职业暴露人群人感染高致病性禽流感H5N1风险研究进展

当前,全球高致病性禽流感[PHAI(H5N1)]疫情形式仍十分严峻,人间HPAI(H5N1)疫情风险将持续存在,从事禽类养殖及活禽市场交易工作的人员是HPAI(H5N1)禽流感病毒感染的高危人群。以发生疫情后的应急应对模式难以应对当前和未来不断增大的疫情风险挑战。开展职业暴露人群人感染PHAI(H5N1)风险管理,在减少人感染病例的发生显得更为重要。本课题组在查阅分析相关文献基础上,归纳职业暴露中人感染HPAI(H5N1)的风险因子及风险评估方法,为加强职业暴露人群人感染HPAI(H5N1)风险管理提供参考。     

人感染高致病性禽流感H5N1流行病学研究进展

禽流感（Avian Influenza,AI）是由正粘病毒科流感病毒属A型流感病毒引起的一种禽类感染征或疾病综合症。此病主要发生在家禽（鸡、火鸡等）和野禽（野鸭、野鹅等）等禽类,随着禽流感病毒的变异,有时也感染猪、马等低等哺乳动物,有时人偶尔感染。根据禽流感病毒对鸡致病性的不同,而不是针对人而言,将禽流感病毒分为高致病性、中致病性和Ⅳ非致病性,高致病性的为H5和H7亚型病毒毒株。     

1例人感染高致病性禽流感(H5N1)病例流行病学调查

目的研究1例人感染高致病性禽流感(H5N1)病例,为今后开展人禽流感防控工作提供科学依据。方法根据流行病学调查、临床表现、血清学检查、病毒分离及RT-PCR、Read-PCR法进行分析和诊断。结果此例患者为人感染高致病性禽流感(H5N1)实验室确诊病例,经抢救治疗无效因呼吸循环衰竭死亡。患者有明确病死禽接触史、典型临床症状与体征和实验室病原学依据。经采用隔离治疗、个人防护、医学观察、家禽捕杀和消毒等措施,疫情得到控制。结论加强禽流感疫情监测,禁止宰杀、食用病死家禽,采取综合性防控措施,是预防疫情发生的关键。     

人感染高致病性禽流感H5N1病例流行病学分析

[目的]分析人感染高致病性禽流感H5N1病例的流行病学特点,指导禽流感防控工作。[方法]收集2003年12月至2006年7月各国向世界卫生组织报告的人感染高致病性禽流感病例个案资料进行统计分析。[结果]10个国家共报告人感染高致病性禽流感病例230例,病死率为58.26%;2005年10月以后,有病例报告的国家迅速增加,发病数有逐年递增趋势;在北半球冬春季是禽流感的发病高峰期;全球病例的性别比为0.97,51.5%的病例年龄小于20岁,而中国病例的性别比为0.46,68.4%的病例年龄在20-39岁。[结论]2006年底2007年春可能会出现人感染禽流感的发病高峰,各项防控措施必须加强。     

贵州省黎平县一例人感染高致病性禽流感(H5N1)的流行病学调查

目的对黎平县一例人感染高致病性禽流感(H5N1)的调查进行分析,为制定禽流感防控措施提供依据。方法采用流行病学调查、临床检查、血清学检查和Real-time PCR法进行分析和诊断。结果黎平县发现一例H5N1确诊病例,经救治无效因多器官衰竭死亡。患者有明确的病、死禽接触史。采用隔离治疗、个人防护、医学观察、消毒等措施,疫情得到控制,未出现二代病例。结论黎平县一例H5N1病例属感染个案,感染来源可能与接触病、死家禽有关。需要加强人禽流感相关知识的技术培训和不明原因肺炎、不明原因死亡的主动搜索监测,以及与农、林、工商、运输等部门的信息联系才能防止疫情再次发生。     

一起人感染高致病性禽流感(H5N1)家庭聚集性病例的流行病学调查

[目的]为明确两名禽流感病例的感染来源,探索病例间是否存在人与人之间的传播,总结禽流感防控工作的经验及教训,并提供科学依据. [方法]通过现场流行病学调查,按照<人感染高致病性禽流感应急预案>的要求,开展病例诊断、报告、疫情调查和控制工作. [结果]共发生两例H5N1确认病例,系父子关系.首例病例感染来源不明,在发病后d 8抢救无效死亡.第2例痊愈出院,其感染来源最大可能是在医院内护理首例病例期间,与其近距离接触感染. [结论]此起疫情是我国大陆第一起确诊的家庭聚集性人禽流感H5N1发病.提高不明原因肺炎监测系统的敏感性,加强对密切接触者特别是直系亲属的管理是及早发现病例、提高救治率和控制疫情的关键措施.     

黑龙江省职业暴露人群高致病性禽流感病毒感染的调查分析

禽流感是由A型流感病毒引起的严重危害动物及人类健康的一种传染性疾病综合征。根据血凝素和神经氨酸酶检测方法可将A型流感分为16个HA亚型和9个NA亚型。黑龙江省迄今未发现人感染高致病性禽流感病例,但是,随着各种贸易的往来、鸟类的迁徙,黑龙江省是否存在H5N1感染的风险．有必要开展流行病学调查。     

职业暴露人群A(H5N1)和甲型H1N1流感血清抗体分析

目的:了解人禽流感A(H5N1)和甲型H1N1流感职业暴露人群中的感染状况。方法:对职业暴露人群进行个案调查,采用血凝抑制法(HI)检测职业暴露人群血清中人禽流感A(H5N1)和甲型H1N1流感抗体。结果:2009年-2010年采集的624份职业暴露人群血清中未检测出人禽流感A(H5N1)抗体,而在2009年采集的血清中有5份检测出甲型H1N1流感抗体,抗体阳性率为1.55%,2010年采集的血清中抗体阳性率为11.96%,其中<29岁阳性率为17.19%,30岁～59岁阳性率为10.87%。结论:职业暴露人群中未检测出A(H5N1)流感抗体,但仍需加强职业暴露人群监测。同时甲型H1N1流感抗体水平较低,缺乏相应的抗体水平保护。     

高致病性H5N1禽流感全球分布地理信息系统时空分析

目的 了解高致病性H5N1禽流感疫情的时间与空间分布,为研究病毒的传播途径与机制提供假设和间接证据,为疾病的预防和预警提供技术支持。方法 收集2003年3月—2012年3月世界卫生组织和世界动物卫生组织报告中官方确认的5 963起暴发事件,运用多距离空间聚类分析、空间自相关等基于地理信息系统（GIS）的分析手段对高致病性H5N1禽流感的全球分布进行时间和空间尺度分析。结果 2003—2012年共标记5 963个高致病性H5N1禽流感暴发点,亚洲、欧洲、非洲暴发点分别为3 647、1 309、1 007个,分别占61.16%、21.95%、16.89%;亚洲国家越南暴发点数（1 055个）和暴发率（2.22/百万头）最高,欧洲国家暴发点数最多的为德国（407个）,暴发率最高的为罗马尼亚（1.09/百万头）,非洲国家埃及暴发点数（758个）和暴发率（1.35/百万头）最高;空间自相关函数（Moran’s I）和多距离空间聚类分析结果表明,2003年3月—2006年3月实际K值在0~5 000 km尺度范围内大于期望K值（Moran’s I=0.19,P<0.05）,2006年4月—2009年7月实际K值在0~4 500 km尺度范围内大于期望K值（Moran’s I=0.02,P>0.05）,2009年8月—2012年3月实际K值在0~6 000 km尺度范围内大于期望K值（Moran’s I=0.10,P<0.01）,其分布特征随着时间和空间尺度的变化而改变。结论 高致病性H5N1禽流感的时空分布存在显著异质性,其空间分布模式对疫情预警有重要意义,人类活动、候鸟迁徙可能是禽流感传播的主要途径。     

世卫组织人间禽流感H5N1病例流行病学分析

世卫组织在线出版的本周《疫情周报》提出了从2003—12／2006—04—30按发病日期向世卫组织正式报告的所有205例实验室确诊的H5N1病例流行病学数据首次分析结果。     

2005年广州市职业人群H5N1、H9N2血清学监测

目的了解广州地区禽流感病毒H5N1、H9N2在禽类从业人群及生猪从业人群中的感染状况。方法采集广州地区部分禽类、生猪从业人员以及非从事动物相关工作的人员的全血样本,用微量血凝抑制半加敏法检测H5N1、H9N2抗体。结果共调查禽类及生猪从业人员共322名,其中禽类及生猪从业人群H9N2抗体阳性率分别为3.94%(8/203)、1.68%(2/119),两者差异无统计学意义(P>0.05),138名非从事动物相关工作的人员的H9N2抗体均为阴性,三类人群的H5N1抗体均为阴性。结论禽类从业环境是感染禽流感的危险环境,生猪饲养、屠宰等场所也可能增加感染禽流感的风险。     

Prior infection with an H1N1 swine influenza virus partially protects pigs against a low pathogenic H5N1 avian influenza virus

Most humans lack virus neutralizing (VN) and haemagglutination inhibition (HI) antibodies to H5N1 avian influenza viruses (AIVs), but cross-reactive neuraminidase inhibition (NI) antibodies and cell-mediated immune (CMI) responses are common. These immune responses result largely from infections with seasonal human H1N1 influenza viruses, but the protective effect of H1N1 infection-immunity against H5N1 infection has never been examined. To this purpose, we have used the pig model of influenza and a low pathogenic (LP) H5N1 AIV. Pigs were inoculated intranasally with sw/Belgium/1/98 (H1N1) 4 weeks before challenge with duck/Minnesota/1525/81 (H5N1). While the viruses failed to cross-react in HI and VN tests, the H1N1 infection induced high levels of H5N1 cross-reactive NI antibodies. Cross-reactive CMI was demonstrated by measurements of lymphoproliferation and IFN-γ secretion after in vitro restimulation of peripheral blood mononuclear cells. All control pigs showed clinical signs and H5N1 virus isolation from the respiratory tract post-challenge. The H1N1-immune pigs, in contrast, showed a complete clinical protection and only 3 pigs out of 10 were H5N1 virus-positive. In a second and smaller experiment, H1N1 virus infection also conferred cross-protection against a LP H5N2 AIV, while cross-reactive immunity was solely detected in tests for CMI. Our data further support the notion that immunity induced by seasonal human H1N1 influenza virus infection may provide some protection against H5N1 or other H5 AIVs in the absence of neutralizing H5 antibodies. Further studies should reveal whether cross-protection holds against H5N1 viruses that are better adapted to replicate in mammals or with a more distantly related N1.     

Experimental infection of cattle with highly pathogenic avian influenza virus (H5N1)

Four calves were experimentally inoculated with highly pathogenic avian influenza virus A/cat/Germany/R606/2006 (H5N1) isolated from a cat in 2006. All calves remained healthy, but several animals shed low amounts of virus, detected by inoculation of nasal swab fluid into embryonated chicken eggs and onto MDCK cells. All calves seroconverted.     

安徽省甲型H1N1流感抗体水平调查

目的了解安徽省不同人群甲型H1N1流感抗体水平,为防控措施的制定提供依据。方法 2010年1月10～25日期间,采取分层随机抽样的方法抽取4 567名调查对象,进行问卷调查,并运用血清抗凝实验方法检测甲型H1N1流感抗体水平。结果全人群抗体阳性率为29.41%,未接种疫苗人群抗体阳性率为23.94%;全人群中,省会城市抗体阳性率高于中小城市,中小城市高于农村;在全人群和未接种疫苗的人群中,6～岁和16～岁年龄组抗体阳性率较高,60岁及以上组抗体阳性率最低,中小学生抗体阳性率最高,其次是幼托儿童和医护人员。结论人群中甲型H1N1流感免疫屏障尚未建立,目前仍需加强疫苗接种和疫情监测。     

Highly pathogenic avian influenza virus (H5N1) isolated from whooper swans, Japan

On April 21, 2008, four whooper swans were found dead at Lake Towada, Akita prefecture, Japan. Highly pathogenic avian influenza virus of the H5N1 subtype was isolated from specimens of the affected birds. The hemagglutinin (HA) gene of the isolate belongs to clade 2.3.2 in the HA phylogenetic tree.     

Flagellin-HA vaccines protect ferrets and mice against H5N1 highly pathogenic avian influenza virus (HPAIV) infections

In order to meet the global demand for rapid production of pandemic influenza vaccines, we have developed a recombinant fusion vaccine platform in which the globular head of hemagglutinin (HA) antigen is genetically fused to bacterial flagellin (a TLR5 ligand). These flagellin-HA fusion vaccine candidates elicit highly protective immunity against a lethal challenge with 2009 pandemic H1N1 (Liu, et al. PLoS ONE 2011; 6:e20928) or H5N1 influenza A/Vietnam/1203/04 (A/VN) infections in mice (Song, et al. Vaccine 2009;27:5875–88). Here we provide the first evidence showing that two A/VN vaccine candidates elicited HA-specific IgG, reduced nasal virus shedding, and conferred full protection against a lethal A/VN infection in ferrets. Furthermore, we show that similar flagellin-HA vaccine candidates of two other H5N1 HPAIV are immunogenic and/or efficacious in mice. Vaccines of A/Indonesia/5/05 (A/IN) induced significant HAI titers to homologous and heterologous A/Anhui/1/05 (A/AN) H5N1 viruses. Two subcutaneous immunizations with doses of either 0.3 μg or 3 μg of A/IN candidates resulted in ≥2.5 log₁₀ unit reduction in day 5 lung virus titer and 90–100% protection against a lethal A/IN challenge in mice. Both R3.HA5 IN and R3.2xHA5 IN vaccines elicited robust neutralizing antibody responses that last for at least 9 months and demonstrated a significant anamnestic antibody response upon further booster immunization. Finally, we found that two vaccine candidates of A/AN induced significant HAI titers in mice. Taken together, our recombinant flagellin-HA platform has been successfully used to generate potent H5N1 HPAIV vaccine candidates. These promising preclinical results justify the advancement of these candidates into the clinic.     

Highly pathogenic avian influenza virus (H5N1) in experimentally infected adult mute swans

Adult, healthy mute swans were experimentally infected with highly pathogenic avian influenza virus A/Cygnus cygnus/Germany/R65/2006 subtype H5N1. Immunologically naive birds died, whereas animals with preexisting, naturally acquired avian influenza virus-specific antibodies became infected asymptomatically and shed virus. Adult mute swans are highly susceptible, excrete virus, and can be clinically protected by preexposure immunity.     

长沙市家禽市场环境中H5N1亚型禽流感病毒传播风险研究

目的 对长沙市家禽市场职业暴露人群进行禽流感病毒（AIV）H5N1亚型抗体水平和环境AIV核酸检测,并对环境中AIV H5N1亚型的血凝素（HA）基因进行测序分析。方法 抽取长沙市1个区和1个县,各选择2个城区或乡镇家禽市场进行职业暴露人群H5N1抗体和环境AIV核酸检测。利用单放射免疫扩散溶血实验（SRH）对102份家禽市场职业暴露人员血清标本进行H5N1抗体检测,real-time PCR方法检测160份家禽市场环境标本（污水、禽类粪便、羽毛和禽类笼具表面涂抹标本）AIV核酸,对4份污水H5N1亚型AIV核酸阳性标本进行HA基因RT-PCR扩增和TA克隆测序,测序结果利用Lasergene和Mega 5.0软件进行氨基酸比对和进化树构建。结果AIVH5N1抗体监测结果显示,家禽市场职业暴露人群血清H5N1抗体阳性率为25.5%（26/102）,其中乡镇和城区家禽市场职业暴露人群阳性率分别为50.0%（9/18）和25.4%（17/67）,乡镇家禽市场职业暴露人群阳性率高于城区。长沙市家禽市场环境中H5亚型AIV核酸阳性率为31.3%（50/160）,其中乡镇家禽市场阳性率为37.3%（31/83）,高于城区家禽市场24.7%（19/77）;不同标本H5亚型AIV核酸阳性率不同：污水（50.0%,24/48）、羽毛（44.5%,4/9）、禽类粪便（29.8%,14/47）和禽类笼具表面涂抹（14.3%,8/56）;差异均有统计学意义（P＜0.01）。TA克隆测序得到4个AIVH5N1亚型HA基因序列,进化树显示4个AIVH5N1亚型HA基因与中国内地和香港禽来源的AIV分离株为同一分组,属于欧亚分支;4个AIV H5N1亚型HA基因受体结合位点氨基酸序列仍然为禽源（QSG）、HA1和HA2蛋白之间连接肽为多个碱性氨基酸序列（RERRRKK或RERRGKK）,与入源AIV H5N1亚型具有相同的受体结合位点和高致病性的分子特征。结论 长沙市家禽市场环境中存在较多数量的AIVH5N1亚型,是导致职业暴露人群抗体阳性率达25.5%的原因之一;环境中存在的AIVH5N1亚型HA基因表现出来的高致病性分子特征,增加了家禽市场环境中发生AIV传播的风险。     

Atypical avian influenza (H5N1)

We report the first case of avian influenza in a patient with fever and diarrhea but no respiratory symptoms. Avian influenza should be included in the differential diagnosis for patients with predominantly gastrointestinal symptoms, particularly if they have a history of exposure to poultry.