Aids Guide-CDC releases CMV guidelines for HIV patients
Aids Guide-CDC releases CMV guidelines for HIV patients
Cytomegalovirus (CMV) infects between 50% and 85% of U.S. adults by age 40, and CMV is the virus most frequently transmitted to fetuses.
Most healthy people experience no symptoms from infection, although a few will have symptoms similar to mononucleosis with a prolonged fever and mild hepatitis. Once a person is infected with the virus, it remains dormant for life unless the person has a suppressed immune system. This is why CMV infection could be dangerous to high-risk groups, including HIV/ AIDS patients.
The Centers for Disease Control and Prevention (CDC) in Atlanta has published information about CMV infection. Here are some of the CDC's answers to questions about CMV:
Q: What exactly is CMV?
CDC: CMV is a member of the herpes virus group, which includes herpes simplex virus types 1 and 2, varicella-zoster virus (which causes chickenpox), and Epstein-Barr virus (which causes infectious mononucleosis). These viruses have 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 or clinical illness. Severe impairment of the body's immune system by medication or disease consistently reactivates the virus from the latent or dormant state.
Infectious CMV may be shed in the bodily fluids of any previously infected person, and thus may be found in urine, blood, tears, semen, and breast milk. The shedding of virus may take place intermittently, without any detectable signs, and without causing symptoms.
Q: How easily can CMV be transmitted?
CDC: Transmission of CMV occurs from person to person. Infection requires close, intimate contact with a person excreting the virus in their saliva, urine, or other bodily fluids. CMV can be sexually transmitted and can also be transmitted via breast milk, transplanted organs, and rarely from blood transfusions.
Although the virus is not highly contagious, 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 the nose or mouth of a susceptible person. Therefore, care should be taken when handling children and items like diapers. Simple hand washing with soap and water is effective in removing the virus from the hands.
Q: How serious is CMV infection in HIV-positive people?
CDC: Primary or initial CMV infection in the immunocompromised patient can cause serious disease. However, the more common problem is reactivation of the dormant virus. Infection with CMV is a major cause of disease and death in immunocompromised patients, including HIV-infected patients, organ transplant recipients, patients undergoing hemodialysis, patients with cancer, and patients receiving immunosuppressive drugs. Pneumonia, retinitis (an infection of the eyes), and gastrointestinal disease are the common manifestations of disease. Because of this risk, exposure of 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.
Q: How can a health care worker/professional diagnose CMV?
CDC: 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 of laboratory tests that detect these antibodies to CMV have been developed to determine if infection has occurred. These tests are widely available from commercial laboratories. In addition, the virus can be cultured from specimens obtained from urine, throat swabs, and tissue samples to detect active infection.
Also, CMV should be suspected if a patient:
• has symptoms of infectious mononucleosis but has negative test results for mononucleosis and Epstein-Barr virus;
• shows signs of hepatitis but has negative test results for hepatitis A, B, and C.
For best diagnostic results, laboratory tests for CMV antibody should be performed by using paired serum samples. One blood sample should be taken upon suspicion of CMV, and another one taken within two weeks. A virus culture can be performed at any time the patient is symptomatic.
Q: What serologic testing is available for CMV?
CDC: The enzyme-linked immunosorbent assay (ELISA) is the most commonly available serologic test for measuring antibody to CMV. The result can be used to determine if acute infection, prior infection, or passively acquired maternal antibody in an infant is present. Other tests include various fluorescence assays, indirect hemagglutination, and latex agglutination.
An ELISA technique for CMV-specific IgM is available but may give false-positive results unless steps are taken to remove rheumatoid factor or most of the IgG antibody before the serum sample is tested. Because CMV-specific IgM may be produced in low levels in reactivated CMV infection, its presence is not always indicative of primary infection. Only a virus recovered from a target organ, such as a lung, provides unequivocal evidence that the current illness is caused by acquired CMV infection. If serologic tests detect a positive or high titer of IgG, this result should not automatically be interpreted to mean that active CMV infection is present. However, if antibody tests of paired serum samples show a fourfold rise in IgG antibody and a significant level of IgM antibody, meaning equal to at least 30% of the IgG value, or virus is cultured from a urine or throat specimen, the findings indicate that an active CMV infection is present.
Q: What is the treatment for CMV infection?
CDC: Currently, no treatment exists for CMV infection in the healthy individual. Antiviral drug therapy is now being evaluated in infants. Ganciclovir treatment is used for patients with depressed immunity who have either sight-related or life-threatening illnesses. Vaccines are still in the research and development stage.
Q: Where can I find additional information?
CDC: The CDC has made available for distribution a brochure titled "CMV: Diagnosis, Prevention, and Treatment." To obtain the brochure, write to:
Viral Exanthems and Herpesvirus Branch
DVRD/NCID
Mail Stop A-15
Centers for Disease Control and Prevention
Atlanta, GA 30333
Or call (404) 639-1338, or go to the CDC Web site at www.cdc. gov/ncidod/diseases/cmv.
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