title: Incidence rates of enterovirus 71 infections in young children during a nationwide epidemic in Taiwan, 2008-09.
abstract: OBJECTIVE
  Enterovirus 71 (EV71) is causing life-threatening outbreaks in tropical Asia. In Taiwan and other tropical Asian countries, although nationwide EV71 epidemics occur cyclically, age-specific incidence rates of EV71 infections that are critical to estimate disease burden and design vaccine trials are not clear. A nationwide EV71 epidemic occurred in 2008-09 in Taiwan, which provided a unique opportunity to estimate age-specific incidence rates of EV71 infections.
  
  
  METHODS
  We prospectively recruited 749 healthy neonates and conducted follow-ups from June 2006 to December 2009. Sera were obtained from participants at 0, 6, 12, 24, and 36 months of age for measuring EV71 neutralizing antibody titers. If the participants developed suspected enterovirus illnesses, throat swabs were collected for virus isolation.
  
  
  RESULTS
  We detected 28 EV71 infections including 20 symptomatic and 8 asymptomatic infections. Age-specific incidence rates of EV71 infection increased from 1.71 per 100 person-years at 0-6 months of age to 4.09, 5.74, and 4.97 per 100 person-years at 7-12, 13-24, and 25-36 months of age, respectively. Cumulative incidence rate was 15.15 per 100 persons by 36 months of age, respectively.
  
  
  CONCLUSIONS
  Risk of EV71 infections in Taiwan increased after 6 months of age during EV71 epidemics. The cumulative incidence rate was 15% by 36 months of age, and 29% of EV71 infections were asymptomatic in young children.
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan. minshi.lee@hotmail.com
authors.forename: Min-Shi
authors.initials: MS
authors.lastname: Lee
authors.forename: Pai-Shan
authors.initials: PS
authors.lastname: Chiang
authors.forename: Shu-Ting
authors.initials: ST
authors.lastname: Luo
authors.forename: Mei-Liang
authors.initials: ML
authors.lastname: Huang
authors.forename: Guan-Yuan
authors.initials: GY
authors.lastname: Liou
authors.forename: Kuo-Chien
authors.initials: KC
authors.lastname: Tsao
authors.forename: Tzou-Yien
authors.initials: TY
authors.lastname: Lin
mesh_terms: D000367:Age Factors; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D058070:Asymptomatic Diseases / Q000453:epidemiology; D002675:Child, Preschool; D015331:Cohort Studies; D004196:Disease Outbreaks; D029821:Enterovirus A, Human / Q000302:isolation & purification*; D004769:Enterovirus Infections / Q000453:epidemiology* / Q000821:virology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D011247:Pregnancy; D011446:Prospective Studies; D013624:Taiwan / Q000453:epidemiology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral