ABSTRACT
Objective: To understand the epidemiological characteristics of human infection with avian influenza A (H7N9) virus in China, and provide evidence for the prevention and control of human infection with H7N9 virus. Methods: The published incidence data of human infection with H7N9 virus in China from March 2013 to April 2017 were collected. Excel 2007 software was used to perform the analysis. The characteristics of distribution of the disease, exposure history, cluster of the disease were described. Results: By the end of April 2017, a total of 1 416 cases of human infection with H7N9 virus were confirmed in China, including 559 deaths, the case fatality rate was 39.5%. In 2016, the case number was lowest (127 cases), with the highest fatality rate (57.5%). The first three provinces with high case numbers were Zhejiang, Guangdong and Jiangsu. The median age of the cases was 55 years and the male to female ratio was 2.3∶1. Up to 66% of cases had clear live poultry exposure history before illness onset, 31% of cases had unknown exposure history and only 3% of the cases had no live poultry exposure history. There were 35 household clusters (5 in 2013, 9 in 2014, 6 in 2015, 5 in 2016, 10 in 2017), which involved 72 cases, accounting for 5% of the total cases. Conclusions: The epidemic of human infection with H7N9 virus in China during 2013-2017 had obvious seasonality and spatial distribution. There was limited family clustering. Infection cases were mostly related to poultry contact.
Subject(s)
Adult , Aged , Aged, 80 and over , Animals , Female , Humans , Male , Middle Aged , Age Distribution , China/epidemiology , Cluster Analysis , Disease Outbreaks , Epidemics , Incidence , Influenza A Virus, H7N9 Subtype/isolation & purification , Influenza, Human/virology , Poultry , Sex DistributionABSTRACT
Objective To understand the epidemiological characteristics of human infection with avian influenza A (H7N9) virus in China,and provide evidence for the prevention and control of human infection with H7N9 virus.Methods The published incidence data of human infection with H7N9 virus in China from March 2013 to April 2017 were collected.Excel 2007 software was used to perform the analysis.The characteristics of distribution of the disease,exposure history,cluster of the disease were described.Results By the end of April 2017,a total of 1 416 cases of human infection with H7N9 virus were confirmed in China,including 559 deaths,the case fatality rate was 39.5％.In 2016,the case number was lowest (127 cases),with the highest fatality rate (57.5％).The first three provinces with high case numbers were Zhejiang,Guangdong and Jiangsu.The median age of the cases was 55 years and the male to female ratio was 2.3 ∶ 1.Up to 66％ of cases had clear live poultry exposure history before illness onset,31％ of cases had unknown exposure history and only 3％ of the cases had no live poultry exposure history.There were 35 household clusters (5 in 2013,9 in 2014,6 in 2015,5 in 2016,10 in 2017),which involved 72 cases,accounting for 5％ of the total cases.Conclusions The epidemic of human infection with H7N9 virus in China during 2013-2017 had obvious seasonality and spatial distribution.There was limited family clustering.Infection cases were mostly related to poultry contact.
ABSTRACT
To analyze the epidemiological characteristics of human infection with avian influenza A(H7N9) virus from 2013 to 2016 in Xiaoshan,China,we collected the epidemiological data of human A(H7N9) cases as well as the results of environmental monitoring and analyzed it by case study,descriptive epidemiological method,and statistical analysis.Results showed that a total of 22 cases were confirmed,including 12 deaths.All the cases occurred in winter and spring,and most of them had been exposed to live poultry,and with the underlying condition of chronic diseases.Chi-square test showed that the ratio of cases with chronic diseases in death group was higher (P=0.01).The environmental monitoring result showed there were distinctive seasonal differences of positive rate with peaks in winter and spring and nadirs in autumn and summer.Positive rates for the samples from external environmental monitoring were consistent with the distribution of the case onset.Due to rise of environmental monitoring positive rate,we should be alert to the occurrence of new cases,especially in rural areas where live poultry fairs still exist and among people with occupational exposure.We should further improve ability to prevent and control this disease.
ABSTRACT
We analyzed genetic evolution characteristics of avian influenza A (H7N9) virus isolated in Zhaoqing,China,2014-2016.Nucleic acid were extracted and sequenced from 17 samples of H7N9 positive cases in Zhaoqing.Genetic characteristics of homology and important amino acid sites were analyzed by using BioEdit5.0 and MEGA6.0.The evolutionary trees were constructed by Neighbor-Joining and the referenced sequences were downloaded from GenBank,Eight nucleic acid fragments from 7 strains of H7N9 viruses were successfully generated.The highest homology was found in HA gene with A/chicken/Dongguan/695/2014(H7N9),and NA gene with A/chicken/Dongguan/1075/2014(H7N9).The internal genes were high homology with avian H7N9 and H9N2 virus from Dongguan and Shenzhen in Guangdong,China.The HA and NA genes were directly evolved in the Pearl River Delta evolution branch with the H7N9 sequences from the cities of Dongguan,Guangzhou and Shenzhen,while the sequences from the provinces of Anhui,Zhejiang,and Jiangsu were in the Yangtze River Delta evolution branch.There were 2 alkaline amino acids in cleavage site of HA,2 mutations (G186V and Q226L) in the crucial sites related with the receptor of HA protein,1 mutation (E627K) in PB2 protein,and 1 drug resistance mutation (S31N) in M2 protein.And no evidence of neuraminidase resistance in NA protein was found.In conclusion,the H7N9 virus for human infection in Zhaoqing may originate from avian H7N9 and H9N2 viruses,which circulated in the Pearl River Delta region of Guangdong from 2013 to 2014.The mutations of G186V,Q226L and E627 K might be related with high susceptibility to human beings.