Cytomegalovirus transmission in a Midwest day care center: possible relationship to child care practices.

The epidemiology of cytomegalovirus (CMV) infection and transmission in a large Iowa day care center was studied. Over the 9 months of the study the overall CMV prevalence rates were 21% to 22%, with rates as high as 71% in toddlers. Titers of CMV in the urine or saliva of infected children were as high as 3 X 10(4) plaque-forming units of CMV per milliliter, similar to titers of CMV observed in some congenitally infected infants. Restriction enzyme analysis of CMV isolates from children in the center demonstrated two major clusters with similar patterns, one among 2- and 3-year-old children and another among infants. The clustering of similar CMV isolates among nonambulatory infants suggests that child care or hygienic practices may contribute to the spread of CMV infection in day care centers. Furthermore, the relatively high prevalence of CMV excretion in this center and the low seropositivity rates to CMV among adults in Iowa suggest that adults in the Midwest who have contact with children in day care centers may be at risk for primary CMV infection.