oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
The biennial cycle of respiratory syncytial virus outbreaks in Croatia
Gordana Mlinaric-Galinovic, Robert C Welliver, Tatjana Vilibic-Cavlek, Suncanica Ljubin-Sternak, Vladimir Drazenovic, Ivana Galinovic, Vlatka Tomic
Virology Journal , 2008, DOI: 10.1186/1743-422x-5-18
Abstract: In the Zagreb area, RSV outbreaks were proven to vary in a two-year cycle, which was repeated every 23–25 months. This biennial cycle comprised one larger and one smaller season. Climate factors correlated significantly with the number of RSV cases identified only in the large seasons, which suggests that the biennial cycle is likely to continue regardless of meteorological conditions. Knowledge of this biennial pattern should be useful in predicting the onset of RSV outbreaks in Croatia, and would facilitate planning for the prevention and control of RSV infections in the region.Respiratory syncytial virus (RSV) frequently causes acute respiratory tract infections (ARTI) among children. In investigations of the epidemiology of viral respiratory infections in Croatian children over four seasons in the 1980s, RSV was determined to be the agent of 20–34% of inpatient ARTI [1,2]. Our study of RSV-genotypes circulating in Zagreb and Vienna from 1987–1994 showed that they were similar to the pattern of expression of these genotypes globally [3].In temperate climates, RSV infections occur in winter and in the early spring [1,4]. The role of climate in causing this epidemic pattern has not been evaluated in the area including and surrounding Croatia. We set out to examine the timing of RSV epidemics and the relationship of various meteorological factors and the number of RSV infections in children over 11 consecutive years in Zagreb County. The county covers an area of 3,719.355 km2, and includes a population of 1,088,841 inhabitants in the northwest part of Croatia.This study was conducted as a part of the scientific project #0005002 approved by the Ethic Committee of Croatian National Institute of Public Health (CNIPH). The study period lasted from 1 July 1994 to 1 July 2005. This retrospective cohort study comprised 3,435 inpatients with an ARTI from Zagreb County who were 0 to 10 years of age (median = 7.5 months).Samples of nasopharyngeal secretions collected from eac
Defining the timing of respiratory syncytial virus (RSV) outbreaks: an epidemiological study
Elena Terletskaia-Ladwig, Gisela Enders, Gunnar Schalasta, Martin Enders
BMC Infectious Diseases , 2005, DOI: 10.1186/1471-2334-5-20
Abstract: Epidemiological analysis of the RSV situation in southern Germany from 1996 to 2004 and comparison of results with literature was made. The respiratory tract specimens were sent in for the detection of RSV mainly by paediatric clinics. Detection of RSV was carried out mainly by real-time RT-PCR or by ELISA "Pathfinder". RSV outbreaks were depicted as an absolute number and as a percentage of RSV diagnoses in a month. Onsets, offsets, peaks, duration and severity of RSV seasons were defined and analysed.An early season with strong RSV activity (early-high phase) was followed by a weaker late season (late-low phase) in a regular biennial rhythm. However, onsets, offsets and durations of outbreaks varied significantly from year to year. RSV epidemics in southern Germany were found to oscillate in an antiphase with RSV epidemics in Finland and Sweden.The long-term regular biennial rhythm allows predicting whether the next outbreak will be late or early and whether RSV activity will be strong or weak. Not foreseeable, however, is the precise time of increase and decrease of RSV activity. Moreover, the regular seasonal pattern may be disrupted by irregular outbreaks. Thus, activity of RSV has to be monitored every year to define the period with high risk of infection.Respiratory syncytial virus (RSV) is the most common cause of viral bronchiolitis and pneumonia in infants and children under two years of age. Premature infants, children with chronic lung diseases (e.g. bronchopulmonary dysplasia), children with congenital heart disease and immunodeficiency patients have high risk of a severe disease.There are no efficient active vaccines and causal therapy, therefore prophylactic measures are especially important. Prospective surveillance of RSV infection and consequent implication of hygienic measures for preventing transmission and spread of RSV contribute effectively to reduction of hospital-acquired infections. Moreover, a humanized monoclonal antibody palivizumab (Syn
Dry weather induces outbreaks of human West Nile virus infections
Guiming Wang, Richard B Minnis, Jerrold L Belant, Charles L Wax
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-38
Abstract: We analyzed data on the human WNV incidences in the 82 counties of Mississippi in 2002, using standard morbidity ratio (SMR) and Bayesian hierarchical models, to determine relationships between precipitation and human WNV risks. We also entertained spatial autocorrelations of human WNV risks with conditional autocorrelative (CAR) models, implemented in WinBUGS 1.4.3.We observed an inverse relationship between county-level human WNV incidence risk and total annual rainfall during the previous year. Parameters representing spatial heterogeneity in the risk of human exposure to WNV improved model fit. Annual precipitation of the previous year was a predictor of spatial variation of WNV risk.Our results have broad implications for risk assessment of WNV and forecasting WNV outbreaks. Assessing risk of vector-born infectious diseases will require understanding of complex ecological relationships. Based on the climatologically characteristic drought occurrence in the past and on climate model predictions for climate change and potentially greater drought occurrence in the future, we suggest that the frequency and relative risk of WNV outbreaks could increase.Initially detected in Uganda in 1937, West Nile virus (WNV) spread across Africa to the Middle East, West Asia, and eastern Europe [1,2]. The first occurrence of WNV in the Western Hemisphere was in the New York City area during 1999, where 59 patients were hospitalized with WNV infection during August and September [2]. West Nile virus spread rapidly across North America and by 2002, was reported in 40 states and the District of Columbia of the United States (US) with 4,156 human and 14,539 equine cases of infection [3]. West Nile virus infection can cause neuroinvasive diseases (e.g., encephalitis) and even human fatalities [3]. Additionally, an epidemic of WNV can impose enormous impacts on local economies. For instance, the estimated short-term economic cost incurred from the 2002 WNV epidemic in Louisiana was $20
Preface An introduction to the 1st European Space Weather Week (ESWW)
N. Srivastava
Annales Geophysicae (ANGEO) , 2005,
Abstract: A logistic regression model is implemented for predicting the occurrence of intense/super-intense geomagnetic storms. A binary dependent variable, indicating the occurrence of intense/super-intense geomagnetic storms, is regressed against a series of independent model variables that define a number of solar and interplanetary properties of geo-effective CMEs. The model parameters (regression coefficients) are estimated from a training data set which was extracted from a dataset of 64 geo-effective CMEs observed during 1996-2002. The trained model is validated by predicting the occurrence of geomagnetic storms from a validation dataset, also extracted from the same data set of 64 geo-effective CMEs, recorded during 1996-2002, but not used for training the model. The model predicts 78% of the geomagnetic storms from the validation data set. In addition, the model predicts 85% of the geomagnetic storms from the training data set. These results indicate that logistic regression models can be effectively used for predicting the occurrence of intense geomagnetic storms from a set of solar and interplanetary factors.
Influence of extreme weather and meteorological anomalies on outbreaks of influenza A (H1N1)
Hong Xiao,HuaiYu Tian,XiaoLing Lin,LiDong Gao,XiangYu Dai,XiXing Zhang,BiYun Chen,Jian Zhao,JingZhe Xu
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5571-7
Abstract: Biological experiments and epidemiological evidence indicate that variations in environment have important effect on the occurrence and transmission of epidemic influenza. It is therefore important to understand the characteristic patterns of transmission for prevention of disease and reduction of disease burden. Based on case records, we analyzed the environmental characteristics including climate variables in Changsha, and then constructed a meteorological anomaly susceptive-infective-removal (SIR) model on the basis of the results of influenza A (H1N1) transmission. The results showed that the outbreak of influenza A (H1N1) in Changsha showed significant correlation with meteorological conditions; the spread of influenza was sensitive to meteorological anomalies, and that the outbreak of influenza A (H1N1) in Changsha was influenced by a combination of absolute humidity anomalous weather conditions, contact rates of the influenza patients and changes in population movements. These findings will provide helpful information regarding prevention strategies under different conditions, a fresh understanding of the emergence and re-emergence of influenza outbreaks, and a new perspective on the transmission dynamics of influenza.
Antigenic and Genetic Characterization of Twenty-six Strains of Human Respiratory Syncytial Virus (Subgroup A) Isolated During Three Consecutive Outbreaks in Havana City, Cuba
Valdivia, Angel;González, Grehete;Chacón, Danay;Savón, Clara;Otero, Anselmo;Váldes, Odalys;Cancio, Reynel;Oropesa, Suset;Melero, José A;García-Barreno, Blanca;Goyenechea, Angel;
Memórias do Instituto Oswaldo Cruz , 1999, DOI: 10.1590/S0074-02761999000400007
Abstract: twenty-six human respiratory syncytial virus strains (subgroup a) isolated from three outbreaks in havana city during the period 1994/95, 1995/96 and 1996/97 were analyzed to determine their antigenic and genetic relationships. analyses were performed by monoclonal antibodies and restriction mapping (n gene) following amplification of the select region of the virus genome by polymerase chain reaction. all isolated strains were classified as subgroup a by monoclonal antibodies and they showed a restriction pattern np4 that belonged to subgroup a. thus the results obtained in this work, showed a close relation (100%) between antigenic and genetic characterization of the isolated strains in our laboratory. these methods permit the examination of large numbers of isolates by molecular techniques, simplifying the researchs into the molecular epidemiology of the virus.
Antigenic and Genetic Characterization of Twenty-six Strains of Human Respiratory Syncytial Virus (Subgroup A) Isolated During Three Consecutive Outbreaks in Havana City, Cuba  [cached]
Valdivia Angel,González Grehete,Chacón Danay,Savón Clara
Memórias do Instituto Oswaldo Cruz , 1999,
Abstract: Twenty-six human respiratory syncytial virus strains (subgroup A) isolated from three outbreaks in Havana City during the period 1994/95, 1995/96 and 1996/97 were analyzed to determine their antigenic and genetic relationships. Analyses were performed by monoclonal antibodies and restriction mapping (N gene) following amplification of the select region of the virus genome by polymerase chain reaction. All isolated strains were classified as subgroup A by monoclonal antibodies and they showed a restriction pattern NP4 that belonged to subgroup A. Thus the results obtained in this work, showed a close relation (100%) between antigenic and genetic characterization of the isolated strains in our laboratory. These methods permit the examination of large numbers of isolates by molecular techniques, simplifying the researchs into the molecular epidemiology of the virus.
Temperature Drops and the Onset of Severe Avian Influenza A H5N1 Virus Outbreaks  [PDF]
Chung-Ming Liu, Shu-Hua Lin, Ying-Chen Chen, Katherine Chun-Min Lin, Tsung-Shu Joseph Wu, Chwan-Chuen King
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000191
Abstract: Global influenza surveillance is one of the most effective strategies for containing outbreaks and preparing for a possible pandemic influenza. Since the end of 2003, highly pathogenic avian influenza viruses (HPAI) H5N1 have caused many outbreaks in poultries and wild birds from East Asia and have spread to at least 48 countries. For such a fast and wide-spreading virulent pathogen, prediction based on changes of micro- and macro-environment has rarely been evaluated. In this study, we are developing a new climatic approach by investigating the conditions that occurred before the H5N1 avian influenza outbreaks for early predicting future HPAI outbreaks and preventing pandemic disasters. The results show a temperature drop shortly before these outbreaks in birds in each of the Eurasian regions stricken in 2005 and 2006. Dust storms, like those that struck near China's Lake Qinghai around May 4, 2005, exacerbated the spread of this HPAI H5N1 virus, causing the deaths of a record number of wild birds and triggering the subsequent spread of H5N1. Weather monitoring could play an important role in the early warning of outbreaks of this potentially dangerous virus.
Limits to Forecasting Precision for Outbreaks of Directly Transmitted Diseases  [PDF]
John M Drake
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030003
Abstract: Background Early warning systems for outbreaks of infectious diseases are an important application of the ecological theory of epidemics. A key variable predicted by early warning systems is the final outbreak size. However, for directly transmitted diseases, the stochastic contact process by which outbreaks develop entails fundamental limits to the precision with which the final size can be predicted. Methods and Findings I studied how the expected final outbreak size and the coefficient of variation in the final size of outbreaks scale with control effectiveness and the rate of infectious contacts in the simple stochastic epidemic. As examples, I parameterized this model with data on observed ranges for the basic reproductive ratio (R0) of nine directly transmitted diseases. I also present results from a new model, the simple stochastic epidemic with delayed-onset intervention, in which an initially supercritical outbreak (R0 > 1) is brought under control after a delay. Conclusion The coefficient of variation of final outbreak size in the subcritical case (R0 < 1) will be greater than one for any outbreak in which the removal rate is less than approximately 2.41 times the rate of infectious contacts, implying that for many transmissible diseases precise forecasts of the final outbreak size will be unattainable. In the delayed-onset model, the coefficient of variation (CV) was generally large (CV > 1) and increased with the delay between the start of the epidemic and intervention, and with the average outbreak size. These results suggest that early warning systems for infectious diseases should not focus exclusively on predicting outbreak size but should consider other characteristics of outbreaks such as the timing of disease emergence.
Epidemiological assessment of Respiratory Syncytial Virus infection in hospitalized infants, during the season 2005–2006 in Palermo, Italy
Paola Di Carlo, Amelia Romano, Ludovico Salsa, Alessandra Gueli, Antonella Poma, Fortunata Fucà, Piera Dones, Mirella Collura, Diego Pampinella, Delia Motisi, Giovanni Corsello
Italian Journal of Pediatrics , 2009, DOI: 10.1186/1824-7288-35-11
Abstract: We evaluate the epidemiological and clinical patterns of RSV infection in infants hospitalized for LRTI in in Palermo, South Italy, Sicily.We collected the demographic details of infants hospitalized to G. Di Cristina Children's Hospital in Palermo for LRTI between November 2005 and May 2006. We also included all cases occurred in newborns hospitalized in the Neonatal Intensive Care Unit (NICU) Of Palermo.During the studied period, 335/705 hospitalized infants for LRTI were enrolled in the study. The trend of hospitalization started in late winter and lasting until May 2006 with an epidemic peak in spring. 178/335 infants tested for viral infection showed RSV disease. Three cases occurred in preterm newborns hospitalized from birth in NICU. The likelihood to be RSV+, rather than RSV negative (RSV-) was higher for infants < 6 months and lower for infants with history of breast feeding (P < 0.05). RSV infection was associated with a higher likelihood to be admitted to intensive care unit and to a longer hospitalization and oxygen therapy.The study shows that, in Sicily, RSV is an important cause of LRTI in infants. The seasonal distribution shows that both LRTI and RSV infections peak in late spring, in contrast to Northern Italy. Our data could help to define the regional appropriate start of prophylactic interventions.Almost all children are infected by Respiratory Syncytial Virus (RSV) at least once by 2 years of age, and approximately 1–2% of infants will require hospitalization for RSV-associated Lower Respiratory Tract Infections (LRTI) [1-3].Infection rates vary from 50–70% during the first year of life, to 100% during the second-third year of age. Immunity, however, is not complete, and reinfection is common [1-4].Evidence of RSV infection has been found in every geographic area studied. In countries with a temperate climate, outbreaks generally occur during the autumn and last until spring, with the number of infections peaking in January-March. In tropical a
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.