Cytomegalovirus infection (CMV) is a viral infection that rarely causes obvious illness. The virus that causes CMV is part of the herpes virus family and, like other herpes viruses, may become dormant for a period of time and then be reactivated. CMV affects young children mainly, but it is estimated that by age 30 in the United States, half of all adults are, or have been, infected. The virus can pass from an infected, pregnant mother to her child through the shared blood supply (umbilical cord).
Physicians recognize three clinical forms of CMV. These include: (1) CMV inclusion disease of the newborn, which ranges in severity from being without symptoms to being a severe disease affecting the liver, spleen and central nervous system, with possible developmental disabilities; (2) Acute acquired CMV infection, which is similar to infectious mononucleosis and characterized by fever, a feeling of being not quite right (malaise), skeletal-muscular pain and the absence of a sore throat; (3) CMV in immuno-compromised persons (for instance, people who have had organ transplants or who have HIV) with increased risk for difficult eye infections (CMV retinitis), gastrointestinal CMV, and encephalitis.
Most of those who are infected with CMV (children or adult) do not develop symptoms. When symptoms are present, there may be a great range in the type and severity of symptoms experienced. Among the 10 to 20% of infants who do have symptoms, they may range from such benign signs as the presence of CMV in the urine to dangerous conditions such as hemorrhagic anemia, liver damage and central nervous sytem (CNS) damage.
Infants born with a severe form of the disease typically have a low birth weight and develop a fever, hepatitis with jaundice, and hemorrhagic manifestations such as purpura. Hepatosplenomegaly (enlargement of liver and spleen), thrombocytopenia (decrease in number of blood platelets), chorioretinitis (inflammation of the choroid and retina), microcephaly (abnormal smallness of the head), and periventricular cerebral calcification may be present. Psychomotor retardation (development of motor defects and psychic abnormalities), spastic diplegia (spastic paralysis on both sides of body), blindness, deafness, or seizures may develop. Even though the cytomegalovirus infection may not at times be apparent in some infants, it may later cause hearing defects in these children.
Acquired cytomegalovirus infections are often asymptomatic (there are no symptoms apparent). An acute illness with fever, termed cytomegalovirus mononucleosis or cytomegalovirus hepatitis, may result from contact through medical treatment or from spontaneous contact with cytomegalovirus.
Postperfusion syndrome develops two to four weeks after transfusion with fresh blood containing CMV and is characterized by fever lasting two to three weeks, hepatitis of variable degrees with or without jaundice, a characteristic atypical lymphocytosis (excess of lymph cells in the blood or in any effusion) resembling that of infectious mononucleosis, and occasionally a rash. CMV infection in patients with malignancy or receiving immunosuppressive therapy may cause pulmonary, gastrointestinal or renal (kidney) involvement. This complication is of major importance in some reported transplantation series in which immunosuppressive therapy is utilized.
Cytomegalovirus retinitis may occur in some people with impaired immune systems due to AIDS, cytotoxic chemotherapy, or long-term immunosuppression. Some affected individuals may experience blurred vision, decreased visual activity, progressive visual impairment, and a defect of vision in a defined area in one or both eyes (scotomas).
Cytomegalovirus infection is caused by the human cytomegaloviruses (also known as “salivary gland viruses”). These are a subgroup of infective agents closely related to the herpes group of viruses. Like other herpes viruses, they may remain latent for years in people.
Cytomegalovirus infection has increased in the United States in recent years, possibly because of the increased use of daycare facilities. Recent studies of the percent of children with CMV virus in daycare facilities compared to the percent of children with CMV who are cared for at home found that about 60% of the children in daycare facilities have CMV compared to only 20% of the children cared for at home. If a woman is infected during pregnancy, fetal infections known as cytomegalic inclusion disease (CID) can occur.
According to the American Academy of Pediatrics, eighty-seven percent of children with CID develop complications. Thirty-one percent have serious sensorineural hearing loss, and sixty-two percent have some degree of mental retardation.
Perinatal CMV infection is common. It occurs in eight to thirteen percent of healthy newborns in the United States, and fourteen to eighteen percent of sick or premature infants. Healthy full-term infants rarely have symptoms and are at lesser risk of long-term effects. In contrast, symptoms are common in premature and sick full-term infants and may include pneumonia, hepatitis, hemolytic anemia, thrombocytopenia, and fever.
CMV infections can be controlled by drug therapy but, as yet, cannot be cured. Two drugs that keep the infection from getting worse are ganciclovir and foscarnet. These are delivered intravenously, and treatment must continue over a long period of time. A tablet form of ganciclovir, approved for CMV infections of the eye, has become available.
Further, ganciclovir, delivered in the form of an intravitreal implant (Vitrasert Implant) is available as a means of providing long-term delivery of the drug o the eye. This delivery system requires a minor operation on the eye(s) in order to implant the delivery system. This form of delivery lasts for 3 to 6 months before it must be repeated.
CMV infections arising in the course of an organ transplant are now treated with cytomegalovirus immune globulin intravenous (human) (CMV IGIV). CMV IGIV is an intravenous immune globulin enriched in antibodies against cytomegalovirus (CMV). It is approved by the U.S. Food and Drug Administration (FDA) as a preventive measure (prophylaxis) against CMV disease associated with transplantation of the kidney, lung, liver, pancreas, and heart.
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FROM THE INTERNET
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