Because polioviruses have nearly been eradicated, nonpolio enteroviruses remain an important cause of illness in the absence of vaccines and effective antiviral therapy.6,9 One enterovirus, EV71, recently caused 2 large epidemics with many fatal cases in Malaysia and Taiwan10,15 and was studied in Taiwan to delineate the seroepidemiologic background in which an EV71 epidemic occurred and the risk factors associated with EV71 infection and disease.