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.