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Int. J. Environ. Res. Public Health 2017, 14(3), 263; doi:10.3390/ijerph14030263

Comparative Epidemiology of Human Fatal Infections with Novel, High (H5N6 and H5N1) and Low (H7N9 and H9N2) Pathogenicity Avian Influenza A Viruses

7,* and 4,*
Department of Respiratory Medicine, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
Department of Medicine, Jinxi Petrochemical Hospital, Huludao 125001, China
National Research Center for Wildlife Borne Diseases, Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
Department of Infectious Diseases and Key Lab of Vaccine against Hemorrhagic Fever with Renal Syndrome, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
Department of Infectious Diseases, Shanghai Municipal Centre for Disease Control and Prevention, Shanghai 200336, China
Center for Geographic Information Science, Research Centre for Humanities and Social Science, Academia Sinica, Taipei 115, Taiwan
School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
Zu-Qun Wu, Yi Zhang and Na Zhao equally contributed to this work.
Authors to whom correspondence should be addressed.
Academic Editor: Paul B. Tchounwou
Received: 18 January 2017 / Revised: 20 February 2017 / Accepted: 28 February 2017 / Published: 4 March 2017
(This article belongs to the Section Global Health)
View Full-Text   |   Download PDF [3101 KB, uploaded 4 March 2017]   |  


This study aimed to assess the mortality risks for human infection with high (HPAI) and low (LPAI) pathogenicity avian influenza viruses. The HPAI case fatality rate (CFR) was far higher than the LPAI CFR [66.0% (293/444) vs. 68.75% (11/16) vs. 40.4% (265/656) vs. 0.0% (0/18) in the cases with H5N1, H5N6, H7N9, and H9N2 viruses, respectively; p < 0.001]. Similarly, the CFR of the index cases was greater than the secondary cases with H5N1 [100% (43/43) vs. 43.3% (42/97), p < 0.001]. Old age [22.5 vs. 17 years for H5N1, p = 0.018; 61 vs. 49 years for H7H9, p < 0.001], concurrent diseases [18.8% (15/80) vs. 8.33% (9/108) for H5N1, p = 0.046; 58.6% (156/266) vs. 34.8% (135/388) for H7H9, p < 0.001], delayed confirmation [13 vs. 6 days for H5N1, p < 0.001; 10 vs. 8 days for H7N9, p = 0.011] in the fatalities and survivors, were risk factors for deaths. With regard to the H5N1 clusters, exposure to poultry [67.4% (29/43) vs. 45.2% (19/42), p = 0.039] was the higher risk for the primary than the secondary deaths. In conclusion, old age, comorbidities, delayed confirmation, along with poultry exposure are the major risks contributing to fatal outcomes in human HPAI and LPAI infections. View Full-Text
Keywords: influenza virus; endemic infection; horizontal transmission; seasonal incidence influenza virus; endemic infection; horizontal transmission; seasonal incidence

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Wu, Z.-Q.; Zhang, Y.; Zhao, N.; Yu, Z.; Pan, H.; Chan, T.-C.; Zhang, Z.-R.; Liu, S.-L. Comparative Epidemiology of Human Fatal Infections with Novel, High (H5N6 and H5N1) and Low (H7N9 and H9N2) Pathogenicity Avian Influenza A Viruses. Int. J. Environ. Res. Public Health 2017, 14, 263.

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