Cytomegalovirus (CMV):Avirusthat infects 50-85% of adultsinthe US by age 40 and is also the virus most frequently transmitted to a child before birth. Persons with symptoms have amononucleosis-likesyndromewith prolonged fever and mild hepatitis. Once a person becomes infected, the virus remains alive and usually dormant within that person's body for life.Recurrentdiseaserarely occurs unless the person'simmune systemis suppressed due totherapeuticdrugs or disease. CMV infection is therefore a concern because of the risk ofinfectionto the unborn baby, people who work with children, andimmunodeficientpeople such astransplantrecipients and those with HIV.
CMVis a member of theherpesvirusgroup, which also includesherpessimplex virus,varicella-zoster virus(which causes chickenpox) and Epstein-Barr virus (which causes infectious mononucleosis). Thesevirusesshare a characteristic ability to remain dormant within the body over a long period. Initial CMV infection, which may have few symptoms, is always followed by a prolonged, inapparent infection during which the virus resides in cells without causing detectable damage orclinicalillness. Severe impairment of the body'simmunesystem bymedicationor disease consistently reactivates the virus from thelatentor dormant state.
Infectious CMV may be shed in the bodily fluids of any previously infected person, and thus may be found inurine,saliva,blood, tears,semen, and breast milk. The shedding of virus may take place intermittently, without any detectable signs, and without causing symptoms.
Spread of CMV is from person to person. Infection requires close contact with a person excreting the virus in their saliva, urine, or other bodily fluids. CMV can be sexually transmitted. It can also be transmitted viabreastmilk, transplanted organs and, rarely, blood transfusions. Although the virus is not highlycontagious, it has been shown to spread in households and among young children in day care centers.
Transmission of the virus is often preventable because it is most often transmitted through infected bodily fluids that come in contact with hands and then are absorbed through thenoseormouthof a susceptible person. Therefore, care should be taken when handling children and items like diapers. Simple hand washing with soap andwateris effective in removing the virus from the hands.
CMV infection without symptoms is common in infants and young children; therefore, it is unjustified and unnecessary to exclude from school or an institution a child known to be infected. Similarly, hospitalized patients do not need separate or elaborate isolation precautions.
During pregnancy when a woman becomes infected with CMV, there is a risk that theinfantmay be born with CMV and have CMV-related complications. On the other hand, infants and children who acquire CMV after birth have few, if any, symptoms or complications.
CMV is the most important cause ofcongenitalviral infectionin the US. For infants who are infected by their mothers before birth, two potential pictures exist:
- Generalized infection may occur in the infant, and symptoms mayrangefrom moderate enlargement of the liver andspleen(withjaundice) to fatal illness. With supportive treatment, most infants with CMV disease survive. However, from 80% to 90% have complications within the first few years of life that may include hearing loss, vision impairment, and varying degrees ofmental retardation.
- Another 5% to 10% of infants who are infected have no symptoms at birth but subsequently have varying degrees of hearing and mental or coordination problems.
Mosthealthypeople working with infants and children face no special risk from CMV infection. However, for women of child-bearing age who previously have not been infected with CMV, there is a potential risk to the developing unborn child (the risk is described above in the Pregnancysection). Contact with children who are in day care, where CMV infection is commonly transmitted among young children (particularly toddlers), may be a source of exposure to CMV. Since CMV is transmitted through contact with infected body fluids, including urine and saliva, child care providers (meaning day care workers, special education teachers, therapists, as well as mothers) should be educated about the risks of CMV infection and the precautions they can take. Day care workers appear to be at a greater risk thanhospitaland otherhealthcare providers, and this may be due in part to the increased emphasis on personalhygienein the health care setting.
Primary(or the initial) CMV infection in theimmunocompromisedpatientcan cause serious disease. However, the more common problem is the reactivation of the dormant virus. Infection with CMV is amajorcause of disease anddeathin immunocompromised patients, includingorgantransplant recipients, patients undergoing hemodialysis, patients with cancer, patients receivingimmunosuppressivedrugs, andHIV-infected patients. Pneumonia, retinitis (an infection of the eyes), andgastrointestinal疾病疾病的常见表现。Because of this risk, exposing immunosuppressed patients to outside sources of CMV should be minimized. Whenever possible, patients without CMV infection should be given organs and/or blood products that are free of the virus.
Most infections with CMV are not diagnosed because the virus usually produces few, if any, symptoms and tends to reactivate intermittently without symptoms. However, persons who have been infected with CMV develop antibodies to the virus, and these antibodies persist in the body for the lifetime of that individual. A number oflaboratorytests that detect these antibodies to CMV have been developed to determine if infection has occurred and are widely available. In addition, the virus can be cultured from specimens obtained from urine,throatswabs, and组织samples to detect active infection.
