摘要 :
The influence that atmospheric conditions might have on the efficiency of the spread of influenza virus is important for epidemiological and evolutionary research. However, it has not been satisfactorily recognized and quantified ...
展开
The influence that atmospheric conditions might have on the efficiency of the spread of influenza virus is important for epidemiological and evolutionary research. However, it has not been satisfactorily recognized and quantified so far. Here we provide a statistical model of influenza transmission between individuals. It has been derived from the results of recent experiments, which involved infecting guinea pigs with influenza at various temperatures and relative air humidity levels. The wide range of transmission rates in those experiments reflects the ensemble-independent phenomena. The correlation between most of our simulations and the experimental results is satisfactory. For several different conditions, we obtained transmissibility values which seem to be sufficiently accurate to provide partial input for an intended large-scale epidemiological study in the near future.
收起
摘要 :
The spread efficiency of influenza virus is significantly affected by several environmental parameters. However, neither the underlying reasons, nor the exact character and magnitude of the phenomena involved are sufficiently well...
展开
The spread efficiency of influenza virus is significantly affected by several environmental parameters. However, neither the underlying reasons, nor the exact character and magnitude of the phenomena involved are sufficiently well understood. Here we present a probabilistic approach to the virus transmission events. For a sample ensemble, we construct a model of the infectivity as a function of the ambient conditions, and we determine its parameter values on the basis of the available experimental data.
收起
摘要 :
SUMMARY The aim of this study was to investigate the epidemiology of influenza A virus infection in Cyprus from the 2009 pandemic until 2013. Pandemic influenza A(H1N1)2009 virus infections outnumbered infections with other respir...
展开
SUMMARY The aim of this study was to investigate the epidemiology of influenza A virus infection in Cyprus from the 2009 pandemic until 2013. Pandemic influenza A(H1N1)2009 virus infections outnumbered infections with other respiratory viruses until the end of 2009. The pandemic virus was also the prevalent influenza strain during influenza season 2010-2011; however, it was completely replaced by H3N2 subtype in the next season. During the most recent influenza season, 2012-2013, the pandemic strain was once again the only influenza A virus circulating in Cyprus. Full-length neuraminidase gene sequencing revealed mutations that had previously been identified as permissive. No significant difference in the expression of the IFN-inducible genes OAS and IFIT1 were observed. The phylogenetic analysis of the neuraminidase gene sequences revealed a picture of continuous importation of influenza strains in the island of Cyprus with local circulation playing only a minor role in determining the prevalent strain of the next influenza season.
收起
摘要 :
In Pakistan, the burden of influenza was largely unknown, as no formal surveillance system was in place. In 2008, an influenza surveillance system was set up in eight sentinel sites. This study describes the epidemiology of influe...
展开
In Pakistan, the burden of influenza was largely unknown, as no formal surveillance system was in place. In 2008, an influenza surveillance system was set up in eight sentinel sites. This study describes the epidemiology of influenza virus using a 10-year surveillance data from 2008 to 2017. Nasopharyngeal/throat swabs were collected from patients with influenza-like illness (ILI) and severe acute respiratory illness (SARI) along with relevant epidemiological information. The samples were tested using real-time reverse transcriptase-polymerase chain reaction for the detection and characterization of influenza viruses. A total of 17 209 samples were tested for influenza, out of which 3552 (20.6%) were positive; 2151/11 239 (19.1%) were patients with ILI, whereas 1401/5970 (23.5%) were patients with SARI. Influenza A/H1N1pdm09 was the predominant strain with 40.6% (n = 1442) followed by influenza B (936, 26.4%). Influenza A/H1N1pdm09 was predominant among the children (5-14 years) and adults (15-64 years). Influenza B strain was predominantly found in the elderly age group (>= 65 years) accounting for 48% of cases followed by children (2-4 years) accounting for 37% of cases. This 10-year surveillance data provides evidence of influenza activity in the country throughout the year with seasonal winter peaks. The results could be used to strengthen the epidemic preparedness and response plan.
收起
摘要 :
Objectives: During the 2009 influenza A (H1N1) pandemic, unusual influenza activity outside the typical winter season provided a unique opportunity to evaluate the association between influenza and pneumonia incidence. We sought t...
展开
Objectives: During the 2009 influenza A (H1N1) pandemic, unusual influenza activity outside the typical winter season provided a unique opportunity to evaluate the association between influenza and pneumonia incidence. We sought to quantify the impact of the 2009 pandemic on the incidence of emergency department (ED) visits for pneumonia in the United States (US). Methods: Using the Nationwide Emergency Department Survey, we estimated monthly counts and rates of excess all-cause pneumonia ED visits in the US attributable to the pandemic by comparing observed pneumonia ED visits during the pandemic (April 2009-March 2010) to expected values modeled from the three prior years. Results: The pandemic was associated with an excess of 180,560 pneumonia ED visits or 0.59 excess pneumonia visits per 1000 US population (95% confidence interval: 0.55, 0.62). These excess visits accounted for 7.0% of all pneumonia ED visits during the pandemic year. The greatest excess occurred during months with highest influenza activity (September-November 2009). Persons aged <65 years accounted for 94% of the excess pneumonia visits. Conclusions: ED visits for pneumonia increased substantially during the 2009 pandemic, especially during peak influenza activity, suggesting a strong association between influenza activity and pneumonia incidence during the pandemic period.
收起
摘要 :
Abstract Surveillance and reporting of epidemiological features of seasonal influenza mostly are aggregates across all‐ages. We investigated age‐specific differences in distribution of influenza virus (sub)types in tropical Sing...
展开
Abstract Surveillance and reporting of epidemiological features of seasonal influenza mostly are aggregates across all‐ages. We investigated age‐specific differences in distribution of influenza virus (sub)types in tropical Singapore, using laboratory‐confirmed virological data collected under the national influenza surveillance programme?from 2011 to 2017. The proportion of influenza‐positive specimens from outpatients with influenza‐like illness was used as an indicator of influenza activity in the community. The highest influenza positivity for age groups of 5 to 14 years and 15 to 64 years coincided in the same month in 5 out of the 7 years under study. Influenza positivity was lowest in young children <5 years of age compared with older age groups. Influenza A(H3N2) was most prevalent in the community except in 2012 when a predominance of influenza B was observed. The dominant virus (sub)type varied across the years in children <5 years and 5 to 14 years of age. Influenza A(H3N2) was the predominant circulating virus subtype among elderly persons aged ≥65 years during the 7‐year period, and among adults aged 15 to 64 years since 2013. Knowledge about the age‐specific differences in distribution of influenza virus (sub)types helps to facilitate better understanding of seasonal epidemics and to inform targeted strategies in prevention and control of influenza virus transmission.
收起
摘要 :
Over recent years, swine respiratory disease has been the most serious problem on swine farms. Many respiratory diseases of swine are linked to both environmental factors and infectious agents, which interact to create the porcine...
展开
Over recent years, swine respiratory disease has been the most serious problem on swine farms. Many respiratory diseases of swine are linked to both environmental factors and infectious agents, which interact to create the porcine respiratory disease complex (PRDC). The influenza virus is a respiratory pathogen able to cause disease by itself; it is therefore of great importance in PRDC. Pigs can also be infected by several subtypes of the influenza A virus, of avian and human origin; however, the subtypes normally causing disease are H1N1 and H3N2 (Easterday and Van Reeth, 1999). In Table I the main steps of evolution of swine influenza (SI) are shown. Swine influenza is extremely diffuse around the world. Some data (Janke, 1998) demonstrate the presence of virus in over 25% of cases of acute respiratory disease in the USA, and others in Europe suggest the presence of antibodies to influenza virus in the whole swine population (Van Reeth et al., 2000).
收起
摘要 :
Objective: Influenza infection is a viral respiratory disease that is common all over the world and in our country and has significant mortality and morbidity. It affects all age groups and the rate of infection is quite high in c...
展开
Objective: Influenza infection is a viral respiratory disease that is common all over the world and in our country and has significant mortality and morbidity. It affects all age groups and the rate of infection is quite high in children. The distribution of subtypes may vary over the years and regions. In this study, strain distribution and clinical features according to strain of influenza cases hospitalized in our center during the 2015-2016 season were investigated. Methods: Between October 1, 2015 and April 1, 2016, patients with symptoms and signs meeting the diagnostic criteria of influenza-like illness (GBD) in Gazi University Faculty of Medicine, Department of Pediatrics were included in the study. Demographic data of the patients, symptoms and findings in physical examination, laboratory test results, medications, and complications during follow-up were recorded. The relationship of these data with influenza virus types and subtypes isolated from the respiratory tract was examined. Results: In our study, 212 patients with positive ILI symptoms were screened, and a total of 30 (14.1%) were positive for influenza virus. The median age of the patients was 30 months (1-180 months). Seventeen (56.6%) of the patients were female and 13 (43.4%) were male. Influenza A was positive in 24 (80%) of the patients, influenza B in 3 (10%) and more than one virus in 3 (10%). Among patients who were positive for influenza A virus, 13 had H1N1 subtype and 9 had H3N2 subtype. Complications were observed in 21 (70%) of the patients, and the most common complication was pneumonia (53.3%). Of the patients who developed complications, 47.7% were H1N1, 38.1% were H3N2 positive (p=0.004) Conclusion: Influenza always remains important in children, and multicenter epidemiological studies with continuity always maintain their importance due to dynamic epidemiological features. The number of studies comparing the disease characteristics according to influenza types and strains in children is few. This study is important because it presents clinical findings by comparing strains.
收起
原文获取