The risks and benefits of cytomegalovirus transmission in child day care

CONGENITAL CYTOMEGALOVIRUS DISEASE Congenital infection with cytomegalovirus (CMV) is the leading viral cause of birth defects, and it is the major cause of severe, multiple birth defects in the US. Approximately 40 000 infants, or 1% of all births, are congenitally infected each year; 4000 of these infants are born with the severe defects that define the disease, and another 6000 will have developmental problems later in life. The remaining 30 000 infected infants have no recognizable damage. Defects frequently noted at birth include microcephaly, intracranial calcifications, hearing and vision damage, neurologic damage, and growth retardation. Developmental problems noted later may include partial loss of vision or hearing and learning disabilities.1 Infection of the fetus can result from both primary and recurrent maternal infection, although recurrent infections only rarely produce recognizable congenital disease with severe consequences. This distinction is important because public health intervention is based entirely on preventing primary CMV infection during pregnancy. Cytomegalovirus The cause of this damage, CMV, is a common virus that produces a life-long infection. Reactivation of earlier infections is possible, as is reinfection with a different strain of the virus. Usually, both primary and recurrent infections result in either inapparent or mild illness, although some adolescents and adults may develop mononucleosis. In some persons with an impaired immune system, however, infection can be devastating and life-threatening. Persons with AIDS, some transplant patients, cancer patients, and fetuses lack the ability to control infection with CMV. Person-to-person transmission of the virus occurs through bodily fluids including breast milk, semen and vaginal secretions, blood, and particularly, saliva and urine.