title: A family cluster of three confirmed cases infected with avian influenza A (H7N9) virus in Zhejiang Province of China.
abstract: BACKGROUND
  A total of 453 laboratory-confirmed cases infected with avian influenza A (H7N9) virus (including 175 deaths) have been reported till October 2,2014, of which 30.68% (139/453) of the cases were identified from Zhejiang Province. We describe the largest reported cluster of virologically confirmed H7N9 cases, comprised by a fatal Index case and two mild secondary cases.
  
  
  METHODS
  A retrospective investigation was conducted in January of 2014. Three confirmed cases, their close contacts, and relevant environments samples were tested by real-time reverse transcriptase-polymerase chain reaction (RT-PCR), viral culture, and sequencing. Serum samples were tested by haemagglutination inhibition (HI) assay.
  
  
  RESULTS
  The Index case, a 49-year-old farmer with type II diabetes, who lived with his daughter (Case 2, aged 24) and wife (Case 3, aged 43) and his son-in-law (H7N9 negative). The Index case and Case 3 worked daily in a live bird market. Onset of illness in Index case occurred in January 13, 2014 and subsequently, he died of multi-organ failure on January 20. Case 2 presented with mild symptoms on January 20 following frequent unprotected bed-side care of the Index case between January 14 to 19, and exposed to live bird market on January 17. Case 3 became unwell on January 23 after providing bedside care to the Index case on January 17 to 18, and following the contact with Case 2 during January 21 to 22 at the funeral of the Index case. The two secondary cases were discharged on February 2 and 5 separately after early treatment with antiviral medication. Four virus strains were isolated and genome analyses showed 99.6 ~100% genetic homology, with two amino mutations (V192I in NS and V280A in NP). 42% (11/26) of environmental samples collected in January were H7N9 positive. Twenty-five close contacts remained well and were negative for H7N9 infection by RT-PCR and HI assay.
  
  
  CONCLUSIONS
  In the present study, the Index case was infected from a live bird market while the two secondary cases were infected by the Index case during unprotected exposure. This family cluster is, therefore, compatible with non-sustained person-to-person transmission of avian influenza A/H7N9.
authors.affiliation: Hangzhou Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. dh.dhua999@163.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Ding
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. yinch@cdc.zj.cn.
authors.forename: Yin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. zhy@cdc.zj.cn.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Oxford University Clinical Research Unit-Wellcome Trust Major Overseas Programme, Hu Chi Minh City, Vietnam. peter.horby@ndm.ox.ac.uk.|Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, Oxford, United Kingdom. peter.horby@ndm.ox.ac.uk.|Singapore Infectious Disease Initiative, Singapore City, Singapore. peter.horby@ndm.ox.ac.uk.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Horby
authors.affiliation: XiaoShan District Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. fenjuanwang@163.com.
authors.forename: Fenjuan
authors.initials: F
authors.lastname: Wang
authors.affiliation: ShangCheng District Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. 17407128@qq.com.
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Hu
authors.affiliation: Hangzhou Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. bluefantasia@163.com.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Yang
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. hymao@cdc.zj.cn.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Mao
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. swqin@cdc.zj.cn.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Qin
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. chlchai@cdc.zj.cn.
authors.forename: Chengliang
authors.initials: C
authors.lastname: Chai
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. liushelan@126.com.
authors.forename: Shelan
authors.initials: S
authors.lastname: Liu
authors.affiliation: Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, Zhejiang Province, China. enfchen@cdc.zj.cn.|Department of Infectious Diseases, Zhejiang Provincial Center for Disease Control and Prevention, 3399 Binsheng Road, Binjiang District, Hangzhou, Zhejiang, 310051, China. enfchen@cdc.zj.cn.
authors.forename: Enfu
authors.initials: E
authors.lastname: Chen
authors.affiliation: Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, No. 155 Changbai Road, Changping District, Beijing, China. yuhj@chinacdc.cn.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yu
mesh_terms: D000328:Adult; D000818:Animals; D001717:Birds; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D016358:Contact Tracing; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005190:Family; D000067565:Farmers; D005260:Female; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000635:transmission*; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D012189:Retrospective Studies; D055815:Young Adult