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Background: Children attending child care centers have high rates of cytomegalovirus (CMV) excretion. Women exposed to such children have an increased risk of acquiring CMV infection, and primary infection places the offspring of such women at risk of congenital CMV infection. We studied family child care homes to determine if this child care alternative might represent a safe haven from CMV., Methods: One hundred thirty-two women providing care in their homes were studied using a latex agglutination method to determine the rate of CMV seropositivity at baseline. Women who were seronegative for CMV were then sampled prospectively at 6-month intervals between March 1991 and August 1994 to determine the annual rate of CMV acquisition. A point prevalence of CMV excretion in family homes was determined by sampling 106 children from 25 randomly selected homes. Cytomegalovirus isolates were compared by molecular analysis using polymerase chain reaction-based methods to identify transmission., Results: At baseline, 57.6% of the 132 providers were seropositive for CMV. Seropositive providers were more likely to be caring for toddlers (aged 1-2 years) (67% vs 46%; P=.02) and had worked in child care somewhat longer (median of 28.5 vs 21.5 months; P=.11). Using stepwise logistic regression, the strongest predictors of seropositivity at baseline were caring for children aged 1 to 2 years (odds ratio [OR] =2.37; P=.02) and number of months as a child care provider (OR= 1.17 for an increase of 24 months as provider; P=.08). Six or more years as a provider was highly associated with seropositivity (OR=3.27; P=.02). During follow-up, 5 of 51 seronegative providers seroconverted, yielding an annual infection rate of 6.8%. The point prevalence survey of children from the 25 homes (14 had seropositive providers) identified 8 CMV-excreting children. Three children in 1 home had indistinguishable isolates by polymerase chain reaction mapping. The provider seroconverted and excreted an isolate with a molecular profile indistinguishable from that of the children., Conclusions: The prevalence of CMV excretion is low among children attending child care homes (8% vs 15% in prior studies of child care centers; P=.07), and only 1 (20%) in 5 of the homes had CMV-excreting children. However, the overall CMV seroconversion rate of home child care providers was comparable to the rate observed among providers in child care centers. Families who use family home child care as an alternative to large child care centers are exposed to a low and unpredictable risk of CMV infection.

To determine factors that influence the occurrence of congenital cytomegalovirus (CMV) infection, the authors surveyed prospectively 8,254 infants born in eastern Iowa between October 1989 and June 1994. The authors conducted a case-control study to identify maternal risk factors, matching each CMV-infected infant with three uninfected infants according to hospital and date of birth. CMV strains were compared by using the polymerase chain reaction (PCR) to identify common sources of infection. Of the 7,229 infants cultured successfully for CMV, 35 (0.48%) were congenitally infected. Mothers of CMV-infected infants were more likely to be single (odds ratio (OR) = 3.05, p = 0.016), to work in sales (OR = 4.93, p = 0.008), or to be students (OR = 5.01, p = 0.017). Conversely, women who worked in health-care professions were less likely to have a congenitally infected infant (OR = 0.14, p = 0.049). PCR analysis indicated 27 distinct strains of CMV, but two groups of infants (two infants per group) excreted strains with indistinguishable molecular patterns. One of these pairs of infants had older siblings who attended the same child-care center during their mothers' pregnancies. The authors concluded that demographic and occupational factors influenced the risk of giving birth to an infant with congenital CMV infection. Many distinct CMV strains were identified, suggesting that major point source outbreaks had not occurred. Nonetheless, point source acquisition of CMV from child-care environments did account for some cases of congenital CMV infection in eastern Iowa.

Objective: To determine the frequency of reinfection with new cytomegalovirus (CMV) strains in children in group child-care environments., Methods: Ninety-two CMV strains isolated serially from children attending child care centers were analyzed. Strains were obtained from 1986 to 1994, from 37 children attending one of six centers in the area of Cedar Rapids and Iowa City, Iowa. The CMV isolates were analyzed by a polymerase chain reaction-based algorithm using primers for the a-sequence, glycoprotein B, and major immediate early (MIE) genes of human CMV. The a-sequence polymerase chain reaction products were compared on the basis of size, and products derived from glycoprotein B and MIE genes were compared according to restriction fragment length polymorphisms., Results: Children were between 8 months and 5 years 7 months of age at the time of CMV isolation. The number of isolates ranged from 2 to 6 per child, and the intervals between the first and last CMV isolation ranged from 11 weeks to more than 3 years. At least 7 (19%) of the 37 children had evidence of infection with more than one CMV strain. In six of these children, reinfection with distinct strains was confirmed by analysis of the MIE gene products of sequential CMV strains., Conclusions: Children who attend child care centers, like adults who are immunosuppressed or have multiple sexual partners, are at risk of being reinfected with distinct CMV strains.