Reassortment of Ancient Neuraminidase and Recent Hemagglutinin in Pandemic (H1N1) 2009 Virus

Sequence analyses show that the outbreak of pandemic (H1N1) 2009 resulted from the spread of a recently derived hemagglutinin through a population of ancient and more diverse neuraminidase segments. This pattern implies reassortment and suggests that the novel form of hemagglutinin conferred a selective advantage

Pandemic (H1N1) 2009 Surveillance and Prevalence of Seasonal Influenza, Singapore

On April 25, 2009, Singapore implemented strict containment measures for pandemic (H1N1) 2009 with enhanced surveillance and hospital isolation. In the first month, seasonal influenza, predominantly virus subtype H3N2, was diagnosed for 32% of patients with acute febrile respiratory illness. Our findings underscore the high prevalence of seasonal influenza in Singapore

During the summer 2009 outbreak of "swine flu" in Scotland what respiratory pathogens were diagnosed as H1N1/2009?

<p>Abstract</p> <p>Background</p> <p>During the April-July 2009 outbreak of H1N1/2009 in scotland the West of Scotland Specialist Virology Centre (WoSSVC) in Glasgow tested > 16 000 clinical samples for H1N1/2009. Most were from patients clinically diagnosed with H1N1/2009. Out of these, 9% were positive. This study sought to determine what respiratory pathogens were misdiagnosed as cases of H1N1/2009 during this time.</p> <p>Methods</p> <p>We examined the results from 3247 samples which were sent to the laboratory during April-July 2009. All were from patients clinically diagnosed as having H1N1/2009 (based on accepted criteria) and all were given a full respiratory screen using real time reverse transcriptase polymerase chain reaction (rtRT-PCR) assays.</p> <p>Results</p> <p>In total, respiratory pathogens were detected in 27.9% (95% confidence interval, 26.3-29.5%) of the samples submitted. Numerous pathogens were detected, the most common of which were rhinovirus (8.9% (95% confidence interval, 7.9-9.9%)), parainfluenza 1 (1.9% (95% confidence interval, 1.4-2.4%)) and 3 (4.1% (95% confidence interval, 3.3-4.9%)), and adenovirus ((3.5% (95% confidence interval, 2.9-4.2%)).</p> <p>Conclusions</p> <p>This study highlights the problems of using a clinical algorithm to detect H1N1/2009. Clinicians frequently misdiagnosed common respiratory pathogens as H1N1/2009 during the spring/summer outbreak in Scotland. Many undesirable consequences would have resulted, relating to treatment, infection control, and public health surveillance.</p

Clinical Predictors of Novel Influenza A (H1N1) Infection in Korea

PURPOSE: Pandemic influenza A (H1N1) virus has spread rapidly and prompt diagnosis is needed for successful treatment and prevention of transmission. We investigated clinical predictors, validated the use of previous criteria with laboratory tests, and evaluated the clinical criteria for H1N1 infection in the Korean population. MATERIALS AND METHODS: We analyzed clinical and laboratory evaluation data from outpatient clinics at Severance Hospital in Seoul, Korea between November 11 and December 5, 2009. RESULTS: This analysis included a total of 828 patients. Of these, 372 (44.9%) patients were confirmed with H1N1 infection by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The most common and predictive symptom was cough (90.3%, OR 8.87, 95% CI 5.89- 13.38) and about 40% of H1N1-positive patients were afebrile. The best predictive model of H1N1 infection was cough plus fever or myalgia. The sensitivities, specificities, positive predictive values, and negative predictive values of our suggested criteria were 73.9%, 69.5%, 66.4%, and 76.6%, respectively. CONCLUSION: Cough was the most common independent symptom in patients with laboratory-confirmed H1N1 infection, and while not perfect, the combination of cough plus fever or myalgia is suggested as clinical diagnostic criteria. Health care providers in Korea should suspect a cough without fever to be an early symptom of H1N1 infection.ope

Characteristics of Outpatients with Pandemic H1N1/09 Influenza in a Tertiary Care University Hospital in Korea

The pandemic H1N1/09 emerged rapidly in Korea. Here, we describe the clinical characteristics of outpatients in Seoul, Korea who were infected in the 2009 H1N1 pandemic. We reviewed the cases of outpatients with pandemic H1N1/09 who visited a tertiary care teaching hospital between September 1 and December 31, 2009. Infection with pandemic H1N1/09 was confirmed by molecular tests. Of a total of 7,182 tests, 3,020 (42.0%) were positive. Compared with 473 cases of influenza-like illness (ILI), the 586 confirmed cases of pandemic H1N1/09 differed in age [odds ratio (OR) 0.975] and fulfilling at least one of the following factors: age <5 or ≥65 years, history of contact with other pandemic H1N1/09-infected individuals (OR 0.611), fever ≥37.8℃ (OR 3.567), cough (OR 2.290), and myalgia (OR 1.559). The sensitivity of the best criteria, "fever (≥37.8℃) plus cough" (41.03%) in this study was lower than that of the Korea Centers for Disease Control and Prevention (KCDC) criteria (47.95%), whereas the positive likelihood ratio (3.55) and positive predictive value (81.6) of this criteria was higher than those of the KCDC criteria (2.98 and 78.7, respectively). The clinical characteristics of pandemic H1N1/09 are, in many regards, indistinguishable from those of ILI. Moreover, the accuracy and predictability of criteria which include only symptoms or signs were not sufficient to diagnose pandemic H1N1/09 infection. Therefore, use of a combination of symptoms with confirmatory laboratory testing is necessary for accurate diagnosis of pandemic H1N1/09

CD4+/CD8+ T lymphocytes imbalance in children with severe 2009 pandemic influenza A (H1N1) pneumonia

PurposeThis study was conducted to investigate the immune responses of children with moderate and severe novel influenza A virus (H1N1) pneumonia, and to compare their clinical and immunological findings with those of control subjects.MethodsThirty-two admitted patients with H1N1 pneumonia were enrolled in the study. The clinical profiles, humoral and cell-mediated immune responses of the 16 H1N1 pneumonia patients who were admitted to the pediatric intensive care unit (severe pneumonia group), 16 H1N1 pneumonia patients admitted to the pediatric general ward (moderate pneumonia group) and 13 control subjects (control group) were measured.ResultsTotal lymphocyte counts were significantly lower in patients with H1N1 pneumonia than in the control group (P=0.02). The number of CD4+ T lymphocytes was significantly lower in the severe pneumonia group (411.5±253.5/µL) than in the moderate pneumonia (644.9±291.1/µL, P=0.04) and control (902.5±461.2/µL, P=0.01) groups. However, the number of CD8+ T lymphocytes was significantly higher in the severe pneumonia group (684.2±420.8/µL) than in the moderate pneumonia (319.7±176.6/µL, P=0.02) and control (407.2±309.3/µL, P=0.03) groups. The CD4+/CD8+ T lymphocytes ratio was significantly lower in the severe pneumonia group (0.86±0.24) than in the moderate pneumonia (1.57±0.41, P=0.01) and control (1.61±0.49, P=0.01) groups. The serum levels of IgG, IgM and IgE were significantly higher in the severe pneumonia group than in the 2 other groups.ConclusionThe results of this study suggest that increased humoral immune responses and the differences in the CD4+ and CD8+ T lymphocyte profiles, and imbalance of their ratios may be related to the severity of H1N1 pneumonia in children

Radiological and Clinical Characteristics of a Military Outbreak of Pandemic H1N1 2009 Influenza Virus Infection

Objective: To describe detailed clinical and radiological features of the pandemic H1N1 2009 influenza viral infection among healthy young males in a semi-closed institutionalized setting. Materials and Methods: A total of 18 patients confirmed with the pandemic H1N1 2009 influenza virus infection from July 18 to July 30, 2009 were enrolled in this study. Each patient underwent an evaluation to determine detailed clinical and radiological features. Results: All patients presented with high fever (> 38.0 degrees C), with accompanying symptoms of cough, rhinorrhea, sore throat, myalgia and diarrhea, and increased C-reactive protein (CRP) values with no leukocytosis nor elevated erythrocyte sedimentation rate (ESR). All patients, including one patient who progressed into acute respiratory distress syndrome, were treated with oseltamivir phosphate and quickly recovered from their symptoms. Chest radiographs showed abnormalities of small nodules and lobar consolidation in only two out of 18 patients. However, six of 12 patients who underwent thin-section CT examinations showed abnormal findings for small ground-glass opacities (GGOs) in addition to poorly-defined nodules with upper lobe predominance. Conclusion: In a population of healthy young adults, elevated CRP with normal ESR and white blood cell levels combined with GGOs and nodules on thin-section CT scans may indicate early signs of infection by the pandemic H1N1 2009 influenza virus.Agarwal PP, 2009, AM J ROENTGENOL, V193, P1488, DOI 10.2214/AJR.09.3599Ajlan AM, 2009, AM J ROENTGENOL, V193, P1494, DOI 10.2214/AJR.09.3625Lee CW, 2009, KOREAN J RADIOL, V10, P531, DOI 10.3348/kjr.2009.10.6.531Chowell G, 2009, NEW ENGL J MED, V361, P674, DOI 10.1056/NEJMoa0904023Perez-Padilla R, 2009, NEW ENGL J MED, V361, P680, DOI 10.1056/NEJMoa0904252Dawood FS, 2009, NEW ENGL J MED, V360, P2605, DOI 10.1056/NEJMoa0903810Shinde V, 2009, NEW ENGL J MED, V360, P2616, DOI 10.1056/NEJMoa0903812Belshe RB, 2009, NEW ENGL J MED, V360, P2667, DOI 10.1056/NEJMe09039952009, MMWR MORB MORTAL WKL, V58, P536*WHO, 2009, WKLY EPIDEMIOL REC, V84, P185*US CDCP, 2009, INT WHO GUID SURV HUHansell DM, 2008, RADIOLOGY, V246, P697DOLIN R, 2008, HARRISONS PRINCIPLES, P1127Grinblat L, 2003, RADIOLOGY, V228, P802, DOI 10.1148/radiol.2283030671Wong KT, 2003, RADIOLOGY, V228, P395, DOI 10.1148/radiol.2283030541*WHO, WORLD NOW START 2009*WHO, INFL A H1N1 UPD 68