Cytomegalovirus (CMV) infection, the most commonly recognized congenital viral infection among humans, can severely damage the nervous system of the developing fetus. Several studies, including those of the co- investigators', have shown that CMV frequently infects young children in group day care. Parents of such children appear to be at significant risk of CMV acquisition. In addition, our preliminary studies suggest that women who work with young children in group day care may also be at risk. These observations indicate that children in group day care who excrete CMV may significantly influence the epidemiology of congenital CMV infection. In this proposal we will extend our ongoing studies regarding the epidemiology of CMV infection among seronegative women who have contact with young children. We intend to test the hypothesis that the incidence of congenital CMV infection is increased among the offspring of mothers and/or caretakers of children in group day care. We will determine 1) whether maternal contact with a child in day care is a significant risk factor for delivering a CMV-infected infant and whether CMV infection, in this instance, is the result of vertical transmission from child to mother to fetus; 2) whether the occurrence of symptomatic congenital CMV infection is influenced by the high prevalence of CMV infection among children in group day care; and 3) whether the risk of CMV infection is increased among day care providers compared with controls. This will be accomplished be determining the incidence of congenital CMV infection (assessed by CMV viruria) among 15,000 Iowa newborns over a 5 year period and relating congenital infection to parental contact with a child in day care. Transmission will be assessed by restriction enzyme analysis of CMV isolates from parents, sibling, and caretakers. The Iowa Birth Defects Registry will be used to identify infants/children with suspected symptomatic congenital CMV infants to parental contact with children in day care will be assessed via questionnaire. The rates of seroconversion among two groups of day care providers will be assessed via serial serologic examinations using a passive latex agglutination method.