Clinical Factors Predictive of Pneumonia Caused by Pandemic 2009 H1N1 Influenza Virus

Pneumonia was the most common cause of death during the 2009 pandemic H1N1 influenza virus infection. Clinical risk factors for pneumonia caused by this virus are limited. We enrolled consecutive patients treated at the H1N1 Clinic in Thungsong Hospital in Nakhon Si Thammarat, Thailand, during June–December 2009 who had positive polymerase chain reaction results for H1N1 virus. Clinical features for patients given a diagnosis with and without pneumonia were studied. There were 441 patients with positive polymerase chain reaction results for H1N1 virus. Of these patients, 51 (11.56%) had pneumonia. Three independent clinical factors for H1N1 pneumonia were myalgia, dyspnea, and an absolute neutrophil count > 7,700 cells/μL. Adjusted odds ratios (95% confidence intervals) for these three variables were 0.413 (0.173–0.988), 2.625 (1.230–5.604), and 4.475 (1.882–10.644), respectively. Clinical features may be a useful tool for predicting risk for pneumonia caused by H1N1 virus.     

97例甲型H1N1流感确诊病例临床分析

目的分析甲型H1N1流感确诊病例的临床特点。方法收集97例甲型H1N1流感确诊病例的临床资料并进行回顾性分析。结果97例甲型H1N1流感确诊病例均为轻症病例,主要是本土病例,男性多于女性,学生为主,青少年居多,平均年龄（23．72±4．56）岁,80．0％来自集体单位人群;否认有接触史者占63．92％,无明确诱因占82．47％。首发症状主要为发热、咽部不适、全身酸痛,最常见的症状依次为发热、咽部不适、咳嗽,主要症状组合为发热并咽部不适、发热并咳嗽和3种症状同时出现,体征不明显;发热以中低热为主,热程3天,部分患者不发热;血常规以白细胞正常或降低,淋巴细胞百分比增加或正常为主,57．73％的患者c反应蛋白增高;病程5天,最长不超过10天,预后良好。结论甲型H1N1流感的临床表现并不特异,掌握其临床特点有助于早期识别和规范治疗。     

儿童与成人甲型H1N1流感临床对比分析

目的探讨儿童与成人甲型H1N1流感的临床特点,并进行对比分析。方法选择2009年9月～2010年1月间隔离治疗的甲型H1Nl流感患者57例,并将其分为成人组（23例）和儿童组（34例）,比较两组患者的临床症状、合并症、实验室检查和特检等指标。结果成人组与儿童组甲型HlNl流感患者的扁桃体肿大、合并基础疾病等方面相近;成人组并发肺炎、呼吸衰竭等危重症的发生率较儿童组高,但无显著性差异（P〉0．05）。儿童组的高热、消化道症状发生率、表浅淋巴结肿大、支气管炎发生率较成人组明显增高,差异有显著性（P〈0．05或P〈0．01）。两组患者的外周血白细胞计数、乳酸脱氢酶、空腹血糖相近;成人组丙氨酸氨基转移酶、肌酸激酶及心电图异常等指标高于儿童组,但差异无显著性（P〉0．05）;成人组外周血淋巴细胞计数及低氯低钠血症异常指标明显高于儿童组,而儿童组x线异常率明显高于成人组（P〈0．05）;儿童组肌酸激酶同工酶明显高于成人组（P〈0．01）。结论甲型H1N1流感可引起多器官、多系统的病变损害,成人和儿童患者的临床表现不尽相同,各有其特点。     

Influenza A (H1N1) pneumonia: HRCT findings

OBJECTIVE:

To describe aspects found on HRCT scans of the chest in patients infected with the influenza A (H1N1) virus.

METHODS:

We retrospectively analyzed the HRCT scans of 71 patients (38 females and 33 males) with H1N1 infection, confirmed through laboratory tests, between July and September of 2009. The HRCT scans were interpreted by two thoracic radiologists independently, and in case of disagreement, the decisions were made by consensus.

RESULTS:

The most common HRCT findings were ground-glass opacities (85%), consolidation (64%), or a combination of ground-glass opacities and consolidation (58%). Other findings were airspace nodules (25%), bronchial wall thickening (25%), interlobular septal thickening (21%), crazy-paving pattern (15%), perilobular pattern (3%), and air trapping (3%). The findings were frequently bilateral (89%), with a random distribution (68%). Pleural effusion, when observed, was typically minimal. No lymphadenopathy was identified.

CONCLUSIONS:

The most common findings were ground-glass opacities and consolidations, or a combination of both. Involvement was commonly bilateral with no axial or craniocaudal predominance in the distribution. Although the major tomographic findings in H1N1 infection are nonspecific, it is important to recognize such findings in order to include infection with the H1N1 virus in the differential diagnosis of respiratory symptoms.     

Initial psychological responses to Influenza A, H1N1 ("Swine flu")

Background  

The outbreak of the pandemic flu, Influenza A H1N1 (Swine Flu) in early 2009, provided a major challenge to health services around the world. Previous pandemics have led to stockpiling of goods, the victimisation of particular population groups, and the cancellation of travel and the boycotting of particular foods (e.g. pork). We examined initial behavioural and attitudinal responses towards Influenza A, H1N1 ("Swine flu") in the six days following the WHO pandemic alert level 5, and regional differences in these responses.     

Swine influenza (H1N1) pneumonia in hospitalized adults: chest film findings

In patients with swine influenza (H1N1) pneumonia, the admission chest film is critical to rapidly detect simultaneous bacterial pneumonia due to Staphylococcus aureus or subsequent bacterial pneumonia due to Streptococcus pneumoniae or Haemophilus influenzae by the presence of focal infiltrates. Our objective was to characterize the chest film findings in 25 adults hospitalized with H1N1 pneumonia during the pandemic and detect focal infiltrates indicative of bacterial coinfection, that is, bacterial pneumonia. Chest films were obtained on admission, after 48 hours, and thereafter as indicated throughout hospitalization. Chest film findings were classified as no infiltrates, clear with accentuated bibasilar lung markings, or focal segmental/lobar infiltrates. The presence or absence of pleural effusion and cavitation was also noted. Admitted adults with H1N1 pneumonia had negative chest films or accentuated basilar lung markings. After 48 hours, 13% of patients developed patchy bilateral interstitial infiltrates. No patients had or subsequently developed focal segmental/lobar infiltrates indicative of bacterial community-acquired pneumonia during hospitalization. The most common chest film finding was no infiltrates or an accentuation of bibasilar lung markings in hospitalized adults with H1N1 pneumonia. No patients had focal segmental/lobar infiltrates indicative of superimposed bacterial community-acquired pneumonia.     

Evolution of Swine Influenza Virus H3N2 in Vaccinated and Nonvaccinated Pigs after Previous Natural H1N1 Infection

Swine influenza viruses (SIV) produce a highly contagious and worldwide distributed disease that can cause important economic losses to the pig industry. Currently, this virus is endemic in farms and, although used limitedly, trivalent vaccine application is the most extended strategy to control SIV. The presence of pre-existing immunity against SIV may modulate the evolutionary dynamic of this virus. To better understand these dynamics, the viral variants generated in vaccinated and nonvaccinated H3N2 challenged pigs after recovery from a natural A(H1N1) pdm09 infection were determined and analyzed. In total, seventeen whole SIV genomes were determined, 6 from vaccinated, and 10 from nonvaccinated animals and their inoculum, by NGS. Herein, 214 de novo substitutions were found along all SIV segments, 44 of them being nonsynonymous ones with an allele frequency greater than 5%. Nonsynonymous substitutions were not found in NP; meanwhile, many of these were allocated in PB2, PB1, and NS1 proteins. Regarding HA and NA proteins, higher nucleotide diversity, proportionally more nonsynonymous substitutions with an allele frequency greater than 5%, and different domain allocations of mutants, were observed in vaccinated animals, indicating different evolutionary dynamics. This study highlights the rapid adaptability of SIV in different environments.     

Genetic Analysis of Influenza A/H1N1 of Swine Origin Virus (SOIV) Circulating in Central and South America

Since the first detection of swine origin virus (SOIV) on March 28, 2009, the virus has spread worldwide and oseltamivir-resistant strains have already been identified in the past months. Here, we show the phylogenetic analysis of 63 SOIV isolates from eight countries in Central and South America, and their sensitivity to oseltamivir.     

Potential for a global dynamic of Influenza A (H1N1)

Background  

Geographical and temporal diffusion patterns of a human pandemic due to Swine Origin Influenza Virus (S-OIV) remain uncertain. The extent to which national and international pandemic preparedness plans and control strategies can slow or stop the process is not known. However, despite preparedness efforts, it appears that, particularly in the USA, Mexico, Canada and the UK, local chains of virus transmission can sustain autonomous dynamics which may lead to the next pandemic. Forecasts of influenza experts usually rely on information related to new circulating strains.     

新型甲型H1N1流感危重症临床分析

目的探讨新型甲型H1N1流感危重症患者的临床特点,加深认识,提高诊治水平。方法回顾性分析2009年11月—2011年2月收治的经临床和实验室确诊的8例新型甲型H1N1流感危重病例的临床资料。结果治愈6例,好转1例,死亡1例。结论青壮年、肥胖、伴基础疾病和妊娠的甲型H1N1流感患者易进展为危重症;早期应用奥司他韦,积极治疗基础疾病,控制细菌、真菌感染和液体出入量,实时机械通气并合理应用激素等综合治疗可改善预后,降低病死率。     

2009年甲型H1N1流感患者临床特点的研究

目的调查2009年甲型H1N1流感患者的临床特点。方法通过调查2009年11月至2010年2月符合流感疑似病例收治入院的136例患者,明确2009甲型H1N1流感组,季节性甲型流感组和非流感组的人口学情况,肺炎发生的差异,危重症发生的差异,以及实验室检测参数的差异,筛选出需要住院的流感疑似患者发生肺炎的危险因素。结果 2009甲型H1N1流感发病年龄更年轻（36±17岁）;孕妇的构成比（42.2%）高于其他组;发生肺炎的构成比（51.11%）高于其他组;病死1例。D-二聚体、AST、LDH异常增加的构成比明显大于其他发热患者。结论甲型H1N1流感的易感人群是年轻人和孕妇。甲型H1N1流感是发生肺炎的危险因素,容易并发肺炎和呼吸衰竭,及引起血凝系统、骨骼肌、心肌的损害。     

Prevalence,Genetics and Evolutionary Properties of Eurasian Avian-like H1N1 Swine Influenza Viruses in Liaoning

Swine influenza virus (SIV) is an important zoonosis pathogen. The 2009 pandemic of H1N1 influenza A virus (2009/H1N1) highlighted the importance of the role of pigs as intermediate hosts. Liaoning province, located in northeastern China, has become one of the largest pig-farming areas since 2016. However, the epidemiology and evolutionary properties of SIVs in Liaoning are largely unknown. We performed systematic epidemiological and genetic dynamics surveillance of SIVs in Liaoning province during 2020. In total, 33,195 pig nasal swabs were collected, with an SIV detection rate of 2%. Our analysis revealed that multiple subtypes of SIVs are co-circulating in the pig population in Liaoning, including H1N1, H1N2 and H3N2 SIVs. Furthermore, 24 H1N1 SIVs were confirmed to belong to the EA H1N1 lineage and divided into two genotypes. The two genotypes were both triple reassortant, and the predominant one with polymerase, nucleoprotein (NP), and matrix protein (M) genes originating from 2009/H1N1; hemagglutinin (HA) and neuraminidase (NA) genes originating from EA H1N1; and the nonstructural protein (NS) gene originating from triple reassortant H1N2 (TR H1N2) was detected in Liaoning for the first time. According to our evolutionary analysis, the EA H1N1 virus in Liaoning will undergo further genome variation.