title: Differences in the epidemiology and virology of mild, severe and fatal human infections with avian influenza A (H7N9) virus.
abstract: A novel avian influenza A (H7N9) virus caused 5-10 % mild and 30.5 % fatal human infections as of December 10, 2015. In order to investigate the reason for the higher rate of fatal outcome of this infection, this study compared the molecular epidemiology and virology of avian influenza A (H7N9) viruses from mild (N = 14), severe (N = 50) and fatal (N = 35) cases, as well as from non-human hosts (N = 73). The epidemiological results showed that the average age of the people in the mild, severe and fatal groups was 27.6, 52 and 62 years old, respectively (p < 0.001). Males accounted for 42.9 % (6/14), 58.0 % (29/50), and 74.3 % (26/35) of cases in the mild, severe and fatal group respectively (p = 0.094). Median days from onset to start of antiviral treatment were 2, 5 and 7 days in the mild, severe and fatal group, respectively (p = 0.002). The median time from onset to discharge/death was 12, 40 and 19 days in the mild, severe and fatal group, respectively (p < 0.001). Analysis of whole genome sequences showed that PB2 (E627K), NA (R294K) and PA (V100A) mutations were markedly associated with an increased fatality rate, while HA (N276D) and PB2 (N559T) mutations were clearly related to mild cases. There were no differences in the genotypes, adaptation to mammalian hosts, and genetic identity between the three types of infection. In conclusion, advanced age and delayed confirmation of diagnosis and antiviral intervention were risk factors for death. Furthermore, PB2 (E627K), NA (R294K) and PA (V100A) mutations might contribute to a fatal outcome in human H7N9 infection.
authors.affiliation: Department of Gastroenterology, The 421 Hospital of Chinese People's Liberation Army, Guangzhou, People's Republic of China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Sha
authors.affiliation: Department of Senior Cadres, The 421 Hospital of Chinese People's Liberation Army, Guangzhou, People's Republic of China.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Chen
authors.affiliation: Pharmacy Department, The 421 Hospital of Chinese People's Liberation Army, Guangzhou, People's Republic of China.
authors.forename: Yajin
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People's Republic of China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, People's Republic of China.
authors.forename: Zuqun
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Oncology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Dong
authors.initials: D
authors.lastname: Ying
authors.affiliation: School of Public Health, Shanghai Jiao Tong University, 227 South Chongqing Road, Huangpu District, Shanghai, 200025, People's Republic of China. zhangzhiruo@sjtu.edu.cn.
authors.forename: Zhiruo
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Infectious Diseases, Zhejiang Provincial Centre for Disease Control and Prevention, 3399 Binsheng Road, Binjiang District, Hangzhou, 310051, Zhejiang Province, People's Republic of China. liushelan@126.com.
authors.forename: Shelan
authors.initials: S
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality / Q000821:virology; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D012367:RNA, Viral