Herpes simplex type 1 infections in group day care.

To characterize patterns of herpes simplex virus type 1 infection, illness and transmission among children in group day care, the data for 115 children who had been followed longitudinally from early infancy in a research day care center were examined. By 5 years of age 37% of study children had evidence of herpes simplex virus type 1 infection as demonstrated by virus isolation and/or seroconversion. The incidence of infection was highest among children 1 to 2 years old. Four small clusters of primary infections were observed over the 12-year study period but no cluster involved more than 6 children. Fifty-five percent of primary infections occurred during these small outbreaks; the remainder were sporadic. Gingivostomatitis was observed in 26% of children with primary culture-proved infections; no child with infection identified solely by serologic means had a history of gingivostomatitis. The occurrence of gingivostomatitis did not appear to be associated with increased transmission of herpes simplex virus type 1 infection in this day-care setting.