Rotavirus in infant-toddler day care centers: epidemiology relevant to disease control strategies.

A 15-month prospective longitudinal study of diarrhea and rotavirus (RV) infection was conducted concurrently in infants and toddlers in day care centers (DCCs) and in a large pediatric clinic in Houston. The mean number of children in the DCCs was 223; the diarrhea rate during the first 12 months was 2.62 episodes per child-year. Rotavirus accounted for approximately 10% of the total episodes of diarrhea in the pediatric clinic and DCC populations, but 50% during the winter months. The occurrence of RV in the DCCs paralleled that seen in the pediatric clinic. The annual rate of RV infection in DCCs was 0.55 episodes per child-year, with diarrhea occurring in only 40% of the episodes (0.22 episodes per child-year). There were 45 diarrhea outbreaks in DCCs, for a mean of 3.8 per center per year; nine of these outbreaks were associated with RV. Polyacrylamide gel electrophoresis of RNA genome patterns of RV strains from eight of these outbreaks showed that in seven outbreaks a single strain was identified in children in that DCC, whereas multiple strains were identified simultaneously in the community. The age distributions of symptomatic and asymptomatic RV infections in DCC study children were not significantly different. In symptomatic RV-infected children in DCCs, 42% had RV identified in stool specimens within 2 days before diarrhea occurred. Thirty-eight DCC children had more than one episode of RV infection, but only five had two symptomatic RV infections. Diarrhea caused by RV is common in children in DCCs, often occurs in outbreaks due to the same strain, and parallels disease in the community; asymptomatic RV infection is also common in children in DCCs.