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Human Infection with Avian Influenza A(H7N9) Virus: Situation and Response, China Zijian FENG Center for Public Health Emergency Center Chinese Center.

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Presentation on theme: "Human Infection with Avian Influenza A(H7N9) Virus: Situation and Response, China Zijian FENG Center for Public Health Emergency Center Chinese Center."— Presentation transcript:

1 Human Infection with Avian Influenza A(H7N9) Virus: Situation and Response, China Zijian FENG Center for Public Health Emergency Center Chinese Center for Disease Control and Prevention

2 Overview of human H7N9 cases reported in Mainland China One confirmed case was reported in Taiwan ( onset date: Apr 12) and he returned to Taipei from Suzhou via Shanghai 3 days before date of onset ProvinceNo. of casesDeath % Zhejiang481124 Shanghai331855 Jiangsu28932 Jiangxi6117 Fujian5120 Anhui4250 Henan4125 Hunan2150 Shandong200 Beijing200 Hebei100 Guangdong100 Total13644 33

3 Epidemic curve of human H7N9 cases in Mainland China Onset date No. of cases Hebei Jiangxi Fujian Shandong Hunan Beijing Henan Anhui Jiangsu Zhejiang Shanghai 3 stages of the epidemic : Feb 19 ~ Mar 27, Sporadic cases in Shanghai, Zhejiang, Jiangsu and Anhui; Mar 28 ~ Apr 18, Increasing stage, spread to 10 provinces; Apr 19 ~ Aug10, Declined stage, sporadic cases.

4 Human H7N9 cases and deaths by sex and age (as of 10 Aug 2013 , 134 cases and 44 deaths) Sex: Male 70%, Female 30% Age: median 62 yrs , range: 2 ~ 91yrs Deaths

5 Virological features of H7N9 Virus: HA gene:  Similar to H7N3 isolated from duck in Zhejiang NA gene:  Similar to H7N9 isolated from wild bird in South Korea All six internal genes:  Shared highest similarity with A/brambling/Beijing/16/2012-like viruses (H9N2) Gao R, et al. N Engl J Med, 2013, 368(20):1888-97.

6 Serology study of H7N9 virus Sera collected from 1544 poultry workers from Shanghai, Zhejiang, Jiangsu and Anhui during Jan-Nov 2012, all tested negative for H7N9 specific antibody by MN Sera from 90 persons (30 children,30 adults and 30 elderly) before and after influenza vaccination for 2012-13 season, no pre-existing immunity for H7N9, no cross-reactive antibody against H7N9 virus Bai T, Zhou J, Shu Y. N Engl J Med,2013,368(24):2339-2340; Zhou J, Wang D, Gao R, et al. Nature,2013.

7 Serological study in seven provinces (as of Aug 14) No. serum HI positive ( titer≥160 ) ( % ) MN( titer ≥20) ( % ) Close contacts ( HCW ) 480(0)0(0) 0(0)0(0) Other close contacts 4836(1.24)2 ( 0.41 ) Poultry workers** 12250(0)0(0) 0(0)0(0) Note : study provinces included Henan, Shanghai, Hunan, Fujian, Shandong, Anhui, Jiangxi **269 serum specimens from poultry workers in Shanghai were excluded.

8 Exposure history of H7N9 cases ( N=133 ) Types of ExposureNumber (%) Exposed to poultry or live market, n/N (%) 92/133(69%) Exposed to mammal (pig, dog, cat, rabbit ) 8/133(6%) Poultry workers, n(%) 8/133(6%) Exposure history of one case who was retrospectively diagnosed and reported on July 2 in Jiangsu, is unknown (onset date: Apr 25)

9 Risk factors of H7N9 infection Case-control study in Jiangsu –25 cases, 93 controls; age, sex, and location were matched –Risk factors: contact with poultry, birds (pigeon, quail) within 2 weeks before illness onset; with underlying chronic diseases ( exclude hypertension); environment exposure (visiting live market) National case-control study –89 cases, 340 controls; age, sex, and location were matched –Risk factors: visiting live poultry market, direct/indirect contact with poultry, backyard poultry death, Obesity, COPD, long-term taking immunosuppressive medication Ai J, Huang Y, Xu K, et al. Euro Surveill. 2013;18(26):pii=20510.

10 Case-Control Study of Risk factors associated with H7N9 virus infections (89 cases, 340 controls)


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