Diversity of influenza viruses in swine and the emergence of a novel human pandemic influenza A (H1N1)

Abstract The novel H1N1 influenza virus that emerged in humans in Mexico in early 2009 and transmitted efficiently in the human population with global spread has been declared a pandemic strain. Here we review influenza infections in swine since 1918 and the introduction of different avian and human influenza virus genes into swine influenza viruses of North America and Eurasia. These introductions often result in viruses of increased fitness for pigs that occasionally transmit to humans. The novel virus affecting humans is derived from a North American swine influenza virus that has acquired two gene segments [Neuraminidase (NA) and Matrix (M)] from the European swine lineages. This reassortant appears to have increased fitness in humans. The potential for increased virulence in humans and of further reassortment between the novel H1N1 influenza virus and oseltamivir resistant seasonal H1N1 or with highly pathogenic H5N1 influenza stresses the need for urgent pandemic planning.     

四川省2009甲型H1N1流感的流行病学特征

目的分析四川地区甲型H1N1流感流行病学特点,为今后新发传染病的防控提供参考。方法回顾性分析我院2009年收治的271例甲型H1N1流感病例的来源、年龄及时间分布。结果 1.271例甲型H1N1流感病例,男∶女为1.09∶1,随着病情加重发病年龄逐渐增加,病程亦逐渐延长;2.轻症患者均无基础疾病,危重症患者基础疾病较重症患者多且重;3.绝大多数患者年龄在10~30岁（211例,77.87%）,轻症及重症中无≤2岁及≥65岁的患者,危重症中≥65岁者2例;4.疫情早期（5~9月）患者均为轻症,以输入病例为主（52例,19.19%）,疫情后期以本土暴发病例为主（9月以后）有危重症出现。结论新发传染病疫情早期以轻症、输入病例为主,后期随着社区聚集性疫情,有重危症患者出现;患者年龄、基础疾病是该疾病严重程度的重要影响因素。     

H1N1 swine origin influenza infection in the United States and Europe in 2009 may be similar to H1N1 seasonal influenza infection in two Australian states in 2007 and 2008

Background The population‐based impact of infection with swine origin influenza A (H1N1) virus infection was not clear in the early days of the epidemic towards the end of May 2009. Australia had seven confirmed cases by 22 May 2009. We aimed to compare available data on swine origin influenza A (H1N1) virus infection overseas with seasonal influenza A (H1N1) virus infection in Australia to assist with forward planning. Methods Data on infection with seasonal influenza A (H1N1) virus in patients recruited through sentinel general practices in Victoria and Western Australia in 2007 and 2008 were compared with early publications on infection with swine origin influenza A (H1N1) virus in the United States and Europe. Results Influenza A (H1N1) virus infection was predominantly a disease of younger people, regardless of whether the virus was of swine or human origin. The median age of infection with swine origin virus was 20 years in the United States and 22 years in Spain, while the median age of infection with human origin virus was 18 years in Western Australia and 23 years in Victoria. Conclusions The median age of infection with influenza A (H1N1) virus was around 20 ± 3 years, independent of the origin of the H1N1 virus but a higher proportion of swine origin influenza infections occurred in people aged 10–18 years. This is at least partially explained by biased sampling among surveillance patients, although it may also reflect a different infection pattern.     

6例危重甲型H1N1流感救治体会

目的探索危重甲型H1N1流感的救治方案。方法对6例危重甲型H1N1流感的临床特征、救治方案、预后进行回顾性分析。结果 6例患者中男4例,女2例,中位数年龄40岁。首发症状发热3例,咳嗽咳痰3例;5例最高体温在39.0℃以上;6例患者中3例有基础疾病;6例患者均使用奥司他韦、有创机械通气、甲强龙、低分子肝素钙治疗,4例使用CRRT治疗;6例患者中3例死亡、3例治愈。结论危重甲型H1N1流感病例的治疗,以抗病毒、改善氧合、减轻炎症反应为主的综合治疗。CRRT、ECMO等技术的使用会提高抢救的成功率。     

甲型H1NI流感研究进展

目前南半球大部分国家已经历了甲型H1N1流感流行高峰期,而北半球温带地区逐渐进入活跃期,部分国家和地区出现地区性暴发。尽管当前甲型H1N1的流行总体上比较温和,但随着发病人数的增加,重症及危重症病例数逐渐增多,死亡病例也在明显增加。本文复习近期文献,就目前甲型H1N1流感流行态势、临床特点、病毒变异和耐药以及疫苗等热点问题作一综述,为临床医师掌握最新研究动态、及时发现和救治重症及危重症病例、降低病死率提供帮助。     

A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza

Please cite this paper as: Straight et al. (2010) A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza. Influenza and Other Respiratory Viruses 4(2), 73–79. Background One of the challenges of the recent pandemic (H1N1) 2009 influenza outbreak was to differentiate the virus from seasonal influenza when confronting clinical cases. The determination of the virus has implications on treatment choice, and obvious epidemiologic significance. Objectives We set out to apply a novel electrochemical device to samples derived from clinical cases of pandemic (H1N1) 2009 influenza to examine the ability of the device to differentiate these samples from cases of seasonal influenza. Patients/Methods An IRB approved protocol allowed for the use of original nasal wash samples from 24 confirmed human cases pandemic (H1N1) 2009 influenza. Clinical samples from cases of seasonal influenza (Influenza A/H1N1, A/H3N2, and B) were included as controls. Nucleic acids were extracted and samples examined by the ElectraSense^® Influenza A assay (CombiMatrix, Inc). Samples were also examined by RT-PCR or Luminex assays as a comparator. Results and Conclusions The ElectraSense^® Influenza A assay correctly identified 23 of 24 samples of laboratory-confirmed pandemic (H1N1) 2009 Influenza. The assay correctly identified all samples of influenza A/H1N1 and A/H3N2, and differentiated these from pandemic (H1N1) 2009 Influenza in all cases. The ElectraSense^® Influenza A assay proved to be a useful assay to quickly and accurately differentiate pandemic (H1N1) 2009 influenza from seasonal influenza.     

3例重症甲型H1N1流感的救治经验

目的提高重症甲型H1N1流感的治愈率。方法对3例重症甲型H1N1流感患者的临床主要症状、影像学表现、心电图、实验室检查、治疗及预后进行回顾性研究。结果重症甲型H1N1流感侵犯全身脏器,死亡率高。结论重症甲型H1N1流感应早诊断,早治疗,可以降低死亡率。     

Course of pandemic influenza A(H1N1) 2009 virus infection in Dutch patients

The clinical dynamics of influenza A(H1N1) 2009 infections in 61 laboratory-confirmed Dutch cases were examined. An episode lasted a median of 7·5 days of which 2 days included fever. Respiratory symptoms resolved slowly, while systemic symptoms peaked early in the episode and disappeared quickly. Severity of each symptom was rated highest in the first few days. Furthermore, diarrhoea was negatively associated with viral load, but not with faecal excretion of influenza virus. Cases with comorbidities appeared to have higher viral loads than the cases without, suggesting a less effective immune response. These results complement information obtained through traditional surveillance.     

2009年甲型H1N1流感大流行重症病例的治疗

本文就呼吸支持、药物治疗（抗病毒药物、皮质类固醇、抗菌药物、乌司他丁）、血浆疗法与营养支持及抗凝疗法等方面介绍了重症甲型H1N1流感的救治经验。随着病例的增加,这些经验对临床医生有很好的指导意义。     

甲型H1N1流感患者免疫学指标分析

目的分析甲型H1N1流感患者免疫学指标的特点。方法以明确诊断的87例甲型H1N1流感患者为研究对象,比较疾病急性期、恢复期部分免疫学指标变化情况,并进行统计学分析。结果在病程急性期,淋巴细胞总数、GIN＋T淋巴细胞、CD8＋T淋巴细胞及B淋巴细胞计数明显下降。随着病情的恢复,以上指标均明显上升;总补体溶血活性CH50在整个病程中均处于较高水平。结论在甲型H1N1流感病程中,机体细胞免疫起着重要作用。     

甲型H1N1流感95例临床分析

目的分析甲型H1N1流感的临床特征。方法对我院2009年7月—2009年9月收治的95例确诊为甲型H1N1流感患者的病例资料进行回顾性分析。结果昆明地区甲型H1N1流感患者常见临床表现为发热、咽痛、咳嗽、咯痰,咽部充血,白细胞数减少、中性粒细胞比例下降、淋巴细胞及单核细胞比例升高,咽拭子甲型H1N1病毒核酸阳性(100%)。未发现重症病例及严重并发症。采取口服磷酸奥司他韦、双黄连口服液、莲花清瘟胶囊等中西医结合治疗,效果较好,无死亡病例。结论昆明地区甲型H1N1流感临床表现典型,并发症少,但其传染性强,防控重点地区应放在人口密集的学校。     

甲型H1N1流感96例临床观察

目的探讨辽阳地区甲型H1N1流感的临床特点。方法分析2009年9—10月我市收治的96例甲型H1N1流感患者的临床表现、实验室检查结果、治疗及预后特点。结果辽阳地区甲型H1N1流感以青少年学生多发;绝大多数病例临床表现类似于普通感冒,少数病例出现CK、AIJT、AST升高,极少数病例可出现口周疱疹及皮疹;重症发生率为4．2％;连花清瘟胶囊和（或）痰热清注射液治疗有效。结论辽阳地区甲型H1N1流感临床经过良好,无危重症病例,治愈率为100％。中西医结合治疗有效。     

妊娠合并重症新型甲型H1N1流感13例临床分析

目的探讨妊娠合并重症新型甲型H1N1流感的临床及治疗特点。方法对2009年11月7日至12月18日中国医科大学附属盛京医院收治的妊娠合并重症新型甲型H1N1流感住院的13例患者临床资料进行回顾性分析。结果13例患者均为妊娠中晚期,均伴有发热、气短症状。11例有低蛋白血症,6例脑钠肽增高,7例D-二聚体增高,10例氧合指数小于300。7例入住重症监护病房(ICU),2例死亡。8例行紧急剖宫产手术,其中4例新生儿存活,3例胎死宫内,1例新生儿死亡。入住ICU的患者平均孕龄为31.7周,而非入住ICU的患者平均孕龄为21.7周,两组差异有统计学意义(P0.01)。结论妊娠妇女是重症新型甲型H1N1流感的高危人群;孕龄与病情严重程度相关;适时中止妊娠、抗凝及负液平衡治疗对预后至关重要。     

63例重症甲型H1N1流感病例的临床特点及救治体会

目的分析成人重症甲型HlNl流感患者的流行病学及临床特征。方法分析63例重症甲型H1N1流感患者的临床表现,比较其流行病学信息及临床特征。结果 63例患者中59例患者病情好转出院,4例死亡。临床表现以显著的低氧血症为主要特征,患者有明显的全身症状,多器官功能障碍及免疫功能低下多见,易合并继发细菌或真菌感染。但经过积极抗病毒、抗感染、改善全身症状及支持治疗后,大部分患者病情改善。结论重症甲型H1N1流感病例病程进展快、低氧血症难以纠正、肺部病变范围广、合并感染严重,因此,早发现、尽早开始全身的综合救治是治疗成功的关键。     

Immunization with 1976 swine H1N1- or 2009 pandemic H1N1-inactivated vaccines protects mice from a lethal 1918 influenza infection

Please cite this paper as: Easterbrook et al. (2011) Immunization with 1976 swine H1N1‐ or 2009 pandemic H1N1‐inactivated vaccines protects mice from a lethal 1918 influenza infection. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00191.x. Background Zoonotic infections with H1N1 influenza viruses that evolved initially from the 1918 virus (1918) and adapted to swine threatened a pandemic in 1976 (1976 swH1N1) and a novel reassortant H1N1 virus caused a pandemic in 2009–2010 (2009 pH1N1). Epidemiological and laboratory animal studies show that protection from severe 2009 pH1N1 infection is conferred by vaccination or prior infection with 1976 swH1N1 or 1918. Objectives Our aim was to demonstrate cross‐protection by immunization with 2009 pH1N1 or 1976 swH1N1 vaccines following a lethal challenge with 1918. Further, the mechanisms of cross‐protective antibody responses were evaluated. Methods Mice were immunized with 1976 swH1N1, 2009 pH1N1, 2009 seasonal trivalent, or 1918 vaccines and challenged with 1918. Cross‐reactive antibody responses were assessed and protection monitored by survival, weight loss, and pathology in mice. Results and Conclusions Vaccination with the 1976 swH1N1 or 2009 pH1N1 vaccines protected mice from a lethal challenge with 1918, and these mice lost no weight and had significantly reduced viral load and pathology in the lungs. Protection was likely due to cross‐reactive antibodies detected by microneutralization assay. Our data suggest that the general population may be protected from a future 1918‐like pandemic because of prior infection or immunization with 1976 swH1N1 or 2009 pH1N1. Also, influenza protection studies generally focus on cross‐reactive hemagglutination‐inhibiting antibodies; while hemagglutinin is the primary surface antigen, this fails to account for other influenza viral antigens. Neutralizing antibody may be a better correlate of human protection against pathogenic influenza strains and should be considered for vaccine efficacy.     

应对甲型H1N1流感疫情开展培训的实践与思考

根据2009年甲型H1N1流感防控形势，我院及时开展了防治知识和技能的培训。在培训中把握重点，抓住关键，形式多样，内容丰富，收到了良好效果；同时也体会到加强部门间协作，重视国家有关政策法规的学习，加强住院医师毕业后教育的多学科培训和实践教育都是十分必要的。     

Original Article: A primary school outbreak of pandemic 2009 influenza A (H1N1) in China

Please cite this paper as: Huai et al. (2010) A primary school outbreak of pandemic 2009 influenza A (H1N1) in China. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00150.x. Background  We investigated the first known outbreak of pandemic 2009 influenza A (H1N1) at a primary school in China. Objectives  To describe epidemiologic findings, identify risk factors associated with 2009 H1N1 illness, and inform national policy including school outbreak control and surveillance strategies. Methods  We conducted retrospective case finding by reviewing the school’s absentee log and retrieving medical records. Enhanced surveillance was implemented by requiring physicians to report any influenza‐like illness (ILI) cases to public health authorities. A case–control study was conducted to detect potential risk factors for 2009 H1N1 illness. A questionnaire was administered to 50 confirmed cases and 197 age‐, gender‐, and location‐matched controls randomly selected from student and population registries. Results  The attack rate was 4% (50/1314), and children from all grades were affected. When compared with controls, confirmed cases were more likely to have been exposed to persons with respiratory illness either in the home or classroom within 7 days of symptom onset (OR, 4·5, 95% CI: 1·9–10·7). No cases reported travel or contact with persons who had traveled outside of the country. Conclusions  Findings in this outbreak investigation, including risk of illness associated with contacting persons with respiratory illness, are consistent with those reported by others for seasonal influenza and 2009 H1N1 outbreaks in school. The outbreak confirmed that community‐level transmission of 2009 H1N1 virus was occurring in China and helped lead to changes in the national pandemic policy from containment to mitigation.     

新型甲型H1N1流感重症和危重病例75例临床分析

目的分析新型甲型H1N1流感重症和危重病例的临床特点,并对其诊治方法进行探讨。方法对2009年10月24日至12月12日中国医科大学附属第一医院收治的75例新型甲型H1N1流感重症和危重病例的临床症状、实验室检查及影像学资料进行回顾性分析。结果75例患者中男54例,女21例。年龄18～66岁,平均42.4岁。重症患者29例,危重症患者46例。16例患者有明确的接触史,平均潜伏期3.5d;56.0%的患者以发热为首发症状,10.7%的患者病程中没有出现发热,20.0%的患者出现血性痰;90.7%的患者肺部可闻及啰音笛槭壹觳?78.7%的患者中性粒细胞比率升高,74.7%的患者淋巴细胞比率降低;56.7%的患者白蛋白降低,乳酸脱氢酶(LDH)明显升高(58.2%);外周血T细胞亚群CD4明显降低(57.1%)。肺CT主要表现为双肺多发的斑片影和磨玻璃影。出现急性呼吸窘迫综合征(ARDS)23例,其中10例死亡。结论新型甲型H1N1流感诊治的关键是早期识别重症和危重病例,并及时给予奥司他韦治疗,综合支持治疗可取得较好的疗效。