have a weakened immune system.
Infection with cytomegalovirus (CMV), a type of herpesvirus, is very common. Blood tests show that 60 to 90% of adults have had a CMV infection at some time. Usually this infection produces no symptoms. Serious infections generally develop only in babies infected before birth (see Section 23, Chapter 264) and in people with an impaired 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 of the immunosuppressant drugs they receive as part of the transplantation process.
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, both sexual and nonsexual transmission of the virus takes place. CMV infection may develop in people who receive infected blood.
CMV may cause symptoms soon after infection. It also has the ability to remain dormant in various tissues for the person's lifetime. Various stimuli can cause the dormant CMV to become active and cause disease.
Symptoms
The vast majority of people infected with CMV have no symptoms. Occasionally, a healthy person who is infected may feel ill and have a fever. CMV infection in adolescents and young adults can produce an illness with symptoms of fever and fatigue that resembles infectious mononucleosis. If a person receives a transfusion of blood containing CMV, fever and sometimes liver inflammation may develop 2 to 4 weeks later.
A person with a weakened immune system who becomes infected with CMV is particularly likely to develop a severe infection; serious illness and death may result. In people with AIDS, CMV infection is the most common viral complication. The virus tends to infect the retina of the eye (CMV retinitis), which can cause blindness. Infection of the brain (encephalitis) or ulcers of the intestine or esophagus may also develop.
In a pregnant woman, CMV infection can cause miscarriage, stillbirth, or death of the newborn. Death is caused by bleeding, anemia, or extensive damage to the liver or brain. Other disorders that may occur in the newborn include hearing loss and mental retardation.
Diagnosis and Treatment
CMV infection may develop gradually and not be recognized immediately. However, doctors always consider the possibility of CMV infection in a person with an impaired immune system. 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. In other people, doctors may be able to grow the virus from blood or lung specimens. In a person with CMV retinitis, an eye doctor can see characteristic abnormalities using an ophthalmoscope (an instrument that allows viewing of the internal eye structures).
Mild CMV infection usually is not treated but subsides by itself. When the infection threatens a person's life or eyesight, the antiviral drugs ganciclovir, valganciclovir, cidofovir, or foscarnet may be given. For people with CMV retinitis, a small device containing sustained-release ganciclovir can be implanted in the eye, or fomivirsen may be injected directly into the eye. These drugs have serious side effects and they may not cure the infection; however, treatment slows the disease's progression. CMV infections usually subside without treatment when the body's immune system recovers or immunosuppressant drugs are discontinued.
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