Dataset Information

Epidemiology of human infections with avian influenza A(H7N9) virus in China.

ABSTRACT: BACKGROUND:The first identified cases of avian influenza A(H7N9) virus infection in humans occurred in China during February and March 2013. We analyzed data obtained from field investigations to describe the epidemiologic characteristics of H7N9 cases in China identified as of December 1, 2013. METHODS:Field investigations were conducted for each confirmed case of H7N9 virus infection. A patient was considered to have a confirmed case if the presence of the H7N9 virus was verified by means of real-time reverse-transcriptase-polymerase-chain-reaction assay (RT-PCR), viral isolation, or serologic testing. Information on demographic characteristics, exposure history, and illness timelines was obtained from patients with confirmed cases. Close contacts were monitored for 7 days for symptoms of illness. Throat swabs were obtained from contacts in whom symptoms developed and were tested for the presence of the H7N9 virus by means of real-time RT-PCR. RESULTS:Among 139 persons with confirmed H7N9 virus infection, the median age was 61 years (range, 2 to 91), 71% were male, and 73% were urban residents. Confirmed cases occurred in 12 areas of China. Nine persons were poultry workers, and of 131 persons with available data, 82% had a history of exposure to live animals, including chickens (82%). A total of 137 persons (99%) were hospitalized, 125 (90%) had pneumonia or respiratory failure, and 65 of 103 with available data (63%) were admitted to an intensive care unit. A total of 47 persons (34%) died in the hospital after a median duration of illness of 21 days, 88 were discharged from the hospital, and 2 remain hospitalized in critical condition; 2 patients were not admitted to a hospital. In four family clusters, human-to-human transmission of H7N9 virus could not be ruled out. Excluding secondary cases in clusters, 2675 close contacts of case patients completed the monitoring period; respiratory symptoms developed in 28 of them (1%); all tested negative for H7N9 virus. CONCLUSIONS:Most persons with confirmed H7N9 virus infection had severe lower respiratory tract illness, were epidemiologically unrelated, and had a history of recent exposure to poultry. However, limited, nonsustained human-to-human H7N9 virus transmission could not be ruled out in four families.

SUBMITTER: Li Q

PROVIDER: S-EPMC6652192 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Epidemiology of human infections with avian influenza A(H7N9) virus in China.

Li Qun Q Zhou Lei L Zhou Minghao M Chen Zhiping Z Li Furong F Wu Huanyu H Xiang Nijuan N Chen Enfu E Tang Fenyang F Wang Dayan D Meng Ling L Hong Zhiheng Z Tu Wenxiao W Cao Yang Y Li Leilei L Ding Fan F Liu Bo B Wang Mei M Xie Rongheng R Gao Rongbao R Li Xiaodan X Bai Tian T Zou Shumei S He Jun J Hu Jiayu J Xu Yangting Y Chai Chengliang C Wang Shiwen S Gao Yongjun Y Jin Lianmei L Zhang Yanping Y Luo Huiming H Yu Hongjie H He Jianfeng J Li Qi Q Wang Xianjun X Gao Lidong L Pang Xinghuo X Liu Guohua G Yan Yansheng Y Yuan Hui H Shu Yuelong Y Yang Weizhong W Wang Yu Y Wu Fan F Uyeki Timothy M TM Feng Zijian Z

The New England journal of medicine 20130424 6

<h4>Background</h4>The first identified cases of avian influenza A(H7N9) virus infection in humans occurred in China during February and March 2013. We analyzed data obtained from field investigations to describe the epidemiologic characteristics of H7N9 cases in China identified as of December 1, 2013.<h4>Methods</h4>Field investigations were conducted for each confirmed case of H7N9 virus infection. A patient was considered to have a confirmed case if the presence of the H7N9 virus was verifie ...[more]

PMID: 23614499

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Project description:BackgroundThe five-wave epidemic of H7N9 in China emerged in the second half of 2016. This study aimed to compare the epidemiological characteristics among the five waves, estimating the possible infected cases and inferring the extent of the possible epidemic in the areas that have not reported cases before.MethodsThe data for the H7N9 cases from Zhejiang Province between 2013 and 2017 was obtained from the China Information Network System of Disease Prevention and Control. The start date of each wave was 16 March 2013, 1 July 2013, 1 July 2014, 1 July 2015 and 1 July 2016. The F test or Pearson's chi-square test were used to compare the characteristics of the five waves. Global and local autocorrelation analysis was carried out to identify spatial autocorrelations. Ordinary kriging interpolation was analyzed to estimate the number of human infections with H7N9 virus and to infer the extent of infections in the areas with no cases reported before.ResultThere were 45, 94, 45, 34 and 80 cases identified from the first wave to the fifth, respectively. The death rate was significantly different among the five waves of epidemics (?2 = 10.784, P = 0.029). The age distribution (F = 0.903, P = 0.462), gender (?2 = 2.674, P = 0.614) and occupation(?2 = 19.764, P = 0.407) were similar in each period. Most of the cases were males and farmers. A significant trend (?2 = 70.328, P<0.001) was identified that showed a growing proportion of rural cases. There were 31 high-high clusters and 3 high-low clusters at the county level among the five waves and 12, 8, 2, 9 and 3 clusters in each wave, respectively. The total cases infected with the H7N9 virus were far more than those that have been reported now, and the affected areas continue to expand. The epidemic in the north of Zhejiang Province persisted in all five waves. Since the second wave, the virus spread to the south areas and central areas. There was an obvious decline in the infected cases in the urban areas, and the epidemics mostly occurred in the rural areas after the fourth wave. The epidemic was relatively dispersed since the third wave had fewer than two cases in most of the areas and showed a reinforcing trend again in the fifth wave.ConclusionsThe study revealed that there were few differences in the epidemiologic characteristics among the five waves of the epidemic. However, the areas where the possible epidemic circulated was larger than reported. The epidemic cross-regional expansion continued and mostly occurred in rural areas. Continuous closure of the live poultry market (LPM) is strongly recommended in both rural and urban areas. Illegal and scattered live poultry trading, especially in rural areas, must be forbidden. It is suggested too that a more rigorous management be performed on live poultry trade and wholesale across the area. Health education, surveillance of cases and pathogenicity should also be strengthened.

Dataset Information

Epidemiology of human infections with avian influenza A(H7N9) virus in China.

Publications

Epidemiology of human infections with avian influenza A(H7N9) virus in China.

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