Phylogenetic analysis of EV71 isolates in Japan revealed multiple subgenogroups, indicating frequent importation from surrounding countries.
Phylogenetic analysis of 45 enterovirus 71 (EV71) isolates for 6 years in Yamagata, Japan, clarified that the annual outbreak of hand-foot-and-mouth disease was due to four genetically distinct subgenogroups, including a novel "B5." Our results suggest that the importation of EV71 from surrounding countries has had a major epidemiological impact on the local community used in our study.
Mizuta et al. (2005) studied this question.