Outcome of pandemic H1N1 infections in hematopoietic stem cell transplant recipients

During 2009, a new strain of A/H1N1 influenza appeared and became pandemic. A prospective study was performed to collect data regarding risk factors and outcome of A/H1N1 in hematopoietic stem cell transplant recipients. Only verified pandemic A/H1N1 influenza strains were included: 286 patients were reported, 222 allogeneic and 64 autologous recipients. The median age was 38.3 years and the median time from transplant was 19.4 months. Oseltamivir was administered to 267 patients and 15 patients received zanamivir. One hundred and twenty-five patients (43.7%) were hospitalized. Ninety-three patients (32.5%) developed lower respiratory tract disease. In multivariate analysis, risk factors were age (OR 1.025; 1.01-1.04; P=0.002) and lymphopenia (OR 2.49; 1.33-4.67; P<0.001). Thirty-three patients (11.5%) required mechanical ventilation. Eighteen patients (6.3%) died from A/H1N1 infection or its complications. Neutropenia (P=0.03) and patient age (P=0.04) were significant risk factors for death. The 2009 A/H1N1 influenza pandemic caused severe complications in stem cell transplant recipients.     

儿童甲型H1N1流行性感冒病毒相关性肺炎的临床特征

目的 了解儿童甲型H1N1流行性感冒(流感)病毒相关性肺炎的临床流行特征.方法 通过描述性研究对2009年上海复旦大学附属儿科医院收治的30例甲型H1N1流感病毒所致肺炎的患儿做临床及流行病学分析.中位数比较采用秩和检验,率的比较采用精确卡方检验.结果 30例确诊为甲型H1N1流感合并肺炎的患儿中,年龄中位数为5.9岁,5例有基础疾病史,占16.7%.有明确发热病例暴露史的20例,占66.7%.所有患儿均有发热和咳嗽,11例伴气促,占36.7%,10例伴喘息,占33.3%.11例患儿WBC＜4.0×109/L,占36.7%,2例PLT减少,占6.7%.所有患儿入院时胸部X线片提示肺部有单侧或双侧片状渗出性病灶,4例危重症患儿肺部多处大片状渗出伴肺水肿,占13.3%,1例危重症肺炎患儿发病后3个月和9个月复查胸部CT提示不同程度肺纤维化,占3.3%,3例同时伴纵隔积气和皮下积气,占10.0%,6例并发急性呼吸衰竭,占20.0%,3例伴支气管哮喘急性发作,占10.0%,1例合并脑炎,占3.3%.所有患儿均给予奥司他书和抗菌药物治疗,4例接受机械通气,均治愈或好转出院.发病2 d内和2 d后接受奥司他韦治疗的患儿的热程中位数比较差异有统计学意义(2 d比5 d,Z=-8.015,P＜0.01).结论 学龄前和学龄儿童易感染甲型H1N1流感病毒,可并发严重的肺部疾病.在发病早期采用奥司他韦治疗,可缩短热程,降低危重并发症的发生.     

Role of procalcitonin and C-reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia

Please cite this paper as: Ahn et al. (2011) Role of procalcitonin and C‐reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia. Influenza and Other Respiratory Viruses 5(6), 398–403. Background Mixed bacterial infection is an important contributor to morbidity and mortality during influenza pandemics. We evaluated procalcitonin (PCT) and C‐reactive protein (CRP) in differentiating pneumonia caused by mixed bacterial and 2009 H1N1 influenza infection from 2009 H1N1 influenza infection alone. Methods Data were collected retrospectively over a 7‐month period during the 2009 H1N1 influenza pandemic. Patients visiting emergency department and diagnosed as community‐acquired pneumonia caused by 2009 H1N1 infection were included (n = 60). Results Mixed bacterial and viral infection pneumonia (n = 16) had significantly higher PCT and CRP levels than pneumonia caused by 2009 H1N1 influenza alone (n = 44, P = 0·019, 0·022 respectively). The sensitivity and specificity for detection of mixed bacterial infection pneumonia was 56% and 84% for PCT > 1·5 ng/ml, and 69% and 63% for CRP > 10 mg/dl. Using PCT and CRP in combination, the sensitivity and specificity were 50% and 93%, respectively. Conclusion Procalcitonin and CRP alone and their combination had a moderate ability to detect pneumonia of mixed bacterial infection during the 2009 H1N1 pandemic. Considering high specificity, combination of low CRP and PCT result may suggest that pneumonia is unlikely to be caused by mixed bacterial infection.     

北京市2009年甲型H1N1流行性感冒危重症与死亡病例流行病学特征及其影响因素分析

目的 了解北京市2009年甲型H1N1流行性感冒(流感)危重症与死亡病例的流行病学特征,探讨影响甲型H1N1流感病情严重程度的主要因素.方法 利用北京市2009年甲型H1N1流感病例个案信息进行描述性分析和多因素Logistic回归分析.结果 北京市2009年甲型H1N1流感感染率为66.1/10万,25～60岁组人群感染率最高,为86.8/10万.0～5岁组和60岁以上年龄组危重症感染率(12.5/10万,3.9/10万)、死亡率(0.9/10万,0.7/10万)和病死率(2.4%,3.3%)较高.549例危重症病例中学龄前儿童110例,比例最高,占20.0%,69例死亡病例中离、退休人员17例,比例最高,占24.6%.超过70.0%的危重症和死亡病例均在发病后2 d内到医院就诊.危重症病例和死亡病例中,均以有心血管疾病的病例比例最高,其次为慢性肺部疾病.多因素Logistic回归分析显示,甲型H1N1流感病例中,60岁以上、慢性肺部疾病及心血管疾病可能导致其病情较重,OR值分别为3.586(95%CI 1.586～8.117)、2.126(95%CI 1.178～3.835)和1.954(95%CI 1.126～3.391).结论 60岁以上、伴心血管疾病及慢性肺部疾病等因素可能加重甲型H1N1流感病例病情.     

北京市2009年甲型H1N1流行性感冒危重症与死亡病例流行病学特征及其影响因素分析

目的 了解北京市2009年甲型H1N1流行性感冒(流感)危重症与死亡病例的流行病学特征,探讨影响甲型H1N1流感病情严重程度的主要因素.方法 利用北京市2009年甲型H1N1流感病例个案信息进行描述性分析和多因素Logistic回归分析.结果 北京市2009年甲型H1N1流感感染率为66.1/10万,25～60岁组人群感染率最高,为86.8/10万.0～5岁组和60岁以上年龄组危重症感染率(12.5/10万,3.9/10万)、死亡率(0.9/10万,0.7/10万)和病死率(2.4%,3.3%)较高.549例危重症病例中学龄前儿童110例,比例最高,占20.0%,69例死亡病例中离、退休人员17例,比例最高,占24.6%.超过70.0%的危重症和死亡病例均在发病后2 d内到医院就诊.危重症病例和死亡病例中,均以有心血管疾病的病例比例最高,其次为慢性肺部疾病.多因素Logistic回归分析显示,甲型H1N1流感病例中,60岁以上、慢性肺部疾病及心血管疾病可能导致其病情较重,OR值分别为3.586(95%CI 1.586～8.117)、2.126(95%CI 1.178～3.835)和1.954(95%CI 1.126～3.391).结论 60岁以上、伴心血管疾病及慢性肺部疾病等因素可能加重甲型H1N1流感病例病情.     

Incidence and characteristics of the 2009 influenza (H1N1) infections in inflammatory bowel disease patients

BackgroundIn 2009, influenza A (H1N1) infections spread worldwide. Because the use of immunomodulators is associated with an increased risk of infection, inflammatory bowel disease (IBD) patients who are on immunomodulators might be concerned about H1N1 influenza infections. The aim of this study was to investigate the age distribution and risk factors associated with H1N1 influenza of IBD patients in 2009–2010.MethodsA multicenter, prospective study was conducted, and 570 IBD patients were enrolled. Patients were followed up for 10 months to identify any new infections. The incidence and age distribution of the H1N1 influenza infections were analyzed. IBD patients with H1N1 influenza infections and 2 matched, noninfected IBD patients were selected to assess the effect of specifying the medication on the incidence of infections.ResultsA total of 38 patients (6.7%) developed H1N1 influenza infections. The incidence of H1N1 influenza infections in patients aged less than 20 years was significantly higher than that among patients in other age groups (p < 0.01). The age distribution for H1N1 influenza infections in IBD patients was comparable to those in the general population. No patients needed hospitalization due to influenza infection. A total of 29 patients (76%) recovered from the H1N1 influenza symptoms within 7 days and 20 patients (53%) received antiviral treatment. The percentage of patients who used steroids or thiopurine was comparable between the cases of H1N1 influenza infection and the control group.ConclusionOur prospective study showed that younger IBD patients were frequently infected with the influenza A (H1N1) virus as well as general population. Admission and fatal cases due to H1N1 influenza infections were not observed.     

Clinical characteristics and outcomes of hospitalized patients with 2009 H1N1 influenza in a large acute care tertiary hospital, Singapore

This study describes the clinical characteristics and outcomes of hospitalized patients with 2009 H1N1 influenza in a large, acute care, tertiary hospital in Singapore. Of the 265 hospitalized patients with laboratory-confirmed 2009 influenza A (H1N1) during the height of the H1N1 flu pandemic, 13% (35) suffered severe outcomes including a mortality rate of 4.5% (12). Severe outcomes were associated with patients aged 40 years or more, underlying comorbidities, and complicated by pneumonia.     

Comparison of the patients with pandemic (H1N1) influenza A virus pneumonia and community-acquired pneumonia

Prognosis of pandemic influenza A (H1N1) virus pneumonia is worse than community-acquired pneumonia (CAP), therefore it is important to know distinctive clinical features of both pneumonias. The aims of this study were to compare clinical features and prognosis of patients with pandemic influenza A (H1N1) pneumonia and CAP due to other agents. Demographic features, symptoms and findings of 20 pandemic influenza A (H1N1) pneumonia and 18 CAP patients hospitalized between October 1st and December 30th, 2009 were evaluated. One patient (5.0%) with pandemic Influenza A (H1N1) pneumonia and 55.6% of CAP patients were over 65 years (p= 0.001). Symptoms of fever, dyspnea, fatigue, muscle and joint pain, nausea, vomiting and headache were more frequent (p< 0.05), platelet count (p= 0.024) and PaO(2)/FiO(2) ratio (p= 0.006) were lower, number of thrombocytopenic patients (p= 0.024) and LDH levels (p= 0.016) were higher, duration of hospitalization was longer (p= 0.038) in patients with pandemic influenza A (H1N1) pneumonia. There was no difference in terms of radiological findings between two groups. None of the CAP patients were followed-up in the intensive care, whereas five pandemic influenza A (H1N1) pneumonia patients (25.0%) required intensive care and three of them died despite invasive mechanical ventilation. In conclusion, in the presence of fever, dyspnea with non-pulmonary symptoms and accompanying radiological alveolar opacities should be considered as pandemic influenza A (H1N1) pneumonia should be suspected in patients admitted with findings of pneumonia during influenza season. Admission to the intensive care unit and mechanical ventilation should be considered in patients with dyspnea and diffuse radiological findings.     

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.     

Clinical aspects of 2009 pandemic influenza A (H1N1) virus infection in Austria

Purpose

To describe the clinical features, risk factors for severe disease and effectiveness of oseltamivir in patients with 2009 pandemic influenza A (H1N1) virus infection.

Methods

In a prospective, cross-sectional, multicentre study, data on 540 patients with confirmed 2009 H1N1 infection from seven Austrian hospitals were collected using a standardised online case-history form.

Results

The median age of the patients was 19.3 years (range 26 days–90.8 years); point-of-care testing yielded false-negative results in 60.2% of the 176 cases tested. The most common symptoms were fever, cough, fatigue and headache. Overall, 343 patients (63.5%) were hospitalised, 49 (9.1%) were admitted to an intensive care unit (ICU) and 14 (4.1%) died. Case fatality rates were highest (9.1%) in those aged 65 years or older. Factors significantly associated with a higher risk for ICU admission included age, neurological disease, adipositas, and both interstitial pathology and lobular pathology on chest X-ray. No association with pregnancy, malignancy or immunosuppressive therapy was detected. Antiviral treatment significantly reduced the duration of fever by 0.66 days and lowered the risk of ICU admission, but had no significant benefit on survival.

Conclusions

During the 2009 H1N1 influenza pandemic, elderly or obese patients and those with neurological disease had an increased risk for severe H1N1 infection in Austria. Pregnancy was not associated with a higher risk for severe disease in the later phase of the 2009 H1N1 pandemic. Antiviral treatment provided a minimal effect on the symptoms of influenza but reduced the risk of admission to an ICU.     

Population‐based surveillance for 2009 pandemic influenza A (H1N1) virus in Guatemala, 2009

Please cite this paper as: Reyes et al. (2010) Population‐based surveillance for 2009 pandemic influenza A (H1N1) virus in Guatemala, 2009. Influenza and Other Respiratory Viruses 4(3), 129–140. Background  In April 2009, 2009 pandemic influenza A H1N1 (2009 H1N1) was first identified in Mexico but did not cause widespread transmission in neighboring Guatemala until several weeks later. Methodology and principle findings  Using a population‐based surveillance system for hospitalized pneumonia and influenza‐like illness ongoing before the 2009 H1N1 pandemic began, we tracked the onset of 2009 H1N1 infection in Guatemala. We identified 239 individuals infected with influenza A (2009 H1N1) between May and December 2009, of whom 76 were hospitalized with pneumonia and 11 died (case fatality proportion: 4·6%, 95% confidence interval [CI] 2·3–8·1%). The median age of patients infected with 2009 H1N1 was 8·8 years, the median age of those hospitalized with pneumonia was 4·2 years, and five (45·5%) deaths occurred in children <5 years old. Crude rates of hospitalization between May and December 2009 were highest for children <5 years old. Twenty‐one (27·6%) of the patients hospitalized with 2009 H1N1 were admitted to the intensive care unit and eight (10·5%) required mechanical ventilation. Underlying chronic conditions were noted in 14 (18·4%) of patients with pneumonia hospitalized with 2009 H1N1 infection. Conclusions and significance  Chronic illnesses may be underdiagnosed in Guatemala, making it difficult to identify this risk group for vaccination. Children 6 months to 5 years old should be among priority groups for vaccination to prevent serious consequences because of 2009 H1N1 infection.     

Influenza-associated bacterial pathogens in patients with 2009 influenza A (H1N1) infection: impact of community-associated methicillin-resistant Staphylococcus aureus in Queensland, Australia

Background: Secondary bacterial pneumonia due to community onset methicillin‐resistant Staphylococcus aureus (MRSA) has become a highly publicised cause of influenza‐associated death. There is a risk that case reports of fatal outcomes with post‐influenza MRSA pneumonia may unduly influence antibiotic prescribing. Aims: The aim of this study was to demonstrate the incidence of community‐onset MRSA pneumonia in 2009 H1N1 influenza patients. Methods: The microbiology records of patients positive for influenza A (H1N1) in 2009 were reviewed for positive blood or respiratory tract cultures and urinary pneumococcal antigen results within a Queensland database. Patients with such positive results within 48 h of hospital admission and a positive H1N1 influenza result in the prior 6 weeks were included. Results: In 2009, 4491 laboratory‐confirmed pandemic influenza A (H1N1) infections were detected. Fifty patients (1.1% of the H1N1 cohort) who were hospitalised with H1N1 and who had a bacterial respiratory tract pathogen were identified. Streptococcus pneumoniae (16 patients; 32%), Staphylococcus aureus (13 patients; 26%) and Haemophilus influenzae (9 patients; 18%) were the most commonly cultured organisms. Of the cohort of 4491 patients, MRSA was detected in only two patients, both of whom were admitted to intensive care units and survived after prolonged admissions. Conclusions: Influenza‐associated community‐onset MRSA pneumonia was infrequently identified in the 2009 H1N1 season in Queensland, despite community‐onset MRSA skin and soft tissue infections being very common. Although post‐influenza MRSA pneumonia is of great concern, its influence on empiric‐prescribing guidelines should take into account its incidence relative to other secondary bacterial pathogens.     

新型甲型H1N1流感危重症存活和死亡病例的临床特点分析

目的 了解新型甲型H1N1流感(简称甲型流感)危重病例的临床特点,探讨与死亡相关的危险因素. 方法 采用前瞻性研究方法分析北京地坛医院2009年10月3日至12月15日收治的55例甲型流感危重病例的临床特点,并对存活病例和死亡病例进行比较分析. 结果 55例中男31例,女24例,年龄10个月至84岁,平均(38±20)岁.危重患者中<65岁48例(48/55),肥胖33例(33/49),伴基础疾病26例(26/49),妊娠6例(6/24),临床表现为高热、咳嗽、咳痰(部分为血痰)及呼吸困难,双肺可闻及干湿性啰音.55例中54例并发呼吸衰竭,26例并发ARDS,38例需行机械通气;27例继发感染,其中肺部感染24例(呼吸机相关肺炎10例).发病早期C反应蛋白升高,平均为(131±130)mg/L,CD4+及CD8+T细胞计数降低,分别为(217±139)/μl和(162±82)/μl;随病程进展,死亡病例的C反应蛋白持续升高,T细胞亚群计数持续降低,继发真菌感染的比例明显高于存活组(P<0.05);Logistic回归分析结果显示,体重指数高及继发真菌感染的患者病死率明显增高(OR值分别为6.512和19.631,P均<0.05);发病48 h内使用奥司他韦抗病毒治疗者中未出现死亡病例. 结论 青壮年、肥胖、伴基础疾病和妊娠的甲型流感患者易进展为危重症;C反应蛋白水平持续升高及T细胞亚群计数持续降低提示预后不良;体重指数高及继发真菌感染者病死率高;早期应用奥司他韦治疗可降低病死率.     

Emergence of 2009A/H1N1 cases in a tertiary care hospital in New Delhi, India

Please cite this paper as: Broor et al. (2011) Emergence of 2009A/H1N1 cases in a tertiary care hospital in New Delhi, India. Influenza and Other Respiratory Viruses 5(6), e552–e557. Objective To determine virologic and epidemiologic characteristics of pandemic (H1N1) 2009 at All India Institute of Medical Sciences (AIIMS) a tertiary care hospital in New Delhi, India. Methods Nasal and throat swabs from patients with febrile acute respiratory illness (FARI) from August to December 2009 (n = 1401) were tested for 2009A/H1N1 and seasonal influenza A viruses by real‐time RT‐PCR. Results Of 1401 samples tested, 475 (33·9%) were positive for influenza A, of these majority (412; 87%) were 2009A/H1N1, whereas the remaining 63 (13%) were seasonal influenza A (49 were A/H3 and 14 were A/H1). While co‐circulation of 2009A/H1N1 and A/H3 was observed in August–September, subsequent months had exclusive pandemic influenza activity (October–December 2009). Pandemic 2009A/H1N1 emergence did not follow typical seasonal influenza seasonality in New Delhi, which normally peaks in July–August, but instead showed bimodal peaks in weeks 39 and 48 in 2009. The percent of specimens testing positive for 2009A/H1N1 influenza virus was found to be highest in >5‐ to 18‐year age group (41·2%; OR = 2·3; CI = 1·6–3·2; P = 0·00). Conclusions Taken together, our data provide high prevalence of pandemic 2009A/H1N1 in urban New Delhi with bimodal peaks in weeks 39 and 48 and highest risk group being the children of school‐going age (aged >5–18).     

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。     

Differences in clinical outcomes after 2009 influenza A/H1N1 and seasonal influenza among hematopoietic cell transplant recipients

It is not known whether pandemic 2009 influenza A/H1N1 (2009 H1N1) leads to more serious disease than seasonal influenza in hematopoietic cell transplant (HCT) recipients. In a retrospective study in HCT recipients with virologically proven influenza virus infection, a total of 161 HCT recipients (18 2009 H1N1, 103 seasonal influenza A, and 40 seasonal influenza B) were analyzed. In multivariable analyses, more patients with 2009 H1N1 had lower respiratory tract disease (LRD), hypoxemia, and prolonged viral shedding compared with seasonal influenza A. Seasonal influenza A and B outcomes were similar. There was no difference in overall and influenza-associated mortality among influenza virus types. Both early and delayed administration of antiviral therapy was shown to be beneficial in terms of decreased rates of development of LRD, although earlier intervention appeared to be more effective. Profound lymphopenia and lack of early antiviral therapy were associated significantly with LRD, hypoxemia, and death. High-dose corticosteroid treatment (≥ 1 mg/kg) given at the time of influenza diagnosis was associated with a reduced risk for mechanical ventilation. Thus, our data suggest that infection with 2009 influenza A/H1N1 resulted in more severe respiratory disease in HCT recipients compared with seasonal influenza.     

Clinical presentation and lung function of children hospitalized with 2009 pandemic influenza A (H1N1) pneumonia

To determine the clinical presentation and subsequent lung function following pneumonia caused by 2009 pandemic influenza A (H1N1), pH1N1, in children aged 5-15 years hospitalized from June to September 2009, we contacted patients meeting the criterion 3-6 months post-hospitalization. Of the 88 patients contacted, 31 (35.2%) had pH1N1 and 57 (64.8%) had infections due to other viral pathogens (non-pH1N1), the mean age was 10.4 years and 52 (59%) were boys. Compared to non-pH1N1 patients, the pH1N1 patients were more likely to have a high fever (96.8% vs 77.2%, p = 0.03), sore throat (58.1% vs 33.3%, p = 0.03), and injected pharynx (80.6% vs 40.4%, p = 0.001). At 3-6 months after pneumonia onset, means for FVC, FEV1, FEV1/FVC, FEF25-75%, and PEF were within normal limit in both the pH1N1 and non-pH1N1 groups. Five (28%) of 18 pH1N1 children and 4 (20%) of 20 non-pH1N1 children had abnormal lung function results. All were restrictive type. In conclusion, pH1N1 pneumonia were more likely to present with high fever, sore throat, and pharyngeal injection than pneumonia from other viruses. About one quarter of the children who had pH1N1 had restrictive lung function 3-6 months after infection. This number did not differ from the non-pH1N1 group.     

Severe influenza A(H1N1)2009 infection: a single centre experience and review of the literature

The first influenza pandemic of the 21st century started in April 2009 with an outbreak of swine origin influenza A(H1NI)2009 in Mexico and the United States. While generally a mild disease affecting mostly school-aged children and young adults, most attention went to severe cases of pneumonia in young previously healthy individuals or individuals belonging to a risk group. In this article we review the literature on the presentation and management of severe cases of influenza A(H1N1)2009 in the intensive care unit (ICU), and describe our own experience in a tertiary referral centre with ECMO facilities. Pregnant women and (bone marrow) transplant patients are two known risk groups for severe influenza described more thoroughly in this paper.These severely ill patients are characterized by respiratory failure, resulting often in the need of mechanical ventilation. As Oseltamivir resistance remains low up till now, early antiviral therapy with Oseltamivir is warranted in these cases. Despite pharmacological and ventilator management, refractory hypoxaemia is described frequently in these patients, with need for rescue therapies like nitric oxide inhalation, high frequency ventilation, and extracorporeal membrane oxygenation. The value of the use of corticosteroids is under discussion. Despite advances in management strategies, mortality and morbidity in these severe cases remains high. In the first influenza season after the pandemic, winter 2010/2011, influenza A(H1N1)2009 is the major influenza A strain in Europe, resulting in reports with increased mortality and morbidity compared to pre-pandemic seasonal influenza. "Continuing vigilance for severe influenza in patients not belonging to the classical influenza risk group might still be warranted for the upcoming influenza season".     

Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia

Please cite this paper as: Song et al. (2011). Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia. Influenza and Other Respiratory Viruses 5(6), e535–e543. Background Although influenza virus usually involves the upper respiratory tract, pneumonia was seen more frequently with the 2009 pandemic influenza A/H1N1 than with seasonal influenza. Methods From September 1, 2009, to January 31, 2010, a specialized clinic for patients (aged ≥15 years) with ILI was operated in Korea University Guro Hospital. RT‐PCR assay was performed to diagnose 2009 pandemic influenza A/H1N1. A retrospective case–case–control study was performed to determine the predictive factors for influenza pneumonia and to discriminate concomitant/secondary bacterial pneumonia from primary influenza pneumonia during the 2009–2010 pandemic. Results During the study period, the proportions of fatal cases and pneumonia development were 0·12% and 1·59%, respectively. Patients with pneumonic influenza were less likely to have nasal symptoms and extra‐pulmonary symptoms (myalgia, headache, and diarrhea) compared to patients with non‐pneumonic influenza. Crackle was audible in just about half of the patients with pneumonic influenza (38·5% of patients with primary influenza pneumonia and 53·3% of patients with concomitant/secondary bacterial pneumonia). Procalcitonin, C‐reactive protein (CRP), and lactate dehydrogenase were markedly increased in patients with influenza pneumonia. Furthermore, procalcitonin (cutoff value 0·35 ng/ml, sensitivity 81·8%, and specificity 66·7%) and CRP (cutoff value 86·5 mg/IU, sensitivity 81·8%, and specificity 59·3%) were discriminative between patients with concomitant/secondary bacterial pneumonia and patients with primary influenza pneumonia. Conclusions Considering the subtle manifestations of 2009 pandemic influenza A/H1N1 pneumonia in the early stage, high clinical suspicion is required to detect this condition. Both procalcitonin and CRP would be helpful to differentiate primary influenza pneumonia from concomitant/secondary bacterial pneumonia.