title: A large outbreak of acute gastroenteritis caused by the human norovirus GII.17 strain at a university in Henan Province, China.
abstract: BACKGROUND
  Human noroviruses are a major cause of viral gastroenteritis and are the main etiological agents of acute gastroenteritis outbreaks. An increasing number of outbreaks and sporadic cases of norovirus have been reported in China in recent years. There was a large acute gastroenteritis outbreak at a university in Henan Province, China in the past five years. We want to identify the source, transmission routes of the outbreak by epidemiological investigation and laboratory testing in order to provide the effective control measures.
  
  
  METHODS
  The clinical cases were investigated, and analysed by descriptive epidemiological methods according to factors such as time, department, grade and so on. Samples were collected from clinical cases, healthy persons, the environment, water, and food at the university. These samples were tested for potential bacteria and viruses. The samples that tested positive for norovirus were selected for whole genome sequencing and the sequences were then analysed.
  
  
  RESULTS
  From 4 March to 3 April 2015, a total of 753 acute diarrhoea cases were reported at the university; the attack rate was 3.29%. The epidemic curve showed two peaks, with the main peak occurring between 10 and 20 March, accounting for 85.26% of reported cases. The rates of norovirus detection in samples from confirmed cases, people without symptoms, and environmental samples were 32.72%, 17.39%, and 9.17%, respectively. The phylogenetic analysis showed that the norovirus belonged to the genotype GII.17.
  
  
  CONCLUSIONS
  This is the largest and most severe outbreak caused by genotype GII.17 norovirus in recent years in China. The GII.17 viruses displayed high epidemic activity and have become a dominant strain in China since the winter of 2014, having replaced the previously dominant GII.4 Sydney 2012 strain.
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Xue-Yong
authors.initials: XY
authors.lastname: Huang
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Su
authors.affiliation: Nanyang City Center for Disease Control and Prevention, Nanyang, China.
authors.forename: Qian-Chao
authors.initials: QC
authors.lastname: Lu
authors.affiliation: Nanyang City Center for Disease Control and Prevention, Nanyang, China.
authors.forename: Shi-Zheng
authors.initials: SZ
authors.lastname: Li
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Jia-Yong
authors.initials: JY
authors.lastname: Zhao
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.
authors.forename: Meng-Lei
authors.initials: ML
authors.lastname: Li
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Shen
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Bai-Fan
authors.initials: BF
authors.lastname: Zhang
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Wang
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Yu-Jiao
authors.initials: YJ
authors.lastname: Mu
authors.affiliation: Program of Global Disease Detection, US Centers for Disease Control and Prevention, Beijing, China.
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Wu
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China.
authors.forename: Yan-Hua
authors.initials: YH
authors.lastname: Du
authors.affiliation: State Key Laboratory of Pathogens and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China.|Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pathogens and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China.|Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Wei-Jun
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: Program of Global Disease Detection, US Centers for Disease Control and Prevention, Beijing, China.|Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA.
authors.forename: John David
authors.initials: JD
authors.lastname: Klena
authors.affiliation: Henan Center for Disease Control and Prevention, Zhengzhou, China. bianlixu@163.com.|Henan Key Laboratory of Pathogenic Microorganisms, Zhengzhou, China. bianlixu@163.com.
authors.forename: Bian-Li
authors.initials: BL
authors.lastname: Xu
mesh_terms: D000208:Acute Disease; D000328:Adult; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D029322:Norovirus / Q000235:genetics*; D010802:Phylogeny; D014495:Universities; D055815:Young Adult
keywords: Acute gastroenteritis outbreak; China; Epidemiological investigation; Henan Province; Human norovirus; Phylogenetic analysis