WorldWideScience

Sample records for geo-parsing online epidemic

  1. Behavioral responses to epidemics in an online experiment: using virtual diseases to study human behavior.

    Science.gov (United States)

    Chen, Frederick; Griffith, Amanda; Cottrell, Allin; Wong, Yue-Ling

    2013-01-01

    We report the results of a study we conducted using a simple multiplayer online game that simulates the spread of an infectious disease through a population composed of the players. We use our virtual epidemics game to examine how people respond to epidemics. The analysis shows that people's behavior is responsive to the cost of self-protection, the reported prevalence of disease, and their experiences earlier in the epidemic. Specifically, decreasing the cost of self-protection increases the rate of safe behavior. Higher reported prevalence also raises the likelihood that individuals would engage in self-protection, where the magnitude of this effect depends on how much time has elapsed in the epidemic. Individuals' experiences in terms of how often an infection was acquired when they did not engage in self-protection are another factor that determines whether they will invest in preventive measures later on. All else being equal, individuals who were infected at a higher rate are more likely to engage in self-protective behavior compared to those with a lower rate of infection. Lastly, fixing everything else, people's willingness to engage in safe behavior waxes or wanes over time, depending on the severity of an epidemic: when prevalence is high, people are more likely to adopt self-protective measures as time goes by; when prevalence is low, a 'self-protection fatigue' effect sets in whereby individuals are less willing to engage in safe behavior over time.

  2. Blood libel rebooted: traditional scapegoats, online media, and the H1N1 epidemic.

    Science.gov (United States)

    Atlani-Duault, L; Mercier, A; Rousseau, C; Guyot, P; Moatti, J P

    2015-03-01

    This study of comments posted on major French print and TV media websites during the H1N1 epidemic illustrates the relationship between the traditional media and social media in responding to an emerging disease. A disturbing "geography of blame" was observed suggesting the metamorphosis of the folk-devil phenomenon to the Internet. We discovered a subterranean discourse about the putative origins and "objectives" of the H1N1 virus, which was absent from the discussions in mainstream television channels and large-circulation print media. These online rumours attributed hidden motives to governments, pharmaceutical companies, and figures of Otherness that were scapegoated in the social history of previous European epidemics, notably Freemasons and Jews.

  3. An online spatio-temporal prediction model for dengue fever epidemic in Kaohsiung,Taiwan

    Science.gov (United States)

    Cheng, Ming-Hung; Yu, Hwa-Lung; Angulo, Jose; Christakos, George

    2013-04-01

    Dengue Fever (DF) is one of the most serious vector-borne infectious diseases in tropical and subtropical areas. DF epidemics occur in Taiwan annually especially during summer and fall seasons. Kaohsiung city has been one of the major DF hotspots in decades. The emergence and re-emergence of the DF epidemic is complex and can be influenced by various factors including space-time dynamics of human and vector populations and virus serotypes as well as the associated uncertainties. This study integrates a stochastic space-time "Susceptible-Infected-Recovered" model under Bayesian maximum entropy framework (BME-SIR) to perform real-time prediction of disease diffusion across space-time. The proposed model is applied for spatiotemporal prediction of the DF epidemic at Kaohsiung city during 2002 when the historical series of high DF cases was recorded. The online prediction by BME-SIR model updates the parameters of SIR model and infected cases across districts over time. Results show that the proposed model is rigorous to initial guess of unknown model parameters, i.e. transmission and recovery rates, which can depend upon the virus serotypes and various human interventions. This study shows that spatial diffusion can be well characterized by BME-SIR model, especially at the district surrounding the disease outbreak locations. The prediction performance at DF hotspots, i.e. Cianjhen and Sanmin, can be degraded due to the implementation of various disease control strategies during the epidemics. The proposed online disease prediction BME-SIR model can provide the governmental agency with a valuable reference to timely identify, control, and efficiently prevent DF spread across space-time.

  4. SimNest: Social Media Nested Epidemic Simulation via Online Semi-supervised Deep Learning.

    Science.gov (United States)

    Zhao, Liang; Chen, Jiangzhuo; Chen, Feng; Wang, Wei; Lu, Chang-Tien; Ramakrishnan, Naren

    2015-11-01

    Infectious disease epidemics such as influenza and Ebola pose a serious threat to global public health. It is crucial to characterize the disease and the evolution of the ongoing epidemic efficiently and accurately. Computational epidemiology can model the disease progress and underlying contact network, but suffers from the lack of real-time and fine-grained surveillance data. Social media, on the other hand, provides timely and detailed disease surveillance, but is insensible to the underlying contact network and disease model. This paper proposes a novel semi-supervised deep learning framework that integrates the strengths of computational epidemiology and social media mining techniques. Specifically, this framework learns the social media users' health states and intervention actions in real time, which are regularized by the underlying disease model and contact network. Conversely, the learned knowledge from social media can be fed into computational epidemic model to improve the efficiency and accuracy of disease diffusion modeling. We propose an online optimization algorithm to substantialize the above interactive learning process iteratively to achieve a consistent stage of the integration. The extensive experimental results demonstrated that our approach can effectively characterize the spatio-temporal disease diffusion, outperforming competing methods by a substantial margin on multiple metrics.

  5. Analysis of Infectious-Recovery Epidemic Models for Membership Dynamics of Online Social Networks

    CERN Document Server

    Cooney, Daniel; Bar-Yam, Yaneer

    2016-01-01

    The recent rapid growth of social media and online social networks (OSNs) has raised interesting questions about the spread of ideas and fads within our society. In the past year, several papers have drawn analogies between the rise and fall in popularity of OSNs and mathematical models used to study infectious disease. One such model, the irSIR model, made use of the idea of "infectious recovery" to outperform the traditional SIR model in replicating the rise and fall of MySpace and to predict a rapid drop in the popularity of Facebook. Here we explore the irSIR model and two of its logical extensions and we mathematically characterize the initial and long-run behavior of these dynamical systems. In particular, while the original irSIR model always predicts extinction of a social epidemic, we construct an extension of the model that matches the exponential growth phase of the irSIR model while allowing for the possibility of an arbitrary proportion of infections in the long run.

  6. An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa

    Science.gov (United States)

    Grover-Kopec, Emily; Kawano, Mika; Klaver, Robert W.; Blumenthal, Benno; Ceccato, Pietro; Connor, Stephen J.

    2005-01-01

    Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response.

  7. An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa

    Directory of Open Access Journals (Sweden)

    Ceccato Pietro

    2005-01-01

    Full Text Available Abstract Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response. Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization. The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to

  8. The development of a massive open online course during the 2014-15 Ebola virus disease epidemic.

    Science.gov (United States)

    Evans, Dabney P; Luffy, Samantha M; Parisi, Stephanie; Del Rio, Carlos

    2017-08-12

    Timely training was urgently needed at the onset of the 2014 Ebola virus disease epidemic. Massive open online courses (MOOCs) have grown in popularity, though little is known about their utility in time-sensitive situations, including infectious disease outbreaks. We created the first English language massive open online course on Ebola virus disease. Designed by a team representing various units of Emory University and six partner institutions, the six module course was aimed at a global general audience but also relevant for health care professionals. Over 7,000 learners from 170 countries participated in the initial course offering. More than a third of learners were from emerging economies, including seven percent from Africa, and another 13% from countries outside the United States who received individuals requiring treatment for Ebola virus disease. Creating and producing the first English language MOOC on EVD in a short time period required effective collaboration and strong coordination between subject matter and course development experts from Emory. Through these collaborative efforts, the development team was able to provide urgently needed training and educational materials while the epidemic of EVD continued to radiate through West Africa. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Blood libel rebooted : traditional scapegoats, online media, and the H1N1 epidemic

    OpenAIRE

    Atlani Duault, Laëtitia (ed.); Mercier, A.; Rousseau, C; Guyot, P; Moatti, Jean-Paul

    2015-01-01

    This study of comments posted on major French print and TV media websites during the H1N1 epidemic illustrates the relationship between the traditional media and social media in responding to an emerging disease. A disturbing "geography of blame" was observed suggesting the metamorphosis of the folk-devil phenomenon to the Internet. We discovered a subterranean discourse about the putative origins and "objectives" of the H1N1 virus, which was absent from the discussions in mainstream televisi...

  10. Virtual plagues and real-world pandemics: reflecting on the potential for online computer role-playing games to inform real world epidemic research.

    Science.gov (United States)

    Oultram, Stuart

    2013-12-01

    In the wake of the Corrupted Blood incident, which afflicted the massively multiplayer online computer role-playing game World of Warcraft in 2005, it has been suggested that both, the incident itself and massively multiplayer online computer role-playing games in general, can be utilised to inform and assist real-world epidemic and public health research. In this paper, I engage critically with these claims.

  11. Can Health 2.0 Address Critical Healthcare Challenges? Insights from the Case of How Online Social Networks Can Assist in Combatting the Obesity Epidemic

    Directory of Open Access Journals (Sweden)

    Janine Hacker

    2017-03-01

    Full Text Available One of the serious concerns in healthcare in this 21st century is obesity. While the causes of obesity are multifaceted, social networks have been identified as one of the most important dimensions of people's social environment that may influence the adoption of many behaviours, including health-promoting behaviours. In this article, we examine the possibility of harnessing the appeal of online social networks to address the obesity epidemic currently plaguing society. Specifically, a design science research methodology is adopted to design, implement and test the Health 2.0 application called “Calorie Cruncher”. The application is designed specifically to explore the influence of online social networks on individual’s health-related behaviour. In this regard, pilot data collected based on qualitative interviews indicate that online social networks may influence health-related behaviours in several ways. Firstly, they can influence people’s norms and value system that have an impact on their health-related behaviours. Secondly, social control and pressure of social connections may also shape health-related behaviours, and operate implicitly when people make food selection decisions. Thirdly, social relationships may provide emotional support. Our study has implications for research and practice. From a theoretical perspective, the article inductively identifies three factors that influence specific types of health outcomes in the context of obesity. From a practical perspective, the study underscores the benefits of adopting a design science methodology to design and implement a technology solution for a healthcare issue as well as the key role for online social media to assist with health and wellness management and maintenance.

  12. Epidemics and rumours in complex networks

    CERN Document Server

    Draief, Moez

    2009-01-01

    Information propagation through peer-to-peer systems, online social systems, wireless mobile ad hoc networks and other modern structures can be modelled as an epidemic on a network of contacts. Understanding how epidemic processes interact with network topology allows us to predict ultimate course, understand phase transitions and develop strategies to control and optimise dissemination. This book is a concise introduction for applied mathematicians and computer scientists to basic models, analytical tools and mathematical and algorithmic results. Mathematical tools introduced include coupling

  13. Epidemic spreading on weighted complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ye [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Liu, Chuang, E-mail: liuchuang@hznu.edu.cn [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Chu-Xu [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Zi-Ke, E-mail: zhangzike@gmail.com [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China)

    2014-01-31

    Nowadays, the emergence of online services provides various multi-relation information to support the comprehensive understanding of the epidemic spreading process. In this Letter, we consider the edge weights to represent such multi-role relations. In addition, we perform detailed analysis of two representative metrics, outbreak threshold and epidemic prevalence, on SIS and SIR models. Both theoretical and simulation results find good agreements with each other. Furthermore, experiments show that, on fully mixed networks, the weight distribution on edges would not affect the epidemic results once the average weight of whole network is fixed. This work may shed some light on the in-depth understanding of epidemic spreading on multi-relation and weighted networks.

  14. Addressing the "Epidemic" of Overweight Children by Using the Internet

    Science.gov (United States)

    Coleman, Mick; Wallinga, Charlotte; Bales, Diane

    2009-01-01

    The Internet can be of great assistance to early childhood teachers in planning educational activities for the classroom and with families. This article explores how early childhood teachers can use resources online to address what has been called an "epidemic" of overweight children. Guidelines for using online resources are presented. (Contains…

  15. Modeling Epidemic Network Failures

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Fagertun, Anna Manolova

    2013-01-01

    This paper presents the implementation of a failure propagation model for transport networks when multiple failures occur resulting in an epidemic. We model the Susceptible Infected Disabled (SID) epidemic model and validate it by comparing it to analytical solutions. Furthermore, we evaluate...... the SID model’s behavior and impact on the network performance, as well as the severity of the infection spreading. The simulations are carried out in OPNET Modeler. The model provides an important input to epidemic connection recovery mechanisms, and can due to its flexibility and versatility be used...... to evaluate multiple epidemic scenarios in various network types....

  16. Modeling Epidemic Network Failures

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Fagertun, Anna Manolova

    2013-01-01

    the SID model’s behavior and impact on the network performance, as well as the severity of the infection spreading. The simulations are carried out in OPNET Modeler. The model provides an important input to epidemic connection recovery mechanisms, and can due to its flexibility and versatility be used......This paper presents the implementation of a failure propagation model for transport networks when multiple failures occur resulting in an epidemic. We model the Susceptible Infected Disabled (SID) epidemic model and validate it by comparing it to analytical solutions. Furthermore, we evaluate...

  17. Dynamics of beneficial epidemics

    CERN Document Server

    Berdahl, Andrew; De Bacco, Caterina; Dumas, Marion; Ferdinand, Vanessa; Grochow, Joshua A; Hébert-Dufresne, Laurent; Kallus, Yoav; Kempes, Christopher P; Kolchinsky, Artemy; Larremore, Daniel B; Libby, Eric; Power, Eleanor A; Stern, Caitlin A; Tracey, Brendan

    2016-01-01

    Pathogens can spread epidemically through populations. Beneficial contagions, such as viruses that enhance host survival or technological innovations that improve quality of life, also have the potential to spread epidemically. How do the dynamics of beneficial biological and social epidemics differ from those of detrimental epidemics? We investigate this question using three theoretical approaches as well as an empirical analysis of concept propagation. First, in evolutionary models, we show that a beneficial horizontally-transmissible element, such as viral DNA, spreads super-exponentially through a population, substantially more quickly than a beneficial mutation. Second, in an epidemiological social network approach, we show that infections that cause increased connectivity lead to faster-than-exponential fixation in the population. Third, in a sociological model with strategic rewiring, we find that preferences for increased global infection accelerate spread and produce super-exponential fixation rates,...

  18. Modularity promotes epidemic recurrence

    CERN Document Server

    Jesan, T; Sinha, Sitabhra

    2016-01-01

    The long-term evolution of epidemic processes depends crucially on the structure of contact networks. As empirical evidence indicates that human populations exhibit strong community organization, we investigate here how such mesoscopic configurations affect the likelihood of epidemic recurrence. Through numerical simulations on real social networks and theoretical arguments using spectral methods, we demonstrate that highly contagious diseases that would have otherwise died out rapidly can persist indefinitely for an optimal range of modularity in contact networks.

  19. The Opioid Epidemic: Crisis and Solutions.

    Science.gov (United States)

    Skolnick, Phil

    2017-10-02

    The widespread abuse of prescription opioids and a dramatic increase in the availability of illicit opioids have created what is commonly referred to as the opioid epidemic. The magnitude of this epidemic is startling: About 4% of the adult US population misuses prescription opioids, and in 2015, more than 33,000 deaths were attributable to overdose with licit and illicit opioids. Increasing the availability of medication-assisted treatments (such as buprenorphine and naltrexone), the use of abuse-deterrent formulations, and the adoption of US Centers for Disease Control and Prevention prescribing guidelines all constitute short-term approaches to quell this epidemic. However, with more than 125 million Americans suffering from either acute or chronic pain, the development of effective alternatives to opioids, enabled at least in part by a fuller understanding of the neurobiological bases of pain, offers the best long-term solution for controlling and ultimately eradicating this epidemic. Expected final online publication date for the Annual Review of Pharmacology and Toxicology Volume 58 is January 6, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  20. Configuring the autism epidemic

    DEFF Research Database (Denmark)

    Christensen, Fie Lund Lindegaard; Seeberg, Jens

    2017-01-01

    Autism has been described as an epidemic, but this claim is contested and may point to an awareness epidemic, i.e. changes in the definition of what autism is and more attention being invested in diagnosis leading to a rise in registered cases. The sex ratio of children diagnosed with autism...... is skewed in favour of boys, and girls with autism tend to be diagnosed much later than boys. Building and further developing the notion of ‘configuration’ of epidemics, this article explores the configuration of autism in Denmark, with a particular focus on the health system and social support to families...... with children diagnosed with autism, seen from a parental perspective. The article points to diagnostic dynamics that contribute to explaining why girls with autism are not diagnosed as easily as boys. We unfold these dynamics through the analysis of a case of a Danish family with autism....

  1. The Epidemics of Corruption

    CERN Document Server

    Blanchard, P; Krüger, T; Martin, P; Blanchard, Ph.

    2005-01-01

    We study corruption as a generalized epidemic process on the graph of social relationships. The main difference to classical epidemic processes is the strong nonlinear dependence of the transmission probability on the local density of corruption and the mean field influence of the overall corruption in the society. Network clustering and the degree-degree correlation play an essential role in corruption dynamics. We discuss phase transitions, the influence of the graph structure and the implications for epidemic control. Structural and dynamical arguments are given why strongly hierarchically organized societies like systems with dictatorial tendency are more vulnerable to corruption than democracies. A similar type of modelling can be applied to other social contagion spreading processes like opinion formation, doping usage, social disorders or innovation dynamics.

  2. Discrete epidemic models.

    Science.gov (United States)

    Brauer, Fred; Feng, Zhilan; Castillo-Chavez, Carlos

    2010-01-01

    The mathematical theory of single outbreak epidemic models really began with the work of Kermack and Mackendrick about decades ago. This gave a simple answer to the long-standing question of why epidemics woould appear suddenly and then disappear just as suddenly without having infected an entire population. Therefore it seemed natural to expect that theoreticians would immediately proceed to expand this mathematical framework both because the need to handle recurrent single infectious disease outbreaks has always been a priority for public health officials and because theoreticians often try to push the limits of exiting theories. However, the expansion of the theory via the inclusion of refined epidemiological classifications or through the incorporation of categories that are essential for the evaluation of intervention strategies, in the context of ongoing epidemic outbreaks, did not materialize. It was the global threat posed by SARS in that caused theoreticians to expand the Kermack-McKendrick single-outbreak framework. Most recently, efforts to connect theoretical work to data have exploded as attempts to deal with the threat of emergent and re-emergent diseases including the most recent H1N1 influenza pandemic, have marched to the forefront of our global priorities. Since data are collected and/or reported over discrete units of time, developing single outbreak models that fit collected data naturally is relevant. In this note, we introduce a discrete-epidemic framework and highlight, through our analyses, the similarities between single-outbreak comparable classical continuous-time epidemic models and the discrete-time models introduced in this note. The emphasis is on comparisons driven by expressions for the final epidemic size.

  3. The Obesity Epidemic

    Centers for Disease Control (CDC) Podcasts

    2011-07-18

    Learn about obesity and the community initiatives taking place to prevent and reduce this epidemic.  Created: 7/18/2011 by National Center for Chronic Disease Prevention and Health Promotion, Division of Nutrition, Physical Activity and Obesity.   Date Released: 7/18/2011.

  4. Temporal Dynamics of Connectivity and Epidemic Properties of Growing Networks

    CERN Document Server

    Fotouhi, Babak

    2015-01-01

    Traditional mathematical models of epidemic disease had for decades conventionally considered static structure for contacts. Recently, an upsurge of theoretical inquiry has strived towards rendering the models more realistic by incorporating the temporal aspects of networks of contacts, societal and online, that are of interest in the study of epidemics (and other similar diffusion processes). However, temporal dynamics have predominantly focused on link fluctuations and nodal activities, and less attention has been paid to the growth of the underlying network. Many real networks grow: online networks are evidently in constant growth, and societal networks can grow due to migration flux and reproduction. The effect of network growth on the epidemic properties of networks is hitherto unknown---mainly due to the predominant focus of the network growth literature on the so-called steady-state. This paper takes a step towards alleviating this gap. We analytically study the degree dynamics of a given arbitrary net...

  5. Understanding Virtual Epidemics: Children's Folk Conceptions of a Computer Virus

    Science.gov (United States)

    Kafai, Yasmin B.

    2008-01-01

    Our work investigates the annual outbreak of Whypox, a virtual epidemic in Whyville.net, a virtual world with over 1.2 million registered players ages 8-16. We examined online and classroom participants' understanding of a computer virus using surveys and design activities. Our analyses reveal that students have a mostly naive understanding of a…

  6. Understanding Virtual Epidemics: Children's Folk Conceptions of a Computer Virus

    Science.gov (United States)

    Kafai, Yasmin B.

    2008-01-01

    Our work investigates the annual outbreak of Whypox, a virtual epidemic in Whyville.net, a virtual world with over 1.2 million registered players ages 8-16. We examined online and classroom participants' understanding of a computer virus using surveys and design activities. Our analyses reveal that students have a mostly naive understanding of a…

  7. Resilience of epidemics on networks

    CERN Document Server

    Lu, Dan; Zhang, Jiaquan; Wang, Huijuan; Li, Daqing

    2016-01-01

    Epidemic propagation on complex networks has been widely investigated, mostly with invariant parameters. However, the process of epidemic propagation is not always constant. Epidemics can be affected by various perturbations, and may bounce back to its original state, which is considered resilient. Here, we study the resilience of epidemics on networks, by introducing a different infection rate ${\\lambda_{2}}$ during SIS (susceptible-infected-susceptible) epidemic propagation to model perturbations (control state), whereas the infection rate is ${\\lambda_{1}}$ in the rest of time. Through simulations and theoretical analysis, we find that even for ${\\lambda_{2}<\\lambda_{c}}$, epidemics eventually could bounce back if control duration is below a threshold. This critical control time for epidemic resilience, i.e., ${cd_{max}}$ can be predicted by the diameter (${d}$) of the underlying network, with the quantitative relation ${cd_{max}\\sim d^{\\alpha}}$. Our findings can help to design a better mitigation stra...

  8. Proximity Networks and Epidemics

    CERN Document Server

    Toroczkai, Z

    2007-01-01

    Disease spread in most biological populations requires the proximity of agents. In populations where the individuals have spatial mobility, the contact graph is generated by the "collision dynamics" of the agents, and thus the evolution of epidemics couples directly to the spatial dynamics of the population. We first briefly review the properties and the methodology of an agent-based simulation (EPISIMS) to model disease spread in realistic urban dynamic contact networks. Using the data generated by this simulation, we introduce the notion of dynamic proximity networks which takes into account the relevant time scales for disease spread: contact duration, infectivity period and rate of contact creation. This approach promises to be a good candidate for a unified treatment of epidemic types that are driven by agent collision dynamics. In particular, using a simple model, we show that it can can account for the observed qualitative differences between the degree distributions of contact graphs of diseases with ...

  9. A break in the obesity epidemic?

    DEFF Research Database (Denmark)

    Visscher, T L S; Heitmann, B L; Rissanen, A

    2015-01-01

    Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look into the litera......, focusing on trends in waist circumference rather than BMI leads to a less optimistic conclusion: the public health problem of obesity is still increasing.International Journal of Obesity advance online publication, 22 July 2014; doi:10.1038/ijo.2014.98.......Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look...... into the literature presented in recent reviews to address the major potential biases and distortions, and to develop insights about how to interpret the presented suggestions for a potential break in the obesity epidemic. Decreasing participation rates, the use of reported rather than measured data and small sample...

  10. [Cholera++ epidemic in Kenya].

    Science.gov (United States)

    Paugam, H

    1999-03-01

    A cholera epidemic in 1997 followed on the heels of the 1992 epidemic that claimed thousands of victims in Kenya. This time, it emerged in the Migori district near the Tanzanian border, when a woman who had married in Tanzania brought her five-month-old baby to visit her parents. The infant, who contracted serious diarrhea and vomiting, died before the mother could reach a dispensary. During the funeral, a perfect opportunity for the disease to spread, those attending observed the traditional ritual of touching the corpse, and then ate and drank with the next of kin. Many developed symptoms of cholera, and several died in the next few days, even before first aid could be administered. At the Public Health Laboratory in Nairobi, analyses confirmed the presence of the Ogawa strain of Vibrio cholerae. Given the global reputation of Médecins Sans Frontières [Doctors Without Borders] in the field of cholera, the head of public health for Homa Bay District issued a call for help in August 1997, asking the team to provide preventive solutions and assess the gravity of the situation. Despite intense logistical, technical and health initiatives, the epidemic spread like wildfire. Five months after the initial outbreak, in February 1998, two Canadian nurses working for MSF in Homa Bay hurriedly surveyed the situation in Nyanza Province, which has a population of three million. The author accompanied one of these nurses, Joceline Roy, a Quebecer in her forties, on a tour that lasted more than 15 hours. Roy worked conscientiously, with great precision and energy. This narrative conveys much more than the fatigue and hazards of travel in the developing world; it tells the story of an important, but little publicized, aspect of nursing.

  11. Dynamic Forecasting of Zika Epidemics Using Google Trends

    Science.gov (United States)

    Jin, Yuan; Huang, Yong; Lin, Baihan; An, Xiaoping; Feng, Dan; Tong, Yigang

    2017-01-01

    We developed a dynamic forecasting model for Zika virus (ZIKV), based on real-time online search data from Google Trends (GTs). It was designed to provide Zika virus disease (ZVD) surveillance and detection for Health Departments, and predictive numbers of infection cases, which would allow them sufficient time to implement interventions. In this study, we found a strong correlation between Zika-related GTs and the cumulative numbers of reported cases (confirmed, suspected and total cases; p<0.001). Then, we used the correlation data from Zika-related online search in GTs and ZIKV epidemics between 12 February and 20 October 2016 to construct an autoregressive integrated moving average (ARIMA) model (0, 1, 3) for the dynamic estimation of ZIKV outbreaks. The forecasting results indicated that the predicted data by ARIMA model, which used the online search data as the external regressor to enhance the forecasting model and assist the historical epidemic data in improving the quality of the predictions, are quite similar to the actual data during ZIKV epidemic early November 2016. Integer-valued autoregression provides a useful base predictive model for ZVD cases. This is enhanced by the incorporation of GTs data, confirming the prognostic utility of search query based surveillance. This accessible and flexible dynamic forecast model could be used in the monitoring of ZVD to provide advanced warning of future ZIKV outbreaks. PMID:28060809

  12. Stochastic epidemic models: a survey

    CERN Document Server

    Britton, Tom

    2009-01-01

    This paper is a survey paper on stochastic epidemic models. A simple stochastic epidemic model is defined and exact and asymptotic model properties (relying on a large community) are presented. The purpose of modelling is illustrated by studying effects of vaccination and also in terms of inference procedures for important parameters, such as the basic reproduction number and the critical vaccination coverage. Several generalizations towards realism, e.g. multitype and household epidemic models, are also presented, as is a model for endemic diseases.

  13. Epidemic dynamics on complex networks

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tao; FU Zhongqian; WANG Binghong

    2006-01-01

    Recently, motivated by the pioneer work in revealing the small-world effect and scale-free property of various real-life networks, many scientists devote themselves to studying complex networks. One of the ultimate goals is to understand how the topological structures affect the dynamics upon networks. In this paper, we give a brief review on the studies of epidemic dynamics on complex networks, including the description of classical epidemic models, the epidemic spread on small-world and scale-free networks, and network immunization. Finally, perspectives and some interesting problems are proposed.

  14. Epidemic Diffusion on Complex Networks

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-Yan; LIU Zong-Hua

    2007-01-01

    Boyh diffusion and epidemic are well studied in the stochastic systems and complex networks,respetively.Here we combine these two fields and study epidemic diffusion in complex networks.Instead of studying the threshold of infection,which was focused on in previous works,we focus on the diffusion.behaviour.We find that the epidemic diffusion in a complex network is an anomalous superdiffusion with varyingg diffusion exponext γand that γ is influenced seriously by the network structure,such as the clustering coefficient and the degree distribution.Numerical simulations have confirmed the theoretical predictions.

  15. The new epidemic.

    Science.gov (United States)

    Allen, Jeanne V; Mellin, Grace C

    2014-03-01

    Editor's note: From its first issue in 1900 through to the present day, AJN has unparalleled archives detailing nurses' work and lives over the last century. These articles not only chronicle nursing's growth as a profession within the context of the events of the day, but they also reveal prevailing societal attitudes about women, health care, and human rights. Today's nursing school curricula rarely include nursing's history, but it's a history worth knowing. To this end, From the AJN Archives will be a frequent column, containing articles selected to fit today's topics and times.This month's article, from the November 1982 issue, is the first AJN article published on AIDS. It was early in the epidemic; only 608 cases of Kaposi's sarcoma and opportunistic infections had been reported to the Centers for Disease Control and Prevention-a mere trickle in the flood that was to come. Reading it now, aware of all we've learned since, we have a sense of how much we were fumbling around in the dark in those early days, searching for a cause and a cure, often going in wrong directions. The closest we had come to the true nature of the syndrome was an understanding that "life-style factors seem to be involved and the agent appears to be infectious." To read the complete article from our archives, go to http://bit.ly/1iswhZe.

  16. Human mobility and epidemic invasion

    Science.gov (United States)

    Colizza, Vittoria

    2010-03-01

    The current H1N1 influenza pandemic is just the latest example of how human mobility helps drive infectious diseases. Travel has grown explosively in the last decades, contributing to an emerging complex pattern of traffic flows that unfolds at different scales, shaping the spread of epidemics. Restrictions on people's mobility are thus investigated to design possible containment measures. By considering a theoretical framework in terms of reaction-diffusion processes, it is possible to study the invasion dynamics of epidemics in a metapopulation system with heterogeneous mobility patterns. The system is found to exhibit a global invasion threshold that sets the critical mobility rate below which the epidemic is contained. The results provide a general framework for the understanding of the numerical evidence from detailed data-driven simulations that show the limited benefit provided by travel flows reduction in slowing down or containing an emerging epidemic.

  17. Epidemic cholera spreads like wildfire

    Science.gov (United States)

    Roy, Manojit; Zinck, Richard D.; Bouma, Menno J.; Pascual, Mercedes

    2014-01-01

    Cholera is on the rise globally, especially epidemic cholera which is characterized by intermittent and unpredictable outbreaks that punctuate periods of regional disease fade-out. These epidemic dynamics remain however poorly understood. Here we examine records for epidemic cholera over both contemporary and historical timelines, from Africa (1990-2006) and former British India (1882-1939). We find that the frequency distribution of outbreak size is fat-tailed, scaling approximately as a power-law. This pattern which shows strong parallels with wildfires is incompatible with existing cholera models developed for endemic regions, as it implies a fundamental role for stochastic transmission and local depletion of susceptible hosts. Application of a recently developed forest-fire model indicates that epidemic cholera dynamics are located above a critical phase transition and propagate in similar ways to aggressive wildfires. These findings have implications for the effectiveness of control measures and the mechanisms that ultimately limit the size of outbreaks.

  18. [Epidemic parotiditis, a reportable disease].

    Science.gov (United States)

    Boverhoff, J C; Baart, J A

    2013-01-01

    Three consecutive patients with an acute swelling of one of the cheeks, were diagnosed with epidemic parotiditis. The first phase of the diagnostic procedure for an acute cheek swelling is to eliminate the possibility of odontogenic causes. When odontogenic problems have been excluded, non-dentition-related causes may be considered. An acute, progressive swelling in the preauricular area can often be attributed to an inflammation of the parotid gland, but epidemic parotiditis should also be considered. Epidemic parotiditis, or mumps, is caused by the mumps virus. Contamination occurs aerogenically. In the Netherlands, mumps vaccine is an ingredient of the governmental combined mump-measles-rubella inoculation programme. However, in recent years several small-scale parotiditis epidemics have broken out, predominantly among young, inoculated adults. Oropharyngeal mucus and blood samples are needed to diagnose the disease. Each case of the disease should be reported to the community healthcare service.

  19. Understanding the Opioid Overdose Epidemic

    Science.gov (United States)

    ... can happen when someone takes more than prescribed, combines opioids with depressants (such as Xanax ® ) or alcohol, ... suffering with chronic pain.” Read More "Understanding Opioids" Articles Understanding The Opioid Overdose Epidemic / Beyond Opioids: Mind ...

  20. Epidemic spreading in complex networks

    Institute of Scientific and Technical Information of China (English)

    Jie ZHOU; Zong-hua LIU

    2008-01-01

    The study of epidemic spreading in complex networks is currently a hot topic and a large body of results have been achieved.In this paper,we briefly review our contributions to this field,which includes the underlying mechanism of rumor propagation,the epidemic spreading in community networks,the influence of varying topology,and the influence of mobility of agents.Also,some future directions are pointed out.

  1. Epidemic Network Failures in Optical Transport Networks

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Katsikas, Dimitrios; Fagertun, Anna Manolova

    2013-01-01

    This paper presents a failure propagation model for transport networks which are affected by epidemic failures. The network is controlled using the GMPLS protocol suite. The Susceptible Infected Disabled (SID) epidemic model is investigated and new signaling functionality of GMPLS to support epid...... epidemic failure resolution is proposed. The results provide important input to service recovery mechanisms under epidemic failures....

  2. Temporal dynamics of connectivity and epidemic properties of growing networks

    Science.gov (United States)

    Fotouhi, Babak; Shirkoohi, Mehrdad Khani

    2016-01-01

    Traditional mathematical models of epidemic disease had for decades conventionally considered static structure for contacts. Recently, an upsurge of theoretical inquiry has strived towards rendering the models more realistic by incorporating the temporal aspects of networks of contacts, societal and online, that are of interest in the study of epidemics (and other similar diffusion processes). However, temporal dynamics have predominantly focused on link fluctuations and nodal activities, and less attention has been paid to the growth of the underlying network. Many real networks grow: Online networks are evidently in constant growth, and societal networks can grow due to migration flux and reproduction. The effect of network growth on the epidemic properties of networks is hitherto unknown, mainly due to the predominant focus of the network growth literature on the so-called steady state. This paper takes a step towards alleviating this gap. We analytically study the degree dynamics of a given arbitrary network that is subject to growth. We use the theoretical findings to predict the epidemic properties of the network as a function of time. We observe that the introduction of new individuals into the network can enhance or diminish its resilience against endemic outbreaks and investigate how this regime shift depends upon the connectivity of newcomers and on how they establish connections to existing nodes. Throughout, theoretical findings are corroborated with Monte Carlo simulations over synthetic and real networks. The results shed light on the effects of network growth on the future epidemic properties of networks and offers insights for devising a priori immunization strategies.

  3. Epidemic processes in complex networks

    Science.gov (United States)

    Pastor-Satorras, Romualdo; Castellano, Claudio; Van Mieghem, Piet; Vespignani, Alessandro

    2015-07-01

    In recent years the research community has accumulated overwhelming evidence for the emergence of complex and heterogeneous connectivity patterns in a wide range of biological and sociotechnical systems. The complex properties of real-world networks have a profound impact on the behavior of equilibrium and nonequilibrium phenomena occurring in various systems, and the study of epidemic spreading is central to our understanding of the unfolding of dynamical processes in complex networks. The theoretical analysis of epidemic spreading in heterogeneous networks requires the development of novel analytical frameworks, and it has produced results of conceptual and practical relevance. A coherent and comprehensive review of the vast research activity concerning epidemic processes is presented, detailing the successful theoretical approaches as well as making their limits and assumptions clear. Physicists, mathematicians, epidemiologists, computer, and social scientists share a common interest in studying epidemic spreading and rely on similar models for the description of the diffusion of pathogens, knowledge, and innovation. For this reason, while focusing on the main results and the paradigmatic models in infectious disease modeling, the major results concerning generalized social contagion processes are also presented. Finally, the research activity at the forefront in the study of epidemic spreading in coevolving, coupled, and time-varying networks is reported.

  4. Environmental Factors Influencing Epidemic Cholera

    Science.gov (United States)

    Jutla, Antarpreet; Whitcombe, Elizabeth; Hasan, Nur; Haley, Bradd; Akanda, Ali; Huq, Anwar; Alam, Munir; Sack, R. Bradley; Colwell, Rita

    2013-01-01

    Cholera outbreak following the earthquake of 2010 in Haiti has reaffirmed that the disease is a major public health threat. Vibrio cholerae is autochthonous to aquatic environment, hence, it cannot be eradicated but hydroclimatology-based prediction and prevention is an achievable goal. Using data from the 1800s, we describe uniqueness in seasonality and mechanism of occurrence of cholera in the epidemic regions of Asia and Latin America. Epidemic regions are located near regional rivers and are characterized by sporadic outbreaks, which are likely to be initiated during episodes of prevailing warm air temperature with low river flows, creating favorable environmental conditions for growth of cholera bacteria. Heavy rainfall, through inundation or breakdown of sanitary infrastructure, accelerates interaction between contaminated water and human activities, resulting in an epidemic. This causal mechanism is markedly different from endemic cholera where tidal intrusion of seawater carrying bacteria from estuary to inland regions, results in outbreaks. PMID:23897993

  5. Epidemic spreading by objective traveling

    Science.gov (United States)

    Tang, Ming; Liu, Zonghua; Li, Baowen

    2009-07-01

    A fundamental feature of agent traveling in social networks is that traveling is usually not a random walk but with a specific destination and goes through the shortest path from starting to destination. A serious consequence of the objective traveling is that it may result in a fast epidemic spreading, such as SARS etc. In this letter we present a reaction-traveling model to study how the objective traveling influences the epidemic spreading. We consider a random scale-free meta-population network with sub-population at each node. Through a SIS model we theoretically prove that near the threshold of epidemic outbreak, the objective traveling can significantly enhance the final infected population and the infected fraction at a node is proportional to its betweenness for the traveling agents and approximately proportional to its degree for the non-traveling agents. Numerical simulations have confirmed the theoretical predictions.

  6. The narcissism epidemic is dead : Long live the narcissism epidemic

    NARCIS (Netherlands)

    Wetzel, Eunike; Brown, Anna; Hill, Patrick; Chung, J.M.H.; Robins, R.W.; Roberts, B.W.

    2017-01-01

    Are recent cohorts of college students more narcissistic than their predecessors? To address debates about the so-called “narcissism epidemic,” we used data from three cohorts of students (N1990s = 1,166; N2000s = 33,647; N2010s = 25,412) to test whether narcissism levels (overall and specific

  7. The narcissism epidemic is dead : Long live the narcissism epidemic

    NARCIS (Netherlands)

    Wetzel, Eunike; Brown, Anna; Hill, Patrick; Chung, J.M.H.; Robins, R.W.; Roberts, B.W.

    2017-01-01

    Are recent cohorts of college students more narcissistic than their predecessors? To address debates about the so-called “narcissism epidemic,” we used data from three cohorts of students (N1990s = 1,166; N2000s = 33,647; N2010s = 25,412) to test whether narcissism levels (overall and specific facet

  8. Visual Mining of Epidemic Networks

    CERN Document Server

    Clémençon, Stéphan; Rossi, Fabrice; Tran, Viet Chi; 10.1007/978-3-642-21498-1_35

    2012-01-01

    We show how an interactive graph visualization method based on maximal modularity clustering can be used to explore a large epidemic network. The visual representation is used to display statistical tests results that expose the relations between the propagation of HIV in a sexual contact network and the sexual orientation of the patients.

  9. Stochastic Processes in Epidemic Theory

    CERN Document Server

    Lefèvre, Claude; Picard, Philippe

    1990-01-01

    This collection of papers gives a representative cross-selectional view of recent developments in the field. After a survey paper by C. Lefèvre, 17 other research papers look at stochastic modeling of epidemics, both from a theoretical and a statistical point of view. Some look more specifically at a particular disease such as AIDS, malaria, schistosomiasis and diabetes.

  10. Epidemic Spread in Human Networks

    CERN Document Server

    Sahneh, Faryad Darabi

    2011-01-01

    One of the popular dynamics on complex networks is the epidemic spreading. An epidemic model describes how infections spread throughout a network. Among the compartmental models used to describe epidemics, the Susceptible-Infected-Susceptible (SIS) model has been widely used. In the SIS model, each node can be susceptible, become infected with a given infection rate, and become again susceptible with a given curing rate. In this paper, we add a new compartment to the classic SIS model to account for human response to epidemic spread. Each individual can be infected, susceptible, or alert. Susceptible individuals can become alert with an alerting rate if infected individuals exist in their neighborhood. An individual in the alert state is less probable to become infected than an individual in the susceptible state; due to a newly adopted cautious behavior. The problem is formulated as a continuous-time Markov process on a general static graph and then modeled into a set of ordinary differential equations using...

  11. Epidemic Synchronization in Robotic Swarms

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Nielsen, Jens Frederik Dalsgaard; Ngo, Trung Dung

    2009-01-01

    Clock synchronization in swarms of networked mobile robots is studied in a probabilistic, epidemic framework. In this setting communication and synchonization is considered to be a randomized process, taking place at unplanned instants of geographical rendezvous between robots. In combination wit...

  12. Epidemics spreading in interconnected complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research (A-STAR), Singapore 138632 (Singapore); Xiao, G., E-mail: egxxiao@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2012-09-03

    We study epidemic spreading in two interconnected complex networks. It is found that in our model the epidemic threshold of the interconnected network is always lower than that in any of the two component networks. Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. Theoretical analysis and simulation results show that, generally speaking, the epidemic size is not significantly affected by the inter-network correlation. In interdependent networks which can be viewed as a special case of interconnected networks, however, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant. -- Highlights: ► We study epidemic spreading in two interconnected complex networks. ► The epidemic threshold is lower than that in any of the two networks. And Interconnection correlation has impacts on threshold and average outbreak size. ► Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. ► We demonstrated and proved that Interconnection correlation does not affect epidemic size significantly. ► In interdependent networks, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant.

  13. Multiple routes transmitted epidemics on multiplex networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dawei [Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, P.O. Box 145, Beijing 100876 (China); National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Shandong Provincial Key Laboratory of Computer Network, Shandong Computer Science Center, Jinan 250014 (China); Li, Lixiang [Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, P.O. Box 145, Beijing 100876 (China); National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Peng, Haipeng, E-mail: penghaipeng@bupt.edu.cn [Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, P.O. Box 145, Beijing 100876 (China); National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Luo, Qun; Yang, Yixian [Information Security Center, State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, P.O. Box 145, Beijing 100876 (China); National Engineering Laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-02-01

    This letter investigates the multiple routes transmitted epidemic process on multiplex networks. We propose detailed theoretical analysis that allows us to accurately calculate the epidemic threshold and outbreak size. It is found that the epidemic can spread across the multiplex network even if all the network layers are well below their respective epidemic thresholds. Strong positive degree–degree correlation of nodes in multiplex network could lead to a much lower epidemic threshold and a relatively smaller outbreak size. However, the average similarity of neighbors from different layers of nodes has no obvious effect on the epidemic threshold and outbreak size. -- Highlights: •We studies multiple routes transmitted epidemic process on multiplex networks. •SIR model and bond percolation theory are used to analyze the epidemic processes. •We derive equations to accurately calculate the epidemic threshold and outbreak size. •ASN has no effect on the epidemic threshold and outbreak size. •Strong positive DDC leads to a lower epidemic threshold and a smaller outbreak size.

  14. Hepatocellular carcinoma and industrial epidemics

    Institute of Scientific and Technical Information of China (English)

    Alain Braillon; Gérard Dubois

    2011-01-01

    Worldwide, the burden of the non viral causes of hepatocellular carcinoma (HCC) is usually underestimated. Clearly industrial goods, tobacco, alcohol and processed foods are the agents of new epidemics in modern times which far outscore the burden of infectious agents on morbidity and mortality. Smoking, a dose-related contributing factor for HCC, receives too little attention in clinical practice. In France, tobacco, hepatitis B and C virus and alcohol are the main risk factors for HCC mortality (33%, 31% and 26%, respectively). In developing countries, where tobacco consumption is dramatically increasing, this epidemic may soon surpass hepatitis B. Obesity and diabetes are the contributing factors too. The role of industrial processed foods in the increase of the prevalence of obesity and diabetes cannot be ignored.

  15. The Economics of Epidemic Diseases.

    Science.gov (United States)

    Dimitri, Nicola

    2015-01-01

    Epidemic, infectious, diseases affect a large number of individuals across developing as well as developed countries. With reference to some very simple diffusion models, in this paper we consider how available economic resources could be optimally allocated by health authorities to mitigate, possibly eradicate, the disease. Optimality was defined as the minimization of the long run number of infected people. The main goal of the work has been to introduce a methodology for deciding if it would be best to concentrate resources to prevent contact between individuals and with an external source, or to develop a new treatment for curing the disease, or both. The analysis suggests that this depends on the cost functions, that is the available technology, for controlling the relevant parameters underlying the epidemics as well as on the available financial resources. In the case of the recent Ebola outbreak, the suggestions of the model have been consistent with the policies adopted.

  16. Online Plagiarism Training Falls Short in Biology Classrooms

    Science.gov (United States)

    Holt, Emily A.; Fagerheim, Britt; Durham, Susan

    2014-01-01

    Online plagiarism tutorials are increasingly popular in higher education, as faculty and staff try to curb the plagiarism epidemic. Yet no research has validated the efficacy of such tools in minimizing plagiarism in the sciences. Our study compared three plagiarism-avoidance training regimens (i.e., no training, online tutorial, or homework…

  17. Online Plagiarism Training Falls Short in Biology Classrooms

    Science.gov (United States)

    Holt, Emily A.; Fagerheim, Britt; Durham, Susan

    2014-01-01

    Online plagiarism tutorials are increasingly popular in higher education, as faculty and staff try to curb the plagiarism epidemic. Yet no research has validated the efficacy of such tools in minimizing plagiarism in the sciences. Our study compared three plagiarism-avoidance training regimens (i.e., no training, online tutorial, or homework…

  18. Networked SIS Epidemics with Awareness

    CERN Document Server

    Paarporn, Keith; Weitz, Joshua S; Shamma, Jeff S

    2016-01-01

    We study an SIS epidemic process over a static contact network where the nodes have partial information about the epidemic state. They react by limiting their interactions with their neighbors when they believe the epidemic is currently prevalent. A node's awareness is weighted by the fraction of infected neighbors in their social network, and a global broadcast of the fraction of infected nodes in the entire network. The dynamics of the benchmark (no awareness) and awareness models are described by discrete-time Markov chains, from which mean-field approximations (MFA) are derived. The states of the MFA are interpreted as the nodes' probabilities of being infected. We show a sufficient condition for existence of a "metastable", or endemic, state of the awareness model coincides with that of the benchmark model. Furthermore, we use a coupling technique to give a full stochastic comparison analysis between the two chains, which serves as a probabilistic analogue to the MFA analysis. In particular, we show that...

  19. Understanding the Cholera Epidemic, Haiti

    Science.gov (United States)

    Barrais, Robert; Faucher, Benoît; Haus, Rachel; Piarroux, Martine; Gaudart, Jean; Magloire, Roc; Raoult, Didier

    2011-01-01

    After onset of a cholera epidemic in Haiti in mid-October 2010, a team of researchers from France and Haiti implemented field investigations and built a database of daily cases to facilitate identification of communes most affected. Several models were used to identify spatiotemporal clusters, assess relative risk associated with the epidemic’s spread, and investigate causes of its rapid expansion in Artibonite Department. Spatiotemporal analyses highlighted 5 significant clusters (p<0.001): 1 near Mirebalais (October 16–19) next to a United Nations camp with deficient sanitation, 1 along the Artibonite River (October 20–28), and 3 caused by the centrifugal epidemic spread during November. The regression model indicated that cholera more severely affected communes in the coastal plain (risk ratio 4.91) along the Artibonite River downstream of Mirebalais (risk ratio 4.60). Our findings strongly suggest that contamination of the Artibonite and 1 of its tributaries downstream from a military camp triggered the epidemic. PMID:21762567

  20. Leveraging social networks for understanding the evolution of epidemics

    Directory of Open Access Journals (Sweden)

    Martín Gonzalo

    2011-12-01

    Full Text Available Abstract Background To understand how infectious agents disseminate throughout a population it is essential to capture the social model in a realistic manner. This paper presents a novel approach to modeling the propagation of the influenza virus throughout a realistic interconnection network based on actual individual interactions which we extract from online social networks. The advantage is that these networks can be extracted from existing sources which faithfully record interactions between people in their natural environment. We additionally allow modeling the characteristics of each individual as well as customizing his daily interaction patterns by making them time-dependent. Our purpose is to understand how the infection spreads depending on the structure of the contact network and the individuals who introduce the infection in the population. This would help public health authorities to respond more efficiently to epidemics. Results We implement a scalable, fully distributed simulator and validate the epidemic model by comparing the simulation results against the data in the 2004-2005 New York State Department of Health Report (NYSDOH, with similar temporal distribution results for the number of infected individuals. We analyze the impact of different types of connection models on the virus propagation. Lastly, we analyze and compare the effects of adopting several different vaccination policies, some of them based on individual characteristics -such as age- while others targeting the super-connectors in the social model. Conclusions This paper presents an approach to modeling the propagation of the influenza virus via a realistic social model based on actual individual interactions extracted from online social networks. We implemented a scalable, fully distributed simulator and we analyzed both the dissemination of the infection and the effect of different vaccination policies on the progress of the epidemics. The epidemic values

  1. Dynamic Forecasting of Zika Epidemics Using Google Trends.

    Science.gov (United States)

    Teng, Yue; Bi, Dehua; Xie, Guigang; Jin, Yuan; Huang, Yong; Lin, Baihan; An, Xiaoping; Feng, Dan; Tong, Yigang

    2017-01-01

    We developed a dynamic forecasting model for Zika virus (ZIKV), based on real-time online search data from Google Trends (GTs). It was designed to provide Zika virus disease (ZVD) surveillance and detection for Health Departments, and predictive numbers of infection cases, which would allow them sufficient time to implement interventions. In this study, we found a strong correlation between Zika-related GTs and the cumulative numbers of reported cases (confirmed, suspected and total cases; pforecasting results indicated that the predicted data by ARIMA model, which used the online search data as the external regressor to enhance the forecasting model and assist the historical epidemic data in improving the quality of the predictions, are quite similar to the actual data during ZIKV epidemic early November 2016. Integer-valued autoregression provides a useful base predictive model for ZVD cases. This is enhanced by the incorporation of GTs data, confirming the prognostic utility of search query based surveillance. This accessible and flexible dynamic forecast model could be used in the monitoring of ZVD to provide advanced warning of future ZIKV outbreaks.

  2. Competing activation mechanisms in epidemics on networks

    CERN Document Server

    Castellano, Claudio

    2011-01-01

    In stark contrast to previous common wisdom that epidemic activity and thresholds in heterogeneous networks are dominated by the elements with the largest number of connections (the hubs), recent research has pointed out the role of the most efficient spreaders, located at the innermost, dense core of the network, in sustaining epidemic processes. Here we show that the mechanism responsible of epidemic spreading depends on the dynamical pattern of the epidemic process. For epidemics with a transient state, activity is essentially boosted by the innermost core of the network. On the contrary, epidemics allowing a steady state present a dual scenario, where either the vertex with the largest connectivity independently sustains activity and propagates it to the rest of the system, or, alternatively, the innermost core of the network collectively turns into the active state, maintaining it on a global scale. Which one of these two mechanisms actually governs the dynamics depends on the network features. In uncorr...

  3. Fractional Derivatives in Dengue Epidemics

    Science.gov (United States)

    Pooseh, Shakoor; Rodrigues, Helena Sofia; Torres, Delfim F. M.

    2011-09-01

    We introduce the use of fractional calculus, i.e., the use of integrals and derivatives of non-integer (arbitrary) order, in epidemiology. The proposed approach is illustrated with an outbreak of dengue disease, which is motivated by the first dengue epidemic ever recorded in the Cape Verde islands off the coast of west Africa, in 2009. Numerical simulations show that in some cases the fractional models fit better the reality when compared with the standard differential models. The classical results are obtained as particular cases by considering the order of the derivatives to take an integer value.

  4. The cancer, a silent epidemic.

    Directory of Open Access Journals (Sweden)

    Edith María Beltrán Molina

    2014-03-01

    Full Text Available This article deals with some very interesting aspects related to cancer the first cause of death in many countries with a high prevalence in Cuba so it is necessary to increase prevention and education to reduce risk factors and prevalence of malignancy. Taking into account the importance of cancer awareness as well as the social therapeutic and technological resources available to Cuba for its treatment it is propose with this work to exemplify the Cuban scientific treatment of cancer as a silent epidemic of the XXI century.

  5. SIS epidemic propagation on hypergraphs

    CERN Document Server

    Bodó, Ágnes; Simon, Péter L

    2015-01-01

    Mathematical modeling of epidemic propagation on networks is extended to hypergraphs in order to account for both the community structure and the nonlinear dependence of the infection pressure on the number of infected neighbours. The exact master equations of the propagation process are derived for an arbitrary hypergraph given by its incidence matrix. Based on these, moment closure approximation and mean-?eld models are introduced and compared to individual-based stochastic simulations. The simulation algorithm, developed for networks, is extended to hypergraphs. The e?ects of hypergraph structure and the model parameters are investigated via individual-based simulation results.

  6. Fractional derivatives in Dengue epidemics

    CERN Document Server

    Pooseh, Shakoor; Torres, Delfim F M

    2011-01-01

    We introduce the use of fractional calculus, i.e., the use of integrals and derivatives of non-integer (arbitrary) order, in epidemiology. The proposed approach is illustrated with an outbreak of dengue disease, which is motivated by the first dengue epidemic ever recorded in the Cape Verde islands off the coast of west Africa, in 2009. Numerical simulations show that in some cases the fractional models fit better the reality when compared with the standard differential models. The classical results are obtained as particular cases by considering the order of the derivatives to take an integer value.

  7. Online Gaming

    Directory of Open Access Journals (Sweden)

    Kevin Curran

    2005-01-01

    Full Text Available Computer gaming is a medium by which we can entertain ourselves, a medium that has expanded to the online worldwide market as part as globalization. The growth of online gaming has close ties with the use of broadband, as a good online gaming experience requires a broadband connection. Through online gaming, people can play and communicate with each other freely in almost any country, at any given time. This paper examines the phenomenon of online gaming.

  8. Epidemic suicide among Micronesian adolescents.

    Science.gov (United States)

    Rubinstein, D H

    1983-01-01

    Suicide rates since 1960 in Micronesia (the U.S. Trust Territory of the Pacific Islands) have undergone an epidemic-like increase. This phenomenon is focused narrowly within the 15--24-year male age-group. Extremely high rates and culturally patterned motives and methods are now characteristic of this group. Survey research throughout Micronesia suggests that the epidemic increase in adolescent male suicide is a cohort effect among the first post-war generation. Traditional adolescent socialization in pre-war Micronesia largely involved village-level subsistence activities organized around communal lineage-houses. This extra-familial level of socialization served as a cultural solution to the residential and psychological distance post-pubertal males maintained from their domestic families. With the post-war social change in Micronesia, the communal village-level of organization has largely disintegrated, causing adolescent socialization functions to be absorbed by the nuclear family. The resulting situations of intergenerational domestic discord appear the primary social triggers for adolescent suicide. At the same time, suicides have acquired subcultural significance among male youth, giving rise to fad-like and imitative acts. A 3-year research project is now being undertaken to conduct an ethnographic study of factors contributing to adolescent stress and suicide in one Micronesian community.

  9. Modeling and simulation of epidemic spread

    DEFF Research Database (Denmark)

    Shatnawi, Maad; Lazarova-Molnar, Sanja; Zaki, Nazar

    2013-01-01

    and control such epidemics. This paper presents an overview of the epidemic spread modeling and simulation, and summarizes the main technical challenges in this field. It further investigates the most relevant recent approaches carried out towards this perspective and provides a comparison and classification...

  10. Contact allergy epidemics and their controls

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Johansen, Jeanne Duus; Menné, Torkil

    2007-01-01

    Contact dermatitis can be severe and lead to sick leave as well as significant healthcare expenses. The aim of this review is to present the published knowledge on 6 historical epidemics of contact allergy to apply this knowledge on the prevention and control of future contact allergy epidemics...

  11. Epidemics in interconnected small-world networks

    NARCIS (Netherlands)

    Liu, M.; Li, D.; Qin, P.; Liu, C.; Wang, H.; Wang, F.

    2015-01-01

    Networks can be used to describe the interconnections among individuals, which play an important role in the spread of disease. Although the small-world effect has been found to have a significant impact on epidemics in single networks, the small-world effect on epidemics in interconnected networks

  12. Malaria Epidemic and Drug Resistance, Djibouti

    OpenAIRE

    Rogier, Christophe; Pradines, Bruno; Bogreau, H.; Koeck, Jean-Louis; Kamil, Mohamed-Ali; Mercereau-Puijalon, Odile

    2005-01-01

    Analysis of Plasmodium falciparum isolates collected before, during, and after a 1999 malaria epidemic in Djibouti shows that, despite a high prevalence of resistance to chloroquine, the epidemic cannot be attributed to a sudden increase in drug resistance of local parasite populations.

  13. Inferring epidemic contact structure from phylogenetic trees.

    Directory of Open Access Journals (Sweden)

    Gabriel E Leventhal

    Full Text Available Contact structure is believed to have a large impact on epidemic spreading and consequently using networks to model such contact structure continues to gain interest in epidemiology. However, detailed knowledge of the exact contact structure underlying real epidemics is limited. Here we address the question whether the structure of the contact network leaves a detectable genetic fingerprint in the pathogen population. To this end we compare phylogenies generated by disease outbreaks in simulated populations with different types of contact networks. We find that the shape of these phylogenies strongly depends on contact structure. In particular, measures of tree imbalance allow us to quantify to what extent the contact structure underlying an epidemic deviates from a null model contact network and illustrate this in the case of random mixing. Using a phylogeny from the Swiss HIV epidemic, we show that this epidemic has a significantly more unbalanced tree than would be expected from random mixing.

  14. Epidemic centrality and the underestimated epidemic impact on network peripheral nodes

    CERN Document Server

    Sikic, Mile; Antulov-Fantulin, Nino; Stefancic, Hrvoje

    2011-01-01

    Studies of disease spreading on complex networks have provided a deep insight into the conditions of onset, dynamics and prevention of epidemics in human populations and malicious software propagation in computer networks. Identifying nodes which, when initially infected, infect the largest part of the network and ranking them according to their epidemic impact is a priority for public health policies. In simulations of the disease spreading in SIR model on studied empirical complex networks, it is shown that the ranking depends on the dynamical regime of the disease spreading. A possible mechanism leading to this dynamical dependence is illustrated in an analytically tractable example. A measure called epidemic centrality, averaging the epidemic impact over all possible disease spreading regimes, is introduced as a basis of epidemic ranking. Contrary to standard notion, the epidemic centrality of nodes with high degree, k-cores value or betweenness, which are structurally central, is comparable to epidemic c...

  15. An epidemic outbreak of cryptosporidiosis

    DEFF Research Database (Denmark)

    Mølbak, Kåre; Højlyng, Niels; Ingholt, Liselotte

    1990-01-01

    In the first year of a prospective community study of childhood diarrhea conducted in a semiurban area in the capital of Guinea Bissau, Cryptosporidium sp. was found in 73 (6.0%) of 1216 episodes of diarrhea. The parasite was the second most prevalent intestinal parasite, and the only one...... significantly associated with diarrhea (OR = 2.79, P = 0.0006). The seasonal distribution was striking, with a peak prevalence in the beginning of the rainy season (May 17.6%) when an epidemic outbreak of diarrhea started. The prevalence was highest in children younger than 18 months, an age at which...... prevalences of other intestinal parasites were low. This reverse age pattern may possibly be explained by the small infective dose needed to create severe infections, by air-borne transmission and by the development of protective immunity....

  16. Cooperative epidemics on multiplex networks

    CERN Document Server

    Azimi-Tafreshi, N

    2015-01-01

    The spread of one disease, in some cases, can stimulate the spreading of another infectious disease. Here, we treat analytically a symmetric co-infection model for spreading of two diseases on a 2-layer multiplex network. We allow layer overlapping, but we assume that each layer is random and locally loop-less. Infection with one of the diseases increases the probability to get infected by the other. Using generating function method, we calculate exactly the fraction of individuals infected with both diseases (so-called co-infected clusters) in the stationary state, as well as the epidemic spreading thresholds and the phase diagram of the model. With increasing cooperation, we observe a tricritical point and the type of transition changes from continuous to hybrid. Finally we compare the co-infected clusters in the case of co-operating diseases with the so-called viable clusters in networks with dependencies.

  17. Familial epidemic of meningococcal disease.

    Science.gov (United States)

    Smilović, V; Vrbanec-Megla, L; Payerl-Pal, M; Puntarić, D; Baklaić, Z

    1998-03-01

    Two closely related boys from the same house hold (Home 1), aged two and three, were affected with fulminant meningococcal sepsis known as Waterhouse-Friderichsen syndrome. Neisseria meningitidis serogorup B was isolated from their blood and cerebrospinal fluid. The two-year-old boy died one day after the onset of the disease. Epidemiological examination of contacts and pharyngeal swabs were performed in 14 persons from the household, all of them relatives of the affected children, as well as in a number of other contacts. Chemoprophylaxis with cotrimoxazole was simultaneously administered to all contacts. Family histories revealed that two contacts from the household where the patients did not live (Home 2) were inadvertently omitted. Subsequent examinations, following a report of another contagious disease (salmonelosis), revealed that these two persons were Neisseria meningitidis carriers, together with another one in the same household. The carriers most probably caused the infection of a third, five-year-old boy, the deceased boy's brother (Home 1) who also developed fulminant meningococcal sepsis. The failure to take the appropriate prophylaxis led to a prolonged carrier state in the carrier from the second household. Repeated pharyngeal swab sampling revealed two more carriers from both households that had previously been negative. Control of the epidemic was achieved after 5 weeks by repeated and controlled chemoprophylaxis with ciprofloxacin, and by repeated epidemiological examinations, disinfection, and daily health surveillance by the Sanitary Inspectorate. This extremely rare instance of a familial epidemic with three infected persons emphasizes the need for consistent chemoprophylaxis in meningococcal disease contacts.

  18. Online reklama

    OpenAIRE

    Švarc, Ondřej

    2016-01-01

    This thesis is thematically focused on online advertising. The paper describes the history of online advertising and its advantages and disadvantages compared to other media types. There are mentioned standards of online advertising on the Czech Internet and ways to optimize the different types for better performance. Next we go over the characteristics of selected tools for assessing the success and management of online campaigns. We also compare the advertising possibilities ...

  19. Heterogeneous edge weights promote epidemic diffusion in weighted evolving networks

    Science.gov (United States)

    Duan, Wei; Song, Zhichao; Qiu, Xiaogang

    2016-08-01

    The impact that the heterogeneities of links’ weights have on epidemic diffusion in weighted networks has received much attention. Investigating how heterogeneous edge weights affect epidemic spread is helpful for disease control. In this paper, we study a Reed-Frost epidemic model in weighted evolving networks. Our results indicate that a higher heterogeneity of edge weights leads to higher epidemic prevalence and epidemic incidence at earlier stage of epidemic diffusion in weighted evolving networks. In addition, weighted evolving scale-free networks come with a higher epidemic prevalence and epidemic incidence than unweighted scale-free networks.

  20. Identifying Influential Spreaders of Epidemics on Community Networks

    CERN Document Server

    Luo, Shi-Long; Kang, Li

    2016-01-01

    An efficient strategy for the identification of influential spreaders that could be used to control epidemics within populations would be of considerable importance. Generally, populations are characterized by its community structures and by the heterogeneous distributions of weak ties among nodes bridging over communities. A strategy for community networks capable of identifying influential spreaders that accelerate the spread of disease is here proposed. In this strategy, influential spreaders serve as target nodes. This is based on the idea that, in k-shell decomposition, weak ties and strong ties are processed separately. The strategy was used on empirical networks constructed from online social networks, and results indicated that this strategy is more accurate than other strategies. Its effectiveness stems from the patterns of connectivity among neighbors, and it successfully identified the important nodes. In addition, the performance of the strategy remained robust even when there were errors in the s...

  1. Fibroid Tumors in Women: A Hidden Epidemic?

    Science.gov (United States)

    ... Issue Past Issues Fibroid Tumors in Women: A Hidden Epidemic? Past Issues / Spring 2007 Table of Contents ... fibroids@rics.bwh.harvard.edu , or visit our Web site: www.fibroids.net . You may also write ...

  2. Generation interval contraction and epidemic data analysis

    CERN Document Server

    Kenah, Eben; Robins, James M

    2008-01-01

    The generation interval is the time between the infection time of an infected person and the infection time of his or her infector. Probability density functions for generation intervals have been an important input for epidemic models and epidemic data analysis. In this paper, we specify a general stochastic SIR epidemic model and prove that the mean generation interval decreases when susceptible persons are at risk of infectious contact from multiple sources. The intuition behind this is that when a susceptible person has multiple potential infectors, there is a ``race'' to infect him or her in which only the first infectious contact leads to infection. In an epidemic, the mean generation interval contracts as the prevalence of infection increases. We call this global competition among potential infectors. When there is rapid transmission within clusters of contacts, generation interval contraction can be caused by a high local prevalence of infection even when the global prevalence is low. We call this loc...

  3. Some discrete SI and SIS epidemic models

    Institute of Scientific and Technical Information of China (English)

    LI Jian-quan; LOU Jie; LOU Mei-zhi

    2008-01-01

    The probability is introduced to formulate the death of individuals, the recovery of the infected individuals and incidence of epidemic disease. Based on the assumption that the number of individuals in a population is a constant, discrete-time SI and SIS epidemic models with vital dynamics are established respectively corresponding to the case that the infectives can recover from the disease or not. For these two models, the results obtained in this paper show that there is the same dynamical behavior as their corresponding continuous ones, and the threshold determining its dynamical behavior is found. Below the threshold the epidemic disease dies out eventually, above the threshold the epidemic disease becomes an endemic eventually, and the number of the infectives approaches a positive constant.

  4. On spatially explicit models of cholera epidemics

    National Research Council Canada - National Science Library

    Bertuzzo, E; Casagrandi, R; Gatto, M; Rodriguez-Iturbe, I; Rinaldo, A

    2010-01-01

    We generalize a recently proposed model for cholera epidemics that accounts for local communities of susceptibles and infectives in a spatially explicit arrangement of nodes linked by networks having...

  5. Reporting epidemics: newspapers, information dissemination and ...

    African Journals Online (AJOL)

    Pan African Medical Journal ... When an outbreak occurs, the affected population needs timely information in order to make informed decisions on how best to deal with ... Key words: Ebola, Uganda, epidemic, case, reporting, media, Uganda ...

  6. Detecting nonlinearity and chaos in epidemic data

    Energy Technology Data Exchange (ETDEWEB)

    Ellner, S.; Gallant, A.R. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Statistics; Theiler, J. [Santa Fe Inst., NM (United States)]|[Los Alamos National Lab., NM (United States)

    1993-08-01

    Historical data on recurrent epidemics have been central to the debate about the prevalence of chaos in biological population dynamics. Schaffer and Kot who first recognized that the abundance and accuracy of disease incidence data opened the door to applying a range of methods for detecting chaos that had been devised in the early 1980`s. Using attractor reconstruction, estimates of dynamical invariants, and comparisons between data and simulation of SEIR models, the ``case for chaos in childhood epidemics`` was made through a series of influential papers beginning in the mid 1980`s. The proposition that the precise timing and magnitude of epidemic outbreaks are deterministic but chaotic is appealing, since it raises the hope of finding determinism and simplicity beneath the apparently stochastic and complicated surface of the data. The initial enthusiasm for methods of detecting chaos in data has been followed by critical re-evaluations of their limitations. Early hopes of a ``one size fits all`` algorithm to diagnose chaos vs. noise in any data set have given way to a recognition that a variety of methods must be used, and interpretation of results must take into account the limitations of each method and the imperfections of the data. Our goals here are to outline some newer methods for detecting nonlinearity and chaos that have a solid statistical basis and are suited to epidemic data, and to begin a re-evaluation of the claims for nonlinear dynamics and chaos in epidemics using these newer methods. We also identify features of epidemic data that create problems for the older, better known methods of detecting chaos. When we ask ``are epidemics nonlinear?``, we are not questioning the existence of global nonlinearities in epidemic dynamics, such as nonlinear transmission rates. Our question is whether the data`s deviations from an annual cyclic trend (which would reflect global nonlinearities) are described by a linear, noise-driven stochastic process.

  7. Second Quantization Approach to Stochastic Epidemic Models

    CERN Document Server

    Mondaini, Leonardo

    2015-01-01

    We show how the standard field theoretical language based on creation and annihilation operators may be used for a straightforward derivation of closed master equations describing the population dynamics of multivariate stochastic epidemic models. In order to do that, we introduce an SIR-inspired stochastic model for hepatitis C virus epidemic, from which we obtain the time evolution of the mean number of susceptible, infected, recovered and chronically infected individuals in a population whose total size is allowed to change.

  8. Phylodynamic analysis of HIV sub-epidemics in Mochudi, Botswana

    Directory of Open Access Journals (Sweden)

    Vlad Novitsky

    2015-12-01

    Real-time HIV genotyping and breaking down local HIV epidemics into phylogenetically distinct sub-epidemics may help to reveal the structure and dynamics of HIV transmission networks in communities, and aid in the design of targeted interventions for members of the acute sub-epidemics that likely fuel local HIV/AIDS epidemics.

  9. Online Advertising

    OpenAIRE

    Goldfarb, Avi; Tucker, Catherine Elizabeth

    2011-01-01

    This chapter explores what makes online advertising different from traditional advertising channels. We argue that online advertising differs from traditional advertising channels in two important ways: measurability and targetability. Measurability is higher because the digital nature of online advertising means that responses to ads can be tracked relatively easily. Targetability is higher because data can be automatically tracked at an individual level, and it is relatively easy to show di...

  10. [The history of cholera epidemics in Israel].

    Science.gov (United States)

    Schwartz, Eli; Bar-El, Dan; Schur, Natan

    2005-05-01

    During the years 1831-1918 Israel (Palestine at that time) suffered from repeated cholera epidemics. The cholera epidemics were the major cause of severe health crisis among the population. The epidemics were transmitted by returening pilgrims returning from Mecca and, during the first world War, by the Turkish soldiers crossing the country. The disease caused panic amongst the population due to its high mortality rate. Quarantine which was the major measure taken by the government at that time was repeatedly broken by people trying to escape from the affected area. During the epidemic of 1902, patients were even reluctant to be treated by physicians as they were blamed for causing death. On the other hand, cholera was a major trigger for maintaining a better sanitation and establishing social relief systems within the communities. Most of the epidemics occurred in the old cities such as Jerusalem, Tiberia and Jaffa where infrastructure was inadequate. Cholera outbreaks were the trigger to build outside the old cities as in case of Jerusalem in which after the 1865 outbreak the city was expanded outside the walls. Since the end of the Ottoman period in Israel, cholera epidemics ceased, and except for very small occeasional small outbreaks, cholera is not seen here more.

  11. Cholera epidemic threatens Sierra Leone.

    Science.gov (United States)

    Dyer, O

    1995-07-08

    Sierra Leone faces the threat of a major epidemic of cholera with the onset of the rainy season, according to the World Health Organization (WHO). The situation is particularly grave for the two million people displaced by the country's civil war. Already 1709 cases of cholera have been registered in Freetown, with 57 deaths. Freetown's population has doubled since the start of the war in 1991 with 750,000 refugees camping out in the town. The insurgent Revolutionary United Front is now within 32 km of the capital. Provinces are cut off from the capital, medical supplies are scarce. Doctors and aid workers are forced to rely on a private helicopter service for personal transport. As many as 10,000 people were affected by the disease last year. WHO experts predict that pneumonia is likely to claim the lives of many children, and a highly drug resistant strain of Plasmodium falciparum malaria is also looming. The greatest problems are the lack of safe drinking water and the attendant risks of cholera and dysentery. At one site in Freetown the 6000 refugees have to fetch water from a well and have no latrines. As a result there have been 277 cases of cholera and 2 deaths already among that group. The health department has set up five centers to treat cholera in Freetown and is organizing mobile clinics. WHO's Sierra Leone office is assisting the government mobile health teams, which provide free primary care to displaced people. Medicines and vaccines, however, are lacking. Many of the staff of the 13 district health authorities have been displaced to Freetown. Aid agencies such as Medecins Sans Frontieres and Oxfam have stepped into the role in many districts. Ironically, one of the Revolutionary United Front's main demands is for a free national health service.

  12. FluBreaks: early epidemic detection from Google flu trends.

    Science.gov (United States)

    Pervaiz, Fahad; Pervaiz, Mansoor; Abdur Rehman, Nabeel; Saif, Umar

    2012-10-04

    The Google Flu Trends service was launched in 2008 to track changes in the volume of online search queries related to flu-like symptoms. Over the last few years, the trend data produced by this service has shown a consistent relationship with the actual number of flu reports collected by the US Centers for Disease Control and Prevention (CDC), often identifying increases in flu cases weeks in advance of CDC records. However, contrary to popular belief, Google Flu Trends is not an early epidemic detection system. Instead, it is designed as a baseline indicator of the trend, or changes, in the number of disease cases. To evaluate whether these trends can be used as a basis for an early warning system for epidemics. We present the first detailed algorithmic analysis of how Google Flu Trends can be used as a basis for building a fully automated system for early warning of epidemics in advance of methods used by the CDC. Based on our work, we present a novel early epidemic detection system, called FluBreaks (dritte.org/flubreaks), based on Google Flu Trends data. We compared the accuracy and practicality of three types of algorithms: normal distribution algorithms, Poisson distribution algorithms, and negative binomial distribution algorithms. We explored the relative merits of these methods, and related our findings to changes in Internet penetration and population size for the regions in Google Flu Trends providing data. Across our performance metrics of percentage true-positives (RTP), percentage false-positives (RFP), percentage overlap (OT), and percentage early alarms (EA), Poisson- and negative binomial-based algorithms performed better in all except RFP. Poisson-based algorithms had average values of 99%, 28%, 71%, and 76% for RTP, RFP, OT, and EA, respectively, whereas negative binomial-based algorithms had average values of 97.8%, 17.8%, 60%, and 55% for RTP, RFP, OT, and EA, respectively. Moreover, the EA was also affected by the region's population size

  13. Epidemic Survivability: Characterizing Networks Under Epidemic-like Failure Propagation Scenarios

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

    2013-01-01

    in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur...

  14. Ten Putative Contributors to the Obesity Epidemic

    Science.gov (United States)

    McAllister, Emily J.; Dhurandhar, Nikhil V.; Keith, Scott W.; Aronne, Louis J.; Barger, Jamie; Baskin, Monica; Benca, Ruth M.; Biggio, Joseph; Boggiano, Mary M.; Eisenmann, Joe C.; Elobeid, Mai; Fontaine, Kevin R.; Gluckman, Peter; Hanlon, Erin C.; Katzmarzyk, Peter; Pietrobelli, Angelo; Redden, David T.; Ruden, Douglas M.; Wang, Chenxi; Waterland, Robert A.; Wright, Suzanne M.; Allison, David B.

    2010-01-01

    The obesity epidemic is a global issue and shows no signs of abating, while the cause of this epidemic remains unclear. Marketing practices of energy-dense foods and institutionally-driven declines in physical activity are the alleged perpetrators for the epidemic, despite a lack of solid evidence to demonstrate their causal role. While both may contribute to obesity, we call attention to their unquestioned dominance in program funding and public efforts to reduce obesity, and propose several alternative putative contributors that would benefit from equal consideration and attention. Evidence for microorganisms, epigenetics, increasing maternal age, greater fecundity among people with higher adiposity, assortative mating, sleep debt, endocrine disruptors, pharmaceutical iatrogenesis, reduction in variability of ambient temperatures, and intrauterine and intergenerational effects, as contributing factors to the obesity epidemic are reviewed herein. While the evidence is strong for some contributors such as pharmaceutical-induced weight gain, it is still emerging for other reviewed factors. Considering the role of such putative etiological factors of obesity may lead to comprehensive, cause specific, and effective strategies for prevention and treatment of this global epidemic. PMID:19960394

  15. Epidemic Spreading in Random Rectangular Networks

    CERN Document Server

    Estrada, Ernesto; Moreno, Yamir

    2015-01-01

    Recently, Estrada and Sheerin (Phys. Rev. E 91, 042805 (2015)) developed the random rectangular graph (RRG) model to account for the spatial distribution of nodes in a network allowing the variation of the shape of the unit square commonly used in random geometric graphs (RGGs). Here, we consider an epidemics dynamics taking place on the nodes and edges of an RRG and we derive analytically a lower bound for the epidemic threshold for a Susceptible-Infected-Susceptible (SIS) or Susceptible-Infected-Recovered (SIR) model on these networks. Using extensive numerical simulations of the SIS dynamics we show that the lower bound found is very tight. We conclude that the elongation of the area in which the nodes are distributed makes the network more resilient to the propagation of an epidemics due to the fact that the epidemic threshold increases with the elongation of the rectangle. On the other hand, using the "classical" RGG for modeling epidemics on non-squared cities generates a larger error due to the effects...

  16. Vaccination intervention on epidemic dynamics in networks

    CERN Document Server

    Peng, Xiao-Long; Fu, Xinchu; Zhou, Tao

    2013-01-01

    Vaccination is an important measure available for preventing or reducing the spread of infectious diseases. In this paper, an epidemic model including susceptible, infected, and imperfectly vaccinated compartments is studied on Watts-Strogatz small-world, Barab\\'asi-Albert scale-free, and random scale-free networks. The epidemic threshold and prevalence are analyzed. For small-world networks, the effective vaccination intervention is suggested and its influence on the threshold and prevalence is analyzed. For scale-free networks, the threshold is found to be strongly dependent both on the effective vaccination rate and on the connectivity distribution. Moreover, so long as vaccination is effective, it can linearly decrease the epidemic prevalence in small-world networks, whereas for scale-free networks it acts exponentially. These results can help in adopting pragmatic treatment upon diseases in structured populations.

  17. Urgent epidemic control mechanism for aviation networks

    KAUST Repository

    Peng, Chengbin

    2011-01-01

    In the current century, the highly developed transportation system can not only boost the economy, but also greatly accelerate the spreading of epidemics. While some epidemic diseases may infect quite a number of people ahead of our awareness, the health care resources such as vaccines and the medical staff are usually locally or even globally insufficient. In this research, with the network of major aviation routes as an example, we present a method to determine the optimal locations to allocate the medical service in order to minimize the impact of the infectious disease with limited resources. Specifically, we demonstrate that when the medical resources are insufficient, we should concentrate our efforts on the travelers with the objective of effectively controlling the spreading rate of the epidemic diseases. © 2011 Springer-Verlag Berlin Heidelberg.

  18. Pursuing Justice in Haiti's Cholera Epidemic.

    Science.gov (United States)

    Weinmeyer, Richard

    2016-07-01

    In 2010, the nation of Haiti was leveled by a shattering earthquake that killed thousands and devastated its already fragile infrastructure. During relief efforts to aid Haiti's suffering population, the United Nations sent troops to Haiti to assist the rebuilding of country's most basic services. But those troops unknowingly carried with them the bacteria that cause cholera, and through the UN's negligent actions, it triggered a horrifying cholera epidemic that continues to harm the Haitian people. Those injured by the cholera epidemic have sought relief in the US federal court system to obtain justice for those killed or sickened by the cholera outbreak. The UN has declared legal immunity for causing the epidemic, yet the litigation on this matter is ongoing. © 2016 American Medical Association. All Rights Reserved. ISSN 2376-6980.

  19. Epidemic and Cascading Survivability of Complex Networks

    CERN Document Server

    Manzano, Marc; Ripoll, Jordi; Fagertun, Anna Manolova; Torres-Padrosa, Victor; Pahwa, Sakshi; Scoglio, Caterina

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present \\emph{epidemic survivability} ($ES$), a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose \\emph{cascading survivability} ($CS$), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from $ES$ and $CS$ it is possible to describe the vulnerability of a given network. We consider a set of 17 different compl...

  20. Inferring epidemic network topology from surveillance data.

    Science.gov (United States)

    Wan, Xiang; Liu, Jiming; Cheung, William K; Tong, Tiejun

    2014-01-01

    The transmission of infectious diseases can be affected by many or even hidden factors, making it difficult to accurately predict when and where outbreaks may emerge. One approach at the moment is to develop and deploy surveillance systems in an effort to detect outbreaks as timely as possible. This enables policy makers to modify and implement strategies for the control of the transmission. The accumulated surveillance data including temporal, spatial, clinical, and demographic information, can provide valuable information with which to infer the underlying epidemic networks. Such networks can be quite informative and insightful as they characterize how infectious diseases transmit from one location to another. The aim of this work is to develop a computational model that allows inferences to be made regarding epidemic network topology in heterogeneous populations. We apply our model on the surveillance data from the 2009 H1N1 pandemic in Hong Kong. The inferred epidemic network displays significant effect on the propagation of infectious diseases.

  1. The epidemic of Tuberculosis on vaccinated population

    Science.gov (United States)

    Syahrini, Intan; Sriwahyuni; Halfiani, Vera; Meurah Yuni, Syarifah; Iskandar, Taufiq; Rasudin; Ramli, Marwan

    2017-09-01

    Tuberculosis is an infectious disease which has caused a large number of mortality in Indonesia. This disease is caused by Mycrobacterium tuberculosis. Besides affecting lung, this disease also affects other organs such as lymph gland, intestine, kidneys, uterus, bone, and brain. This article discusses the epidemic of tuberculosis through employing the SEIR model. Here, the population is divided into four compartments which are susceptible, exposed, infected and recovered. The susceptible population is further grouped into two which are vaccinated group and unvaccinated group. The behavior of the epidemic is investigated through analysing the equilibrium of the model. The result shows that administering vaccine to the susceptible population contributes to the reduction of the tuberculosis epidemic rate.

  2. Epidemic spreading with immunization on bipartite networks

    CERN Document Server

    Tanimoto, Shinji

    2011-01-01

    Bipartite networks are composed of two types of nodes and there are no links between nodes of the same type. Thus the study of epidemic spread and control on such networks is relevant to sexually transmitted diseases (STDs). When entire populations of two types cannot be immunized and the effect of immunization is not perfect, we have to consider the targeted immunization with immunization rates. We derive the epidemic thresholds of SIR and SIS models with immunization and illustrate the results with STDs on heterosexual contact networks.

  3. Forecasting peaks of seasonal influenza epidemics.

    Science.gov (United States)

    Nsoesie, Elaine; Mararthe, Madhav; Brownstein, John

    2013-06-21

    We present a framework for near real-time forecast of influenza epidemics using a simulation optimization approach. The method combines an individual-based model and a simple root finding optimization method for parameter estimation and forecasting. In this study, retrospective forecasts were generated for seasonal influenza epidemics using web-based estimates of influenza activity from Google Flu Trends for 2004-2005, 2007-2008 and 2012-2013 flu seasons. In some cases, the peak could be forecasted 5-6 weeks ahead. This study adds to existing resources for influenza forecasting and the proposed method can be used in conjunction with other approaches in an ensemble framework.

  4. Online Tracking

    Science.gov (United States)

    ... Making Money Privacy, Identity & Online Security Blog Video & Media Scam Alerts ... Feed Facebook YouTube Twitter The Federal Trade Commission (FTC) is the nation’s consumer protection agency. ...

  5. Online dictionaries

    DEFF Research Database (Denmark)

    Tarp, Sven

    2012-01-01

    This article initially provides a panoramic overview and a preliminary typologization of present and future online dictionaries based upon their application of the available technologies and suggests that the future of lexicography will be the development of highly sophisticated tools which may......, need, consultation, and data. The article then proceeds to the discussion of some advanced information science techniques that may contribute to the desired individualization. Upon this basis, it finally discusses the interaction between online dictionaries and external sources like the Internet...

  6. Online marketing

    OpenAIRE

    Zrůst, Daniel

    2013-01-01

    The aim of this thesis is to evaluate pay per click marketing as suitable marketing tool for promotion and distribution of a given product. The paper describes basic vocabulary related to PPC advertising, common metrics, tools used by online marketers, and logic of running PPC campaigns. The paper also tries to quantify impact of Internet on economies. The second part applies the theory to analysis of consumers' conversion path while searching online in common search engines where PPC marketi...

  7. HIV/AIDS and Drug Abuse: Intertwined Epidemics

    Science.gov (United States)

    ... DrugFacts » HIV/AIDS and Drug Abuse: Intertwined Epidemics HIV/AIDS and Drug Abuse: Intertwined Epidemics Email Facebook ... to AIDS, greatly prolonging lives. What Exactly Is HIV/AIDS? HIV stands for human immunodeficiency virus. This ...

  8. A Dirichlet process model for classifying and forecasting epidemic curves

    National Research Council Canada - National Science Library

    Nsoesie, Elaine O; Leman, Scotland C; Marathe, Madhav V

    2014-01-01

    .... Forecasting stochastic processes such as epidemics is challenging since there are several biological, behavioral, and environmental factors that influence the number of cases observed at each point during an epidemic...

  9. Ending U.S. Opioid Abuse Epidemic Will Take Years

    Science.gov (United States)

    ... medlineplus.gov/news/fullstory_167176.html Ending U.S. Opioid Abuse Epidemic Will Take Years: Report Expert panel ... wide-ranging "action plan" to combat the U.S. opioid abuse epidemic warn there's no quick fix. Needed ...

  10. Phylogenetics of the Danish HIV epidemic

    DEFF Research Database (Denmark)

    Audelin, Anne Margrethe; Cowan, Susan A; Obel, Niels

    2013-01-01

    BACKGROUND:: In Denmark 300 new individuals are diagnosed with HIV every year, despite decades of public health campaigns aimed to raise awareness of potential risk behaviour for HIV transmission. It is important to identify the driving forces of the epidemic, to enable more targeted campaigns...

  11. Epidemics of mold poisoning past and present.

    Science.gov (United States)

    Meggs, William J

    2009-01-01

    Molds are ubiquitous throughout the biosphere of planet earth and cause infectious, allergic, and toxic diseases. Toxic diseases arise from exposure to mycotoxins produced by molds. Throughout history, there have been a number of toxic epidemics associated with exposure to mycotoxins. Acute epidemics of ergotism are caused by consumption of grain infested by fungi of the genus Claviceps, which produce the bioactive amine ergotamine that mimics the neurotransmitters norepinephrine, serotonin, and dopamine. Acute aflatoxin outbreaks have occurred from ingestion of corn stored in damp conditions that potentiate growth of the molds of the species Aspergillus. Contemporary construction methods that use cellulose substrates such as fiber board and indoor moisture have caused an outbreak of contaminated buildings with Stachybotrys chartarum, with the extent of health effects still a subject of debate and ongoing research. This article reviews several of the more prominent epidemics and discusses the nature of the toxins. Two diseases that were leading causes of childhood mortality in England in the 1970s and vanished with changing dietary habits, putrid malignant fever, and slow nervous fever were most likely toxic mold epidemics.

  12. The Prescription Opioid Pain Medication Overdose Epidemic

    Centers for Disease Control (CDC) Podcasts

    2016-04-19

    Overdose related to prescription opioids has become an epidemic. This podcast discusses the risks of this type of drug sometimes used to treat pain, and how to protect yourself. .  Created: 4/19/2016 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/19/2016.

  13. Social epidemics in the aftermath of disasters.

    NARCIS (Netherlands)

    IJzermans, C.J.

    2002-01-01

    Issue/problem: After disasters, terrorist attacks and wars social epidemics of medically unexplained physical symptoms/syndromes (ups) are often seen. In modern times people feel more vulnerable and especially under pressure of those incidents, everyday symptoms are interpreted as disease and causal

  14. The epidemic of Athens, 430 - 426 BC

    African Journals Online (AJOL)

    1998-01-01

    Jan 1, 1998 ... evidence, narrows down the many possibilities to epidemic typhus, plague, arboviral disease (e.g. Rift Valley fever) and smallpox. ... reviews have been published}" Instead of attempting to ... personal opinion about the origin of the plague, and the .... It was a previously unknown disease with an explosive.

  15. Social epidemics in the aftermath of disasters.

    NARCIS (Netherlands)

    IJzermans, C.J.

    2002-01-01

    Issue/problem: After disasters, terrorist attacks and wars social epidemics of medically unexplained physical symptoms/syndromes (ups) are often seen. In modern times people feel more vulnerable and especially under pressure of those incidents, everyday symptoms are interpreted as disease and

  16. School Violence, the Media's Phanton Epidemic.

    Science.gov (United States)

    Best, Joel

    2002-01-01

    Argues that public perceptions of an epidemic of school violence are media-induced; asserts that violence in schools declined during the 1990s; supports assertion with evidence from the National School Safety Center; states the estimates of bullying in school are exaggerated. (PKP)

  17. Police Brutality--the New Epidemic

    Science.gov (United States)

    Sandoval, Ruben; Martinez, Douglas R.

    1978-01-01

    Recently, incidents of police abuse against Hispanics have increased so rapidly that the phenomenon has been called an epidemic. Of special concern to Hispanic leaders is the lack of Federal intervention in these police brutality cases. A list of 56 documented cases involving police brutality against Hispanics is included. (Author/NQ)

  18. Nine challenges for deterministic epidemic models

    DEFF Research Database (Denmark)

    Roberts, Mick G; Andreasen, Viggo; Lloyd, Alun;

    2015-01-01

    , infections with time-varying infectivity, and those where superinfection is possible. We then consider the need for advances in spatial epidemic models, and draw attention to the lack of models that explore the relationship between communicable and non-communicable diseases. The final two challenges concern...

  19. Can epidemics be non-communicable?

    DEFF Research Database (Denmark)

    Seeberg, Jens; Meinert, Lotte

    2015-01-01

    This article argues that the concept of communicability that is central to the distinction between communicable diseases (CDs) and noncommunicable diseases (NCDs) is poorly conceptualized. The epidemic spread of NCDs such as diabetes, depression, and eating disorders demonstrates that they are co......This article argues that the concept of communicability that is central to the distinction between communicable diseases (CDs) and noncommunicable diseases (NCDs) is poorly conceptualized. The epidemic spread of NCDs such as diabetes, depression, and eating disorders demonstrates...... that they are communicable, even if they are not infectious. We need to more critically explore how they might be communicable in specific environments. All diseases with epidemic potential, we argue, should be assumed to be commun icable in a broader sense, and that the underlying medical distinction between infectious...... and noninfectious diseases confuses our understanding of NCD epidemics when these categories are treated as synonymous with ‘communicable’ and ‘noncommunicable’ diseases, respectively. The dominant role accorded to the concept of ‘lifestyle’, with its focus on individual responsibility, is part of the problem...

  20. Epidemic and power in imperial Recife

    Directory of Open Access Journals (Sweden)

    Rosilene Gomes Farias

    2016-06-01

    Full Text Available In 1856, during the cholera epidemic that hit Recife, actions were implemented to prevent the disease, which presupposed the social control of the poorest sections of the population. The article discusses how these actions demonstrate the power relations involving public and medical authorities in Recife of the Nineteenth Century.

  1. Mitigating the future impact of Cholera Epidemics

    CSIR Research Space (South Africa)

    Woodborne, S

    2008-11-01

    Full Text Available Cholera epidemics have been analysed using epidemiological models that depend on human-to environment- to-human spread of toxigenic Vibrio cholerae bacteria (Koelle et al. 2004, Koelle et al. 2005). Within such a framework the vulnerable human...

  2. Can epidemics be non-communicable?

    DEFF Research Database (Denmark)

    Seeberg, Jens; Meinert, Lotte

    2015-01-01

    This article argues that the concept of communicability that is central to the distinction between communicable diseases (CDs) and noncommunicable diseases (NCDs) is poorly conceptualized. The epidemic spread of NCDs such as diabetes, depression, and eating disorders demonstrates that they are co...

  3. Epidemic Models for SARS and Measles

    Science.gov (United States)

    Rozema, Edward

    2007-01-01

    Recent events have led to an increased interest in emerging infectious diseases. This article applies various deterministic models to the SARS epidemic of 2003 and a measles outbreak in the Netherlands in 1999-2000. We take a historical approach beginning with the well-known logistic curve and a lesser-known extension popularized by Pearl and Reed…

  4. Social epidemics in the aftermath of disasters.

    NARCIS (Netherlands)

    IJzermans, C.J.

    2002-01-01

    Issue/problem: After disasters, terrorist attacks and wars social epidemics of medically unexplained physical symptoms/syndromes (ups) are often seen. In modern times people feel more vulnerable and especially under pressure of those incidents, everyday symptoms are interpreted as disease and causal

  5. Nursing experience of patients with epidemic hemorrhagic fever

    Directory of Open Access Journals (Sweden)

    Ling-yan ZHANG

    2014-04-01

    Full Text Available Objective: To explore the nursing methods of patients with epidemic hemorrhagic fever. Methods: Through careful nursing, 1 case of patients with epidemic hemorrhagic fever, summed up the experience. Results: Patients with epidemic hemorrhagic fever were 2 days later improved, within 6 months to fully recover. Conclusion: With proper treatment and careful nursing, patients with epidemic hemorrhagic fever are able to fully recover.

  6. Out Online

    DEFF Research Database (Denmark)

    Raun, Tobias

    Trans people are increasingly stepping out of the shadow of pathologization and secretiveness to tell their life stories, share information and to connect with like-minded others, using YouTube as a platform. "Out Online: Trans Self-Representation and Community Building on YouTube" explores...... on the ways in which the video blog (or ’vlog’) as a multimodal medium enables trans people to tell their stories with the use of sound, text, music, and pictures - thus offering new ways to construct and archive bodily changes, and to revise the story endlessly. A groundbreaking study of the intersection...... between trans identity and technology, "Out Online" explores the transformative and therapeutic potential of the video blog as a means by which trans vloggers can emerge and develop online, using the vlog as a site for creation, intervention, community building and resistance. As such, it will appeal...

  7. Online Innovation

    DEFF Research Database (Denmark)

    Vujovic, Sladjana; Ulhøi, John Parm

    2008-01-01

    ways of communicating, cooperating and coordinating during the innovation and product development process. Moreover, it challenges the traditional business model in that it forces the actors involved to shift the focus from the innovation itself to the identification of new supporting services higher...... implications for existing software manufacturers. The paper therefore includes the case of IBM, a company which has successfully integrated this new and more open way of collaboration into its business model. Findings - The paper concludes that online computer-based innovation fundamentally challenges current......  Purpose - The aim of this paper is to investigate the role of online networking during the innovation process, including its role(s) in communication, cooperation and coordination. The paper neither implicitly assumes that online computer-based networking is a prerequisite for the innovation...

  8. Online safety

    CERN Document Server

    Healey, Justin

    2015-01-01

    Australians are increasingly connecting online through computers, mobile phones and other electronic devices to access the internet and social media. In the process, young people in particular are becoming more at risk of being exposed to fraud, identity theft, unauthorised access to personal information, stalking, harassment and exposure to illicit or offensive materials. This book presents a range of cybersafety tips to arm readers with an informed awareness of the risks online and offer advice on how to stay protected. A chapter in the book is specifically dedicated to understanding and dea

  9. Online Communities

    DEFF Research Database (Denmark)

    Sørensen, Henrik; Lassen, Astrid Heidemann; Gorm Hansen, Katrine

    Online Communities” er et medie for brugere og fagfolk, hvor de kan mødes digitalt for at dele erfaringer, og dette kan anvendes som inspiration indenfor Brugerdreven Innovation. Via ”desk research” kan virksomheder opnå adgang til varierende mængder af brugere på en forholdsvist enkelt måde. I...... denne rapport beskrives eksperimentets opbygning, resultater og mulige værdi. Vi håber hermed på at kunne give praktisk indsigt i, hvorledes virksomheder fra byggematerialeindustrien kan agere i online communities....

  10. Epidemic mitigation via awareness propagation in communication networks: the role of time scales

    Science.gov (United States)

    Wang, Huijuan; Chen, Chuyi; Qu, Bo; Li, Daqing; Havlin, Shlomo

    2017-07-01

    The participation of individuals in multi-layer networks allows for feedback between network layers, opening new possibilities to mitigate epidemic spreading. For instance, the spread of a biological disease such as Ebola in a physical contact network may trigger the propagation of the information related to this disease in a communication network, e.g. an online social network. The information propagated in the communication network may increase the awareness of some individuals, resulting in them avoiding contact with their infected neighbors in the physical contact network, which might protect the population from the infection. In this work, we aim to understand how the time scale γ of the information propagation (speed that information is spread and forgotten) in the communication network relative to that of the epidemic spread (speed that an epidemic is spread and cured) in the physical contact network influences such mitigation using awareness information. We begin by proposing a model of the interaction between information propagation and epidemic spread, taking into account the relative time scale γ. We analytically derive the average fraction of infected nodes in the meta-stable state for this model (i) by developing an individual-based mean-field approximation (IBMFA) method and (ii) by extending the microscopic Markov chain approach (MMCA). We show that when the time scale γ of the information spread relative to the epidemic spread is large, our IBMFA approximation is better compared to MMCA near the epidemic threshold, whereas MMCA performs better when the prevalence of the epidemic is high. Furthermore, we find that an optimal mitigation exists that leads to a minimal fraction of infected nodes. The optimal mitigation is achieved at a non-trivial relative time scale γ, which depends on the rate at which an infected individual becomes aware. Contrary to our intuition, information spread too fast in the communication network could reduce the

  11. Epidemic thresholds in a heterogenous population with competing strains

    Institute of Scientific and Technical Information of China (English)

    Wu Qing-Chu; FU Xin-Chu; Yang Meng

    2011-01-01

    Among many epidemic models, one epidemic disease may transmit with the existence of other pathogens or other strains from the same pathogen. In this paper, we consider the case where all of the strains obey the susceptible-infectedsusceptible mechanism and compete with each other at the expense of common susceptible individuals. By using the heterogenous mean-field approach, we discuss the epidemic threshold for one of two strains. We confirm the xistence of epidemic threshold in both finite and infinite populations subject to underlying epidemic transmission. Simulations in the Barabasi-Albert(BA)scale-free networks are in good agreement with the analytical results.

  12. Online 1990.

    Science.gov (United States)

    Goldstein, Morris

    This paper examines the co-existence of online and CD-ROM technologies in terms of their existing pricing structures, marketing strategies, functionality, and future roles. "Fixed Price Unlimited Usage" (FPUU) pricing and flat-rate pricing are discussed as viable alternatives to current pricing practices. In addition, it is argued that the…

  13. Online dictionaries

    DEFF Research Database (Denmark)

    Tarp, Sven

    2012-01-01

    , need, consultation, and data. The article then proceeds to the discussion of some advanced information science techniques that may contribute to the desired individualization. Upon this basis, it finally discusses the interaction between online dictionaries and external sources like the Internet...

  14. Traffic-driven SIR epidemic model on networks

    CERN Document Server

    Pu, Cunlai; Yang, Jian

    2015-01-01

    We propose a novel SIR epidemic model which is driven by the transmission of infection packets in networks. Specifically, infected nodes generate and deliver infection packets causing the spread of the epidemic, while recovered nodes block the delivery of infection packets, and this inhibits the epidemic spreading. The efficient routing protocol governed by a control parameter $\\alpha$ is used in the packet transmission. We obtain the maximum instantaneous population of infected nodes, the maximum population of ever infected nodes, as well as the corresponding optimal $\\alpha$ through simulation. We find that generally more balanced load distribution leads to more intense and wide spread of an epidemic in networks. Increasing either average node degree or homogeneity of degree distribution will facilitate epidemic spreading. When packet generation rate $\\rho$ is small, increasing $\\rho$ favors epidemic spreading. However, when $\\rho$ is large enough, traffic congestion appears which inhibits epidemic spreadin...

  15. Computational algebraic geometry of epidemic models

    Science.gov (United States)

    Rodríguez Vega, Martín.

    2014-06-01

    Computational Algebraic Geometry is applied to the analysis of various epidemic models for Schistosomiasis and Dengue, both, for the case without control measures and for the case where control measures are applied. The models were analyzed using the mathematical software Maple. Explicitly the analysis is performed using Groebner basis, Hilbert dimension and Hilbert polynomials. These computational tools are included automatically in Maple. Each of these models is represented by a system of ordinary differential equations, and for each model the basic reproductive number (R0) is calculated. The effects of the control measures are observed by the changes in the algebraic structure of R0, the changes in Groebner basis, the changes in Hilbert dimension, and the changes in Hilbert polynomials. It is hoped that the results obtained in this paper become of importance for designing control measures against the epidemic diseases described. For future researches it is proposed the use of algebraic epidemiology to analyze models for airborne and waterborne diseases.

  16. Epidemics and vaccination on weighted graphs

    CERN Document Server

    Deijfen, Maria

    2011-01-01

    A Reed-Frost epidemic with inhomogeneous infection probabilities on a graph with prescribed degree distribution is studied. Each edge $(u,v)$ in the graph is equipped with two weights $W_{(u,v)}$ and $W_{(v,u)}$ that represent the (subjective) strength of the connection and determine the probability that $u$ infects $v$ in case $u$ is infected and vice versa. Expressions for the epidemic threshold are derived for i.i.d.\\ weights and for weights that are functions of the degrees. For i.i.d.\\ weights, a variation of the so called acquaintance vaccination strategy is analyzed where vertices are chosen randomly and neighbors of these vertices with large edge weights are vaccinated. This strategy is shown to outperform the strategy where the neighbors are chosen randomly in the sense that the basic reproduction number is smaller for a given vaccination coverage.

  17. Restraining Epidemics by Improving Immunization Strategies

    CERN Document Server

    Schneider, Christian M; Havlin, Shlomo; Herrmann, Hans J

    2011-01-01

    The way diseases spread through social and global transportation networks is crucially determining their risk for humanity. Based on percolation theory we quantitatively analyze the effect of immunization strategies on the spreading of diseases through networks and propose a novel approach to improve their effectiveness. We find that the network's vulnerability to epidemics can be significantly reduced by implementing improved immunization strategies based on high betweenness centrality. We demonstrate this on two real networks, the global flight network, which is known as the most important source of pandemic spreading and a school friendship network. In theses networks, the average probability for a node to get infected is reduced by more than 10% compared to the betweenness centrality method believed to be the most efficient strategy to prevent epidemic spreading.

  18. Eight challenges for network epidemic models

    Directory of Open Access Journals (Sweden)

    Lorenzo Pellis

    2015-03-01

    Full Text Available Networks offer a fertile framework for studying the spread of infection in human and animal populations. However, owing to the inherent high-dimensionality of networks themselves, modelling transmission through networks is mathematically and computationally challenging. Even the simplest network epidemic models present unanswered questions. Attempts to improve the practical usefulness of network models by including realistic features of contact networks and of host–pathogen biology (e.g. waning immunity have made some progress, but robust analytical results remain scarce. A more general theory is needed to understand the impact of network structure on the dynamics and control of infection. Here we identify a set of challenges that provide scope for active research in the field of network epidemic models.

  19. [Epidemics and colonial medicine in West Africa].

    Science.gov (United States)

    Becker, C; Collignon, R

    1998-01-01

    We studied colonial medical practices and health policies in West Africa, which has faced endemics and epidemics that have affected entire societies. We found that attempts to centralize the organization of colonial medicine, which began in the late 19th Century, were limited until the end of World War I. Research and control programs expanded after 1920, concentrating on epidemics, but largely ignoring many major health problems, such as measles, whooping cough and malnutrition, the importance of which were not recognized until after World War II. This appraisal of colonial medicine highlights the difficulties of introducing modern medicine and its ideas into African societies. There have been various social reactions, resulting in the current duality in which traditional and modern medicine coexist.

  20. [The depression epidemic does not exist].

    Science.gov (United States)

    van der Feltz-Cornelis, Christina M

    2009-01-01

    There has been much discussion in the media about the question of the existence of a depression epidemic. This leads on to the questions of whether the social and economic approaches are adequate, and what the alternatives are. The concept of the disease 'depression' can be defined using a medical model, or from a patient's or a societal perspective. From a medical perspective, indeed a depression epidemic has ensued from the increased prosperity and the associated decompression of the mortality rate. Society responded with preventative measures and policies aimed at improving functioning in the workplace. However, patients with a major depressive disorder (MDD) who are eligible for treatment are often not motivated to take it up, or are undertreated. Research is necessary in order to explore what patients think about the identification and treatment of depression. The confusion regarding the concept of depression found in the media, needs to be cleared.

  1. How Clustering Affects Epidemics in Random Networks

    CERN Document Server

    Coupechoux, Emilie

    2012-01-01

    Motivated by the analysis of social networks, we study a model of random networks that has both a given degree distribution and a tunable clustering coefficient. We consider two types of growth processes on these graphs: diffusion and symmetric threshold model. The diffusion process is inspired from epidemic models. It is characterized by an infection probability, each neighbor transmitting the epidemic independently. In the symmetric threshold process, the interactions are still local but the propagation rule is governed by a threshold (that might vary among the different nodes). An interesting example of symmetric threshold process is the contagion process, which is inspired by a simple coordination game played on the network. Both types of processes have been used to model spread of new ideas, technologies, viruses or worms and results have been obtained for random graphs with no clustering. In this paper, we are able to analyze the impact of clustering on the growth processes. While clustering inhibits th...

  2. HIV epidemic in Russia and neighbouring countries

    Directory of Open Access Journals (Sweden)

    Vadim Pokrovskiy

    2014-11-01

    Full Text Available Reports of HIV/AIDS cases attributed to sexual transmission from foreigners were published in the USSR in the mid of 80s. In the initial decade of the epidemic, the subtype B was found in men who have sex with men (MSM population and several non-B subtypes were identified in heterosexual persons. The first case of HIV infection in intravenous drug users (IVDU was reported in 1993 and since then a specific subtype A and its recombinants invaded the intravenous drug users (IVDU populations of the region with the highest rate in Estonia, Russia and Ukraine. The concentrated HIV epidemic in IVDUs is still the main problem in the Eastern Europe; however, the rate of heterosexual transmission is increasing and many evidences of HIV prevalence rise in MSM are published. UNAIDS estimations for the number of HIV-positive persons living in the region range from 980,000 to 1,300,000 but distribution of HIV-cases is uneven and the prevalence rate of HIV infection in separate regions is over 1%. Mass seasonal labour migration from Central Asia and Caucasian republics to Russia transmits HIV to these countries. Prevention programs in the region are limited, and ART coverage is not more than 20% of the total HIV-positive population. The lack of concern about the epidemic, absence of effective national strategies and limited allocated resources are the main barriers to prevention and care in many countries. Local conflicts, rising religiosity and discrimination are adverse factors. The near-term forecast for the epidemic in the region is pessimistic and further international advocacy is needed to improve the situation.

  3. [Late sequelae of epidemic viral meningitis].

    Science.gov (United States)

    Pierzchała, K; Grudzińska, B; Bara, M; Kłosińska, E

    1989-02-01

    In autumn 1982 during an epidemic of meningitis caused by Coxsackie A9 and ECHO4 viruses 36 patients, usually young, were hospitalized. After 3-4 years 22 of them were subjected to control examinations, carrying out medical examination. EEG, ACG, motor nerve conduction velocity measurements and psychological examinations by the tests od Eysenck, Bender-Koppitz and Wechsler. The studied group comprised 14 men and 8 women with mean age 29.8 years.

  4. Genome organization of epidemic Acinetobacter baumannii strains

    Directory of Open Access Journals (Sweden)

    Triassi Maria

    2011-10-01

    Full Text Available Abstract Background Acinetobacter baumannii is an opportunistic pathogen responsible for hospital-acquired infections. A. baumannii epidemics described world-wide were caused by few genotypic clusters of strains. The occurrence of epidemics caused by multi-drug resistant strains assigned to novel genotypes have been reported over the last few years. Results In the present study, we compared whole genome sequences of three A. baumannii strains assigned to genotypes ST2, ST25 and ST78, representative of the most frequent genotypes responsible for epidemics in several Mediterranean hospitals, and four complete genome sequences of A. baumannii strains assigned to genotypes ST1, ST2 and ST77. Comparative genome analysis showed extensive synteny and identified 3068 coding regions which are conserved, at the same chromosomal position, in all A. baumannii genomes. Genome alignments also identified 63 DNA regions, ranging in size from 4 o 126 kb, all defined as genomic islands, which were present in some genomes, but were either missing or replaced by non-homologous DNA sequences in others. Some islands are involved in resistance to drugs and metals, others carry genes encoding surface proteins or enzymes involved in specific metabolic pathways, and others correspond to prophage-like elements. Accessory DNA regions encode 12 to 19% of the potential gene products of the analyzed strains. The analysis of a collection of epidemic A. baumannii strains showed that some islands were restricted to specific genotypes. Conclusion The definition of the genome components of A. baumannii provides a scaffold to rapidly evaluate the genomic organization of novel clinical A. baumannii isolates. Changes in island profiling will be useful in genomic epidemiology of A. baumannii population.

  5. X Syndrome. The epidemic of the XXI century.

    Directory of Open Access Journals (Sweden)

    Mirian Belkis Nápoles

    2013-03-01

    Full Text Available The humanity has always been tied to the emergence of epidemics and pandemics that affect the course of the history, of the development in entire civilizations. In the epidemiologic transition that happened in last century, the control of transmissible illnesses with the progress of the science and the prevention, it brought about the appearance of chronic not transmissible illnesses. The metabolic syndrome (SM also known as Multimetabolic Syndrome or X Syndrome, is only a constellation of factors of risk lipids and not lipids that can appear in sequential or simultaneous form in the same individual. The objective of the present bibliographical review is to mention some relevant aspects destined to know, prevent and treating to the X Syndrome. For the realization of the same one we base on two types of sources: written material and on-line material. We conclude that a primary prevention and an opportune change of the food habits, environmental factors and life styles, would lead to diminishing the appearance of the Metabolic Syndrome. The treatment is accessible to the patient, of low economical cost, of very easy application for the population, and whose finality will be to prevent complications and to diminish the risks of cardiovascular illness.

  6. SARS epidemical forecast research in mathematical model

    Institute of Scientific and Technical Information of China (English)

    DING Guanghong; LIU Chang; GONG Jianqiu; WANG Ling; CHENG Ke; ZHANG Di

    2004-01-01

    The SIJR model, simplified from the SEIJR model, is adopted to analyze the important parameters of the model of SARS epidemic such as the transmission rate, basic reproductive number. And some important parameters are obtained such as the transmission rate by applying this model to analyzing the situation in Hong Kong, Singapore and Canada at the outbreak of SARS. Then forecast of the transmission of SARS is drawn out here by the adjustment of parameters (such as quarantined rate) in the model. It is obvious that inflexion lies on the crunode of the graph, which indicates the big difference in transmission characteristics between the epidemic under control and not under control. This model can also be used in the comparison of the control effectiveness among different regions. The results from this model match well with the actual data in Hong Kong, Singapore and Canada and as a by-product, the index of the effectiveness of control in the later period can be acquired. It offers some quantitative indexes, which may help the further research in epidemic diseases.

  7. Optimal Vaccination For A Probabilistic Epidemic

    Science.gov (United States)

    Yuan, Edwin; Stromberg, Sean; Carlson, Jean

    2014-03-01

    In epidemiology, herd immunity is the well-known idea that by vaccinating a sufficient fraction of a susceptible population, one lowers the basic reproduction number of the pathogen below one, and thereby prevents an epidemic. A natural conclusion from this is that given two identical populations, and enough vaccine to induce herd immunity in only one, we can prevent the greatest number of people from infection by inequitably distributing vaccine to completely protect one population while leaving the other much more relatively susceptible. This heuristic has been verified by simulation of the standard deterministic SIR epidemic. We show, however, that when stochasticity is introduced to the system, or more specifically when there is now a significant probability that an epidemic will not develop independently, it is counter-intuitively optimal to distribute vaccine more equally and not induce herd immunity in either population. There is thus a regime where the purely deterministic SIR model is a poor predictor of the optimal vaccination scheme.

  8. Politicians and Epidemics in the Bible Belt

    Directory of Open Access Journals (Sweden)

    Geurt Henk Spruyt

    2016-07-01

    Full Text Available The Netherlands has a high vaccination coverage, but due to a concentration of people objecting to vaccination on religious grounds in the Bible belt, several polio and measles epidemics have occurred there in the past. This article analyses how and in what way Dutch politicians responded to parents refusing to have their children vaccinated. First, during these epidemics Members of Parliament mainly addressed written questions of a highly technical or procedural nature to the responsible State Secretary or Minister of Public Health. Secondly, the government always requested advice from an advisory body with regard to matters of health after an epidemic. These reports were opposed to mandatory vaccination mainly by using practical arguments. However, by advocating the idea of strengthening the position of minors in public healthcare these reports contributed to legislation codifying the rights of minors concerning public health. The most important rationale behind this response is the complexity of the issue of mandatory vaccination, because different human rights are involved. On the one hand, mandatory vaccination infringes the constitutional rights to the freedom of thought, conscience and religion and encroaches on parental autonomy. On the other hand, children have a right to physical integrity. To find a way out of this unsolvable dilemma, the government and its advisory bodies mainly used practical arguments against mandatory vaccination.

  9. Epidemic model with isolation in multilayer networks

    CERN Document Server

    Zuzek, L G Alvarez; Braunstein, L A

    2014-01-01

    The Susceptible-Infected-Recovered (SIR) model has successfully mimicked the propagation of such airborne diseases as influenza A (H1N1). Although the SIR model has recently been studied in a multilayer networks configuration, in almost all the research the dynamic movement of infected individuals, e.g., how they are often kept in isolation, is disregarded. We study the SIR model in two multilayer networks and use an isolation parameter, indicating time period, to measure the effect of isolating infected individuals from both layers. This isolation reduces the transmission of the disease because the time in which infection can spread is reduced. In this scenario we find that the epidemic threshold increases with the isolation time and the isolation parameter and the impact of the propagation is reduced. We also find that when isolation is total there is a threshold for the isolation parameter above which the disease never becomes an epidemic. We also find that regular epidemic models always overestimate the e...

  10. Connecting the obesity and the narcissism epidemics.

    Science.gov (United States)

    Lemaitre, Bruno

    2016-10-01

    Obesity and metabolic syndromes are major threats to health in both developed and developing countries. This opinion article is a holistic attempt to understand the obesity epidemic, by connecting it to the widespread narcissism in society. The narcissism epidemic refers to an increased prevalence of status-striving individualism and a decreased sense of community, observed in Westerns populations and spreading worldwide. Based on social personality and evolutionary psychology approaches, I speculate that this rise of narcissism underlies a steep social hierarchy resulting in increase of social stress. This social stress markedly affects individuals who are sensitive to social hierarchy dominance due to their personality, yet are relegated at a lower social position. I speculate that over-eating is one major mechanism for coping with this stress, and discuss the possibility that visceral fat may constitute an adaptive behaviour to the lower social hierarchy position, which is perceived as unjust. Connecting the prevalence of obesity to the narcissism epidemic allows for a more thorough examination of factors, which contribute to obesity, which includes early difficult childhood experience, lower rank, and the overall competitive framework of the society. Copyright © 2016 The Author. Published by Elsevier Ltd.. All rights reserved.

  11. Cyanobacteria facilitate parasite epidemics in Daphnia.

    Science.gov (United States)

    Tellenbach, C; Tardent, N; Pomati, F; Keller, B; Hairston, N G; Wolinska, J; Spaak, P

    2016-12-01

    The seasonal dominance of cyanobacteria in the phytoplankton community of lake ecosystems can have severe implications for higher trophic levels. For herbivorous zooplankton such as Daphnia, cyanobacteria have poor nutritional value and some species can produce toxins affecting zooplankton survival and reproduction. Here we present another, hitherto largely unexplored aspect of cyanobacteria, namely that they can increase Daphnia susceptibility to parasites. In a 12-yr monthly time-series analysis of the Daphnia community in Greifensee (Switzerland), we observed that cyanobacteria density correlated significantly with the epidemics of a common gut parasite of Daphnia, Caullerya mesnili, regardless of what cyanobacteria species was present or whether it was colonial or filamentous. The temperature from the previous month also affected the occurrence of Caullerya epidemics, either directly or indirectly by the promotion of cyanobacterial growth. A laboratory experiment confirmed that cyanobacteria increase the susceptibility of Daphnia to Caullerya, and suggested a possible involvement of cyanotoxins or other chemical traits of cyanobacteria in this process. These findings expand our understanding of the consequences of toxic cyanobacterial blooms for lake ecosystems and might be relevant for epidemics experienced by other aquatic species. © 2016 by the Ecological Society of America.

  12. [Fight against epidemics: Austrian prisoners in Troyes].

    Science.gov (United States)

    Hetzel, Géraldine

    2014-01-01

    The victories near Ulm and Elchingen, where the Napoleonic army took 60000 prisoners between 15th and 20th of October 1805, lead to the arrival at Troyes (county "Aube") of nearly 2000 Austrian soldiers to be held inside former monasteries among whose, mainly the Jacobinians casern where more than half of them stayed. At the beginning of 1806, the government sent the epidemics medical practitioner Dr Desgenettes on an inspection tour to control the state of health of the populations of places where foreign prisoners were held, which lead him through several counties of the North-eastern part of France, where he surveyed several diseases ranging from all kinds offevers up to dysentery, scabies or gangrenes. With the means of acid fumigations invented by the chemist Guyton Morveau from Dijon, the authorities took care of combating and preventing the epidemics in the caserns. As soon as October 1805, the epidemics medical practitioner Dr Pigeotte from Troyes wrote to the county governor his observations recommending a better diet, airing of the rooms and also calls to take some exercise. All these precepts showed an astonishing modernity.

  13. Politicians and Epidemics in the Bible Belt

    Directory of Open Access Journals (Sweden)

    Geurt Henk Spruyt

    2016-07-01

    Full Text Available The Netherlands has a high vaccination coverage, but due to a concentration of people objecting to vaccination on religious grounds in the Bible belt, several polio and measles epidemics have occurred there in the past. This article analyses how and in what way Dutch politicians responded to parents refusing to have their children vaccinated. First, during these epidemics Members of Parliament mainly addressed written questions of a highly technical or procedural nature to the responsible State Secretary or Minister of Public Health. Secondly, the government always requested advice from an advisory body with regard to matters of health after an epidemic. These reports were opposed to mandatory vaccination mainly by using practical arguments. However, by advocating the idea of strengthening the position of minors in public healthcare these reports contributed to legislation codifying the rights of minors concerning public health. The most important rationale behind this response is the complexity of the issue of mandatory vaccination, because different human rights are involved. On the one hand, mandatory vaccination infringes the constitutional rights to the freedom of thought, conscience and religion and encroaches on parental autonomy. On the other hand, children have a right to physical integrity. To find a way out of this unsolvable dilemma, the government and its advisory bodies mainly used practical arguments against mandatory vaccination.

  14. Distribution of carbapenem resistance determinants among epidemic and non-epidemic types of Acinetobacter species in Japan.

    Science.gov (United States)

    Matsui, Mari; Suzuki, Satowa; Yamane, Kunikazu; Suzuki, Masato; Konda, Toshifumi; Arakawa, Yoshichika; Shibayama, Keigo

    2014-06-01

    We performed a comparative molecular analysis on three types of clinically isolated Acinetobacter spp.: epidemic sequence types (STs) of Acinetobacter baumannii (epidemic ST-AB), non-epidemic sequence types of A. baumannii (non-epidemic ST-AB) and non-baumannii Acinetobacter spp. A total of 87 isolates - 46 A. baumannii, 25 A. pittii and 16 A. nosocomialis - from 43 hospitals were analysed. Of these, 31 A. baumannii isolates were ST1 or ST2 according to the Pasteur Institute multilocus sequence typing scheme and were defined as epidemic ST-AB. The other 15 A. baumannii isolates were defined as non-epidemic ST-AB. The epidemic ST-AB isolates harboured the blaOXA-23-like gene or had an ISAba1 element upstream of blaOXA-51-like, or both, whereas non-epidemic ST-AB and non-baumannii Acinetobacter spp. isolates harboured blaOXA-58-like or metallo-β-lactamase genes, or both. The proportion of multidrug-resistant isolates was significantly higher in the epidemic ST-AB isolates (48 %) than that in the other types of Acinetobacter isolates (5 %) (PAcinetobacter spp. isolates than with epidemic ST-AB isolates, regardless of bacterial species. In addition, this study revealed that, even in Japan, where IMP-type metallo-β-lactamase producers are endemic, epidemic ST-AB harbouring blaIMP have not yet emerged.

  15. Memory effects on epidemic evolution: The susceptible-infected-recovered epidemic model

    Science.gov (United States)

    Saeedian, M.; Khalighi, M.; Azimi-Tafreshi, N.; Jafari, G. R.; Ausloos, M.

    2017-02-01

    Memory has a great impact on the evolution of every process related to human societies. Among them, the evolution of an epidemic is directly related to the individuals' experiences. Indeed, any real epidemic process is clearly sustained by a non-Markovian dynamics: memory effects play an essential role in the spreading of diseases. Including memory effects in the susceptible-infected-recovered (SIR) epidemic model seems very appropriate for such an investigation. Thus, the memory prone SIR model dynamics is investigated using fractional derivatives. The decay of long-range memory, taken as a power-law function, is directly controlled by the order of the fractional derivatives in the corresponding nonlinear fractional differential evolution equations. Here we assume "fully mixed" approximation and show that the epidemic threshold is shifted to higher values than those for the memoryless system, depending on this memory "length" decay exponent. We also consider the SIR model on structured networks and study the effect of topology on threshold points in a non-Markovian dynamics. Furthermore, the lack of access to the precise information about the initial conditions or the past events plays a very relevant role in the correct estimation or prediction of the epidemic evolution. Such a "constraint" is analyzed and discussed.

  16. Accurate estimation of influenza epidemics using Google search data via ARGO.

    Science.gov (United States)

    Yang, Shihao; Santillana, Mauricio; Kou, S C

    2015-11-24

    Accurate real-time tracking of influenza outbreaks helps public health officials make timely and meaningful decisions that could save lives. We propose an influenza tracking model, ARGO (AutoRegression with GOogle search data), that uses publicly available online search data. In addition to having a rigorous statistical foundation, ARGO outperforms all previously available Google-search-based tracking models, including the latest version of Google Flu Trends, even though it uses only low-quality search data as input from publicly available Google Trends and Google Correlate websites. ARGO not only incorporates the seasonality in influenza epidemics but also captures changes in people's online search behavior over time. ARGO is also flexible, self-correcting, robust, and scalable, making it a potentially powerful tool that can be used for real-time tracking of other social events at multiple temporal and spatial resolutions.

  17. Euroscepticism Online

    DEFF Research Database (Denmark)

    Dutceac Segesten, Anamaria; Bossetta Jr, Michael Joseph

    -criticism between Sweden and Denmark? Methodologically we combine quantitative and qualitative content analysis of the forum discussions pertaining to the EU critique taking place on the two platforms respectively. Our focus is thus not on the republished content originated in traditional media channels...... states, leading to numerous street protests. The internet is another site where EU contestation takes place.In the present paper we propose to compare two online platform consisting of user-generated content, where the exchange of ideas and opinions is unfiltered and largely unmoderated. Flashback...... is the leading online discussion forum in Sweden and one of the most popular sites of interaction for those euroskeptic voices coming from the right side of the political spectrum. 180grader is its Danish equivalent. Our research question is: Are there any differences in the discourse surrounding EU...

  18. Euroscepticism Online

    DEFF Research Database (Denmark)

    Dutceac Segesten, Anamaria; Bossetta Jr, Michael Joseph

    -criticism between Sweden and Denmark? Methodologically we combine quantitative and qualitative content analysis of the forum discussions pertaining to the EU critique taking place on the two platforms respectively. Our focus is thus not on the republished content originated in traditional media channels...... states, leading to numerous street protests. The internet is another site where EU contestation takes place.In the present paper we propose to compare two online platform consisting of user-generated content, where the exchange of ideas and opinions is unfiltered and largely unmoderated. Flashback...... and nationalism as the two poles on a continuum of attitudes coming out of the discourses. We discuss finally the consequences of the expected Swedish-Danish divergence of online debate content for the idea of a unified European public sphere....

  19. Online kinship

    DEFF Research Database (Denmark)

    Andreassen, Rikke

    2016-01-01

    The article shows how the technology of social media sites facilitates new kinds of kinship. It ana-lyzes how ‘donor families’ – i.e., families in which the children are conceived via sperm and/or egg donations – negotiate kinship, family formations and gender when connecting with each other online....... Family formation and parenting are closely connected with gender and gender norms, and online donor families, therefore, offer an opportunity for understanding gender and gender for-mations in contemporary times and contemporary media. By analyzing commentary threads of a Facebook group connecting donor...... families as well as interviews with users of this Facebook group, the article shows how the affordances of social media, especially the Facebook application for smart phones, are central to the formation and maintenance of new kinship relations. Furthermore, the article illustrates how conventional...

  20. Climate Regimes, El Nino-Southern Oscillation and Konzo Epidemics

    Directory of Open Access Journals (Sweden)

    Olusegun Steven Ayodele Oluwole

    2015-06-01

    Full Text Available Epidemics of konzo have occurred during severe droughts in parts of east, central, and southern Africa since the 1920s. Occurrence is attributed to exposure to cyanide from poorly processed cassava foods, the sole source of calories when other food crops fail. El Nino, the warm phase of the El Nino-Southern Oscillation (ENSO, induces severe droughts in the geographical areas of Africa where epidemics of konzo occur. Climate regimes are determined by modes of Pacific Decadal Oscillation, which modulates the ENSO. Study was done to determine the relationship of konzo epidemics to climate regimes and phases of ENSO, and to propose a model to explain while konzo epidemics do not occur in all drought affected areas. Data of all konzo epidemics in the past century and in DR Congo from 1974–1996, and indices of ENSO and PDO from 1915 to 2014 were obtained. Konzo epidemics were mapped to phases of ENSO and PDO. Wavelet spectral and wavelet spectral coherence analysis of climate indices and konzo epidemics were done. All konzo epidemics of the past century occurred during warm climate regimes. Of 19 warm phases of ENSO from 1974–1996 in DR Congo, 17 were coupled to konzo epidemics, while of 4 cold phases of ENSO, 1was coupled to konzo epidemic, odds ratio 26 (95 % CI, 2–378. Global spectral of ENSO and konzo showed dominant periodicity of 5 years, while spectograms showed significant periodicities and coherence between 3–6 years. Spatial distribution of konzo is restricted to the area of maximal impact of El Nino on precipitation in Africa. El Nino is the underlying cause of konzo epidemics. Control of konzo epidemics requires management of the impact of El Nino on agriculture in areas where the population depends on cassava as sole source of calories during droughts. There is the need to develop forecast models of changes in cassava production to predict likely periods of konzo epidemics.

  1. Epidemic and Non-Epidemic Hot Spots of Malaria Transmission Occur in Indigenous Comarcas of Panama

    Science.gov (United States)

    Dutari, Larissa C.; Rovira, Jose R.; Sucupira, Izis M. C.; Póvoa, Marinete M.; Conn, Jan E.; Loaiza, Jose R.

    2016-01-01

    From 2002–2005, Panama experienced a malaria epidemic that has been associated with El Niño Southern Oscillation weather patterns, decreased funding for malaria control, and landscape modification. Case numbers quickly decreased afterward, and Panama is now in the pre-elimination stage of malaria eradication. To achieve this new goal, the characterization of epidemiological risk factors, foci of transmission, and important anopheline vectors is needed. Of the 24,681 reported cases in these analyses (2000–2014), ~62% occurred in epidemic years and ~44% in indigenous comarcas (5.9% of Panama’s population). Sub-analyses comparing overall numbers of cases in epidemic and non-epidemic years identified females, comarcas and some 5-year age categories as those disproportionately affected by malaria during epidemic years. Annual parasites indices (APIs; number of cases per 1,000 persons) for Plasmodium vivax were higher in comarcas compared to provinces for all study years, though P. falciparum APIs were only higher in comarcas during epidemic years. Interestingly, two comarcas report increasing numbers of cases annually, despite national annual decreases. Inclusion of these comarcas within identified foci of malaria transmission confirmed their roles in continued transmission. Comparison of species distribution models for two important anophelines with Plasmodium case distribution suggest An. albimanus is the primary malaria vector in Panama, confirmed by identification of nine P. vivax-infected specimen pools. Future malaria eradication strategies in Panama should focus on indigenous comarcas and include both active surveillance for cases and comprehensive anopheline vector surveys. PMID:27182773

  2. An epidemic model for the future progression of the current Haiti cholera epidemic

    Science.gov (United States)

    Bertuzzo, E.; Mari, L.; Righetto, L.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2012-04-01

    As a major cholera epidemic progresses in Haiti, and the figures of the infection, up to December 2011, climb to 522,000 cases and 7,000 deaths, the development of general models to track and predict the evolution of the outbreak, so as to guide the allocation of medical supplies and staff, is gaining notable urgency. We propose here a spatially explicit epidemic model that accounts for the dynamics of susceptible and infected individuals as well as the redistribution of Vibrio cholera, the causative agent of the disease, among different human communities. In particular, we model two spreading pathways: the advection of pathogens through hydrologic connections and the dissemination due to human mobility described by means of a gravity-like model. To this end the country has been divided into hydrologic units based on drainage directions derived from a digital terrain model. Moreover the population of each unit has been estimated from census data downscaled to 1 km x 1 km resolution via remotely sensed geomorphological information (LandScan project). The model directly accounts for the role of rainfall patterns in driving the seasonality of cholera outbreaks. The two main outbreaks in fact occurred during the rainy seasons (October and May) when extensive floodings severely worsened the sanitation conditions and, in turn, raised the risk of infection. The model capability to reproduce the spatiotemporal features of the epidemic up to date grants robustness to the foreseen future development. To this end, we generate realistic scenario of future precipitation in order to forecast possible epidemic paths up to the end of the 2013. In this context, the duration of acquired immunity, a hotly debated topic in the scientific community, emerges as a controlling factor for progression of the epidemic in the near future. The framework presented here can straightforwardly be used to evaluate the effectiveness of alternative intervention strategies like mass vaccinations

  3. Epidemic and Non-Epidemic Hot Spots of Malaria Transmission Occur in Indigenous Comarcas of Panama.

    Directory of Open Access Journals (Sweden)

    William Lainhart

    2016-05-01

    Full Text Available From 2002-2005, Panama experienced a malaria epidemic that has been associated with El Niño Southern Oscillation weather patterns, decreased funding for malaria control, and landscape modification. Case numbers quickly decreased afterward, and Panama is now in the pre-elimination stage of malaria eradication. To achieve this new goal, the characterization of epidemiological risk factors, foci of transmission, and important anopheline vectors is needed. Of the 24,681 reported cases in these analyses (2000-2014, ~62% occurred in epidemic years and ~44% in indigenous comarcas (5.9% of Panama's population. Sub-analyses comparing overall numbers of cases in epidemic and non-epidemic years identified females, comarcas and some 5-year age categories as those disproportionately affected by malaria during epidemic years. Annual parasites indices (APIs; number of cases per 1,000 persons for Plasmodium vivax were higher in comarcas compared to provinces for all study years, though P. falciparum APIs were only higher in comarcas during epidemic years. Interestingly, two comarcas report increasing numbers of cases annually, despite national annual decreases. Inclusion of these comarcas within identified foci of malaria transmission confirmed their roles in continued transmission. Comparison of species distribution models for two important anophelines with Plasmodium case distribution suggest An. albimanus is the primary malaria vector in Panama, confirmed by identification of nine P. vivax-infected specimen pools. Future malaria eradication strategies in Panama should focus on indigenous comarcas and include both active surveillance for cases and comprehensive anopheline vector surveys.

  4. Event history analysis of dengue fever epidemic and inter-epidemic spells in Barbados, Brazil, and Thailand.

    Science.gov (United States)

    Parker, Daniel; Holman, Darryl

    2012-11-01

    This study investigated meteorological and demographic factors affecting the length of dengue fever epidemics and the length of time between epidemics in Barbados, Brazil, and Thailand. Region-specific meteorological and demographic data were collected for 104 sites from public sources. Fixed effects piecewise logistic event history analysis was used to quantify the effects of time-varying covariates on the duration of inter-epidemic spells and for the duration of epidemics. Mean monthly temperature was the most important factor affecting the duration of both inter-epidemic spells (β=0.543; confidence interval (CI) 0.4954, 0.5906) and epidemic spells (β=-0.648; CI -0.7553, -0.5405). Drought conditions increased the time between epidemics. Increased temperature hastened the onset of an epidemic, and during an epidemic, higher mean temperature increased the duration of the epidemic. By using a duration analysis, this study offers a novel approach for investigating the dynamics of dengue fever epidemiology. Furthermore, these results offer new insights into prior findings of a correlation between temperature and the geographic range and vector efficiency of dengue fever. Copyright © 2012 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  5. Resilience of epidemics for SIS model on networks

    Science.gov (United States)

    Lu, Dan; Yang, Shunkun; Zhang, Jiaquan; Wang, Huijuan; Li, Daqing

    2017-08-01

    Epidemic propagation on complex networks has been widely investigated, mostly with invariant parameters. However, the process of epidemic propagation is not always constant. Epidemics can be affected by various perturbations and may bounce back to its original state, which is considered resilient. Here, we study the resilience of epidemics on networks, by introducing a different infection rate λ2 during SIS (susceptible-infected-susceptible) epidemic propagation to model perturbations (control state), whereas the infection rate is λ1 in the rest of time. Noticing that when λ1 is below λc, there is no resilience in the SIS model. Through simulations and theoretical analysis, we find that even for λ2 resilience, i.e., cdmax, seems to be predicted by the diameter (d) of the underlying network, with the quantitative relation cdmax ˜ dα. Our findings can help to design a better mitigation strategy for epidemics.

  6. Epidemic Spreading in Contact Networks Based on Exposure Level

    Institute of Scientific and Technical Information of China (English)

    DUAN Wen-Qi; CHEN Zhong; LIU Zeng-Rong

    2006-01-01

    @@ Most epidemic models for the spread of diseases in contact networks take the assumption of the infected probability of a susceptible agent dependent on its absolute number of infectious neighbours. We introduce a new epidemic model in which the infected probability of a susceptible agent in contact networks depends not on its degree but on its exposure level. We find that effective average infection rate (λ) (i.e., the average number of infections produced by a single contact between infected individuals and susceptible individuals) has an epidemic threshold (λ)c = 1, which is related to recovery rate, epidemic mechanisms and topology of contact network. Furthermore,we show the dominating importance of epidemic mechanisms in determining epidemic patterns and discussed the implications of our model for infection control policy.

  7. Porcine epidemic diarrhea virus: current insights

    Directory of Open Access Journals (Sweden)

    Lv C

    2016-05-01

    Full Text Available Chaochao Lv,1,* Yan Xiao,1,* Xiangdong Li,1 Kegong Tian,1,2 1National Research Center for Veterinary Medicine, Luoyang, People's Republic of China; 2College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, People's Republic of China *These authors contributed equally to this review Abstract: Porcine epidemic diarrhea virus (PEDV, an enveloped, single-stranded, positive-sense RNA virus belonging to the genus Alphacoronavirus in the family Coronaviridae, can infect pigs of all ages and causes acute and watery diarrhea, vomiting, dehydration, and high mortality in neonatal piglets. This disease was first observed in England in 1971 and was subsequently reported in many swine-producing countries in Europe and Asia. In contrast to the situation in Europe, the disease has remained a major cause of diarrhea outbreaks on swine farms in Asia. Since late 2010, severe porcine epidemic diarrhea (PED epizootics caused by new variants have been affecting pigs in the People's Republic of China, resulting in substantial economic losses. In April 2013, PEDV was identified for the first time in the United States and resulted in the estimated death of over seven million piglets during a 1-year epidemic. Nowadays, it has spread into North and South America, Asia, and Europe, causing significant economic problems worldwide. More studies have been conducted in PEDV research, and the number of scientific literatures published during the last 5 years has exceeded the total of that in the past several decades. This review focuses on the current understanding of the etiology, molecular epidemiology, transmission, diagnosis, and pathogenesis of PEDV, as well as the vaccine to prevent PEDV infection. Keywords: PEDV, molecular epidemiology, transmission, diagnosis, pathogenesis, immune response, vaccine

  8. Drought and Epidemic Typhus, Central Mexico, 1655–1918

    OpenAIRE

    Burns, Jordan N.; Acuna-Soto, Rudofo; David W. Stahle

    2014-01-01

    Epidemic typhus is an infectious disease caused by the bacterium Rickettsia prowazekii and transmitted by body lice (Pediculus humanus corporis). This disease occurs where conditions are crowded and unsanitary. This disease accompanied war, famine, and poverty for centuries. Historical and proxy climate data indicate that drought was a major factor in the development of typhus epidemics in Mexico during 1655–1918. Evidence was found for 22 large typhus epidemics in central Mexico, and tree-ri...

  9. A dynamic epidemic control model on uncorrelated complex networks

    Institute of Scientific and Technical Information of China (English)

    Pei Wei-Dong; Chen Zeng-Qiang; Yuan Zhu-Zhi

    2008-01-01

    In this paper,a dynamic epidemic control model on the uncorrelated complex networks is proposed.By means of theoretical analysis,we found that the new model has a similar epidemic threshold as that of the susceptible-infectedrecovered (SIR) model on the above networks,but it can reduce the prevalence of the infected individuals remarkably.This result may help us understand epidemic spreading phenomena on real networks and design appropriate strategies to control infections.

  10. Epidemic Dynamics with Feedback Mechanism in Exponential Networks

    Institute of Scientific and Technical Information of China (English)

    LIU Zi-Ran; YAN Jia-Ren; ZHANG Jian-Guo; WANG Li

    2006-01-01

    @@ We introduce a feedback mechanism to study the spreading of an epidemic by analytical methods and large scale simulations in exponential networks. It is found that introducing the feedback mechanism can reduce the density of infected individuals. Furthermore, it does not change the epidemic threshold (critical point) λc. These results can help us to understand epidemic spreading phenomena on social networks more practically and design appropriate strategies to control social infections.

  11. Reemergence of Enterovirus 71 Epidemic in Northern Taiwan, 2012

    OpenAIRE

    Shu-Ting Luo; Pai-Shan Chiang; Wan-Yu Chung; Min-Yuan Chia; Kuo-Chien Tsao; Ying-Hsiang Wang; Tzou-Yien Lin; Min-Shi Lee

    2015-01-01

    Background Enterovirus 71 (EV71) belongs to picornavirus family and could be classified phylogenetically into three major genogroups (A, B and C) including 11 genotypes (A, B1-B5 and C1-C5). Since 1997, EV71 has caused large-scale of epidemics with neurological complications in Asian children. In Taiwan, nationwide EV71 epidemics with different predominant genotypes have occurred cyclically since 1998. A nationwide EV71 epidemic occurred again in 2012. We conducted genetic and antigenic chara...

  12. CHEMICAL VERSUS SERUM TREATMENT OF EPIDEMIC MENINGITIS.

    Science.gov (United States)

    Flexner, S; Amoss, H L

    1916-05-01

    Claims of efficiency have been made at two widely separated periods for the chemical treatment of epidemic meningitis, in the first instance for lysol and in the second for protargol. The use of lysol was long since abandoned; the recommendation for protargol is based on a single series of cases, small in number. Because of the variable severity of epidemics of meningitis, small reliance can be placed on results of treatment limited in extent to small numbers of cases and to one locality. A more uniform and accurate measure of the value of a method of treatment is provided by animals infected experimentally with pathogenic cultures of meningococci. Young guinea pigs respond in a definite manner to intraperitoneal inoculation of virulent meningococci. Neither protargol nor lysol proved to have any curative action on the experimental infection thus produced in these animals. Monkeys respond in a characteristic manner to the inoculation of virulent cultures into the subarachnoid space. Protargol displayed no curative action on the experimental infection thus produced in these animals. On the contrary, both lysol and protargol exert antileukotactic and antiphagocytic effects, and are also potent protoplasmic poisons, and the leukocytes with which they come in contact are injured and made to degenerate. According to the extent to which these harmful properties are exerted, the chemicals promote the advance rather than restrain the progress of meningococcic infection. Recovery from meningococcic infection in man and animals is accomplished chiefly through the process of phagocytosis. The specific antiserum acts curatively by increasing the emigration of leukocytes, by promoting phagocytosis directly, and by agglutinating the meningococci, and also by neutralizing endotoxin. Any means which interfere with and reduce these essential processes retard or prevent recovery. Both lysol and protargol interfere with and diminish the emigration of leukocytes and the phagocytosis

  13. Generalized epidemic process on modular networks

    CERN Document Server

    Chung, Kihong; Kim, Daniel; Ha, Meesoon; Jeong, Hawoong

    2013-01-01

    Social reinforcement and modular structure are two salient features observed in the spreading of behavior through social contacts. In order to investigate the interplay between these two features, we study the generalized epidemic process on modular networks with equal-sized finite communities and adjustable modularity. Using the analytical approach originally applied to clique-based random networks, we show that the system exhibits a bond-percolation type continuous phase transition for weak social reinforcement, whereas a discontinuous phase transition occurs for sufficiently strong social reinforcement. Our findings are numerically verified by the finite-size scaling analysis for critical behaviors and the bimodality coefficient test for discontinuous transitions.

  14. Improving epidemic control strategies by extended detection

    Science.gov (United States)

    Karp, Paweł; Dybiec, Bartłomiej; Kleczkowski, Adam

    2014-11-01

    Majority of epidemics eradication programs work in preventive responsive way. The lack of exact information about epidemiological status of individuals makes responsive actions less efficient. Here, we demonstrate that additional tests can significantly increase the efficiency of "blind" treatment (vaccination or culling). Eradication strategy consisting of "blind" treatment in very limited local neighborhood supplemented by extra tests in a little bit larger neighborhood is able to prevent invasion of even highly infectious diseases and to achieve this at a cost lower than for the "blind" strategy. The effectiveness of the extended strategy depends on such parameters as the test efficiency and test cost.

  15. Effects of superspreaders in spread of epidemic

    Science.gov (United States)

    Fujie, Ryo; Odagaki, Takashi

    2007-02-01

    Within the standard SIR model with spatial structure, we propose two models for the superspreader. In one model, superspreaders have intrinsically strong infectiousness. In other model, they have many social connections. By Monte Carlo simulation, we obtain the percolation probability, the propagation speed, the epidemic curve, the distribution of secondary infected and the propagation path as functions of population and the density of superspreaders. By comparing the results with the data of SARS in Singapore 2003, we conclude that the latter model can explain the observation.

  16. Gorging Online

    Institute of Scientific and Technical Information of China (English)

    Pride; Phiri

    2011-01-01

    MY introduction to social networking came in my first year of university.I had never been online before then nor used a computer extensively. The archaic machines at my high school had been good for a few rounds of solitaire and nothing more.Growing up in Zimbabwe at the turn of the century where even cell phones were a novelty,the Internet was just something you read about and then added to the list of things that while nice to have,didn’t really factor into everyday life.

  17. Epidemics: Lessons from the past and current patterns of response

    Science.gov (United States)

    Martin, Paul

    2008-09-01

    Hippocrates gave the term 'epidemic' its medical meaning. From antiquity to modern times, the meaning of the word epidemic has continued to evolve. Over the centuries, researchers have reached an understanding of the varying aspects of epidemics and have tried to combat them. The role played by travel, trade, and human exchanges in the propagation of epidemic infectious diseases has been understood. In 1948, the World Health Organization was created and given the task of advancing ways of combating epidemics. An early warning system to combat epidemics has been implemented by the WHO. The Global Outbreak Alert and Response Network (GOARN) is collaboration between existing institutions and networks that pool their human and technical resources to fight outbreaks. Avian influenza constitutes currently the most deadly epidemic threat, with fears that it could rapidly reach pandemic proportions and put several thousands of lives in jeopardy. Thanks to the WHO's support, most of the world's countries have mobilised and implemented an 'Action Plan for Pandemic Influenza'. As a result, most outbreaks of the H5N1 avian flu virus have so far been speedily contained. Cases of dengue virus introduction in countries possessing every circumstance required for its epidemic spread provide another example pertinent to the prevention of epidemics caused by vector-borne pathogens.

  18. Abia State HIV epidemic and response: challenges and prospects.

    Science.gov (United States)

    Onyeonoro, Ugochukwu Uchenna; Emelumadu, Obiageli Fidelia; Nwamoh, Uche Ngozi; Ukegbu, Andrew Ugwunna; Okafor, Godwin Oc

    2014-11-13

    Since the first seroprevalence survey in 1999, the HIV prevalence in Abia State has increased from 1.8% to 7.3% in 2010. The state is currently experiencing a generalized epidemic, with most transmission occurring through heterosexual low-risk sex. Drivers of the epidemic include low knowledge of HIV prevention, low risk perception, predominantly male factor-driven risky sexual behavior, and low condom use. This study reviewed the state HIV epidemic trend in relation to response, sought to identify the gaps between the epidemic and response, and recommended measures to strengthen the state response.

  19. Untangling the Interplay between Epidemic Spread and Transmission Network Dynamics.

    Directory of Open Access Journals (Sweden)

    Christel Kamp

    Full Text Available The epidemic spread of infectious diseases is ubiquitous and often has a considerable impact on public health and economic wealth. The large variability in the spatio-temporal patterns of epidemics prohibits simple interventions and requires a detailed analysis of each epidemic with respect to its infectious agent and the corresponding routes of transmission. To facilitate this analysis, we introduce a mathematical framework which links epidemic patterns to the topology and dynamics of the underlying transmission network. The evolution, both in disease prevalence and transmission network topology, is derived from a closed set of partial differential equations for infections without allowing for recovery. The predictions are in excellent agreement with complementarily conducted agent-based simulations. The capacity of this new method is demonstrated in several case studies on HIV epidemics in synthetic populations: it allows us to monitor the evolution of contact behavior among healthy and infected individuals and the contributions of different disease stages to the spreading of the epidemic. This gives both direction to and a test bed for targeted intervention strategies for epidemic control. In conclusion, this mathematical framework provides a capable toolbox for the analysis of epidemics from first principles. This allows for fast, in silico modeling--and manipulation--of epidemics and is especially powerful if complemented with adequate empirical data for parameterization.

  20. Effects of local and global network connectivity on synergistic epidemics

    CERN Document Server

    Broder-Rodgers, David; Taraskin, Sergei N

    2015-01-01

    The effects of local and global connectivity on the spread of synergistic susceptible-infected-removed epidemics were studied in lattice models with infinite- and finite-range rewiring (small-world and small-world-like models). Several effects were found numerically and supported analytically within a simple model: (i) rewiring enhanced resilience to epidemics with strong constructive synergy on networks with high local connectivity; (ii) rewiring enhanced spread of epidemics with destructive or weak constructive synergy on networks with arbitrary local connectivity; (iii) rewiring enhanced spread of epidemics, independent of synergy, in networks with low local connectivity.

  1. Collective versus hub activation of epidemic phases on networks

    CERN Document Server

    Ferreira, Silvio C; Pastor-Satorras, Romualdo

    2015-01-01

    We consider a general criterion to discern the nature of the threshold in epidemic models on scale-free (SF) networks. Comparing the epidemic lifespan of the nodes with largest degrees with the infection time between them, we propose a general dual scenario, in which the epidemic transition is either ruled by a hub activation process, leading to a null threshold in the thermodynamic limit, or given by a collective activation process, corresponding to a standard phase transition with a finite threshold. We validate the proposed criterion applying it different to epidemic models, with waning immunity or heterogeneous infection rates.

  2. Emergence of Strange Spatial Pattern in a Spatial Epidemic Model

    Institute of Scientific and Technical Information of China (English)

    SUN Gui-Quan; JIN Zhen; LIU Quan-Xing; LI Li

    2008-01-01

    Pattern formation of a spatial epidemic model with nonlinear incidence rate kI2 S/ (1 + αI2) is investigated. Our results show that strange spatial dynamics, i.e., filament-like pattern, can be obtained by both mathematical analysis and numerical simulation, which are different from the previous results in the spatial epidemic model such as stripe-like or spotted or coexistence of both pattern and so on. The obtained results well extend the finding of pattern formation in the epidemic model and may well explain the distribution of the infected of some epidemic.

  3. Heterogeneous Epidemic Model for Assessing Data Dissemination in Opportunistic Networks

    DEFF Research Database (Denmark)

    Rozanova, Liudmila; Alekseev, Vadim; Temerev, Alexander

    2014-01-01

    In this paper we apply a susceptible-infected-susceptible (SIS) epidemic model to analyse data dissemination in opportunistic networks with heterogeneous setting of transmission parameters, as established in author's previous paper? . We obtained the estimation of the final epidemic size assuming...... that amount of data transferred between network nodes possesses a Pareto distribution, implying scale-free properties. In this context, more heterogeneity in susceptibility means the less severe epidemic progression, and, on the contrary, more heterogeneity in infectivity leads to more severe epidemics...

  4. Detection of Severe Respiratory Disease Epidemic Outbreaks by CUSUM-Based Overcrowd-Severe-Respiratory-Disease-Index Model

    Directory of Open Access Journals (Sweden)

    Carlos Polanco

    2013-01-01

    Full Text Available A severe respiratory disease epidemic outbreak correlates with a high demand of specific supplies and specialized personnel to hold it back in a wide region or set of regions; these supplies would be beds, storage areas, hemodynamic monitors, and mechanical ventilators, as well as physicians, respiratory technicians, and specialized nurses. We describe an online cumulative sum based model named Overcrowd-Severe-Respiratory-Disease-Index based on the Modified Overcrowd Index that simultaneously monitors and informs the demand of those supplies and personnel in a healthcare network generating early warnings of severe respiratory disease epidemic outbreaks through the interpretation of such variables. A post hoc historical archive is generated, helping physicians in charge to improve the transit and future allocation of supplies in the entire hospital network during the outbreak. The model was thoroughly verified in a virtual scenario, generating multiple epidemic outbreaks in a 6-year span for a 13-hospital network. When it was superimposed over the H1N1 influenza outbreak census (2008–2010 taken by the National Institute of Medical Sciences and Nutrition Salvador Zubiran in Mexico City, it showed that it is an effective algorithm to notify early warnings of severe respiratory disease epidemic outbreaks with a minimal rate of false alerts.

  5. Detection of severe respiratory disease epidemic outbreaks by CUSUM-based overcrowd-severe-respiratory-disease-index model.

    Science.gov (United States)

    Polanco, Carlos; Castañón-González, Jorge Alberto; Macías, Alejandro E; Samaniego, José Lino; Buhse, Thomas; Villanueva-Martínez, Sebastián

    2013-01-01

    A severe respiratory disease epidemic outbreak correlates with a high demand of specific supplies and specialized personnel to hold it back in a wide region or set of regions; these supplies would be beds, storage areas, hemodynamic monitors, and mechanical ventilators, as well as physicians, respiratory technicians, and specialized nurses. We describe an online cumulative sum based model named Overcrowd-Severe-Respiratory-Disease-Index based on the Modified Overcrowd Index that simultaneously monitors and informs the demand of those supplies and personnel in a healthcare network generating early warnings of severe respiratory disease epidemic outbreaks through the interpretation of such variables. A post hoc historical archive is generated, helping physicians in charge to improve the transit and future allocation of supplies in the entire hospital network during the outbreak. The model was thoroughly verified in a virtual scenario, generating multiple epidemic outbreaks in a 6-year span for a 13-hospital network. When it was superimposed over the H1N1 influenza outbreak census (2008-2010) taken by the National Institute of Medical Sciences and Nutrition Salvador Zubiran in Mexico City, it showed that it is an effective algorithm to notify early warnings of severe respiratory disease epidemic outbreaks with a minimal rate of false alerts.

  6. Zika virus epidemic: the newest international emergency

    Directory of Open Access Journals (Sweden)

    Ruth Minamisava

    2016-03-01

    production, accurate diagnosis and treatment, training for caring for neurological syndromes and congenital malformations. (iii          Measures for travelers: counseling, disinfestation of aircrafts and airports. (iv          Sharing of information. Some inquiries have been made about the magnitude of this epidemic and its association with microcephaly and neurological disorders(4-5. It is reasonable to consider that there is an underreporting of microcephaly in the records of the Live Births Information System in Brazil. It is also to be expected that, after the national alert, the number of suspected cases would rise. When there is an increase or the implementation of surveillance, this always results in higher sensitivity of detection of suspected/reported cases with an increase in false positives. For these reasons, it is possible to say that part of the increase in reported cases of microcephaly may be attributable to the current intense surveillance. What is inconceivable, however, is that the prevalence of microcephaly in northeastern Brazil is 10 to 20 times higher than in other countries(6. At present, there are hypotheses that the Zika virus may have an etiologic and/or pathophysiological role for these events, which is usually rare. What seems indisputable is the gravity of the situation. Health managers cannot wait for high-level scientific evidence. Care and prudence when assessing is advisable, and the same goes for avoiding premature conclusions. However, given the potential threat, we have a duty to at least protect pregnant women and their fetuses. The current situation poses many challenges that we need to face and it seems logical that Brazil take the lead in beginning the actions. We recognize in our history both the success in the fight against yellow fever early in the last century and also our recent inefficiency in the fight against the Aedes aegypti mosquito to control dengue and chikungunya. It is necessary to create, renew, and

  7. Phenotypic and Genotypic Comparison of Epidemic and Non-Epidemic Strains of Pseudomonas aeruginosa from Individuals with Cystic Fibrosis.

    Directory of Open Access Journals (Sweden)

    Jessica Duong

    Full Text Available Epidemic strains of Pseudomonas aeruginosa have been found worldwide among the cystic fibrosis (CF patient population. Using pulse-field gel electrophoresis, the Prairie Epidemic Strain (PES has recently been found in one-third of patients attending the Calgary Adult CF Clinic in Canada. Using multi-locus sequence typing, PES isolates from unrelated patients were found to consistently have ST192. Though most patients acquired PES prior to enrolling in the clinic, some patients were observed to experience strain replacement upon transitioning to the clinic whereby local non-epidemic P. aeruginosa isolates were displaced by PES. Here we genotypically and phenotypically compared PES to other P. aeruginosa epidemic strains (OES found around the world as well as local non-epidemic CF P. aeruginosa isolates in order to characterize PES. Since some epidemic strains are associated with worse clinical outcomes, we assessed the pathogenic potential of PES to determine if these isolates are virulent, shared properties with OES, and if its phenotypic properties may offer a competitive advantage in displacing local non-epidemic isolates during strain replacement. As such, we conducted a comparative analysis using fourteen phenotypic traits, including virulence factor production, biofilm formation, planktonic growth, mucoidy, and antibiotic susceptibility to characterize PES, OES, and local non-epidemic isolates. We observed that PES and OES could be differentiated from local non-epidemic isolates based on biofilm growth with PES isolates being more mucoid. Pairwise comparisons indicated that PES produced significantly higher levels of proteases and formed better biofilms than OES but were more susceptible to antibiotic treatment. Amongst five patients experiencing strain replacement, we found that super-infecting PES produced lower levels of proteases and elastases but were more resistant to antibiotics compared to the displaced non-epidemic isolates. This

  8. Phenotypic and Genotypic Comparison of Epidemic and Non-Epidemic Strains of Pseudomonas aeruginosa from Individuals with Cystic Fibrosis.

    Science.gov (United States)

    Duong, Jessica; Booth, Sean C; McCartney, Nathan K; Rabin, Harvey R; Parkins, Michael D; Storey, Douglas G

    2015-01-01

    Epidemic strains of Pseudomonas aeruginosa have been found worldwide among the cystic fibrosis (CF) patient population. Using pulse-field gel electrophoresis, the Prairie Epidemic Strain (PES) has recently been found in one-third of patients attending the Calgary Adult CF Clinic in Canada. Using multi-locus sequence typing, PES isolates from unrelated patients were found to consistently have ST192. Though most patients acquired PES prior to enrolling in the clinic, some patients were observed to experience strain replacement upon transitioning to the clinic whereby local non-epidemic P. aeruginosa isolates were displaced by PES. Here we genotypically and phenotypically compared PES to other P. aeruginosa epidemic strains (OES) found around the world as well as local non-epidemic CF P. aeruginosa isolates in order to characterize PES. Since some epidemic strains are associated with worse clinical outcomes, we assessed the pathogenic potential of PES to determine if these isolates are virulent, shared properties with OES, and if its phenotypic properties may offer a competitive advantage in displacing local non-epidemic isolates during strain replacement. As such, we conducted a comparative analysis using fourteen phenotypic traits, including virulence factor production, biofilm formation, planktonic growth, mucoidy, and antibiotic susceptibility to characterize PES, OES, and local non-epidemic isolates. We observed that PES and OES could be differentiated from local non-epidemic isolates based on biofilm growth with PES isolates being more mucoid. Pairwise comparisons indicated that PES produced significantly higher levels of proteases and formed better biofilms than OES but were more susceptible to antibiotic treatment. Amongst five patients experiencing strain replacement, we found that super-infecting PES produced lower levels of proteases and elastases but were more resistant to antibiotics compared to the displaced non-epidemic isolates. This comparative

  9. Competitive epidemic spreading over arbitrary multilayer networks

    Science.gov (United States)

    Darabi Sahneh, Faryad; Scoglio, Caterina

    2014-06-01

    This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI1SI2S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.

  10. Resource allocation for epidemic control in metapopulations.

    Directory of Open Access Journals (Sweden)

    Martial L Ndeffo Mbah

    Full Text Available Deployment of limited resources is an issue of major importance for decision-making in crisis events. This is especially true for large-scale outbreaks of infectious diseases. Little is known when it comes to identifying the most efficient way of deploying scarce resources for control when disease outbreaks occur in different but interconnected regions. The policy maker is frequently faced with the challenge of optimizing efficiency (e.g. minimizing the burden of infection while accounting for social equity (e.g. equal opportunity for infected individuals to access treatment. For a large range of diseases described by a simple SIRS model, we consider strategies that should be used to minimize the discounted number of infected individuals during the course of an epidemic. We show that when faced with the dilemma of choosing between socially equitable and purely efficient strategies, the choice of the control strategy should be informed by key measurable epidemiological factors such as the basic reproductive number and the efficiency of the treatment measure. Our model provides new insights for policy makers in the optimal deployment of limited resources for control in the event of epidemic outbreaks at the landscape scale.

  11. SIS epidemics on Triadic Random Graphs

    CERN Document Server

    Rausch, Ilja

    2016-01-01

    It has been shown in the past that many real-world networks exhibit community structures and non-trivial clustering which comes with the occurrence of a notable number of triangular connections. Yet the influence of such connection patterns on the dynamics of disease transmission is not fully understood. In order to study their role in the context of Susceptible-Infected-Susceptible (SIS) epidemics we use the Triadic Random Graph (TRG) model to construct small networks (N=49) from distinct, closed, directed triadic subpatterns. We compare various global properties of TRGs and use the N-intertwined mean-field approximation (NIMFA) model to perform numerical simulations of SIS-dynamics on TRGs. The results show that the infection spread on undirected TRGs displays very similar behavior to TRGs with an abundance of (directed) feed-back-loops, while using (directed) feed-forward-loops as network-entities significantly slows down the epidemic and lowers the number of infected individuals in the endemic state. More...

  12. Nepalese origin of cholera epidemic in Haiti.

    Science.gov (United States)

    Frerichs, R R; Keim, P S; Barrais, R; Piarroux, R

    2012-06-01

    Cholera appeared in Haiti in October 2010 for the first time in recorded history. The causative agent was quickly identified by the Haitian National Public Health Laboratory and the United States Centers for Disease Control and Prevention as Vibrio cholerae serogroup O1, serotype Ogawa, biotype El Tor. Since then, >500 000 government-acknowledged cholera cases and >7000 deaths have occurred, the largest cholera epidemic in the world, with the real death toll probably much higher. Questions of origin have been widely debated with some attributing the onset of the epidemic to climatic factors and others to human transmission. None of the evidence on origin supports climatic factors. Instead, recent epidemiological and molecular-genetic evidence point to the United Nations peacekeeping troops from Nepal as the source of cholera to Haiti, following their troop rotation in early October 2010. Such findings have important policy implications for shaping future international relief efforts. © 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.

  13. Colliding Epidemics and the Rise of Cryptococcosis

    Directory of Open Access Journals (Sweden)

    Christina C. Chang

    2015-12-01

    Full Text Available Discovered more than 100 years ago as a human pathogen, the Cryptococcus neoformans–Cryptococcus gattii (C. neoformans–C. gattii complex has seen a large global resurgence in its association with clinical disease in the last 30 years. First isolated in fermenting peach juice, and identified as a human pathogen in 1894 in a patient with bone lesions, this environmental pathogen has now found niches in soil, trees, birds, and domestic pets. Cryptococcosis is well recognized as an opportunistic infection and was first noted to be associated with reticuloendothelial cancers in the 1950s. Since then, advances in transplant immunology, medical science and surgical techniques have led to increasing numbers of solid organ transplantations (SOT and hematological stem cell transplantations being performed, and the use of biological immunotherapeutics in increasingly high-risk and older individuals, have contributed to the further rise in cryptococcosis. Globally, however, the major driver for revivification of cryptococcosis is undoubtedly the HIV epidemic, particularly in Sub-Saharan Africa where access to care and antiretroviral therapy remains limited and advanced immunodeficiency, poverty and malnutrition remains the norm. As a zoonotic disease, environmental outbreaks of both human and animal cryptococcosis have been reported, possibly driven by climate change. This is best exemplified by the resurgence of C. gattii infection in Vancouver Island, Canada, and the Pacific Northwest of the United States since 1999. Here we describe how the colliding epidemics of HIV, transplantation and immunologics, climate change and migration have contributed to the rise of cryptococcosis.

  14. Epidemic contact tracing via communication traces.

    Directory of Open Access Journals (Sweden)

    Katayoun Farrahi

    Full Text Available Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  15. Epidemic spreading in random rectangular networks

    Science.gov (United States)

    Estrada, Ernesto; Meloni, Sandro; Sheerin, Matthew; Moreno, Yamir

    2016-11-01

    The use of network theory to model disease propagation on populations introduces important elements of reality to the classical epidemiological models. The use of random geometric graphs (RGGs) is one of such network models that allows for the consideration of spatial properties on disease propagation. In certain real-world scenarios—like in the analysis of a disease propagating through plants—the shape of the plots and fields where the host of the disease is located may play a fundamental role in the propagation dynamics. Here we consider a generalization of the RGG to account for the variation of the shape of the plots or fields where the hosts of a disease are allocated. We consider a disease propagation taking place on the nodes of a random rectangular graph and we consider a lower bound for the epidemic threshold of a susceptible-infected-susceptible model or a susceptible-infected-recovered model on these networks. Using extensive numerical simulations and based on our analytical results we conclude that (ceteris paribus) the elongation of the plot or field in which the nodes are distributed makes the network more resilient to the propagation of a disease due to the fact that the epidemic threshold increases with the elongation of the rectangle. These results agree with accumulated empirical evidence and simulation results about the propagation of diseases on plants in plots or fields of the same area and different shapes.

  16. Suppressed epidemics in multi-relational networks

    CERN Document Server

    Xu, Elvis H W; Xu, C; Tang, Ming; Do, Younghae; Hui, P M

    2014-01-01

    A two-state epidemic model in networks with links mimicking two kinds of relationships between connected nodes is introduced. Links of weights w1 and w0 occur with probabilities p and 1-p, respectively. The fraction of infected nodes rho(p) shows a non-monotonic behavior, with rho drops with p for small p and increases for large p. For small to moderate w1/w0 ratios, rho(p) exhibits a minimum that signifies an optimal suppression. For large w1/w0 ratios, the suppression leads to an absorbing phase consisting only of healthy nodes within a range p_L =p_R. A mean field theory that ignores spatial correlation is shown to give qualitative agreement and capture all the key features. A physical picture that emphasizes the intricate interplay between infections via w0 links and within clusters formed by nodes carrying the w1 links is presented. The absorbing state at large w1/w0 ratios results when the clusters are big enough to disrupt the spread via w0 links and yet small enough to avoid an epidemic within the clu...

  17. Modelling dengue epidemic spreading with human mobility

    Science.gov (United States)

    Barmak, D. H.; Dorso, C. O.; Otero, M.

    2016-04-01

    We explored the effect of human mobility on the spatio-temporal dynamics of Dengue with a stochastic model that takes into account the epidemiological dynamics of the infected mosquitoes and humans, with different mobility patterns of the human population. We observed that human mobility strongly affects the spread of infection by increasing the final size and by changing the morphology of the epidemic outbreaks. When the spreading of the disease is driven only by mosquito dispersal (flight), a main central focus expands diffusively. On the contrary, when human mobility is taken into account, multiple foci appear throughout the evolution of the outbreaks. These secondary foci generated throughout the outbreaks could be of little importance according to their mass or size compared with the largest main focus. However, the coalescence of these foci with the main one generates an effect, through which the latter develops a size greater than the one obtained in the case driven only by mosquito dispersal. This increase in growth rate due to human mobility and the coalescence of the foci are particularly relevant in temperate cities such as the city of Buenos Aires, since they give more possibilities to the outbreak to grow before the arrival of the low-temperature season. The findings of this work indicate that human mobility could be the main driving force in the dynamics of vector epidemics.

  18. [A pseudo-epidemic of puerperal sepsis].

    Science.gov (United States)

    Dietz, V; Derks, J B; Mascini, E M; Bruinse, H W

    2003-12-20

    Within a four-week period, five patients were admitted to the maternity ward of the Utrecht Children's Hospital diagnosed with puerperal sepsis due to group-A streptococcal infection. The clinical presentation was different for each patient. All patients recovered upon adequate antibiotic treatment. One of the children died, possibly due to sepsis and hypotension of his mother. As group-A streptococci can be extremely contagious and an epidemic was suspected, measures for additional hygiene were taken. Furthermore, all personnel at the maternity ward and the obstetric centre were tested. T-serotyping, M-genotyping, exotoxin A- and C-gene amplification and pulsed field gel electrophoresis were used to characterize the cultured group-A streptococci. Cross-contamination was not found. Therefore, this increase in puerperal sepsis was attributed to polyclonal expansion rather than an epidemic. All mothers of newly born children who present with fever and lower abdominal pain should be suspected of group-A streptococcal infection. Evaluation and treatment in hospital is indicated due to a sometimes fulminant course. When group-A streptococci are cultured again in a new pregnancy, eradication therapy during pregnancy or prophylactic treatment during birth should be considered to prevent recurrent infection.

  19. Epidemic Process over the Commute Network in a Metropolitan Area

    Science.gov (United States)

    Yashima, Kenta; Sasaki, Akira

    2014-01-01

    An understanding of epidemiological dynamics is important for prevention and control of epidemic outbreaks. However, previous studies tend to focus only on specific areas, indicating that application to another area or intervention strategy requires a similar time-consuming simulation. Here, we study the epidemic dynamics of the disease-spread over a commute network, using the Tokyo metropolitan area as an example, in an attempt to elucidate the general properties of epidemic spread over a commute network that could be used for a prediction in any metropolitan area. The model is formulated on the basis of a metapopulation network in which local populations are interconnected by actual commuter flows in the Tokyo metropolitan area and the spread of infection is simulated by an individual-based model. We find that the probability of a global epidemic as well as the final epidemic sizes in both global and local populations, the timing of the epidemic peak, and the time at which the epidemic reaches a local population are mainly determined by the joint distribution of the local population sizes connected by the commuter flows, but are insensitive to geographical or topological structure of the network. Moreover, there is a strong relation between the population size and the time that the epidemic reaches this local population and we are able to determine the reason for this relation as well as its dependence on the commute network structure and epidemic parameters. This study shows that the model based on the connection between the population size classes is sufficient to predict both global and local epidemic dynamics in metropolitan area. Moreover, the clear relation of the time taken by the epidemic to reach each local population can be used as a novel measure for intervention; this enables efficient intervention strategies in each local population prior to the actual arrival. PMID:24905831

  20. Paarberatung online

    Directory of Open Access Journals (Sweden)

    Josef Lang

    2005-09-01

    Full Text Available Auf dem Hintergrund der Fragestellungen und der Entwicklung von Beratungsangeboten im Internet generell wird das Spezifische der Paarberatung im Internet dargestellt. Die bekanntesten Angebote in deutscher Sprache werden vorgestellt. In einem Schwerpunkt wird das Konzept von „www.paarberatung.ch“ skizziert. Angebote unterscheiden sich in ihren Zielsetzungen, die auf die unterschiedlichen Erwartungen der Ratsuchenden ausgerichtet sind und auf jede Anfrage zugeschnitten werden. Methodische Leitlinien sind aus der Beratungspsychologie mit Blick auf das Medium Internet abgeleitet.Der Autor bevorzugt den systemischen Ansatz, integriert Methoden des kognitiv-verhaltenstherapeutischen Beratungsansatzes und plädiert dafür, die personspezifischen Elemente einer Anfrage für die Antwort zu nutzen. Grundsätzliches zur Psychologie der Paarberatung und zur Textinterpretation bei einer E-Mail-Beratung wird veranschaulicht mit einem konkreten Beispiel aus der Online-praxis und einer kurzen Beschreibung der Population der Ratsuchenden.

  1. Online Innovation

    DEFF Research Database (Denmark)

    Vujovic, Sladjana; Ulhøi, John Parm

    2008-01-01

    on proprietary knowledge. Design/methodology/approach - The paper borrows from the theory of communities-of-practice, which takes into account social relations, contacts, and the transfer and incorporation of knowledge. Open source innovation is not the exclusive preserve of computer nerds, but also has...... implications for existing software manufacturers. The paper therefore includes the case of IBM, a company which has successfully integrated this new and more open way of collaboration into its business model. Findings - The paper concludes that online computer-based innovation fundamentally challenges current...... for practitioners directly involved in innovation and product development. Originality/value - This paper develops a conceptual framework for understanding product development based on non-proprietary knowledge, which cannot be adequately accounted for by traditional corporate innovation theory alone....

  2. WKB theory of epidemic fade-out in stochastic populations

    OpenAIRE

    Meerson, Baruch; Sasorov, Pavel V.

    2009-01-01

    Stochastic effects may cause fade-out of an infectious disease in a population immediately after an epidemic outbreak. We develop WKB theory to determine the most probable path of the system toward epidemic fade-out and to evaluate the fade-out probability. The most probable path is an instanton-like orbit in the phase space of the underlying Hamiltonian flow.

  3. Effects of local and global network connectivity on synergistic epidemics

    Science.gov (United States)

    Broder-Rodgers, David; Pérez-Reche, Francisco J.; Taraskin, Sergei N.

    2015-12-01

    Epidemics in networks can be affected by cooperation in transmission of infection and also connectivity between nodes. An interplay between these two properties and their influence on epidemic spread are addressed in the paper. A particular type of cooperative effects (called synergy effects) is considered, where the transmission rate between a pair of nodes depends on the number of infected neighbors. The connectivity effects are studied by constructing networks of different topology, starting with lattices with only local connectivity and then with networks that have both local and global connectivity obtained by random bond-rewiring to nodes within a certain distance. The susceptible-infected-removed epidemics were found to exhibit several interesting effects: (i) for epidemics with strong constructive synergy spreading in networks with high local connectivity, the bond rewiring has a negative role in epidemic spread, i.e., it reduces invasion probability; (ii) in contrast, for epidemics with destructive or weak constructive synergy spreading on networks of arbitrary local connectivity, rewiring helps epidemics to spread; (iii) and, finally, rewiring always enhances the spread of epidemics, independent of synergy, if the local connectivity is low.

  4. The severe acute respiratory syndrome epidemic in mainland China dissected

    NARCIS (Netherlands)

    W.C. Cao (Wu Chun); S.J. de Vlas (Sake); J.H. Richardus (Jan Hendrik)

    2011-01-01

    textabstractThis paper provides a review of a recently published series of studies that give a detailed and comprehensive documentation of the severe acute respiratory syndrome (SARS) epidemic in mainland China, which severely struck the country in the spring of 2003. The epidemic spanned a large ge

  5. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    G. Magiorkinis (Gkikas); K. Angelis (Konstantinos); I. Mamais (Ioannis); Katzourakis, A. (Aris); A. Hatzakis (Angelos); J. Albert (Jan); Lawyer, G. (Glenn); O. Hamouda (Osamah); D. Struck (Daniel); J. Vercauteren (Jurgen); A. Wensing (Amj); I. Alexiev (Ivailo); B. Åsjö (Birgitta); C. Balotta (Claudia); Gomes, P. (Perpétua); R.J. Camacho (Ricardo Jorge); S. Coughlan (Suzie); A. Griskevicius (Algirdas); Z. Grossman (Zehava); Horban, A. (Anders); L.G. Kostrikis (Leondios); Lepej, S.J. (Snjezana J.); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen; D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.C. Schmit; A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); Stylianou, D.C. (Dora C.); C.A. Boucher (Charles); Nikolopoulos, G. (Georgios); Vasylyeva, T. (Tetyana); Friedman, S.R. (Samuel R.); D.A.M.C. van de Vijver (David); G. Angarano (Guiseppe); M.L. Chaix (Marie Laure); A. de Luca (Andrea); K. Korn (Klaus); Loveday, C. (Clive); V. Soriano (Virtudes); S. Yerly (Sabine); M. Zazzi; A.M. Vandamme (Anne Mieke); D. Paraskevis (Dimitrios)

    2016-01-01

    textabstractHuman immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa

  6. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J.; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G.; Lepej, Snjezana J.; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C.; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R.; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne Mieke; Paraskevis, Dimitrios

    2016-01-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti

  7. Resolving epidemic network failures through differentiated repair times

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée; Manzano, Marc

    2015-01-01

    In this study, the authors investigate epidemic failure spreading in large-scale transport networks under generalisedmulti-protocol label switching control plane. By evaluating the effect of the epidemic failure spreading on the network,they design several strategies for cost-effective network...

  8. Epidemic Spreading in a Multi-compartment System

    Institute of Scientific and Technical Information of China (English)

    GAO Zong-Mao; GU Jiao; LI Wei

    2012-01-01

    We introduce the variant rate and white noise into the susceptible-infected-removed (SIR) model for epidemics, discuss the epidemic dynamics of a multiple-compartment system, and describe this system by using master equations. For both the local epidemic spreading system and the whole multiple-compartment system, we find that a threshold could be useful in forecasting when the epidemic vanishes. Furthermore, numerical simulations show that a model with the variant infection rate and white noise can improve fitting with real SARS data.%We introduce the variant rate and white noise into the susceptible-infected-removed (SIR) model for epidemics,discuss the epidemic dynamics of a multiple-compartment system,and describe this system by using master equations.For both the local epidemic spreading system and the whole multiple-compartment system,we find that a threshold could be useful in forecasting when the epidemic vanishes.Furthermore,numerical simulations show that a model with the variant infection rate and white noise can improve fitting with real SARS data.

  9. Epidemic features affecting the performance of outbreak detection algorithms

    Directory of Open Access Journals (Sweden)

    Kuang Jie

    2012-06-01

    Full Text Available Abstract Background Outbreak detection algorithms play an important role in effective automated surveillance. Although many algorithms have been designed to improve the performance of outbreak detection, few published studies have examined how epidemic features of infectious disease impact on the detection performance of algorithms. This study compared the performance of three outbreak detection algorithms stratified by epidemic features of infectious disease and examined the relationship between epidemic features and performance of outbreak detection algorithms. Methods Exponentially weighted moving average (EWMA, cumulative sum (CUSUM and moving percentile method (MPM algorithms were applied. We inserted simulated outbreaks into notifiable infectious disease data in China Infectious Disease Automated-alert and Response System (CIDARS, and compared the performance of the three algorithms with optimized parameters at a fixed false alarm rate of 5% classified by epidemic features of infectious disease. Multiple linear regression was adopted to analyse the relationship of the algorithms’ sensitivity and timeliness with the epidemic features of infectious diseases. Results The MPM had better detection performance than EWMA and CUSUM through all simulated outbreaks, with or without stratification by epidemic features (incubation period, baseline counts and outbreak magnitude. The epidemic features were associated with both sensitivity and timeliness. Compared with long incubation, short incubation had lower probability (β* = −0.13, P  Conclusions The results of this study suggest that the MPM is a prior algorithm for outbreak detection and differences of epidemic features in detection performance should be considered in automatic surveillance practice.

  10. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    G. Magiorkinis (Gkikas); K. Angelis (Konstantinos); I. Mamais (Ioannis); Katzourakis, A. (Aris); A. Hatzakis (Angelos); J. Albert (Jan); Lawyer, G. (Glenn); O. Hamouda (Osamah); D. Struck (Daniel); J. Vercauteren (Jurgen); A. Wensing (Amj); I. Alexiev (Ivailo); B. Åsjö (Birgitta); C. Balotta (Claudia); Gomes, P. (Perpétua); R.J. Camacho (Ricardo Jorge); S. Coughlan (Suzie); A. Griskevicius (Algis); Z. Grossman (Zehava); Horban, A. (Anders); L.G. Kostrikis (Leondios); Lepej, S.J. (Snjezana J.); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen; D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.C. Schmit; A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); Stylianou, D.C. (Dora C.); C.A. Boucher (Charles); Nikolopoulos, G. (Georgios); Vasylyeva, T. (Tetyana); Friedman, S.R. (Samuel R.); D.A.M.C. van de Vijver (David); G. Angarano (Guiseppe); M.L. Chaix (Marie Laure); A. de Luca (Andrea); K. Korn (Klaus); Loveday, C. (Clive); V. Soriano (Virtudes); S. Yerly (Sabine); M. Zazzi; A.M. Vandamme (Anne Mieke); D. Paraskevis (Dimitrios)

    2016-01-01

    textabstractHuman immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa th

  11. The origin and emergence of an HIV-1 epidemic:

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne; Audelin, Anne M.; Helleberg, Marie;

    2014-01-01

    To describe, at patient-level detail, the determining events and factors involved in the development of a country's HIV-1 epidemic.......To describe, at patient-level detail, the determining events and factors involved in the development of a country's HIV-1 epidemic....

  12. Obesity and diabetes epidemics: cancer repercussions.

    Science.gov (United States)

    Hjartåker, Anette; Langseth, Hilde; Weiderpass, Elisabete

    2008-01-01

    The prevalence of overweight (body mass index, BMI, between 25 and 30 kg/m2) and obesity (BMI of 30 kg/m2 or higher) is increasing rapidly worldwide, especially in developing countries and countries undergoing economic transition to a market economy. One consequence of obesity is an increased risk of developing type II diabetes. Overall, there is considerable evidence that overweight and obesity are associated with risk for some of the most common cancers. There is convincing evidence of a positive association between overweight/obesity and risk for adenocarcinoma of the oesophagus and the gastric cardia, colorectal cancer, postmenopausal breast cancer, endometrial cancer and kidney cancer (renal-cell). Premenopausal breast cancer seems to be inversely related to obesity. For all other cancer sites the evidence of an association between overweight/obesity and cancer is inadequate, although there are studies suggesting an increased risk of cancers of the liver, gallbladder, pancreas, thyroid gland and in lymphoid and haematopoietic tissue. Far less is known about the association between diabetes mellitus type I (also called insulin dependent diabetes mellitus or juvenile diabetes), type II diabetes (called non-insulin dependent diabetes mellitus or adult onset diabetes mellitus) and cancer risk. The most common type of diabetes mellitus, type II, seems to be associated with liver and pancreas cancer and probably with colorectal cancer. Some studies suggest an association with endometrial and postmenopausal breast cancer. Studies reporting on the association between type I diabetes mellitus, which is relatively rare in most populations and cancer risk are scanty, but suggest a possible association with endometrial cancer. Overweight and obesity, as well as type II diabetes mellitus are largely preventable through changes in lifestyle. The fundamental causes of the obesity epidemic-and consequently the diabetes type II epidemic-are societal, resulting from an

  13. Mutual Feedback Between Epidemic Spreading and Information Diffusion

    CERN Document Server

    Zhan, Xiu-Xiu; Zhou, Ge; Zhang, Zi-Ke; Sun, Gui-Quan; Zhu, Jonathan J H

    2015-01-01

    The impact that information diffusion has on epidemic spreading has recently attracted much attention. As a disease begins to spread in the population, information about the disease is transmitted to others, which in turn has an effect on the spread of disease. In this paper, using empirical results of the propagation of H7N9 and information about the disease, we clearly show that the spreading dynamics of the two-types of processes influence each other. We build a mathematical model in which both types of spreading dynamics are described using the SIS process in order to illustrate the influence of information diffusion on epidemic spreading. Both the simulation results and the pairwise analysis reveal that information diffusion can increase the threshold of an epidemic outbreak, decrease the final fraction of infected individuals and significantly decrease the rate at which the epidemic propagates. Additionally, we find that the multi-outbreak phenomena of epidemic spreading, along with the impact of inform...

  14. Chronicle of malaria epidemics in Thailand, 1980-2000.

    Science.gov (United States)

    Konchom, Supawadee; Singhasivanon, Pratap; Kaewkungwal, Jaranit; Chuprapawan, Sirichai; Thimasarn, Krongthong; Kidson, Chev; Yimsamran, Surapon; Rojanawatsirivet, Chaiporn

    2005-01-01

    The occurrence of malaria epidemics in Thailand was reviewed from the malaria surveillance report of the National Malaria Control Program. The literature review revealed that the four epidemic periods recorded during 1980-2000 almost always occurred in the provinces and districts located along international borders. Malaria epidemics are caused by various factors such as: extensive population movement, multi-drug resistance development, low immune status of the population, lack of knowledge and appropriate personal protection against mosquito biting, and the re-emergence of malaria transmission in low malarious areas. Such factors can lead to changes in the parasite ratio and appearance of malaria epidemics throughout the country. Evidence related to the burden of malaria epidemics was also reviewed to identify causal factors that will be helpful in future research.

  15. Traffic-driven epidemic spreading in correlated networks

    CERN Document Server

    Yang, Han-Xin; Lai, Ying-Cheng

    2015-01-01

    In spite of the extensive previous efforts on traffic dynamics and epidemic spreading in complex networks, the problem of traffic-driven epidemic spreading on {\\em correlated} networks has not been addressed. Interestingly, we find that the epidemic threshold, a fundamental quantity underlying the spreading dynamics, exhibits a non-monotonic behavior in that it can be minimized for some critical value of the assortativity coefficient, a parameter characterizing the network correlation. To understand this phenomenon, we use the degree-based mean-field theory to calculate the traffic-driven epidemic threshold for correlated networks. The theory predicts that the threshold is inversely proportional to the packet-generation rate and the largest eigenvalue of the betweenness matrix. We obtain consistency between theory and numerics. Our results may provide insights into the important problem of controlling/harnessing real-world epidemic spreading dynamics driven by traffic flows.

  16. Hysteresis loop of nonperiodic outbreaks of recurrent epidemics.

    Science.gov (United States)

    Liu, Hengcong; Zheng, Muhua; Wu, Dayu; Wang, Zhenhua; Liu, Jinming; Liu, Zonghua

    2016-12-01

    Most of the studies on epidemics so far have focused on the growing phase, such as how an epidemic spreads and what are the conditions for an epidemic to break out in a variety of cases. However, we discover from real data that on a large scale, the spread of an epidemic is in fact a recurrent event with distinctive growing and recovering phases, i.e., a hysteresis loop. We show here that the hysteresis loop can be reproduced in epidemic models provided that the infectious rate is adiabatically increased or decreased before the system reaches its stationary state. Two ways to the hysteresis loop are revealed, which is helpful in understanding the mechanics of infections in real evolution. Moreover, a theoretical analysis is presented to explain the mechanism of the hysteresis loop.

  17. Eigen values in epidemic and other bio-inspired models

    Science.gov (United States)

    Supriatna, A. K.; Anggriani, N.; Carnia, E.; Raihan, A.

    2017-08-01

    Eigen values and the largest eigen value have special roles in many applications. In this paper we will discuss its role in determining the epidemic threshold in which we can determine if an epidemic will decease or blow out eventually. Some examples and their consequences to controling the epidemic are also discusses. Beside the application in epidemic model, the paper also discusses other example of appication in bio-inspired model, such as the backcross breeding for two age classes of local and exotic goats. Here we give some elaborative examples on the use of previous backcross breeding model. Some future direction on the exploration of the relationship between these eigenvalues to different epidemic models and other bio-inspired models are also presented.

  18. Recovery rate affects the effective epidemic threshold with synchronous updating

    CERN Document Server

    Shu, Panpan; Tang, Ming; Zhao, Pengcheng; Zhang, Yi-Cheng

    2016-01-01

    Accurate identification of effective epidemic threshold is essential for understanding epidemic dynamics on complex networks. The existing studies on the effective epidemic threshold of the susceptible-infected-removed (SIR) model generally assume that all infected nodes immediately recover after the infection process, which more or less does not conform to the realistic situation of disease. In this paper, we systematically study the effect of arbitrary recovery rate on the SIR spreading dynamics on complex networks. We derive the theoretical effective epidemic threshold and final outbreak size based on the edge-based compartmental theory. To validate the proposed theoretical predictions, extensive numerical experiments are implemented by using asynchronous and synchronous updating methods. When asynchronous updating method is used in simulations, recovery rate does not affect the final state of spreading dynamics. But with synchronous updating, we find that the effective epidemic threshold decreases with re...

  19. Estimating the epidemic threshold on networks by deterministic connections

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kezan, E-mail: lkzzr@sohu.com; Zhu, Guanghu [School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin 541004 (China); Fu, Xinchu [Department of Mathematics, Shanghai University, Shanghai 200444 (China); Small, Michael [School of Mathematics and Statistics, The University of Western Australia, Crawley, Western Australia 6009 (Australia)

    2014-12-15

    For many epidemic networks some connections between nodes are treated as deterministic, while the remainder are random and have different connection probabilities. By applying spectral analysis to several constructed models, we find that one can estimate the epidemic thresholds of these networks by investigating information from only the deterministic connections. Nonetheless, in these models, generic nonuniform stochastic connections and heterogeneous community structure are also considered. The estimation of epidemic thresholds is achieved via inequalities with upper and lower bounds, which are found to be in very good agreement with numerical simulations. Since these deterministic connections are easier to detect than those stochastic connections, this work provides a feasible and effective method to estimate the epidemic thresholds in real epidemic networks.

  20. Evaluating Subcriticality during the Ebola Epidemic in West Africa.

    Directory of Open Access Journals (Sweden)

    Wayne T A Enanoria

    Full Text Available The 2014-2015 Ebola outbreak is the largest and most widespread to date. In order to estimate ongoing transmission in the affected countries, we estimated the weekly average number of secondary cases caused by one individual infected with Ebola throughout the infectious period for each affected West African country using a stochastic hidden Markov model fitted to case data from the World Health Organization. If the average number of infections caused by one Ebola infection is less than 1.0, the epidemic is subcritical and cannot sustain itself. The epidemics in Liberia and Sierra Leone have approached subcriticality at some point during the epidemic; the epidemic in Guinea is ongoing with no evidence that it is subcritical. Response efforts to control the epidemic should continue in order to eliminate Ebola cases in West Africa.

  1. Epidemic keratoconjunctivitis and lacrimal excretory system obstruction.

    Science.gov (United States)

    Hyde, K J; Berger, S T

    1988-10-01

    Epiphora is a common symptom associated with the acute phase of epidemic keratoconjunctivitis (EKC). Reflex lacrimal secretion occurs secondary to conjunctival or corneal inflammation. Acquired obstruction of the lacrimal excretory system may account for persistence of tearing after resolution of the acute inflammatory phase of the viral infection. Three cases of lacrimal excretory system obstruction after EKC are reported. Multifocal obstruction of the canaliculi and nasolacrimal duct is characteristic. Dacryocystorhinostomy (DCR) was required to relieve obstruction in all cases. Probing and corticosteroid irrigation may avoid the need for silicone intubation or conjunctivodacryocystorhinostomy in the management of canalicular obstruction. Persistent epiphora after EKC should raise clinical suspicion of acquired dacryostenosis. Early recognition may allow for optimal management.

  2. Epidemics of Liquidity Shortages in Interbank Markets

    CERN Document Server

    Brandi, Giuseppe; Cimini, Giulio

    2016-01-01

    Financial contagion from liquidity shocks has being recently ascribed as a prominent driver of systemic risk in interbank lending markets. Building on standard compartment models used in epidemics, here we develop an EDB (Exposed-Distressed-Bankrupted) model for the dynamics of liquidity shocks reverberation between banks, and validate it on electronic market for interbank deposits data. We show that the interbank network was highly susceptible to liquidity contagion at the beginning of the 2007/2008 global financial crisis, and that the subsequent micro-prudential and liquidity hoarding policies adopted by banks increased the network resilience to systemic risk, yet with the undesired side effect of drying out liquidity from the market. We finally show that the individual riskiness of a bank is better captured by its network centrality than by its participation to the market, along with the currently debated concept of "too interconnected to fail".

  3. Epidemic extinction and control in heterogeneous networks

    CERN Document Server

    Hindes, Jason

    2016-01-01

    We consider epidemic extinction in finite networks with broad variation in local connectivity. Generalizing the theory of large fluctuations to random networks with a given degree distribution, we are able to predict the most probable, or optimal, paths to extinction in various configurations, including truncated power-laws. We find that paths for heterogeneous networks follow a limiting form in which infection first decreases in low-degree nodes, which triggers a rapid extinction in high- degree nodes, and finishes with a residual low-degree extinction. The usefulness of the approach is further demonstrated through optimal control strategies that leverage finite-size fluctuations. Interestingly, we find that the optimal control is a mix of treating both high and low-degree nodes based on large-fluctuation theoretical predictions.

  4. Epidemic spreading on evolving signed networks

    CERN Document Server

    Saeedian, M; Jafari, G R; Kertesz, J

    2016-01-01

    Most studies of disease spreading consider the underlying social network as obtained without the contagion, though epidemic influences peoples willingness to contact others: A friendly contact may be turned to unfriendly to avoid infection. We study the susceptible-infected (SI) disease spreading model on signed networks, in which each edge is associated with a positive or negative sign representing the friendly or unfriendly relation between its end nodes. In a signed network, according to Heiders theory, edge signs evolve such that finally a state of structural balance is achieved, corresponding to no frustration in physics terms. However, the danger of infection affects the evolution of its edge signs. To describe the coupled problem of the sign evolution and disease spreading, we generalize the notion of structural balance by taking into account the state of the nodes. We introduce an energy function and carry out Monte-Carlo simulations on complete networks to test the energy landscape, where we find loc...

  5. Real-time forecasts of dengue epidemics

    Science.gov (United States)

    Yamana, T. K.; Shaman, J. L.

    2015-12-01

    Dengue is a mosquito-borne viral disease prevalent in the tropics and subtropics, with an estimated 2.5 billion people at risk of transmission. In many areas with endemic dengue, disease transmission is seasonal but prone to high inter-annual variability with occasional severe epidemics. Predicting and preparing for periods of higher than average transmission is a significant public health challenge. Here we present a model of dengue transmission and a framework for optimizing model simulations with real-time observational data of dengue cases and environmental variables in order to generate ensemble-based forecasts of the timing and severity of disease outbreaks. The model-inference system is validated using synthetic data and dengue outbreak records. Retrospective forecasts are generated for a number of locations and the accuracy of these forecasts is quantified.

  6. Quasi-neutral theory of epidemic outbreaks.

    Directory of Open Access Journals (Sweden)

    Oscar A Pinto

    Full Text Available Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for "accidental pathogens" which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way.

  7. Power laws governing epidemics in isolated populations

    Science.gov (United States)

    Rhodes, C. J.; Anderson, R. M.

    1996-06-01

    TEMPORAL changes in the incidence of measles virus infection within large urban communities in the developed world have been the focus of much discussion in the context of the identification and analysis of nonlinear and chaotic patterns in biological time series1-11. In contrast, the measles records for small isolated island populations are highly irregular, because of frequent fade-outs of infection12-14, and traditional analysis15 does not yield useful insight. Here we use measurements of the distribution of epidemic sizes and duration to show that regularities in the dynamics of such systems do become apparent. Specifically, these biological systems are characterized by well-defined power laws in a manner reminiscent of other nonlinear, spatially extended dynamical systems in the physical sciences16-19. We further show that the observed power-law exponents are well described by a simple lattice-based model which reflects the social interaction between individual hosts.

  8. Epidemics scenarios in the "Romantic network"

    CERN Document Server

    Carvalho, Alexsandro M

    2012-01-01

    The structure of sexual contacts, its contacts network and its temporal interactions, play an important role in the spread of sexually transmitted infections. Unfortunately, that kind of data is very hard to obtain. One of the few exceptions is the "Romantic network" which is a complete structure of a real sexual network of a high school. In terms of topology, unlike other sexual networks classified as scale-free network. Regarding the temporal structure, several studies indicate that relationship timing can have effects on diffusion through networks, as relationship order determines transmission routes.With the aim to check if the particular structure, static and dynamic, of the Romantic network is determinant for the propagation of an STI in it, we perform simulations in two scenarios: the static network where all contacts are available and the dynamic case where contacts evolve in time. In the static case, we compare the epidemic results in the Romantic network with some paradigmatic topologies. We further...

  9. A new epidemic model of computer viruses

    Science.gov (United States)

    Yang, Lu-Xing; Yang, Xiaofan

    2014-06-01

    This paper addresses the epidemiological modeling of computer viruses. By incorporating the effect of removable storage media, considering the possibility of connecting infected computers to the Internet, and removing the conservative restriction on the total number of computers connected to the Internet, a new epidemic model is proposed. Unlike most previous models, the proposed model has no virus-free equilibrium and has a unique endemic equilibrium. With the aid of the theory of asymptotically autonomous systems as well as the generalized Poincare-Bendixson theorem, the endemic equilibrium is shown to be globally asymptotically stable. By analyzing the influence of different system parameters on the steady number of infected computers, a collection of policies is recommended to prohibit the virus prevalence.

  10. Cholera: a continuous epidemic in Africa.

    Science.gov (United States)

    Naidoo, A; Patric, K

    2002-06-01

    Cholera continues to plague many parts of the world, but has largely been concentrated in Africa, which contributes more than 80% of the total cases worldwide. Natural disasters, like the 2000 floods in Mozambique and the volcanic eruption in the Democratic Republic of the Congo in 2002, generally lead to new outbreaks of the disease. The refugee problem in many countries throughout the world also causes potential threats for disease outbreaks. Case fatality rates are high, and we are not anywhere near curbing new cholera epidemics, especially in Africa. It is thus imperative to renew discussions about the nature of this deadly disease, its treatment, measures for prevention and control, modes of transmission, its physical, social and economic impact, and potential solutions.

  11. Quasi-Neutral Theory of Epidemic Outbreaks

    Science.gov (United States)

    Pinto, Oscar A.; Muñoz, Miguel A.

    2011-01-01

    Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for “accidental pathogens” which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi) neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi)-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way. PMID:21760930

  12. Dynamics of Dengue epidemics using optimal control

    CERN Document Server

    Rodrigues, Helena Sofia; Torres, Delfim F M

    2010-01-01

    We present an application of optimal control theory to Dengue epidemics. This epidemiologic disease is an important theme in tropical countries due to the growing number of infected individuals. The dynamic model is described by a set of nonlinear ordinary differential equations, that depend on the dynamic of the Dengue mosquito, the number of infected individuals, and the people's motivation to combat the mosquito. The cost functional depends not only on the costs of medical treatment of the infected people but also on the costs related to educational and sanitary campaigns. Two approaches to solve the problem are considered: one using optimal control theory, another one by discretizing first the problem and then solving it with nonlinear programming. The results obtained with OC-ODE and IPOPT solvers are given and discussed. We observe that with current computational tools it is easy to obtain, in an efficient way, better solutions to Dengue problems, leading to a decrease of infected mosquitoes and individ...

  13. Forecasting fluctuating outbreaks in seasonally driven epidemics

    Science.gov (United States)

    Stone, Lewi

    2009-03-01

    Seasonality is a driving force that has major impact on the spatio-temporal dynamics of natural systems and their populations. This is especially true for the transmission of common infectious diseases such as influenza, measles, chickenpox, and pertussis. Here we gain new insights into the nonlinear dynamics of recurrent diseases through the analysis of the classical seasonally forced SIR epidemic model. Despite many efforts over the last decades, it has been difficult to gain general analytical insights because of the complex synchronization effects that can evolve between the external forcing and the model's natural oscillations. The analysis advanced here attempts to make progress in this direction by focusing on the dynamics of ``skips'' where we identify and predict years in which the epidemic is absent rather than outbreak years. Skipping events are intrinsic to the forced SIR model when parameterised in the chaotic regime. In fact, it is difficult if not impossible to locate realistic chaotic parameter regimes in which outbreaks occur regularly each year. This contrasts with the well known Rossler oscillator whose outbreaks recur regularly but whose amplitude vary chaotically in time (Uniform Phase Chaotic Amplitude oscillations). The goal of the present study is to develop a ``language of skips'' that makes it possible to predict under what conditions the next outbreak is likely to occur, and how many ``skips'' might be expected after any given outbreak. We identify a new threshold effect and give clear analytical conditions that allow accurate predictions. Moreover, the time of occurrence (i.e., phase) of an outbreak proves to be a useful new parameter that carries important epidemiological information. In forced systems, seasonal changes can prevent late-initiating outbreaks (i.e., having high phase) from running to completion. These principles yield forecasting tools that should have relevance for the study of newly emerging and reemerging diseases.

  14. Heroin epidemics, treatment and ODE modelling.

    Science.gov (United States)

    White, Emma; Comiskey, Catherine

    2007-07-01

    The UN [United Nations Office on Drugs and Crime (UNODC): World Drug Report, 2005, vol. 1: Analysis. UNODC, 2005.], EU [European Monitoring Centre for Drugs and Drug Addiction (EMCDDA): Annual Report, 2005.http://annualreport.emcdda.eu.int/en/home-en.html.] and WHO [World Health Organisation (WHO): Biregional Strategy for Harm Reduction, 2005-2009. HIV and Injecting Drug Use. WHO, 2005.] have consistently highlighted in recent years the ongoing and persistent nature of opiate and particularly heroin use on a global scale. While this is a global phenomenon, authors have emphasised the significant impact such an epidemic has on individual lives and on society. National prevalence studies have indicated the scale of the problem, but the drug-using career, typically consisting of initiation, habitual use, a treatment-relapse cycle and eventual recovery, is not well understood. This paper presents one of the first ODE models of opiate addiction, based on the principles of mathematical epidemiology. The aim of this model is to identify parameters of interest for further study, with a view to informing and assisting policy-makers in targeting prevention and treatment resources for maximum effectiveness. An epidemic threshold value, R(0), is proposed for the drug-using career. Sensitivity analysis is performed on R(0) and it is then used to examine the stability of the system. A condition under which a backward bifurcation may exist is found, as are conditions that permit the existence of one or more endemic equilibria. A key result arising from this model is that prevention is indeed better than cure.

  15. Epidemics scenarios in the "Romantic network".

    Directory of Open Access Journals (Sweden)

    Alexsandro M Carvalho

    Full Text Available The networks of sexual contacts together with temporal interactions play key roles in the spread of sexually transmitted infections. Unfortunately, data for this kind of network is scarce. One of the few exceptions, the "Romantic network", is a complete structure of a real sexual network in a high school. Based on many network measurements the authors of the work have concluded that it does not correspond to any other model network. Regarding the temporal structure, several studies indicate that relationship timing can have an effect on the diffusion throughout networks, as relationship order determines transmission routes. The aim is to check if the particular structure, static and dynamic, of the Romantic network is determinant for the propagation of an STI. We performed simulations in two scenarios: the static network where all contacts are available and the dynamic case where contacts evolve over time. In the static case, we compared the epidemic results in the Romantic network with some paradigmatic topologies. In the dynamic scenario, we considered the dynamics of formation of pairs in the Romantic network and we studied the propagation of the diseases. Our results suggest that although this real network cannot be labeled as a Watts-Strogatz network, it is, in regard to the propagation of an STI, very similar to a high disorder network. Additionally, we found that: the effect that any individual contacting an externally infected subject is to make the network closer to a fully connected one, the higher the contact degree of patient zero the faster the spread of the outbreaks, and the epidemic impact is proportional to the numbers of contacts per unit time. Finally, our simulations confirm that relationship timing severely reduced the final outbreak size, and also, show a clear correlation between the average degree and the outbreak size over time.

  16. Information content of household-stratified epidemics

    Directory of Open Access Journals (Sweden)

    T.M. Kinyanjui

    2016-09-01

    Full Text Available Household structure is a key driver of many infectious diseases, as well as a natural target for interventions such as vaccination programs. Many theoretical and conceptual advances on household-stratified epidemic models are relatively recent, but have successfully managed to increase the applicability of such models to practical problems. To be of maximum realism and hence benefit, they require parameterisation from epidemiological data, and while household-stratified final size data has been the traditional source, increasingly time-series infection data from households are becoming available. This paper is concerned with the design of studies aimed at collecting time-series epidemic data in order to maximize the amount of information available to calibrate household models. A design decision involves a trade-off between the number of households to enrol and the sampling frequency. Two commonly used epidemiological study designs are considered: cross-sectional, where different households are sampled at every time point, and cohort, where the same households are followed over the course of the study period. The search for an optimal design uses Bayesian computationally intensive methods to explore the joint parameter-design space combined with the Shannon entropy of the posteriors to estimate the amount of information in each design. For the cross-sectional design, the amount of information increases with the sampling intensity, i.e., the designs with the highest number of time points have the most information. On the other hand, the cohort design often exhibits a trade-off between the number of households sampled and the intensity of follow-up. Our results broadly support the choices made in existing epidemiological data collection studies. Prospective problem-specific use of our computational methods can bring significant benefits in guiding future study designs.

  17. Discrimination between epidemic and non-epidemic glycopeptide-resistant E. faecium in a post-outbreak situation.

    Science.gov (United States)

    Borgmann, S; Schulte, B; Wolz, C; Gruber, H; Werner, G; Goerke, C; Klare, I; Beyser, K; Heeg, P; Autenrieth, I B

    2007-09-01

    Vancomycin-resistant enterococci (VRE) have been isolated in increasing numbers. Hospital-adapted VRE exhibit relatively high pathogenicity by expressing factors like enterococcal surface protein (Esp), which facilitates epidemic spread. By contrast, 'community-acquired' VRE show low pathogenicity and non-epidemic features. In 2004 and 2005 an extended outbreak of VRE occurred at a university hospital in Southwestern Germany and an infection control programme was implemented to confine the outbreak. Pulsed-field gel electrophoresis (PFGE), esp PCR, multiple-locus variable number of tandem repeat analysis (MLVA), purK1 typing and multiple-locus sequence typing (MLST) were performed on representative VRE isolates. Twenty-six non-epidemic and two epidemic VRE types (MLST203, MLST280) were identified by PFGE. Seven of the non-outbreak VRE types were esp gene negative, whereas 19 non-outbreak and both epidemic VRE types were esp positive. Eight MLVA types were identified. MLVA type 1 included five PFGE types and MLVA type 159 included 16 PFGE types. Currently there is no efficient method available to identify non-epidemic VRE and avoid unnecessary isolation of patients. More than 50% non-epidemic clones were esp positive; nevertheless, esp PCR appears to be the most promising approach to identify non-epidemic VRE.

  18. University Student Online Plagiarism

    Science.gov (United States)

    Wang, Yu-mei

    2008-01-01

    This article reports a study investigating university student online plagiarism. The following questions are investigated: (a) What is the incidence of student online plagiarism? (b) What are student perceptions regarding online plagiarism? (c) Are there any differences in terms of student perceptions of online plagiarism and print plagiarism? (d)…

  19. Online Organic Chemistry

    Science.gov (United States)

    Janowicz, Philip A.

    2010-01-01

    This is a comprehensive study of the many facets of an entirely online organic chemistry course. Online homework with structure-drawing capabilities was found to be more effective than written homework. Online lecture was found to be just as effective as in-person lecture, and students prefer an online lecture format with shorter Webcasts. Online…

  20. University Student Online Plagiarism

    Science.gov (United States)

    Wang, Yu-mei

    2008-01-01

    This article reports a study investigating university student online plagiarism. The following questions are investigated: (a) What is the incidence of student online plagiarism? (b) What are student perceptions regarding online plagiarism? (c) Are there any differences in terms of student perceptions of online plagiarism and print plagiarism? (d)…

  1. Is the New Heroin Epidemic Really New? Racializing Heroin.

    Science.gov (United States)

    Bowser, Benjamin; Fullilove, Robert; Word, Carl

    2017-01-01

    Heroin abuse as an outcome of the prior use of painkillers increased rapidly over the past decade. This "new epidemic" is unique because the new heroin users are primarily young White Americans in rural areas of virtually every state. This commentary argues that the painkiller-to-heroin transition could not be the only cause of heroin use on such a scale and that the new and old heroin epidemics are linked. The social marketing that so successfully drove the old heroin epidemic has innovated and expanded due to the use of cell-phones, text messaging and the "dark web" which requires a Tor browser, and software that allows one to communicate with encrypted sites without detection. Central city gentrification has forced traffickers to take advantage of larger and more lucrative markets. A second outcome is that urban black and Latino communities are no longer needed as heroin stages areas for suburban and exurban illicit drug distribution. Drug dealing can be done directly in predominantly white suburbs and rural areas without the accompanying violence associated with the old epidemic. Denial of the link between the new and old heroin epidemics racially segregates heroin users and more proactive prevention and treatment in the new epidemic than in the old. It also cuts off a half-century of knowledge about the supply-side of heroin drug dealing and the inevitable public policy measures that will have to be implemented to effectively slow and stop both the old and new epidemic.

  2. Attitudes toward buying online.

    Science.gov (United States)

    Yang, Bijou; Lester, David

    2004-02-01

    A survey of 11 positive features and 10 discouraging features of online shopping was carried out on 180 students and identified certain behavioral patterns for online shoppers versus non-shoppers. It was found that online shoppers have consistently stronger positive feelings about online shopping than do non-shoppers. On the other hand, non-shoppers have more negative feelings about online shopping than do shoppers, but not consistently so. Online shoppers are aware of some of the discouraging features of online shopping, but these features do not deter them from shopping online. The implication for marketers is that they should focus on making the experience of online shopping more accommodating and more user-friendly since the positive features of online shopping ("convenience" and "efficiency") appear to be more important than the negative features ("effort/impersonality").

  3. SNR analysis: molecular investigation of an anthrax epidemic

    Science.gov (United States)

    2010-01-01

    Background In Italy, anthrax is endemic but occurs sporadically. During the summer of 2004, in the Pollino National Park, Basilicata, Southern Italy, an anthrax epidemic consisting of 41 outbreaks occurred; it claimed the lives of 124 animals belonging to different mammal species. This study is a retrospective molecular epidemiological investigation carried out on 53 isolates collected during the epidemic. A 25-loci Multiple Locus VNTR Analysis (MLVA) MLVA was initially performed to define genetic relationships, followed by an investigation of genetic diversity between epidemic strains through Single Nucleotide Repeat (SNR) analysis. Results 53 Bacillus anthracis strains were isolated. The 25-loci MLVA analysis identified all of them as belonging to a single genotype, while the SNR analysis was able to detect the existence of five subgenotypes (SGTs), allowing a detailed epidemic investigation. SGT-1 was the most frequent (46/53); SGTs 2 (4/53), 3 (1/53) 4 (1/53) and 5 (1/53) were detected in the remaining seven isolates. Conclusions The analysis revealed the prevalent spread, during this epidemic, of a single anthrax clone. SGT-1 - widely distributed across the epidemic area and present throughout the period in question - may, thus, be the ancestral form. SGTs 2, 3 and 4 differed from SGT-1 at only one locus, suggesting that they could have evolved directly from the latter during the course of this epidemic. SGT-5 differed from the other SGTs at 2-3 loci. This isolate, thus, appears to be more distantly related to SGT-1 and may not be a direct descendant of the lineage responsible for the majority of cases in this epidemic. These data confirm the importance of molecular typing and subtyping methods for in-depth epidemiological analyses of anthrax epidemics. PMID:20187980

  4. Can influenza epidemics be prevented by voluntary vaccination?

    Directory of Open Access Journals (Sweden)

    Raffaele Vardavas

    2007-05-01

    Full Text Available Previous modeling studies have identified the vaccination coverage level necessary for preventing influenza epidemics, but have not shown whether this critical coverage can be reached. Here we use computational modeling to determine, for the first time, whether the critical coverage for influenza can be achieved by voluntary vaccination. We construct a novel individual-level model of human cognition and behavior; individuals are characterized by two biological attributes (memory and adaptability that they use when making vaccination decisions. We couple this model with a population-level model of influenza that includes vaccination dynamics. The coupled models allow individual-level decisions to influence influenza epidemiology and, conversely, influenza epidemiology to influence individual-level decisions. By including the effects of adaptive decision-making within an epidemic model, we can reproduce two essential characteristics of influenza epidemiology: annual variation in epidemic severity and sporadic occurrence of severe epidemics. We suggest that individual-level adaptive decision-making may be an important (previously overlooked causal factor in driving influenza epidemiology. We find that severe epidemics cannot be prevented unless vaccination programs offer incentives. Frequency of severe epidemics could be reduced if programs provide, as an incentive to be vaccinated, several years of free vaccines to individuals who pay for one year of vaccination. Magnitude of epidemic amelioration will be determined by the number of years of free vaccination, an individuals' adaptability in decision-making, and their memory. This type of incentive program could control epidemics if individuals are very adaptable and have long-term memories. However, incentive-based programs that provide free vaccination for families could increase the frequency of severe epidemics. We conclude that incentive-based vaccination programs are necessary to control

  5. Online Archives

    Directory of Open Access Journals (Sweden)

    Julian D. Richards

    2004-01-01

    Full Text Available Online archives are of increasing importance in Archaeological Informatics, but like any new genre they prompt a number of questions. What is their relationship to publication? What should go in them? How should they be delivered and indexed? Can they be preserved? Whilst their delivery requires technology, we must also consider how that technology should best be employed in the service of our discipline. This article attempts to address some of these questions but it need not be read from start to finish. The links from this summary provide one fairly linear route through the text but each section is self-contained and can also be accessed directly from the Contents page. The problems posed by effective publication of archaeological fieldwork have exercised the profession for many decades. The issues raised go to the core of discussion of whether preservation by record is a valid concept, and indeed whether archaeological data exist. There are different schools of thought about the relationship between publication and archiving, but hopefully we can accept that data are recorded observations but still agree that they have a re-use value for re-examination and re-interpretation. Since the 1960s archaeology has experienced a publication crisis point. The scenario is familiar. Excavation is destruction; it is an unrepeatable experiment and the archaeologist has a professional obligation to make a full and accessible record of his/her observations. Yet full publication is increasingly expensive and difficult, and excavation monographs are read by few people, and bought by even fewer. In England the development of post-PPG16 fieldwork has exacerbated the problem by creating a mountain of unpublished grey literature and making the work of synthesis even harder; a similar situation exists in other countries. Meanwhile museum archives are also reaching breaking point; most are running out of storage space, few can provide facilities for access, and

  6. Online Shopping Behavior

    OpenAIRE

    Shahzad, Hashim

    2015-01-01

    Online shopping is a very much developed phenomena in Scandinavian countries. Different online factors impact online consumers’ behavior differently depending on the environment of different regions. Sweden is one of the developed and technologically advanced countries. To see the impact of different factors on consumers’ online shopping behavior, the purpose of this study is to analyse the factors that influence consumers’ online shopping behavior in Sweden’s context. One of the objectives o...

  7. Online Marketing Trends

    OpenAIRE

    Horecká, Ivana

    2015-01-01

    This thesis deals with online marketing trends. Its main goal is to define the latest online marketing trends, create a website with the free online marketing trends, and analyse their effectiveness. The theoretical part brings a thorough description of the latest online marketing trends. Moreover, it provides an insight into the latest trends in the website development. The chosen online marketing trends defined in the theoretical part are subsequently applied on a newly created website. All...

  8. Epidemic spreading with immunization rate on complex networks

    CERN Document Server

    Tanimoto, Shinji

    2011-01-01

    We investigate the spread of diseases, computer viruses or information on complex networks and also immunization strategies to prevent or control the spread. When an entire population cannot be immunized and the effect of immunization is not perfect, we need the targeted immunization with immunization rate. Under such a circumstance we calculate epidemic thresholds for the SIR and SIS epidemic models. It is shown that, in scale-free networks, the targeted immunization is effective only if the immunization rate is equal to one. We analyze here epidemic spreading on directed complex networks, but similar results are also valid for undirected ones.

  9. Numerical Investigation of Metrics for Epidemic Processes on Graphs

    CERN Document Server

    Goering, Max; Albin, Nathan; Scoglio, Caterina; Poggi-Corradini, Pietro

    2015-01-01

    This study develops the epidemic hitting time (EHT) metric on graphs measuring the expected time an epidemic starting at node $a$ in a fully susceptible network takes to propagate and reach node $b$. An associated EHT centrality measure is then compared to degree, betweenness, spectral, and effective resistance centrality measures through exhaustive numerical simulations on several real-world network data-sets. We find two surprising observations: first, EHT centrality is highly correlated with effective resistance centrality; second, the EHT centrality measure is much more delocalized compared to degree and spectral centrality, highlighting the role of peripheral nodes in epidemic spreading on graphs.

  10. Five challenges for stochastic epidemic models involving global transmission

    Directory of Open Access Journals (Sweden)

    Tom Britton

    2015-03-01

    Full Text Available The most basic stochastic epidemic models are those involving global transmission, meaning that infection rates depend only on the type and state of the individuals involved, and not on their location in the population. Simple as they are, there are still several open problems for such models. For example, when will such an epidemic go extinct and with what probability (questions depending on the population being fixed, changing or growing? How can a model be defined explaining the sometimes observed scenario of frequent mid-sized epidemic outbreaks? How can evolution of the infectious agent transmission rates be modelled and fitted to data in a robust way?

  11. An Epidemic of Cirrhosis in Danish Women Revisited

    DEFF Research Database (Denmark)

    Petersen, J.; Skinhøj, P.; Thorsen, Thorkil

    1986-01-01

    Between 1944 and 1947 the mortality statistics for the Danish population show an epidemic increase of liver diseases: subacute necrosis and cirrhosis. The epidemic only affected female mortality rates. Mortality due to cirrhosis remained at a higher rate for women than men until 1970 as a result...... of an excess mortality in the cohort of women who in 1945 were over the age of 45. Up to 1981 this group showed an excess of 4,000 fatalities. A reevaluation of medico-statistical data shows that the disease cannot be explained by the epidemic hepatitis occurring in 1942-1944 or by increased consumption...

  12. Periodic Wave of Epidemic Spreading in Community Networks

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yin-Zuo; LIU Zong-Hua; ZHOU Jie

    2007-01-01

    It was reported by Cummings et al. [Nature 427 (2004)344] that there are periodic waves in the spatiotemporal data of epidemics. For understanding the mechanism, we study the epidemic spreading on community networks by both the SIS model and the SIRS model. We find that with the increase of infection rate, the number of total infected nodes may be stabilized at a fixed point, oscillatory waves, and periodic cycles. Moreover, the epidemic spreading in the SIS model can be explained by an analytic map.

  13. Game Modeling Research for Urbanization and Epidemic Control

    Institute of Scientific and Technical Information of China (English)

    Bai-Da Qu

    2005-01-01

    To aid in the sustainable development of cities this paper examines methods for urbanization and epidemic control. Using, as a foundation, game theory from modern control theory, a set of strategies for modeling urbanization and epidemic control are examined by analyzing and studying the current condition of China including its population, economy,resources and city management methods. Urbanization and epidemic control solving strategies are probed and the solution to a simulated example is provided. The conclusion from this research is that the speed of Chinese urbanization should be slowed to match the condition of resources and level of city management available.

  14. AIDS epidemic runs riot in South Africa.

    Science.gov (United States)

    1997-05-27

    Based on current health surveys in South Africa, the HIV and AIDS epidemic there is spreading faster than health workers can develop a policy to combat it. 120 million male and 90,000 female condoms have been distributed to the areas that are most affected. According to Health Minister Nkosazana Zuma, the percentage of HIV-positive pregnant women in the North-West Province rose from 8.3% in 1995 to 25% in 1997. In June 1996, 1.7 million people were at risk; this number rose to 2.5 million in 1997, 90,000 of whom will develop advanced AIDS by the end of the year. According to independent researchers, 800 people are infected daily, which means that 16% of South Africa's workers are already infected. This figure could rise to 20% by the year 2000 according to Professor Ronald Green-Thompson. At that time, the cost to the South African economy would be between US$25 million and US$2.3 billion. The World Health Organization (WHO) is touring provinces for the first time to select sites for use by assessment teams in July. Dr. Liz Floyd, head of the HIV/AIDS and communicable diseases unit, states that, although US$6.1 million (US$2.3 million more than in 1996) have been designated to fight the epidemic, new measures have to be found to avoid an infection rate of 1 in 5 young women by the end of the year. The unit conducts annual surveys among women attending public prenatal clinics. Infection appears to be linked to poverty, migration, family breakdowns, and prostitution. The greatest increase has been among women aged 20-24 years. According to Floyd, "the supply of condoms is still uneven and unreliable, especially in high density peri-urban settlements and shanty towns. Primary care for the youth and home-based schemes are poorly coordinated and erratic." Zuma believes that schools should be targeted; she hopes to educate children in 7400 secondary and 13,500 primary schools. Donor agencies, churches, workers, and business people have become involved, including

  15. Epidemic model for information diffusion in web forums: experiments in marketing exchange and political dialog.

    Science.gov (United States)

    Woo, Jiyoung; Chen, Hsinchun

    2016-01-01

    As social media has become more prevalent, its influence on business, politics, and society has become significant. Due to easy access and interaction between large numbers of users, information diffuses in an epidemic style on the web. Understanding the mechanisms of information diffusion through these new publication methods is important for political and marketing purposes. Among social media, web forums, where people in online communities disseminate and receive information, provide a good environment for examining information diffusion. In this paper, we model topic diffusion in web forums using the epidemiology model, the susceptible-infected-recovered (SIR) model, frequently used in previous research to analyze both disease outbreaks and knowledge diffusion. The model was evaluated on a large longitudinal dataset from the web forum of a major retail company and from a general political discussion forum. The fitting results showed that the SIR model is a plausible model to describe the diffusion process of a topic. This research shows that epidemic models can expand their application areas to topic discussion on the web, particularly social media such as web forums.

  16. The initial hospital response to an epidemic.

    Science.gov (United States)

    Petrosillo, Nicola; Puro, Vincenzo; Di Caro, Antonino; Ippolito, Giuseppe

    2005-01-01

    The last decades have been characterized by the appearance of a substantial number of newly recognized or novel infectious agents and by the re-emergence of infectious diseases with a global impact. The objective of this article is to briefly describe the model of hospital response for early diagnosis and prompt management of patients with highly contagious infectious diseases. We reviewed the main components of hospital preparedness in response to clustering of highly contagious diseases. A model for the initial hospital response to an epidemic in our referral Institute is discussed. Prompt recognition and identification is the initial and indispensable step in facing any communicable diseases, regardless of whether it is a prevalent, a newly emerging one or deliberately released. The importance of developing and implementing nontraditional methods of public health surveillance and a system that allows a wide and immediate dissemination of information and exchange of views on risk assessment and risk management are highlighted. Case identification and laboratory capabilities and isolation procedures are the essential components for an initial hospital response. The recent bioterrorist events and the worldwide outbreaks of highly contagious infectious diseases have evidenced the need for institutional preparedness at each hospital and for identification of referral centers for patient isolation and of laboratories with adequate capabilities. Moreover, hospitals should develop a plan for coordinating all hospital components to respond to critical situations deriving from the admission of patients with highly contagious infectious diseases.

  17. MICROSPORUM CANIS RINGWORM EPIDEMIC IN TEHRAN

    Directory of Open Access Journals (Sweden)

    M.Emami

    1982-09-01

    Full Text Available Twenty Patients, a family, their neighbors, and friends; with lesions suspicious of Ringworm infection, were referred to us within a period of 80 days. The Source of infection was found to be 3 persian Cats (a mother and two kittens living with the family. The cats had multiple lesions around their nose and on abdomen which reveales the Prevalence of cutaneous fungi both on direct microscopic examination and culture. Sixteen of the 20 pateints examined 80% were positive both in Microscopic examination and culture. The rest were negative because they have used topical and systemic antifungal drugs. Of these positives 12(75% had Tinea corporis and 4(25% had Tinea capitis. The ege range of the patients with Tinea corporis was 2-9 years and for those with Tinea corpois was 5- 48 years. The causative agent in this epidemic was Microsporum canis which was most probably transmitted from the cats to this family, their friends and neighbors.

  18. Diabetes mellitus: The epidemic of the century

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The epidemic nature of diabetes mellitus in differentregions is reviewed. The Middle East and North Africaregion has the highest prevalence of diabetes inadults (10.9%) whereas, the Western Pacific regionhas the highest number of adults diagnosed withdiabetes and has countries with the highest prevalenceof diabetes (37.5%). Different classes of diabetesmellitus, type 1, type 2, gestational diabetes and othertypes of diabetes mellitus are compared in terms ofdiagnostic criteria, etiology and genetics. The moleculargenetics of diabetes received extensive attention inrecent years by many prominent investigators andresearch groups in the biomedical field. A large arrayof mutations and single nucleotide polymorphismsin genes that play a role in the various steps andpathways involved in glucose metabolism and thedevelopment, control and function of pancreatic cellsat various levels are reviewed. The major advances inthe molecular understanding of diabetes in relation tothe different types of diabetes in comparison to theprevious understanding in this field are briefly reviewedhere. Despite the accumulation of extensive data atthe molecular and cellular levels, the mechanism ofdiabetes development and complications are still notfully understood. Definitely, more extensive researchis needed in this field that will eventually reflect onthe ultimate objective to improve diagnoses, therapyand minimize the chance of chronic complicationsdevelopment.

  19. Impact of the obesity epidemic on cancer.

    Science.gov (United States)

    Goodwin, Pamela J; Stambolic, Vuk

    2015-01-01

    There is growing appreciation that the current obesity epidemic is associated with increases in cancer incidence at a population level and may lead to poor cancer outcomes; concurrent decreases in cancer mortality at a population level may represent a paradox, i.e., they may also reflect improvements in the diagnosis and treatment of cancer that mask obesity effects. An association of obesity with cancer is biologically plausible because adipose tissue is biologically active, secreting estrogens, adipokines, and cytokines. In obesity, adipose tissue reprogramming may lead to insulin resistance, with or without diabetes, and it may contribute to cancer growth and progression locally or through systemic effects. Obesity-associated changes impact cancer in a complex fashion, potentially acting directly on cells through pathways, such as the phosphoinositide 3-kinase (PI3K) and Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways, or indirectly via changes in the tumor microenvironment. Approaches to obesity management are discussed, and the potential for pharmacologic interventions that target the obesity-cancer link is addressed.

  20. Epidemic spreading on evolving signed networks

    Science.gov (United States)

    Saeedian, M.; Azimi-Tafreshi, N.; Jafari, G. R.; Kertesz, J.

    2017-02-01

    Most studies of disease spreading consider the underlying social network as obtained without the contagion, though epidemic influences people's willingness to contact others: A "friendly" contact may be turned to "unfriendly" to avoid infection. We study the susceptible-infected disease-spreading model on signed networks, in which each edge is associated with a positive or negative sign representing the friendly or unfriendly relation between its end nodes. In a signed network, according to Heider's theory, edge signs evolve such that finally a state of structural balance is achieved, corresponding to no frustration in physics terms. However, the danger of infection affects the evolution of its edge signs. To describe the coupled problem of the sign evolution and disease spreading, we generalize the notion of structural balance by taking into account the state of the nodes. We introduce an energy function and carry out Monte Carlo simulations on complete networks to test the energy landscape, where we find local minima corresponding to the so-called jammed states. We study the effect of the ratio of initial friendly to unfriendly connections on the propagation of disease. The steady state can be balanced or a jammed state such that a coexistence occurs between susceptible and infected nodes in the system.

  1. SIS Epidemic Spreading with Heterogeneous Infection Rates

    CERN Document Server

    Qu, Bo

    2015-01-01

    In this work, we aim to understand the influence of the heterogeneity of infection rates on the Susceptible-Infected-Susceptible (SIS) epidemic spreading. Specifically, we keep the recovery rates the same for all nodes and study the influence of the moments of the independently identically distributed (i.i.d.) infection rates on the average fraction $y_\\infty$ of infected nodes in the meta-stable state, which indicates the severity of the overall infection. Motivated by real-world datasets, we consider the log-normal and gamma distributions for the infection rates and we design as well a symmetric distribution so that we have a systematic view of the influence of various distributions. By continuous-time simulations on several types of networks, theoretical proofs and physical interpretations, we conclude that: 1) the heterogeneity of infection rates on average retards the virus spread, and 2) a larger even-order moment of the infection rates leads to a smaller average fraction of infected nodes, but the odd-...

  2. Tuberculosis and Cardiovascular Disease: Linking the Epidemics.

    Science.gov (United States)

    Huaman, Moises A; Henson, David; Ticona, Eduardo; Sterling, Timothy R; Garvy, Beth A

    The burden of tuberculosis and cardiovascular disease (CVD) is enormous worldwide. CVD rates are rapidly increasing in low- and middle-income countries. Public health programs have been challenged with the overlapping tuberculosis and CVD epidemics. Monocyte/macrophages, lymphocytes and cytokines involved in cellular mediated immune responses against Mycobacterium tuberculosis are also main drivers of atherogenesis, suggesting a potential pathogenic role of tuberculosis in CVD via mechanisms that have been described for other pathogens that establish chronic infection and latency. Studies have shown a pro-atherogenic effect of antibody-mediated responses against mycobacterial heat shock protein-65 through cross reaction with self-antigens in human vessels. Furthermore, subsets of mycobacteria actively replicate during latent tuberculosis infection (LTBI), and recent studies suggest that LTBI is associated with persistent chronic inflammation that may lead to CVD. Recent epidemiologic work has shown that the risk of CVD in persons who develop tuberculosis is higher than in persons without a history of tuberculosis, even several years after recovery from tuberculosis. Together, these data suggest that tuberculosis may play a role in the pathogenesis of CVD. Further research to investigate a potential link between tuberculosis and CVD is warranted.

  3. Current Zika virus epidemiology and recent epidemics.

    Science.gov (United States)

    Ioos, S; Mallet, H-P; Leparc Goffart, I; Gauthier, V; Cardoso, T; Herida, M

    2014-07-01

    The Zika virus (ZIKV) is a mosquito-borne flavivirus (Aedes), similar to other arboviruses, first identified in Uganda in 1947. Few human cases were reported until 2007, when a Zika outbreak occurred in Yap, Micronesia, even though ZIKV activity had been reported in Africa and in Asia through virological surveillance and entomological studies. French Polynesia has recorded a large outbreak since October 2013. A great number of cases and some with neurological and autoimmune complications have been reported in a context of concurrent circulation of dengue viruses. The clinical presentation is a "dengue-like syndrome". Until the epidemic in French Polynesia, no severe ZIKV disease had been described so far. The diagnosis is confirmed by viral genome detection by genomic amplification (RT- PCR) and viral isolation. These two large outbreaks occurred in a previously unaffected area in less than a decade. They should raise awareness as to the potential for ZIKV to spread especially since this emergent disease is not well known and that some questions remain on potential reservoirs and transmission modes as well as on clinical presentations and complications. ZIKV has the potential to spread to new areas where the Aedes mosquito vector is present and could be a risk for Southern Europe. Strategies for the prevention and control of ZIKV disease should include the use of insect repellent and mosquito vector eradication.

  4. Systemic calicivirus epidemic in captive exotic felids.

    Science.gov (United States)

    Harrison, Tara M; Sikarskie, James; Kruger, John; Wise, Annabel; Mullaney, Thomas P; Kiupel, Matti; Maes, Roger K

    2007-06-01

    A 5-day-old, mother-raised, Amur tiger cub (Panthera tigris altaica) presented with tongue ulcerations. Identical lesions appeared and progressed to sloughing of the tongue in the three littermates of this cub the following day. The lesions progressed in all cubs to include sloughing of the carpal, tarsal, metacarpal, and metatarsal foot pad epithelium. Oral ulcerations were also noted in adult African lions (Panthera leo) and Amur tigers (Panthera tigris altaica), but not in two adult snow leopards (Panthera uncia) housed in the same building. All adult cats had been previously vaccinated for common feline diseases including feline calicivirus (FCV). Detection of FCV RNA in oral secretions by a real-time reverse transcription polymerase chain reaction assay (RRT-PCR) confirmed FCV infection in the tiger cubs and one lion. A male lion and a male tiger cub died during the disease outbreak. RRT-PCR confirmed FCV in multiple tissues in both of these animals. A stray cat live-trapped outside the feline building during the epidemic was found to be positive for FCV by virus isolation and was thought to be the source of infection.

  5. Spatially explicit modelling of cholera epidemics

    Science.gov (United States)

    Finger, F.; Bertuzzo, E.; Mari, L.; Knox, A. C.; Gatto, M.; Rinaldo, A.

    2013-12-01

    Epidemiological models can provide crucial understanding about the dynamics of infectious diseases. Possible applications range from real-time forecasting and allocation of health care resources to testing alternative intervention mechanisms such as vaccines, antibiotics or the improvement of sanitary conditions. We apply a spatially explicit model to the cholera epidemic that struck Haiti in October 2010 and is still ongoing. The dynamics of susceptibles as well as symptomatic and asymptomatic infectives are modelled at the scale of local human communities. Dissemination of Vibrio cholerae through hydrological transport and human mobility along the road network is explicitly taken into account, as well as the effect of rainfall as a driver of increasing disease incidence. The model is calibrated using a dataset of reported cholera cases. We further model the long term impact of several types of interventions on the disease dynamics by varying parameters appropriately. Key epidemiological mechanisms and parameters which affect the efficiency of treatments such as antibiotics are identified. Our results lead to conclusions about the influence of different intervention strategies on the overall epidemiological dynamics.

  6. Epidemic spreading on random surfer networks with infected avoidance strategy

    Science.gov (United States)

    Feng, Yun; Ding, Li; Huang, Yun-Han; Guan, Zhi-Hong

    2016-12-01

    In this paper, we study epidemic spreading on random surfer networks with infected avoidance (IA) strategy. In particular, we consider that susceptible individuals’ moving direction angles are affected by the current location information received from infected individuals through a directed information network. The model is mainly analyzed by discrete-time numerical simulations. The results indicate that the IA strategy can restrain epidemic spreading effectively. However, when long-distance jumps of individuals exist, the IA strategy’s effectiveness on restraining epidemic spreading is heavily reduced. Finally, it is found that the influence of the noises from information transferring process on epidemic spreading is indistinctive. Project supported in part by the National Natural Science Foundation of China (Grant Nos. 61403284, 61272114, 61673303, and 61672112) and the Marine Renewable Energy Special Fund Project of the State Oceanic Administration of China (Grant No. GHME2013JS01).

  7. Enhancing risk communication for more effective epidemic control in Taiwan.

    Science.gov (United States)

    Ou, Shih-Ming; Liu, Li-Ling; Chin, Ko-Chien

    2014-01-01

    This article investigates how to more effectively conduct risk communication to increase the probability of successful control of an epidemic in Taiwan. The epidemic control of H1N1 in Taiwan in 2010 was studied. We used factor analysis and Decision-Making Trial and Evaluation Laboratory (DEMATEL) to obtain the total influence for each factor and to determine the critical factors among them. After being processed using proposed operational procedures, we obtained the critical factors and found that the government plays the key role in successful epidemic control. To reduce the resistance to efforts that seek to prevent pandemic crises, some necessary intervention activities, such as fairly and honorably exploring the complete relevant information and revealing the side effects of vaccines in a manner that is easily understood, were recommended. These could lead to an increase in immunizations among Taiwanese people by gaining their trust and commitment, thus achieving control of this epidemic.

  8. Large epidemic thresholds emerge in heterogeneous networks of heterogeneous nodes

    CERN Document Server

    Yang, Hui; Gross, Thilo

    2015-01-01

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that heterogeneity can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. Here, we point out that for real world applications, this result should not be regarded independently of the intra-individual heterogeneity between people. Our results show that, if heterogeneity among people is taken into account, networks that are more heterogeneous in connectivity can be more resistant to epidemic spreading. We study a susceptible-infected-susceptible model with adaptive disease avoidance. Results from this model suggest that this reversal of the effect of network heterogeneity is likely to occur in populations in which the individuals are aware of t...

  9. Epidemic spreading in time-varying community networks

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guangming, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [School of Electronic and Information, Guangdong Polytechnic Normal University, Guangzhou 510665 (China); Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2014-06-15

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q{sub c}. The epidemic will survive when q > q{sub c} and die when q < q{sub c}. These results can help understanding the impacts of human travel on the epidemic spreading in complex networks with community structure.

  10. [Hippocrates. Aphorisms and Epidemics III. Two clinical texts].

    Science.gov (United States)

    Frøland, Anders

    2015-01-01

    The two Hippocratic texts, Aphorisms and Epidemics III, have not been translated into Danish previously. The Aphorisms are 412 short, pithy statements, mostly on the prognosis in relation to certain symptoms in the course of the diseases, very often febrile. The Aphorisms begin with the famous words: "Life is short, the Art long, opportunity fleeting, experiment treacherous, judgment difficult." (Transl. W H S Jones [22]). Epidemics III consists of 28 case histories, again mostly of febrile patients, but also of observations on the connection of the seasons with general morbidity and mortality. The author describes an epidemic, which in some respects resembles Thucydides' report on the plague in Athens in 430 BC. It is suggested, that observations as have been recorded in the seven Hippocratic texts on epidemic diseases are the material on which prognostic statements as those collected in the Aphorisms are founded.

  11. [Epidemics and disease during the Revolution Period in Mexico].

    Science.gov (United States)

    Sanfilippo-Borrás, José

    2010-01-01

    The health condition in Mexico was bad around de beginning of the revolutionary period. The movement of troops led the development of epidemics like yellow fever, typhus, smallpox, and influenza that were enhance with natural disasters and hunger in whole country, from cost to cost and in the north big cities like Monterrey, Guadalajara and Saltillo. Doctor Liceaga conducted a well planned campaign against yellow fever eradicating water stagnant deposits in order to combat the vector transmission, the Aedes aegypti, mosquito with satisfactory results. The first smallpox epidemic in the XX Century in Mexico was in 1916. The Mexican physicians used the smallpox vaccine against this epidemic. An American physician named Howard Taylor Ricketts arrived to Mexico for studying the typhus transmission. Accidentally he had been infected and finally, he died from typhus. Definitively, the epidemics predominate along de revolutionary period in Mexico.

  12. Drought and epidemic typhus, central Mexico, 1655-1918.

    Science.gov (United States)

    Burns, Jordan N; Acuna-Soto, Rudofo; Stahle, David W

    2014-03-01

    Epidemic typhus is an infectious disease caused by the bacterium Rickettsia prowazekii and transmitted by body lice (Pediculus humanus corporis). This disease occurs where conditions are crowded and unsanitary. This disease accompanied war, famine, and poverty for centuries. Historical and proxy climate data indicate that drought was a major factor in the development of typhus epidemics in Mexico during 1655-1918. Evidence was found for 22 large typhus epidemics in central Mexico, and tree-ring chronologies were used to reconstruct moisture levels over central Mexico for the past 500 years. Below-average tree growth, reconstructed drought, and low crop yields occurred during 19 of these 22 typhus epidemics. Historical documents describe how drought created large numbers of environmental refugees that fled the famine-stricken countryside for food relief in towns. These refugees often ended up in improvised shelters in which crowding encouraged conditions necessary for spread of typhus.

  13. Unification of theoretical approaches for epidemic spreading on complex networks

    Science.gov (United States)

    Wang, Wei; Tang, Ming; Stanley, H. Eugene; Braunstein, Lidia A.

    2017-03-01

    Models of epidemic spreading on complex networks have attracted great attention among researchers in physics, mathematics, and epidemiology due to their success in predicting and controlling scenarios of epidemic spreading in real-world scenarios. To understand the interplay between epidemic spreading and the topology of a contact network, several outstanding theoretical approaches have been developed. An accurate theoretical approach describing the spreading dynamics must take both the network topology and dynamical correlations into consideration at the expense of increasing the complexity of the equations. In this short survey we unify the most widely used theoretical approaches for epidemic spreading on complex networks in terms of increasing complexity, including the mean-field, the heterogeneous mean-field, the quench mean-field, dynamical message-passing, link percolation, and pairwise approximation. We build connections among these approaches to provide new insights into developing an accurate theoretical approach to spreading dynamics on complex networks.

  14. Modeling and Analysis of Epidemic Diffusion with Population Migration

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2013-01-01

    Full Text Available An improved Susceptible-Infected-Susceptible (SIS epidemic diffusion model with population migration between two cities is modeled. Global stability conditions for both the disease-free equilibrium and the endemic equilibrium are analyzed and proved. The main contribution of this paper is reflected in epidemic modeling and analysis which considers unequal migration rates, and only susceptible individuals can migrate between the two cities. Numerical simulation shows when the epidemic diffusion system is stable, number of infected individuals in one city can reach zero, while the number of infected individuals in the other city is still positive. On the other hand, decreasing population migration in only one city seems not as effective as improving the recovery rate for controlling the epidemic diffusion.

  15. Obesity and kidney disease: hidden consequences of the epidemic

    African Journals Online (AJOL)

    Obesity has become a worldwide epidemic, and its prevalence has been projected to ... Keywords: chronic kidney disease, kidney cancer, nephrolithiasis, obesity, prevention ... kidney disease on the occasion of the 2017 World Kidney Day.

  16. Effects of active links on epidemic transmission over social networks

    Science.gov (United States)

    Zhu, Guanghu; Chen, Guanrong; Fu, Xinchu

    2017-02-01

    A new epidemic model with two infection periods is developed to account for the human behavior in social network, where newly infected individuals gradually restrict most of future contacts or are quarantined, causing infectivity change from a degree-dependent form to a constant. The corresponding dynamics are formulated by a set of ordinary differential equations (ODEs) via mean-field approximation. The effects of diverse infectivity on the epidemic dynamics ​are examined, with a behavioral interpretation of the basic reproduction number. Results show that such simple adaptive reactions largely determine the impact of network structure on epidemics. Particularly, a theorem proposed by Lajmanovich and Yorke in 1976 is generalized, so that it can be applied for the analysis of the epidemic models with multi-compartments especially network-coupled ODE systems.

  17. Topology dependent epidemic spreading velocity in weighted networks

    Science.gov (United States)

    Duan, Wei; Quax, Rick; Lees, Michael; Qiu, Xiaogang; Sloot, Peter M. A.

    2014-12-01

    Many diffusive processes occur on structured networks with weighted links, such as disease spread by airplane transport or information diffusion in social networks or blogs. Understanding the impact of weight-connectivity correlations on epidemic spreading in weighted networks is crucial to support decision-making on disease control and other diffusive processes. However, a real understanding of epidemic spreading velocity in weighted networks is still lacking. Here we conduct a numerical study of the velocity of a Reed-Frost epidemic spreading process in various weighted network topologies as a function of the correlations between edge weights and node degrees. We find that a positive weight-connectivity correlation leads to a faster epidemic spreading compared to an unweighted network. In contrast, we find that both uncorrelated and negatively correlated weight distributions lead to slower spreading processes. In the case of positive weight-connectivity correlations, the acceleration of spreading velocity is weak when the heterogeneity of weight distribution increases.

  18. Stochastic population and epidemic models persistence and extinction

    CERN Document Server

    Allen, Linda J S

    2015-01-01

    This monograph provides a summary of the basic theory of branching processes for single-type and multi-type processes. Classic examples of population and epidemic models illustrate the probability of population or epidemic extinction obtained from the theory of branching processes. The first chapter develops the branching process theory, while in the second chapter two applications to population and epidemic processes of single-type branching process theory are explored. The last two chapters present multi-type branching process applications to epidemic models, and then continuous-time and continuous-state branching processes with applications. In addition, several MATLAB programs for simulating stochastic sample paths  are provided in an Appendix. These notes originated as part of a lecture series on Stochastics in Biological Systems at the Mathematical Biosciences Institute in Ohio, USA. Professor Linda Allen is a Paul Whitfield Horn Professor of Mathematics in the Department of Mathematics and Statistics ...

  19. Interactions among symbionts operate across scales to influence parasite epidemics.

    Science.gov (United States)

    Halliday, Fletcher W; Umbanhowar, James; Mitchell, Charles E

    2017-10-01

    Parasite epidemics may be influenced by interactions among symbionts, which can depend on past events at multiple spatial scales. Within host individuals, interactions can depend on the sequence in which symbionts infect a host, generating priority effects. Across host individuals, interactions can depend on parasite phenology. To test the roles of parasite interactions and phenology in epidemics, we embedded multiple cohorts of sentinel plants, grown from seeds with and without a vertically transmitted symbiont, into a wild host population, and tracked foliar infections caused by three common fungal parasites. Within hosts, parasite growth was influenced by coinfections, but coinfections were often prevented by priority effects among symbionts. Across hosts, parasite phenology altered host susceptibility to secondary infections, symbiont interactions and ultimately the magnitude of parasite epidemics. Together, these results indicate that parasite phenology can influence parasite epidemics by altering the sequence of infection and interactions among symbionts within host individuals. © 2017 John Wiley & Sons Ltd/CNRS.

  20. The HIV-1 Epidemic: Low- to Middle-Income Countries

    Science.gov (United States)

    Shao, Yiming; Williamson, Carolyn

    2012-01-01

    Low- to middle-income countries bear the overwhelming burden of the human immunodeficiency virus type 1 (HIV-1) epidemic in terms of the numbers of their citizens living with HIV/AIDS (acquired immunodeficiency syndrome), the high degrees of viral diversity often involving multiple HIV-1 clades circulating within their populations, and the social and economic factors that compromise current control measures. Distinct epidemics have emerged in different geographical areas. These epidemics differ in their severity, the population groups they affect, their associated risk behaviors, and the viral strains that drive them. In addition to inflicting great human cost, the high burden of HIV infection has a major impact on the social and economic development of many low- to middle-income countries. Furthermore, the high degrees of viral diversity associated with multiclade HIV epidemics impacts viral diagnosis and pathogenicity and treatment and poses daunting challenges for effective vaccine development. PMID:22393534

  1. Influence of periodic traffic congestion on epidemic spreading

    Science.gov (United States)

    Zheng, Muhua; Ruan, Zhongyuan; Tang, Ming; Do, Younghae; Liu, Zonghua

    2016-11-01

    In the metropolis, traffic congestion has become a very serious problem, especially in rush hours. This congestion causes people to have more chance to contact each other and thus will accelerate epidemic spreading. To explain this observation, we present a reaction-diffusion (RD) model with a periodic varying diffusion rate to represent the daily traveling behaviors of human beings and its influence to epidemic spreading. By extensive numerical simulations, we find that the epidemic spreading can be significantly influenced by traffic congestion where the amplitude, period and duration of diffusion rate are the three key parameters. Furthermore, a brief theory is presented to explain the effects of the three key parameters. These findings suggest that except the normal ways of controlling contagion in working places and long-distance traveling, controlling the contagion in daily traffic congestion may be another effective way to reduce epidemic spreading.

  2. The effect of risk-taking behaviour in epidemic models.

    Science.gov (United States)

    Sega, L; Maxin, D; Eaton, L; Latham, A; Moose, A; Stenslie, S

    2015-01-01

    We study an epidemic model that incorporates risk-taking behaviour as a response to a perceived low prevalence of infection that follows from the administration of an effective treatment or vaccine. We assume that knowledge about the number of infected, recovered and vaccinated individuals has an effect in the contact rate between susceptible and infectious individuals. We show that, whenever optimism prevails in the risk behaviour response, the fate of an epidemic may change from disease clearance to disease persistence. Moreover, under certain conditions on the parameters, increasing the efficiency of vaccine and/or treatment has the unwanted effect of increasing the epidemic reproductive number, suggesting a wider range of diseases may become endemic due to risk-taking alone. These results indicate that the manner in which treatment/vaccine effectiveness is advertised can have an important influence on how the epidemic unfolds.

  3. Variations in epidemic distribution with some characteristic parameters

    Institute of Scientific and Technical Information of China (English)

    Liu Zhen-Zhen; Wang Xing-Yuan; Wang Mao-Ji

    2012-01-01

    Considering the spread of an epidemic among a population of mobile agents that can get infected and maintain the infection for a period,we investigate the variation in the homogeneity of the distribution of the epidemic with the remaining time of infection τ,the velocity modulus of the agent υ,and the infection rate α.We find that the distribution of the infected cluster size is always exponential.By analyzing the variation of the characteristic infected cluster size coefficient,we show that the inhomogeneity of epidemic distribution increases with an increase in τ for very low υ,while it decreases with an increase in τ for moderate υ.The epidemic distribution also tends to a homogeneous state as both υ and α increase.

  4. Epidemic spreading behavior in local-world evolving networks

    Institute of Scientific and Technical Information of China (English)

    Chengyi Xia; Zhongxin Liu; Zengqiang Chen; Shiwen Sun; Zhuzhi Yuan

    2008-01-01

    The susceptible-infected-susceptible (SIS) epidemic model is presented which can be used to study the epidemic spreading behavior in the local-world evolving network model. Local-world evolving model displays a transition from the exponential network to the scale-free network with respect to the connectivity distribution. From theoretical analyses and numerical simulations, we find that the epidemic spreading behavior on local-world networks also takes on some kind of transitional behaviors. The transitional behavior is further verified by comparing the spreading behavior of local-world network with that of random and scale-free networks. Some feasible control strategies are also proposed to keep from the epidemic spreading on networks.

  5. Dynamics of epidemic diseases on a growing adaptive network

    Science.gov (United States)

    Demirel, Güven; Barter, Edmund; Gross, Thilo

    2017-02-01

    The study of epidemics on static networks has revealed important effects on disease prevalence of network topological features such as the variance of the degree distribution, i.e. the distribution of the number of neighbors of nodes, and the maximum degree. Here, we analyze an adaptive network where the degree distribution is not independent of epidemics but is shaped through disease-induced dynamics and mortality in a complex interplay. We study the dynamics of a network that grows according to a preferential attachment rule, while nodes are simultaneously removed from the network due to disease-induced mortality. We investigate the prevalence of the disease using individual-based simulations and a heterogeneous node approximation. Our results suggest that in this system in the thermodynamic limit no epidemic thresholds exist, while the interplay between network growth and epidemic spreading leads to exponential networks for any finite rate of infectiousness when the disease persists.

  6. Drought and Epidemic Typhus, Central Mexico, 1655–1918

    Science.gov (United States)

    Acuna-Soto, Rudofo; Stahle, David W.

    2014-01-01

    Epidemic typhus is an infectious disease caused by the bacterium Rickettsia prowazekii and transmitted by body lice (Pediculus humanus corporis). This disease occurs where conditions are crowded and unsanitary. This disease accompanied war, famine, and poverty for centuries. Historical and proxy climate data indicate that drought was a major factor in the development of typhus epidemics in Mexico during 1655–1918. Evidence was found for 22 large typhus epidemics in central Mexico, and tree-ring chronologies were used to reconstruct moisture levels over central Mexico for the past 500 years. Below-average tree growth, reconstructed drought, and low crop yields occurred during 19 of these 22 typhus epidemics. Historical documents describe how drought created large numbers of environmental refugees that fled the famine-stricken countryside for food relief in towns. These refugees often ended up in improvised shelters in which crowding encouraged conditions necessary for spread of typhus. PMID:24564928

  7. Underrecognition of Dengue during 2013 Epidemic in Luanda, Angola.

    Science.gov (United States)

    Sharp, Tyler M; Moreira, Rosa; Soares, Maria José; Miguel da Costa, Lúis; Mann, Jennifer; DeLorey, Mark; Hunsperger, Elizabeth; Muñoz-Jordán, Jorge L; Colón, Candimar; Margolis, Harold S; de Caravalho, Adelaide; Tomashek, Kay M

    2015-08-01

    During the 2013 dengue epidemic in Luanda, Angola, 811 dengue rapid diagnostic test-positive cases were reported to the Ministry of Health. To better understand the magnitude of the epidemic and identify risk factors for dengue virus (DENV) infection, we conducted cluster surveys around households of case-patients and randomly selected households 6 weeks after the peak of the epidemic. Of 173 case cluster participants, 16 (9%) exhibited evidence of recent DENV infection. Of 247 random cluster participants, 25 (10%) had evidence of recent DENV infection. Of 13 recently infected participants who had a recent febrile illness, 7 (54%) had sought medical care, and 1 (14%) was hospitalized with symptoms consistent with severe dengue; however, none received a diagnosis of dengue. Behavior associated with protection from DENV infection included recent use of mosquito repellent or a bed net. These findings suggest that the 2013 dengue epidemic was larger than indicated by passive surveillance data.

  8. SIR epidemics with multiple seeds percolate without outbreaks

    CERN Document Server

    Hasegawa, Takehisa

    2015-01-01

    We study a susceptible-infected-removed (SIR) model with multiple seeds on a random regular graph. Many researchers have studied the epidemic threshold of epidemic models above which a global outbreak can occur, starting from an infinitesimal fraction of seeds. However, there have been few studies on the epidemic models with finite fractions of seeds. The aim of this paper is to clarify what happens on phase transitions in such cases. The SIR model on networks exhibits two percolation transitions. We derive the percolation transition points for the SIR model with multiple seeds to show that as the infection rate increases epidemic clusters generated from each seed percolate before a single seed can induce a global outbreak.

  9. Epidemic spreading in interconnected networks: a continuous time approach

    CERN Document Server

    de Arruda, Guilherme Ferraz; Peixoto, Tiago P; Rodrigues, Francisco A; Moreno, Yamir

    2015-01-01

    We present a continuous formulation of epidemic spreading on interconnected networks using a tensorial notation, extending the models of monoplex networks to this context. We derive analytical expressions for the epidemic threshold on the SIS and SIR dynamics, as well as upper and lower bounds for the steady-state. Using the quasi-stationary state (QS) method we show the emergence of two or more phase transitions, and propose an analytical and numerical analysis based on the inverse participation ratio. Furthermore, when mapping the critical epidemic dynamics to the eigenvalue problem, we observe a characteristic transition in the eigenvalue spectra of the supra-contact tensor as a function of the ratio of spreading rates: If the spreading rate within each layer is comparable to the rate across layers, the individual spectra of each layer merge with the coupling between layers. Our formalism provides a mathematical approach to epidemic spreading in multiplex systems and our results reinforce the importance of...

  10. A SIRS epidemic model with infection-age dependence

    Science.gov (United States)

    Zhang, Zhonghua; Peng, Jigen

    2007-07-01

    Based on J. Mena-Lorca and H.W. Hethcote's epidemic model, a SIRS epidemic model with infection-age-dependent infectivity and general nonlinear contact rate is formulated. Under general conditions, the unique existence of its global positive solutions is obtained. Moreover, under more general assumptions than the existing, the existence and asymptotical stability of its equilibria are discussed. In the end, the condition on the stability of endemic equilibrium is verified by a special model.

  11. Differentiation in online retailing

    DEFF Research Database (Denmark)

    Kellner, Julian; Wagner, Gerhard; Zielke, Stephan;

    Due to the highly competitive nature of the online retail environment, differentiation strategies are of importance for online retailers to gain competitive advantages and to achieve a unique positioning in the market. However, little is known about perceptual dimensions used by consumers to make...... a distinction between online retailers. The present study addresses this research gap by using a repertory grid approach to identify points of difference between online retailers from a consumer’s perspective. The results have important implications for positioning strategies of online retailers and research...... on online store formats....

  12. Mathematical models to characterize early epidemic growth: A review

    Science.gov (United States)

    Chowell, Gerardo; Sattenspiel, Lisa; Bansal, Shweta; Viboud, Cécile

    2016-09-01

    There is a long tradition of using mathematical models to generate insights into the transmission dynamics of infectious diseases and assess the potential impact of different intervention strategies. The increasing use of mathematical models for epidemic forecasting has highlighted the importance of designing reliable models that capture the baseline transmission characteristics of specific pathogens and social contexts. More refined models are needed however, in particular to account for variation in the early growth dynamics of real epidemics and to gain a better understanding of the mechanisms at play. Here, we review recent progress on modeling and characterizing early epidemic growth patterns from infectious disease outbreak data, and survey the types of mathematical formulations that are most useful for capturing a diversity of early epidemic growth profiles, ranging from sub-exponential to exponential growth dynamics. Specifically, we review mathematical models that incorporate spatial details or realistic population mixing structures, including meta-population models, individual-based network models, and simple SIR-type models that incorporate the effects of reactive behavior changes or inhomogeneous mixing. In this process, we also analyze simulation data stemming from detailed large-scale agent-based models previously designed and calibrated to study how realistic social networks and disease transmission characteristics shape early epidemic growth patterns, general transmission dynamics, and control of international disease emergencies such as the 2009 A/H1N1 influenza pandemic and the 2014-2015 Ebola epidemic in West Africa.

  13. The impact of vaccine success and awareness on epidemic dynamics

    Science.gov (United States)

    Juang, Jonq; Liang, Yu-Hao

    2016-11-01

    The role of vaccine success is introduced into an epidemic spreading model consisting of three states: susceptible, infectious, and vaccinated. Moreover, the effect of three types, namely, contact, local, and global, of infection awareness and immunization awareness is also taken into consideration. The model generalizes those considered in Pastor-Satorras and Vespignani [Phys. Rev. E 63, 066117 (2001)], Pastor-Satorras and Vespignani [Phys. Rev. E 65, 036104 (2002)], Moreno et al. [Eur. Phys. J. B 26, 521-529 (2002)], Wu et al. [Chaos 22, 013101 (2012)], and Wu et al. [Chaos 24, 023108 (2014)]. Our main results contain the following. First, the epidemic threshold is explicitly obtained. In particular, we show that, for any initial conditions, the epidemic eventually dies out regardless of what other factors are whenever some type of immunization awareness is considered, and vaccination has a perfect success. Moreover, the threshold is independent of the global type of awareness. Second, we compare the effect of contact and local types of awareness on the epidemic thresholds between heterogeneous networks and homogeneous networks. Specifically, we find that the epidemic threshold for the homogeneous network can be lower than that of the heterogeneous network in an intermediate regime for intensity of contact infection awareness while it is higher otherwise. In summary, our results highlight the important and crucial roles of both vaccine success and contact infection awareness on epidemic dynamics.

  14. Parasite transmission in social interacting hosts: Monogenean epidemics in guppies

    Science.gov (United States)

    Johnson, Mirelle B.; Lafferty, Kevin D.; van Oosterhout, Cock; Cable, Joanne

    2011-01-01

    Background Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. Methodology/Principal Findings Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata). Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria), and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. Conclusions/Significance These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

  15. A simple model for behaviour change in epidemics

    Directory of Open Access Journals (Sweden)

    Brauer Fred

    2011-02-01

    Full Text Available Abstract Background People change their behaviour during an epidemic. Infectious members of a population may reduce the number of contacts they make with other people because of the physical effects of their illness and possibly because of public health announcements asking them to do so in order to decrease the number of new infections, while susceptible members of the population may reduce the number of contacts they make in order to try to avoid becoming infected. Methods We consider a simple epidemic model in which susceptible and infectious members respond to a disease outbreak by reducing contacts by different fractions and analyze the effect of such contact reductions on the size of the epidemic. We assume constant fractional reductions, without attempting to consider the way in which susceptible members might respond to information about the epidemic. Results We are able to derive upper and lower bounds for the final size of an epidemic, both for simple and staged progression models. Conclusions The responses of uninfected and infected individuals in a disease outbreak are different, and this difference affects estimates of epidemic size.

  16. [Cholera epidemics in Mali between 1995 and 2004].

    Science.gov (United States)

    Dao, Sounkalo; Konaté, Issa; Oumar, Aboubacar Alassane; Sacko, Massambou; Maiga, Ibrahim; Toure, Kandioura; Diarra, Seydou; Bougoudogo, Flabou

    2009-01-01

    Cholera represents a public health problem in developing countries like Mali. This work aims to describe the characteristics of the cholera epidemics which occurred in Mali between 1995 and 2004. A retrospective survey was conducted within the Division of the fight against the diseases of epidemic potential and the Institute of Public Health and Research of the Ministry of Health of Mali. Individual medical records tracking the follow-up of patients as well as the registers of these structures were used as sources to collect data for the study. There were 12,176 cases of cholera recorded, including 1,406 deaths, from 1995 to 2004. Cholera outbreaks in Mali have been a regular occurrence every year since 2001. The regions of Mopti and Segou seem to be the most impacted by these epidemics. The lethal rates were higher than 1% at the time of each of these epidemics during this period. Vibrio cholerae O: 1, biotype El Tor were responsible for the epidemics, and the serotype Ogawa was prevalent. Cholera epidemics have been constant in Mali since the beginning of the 21st century in spite of the efforts which have been made to prevent and control them. A rigorous analysis of the factors which support this persistence and appropriate measures are essential to reverse cholera in this country.

  17. Parasite transmission in social interacting hosts: monogenean epidemics in guppies.

    Directory of Open Access Journals (Sweden)

    Mirelle B Johnson

    Full Text Available BACKGROUND: Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. METHODOLOGY/PRINCIPAL FINDINGS: Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata. Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria, and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. CONCLUSIONS/SIGNIFICANCE: These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

  18. The fundamental drivers of the obesity epidemic.

    Science.gov (United States)

    James, W P T

    2008-03-01

    Most policy makers do not yet understand that the obesity epidemic is a normal population response to the dramatic reduction in the demand for physical activity and the major changes in the food supply of countries over the last 40 years. A national focus on individual behaviour reflects a failure to confront the facts. Thus, the changes in food supply and physical environment are socioeconomically driven, and the health sector simply picks up the consequences. Urbanization alone in China has reduced daily energy expenditure by about 300-400 kcal d(-1) and cycling/bussing or going to work by car determines another variation of 200 kcal d(-1). Thus, energy demands may have dropped with additional TV/media, mechanization and computerized changes by 400-800 kcal d(-1), so weight gain and obesity are inevitable for most or all the population. Food intake should have fallen substantially despite the community's focus on the value of food after all the food crises of the past. Yet, Chinese fat and sugar intakes are escalating, and these policy-mediated features are amplified by the primeval biological drive for those commodities with specialized taste buds for fatty acids, meat, sugar and salt. Yet, traditionally, Chinese diets had negligible sugar, and 25-year-old data show that the optimum diet for Chinese contains 15% fat. Policies relating to food imports, agriculture, food quality standards, appropriate food traffic light labelling, price adjustments and controlled access to unhealthy foods are all within the grasp of the Chinese government. China has traditionally been far more responsive to the value of policies which limit inequalities and establish standards of care than many western governments, who have yet to recognize that the individualistic free-market approach to obesity prevention is guaranteed to fail. China could therefore lead the way: if it follows western approaches, the health and economic burden will become unsustainable.

  19. The asthma epidemic and our artificial habitats

    Directory of Open Access Journals (Sweden)

    Maziak Wasim

    2005-03-01

    Full Text Available Abstract Background The recent increase in childhood asthma has been a puzzling one. Recent views focus on the role of infection in the education of the immune system of young children. However, this so called hygiene hypothesis fails to answer some important questions about the current trends in asthma or to account for environmental influences that bear little relation to infection. Discussion The multi-factorial nature of asthma, reflecting the different ways we tend to interact with our environment, mandates that we look at the asthma epidemic from a broader perspective. Seemingly modern affluent lifestyles are placing us increasingly in static, artificial, microenvironments very different from the conditions prevailed for most part of our evolution and shaped our organisms. Changes that occurred during the second half of the 20th century in industrialized nations with the spread of central heating/conditioning, building insulation, hygiene, TV/PC/games, manufactured food, indoor entertainment, cars, medical care, and sedentary lifestyles all seem to be depriving our children from the essential inputs needed to develop normal airway function (resistance. Asthma according to this view is a manifestation of our respiratory maladaptation to modern lifestyles, or in other words to our increasingly artificial habitats. The basis of the artificial habitat notion may lie in reduced exposure of innate immunity to a variety of environmental stimuli, infectious and non-infectious, leading to reduced formulation of regulatory cells/cytokines as well as inscribed regulatory pathways. This could contribute to a faulty checking mechanism of non-functional Th2 (and likely Th1 responses, resulting in asthma and other immuno-dysregulation disorders. Summary In this piece I discuss the artificial habitat concept, its correspondence with epidemiological data of asthma and allergy, and provide possible immunological underpinning for it from an evolutionary

  20. Paediatric HIV treatment failure: a silent epidemic

    Directory of Open Access Journals (Sweden)

    Jonathan M Bernheimer

    2015-07-01

    Full Text Available Paediatric antiretroviral treatment (ART failure is an under-recognized issue that receives inadequate attention in the field of paediatrics and within HIV treatment programmes. With paediatric ART failure rates ranging from 19.3% to over 32% in resource limited settings, a comprehensive evaluation of the causes of failure along with approaches to address barriers to treatment adherence are urgently needed.In partnership with the local Department of Health, a pilot programme has been established by Medecins Sans Frontieres (MSF in Khayelitsha, South Africa, to identify and support paediatric HIV patients with high viral loads and potential treatment failure. Through detailed clinical and psychosocial evaluations and adherence support with an innovative counselling model, treatment barriers are identified and addressed.Demographic and clinical characteristics from the cohort show a delayed median start date for ART, prolonged viraemia including a large number of patients who have never achieved viral load (VL suppression, a low rate of regimen changes despite failure, and a high percentage of pre-adolescent and adolescent patients who have not gone through the disclosure process.Stemming this epidemic of paediatric treatment failure requires programmatic responses to high viral loads in children, starting with improved “case finding” of previously undiagnosed HIV-infected children and adolescents. Viral load testing needs to be prioritized over CD4 count monitoring, and flagging systems to identify high VL results should be developed in clinics. Clinicians must understand that successful treatment begins with good adherence, and that simple adherence support strategies can often dramatically improve adherence. Moreover, appropriate adherence counselling should begin not when the child fails to respond to treatment. Establishing good adherence from the beginning of treatment, and supporting ongoing adherence during the milestones in these

  1. Ongoing dengue epidemic - Angola, June 2013.

    Science.gov (United States)

    2013-06-21

    On April 1, 2013, the Public Health Directorate of Angola announced that six cases of dengue had been reported to the Ministry of Health of Angola (MHA). As of May 31, a total of 517 suspected dengue cases had been reported and tested for dengue with a rapid diagnostic test (RDT). A total of 313 (60.5%) specimens tested positive for dengue, including one from a patient who died. All suspected cases were reported from Luanda Province, except for two from Malanje Province. Confirmatory diagnostic testing of 49 specimens (43 RDT-positive and six RDT-negative) at the CDC Dengue Branch confirmed dengue virus (DENV) infection in 100% of the RDT-positive specimens and 50% of the RDT-negative specimens. Only DENV-1 was detected by molecular diagnostic testing. Phylogenetic analysis indicated this virus has been circulating in the region since at least 1968, strongly suggesting that dengue is endemic in Angola. Health-care professionals throughout Angola should be aware of the ongoing epidemic, the recommended practices for clinical management of dengue patients, and the need to report cases to MHA. Persons in Angola should seek medical care for acute febrile illness to reduce the risk for developing complications. Laboratory-confirmed dengue also has been reported from seven countries on four continents among persons who had recently traveled to Luanda, including 79 persons from Portugal. Angola is the third of four African countries to report a dengue outbreak in 2013. Persons returning from Africa with acute febrile illness should seek medical care, including testing for DENV infection, and suspected cases should be reported to public health authorities.

  2. Epidemic phase and the site percolation with distant-neighbor interactions

    Science.gov (United States)

    dos Santos, C. B.; Barbin, D.; Caliri, A.

    1998-01-01

    A generalized site percolation model is used to construct an analogy with the epidemic problem, involving spatial coordinates. Epidemic phase and concepts like herd immunity are analyzed in terms of connectivity in a 2D square lattice. The epidemic model used in this work considers a specific interaction topology that includes up to the fifth-nearest neighbors. The results, obtained by Monte Carlo simulation, emphasize the meaning of the spatial coordinates and are illustrated by an epidemic/non-epidemic phase diagram.

  3. The Online Underworld.

    Science.gov (United States)

    Scrogan, Len

    1988-01-01

    Discusses some of the misuses of telecommunicating using school computers, including online piracy, hacking, phreaking, online crime, and destruction boards. Suggests ways that schools can deal with these problems. (TW)

  4. Implementing Online Physical Education

    Science.gov (United States)

    Mohnsen, Bonnie

    2012-01-01

    Online physical education, although seemingly an oxymoron, appears to be the wave of the future at least for some students. The purpose of this article is to explore research and options for online learning in physical education and to examine a curriculum, assessment, and instructional model for online learning. The article examines how physical…

  5. Performance marketing online

    OpenAIRE

    Hamaďáková, Markéta

    2012-01-01

    This thesis discusses the online performance marketing business practices. The theoretical part contains the definition of performance marketing and presents its main components, which include the key performance indicators, the targeting of users, the pricing models of online advertising and affiliate marketing. The second part of the thesis analyzes the performance of online marketing operations for the website FFFFLASH.com.

  6. Could the Recent Zika Epidemic Have Been Predicted?

    Directory of Open Access Journals (Sweden)

    Ángel G. Muñoz

    2017-07-01

    Full Text Available Given knowledge at the time, the recent 2015–2016 zika virus (ZIKV epidemic probably could not have been predicted. Without the prior knowledge of ZIKV being already present in South America, and given the lack of understanding of key epidemiologic processes and long-term records of ZIKV cases in the continent, the best related prediction could be carried out for the potential risk of a generic Aedes-borne disease epidemic. Here we use a recently published two-vector basic reproduction number model to assess the predictability of the conditions conducive to epidemics of diseases like zika, chikungunya, or dengue, transmitted by the independent or concurrent presence of Aedes aegypti and Aedes albopictus. We compare the potential risk of transmission forcing the model with the observed climate and with state-of-the-art operational forecasts from the North American Multi Model Ensemble (NMME, finding that the predictive skill of this new seasonal forecast system is highest for multiple countries in Latin America and the Caribbean during the December-February and March-May seasons, and slightly lower—but still of potential use to decision-makers—for the rest of the year. In particular, we find that above-normal suitable conditions for the occurrence of the zika epidemic at the beginning of 2015 could have been successfully predicted at least 1 month in advance for several zika hotspots, and in particular for Northeast Brazil: the heart of the epidemic. Nonetheless, the initiation and spread of an epidemic depends on the effect of multiple factors beyond climate conditions, and thus this type of approach must be considered as a guide and not as a formal predictive tool of vector-borne epidemics.

  7. Online Cake Cutting

    CERN Document Server

    Walsh, Toby

    2010-01-01

    We propose an online form of the cake cutting problem. This models situations where players arrive and depart during the process of dividing a resource. We show that well known fair division procedures like cut-and-choose and the Dubins-Spanier moving knife procedure can be adapted to apply to such online problems. We propose some desirable properties that online cake cutting procedures might possess like online forms of proportionality and envy-freeness, and identify which properties are in fact possessed by the different online cake procedures.

  8. Differentiation in online retailing

    DEFF Research Database (Denmark)

    Kellner, Julian; Wagner, Gerhard; Zielke, Stephan

    Due to the highly competitive nature of the online retail environment, differentiation strategies are of importance for online retailers to gain competitive advantages and to achieve a unique positioning in the market. However, little is known about perceptual dimensions used by consumers to make...... a distinction between online retailers. The present study addresses this research gap by using a repertory grid approach to identify points of difference between online retailers from a consumer’s perspective. The results have important implications for positioning strategies of online retailers and research...

  9. Reconstructing the AIDS epidemic among injection drug users in Brazil

    Directory of Open Access Journals (Sweden)

    Mariana A. Hacker

    2006-04-01

    Full Text Available The HIV/AIDS epidemic among injection drug users (IDUs in Brazil has been unique in terms of temporal and geographical contrasts. This analysis explores these contrasts through the use of multilevel modeling. Standardized AIDS incidence rates among IDUs for Brazilian municipalities (1986-2000 were used as the dependent variable, with a set of social indicators as independent variables (covariates. In some States of the North/Northeast, the epidemic among IDUs has been incipient. The São Paulo epidemic extended to reach a network of municipalities, most of which located far from the capital. More recently, on a smaller scale, a similar extension has been observed in the southernmost States of the country. Both "number of physicians per inhabitant" and "standard distance to the State capital" were found to be associated with AIDS incidence. AIDS cases among IDUs appeared to cluster in wealthier, more developed municipalities. The relative weight of such extensive dissemination in key, heavily populated States prevails in the Brazilian IDU epidemic, defining a central-western-southeastern strip of wealthier middle-sized municipalities and more recently a southern strip of municipalities deeply affected by the epidemic in this population.

  10. Porcine epidemic diarrhea virus infection: Etiology, epidemiology, pathogenesis and immunoprophylaxis.

    Science.gov (United States)

    Jung, Kwonil; Saif, Linda J

    2015-05-01

    Porcine epidemic diarrhea virus (PEDV), a member of the genera Alphacoronavirus in the family Coronaviridae, causes acute diarrhea/vomiting, dehydration and high mortality in seronegative neonatal piglets. For the last three decades, PEDV infection has resulted in significant economic losses in the European and Asian pig industries, but in 2013-2014 the disease was also reported in the US, Canada and Mexico. The PED epidemic in the US, from April 2013 to the present, has led to the loss of more than 10% of the US pig population. The disappearance and re-emergence of epidemic PED indicates that the virus is able to escape from current vaccination protocols, biosecurity and control systems. Endemic PED is a significant problem, which is exacerbated by the emergence (or potential importation) of multiple PEDV variants. Epidemic PEDV strains spread rapidly and cause a high number of pig deaths. These strains are highly enteropathogenic and acutely infect villous epithelial cells of the entire small and large intestines although the jejunum and ileum are the primary sites. PEDV infections cause acute, severe atrophic enteritis accompanied by viremia that leads to profound diarrhea and vomiting, followed by extensive dehydration, which is the major cause of death in nursing piglets. A comprehensive understanding of the pathogenic characteristics of epidemic or endemic PEDV strains is needed to prevent and control the disease in affected regions and to develop an effective vaccine. This review focuses on the etiology, epidemiology, disease mechanisms and pathogenesis as well as immunoprophylaxis against PEDV infection.

  11. When pestilence prevails...physician responsibilities in epidemics.

    Science.gov (United States)

    Huber, Samuel J; Wynia, Matthew K

    2004-01-01

    The threat of bioterrorism, the emergence of the SARS epidemic, and a recent focus on professionalism among physicians, present a timely opportunity for a review of, and renewed commitment to, physician obligations to care for patients during epidemics. The professional obligation to care for contagious patients is part of a larger "duty to treat," which historically became accepted when 1) a risk of nosocomial infection was perceived, 2) an organized professional body existed to promote the duty, and 3) the public came to rely on the duty. Physicians' responses to epidemics from the Hippocratic era to the present suggests an evolving acceptance of the professional duty to treat contagious patients, reaching a long-held peak between 1847 and the 1950's. There has been some professional retrenchment against this duty to treat in the last 40 years but, we argue, conditions favoring acceptance of the duty are met today. A renewed embrace of physicians' duty to treat patients during epidemics, despite conditions of personal risk, might strengthen medicine's relationship with society, improve society's capacity to prepare for threats such as bioterrorism and new epidemics, and contribute to the development of a more robust and meaningful medical professionalism.

  12. Game theory of social distancing in response to an epidemic.

    Directory of Open Access Journals (Sweden)

    Timothy C Reluga

    2010-05-01

    Full Text Available Social distancing practices are changes in behavior that prevent disease transmission by reducing contact rates between susceptible individuals and infected individuals who may transmit the disease. Social distancing practices can reduce the severity of an epidemic, but the benefits of social distancing depend on the extent to which it is used by individuals. Individuals are sometimes reluctant to pay the costs inherent in social distancing, and this can limit its effectiveness as a control measure. This paper formulates a differential-game to identify how individuals would best use social distancing and related self-protective behaviors during an epidemic. The epidemic is described by a simple, well-mixed ordinary differential equation model. We use the differential game to study potential value of social distancing as a mitigation measure by calculating the equilibrium behaviors under a variety of cost-functions. Numerical methods are used to calculate the total costs of an epidemic under equilibrium behaviors as a function of the time to mass vaccination, following epidemic identification. The key parameters in the analysis are the basic reproduction number and the baseline efficiency of social distancing. The results show that social distancing is most beneficial to individuals for basic reproduction numbers around 2. In the absence of vaccination or other intervention measures, optimal social distancing never recovers more than 30% of the cost of infection. We also show how the window of opportunity for vaccine development lengthens as the efficiency of social distancing and detection improve.

  13. Evolutionary genomics of epidemic and nonepidemic strains of Pseudomonas aeruginosa.

    Science.gov (United States)

    Dettman, Jeremy R; Rodrigue, Nicolas; Aaron, Shawn D; Kassen, Rees

    2013-12-24

    Pseudomonas aeruginosa is an opportunistic pathogen of humans and is a major cause of morbidity and mortality in patients with cystic fibrosis (CF). Prolonged infection of the respiratory tract can lead to adaptation of the pathogen to the CF lung environment. To examine the general patterns of adaptation associated with chronic infection, we obtained genome sequences from a collection of P. aeruginosa isolated from airways of patients with CF. Our analyses support a nonclonal epidemic population structure, with a background of unique, recombining genotypes, and the rare occurrence of successful epidemic clones. We present unique genome sequence evidence for the intercontinental spread of an epidemic strain shared between CF clinics in the United Kingdom and North America. Analyses of core and accessory genomes identified candidate genes and important functional pathways associated with adaptive evolution. Many genes of interest were involved in biological functions with obvious roles in this pathosystem, such as biofilm formation, antibiotic metabolism, pathogenesis, transport, reduction/oxidation, and secretion. Key factors driving the adaptive evolution of this pathogen within the host appear to be the presence of oxidative stressors and antibiotics. Regions of the accessory genome unique to the epidemic strain were enriched for genes in transporter families that efflux heavy metals and antibiotics. The epidemic strain was significantly more resistant than nonepidemic strains to three different antibiotics. Multiple lines of evidence suggest that selection imposed by the CF lung environment has a major influence on genomic evolution and the genetic characteristics of P. aeruginosa isolates causing contemporary infection.

  14. Synchronized and mixed outbreaks of coupled recurrent epidemics

    CERN Document Server

    Zheng, Muhua; Min, Byungjoon; Liu, Zonghua

    2016-01-01

    Epidemic spreading has been studied for a long time and most of them are focused on the growing aspect of a single epidemic outbreak. Recently, we extended the study to the case of recurrent epidemics (Sci. Rep. {\\bf 5}, 16010 (2015)) but limited only to a single network. We here report from the real data of coupled regions or cities that the recurrent epidemics in two coupled networks are closely related to each other and can show either synchronized outbreak phase where outbreaks occur simultaneously in both networks or mixed outbreak phase where outbreaks occur in one network but do not in another one. To reveal the underlying mechanism, we present a two-layered network model of coupled recurrent epidemics to reproduce the synchronized and mixed outbreak phases. We show that the synchronized outbreak phase is preferred to be triggered in two coupled networks with the same average degree while the mixed outbreak phase is preferred for the case with different average degrees. Further, we show that the coupli...

  15. Game theory of social distancing in response to an epidemic.

    Science.gov (United States)

    Reluga, Timothy C

    2010-05-27

    Social distancing practices are changes in behavior that prevent disease transmission by reducing contact rates between susceptible individuals and infected individuals who may transmit the disease. Social distancing practices can reduce the severity of an epidemic, but the benefits of social distancing depend on the extent to which it is used by individuals. Individuals are sometimes reluctant to pay the costs inherent in social distancing, and this can limit its effectiveness as a control measure. This paper formulates a differential-game to identify how individuals would best use social distancing and related self-protective behaviors during an epidemic. The epidemic is described by a simple, well-mixed ordinary differential equation model. We use the differential game to study potential value of social distancing as a mitigation measure by calculating the equilibrium behaviors under a variety of cost-functions. Numerical methods are used to calculate the total costs of an epidemic under equilibrium behaviors as a function of the time to mass vaccination, following epidemic identification. The key parameters in the analysis are the basic reproduction number and the baseline efficiency of social distancing. The results show that social distancing is most beneficial to individuals for basic reproduction numbers around 2. In the absence of vaccination or other intervention measures, optimal social distancing never recovers more than 30% of the cost of infection. We also show how the window of opportunity for vaccine development lengthens as the efficiency of social distancing and detection improve.

  16. Epidemic spread over networks with agent awareness and social distancing

    KAUST Repository

    Paarporn, Keith

    2016-04-20

    We study an SIS epidemic model over an arbitrary connected network topology when the agents receive personalized information about the current epidemic state. The agents utilize their available information to either reduce interactions with their neighbors (social distancing) when they believe the epidemic is currently prevalent or resume normal interactions when they believe there is low risk of becoming infected. The information is a weighted combination of three sources: 1) the average states of nodes in contact neighborhoods 2) the average states of nodes in an information network 3) a global broadcast of the average epidemic state of the network. A 2n-state Markov Chain is first considered to model the disease dynamics with awareness, from which a mean-field discrete-time n-state dynamical system is derived, where each state corresponds to an agent\\'s probability of being infected. The nonlinear model is a lower bound of its linearized version about the origin. Hence, global stability of the origin (the diseasefree equilibrium) in the linear model implies global stability in the nonlinear model. When the origin is not stable, we show the existence of a nontrivial fixed point in the awareness model, which obeys a strict partial order in relation to the nontrivial fixed point of the dynamics without distancing. In simulations, we define two performance metrics to understand the effectiveness agent awareness has in reducing the spread of an epidemic. © 2015 IEEE.

  17. Epidemic Intelligence. Langmuir and the Birth of Disease Surveillance

    Directory of Open Access Journals (Sweden)

    Lyle Fearnley

    2010-12-01

    Full Text Available In the wake of the SARS and influenza epidemics of the past decade, one public health solution has become a refrain: surveillance systems for detection of disease outbreaks. This paper is an effort to understand how disease surveillance for outbreak detection gained such paramount rationality in contemporary public health. The epidemiologist Alexander Langmuir is well known as the creator of modern disease surveillance. But less well known is how he imagined disease surveillance as one part of what he called “epidemic intelligence.” Langmuir developed the practice of disease surveillance during an unprecedented moment in which the threat of biological warfare brought civil defense experts and epidemiologists together around a common problem. In this paper, I describe how Langmuir navigated this world, experimenting with new techniques and rationales of epidemic control. Ultimately, I argue, Langmuir′s experiments resulted in a set of techniques and infrastructures – a system of epidemic intelligence – that transformed the epidemic as an object of human art.

  18. Epidemic spreading on dual-structure networks with mobile agents

    Science.gov (United States)

    Yao, Yiyang; Zhou, Yinzuo

    2017-02-01

    The rapid development of modern society continually transforms the social structure which leads to an increasingly distinct dual structure of higher population density in urban areas and lower density in rural areas. Such structure may induce distinctive spreading behavior of epidemics which does not happen in a single type structure. In this paper, we study the epidemic spreading of mobile agents on dual structure networks based on SIRS model. First, beyond the well known epidemic threshold for generic epidemic model that when the infection rate is below the threshold a pertinent infectious disease will die out, we find the other epidemic threshold which appears when the infection rate of a disease is relatively high. This feature of two thresholds for the SIRS model may lead to the elimination of infectious disease when social network has either high population density or low population density. Interestingly, however, we find that when a high density area is connected to a low density may cause persistent spreading of the infectious disease, even though the same disease will die out when it spreads in each single area. This phenomenon indicates the critical role of the connection between the two areas which could radically change the behavior of spreading dynamics. Our findings, therefore, provide new understanding of epidemiology pertinent to the characteristic modern social structure and have potential to develop controlling strategies accordingly.

  19. SIS model of epidemic spreading on dynamical networks with community

    Institute of Scientific and Technical Information of China (English)

    Chengyi XIA; Shiwen SUN; Feng RAO; Junqing SUN; Jinsong WANG; Zengqiang CHEN

    2009-01-01

    We present a new epidemic Susceptible-Infected-Susceptible (SIS) model to investigate the spreading behav-ior on networks with dynamical topology and community structure. Individuals in the model are mobile agents who are allowed to perform the inter-community (i.e., long-range) motion with the probability p. The mean-field theory is uti-lized to derive the critical threshold (λ_C) of epidemic spread-ing inside separate communities and the influence of the long-range motion on the epidemic spreading. The results indicate that λ_C is only related with the population density within the community, and the long-range motion will make the original disease-free community become the endemic state. Large-scale numerical simulations also demonstrate the theoretical approximations based on our new epidemic model. The current model and analysis will help us to fur-ther understand the propagation behavior of real epidemics taking place on social networks.

  20. Surveillance and control of meningococcal meningitis epidemics in refugee populations.

    Science.gov (United States)

    Moore, P S; Toole, M J; Nieburg, P; Waldman, R J; Broome, C V

    1990-01-01

    Epidemics of communicable diseases pose a direct threat to refugee and internally displaced populations, and could lead to high mortality rates and a disruption of basic health care services. Several large refugee populations live in regions of high meningococcal disease endemicity and their camps are at risk for outbreaks of meningococcal meningitis. Surveillance in these camps allows early detection and control of impending outbreaks. Confirmation of meningococcal disease can be performed under field conditions using simple techniques, such as latex agglutination. Isolates should be obtained for serogroup confirmation and antibiotic sensitivity studies at reference laboratories. Serogroup information is used to determine the risk of widespread epidemic disease and the utility of available vaccines. During epidemics, treatment regimens should be standardized, preferably with an effective single-dose antibiotic. Mass vaccination campaigns should be initiated, the populations at high risk being targeted for vaccination as quickly as possible. When the risk of epidemic disease is deemed to be high, preemptive vaccination may be warranted. Daily surveillance using a simple case definition is essential during an epidemic to determine the effectiveness of control measures and to delineate high-risk groups for vaccination or chemoprophylaxis. Many of these recommendations can be applied also to other populations in developing countries.

  1. [Observations on the 1348 plague epidemic. Measures taken to combat its tragic effects and avoid epidemic recrudescence].

    Science.gov (United States)

    Sabbatani, Sergio

    2003-03-01

    When the "Black Death" swept through Europe from southern France in 1348, in the short space of two years the Europeans were hit by one of the most serious epidemics ever recorded in human history. Yersinia pestis reached Europe by sea, its contamination propagated by the Genoese ships coming from the Crimean port of Jaffa. For the first time the world experienced microbiological unification: East and West were equally involved in the tragedy that spread, and no town remained unscathed during the various epidemic waves which succeeded one another in the following three centuries. The authors of this article describe how and why the epidemic spread, as well as the factors that led to the swift, and often fatal, involment of millions of Europeans. The second part of the article deals with the measures taken by the healthcare authorities of European towns and countries in order to halt the proliferation of the disease. According to the data and observations by authoritative authors, selected among the many who studied the disease that from the 14th century spread like a scourge throughout the known world at the time, the epidemic could have been even more serious, in terms of mortality and morbidity, without the disciplinary and provisional health measures taken. The experience gained in Italy and all over Europe at the time proved useful not only to better manage the epidemics which cyclically broke out, but also to efficiently combat the cholera epidemics of the 19th century. With the 14th century plague epidemic, the Europeans and their political and administrative representatives may well have realized for the very first time that contamination could be combatted by adopting a set of rational, scientific norms - although in practice such rules were mostly inspired by misguided scientific theories. Humankind was no longer alone. A new society was emerging, one that was not going to passively accept the more or less mysterious ways of a superior being of fate. The

  2. Steady States in SIRS Epidemical Model of Mobile Individuals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Duan-Ming; LIU Dan; HE Min-Hua; YU Xiao-Ling; PAN Gui-Jun; SUN Hong-Zhang; SU Xiang-Ying; SUN Fan; YIN Yan-Ping; LI Rui

    2006-01-01

    We consider an epidemical model within socially interacting mobile individuals to study the behaviors of steady statesof epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations, we recover the usual epidemic behavior with critical thresholds δc and pc below which infectious disease dies out. For the population density δ far above δc, it is found that there is linear relationship between contact rate λ and the population density δ in the main. At the same time, the result obtained from mean-field approximation is compared with our numerical result, and it is found that these two results are similar by and large but not completely the same.

  3. Steady States in SIRS Epidemical Model of Mobile Individuals

    Science.gov (United States)

    Zhang, Duan-Ming; He, Min-Hua; Yu, Xiao-Ling; Pan, Gui-Jun; Sun, Hong-Zhang; Su, Xiang-Ying; Sun, Fan; Yin, Yan-Ping; Li, Rui; Liu, Dan

    2006-01-01

    We consider an epidemical model within socially interacting mobile individuals to study the behaviors of steady states of epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations, we recover the usual epidemic behavior with critical thresholds δc and pc below which infectious disease dies out. For the population density δ far above δc, it is found that there is linear relationship between contact rate λ and the population density δ in the main. At the same time, the result obtained from mean-field approximation is compared with our numerical result, and it is found that these two results are similar by and large but not completely the same.

  4. Emergence and transmission of arbovirus evolutionary intermediates with epidemic potential.

    Science.gov (United States)

    Stapleford, Kenneth A; Coffey, Lark L; Lay, Sreyrath; Bordería, Antonio V; Duong, Veasna; Isakov, Ofer; Rozen-Gagnon, Kathryn; Arias-Goeta, Camilo; Blanc, Hervé; Beaucourt, Stéphanie; Haliloğlu, Türkan; Schmitt, Christine; Bonne, Isabelle; Ben-Tal, Nir; Shomron, Noam; Failloux, Anna-Bella; Buchy, Philippe; Vignuzzi, Marco

    2014-06-11

    The high replication and mutation rates of RNA viruses can result in the emergence of new epidemic variants. Thus, the ability to follow host-specific evolutionary trajectories of viruses is essential to predict and prevent epidemics. By studying the spatial and temporal evolution of chikungunya virus during natural transmission between mosquitoes and mammals, we have identified viral evolutionary intermediates prior to emergence. Analysis of virus populations at anatomical barriers revealed that the mosquito midgut and salivary gland pose population bottlenecks. By focusing on virus subpopulations in the saliva of multiple mosquito strains, we recapitulated the emergence of a recent epidemic strain of chikungunya and identified E1 glycoprotein mutations with potential to emerge in the future. These mutations confer fitness advantages in mosquito and mammalian hosts by altering virion stability and fusogenic activity. Thus, virus evolutionary trajectories can be predicted and studied in the short term before new variants displace currently circulating strains.

  5. Epidemic Dynamics On Information-Driven Adaptive Networks

    CERN Document Server

    Zhan, Xiu-Xiu; Sun, Gui-Quan; Zhang, Zi-Ke

    2015-01-01

    can evolve simultaneously. For the information-driven adaptive process, susceptible (infected) individuals who have abilities to recognize the disease would break the links of their infected (susceptible) neighbors to prevent the epidemic from further spreading. Simulation results and numerical analyses based on the pairwise approach indicate that the information-driven adaptive process can not only slow down the speed of epidemic spreading, but can also diminish the epidemic prevalence at the final state significantly. In addition, the disease spreading and information diffusion pattern on the lattice give a visual representation about how the disease is trapped into an isolated field with the information-driven adaptive process. Furthermore, we perform the local bifurcation analysis on four types of dynamical regions, including healthy, oscillatory, bistable and endemic, to understand the evolution of the observed dynamical behaviors. This work may shed some lights on understanding how information affects h...

  6. Competing spreading processes on multiplex networks: awareness and epidemics

    CERN Document Server

    Granell, Clara; Arenas, Alex

    2014-01-01

    Epidemic-like spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [Granell et al. Phys. Rev. Lett. 111, 128701 (2013)] presented the analysis of the interrelation between two processes accounting for the spreading of an epidemics, and the spreading of information awareness to prevent its infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease, revealed the existence of a metacritical point at which the critical onset of the epidemics starts depending on the reaching of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between both competing processes for a wide spectrum of parameters representing the interacti...

  7. Efficient mitigation strategies for epidemics in rural regions

    CERN Document Server

    Scoglio, Caterina; Schumm, Phillip; Easton, Todd; Chowdhury, Sohini Roy; Sydney, Ali; Youssef, Mina

    2010-01-01

    Containing an epidemic at its origin is the most desirable mitigation. Epidemics have often originated in rural areas, with rural communities among the first affected. Disease dynamics in rural regions have received limited attention, and results of general studies cannot be directly applied since population densities and human mobility factors are very different in rural regions from those in cities. We create a network model of a rural community in Kansas, USA, by collecting data on the contact patterns and computing rates of contact among a sampled population. We model the impact of different mitigation strategies detecting closely connected groups of people and frequently visited locations. Within those groups and locations, we compare the effectiveness of random and targeted vaccinations using a Susceptible-Exposed-Infected-Recovered compartmental model on the contact network. Our simulations show that the targeted vaccinations of only 10% of the sampled population reduced the size of the epidemic by 34....

  8. How to estimate epidemic risk from incomplete contact diaries data?

    CERN Document Server

    Mastrandrea, Rossana

    2016-01-01

    Social interactions shape the patterns of spreading processes in a population. Techniques such as diaries or proximity sensors allow to collect data about encounters and to build networks of contacts between individuals. The contact networks obtained from these different techniques are however quantitatively different. Here, we first show how these discrepancies affect the prediction of the epidemic risk when these data are fed to numerical models of epidemic spread: low participation rate, under-reporting of contacts and overestimation of contact durations in contact diaries with respect to sensor data determine indeed important differences in the outcomes of the corresponding simulations {with for instance an enhanced sensitivity to initial conditions}. Most importantly, we investigate if and how information gathered from contact diaries can be used in such simulations in order to yield an accurate description of the epidemic risk, assuming that data from sensors represent the ground truth. The contact netw...

  9. Know your epidemic, know your response: targeting HIV in Asia

    DEFF Research Database (Denmark)

    Lazarus, Jeff; Curth, Nadja; Bridge, Jamie

    2010-01-01

    prevention and treatment services. In order to reach the Millennium Development Goal of halting and reversing the spread of HIV by 2015 and to achieve universal access to HIV treatment, these barriers must be overcome across Asia. High-impact programs must be targeted at those in need, with continuous......This article provides an overview of the HIV epidemic in Asia, the context within which the epidemic is evolving, and the key actions to address the challenges faced by countries and risk groups. HIV epidemics across Asia are predominantly concentrated among most-at-risk populations. Although...... there have been many successes in the HIV response in Asia over the past decade, great challenges clearly remain - especially when addressing most-at-risk populations, who are often criminalized, marginalized, and discriminated against. These groups face significant legal and social barriers to accessing HIV...

  10. Model of epidemic control based on quarantine and message delivery

    Science.gov (United States)

    Wang, Xingyuan; Zhao, Tianfang; Qin, Xiaomeng

    2016-09-01

    The model provides two novel strategies for the preventive control of epidemic diseases. One approach is related to the different isolating rates in latent period and invasion period. Experiments show that the increasing of isolating rates in invasion period, as long as over 0.5, contributes little to the preventing of epidemic; the improvement of isolation rate in latent period is key to control the disease spreading. Another is a specific mechanism of message delivering and forwarding. Information quality and information accumulating process are also considered there. Macroscopically, diseases are easy to control as long as the immune messages reach a certain quality. Individually, the accumulating messages bring people with certain immunity to the disease. Also, the model is performed on the classic complex networks like scale-free network and small-world network, and location-based social networks. Results show that the proposed measures demonstrate superior performance and significantly reduce the negative impact of epidemic disease.

  11. The "childhood obesity epidemic": health crisis or social construction?

    Science.gov (United States)

    Moffat, Tina

    2010-03-01

    There has been a meteoric rise over the past two decades in the medical research and media coverage of the so-called global childhood obesity epidemic. Recently, in response to this phenomenon, there has been a spate of books and articles in the fields of critical sociology and cultural studies that have argued that this "epidemic" is socially constructed, what Natalie Boero (2007) dubs a "postmodern epidemic." As an anthropologist who has studied child nutrition and obesity in relation to poverty and the school environment, I am concerned about both the lack of reflexivity among medical researchers as well as critical scholars' treatment of the problem as entirely socially constructed. In this article I present both sides of this debate and then discuss how wee can attempt to navigate a middle course that recognizes this health issue but also offers alternative approaches to those set by the biomedical agenda.

  12. Individual-based lattice model for spatial spread of epidemics

    Directory of Open Access Journals (Sweden)

    Henryk Fuks

    2001-01-01

    Full Text Available We present a lattice gas cellular automaton (LGCA to study spatial and temporal dynamics of an epidemic of SIR (susceptible-infected-removed type. The automaton is fully discrete, i.e., space, time and number of individuals are discrete variables. The automaton can be applied to study spread of epidemics in both human and animal populations. We investigate effects of spatial inhomogeneities in initial distribution of infected and vaccinated populations on the dynamics of epidemic of SIR type. We discuss vaccination strategies which differ only in spatial distribution of vaccinated individuals. Also, we derive an approximate, mean-field type description of the automaton, and discuss differences between the mean-field dynamics and the results ofLGCA simulation.

  13. Predicting epidemic outbreak from individual features of the spreaders

    CERN Document Server

    da Silva, Renato Aparecido Pimentel; Costa, Luciano da Fontoura

    2012-01-01

    Knowing which individuals can be more efficient in spreading a pathogen throughout a determinate environment is a fundamental question in disease control. Indeed, over the last years the spread of epidemic diseases and its relationship with the topology of the involved system have been a recurrent topic in complex network theory, taking into account both network models and real-world data. In this paper we explore possible correlations between the heterogeneous spread of an epidemic disease governed by the susceptible-infected-recovered (SIR) model, and several attributes of the originating vertices, considering Erd\\"os-R\\'enyi (ER), Barab\\'asi-Albert (BA) and random geometric graphs (RGG), as well as a real case of study, the US Air Transportation Network that comprises the US 500 busiest airports along with inter-connections. Among both the theoretical and the real networks considered, we observe high correlation between the total epidemic prevalence and the degree, the strength and the accessibility of the...

  14. Epidemiological investigations of chikungunya epidemic at Barsi, Maharashtra state, India.

    Science.gov (United States)

    Padbidri, V S; Gnaneswar, T T

    1979-01-01

    During the summer of 1973, an epidemic of Chikungunya broke out in Barsi, Sholapur district. Epidemiological investigations carried out during the decline phase revealed that all age groups and both sexes were involved with varying morbidity. The absence of previous immunity was demonstrated by a very high morbidity of 37.53 per cent for the whole town. The clinical picture encountered during the epidemic was quite characteristic of chikungunya. Besides gingivitis and epistaxis there were no frank haemorrhagic episodes. Reports about the presence of demonstrable rash varied. Except for one possible case, there was no mortality as a result of the epidemic. Results of the search for the index case are also described.

  15. Effects of Weak Ties on Epidemic Predictability in Community Networks

    CERN Document Server

    Shu, Panpan; Gong, Kai; Liu, Ying

    2012-01-01

    Weak ties play a significant role in the structures and the dynamics of community networks. Based on the susceptible-infected model in contact process, we study numerically how weak ties influence the predictability of epidemic dynamics. We first investigate the effects of different kinds of weak ties on the variabilities of both the arrival time and the prevalence of disease, and find that the bridgeness with small degree can enhance the predictability of epidemic spreading. Once weak ties are settled, compared with the variability of arrival time, the variability of prevalence displays a diametrically opposed changing trend with both the distance of the initial seed to the bridgeness and the degree of the initial seed. More specifically, the further distance and the larger degree of the initial seed can induce the better predictability of arrival time and the worse predictability of prevalence. Moreover, we discuss the effects of weak tie number on the epidemic variability. As community strength becomes ver...

  16. Absence of epidemic thresholds in a growing adaptive network

    CERN Document Server

    Demirel, Güven

    2012-01-01

    The structure of social contact networks strongly influences the dynamics of epidemic diseases. In particular the scale-free structure of real-world social networks allows unlikely diseases with low infection rates to spread and become endemic. However, in particular for potentially fatal diseases, also the impact of the disease on the social structure cannot be neglected, leading to a complex interplay. Here, we consider the growth of a network by preferential attachment from which nodes are simultaneously removed due to an SIR epidemic. We show that increased infectiousness increases the prevalence of the disease and simultaneously causes a transition from scale-free to exponential topology. Although a transition to a degree distribution with finite variance takes place, the network still exhibits no epidemic threshold in the thermodynamic limit. We illustrate these results using agent-based simulations and analytically tractable approximation schemes.

  17. Temporal prediction of epidemic patterns in community networks

    CERN Document Server

    Peng, Xiao-Long; Xu, Xin-Jian; Fu, Xinchu

    2013-01-01

    Most previous studies of epidemic dynamics on complex networks suppose that the disease will eventually stabilize at either a disease-free state or an endemic one. In reality, however, some epidemics always exhibit sporadic and recurrent behaviour in one region because of the invasion from an endemic population elsewhere. In this paper we address this issue and study a susceptible-infected-susceptible epidemiological model on a network consisting of two communities, where the disease is endemic in one community but alternates between outbreaks and extinctions in the other. We provide a detailed characterization of the temporal dynamics of epidemic patterns in the latter community. In particular, we investigate the time duration of both outbreak and extinction, and the time interval between two consecutive inter-community infections, as well as their frequency distributions. Based on the mean-field theory, we theoretically analyze these three timescales and their dependence on the average node degree of each c...

  18. Spatial extent of an outbreak in animal epidemics.

    Science.gov (United States)

    Dumonteil, Eric; Majumdar, Satya N; Rosso, Alberto; Zoia, Andrea

    2013-03-12

    Characterizing the spatial extent of epidemics at the outbreak stage is key to controlling the evolution of the disease. At the outbreak, the number of infected individuals is typically small, and therefore, fluctuations around their average are important: then, it is commonly assumed that the susceptible-infected-recovered mechanism can be described by a stochastic birth-death process of Galton-Watson type. The displacements of the infected individuals can be modeled by resorting to brownian motion, which is applicable when long-range movements and complex network interactions can be safely neglected, like in the case of animal epidemics. In this context, the spatial extent of an epidemic can be assessed by computing the convex hull enclosing the infected individuals at a given time. We derive the exact evolution equations for the mean perimeter and the mean area of the convex hull, and we compare them with Monte Carlo simulations.

  19. The global HIV epidemic: current status and challenges.

    Science.gov (United States)

    Abdool Karim, Quarraisha

    2013-06-01

    Three decades after the first reported cases of AIDS we have within our reach sufficient evidence to substantially alter the HIV epidemic at a country level regardless of mode of transmission of HIV. There are a growing number of countries demonstrating control of the epidemic. Human rights violations and/or legislation relating to sexual orientation, status of minors, injecting drug use and sex work together with stigma and discrimination remain key barriers to knowledge of HIV status and access to appropriate services. The use of anti-retrovirals prophylactically to reduce sexual and vertical transmission and systemically to treat infected infants and adults is central to the optimism in responses to the epidemic. In the current fiscal climate careful thought needs to be given to how to efficiently optimise combinations of what is available to have the biggest impact in the context of limited human and infrastructure resources.

  20. Epidemic Forecasting is Messier Than Weather Forecasting: The Role of Human Behavior and Internet Data Streams in Epidemic Forecast.

    Science.gov (United States)

    Moran, Kelly R; Fairchild, Geoffrey; Generous, Nicholas; Hickmann, Kyle; Osthus, Dave; Priedhorsky, Reid; Hyman, James; Del Valle, Sara Y

    2016-12-01

    Mathematical models, such as those that forecast the spread of epidemics or predict the weather, must overcome the challenges of integrating incomplete and inaccurate data in computer simulations, estimating the probability of multiple possible scenarios, incorporating changes in human behavior and/or the pathogen, and environmental factors. In the past 3 decades, the weather forecasting community has made significant advances in data collection, assimilating heterogeneous data steams into models and communicating the uncertainty of their predictions to the general public. Epidemic modelers are struggling with these same issues in forecasting the spread of emerging diseases, such as Zika virus infection and Ebola virus disease. While weather models rely on physical systems, data from satellites, and weather stations, epidemic models rely on human interactions, multiple data sources such as clinical surveillance and Internet data, and environmental or biological factors that can change the pathogen dynamics. We describe some of similarities and differences between these 2 fields and how the epidemic modeling community is rising to the challenges posed by forecasting to help anticipate and guide the mitigation of epidemics. We conclude that some of the fundamental differences between these 2 fields, such as human behavior, make disease forecasting more challenging than weather forecasting. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  1. Suppressing traffic-driven epidemic spreading by use of the efficient routing protocol

    CERN Document Server

    Yang, Han-Xin

    2015-01-01

    Despite extensive work on the interplay between traffic dynamics and epidemic spreading, the control of epidemic spreading by routing strategies has not received adequate attention. In this paper, we study the impact of efficient routing protocol on epidemic spreading. In the case of infinite node-delivery capacity, where the traffic is free of congestion, we find that that there exists optimal values of routing parameter, leading to the maximal epidemic threshold. This means that epidemic spreading can be effectively controlled by fine tuning the routing scheme. Moreover, we find that an increase in the average network connectivity and the emergence of traffic congestion can suppress the epidemic outbreak.

  2. Association of Drought with Typhus Epidemics in Central Mexico

    Science.gov (United States)

    Acuna-Soto, R.; Stahle, D.; Villanueva Diaz, J.; Therrell, M.

    2007-05-01

    Typhus is an acute infectious disease caused by the bacteria Rickettsia prowazekii, which is transmitted among humans by the body lice (Pediculus humanus corporis). The disease is highly contagious and transmission is favored in populations living in crowded conditions. Under these circumstances, typhus transmission is facilitated by factors that favor the colonization and proliferation of body lice such as absence of personal hygiene and wearing the same clothes for long periods of time. Historically, periods of war and famine were associated with devastating epidemics with high mortality rates in many parts of the world. Central Mexico has a long record of typhus epidemics. In this region, at > 2000 meters above sea level, the disease was endemic and occurred with a seasonal pattern in winter, with occasional large epidemics. Recently, we completed a chronology of epidemics in Mexico. A total of 22 well-defined major typhus epidemics were identified between 1650 and 1920. All of them caused periods of increased mortality that lasted 2 - 4 years (more than one standard deviation from the previous ten year period). The record of typhus epidemics was evaluated against the tree-ring record of Cuauhtmoc La Fragua, Puebla. This chronology, based on Douglas fir, has demonstrated to be a faithful record of precipitation in central Mexico. The results indicate that a statistically significant drought (t test, p < .05) prevailed during the first year of all 22 large outbreaks of typhus in recent Mexican history. No distinction is made between times of peace and war. This indicates that drought alone was capable of inducing the social conditions for increased transmission of typhus in pre-industrial central Mexico.

  3. Reemergence of enterovirus 71 epidemic in northern Taiwan, 2012.

    Directory of Open Access Journals (Sweden)

    Shu-Ting Luo

    Full Text Available Enterovirus 71 (EV71 belongs to picornavirus family and could be classified phylogenetically into three major genogroups (A, B and C including 11 genotypes (A, B1-B5 and C1-C5. Since 1997, EV71 has caused large-scale of epidemics with neurological complications in Asian children. In Taiwan, nationwide EV71 epidemics with different predominant genotypes have occurred cyclically since 1998. A nationwide EV71 epidemic occurred again in 2012. We conducted genetic and antigenic characterizations of the 2012 epidemic.Chang Gung Memorial Hospital (CGMH is a medical center in northern Taiwan. In CGMH, specimens were collected from pediatric inpatients with suspected enterovirus infections for virus isolation. Enterovirus isolates were serotyped and genotyped and sera from EV71 inpatients were collected for measuring neutralizing antibody titers.There were 10, 16 and 99 EV71 inpatients identified in 2010, 2011 and 2012, respectively. There were 82 EV71 isolates genotyped, which identified 17 genotype C4a viruses and 65 genotype B5 viruses. The genotype B5 viruses were not detected until November 2011 and caused epidemics in 2012. Interestingly, the B5-2011 viruses were genetically distinguishable from the B5 viruses causing the 2008 epidemic and are likely introduced from China or Southeastern Asia. Based on antigenic analysis, minor antigenic variations were detected among the B5-2008, B5-2011, C4a-2008 and C4a-2012 viruses but these viruses antigenically differed from genotype A.Genotype B5 and C4a viruses antigenically differ from genotype A viruses which have disappeared globally for 30 years but have been detected in China since 2008. Enterovirus surveillance should monitor genetic and antigenic variations of EV71.

  4. A study of epidemic spreading on activity-driven networks

    Science.gov (United States)

    Zou, Yijiang; Deng, Weibing; Li, Wei; Cai, Xu

    2016-03-01

    The epidemic spreading was explored on activity-driven networks (ADNs), accounting for the study of dynamics both on and of the ADN. By employing the susceptible-infected-susceptible (SIS) model, two aspects were considered: (1) the infection rate of susceptible agent (depending on the number of its infected neighbors) evolves due to the temporal structure of ADN, rather than being a constant number; (2) the susceptible and infected agents generate unequal links while being activated, namely, the susceptible agent gets few contacts with others in order to protect itself. Results show that, in both cases, the larger epidemic threshold and smaller outbreak size were obtained.

  5. Epidemic Increase in Methicillin-resistant Staphylococcus aureus in Copenhagen

    DEFF Research Database (Denmark)

    Westh, Henrik; Boye, Kit; Bartels, Mette Damkjær;

    2006-01-01

    in 2004. All isolates have been spa-typed and epidemiologic information collected. RESULTS: The number of MRSA cases has a doubling time of about six months. The epidemic has been caused by many different MRSA types and 31 staphylococcus protein A genotypes (spa types). MRSA has caused several hospital......INTRODUCTION: We have found an epidemic increase in methicillin-resistant Staphylococcus aureus (MRSA) in Copenhagen. The increase has a complex background and involves hospitals, nursing homes and persons nursed in their own home. MATERIAL AND METHODS: We found 33 MRSA patients in 2003 and 121...

  6. Modelling AIDS epidemic and treatment with difference equations

    Directory of Open Access Journals (Sweden)

    Ramani A

    2004-01-01

    Full Text Available We propose two models for the description of the dynamics of an AIDS epidemic and of the effect of a combined-drugs AIDS treatment based on difference equations. We show that our interacting population model, despite its extreme simplicity, describes adequately the evolution of an AIDS epidemic. A cellular-automaton analogue of the discrete system of equations is presented as well. In the case of drug treatment, we identify two different regimes corresponding to efficient and inefficient medication. The effect of the discreteness of the equations is also studied.

  7. Modelling AIDS epidemic and treatment with difference equations

    Directory of Open Access Journals (Sweden)

    A. S. Carstea

    2004-07-01

    Full Text Available We propose two models for the description of the dynamics of an AIDS epidemic and of the effect of a combined-drugs AIDS treatment based on difference equations. We show that our interacting population model, despite its extreme simplicity, describes adequately the evolution of an AIDS epidemic. A cellular-automaton analogue of the discrete system of equations is presented as well. In the case of drug treatment, we identify two different regimes corresponding to efficient and inefficient medication. The effect of the discreteness of the equations is also studied.

  8. Siting epidemic disease: 3 centuries of American history.

    Science.gov (United States)

    Rosenberg, Charles E

    2008-02-15

    Epidemics of infectious disease have always played a role in American history, and such epidemics are sited in time and place and configured in terms of ecology and demography, available medical knowledge, and cultural values and collective experience. The mix of these variables has changed dramatically since the theocratic world of 17th-century New England, but the relevance of each remains. Avian influenza already exists virtually in Western society in terms of planning, global networks, laboratory research, social expectations, media representations, and a specific shared history based on the memory of the 1918 influenza pandemic.

  9. An epidemic of influenza on Tristan da Cunha.

    Science.gov (United States)

    Mantle, J; Tyrrell, D A

    1973-03-01

    Respiratory disease on Tristan da Cunha has been observed since the islanders returned in 1962. An epidemic of unprecedented severity occurred in the winter of 1971 and involved 273 (96%) of 284 islanders, 92 of whom had two attacks.The epidemic was apparently introduced by the Tristania.The illness of both first and second attacks ranged from mild to severe but there were some differences. There were two deaths, both in elderly persons with chronic chest disease and heart failure. Serological evidence suggests that this was due to influenza A2 of the Hong Kong serotype H(3)N(2).

  10. Spatial Pattern of an Epidemic Model with Cross-diffusion

    Institute of Scientific and Technical Information of China (English)

    LI Li; JIN Zhen; SUN Gui-Quan

    2008-01-01

    Pattern formation of a spatial epidemic model with both serf- and cross-diffusion is investigated. From the Turing theory, it is well known that Thring pattern formation cannot occur for the equal self-diffusion coefficients.However, combined with cross-diffusion, the system will show emergence of isolated groups, i.e., stripe-like or spotted or coexistence of both, which we show by both mathematical ana/ysis and numerical simulations. Our study shows that the interaction of self- and cross-diffusion can be considered as an important mechanism for the appearance of complex spatiotemporal dynamics in epidemic models.

  11. Many-body methods in agent-based epidemic models

    CERN Document Server

    Nakamura, Gilberto M

    2016-01-01

    The susceptible-infected-susceptible (SIS) agent-based model is usually employed in the investigation of epidemics. The model describes a Markov process for a single communicable disease among susceptible (S) and infected (I) agents. However, the disease spreading forecasting is often restricted to numerical simulations, while analytic formulations lack both general results and perturbative approaches since they are subjected to asymmetric time generators. Here, we discuss perturbation theory, approximations and application of many-body techniques in epidemic models in the framework for squared norm of probability vector $|P(t)| ^2$, in which asymmetric time generators are replaced by their symmetric counterparts.

  12. Modular Epidemic Spreading in Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; GAO Zi-You

    2007-01-01

    We study the epidemic spreading of the susceptible-infected-susceptible model on small-world networks with modular structure.It is found that the epidemic threshold increases linearly with the modular strength.Furthermore,the modular structure may influence the infected density in the steady state and the spreading velocity at the beginning of propagation.Practically,the propagation can be hindered by strengthening the modular structure in the view of network topology.In addition,to reduce the probability of reconnection between modules may also help to control the propagation.

  13. Epidemic spreading and bond percolation in multilayer networks

    CERN Document Server

    Bianconi, Ginestra

    2016-01-01

    The Susceptible-Infected-Recovered (SIR) model is studied in multilayer networks with arbitrary number of links across the layers. By following the mapping to bond percolation we give the exact expression for the epidemic threshold and the fraction of the infected individuals in arbitrary number of layers. The case of a multilayer network formed by two interconnected networks is specifically studied as a function of the degree distribution within and across the layers. We show that the epidemic threshold strongly depends on the degree correlations of the multilayer structure. Finally we relate our results to the results obtained in the annealed approximation for the Susceptible-Infected-Susceptible (SIS) model.

  14. Modeling infectious diseases dissemination through online role-playing games.

    Science.gov (United States)

    Balicer, Ran D

    2007-03-01

    As mathematical modeling of infectious diseases becomes increasingly important for developing public health policies, a novel platform for such studies might be considered. Millions of people worldwide play interactive online role-playing games, forming complex and rich networks among their virtual characters. An unexpected outbreak of an infective communicable disease (unplanned by the game creators) recently occurred in this virtual world. This outbreak holds surprising similarities to real-world epidemics. It is possible that these virtual environments could serve as a platform for studying the dissemination of infectious diseases, and as a testing ground for novel interventions to control emerging communicable diseases.

  15. Observation of online communities

    DEFF Research Database (Denmark)

    Nørskov, Sladjana V.; Rask, Morten

    2011-01-01

    This paper addresses the application of observation to online settings with a special focus on observer roles. It draws on a study of online observation of a virtual community, i.e. an open source software (OSS) community. The paper examines general and specific advantages and disadvantages...... of the observer roles in online settings by relating these roles to the same roles assumed in offline settings. The study suggests that under the right circumstances online and offline observation may benefit from being combined as they complement each other well. Quality issues and factors important to elicit...... trustworthy observational data from online study settings, such as OSS communities, are discussed. A proposition is made concerning how threats to credibility and transferability in relation to online observation (i.e. lack of richness and detail, risk of misunderstandings) can be diminished, while...

  16. Non-Markovian character in human mobility: Online and offline

    Science.gov (United States)

    Zhao, Zhi-Dan; Cai, Shi-Min; Lu, Yang

    2015-06-01

    The dynamics of human mobility characterizes the trajectories that humans follow during their daily activities and is the foundation of processes from epidemic spreading to traffic prediction and information recommendation. In this paper, we investigate a massive data set of human activity, including both online behavior of browsing websites and offline one of visiting towers based mobile terminations. The non-Markovian character observed from both online and offline cases is suggested by the scaling law in the distribution of dwelling time at individual and collective levels, respectively. Furthermore, we argue that the lower entropy and higher predictability in human mobility for both online and offline cases may originate from this non-Markovian character. However, the distributions of individual entropy and predictability show the different degrees of non-Markovian character between online and offline cases. To account for non-Markovian character in human mobility, we apply a protype model with three basic ingredients, namely, preferential return, inertial effect, and exploration to reproduce the dynamic process of online and offline human mobilities. The simulations show that the model has an ability to obtain characters much closer to empirical observations.

  17. ONLINE PUBLISHING CURRENT SCENARIO

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan

    2012-12-01

    Full Text Available This article attempts to unravel the current scenario in online publishing. Advent of internet has brought with it tremendous changes in the publishing industry. What was hither to an industry dominated by publisher has been thrown open to one and sundry. Online publishing has brought with it a reach which was hitherto never been imagined. In the normal course it would take at least a year to publish a manuscript. Online publishing has managed to bring this time down to a few weeks / at most a month. This article attempts to discusses the positives and perils of online publishing scenario.

  18. Online shopping hesitation.

    Science.gov (United States)

    Cho, Chang-Hoan; Kang, Jaewon; Cheon, Hongsik John

    2006-06-01

    This study was designed to understand which factors influence consumer hesitation or delay in online product purchases. The study examined four groups of variables (i.e., consumer characteristics, contextual factors perceived uncertainty factors, and medium/channel innovation factors) that predict three types of online shopping hesitation (i.e., overall hesitation, shopping cart abandonment, and hesitation at the final payment stage). We found that different sets of delay factors are related to different aspects of online shopping hesitation. The study concludes with suggestion for various delay-reduction devices to help consumers close their online decision hesitation.

  19. Observation of online communities

    DEFF Research Database (Denmark)

    Nørskov, Sladjana V.; Rask, Morten

    2011-01-01

    This paper addresses the application of observation to online settings with a special focus on observer roles. It draws on a study of online observation of a virtual community, i.e. an open source software (OSS) community. The paper examines general and specific advantages and disadvantages...... of the observer roles in online settings by relating these roles to the same roles assumed in offline settings. The study suggests that under the right circumstances online and offline observation may benefit from being combined as they complement each other well. Quality issues and factors important to elicit...

  20. Online Shopping Woes

    Institute of Scientific and Technical Information of China (English)

    Hou Weili

    2011-01-01

    AS a frequent online shopper,Zhou Fangjie,a 28-year-old white-collar worker,was annoyed when she could not open Hanyidushe,an online shop selling Korean-style clothing on Taobao Mall.Her experience resulted from the online protest initiated by small vendors on Taobao Mall,China's largest business to consumer online platform.Thousands of small vendors started the protest against larger established vendors by discrediting them through False orders,forming an anti-Taobao Union and setting up a chat room to devise ways to disrupt operations on Taobao Mall.

  1. Online organic chemistry

    Science.gov (United States)

    Janowicz, Philip A.

    This is a comprehensive study of the many facets of an entirely online organic chemistry course. Online homework with structure-drawing capabilities was found to be more effective than written homework. Online lecture was found to be just as effective as in-person lecture, and students prefer an online lecture format with shorter Webcasts. Online office hours were found to be effective, and discussion sessions can be placed online as well. A model was created that explains 36.1% of student performance based on GPA, ACT Math score, grade in previous chemistry course, and attendance at various forms of discussion. Online exams have been created which test problem-solving skills and is instantly gradable. In these exams, students can submit answers until time runs out for different numbers of points. These facets were combined effectively to create an entirely online organic chemistry course which students prefer over the in-person alternative. Lastly, there is a vision for where online organic chemistry is going and what can be done to improve education for all.

  2. Potato late blight epidemics and population structure of Phytophthora infestans.

    NARCIS (Netherlands)

    Zwankhuizen, M.J.

    1998-01-01

    Potato late blight is caused by the fungus Phytophthora infestans . To study the relative importance of oospores in the epidemiology, and to estimate the relative impact of various infection sources, late blight epidemics in Southern Flevoland (The Netherlands) were studied using epidemiological and

  3. Optimal control of a dengue epidemic model with vaccination

    CERN Document Server

    Rodrigues, Helena Sofia; Torres, Delfim F M

    2011-01-01

    We present a SIR+ASI epidemic model to describe the interaction between human and dengue fever mosquito populations. A control strategy in the form of vaccination, to decrease the number of infected individuals, is used. An optimal control approach is applied in order to find the best way to fight the disease.

  4. The global spread of HIV-1 subtype B epidemic.

    Science.gov (United States)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G; Lepej, Snjezana J; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie-Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne-Mieke; Paraskevis, Dimitrios

    2016-12-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti to United States. However, the pattern of the subsequent spread still remains poorly understood. Here we analyze a large dataset of globally representative HIV-1 subtype B strains to map their spread around the world over the last 50years and describe significant spread patterns. We show that subtype B travelled from North America to Western Europe in different occasions, while Central/Eastern Europe remained isolated for the most part of the early epidemic. Looking with more detail in European countries we see that the United Kingdom, France and Switzerland exchanged viral isolates with non-European countries than with European ones. The observed pattern is likely to mirror geopolitical landmarks in the post-World War II era, namely the rise and the fall of the Iron Curtain and the European colonialism. In conclusion, HIV-1 spread through specific migration routes which are consistent with geopolitical factors that affected human activities during the last 50years, such as migration, tourism and trade. Our findings support the argument that epidemic control policies should be global and incorporate political and socioeconomic factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Molecular evolution and the natural history of select virus epidemics

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne

    Molecular evolution of pathogenic viruses with RNA based genomes is most often fast enough to leave an informative genomic sequence signal within a timeframe that is relevant for the study of both recent and on-­‐going epidemics (and epizootics). The true power of molecular evolutionary methodology...

  6. Using clinicians' search query data to monitor influenza epidemics.

    Science.gov (United States)

    Santillana, Mauricio; Nsoesie, Elaine O; Mekaru, Sumiko R; Scales, David; Brownstein, John S

    2014-11-15

    Search query information from a clinician's database, UpToDate, is shown to predict influenza epidemics in the United States in a timely manner. Our results show that digital disease surveillance tools based on experts' databases may be able to provide an alternative, reliable, and stable signal for accurate predictions of influenza outbreaks.

  7. Containing epidemic outbreaks by message-passing techniques

    CERN Document Server

    Altarelli, F; Dall'Asta, L; Wakeling, J R; Zecchina, R

    2013-01-01

    The problem of targeted network immunization can be defined as the one of finding a subset of nodes in a network to immunize or vaccinate in order to minimize a tradeoff between the cost of vaccination and the final (stationary) expected infection under a given epidemic model. Although computing the expected infection is a hard computational problem, simple and efficient mean-field approximations have been put forward in the literature in recent years. The optimization problem can be recast into a constrained one in which the constraints enforce local mean-field equations describing the average stationary state of the epidemic process. For a wide class of epidemic models, including the susceptible-infected-removed and the susceptible-infected-susceptible models, we define a message-passing approach to network immunization that allows us to study the statistical properties of epidemic outbreaks in the presence of immunized nodes as well as to find (nearly) optimal immunization sets for a given choice of parame...

  8. The influence of the school year on measles epidemics

    DEFF Research Database (Denmark)

    Andreasen, Viggo

    The measles incidence record for Copenhagen 1880-1966 shows that the date of admission of new pupils has major impact on the structure of the epidemics, suggesting that measles transmission should be modelled in a way that accounts for the pulsed influx of new pupils. Assuming that the school year...

  9. Predicting Development of an Epidemics on Cultivar Mixtures

    DEFF Research Database (Denmark)

    Østergård, Hanne

    1983-01-01

    A mathematical model for the development of an epidemic on a plant cultivar mixture illustrates the influence of the infection efficiency, spore production rate, proportion of deposited spores, frequency of autodeposition, and composition of the mixture on the genetic composition of the pathogen...

  10. Vaccination Control in a Stochastic SVIR Epidemic Model.

    Science.gov (United States)

    Witbooi, Peter J; Muller, Grant E; Van Schalkwyk, Garth J

    2015-01-01

    For a stochastic differential equation SVIR epidemic model with vaccination, we prove almost sure exponential stability of the disease-free equilibrium for ℛ(0) stochastic model as well as for the underlying deterministic model. In order to solve the stochastic problem numerically, we use an approximation based on the solution of the deterministic model.

  11. A canine distemper virus epidemic in Serengeti lions (Panthera leo).

    Science.gov (United States)

    Roelke-Parker, M E; Munson, L; Packer, C; Kock, R; Cleaveland, S; Carpenter, M; O'Brien, S J; Pospischil, A; Hofmann-Lehmann, R; Lutz, H; Mwamengele, G L; Mgasa, M N; Machange, G A; Summers, B A; Appel, M J

    1996-02-01

    Canine distemper virus (CDV) is thought to have caused several fatal epidemics in canids within the Serengeti-Mara ecosystem of East Africa, affecting silver-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis) in 1978 (ref. 1), and African wild dogs (Lycaon pictus) in 1991 (refs 2, 3). The large, closely monitored Serengeti lion population was not affected in these epidemics. However, an epidemic caused by a morbillivirus closely related to CDV emerged abruptly in the lion population of the Serengeti National Park, Tanzania, in early 1994, resulting in fatal neurological disease characterized by grand mal seizures and myoclonus; the lions that died had encephalitis and pneumonia. Here we report the identification of CDV from these lions, and the close phylogenetic relationship between CDV isolates from lions and domestic dogs. By August 1994, 85% of the Serengeti lion population had anti-CDV antibodies, and the epidemic spread north to lions in the Maasai Mara National reserve, Kenya, and uncounted hyaenas, bat-eared foxes, and leopards were also affected.

  12. A hidden HIV epidemic among women in Vietnam

    NARCIS (Netherlands)

    T.A. Nguyen; P. Oosterhoff; A. Hardon; H.N. Tran; R.A. Coutinho; P. Wright

    2008-01-01

    Background: The HIV epidemic in Vietnam is still concentrated among high risk populations, including IDU and FSW. The response of the government has focused on the recognized high risk populations, mainly young male drug users. This concentration on one high risk population may leave other populatio

  13. Using Clinicians’ Search Query Data to Monitor Influenza Epidemics

    Science.gov (United States)

    Santillana, Mauricio; Nsoesie, Elaine O.; Mekaru, Sumiko R.; Scales, David; Brownstein, John S.

    2014-01-01

    Search query information from a clinician's database, UpToDate, is shown to predict influenza epidemics in the United States in a timely manner. Our results show that digital disease surveillance tools based on experts' databases may be able to provide an alternative, reliable, and stable signal for accurate predictions of influenza outbreaks. PMID:25115873

  14. Epidemic Processes on Complex Networks: Modelling, Simulation and Algorithms

    NARCIS (Netherlands)

    Van de Bovenkamp, R.

    2015-01-01

    Local interactions on a graph will lead to global dynamic behaviour. In this thesis we focus on two types of dynamic processes on graphs: the Susceptible-Infected-Susceptilbe (SIS) virus spreading model, and gossip style epidemic algorithms. The largest part of this thesis is devoted to the SIS mode

  15. Information Spreading in Epidemics and in Communication Networks

    DEFF Research Database (Denmark)

    Uekermann, Florian Philipp

    The PhD thesis revolves mainly around models of disease spreading and human behavior. We present models for different epidemic patterns of infectious diseases. This includes investigations of the trajectory of the 2014 Ebola outbreak in West-Africa, influenza evolution and the seasonal dynamics...

  16. The effect of awareness on networked SIS epidemics

    KAUST Repository

    Paarporn, Keith

    2017-01-05

    We study an SIS epidemic model over an arbitrary fixed network topology where the n agents, or nodes of the network, have partial information about the epidemic state. The agents react by distancing themselves from their neighbors when they believe the epidemic is currently prevalent. An agent\\'s awareness is weighted from three sources of information: the fraction of infected neighbors in their contact network, their social network, and a global broadcast of the fraction of infected nodes in the entire network. The dynamics of the benchmark (no awareness) and awareness models are described by discrete-time 2-state Markov chains. Through a coupling technique, we establish monotonicity properties between the benchmark and awareness models. Particularly, we show that the expectation of any increasing random variable on the space of sample paths, e.g. eradication time or total infections, is lower for the awareness model. In addition, we give a characterization for this difference of expectations in terms of the coupling distribution. In simulations, we evaluate how different sources of information affect the spread of an epidemic.

  17. development of an epidemic early warning system in Mpwapwa ...

    African Journals Online (AJOL)

    Using retrospective epidemiological data to determine malaria epidemic prone areas and ... 3Regional Medical Ojfice, P.O. Box 904, Dodoma, Tanzania ... Similarly, a remarkably high number of severely affected and admitted malaria patients were recorded in 1999 .... examined in the laboratories were positive for malaria.

  18. Disease-induced resource constraints can trigger explosive epidemics

    CERN Document Server

    Böttcher, Lucas; Araújo, Nuno A M; Herrmann, Hans J; Helbing, Dirk

    2015-01-01

    Advances in mathematical epidemiology have led to a better understanding of the risks posed by epidemic spreading and informed strategies to contain disease spread. However, a challenge that has been overlooked is that, as a disease becomes more prevalent, it can limit the availability of the capital needed to effectively treat those who have fallen ill. Here we use a simple mathematical model to gain insight into the dynamics of an epidemic when the recovery of sick individuals depends on the availability of healing resources that are generated by the healthy population. We find that epidemics spiral out of control into "explosive" spread if the cost of recovery is above a critical cost. This can occur even when the disease would die out without the resource constraint. The onset of explosive epidemics is very sudden, exhibiting a discontinuous transition under very general assumptions. We find analytical expressions for the critical cost and the size of the explosive jump in infection levels in terms of the...

  19. STUDY ON AN SIS EPIDEMIC MODEL WITH TIME VARIANT DELAY

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper,we study an SIS epidemic model with a time variant delay.By means of Liapunov functional,some sufficient conditions of global stability to endemic equilibrium and disease free equilibrium have been obtained.The influence of time delay on the stability of equilibria is displayed.

  20. STUDY ON AN SIS EPIDEMIC MODEL WITH TIME VARIANT DELAY

    Institute of Scientific and Technical Information of China (English)

    YUAN Sanling; MA Zhien

    2002-01-01

    In this paper, we study an SIS epidemic model with a time variant delay.By means of Liapunov functional, some sufficient conditions of global stability to endemic equilibrium and disease free equilibrium have been obtained. The influence of time delay on the stability of equilibria is displayed.

  1. Epidemic Increase in Methicillin-resistant Staphylococcus aureus in Copenhagen

    DEFF Research Database (Denmark)

    Westh, Henrik; Boye, Kit; Bartels, Mette Damkjær

    2006-01-01

    INTRODUCTION: We have found an epidemic increase in methicillin-resistant Staphylococcus aureus (MRSA) in Copenhagen. The increase has a complex background and involves hospitals, nursing homes and persons nursed in their own home. MATERIAL AND METHODS: We found 33 MRSA patients in 2003 and 121...

  2. The looming epidemic of diabetes-associated tuberculosis

    DEFF Research Database (Denmark)

    Harries, A D; Lin, Y; Satyanarayana, S

    2011-01-01

    The prevalence of diabetes mellitus is increasing at a dramatic rate, and countries in Asia, particularly India and China, will bear the brunt of this epidemic. Persons with diabetes have a significantly increased risk of active tuberculosis (TB), which is two to three times higher than in persons...

  3. Epidemic processes over adaptive state-dependent networks

    Science.gov (United States)

    Ogura, Masaki; Preciado, Victor M.

    2016-06-01

    In this paper we study the dynamics of epidemic processes taking place in adaptive networks of arbitrary topology. We focus our study on the adaptive susceptible-infected-susceptible (ASIS) model, where healthy individuals are allowed to temporarily cut edges connecting them to infected nodes in order to prevent the spread of the infection. In this paper we derive a closed-form expression for a lower bound on the epidemic threshold of the ASIS model in arbitrary networks with heterogeneous node and edge dynamics. For networks with homogeneous node and edge dynamics, we show that the resulting lower bound is proportional to the epidemic threshold of the standard SIS model over static networks, with a proportionality constant that depends on the adaptation rates. Furthermore, based on our results, we propose an efficient algorithm to optimally tune the adaptation rates in order to eradicate epidemic outbreaks in arbitrary networks. We confirm the tightness of the proposed lower bounds with several numerical simulations and compare our optimal adaptation rates with popular centrality measures.

  4. A social contagious model of the obesity epidemic

    Science.gov (United States)

    Huang, He; Yan, Zhijun; Chen, Yahong; Liu, Fangyan

    2016-11-01

    Obesity has been recognized as a global epidemic by WHO, followed by many empirical evidences to prove its infectiousness. However, the inter-person spreading dynamics of obesity are seldom studied. A distinguishing feature of the obesity epidemic is that it is driven by a social contagion process which cannot be perfectly described by the infectious disease models. In this paper, we propose a novel belief decision model based on the famous Dempster-Shafer theory of evidence to model obesity epidemic as the competing spread of two obesity-related behaviors: physical inactivity and physical activity. The transition of health states is described by an SIS model. Results reveal the existence of obesity epidemic threshold, above which obesity is quickly eradicated. When increasing the fading level of information spread, enlarging the clustering of initial obese seeds, or introducing small-world characteristics into the network topology, the threshold is easily met. Social discrimination against the obese people plays completely different roles in two cases: on one hand, when obesity cannot be eradicated, social discrimination can reduce the number of obese people; on the other hand, when obesity is eradicable, social discrimination may instead cause it breaking out.

  5. Can weight management programs in worksites reduce the obesity epidemic?

    Science.gov (United States)

    Worksites can potentially be important locations for weight management programs that contribute to curbing the national obesity epidemic. In published studies, weight loss programs targeting overweight and obese employees have been relatively more effective for weight loss than programs for preventi...

  6. Recovery rate affects the effective epidemic threshold with synchronous updating.

    Science.gov (United States)

    Shu, Panpan; Wang, Wei; Tang, Ming; Zhao, Pengcheng; Zhang, Yi-Cheng

    2016-06-01

    Accurate identification of effective epidemic threshold is essential for understanding epidemic dynamics on complex networks. In this paper, we systematically study how the recovery rate affects the susceptible-infected-removed spreading dynamics on complex networks, where synchronous and asynchronous updating processes are taken into account. We derive the theoretical effective epidemic threshold and final outbreak size based on the edge-based compartmental theory. To validate the proposed theoretical predictions, extensive numerical experiments are implemented by using asynchronous and synchronous updating methods. When asynchronous updating method is used in simulations, recovery rate does not affect the final state of spreading dynamics. But with synchronous updating, we find that the effective epidemic threshold decreases with recovery rate, and final outbreak size increases with recovery rate. A good agreement between the theoretical predictions and the numerical results are observed on both synthetic and real-world networks. Our results extend the existing theoretical studies and help us to understand the phase transition with arbitrary recovery rate.

  7. Effects of Variant Rates and Noise on Epidemic Spreading

    Institute of Scientific and Technical Information of China (English)

    LI Wei; GAO Zong-Mao; GU Jiao

    2011-01-01

    We introduce variant rates, for both infection and recovery and noise into the susceptible-infected-removed (SIR)model for epidemic spreading. The changing rates are taken mainly due to the changing profiles of an epidemic during its evolution. However, the noise parameter which is taken from a given distribution, i.e. Gaussian can describe the fluctuations of the infection and recovery rates. The numerical simulations show that the SIR model with variant rates and noise and can improve the fitting with real SARS data in the near-stationary stage.%@@ We introduce variant rates,for both infection and recovery and noise into the susceptible-infected-removed(SIR)modelfor epidemic spreading.The changing rates are taken mainly due to the changing profiles of an epidemic during its evolution.However,the noise parameter which is taken from a given distribution,i.e.Gaussian can describe the fluctuations of the infection and recovery rates.The numerical simulations show that the SIR model with variant rates and noise and can improve the fitting with real SARS data in the near-stationary stage.

  8. Understanding the epidemic of HIV in South Africa

    African Journals Online (AJOL)

    growth rate and probable asymptotic prevalence of HIV among women attending ... intrinsic growth rate of the epidemic in different provinces and the ..... A pharma meta-anal. Fran'rois W. Osman Eb. Objectives assess the antibiotic ... treatment assumptio. Outcome. Franyois. Anderson. A Nixon A. Roche Pr. Osman E.

  9. Efficient mitigation strategies for epidemics in rural regions.

    Science.gov (United States)

    Scoglio, Caterina; Schumm, Walter; Schumm, Phillip; Easton, Todd; Roy Chowdhury, Sohini; Sydney, Ali; Youssef, Mina

    2010-07-13

    Containing an epidemic at its origin is the most desirable mitigation. Epidemics have often originated in rural areas, with rural communities among the first affected. Disease dynamics in rural regions have received limited attention, and results of general studies cannot be directly applied since population densities and human mobility factors are very different in rural regions from those in cities. We create a network model of a rural community in Kansas, USA, by collecting data on the contact patterns and computing rates of contact among a sampled population. We model the impact of different mitigation strategies detecting closely connected groups of people and frequently visited locations. Within those groups and locations, we compare the effectiveness of random and targeted vaccinations using a Susceptible-Exposed-Infected-Recovered compartmental model on the contact network. Our simulations show that the targeted vaccinations of only 10% of the sampled population reduced the size of the epidemic by 34.5%. Additionally, if 10% of the population visiting one of the most popular locations is randomly vaccinated, the epidemic size is reduced by 19%. Our results suggest a new implementation of a highly effective strategy for targeted vaccinations through the use of popular locations in rural communities.

  10. Some Empirical Notes on the Epo Epidemic in Professional Cycling

    Science.gov (United States)

    Lodewijkx, Hein F. M.; Brouwer, Bram

    2011-01-01

    The 1990-2010 period in professional cycling is labeled by some as the epo epidemic. Surprisingly, performance enhancement by epo and blood doping is not that clear-cut for endurance athletes, leading to the question whether doping indeed strongly influenced cyclists' performances from the 1990s onwards. We examined the records (1947-2008) of the…

  11. GLOBAL STABILITY OF AN SIRS EPIDEMIC MODEL WITH DELAYS

    Institute of Scientific and Technical Information of China (English)

    Zhen Jin; Ma Zhien; Han Maoan

    2006-01-01

    In this article, an SIRS epidemic model spread by vectors (mosquitoes) which have an incubation time to become infectious is formulated. It is shown that a disease-free equilibrium point is globally stable if no endemic equilibrium point exists. Further, the endemic equilibrium point (if it exists) is globally stable with a respect "weak delay". Some known results are generalized.

  12. Information Spreading in Epidemics and in Communication Networks

    DEFF Research Database (Denmark)

    Uekermann, Florian Philipp

    The PhD thesis revolves mainly around models of disease spreading and human behavior. We present models for different epidemic patterns of infectious diseases. This includes investigations of the trajectory of the 2014 Ebola outbreak in West-Africa, influenza evolution and the seasonal dynamics o...

  13. The Schmallenberg virus epidemic in Europe 2011-2013

    NARCIS (Netherlands)

    Afonso, A.; Abrahantes, J.C.; Conraths, F.; Veldhuis, A.E.; Elbers, A.R.W.

    2014-01-01

    During the Schmallenberg virus (SBV) epidemic, the European Food Safety Authority (EFSA) collected data on SBV occurrence across Europe in order to provide an assessment of spread and impact. By May 2013, twenty-nine countries were reporting to EFSA and twenty-two countries had reported cases of SBV

  14. Molecular evolution and the natural history of select virus epidemics

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne

    Molecular evolution of pathogenic viruses with RNA based genomes is most often fast enough to leave an informative genomic sequence signal within a timeframe that is relevant for the study of both recent and on-­‐going epidemics (and epizootics). The true power of molecular evolutionary methodolo...

  15. Epidemics in Networks: Modeling, Optimization and Security Games

    NARCIS (Netherlands)

    Omic, J.

    2010-01-01

    Epidemic theory has wide range of applications in computer networks, from spreading of malware to the information dissemination algorithms. Our society depends more strongly than ever on such computer networks. Many of these networks rely to a large extent on decentralization and self-organization.

  16. Stationary distribution of a stochastic SIS epidemic model with vaccination

    Science.gov (United States)

    Lin, Yuguo; Jiang, Daqing; Wang, Shuai

    2014-01-01

    In this paper, we consider a stochastic SIS epidemic model with vaccination. We prove that the densities of the distributions of the solution can converge in L1 to an invariant density under appropriate conditions. Also we find the support of the invariant density.

  17. Urban epidemic of dengue virus serotype 3 infection, Senegal, 2009.

    Science.gov (United States)

    Faye, Ousmane; Ba, Yamar; Faye, Oumar; Talla, Cheikh; Diallo, Diawo; Chen, Rubing; Mondo, Mireille; Ba, Rouguiétou; Macondo, Edgard; Siby, Tidiane; Weaver, Scott C; Diallo, Mawlouth; Sall, Amadou Alpha

    2014-03-01

    An urban epidemic of dengue in Senegal during 2009 affected 196 persons and included 5 cases of dengue hemorrhagic fever and 1 fatal case of dengue shock syndrome. Dengue virus serotype 3 was identified from all patients, and Aedes aegypti mosquitoes were identified as the primary vector of the virus.

  18. Predicting epidemic evolution on contact networks from partial observations

    CERN Document Server

    Bindi, Jacopo; Dall'Asta, Luca

    2016-01-01

    The massive employment of computational models in network epidemiology calls for the development of improved inference methods for epidemic forecast. For simple compartment models, such as the Susceptible-Infected-Recovered model, Belief Propagation was proved to be a reliable and efficient method to identify the origin of an observed epidemics. Here we show that the same method can be applied to predict the future evolution of an epidemic outbreak from partial observations at the early stage of the dynamics. The results obtained using Belief Propagation are compared with Monte Carlo direct sampling in the case of SIR model on random (regular and power-law) graphs for different observation methods and on an example of real-world contact network. Belief Propagation gives in general a better prediction that direct sampling, although the quality of the prediction depends on the quantity under study (e.g. marginals of individual states, epidemic size, extinction-time distribution) and on the actual number of obse...

  19. Neoliberal science, Chinese style: Making and managing the 'obesity epidemic'.

    Science.gov (United States)

    Greenhalgh, Susan

    2016-08-01

    Science and Technology Studies has seen a growing interest in the commercialization of science. In this article, I track the role of corporations in the construction of the obesity epidemic, deemed one of the major public health threats of the century. Focusing on China, a rising superpower in the midst of rampant, state-directed neoliberalization, I unravel the process, mechanisms, and broad effects of the corporate invention of an obesity epidemic. Largely hidden from view, Western firms were central actors at every stage in the creation, definition, and governmental management of obesity as a Chinese disease. Two industry-funded global health entities and the exploitation of personal ties enabled actors to nudge the development of obesity science and policy along lines beneficial to large firms, while obscuring the nudging. From Big Pharma to Big Food and Big Soda, transnational companies have been profiting from the 'epidemic of Chinese obesity', while doing little to effectively treat or prevent it. The China case suggests how obesity might have been constituted an 'epidemic threat' in other parts of the world and underscores the need for global frameworks to guide the study of neoliberal science and policymaking.

  20. Some Empirical Notes on the Epo Epidemic in Professional Cycling

    Science.gov (United States)

    Lodewijkx, Hein F. M.; Brouwer, Bram

    2011-01-01

    The 1990-2010 period in professional cycling is labeled by some as the epo epidemic. Surprisingly, performance enhancement by epo and blood doping is not that clear-cut for endurance athletes, leading to the question whether doping indeed strongly influenced cyclists' performances from the 1990s onwards. We examined the records (1947-2008) of the…

  1. Towards flexible decision support in thecontrol of animal epidemics

    NARCIS (Netherlands)

    Ge, L.; Mourits, M.C.M.; Huirne, R.B.M.

    2007-01-01

    Decision-making in the control of animal epidemics is a dynamic and flexible process. Facing uncertainties about the consequences of control options, flexible decision-making can avoid unnecessary control costs through learning and adjusting. While recognising the importance and complexity of decisi

  2. The Curse of Frybread: The Diabetes Epidemic in Indian Country.

    Science.gov (United States)

    Hill, Mary Anne

    1997-01-01

    Diabetes among American Indians has become epidemic since World War II, due to dietary changes and a possible genetic predisposition. Innovative community-based programs teach prevention and management of diabetes through exercise, diet, and blood sugar monitoring. Traditional American Indian lifestyles and diets prevented diabetes. Sidebars…

  3. An HIV epidemic is ready to emerge in the Philippines

    Directory of Open Access Journals (Sweden)

    Farr Anna C

    2010-04-01

    Full Text Available Abstract Background The state of the HIV epidemic in the Philippines has been described as "low and slow", which is in stark contrast to many other countries in the region. A review of the conditions for HIV spread in the Philippines is necessary. Methods We evaluated the current epidemiology, trends in behaviour and public health response in the Philippines to identify factors that could account for the current HIV epidemic, as well as to review conditions that may be of concern for facilitating an emerging epidemic. Results The past control of HIV in the Philippines cannot be attributed to any single factor, nor is it necessarily a result of the actions of the Filipino government or other stakeholders. Likely reasons for the epidemic's slow development include: the country's geography is complicated; injecting drug use is relatively uncommon; a culture of sexual conservatism exists; sex workers tend to have few clients; anal sex is relatively uncommon; and circumcision rates are relatively high. In contrast, there are numerous factors suggesting that HIV is increasing and ready to emerge at high rates, including: the lowest documented rates of condom use in Asia; increasing casual sexual activity; returning overseas Filipino workers from high-prevalence settings; widespread misconceptions about HIV/AIDS; and high needle-sharing rates among injecting drug users. There was a three-fold increase in the rate of HIV diagnoses in the Philippines between 2003 and 2008, and this has continued over the past year. HIV diagnoses rates have noticeably increased among men, particularly among bisexual and homosexual men (114% and 214% respective increases over 2003-2008. The average age of diagnosis has also significantly decreased, from approximately 36 to 29 years. Conclusions Young adults, men who have sex with men, commercial sex workers, injecting drug users, overseas Filipino workers, and the sexual partners of people in these groups are particularly

  4. Rainfall mediations in the spreading of epidemic cholera

    Science.gov (United States)

    Righetto, L.; Bertuzzo, E.; Mari, L.; Schild, E.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2013-10-01

    Following the empirical evidence of a clear correlation between rainfall events and cholera resurgence that was observed in particular during the recent outbreak in Haiti, a spatially explicit model of epidemic cholera is re-examined. Specifically, we test a multivariate Poisson rainfall generator, with parameters varying in space and time, as a driver of enhanced disease transmission. The relevance of the issue relates to the key insight that predictive mathematical models may provide into the course of an ongoing cholera epidemic aiding emergency management (say, in allocating life-saving supplies or health care staff) or in evaluating alternative management strategies. Our model consists of a set of dynamical equations (SIRB-like i.e. subdivided into the compartments of Susceptible, Infected and Recovered individuals, and including a balance of Bacterial concentrations in the water reservoir) describing a connected network of human communities where the infection results from the exposure to excess concentrations of pathogens in the water. These, in turn, are driven by rainfall washout of open-air defecation sites or cesspool overflows, hydrologic transport through waterways and by mobility of susceptible and infected individuals. We perform an a posteriori analysis (from the beginning of the epidemic in October 2010 until December 2011) to test the model reliability in predicting cholera cases and in testing control measures, involving vaccination and sanitation campaigns, for the ongoing epidemic. Even though predicting reliably the timing of the epidemic resurgence proves difficult due to rainfall inter-annual variability, we find that the model can reasonably quantify the total number of reported infection cases in the selected time-span. We then run a multi-seasonal prediction of the course of the epidemic until December 2015, to investigate conditions for further resurgences and endemicity of cholera in the region with a view to policies which may bring to

  5. The severe acute respiratory syndrome epidemic in mainland China dissected

    Directory of Open Access Journals (Sweden)

    Wuchun Cao

    2011-02-01

    Full Text Available This paper provides a review of a recently published series of studies that give a detailed and comprehensive documentation of the severe acute respiratory syndrome (SARS epidemic in mainland China, which severely struck the country in the spring of 2003. The epidemic spanned a large geographical extent but clustered in two areas: first in Guangdong Province, and about 3 months later in Beijing with its surrounding areas. Reanalysis of all available epidemiological data resulted in a total of 5327 probable cases of SARS, of whom 343 died. The resulting case fatality ratio (CFR of 6.4% was less than half of that in other SARS-affected countries or areas, and this difference could only partly be explained by younger age of patients and higher number of community acquired infections. Analysis of the impact of interventions demonstrated that strong political commitment and a centrally coordinated response was the most important factor to control SARS in mainland China, whereas the most stringent control measures were all initiated when the epidemic was already dying down. The long-term economic consequence of the epidemic was limited, much consumption was merely postponed, but for Beijing irrecoverable losses to the tourist sector were considerable. An important finding from a cohort study was that many former SARS patients currently suffer from avascular osteo­necrosis, as a consequence of the treatment with corticosteroids during their infection. The SARS epidemic provided valuable information and lessons relevant in controlling outbreaks of newly emerging infectious diseases, and has led to fundamental reforms of the Chinese health system. In particular, a comprehensive nation-wide internet-based disease reporting system was established.

  6. Dynamic optimization model for allocating medical resources in epidemic controlling

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2013-03-01

    Full Text Available Purpose: The model proposed in this paper addresses a dynamic optimization model for allocating medical resources in epidemic controlling.Design/methodology/approach: In this work, a three-level and dynamic linear programming model for allocating medical resources based on epidemic diffusion model is proposed. The epidemic diffusion model is used to construct the forecasting mechanism for dynamic demand of medical resources. Heuristic algorithm coupled with MTLAB mathematical programming solver is adopted to solve the model. A numerical example is presented for testing the model’s practical applicability.Findings: The main contribution of the present study is that a discrete time-space network model to study the medical resources allocation problem when an epidemic outbreak is formulated. It takes consideration of the time evolution and dynamic nature of the demand, which is different from most existing researches on medical resources allocation.Practical implications: In our model, the medicine logistics operation problem has been decomposed into several mutually correlated sub-problems, and then be solved systematically in the same decision scheme. Thus, the result will be much more suitable for real operations.Originality/value: In our model, the rationale that the medical resources allocated in early periods will take effect in subduing the spread of the epidemic spread and thus impact the demand in later periods has been for the first time incorporated. A win-win emergency rescue effect is achieved by the integrated and dynamic optimization model. The total rescue cost is controlled effectively, and meanwhile, inventory level in each urban health departments is restored and raised gradually.

  7. Climate-based models for understanding and forecasting dengue epidemics.

    Directory of Open Access Journals (Sweden)

    Elodie Descloux

    Full Text Available BACKGROUND: Dengue dynamics are driven by complex interactions between human-hosts, mosquito-vectors and viruses that are influenced by environmental and climatic factors. The objectives of this study were to analyze and model the relationships between climate, Aedes aegypti vectors and dengue outbreaks in Noumea (New Caledonia, and to provide an early warning system. METHODOLOGY/PRINCIPAL FINDINGS: Epidemiological and meteorological data were analyzed from 1971 to 2010 in Noumea. Entomological surveillance indices were available from March 2000 to December 2009. During epidemic years, the distribution of dengue cases was highly seasonal. The epidemic peak (March-April lagged the warmest temperature by 1-2 months and was in phase with maximum precipitations, relative humidity and entomological indices. Significant inter-annual correlations were observed between the risk of outbreak and summertime temperature, precipitations or relative humidity but not ENSO. Climate-based multivariate non-linear models were developed to estimate the yearly risk of dengue outbreak in Noumea. The best explicative meteorological variables were the number of days with maximal temperature exceeding 32°C during January-February-March and the number of days with maximal relative humidity exceeding 95% during January. The best predictive variables were the maximal temperature in December and maximal relative humidity during October-November-December of the previous year. For a probability of dengue outbreak above 65% in leave-one-out cross validation, the explicative model predicted 94% of the epidemic years and 79% of the non epidemic years, and the predictive model 79% and 65%, respectively. CONCLUSIONS/SIGNIFICANCE: The epidemic dynamics of dengue in Noumea were essentially driven by climate during the last forty years. Specific conditions based on maximal temperature and relative humidity thresholds were determinant in outbreaks occurrence. Their persistence was

  8. Epidemiological description of unmitigated cholera epidemics in 19th century Denmark

    DEFF Research Database (Denmark)

    Phelps, Matthew David; Perner, Mads Linnet; Davidsen, Emma;

    Background. Cholera epidemics devastated 19th century European cities in multiple outbreaks during 1830-1900. Most Danish cities experienced only a single epidemic in 1853 and detailed data are available. This uniquely allows study of unmitigated epidemic cholera in a fully susceptible population...

  9. On the political economy of plant disease epidemics : capita selecta in historical epidemiology

    NARCIS (Netherlands)

    Zadoks, J.C.

    2008-01-01

    Food security has been and always will be a human concern. Food security has always been fragile, threatened by a variety of factors including plant disease epidemics. Several plant disease epidemics of the past lead to questions like: What happened? How did people deal with these epidemics? What we

  10. Viral conductance : Quantifying the robustness of networks with respect to spread of epidemics

    NARCIS (Netherlands)

    Youssef, M.; Kooij, R.E.; Scoglio, C.

    2011-01-01

    In this paper, we propose a novel measure, viral conductance (VC), to assess the robustness of complex networks with respect to the spread of SIS epidemics. In contrast to classical measures that assess the robustness of networks based on the epidemic threshold above which an epidemic takes place, t

  11. Consumers' Online Brand Endorsements

    NARCIS (Netherlands)

    Bernritter, S.F.; Verlegh, P.W.J.; Smit, E.G.; De Pelsmacker, P.

    2016-01-01

    Abstract Purpose and Approach This Chapter has three central goals: First, it aims to introduce the concept of consumers’ online brand endorsements, which we define as consumers’ intentional, public, and positive online affiliations with brands (e.g., liking a brand page on Facebook). Second, it pro

  12. Quality online personalisation

    NARCIS (Netherlands)

    T. Li (Ting); T. Unger (Till)

    2012-01-01

    textabstractWhen done right, personalisation online can be an effective way to enhance the buying or consuming experience, thus stimulating purchasing. However, it can also rely heavily on customers’ private details, a very sensitive and currently hot issue. So, how do online marketeers deal with th

  13. Framework for online teaching

    DEFF Research Database (Denmark)

    Strobel, Bjarne W.

    2014-01-01

    The following framework for online teaching is a guidance to inspire you on how to to use e-learning in your teaching. Maybe you want to make a whole online course (distance learning) or maybe you want to use e-learning as a part of a course (blended learning). If you want to go further or have...

  14. StuDIY Online

    DEFF Research Database (Denmark)

    2015-01-01

    StuDIY Online er kurser i akademisk argumentation, problemformulering, analyse og akademisk sprog. Kurserne er frit tilgængelige for alle via Blackboard på AU......StuDIY Online er kurser i akademisk argumentation, problemformulering, analyse og akademisk sprog. Kurserne er frit tilgængelige for alle via Blackboard på AU...

  15. Consumers' Online Brand Endorsements

    NARCIS (Netherlands)

    Bernritter, S.F.; Verlegh, P.W.J.; Smit, E.G.; De Pelsmacker, P.

    2016-01-01

    Purpose and Approach This Chapter has three central goals: First, it aims to introduce the concept of consumers’ online brand endorsements, which we define as consumers’ intentional, public, and positive online affiliations with brands (e.g., liking a brand page on Facebook). Second, it provides an

  16. Online Reading Test Evaluation

    Institute of Scientific and Technical Information of China (English)

    雷鸣

    2011-01-01

    Language test has been used as a scientific assessment tool in providing valuable information for teaching and learning. In fact,lots of online reading tests are not designed with validity. This paper analyzes those online reading tests from the aspects o

  17. Online consumer contracts

    NARCIS (Netherlands)

    Luzak, J.

    2014-01-01

    The new Consumer Rights Directive introduced some changes to the level of consumers’ protection online. However, just like with its predecessor, the Distance Selling Directive, the main focus of the protection that consumers have been granted online is to provide them with transparent and salient

  18. Consumers' Online Brand Endorsements

    NARCIS (Netherlands)

    Bernritter, S.F.; Verlegh, P.W.J.; Smit, E.G.; De Pelsmacker, P.

    2016-01-01

    Purpose and Approach This Chapter has three central goals: First, it aims to introduce the concept of consumers’ online brand endorsements, which we define as consumers’ intentional, public, and positive online affiliations with brands (e.g., liking a brand page on Facebook). Second, it provides an

  19. Online Readiness Rijscholen 2013

    NARCIS (Netherlands)

    Weltevreden, J.W.J.; Boels, D.H.H.

    2013-01-01

    In dit onderzoek is de online readiness van rijscholen in 2013 in kaart gebracht. In totaal hebben 115 rijscholen deelgenomen aan het onderzoek. Het onderzoek is uitgevoerd door het lectoraat Online Ondernemen samen met studenten van de minor Marketing Tomorrow van de Hogeschool van Amsterdam.

  20. Quality online personalisation

    NARCIS (Netherlands)

    T. Li (Ting); T. Unger (Till)

    2012-01-01

    textabstractWhen done right, personalisation online can be an effective way to enhance the buying or consuming experience, thus stimulating purchasing. However, it can also rely heavily on customers’ private details, a very sensitive and currently hot issue. So, how do online marketeers deal

  1. Framework for online teaching

    DEFF Research Database (Denmark)

    Strobel, Bjarne W.

    2014-01-01

    The following framework for online teaching is a guidance to inspire you on how to to use e-learning in your teaching. Maybe you want to make a whole online course (distance learning) or maybe you want to use e-learning as a part of a course (blended learning). If you want to go further or have...

  2. Online Advertising in Social Networks

    Science.gov (United States)

    Bagherjeiran, Abraham; Bhatt, Rushi P.; Parekh, Rajesh; Chaoji, Vineet

    Online social networks offer opportunities to analyze user behavior and social connectivity and leverage resulting insights for effective online advertising. This chapter focuses on the role of social network information in online display advertising.

  3. Online Sellers’ Website Quality Influencing Online Buyers’ Purchase Intention

    Science.gov (United States)

    Shea Lee, Tan; Ariff, Mohd Shoki Md; Zakuan, Norhayati; Sulaiman, Zuraidah; Zameri Mat Saman, Muhamad

    2016-05-01

    The increase adoption of Internet among young users in Malaysia provides high prospect for online seller. Young users aged between 18 and 25 years old are important to online sellers because they are actively involved in online purchasing and this group of online buyers is expected to dominate future online market. Therefore, examining online sellers’ website quality and online buyers’ purchase intention is crucial. Based on the Theory of planned behavior (TPB), a conceptual model of online sellers’ website quality and purchase intention of online buyers was developed. E-tailQ instrument was adapted in this study which composed of website design, reliability/fulfillment, security, privacy & trust, and customer service. Using online questionnaire and convenience sampling procedure, primary data were obtained from 240 online buyers aged between 18 to 25 years old. It was discovered that website design, website reliability/fulfillment, website security, privacy & trust, and website customer service positively and significantly influence intention of online buyers to continuously purchase via online channels. This study concludes that online sellers’ website quality is important in predicting online buyers’ purchase intention. Recommendation and implication of this study were discussed focusing on how online sellers should improve their website quality to stay competitive in online business.

  4. Enhanced epidemic intelligence using a web-based screening system during the 2010 FIFA World Cup in South Africa.

    Science.gov (United States)

    Mantero, J; Szegedi, E; Payne Hallstrom, L; Lenglet, A; Depoortere, E; Kaic, B; Blumberg, L; Linge, J P; Coulombier, D

    2014-05-08

    The 2010 FIFA World Cup took place in South Africa between 11 June and 11 July 2010. The European Centre for Disease Prevention and Control (ECDC), in collaboration with the hosting authorities, carried out enhanced epidemic intelligence activities from 7 June to 16 July 2010 for timely detection and monitoring of signals of public health events with a potential to pose a risk to participants and visitors. We adapted ECDC’s routine epidemic intelligence process to targeted event-based surveillance of official and unofficial online information sources. A set of three specifically adapted alerts in the web-based screening system MedISys were set up: potential public health events in South Africa, those occurring in the participating countries and those in the rest of the world. Results were shared with national and international public health partners through daily bulletins. According to pre-established ECDC criteria for the World Cup, 21 events of potential public health relevance were identified at local and international level. Although none of the events detected were evaluated as posing a serious risk for the World Cup, we consider that the investment in targeted event-based surveillance activities during the tournament was relevant as it facilitated real-time detection and assessment of potential threats. An additional benefit was early communication of relevant information to public health partners.

  5. Optimal vaccination and treatment of an epidemic network model

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lijuan [Department of Mathematics, Tongji University, Shanghai 200092 (China); College of Mathematics and Computer Science, Fuzhou University, Fuzhou, Fujian 350002 (China); Sun, Jitao, E-mail: sunjt@sh163.net [Department of Mathematics, Tongji University, Shanghai 200092 (China)

    2014-08-22

    In this Letter, we firstly propose an epidemic network model incorporating two controls which are vaccination and treatment. For the constant controls, by using Lyapunov function, global stability of the disease-free equilibrium and the endemic equilibrium of the model is investigated. For the non-constant controls, by using the optimal control strategy, we discuss an optimal strategy to minimize the total number of the infected and the cost associated with vaccination and treatment. Table 1 and Figs. 1–5 are presented to show the global stability and the efficiency of this optimal control. - Highlights: • Propose an optimally controlled SIRS epidemic model on heterogeneous networks. • Obtain criteria of global stability of the disease-free equilibrium and the endemic equilibrium. • Investigate existence of optimal control for the control problem. • The results be illustrated by some numerical simulations.

  6. Vaccination Strategies: a comparative study in an epidemic scenario

    Science.gov (United States)

    Prates, D. B.; Jardim, C. L. T. F.; Ferreira, L. A. F.; da Silva, J. M.; Kritz, M. V.

    2016-08-01

    Epidemics are an extremely important matter of study within the Mathematical Modeling area and can be widely found in the literature. Some epidemiological models use differential equations, which are very sensible to parameters, to represent and describe the diseases mathematically. For this work, a variation of the SIR model is discussed and applied to a certain epidemic scenario, wherein vaccination is introduced through two different strategies: constant vaccination and vaccination in pulses. Other epidemiological and population aspects are also considered, such as mortality/natality and infection rates. The analysis and results are performed through numerical solutions of the model and a special attention is given to the discussion generated by the paramenters variation.

  7. The emerging epidemic of hypertension in Asian children and adolescents.

    Science.gov (United States)

    Lee, Chong Guk

    2014-12-01

    Hypertension has become a serious global public health burden because of its high incidence and concomitant risk of cardiovascular disease. Many studies have verified that risk factors, such as hypertension and obesity which are responsible for cardiovascular disease, start in early childhood. In Asian countries, the prevalence of hypertension in the pediatric age group has become more prevalent than ever before with the increasing obesity epidemic. To tackle the epidemic of cardiovascular disease, a leading cause of death and disability of non-communicable diseases in Asian countries, population-based measures aiming at reducing harmful environmental factors to blood pressure and body weight must be applied to individuals in their early childhood, as early as the fetal stage. This review focused on the prevalence of pediatric hypertension in Asian countries and outlined several considerations for accurate blood pressure (BP) measurement and evaluation, along with an overview of pathophysiology of fetal programming and obesity related with childhood hypertension.

  8. On Resource Aware Algorithms in Epidemic Live Streaming

    CERN Document Server

    Mathieu, Fabien

    2009-01-01

    Epidemic-style diffusion schemes have been previously proposed for achieving peer-to-peer live streaming. Their performance trade-offs have been deeply analyzed for homogeneous systems, where all peers have the same upload capacity. However, epidemic schemes designed for heterogeneous systems have not been completely understood yet. In this report we focus on the peer selection process and propose a generic model that encompasses a large class of algorithms. The process is modeled as a combination of two functions, an aware one and an agnostic one. By means of simulations, we analyze the awareness-agnostism trade-offs on the peer selection process and the impact of the source distribution policy in non-homogeneous networks. We highlight that the early diffusion of a given chunk is crucial for its overall diffusion performance, and a fairness trade-off arises between the performance of heterogeneous peers, as a function of the level of awareness.

  9. Modeling the dynamical interaction between epidemics on overlay networks

    CERN Document Server

    Marceau, Vincent; Hébert-Dufresne, Laurent; Allard, Antoine; Dubé, Louis J

    2011-01-01

    Epidemics seldom occur as isolated phenomena. Typically, two or more viral agents spread within the same host population and may interact dynamically with each other. We present a general model where two viral agents interact via an immunity mechanism as they propagate simultaneously on two networks connecting the same set of nodes. Exploiting a correspondence between the propagation dynamics and a dynamical process performing progressive network generation, we develop an analytic approach that accurately captures the dynamical interaction between epidemics on overlay networks. The formalism allows for overlay networks with arbitrary joint degree distribution and overlap. To illustrate the versatility of our approach, we consider a hypothetical delayed intervention scenario in which an immunizing agent is disseminated in a host population to hinder the propagation of an undesirable agent (e.g. the spread of preventive information in the context of an emerging infectious disease).

  10. Malathion-induced epidemic hysteria in an elementary school.

    Science.gov (United States)

    Baker, P; Selvey, D

    1992-04-01

    More than 100 people, including firefighters, police officers, paramedics, nurses and physicians responded to reports that students at an elementary school had been exposed to an unknown and possibly toxic substance; 296 students were transported to eight hospital emergency departments. None were diagnosed as acutely ill. The substance was subsequently identified as approximately 22 ml of malathion, diluted in 15 L of water and applied by means of a hand-held sprayer approximately 100 m from the school. The odor apparently drifted to the school in 19 to 24 km/h winds. The episode was determined to be epidemic hysteria, possibly triggered by the malathion odor, but perpetuated by the stress of the emergency response. Hallmarks of epidemic hysteria are discussed, and recommendations for dealing with similar events are offered.

  11. Spatiotemporal Characteristic of Epidemic Spreading in Mobile Individuals

    Institute of Scientific and Technical Information of China (English)

    HE Min-Hua; ZHANG Duan-Ming; PAN Gui-Jun; YIN Yan-Ping; TAN Xin-Yu

    2008-01-01

    We numerical simulate the propagation behaviour and people distribution trait of epidemic spreading in mobile individuals by using cellular automaton method.The simulation results show that there exists a critical value of infected rate fluctuating amplitude,above which the epidemic can spread in whole population.Moreover,with the value of infected rate fluctuating amplitude increasing,the spatial distribution of infected population exhibits the spontaneous formation of irregular spiral waves and convergence phenomena,at the same time,the density of different populations will oscillate automatically with time.What is more,the traits of dynamic grow clearly and stably when the time and the value of infected rate fluctuating amplitude increasing.It is also found that the maximal proportion of infected individuals os independent of the value of fluctuating amplitude rate,but increases linearly with the population density.

  12. A qualitative view of the HIV epidemic in coastal Ecuador.

    Science.gov (United States)

    Beckman, Adam L; Wilson, Magdalena M; Prabhu, Vishaal; Soekoe, Nicola; Mata, Humberto; Grau, Lauretta E

    2016-01-01

    In 2013 approximately 37,000 people were living with HIV in Ecuador (prevalence 0.4%), representing a generalized epidemic where most new infections arise from sexual interactions in the general population. Studies that examine attitudes towards people living with HIV (PLWH), individual risk perception of acquiring HIV amongst Ecuadorians, and the ways in which levels of risk perception may affect risk behaviors are lacking. This qualitative study aimed to fill this gap in the literature by investigating these issues in the rural, coastal community of Manglaralto, Ecuador, which has among the highest incidence of HIV in Ecuador. We conducted interviews with 15 patients at Manglaralto Hospital. Analysis of interview transcripts revealed widespread negative attitudes towards PLWH, prevalent risk behaviors such as multiple sex partners and lack of condom use, and low individual risk-perception of contracting HIV. These findings underscore the need for increased efforts to prevent further growth of the HIV epidemic in Ecuador.

  13. [Increased epidemic incidence of hepatitis B in a district hospital].

    Science.gov (United States)

    Jakob, A; Mönch, E

    1978-01-15

    It is reported on an epidemic of hepatitis B of 29 patients in a district hospital. Due to diagnostic errors in importation and a more frequent appearance of diseases of hepatitis B in the surgical department and the 2nd medical department, in which above all diabetics are treated, took place. The average age of the patients was 55 years. In all patients the clinical course was to be regarded as severe. 4 of 29 patients died. In all patients the hepatitis B disease showed a pronounced jaundice with high transaminases, particularly the SGOT and LAP were clearly increased. Also the duration of the presence was longer than in hepatitis A as well as the transition into chronic hepatitis was more frequent. By diagnostic information of the physicians and the other medical staff as well as improved measures of desinfection the epidemic could be restricted.

  14. Cooperating epidemics of foodborne diseases with diverse trade networks

    CERN Document Server

    Min, Yong; Jin, Xiaogang; Chang, Jie

    2012-01-01

    The frequent outbreak of severe foodborne diseases warns of a potential threat that the global trade networks could spread fatal pathogens. The global trade network is a typical overlay network, which compounds multiple standalone trade networks representing the transmission of a single product and connecting the same set of countries and territories through their own set of trade interactions. Although the epidemic dynamic implications of overlay networks have been debated in recent studies, some general answers for the overlay of multiple and diverse standalone networks remain elusive, especially the relationship between the heterogeneity and diversity of a set of standalone networks and the behavior of the overlay network. In this paper, we establish a general analysis framework for multiple overlay networks based on diversity theory. The framework could reveal the critical epidemic mechanisms beyond overlay processes. Applying the framework to global trade networks, we found that, although the distributio...

  15. Stochastic SIR epidemics in a population with households and schools

    CERN Document Server

    Ouboter, Tanneke; Trapman, Pieter

    2015-01-01

    We study the spread of stochastic SIR (Susceptible $\\to$ Infectious $\\to$ Recovered) epidemics in two types of structured populations, both consisting of schools and households. In each of the types, every individual is part of one school and one household. In the independent partition model, the partitions of the population into schools and households are independent of each other. This model corresponds to the well-studied household-workplace model. In the hierarchical model which we introduce here, members of the same household are also members of the same school. We introduce computable branching process approximations for both types of populations and use these to compare the probabilities of a large outbreak. The branching process approximation in the hierarchical model is novel and of independent interest. We prove by a coupling argument that if all households and schools have the same size, an epidemic spreads easier (in the sense that the number of individuals infected is stochastically larger) in th...

  16. Impact of preventive responses to epidemics in rural regions.

    Science.gov (United States)

    Schumm, Phillip; Schumm, Walter; Scoglio, Caterina

    2013-01-01

    Various epidemics have arisen in rural locations through human-animal interaction, such as the H1N1 outbreak of 2009. Through collaboration with local government officials, we have surveyed a rural county and its communities and collected a dataset characterizing the rural population. From the respondents' answers, we build a social (face-to-face) contact network. With this network, we explore the potential spread of epidemics through a Susceptible-Latent-Infected-Recovered (SLIR) disease model. We simulate an exact model of a stochastic SLIR Poisson process with disease parameters representing a typical influenza-like illness. We test vaccine distribution strategies under limited resources. We examine global and location-based distribution strategies, as a way to reach critical individuals in the rural setting. We demonstrate that locations can be identified through contact metrics for use in vaccination strategies to control contagious diseases.

  17. Investigating the zoonotic origin of the West African Ebola epidemic

    Science.gov (United States)

    Marí Saéz, Almudena; Weiss, Sabrina; Nowak, Kathrin; Lapeyre, Vincent; Zimmermann, Fee; Düx, Ariane; Kühl, Hjalmar S; Kaba, Moussa; Regnaut, Sebastien; Merkel, Kevin; Sachse, Andreas; Thiesen, Ulla; Villányi, Lili; Boesch, Christophe; Dabrowski, Piotr W; Radonić, Aleksandar; Nitsche, Andreas; Leendertz, Siv Aina J; Petterson, Stefan; Becker, Stephan; Krähling, Verena; Couacy-Hymann, Emmanuel; Akoua-Koffi, Chantal; Weber, Natalie; Schaade, Lars; Fahr, Jakob; Borchert, Matthias; Gogarten, Jan F; Calvignac-Spencer, Sébastien; Leendertz, Fabian H

    2015-01-01

    The severe Ebola virus disease epidemic occurring in West Africa stems from a single zoonotic transmission event to a 2-year-old boy in Meliandou, Guinea. We investigated the zoonotic origins of the epidemic using wildlife surveys, interviews, and molecular analyses of bat and environmental samples. We found no evidence for a concurrent outbreak in larger wildlife. Exposure to fruit bats is common in the region, but the index case may have been infected by playing in a hollow tree housing a colony of insectivorous free-tailed bats (Mops condylurus). Bats in this family have previously been discussed as potential sources for Ebola virus outbreaks, and experimental data have shown that this species can survive experimental infection. These analyses expand the range of possible Ebola virus sources to include insectivorous bats and reiterate the importance of broader sampling efforts for understanding Ebola virus ecology. PMID:25550396

  18. Spatial and temporal dynamics of infected populations: the Mexican epidemic

    CERN Document Server

    Rodriguez-Meza, Mario A

    2012-01-01

    Recently the A/H1N1-2009 virus pandemic appeared in Mexico and in other nations. We present a study of this pandemic in the Mexican case using the SIR model to describe epidemics. This model is one of the simplest models but it has been a successful description of some epidemics of closed populations. We consider the data for the Mexican case and use the SIR model to make some predictions. Then, we generalize the SIR model in order to describe the spatial dynamics of the disease. We make a study of the spatial and temporal spread of the infected population with model parameters that are consistent with temporal SIR model parameters obtained by fitting to the Mexican case.

  19. The role of immunity and seasonality in cholera epidemics.

    Science.gov (United States)

    Sanches, Rosângela P; Ferreira, Claudia P; Kraenkel, Roberto A

    2011-12-01

    This paper presents a mathematical model for cholera epidemics which comprises seasonality, loss of host immunity, and control mechanisms acting to reduce cholera transmission. A collection of data related to cholera disease allows us to show that outbreaks in endemic areas are subject to a resonant behavior, since the intrinsic oscillation period of the disease (∼1 year) is synchronized with the annual contact rate variation. Moreover, we argue that the short period of the host immunity may be associated to secondary peaks of incidence observed in some regions (a bimodal pattern). Finally, we explore some possible mechanisms of cholera control, and analyze their efficiency. We conclude that, besides mass vaccination--which may be impracticable--improvements in sanitation system and food/personal hygiene are the most effective ways to prevent an epidemic.

  20. Investigating the zoonotic origin of the West African Ebola epidemic.

    Science.gov (United States)

    Marí Saéz, Almudena; Weiss, Sabrina; Nowak, Kathrin; Lapeyre, Vincent; Zimmermann, Fee; Düx, Ariane; Kühl, Hjalmar S; Kaba, Moussa; Regnaut, Sebastien; Merkel, Kevin; Sachse, Andreas; Thiesen, Ulla; Villányi, Lili; Boesch, Christophe; Dabrowski, Piotr W; Radonić, Aleksandar; Nitsche, Andreas; Leendertz, Siv Aina J; Petterson, Stefan; Becker, Stephan; Krähling, Verena; Couacy-Hymann, Emmanuel; Akoua-Koffi, Chantal; Weber, Natalie; Schaade, Lars; Fahr, Jakob; Borchert, Matthias; Gogarten, Jan F; Calvignac-Spencer, Sébastien; Leendertz, Fabian H

    2014-12-30

    The severe Ebola virus disease epidemic occurring in West Africa stems from a single zoonotic transmission event to a 2-year-old boy in Meliandou, Guinea. We investigated the zoonotic origins of the epidemic using wildlife surveys, interviews, and molecular analyses of bat and environmental samples. We found no evidence for a concurrent outbreak in larger wildlife. Exposure to fruit bats is common in the region, but the index case may have been infected by playing in a hollow tree housing a colony of insectivorous free-tailed bats (Mops condylurus). Bats in this family have previously been discussed as potential sources for Ebola virus outbreaks, and experimental data have shown that this species can survive experimental infection. These analyses expand the range of possible Ebola virus sources to include insectivorous bats and reiterate the importance of broader sampling efforts for understanding Ebola virus ecology.

  1. Chemostats and epidemics: competition for nutrients/hosts.

    Science.gov (United States)

    Smith, Hal L; Thieme, Horst R

    2013-01-01

    In a chemostat, several species compete for the same nutrient, while in an epidemic, several strains of the same pathogen may compete for the same susceptible hosts. As winner, chemostat models predict the species with the lowest break-even concentration, while epidemic models predict the strain with the largest basic reproduction number. We show that these predictions amount to the same if the per capita functional responses of consumer species to the nutrient concentration or of infective individuals to the density of susceptibles are proportional to each other but that they are different if the functional responses are nonproportional. In the second case, the correct prediction is given by the break-even concentrations. In the case of nonproportional functional responses, we add a class for which the prediction does not only rely on local stability and instability of one-species (strain) equilibria but on the global outcome of the competition. We also review some results for nonautonomous models.

  2. Epidemic spreading and immunization strategy in multiplex networks

    CERN Document Server

    Zuzek, Lucila G Alvarez; Braunstein, Lidia A

    2015-01-01

    A more connected world has brought major consequences such as facilitate the spread of diseases all over the world to quickly become epidemics, reason why researchers are concentrated in modeling the propagation of epidemics and outbreaks in Multilayer Networks. In this networks all nodes interact in different layers with different type of links. However, in many scenarios such as in the society, a Multiplex Network framework is not completely suitable since not all individuals participate in all layers. In this paper, we use a partially overlapped Multiplex Network where only a fraction of the individuals are shared by the layers. We develop a mitigation strategy for stopping a disease propagation, considering the Susceptible-Infected-Recover model, in a system consisted by two layers. We consider a random immunization in one of the layers and study the effect of the overlapping fraction in both, the propagation of the disease and the immunization strategy. Using branching theory, we study this scenario theo...

  3. Porcine Epidemic Diarrhea Virus Induces Autophagy to Benefit Its Replication

    Directory of Open Access Journals (Sweden)

    Xiaozhen Guo

    2017-03-01

    Full Text Available The new porcine epidemic diarrhea (PED has caused devastating economic losses to the swine industry worldwide. Despite extensive research on the relationship between autophagy and virus infection, the concrete role of autophagy in porcine epidemic diarrhea virus (PEDV infection has not been reported. In this study, autophagy was demonstrated to be triggered by the effective replication of PEDV through transmission electron microscopy, confocal microscopy, and Western blot analysis. Moreover, autophagy was confirmed to benefit PEDV replication by using autophagy regulators and RNA interference. Furthermore, autophagy might be associated with the expression of inflammatory cytokines and have a positive feedback loop with the NF-κB signaling pathway during PEDV infection. This work is the first attempt to explore the complex interplay between autophagy and PEDV infection. Our findings might accelerate our understanding of the pathogenesis of PEDV infection and provide new insights into the development of effective therapeutic strategies.

  4. Mathematics of epidemics on networks from exact to approximate models

    CERN Document Server

    Kiss, István Z; Simon, Péter L

    2017-01-01

    This textbook provides an exciting new addition to the area of network science featuring a stronger and more methodical link of models to their mathematical origin and explains how these relate to each other with special focus on epidemic spread on networks. The content of the book is at the interface of graph theory, stochastic processes and dynamical systems. The authors set out to make a significant contribution to closing the gap between model development and the supporting mathematics. This is done by: Summarising and presenting the state-of-the-art in modeling epidemics on networks with results and readily usable models signposted throughout the book; Presenting different mathematical approaches to formulate exact and solvable models; Identifying the concrete links between approximate models and their rigorous mathematical representation; Presenting a model hierarchy and clearly highlighting the links between model assumptions and model complexity; Providing a reference source for advanced undergraduate...

  5. [Human factors caused the third plague epidemic in Harbin].

    Science.gov (United States)

    Jin, Dong-Ying; Li, Zhi-Ping

    2011-03-01

    The third plague epidemic in Harbin broke out in 1946 and ended in 1954. Different from the first two plague epidemics (imported), the third prevalence was both imported and idiopathic infectious disease which was caused by human factors. Japanese troops set forbidden zones to build a biological weapon center, which destroyed the natural environment and offered a good growth condition for Citellus Undulatus. In 1945, on the eve of surrender, the Japanese blew up the Unit 731 germ factory located in a bungalow district, which caused diffusion of infected plague fleas. Mice of the district were infected and a man-made plague focus was created. During the prevalence of the third plague, prevention departments at all levels took a series of actions and with people's efforts, the plague was effectively controlled.

  6. [Scarlet fever epidemic during year 1929 in Chile].

    Science.gov (United States)

    Laval R, Enrique

    2009-04-01

    Scarlet fever is endemic in Chile, with relatively low morbidity and periodic exacerbations every 4 or 5 years, which can become epidemics. From 1921 to 1927, the number of patients hospitalized in the country fluctuated from 15 to 65 per year, until an epidemic involving nearly 3.000 patients started at the end of 1928 and continued during all 1929. 978 patients died, 537 (52.5%) were from Santiago. Public Health authorities confronted this emergency with prevention, prophylaxis, isolation and treatment measures and 558 beds were disposed for patient hospitalization. Vaccination trials were undertaken and specific treatment with antitoxins was used in patients with toxic clinical cases, having satisfactory results. Convalescent patients were controlled in order to stop the spread of the infection. After approximately 3 years, this disease returned to its regular endemicity.

  7. Bayesian online compressed sensing

    Science.gov (United States)

    Rossi, Paulo V.; Kabashima, Yoshiyuki; Inoue, Jun-ichi

    2016-08-01

    In this paper, we explore the possibilities and limitations of recovering sparse signals in an online fashion. Employing a mean field approximation to the Bayes recursion formula yields an online signal recovery algorithm that can be performed with a computational cost that is linearly proportional to the signal length per update. Analysis of the resulting algorithm indicates that the online algorithm asymptotically saturates the optimal performance limit achieved by the offline method in the presence of Gaussian measurement noise, while differences in the allowable computational costs may result in fundamental gaps of the achievable performance in the absence of noise.

  8. Unwanted online sexual solicitation and online sexual risk behavior

    NARCIS (Netherlands)

    Baumgartner, S.E.; Valkenburg, P.M.; Peter, J.; Yan, Z.

    2012-01-01

    In recent years, there have been growing concerns about online sexual solicitations and online sexual risk behaviors. Recent studies suggest that only a minority of adolescents is confronted with online sexual solicitations or engages in online sexual risk behavior. Whereas more girls encounter

  9. FluDetWeb: an interactive web-based system for the early detection of the onset of influenza epidemics

    Directory of Open Access Journals (Sweden)

    Miralles María

    2009-07-01

    Full Text Available Abstract Background The early identification of influenza outbreaks has became a priority in public health practice. A large variety of statistical algorithms for the automated monitoring of influenza surveillance have been proposed, but most of them require not only a lot of computational effort but also operation of sometimes not-so-friendly software. Results In this paper, we introduce FluDetWeb, an implementation of a prospective influenza surveillance methodology based on a client-server architecture with a thin (web-based client application design. Users can introduce and edit their own data consisting of a series of weekly influenza incidence rates. The system returns the probability of being in an epidemic phase (via e-mail if desired. When the probability is greater than 0.5, it also returns the probability of an increase in the incidence rate during the following week. The system also provides two complementary graphs. This system has been implemented using statistical free-software (ℝ and WinBUGS, a web server environment for Java code (Tomcat and a software module created by us (Rdp responsible for managing internal tasks; the software package MySQL has been used to construct the database management system. The implementation is available on-line from: http://www.geeitema.org/meviepi/fludetweb/. Conclusion The ease of use of FluDetWeb and its on-line availability can make it a valuable tool for public health practitioners who want to obtain information about the probability that their system is in an epidemic phase. Moreover, the architecture described can also be useful for developers of systems based on computationally intensive methods.

  10. Online plagiarism training falls short in biology classrooms.

    Science.gov (United States)

    Holt, Emily A; Fagerheim, Britt; Durham, Susan

    2014-01-01

    Online plagiarism tutorials are increasingly popular in higher education, as faculty and staff try to curb the plagiarism epidemic. Yet no research has validated the efficacy of such tools in minimizing plagiarism in the sciences. Our study compared three plagiarism-avoidance training regimens (i.e., no training, online tutorial, or homework assignment) and their impacts on students' ability to accurately discriminate plagiarism from text that is properly quoted, paraphrased, and attributed. Using pre- and postsurveys of 173 undergraduate students in three general ecology courses, we found that students given the homework assignment had far greater success in identifying plagiarism or the lack thereof compared with students given no training. In general, students trained with the homework assignment more successfully identified plagiarism than did students trained with the online tutorial. We also found that the summative assessment associated with the plagiarism-avoidance training formats (i.e., homework grade and online tutorial assessment score) did not correlate with student improvement on surveys through time.

  11. Age at puberty and the emerging obesity epidemic

    DEFF Research Database (Denmark)

    Aksglaede, Lise; Juul, Anders; Olsen, Lina W

    2009-01-01

    BACKGROUND: Recent studies have shown that puberty starts at younger ages than previously. It has been hypothesized that the increasing prevalence of childhood obesity is contributing to this trend. The purpose of this study was to analyze the association between prepubertal body mass index (BMI....... Irrespective of level of BMI at age seven, there was a downward trend in the age at attaining puberty in both boys and girls, which suggests that the obesity epidemic is not solely responsible for the trend....

  12. Preventing the Epidemic of Mental Ill Health: An Overview

    OpenAIRE

    Robson, Anthony,

    2013-01-01

    International audience; Diet, lifestyle and environment do not just affect a person's health, they also determine the health of their children and possibly the health of their grandchildren. Mental ill health is an epidemic worldwide because of the combined effect of the modern diet and a sedentary lifestyle. Primary prevention of mental ill health starts, crucially, with optimal adult nutrition before the inception of pregnancy, includes breastfeeding, and continues throughout the life of th...

  13. GLOBAL STABILITY OF AN SVIR EPIDEMIC MODEL WITH VACCINATION

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In this paper, an SIR epidemic model with vaccination for both the newborns and susceptibles is investigated, where it is assumed that the vaccinated individuals have the temporary immunity. The basic reproduction number determining the extinction or persistence of the infection is found. By constructing a Lyapunov function, it is proved that the disease free equilibrium is globally stable when the basic reproduction number is less than or equal to one, and that the endemic equilibrium is globally stable wh...

  14. SIVS EPIDEMIC MODELS WITH INFECTION AGE AND NONLINEAR VACCINATION RATE

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Vaccination is a very important strategy for the elimination of infectious diseaVaccination is a very important strategy for the elimination of infectious diseases. A SIVS epidemic model with infection age and nonlinear vaccination has been formulated in this paper. Using the theory of differential and integral equation, we show the local asymptotic stability of the infection-free equilibrium and the endemic equilibrium under some assumptions.

  15. Climate drives the meningitis epidemics onset in west Africa.

    Directory of Open Access Journals (Sweden)

    Benjamin Sultan

    2005-01-01

    Full Text Available BACKGROUND: Every year West African countries within the Sahelo-Sudanian band are afflicted with major meningococcal meningitis (MCM disease outbreaks, which affect up to 200,000 people, mainly young children, in one of the world's poorest regions. The timing of the epidemic year, which starts in February and ends in late May, and the spatial distribution of disease cases throughout the "Meningitis Belt" strongly indicate a close linkage between the life cycle of the causative agent of MCM and climate variability. However, mechanisms responsible for the observed patterns are still not clearly identified. METHODS AND FINDINGS: By comparing the information on cases and deaths of MCM from World Health Organization weekly reports with atmospheric datasets, we quantified the relationship between the seasonal occurrence of MCM in Mali, a West African country, and large-scale atmospheric circulation. Regional atmospheric indexes based on surface wind speed show a clear link between population dynamics of the disease and climate: the onset of epidemics and the winter maximum defined by the atmospheric index share the same mean week (sixth week of the year; standard deviation, 2 wk and are highly correlated. CONCLUSIONS: This study is the first that provides a clear, quantitative demonstration of the connections that exist between MCM epidemics and regional climate variability in Africa. Moreover, this statistically robust explanation of the MCM dynamics enables the development of an Early Warning Index for meningitis epidemic onset in West Africa. The development of such an index will undoubtedly help nationwide and international public health institutions and policy makers to better control MCM disease within the so-called westward-eastward pan-African Meningitis Belt.

  16. Preventing the Epidemic of Non-Communicable Diseases: An Overview

    OpenAIRE

    Robson, Anthony,

    2013-01-01

    International audience; Diet, lifestyle and environment do not just affect a person's health, they also determine the health of their children and possibly the health of their grandchildren. Non-communicable disease is a global epidemic because of the combined effect of the modern diet (including drug abuse) and a sedentary lifestyle. A low energy dense, drug-free diet rich in bioavailable nutrients-plus-exercise is most effective for preventing non-communicable disease throughout life. Nanoc...

  17. COURSE FEATURES EPIDEMIC PROCESS HIV INFECTION IN KHARKIV REGION

    Directory of Open Access Journals (Sweden)

    Nikolaeva LG

    2016-03-01

    Full Text Available Introduction. In the context of the transformation of the spheres of human living epidemic HIV-infection continues. According to the intensity of the epidemic process of HIV-infection, Ukraine takes one of the first places among the European countries. The epidemic process of the infection is concentrated mainly on the high-risk groups, and there is uneven prevalence. Besides in most cases this distribution can not be explained by the social and economic characteristics of certain territories. Kharkiv region belongs to the territory of Ukraine with the lowest prevalence level of HIV-infection. Though in terms of the social and economic crisis due to hostilities in the east of the country, which the region borders, the epidemic situation may significantly become worse. Work objective: to study the peculiarities of the course of the epidemic process of HIV-infection for the period from 1987 till 2015 in Kharkiv region that will improve the epidemiological surveillance of the infection and develop appropriate preventive measures in modern conditions. Material & methods. The studies were conducted in Kharkiv region, which is a big industrial and administrative center. The city of Kharkiv is located at the crossroads of drug trafficking from Asia and Russia. The reportings and analytics of the Kharkiv regional center for prevention and control of AIDS and the Ministry of Health of Ukraine for the period of 1987 – 2015 were used in the research. The analysis of incidence of HIV prevalence, structure of transmission routes and sex-age groups were carried out using descriptive and evaluative and analytical ways of epidemiological research method. Results & discussion. During 1987 – 2015 in Kharkiv region there were officially registered 7868 cases of HIV-infection what was equal to 4.0 % of the registered cases in Ukraine. Since 1996 a marked upward tendency of the incidence of HIV infection in Kharkiv region (growth rate – +7.0 %, and on the

  18. HIV and AIDS: where is the epidemic going?

    OpenAIRE

    Mertens, T.E.; Low-Beer, D.

    1996-01-01

    Routine surveillance of HIV (human immunodeficiency virus) infection and AIDS has been established over the past decade in many countries around the world. HIV estimates derived from empirical data are essential to the assessment of the HIV situation in different parts of the world and trends are used in tracking the development of regional epidemics, thereby keeping intervention activities focused on realities. As of the end of 1995, and following an extensive country-by-country review of HI...

  19. Current human immunodeficiency virus epidemic and its response in China

    Institute of Scientific and Technical Information of China (English)

    KANG Lai-Yi

    2012-01-01

    The first patient with acquired immunodeficiency syndrome (AIDS) was identified in 1985; since then, as of October 31, 2010, a total accumulative number of 370 000 patients with human immunodeficiency virus (HIV)/AIDS have been reported. The estimated number of patients living with HIV (PLHIV) in China was 740 000 in 2009. Although China is still a low-HIV prevalence region (rate of 0.057%), the epidemic has spread more widely from the high-risk groups to the general population. This paper covers five topics of importance, i.e., current trends of the HIV epidemic; HIV-1 subtype diversity; emergence of HIV drug resistance (HIVDR); the country's response to the disease; and future challenges and additional actions needed. This paper emphasizes sexual transmission as the predominant route of transmission and it being spread more frequently among men who have sex with men; the epidemic being concentrated over particular areas in China. We also discuss the fact that diverse HIV-1 subtypes have been found throughout the entire country and that recombinant subtypes became predominant. We also explore other topics such as the possibility of HIVDR, including primary and secondary resistance, with the use of free highly active anti-retroviral therapy (HAART); the integrated strategy of HIVDR surveillance and individual clinical HIVDR testing as a new attempt in China. For many years both policy-makers and professionals (including non-governmental organizations) have expressed strong commitment to prevention, control, and care of HIV/sexual transmission infection (STI), promoted the research and conducted different actions to slow the rising trend of the HIV epidemics. Although China is facing many challenges, its citizens need to be persistent on continuing the campaign of the State Council titled "Information of Strengthening Work on Prevention and Control of AIDS".

  20. Preventing the Epidemic of Non-Communicable Diseases: An Overview

    OpenAIRE

    2013-01-01

    International audience; Diet, lifestyle and environment do not just affect a person's health, they also determine the health of their children and possibly the health of their grandchildren. Non-communicable disease is a global epidemic because of the combined effect of the modern diet (including drug abuse) and a sedentary lifestyle. A low energy dense, drug-free diet rich in bioavailable nutrients-plus-exercise is most effective for preventing non-communicable disease throughout life. Nanoc...

  1. Where and When Human Viral Epidemics First Emerged

    OpenAIRE

    Rumyantsev, Sergey N.

    2012-01-01

    Aims: This article attempts to date the conditions, terms and places of the first emergence of the main human viral epidemics (HIV, influenza, measles, smallpox). Place and Duration of Study: Department of Evolutionary Immunology Andent, Inc., between May 2002 and July 2012. Methodology: The investigation was based on the integration and consequent sensing of relevant recent achievements of evolutionary branches of immunology, epidemiology and anthropology. The main focus was on the integrati...

  2. Epidemic spreading with time delay in complex networks

    CERN Document Server

    Xu, X J; Wang, X M; Wang, Y H

    2006-01-01

    We present a modified \\emph{susceptible-infected-susceptible} (SIS) model on complex networks, small-world and scale-free, to study epidemic spreading with the effect of time delay which is introduced to the infected phase. Considering the topology of the network, both uniform and degree-dependent delays are studied during the contagion process. We find that the existence of time delay will enhance both outbreaks and prevalence of infectious diseases in the network.

  3. [The Spanish flu epidemic: a challenge to Bahian medicine].

    Science.gov (United States)

    de Souza, Christiane Maria Cruz

    2008-01-01

    The article describes the moment when the medical and health authorities of Bahia state (Brazil) faced the challenge of explaining an illness that was spreading with unexpected virulency throughout the world, provoking much uncertainty and controversy among the global academic and scientific community concerning the diagnosis and etiology of the disease. It analyzes the Bahian medical establishment's stance within these discussions and the scientific knowledge used by medics to explain the epidemic and to recommend therapeutic and prophylactic measures.

  4. Supervised Group Discussion To Teach Investigation Of An Epidemic

    Directory of Open Access Journals (Sweden)

    Soudarssanane M.B

    1994-01-01

    Full Text Available The topic of investigation of an epidemic was taught to three successive batches of medical students using the data of an actual local outbreak of gastro â€" enteritis. The method used was supervised group discussion using audio â€" visual aids. The objectives achieved about the conduct of the sessions and the suggestions given by the students for improvement have also been highlighted.

  5. An Epidemic of Oroya Fever in the Peruvian Andes

    Science.gov (United States)

    1990-01-01

    3 patients. A serologic study revealed a high prevalence of anti- bodies to B. bacilliformis in the villagers. It is concluded that the villagers...epidemiologic studies as pip, guinea pigs, chickens, horses, cattle, and Di I ,have been recorded, and little is known regarding goats in connected courtyards...lipopolysaccharide T’he epidemic began during the rainy season. (Difco laboratories. Detroit. M11) and Brucella November to May. Many of the lPrsi cases re

  6. Epidemic of Mycoplasma pneumoniae infection in Denmark, 2010 and 2011

    DEFF Research Database (Denmark)

    Uldum, S A; Bangsborg, J M; Gahrn-Hansen, B;

    2012-01-01

    Denmark experienced two waves of Mycoplasma pneumoniae infection during autumn and early winter in 2010 and 2011, respectively. Both affected the whole country. The proportion of positive results was almost the same for both, indicating that the two waves were probably of equal size. High macroli...... consumption during the epidemics did not seem to affect levels of macrolide resistance in M. pneumoniae, which remain low in Demark (1% to 3%)....

  7. CE: Responding to the cholera epidemic in Haiti.

    Science.gov (United States)

    Fisher, Mary Lou Schulz; Wood, Tom; Plyler, Lance

    2014-05-01

    While Haiti was still recovering from the January 12, 2010, magnitude-7 earthquake, an outbreak of cholera spread throughout the nation, soon reaching epidemic proportions. Working through the faith-based nongovernmental organization Samaritan's Purse, an NP, an epidemiologist, and a physician joined the effort to prevent the spread of disease and treat those affected. Here they describe the prevention and intervention campaigns their organization initiated, how they prepared for each, and the essential elements of their operations.

  8. Spatio-temporal evolution of Beijing 2003 SARS epidemic

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Studying spatio-temporal evolution of epidemics can uncover important aspects of interaction among people, infectious diseases, and the environment, providing useful insights and modeling support to facilitate public health response and possibly prevention measures. This paper presents an empirical spatio-temporal analysis of epidemiological data concerning 2321 SARS-infected patients in Beijing in 2003. We mapped the SARS morbidity data with the spatial data resolution at the level of street and township. Two smoothing methods, Bayesian adjustment and spatial smoothing, were applied to identify the spatial risks and spatial transmission trends. Furthermore, we explored various spatial patterns and spatio-temporal evolution of Beijing 2003 SARS epidemic using spatial statistics such as Moran’s I and LISA. Part of this study is targeted at evaluating the effectiveness of public health control measures implemented during the SARS epidemic. The main findings are as follows. (1) The diffusion speed of SARS in the northwest-southeast direction is weaker than that in northeast-southwest direction. (2) SARS’s spread risk is positively spatially associated and the strength of this spatial association has experienced changes from weak to strong and then back to weak during the lifetime of the Beijing SARS epidemic. (3) Two spatial clusters of disease cases are identified: one in the city center and the other in the eastern suburban area. These two clusters followed different evolutionary paths but interacted with each other as well. (4) Although the government missed the opportunity to contain the early outbreak of SARS in March 2003, the response strategies implemented after the mid of April were effective. These response measures not only controlled the growth of the disease cases, but also mitigated the spatial diffusion.

  9. First Principles Modeling of Nonlinear Incidence Rates in Seasonal Epidemics

    OpenAIRE

    2011-01-01

    In this paper we used a general stochastic processes framework to derive from first principles the incidence rate function that characterizes epidemic models. We investigate a particular case, the Liu-Hethcote-van den Driessche's (LHD) incidence rate function, which results from modeling the number of successful transmission encounters as a pure birth process. This derivation also takes into account heterogeneity in the population with regard to the per individual transmission probability. We...

  10. Epidemics of enterovirus infection in Chungnam Korea, 2008 and 2009

    Directory of Open Access Journals (Sweden)

    Hwang SeoYeon

    2011-06-01

    Full Text Available Abstract Previously, we explored the epidemic pattern and molecular characterization of enteroviruses isolated in Chungnam, Korea from 2005 to 2006. The present study extended these observations to 2008 and 2009. In this study, enteroviruses showed similar seasonal prevalent pattern from summer to fall and age distribution to previous investigation. The most prevalent month was July: 42.9% in 2008 and 31.9% in 2009. The highest rate of enterovirus-positive samples occurred in children

  11. Computational Software for Fitting Seismic Data to Epidemic-Type Aftershock Sequence Models

    Science.gov (United States)

    Chu, A.

    2014-12-01

    Modern earthquake catalogs are often analyzed using spatial-temporal point process models such as the epidemic-type aftershock sequence (ETAS) models of Ogata (1998). My work introduces software to implement two of ETAS models described in Ogata (1998). To find the Maximum-Likelihood Estimates (MLEs), my software provides estimates of the homogeneous background rate parameter and the temporal and spatial parameters that govern triggering effects by applying the Expectation-Maximization (EM) algorithm introduced in Veen and Schoenberg (2008). Despite other computer programs exist for similar data modeling purpose, using EM-algorithm has the benefits of stability and robustness (Veen and Schoenberg, 2008). Spatial shapes that are very long and narrow cause difficulties in optimization convergence and problems with flat or multi-modal log-likelihood functions encounter similar issues. My program uses a robust method to preset a parameter to overcome the non-convergence computational issue. In addition to model fitting, the software is equipped with useful tools for examining modeling fitting results, for example, visualization of estimated conditional intensity, and estimation of expected number of triggered aftershocks. A simulation generator is also given with flexible spatial shapes that may be defined by the user. This open-source software has a very simple user interface. The user may execute it on a local computer, and the program also has potential to be hosted online. Java language is used for the software's core computing part and an optional interface to the statistical package R is provided.

  12. Epidemic Modelling by Ripple-Spreading Network and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Jian-Qin Liao

    2013-01-01

    Full Text Available Mathematical analysis and modelling is central to infectious disease epidemiology. This paper, inspired by the natural ripple-spreading phenomenon, proposes a novel ripple-spreading network model for the study of infectious disease transmission. The new epidemic model naturally has good potential for capturing many spatial and temporal features observed in the outbreak of plagues. In particular, using a stochastic ripple-spreading process simulates the effect of random contacts and movements of individuals on the probability of infection well, which is usually a challenging issue in epidemic modeling. Some ripple-spreading related parameters such as threshold and amplifying factor of nodes are ideal to describe the importance of individuals’ physical fitness and immunity. The new model is rich in parameters to incorporate many real factors such as public health service and policies, and it is highly flexible to modifications. A genetic algorithm is used to tune the parameters of the model by referring to historic data of an epidemic. The well-tuned model can then be used for analyzing and forecasting purposes. The effectiveness of the proposed method is illustrated by simulation results.

  13. Planning horizon affects prophylactic decision-making and epidemic dynamics.

    Science.gov (United States)

    Nardin, Luis G; Miller, Craig R; Ridenhour, Benjamin J; Krone, Stephen M; Joyce, Paul; Baumgaertner, Bert O

    2016-01-01

    The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon-the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals' payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.

  14. Effect of incubation period on epidemic spreading in complex networks

    Institute of Scientific and Technical Information of China (English)

    Huang Wei; Jiang Rui; Hu Mao-Bin; Wu Qing-Song

    2009-01-01

    We study the effect of incubation period on epidemic spreading in the Barabasi-Albert scale-free network and the Watts-Strogatz small world network by using a Suspectable-Incubated-Infected-Suspectable model.Our analytical investigations show that the epidemic threshold is independent of incubation period in both networks,which is verified by our large-scale simulation results.We also investigate the effect of incubation period on the epidemic dynamics in a supercritical regime.It is found that with the increase of incubation period Ω,a damped oscillation evolution of ρΤ(the ratio of persons in incubated state)appears and the time needed to reach a saturation value increases.Moreover,the steady value of ρI increases and approaches to an asymptotic constant with the value of Ω increasing.As a result,the infected ratio ρΤ decreases with the increase of Ω according to a power law.

  15. Identifying Potential Norovirus Epidemics in China via Internet Surveillance

    Science.gov (United States)

    Chen, Bin; Jiang, Tao; Cai, Gaofeng; Jiang, Zhenggang; Chen, Yongdi; Wang, Zhengting; Gu, Hua; Chai, Chengliang

    2017-01-01

    Background Norovirus is a common virus that causes acute gastroenteritis worldwide, but a monitoring system for norovirus is unavailable in China. Objective We aimed to identify norovirus epidemics through Internet surveillance and construct an appropriate model to predict potential norovirus infections. Methods The norovirus-related data of a selected outbreak in Jiaxing Municipality, Zhejiang Province of China, in 2014 were collected from immediate epidemiological investigation, and the Internet search volume, as indicated by the Baidu Index, was acquired from the Baidu search engine. All correlated search keywords in relation to norovirus were captured, screened, and composited to establish the composite Baidu Index at different time lags by Spearman rank correlation. The optimal model was chosen and possibly predicted maps in Zhejiang Province were presented by ArcGIS software. Results The combination of two vital keywords at a time lag of 1 day was ultimately identified as optimal (ρ=.924, Ptimes during the outbreak. In addition to Jiaxing Municipality, Hangzhou Municipality might have had some potential epidemics in the study time from the predicted model. Conclusions Although there are limitations with early warning and unavoidable biases, Internet surveillance may be still useful for the monitoring of norovirus epidemics when a monitoring system is unavailable. PMID:28790023

  16. Drivers of Rift Valley fever epidemics in Madagascar

    Science.gov (United States)

    Lancelot, Renaud; Béral, Marina; Rakotoharinome, Vincent Michel; Andriamandimby, Soa-Fy; Héraud, Jean-Michel; Coste, Caroline; Apolloni, Andrea; Squarzoni-Diaw, Cécile; de La Rocque, Stéphane; Wint, G. R. William; Cardinale, Eric

    2017-01-01

    Rift Valley fever (RVF) is a vector-borne viral disease widespread in Africa. The primary cycle involves mosquitoes and wild and domestic ruminant hosts. Humans are usually contaminated after contact with infected ruminants. As many environmental, agricultural, epidemiological, and anthropogenic factors are implicated in RVF spread, the multidisciplinary One Health approach was needed to identify the drivers of RVF epidemics in Madagascar. We examined the environmental patterns associated with these epidemics, comparing human and ruminant serological data with environmental and cattle-trade data. In contrast to East Africa, environmental drivers did not trigger the epidemics: They only modulated local Rift Valley fever virus (RVFV) transmission in ruminants. Instead, RVFV was introduced through ruminant trade and subsequent movement of cattle between trade hubs caused its long-distance spread within the country. Contact with cattle brought in from infected districts was associated with higher infection risk in slaughterhouse workers. The finding that anthropogenic rather than environmental factors are the main drivers of RVF infection in humans can be used to design better prevention and early detection in the case of RVF resurgence in the region. PMID:28096420

  17. Inference of causality in epidemics on temporal contact networks

    Science.gov (United States)

    Braunstein, Alfredo; Ingrosso, Alessandro

    2016-06-01

    Investigating into the past history of an epidemic outbreak is a paramount problem in epidemiology. Based on observations about the state of individuals, on the knowledge of the network of contacts and on a mathematical model for the epidemic process, the problem consists in describing some features of the posterior distribution of unobserved past events, such as the source, potential transmissions, and undetected positive cases. Several methods have been proposed for the study of these inference problems on discrete-time, synchronous epidemic models on networks, including naive Bayes, centrality measures, accelerated Monte-Carlo approaches and Belief Propagation. However, most traced real networks consist of short-time contacts on continuous time. A possibility that has been adopted is to discretize time line into identical intervals, a method that becomes more and more precise as the length of the intervals vanishes. Unfortunately, the computational time of the inference methods increase with the number of intervals, turning a sufficiently precise inference procedure often impractical. We show here an extension of the Belief Propagation method that is able to deal with a model of continuous-time events, without resorting to time discretization. We also investigate the effect of time discretization on the quality of the inference.

  18. Plague Epidemic s in Syria b etween XIII - XV. Centuries

    Directory of Open Access Journals (Sweden)

    Esra ATMACA

    2015-07-01

    Full Text Available Epidemic diseases that cause mass death has been one of the greatest fears of the society in the past century Usually due to poor living conditions, poverty, the inadequate treatment. Plague is one of them. Plague word is sometimes used synonymously with t he word tâûn, sometimes considered to be a greater sense of the Word plague. These outbreaks occured repeatedly in human society and many times occured between XIII - XV. centuries. Our research aims to examine the plague occured in Syria in the Mamluk state domination discussed period. One of the outbreaks have occured in the period between the years 1347 - 1351. Epidemic was looming at the same time with the European named the black death or large extinction. Many people have been killed in Syria as in other places where the epidemic has spread. Rumors about them are given in the source is situated in the form of the issuance of the number of people who died in one day and sometimes the total number of deaths took place at a given date range. In this study, we aimed to determine which is more severe than the others in the outbreak, to assess the rumor about the number of deaths from this cause, to reveal the difficulties of the funeral of the dead, to uncover practices that people do to get rid of this disease.

  19. [Epidemics and diseases during the Independence period in Mexico].

    Science.gov (United States)

    Viesca-Treviño, Carlos

    2010-01-01

    The epidemics and endemic diseases in Mexico were not a problem before the Independence period. Hunger was less than in the past. The 1806 Influenza epidemics had been forgotten. Measles was considered a benign illness. In 1810, there was an increase in the number of cases of black vomit in Veracruz. Sixty percent of 541 hospitalized patients die of the disease. In 1812, an outbreak of yellow fever spread from Veracruz to Jalapa accompanying the movement of troops and killing over 300 soldiers of the Castilla's Battalion. The appearance of petechial fever, maybe typhus marketed in 1813 the onset of the most important epidemics. The preceding was the indirect effect of war: diseases of prisons and military quarters which became overwhelming in times where the movements of troops and of important groups of populations along with crowing, loss homes, hunger and bad hygiene habits. There was also Influenza or "pestilent cold." Measures of detection and quarantine were taken. "Naranjate" mixed with tartaric cremor was used against fever. Fumigation with nitric acid and burners, where they incinerated gun powder were among the health protection policies. It is noteworthy the advance and relief provided by the introduction of smallpox vaccine, the only preventive mean useful against smallpox which was a breakthrough in public health.

  20. Monitoring linked epidemics: the case of tuberculosis and HIV.

    Directory of Open Access Journals (Sweden)

    María S Sánchez

    Full Text Available BACKGROUND: The tight epidemiological coupling between HIV and its associated opportunistic infections leads to challenges and opportunities for disease surveillance. METHODOLOGY/PRINCIPAL FINDINGS: We review efforts of WHO and collaborating agencies to track and fight the TB/HIV co-epidemic, and discuss modeling--via mathematical, statistical, and computational approaches--as a means to identify disease indicators designed to integrate data from linked diseases in order to characterize how co-epidemics change in time and space. We present R(TB/HIV, an index comparing changes in TB incidence relative to HIV prevalence, and use it to identify those sub-Saharan African countries with outlier TB/HIV dynamics. R(TB/HIV can also be used to predict epidemiological trends, investigate the coherency of reported trends, and cross-check the anticipated impact of public health interventions. Identifying the cause(s responsible for anomalous R(TB/HIV values can reveal information crucial to the management of public health. CONCLUSIONS/SIGNIFICANCE: We frame our suggestions for integrating and analyzing co-epidemic data within the context of global disease monitoring. Used routinely, joint disease indicators such as R(TB/HIV could greatly enhance the monitoring and evaluation of public health programs.

  1. Respondent-driven sampling and an unusual epidemic

    CERN Document Server

    Malmros, Jens; Britton, Tom

    2014-01-01

    Respondent-driven sampling (RDS) is frequently used when sampling hard-to-reach and/or stigmatized communities. RDS utilizes a peer-driven recruitment mechanism where sampled individuals pass on participation coupons to at most $c$ of their acquaintances in the community ($c=3$ being a common choice), who then in turn pass on to their acquaintances if they choose to participate, and so on. This process of distributing coupons is shown to behave like a new Reed-Frost type network epidemic model, in which becoming infected corresponds to receiving a coupon. The difference from existing network epidemic models is that an infected individual can not infect (i.e.\\ sample) all of its contacts, but only at most $c$ of them. We calculate $R_0$, the probability of a major "outbreak", and the relative size of a major outbreak in the limit of infinite population size and evaluate their adequacy in finite populations. We study the effect of varying $c$ and compare RDS to the corresponding usual epidemic models, i.e.\\ the...

  2. Simulated identification of epidemic threshold in finite-size networks

    CERN Document Server

    Shu, Panpan; Tang, Ming

    2014-01-01

    Epidemic threshold is one of the most important features of the epidemic dynamics. Based on a lot of numerical simulations of classic Susceptible-Infected-Recovered (SIR) and Susceptible-Infected-Susceptible (SIS) models on various types of networks, we study the simulated thresholds for finite-size networks. We confirm that the susceptibility measure goes awry for the SIR model due to the bimodal distribution of outbreak sizes near the critical point, while the simulated thresholds of the SIS and SIR models can be accurately determined by analyzing the peak of the epidemic variability. We further verify the accuracy of theoretical predictions of the heterogeneous mean-field theory (HMF) and of the quenched mean-field theory (QMF), by comparing them with the simulated threshold of the SIR model obtained from the variability measure. The results show that the HMF prediction agrees very well with the simulated threshold, except the case that the networks are disassortive, in which the QMF prediction is more clo...

  3. Immunization strategy for epidemic spreading on multilayer networks

    CERN Document Server

    Buono, C

    2014-01-01

    In many real-world complex systems, individuals have many kind of interactions among them, suggesting that it is necessary to consider a layered structure framework to model systems such as social interactions. This structure can be captured by multilayer networks and can have major effects on the spreading of process that occurs over them, such as epidemics. In this Letter we study a targeted immunization strategy for epidemic spreading over a multilayer network. We apply the strategy in one of the layers and study its effect in all layers of the network disregarding degree-degree correlation among layers. We found that the targeted strategy is not as efficient as in isolated networks, due to the fact that in order to stop the spreading of the disease it is necessary to immunize more than the 80 % of the individuals. However, the size of the epidemic is drastically reduced in the layer where the immunization strategy is applied compared to the case with no mitigation strategy. Thus, the immunization strategy...

  4. A study of the 2006 Chikungunya epidemic outbreak in Mauritius

    Directory of Open Access Journals (Sweden)

    Mr. V. Pydiah

    2008-01-01

    Full Text Available Chikungunya epidemic outbreaks have affected more than 1 million people in 2005-2006 in many Indian Ocean islands and in India. Mauritius experienced a major outbreak in February/March 2006 following a minor outbreak in April/May 2005. No cases have been registered on the island since August 2006. The objectives of this study were to understand the timing and development of the 2006-outbreak in Mauritius, to investigate the possibility of a future outbreak, and to propose measures to prevent the recurrence of an epidemic in Mauritius. Mauritius rainfall, temperature and humidity data were analyzed. A door-to-door household census-type survey was carried out in a study locality on the island. A compartmental human-mosquito interaction model was integrated to understand outbreak evolutions in the surveyed locality and in a theoretical locality. It was observed that the onset of the 2006-outbreak in February followed an abnormally high rainfall in the third week of January 2006. 51% of the surveyed population was found to be suspected Chikungunya cases. Computer simulations indicated that a small number of infected humans and mosquitoes existed in the surveyed locality at the outbreak onset. From simulations in the theoretical locality, it was deduced that the level of infectivity in some localities may be below a herd immunity threshold and that the additional percentage of infected inhabitants in a follow-up epidemic would be significantly reduced with the case-reactive control of infected adult mosquitoes.

  5. Local variations in spatial synchrony of influenza epidemics.

    Directory of Open Access Journals (Sweden)

    James H Stark

    Full Text Available BACKGROUND: Understanding the mechanism of influenza spread across multiple geographic scales is not complete. While the mechanism of dissemination across regions and states of the United States has been described, understanding the determinants of dissemination between counties has not been elucidated. The paucity of high resolution spatial-temporal influenza incidence data to evaluate disease structure is often not available. METHODOLOGY AND FINDINGS: We report on the underlying relationship between the spread of influenza and human movement between counties of one state. Significant synchrony in the timing of epidemics exists across the entire state and decay with distance (regional correlation=62%. Synchrony as a function of population size display evidence of hierarchical spread with more synchronized epidemics occurring among the most populated counties. A gravity model describing movement between two populations is a stronger predictor of influenza spread than adult movement to and from workplaces suggesting that non-routine and leisure travel drive local epidemics. CONCLUSIONS: These findings highlight the complex nature of influenza spread across multiple geographic scales.

  6. The evolutionary rate dynamically tracks changes in HIV-1 epidemics

    Energy Technology Data Exchange (ETDEWEB)

    Maljkovic-berry, Irina [Los Alamos National Laboratory; Athreya, Gayathri [Los Alamos National Laboratory; Daniels, Marcus [Los Alamos National Laboratory; Bruno, William [Los Alamos National Laboratory; Korber, Bette [Los Alamos National Laboratory; Kuiken, Carla [Los Alamos National Laboratory; Ribeiro, Ruy M [Los Alamos National Laboratory

    2009-01-01

    Large-sequence datasets provide an opportunity to investigate the dynamics of pathogen epidemics. Thus, a fast method to estimate the evolutionary rate from large and numerous phylogenetic trees becomes necessary. Based on minimizing tip height variances, we optimize the root in a given phylogenetic tree to estimate the most homogenous evolutionary rate between samples from at least two different time points. Simulations showed that the method had no bias in the estimation of evolutionary rates and that it was robust to tree rooting and topological errors. We show that the evolutionary rates of HIV-1 subtype B and C epidemics have changed over time, with the rate of evolution inversely correlated to the rate of virus spread. For subtype B, the evolutionary rate slowed down and tracked the start of the HAART era in 1996. Subtype C in Ethiopia showed an increase in the evolutionary rate when the prevalence increase markedly slowed down in 1995. Thus, we show that the evolutionary rate of HIV-1 on the population level dynamically tracks epidemic events.

  7. The Online Bookstore

    Directory of Open Access Journals (Sweden)

    Zhai Yunkai

    2017-01-01

    Full Text Available Nowadays, the network plays an import role in people’s life. In the process of the improvement of the people’s living standard, people’s demands of the life’s quality and efficiency is more higher, the traditional bookstore’s inconvenience gradually emerge, and the online bookstore has gradually be used in public. The online bookstore is a revolution of book industry. The traditional bookstores’ operation time, address and space is limited, so the types of books and books to find received a degree of restriction. But the online bookstore broke the management mode of traditional bookstore, as long as you have a computer, you can buy the book anywhere, saving time and effort, shortening the time of book selection link effectively. The online bookstore system based on the principle of provides convenience and service to people.

  8. Online learning for all.

    Science.gov (United States)

    Doherty, Simon

    2015-05-30

    Last year, Simon Doherty, president of the North of Ireland Veterinary Association and the BVA's NI Branch, completed a number of MOOCs (massive open online courses) having read about them in Vet Record Careers; here, he describes his experiences.

  9. Varieties of online gatekeeping

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    News media organizations like newspapers and broadcasters have long functioned as gatekeepers between news and audiences, but with the rise of digital media, the search engines and social networking sites that are central to how most people navigate online increasingly complement news media......) and where non-journalistic actors too serve as gates between news and audiences. In this paper, I adopt such a broader approach and outline three varieties of online gatekeeping that each integrate different technologies in the gatekeeping process, but do so in different ways and for different purposes...... media websites remain amongst the most important gateways to news online. But they are increasingly supplemented by other, second-order online gatekeepers like search engines and social networking sites that, while rarely producing original content defined as “news”, increasingly serve as alternative...

  10. Conserveermiddelen on-line

    NARCIS (Netherlands)

    Top, J.L.; Ketelaars, N.J.J.P.; Hulzebos, J.L.

    2004-01-01

    Antimicrobials Online is een Engelstalige database die wetenschappelijke informatie over natuurlijke conserveermiddelen via internet beschikbaar stelt aan de levensmiddelenindustrie. Het project is uitgevoerd door Wageningen UR-Agrotechnology & Food Innovations. Er volgt uitbreiding met traditio

  11. Doing recovery online.

    Science.gov (United States)

    Mudry, Tanya E; Strong, Tom

    2013-03-01

    Although problem gambling is becoming more prevalent, research shows that many problem gamblers do not seek help. Online social support forums have become an increasingly popular option for receiving support for problem gambling. Few researchers have explored how participants within these forums interact, or what is supportive about participation in online communities. Melding netnography (ethnographic approaches online), discourse analysis, and ethnomethodology, we analyzed the discursive interactions of self-identified problem gamblers on an online forum. We report on the characteristics of this unique setting, the common discourses that members used, and how they discursively accomplished various interactional tasks, including constructing identities, and negotiating membership, legitimacy, and support. We conclude with recommendations for practitioners and researchers interested in better understanding people trying to overcome problem gambling and other behavioral concerns.

  12. Exploring Online Purchasing.

    Science.gov (United States)

    Fickes, Michael

    2001-01-01

    Examines the setup of American University's electronic procurement system and explains how it works and the benefits it brings to the school. Cautionary advice on setting up an online purchasing system is also offered. (GR)

  13. Conserveermiddelen on-line

    NARCIS (Netherlands)

    Top, J.L.; Ketelaars, N.J.J.P.; Hulzebos, J.L.

    2004-01-01

    Antimicrobials Online is een Engelstalige database die wetenschappelijke informatie over natuurlijke conserveermiddelen via internet beschikbaar stelt aan de levensmiddelenindustrie. Het project is uitgevoerd door Wageningen UR-Agrotechnology & Food Innovations. Er volgt uitbreiding met

  14. TU Delft en online media

    NARCIS (Netherlands)

    Speekenbrink, R.J.H.

    2013-01-01

    Dit boek behandelt een visie op online media bij Nederlandse universiteiten. Daarbij beperk ik me tot die aspecten waarin online communicatie en/of online marketing een rol speelt. Dit boek behandelt niet de onderwijsgerelateerde aspecten van online media. Elektronische leeromgevingen, sociale medi

  15. TU Delft en online media

    NARCIS (Netherlands)

    Speekenbrink, R.J.H.

    2013-01-01

    Dit boek behandelt een visie op online media bij Nederlandse universiteiten. Daarbij beperk ik me tot die aspecten waarin online communicatie en/of online marketing een rol speelt. Dit boek behandelt niet de onderwijsgerelateerde aspecten van online media. Elektronische leeromgevingen, sociale medi

  16. TU Delft en online media

    NARCIS (Netherlands)

    Speekenbrink, R.J.H.

    2013-01-01

    Dit boek behandelt een visie op online media bij Nederlandse universiteiten. Daarbij beperk ik me tot die aspecten waarin online communicatie en/of online marketing een rol speelt. Dit boek behandelt niet de onderwijsgerelateerde aspecten van online media. Elektronische leeromgevingen, sociale

  17. Using online tone generators

    Science.gov (United States)

    2017-04-01

    Online tone generators are free, user friendly, and can make for engaging and meaningful study of many topics in the areas of interference, waves, and the physics of music. By using a website such as OnlineToneGenerator.com, and through opening multiple windows simultaneously, students can immediately perform several experiments. In this article, I highlight five lesson ideas that come naturally from these types of websites.

  18. Building online worlds

    DEFF Research Database (Denmark)

    Toft-Nielsen, Claus

    2013-01-01

    The fantasy genre has proven to be extremely durable in creating blockbuster successes across multiple media platforms, such as books, films, tabletop and especially online computer games. Currently 85 % of all Massively Multiplayer Online Role-Playing Games (MMORPGs) are situated in fantasy univ....... This paper will examine the genre function of fantasy drawing on both literary theory and computer game theory, through both textual analysis and reception analysis....

  19. Online Digital Trading

    Directory of Open Access Journals (Sweden)

    Felician Alecu

    2013-09-01

    Full Text Available This paper summarizes the main options a digital content creator has in order to obtain money by online trading of digital works. There are multiple ways to get paid for the digital products, like licensing, for example, however this article tries to present the most successful business models targeting the online market. The exclusive rights stated by the copyright laws are helping the authors to maximize to potential advantages coming from their digital creations.

  20. Suicidality, psychopathology, and the internet: Online time vs. online behaviors.

    Science.gov (United States)

    Harris, Keith M; Starcevic, Vladan; Ma, Jing; Zhang, Wei; Aboujaoude, Elias

    2017-09-01

    This study investigated whether several psychopathology variables, including suicidality, could predict the time people spend using the internet (hours online). Next, we examined a specific at-risk population (suicidal individuals) by their online behaviors, comparing suicidal individuals who went online for suicide-related purposes with suicidal individuals who did not go online for suicide-related purposes. An anonymous online sample of 713 (aged 18-71) reported hours online, psychiatric histories, and completed several standardized scales. After accounting for age and education, hierarchical regression modeling showed that the assessed psychopathology variables, including suicidality, did not explain significant variance in hours online. Hours online were better predicted by younger age, greater willingness to develop online relationships, higher perceived social support, higher curiosity, and lower extraversion. Suicidal participants, who did or did not go online for suicide-related purposes, did not differ on hours online. Multiple regression modeling showed that those who went online for suicide-related purposes were likely to be younger, more suicidal, and more willing to seek help from online mental health professionals. These findings revealed that hours online are not a valid indicator of psychopathology. However, studying online behaviors of specific at-risk groups could be informative and useful, including for suicide prevention efforts. Copyright © 2017. Published by Elsevier B.V.