一例儿童轻型人感染H7N9禽流感确诊病例调查

目的 分析2013年北京市海淀区一例人感染H7N9禽流感病例的发病、诊治和感染来源情况,提出疫情控制措施.方法 采集患儿标本进行实验室检测,应用《人感染H7N9禽流感个案调查表》对患儿及其家属开展面对面问卷调查,获得现场资料.结果 患儿以上呼吸道症状为首发症状,经门诊治疗痊愈,传染源不明.患儿无肺部感染,未服用达菲,经过抗炎、抗病毒治疗.结论 人感染H7 N9禽流感是一种新出现的传染病,传染和流行特征未明,要加强流感样病例监测、流感病原学监测、不明原因肺炎监测等传染病监测工作,及时发现病例,及早采取防治措施.     

Risk assessment on the epidemics of human infection with a novel avian influenza A (H7N9) virus in Jiangsu Province, China

A novel avian influenza A (H7N9) virus was discovered in February 2013 in China and has resulted in more than 100 comfirmed human infections including 26 fatal cases as of May 2, 2013. The situation raises many urgent questions and global public health concerns. In this study, epidemiologic characteristics of infected human cases in Jiangsu province were analyzed and risk assessment was undertaken based on the information available. Briefly, it is highly unlikely that a pandemic of human infection with avian influenza A (H7N9) virus will happen in Jiangsu Province in the near future. In the end, some measures are recommended to prevent the situation from becoming worse.     

一例儿童轻型人感染H7N9禽流感确诊病例调查

目的 分析2013年北京市海淀区一例人感染H7N9禽流感病例的发病、诊治和感染来源情况,提出疫情控制措施调整意见.方法 采集患儿标本进行实验室检测,应用《人感染H7 N9禽流感个案调查表》与患儿及其家属面对面问卷调查,获得现场资料.结果 患儿以上呼吸道症状为首发症状,经门诊治疗痊愈,传染源不明.患儿无肺部感染,经过抗炎、抗病毒治疗,未服用达菲.结论 人感染H7 N9禽流感是一种新出现的传染病,传染和流行特征未明,要加强流感样病例监测、流感病原学监测、不明原因肺炎监测等传染病监测工作,及时发现病例,及早采取防治措施.     

从我国人群中再次分离到H9N2亚型流感病毒

目的 了解分离流感病毒毒株表面抗原亚型和特性及其来源。方法 病毒通过ＭＤＣＫ细胞分离,用红细胞凝集抑制（ＨＩ）和神经氨酸酶抑制（ＮＩ）测定对病毒株表面抗原进行鉴定和特性分析,人血清中抗体测定采用ＨＩ和中和实验。对患者进行个」案调查。结果 分离物为甲型流感病毒Ｈ９Ｎ２亚型,属Ｇ９类似毒株,它的ＨＡ抗原特性与已经从人、鸡和鸽分离到的Ｈ９Ｎ２亚型毒株均有差异。患者恢复期血清对分离物的ＨＩ抗体滴度为４００     

广州地区禽H9N2亚型流感病毒的发现及感染人调查

目的 了解广州地区禽流感病毒在家禽中的流行及感染人的情况，防止香港H5N1禽流感在广州地区流行。方法 对广州地区的主要鸡场和农贸市场的家禽和密切接触家禽的职业人群进行病原学和血清学的检测。病毒分离同时采用MDCK细胞和鸡胚双腔接种法；采用微量血凝抑制半致敏法进行血清学检测。结果 从54份鸡咽拭液中分离到1株H9N2亚型流感病毒；鸡及职业人群血对分离的H9N2毒株的血抑抗体阳性率分别为12．8％和15．1％。结论 广州地区鸡群中有H9N2，亚型流感病毒存在，禽H9N2亚型流感病毒能感染人。     

从人分离出两株甲型流感H9N2亚型毒株内部基因特性的研究

目的 了解2株从人分离出的H9N2亚型毒株内部基因特性，并弄清其来源。方法 用RT-PCR扩增目的基因，用P^CEM-T Vector(美国Promega公司)，4℃过夜连接，重组质粒转入dH5a细菌，筛选阳性菌落，酶切鉴定，送六合通公司自动测序。然后进行进化树分析。结果 2株测定毒株内部基因均为G9基因系，它们相互间除PA基因有差异外，其余5个基因均相同。结论 2株测定毒株的基因组均为G9基因系，它们是由携带不同基因特性H9N2毒株的禽群分别直接感染人，而不是来自同一禽的H9N2亚型流感病毒。     

An Internet-Based Epidemiological Investigation of the Outbreak of H7N9 Avian Influenza A in China Since Early 2013

Background

In early 2013, a new type of avian influenza, H7N9, emerged in China. It quickly became an issue of great public concern and a widely discussed topic on the Internet. A considerable volume of relevant information was made publicly available on the Internet through various sources.

Objective

This study aimed to describe the outbreak of H7N9 in China based on data openly available on the Internet and to validate our investigation by comparing our findings with a well-conducted conventional field epidemiologic study.

Methods

We searched publicly accessible Internet data on the H7N9 outbreak primarily from government and major mass media websites in China up to February 10, 2014. Two researchers independently extracted, compared, and confirmed the information of each confirmed H7N9 case using a self-designed data extraction form. We summarized the epidemiological and clinical characteristics of confirmed H7N9 cases and compared them with those from the field study.

Results

According to our data updated until February 10, 2014, 334 confirmed H7N9 cases were identified. The median age was 58 years and 67.0% (219/327) were males. Cases were reported in 15 regions in China. Five family clusters were found. Of the 16.8% (56/334) of the cases with relevant data, 69.6% (39/56) reported a history of exposure to animals. Of the 1751 persons with a close contact with a confirmed case, 0.6% (11/1751) of them developed respiratory symptoms during the 7-day surveillance period. In the 97.9% (327/334) of the cases with relevant data, 21.7% (71/327) died, 20.8% (68/327) were discharged from a hospital, and 57.5% (188/327) were of uncertain status. We compared our findings before February 10, 2014 and those before December 1, 2013 with those from the conventional field study, which had the latter cutoff date of ours in data collection. Our study showed most epidemiological and clinical characteristics were similar to those in the field study, except for case fatality (71/327, 21.7% for our data before February 10; 45/138, 32.6% for our data before December 1; 47/139, 33.8% for the field study), time from illness onset to first medical care (4 days, 3 days, and 1 day), and time from illness onset to death (16.5 days, 17 days, and 21 days).

Conclusions

Findings from our Internet-based investigation were similar to those from the conventional field study in most epidemiological and clinical aspects of the outbreak. Importantly, publicly available Internet data are open to any interested researchers and can thus greatly facilitate the investigation and control of such outbreaks. With improved efforts for Internet data provision, Internet-based investigation has a great potential to become a quick, economical, novel approach to investigating sudden issues of great public concern that involve a relatively small number of cases like this H7N9 outbreak.     

人感染H7N9禽流感临床病理学特征分析

目的探讨人感染高致病H7N9禽流感的临床病理学特征。方法收集12例人感染高致病H7N9禽流感患者的临床资料,其中3例有病理资料,分析其流行病学及病理学特征。结果流行病学统计显示H7N9禽流感最常见的症状为发热、咳嗽、咳痰、气促,伴全身酸痛、乏力等。血常规示白细胞计数正常或下降,淋巴细胞计数及比例下降,合并感染者白细胞计数和(或)中性粒细胞百分比升高;血气分析提示严重低氧血症、呼吸衰竭等。胸部影像学检查表现为双肺弥漫性斑片状、磨玻璃影及肺实变影且进展迅速。3例病理学显示:例1,左主气管赘生物纤支镜活检:形态学符合坏死性气管炎;例2,右下肺纤支镜活检:提示肺部急性感染性病变;例3,因气胸在体外膜氧合(ECMO)辅助通气胸腔镜下(VATS)行右肺大疱修补术,病理检查结果提示弥漫性肺泡损伤合并肺大疱。结论人感染H7N9禽流感的流行病学表现为病情进展迅速、凶险,临床表现为重症肺炎、多脏器功能衰竭等;针对具有疑似症状的患者,相关的临床检查及病理组织活检对该病诊断与鉴别诊断具有重要意义。     

Novel reassortant H10N7 avian influenza viruses isolated from chickens in Eastern China

BackgroundSince 2004, the H10N7 subtype avian influenza virus (AIV) has caused sporadic human infections with variable clinical symptoms world-wide. However, there is limited information pertaining to the molecular characteristics of H10N7 AIVs in China.ObjectiveTo more fully characterize the genetic relationships between three novel H10N7 strains isolated from chickens in Eastern China and the strains isolated from birds throughout Asia, and to determine the pathogenicity of the H10N7 isolates in vivo.Study designAll eight gene segments from the Chinese H10N7 strains were sequenced and compared with AIV strains available in GenBank. The virulence of the three isolates was determined in chickens and mice.ResultsThree H10N7 subtype avian influenza viruses were isolated from chickens in live poultry markets in Eastern China in 2014: (1) A/chicken/Zhejiang/2C66/2014(H10N7) (ZJ-2C66), (2) A/chicken/Zhejiang/2CP2/2014(H10N7) (ZJ-2CP2), and (3) A/chicken/Zhejiang/2CP8/2014(H10N7) (ZJ-2CP8). Phylogenetic analysis indicated that the viruses contained genetic material from H10, H2, H7, and H3 AIV strains that were circulating at the same time. The reassortant H10N7 viruses were found to be minimally pathogenic in chickens and moderately pathogenic in mice. The viruses were able to replicate in mice without prior adaptation.ConclusionThese results suggest that H10N7 surveillance in poultry should be used as an early warning system for avian influenza outbreaks. The novel strains identified here may post a threat to human health in the future if they continue to circulate.     

Evolutionary characterization of influenza virus A/duck/Hubei/W1/2004 (H9N2) isolated from central China

Full-length eight gene segments of avian influenza virus A/duck/Hubei/W1/2004(H9N2) (Dk/Hub/W1/04) were amplified by RT-PCR and completely sequenced. Phylogenetic analysis revealed that Dk/Hub/W1/04 was derived from A/Duck/HongKong/Y280/97, not displaying direct evolutional relationship with A/Quail/HongKong/G1/97 or Hubei H5N1 viruses. Meanwhile, Dk/Hub/W1/04 was found highly related to recent three chicken isolates. The connecting peptide of HA and the deletion in NA stalk were consistent with three chicken isolates, and the number of potential glycosylation site on the HA and NA also was similar or identical to the three chicken isolates. These findings suggested that Dk/Hub/W1/04 is likely to transmit back to ducks from chickens.     

一起人感染H7N9禽流感家庭聚集性疫情的流行病学调查分析

目的 调查一起人感染H7 N9禽流感聚集性疫情的流行病学特征,分析病例的感染来源和传播途径.方法 对病例开展现场流行病学调查和实验室检测,对病例感染来源进行调查和外环境采样检测.结果 共发现两名病例,病例为父女关系.两病例发病前有可疑活禽暴露史,居住地附近可疑暴露市场标本检测出H7N9禽流感病毒.病例1在潜伏期内即发病,判断为环境暴露感染;其女儿的发病时间距脱离暴露环境已经10天,而在其父亲发病后曾共同生活,判断由其父亲传染给她的可能性大.结论 本起家庭聚集性疫情中,病例1的感染来源可能为被H7 N9禽流感病毒污染的环境,病例2被病例1传染的可能性更大.     

Generation and characterisation of monoclonal antibodies specific to avian influenza H7N9 haemagglutinin protein

Introduction: Emerging virulent strains of influenza virus pose a serious public health threat with potential pandemic consequences. A novel avian influenza virus, H7N9, breached the species barrier from infected domestic poultry to humans in 2013 in China. Since then, it has caused numerous infections in humans with a close contact to poultry. Materials and Methods: In this study, we describe the preliminary characterisation of five murine monoclonal antibodies (MAbs) developed against recombinant haemagglutinin (rHA) protein of avian H7N9 A/Anhui/1/2013 virus by their Western blot and enzyme-linked immunosorbent assay (ELISA) reactivity and binding affinity. Results: Of the five MAbs, four were highly specific to H7N9 HA and did not show any cross-reactivity in ELISA with rHA protein from pandemic as well as seasonal H1N1, H2N2, H3N2, H5N1 and influenza virus B (B/Brisbane/60/2008). However, one of the MAbs, MA-24, in addition to HA protein of H7N9 also reacted strongly with HA protein of H3N2 and weakly with HA of pandemic and seasonal H1N1 and H2N2. All the five MAbs also reacted with H7N9 rHA in Western blot. The MAbs bound H7N9 rHA with an equilibrium dissociation constant (K_D) ranging between 0.14 and 25.20 nM, indicating their high affinity to HA. Conclusions: These antibodies may be useful in developing diagnostic tools for the detection of influenza H7N9 virus infections.     

Importance of Internet Surveillance in Public Health Emergency Control and Prevention: Evidence From a Digital Epidemiologic Study During Avian Influenza A H7N9 Outbreaks

Background

Outbreaks of human infection with a new avian influenza A H7N9 virus occurred in China in the spring of 2013. Control and prevention of a new human infectious disease outbreak can be strongly affected by public reaction and social impact through the Internet and social media.

Objective

This study aimed to investigate the potential roles of Internet surveillance in control and prevention of the human H7N9 outbreaks.

Methods

Official data for the human H7N9 outbreaks were collected via the China National Health and Family Planning Committee website from March 31 to April 24, 2013. We obtained daily posted and forwarded number of blogs for the keyword “H7N9” from Sina microblog website and a daily Baidu Attention Index (BAI) from Baidu website, which reflected public attention to the outbreak. Rumors identified and confirmed by the authorities were collected from Baidu search engine.

Results

Both daily posted and forwarded number and BAI for keyword H7N9 increased quickly during the first 3 days of the outbreaks and remained at a high level for 5 days. The total daily posted and forwarded number for H7N9 on Sina microblog peaked at 850,000 on April 3, from zero blogs before March 31, increasing to 97,726 on April 1 and to 370,607 on April 2, and remaining above 500,000 from April 5-8 before declining to 208,524 on April 12. The total daily BAI showed a similar pattern of change to the total daily posted and forwarded number over time from March 31 to April 12. When the outbreak locations spread, especially into other areas of the same province/city and the capital, Beijing, daily posted and forwarded number and BAI increased again to a peak at 368,500 and 116,911, respectively. The median daily BAI during the studied 25 days was significantly higher among the 7 provinces/cities with reported human H7N9 cases than the 2 provinces without any cases (P<.001). So were the median daily posted and forwarded number and daily BAI in each province/city except Anhui province. We retrieved a total of 32 confirmed rumors spread across 19 provinces/cities in China. In all, 84% (27/32) of rumors were disseminated and transmitted by social media.

Conclusions

The first 3 days of an epidemic is a critical period for the authorities to take appropriate action through Internet surveillance to prevent and control the epidemic, including preparation of personnel, technology, and other resources; information release; collection of public opinion and reaction; and clarification, prevention, and control of rumors. Internet surveillance can be used as an efficient and economical tool to prevent and control public health emergencies, such as H7N9 outbreaks.     

Swine infection with H9N2 influenza viruses in China in 2004

In 2004, H9N2 influenza A viruses were isolated from pigs with respiratory syndrome in commercial swine farms in Henan province, China. Antigenic and genetic characterization were performed for seven swine H9N2 influenza viruses. The hemagglutinin antigenicity of swine H9N2 viruses was similar to those of avian H9N2 viruses of A/duck/Hong Kong/Y280/1997 (Dk/HK/Y280/97)-like sublineage prevalent in China. It is noteworthy that the neuraminidase of these isolates had no deletions in the stalk, which was seldom observed in those viruses of Dk/HK/Y280/97-like sublineage. Genetic analysis revealed that all seven isolates had an -R-S-S-R- motif at the HA cleavage site, which was the same as those of Dk/HK/Y280/97-like viruses established in avian population in China. Phylogenetic analyses showed that the seven swine H9N2 viruses were completely derived from avian influenza viruses of Dk/HK/Y280/97-like sublineage. The present results indicated that avian-to-pig interspecies transmission of H9N2 viruses continued to exist in China through 2004; therefore, surveillance of swine influenza should be given a high priority. Yan-Long Cong, Chun-Feng Wang and Chun-Mei Yan have contributed equally to this work. (i) All the authors have agreed to its submission and are responsible for its contents and (ii) all the authors have agreed that Yanlong Cong may act on their behalf regarding any subsequent processing of the paper.     

Rapid genome sequencing and characterization of novel avian-origin influenza A H7N9 virus directly from clinical sample by semiconductor sequencing

BackgroundRecent outbreaks of severe pneumonia or acute respiratory distress syndrome have attracted much public interest. Rapid and accurate diagnosis of the causative agent is key for an adequate response to suspected outbreaks.ObjectivesWe report a case that highlights the potential of semiconductor sequencing to rapidly determine the novel virus genome sequences.Study designWe have developed a method for rapid de novo assembly of the novel influenza A H7N9 virus genome directly from the tracheal aspirate of a patient using semiconductor sequencer without culture and prior sequence information. Further, characteristic amino acids were analyzed and phylogenetic analysis were done for key genes of the influenza A virus.ResultsDeep sequencing yielded 435,239 reads assigned to H7N9 viruses, with an average length of 172 bp, accounting for 18.6% of total reads (2,339,680). Complete genome of the virus was obtained by de novo assembly method within 2 days. Genomic average depth of coverage of the Ion Torrent PGM was up to 5679 fold. Selected characteristic amino acids were observed, and phylogenetic analyses showed that the novel H7 virus was genetically close to 2011 duck H7N3 viruses in Zhejiang. The novel N9 sequences were most closely related to gene sequences of N9 derived from ducks H11N9 in 2011 in Jiangxi and H2N9 sequences from Hong Kong in 2010, in China, and therefore they may share a common ancestor.ConclusionsThe sequence-independent semiconductor sequencing is a powerful tool to investigate outbreak of a novel pathogen.     

Phylogenetic analysis of low pathogenicity H5N1 and H7N3 influenza A virus isolates recovered from sentinel, free flying, wild mallards at one study site during 2006

From August 2 to October 11, 2006, clusters of low pathogenicity (LP) North American lineage H5N1 and H7N3 avian influenza A viruses (AIV), and other subtypes, were recovered from free-flying, resident, wild mallards used as sentinels at one site. The antigenic subtypes, pathogenicity potential, and Sanger sequencing of the isolates determined the H5N1 and H7N3 isolates were only recovered from samples collected on 8/2/2006 and 9/8/2006, respectively. However, subsequent efforts using next-generation sequencing (NGS) and additional Sanger sequencing found partial H7 segments in other HA-NA virus combinations on 8/2/2006, 9/8/2006 and 10/11/2006. It is well established that over larger geographic areas and years AIVs form transient genomic constellations; this sequential sampling data revealed that over a short period of time the dynamics of AIVs can be active and newer sequencing platforms increase recognition of mixed infections. Both findings provide further insight into the natural history of AIVs in natural reservoirs.