Transmission of human herpesvirus 7 through multigenerational families in the same household

background. Human herpesvirus 7 (HHV-7) closely resembles Hhv-6 and to a lesser degree cytomegalovirus. Hhv-7 infection is usually acquired during early childhood. Primary infection can cause a roseola-like illness but in most cases it is only mildly symptomatic. The majority of adults are seropositive and in contrast to Hhv-6 and cytomegalovirus infection, they continue to secrete the virus in their saliva for many years. The mode of intrafamilial transmission of this virus is not well-understood, methods. Saliva samples for virus isolation and Dna restriction analysis were obtained from all 47 members of 6 Japanese families, including 4 families with 3 generations living in the same household. Results. Hhv-7 was isolated from 43 of 47 saliva samples collected from children and adult members of the 6 families (91.5%). In one family the restriction patterns of the maternal grand-mother, the mother and the children were similar, and the patterns of the paternal grand-mother and the father were similar. In another family the patterns of the father and 5 of 6 children were similar, and those of the mother and the other child were Similar. Altogether similar Hhv-7 restriction profiles with his or her mother were found in 48% of offspring, and similar profiles with his or her father were found in 28% of offspring, conclusions. The results strongly suggested horizontal transmission of Hhv-7 from grand- parents to parents to children through close contact within a household. Either parent could transmit Hhv-7 to the children.