Molecular epidemiology of cytomegalovirus: evidence for viral transmission to parents from children infected at a day care center.

Based on an analysis of the DNA of 16 cytomegalovirus (CMV) isolates obtained from children attending a day care center, we had previously determined that one group of 7 and another group of 4 children were shedding common viral strains. Because the DNA of each epidemiologically unrelated strain of CMV is unique, at least 9 of these 11 children acquired CMV from other children attending the day care center. In order to assess CMV transmission between these 11 viruric children and their parents, the parents were surveyed for CMV infections. Nine of the 10 mothers of the viruric children were seropositive but only 12 of 33 mothers of nonviruric children at the day center were seropositive (P less than 0.007), Fisher's exact test). Urine and saliva specimens from each parent of the viruric children were cultured for CMV. Three parents (a father and two pregnant mothers) were excreting virus. When analyzed with restriction endonucleases, the viral DNA of the isolate from each parent was identical to that from the virus excreted by the child and from the virus excreted by other children at the day care center. The results of this survey indicate that CMV was frequently transmitted to parents from children who had acquired the virus at the day care center.