CMV-The Most Dangerous Pregnancy Complication You Never Heard Of
CMV-The Most Dangerous Pregnancy Complication You Never Heard Of
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by Katie Allison Granju
Alison Schmidt of Guthrie, Minnesota remembers the day the disease Cytomegalovirus, commonly known as "CMV", first entered her consciousness. While in the last trimester of pregnancy with her daughter Jaime, Schmidt was in her obstetrician's office for her first and only routine ultrasound. Because the pregnancy had been problem-free, no one in the examining room expected to see anything out of the ordinary on the viewing monitor. Shockingly, the sonogram revealed a fetus with severe and clearly apparent brain damage. Schmidt and her husband were confused and devastated. "Nothing in the pregnancy had given us any reason to believe that there was a problem. I had been feeling fine and the obstetrician gave us no cause to worry," recalls Schmidt. The anxious parents were immediately referred to the University of Minnesota for follow-up testing. A decision was made to deliver the baby by cesarean section two weeks before the due date. Within hours after infant Jaime's birth, neonatologists were able to pinpoint the cause of her neurologic anomalies. Alison had passed the disease Cytomegalovirus on to her unborn daughter and the baby had become infected while still in the womb. Jaime had Congenital CMV. Like most expectant parents, the Schmidts had never heard of CMV before this frightening member of the herpes group of viruses complicated their own pregnancy. Health care providers who routinely warn pregnant women about the dangers of prenatal infections such as rubella and toxoplasmosis, fail to even mention the much more prevalent danger of CMV. According to Dr. Gail Demmler of the National CMV Registry at Baylor College of Medicine, CMV is the most common congenital viral infection in this country. Each year in the United States, 30,000 to 40,000 infants are born prenatally infected with the disease, meaning that the virus was transmitted from mother to unborn baby.This constitutes approximately 1% of all babies born in this country. Of these infected newborns, 3,000 to 4,000 are symptomatic at birth and up to 10% of this group die. An additional 4,500 to 6,000 babies with Congenital CMV, while seemingly without health problems at birth, go on to develop significant disabilities as they grow into early childhood. Researchers have now determined that Congenital CMV is the most common infectious cause of mental retardation in the United States. It leads to more cases of mental disability each year than does the much better-known Down Syndrome. Additionally, CMV holds another dubious distinction as the leading cause of non-hereditary, sensorineural deafness. It is thought to be a leading cause of deafness overall. Other common sequelae of Congenital CMV include blindness, intrauterine growth retardation (IUGR), jaundice, pneumonia, microcephaly and numerous others. In the case of Jaime Schmidt, now ten years old, Congenital CMV left her with microcephaly, cerebral palsy and a seizure disorder. The 5th grader uses a gastric feeding tube and a wheelchair. She is developmentally and physically delayed in all areas. Her parents have become very active in educating others about the largely unknown disease which affected their daughter's life so profoundly. "When I was told that I had passed CMV to Jaime prenatally, I had never heard of it and I had no idea that I had even been sick while I was pregnant. My sister, who has been an OB-GYN nurse for many years had barely heard of it. Jaime's pediatrician knew very little about it and allowed us to educate him. We had to learn so much ourselves," says Alison Schmidt. Anyone seeking more information about CMV will soon discover the puzzling contradictions of this insidious disease. Most Americans, both male and female, have been infected with CMV by the time they reach adulthood, with no ill effects. Some medical texts refer to CMV as "the silent virus" because for the vast majority of those persons who contract the illness, including those who are pregnant, there will be no symptoms to alert the carrier that she has an active infection. Instead, the virus will come and go with out any signs of its presence. A minority of persons who catch CMV will suffer from a mild to severe mononucleosis-like syndrome which can last for months. Still, for the average, otherwise healthy infant, child or adult, CMV presents no serious threat and a full recovery can be expected. The exceptions to this positive prognosis are immunocompromised individuals, such as persons infected with HIV, those undergoing chemotherapy, or transplant patients, for whom CMV can be deadly. Pregnant women are, however, the primary group for whom CMV offers a significant threat, as demonstrated by Alison Schmidt's experience. The disease is not dangerous to the woman who becomes infected, but to her fetus. Women who develop a CMV infection for the first time during pregnancy will pass that infection on to their unborn children approximately forty percent of the time.Women who have already had CMV prior to becoming pregnant are at little to no risk of becoming re-infected. Therefore, prior exposure to the virus is a woman's best defense against giving birth to a child with Congenital CMV. The odds of a woman reaching her childbearing years without natural immunity to this disease vary, depending on age, race and economic status. The older a woman is when she becomes pregnant, the more likely she is to have already had CMV. Economically disadvantaged women are, in general, more likely to have had CMV prior to adulthood. Only approximately 50-60% of college-educated, white women of childbearing age in this country currently carry protective immunity to CMV. Thus, it is this group which is most vulnerable to contracting a primary CMV infection while pregnant and passing the disease on to an unborn baby. According to Dr. Martha D. Yow of Baylor College of Medicine, a primary reason that young, American women of the middle and upper socio-economic classes have lower rates of natural CMV immunity is because many have had minimal contact with small children prior to becoming pregnant themselves . It is estimated that up to 80% of toddlers in the United States are shedding the CMV virus at any given time. Lack of contact with children prior to pregnancy can mean that a young woman has not had the opportunity to become exposed to the virus and obtain important immunologic protection prior to starting her own family. On the other hand, a pregnant woman who does not already carry CMV immunity should carefully avoid exposure to young children, particularly those in group care, where the disease is of almost epidemic proportions. Daycare centers and nursery schools provide an ideal environment for the spread of CMV, since the virus lives in bodily fluids such as feces, urine, saliva and mucous. Avoidance of the disease can be difficult if a pregnant mother without CMV immunity has other young children in group care. This was the case with Katherine Anderson, the mother of a toddler who was born with Congenital CMV. Unlike Alison Schmidt, Anderson had read a little bit about CMV prior to becoming pregnant. "The books I read said that the odds of catching this disease for the first time while pregnant were about the same as catching leprosy. I just didn't worry about it, especially since my midwife never mentioned anything about it when we talked about things that could be dangerous in pregnancy," says Anderson. Early in her second trimester, however, Anderson became ill with an unusually symptomatic case of CMV. It was later determined that her daughter, age 3, and who had never displayed any symptoms, had brought the virus home from daycare. Amniocentesis revealed that the pregnant Anderson had passed the CMV onto her unborn daughter. The baby was born shedding the virus. Today, at age two, this little girl has had only minor effects from her prenatal exposure. As lucky as Anderson feels about her daughter's good health, she knows that some symptoms of Congenital CMV, such as hearing loss, can develop several years after birth. "I wish that someone had told me about the risks of CMV before I became pregnant. As the pregnant mother of an older child in daycare, I would have been tested to see whether I was immune or not. They test for immunity to rubella. I believe that they should also test for immunity to CMV, since it is so much more common," Anderson says in frustration. The issue of whether pregnant women should be routinely tested for CMV immunity is not a settled one. Most experts believe that evaluation would be too costly to implement on a wide scale. Others, such as Dr. Martha D.Yow, disagree and recommend CMV screening for women who are planning a pregnancy, or as early in pregnancy as possible. Any woman who wishes to determine whether she is at risk of exposing her fetus to Congenital CMV can request that her doctor administer the blood test. Because the level of understanding and knowledge of CMV and its role in pregnancy is so poor among much of the United States health care community, a woman who seeks CMV testing may find that her health care provider is resistant to the idea. Researchers and physicians have been focusing most of their energy in the fight against CMV on development of a vaccine to prevent the disease. With an effective vaccine, women could be immunized against CMV before becoming pregnant. The National CMV Registry estimates that an effective vaccine could prevent severe, life-long disabilities for as many as 4,000 congenitally infected infants in the United States each year. Unfortunately, an acceptable vaccine is presently years away from general use. In the absence of an effective testing program or a vaccine, old-fashioned preventive measures are critical in the fight against Congenital CMV. An increase in the U.S. rate of naturally acquired immunity to the disease could play a very important role. Since breastmilk is a bodily fluid through which CMV is frequently passed, more breastfed babies would ensure a greater number of CMV-immune individuals in the general population. Healthy babies who contract CMV through breastfeeding are at no risk from the virus and are then immune from the disease for life. "It (breastfeeding) is nature's way of affording passive-active immunization:The infant receives small doses of CMV while being protected by antibody acquired from the mother," explains Dr. Yow. Women of childbearing age who are concerned about contracting CMV should practice excellent hygiene around all young children, since such a high proportion of little people excrete the virus. Needless to say, avoiding exposure to virus in one's own children can be tricky. CMV experts recommend to pregnant women or women who plan to become pregnant that they avoid kissing toddlers and preschoolers on the mouth, wash their hands after changing diapers, sterilize toys which have been "mouthed" and avoid sharing food or utensils with anyone. Pregnant women whose occupations involve working with young children are advised that studies have shown that the rate of CMV infection among daycare center employees is up to five times greater than in the general population. For a non CMV-immune pregnant woman who is employed in a child care center or preschool, her workplace can be a hazardous environment for her unborn baby. Because CMV is carried in blood and body fluids, it is considered a sexually transmitted disease. Women of childbearing age should be aware that unprotected sex with a partner who is shedding the virus can easily lead to infection. Considering the prevalence of the disease in the community at large and the commonly asymptomatic etiology of the virus, a woman has no reliable way of knowing whether her partner is infected. Women with new or multiple partners should be especially cautious. Parents, doctors or others with a desire to learn more about Congenital CMV can contact The National CMV Registry in Houston, TX. The Registry offers information on the disease and physicians who specialize in its treatment, a CMV Newsletter and a Parent-to-Parent national network for families with children affected by Congenital CMV. This organization is also at the forefront of tracking the disease and its spread across the United States. To contact the Registry: The National CMV Registry Clinical Care Center, Suite 1150 1102 Bates Street, MC 3-2371 Houston, TX 77030 Phone-(713)770-4387 Fax-(713) 770-4347 |
