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千葉大学教育学部研究紀要. 第一部

Analyse comparative du profil épidémiologique et clinique de l'infection grippale due aux virus pH1N1(2009), H1N1, H3N2 et B à Abidjan, Côte d'Ivoire

English Title: Comparative analysis of the epidemiological and clinical profiles of influenza infection due to 2009 pH1N1, H1N1, H3N2 and B viruses in Abidjan, Cote d'IvoireEnglish AbstractInfluenza can have various epidemiological and clinical characteristics. This study compares the epidemio-clinical profiles of influenza infections related to different viruses in the population of Abidjan. A review of surveillance data (2007-2010) on influenza was performed. We used Chi2 test to compare proportions and simple linear regression and sequential logistic regression models for prediction profiles on Stata 12 software. In tota1529 cases of influenza infection were recorded, including 60 cases of H1N1 (11.3% ), 177 cases ofH3N2 (33.5%), 34 cases of pH1N1 (6.4%) and258 cases of influenza B (48.8%). Fever prevailed  with H1N1 (76.1 %). The patients with pH1N1 were more likely to have cough (OR= 10.52, 95% CI: 1.713-64.575; versus H1N1) and to be from the age group of 5-14 years (OR= 3.10, 95% CI: 1.316-7.301; versus influenza B). For patients with influenza H3N2, cough (OR = 6.3, 95% CI: 2.466-16.347) and arthralgia/myalgia (OR= 2.54, 95% CI: 1.083-5.948) were the best predictors (versus influenza H1N1). The identification of specific profiles in our study can improve the method of diagnosis and surveillance of influenza.Keywords: Influenza Infection, epidemio-clinical profiles, Abidjan, Cote d'Ivoir

Epidemiological and virological characteristics of influenza B: results of the Global Influenza B Study

Contains fulltext : 155189.pdf (publisher's version ) (Open Access)INTRODUCTION: Literature on influenza focuses on influenza A, despite influenza B having a large public health impact. The Global Influenza B Study aims to collect information on global epidemiology and burden of disease of influenza B since 2000. METHODS: Twenty-six countries in the Southern (n = 5) and Northern (n = 7) hemispheres and intertropical belt (n = 14) provided virological and epidemiological data. We calculated the proportion of influenza cases due to type B and Victoria and Yamagata lineages in each country and season; tested the correlation between proportion of influenza B and maximum weekly influenza-like illness (ILI) rate during the same season; determined the frequency of vaccine mismatches; and described the age distribution of cases by virus type. RESULTS: The database included 935 673 influenza cases (2000-2013). Overall median proportion of influenza B was 22.6%, with no statistically significant differences across seasons. During seasons where influenza B was dominant or co-circulated (>20% of total detections), Victoria and Yamagata lineages predominated during 64% and 36% of seasons, respectively, and a vaccine mismatch was observed in approximately 25% of seasons. Proportion of influenza B was inversely correlated with maximum ILI rate in the same season in the Northern and (with borderline significance) Southern hemispheres. Patients infected with influenza B were usually younger (5-17 years) than patients infected with influenza A. CONCLUSION: Influenza B is a common disease with some epidemiological differences from influenza A. This should be considered when optimizing control/prevention strategies in different regions and reducing the global burden of disease due to influenza

Temporal Patterns of Influenza A and B in Tropical and Temperate Countries: What Are the Lessons for Influenza Vaccination?

Introduction Determining the optimal time to vaccinate is important for influenza vaccination programmes. Here, we assessed the temporal characteristics of influenza epidemics in the Northern and Southern hemispheres and in the tropics, and discuss their implications for vaccination programmes. Methods This was a retrospective analysis of surveillance data between 2000 and 2014 from the Global Influenza B Study database. The seasonal peak of influenza was defined as the week with the most reported cases (overall, A, and B) in the season. The duration of seasonal activity was assessed using the maximum proportion of influenza cases during three consecutive months and the minimum number of months with 80% of cases in the season. We also assessed whether co-circulation of A and B virus types affected the duration of influenza epidemics. Results 212 influenza seasons and 571,907 cases were included from 30 countries. In tropical countries, the seasonal influenza activity lasted longer and the peaks of influenza A and B coincided less frequently than in temperate countries. Temporal characteristics of influenza epidemics were heterogeneous in the tropics, with distinct seasonal epidemics observed only in some countries. Seasons with co-circulation of influenza A and B were longer than influenza A seasons, especially in the tropics. Discussion Our findings show that influenza seasonality is less well defined in the tropics than in temperate regions. This has important implications for vaccination programmes in these countries. High-quality influenza surveillance systems are needed in the tropics to enable decisions about when to vaccinate

Temporal patterns of influenza A and B in tropical and temperate countries: What are the lessons for influenza vaccination?

10.1371/journal.pone.0152310PLoS ONE113e015231