title: [Epidemiological characteristics of influenza outbreaks in China, 2005-2013].
abstract: OBJECTIVE
  To understand the epidemiological characteristics of influenza outbreaks in China from 2005 to 2013.
  
  
  METHODS
  The data of influenza-like illness outbreaks involving 10 or more cases were collected through Public Health Emergency Management Information System and National Influenza Surveillance Information System in China, and the influenza outbreaks were identified according to the laboratory detection results. Descriptive epidemiological analysis was conducted to understand the type/subtype of influenza virus and outbreak time, area, place and extent.
  
  
  RESULTS
  From 2005 to 2013, a total of 3 252 influenza-like illness outbreaks were reported in the mainland of China, in which 2 915 influenza outbreaks were laboratory confirmed, and influenza A (H1N1) pdm09 virus and influenza B virus were predominant. More influenza outbreaks were reported in the influenza A (H1N1) pandemic during 2009-2010. Influenza outbreaks mainly occurred during winter-spring, and less influenza outbreaks occurred in winter and summer vacations of schools. More influenza outbreaks were reported in southern provinces, accounting for 79% of the total. Influenza outbreaks mainly occurred in primary and middle schools, where 2 763 outbreaks were reported, accounting for 85% of the total. Average 30-99 people were involved in an outbreak.
  
  
  CONCLUSIONS
  A large number of influenza outbreaks occur during influenza season every year in China, the predominant virus type or subtype varies with season. Primary and middle schools are mainly affected by influenza outbreaks.
authors.affiliation: Key Laboratory of Surveillance and Early-warning for Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Surveillance and Early-warning for Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China; Email: fenglz@chinacdc.cn.
authors.forename: Luzhao
authors.initials: L
authors.lastname: Feng
authors.affiliation: Key Laboratory of Surveillance and Early-warning for Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Key Laboratory of Surveillance and Early-warning for Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Peng
authors.affiliation: Key Laboratory of Surveillance and Early-warning for Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yu
mesh_terms: D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D009981:Influenza B virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D011159:Population Surveillance; D012574:Schools; D012621:Seasons