Phylogenetic analysis of enterovirus 71 strains isolated during linked epidemics in Malaysia, Singapore, and Western Australia

Enterovirus 71 (EV71) is a frequent cause of hand, foot, and mouth disease (HFMD) epidemics associated with severe neurological sequelae in a small pr oportion of cases. There has been a significant increase in EV71 epidemic a ctivity throughout the Asia-Pacific region since 1997. Recent HFMD epidemic s in this region have been associated with a severe form of brainstem encep halitis associated with pulmonary edema and high case fatality rates. In th is study, we show that four genetic lineages of EV71 have been prevalent in the Asia-Pacific region since 1997, including two previously undescribed g enogroups (B3 and B4). Furthermore, we show that viruses belonging to genog roups B3 and B4 have circulated endemically in Southeast Asia during this p eriod and have been the primary cause of several large HFMD or encephalitis epidemics in Malaysia, Singapore, and Western Australia.