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Nasty Infectious Diseases You Want To Avoid - Cytomegalovirus

Updated on December 31, 2008

This is a disease caused by cytomegalovirus, one of the Herpes family of viruses. The CMV is the largest, most complex virus that infects humans. First discovered in 1956, this extremely common infection has affected almost all children, yet rarely produces symptoms. By adulthood, up to 85 percent of Americans have been infected. While not usually a serious disease, those with impaired immunity may have more severe symptoms. Cytomegalovirus also may cause significant problems during pregnancy if a woman has an acute infection, which would be transmitted to her unborn child. This can lead to minor impairments affecting hearing, vision, or mental capacity; a few of these babies are born with severe brain damage, including mental retardation or severe hearing loss. Once a person has been infected, the virus remains latent in the body like other herpes viruses and can be reactivated later on during periods of stress or weakened immunity.

Cause - CMV is present in almost all body fluids, including urine, saliva, semen, breast milk, and blood. It can be sexually transmitted, although most people don't get it this way. It is commonly found in day care centers, where it is passed around in children's saliva or urine-soaked diapers and transmitted, although most people don't get it this way. It is commonly found in day care centers, where it is passed around in children's saliva or urine soaked diapers and transmitted from unwashed hands or shared toys. Women with toddlers in day care are often infected, since CMV transmission happens often in these institutions. While young children rarely have symptoms, they excrete the virus in their urine and saliva for months to years. Anyone who works with young children is exposed to CMV. It is also possible to acquire CMV from transfused blood or transplanted organs, since so many individuals have an infection without having symptoms. A person having an organ transplant or chemotherapy for cancer takes drugs that suppress the immune system; if such a patient had been infected with CMV earlier in life, the dormant virus can reactivate, resulting in lifethreatening illness. If a patient taking these drugs has a first exposure to the virus, the new infection can cause a serious illness. In AIDS patients, reactivation of a CMV infection can lead to serious eye infections called retinitis, as well as hepatitis, encephalitis, colitis and pneumonia.

Symptoms - Very few adults (including pregnant women) have symptoms when infected; if they do, symptoms will be mild, including achiness, low fever, and sore throat. Young children may experience a mild cold or flulike illness with fever. However, if a woman is first exposed to this virus early in pregnancy, the resulting infection can cause serious fetal abnormalities. About 40,000 infants in the United States are infected each year, but almost all babies infected before birth are normal. About 10 percent of babies infected before birth are sick with the symptoms listed above. Of these 10 percent, 20 to 30 percent have a "congenital CMV syndrome" with serious symptoms that may be fatal. These symptoms include problems of major organs, including the liver, brain, eyes, and lungs together with convulsions, lethargy, and breathing problems. If such a profoundly affected infant survives, there may be permanent damage (mental retardation, water on the brain, small brain, hearing loss, eye inflammation, poor coordination, and liver disease). Some studies suggest that a few apparently normal babies who were infected at birth may encounter health problems later in life. Babies infected before birth excrete the virus intermittently for years and are infectious when shedding the virus. While CMV doesn't usually cause a problem for healthy people, it can sometimes lead to an acute illness resembling infectious mononucleosis that is almost identical to the infection associated with Epstein-Barr virus, including a fever of two to three weeks, inflamed liver, and sometimes a rash. Healthy people with CMV mono have an excellent prognosis.

Diagnosis - Test results for CMV can be misleading. Blood can be tested for the CMV antibody, but all the presence of antibody indicates is that there was an earlier infection. The test won't reveal whether the virus is presently in blood, urine, or saliva. If a patient has symptoms that imply a recently acquired infection, sequential tests may reveal changes in antibody levels that indicate an active infection. The test for virus in these fluids is available in most large hospital and commercial labs, but results may take between two and six weeks. Newborns with possible congenital CMV infection must have the virus cultured from their urine, nose, eyes, or spinal fluid to confirm CMV. This can be helpful in diagnosing potential future problems such as hearing loss. In patients with impaired immunity, tests can be helpful to measure the effectiveness of therapy.

Treatment - There is no cure for congenital CMV; babies with the disease need to be hospitalized. In AIDS patients, treatment includes two intravenous antiviral drugs, ganciclovir or foscarnet. These drugs are not recommended for those with healthy immune systems because the side effects from the drugs are more severe than the risks of the illness.

Prevention - Good hygiene can reduce the risk of transmission at day care centers, but intensive infection control is not practical when dealing with a virus as common as CMV. People who need organ transplants are tested for antibodies to CMV; those who do not have the antibodies will be matched to donors without antibodies as well. Because a match isn't always possible, the recipient faces a risk of serious CMV infection from the transplanted organ later. CMV-negative organ recipients who need blood transfusions will be given special CMV-negative blood, which is rare and saved for special cases. There is no generally accepted, valid and widespread vaccine currently available for CMV. Antibodies from those with high levels of immunity are available in the form of hyperimmune globulins for certain high-risk patients, but use of these products is expensive and of limited value. Researchers studying the feasibility of a CMV vaccine believe that widespread vaccination of children with a safe, effective vaccine is justified to protect unborn children from birth defects by reducing the risk that mothers are exposed to infected children. Researchers are studying a possible recombinant CMV vaccine.


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    • Sarah Wingate profile image

      Sarah Wingate 4 years ago from Tel Aviv, Israel

      CMV is a nonlethal virus that in itself should not cause much concern. However, as it is mentioned in the article, the problem begins if the virus attacks a pregnant woman. I know of women whose body does not have antibodies to handle the virus. Getting pregnant for them is very scary.