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. 2016 Jul;16(7):e108-e118.
doi: 10.1016/S1473-3099(16)00153-5. Epub 2016 May 17.

Global epidemiology of avian influenza A H5N1 virus infection in humans, 1997-2015: a systematic review of individual case data

Shengjie Lai  1 , Ying Qin  2 , Benjamin J Cowling  3 , Xiang Ren  2 , Nicola A Wardrop  4 , Marius Gilbert  5 , Tim K Tsang  3 , Peng Wu  3 , Luzhao Feng  2 , Hui Jiang  2 , Zhibin Peng  2 , Jiandong Zheng  2 , Qiaohong Liao  2 , Sa Li  2 , Peter W Horby  6 , Jeremy J Farrar  7 , George F Gao  8 , Andrew J Tatem  9 , Hongjie Yu  10
Affiliations

Global epidemiology of avian influenza A H5N1 virus infection in humans, 1997-2015: a systematic review of individual case data

Shengjie Lai et al. Lancet Infect Dis. 2016 Jul.

Abstract

Avian influenza A H5N1 viruses have caused many, typically severe, human infections since the first human case was reported in 1997. However, no comprehensive epidemiological analysis of global human cases of H5N1 from 1997 to 2015 exists. Moreover, few studies have examined in detail the changing epidemiology of human H5N1 cases in Egypt, especially given the outbreaks since November, 2014, which have the highest number of cases ever reported worldwide in a similar period. Data on individual patients were collated from different sources using a systematic approach to describe the global epidemiology of 907 human H5N1 cases between May, 1997, and April, 2015. The number of affected countries rose between 2003 and 2008, with expansion from east and southeast Asia, then to west Asia and Africa. Most cases (67·2%) occurred from December to March, and the overall case-fatality risk was 483 (53·5%) of 903 cases which varied across geographical regions. Although the incidence in Egypt has increased dramatically since November, 2014, compared with the cases beforehand, there were no significant differences in the fatality risk, history of exposure to poultry, history of patient contact, and time from onset to hospital admission in the recent cases.

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Conflict of interest statement

Conflicts of interest

BJC has received research funding from MedImmune Inc. and Sanofi Pasteur, and consults for Crucell NV. The authors report no other potential conflicts of interest.

Figures

Figure 1
Figure 1. Flow chart of study selection and collection of individual case data on H5N1 cases
Figure 2
Figure 2. The geographic distribution of human cases with H5N1 virus infection by outcome, May 1997–April 2015 (n=907)
The data for China includes the cases reported by mainland China (52 cases) and Hong Kong SAR (23 cases).
Figure 3
Figure 3. Epidemic curve of human cases with H5N1 virus infection by region, May 1997–April 2015
(A) The epidemic curve of H5N1 human cases reported globally (884 cases). (B) East and Southeast Asia (484 cases) includes Indonesia (187), Viet Nam (134), Cambodia (58), mainland China (52), Thailand (27), Hong Kong SAR (23), Laos (2), and Myanmar (1). (C) North Africa (363 cases) includes Egypt (363). Twenty-three cases with unknown month of illness (21 cases of Indonesia in 2009 and two cases of Turkey in 2006) are excluded from this epidemic curve.
Figure 4
Figure 4. The age distribution of human cases with H5N1 virus infection by gender, geographic regions and outcome, May 1997–April 2015
(A) The age distribution of all cases by male (n=401) and female (n=476). (B) The age distribution of all cases by death (n=463) and survive (n=416). (C) The age distribution of survive cases by North Africa (n=245), East and Southeast Asia (n=152). (D) The age distribution of death cases by North Africa (n=116), East and Southeast Asia (n=329). (E) The age distribution of survive cases in Egypt before (n=114) and since 1 November 2014 (n=131). (F) The age distribution of death cases in Egypt before (n=64) and since 1 November 2014 (n=52).
See this image and copyright information in PMC

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