Cytomegalovirus Infection
Cytomegalovirus Infection
Definition
Cytomegalovirus (CMV) is a virus related to the group of herpes viruses. Infection with CMV can cause no symptoms, or can be the source of serious illness in people with weak immune systems. CMV infection is also an important cause of birth defects.
Description
CMV is an extremely common organism worldwide. It is believed that about 85% of the adults in the United States have been infected by CMV at some point in their lives. CMV is found in almost all of the body's organs. It is also found in body fluids, including semen, saliva, urine, feces, breast milk, blood, and secretions of the cervix (the narrow, lower section of the uterus).
CMV is also able to cross the placenta (the organ that provides oxygen and nutrients to the unborn baby in the uterus). Because CMV can cross the placental barrier, initial infection in a pregnant woman can lead to infection of the developing baby.
Causes and symptoms
CMV is passed between people through contact with body fluids. CMV also can be passed through sexual contact. Babies can be born infected with CMV, either becoming infected in the uterus (congenital infection) or during birth (from infected cervical secretions).
Like other herpes viruses, CMV remains inactive (dormant) within the body for life after the initial infection. Some of the more serious types of CMV infections occur in people who have been harboring the dormant virus, only to have it reactivate when their immune system is stressed. Immune systems may be weakened because of cancer chemotherapy, medications given after organ transplantation, or diseases that significantly lower immune resistance like acquired immunodeficiency syndrome (AIDS ).
In a healthy person, initial CMV infection often occurs without symptoms and is rarely noticed. Occasionally, a first-time infection with CMV may cause a mild illness called mononucleosis. Symptoms include swollen glands, liver, and spleen; fever; increased white blood cells; headache; fatigue; and sore throat. About 8% of all mononucleosis cases are due to CMV infection. A similar infection, though slightly more serious, may occur two to four weeks after receiving a blood transfusion containing CMV.
In people with weakened immune systems, CMV infection can cause more serious and potentially life-threatening illnesses. These illnesses include pneumonia, and inflammations of the liver (hepatitis), brain (encephalitis ), esophagus (esophagitis), large intestine (colitis), and retina of the eye (retinitis).
Babies who contract CMV from their mothers during birth rarely develop any illness from these infections. Infants born prematurely who become CMV infected during birth have a greater chance of complications, including pneumonia, hepatitis, decreased blood platelets.
However, an unborn baby is at great risk for serious problems when the mother becomes infected with CMV for the first time while pregnant. About 10% of these babies will be born with obvious problems, including prematurity, lung problems, an enlarged liver and spleen, jaundice, anemia, low birth weight, small head size, and inflammation of the retina. About 90% of these babies may appear perfectly normal at birth. Unfortunately, about 20% will later develop severe hearing impairments and mental retardation. A 2003 report found that pregnant women 25 years and older who are immune to CMV are much less likely to pass the virus to their babies than younger women who have never been exposed to CMV.
Diagnosis
Body fluids or tissues can be tested to reveal CMV infection. However, this information is not always particularly helpful because CMV stays dormant in the cells for life. Tests to look for special immune cells (antibodies) directed specifically against CMV are useful in proving that a person has been infected with CMV. However, these tests do not give any information regarding when the CMV infection first occurred.
Treatment
Ganciclovir and foscarnet are both antiviral medications that have been used to treat patients with weak immune systems who develop a serious illness from CMV (including retinitis). As of 1998, research was still being done to try to find useful drugs to treat newborn babies suffering from congenital infection with CMV. Antiviral drugs are not used to treat CMV infection in otherwise healthy patients because the drugs have significant side effects that outweigh their benefits. In 2003, researchers in Europe announced a new compound that appeared to be highly effective against CMV infections. The new drug acted earlier in the viral replication of the infection and showed promise, however, clinical trials were continuing.
KEY TERMS
Cervix— The narrowed, lowest part of the uterus through which a baby must pass in order to enter the birth canal.
Congenital— A condition that exists before birth and at birth.
Placenta— The organ that provides oxygen and nutrition from the mother to the unborn baby during pregnancy. The placenta is attached to the wall of the uterus and leads to the unborn baby via the umbilical cord.
Prognosis
Prognosis in healthy people with CMV infection is excellent. About 0.1% of all newborn babies will have serious damage from CMV infection occurring while they were developing in the uterus. About 50% of all transplant patients will develop severe illnesses due to reactivation of dormant CMV infection. These illnesses have a high rate of serious complications and death.
Prevention
Prevention of CMV infection in the normal, healthy person involves good handwashing. Blood products can be screened or treated to insure that they do not contain CMV. In 2003, a new high-dose prophylactic (preventive) treatment was being tested to reduce CMV risk in stem cell transplant recipients.
Resources
PERIODICALS
Fowler, Karen B., Sergio Stagno, and Robert F. Pass. "Maternal Immunity and Prevention of Congenital Cytomegalovirus Infection." JAMA, The Journal of the American Medical Association February 26, 2003: 1008.
"High-Dose Acyclovir May Reduce Cytomegalovirus Infection Risk." Virus Weekly July 15, 2003: 16.
"Novel Compound Highly Effective Against Cytomegalovirus Infection." AIDS Weekly November 25, 2003: 17.
ORGANIZATIONS
Baylor College of Medicine. 1 Baylor Plaza, Houston, TX 77030. (713) 798-4951. 〈http://public.bcm.tmc.edu〉.
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. 〈http://www.cdc.gov〉.
March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. (914) 428-7100. resourcecenter@modimes.org. 〈http://www.modimes.org〉.
Cytomegalovirus (CMV) Infection
Cytomegalovirus (CMV) Infection
How Are CMV Infections Diagnosed and Treated?
What Are the Complications of CMV Infection?
How Is CMV Infection Prevented?
Cytomegalovirus (sye-tuh-MEH-guh-lo-vy-rus), or CMV infection is very common and usually causes no symptoms. It poses little risk for healthy people, but it can lead to serious illness in people with weak immune systems.
KEYWORDS
for searching the Internet and other reference sources
Herpes simplex virus
Herpesvirus
Immune deficiencies
Mononucleosis
Varicella zoster virus
What Is CMV?
CMV is part of the herpesvirus (her-peez-VY-rus) family, which also includes the viruses that cause herpes*, chicken pox, and mononucleosis*. As with other members of the herpesvirus family, once CMV enters a person’s body, it remains there for life. CMV infection can bring about flulike symptoms when a person is first infected, but many people have no symptoms at all. The virus usually becomes dormant after it enters the body, meaning that it remains “hidden” and does not cause symptoms of illness. The virus can emerge at a later time, however, and produce illness in people with weakened immune systems, such as people who have cancer or AIDS or those who have received organ or bone marrow* transplants. CMV is a risk for pregnant women because of the danger that it can be transmitted to their babies. The disease is the leading cause of mental retardation and hearing defects in newborns in the United States as a result of congenital (kon-JEH-nih-tul) infection, that is, infection that is present at birth.
- *herpes
- (HER-peez) is a viral infection that can produce painful, recurring skin blisters around the mouth or the genitals, and sometimes symptoms of infection elsewhere in the body.
- *mononucleosis
- (mah-no-nuk-lee-O-sis) is an infectious illness caused by a virus that often leads to fever, sore throat, swollen glands, and tiredness.
- *bone marrow
- is the soft tissue inside bones where blood cells are made.
How Is CMV Spread?
CMV is contagious and can spread through bodily fluids, including blood, saliva, semen, breast milk, tears, and urine. The virus can be transmitted by sexual contact, by close person-to-person contact, or from mother to baby during pregnancy or birth or while breast-feeding. It often spreads among children in day care or preschool or among family members. In the United States, as many as three of every five adults have been infected with CMV by the time they reach age 40. CMV infects people all over the world and is even more widespread in developing countries and those with poor living conditions.
What Are the Symptoms of CMV?
Most people who have been infected with CMV never show symptoms. In some people, the virus causes mild symptoms that mimic the flu or infectious mononucleosis, such as fever, chills, body aches, headache, swollen lymph nodes*, sore throat, and fatigue. Newborns who contract CMV infection in the womb may be born with jaundice*, microcephaly*, signs of brain damage, and a serious inflammation of the eyes known as retinitis*. Others seem healthy when they are born but later have growth problems and signs of hearing loss or mental retardation.
- *lymph
- (LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.
- *jaundice
- (JON-dis) is a yellowing of the skin, and sometimes the whites of the eyes, caused by a buildup in the body of bilirubin, a chemical produced by the liver. An increase in bilirubin may indicate disease of the liver.
- *microcephaly
- (my-kro-SEH-fah-lee) is the condition of having an abnormally small head, which typically results from having an underdeveloped or malformed brain.
- *retinitis
- (reh-tin-EYE-tis) is inflammation of the retina, the nerve-rich membrane at the back of the eye on which visual images form.
How Are CMV Infections Diagnosed and Treated?
Most cases of CMV infection are never diagnosed because they produce few or no symptoms. When doctors do suspect CMV, they often base the diagnosis on symptoms, physical examination, and blood tests for antibodies* to the virus. They also will rule out other diseases that cause similar symptoms, such as infectious mononucleosis caused by the Epstein-Barr virus. Sometimes blood tests show evidence of past infection with CMV but do not indicate active infection. A test known as the polymerase (pah-LIM-er-ace) chain reaction, or PCR, can test specifically for active CMV infection by finding traces of DNA* from the virus in body fluids. People with healthy immune systems who contract CMV infection usually do not require medical treatment. When people with weakened immune systems develop CMV infection, doctors often prescribe medication made to fight viruses. These antiviral medicines may need to be given by injection, and patients sometimes have to take them for months or even years. Symptoms of initial CMV infection usually last 2 to 3 weeks in healthy people. After that, the virus remains in the body for life. Flare-ups of illness from CMV in healthy people are rare and typically occur when the immune system has been stressed by fighting another illness.
- *antibodies
- (AN-tih-bah-deez) are protein molecules produced by the body’s immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.
- *DNA ,
- or deoxyribonucleic acid (dee-OX-see-ry-bo-nyoo-klay-ik AH-sid), is the specialized chemical substance that contains the genetic code necessary to build and maintain the structures and functions of living organisms.
Once inside the human body, the cytomegalovirus can invade many organs and systems. In this microscopic image, viral components are visible in the lining of the stomach. If the virus becomes active in the stomach, it can produce ulcers. Visuals Unlimited
What Are the Complications of CMV Infection?
CMV infection can cause more severe illness in people with weakened immune systems, such as pneumonia* and retinitis. If it is untreated, retinitis can lead to blindness. CMV also can cause severe inflammation of the esophagus and colon, leading to difficulty in swallowing, long-lasting diarrhea, and weight loss. It also can affect the brain or nerves. Infants born with CMV infection may have jaundice, poor growth, problems with vision and hearing, and other disabilities, including slow development and mental retardation.
- *pneumonia
- (nu-MO-nyah) is inflammation of the lung.
How Is CMV Infection Prevented?
The best way to help prevent the spread of CMV is to wash the hands regularly, especially after changing diapers or touching bodily fluids. Doctors advise women who are pregnant and people who work in child care to be particularly careful. Patients scheduled to have organ or bone marrow transplants typically receive medication before the operation to prevent CMV disease from developing, as the transplant process weakens their immune systems.
See also
AIDS and HIV Infection
Congenital Infections
Herpes Simplex Virus Infections
Immune Deficiencies
Laboratory Tests
Mononucleosis, Infectious
Pneumonia
Resources
Organizations
U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC offers information about cytomegalovirus infection at its website.
Telephone 800-311-3435 http://www.cdc.gov
U.S. National Institute of Allergy and Infectious Diseases (NIAID), Building 31, Room 7A-50, 31 Center Drive MSC 2520, Bethesda, MD 20892-2520. The NIAID, part of the National Institutes of Health, posts fact sheets on cytomegalovirus at its website.
Telephone 301-496-5717 http://www.niaid.nih.gov
Cytomegalovirus Infection
Cytomegalovirus infection
Definition
Cytomegalovirus (CMV) is a virus related to the group of herpes viruses. Infection with CMV can cause no symptoms or can be the source of serious illness in people with weak immune systems. CMV infection is also an important cause of birth defects.
Description
CMV is an extremely common organism worldwide. It is believed that about 85 percent of the adults in the United States have been infected by CMV at some point in their lives. CMV is found in almost all of the body's organs. It is also found in body fluids, including semen, saliva, urine, feces, breast milk, blood, and secretions of the cervix (the narrow, lower section of the uterus).
CMV is also able to cross the placenta (the organ that provides oxygen and nutrients to the unborn baby in the uterus). Because CMV can cross the placental barrier, initial infection in a pregnant woman can lead to infection of the developing baby.
Demographics
In the United States, about 40 to 60 percent of all adults in the middle- and upper-socioeconomic classes show antibody proof of prior infection with CMV; antibody proof is as high as 80 percent in adults in the lower socioeconomic class. Worldwide, about 0.2 to 2.2 percent of all babies are born with congenital CMV infection. Of those babies born with congenital CMV infection, about 10 percent to 20 percent ultimately suffer form hearing impairment , eye damage, or problems with intellectual or motor function.
Causes and symptoms
CMV is passed between people through contact with body fluids. CMV also can be passed through sexual contact. Babies can be born infected with CMV, either becoming infected in the uterus (congenital infection) or during birth (from infected cervical secretions).
Like other herpes viruses, CMV remains inactive (dormant) within the body for life after the initial infection. Some of the more serious types of CMV infections occur in people who have been harboring the dormant virus, only to have it reactivate when their immune system is stressed. Immune systems may be weakened because of cancer chemotherapy , medications given after organ transplantation, or diseases that significantly lower immune resistance like acquired immunodeficiency syndrome (AIDS ).
In a healthy person, initial CMV infection often occurs without symptoms and is rarely noticed. Occasionally, a first-time infection with CMV may cause a mild illness called mononucleosis. Symptoms include swollen glands, liver, and spleen; fever ; increased white blood cells; headache ; fatigue; and sore throat . About 8 percent of all mononucleosis cases are due to CMV infection. A similar infection, though slightly more serious, may occur two to four weeks after receiving a blood transfusion containing CMV.
In people with weakened immune systems, CMV infection can cause more serious and potentially life-threatening illnesses. These illnesses include pneumonia and inflammations of the liver (hepatitis), brain (encephalitis ), esophagus (esophagitis), large intestine (colitis), and retina of the eye (retinitis).
Babies who contract CMV from their mothers during birth rarely develop any illness from these infections. Infants born prematurely who become CMV infected during birth have a greater chance of complications, including pneumonia, hepatitis, decreased blood platelets.
However, an unborn baby is at great risk for serious problems when the mother becomes infected with CMV for the first time while pregnant. About 10 percent of these babies will be born with obvious problems, including prematurity , lung problems, an enlarged liver and spleen, jaundice , anemia, low birth weight, small head size, and inflammation of the retina. About 90 percent of these babies may appear perfectly normal at birth. Unfortunately, about 20 percent later develop severe hearing impairments and mental retardation . A 2003 report found that pregnant women 25 years of age and older who are immune to CMV are much less likely to pass the virus to their babies than younger women who have never been exposed to CMV.
Diagnosis
Body fluids or tissues can be tested to reveal CMV infection. However, this information is not always particularly helpful because CMV stays dormant in the cells for life. Tests to look for special immune cells (antibodies) that are directed specifically against CMV are useful in proving that a person has been infected with CMV. However, these tests do not give any information regarding when the CMV infection first occurred.
Treatment
Ganciclovir and foscarnet are antiviral medications that have been used to treat patients with weak immune systems who develop a serious illness from CMV (including retinitis). As of 1998, research was still being done to try to find useful drugs to treat newborn babies suffering from congenital infection with CMV. Antiviral drugs are not used to treat CMV infection in otherwise healthy patients because the drugs have significant side effects that outweigh their benefits. In 2003, researchers in Europe announced a new compound that appeared to be highly effective against CMV infections. The new drug acted earlier in the viral replication of the infection and showed promise; however, clinical trials were continuing.
Prognosis
Prognosis in healthy people with CMV infection is excellent. About 0.1 percent of all newborn babies have serious damage from CMV infection occurring while they were developing in the uterus. About 50 percent of all transplant patients develop severe illnesses due to reactivation of dormant CMV infection. These illnesses have a high rate of serious complications and death.
Prevention
Prevention of CMV infection in the normal, healthy person involves good hand washing. Blood products can be screened or treated to insure that they do not contain CMV. In 2003, a new high-dose prophylactic (preventive) treatment was being tested to reduce CMV risk in stem cell transplant recipients.
KEY TERMS
Cervix —A small, cylindrical structure about an inch or so long and less than an inch around that makes up the lower part and neck of the uterus. The cervix separates the body and cavity of the uterus from the vagina.
Congenital —Present at birth.
Placenta —The organ that provides oxygen and nutrition from the mother to the unborn baby during pregnancy. The placenta is attached to the wall of the uterus and leads to the unborn baby via the umbilical cord.
Resources
BOOKS
"Cytomegalovirus Infection." In Obstetrics: Normal and Problem Pregnancies. Edited by Steven G. Gabbe. London: Churchill Livingstone, 2002.
Pass, Robert F. "Cytomegalovirus." In Principles and Practice of Pediatric Infectious Diseases, 2nd ed. Edited by Sarah S. Long et al. St. Louis, MO: Elsevier, 2003.
Stagno, Sergio. "Cytomegalovirus." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.
PERIODICALS
Fowler, Karen B., Sergio Stagno, and Robert F. Pass. "Maternal Immunity and Prevention of Congenital Cytomegalovirus Infection." Journal of the American Medical Association (February 26, 2003): 1008.
"High-Dose Acyclovir May Reduce Cytomegalovirus Infection Risk." Virus Weekly (July 15, 2003): 16.
"Novel Compound Highly Effective Against Cytomegalovirus Infection." AIDS Weekly (November 25, 2003): 17.
ORGANIZATIONS
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: <www.cdc.gov>.
March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. Web site: <www.modimes.org>.
Rosalyn Carson-DeWitt, MD Teresa G. Odle