Seroprevalence of enterovirus 71 and no evidence of crossprotection of enterovirus 71 antibody against the other enteroviruses in kindergarten children in Taipei city.

Background/purpose: Enterovirus 71 (EV71) infection may cause severe neurological and cardiopulmonary complications, especially in preschool children. This study is to investigate the seroprevalence and seroconversion of EV71, and the crossprotection of EV71 antibody against other enteroviruses among kindergarteners.

Methods: Overall 228 children in a public kindergarten were enrolled during two academic years, 2006 and 2007, in Taipei, Taiwan and we measured their EV71 neutralizing antibody. When the participants had herpangina; hand, foot and mouth disease (HFMD); febrile illness or respiratory symptoms, throat swabs were sampled and processed for viral culture and enterovirus real-time reverse transcriptase polymerase chain reaction (RT-PCR). Questionnaires, completed by the participants' guardians, surveyed the history of allergy and annual incidence of symptoms related to enterovirus infection.

Results: Seropositive rates of EV71 were 20% (32/163) in 2006 and 6% (4/65) in 2007. The rate of EV71 seropositivity increased with age (p < 0.01) in 2006 but it did not differ between genders (p = 0.14). No seroconversion was observed from 2006 to 2007. Herpangina occurred in 64% of children with EV71 seropositivity and 48% of those without EV71 antibodies (p = 0.12). Non-71 enterovirus infection, confirmed by viral study, occurred in 53% (19/36) of the EV71-seropositive children and in 53% (102/192) of EV71-seronegative children (p = 0.89). No participants had EV71 infection during the study period.

Conclusion: EV71 did not frequently circulate in Taipei City from September 2006 to June 2008. Presence of EV71 neutralizing antibody was not associated with lower incidence of enterovirus infection caused by non-71 serotypes.