A simple model for behaviour change in epidemics

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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.

Mitigating Infectious Disease Outbreaks

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Davey, Victoria

The emergence of new, transmissible infections poses a significant threat to human populations. As the 2009 novel influenza A/H1N1 pandemic and the 2014-2015 Ebola epidemic demonstrate, we have observed the effects of rapid spread of illness in non-immune populations and experienced disturbing uncertainty about future potential for human suffering and societal disruption. Clinical and epidemiologic characteristics of a newly emerged infectious organism are usually gathered in retrospect as the outbreak evolves and affects populations. Knowledge of potential effects of outbreaks and epidemics and most importantly, mitigation at community, regional, national and global levels is needed to inform policy that will prepare and protect people. Study of possible outcomes of evolving epidemics and application of mitigation strategies is not possible in observational or experimental research designs, but computational modeling allows conduct of `virtual' experiments. Results of well-designed computer simulations can aid in the selection and implementation of strategies that limit illness and death, and maintain systems of healthcare and other critical resources that are vital to public protection. Mitigating Infectious Disease Outbreaks.

Epidemic spreading on dual-structure networks with mobile agents

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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.

Household demographic determinants of Ebola epidemic risk.

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Adams, Ben

2016-03-07

A salient characteristic of Ebola, and some other infectious diseases such as Tuberculosis, is intense transmission among small groups of cohabitants and relatively limited indiscriminate transmission in the wider population. Here we consider a mathematical model for an Ebola epidemic in a population structured into households of equal size. We show that household size, a fundamental demographic unit, is a critical factor that determines the vulnerability of a community to epidemics, and the effort required to control them. Our analysis is based on the household reproduction number, but we also consider the basic reproduction number, intrinsic growth rate and final epidemic size. We show that, when other epidemiological parameters are kept the same, all of these quantifications of epidemic growth and size are increased by larger households and more intense within-household transmission. We go on to model epidemic control by case detection and isolation followed by household quarantine. We show that, if household quarantine is ineffective, the critical probability with which cases must be detected to halt an epidemic increases significantly with each increment in household size and may be a very challenging target for communities composed of large households. Effective quarantine may, however, mitigate the detrimental impact of large household sizes. We conclude that communities composed of large households are fundamentally more vulnerable to epidemics of infectious diseases primarily transmitted by close contact, and any assessment of control strategies for these epidemics should take into account the demographic structure of the population. Copyright © 2015 Elsevier Ltd. All rights reserved.

Epidemic spreading in time-varying community networks.

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Ren, Guangming; Wang, Xingyuan

2014-06-01

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 qc. The epidemic will survive when q > qc and die when q epidemic spreading in complex networks with community structure.

Untangling the Interplay between Epidemic Spread and Transmission Network Dynamics.

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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.

The Incidence and gastrointestinal infectious risk of functional gastrointestinal disorders in a healthy US adult population.

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Porter, Chad K; Gormley, Robert; Tribble, David R; Cash, Brooks D; Riddle, Mark S

2011-01-01

Functional gastrointestinal disorders (FGDs) are recognized sequelae of infectious gastroenteritis (IGE). Within the active duty military population, a group with known high IGE rates, the population-based incidence, risk factors, and attributable burden of care referable to FGD after IGE are poorly defined. Using electronic medical encounter data (1999-2007) on active duty US military, a matched, case-control study describing the epidemiology and risk determinants of FGD (irritable bowel syndrome (IBS), functional constipation (FC), functional diarrhea (FD), dyspepsia (D)) was conducted. Incidence rates and duration of FGD-related medical care were estimated, and conditional logistic regression was utilized to evaluate FGD risk after IGE. A total of 31,866 cases of FGD identified were distributed as follows: FC 55% (n=17,538), D 21.2% (n=6,750), FD 2.1% (n=674), IBS 28.5% (n=9,091). Previous IGE episodes were distributed as follows: specific bacterial pathogen (n=65, 1.2%), bacterial, with no pathogen specified (n=2155, 38.9%), protozoal (n=38, 0.7%), viral (n=3431, 61.9%). A significant association between IGE and all FGD (odds ratio (OR) 2.64; Phigh risk for IGE. When considering effective countermeasures and mitigation strategies, attention directed toward prevention as well as the acute and chronic sequelae of these infections is needed.

New technologies in predicting, preventing and controlling emerging infectious diseases.

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Christaki, Eirini

2015-01-01

Surveillance of emerging infectious diseases is vital for the early identification of public health threats. Emergence of novel infections is linked to human factors such as population density, travel and trade and ecological factors like climate change and agricultural practices. A wealth of new technologies is becoming increasingly available for the rapid molecular identification of pathogens but also for the more accurate monitoring of infectious disease activity. Web-based surveillance tools and epidemic intelligence methods, used by all major public health institutions, are intended to facilitate risk assessment and timely outbreak detection. In this review, we present new methods for regional and global infectious disease surveillance and advances in epidemic modeling aimed to predict and prevent future infectious diseases threats.

Hybrid epidemic spreading - from Internet worms to HIV infection

OpenAIRE

Zhang, C.

2015-01-01

Epidemic phenomena are ubiquitous, ranging from infectious diseases, computer viruses, to information dissemination. Epidemics have traditionally been studied as a single spreading process, either in a fully mixed population or on a network. Many epidemics, however, are hybrid, employing more than one spreading mechanism. For example, the Internet worm Conficker spreads locally targeting neighbouring computers in local networks as well as globally by randomly probing any computer on the Inter...

Epidemic spreading in time-varying community networks

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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.

Epidemic spreading in time-varying community networks

International Nuclear Information System (INIS)

Ren, Guangming; Wang, Xingyuan

2014-01-01

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 c . The epidemic will survive when q > q c and die when q  c . These results can help understanding the impacts of human travel on the epidemic spreading in complex networks with community structure

A social contagious model of the obesity epidemic

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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.

Dynamics of epidemics outbreaks in heterogeneous populations

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Brockmann, Dirk; Morales-Gallardo, Alejandro; Geisel, Theo

2007-03-01

The dynamics of epidemic outbreaks have been investigated in recent years within two alternative theoretical paradigms. The key parameter of mean field type of models such as the SIR model is the basic reproduction number R0, the average number of secondary infections caused by one infected individual. Recently, scale free network models have received much attention as they account for the high variability in the number of social contacts involved. These models predict an infinite basic reproduction number in some cases. We investigate the impact of heterogeneities of contact rates in a generic model for epidemic outbreaks. We present a system in which both the time periods of being infectious and the time periods between transmissions are Poissonian processes. The heterogeneities are introduced by means of strongly variable contact rates. In contrast to scale free network models we observe a finite basic reproduction number and, counterintuitively a smaller overall epidemic outbreak as compared to the homogeneous system. Our study thus reveals that heterogeneities in contact rates do not necessarily facilitate the spread to infectious disease but may well attenuate it.

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2016.

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Bossé, D; Ng, T; Ahmad, C; Alfakeeh, A; Alruzug, I; Biagi, J; Brierley, J; Chaudhury, P; Cleary, S; Colwell, B; Cripps, C; Dawson, L A; Dorreen, M; Ferland, E; Galiatsatos, P; Girard, S; Gray, S; Halwani, F; Kopek, N; Mahmud, A; Martel, G; Robillard, L; Samson, B; Seal, M; Siddiqui, J; Sideris, L; Snow, S; Thirwell, M; Vickers, M; Goodwin, R; Goel, R; Hsu, T; Tsvetkova, E; Ward, B; Asmis, T

2016-12-01

The annual Eastern Canadian Gastrointestinal Cancer Consensus Conference 2016 was held in Montreal, Quebec, 5-7 February. Experts in radiation oncology, medical oncology, surgical oncology, and infectious diseases involved in the management of patients with gastrointestinal malignancies participated in presentations and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses multiple topics: ■ Follow-up and survivorship of patients with resected colorectal cancer■ Indications for liver metastasectomy■ Treatment of oligometastases by stereotactic body radiation therapy■ Treatment of borderline resectable and unresectable pancreatic cancer■ Transarterial chemoembolization in hepatocellular carcinoma■ Infectious complications of antineoplastic agents.

The Forgotten Plague: Psychiatric Manifestations of Ebola, Zika, and Emerging Infectious Diseases.

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Tucci, Veronica; Moukaddam, Nidal; Meadows, Jonathan; Shah, Suhal; Galwankar, Sagar C; Kapur, G Bobby

2017-01-01

The media and public health generally focus on the biological and physical ramifications of epidemics. Mental health issues that coincide with emerging diseases and epidemics are rarely examined and sometimes, even eschewed due to cultural considerations. Psychiatric manifestations of various infectious diseases, especially with a focus on Ebola Virus disease (EVD) and Zika Virus, are discussed in this commentary to illustrate the continued need of care after the resolution of the actual illness. Various infectious diseases have associations with mental illness, such as an increased risk of obsessive-compulsive disorders and Tourette syndrome in children with Group B streptococcal infection. Current EVD literature does not demonstrate a strong association of mental illness symptoms or diseases but there is a necessity of care that extends beyond the illness. Patients and their families experience depression, anxiety, trauma, suicidal ideation, panic and other manifestations. Zika virus has been associated neuronal injury, genetic alteration that affects fetal development and detrimental maternal mental health symptoms are being documented. While funding calls from the international community are present, there are no specific epidemiological data or fiscal estimates solely for mental health during or after infectious diseases epidemics or disasters that support health care providers and strengthen policies and procedures for responding to such situations. Therefore, those on the frontlines of epidemics including emergency physicians, primary care providers and infectious disease specialists should serve communicate this need and advocate for sustained and increased funding for mental health programs to heighten public awareness regarding acute psychiatric events during infectious diseases outbreaks and offer treatment and support when necessary.

[Epidemiology of imported infectious diseases in China, 2013-2016].

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Wang, Y L; Wang, X; Ren, R Q; Zhou, L; Tu, W W; Ni, D X; Li, Q; Feng, Z J; Zhang, Y P

2017-11-10

Objective: To describe the epidemic of imported infectious diseases in China between 2013 and 2016, including the kinds of infectious diseases, affected provinces, source countries and the epidemiological characteristics, and provide scientific information for the prevention and control of imported infectious diseases. Methods: Data of cases of imported infectious diseases in China from 2013 to 2016 were collected from national information reporting system of infectious diseases, Microsoft Excel 2010 and SPSS 18.0 were used to conduct data cleaning and analysis. Results: From 2013 to 2016, a total of 16 206 imported cases of infectious diseases were reported in China. Of all the cases, 83.12% (13 471 cases) were malaria cases, followed by dengue fever (2 628 cases, 16.22%). The majority of the imported cases were males (14 522 cases, 89.61%). Most cases were aged 20-50 years. Except Zika virus disease and yellow fever, which were mainly reported before and after spring festival, other imported infectious diseases mainly occurred in summer and autumn. The epidemic in affected provinces varied with the types of infectious diseases, and Yunnan reported the largest case number of imported infectious diseases, followed by Jiangsu, Guangxi and Guangdong. The imported cases were mainly from Asian countries, such as Burma, and African countries, such as Angola, Equatorial Guinea and Ghana, which also varied with the types of infectious diseases. Conclusions: We should pay more attention to imported infectious diseases and strengthen the prevention and control measures in our country. In order to reduce the incidence of imported infectious diseases, the health education should be enforced for persons who plan to travel abroad and the active surveillance should be strengthened for returned travelers.

Susceptible-infected-recovered epidemics in random networks with population awareness

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Wu, Qingchu; Chen, Shufang

2017-10-01

The influence of epidemic information-based awareness on the spread of infectious diseases on networks cannot be ignored. Within the effective degree modeling framework, we discuss the susceptible-infected-recovered model in complex networks with general awareness and general degree distribution. By performing the linear stability analysis, the conditions of epidemic outbreak can be deduced and the results of the previous research can be further expanded. Results show that the local awareness can suppress significantly the epidemic spreading on complex networks via raising the epidemic threshold and such effects are closely related to the formulation of awareness functions. In addition, our results suggest that the recovered information-based awareness has no effect on the critical condition of epidemic outbreak.

The epidemic of Tuberculosis on vaccinated population

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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.

Topographic determinants of foot and mouth disease transmission in the UK 2001 epidemic

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Keeling Matthew J

2006-01-01

Full Text Available Abstract Background A key challenge for modelling infectious disease dynamics is to understand the spatial spread of infection in real landscapes. This ideally requires a parallel record of spatial epidemic spread and a detailed map of susceptible host density along with relevant transport links and geographical features. Results Here we analyse the most detailed such data to date arising from the UK 2001 foot and mouth epidemic. We show that Euclidean distance between infectious and susceptible premises is a better predictor of transmission risk than shortest and quickest routes via road, except where major geographical features intervene. Conclusion Thus, a simple spatial transmission kernel based on Euclidean distance suffices in most regions, probably reflecting the multiplicity of transmission routes during the epidemic.

Outbreak or Epidemic? How Obama's Language Choice Transformed the Ebola Outbreak Into an Epidemic.

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Gesser-Edelsburg, Anat; Shir-Raz, Yaffa; Bar-Lev, Oshrat Sassoni; James, James J; Green, Manfred S

2016-08-01

Our aim was to examine in what terms leading newspapers' online sites described the current Ebola crisis. We employed a quantitative content analysis of terms attributed to Ebola. We found and analyzed 582 articles published between March 23 and September 30, 2014, on the online websites of 3 newspapers: The New York Times, Daily Mail, and Ynet. Our theoretical framework drew from the fields of health communication and emerging infectious disease communication, including such concepts as framing media literacy, risk signatures, and mental models. We found that outbreak and epidemic were used interchangeably in the articles. From September 16, 2014, onward, epidemic predominated, corresponding to when President Barack Obama explicitly referred to Ebola as an epidemic. Prior to Obama's speech, 86.8% of the articles (323) used the term outbreak and only 8.6% (32) used the term epidemic. Subsequently, both terms were used almost the same amount: 53.8% of the articles (113) used the term outbreak and 53.3% (112) used the term epidemic. Effective communication is crucial during public health emergencies such as Ebola, because language framing affects the decision-making process of social judgments and actions. The choice of one term (outbreak) over another (epidemic) can create different conceptualizations of the disease, thereby influencing the risk signature. (Disaster Med Public Health Preparedness. 2016;10:669-673).

Learning from Ebola Virus: How to Prevent Future Epidemics

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Alexander S. Kekulé

2015-07-01

Full Text Available The recent Ebola virus disease (EVD epidemic in Guinea, Liberia and Sierra Leone demonstrated that the World Health Organization (WHO is incapable to control outbreaks of infectious diseases in less developed regions of the world. This essay analyses the causes for the failure of the international response and proposes four measures to improve resilience, early detection and response to future outbreaks of infectious diseases.

Mechanistic movement models to understand epidemic spread.

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Fofana, Abdou Moutalab; Hurford, Amy

2017-05-05

An overlooked aspect of disease ecology is considering how and why animals come into contact with one and other resulting in disease transmission. Mathematical models of disease spread frequently assume mass-action transmission, justified by stating that susceptible and infectious hosts mix readily, and foregoing any detailed description of host movement. Numerous recent studies have recorded, analysed and modelled animal movement. These movement models describe how animals move with respect to resources, conspecifics and previous movement directions and have been used to understand the conditions for the occurrence and the spread of infectious diseases when hosts perform a type of movement. Here, we summarize the effect of the different types of movement on the threshold conditions for disease spread. We identify gaps in the literature and suggest several promising directions for future research. The mechanistic inclusion of movement in epidemic models may be beneficial for the following two reasons. Firstly, the estimation of the transmission coefficient in an epidemic model is possible because animal movement data can be used to estimate the rate of contacts between conspecifics. Secondly, unsuccessful transmission events, where a susceptible host contacts an infectious host but does not become infected can be quantified. Following an outbreak, this enables disease ecologists to identify 'near misses' and to explore possible alternative epidemic outcomes given shifts in ecological or immunological parameters.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Author(s).

Extreme weather events and infectious disease outbreaks.

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McMichael, Anthony J

2015-01-01

Human-driven climatic changes will fundamentally influence patterns of human health, including infectious disease clusters and epidemics following extreme weather events. Extreme weather events are projected to increase further with the advance of human-driven climate change. Both recent and historical experiences indicate that infectious disease outbreaks very often follow extreme weather events, as microbes, vectors and reservoir animal hosts exploit the disrupted social and environmental conditions of extreme weather events. This review article examines infectious disease risks associated with extreme weather events; it draws on recent experiences including Hurricane Katrina in 2005 and the 2010 Pakistan mega-floods, and historical examples from previous centuries of epidemics and 'pestilence' associated with extreme weather disasters and climatic changes. A fuller understanding of climatic change, the precursors and triggers of extreme weather events and health consequences is needed in order to anticipate and respond to the infectious disease risks associated with human-driven climate change. Post-event risks to human health can be constrained, nonetheless, by reducing background rates of persistent infection, preparatory action such as coordinated disease surveillance and vaccination coverage, and strengthened disaster response. In the face of changing climate and weather conditions, it is critically important to think in ecological terms about the determinants of health, disease and death in human populations.

Interplay between the local information based behavioral responses and the epidemic spreading in complex networks.

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Liu, Can; Xie, Jia-Rong; Chen, Han-Shuang; Zhang, Hai-Feng; Tang, Ming

2015-10-01

The spreading of an infectious disease can trigger human behavior responses to the disease, which in turn plays a crucial role on the spreading of epidemic. In this study, to illustrate the impacts of the human behavioral responses, a new class of individuals, S(F), is introduced to the classical susceptible-infected-recovered model. In the model, S(F) state represents that susceptible individuals who take self-initiate protective measures to lower the probability of being infected, and a susceptible individual may go to S(F) state with a response rate when contacting an infectious neighbor. Via the percolation method, the theoretical formulas for the epidemic threshold as well as the prevalence of epidemic are derived. Our finding indicates that, with the increasing of the response rate, the epidemic threshold is enhanced and the prevalence of epidemic is reduced. The analytical results are also verified by the numerical simulations. In addition, we demonstrate that, because the mean field method neglects the dynamic correlations, a wrong result based on the mean field method is obtained-the epidemic threshold is not related to the response rate, i.e., the additional S(F) state has no impact on the epidemic threshold.

Epidemic processes in complex networks

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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.

Evaluating Subcriticality during the Ebola Epidemic in West Africa.

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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.

Epidemic spread in bipartite network by considering risk awareness

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Han, She; Sun, Mei; Ampimah, Benjamin Chris; Han, Dun

2018-02-01

Human awareness plays an important role in the spread of infectious diseases and the control of propagation patterns. Exploring the interplay between human awareness and epidemic spreading is a topic that has been receiving increasing attention. Considering the fact, some well-known diseases only spread between different species we propose a theoretical analysis of the Susceptible-Infected-Susceptible (SIS) epidemic spread from the perspective of bipartite network and risk aversion. Using mean field theory, the epidemic threshold is calculated theoretically. Simulation results are consistent with the proposed analytic model. The results show that, the final infection density is negative linear with the value of individuals' risk awareness. Therefore, the epidemic spread could be effectively suppressed by improving individuals' risk awareness.

Anti-Infective Activities of Lactobacillus Strains in the Human Intestinal Microbiota: from Probiotics to Gastrointestinal Anti-Infectious Biotherapeutic Agents

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Liévin-Le Moal, Vanessa

2014-01-01

SUMMARY A vast and diverse array of microbial species displaying great phylogenic, genomic, and metabolic diversity have colonized the gastrointestinal tract. Resident microbes play a beneficial role by regulating the intestinal immune system, stimulating the maturation of host tissues, and playing a variety of roles in nutrition and in host resistance to gastric and enteric bacterial pathogens. The mechanisms by which the resident microbial species combat gastrointestinal pathogens are complex and include competitive metabolic interactions and the production of antimicrobial molecules. The human intestinal microbiota is a source from which Lactobacillus probiotic strains have often been isolated. Only six probiotic Lactobacillus strains isolated from human intestinal microbiota, i.e., L. rhamnosus GG, L. casei Shirota YIT9029, L. casei DN-114 001, L. johnsonii NCC 533, L. acidophilus LB, and L. reuteri DSM 17938, have been well characterized with regard to their potential antimicrobial effects against the major gastric and enteric bacterial pathogens and rotavirus. In this review, we describe the current knowledge concerning the experimental antibacterial activities, including antibiotic-like and cell-regulating activities, and therapeutic effects demonstrated in well-conducted, placebo-controlled, randomized clinical trials of these probiotic Lactobacillus strains. What is known about the antimicrobial activities supported by the molecules secreted by such probiotic Lactobacillus strains suggests that they constitute a promising new source for the development of innovative anti-infectious agents that act luminally and intracellularly in the gastrointestinal tract. PMID:24696432

Peculiarities of infectious diseases course accompanied by quinsy syndrome in children (data from children infectious hospital

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Ovchinnikova T.A.

2011-03-01

Full Text Available The research goal is to study morbidity dynamics for the period of 15 years and to determine clinical signs that accompany quinsy syndrome (diphtheria, infectious mononucleosis, scarlet fever, quinsy. Retrospective study analysis of annual reports and case-histories was carried out. 323 cases of infectious diseases accompanied by quinsy syndrome were examined. Clinical and epidemic signs of diseases were determined during the period of morbidity raise. The current clinical course of diseases was characterized in detail. The significant percentage of renal complications in case of pharyngonasal cavity lesion was shown

The spray-drying process is sufficient to inactivate infectious porcine epidemic diarrhea virus in plasma.

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Gerber, Priscilla F; Xiao, Chao-Ting; Chen, Qi; Zhang, Jianqiang; Halbur, Patrick G; Opriessnig, Tanja

2014-11-07

Porcine epidemic diarrhea virus (PEDV) is considered an emergent pathogen associated with high economic losses in many pig rearing areas. Recently it has been suggested that PEDV could be transmitted to naïve pig populations through inclusion of spray-dried porcine plasma (SDPP) into the nursery diet which led to a ban of SDPP in several areas in North America and Europe. To determine the effect of spray-drying on PEDV infectivity, 3-week-old pigs were intragastrically inoculated with (1) raw porcine plasma spiked with PEDV (RAW-PEDV-CONTROL), (2) porcine plasma spiked with PEDV and then spray dried (SD-PEDV-CONTROL), (3) raw plasma from PEDV infected pigs (RAW-SICK), (4) spray-dried plasma from PEDV infected pigs (SD-SICK), or (5) spray-dried plasma from PEDV negative pigs (SD-NEG-CONTROL). For the spray-drying process, a tabletop spray-dryer with industry-like settings for inlet and outlet temperatures was used. In the RAW-PEDV-CONTROL group, PEDV RNA was present in feces at day post infection (dpi) 3 and the pigs seroconverted by dpi 14. In contrast, PEDV RNA in feces was not detected in any of the pigs in the other groups including the SD-PEDV-CONTROL group and none of the pigs had seroconverted by termination of the project at dpi 28. This work provides direct evidence that the experimental spray-drying process used in this study was effective in inactivating infectious PEDV in the plasma. Additionally, plasma collected from PEDV infected pigs at peak disease did not contain infectious PEDV. These findings suggest that the risk for PEDV transmission through commercially produced SDPP is minimal. Copyright © 2014 Elsevier B.V. All rights reserved.

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?

Influence of Media on Seasonal Influenza Epidemic Curves.

Science.gov (United States)

Saito, Satoshi; Saito, Norihiro; Itoga, Masamichi; Ozaki, Hiromi; Kimura, Toshiyuki; Okamura, Yuji; Murakami, Hiroshi; Kayaba, Hiroyuki

2016-09-01

Theoretical investigations predicting the epidemic curves of seasonal influenza have been demonstrated so far; however, there is little empirical research using ever accumulated epidemic curves. The effects of vaccine coverage and information distribution on influenza epidemics were evaluated. Four indices for epidemics (i.e., onset-peak duration, onset-end duration, ratio of the onset-peak duration to onset-end duration and steepness of epidemic curves) were defined, and the correlations between these indices and anti-flu drug prescription dose, vaccine coverage, the volume of media and search trend on influenza through internet were analyzed. Epidemiological data on seasonal influenza epidemics from 2002/2003 to 2013/2014 excluding 2009/2010 season were collected from National Institute of Infectious Diseases of Japan. The onset-peak duration and its ratio to onset-end duration correlated inversely with the volume of anti-flu drug prescription. Onset-peak duration correlated positively with media information volume on influenza. The steepness of the epidemic curve, and anti-flu drug prescription dose inversely correlated with the volume of media information. Pre-epidemic search trend and media volume on influenza correlated with the vaccine coverage in the season. Vaccine coverage had no strong effect on epidemic curve. Education through media has an effect on the epidemic curve of seasonal influenza. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

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...

Economic Incentives in the Socially Optimal Management of Infectious Disease: When [Formula: see text] is Not Enough.

Science.gov (United States)

Morin, B R; Kinzig, A P; Levin, S A; Perrings, C A

2017-09-29

Does society benefit from encouraging or discouraging private infectious disease-risk mitigation? Private individuals routinely mitigate infectious disease risks through the adoption of a range of precautions, from vaccination to changes in their contact with others. Such precautions have epidemiological consequences. Private disease-risk mitigation generally reduces both peak prevalence of symptomatic infection and the number of people who fall ill. At the same time, however, it can prolong an epidemic. A reduction in prevalence is socially beneficial. Prolongation of an epidemic is not. We find that for a large class of infectious diseases, private risk mitigation is socially suboptimal-either too low or too high. The social optimum requires either more or less private mitigation. Since private mitigation effort depends on the cost of mitigation and the cost of illness, interventions that change either of these costs may be used to alter mitigation decisions. We model the potential for instruments that affect the cost of illness to yield net social benefits. We find that where a disease is not very infectious or the duration of illness is short, it may be socially optimal to promote private mitigation effort by increasing the cost of illness. By contrast, where a disease is highly infectious or long lasting, it may be optimal to discourage private mitigation by reducing the cost of disease. Society would prefer a shorter, more intense, epidemic to a longer, less intense epidemic. There is, however, a region in parameter space where the relationship is more complicated. For moderately infectious diseases with medium infectious periods, the social optimum depends on interactions between prevalence and duration. Basic reproduction numbers are not sufficient to predict the social optimum.

Vaccination intervention on epidemic dynamics in networks

Science.gov (United States)

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

2013-02-01

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, Barabási-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.

Urgent epidemic control mechanism for aviation networks

KAUST Repository

Peng, Chengbin; Wang, Shengbin; Shi, Meixia; Jin, Xiaogang

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.

Statistics of Epidemics in Networks by Passing Messages

Science.gov (United States)

Shrestha, Munik Kumar

Epidemic processes are common out-of-equilibrium phenomena of broad interdisciplinary interest. In this thesis, we show how message-passing approach can be a helpful tool for simulating epidemic models in disordered medium like networks, and in particular for estimating the probability that a given node will become infectious at a particular time. The sort of dynamics we consider are stochastic, where randomness can arise from the stochastic events or from the randomness of network structures. As in belief propagation, variables or messages in message-passing approach are defined on the directed edges of a network. However, unlike belief propagation, where the posterior distributions are updated according to Bayes' rule, in message-passing approach we write differential equations for the messages over time. It takes correlations between neighboring nodes into account while preventing causal signals from backtracking to their immediate source, and thus avoids "echo chamber effects" where a pair of adjacent nodes each amplify the probability that the other is infectious. In our first results, we develop a message-passing approach to threshold models of behavior popular in sociology. These are models, first proposed by Granovetter, where individuals have to hear about a trend or behavior from some number of neighbors before adopting it themselves. In thermodynamic limit of large random networks, we provide an exact analytic scheme while calculating the time dependence of the probabilities and thus learning about the whole dynamics of bootstrap percolation, which is a simple model known in statistical physics for exhibiting discontinuous phase transition. As an application, we apply a similar model to financial networks, studying when bankruptcies spread due to the sudden devaluation of shared assets in overlapping portfolios. We predict that although diversification may be good for individual institutions, it can create dangerous systemic effects, and as a result

Characteristic properties of carrying out anti-epidemic arrangements during liquidation of radiation accident after-effects

International Nuclear Information System (INIS)

Shaposhnikov, A.A.; Konyshev, I.S.

1995-01-01

During liquidation of the after-effects of technogenic accidents it is necessary to maintain satisfactory sanitary and epidemiological conditions in the emergency zone and in the regions of temporary accommodation of the evacuated population, to secure epidemic safety of drinking water, edible raw materials and prepared foods, communal and other establishments. The volume and trend of anti-epidemic measures are planned depending on the type of epidemic situation. In the course of sanitary-epidemiological survey should be ascertained the prevalence of diseases among the population, epizootic among domestic animals and synanthropous rodents, the existence of natural foci of infectious diseases and their activity, the conditions of epidemically important establishments in the emergency zone, sanitary conditions of places of residence of population, the presence of transmitters of infectious diseases, the system of organization of anti-epidemic control of population and rescuers. The rehabilitation of immunological reactivity of human body up to adequate response to the antigen irritation is observed within various periods of time after recovery from radial disease (1-3 months). 17 refs.; 2 tabs

Implementation and validation of an economic module in the Be-FAST model to predict costs generated by livestock disease epidemics: Application to classical swine fever epidemics in Spain.

Science.gov (United States)

Fernández-Carrión, E; Ivorra, B; Martínez-López, B; Ramos, A M; Sánchez-Vizcaíno, J M

2016-04-01

Be-FAST is a computer program based on a time-spatial stochastic spread mathematical model for studying the transmission of infectious livestock diseases within and between farms. The present work describes a new module integrated into Be-FAST to model the economic consequences of the spreading of classical swine fever (CSF) and other infectious livestock diseases within and between farms. CSF is financially one of the most damaging diseases in the swine industry worldwide. Specifically in Spain, the economic costs in the two last CSF epidemics (1997 and 2001) reached jointly more than 108 million euros. The present analysis suggests that severe CSF epidemics are associated with significant economic costs, approximately 80% of which are related to animal culling. Direct costs associated with control measures are strongly associated with the number of infected farms, while indirect costs are more strongly associated with epidemic duration. The economic model has been validated with economic information around the last outbreaks in Spain. These results suggest that our economic module may be useful for analysing and predicting economic consequences of livestock disease epidemics. Copyright © 2016 Elsevier B.V. All rights reserved.

Simulating individual-based models of epidemics in hierarchical networks

NARCIS (Netherlands)

Quax, R.; Bader, D.A.; Sloot, P.M.A.

2009-01-01

Current mathematical modeling methods for the spreading of infectious diseases are too simplified and do not scale well. We present the Simulator of Epidemic Evolution in Complex Networks (SEECN), an efficient simulator of detailed individual-based models by parameterizing separate dynamics

Steady States in SIRS Epidemical Model of Mobile Individuals

International Nuclear Information System (INIS)

Zhang Duanming; He Minhua; Yu Xiaoling; Pan Guijun; Sun Hongzhang; Su Xiangying; Sun Fan; Yin Yanping; 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 δ c and p c below which infectious disease dies out. For the population density δ far above δ c , 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.

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.

Global stability of an SEIR epidemic model with constant immigration

Energy Technology Data Exchange (ETDEWEB)

Li Guihua [Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Faculty of Life Science, Southwest China Normal University, Chongqing 400715 (China) and Department of Mathematics, Southwest China Normal University, Chongqing 400715 (China) and Department of Mathematics, North University of China, Taiyuan Shanxi 030051 (China)]. E-mail: liguihua@nuc.edu.cn; Wang Wendi [Department of Mathematics, Southwest China Normal University, Chongqing 400715 (China); Jin Zhen [Department of Mathematics, North University of China, Taiyuan Shanxi 030051 (China)

2006-11-15

An SEIR epidemic model with the infectious force in the latent (exposed), infected and recovered period is studied. It is assumed that susceptible and exposed individuals have constant immigration rates. The model exhibits a unique endemic state if the fraction p of infectious immigrants is positive. If the basic reproduction number R is greater than 1, sufficient conditions for the global stability of the endemic equilibrium are obtained by the compound matrix theory.

Global stability of an SEIR epidemic model with constant immigration

International Nuclear Information System (INIS)

Li Guihua; Wang Wendi; Jin Zhen

2006-01-01

An SEIR epidemic model with the infectious force in the latent (exposed), infected and recovered period is studied. It is assumed that susceptible and exposed individuals have constant immigration rates. The model exhibits a unique endemic state if the fraction p of infectious immigrants is positive. If the basic reproduction number R is greater than 1, sufficient conditions for the global stability of the endemic equilibrium are obtained by the compound matrix theory

Viral shedding and emission of airborne infectious bursal disease virus from a broiler room

NARCIS (Netherlands)

Zhao, Y.; Aarnink, A.J.A.; Cambra-Lopez, M.; Fabri, T.

2013-01-01

1. The significance of airborne transmission in epidemics of infectious diseases in the livestock production industry remains unclear. The study therefore investigated the shedding route (faeces vs. exhaled air) of a vaccine strain of infectious bursal disease virus (IBDV) by broilers and the

Invited review: Epidemics on social networks

Directory of Open Access Journals (Sweden)

M. N. Kuperman

2013-01-01

Full Text Available Since its first formulations almost a century ago, mathematical models fordisease spreading contributed to understand, evaluate and control the epidemic processes.They promoted a dramatic change in how epidemiologists thought of the propagation of infectious diseases.In the last decade, when the traditional epidemiological models seemed to be exhausted, new types of models were developed.These new models incorporated concepts from graph theory to describe and model the underlying social structure.Many of these works merely produced a more detailed extension of the previous results, but some otherstriggered a completely new paradigm in the mathematical study of epidemic processes. In this review, we will introduce the basicconcepts of epidemiology, epidemic modeling and networks, to finally provide a brief description of the mostrelevant results in the field.Received: 6 April 2013, Accepted: 3 June 2013; Edited by: G. Mindlin; DOI: http://dx.doi.org/10.4279/PIP.050003Cite as: M N Kuperman, Papers in Physics 5, 050003 (2013

Modeling the effects of social impact on epidemic spreading in complex networks

Science.gov (United States)

Ni, Shunjiang; Weng, Wenguo; Zhang, Hui

2011-11-01

We investigate by mean-field analysis and extensive simulations the effects of social impact on epidemic spreading in various typical networks with two types of nodes: active nodes and passive nodes, of which the behavior patterns are modeled according to the social impact theory. In this study, nodes are not only the media to spread the virus, but also disseminate their opinions on the virus-whether there is a need for certain self-protection measures to be taken to reduce the risk of being infected. Our results indicate that the interaction between epidemic spreading and opinion dynamics can have significant influences on the spreading of infectious diseases and related applications, such as the implementation of prevention and control measures against the infectious diseases.

[A prognostic model of a cholera epidemic].

Science.gov (United States)

Boev, B V; Bondarenko, V M; Prokop'eva, N V; San Román, R T; Raygoza-Anaya, M; García de Alba, R

1994-01-01

A new model for the prognostication of cholera epidemic on the territory of a large city is proposed. This model reflects the characteristic feature of contacting infection by sensitive individuals due to the preservation of Vibrio cholerae in their water habitat. The mathematical model of the epidemic quantitatively reflects the processes of the spread of infection by kinetic equations describing the interaction of the streams of infected persons, the causative agents and susceptible persons. The functions and parameters of the model are linked with the distribution of individuals according to the duration of the incubation period and infectious process, as well as the period of asymptomatic carrier state. The computer realization of the model by means of IBM PC/AT made it possible to study the cholera epidemic which took place in Mexico in 1833. The verified model of the cholera epidemic was used for the prognostication of the possible spread of this infection in Guadalajara, taking into account changes in the epidemiological situation and the size of the population, as well as improvements in sanitary and hygienic conditions, in the city.

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.

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

Dynamics of epidemic diseases on a growing adaptive network.

Science.gov (United States)

Demirel, Güven; Barter, Edmund; Gross, Thilo

2017-02-10

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.

The Risk of Chronic Gastrointestinal Disorders Following Acute Infection with Intestinal Parasites

Directory of Open Access Journals (Sweden)

Jason Blitz

2018-01-01

Full Text Available Background: Infectious gastroenteritis (IGE is caused by numerous bacterial, viral, and parasitic pathogens. A history of IGE has been shown in previous studies to increase the risk of developing chronic gastrointestinal disorders and other chronic conditions. As bacteria and viruses represent the majority of pathogen-specific causes of IGE, post-infectious studies have primarily focused on these organisms. The objective of this study was to investigate an association between a history of parasite-associated IGE and the subsequent development of chronic post-infectious gastrointestinal and non-gastrointestinal disorders in a military population.Methods: International Classification of Diseases, 9th Revision Clinical Modification (ICD-9-CM diagnostic coding data for primary exposures and outcomes were obtained for a retrospective cohort study of active component military personnel from 1998 to 2013. Exposed subjects consisted of individuals with documented infection with one of ten parasitic pathogens. Unexposed subjects were matched to exposed subjects on demographic and operational deployment history parameters. Adjusted odds ratios (aORs were estimated using logistic regression for several chronic disorders previously shown to be associated with a history of IGE.Results: A total of 896 subjects with a parasitic exposure were matched to 3681 unexposed subjects for multivariate regression analysis. Individuals infected with Balantidium coli, Ascaris lumbricoides, Strongyloides stercoralis, Necator americanus/Ancylostoma duodenale, and Taenia spp. had higher aOR for development of several chronic gastrointestinal disorders when compared with unexposed subjects after controlling for various covariates.Conclusion: We found that parasite-associated enteric infection increases the risk of development of post-infectious chronic gastrointestinal disorders in a military population. These results require confirmation in similar populations and in the

Dynamics of Ebola epidemics in West Africa 2014 [v2; ref status: indexed, http://f1000r.es/5fh

Directory of Open Access Journals (Sweden)

Robin J. Evans

2015-05-01

Full Text Available This paper investigates the dynamics of Ebola virus transmission in West Africa during 2014. The reproduction numbers for the total period of epidemic and for different consequent time intervals are estimated based on a simple linear model. It contains one major parameter - the average infectious period that defines the dynamics of epidemics. Numerical implementations are carried out on data collected from three countries Guinea, Sierra Leone and Liberia as well as the total data collected worldwide. Predictions are provided by considering different scenarios involving the average times of infectiousness for the next few months and the end of the current epidemic is estimated according to each scenario.

Epidemic spreading induced by diversity of agents' mobility.

Science.gov (United States)

Zhou, Jie; Chung, Ning Ning; Chew, Lock Yue; Lai, Choy Heng

2012-08-01

In this paper, we study the impact of the preference of an individual for public transport on the spread of infectious disease, through a quantity known as the public mobility. Our theoretical and numerical results based on a constructed model reveal that if the average public mobility of the agents is fixed, an increase in the diversity of the agents' public mobility reduces the epidemic threshold, beyond which an enhancement in the rate of infection is observed. Our findings provide an approach to improve the resistance of a society against infectious disease, while preserving the utilization rate of the public transportation system.

A generalized-growth model to characterize the early ascending phase of infectious disease outbreaks

DEFF Research Database (Denmark)

Viboud, Cecile; Simonsen, Lone; Chowell, Gerardo

2016-01-01

the importance of sub-exponential growth for forecasting purposes.Results: We applied the generalized-growth model to 20 infectious disease outbreaks representing a range of transmission routes. We uncovered epidemic profiles ranging from very slow growth (p = 0.14 for the Ebola outbreak in Bomi, Liberia (2014...... African Ebola epidemic provided a unique opportunity to explore how growth profiles vary by geography; analysis of the largest district-level outbreaks revealed substantial growth variations (mean p = 0.59, range: 0.14–0.97). The districts of Margibi in Liberia and Bombali and Bo in Sierra Leone had near......-exponential growth, while the districts of Bomi in Liberia and Kenema in Sierra Leone displayed near constant incidences.Conclusions: Our findings reveal significant variation in epidemic growth patterns across different infectious disease outbreaks and highlights that sub-exponential growth is a common phenomenon...

Ciguatera fish poisoning. A southern California epidemic.

Science.gov (United States)

Barton, E D; Tanner, P; Turchen, S G; Tunget, C L; Manoguerra, A; Clark, R F

1995-01-01

Ciguatera fish poisoning results from the bioconcentration of a variety of toxins produced by marine dinoflagellates. Signs and symptoms vary widely, but it usually presents as gastrointestinal and neurologic complaints beginning shortly after the ingestion of fish containing the toxins. Symptoms may persist for months and sometimes even years. Although cases have been reported throughout the United States, epidemics are most common along tropical and subtropical coasts and usually involve the ingestion of large carnivorous fish. We review the literature and report the first epidemic of 25 cases of ciguatera fish poisoning presenting to area hospitals in Southern California that were successfully tracked by the Department of Health Services and isolated to fish caught off the coast of Baja California, Mexico. Images Figure 1. PMID:7667980

Extinction times of epidemic outbreaks in networks.

Science.gov (United States)

Holme, Petter

2013-01-01

In the Susceptible-Infectious-Recovered (SIR) model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

Extinction times of epidemic outbreaks in networks.

Directory of Open Access Journals (Sweden)

Petter Holme

Full Text Available In the Susceptible-Infectious-Recovered (SIR model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

Population Explosions of Tiger Moth Lead to Lepidopterism Mimicking Infectious Fever Outbreaks.

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Pallara Janardhanan Wills

Full Text Available Lepidopterism is a disease caused by the urticating scales and toxic fluids of adult moths, butterflies or its caterpillars. The resulting cutaneous eruptions and systemic problems progress to clinical complications sometimes leading to death. High incidence of fever epidemics were associated with massive outbreaks of tiger moth Asota caricae adult populations during monsoon in Kerala, India. A significant number of monsoon related fever characteristic to lepidopterism was erroneously treated as infectious fevers due to lookalike symptoms. To diagnose tiger moth lepidopterism, we conducted immunoblots for tiger moth specific IgE in fever patients' sera. We selected a cohort of patients (n = 155 with hallmark symptoms of infectious fevers but were tested negative to infectious fevers. In these cases, the total IgE was elevated and was detected positive (78.6% for tiger moth specific IgE allergens. Chemical characterization of caterpillar and adult moth fluids was performed by HPLC and GC-MS analysis and structural identification of moth scales was performed by SEM analysis. The body fluids and chitinous scales were found to be highly toxic and inflammatory in nature. To replicate the disease in experimental model, wistar rats were exposed to live tiger moths in a dose dependant manner and observed similar clinico-pathological complications reported during the fever epidemics. Further, to link larval abundance and fever epidemics we conducted cointegration test for the period 2009 to 2012 and physical presence of the tiger moths were found to be cointegrated with fever epidemics. In conclusion, our experiments demonstrate that inhalation of aerosols containing tiger moth fluids, scales and hairs cause systemic reactions that can be fatal to human. All these evidences points to the possible involvement of tiger moth disease as a major cause to the massive and fatal fever epidemics observed in Kerala.

The chronic gastrointestinal manifestations of Chagas disease

Directory of Open Access Journals (Sweden)

Nilce Mitiko Matsuda

2009-01-01

Full Text Available Chagas disease is an infectious disease caused by the protozoan Trypanosoma cruzi. The disease mainly affects the nervous system, digestive system and heart. The objective of this review is to revise the literature and summarize the main chronic gastrointestinal manifestations of Chagas disease. The chronic gastrointestinal manifestations of Chagas disease are mainly a result of enteric nervous system impairment caused by T. cruzi infection. The anatomical locations most commonly described to be affected by Chagas disease are salivary glands, esophagus, lower esophageal sphincter, stomach, small intestine, colon, gallbladder and biliary tree. Chagas disease has also been studied in association with Helicobacter pylori infection, interstitial cells of Cajal and the incidence of gastrointestinal cancer.

Infectious diseases in cinema: virus hunters and killer microbes.

Science.gov (United States)

Pappas, Georgios; Seitaridis, Savvas; Akritidis, Nikolaos; Tsianos, Epaminondas

2003-10-01

The world of infectious diseases has been rarely presented in the cinema with accuracy. Apart from random biographies of scientists and retellings of stories about great epidemics from the past, most films focus on the dangers presented by outbreaks of unknown agents that originate from acts of bioterrorism, from laboratory accidents, or even from space. We review these films and underline the possible effect that they have on the public's perception of infection--a perception that, when misguided, could prove to be problematic in times of epidemics.

Using data-driven agent-based models for forecasting emerging infectious diseases

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Srinivasan Venkatramanan

2018-03-01

Full Text Available Producing timely, well-informed and reliable forecasts for an ongoing epidemic of an emerging infectious disease is a huge challenge. Epidemiologists and policy makers have to deal with poor data quality, limited understanding of the disease dynamics, rapidly changing social environment and the uncertainty on effects of various interventions in place. Under this setting, detailed computational models provide a comprehensive framework for integrating diverse data sources into a well-defined model of disease dynamics and social behavior, potentially leading to better understanding and actions. In this paper, we describe one such agent-based model framework developed for forecasting the 2014–2015 Ebola epidemic in Liberia, and subsequently used during the Ebola forecasting challenge. We describe the various components of the model, the calibration process and summarize the forecast performance across scenarios of the challenge. We conclude by highlighting how such a data-driven approach can be refined and adapted for future epidemics, and share the lessons learned over the course of the challenge. Keywords: Emerging infectious diseases, Agent-based models, Simulation optimization, Bayesian calibration, Ebola

An introduction to mathematical modeling of infectious diseases

CERN Document Server

Li, Michael Y

2018-01-01

This text provides essential modeling skills and methodology for the study of infectious diseases through a one-semester modeling course or directed individual studies.  The book includes mathematical descriptions of epidemiological concepts, and uses classic epidemic models to introduce different mathematical methods in model analysis.  Matlab codes are also included for numerical implementations. It is primarily written for upper undergraduate and beginning graduate students in mathematical sciences who have an interest in mathematical modeling of infectious diseases.  Although written in a rigorous mathematical manner, the style is not unfriendly to non-mathematicians.

Emerging and Neglected Infectious Diseases: Insights, Advances, and Challenges.

Science.gov (United States)

Nii-Trebi, Nicholas Israel

2017-01-01

Infectious diseases are a significant burden on public health and economic stability of societies all over the world. They have for centuries been among the leading causes of death and disability and presented growing challenges to health security and human progress. The threat posed by infectious diseases is further deepened by the continued emergence of new, unrecognized, and old infectious disease epidemics of global impact. Over the past three and half decades at least 30 new infectious agents affecting humans have emerged, most of which are zoonotic and their origins have been shown to correlate significantly with socioeconomic, environmental, and ecological factors. As these factors continue to increase, putting people in increased contact with the disease causing pathogens, there is concern that infectious diseases may continue to present a formidable challenge. Constant awareness and pursuance of effective strategies for controlling infectious diseases and disease emergence thus remain crucial. This review presents current updates on emerging and neglected infectious diseases and highlights the scope, dynamics, and advances in infectious disease management with particular focus on WHO top priority emerging infectious diseases (EIDs) and neglected tropical infectious diseases.

Operationalising factors that explain the emergence of infectious diseases: a case study of the human campylobacteriosis epidemic.

Directory of Open Access Journals (Sweden)

Norval J C Strachan

Full Text Available A framework of general factors for infectious disease emergence was made operational for Campylobacter utilising explanatory variables including time series and risk factor data. These variables were generated using a combination of empirical epidemiology, case-case and case-control studies, time series analysis, and microbial sub-typing (source attribution, diversity, genetic distance to unravel the changing/emerging aetiology of human campylobacteriosis. The study focused on Scotland between 1990-2012 where there was a 75% increase in reported cases that included >300% increase in the elderly and 50% decrease in young children. During this period there were three phases 1990-2000 a 75% rise and a 20% fall to 2006, followed by a 19% resurgence. The rise coincided with expansions in the poultry industry, consumption of chicken, and a shift from rural to urban cases. The post-2000 fall occurred across all groups apart from the elderly and coincided with a drop of the prevalence of Campylobacter in chicken and a higher proportion of rural cases. The increase in the elderly was associated with uptake of proton pump inhibitors. During the resurgence the increase was predominantly in adults and the elderly, again there was increasing use of PPIs and high prevalences in chicken and ruminants. Cases associated with foreign travel during the study also increased from 9% to a peak of 16% in 2006 before falling to an estimated 10% in 2011, predominantly in adults and older children. During all three periods source attribution, genetic distance, and diversity measurements placed human isolates most similar to those in chickens. A combination of emergence factors generic for infectious diseases were responsible for the Campylobacter epidemic. It was possible to use these to obtain a putative explanation for the changes in human disease and the potential to make an informed view of how incidence rates may change in the future.

Analysis of social network - An approach towards evaluation of spreading of epidemics in randomized social Network.

OpenAIRE

Rasmita Panigrahi; Trilochan Rout

2012-01-01

Classifying nodes in a network is a task with wide range of applications .it can be particularly useful in epidemics detection .Many resources are invested in the task of epidemics and precisely allow human investigators to work more efficiently. This work creates random and scale- free graphs the simulations with varying relative infectiousness and graph size performed. By using computer simulations it should be possible to model such epidemic Phenomena and to better understand the role play...

Equal Graph Partitioning on Estimated Infection Network as an Effective Epidemic Mitigation Measure

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Hadidjojo, Jeremy; Cheong, Siew Ann

2011-01-01

Controlling severe outbreaks remains the most important problem in infectious disease area. With time, this problem will only become more severe as population density in urban centers grows. Social interactions play a very important role in determining how infectious diseases spread, and organization of people along social lines gives rise to non-spatial networks in which the infections spread. Infection networks are different for diseases with different transmission modes, but are likely to be identical or highly similar for diseases that spread the same way. Hence, infection networks estimated from common infections can be useful to contain epidemics of a more severe disease with the same transmission mode. Here we present a proof-of-concept study demonstrating the effectiveness of epidemic mitigation based on such estimated infection networks. We first generate artificial social networks of different sizes and average degrees, but with roughly the same clustering characteristic. We then start SIR epidemics on these networks, censor the simulated incidences, and use them to reconstruct the infection network. We then efficiently fragment the estimated network by removing the smallest number of nodes identified by a graph partitioning algorithm. Finally, we demonstrate the effectiveness of this targeted strategy, by comparing it against traditional untargeted strategies, in slowing down and reducing the size of advancing epidemics. PMID:21799777

Comparing methods to quantify experimental transmission of infectious agents

NARCIS (Netherlands)

Velthuis, A.G.J.; Jong, de M.C.M.; Bree, de J.

2007-01-01

Transmission of an infectious agent can be quantified from experimental data using the transient-state (TS) algorithm. The TS algorithm is based on the stochastic SIR model and provides a time-dependent probability distribution over the number of infected individuals during an epidemic, with no need

Scale-dependent climatic drivers of human epidemics in ancient China.

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Tian, Huidong; Yan, Chuan; Xu, Lei; Büntgen, Ulf; Stenseth, Nils C; Zhang, Zhibin

2017-12-05

A wide range of climate change-induced effects have been implicated in the prevalence of infectious diseases. Disentangling causes and consequences, however, remains particularly challenging at historical time scales, for which the quality and quantity of most of the available natural proxy archives and written documentary sources often decline. Here, we reconstruct the spatiotemporal occurrence patterns of human epidemics for large parts of China and most of the last two millennia. Cold and dry climate conditions indirectly increased the prevalence of epidemics through the influences of locusts and famines. Our results further reveal that low-frequency, long-term temperature trends mainly contributed to negative associations with epidemics, while positive associations of epidemics with droughts, floods, locusts, and famines mainly coincided with both higher and lower frequency temperature variations. Nevertheless, unstable relationships between human epidemics and temperature changes were observed on relatively smaller time scales. Our study suggests that an intertwined, direct, and indirect array of biological, ecological, and societal responses to different aspects of past climatic changes strongly depended on the frequency domain and study period chosen.

The French Infectious Diseases Society's readiness and response to epidemic or biological risk-the current situation following the Middle East respiratory syndrome coronavirus and Ebola virus disease alerts.

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Coignard-Biehler, H; Rapp, C; Chapplain, J M; Hoen, B; Che, D; Berthelot, P; Cazenave-Roblot, F; Rabaud, C; Brouqui, P; Leport, C

2018-03-01

In 2012, the French Infectious Diseases Society (French acronym SPILF) initiated the "Coordination of epidemic and biological risk" (SPILF-COREB - Emergences [SCE]) group to support the readiness and response of healthcare workers (HCWs) to new alerts. To present the SCE group, its functioning, and the main support it provided for frontline HCWs. A multidisciplinary group of heads of infectious disease departments from reference hospitals was created to build a network of clinical expertise for care, training, and research in the field of epidemic and biological risk (EBR). The network developed a set of standardized operational procedures (SOPs) to guide interventions to manage EBR-suspect patients. A working group created the SOP aimed at frontline HCWs taking care of patients. Priority was given to the development of a generic procedure, which was then adapted according to the current alert. Five key steps were identified and hierarchized: detecting, protecting, caring for, alerting, and referring the EBR patient. The interaction between clinicians and those responsible for the protection of the community was crucial. The SOPs validated by the SPILF and its affiliates were disseminated to a wide range of key stakeholders through various media including workshops and the SPILF's website. SPILF can easily adapt and timely mobilize the EBR expertise in case of an alert. The present work suggests that sharing and discussing this experience, initiated at the European level, can generate a new collective expertise and needs to be further developed and strengthened. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Infectious Diseases Continued to be the World's Core Challenge

African Journals Online (AJOL)

user

Plague epidemic is going on in Madagascar. Many countries are in constant worries that such deadly infectious diseases might be carried from one part of the world to them (3). Although member countries signed an international agreement to report outbreaks promptly to the. World Health Organization and take steps to.

A stochastic SIS epidemic model with vaccination

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Cao, Boqiang; Shan, Meijing; Zhang, Qimin; Wang, Weiming

2017-11-01

In this paper, we investigate the basic features of an SIS type infectious disease model with varying population size and vaccinations in presence of environment noise. By applying the Markov semigroup theory, we propose a stochastic reproduction number R0s which can be seen as a threshold parameter to utilize in identifying the stochastic extinction and persistence: If R0s disease-free absorbing set for the stochastic epidemic model, which implies that disease dies out with probability one; while if R0s > 1, under some mild extra conditions, the SDE model has an endemic stationary distribution which results in the stochastic persistence of the infectious disease. The most interesting finding is that large environmental noise can suppress the outbreak of the disease.

How to select a proper early warning threshold to detect infectious disease outbreaks based on the China infectious disease automated alert and response system (CIDARS).

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Wang, Ruiping; Jiang, Yonggen; Michael, Engelgau; Zhao, Genming

2017-06-12

China Centre for Diseases Control and Prevention (CDC) developed the China Infectious Disease Automated Alert and Response System (CIDARS) in 2005. The CIDARS was used to strengthen infectious disease surveillance and aid in the early warning of outbreak. The CIDARS has been integrated into the routine outbreak monitoring efforts of the CDC at all levels in China. Early warning threshold is crucial for outbreak detection in the CIDARS, but CDCs at all level are currently using thresholds recommended by the China CDC, and these recommended thresholds have recognized limitations. Our study therefore seeks to explore an operational method to select the proper early warning threshold according to the epidemic features of local infectious diseases. The data used in this study were extracted from the web-based Nationwide Notifiable Infectious Diseases Reporting Information System (NIDRIS), and data for infectious disease cases were organized by calendar week (1-52) and year (2009-2015) in Excel format; Px was calculated using a percentile-based moving window (moving window [5 week*5 year], x), where x represents one of 12 centiles (0.40, 0.45, 0.50….0.95). Outbreak signals for the 12 Px were calculated using the moving percentile method (MPM) based on data from the CIDARS. When the outbreak signals generated by the 'mean + 2SD' gold standard were in line with a Px generated outbreak signal for each week during the year of 2014, this Px was then defined as the proper threshold for the infectious disease. Finally, the performance of new selected thresholds for each infectious disease was evaluated by simulated outbreak signals based on 2015 data. Six infectious diseases were selected in this study (chickenpox, mumps, hand foot and mouth diseases (HFMD), scarlet fever, influenza and rubella). Proper thresholds for chickenpox (P75), mumps (P80), influenza (P75), rubella (P45), HFMD (P75), and scarlet fever (P80) were identified. The selected proper thresholds for these

Impact of individual behaviour change on the spread of emerging infectious diseases.

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Yan, Q L; Tang, S Y; Xiao, Y N

2018-03-15

Human behaviour plays an important role in the spread of emerging infectious diseases, and understanding the influence of behaviour changes on epidemics can be key to improving control efforts. However, how the dynamics of individual behaviour changes affects the development of emerging infectious disease is a key public health issue. To develop different formula for individual behaviour change and introduce how to embed it into a dynamic model of infectious diseases, we choose A/H1N1 and Ebola as typical examples, combined with the epidemic reported cases and media related news reports. Thus, the logistic model with the health belief model is used to determine behaviour decisions through the health belief model constructs. Furthermore, we propose 4 candidate infectious disease models without and with individual behaviour change and use approximate Bayesian computation based on sequential Monte Carlo method for model selection. The main results indicate that the classical compartment model without behaviour change and the model with average rate of behaviour change depicted by an exponential function could fit the observed data best. The results provide a new way on how to choose an infectious disease model to predict the disease prevalence trend or to evaluate the influence of intervention measures on disease control. However, sensitivity analyses indicate that the accumulated number of hospital notifications and deaths could be largely reduced as the rate of behaviour change increases. Therefore, in terms of mitigating emerging infectious diseases, both media publicity focused on how to guide people's behaviour change and positive responses of individuals are critical. Copyright © 2017 John Wiley & Sons, Ltd.

Measles epidemics of variable lethality in the early 20th century.

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Shanks, G Dennis; Hu, Zheng; Waller, Michael; Lee, Seung-eun; Terfa, Daniel; Howard, Alan; van Heyningen, Elizabeth; Brundage, John F

2014-02-15

Until the mid-20th century, mortality rates were often very high during measles epidemics, particularly among previously isolated populations (e.g., islanders), refugees/internees who were forcibly crowded into camps, and military recruits. Searching for insights regarding measles mortality rates, we reviewed historical records of measles epidemics on the Polynesian island of Rotuma (in 1911), in Boer War concentration camps (in 1900-1902), and in US Army mobilization camps during the First World War (in 1917-1918). Records classified measles deaths by date and clinical causes; by demographic characteristics, family relationships (for Rotuma islanders and Boer camp internees), and prior residences; and by camp (for Boer internees and US Army recruits). During the Rotuman and Boer War epidemics, measles-related mortality rates were high (up to 40%); however, mortality rates differed more than 10-fold across camps/districts, even though conditions were similar. During measles epidemics, most deaths among camp internees/military recruits were due to secondary bacterial pneumonias; in contrast, most deaths among Rotuman islanders were due to gastrointestinal complications. The clinical expressions, courses, and outcomes of measles during first-contact epidemics differ from those during camp epidemics. The degree of isolation from respiratory pathogens other than measles may significantly determine measles-related mortality risk.

Recurrent dynamics in an epidemic model due to stimulated bifurcation crossovers

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Juanico, Drandreb Earl [Department of Mathematics, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines 1108 (Philippines); National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines 1101 (Philippines)

2015-05-15

Epidemics are known to persist in the form of recurrence cycles. Despite intervention efforts through vaccination and targeted social distancing, peaks of activity for infectious diseases like influenza reappear over time. Analysis of a stochastic model is here undertaken to explore a proposed cycle-generating mechanism – the bifurcation crossover. Time series from simulations of the model exhibit oscillations similar to the temporal signature of influenza activity. Power-spectral density indicates a resonant frequency, which corresponds to the annual seasonality of influenza in temperate zones. The study finds that intervention actions influence the extinguishability of epidemic activity. Asymptotic solution to a backward Kolmogorov equation corresponds to a mean extinction time that is a function of both intervention efficacy and population size. Intervention efficacy must be greater than a certain threshold to increase the chances of extinguishing the epidemic. Agreement of the model with several phenomenological features of epidemic cycles lends to it a tractability that may serve as early warning of imminent outbreaks.

Recurrent dynamics in an epidemic model due to stimulated bifurcation crossovers

International Nuclear Information System (INIS)

Juanico, Drandreb Earl

2015-01-01

Epidemics are known to persist in the form of recurrence cycles. Despite intervention efforts through vaccination and targeted social distancing, peaks of activity for infectious diseases like influenza reappear over time. Analysis of a stochastic model is here undertaken to explore a proposed cycle-generating mechanism – the bifurcation crossover. Time series from simulations of the model exhibit oscillations similar to the temporal signature of influenza activity. Power-spectral density indicates a resonant frequency, which corresponds to the annual seasonality of influenza in temperate zones. The study finds that intervention actions influence the extinguishability of epidemic activity. Asymptotic solution to a backward Kolmogorov equation corresponds to a mean extinction time that is a function of both intervention efficacy and population size. Intervention efficacy must be greater than a certain threshold to increase the chances of extinguishing the epidemic. Agreement of the model with several phenomenological features of epidemic cycles lends to it a tractability that may serve as early warning of imminent outbreaks

Epidemic Wave Dynamics Attributable to Urban Community Structure: A Theoretical Characterization of Disease Transmission in a Large Network

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Eggo, Rosalind M; Lenczner, Michael

2015-01-01

Background Multiple waves of transmission during infectious disease epidemics represent a major public health challenge, but the ecological and behavioral drivers of epidemic resurgence are poorly understood. In theory, community structure—aggregation into highly intraconnected and loosely interconnected social groups—within human populations may lead to punctuated outbreaks as diseases progress from one community to the next. However, this explanation has been largely overlooked in favor of temporal shifts in environmental conditions and human behavior and because of the difficulties associated with estimating large-scale contact patterns. Objective The aim was to characterize naturally arising patterns of human contact that are capable of producing simulated epidemics with multiple wave structures. Methods We used an extensive dataset of proximal physical contacts between users of a public Wi-Fi Internet system to evaluate the epidemiological implications of an empirical urban contact network. We characterized the modularity (community structure) of the network and then estimated epidemic dynamics under a percolation-based model of infectious disease spread on the network. We classified simulated epidemics as multiwave using a novel metric and we identified network structures that were critical to the network’s ability to produce multiwave epidemics. Results We identified robust community structure in a large, empirical urban contact network from which multiwave epidemics may emerge naturally. This pattern was fueled by a special kind of insularity in which locally popular individuals were not the ones forging contacts with more distant social groups. Conclusions Our results suggest that ordinary contact patterns can produce multiwave epidemics at the scale of a single urban area without the temporal shifts that are usually assumed to be responsible. Understanding the role of community structure in epidemic dynamics allows officials to anticipate epidemic

Recurrent epidemic cycles driven by intervention in a population of two susceptibility types

International Nuclear Information System (INIS)

Juanico, Drandreb Earl O

2014-01-01

Epidemics have been known to persist in the form of recurrence cycles. Despite intervention efforts through vaccination and targeted social distancing, infectious diseases like influenza continue to appear intermittently over time. I have undertaken an analysis of a stochastic epidemic model to explore the hypothesis that intervention efforts actually drive epidemic cycles. Time series from simulations of the model reveal oscillations exhibiting a similar temporal signature as influenza epidemics. The power-spectral density indicates a resonant frequency, which approximately corresponds to the apparent annual seasonality of influenza in temperate zones. Asymptotic solution to the backward Kolmogorov equation of the dynamics corresponds to an exponentially-decaying mean-exit time as a function of the intervention rate. Intervention must be implemented at a sufficiently high rate to extinguish the infection. The results demonstrate that intervention efforts can induce epidemic cycles, and that the temporal signature of cycles can provide early warning of imminent outbreaks

Ethnomedical and ethnobotanical investigations on the response capacities of Guinean traditional health practioners in the management of outbreaks of infectious diseases: The case of the Ebola virus epidemic.

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Baldé, A M; Traoré, M S; Baldé, M A; Barry, M S; Diallo, A; Camara, M; Traoré, S; Kouyaté, M; Traoré, S; Ouo-Ouo, S; Myanthé, A L; Keita, N; Haba, N L; Goumou, K; Bah, F; Camara, A; Diallo, M S T; Sylla, M; Baldé, E S; Diané, S; Pieters, L; Oularé, K

2016-04-22

The recent outbreak of Ebola virus infections has mostly remained confined to the West African countries Guinea-Conakry, Sierra-Leone and Liberia. Due to intense national and international mobilizations, a significant reduction in Ebola virus transmission has been recorded. While international efforts focus on new vaccines, medicines and diagnostics, no coherent national or international approach exists to integrate the potential of the traditional health practitioners (THPs) in the management of infectious diseases epidemics. Nevertheless, the first contact of most of the Ebola infected patients is with the THPs since the symptoms are similar to those of common traditionally treated diseases or symptoms such as malaria, hemorrhagic syndrome, typhoid or other gastrointestinal diseases, fever and vomiting. In an ethnomedical survey conducted in the 4 main Guinean regions contacts were established with a total of 113 THPs. The socio-demographic characteristics, the professional status and the traditional perception of Ebola Virus Disease (EVD) were recorded. The traditional treatment of the main symptoms was based on 47 vegetal recipes which were focused on the treatment of diarrhea (22 recipes), fever (22 recipes), vomiting (2 recipes), external antiseptic (2 recipes), hemorrhagic syndrome (2 recipes), convulsion and dysentery (one recipe each). An ethnobotanical survey led to the collection of 54 plant species from which 44 identified belonging to 26 families. The most represented families were Euphorbiaceae, Caesalpiniaceae and Rubiaceae. Literature data on the twelve most cited plant species tends to corroborate their traditional use and to highlight their pharmacological potential. It is worth to document all available knowledge on the traditional management of EVD-like symptoms in order to evaluate systematically the anti-Ebola potential of Guinean plant species. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

[Scabies epidemic in a sheltered workshop--what should be done?].

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Mayer, J; Wever, S; Lurz, C; Bröcker, E B

2000-02-01

Scabies is an infectious parasitic skin disease with a notable rising incidence in Germany. The disease is usually transmitted by close physical contact, but indirect spread e.g. by bedding is also possible. Due to its contagiousness, introduction of scabies into crowding living facilities, such as dormitories or kindergartens, can easily cause an epidemic outbreak. We describe an epidemic of scabies in a workshop for handicapped people in February 1998. A worker with severe scabies reported that numerous colleagues in both workshop and the associated hostel had complained of pruritus for months and that some of them already had undergone scabicide treatment. The number of contacts (staff, colleagues, friends, attendants, family) of our patient and the other already affected people was more than 460. The management of the workshop asked for help in handling the epidemic. We describe the cooperative efforts of the management, as well as hospital and private dermatologists, to evaluate all potential contacts and present a concept of treatment for the termination of such an epidemic outbreak of scabies.

Two-stage effects of awareness cascade on epidemic spreading in multiplex networks

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Guo, Quantong; Jiang, Xin; Lei, Yanjun; Li, Meng; Ma, Yifang; Zheng, Zhiming

2015-01-01

Human awareness plays an important role in the spread of infectious diseases and the control of propagation patterns. The dynamic process with human awareness is called awareness cascade, during which individuals exhibit herd-like behavior because they are making decisions based on the actions of other individuals [Borge-Holthoefer et al., J. Complex Networks 1, 3 (2013), 10.1093/comnet/cnt006]. In this paper, to investigate the epidemic spreading with awareness cascade, we propose a local awareness controlled contagion spreading model on multiplex networks. By theoretical analysis using a microscopic Markov chain approach and numerical simulations, we find the emergence of an abrupt transition of epidemic threshold βc with the local awareness ratio α approximating 0.5 , which induces two-stage effects on epidemic threshold and the final epidemic size. These findings indicate that the increase of α can accelerate the outbreak of epidemics. Furthermore, a simple 1D lattice model is investigated to illustrate the two-stage-like sharp transition at αc≈0.5 . The results can give us a better understanding of why some epidemics cannot break out in reality and also provide a potential access to suppressing and controlling the awareness cascading systems.

Effect of non-stationary climate on infectious gastroenteritis transmission in Japan

Science.gov (United States)

Onozuka, Daisuke

2014-06-01

Local weather factors are widely considered to influence the transmission of infectious gastroenteritis. Few studies, however, have examined the non-stationary relationships between global climatic factors and transmission of infectious gastroenteritis. We analyzed monthly data for cases of infectious gastroenteritis in Fukuoka, Japan from 2000 to 2012 using cross-wavelet coherency analysis to assess the pattern of associations between indices for the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO). Infectious gastroenteritis cases were non-stationary and significantly associated with the IOD and ENSO (Multivariate ENSO Index [MEI], Niño 1 + 2, Niño 3, Niño 4, and Niño 3.4) for a period of approximately 1 to 2 years. This association was non-stationary and appeared to have a major influence on the synchrony of infectious gastroenteritis transmission. Our results suggest that non-stationary patterns of association between global climate factors and incidence of infectious gastroenteritis should be considered when developing early warning systems for epidemics of infectious gastroenteritis.

Bayesian analysis for inference of an emerging epidemic: citrus canker in urban landscapes

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Outbreaks of infectious diseases require a rapid response from policy makers. The strength and efficacy of the responses depend upon available knowledge of the spatial and temporal parameters governing pathogen spread, affecting, amongst others, the predicted severity of the epidemic. Yet, when a ne...

From epidemics to information propagation : Striking differences in structurally similar adaptive network models

NARCIS (Netherlands)

Trajanovski, S.; Guo, D.; Van Mieghem, P.F.A.

2015-01-01

The continuous-time adaptive susceptible-infected-susceptible (ASIS) epidemic model and the adaptive information diffusion (AID) model are two adaptive spreading processes on networks, in which a link in the network changes depending on the infectious state of its end nodes, but in opposite ways:

Review. Systems for prevention and control of epidemic emergencies

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Paolo Calistri

2013-09-01

Full Text Available The development of early warning systems is fundamental for preventing the spread of infectious diseases. Data collection, however, is a costly activity and it is not possible to implement early warning systems everywhere and for all possible events. Hence, tools helping to improve the focus of surveillance efforts are of paramount importance. Risk assessment methods and other provisional modelling techniques may permit to estimate the probability of introduction and spread of infectious diseases in different geographical areas. Similarly, efficient information systems must be in place to assist the veterinary services in case of epidemic emergencies in order to support the prompt application of control measures for the containment of the infection and the reduction of the magnitude of negative consequences. This review describes two recent approaches to the estimation of the probability of introduction and spread of infectious diseases based on the use of risk maps/spatial modelling and Social Network Analysis (SNA techniques. The review also describes a web application developed in Italy to help official veterinary services to trace animals in case of outbreaks of infectious diseases.

Epidemiology and vaccine of porcine epidemic diarrhea virus in China: a mini-review.

Science.gov (United States)

Sun, Dongbo; Wang, Xinyu; Wei, Shan; Chen, Jianfei; Feng, Li

2016-03-01

Porcine epidemic diarrhea (PED) is an intestinal infectious disease caused by porcine epidemic diarrhea virus (PEDV); manifestations of the disease are diarrhea, vomiting and dehydration. Starting from the end of 2010, a PED outbreak occurred in several pig-producing provinces in southern China. Subsequently, the disease spread throughout the country and caused enormous economic losses to the pork industry. Accumulating studies demonstrated that new PEDV variants that appeared in China were responsible for the PED outbreak. In the current mini-review, we summarize PEDV epidemiology and vaccination in China.

Defining epidemics in computer simulation models: How do definitions influence conclusions?

Directory of Open Access Journals (Sweden)

Carolyn Orbann

2017-06-01

Full Text Available Computer models have proven to be useful tools in studying epidemic disease in human populations. Such models are being used by a broader base of researchers, and it has become more important to ensure that descriptions of model construction and data analyses are clear and communicate important features of model structure. Papers describing computer models of infectious disease often lack a clear description of how the data are aggregated and whether or not non-epidemic runs are excluded from analyses. Given that there is no concrete quantitative definition of what constitutes an epidemic within the public health literature, each modeler must decide on a strategy for identifying epidemics during simulation runs. Here, an SEIR model was used to test the effects of how varying the cutoff for considering a run an epidemic changes potential interpretations of simulation outcomes. Varying the cutoff from 0% to 15% of the model population ever infected with the illness generated significant differences in numbers of dead and timing variables. These results are important for those who use models to form public health policy, in which questions of timing or implementation of interventions might be answered using findings from computer simulation models.

Heterogeneous network epidemics: real-time growth, variance and extinction of infection.

Science.gov (United States)

Ball, Frank; House, Thomas

2017-09-01

Recent years have seen a large amount of interest in epidemics on networks as a way of representing the complex structure of contacts capable of spreading infections through the modern human population. The configuration model is a popular choice in theoretical studies since it combines the ability to specify the distribution of the number of contacts (degree) with analytical tractability. Here we consider the early real-time behaviour of the Markovian SIR epidemic model on a configuration model network using a multitype branching process. We find closed-form analytic expressions for the mean and variance of the number of infectious individuals as a function of time and the degree of the initially infected individual(s), and write down a system of differential equations for the probability of extinction by time t that are numerically fast compared to Monte Carlo simulation. We show that these quantities are all sensitive to the degree distribution-in particular we confirm that the mean prevalence of infection depends on the first two moments of the degree distribution and the variance in prevalence depends on the first three moments of the degree distribution. In contrast to most existing analytic approaches, the accuracy of these results does not depend on having a large number of infectious individuals, meaning that in the large population limit they would be asymptotically exact even for one initial infectious individual.

The spatiotemporal trajectory of a dengue epidemic in a medium-sized city

Directory of Open Access Journals (Sweden)

Daniela G Morato

2015-06-01

Full Text Available Understanding the transmission dynamics of infectious diseases is important to allow for improvements of control measures. To investigate the spatiotemporal pattern of an epidemic dengue occurred at a medium-sized city in the Northeast Region of Brazil in 2009, we conducted an ecological study of the notified dengue cases georeferenced according to epidemiological week (EW and home address. Kernel density estimation and space-time interaction were analysed using the Knox method. The evolution of the epidemic was analysed using an animated projection technique. The dengue incidence was 6.918.7/100,000 inhabitants; the peak of the epidemic occurred from 8 February-1 March, EWs 6-9 (828.7/100,000 inhabitants. There were cases throughout the city and was identified space-time interaction. Three epicenters were responsible for spreading the disease in an expansion and relocation diffusion pattern. If the health services could detect in real time the epicenters and apply nimbly control measures, may possibly reduce the magnitude of dengue epidemics.

Double burden of noncommunicable and infectious diseases in developing countries

DEFF Research Database (Denmark)

Bygbjerg, I C

2012-01-01

On top of the unfinished agenda of infectious diseases in low- and middle-income countries, development, industrialization, urbanization, investment, and aging are drivers of an epidemic of noncommunicable diseases (NCDs). Malnutrition and infection in early life increase the risk of chronic NCDs...... for limited funds, is an important policy consideration requiring new thinking and approaches....

Gastrointestinal infections in children.

Science.gov (United States)

Mönkemüller, K E; Wilcox, C M

2001-01-01

Gastrointestinal infections in children are a major cause of morbidity and mortality worldwide. Children living in developing countries are particularly susceptible to infectious diarrhea because of poor standards of hygiene and sanitation. Although the magnitude of diarrheal illnesses in developed countries is less, costly hospital admissions are still frequent. The causal agent of infectious diarrhea is most frequently related to age, geographical location, lifestyle habits, use of antibiotics, associated medical conditions, social circumstances, and degree of immune competence. In this article we present some of the most important articles published in the field during the last year. The role of Helicobacter pylori in the pathogenesis of gastritis and peptic ulcer disease has been shown in adults and children. Information about the natural history of H. pylori, symptomatology, and diagnostic therapeutic approaches for children are being generated constantly; we discuss some of the most relevant information in this review.

Surveillance of gastrointestinal disease in France using drug sales data.

Science.gov (United States)

Pivette, Mathilde; Mueller, Judith E; Crépey, Pascal; Bar-Hen, Avner

2014-09-01

Drug sales data have increasingly been used for disease surveillance during recent years. Our objective was to assess the value of drug sales data as an operational early detection tool for gastroenteritis epidemics at national and regional level in France. For the period 2008-2013, we compared temporal trends of drug sales for the treatment of gastroenteritis with trends of cases reported by a Sentinel Network of general practitioners. We benchmarked detection models to select the one with the best sensitivity, false alert proportion and timeliness, and developed a prospective framework to assess the operational performance of the system. Drug sales data allowed the detection of seasonal gastrointestinal epidemics occurring in winter with a distinction between prescribed and non-prescribed drugs. Sales of non-prescribed drugs allowed epidemic detection on average 2.25 weeks earlier than Sentinel data. These results confirm the value of drug sales data for real-time monitoring of gastroenteritis epidemic activity. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

[Epizootic and epidemic manifestation of natural foci of tularemia in Moscow region (1965-2013)].

Science.gov (United States)

Demidova, T N; Popov, V P; Polukhina, A N; Orlov, D S; Mescheryakova, I S; Mikhailova, T V

2015-01-01

Detection of contemporary features of tularemia focimanifestations, determination of territories of high epidemic risk in various landscape zones and creation of a map of foci territories of Moscow Region for isolation of tularemia infectious agent cultures and registered human morbidity for justified planning of prophylaxis measures. Report materials of epizootologic examinations of natural foci for 1965-2013, 156 maps of epidemiologic examination of cases of human infection with tularemia, results of studies of casting of predatory birds and dung of predatory mammals were used. Registered morbidity and isolation of tularemia infectious agent cultures from 1965 to date were applied to an electronic map of Moscow Region by sign method using modern. GIS-technologies (MapInfo 10.5 program). Electronic maps Ingit at 1:200,000 scale, as well as Google Earth program were used to search for base points. Analysis of morbidity has revealed structure change in human tularemia morbidity--an increase of the fraction of urban population and a decrease of the fraction of patients among rural inhabitants, unimmunized against this infection are mostly ill. The presence of DNA of tularemia causative agent in biological objects in the complex with serologic and bacteriological studies was shown to allow to detect flaccid epizootics even at low numbers of rodents. Cartographic reflection of registered morbidity and isolation of tularemia infectious agent cultures allowed to show territories with various degrees of epizootic activity and epidemic manifestation. Positive results of serologic and molecular-genetic studies of environmental objects gives evident on epizootic activity and constant risk of aggravation of epidemic situation for this infection.

epiDMS: Data Management and Analytics for Decision-Making From Epidemic Spread Simulation Ensembles.

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Liu, Sicong; Poccia, Silvestro; Candan, K Selçuk; Chowell, Gerardo; Sapino, Maria Luisa

2016-12-01

Carefully calibrated large-scale computational models of epidemic spread represent a powerful tool to support the decision-making process during epidemic emergencies. Epidemic models are being increasingly used for generating forecasts of the spatial-temporal progression of epidemics at different spatial scales and for assessing the likely impact of different intervention strategies. However, the management and analysis of simulation ensembles stemming from large-scale computational models pose challenges, particularly when dealing with multiple interdependent parameters, spanning multiple layers and geospatial frames, affected by complex dynamic processes operating at different resolutions. We describe and illustrate with examples a novel epidemic simulation data management system, epiDMS, that was developed to address the challenges that arise from the need to generate, search, visualize, and analyze, in a scalable manner, large volumes of epidemic simulation ensembles and observations during the progression of an epidemic. epiDMS is a publicly available system that facilitates management and analysis of large epidemic simulation ensembles. epiDMS aims to fill an important hole in decision-making during healthcare emergencies by enabling critical services with significant economic and health impact. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Rabies epidemic model with uncertainty in parameters: crisp and fuzzy approaches

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Ndii, M. Z.; Amarti, Z.; Wiraningsih, E. D.; Supriatna, A. K.

2018-03-01

A deterministic mathematical model is formulated to investigate the transmission dynamics of rabies. In particular, we investigate the effects of vaccination, carrying capacity and the transmission rate on the rabies epidemics and allow for uncertainty in the parameters. We perform crisp and fuzzy approaches. We find that, in the case of crisp parameters, rabies epidemics may be interrupted when the carrying capacity and the transmission rate are not high. Our findings suggest that limiting the growth of dog population and reducing the potential contact between susceptible and infectious dogs may aid in interrupting rabies epidemics. We extend the work by considering a fuzzy carrying capacity and allow for low, medium, and high level of carrying capacity. The result confirms the results obtained by using crisp carrying capacity, that is, when the carrying capacity is not too high, the vaccination could confine the disease effectively.

Dynamics of cholera epidemics with impulsive vaccination and disinfection.

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Sisodiya, Omprakash Singh; Misra, O P; Dhar, Joydip

2018-04-01

Waterborne diseases have a tremendous influence on human life. The contaminated drinking water causes water-borne disease like cholera. Pulse vaccination is an important and effective strategy for the elimination of infectious diseases. A waterborne disease like cholera can also be controlled by using impulse technique. In this paper, we have proposed a delayed SEIRB epidemic model with impulsive vaccination and disinfection. We have studied the pulse vaccination strategy and sanitation to control the cholera disease. The existence and stability of the disease-free and endemic periodic solution are investigated both analytically and numerically. It is shown that there exists an infection-free periodic solution, using the impulsive dynamical system defined by the stroboscopic map. It is observed that the infection-free periodic solution is globally attractive when the impulse period is less than some critical value. From the analysis of the model, we have obtained a sufficient condition for the permanence of the epidemic with pulse vaccination. The main highlight of this paper is to introduce impulse technique along with latent period into the SEIRB epidemic model to investigate the role of pulse vaccination and disinfection on the dynamics of the cholera epidemics. Copyright © 2018 Elsevier Inc. All rights reserved.

Planning horizon affects prophylactic decision-making and epidemic dynamics.

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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.

Bayesian inference in an extended SEIR model with nonparametric disease transmission rate: an application to the Ebola epidemic in Sierra Leone.

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Frasso, Gianluca; Lambert, Philippe

2016-10-01

SummaryThe 2014 Ebola outbreak in Sierra Leone is analyzed using a susceptible-exposed-infectious-removed (SEIR) epidemic compartmental model. The discrete time-stochastic model for the epidemic evolution is coupled to a set of ordinary differential equations describing the dynamics of the expected proportions of subjects in each epidemic state. The unknown parameters are estimated in a Bayesian framework by combining data on the number of new (laboratory confirmed) Ebola cases reported by the Ministry of Health and prior distributions for the transition rates elicited using information collected by the WHO during the follow-up of specific Ebola cases. The time-varying disease transmission rate is modeled in a flexible way using penalized B-splines. Our framework represents a valuable stochastic tool for the study of an epidemic dynamic even when only irregularly observed and possibly aggregated data are available. Simulations and the analysis of the 2014 Sierra Leone Ebola data highlight the merits of the proposed methodology. In particular, the flexible modeling of the disease transmission rate makes the estimation of the effective reproduction number robust to the misspecification of the initial epidemic states and to underreporting of the infectious cases. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Impacts of clustering on interacting epidemics.

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Wang, Bing; Cao, Lang; Suzuki, Hideyuki; Aihara, Kazuyuki

2012-07-07

Since community structures in real networks play a major role for the epidemic spread, we therefore explore two interacting diseases spreading in networks with community structures. As a network model with community structures, we propose a random clique network model composed of different orders of cliques. We further assume that each disease spreads only through one type of cliques; this assumption corresponds to the issue that two diseases spread inside communities and outside them. Considering the relationship between the susceptible-infected-recovered (SIR) model and the bond percolation theory, we apply this theory to clique random networks under the assumption that the occupation probability is clique-type dependent, which is consistent with the observation that infection rates inside a community and outside it are different, and obtain a number of statistical properties for this model. Two interacting diseases that compete the same hosts are also investigated, which leads to a natural generalization of analyzing an arbitrary number of infectious diseases. For two-disease dynamics, the clustering effect is hypersensitive to the cohesiveness and concentration of cliques; this illustrates the impacts of clustering and the composition of subgraphs in networks on epidemic behavior. The analysis of coexistence/bistability regions provides significant insight into the relationship between the network structure and the potential epidemic prevalence. Copyright © 2012 Elsevier Ltd. All rights reserved.

Scale-dependent climatic drivers of human epidemics in ancient China

Czech Academy of Sciences Publication Activity Database

Tian, H.; Yan, Ch.; Xu, L.; Büntgen, Ulf; Stenseth, N. C.; Zhang, Z.

2017-01-01

Roč. 114, č. 49 (2017), s. 12970-12975 ISSN 0027-8424 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : infectious-diseases * northern-hemisphere * cholera dynamics * time-series * 2 millennia * reconstruction * variability * management * plague * ad * epidemics * climate * scale dependent * natural disaster * disease Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 9.661, year: 2016

Spatial spreading of infectious disease via local and national mobility networks in South Korea

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Kwon, Okyu; Son, Woo-Sik

2017-12-01

We study the spread of infectious disease based on local- and national-scale mobility networks. We construct a local mobility network using data on urban bus services to estimate local-scale movement of people. We also construct a national mobility network from orientation-destination data of vehicular traffic between highway tollgates to evaluate national-scale movement of people. A metapopulation model is used to simulate the spread of epidemics. Thus, the number of infected people is simulated using a susceptible-infectious-recovered (SIR) model within the administrative division, and inter-division spread of infected people is determined through local and national mobility networks. In this paper, we consider two scenarios for epidemic spread. In the first, the infectious disease only spreads through local-scale movement of people, that is, the local mobility network. In the second, it spreads via both local and national mobility networks. For the former, the simulation results show infected people sequentially spread to neighboring divisions. Yet for the latter, we observe a faster spreading pattern to distant divisions. Thus, we confirm the national mobility network enhances synchronization among the incidence profiles of all administrative divisions.

A Meta-Analysis of the Association between Gender and Protective Behaviors in Response to Respiratory Epidemics and Pandemics.

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Moran, Kelly R; Del Valle, Sara Y

2016-01-01

Respiratory infectious disease epidemics and pandemics are recurring events that levy a high cost on individuals and society. The health-protective behavioral response of the public plays an important role in limiting respiratory infectious disease spread. Health-protective behaviors take several forms. Behaviors can be categorized as pharmaceutical (e.g., vaccination uptake, antiviral use) or non-pharmaceutical (e.g., hand washing, face mask use, avoidance of public transport). Due to the limitations of pharmaceutical interventions during respiratory epidemics and pandemics, public health campaigns aimed at limiting disease spread often emphasize both non-pharmaceutical and pharmaceutical behavioral interventions. Understanding the determinants of the public's behavioral response is crucial for devising public health campaigns, providing information to parametrize mathematical models, and ultimately limiting disease spread. While other reviews have qualitatively analyzed the body of work on demographic determinants of health-protective behavior, this meta-analysis quantitatively combines the results from 85 publications to determine the global relationship between gender and health-protective behavioral response. The results show that women in the general population are about 50% more likely than men to adopt/practice non-pharmaceutical behaviors. Conversely, men in the general population are marginally (about 12%) more likely than women to adopt/practice pharmaceutical behaviors. It is possible that factors other than pharmaceutical/non-pharmaceutical status not included in this analysis act as moderators of this relationship. These results suggest an inherent difference in how men and women respond to epidemic and pandemic respiratory infectious diseases. This information can be used to target specific groups when developing non-pharmaceutical public health campaigns and to parameterize epidemic models incorporating demographic information.

A Meta-Analysis of the Association between Gender and Protective Behaviors in Response to Respiratory Epidemics and Pandemics.

Directory of Open Access Journals (Sweden)

Kelly R Moran

Full Text Available Respiratory infectious disease epidemics and pandemics are recurring events that levy a high cost on individuals and society. The health-protective behavioral response of the public plays an important role in limiting respiratory infectious disease spread. Health-protective behaviors take several forms. Behaviors can be categorized as pharmaceutical (e.g., vaccination uptake, antiviral use or non-pharmaceutical (e.g., hand washing, face mask use, avoidance of public transport. Due to the limitations of pharmaceutical interventions during respiratory epidemics and pandemics, public health campaigns aimed at limiting disease spread often emphasize both non-pharmaceutical and pharmaceutical behavioral interventions. Understanding the determinants of the public's behavioral response is crucial for devising public health campaigns, providing information to parametrize mathematical models, and ultimately limiting disease spread. While other reviews have qualitatively analyzed the body of work on demographic determinants of health-protective behavior, this meta-analysis quantitatively combines the results from 85 publications to determine the global relationship between gender and health-protective behavioral response. The results show that women in the general population are about 50% more likely than men to adopt/practice non-pharmaceutical behaviors. Conversely, men in the general population are marginally (about 12% more likely than women to adopt/practice pharmaceutical behaviors. It is possible that factors other than pharmaceutical/non-pharmaceutical status not included in this analysis act as moderators of this relationship. These results suggest an inherent difference in how men and women respond to epidemic and pandemic respiratory infectious diseases. This information can be used to target specific groups when developing non-pharmaceutical public health campaigns and to parameterize epidemic models incorporating demographic information.

Theoretical basis to measure the impact of short-lasting control of an infectious disease on the epidemic peak

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Omori Ryosuke

2011-01-01

Full Text Available Abstract Background While many pandemic preparedness plans have promoted disease control effort to lower and delay an epidemic peak, analytical methods for determining the required control effort and making statistical inferences have yet to be sought. As a first step to address this issue, we present a theoretical basis on which to assess the impact of an early intervention on the epidemic peak, employing a simple epidemic model. Methods We focus on estimating the impact of an early control effort (e.g. unsuccessful containment, assuming that the transmission rate abruptly increases when control is discontinued. We provide analytical expressions for magnitude and time of the epidemic peak, employing approximate logistic and logarithmic-form solutions for the latter. Empirical influenza data (H1N1-2009 in Japan are analyzed to estimate the effect of the summer holiday period in lowering and delaying the peak in 2009. Results Our model estimates that the epidemic peak of the 2009 pandemic was delayed for 21 days due to summer holiday. Decline in peak appears to be a nonlinear function of control-associated reduction in the reproduction number. Peak delay is shown to critically depend on the fraction of initially immune individuals. Conclusions The proposed modeling approaches offer methodological avenues to assess empirical data and to objectively estimate required control effort to lower and delay an epidemic peak. Analytical findings support a critical need to conduct population-wide serological survey as a prior requirement for estimating the time of peak.

Association of Drought with Typhus Epidemics in Central Mexico

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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 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.

FluTE, a publicly available stochastic influenza epidemic simulation model.

Directory of Open Access Journals (Sweden)

Dennis L Chao

2010-01-01

Full Text Available Mathematical and computer models of epidemics have contributed to our understanding of the spread of infectious disease and the measures needed to contain or mitigate them. To help prepare for future influenza seasonal epidemics or pandemics, we developed a new stochastic model of the spread of influenza across a large population. Individuals in this model have realistic social contact networks, and transmission and infections are based on the current state of knowledge of the natural history of influenza. The model has been calibrated so that outcomes are consistent with the 1957/1958 Asian A(H2N2 and 2009 pandemic A(H1N1 influenza viruses. We present examples of how this model can be used to study the dynamics of influenza epidemics in the United States and simulate how to mitigate or delay them using pharmaceutical interventions and social distancing measures. Computer simulation models play an essential role in informing public policy and evaluating pandemic preparedness plans. We have made the source code of this model publicly available to encourage its use and further development.

FluTE, a publicly available stochastic influenza epidemic simulation model.

Science.gov (United States)

Chao, Dennis L; Halloran, M Elizabeth; Obenchain, Valerie J; Longini, Ira M

2010-01-29

Mathematical and computer models of epidemics have contributed to our understanding of the spread of infectious disease and the measures needed to contain or mitigate them. To help prepare for future influenza seasonal epidemics or pandemics, we developed a new stochastic model of the spread of influenza across a large population. Individuals in this model have realistic social contact networks, and transmission and infections are based on the current state of knowledge of the natural history of influenza. The model has been calibrated so that outcomes are consistent with the 1957/1958 Asian A(H2N2) and 2009 pandemic A(H1N1) influenza viruses. We present examples of how this model can be used to study the dynamics of influenza epidemics in the United States and simulate how to mitigate or delay them using pharmaceutical interventions and social distancing measures. Computer simulation models play an essential role in informing public policy and evaluating pandemic preparedness plans. We have made the source code of this model publicly available to encourage its use and further development.

Epidemic assistance by the Centers for Disease Control and Prevention: role of the Epidemic Intelligence Service, 1946-2005.

Science.gov (United States)

Thacker, Stephen B; Stroup, Donna F; Sencer, David J

2011-12-01

Since 1946, the Centers for Disease Control and Prevention has responded to urgent requests from US states, federal agencies, and international organizations through epidemic-assistance investigations (Epi-Aids). The authors describe the first 60 years of Epi-Aids, breadth of problems addressed, evolution of methodologies, scope of activities, and impact of investigations on population health. They reviewed Epi-Aid reports and EIS Bulletins, contacted current and former Epidemic Intelligence Service staff, and systematically searched the PubMed and Web of Science databases. They abstracted information on dates, location, staff involved, health problems, methods, and impacts of investigations according to a preplanned protocol. They assessed the methods presented as well as the quality of reports. During 1946-2005, a total of 4,484 investigations of health events were initiated by 2,815 Epidemic Intelligence Service officers. In the early years, the majority were in response to infectious agents, although environmental problems emerged. Investigations in subsequent years focused on occupational conditions, birth defects, reproductive health, tobacco use, cancer, violence, legal debate, and terrorism. These Epi-Aids heralded expansion of the agency's mission and presented new methods in statistics and epidemiology. Recommendations from Epi-Aids led to policy implementation, evaluation, or modification. Epi-Aids provide the Centers for Disease Control and Prevention with the agility to respond rapidly to public health crises.

GRAPHICAL USER INTERFACE WITH APPLICATIONS IN SUSCEPTIBLE-INFECTIOUS-SUSCEPTIBLE MODELS.

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Ilea, M; Turnea, M; Arotăriţei, D; Rotariu, Mariana; Popescu, Marilena

2015-01-01

Practical significance of understanding the dynamics and evolution of infectious diseases increases continuously in contemporary world. The mathematical study of the dynamics of infectious diseases has a long history. By incorporating statistical methods and computer-based simulations in dynamic epidemiological models, it could be possible for modeling methods and theoretical analyses to be more realistic and reliable, allowing a more detailed understanding of the rules governing epidemic spreading. To provide the basis for a disease transmission, the population of a region is often divided into various compartments, and the model governing their relation is called the compartmental model. To present all of the information available, a graphical user interface provides icons and visual indicators. The graphical interface shown in this paper is performed using the MATLAB software ver. 7.6.0. MATLAB software offers a wide range of techniques by which data can be displayed graphically. The process of data viewing involves a series of operations. To achieve it, I had to make three separate files, one for defining the mathematical model and two for the interface itself. Considering a fixed population, it is observed that the number of susceptible individuals diminishes along with an increase in the number of infectious individuals so that in about ten days the number of individuals infected and susceptible, respectively, has the same value. If the epidemic is not controlled, it will continue for an indefinite period of time. By changing the global parameters specific of the SIS model, a more rapid increase of infectious individuals is noted. Using the graphical user interface shown in this paper helps achieving a much easier interaction with the computer, simplifying the structure of complex instructions by using icons and menus, and, in particular, programs and files are much easier to organize. Some numerical simulations have been presented to illustrate theoretical

Virulence evolution at the front line of spreading epidemics.

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Griette, Quentin; Raoul, Gaël; Gandon, Sylvain

2015-11-01

Understanding and predicting the spatial spread of emerging pathogens is a major challenge for the public health management of infectious diseases. Theoretical epidemiology shows that the speed of an epidemic is governed by the life-history characteristics of the pathogen and its ability to disperse. Rapid evolution of these traits during the invasion may thus affect the speed of epidemics. Here we study the influence of virulence evolution on the spatial spread of an epidemic. At the edge of the invasion front, we show that more virulent and transmissible genotypes are expected to win the competition with other pathogens. Behind the front line, however, more prudent exploitation strategies outcompete virulent pathogens. Crucially, even when the presence of the virulent mutant is limited to the edge of the front, the invasion speed can be dramatically altered by pathogen evolution. We support our analysis with individual-based simulations and we discuss the additional effects of demographic stochasticity taking place at the front line on virulence evolution. We confirm that an increase of virulence can occur at the front, but only if the carrying capacity of the invading pathogen is large enough. These results are discussed in the light of recent empirical studies examining virulence evolution at the edge of spreading epidemics. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Probiotics for Gastrointestinal Conditions: A Summary of the Evidence.

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Wilkins, Thad; Sequoia, Jacqueline

2017-08-01

Probiotics contain microorganisms, most of which are bacteria similar to the beneficial bacteria that occur naturally in the human gut. Probiotics have been widely studied in a variety of gastrointestinal diseases. The most-studied species include Lactobacillus, Bifidobacterium, and Saccharomyces. However, a lack of clear guidelines on when to use probiotics and the most effective probiotic for different gastrointestinal conditions may be confusing for family physicians and their patients. Probiotics have an important role in the maintenance of immunologic equilibrium in the gastrointestinal tract through the direct interaction with immune cells. Probiotic effectiveness can be species-, dose-, and disease-specific, and the duration of therapy depends on the clinical indication. There is high-quality evidence that probiotics are effective for acute infectious diarrhea, antibiotic-associated diarrhea, Clostridium difficile- associated diarrhea, hepatic encephalopathy, ulcerative colitis, irritable bowel syndrome, functional gastrointestinal disorders, and necrotizing enterocolitis. Conversely, there is evidence that probiotics are not effective for acute pancreatitis and Crohn disease. Probiotics are safe for infants, children, adults, and older patients, but caution is advised in immunologically vulnerable populations.

NOD2/CARD15 genotype and common gastrointestinal diseases in 43 600 individuals

DEFF Research Database (Denmark)

Yazdanyar, S.; Nordestgaard, B.G.

2010-01-01

heterozygotes. Cumulative incidences differed by genotype for appendicitis (log-rank P = 0.02), anal fissure, fistula and abscess (P = 0.003) and gastrointestinal cancer (P = 0.004), but not for any of the other endpoints. Compared with non-carriers, age and sex adjusted hazard ratios were 2.7 (95% CI 1...... appendicitis, 646 irritable bowel syndrome, 1301 infectious diseases of the gastrointestinal tract, 681 anal fissure, fistula and abscess, 826 gastrointestinal cancer and 161 developed cancer in liver and pancreas. Results. Some 89% were non-carriers, 11% heterozygotes, 0.15% homozygotes and 0.23% compound.......4-5.5) for appendicitis amongst compound heterozygotes, 3.2 (1.3-7.8) for anal fissure, fistula and abscess amongst compound heterozygotes, and 3.8 (1.6-9.2) for gastrointestinal cancer amongst homozygotes, whilst other genotypes did not have increased risk. The increased risk of gastrointestinal cancer amongst...

NOD2/CARD15 genotype and common gastrointestinal diseases in 43 600 individuals

DEFF Research Database (Denmark)

Yazdanyar, S.; Nordestgaard, B.G.

2010-01-01

appendicitis, 646 irritable bowel syndrome, 1301 infectious diseases of the gastrointestinal tract, 681 anal fissure, fistula and abscess, 826 gastrointestinal cancer and 161 developed cancer in liver and pancreas. Results. Some 89% were non-carriers, 11% heterozygotes, 0.15% homozygotes and 0.23% compound...... heterozygotes. Cumulative incidences differed by genotype for appendicitis (log-rank P = 0.02), anal fissure, fistula and abscess (P = 0.003) and gastrointestinal cancer (P = 0.004), but not for any of the other endpoints. Compared with non-carriers, age and sex adjusted hazard ratios were 2.7 (95% CI 1.......4-5.5) for appendicitis amongst compound heterozygotes, 3.2 (1.3-7.8) for anal fissure, fistula and abscess amongst compound heterozygotes, and 3.8 (1.6-9.2) for gastrointestinal cancer amongst homozygotes, whilst other genotypes did not have increased risk. The increased risk of gastrointestinal cancer amongst...

Parameterizing Spatial Models of Infectious Disease Transmission that Incorporate Infection Time Uncertainty Using Sampling-Based Likelihood Approximations.

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Rajat Malik

Full Text Available A class of discrete-time models of infectious disease spread, referred to as individual-level models (ILMs, are typically fitted in a Bayesian Markov chain Monte Carlo (MCMC framework. These models quantify probabilistic outcomes regarding the risk of infection of susceptible individuals due to various susceptibility and transmissibility factors, including their spatial distance from infectious individuals. The infectious pressure from infected individuals exerted on susceptible individuals is intrinsic to these ILMs. Unfortunately, quantifying this infectious pressure for data sets containing many individuals can be computationally burdensome, leading to a time-consuming likelihood calculation and, thus, computationally prohibitive MCMC-based analysis. This problem worsens when using data augmentation to allow for uncertainty in infection times. In this paper, we develop sampling methods that can be used to calculate a fast, approximate likelihood when fitting such disease models. A simple random sampling approach is initially considered followed by various spatially-stratified schemes. We test and compare the performance of our methods with both simulated data and data from the 2001 foot-and-mouth disease (FMD epidemic in the U.K. Our results indicate that substantial computation savings can be obtained--albeit, of course, with some information loss--suggesting that such techniques may be of use in the analysis of very large epidemic data sets.

On the Use of Human Mobility Proxies for Modeling Epidemics

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Tizzoni, Michele; Bajardi, Paolo; Decuyper, Adeline; Kon Kam King, Guillaume; Schneider, Christian M.; Blondel, Vincent; Smoreda, Zbigniew; González, Marta C.; Colizza, Vittoria

2014-01-01

Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i) official census surveys, (ii) proxy mobility data extracted from mobile phone call records, and (iii) the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies should therefore be

Epidemic Cholera and American Reform Movements in the 19th Century

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Seohyung KIM

2015-12-01

Full Text Available The 19th century was the age of great reform in American history. After constructing of the canal and railroads, the industrialization began and American society changed so rapidly. In this period, there were so many social crisis and American people tried to solve these problems within the several reform movements. These reform movements were the driving forces to control cholera during the 19th century. Cholera was the endemic disease in Bengal, India, but after the 19th century it had spread globally by the development of trade networks. The 1832 cholera in the United States was the first epidemic cholera in American history. The mortality of cholera was so high, but it was very hard to find out the cause of this fatal infectious disease. So, different social discourses happened to control epidemic cholera in the 19th century, these can be understood within the similar context of American reform movements during this period. Board of Health in New York States made a new public health act to control cholera in 1832, it was ineffective. Some people insisted that the cause of this infectious disease was the corruption of the United States. They emphasized unjust and immoral system in American society. Moral reform expanded to Nativism, because lots of Irish immigrants were the victims of cholera. So, epidemic cholera was the opportunity to spread the desire for moral reform. To control cholera in 1849, the sanitary reform in Britain had affected. The fact that it was so important to improve and maintain the water quality for the control and prevention of disease spread, the sanitary reform happened. There were two different sphere of the sanitary reform. The former was the private reform to improve sewer or privy, the latter was the public reform to build sewage facilities. The 1849 cholera had an important meaning, because the social discourse, which had emphasized the sanitation of people or home expanded to the public sphere. When cholera

[Epidemic Cholera and American Reform Movements in the 19th Century].

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Kim, Seohyung

2015-12-01

The 19th century was the age of great reform in American history. After constructing of the canal and railroads, the industrialization began and American society changed so rapidly. In this period, there were so many social crisis and American people tried to solve these problems within the several reform movements. These reform movements were the driving forces to control cholera during the 19th century. Cholera was the endemic disease in Bengal, India, but after the 19th century it had spread globally by the development of trade networks. The 1832 cholera in the United States was the first epidemic cholera in American history. The mortality of cholera was so high, but it was very hard to find out the cause of this fatal infectious disease. So, different social discourses happened to control epidemic cholera in the 19th century, these can be understood within the similar context of American reform movements during this period. Board of Health in New York States made a new public health act to control cholera in 1832, it was ineffective. Some people insisted that the cause of this infectious disease was the corruption of the United States. They emphasized unjust and immoral system in American society. Moral reform expanded to Nativism, because lots of Irish immigrants were the victims of cholera. So, epidemic cholera was the opportunity to spread the desire for moral reform. To control cholera in 1849, the sanitary reform in Britain had affected. The fact that it was so important to improve and maintain the water quality for the control and prevention of disease spread, the sanitary reform happened. There were two different sphere of the sanitary reform. The former was the private reform to improve sewer or privy, the latter was the public reform to build sewage facilities. The 1849 cholera had an important meaning, because the social discourse, which had emphasized the sanitation of people or home expanded to the public sphere. When cholera broke out in 1866 again

Developing stochastic epidemiological models to quantify the dynamics of infectious diseases in domestic livestock.

Science.gov (United States)

MacKenzie, K; Bishop, S C

2001-08-01

A stochastic model describing disease transmission dynamics for a microparasitic infection in a structured domestic animal population is developed and applied to hypothetical epidemics on a pig farm. Rational decision making regarding appropriate control strategies for infectious diseases in domestic livestock requires an understanding of the disease dynamics and risk profiles for different groups of animals. This is best achieved by means of stochastic epidemic models. Methodologies are presented for 1) estimating the probability of an epidemic, given the presence of an infected animal, whether this epidemic is major (requires intervention) or minor (dies out without intervention), and how the location of the infected animal on the farm influences the epidemic probabilities; 2) estimating the basic reproductive ratio, R0 (i.e., the expected number of secondary cases on the introduction of a single infected animal) and the variability of the estimate of this parameter; and 3) estimating the total proportion of animals infected during an epidemic and the total proportion infected at any point in time. The model can be used for assessing impact of altering farm structure on disease dynamics, as well as disease control strategies, including altering farm structure, vaccination, culling, and genetic selection.

Discrete stochastic analogs of Erlang epidemic models.

Science.gov (United States)

Getz, Wayne M; Dougherty, Eric R

2018-12-01

Erlang differential equation models of epidemic processes provide more realistic disease-class transition dynamics from susceptible (S) to exposed (E) to infectious (I) and removed (R) categories than the ubiquitous SEIR model. The latter is itself is at one end of the spectrum of Erlang SE[Formula: see text]I[Formula: see text]R models with [Formula: see text] concatenated E compartments and [Formula: see text] concatenated I compartments. Discrete-time models, however, are computationally much simpler to simulate and fit to epidemic outbreak data than continuous-time differential equations, and are also much more readily extended to include demographic and other types of stochasticity. Here we formulate discrete-time deterministic analogs of the Erlang models, and their stochastic extension, based on a time-to-go distributional principle. Depending on which distributions are used (e.g. discretized Erlang, Gamma, Beta, or Uniform distributions), we demonstrate that our formulation represents both a discretization of Erlang epidemic models and generalizations thereof. We consider the challenges of fitting SE[Formula: see text]I[Formula: see text]R models and our discrete-time analog to data (the recent outbreak of Ebola in Liberia). We demonstrate that the latter performs much better than the former; although confining fits to strict SEIR formulations reduces the numerical challenges, but sacrifices best-fit likelihood scores by at least 7%.

Route prediction model of infectious diseases for 2018 Winter Olympics in Korea

International Nuclear Information System (INIS)

Kim, Eungyeong; Lee, Seok; Byun, Young Tae; Kim, Jae Hun; Lee, Taikjin; Lee, Hyuk-jae

2014-01-01

There are many types of respiratory infectious diseases caused by germs, virus, mycetes and parasites. Researchers recently have tried to develop mathematical models to predict the epidemic of infectious diseases. However, with the development of ground transportation system in modern society, the spread of infectious diseases became faster and more complicated in terms of the speed and the pathways. The route of infectious diseases during Vancouver Olympics was predicted based on the Susceptible-Infectious-Recovered (SIR) model. In this model only the air traffic as an essential factor for the intercity migration of infectious diseases was involved. Here, we propose a multi-city transmission model to predict the infection route during 2018 Winter Olympics in Korea based on the pre-existing SIR model. Various types of transportation system such as a train, a car, a bus, and an airplane for the interpersonal contact in both inter- and intra-city are considered. Simulation is performed with assumptions and scenarios based on realistic factors including demographic, transportation and diseases data in Korea. Finally, we analyze an economic profit and loss caused by the variation of the number of tourists during the Olympics

Route prediction model of infectious diseases for 2018 Winter Olympics in Korea

Science.gov (United States)

Kim, Eungyeong; Lee, Seok; Byun, Young Tae; Kim, Jae Hun; Lee, Hyuk-jae; Lee, Taikjin

2014-03-01

There are many types of respiratory infectious diseases caused by germs, virus, mycetes and parasites. Researchers recently have tried to develop mathematical models to predict the epidemic of infectious diseases. However, with the development of ground transportation system in modern society, the spread of infectious diseases became faster and more complicated in terms of the speed and the pathways. The route of infectious diseases during Vancouver Olympics was predicted based on the Susceptible-Infectious-Recovered (SIR) model. In this model only the air traffic as an essential factor for the intercity migration of infectious diseases was involved. Here, we propose a multi-city transmission model to predict the infection route during 2018 Winter Olympics in Korea based on the pre-existing SIR model. Various types of transportation system such as a train, a car, a bus, and an airplane for the interpersonal contact in both inter- and intra-city are considered. Simulation is performed with assumptions and scenarios based on realistic factors including demographic, transportation and diseases data in Korea. Finally, we analyze an economic profit and loss caused by the variation of the number of tourists during the Olympics.

Epidemiological monitoring for emerging infectious diseases

Science.gov (United States)

Greene, Marjorie

2010-04-01

The Homeland Security News Wire has been reporting on new ways to fight epidemics using digital tools such as iPhone, social networks, Wikipedia, and other Internet sites. Instant two-way communication now gives consumers the ability to complement official reports on emerging infectious diseases from health authorities. However, there is increasing concern that these communications networks could open the door to mass panic from unreliable or false reports. There is thus an urgent need to ensure that epidemiological monitoring for emerging infectious diseases gives health authorities the capability to identify, analyze, and report disease outbreaks in as timely and efficient a manner as possible. One of the dilemmas in the global dissemination of information on infectious diseases is the possibility that information overload will create inefficiencies as the volume of Internet-based surveillance information increases. What is needed is a filtering mechanism that will retrieve relevant information for further analysis by epidemiologists, laboratories, and other health organizations so they are not overwhelmed with irrelevant information and will be able to respond quickly. This paper introduces a self-organizing ontology that could be used as a filtering mechanism to increase relevance and allow rapid analysis of disease outbreaks as they evolve in real time.

Addressing Future Epidemics: Historical Human Rights Lessons from the AIDS Pandemic

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Ambar Mehta

2016-05-01

Full Text Available Introduction: The Ebola epidemic in West Africa sparked many ethical and polarizing public health questions on how to adequately control transmission of the virus. These deliberations had and will continue to influence patients, healthcare workers, public perceptions of disease, and governmental responses. Such extensive and potential ramifications warranted an analysis of prior epidemics to sufficiently inform policy makers and prepare them and other authorities for future epidemics. We analyzed how the general public, medical institutions, federal government, and patients themselves responded during the early stages of the AIDS pandemic in two different countries and cultures, the United States and India. Discussion: Our analysis identified four key findings pertaining to the human rights of patients and healthcare workers and to the crucial roles of the government and medical community. The first demands that authoritative officials acknowledge the presence of high-risk behaviors and properly educate the public without stigmatizing groups of individuals. For this task, the medical community and federal government must form and display to the public a respectful and collaborative partnership towards battling the epidemic. These two synergistic endeavors will then allow appropriate officials to implement effective, yet civil, interventions for limiting transmission. Finally, the same officials must ensure that their interventions maintain the human rights of high-risk populations and of healthcare workers. Conclusions: Applying these findings to future epidemics of infectious diseases can aid policy makers in navigating complicated ethical and public health questions, and help prevent them from repeating past mistakes in handling epidemics.

Control of African swine fever epidemics in industrialized swine populations

DEFF Research Database (Denmark)

Hisham Beshara Halasa, Tariq; Bøtner, Anette; Mortensen, Sten

2016-01-01

, it is important to explore strategies that can effectively control an epidemic of ASF. In this study, the epidemiological and economic effects of strategies to control the spread of ASF between domestic swine herds were examined using a published model (DTU-DADS-ASF). The control strategies were the basic EU...... and national strategy (Basic), the basic strategy plus pre-emptive depopulation of neighboring swine herds, and intensive surveillance of herds in the control zones, including testing live or dead animals. Virus spread via wild boar was not modelled. Under the basic control strategy, the median epidemic......African swine fever (ASF) is a notifiable infectious disease with a high impact on swine health. The disease is endemic in certain regions in the Baltic countries and has spread to Poland constituting a risk of ASF spread toward Western Europe. Therefore, as part of contingency planning...

Epidemics and dimensionality in hierarchical networks

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Zheng, Da-Fang; Hui, P. M.; Trimper, Steffen; Zheng, Bo

2005-07-01

Epidemiological processes are studied within a recently proposed hierarchical network model using the susceptible-infected-refractory dynamics of an epidemic. Within the network model, a population may be characterized by H independent hierarchies or dimensions, each of which consists of groupings of individuals into layers of subgroups. Detailed numerical simulations reveal that for H>1, global spreading results regardless of the degree of homophily of the individuals forming a social circle. For H=1, a transition from global to local spread occurs as the population becomes decomposed into increasingly homophilous groups. Multiple dimensions in classifying individuals (nodes) thus make a society (computer network) highly susceptible to large-scale outbreaks of infectious diseases (viruses).

A Highly Infectious Disease Care Network in the US Healthcare System.

Science.gov (United States)

Le, Aurora B; Biddinger, Paul D; Smith, Philip W; Herstein, Jocelyn J; Levy, Deborah A; Gibbs, Shawn G; Lowe, John J

During the 2014-15 Ebola outbreak in West Africa, the United States responded by stratifying hospitals into 1 of 3 Centers for Disease Control and Prevention (CDC)-designated categories-based on the hospital's ability to identify, isolate, assess, and provide care to patients with suspected or confirmed Ebola virus disease (EVD)-in an attempt to position the US healthcare system to safely isolate and care for potential patients. Now, with the Ebola epidemic quelled, it is crucial that we act on the lessons learned from the EVD response to broaden our national perspective on infectious disease mitigation and management, build on our newly enhanced healthcare capabilities to respond to infectious disease threats, develop a more cost-effective and sustainable model of infectious disease prevention, and continue to foster training so that the nation is not in a vulnerable position once more. We propose the formal creation of a US Highly Infectious Disease Care Network (HIDCN) modeled after 2 previous highly infectious disease consensus efforts in the United States and the European Union. A US Highly Infectious Disease Care Network can provide a common platform for the exchange of training, protocols, research, knowledge, and capability sharing among high-level isolation units. Furthermore, we envision the network will cultivate relationships among facilities and serve as a means of establishing national standards for infectious disease response, which will strengthen domestic preparedness and the nation's ability to respond to the next highly infectious disease threat.

Changes of Global Infectious Disease Governance in 2000s: Rise of Global Health Security and Transformation of Infectious Disease Control System in South Korea

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Eun Kyung CHOI

2016-12-01

Full Text Available This paper focus upon the changes of global infectious disease governance in 2000s and the transformation of infectious disease control system in South Korea. Traditionally, infectious disease was globally governed by the quarantine regulated by the international conventions. When an infectious disease outbreak occurred in one country, each country prevented transmission of the disease through the standardized quarantine since the installation of international sanitary convention in 1892. Republic of Korea also organized the infectious disease control system with quarantine and disease report procedure after the establishment of government. Additionally, Korea National Health Institute(KNIH was founded as research and training institute for infectious disease. However, traditional international health regulation system faced a serious challenge by the appearance of emerging and re-emerging infectious disease in 1990s. As a result, global infectious disease governance was rapidly changed under the demand to global disease surveillance and response. Moreover, global health security frame became important after 2001 bioterror and 2003 SARS outbreak. Consequently, international health regulation was fully revised in 2005, which included not only infectious disease but also public health emergency. The new international health regime was differently characterized in several aspects; reinforcement of global cooperation and surveillance, enlargement of the role of supranational and international agencies, and reorganization of national capacity. KNIH was reorganized with epidemic control and research since late 1990s. However, in 2004 Korea Center for Disease Control and Prevention(KCDC was established as a disease control institution with combining quarantine and other functions after 2003 SARS outbreak. KCDC unified national function against infectious disease including prevention, protection, response and research, as a national representative in

Changes of Global Infectious Disease Governance in 2000s: Rise of Global Health Security and Transformation of Infectious Disease Control System in South Korea.

Science.gov (United States)

Choi, Eun Kyung; Lee, Jong-Koo

2016-12-01

This paper focus upon the changes of global infectious disease governance in 2000s and the transformation of infectious disease control system in South Korea. Traditionally, infectious disease was globally governed by the quarantine regulated by the international conventions. When an infectious disease outbreak occurred in one country, each country prevented transmission of the disease through the standardized quarantine since the installation of international sanitary convention in 1892. Republic of Korea also organized the infectious disease control system with quarantine and disease report procedure after the establishment of government. Additionally, Korea National Health Institute(KNIH) was founded as research and training institute for infectious disease. However, traditional international health regulation system faced a serious challenge by the appearance of emerging and re-emerging infectious disease in 1990s. As a result, global infectious disease governance was rapidly changed under the demand to global disease surveillance and response. Moreover, global health security frame became important after 2001 bioterror and 2003 SARS outbreak. Consequently, international health regulation was fully revised in 2005, which included not only infectious disease but also public health emergency. The new international health regime was differently characterized in several aspects; reinforcement of global cooperation and surveillance, enlargement of the role of supranational and international agencies, and reorganization of national capacity. KNIH was reorganized with epidemic control and research since late 1990s. However, in 2004 Korea Center for Disease Control and Prevention(KCDC) was established as a disease control institution with combining quarantine and other functions after 2003 SARS outbreak. KCDC unified national function against infectious disease including prevention, protection, response and research, as a national representative in disease control. The

Evaluating neighborhood structures for modeling intercity diffusion of large-scale dengue epidemics.

Science.gov (United States)

Wen, Tzai-Hung; Hsu, Ching-Shun; Hu, Ming-Che

2018-05-03

Dengue fever is a vector-borne infectious disease that is transmitted by contact between vector mosquitoes and susceptible hosts. The literature has addressed the issue on quantifying the effect of individual mobility on dengue transmission. However, there are methodological concerns in the spatial regression model configuration for examining the effect of intercity-scale human mobility on dengue diffusion. The purposes of the study are to investigate the influence of neighborhood structures on intercity epidemic progression from pre-epidemic to epidemic periods and to compare definitions of different neighborhood structures for interpreting the spread of dengue epidemics. We proposed a framework for assessing the effect of model configurations on dengue incidence in 2014 and 2015, which were the most severe outbreaks in 70 years in Taiwan. Compared with the conventional model configuration in spatial regression analysis, our proposed model used a radiation model, which reflects population flow between townships, as a spatial weight to capture the structure of human mobility. The results of our model demonstrate better model fitting performance, indicating that the structure of human mobility has better explanatory power in dengue diffusion than the geometric structure of administration boundaries and geographic distance between centroids of cities. We also identified spatial-temporal hierarchy of dengue diffusion: dengue incidence would be influenced by its immediate neighboring townships during pre-epidemic and epidemic periods, and also with more distant neighbors (based on mobility) in pre-epidemic periods. Our findings suggest that the structure of population mobility could more reasonably capture urban-to-urban interactions, which implies that the hub cities could be a "bridge" for large-scale transmission and make townships that immediately connect to hub cities more vulnerable to dengue epidemics.

Role of Iranian Traditional Medicine in the Prevention of Respiratory Infectious Diseases.

Science.gov (United States)

Soroushzadeh, Sayed Mohammad Ali; Khiveh, Ali; Gerayelimalek, Valiollah

2016-05-01

In order to define appropriate plans for respiratory infectious diseases, in accordance with Iranian traditional medicine, one should cover the topic of "havae vabai". "Havae vabai" is related to the epidemics of respiratory infectious diseases. This study is a review of the role of Iranian traditional medicine in the prevention of respiratory infectious diseases .Resources of traditional medicine with the keyword "havae vabai" were reviewed in Noor digital library. The perspective of traditional medicine for the prevention of disease in "havae vabai" is based on self-recuperation and air modification. Items that are mentioned are; refine the surrounding air, move to a proper space, live in a house with no source of water like fountains and limited flow of air, air-drying, use air freshener, smell fruit sticks, use in-house plants, and place a cloth soaked with vinegar in front of the nose. For self-recuperation, reducing body moisture with proper foods and drugs or with vomiting, diarrhea, phlebotomy, wet-cupping, reduction in food and drink intake, avoiding sexual intercourse, bathing, heavy exercise, inactivity, overeating, hunger, thirst, milk, sweets, fish, fatty foods, fruits especially juicy fruits are recommended. The food that tends to have a sour taste, eating meat cooked with sour taste like vinegar is suggested. The use of the solutions offered in traditional medicine to control air is helpful as it can reduce epidemics, such as influenza; that yearly kills many patients with a heavy financial burden.

Could viruses contribute to the worldwide epidemic of obesity?

Science.gov (United States)

Atkinson, Richard L

2008-01-01

The prevalence of obesity in children increased rapidly starting about 1980 in both developed and developing countries. Studies of changes in diet and physical activity, television watching, and food advertisements on television suggest that these are not sufficient to explain the epidemic. The pattern of rapid spread is suggestive of an infectious origin. The concept of virus-induced obesity is not new. Eight viruses have been shown to cause obesity in animals and there is evidence for virus-induced obesity in humans. Recent evidence on animal and human adenoviruses suggests that these adenoviruses may infect adipocytes to alter enzymes and transcription factors resulting in accumulation of triglycerides and differentiation of preadipocytes into mature adipocytes. The E4orf1 gene of Ad-36 has been shown to be responsible for the adipogenic effect. It appears that a portion of the worldwide epidemic of obesity since 1980 could be due to infections with human adenoviruses.

Infectious Risks of Traveling Abroad.

Science.gov (United States)

Chen, Lin H; Blair, Barbra M

2015-08-01

A popular leisure activity, international travel can be associated with some infections. The most common travel-related illnesses appear to be gastrointestinal, dermatologic, respiratory, and systemic febrile syndromes. The pretravel medical consultation includes immunizations, malaria chemoprophylaxis, self-treatment for traveler's diarrhea, and advice on the prevention of a myriad of other infectious causes including dengue, chikungunya, rickettsiosis, leptospirosis, schistosomiasis, and strongyloidiasis. Travel to locations experiencing outbreaks such as Ebola virus disease, Middle East respiratory syndrome, avian influenza, and chikungunya call for specific alerts on preventive strategies. After travel, evaluation of an ill traveler must explore details of exposure, including destinations visited; activities; ingestion of contaminated food or drinks; contact with vectors, animals, fresh water, or blood and body fluids; and other potential exposures. Knowledge of the geographic distribution of infectious diseases is important in generating the differential diagnoses and testing accordingly. Empiric treatment is sometimes necessary when suspicion of a certain diagnosis is strong and confirmatory tests are delayed or lacking, particularly for infections that are rapidly progressive (for example, malaria) or for which timing of testing is prolonged (such as leptospirosis).

Post-infectious sequelae of travelers' diarrhea.

Science.gov (United States)

Connor, Bradley A; Riddle, Mark S

2013-01-01

Travelers' diarrhea (TD) has generally been considered a self-limited disorder which resolves more quickly with expeditious and appropriate antibiotic therapy given bacteria are the most frequently identified cause. However, epidemiological, clinical, and basic science evidence identifying a number of chronic health conditions related to these infections has recently emerged which challenges this current paradigm. These include serious and potentially disabling enteric and extra-intestinal long-term complications. Among these are rheumatologic, neurologic, gastrointestinal, renal, and endocrine disorders. This review aims to examine and summarize the current literature pertaining to three of these post-infectious disorders: reactive arthritis, Guillain-Barré syndrome, and post-infectious irritable bowel syndrome and the relationship of these conditions to diarrhea associated with travel as well as to diarrhea associated with gastroenteritis which may not be specifically travel related but relevant by shared microbial pathogens. It is hoped this review will allow clinicians who see travelers to be aware of these post-infectious sequelae thus adding to our body of knowledge in travel medicine. Data for this article were identified by searches of PubMed and MEDLINE, and references from relevant articles using search terms "travelers' diarrhea" "reactive arthritis" "Guillain-Barré syndrome" "Post-Infectious Irritable Bowel Syndrome." Abstracts were included when related to previously published work. A review of the published literature reveals that potential consequences of travelers' diarrhea may extend beyond the acute illness and these post-infectious complications may be more common than currently recognized. In addition since TD is such a common occurrence it would be helpful to be able to identify those who might be at greater risk of post-infectious sequelae in order to target more aggressive prophylactic or therapeutic approaches to such individuals. It is

CT evaluation of infectious colitis

International Nuclear Information System (INIS)

Horiki, Noriyuki; Maruyama, Masataka; Fujita, Yoshiyuki; Suzuki, Yuko; Tanaka, Tsuyoshi; Imoto, Ichiro; Adachi, Yukihiko

2002-01-01

Computed tomography (CT) is useful for evaluating the diagnosis of gastrointestinal disease, such as infectious colitis, in patients with severe pain and bloody diarrhea. During the 7 years between November 1993 and October 2000, 34 patients with infectious colitis (18 male, 16 female; mean age 42±19 yrs), received emergency CT and colonoscopy because of severe abdominal pain and dysentery. The following organisms were isolated: pathogenic Escherichia coli (12), 6 of which were O157: H7 (O-157), Salmonella species (11), Campylobacter species (5), Vibrio parahaemolyticus (3), Yersinia enterocolotica (2) and Shigella species (1). Thickening of the intestinal wall greater than 10 mm was seen in the ascending colon in the 6 cases with E. coli O157, in 5/11 cases with Salmonella, 4/5 with Campylobacter and 1/6 with non-O157 pathogenic E. Coli. marked intestinal wall thickening, greater than 20 mm, was seen in the ascending colon of the 4 of the patients with an O-157 infection. In all patients with O-157 colitis, slight ascites was noted in the pelvic space. In additions, ascites was also seen in 3/13 patients with Salmonella and 1/5 patients with Campylobacter colitis. The CT findings, in the patients with infectious colitis, are non-specific but knowledge and recognition of the findings will help in patient evaluation and proper treatment. (author)

CT evaluation of infectious colitis

Energy Technology Data Exchange (ETDEWEB)

Horiki, Noriyuki; Maruyama, Masataka; Fujita, Yoshiyuki; Suzuki, Yuko [Saint Luke' s International Hospital, Tokyo (Japan); Tanaka, Tsuyoshi; Imoto, Ichiro [National Mie Chuo Hospital, Hisai (Japan); Adachi, Yukihiko [Mie Univ., Tsu (Japan). School of Medicine

2002-08-01

Computed tomography (CT) is useful for evaluating the diagnosis of gastrointestinal disease, such as infectious colitis, in patients with severe pain and bloody diarrhea. During the 7 years between November 1993 and October 2000, 34 patients with infectious colitis (18 male, 16 female; mean age 42{+-}19 yrs), received emergency CT and colonoscopy because of severe abdominal pain and dysentery. The following organisms were isolated: pathogenic Escherichia coli (12), 6 of which were O157: H7 (O-157), Salmonella species (11), Campylobacter species (5), Vibrio parahaemolyticus (3), Yersinia enterocolotica (2) and Shigella species (1). Thickening of the intestinal wall greater than 10 mm was seen in the ascending colon in the 6 cases with E. coli O157, in 5/11 cases with Salmonella, 4/5 with Campylobacter and 1/6 with non-O157 pathogenic E. Coli. marked intestinal wall thickening, greater than 20 mm, was seen in the ascending colon of the 4 of the patients with an O-157 infection. In all patients with O-157 colitis, slight ascites was noted in the pelvic space. In additions, ascites was also seen in 3/13 patients with Salmonella and 1/5 patients with Campylobacter colitis. The CT findings, in the patients with infectious colitis, are non-specific but knowledge and recognition of the findings will help in patient evaluation and proper treatment. (author)

A Full-Length Infectious cDNA Clone of Zika Virus from the 2015 Epidemic in Brazil as a Genetic Platform for Studies of Virus-Host Interactions and Vaccine Development

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Konstantin A. Tsetsarkin

2016-08-01

Full Text Available An arthropod-borne virus, Zika virus (ZIKV, has recently emerged as a major human pathogen. Associated with complications during perinatal development and Guillain-Barré syndrome in adults, ZIKV raises new challenges for understanding the molecular determinants of flavivirus pathogenesis. This underscores the necessity for the development of a reverse genetic system based on an epidemic ZIKV strain. Here, we describe the generation and characterization in cell cultures of an infectious cDNA clone of ZIKV isolated from the 2015 epidemic in Brazil. The cDNA-derived ZIKV replicated efficiently in a variety of cell lines, including those of both neuronal and placental origin. We observed that the growth of cDNA-derived virus was attenuated compared to the growth of the parental isolate in most cell lines, which correlates with substantial differences in sequence heterogeneity between these viruses that were determined by deep-sequencing analysis. Our findings support the role of genetic diversity in maintaining the replicative fitness of viral populations under changing conditions. Moreover, these results indicate that caution should be exercised when interpreting the results of reverse-genetics experiments in attempts to accurately predict the biology of natural viruses. Finally, a Vero cell-adapted cDNA clone of ZIKV was generated that can be used as a convenient platform for studies aimed at the development of ZIKV vaccines and therapeutics.

Characterization and Function of the Inflammatory Response to Infection by a Gastrointestinal Nematode Parasite: New Insights into Protective Th2 Responses

Science.gov (United States)

2006-01-01

gastrointestinal nematode parasites;T. trichuris, T. muris , T suis. WT wild type. 1 Dissertation Introduction Background and Significance...and hosts2. Infectious parasites are responsible for a wide range of human diseases, including Leishmanisis, Malaria, Schistosomaisis, Giardia ...the gut to define more clearly protective mechanisms against gastrointestinal nematodes. Using a mouse whipworm model of Trichuris 81 muris

The severe acute respiratory syndrome epidemic in mainland China dissected.

Science.gov (United States)

Cao, Wu-Chun; de Vlas, Sake J; Richardus, Jan Hendrik

2011-03-08

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 nationwide internet-based disease reporting system was established.

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.

Resource allocation for epidemic control in metapopulations.

Science.gov (United States)

Ndeffo Mbah, Martial L; Gilligan, Christopher A

2011-01-01

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.

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.

Combining Surveillance Systems: Effective Merging of U.S. Veteran and Military Health Data

Science.gov (United States)

2016-08-04

Department of Defense, Silver Spring, Maryland, United States of America, 2 Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland...was used to examine seasonal influenza trends, a gastrointestinal (GI) illness epidemic and a heat-related event. This provided the first example of the... geriatric clinics, women’s primary care, infectious diseases and emergency medicine. We grouped visits into an influenza-like-illness (ILI) syndrome

Research on Modularized Design and Allocation of Infectious Disease Prevention and Control Equipment in China.

Science.gov (United States)

Zhao, Xin; Wang, Yun-Dou; Zhang, Xiao-Feng; Gao, Shu-Tian; Guo, Li-Jun; Sun, Li-Na

2017-06-01

For the prevention and control of newly emergent or sudden infectious diseases, we built an on-site, modularized prevention and control system and tested the equipment by using the clustering analysis method. On the basis of this system, we propose a modular equipment allocation method and 4 applications of this method for different types of infectious disease prevention and control. This will help to improve the efficiency and productivity of anti-epidemic emergency forces and will provide strong technical support for implementing more universal and serialized equipment in China. (Disaster Med Public Health Preparedness. 2017;11:375-382).

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

DEFF Research Database (Denmark)

Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

2013-01-01

Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models...... 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......, such as in other multiple failure scenarios, identifying the level of vulnerability offered by a network is one of the main challenges. In this paper, we present epidemic survivability, a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Moreover...

Mathematical Analysis of an Epidemic System in the Presence of Optimal Control and Population Dispersal

Science.gov (United States)

Nandi, Swapan Kumar; Jana, Soovoojeet; Mandal, Manotosh; Kar, T. K.

In this paper, we proposed and analyzed a susceptible-infected-recovered (SIR) type epidemic model to investigate the effect of transport-related infectious diseases namely tuberculosis, measles, rubella, influenza, sexually transmitted diseases, etc. The existence and stability criteria of both the diseases include free equilibrium point and endemic equilibrium point which are established and the threshold parametric condition for which the system passes through a transcritical bifurcation is also obtained. Optimal control strategy for control parameters is formulated and solved both theoretically and numerically. Lastly, we not only illustrate our theoretical results through graphical illustrations but also computer simulation is used to show that our model would be a good model to study the SARS epidemic in 2003.

Infectious prion diseases in humans: cannibalism, iatrogenicity and zoonoses.

Science.gov (United States)

Haïk, Stéphane; Brandel, Jean-Philippe

2014-08-01

In contrast with other neurodegenerative disorders associated to protein misfolding, human prion diseases include infectious forms (also called transmitted forms) such as kuru, iatrogenic Creutzfeldt-Jakob disease and variant Creutzfeldt-Jakob disease. The transmissible agent is thought to be solely composed of the abnormal isoform (PrP(Sc)) of the host-encoded prion protein that accumulated in the central nervous system of affected individuals. Compared to its normal counterpart, PrP(Sc) is β-sheet enriched and aggregated and its propagation is based on an autocatalytic conversion process. Increasing evidence supports the view that conformational variations of PrP(Sc) encoded the biological properties of the various prion strains that have been isolated by transmission studies in experimental models. Infectious forms of human prion diseases played a pivotal role in the emergence of the prion concept and in the characterization of the very unconventional properties of prions. They provide a unique model to understand how prion strains are selected and propagate in humans. Here, we review and discuss how genetic factors interplay with strain properties and route of transmission to influence disease susceptibility, incubation period and phenotypic expression in the light of the kuru epidemics due to ritual endocannibalism, the various series iatrogenic diseases secondary to extractive growth hormone treatment or dura mater graft and the epidemics of variant Creutzfeldt-Jakob disease linked to dietary exposure to the agent of bovine spongiform encephalopathy. Copyright © 2014 Elsevier B.V. All rights reserved.

El Niño Helps Spread Bartonellosis Epidemics in Peru

Science.gov (United States)

Zhou, Jiayu; Lau, William K.-M.; Masuoka, Fenny M.; Andre, Richard G.; Chamberlin, Judith; Lawyer, Phillip; Laughlin, Larry W.

The consequences of climate variability on human health, especially for poor and medically underserved populations, have received much attention in recent years. Some of the most severe health hazards induced by climate variability are epidemics of vector-borne infectious diseases. Entomologic studies have shown that insect vectors that transmit diseases, such as malaria, yellow fever, dengue, etc., are sensitive to temperature, humidity wind, and rainfall patterns, and therefore, their abundance is potentially influenced by climate variability. Because of its geographical location, the climate of tropical South America is strongly influenced by El Niño. The episodic outbreaks of various diseases in this region have been linked to the El Niño cycles. Yet, according to a report of the World Health Organization [1999], early results from South American epidemiological studies, which were based on the aggregated national disease data irrespective of the regional meteorological impacts, found no consistent correlation between the El Niño effect with the epidemics of malaria and yellow fever.

Cooperative epidemics on multiplex networks

Science.gov (United States)

Azimi-Tafreshi, N.

2016-04-01

The spread of one disease, in some cases, can stimulate the spreading of another infectious disease. Here, we treat analytically a symmetric coinfection model for spreading of two diseases on a two-layer multiplex network. We allow layer overlapping, but we assume that each layer is random and locally loopless. Infection with one of the diseases increases the probability of getting infected with the other. Using the generating function method, we calculate exactly the fraction of individuals infected with both diseases (so-called coinfected 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 coinfected clusters in the case of cooperating diseases with the so-called "viable" clusters in networks with dependencies.

Infectious Diseases and Immunizations in International Adoption.

Science.gov (United States)

Obringer, Emily; Walsh, Linda

2017-02-01

Children who are adopted internationally have an increased risk of infectious diseases due to endemic conditions and variable access to preventive health care, such as vaccines, in their country of origin. Pediatricians and other providers who care for children should be familiar with the recommended screening for newly arrived international adoptees. Testing for gastrointestinal pathogens, tuberculosis, hepatitis, syphilis, and HIV should be routinely performed. Other endemic diseases and common skin infections may need to be assessed. Evaluation of the child's immunization record is also important, as nearly all international adoptees will require catch-up vaccines. The provider may also be asked to review medical records prior to adoption, provide travel advice, and ensure that parents and other close contacts are up-to-date on immunizations prior to the arrival of the newest family member. The pediatrician serves a unique role in facilitating the evaluation, treatment, and prevention of infectious diseases in international adoptees. [Pediatr Ann. 2017;46(2):e56-e60.]. Copyright 2017, SLACK Incorporated.

Efficient local behavioral-change strategies to reduce the spread of epidemics in networks

Science.gov (United States)

Bu, Yilei; Gregory, Steve; Mills, Harriet L.

2013-10-01

It has recently become established that the spread of infectious diseases between humans is affected not only by the pathogen itself but also by changes in behavior as the population becomes aware of the epidemic, for example, social distancing. It is also well known that community structure (the existence of relatively densely connected groups of vertices) in contact networks influences the spread of disease. We propose a set of local strategies for social distancing, based on community structure, that can be employed in the event of an epidemic to reduce the epidemic size. Unlike most social distancing methods, ours do not require individuals to know the disease state (infected or susceptible, etc.) of others, and we do not make the unrealistic assumption that the structure of the entire contact network is known. Instead, the recommended behavior change is based only on an individual's local view of the network. Each individual avoids contact with a fraction of his/her contacts, using knowledge of his/her local network to decide which contacts should be avoided. If the behavior change occurs only when an individual becomes ill or aware of the disease, these strategies can substantially reduce epidemic size with a relatively small cost, measured by the number of contacts avoided.

Postinfectious Functional Gastrointestinal Disorders: A Focus on Epidemiology and Research Agendas

OpenAIRE

Deising, Adam; Gutierrez, Ramiro L.; Porter, Chad K.; Riddle, Mark S.

2013-01-01

Epidemiologic research is fundamental and complementary to our understanding of disease and development of primary, secondary, and tertiary interventions. To put the current evidence into context and identify gaps and research priorities in the areas of disease attribution, burden of disease, clinical characterization, and management of postinfectious functional gastrointestinal disorders (PI-FGDs), we took a multidisciplinary approach from the domains of infectious disease, gastroenterology,...

[Historical notes on Infectious Diseases Hospital Francisco Javier Muñiz in Buenos Aires, Argentina].

Science.gov (United States)

Laval, Enrique

2012-08-01

The Infectious Diseases Hospital Francisco Javier Muñiz, Buenos Aires, Argentina, is the oldest in Latin America. It is over 100 years old and has a history worthy of pride. It became known as "Hospital of the pests" and was preceded by the old House of Insulation, which served as a quarantine station during epidemics of cholera, yellow fever and smallpox. The new House of Insulation, built in the neighborhood of Parque Patricios ("Barracks Hospital"), was renamed in 1904 in memory of Francisco Javier Muñiz, a former military doctor, naturalist and paleontologist. Its technical name is "Porteño Care Centre and National Reference Regional Infectious-Contagious Disease". It receives numerous national and foreign undergraduate and postgraduate students in its Departments of Infectious Diseases and Respiratory Diseases.

EpiModel: An R Package for Mathematical Modeling of Infectious Disease over Networks.

Science.gov (United States)

Jenness, Samuel M; Goodreau, Steven M; Morris, Martina

2018-04-01

Package EpiModel provides tools for building, simulating, and analyzing mathematical models for the population dynamics of infectious disease transmission in R. Several classes of models are included, but the unique contribution of this software package is a general stochastic framework for modeling the spread of epidemics on networks. EpiModel integrates recent advances in statistical methods for network analysis (temporal exponential random graph models) that allow the epidemic modeling to be grounded in empirical data on contacts that can spread infection. This article provides an overview of both the modeling tools built into EpiModel , designed to facilitate learning for students new to modeling, and the application programming interface for extending package EpiModel , designed to facilitate the exploration of novel research questions for advanced modelers.

Climate extremes promote fatal co-infections during canine distemper epidemics in African lions.

Science.gov (United States)

Munson, Linda; Terio, Karen A; Kock, Richard; Mlengeya, Titus; Roelke, Melody E; Dubovi, Edward; Summers, Brian; Sinclair, Anthony R E; Packer, Craig

2008-06-25

Extreme climatic conditions may alter historic host-pathogen relationships and synchronize the temporal and spatial convergence of multiple infectious agents, triggering epidemics with far greater mortality than those due to single pathogens. Here we present the first data to clearly illustrate how climate extremes can promote a complex interplay between epidemic and endemic pathogens that are normally tolerated in isolation, but with co-infection, result in catastrophic mortality. A 1994 canine distemper virus (CDV) epidemic in Serengeti lions (Panthera leo) coincided with the death of a third of the population, and a second high-mortality CDV epidemic struck the nearby Ngorongoro Crater lion population in 2001. The extent of adult mortalities was unusual for CDV and prompted an investigation into contributing factors. Serological analyses indicated that at least five "silent" CDV epidemics swept through the same two lion populations between 1976 and 2006 without clinical signs or measurable mortality, indicating that CDV was not necessarily fatal. Clinical and pathology findings suggested that hemoparsitism was a major contributing factor during fatal epidemics. Using quantitative real-time PCR, we measured the magnitude of hemoparasite infections in these populations over 22 years and demonstrated significantly higher levels of Babesia during the 1994 and 2001 epidemics. Babesia levels correlated with mortalities and extent of CDV exposure within prides. The common event preceding the two high mortality CDV outbreaks was extreme drought conditions with wide-spread herbivore die-offs, most notably of Cape buffalo (Syncerus caffer). As a consequence of high tick numbers after the resumption of rains and heavy tick infestations of starving buffalo, the lions were infected by unusually high numbers of Babesia, infections that were magnified by the immunosuppressive effects of coincident CDV, leading to unprecedented mortality. Such mass mortality events may become

Climate extremes promote fatal co-infections during canine distemper epidemics in African lions.

Directory of Open Access Journals (Sweden)

Linda Munson

Full Text Available Extreme climatic conditions may alter historic host-pathogen relationships and synchronize the temporal and spatial convergence of multiple infectious agents, triggering epidemics with far greater mortality than those due to single pathogens. Here we present the first data to clearly illustrate how climate extremes can promote a complex interplay between epidemic and endemic pathogens that are normally tolerated in isolation, but with co-infection, result in catastrophic mortality. A 1994 canine distemper virus (CDV epidemic in Serengeti lions (Panthera leo coincided with the death of a third of the population, and a second high-mortality CDV epidemic struck the nearby Ngorongoro Crater lion population in 2001. The extent of adult mortalities was unusual for CDV and prompted an investigation into contributing factors. Serological analyses indicated that at least five "silent" CDV epidemics swept through the same two lion populations between 1976 and 2006 without clinical signs or measurable mortality, indicating that CDV was not necessarily fatal. Clinical and pathology findings suggested that hemoparsitism was a major contributing factor during fatal epidemics. Using quantitative real-time PCR, we measured the magnitude of hemoparasite infections in these populations over 22 years and demonstrated significantly higher levels of Babesia during the 1994 and 2001 epidemics. Babesia levels correlated with mortalities and extent of CDV exposure within prides. The common event preceding the two high mortality CDV outbreaks was extreme drought conditions with wide-spread herbivore die-offs, most notably of Cape buffalo (Syncerus caffer. As a consequence of high tick numbers after the resumption of rains and heavy tick infestations of starving buffalo, the lions were infected by unusually high numbers of Babesia, infections that were magnified by the immunosuppressive effects of coincident CDV, leading to unprecedented mortality. Such mass mortality

Climate Extremes Promote Fatal Co-Infections during Canine Distemper Epidemics in African Lions

Science.gov (United States)

Munson, Linda; Terio, Karen A.; Kock, Richard; Mlengeya, Titus; Roelke, Melody E.; Dubovi, Edward; Summers, Brian; Sinclair, Anthony R. E.; Packer, Craig

2008-01-01

Extreme climatic conditions may alter historic host-pathogen relationships and synchronize the temporal and spatial convergence of multiple infectious agents, triggering epidemics with far greater mortality than those due to single pathogens. Here we present the first data to clearly illustrate how climate extremes can promote a complex interplay between epidemic and endemic pathogens that are normally tolerated in isolation, but with co-infection, result in catastrophic mortality. A 1994 canine distemper virus (CDV) epidemic in Serengeti lions (Panthera leo) coincided with the death of a third of the population, and a second high-mortality CDV epidemic struck the nearby Ngorongoro Crater lion population in 2001. The extent of adult mortalities was unusual for CDV and prompted an investigation into contributing factors. Serological analyses indicated that at least five “silent” CDV epidemics swept through the same two lion populations between 1976 and 2006 without clinical signs or measurable mortality, indicating that CDV was not necessarily fatal. Clinical and pathology findings suggested that hemoparsitism was a major contributing factor during fatal epidemics. Using quantitative real-time PCR, we measured the magnitude of hemoparasite infections in these populations over 22 years and demonstrated significantly higher levels of Babesia during the 1994 and 2001 epidemics. Babesia levels correlated with mortalities and extent of CDV exposure within prides. The common event preceding the two high mortality CDV outbreaks was extreme drought conditions with wide-spread herbivore die-offs, most notably of Cape buffalo (Syncerus caffer). As a consequence of high tick numbers after the resumption of rains and heavy tick infestations of starving buffalo, the lions were infected by unusually high numbers of Babesia, infections that were magnified by the immunosuppressive effects of coincident CDV, leading to unprecedented mortality. Such mass mortality events may

Gastrointestinal illness linked to incidents in drinking water distribution networks in Sweden.

Science.gov (United States)

Säve-Söderbergh, Melle; Bylund, John; Malm, Annika; Simonsson, Magnus; Toljander, Jonas

2017-10-01

During recent years, knowledge gaps on drinking water-related gastrointestinal illness have been identified, especially for non-epidemic cases. Pathogen contamination of drinking water during distribution has been suggested to contribute to these cases, but the risk factors are not yet fully understood. During 2014-2015, we conducted an epidemiological study in five municipalities in Sweden, to assess whether incidents in the drinking water distribution system influence the risk of gastrointestinal illness. Telephone interviews were conducted in the affected areas and in reference areas 7-14 days after a reported incident. Symptoms of gastrointestinal illness occurring during the period were documented for each household member. The results showed a significantly elevated risk of vomiting and acute gastrointestinal illness (AGI) in the affected areas, compared to the reference areas (OR vom.  = 2.0, 95% CI: 1.2-3.3; OR AGI  = 1.9, 95% CI: 1.2-3.0). Certain conditions, or risk factors, during the incidents, such as sewage and drinking water pipelines at the same level in the trench, were associated with an elevated risk of AGI and vomiting. Safety measures taken during repair work, like flushing, were also associated with an elevated risk of AGI and vomiting. These results show that incidents in the drinking water distribution network contribute to endemic gastrointestinal illness, especially AGI and vomiting, and that external pathogen contamination of the drinking water is a likely cause of these cases of gastrointestinal illness. The results also indicate that safety measures used today may not be sufficient for eliminating the risk of gastrointestinal illness. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Deciphering emerging Zika and dengue viral epidemics: Implications for global maternal–child health burden

Directory of Open Access Journals (Sweden)

Ernest Tambo

2016-05-01

Full Text Available Summary: Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance–response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN with other models of socio-economic, climatic, environmental and ecological mitigation and adaptation strategies will be necessary to improve evidence-based national and global maternal–child health agenda and action plans. Keywords: Zika virus, Epidemics, Health, Preparedness, Surveillance, Maternal–child

Discrete-time moment closure models for epidemic spreading in populations of interacting individuals.

Science.gov (United States)

Frasca, Mattia; Sharkey, Kieran J

2016-06-21

Understanding the dynamics of spread of infectious diseases between individuals is essential for forecasting the evolution of an epidemic outbreak or for defining intervention policies. The problem is addressed by many approaches including stochastic and deterministic models formulated at diverse scales (individuals, populations) and different levels of detail. Here we consider discrete-time SIR (susceptible-infectious-removed) dynamics propagated on contact networks. We derive a novel set of 'discrete-time moment equations' for the probability of the system states at the level of individual nodes and pairs of nodes. These equations form a set which we close by introducing appropriate approximations of the joint probabilities appearing in them. For the example case of SIR processes, we formulate two types of model, one assuming statistical independence at the level of individuals and one at the level of pairs. From the pair-based model we then derive a model at the level of the population which captures the behavior of epidemics on homogeneous random networks. With respect to their continuous-time counterparts, the models include a larger number of possible transitions from one state to another and joint probabilities with a larger number of individuals. The approach is validated through numerical simulation over different network topologies. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Gastrointestinal symptoms in children with acute neuroinfections

Directory of Open Access Journals (Sweden)

A.I. Markov

2018-02-01

Full Text Available Background. In cases of severe forms of infectious di­seases, in addition to local inflammation, secondary lesions of the gastrointestinal organs may occur. We aimed to study the semiotics and epidemiology of gastrointestinal symptoms in children with acute neuroinfection. Materials and methods. This observational, retrospective, case-control study. We analyzed cases of in-patient treatment of children aged 1 month to 18 years with acute neuroinfections (meningitis, encephalitis and encephalomyelopolyneuropathy. Results. The study included 117 patients with acute central nervous system infections. Clinical symptoms of gastrointestinal infection were observed in 83 (70.9 % children. Among revealed symptoms, disorders of intestinal moti­lity, such as constipation and diarrhea, were prevalent. Manifestations of hepatobiliary system dysfunction included increased transaminase level (alanine aminotransferase (ALT, alkaline phosphatase, gamma-glutamyltransferase (GGTF and/or ultrasound changes (enlargement, diffuse structural changes and were observed in 39.1 % of patients. Among the laboratory parameters, elevated ALT level was observed in 8.3 % of patients, bilirubin was elevated in only one child, alkaline phosphatase was above the age norm in 11.8 %, an increased GGTF above the age norm was observed in 31.3 % of patients. The level of intestinal fatty acid binding protein (I-FABP was elevated in 86.4 %, and L-type fatty acid binding protein (L-FABP — in all (100 % children. Clinical manifestations of gastrointestinal dysfunction (the presence of at least one of the gastrointestinal symptoms had an inverse relationship with the child’s age (rpb = –0.19, p = 0.033, correlated with staying in intensive care unit (odds ratio (OR = +5.25; 95% confidence interval (CI 1.62–16.97, artificial ventilation (OR = +4.5; 95% CI 1.00–21.69 and level of I-FABP (rpb = 0.34, p = 0.019. Conclusions. Among gastrointestinal symptoms in children with

Homo-psychologicus: Reactionary behavioural aspects of epidemics

Directory of Open Access Journals (Sweden)

Alhaji Cherif

2016-03-01

Full Text Available We formulate an in silico model of pathogen avoidance mechanism and investigate its impact on defensive behavioural measures (e.g., spontaneous social exclusions and distancing, crowd avoidance and voluntary vaccination adaptation. In particular, we use SIR(BS (e.g., susceptible-infected-recovered with additional behavioural component model to investigate the impact of homo-psychologicus aspects of epidemics. We focus on reactionary behavioural changes, which apply to both social distancing and voluntary vaccination participations. Our analyses reveal complex relationships between spontaneous and uncoordinated behavioural changes, the emergence of its contagion properties, and mitigation of infectious diseases. We find that the presence of effective behavioural changes can impede the persistence of disease. Furthermore, it was found that under perfect effective behavioural change, there are three regions in the response factor (e.g., imitation and/or reactionary and behavioural scale factor (e.g., global/local factors ρ–α behavioural space. Mainly, (1 disease is always endemic even in the presence of behavioural change, (2 behavioural-prevalence plasticity is observed and disease can sometimes be eradication, and (3 elimination of endemic disease under permanence of permanent behavioural change is achieved. These results suggest that preventive behavioural changes (e.g., non-pharmaceutical prophylactic measures, social distancing and exclusion, crowd avoidance are influenced by individual differences in perception of risks and are a salient feature of epidemics. Additionally, these findings indicates that care needs to be taken when considering the effect of adaptive behavioural change in predicting the course of epidemics, and as well as the interpretation and development of the public health measures that account for spontaneous behavioural changes.

Homo-psychologicus: Reactionary behavioural aspects of epidemics.

Science.gov (United States)

Cherif, Alhaji; Barley, Kamal; Hurtado, Marcel

2016-03-01

We formulate an in silico model of pathogen avoidance mechanism and investigate its impact on defensive behavioural measures (e.g., spontaneous social exclusions and distancing, crowd avoidance and voluntary vaccination adaptation). In particular, we use SIR(B)S (e.g., susceptible-infected-recovered with additional behavioural component) model to investigate the impact of homo-psychologicus aspects of epidemics. We focus on reactionary behavioural changes, which apply to both social distancing and voluntary vaccination participations. Our analyses reveal complex relationships between spontaneous and uncoordinated behavioural changes, the emergence of its contagion properties, and mitigation of infectious diseases. We find that the presence of effective behavioural changes can impede the persistence of disease. Furthermore, it was found that under perfect effective behavioural change, there are three regions in the response factor (e.g., imitation and/or reactionary) and behavioural scale factor (e.g., global/local) factors ρ-α behavioural space. Mainly, (1) disease is always endemic even in the presence of behavioural change, (2) behavioural-prevalence plasticity is observed and disease can sometimes be eradication, and (3) elimination of endemic disease under permanence of permanent behavioural change is achieved. These results suggest that preventive behavioural changes (e.g., non-pharmaceutical prophylactic measures, social distancing and exclusion, crowd avoidance) are influenced by individual differences in perception of risks and are a salient feature of epidemics. Additionally, these findings indicates that care needs to be taken when considering the effect of adaptive behavioural change in predicting the course of epidemics, and as well as the interpretation and development of the public health measures that account for spontaneous behavioural changes. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The contribution of biological, mathematical, clinical, engineering and social sciences to combatting the West African Ebola epidemic.

Science.gov (United States)

Whitty, Christopher J M

2017-05-26

The tragic West African Ebola epidemic claimed many lives, but would have been worse still if scientific insights from many disciplines had not been integrated to create a strong technical response. Epidemiology and modelling triggered the international response and guided where response efforts were directed; virology, engineering and clinical science helped reduce deaths and transmission in and from hospitals and treatment centres; social sciences were key to reducing deaths from funerals and in the community; diagnostic and operational research made the response more efficient; immunology and vaccine research contributed to the final stages of the epidemic and will help prevent future epidemics. These varied scientific contributions had to be integrated into a combined narrative, communicated to policymakers to inform decisions, and used by courageous local and international responders in the field in real time. Not every area of science was optimal, and in particular, clinical trials of simple interventions such as fluid management were slow to be adopted and sharing of data was initially poor. This Ebola epidemic demonstrated how science can respond to a major emergency, but also has lessons for better responses in future infectious emergencies.This article is part of the themed issue 'The 2013-2016 West African Ebola epidemic: data, decision-making and disease control'. © 2017 The Author(s).

Using prediction markets of market scoring rule to forecast infectious diseases: a case study in Taiwan.

Science.gov (United States)

Tung, Chen-yuan; Chou, Tzu-chuan; Lin, Jih-wen

2015-08-11

The Taiwan CDC relied on the historical average number of disease cases or rate (AVG) to depict the trend of epidemic diseases in Taiwan. By comparing the historical average data with prediction markets, we show that the latter have a better prediction capability than the former. Given the volatility of the infectious diseases in Taiwan, historical average is unlikely to be an effective prediction mechanism. We designed and built the Epidemic Prediction Markets (EPM) system based upon the trading mechanism of market scoring rule. By using this system, we aggregated dispersed information from various medical professionals to predict influenza, enterovirus, and dengue fever in Taiwan. EPM was more accurate in 701 out of 1,085 prediction events than the traditional baseline of historical average and the winning ratio of EPM versus AVG was 64.6 % for the target week. For the absolute prediction error of five diseases indicators of three infectious diseases, EPM was more accurate for the target week than AVG except for dengue fever confirmed cases. The winning ratios of EPM versus AVG for the confirmed cases of severe complicated influenza case, the rate of enterovirus infection, and the rate of influenza-like illness in the target week were 69.6 %, 83.9 and 76.0 %, respectively; instead, for the prediction of the confirmed cases of dengue fever and the confirmed cases of severe complicated enterovirus infection, the winning ratios of EPM were all below 50 %. Except confirmed cases of dengue fever, EPM provided accurate, continuous and real-time predictions of four indicators of three infectious diseases for the target week in Taiwan and outperformed the historical average data of infectious diseases.

Social networks and spreading of epidemics

Science.gov (United States)

Trimper, Steffen; Zheng, Dafang; Brandau, Marian

2004-05-01

Epidemiological processes are studied within a recently proposed social network model using the susceptible-infected-refractory dynamics (SIR) of an epidemic. Within the network model, a population of individuals may be characterized by H independent hierarchies or dimensions, each of which consists of groupings of individuals into layers of subgroups. Detailed numerical simulations reveals that for H > 1, the global spreading results regardless of the degree of homophily α of the individuals forming a social circle. For H = 1, a transition from a global to a local spread occurs as the population becomes decomposed into increasingly homophilous groups. Multiple dimensions in classifying individuals (nodes) thus make a society (computer network) highly susceptible to large scale outbreaks of infectious diseases (viruses). The SIR-model can be extended by the inclusion of waiting times resulting in modified distribution function of the recovered.

Agent-based financial dynamics model from stochastic interacting epidemic system and complexity analysis

International Nuclear Information System (INIS)

Lu, Yunfan; Wang, Jun; Niu, Hongli

2015-01-01

An agent-based financial stock price model is developed and investigated by a stochastic interacting epidemic system, which is one of the statistical physics systems and has been used to model the spread of an epidemic or a forest fire. Numerical and statistical analysis are performed on the simulated returns of the proposed financial model. Complexity properties of the financial time series are explored by calculating the correlation dimension and using the modified multiscale entropy method. In order to verify the rationality of the financial model, the real stock market indexes, Shanghai Composite Index and Shenzhen Component Index, are studied in comparison with the simulation data of the proposed model for the different infectiousness parameters. The empirical research reveals that this financial model can reproduce some important features of the real stock markets. - Highlights: • A new agent-based financial price model is developed by stochastic interacting epidemic system. • The structure of the proposed model allows to simulate the financial dynamics. • Correlation dimension and MMSE are applied to complexity analysis of financial time series. • Empirical results show the rationality of the proposed financial model

Agent-based financial dynamics model from stochastic interacting epidemic system and complexity analysis

Energy Technology Data Exchange (ETDEWEB)

Lu, Yunfan, E-mail: yunfanlu@yeah.net; Wang, Jun; Niu, Hongli

2015-06-12

An agent-based financial stock price model is developed and investigated by a stochastic interacting epidemic system, which is one of the statistical physics systems and has been used to model the spread of an epidemic or a forest fire. Numerical and statistical analysis are performed on the simulated returns of the proposed financial model. Complexity properties of the financial time series are explored by calculating the correlation dimension and using the modified multiscale entropy method. In order to verify the rationality of the financial model, the real stock market indexes, Shanghai Composite Index and Shenzhen Component Index, are studied in comparison with the simulation data of the proposed model for the different infectiousness parameters. The empirical research reveals that this financial model can reproduce some important features of the real stock markets. - Highlights: • A new agent-based financial price model is developed by stochastic interacting epidemic system. • The structure of the proposed model allows to simulate the financial dynamics. • Correlation dimension and MMSE are applied to complexity analysis of financial time series. • Empirical results show the rationality of the proposed financial model.

ISS--an electronic syndromic surveillance system for infectious disease in rural China.

Directory of Open Access Journals (Sweden)

Weirong Yan

Full Text Available BACKGROUND: Syndromic surveillance system has great advantages in promoting the early detection of epidemics and reducing the necessities of disease confirmation, and it is especially effective for surveillance in resource poor settings. However, most current syndromic surveillance systems are established in developed countries, and there are very few reports on the development of an electronic syndromic surveillance system in resource-constrained settings. OBJECTIVE: This study describes the design and pilot implementation of an electronic surveillance system (ISS for the early detection of infectious disease epidemics in rural China, complementing the conventional case report surveillance system. METHODS: ISS was developed based on an existing platform 'Crisis Information Sharing Platform' (CRISP, combining with modern communication and GIS technology. ISS has four interconnected functions: 1 work group and communication group; 2 data source and collection; 3 data visualization; and 4 outbreak detection and alerting. RESULTS: As of Jan. 31(st 2012, ISS has been installed and pilot tested for six months in four counties in rural China. 95 health facilities, 14 pharmacies and 24 primary schools participated in the pilot study, entering respectively 74,256, 79,701, and 2330 daily records into the central database. More than 90% of surveillance units at the study sites are able to send daily information into the system. In the paper, we also presented the pilot data from health facilities in the two counties, which showed the ISS system had the potential to identify the change of disease patterns at the community level. CONCLUSIONS: The ISS platform may facilitate the early detection of infectious disease epidemic as it provides near real-time syndromic data collection, interactive visualization, and automated aberration detection. However, several constraints and challenges were encountered during the pilot implementation of ISS in rural China.

Prediction of meningococcal meningitis epidemics in western Africa by using climate information

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YAKA, D. P.; Sultan, B.; Tarbangdo, F.; Thiaw, W. M.

2013-12-01

The variations of certain climatic parameters and the degradation of ecosystems, can affect human's health by influencing the transmission, the spatiotemporal repartition and the intensity of infectious diseases. It is mainly the case of meningococcal meningitis (MCM) whose epidemics occur particularly in Sahelo-Soudanian climatic area of Western Africa under quite particular climatic conditions. Meningococcal Meningitis (MCM) is a contagious infection disease due to the bacteria Neisseria meningitis. MCM epidemics occur worldwide but the highest incidence is observed in the "meningitis belt" of sub-Saharan Africa, stretching from Senegal to Ethiopia. In spite of standards, strategies of prevention and control of MCS epidemic from World Health Organization (WHO) and States, African Sahelo-Soudanian countries remain frequently afflicted by disastrous epidemics. In fact, each year, during the dry season (February-April), 25 to 250 thousands of cases are observed. Children under 15 are particularly affected. Among favourable conditions for the resurgence and dispersion of the disease, climatic conditions may be important inducing seasonal fluctuations in disease incidence and contributing to explain the spatial pattern of the disease roughly circumscribed to the ecological Sahelo-Sudanian band. In this study, we tried to analyse the relationships between climatic factors, ecosystems degradation and MCM for a better understanding of MCM epidemic dynamic and their prediction. We have shown that MCM epidemics, whether at the regional, national or local level, occur in a specific period of the year, mainly from January to May characterised by a dry, hot and sandy weather. We have identified both in situ (meteorological synoptic stations) and satellitales climatic variables (NCEP reanalysis dataset) whose seasonal variability is dominating in MCM seasonal transmission. Statistical analysis have measured the links between seasonal variation of certain climatic parameters

Ethics, health policy, and Zika: From emergency to global epidemic?

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Jamrozik, Euzebiusz; Selgelid, Michael J

2018-05-01

Zika virus was recognised in 2016 as an important vector-borne cause of congenital malformations and Guillain-Barré syndrome, during a major epidemic in Latin America, centred in Northeastern Brazil. The WHO and Pan American Health Organisation (PAHO), with partner agencies, initiated a coordinated global response including public health intervention and urgent scientific research, as well as ethical analysis as a vital element of policy design. In this paper, we summarise the major ethical issues raised during the Zika epidemic, highlighting the PAHO ethics guidance and the role of ethics in emergency responses, before turning to ethical issues that are yet to be resolved. Zika raises traditional bioethical issues related to reproduction, prenatal diagnosis of serious malformations and unjust disparities in health outcomes. But the epidemic has also highlighted important issues of growing interest in public health ethics, such as the international spread of infectious disease; the central importance of reproductive healthcare in preventing maternal and neonatal morbidity and mortality; diagnostic and reporting biases; vector control and the links between vectors, climate change, and disparities in the global burden of disease. Finally, there are controversies regarding Zika vaccine research and eventual deployment. Zika virus was a neglected disease for over 50 years before the outbreak in Brazil. As it continues to spread, public health agencies should promote gender equity and disease control efforts in Latin America, while preparing for the possibility of a global epidemic. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Drought and immunity determine the intensity of West Nile virus epidemics and climate change impacts.

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Paull, Sara H; Horton, Daniel E; Ashfaq, Moetasim; Rastogi, Deeksha; Kramer, Laura D; Diffenbaugh, Noah S; Kilpatrick, A Marm

2017-02-08

The effect of global climate change on infectious disease remains hotly debated because multiple extrinsic and intrinsic drivers interact to influence transmission dynamics in nonlinear ways. The dominant drivers of widespread pathogens, like West Nile virus, can be challenging to identify due to regional variability in vector and host ecology, with past studies producing disparate findings. Here, we used analyses at national and state scales to examine a suite of climatic and intrinsic drivers of continental-scale West Nile virus epidemics, including an empirically derived mechanistic relationship between temperature and transmission potential that accounts for spatial variability in vectors. We found that drought was the primary climatic driver of increased West Nile virus epidemics, rather than within-season or winter temperatures, or precipitation independently. Local-scale data from one region suggested drought increased epidemics via changes in mosquito infection prevalence rather than mosquito abundance. In addition, human acquired immunity following regional epidemics limited subsequent transmission in many states. We show that over the next 30 years, increased drought severity from climate change could triple West Nile virus cases, but only in regions with low human immunity. These results illustrate how changes in drought severity can alter the transmission dynamics of vector-borne diseases. © 2017 The Author(s).

Moving Beyond Too Little, Too Late: Managing Emerging Infectious Diseases in Wild Populations Requires International Policy and Partnerships

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Jamie Voyles; A. Marm Kilpatrick; James P. Collins; Matthew C. Fisher; Winifred F. Frick; Hamish McCallum; Craig K. R. Willis; David S. Blehert; Kris A. Murray; Robert Puschendorf; Erica Bree Rosenblum; Benjamin M. Bolker; Tina L. Cheng; Kate E. Langwig; Daniel L. Lindner; Mary Toothman; Mark Q. Wilber; Cheryl J. Briggs

2015-01-01

Emerging infectious diseases (EIDs) are on the rise due to multiple factors, including human facilitated movement of pathogens, broad-scale landscape changes, and perturbations to ecological systems (Jones et al. 2008; Fisher et al. 2012). Epidemics in wildlife are problematic because they can lead to pathogen spillover to new host organisms, erode biodiversity and...

Malnutrition and Gastrointestinal and Respiratory Infections in Children: A Public Health Problem

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Rocío Ortiz

2011-04-01

Full Text Available Infectious disease is the major cause of morbidity and mortality in developing countries, particularly in children. Increasing evidence suggests that protein-calorie malnutrition is the underlying reason for the increased susceptibility to infections observed in these areas. Moreover, certain infectious diseases also cause malnutrition, which can result in a vicious cycle. Malnutrition and bacterial gastrointestinal and respiratory infections represent a serious public health problem. The increased incidence and severity of infections in malnourished children is largely due to the deterioration of immune function; limited production and/or diminished functional capacity of all cellular components of the immune system have been reported in malnutrition. In this review, we analyze the cyclical relationship between malnutrition, immune response dysfunction, increased susceptibility to infectious disease, and metabolic responses that further alter nutritional status. The consequences of malnutrition are diverse and included: increased susceptibility to infection, impaired child development, increased mortality rate and individuals who come to function in suboptimal ways.

Malnutrition and Gastrointestinal and Respiratory Infections in Children: A Public Health Problem

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Rodríguez, Leonor; Cervantes, Elsa; Ortiz, Rocío

2011-01-01

Infectious disease is the major cause of morbidity and mortality in developing countries, particularly in children. Increasing evidence suggests that protein-calorie malnutrition is the underlying reason for the increased susceptibility to infections observed in these areas. Moreover, certain infectious diseases also cause malnutrition, which can result in a vicious cycle. Malnutrition and bacterial gastrointestinal and respiratory infections represent a serious public health problem. The increased incidence and severity of infections in malnourished children is largely due to the deterioration of immune function; limited production and/or diminished functional capacity of all cellular components of the immune system have been reported in malnutrition. In this review, we analyze the cyclical relationship between malnutrition, immune response dysfunction, increased susceptibility to infectious disease, and metabolic responses that further alter nutritional status. The consequences of malnutrition are diverse and included: increased susceptibility to infection, impaired child development, increased mortality rate and individuals who come to function in suboptimal ways. PMID:21695035

Post epidemic giardiasis and gastrointestinal symptoms among preschool children in Bergen, Norway. A cross-sectional study

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Eide Geir E

2010-03-01

Full Text Available Abstract Background A surprisingly low number of children became ill with giardiasis during the large waterborne outbreak of Giardia lamblia in Bergen, Norway during autumn 2004. The aim of the present study was to evaluate the prevalence of giardiasis among exposed children one year after an outbreak and compare faecal carriage of Giardia and abdominal symptoms among exposed versus unexposed children one year after the epidemic. Methods Children between 1 and 6 years old were recruited from the local health care centres in Bergen municipality in the period between June 2005 and January 2006. One faecal sample per child was collected and examined for presence of Giardia with a rapid immunoassay antigen test, and parents were asked to answer a questionnaire. A total of 513 children participated, 378 in the group exposed to contaminated water, and 135 in the in the group not exposed. Results In the exposed group eleven children had been treated for giardiasis during the epidemic and none in the unexposed group. Giardia positive faecal tests were found in six children, all in the exposed group, but the difference between the groups did not reach statistical significance. All six Giardia positive children were asymptomatic. No differences were found between the groups regarding demographic data, nausea, vomiting, different odour from stools and eructation. However, the reported scores of abdominal symptoms (diarrhoea, bloating and stomach ache during the last year were higher in the exposed group than in the unexposed group. Conclusions A low prevalence of asymptomatic Giardia infection (1.7% was found among exposed children around one year after the epidemic (1.2% overall prevalence in the study. In the present setting, pre-school children were therefore unlikely to be an important reservoir for continued transmission in the general population.

Executive summary of imported infectious diseases after returning from foreign travel: Consensus document of the Spanish Society for Infectious Diseases and Clinical Microbiology (SEIMC).

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Pérez-Arellano, José Luis; Górgolas-Hernández-Mora, Miguel; Salvador, Fernando; Carranza-Rodríguez, Cristina; Ramírez-Olivencia, Germán; Martín-Echeverría, Esteban; Rodríguez-Guardado, Azucena; Norman, Francesca; Velasco-Tirado, Virginia; Zubero-Sulibarría, Zuriñe; Rojo-Marcos, Gerardo; Muñoz-Gutierrez, José; Ramos-Rincón, José Manuel; Sánchez-Seco-Fariñas, M Paz; Velasco-Arribas, María; Belhassen-García, Moncef; Lago-Nuñez, Mar; Cañas García-Otero, Elías; López-Vélez, Rogelio

2018-03-01

In a global world, knowledge of imported infectious diseases is essential in daily practice, both for the microbiologist-parasitologist and the clinician who diagnoses and treats infectious diseases in returned travelers. Tropical and subtropical countries where there is a greater risk of contracting an infectious disease are among the most frequently visited tourist destinations. The SEIMC considers it appropriate to produce a consensus document that will be useful to primary care physicians as well as specialists in internal medicine, infectious diseases and tropical medicine who help treat travelers returning from tropical and sub-tropical areas with infections. Preventive aspects of infectious diseases and infections imported by immigrants are explicitly excluded here, since they have been dealt with in other SEIMC documents. Various types of professionals (clinicians, microbiologists, and parasitologists) have helped produce this consensus document by evaluating the available evidence-based data in order to propose a series of key facts about individual aspects of the topic. The first section of the document is a summary of some of the general aspects concerning the general assessment of travelers who return home with potential infections. The main second section contains the key facts (causative agents, diagnostic procedures and therapeutic measures) associated with the major infectious syndromes affecting returned travelers [gastrointestinal syndrome (acute or persistent diarrhea); febrile syndrome with no obvious source of infection; localized cutaneous lesions; and respiratory infections]. Finally, the characteristics of special traveler subtypes, such as pregnant women and immunocompromised travelers, are described. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Spatial spread of an epidemic through public transportation systems with a hub.

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Xu, Fei; Connell McCluskey, C; Cressman, Ross

2013-11-01

This article investigates an epidemic spreading among several locations through a transportation system, with a hub connecting these locations. Public transportation is not only a bridge through which infections travel from one location to another but also a place where infections occur since individuals are typically in close proximity to each other due to the limited space in these systems. A mathematical model is constructed to study the spread of an infectious disease through such systems. A variant of the next generation method is proposed and used to provide upper and lower bounds of the basic reproduction number for the model. Our investigation indicates that increasing transportation efficiency, and improving sanitation and ventilation of the public transportation system decrease the chance of an outbreak occurring. Moreover, discouraging unnecessary travel during an epidemic also decreases the chance of an outbreak. However, reducing travel by infectives while allowing susceptibles to travel may not be enough to avoid an outbreak. Copyright © 2013 Elsevier Inc. All rights reserved.

Powerful colloidal silver nanoparticles for the prevention of gastrointestinal bacterial infections

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Le, Anh-Tuan; Le, Thi Tam; Nguyen, Van Quy; Tran, Huy Hoang; Dang, Duc Anh; Tran, Quang Huy; Vu, Dinh Lam

2012-01-01

In this work we have demonstrated a powerful disinfectant ability of colloidal silver nanoparticles (NPs) for the prevention of gastrointestinal bacterial infections. The silver NPs colloid was synthesized by a UV-enhanced chemical precipitation. Two gastrointestinal bacterial strains of Escherichia coli (ATCC 43888-O157:k-:H7) and Vibrio cholerae (O1) were used to verify the antibacterial activity of the as-prepared silver NPs colloid by means of surface disinfection assay in agar plates and turbidity assay in liquid media. Transmission electron microscopy was also employed to analyze the ultrastructural changes of bacterial cells caused by silver NPs. Noticeably, our silver NPs colloid displayed a highly effective bactericidal effect against two tested gastrointestinal bacterial strains at a silver concentration as low as ∼3 mg l −1 . More importantly, the silver NPs colloid showed an enhancement of antibacterial activity and long-lasting disinfectant effect as compared to conventional chloramin B (5%) disinfection agent. These advantages of the as-prepared colloidal silver NPs make them very promising for environmental treatments contaminated with gastrointestinal bacteria and other infectious pathogens. Moreover, the powerful disinfectant activity of silver-containing materials can also help in controlling and preventing further outbreak of diseases. (paper)

Understanding Spatio-Temporal Variability in the Reproduction Ratio of the Bluetongue (BTV-1 Epidemic in Southern Spain (Andalusia in 2007 Using Epidemic Trees.

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S Napp

Full Text Available Andalusia (Southern Spain is considered one of the main routes of introduction of bluetongue virus (BTV into Europe, evidenced by a devastating epidemic caused by BTV-1 in 2007. Understanding the pattern and the drivers of BTV-1 spread in Andalusia is critical for effective detection and control of future epidemics. A long-standing metric for quantifying the behaviour of infectious diseases is the case-reproduction ratio (Rt, defined as the average number of secondary cases arising from a single infected case at time t (for t>0. Here we apply a method using epidemic trees to estimate the between-herd case reproduction ratio directly from epidemic data allowing the spatial and temporal variability in transmission to be described. We then relate this variability to predictors describing the hosts, vectors and the environment to better understand why the epidemic spread more quickly in some regions or periods. The Rt value for the BTV-1 epidemic in Andalusia peaked in July at 4.6, at the start of the epidemic, then decreased to 2.2 by August, dropped below 1 by September (0.8, and by October it had decreased to 0.02. BTV spread was the consequence of both local transmission within established disease foci and BTV expansion to distant new areas (i.e. new foci, which resulted in a high variability in BTV transmission, not only among different areas, but particularly through time, which suggests that general control measures applied at broad spatial scales are unlikely to be effective. This high variability through time was probably due to the impact of temperature on BTV transmission, as evidenced by a reduction in the value of Rt by 0.0041 for every unit increase (day in the extrinsic incubation period (EIP, which is itself directly dependent on temperature. Moreover, within the range of values at which BTV-1 transmission occurred in Andalusia (20.6°C to 29.5°C there was a positive correlation between temperature and Rt values, although the

The First Epidemic and New-emerging Human Fascioliasis in Kermanshah (Western Iran and a Ten-year Follow Up, 1998-2008

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Hossein Hatami

2012-01-01

Conclusions: It was the first case of human fascioliasis in west Iran and was a real epidemic and an emerging infectious disease for this area at that time. The clinical symptoms were less severe compared with other reports. Health education to inhabitants and health care workers can lead to rapid detection of such outbreaks.

Mathematical modeling, analysis and Markov Chain Monte Carlo simulation of Ebola epidemics

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Tulu, Thomas Wetere; Tian, Boping; Wu, Zunyou

Ebola virus infection is a severe infectious disease with the highest case fatality rate which become the global public health treat now. What makes the disease the worst of all is no specific effective treatment available, its dynamics is not much researched and understood. In this article a new mathematical model incorporating both vaccination and quarantine to study the dynamics of Ebola epidemic has been developed and comprehensively analyzed. The existence as well as uniqueness of the solution to the model is also verified and the basic reproduction number is calculated. Besides, stability conditions are also checked and finally simulation is done using both Euler method and one of the top ten most influential algorithm known as Markov Chain Monte Carlo (MCMC) method. Different rates of vaccination to predict the effect of vaccination on the infected individual over time and that of quarantine are discussed. The results show that quarantine and vaccination are very effective ways to control Ebola epidemic. From our study it was also seen that there is less possibility of an individual for getting Ebola virus for the second time if they survived his/her first infection. Last but not least real data has been fitted to the model, showing that it can used to predict the dynamic of Ebola epidemic.

Parallel Epidemics of Community-Associated Methicillin-Resistant Staphylococcus aureus USA300 Infection in North and South America.

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Planet, Paul J; Diaz, Lorena; Kolokotronis, Sergios-Orestis; Narechania, Apurva; Reyes, Jinnethe; Xing, Galen; Rincon, Sandra; Smith, Hannah; Panesso, Diana; Ryan, Chanelle; Smith, Dylan P; Guzman, Manuel; Zurita, Jeannete; Sebra, Robert; Deikus, Gintaras; Nolan, Rathel L; Tenover, Fred C; Weinstock, George M; Robinson, D Ashley; Arias, Cesar A

2015-12-15

The community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) epidemic in the United States is attributed to the spread of the USA300 clone. An epidemic of CA-MRSA closely related to USA300 has occurred in northern South America (USA300 Latin-American variant, USA300-LV). Using phylogenomic analysis, we aimed to understand the relationships between these 2 epidemics. We sequenced the genomes of 51 MRSA clinical isolates collected between 1999 and 2012 from the United States, Colombia, Venezuela, and Ecuador. Phylogenetic analysis was used to infer the relationships and times since the divergence of the major clades. Phylogenetic analyses revealed 2 dominant clades that segregated by geographical region, had a putative common ancestor in 1975, and originated in 1989, in North America, and in 1985, in South America. Emergence of these parallel epidemics coincides with the independent acquisition of the arginine catabolic mobile element (ACME) in North American isolates and a novel copper and mercury resistance (COMER) mobile element in South American isolates. Our results reveal the existence of 2 parallel USA300 epidemics that shared a recent common ancestor. The simultaneous rapid dissemination of these 2 epidemic clades suggests the presence of shared, potentially convergent adaptations that enhance fitness and ability to spread. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Behavioral Responses to Epidemics in an Online Experiment: Using Virtual Diseases to Study Human Behavior

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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. PMID:23326360

Assessing node risk and vulnerability in epidemics on networks

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Rogers, T.

2015-01-01

Which nodes are most vulnerable to an epidemic spreading through a network, and which carry the highest risk of causing a major outbreak if they are the source of the infection? Here we show how these questions can be answered to good approximation using the cavity method. Several curious properties of node vulnerability and risk are explored: some nodes are more vulnerable than others to weaker infections, yet less vulnerable to stronger ones; a node is always more likely to be caught in an outbreak than it is to start one, except when the disease has a deterministic lifetime; the rank order of node risk depends on the details of the distribution of infectious periods.

A generalized-growth model to characterize the early ascending phase of infectious disease outbreaks

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Cécile Viboud

2016-06-01

Conclusions: Our findings reveal significant variation in epidemic growth patterns across different infectious disease outbreaks and highlights that sub-exponential growth is a common phenomenon, especially for pathogens that are not airborne. Sub-exponential growth profiles may result from heterogeneity in contact structures or risk groups, reactive behavior changes, or the early onset of interventions strategies, and consideration of “deceleration parameters” may be useful to refine existing mathematical transmission models and improve disease forecasts.

Transmission of infectious diseases en route to habitat hotspots.

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Benavides, Julio; Walsh, Peter D; Meyers, Lauren Ancel; Raymond, Michel; Caillaud, Damien

2012-01-01

The spread of infectious diseases in wildlife populations is influenced by patterns of between-host contacts. Habitat "hotspots"--places attracting a large numbers of individuals or social groups--can significantly alter contact patterns and, hence, disease propagation. Research on the importance of habitat hotspots in wildlife epidemiology has primarily focused on how inter-individual contacts occurring at the hotspot itself increase disease transmission. However, in territorial animals, epidemiologically important contacts may primarily occur as animals cross through territories of conspecifics en route to habitat hotspots. So far, the phenomenon has received little attention. Here, we investigate the importance of these contacts in the case where infectious individuals keep visiting the hotspots and in the case where these individuals are not able to travel to the hotspot any more. We developed a simulation epidemiological model to investigate both cases in a scenario when transmission at the hotspot does not occur. We find that (i) hotspots still exacerbate epidemics, (ii) when infectious individuals do not travel to the hotspot, the most vulnerable individuals are those residing at intermediate distances from the hotspot rather than nearby, and (iii) the epidemiological vulnerability of a population is the highest when the number of hotspots is intermediate. By altering animal movements in their vicinity, habitat hotspots can thus strongly increase the spread of infectious diseases, even when disease transmission does not occur at the hotspot itself. Interestingly, when animals only visit the nearest hotspot, creating additional artificial hotspots, rather than reducing their number, may be an efficient disease control measure.

Epidemiological bridging by injection drug use drives an early HIV epidemic

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Erik Volz

2010-09-01

Full Text Available The risk of acquiring sexually transmitted infections (STIs depends on individual behavior and the network of risky partnerships in which an individual participates. STI epidemics often spread rapidly and primarily among individuals central to transmission networks; and thus they often defy the mass-action principle since incidence is not proportional to the infectious fraction of the population. Here, we estimate the contact network structure for an Atlanta, Georgia community with heterogeneous sexual and drug-related risk behaviors and build a detailed transmission model for HIV through this population. We show that accurate estimation of epidemic incidence requires careful measurement and inclusion of diverse factors including concurrency (having multiple partners, the duration of partnerships, serosorting (preference for partners with matching disease state, and heterogeneity in the number and kinds of partners. In the focal population, we find that injection drug users (IDUs do not directly cause many secondary infections; yet they bridge the heterosexual and men-who-have-sex-with-men (MSM populations and are thereby indirectly responsible for extensive transmission. Keywords: HIV, Networks, Serosorting, Concurrency

Public health interventions for epidemics: implications for multiple infection waves.

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Wessel, Lindsay; Hua, Yi; Wu, Jianhong; Moghadas, Seyed M

2011-02-25

Epidemics with multiple infection waves have been documented for some human diseases, most notably during past influenza pandemics. While pathogen evolution, co-infection, and behavioural changes have been proposed as possible mechanisms for the occurrence of subsequent outbreaks, the effect of public health interventions remains undetermined. We develop mean-field and stochastic epidemiological models for disease transmission, and perform simulations to show how control measures, such as drug treatment and isolation of ill individuals, can influence the epidemic profile and generate sequences of infection waves with different characteristics. We demonstrate the impact of parameters representing the effectiveness and adverse consequences of intervention measures, such as treatment and emergence of drug resistance, on the spread of a pathogen in the population. If pathogen resistant strains evolve under drug pressure, multiple outbreaks are possible with variability in their characteristics, magnitude, and timing. In this context, the level of drug use and isolation capacity play an important role in the occurrence of subsequent outbreaks. Our simulations for influenza infection as a case study indicate that the intensive use of these interventions during the early stages of the epidemic could delay the spread of disease, but it may also result in later infection waves with possibly larger magnitudes. The findings highlight the importance of intervention parameters in the process of public health decision-making, and in evaluating control measures when facing substantial uncertainty regarding the epidemiological characteristics of an emerging infectious pathogen. Critical factors that influence population health including evolutionary responses of the pathogen under the pressure of different intervention measures during an epidemic should be considered for the design of effective strategies that address short-term targets compatible with long-term disease outcomes.

Economic and Social Factors in Designing Disease Control Strategies for Epidemics on Networks

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Kleczkowski, A.; Dybiec, B.; Gilligan, C. A.

2006-11-01

Models for control of epidemics on local, global and small-world networks are considered, with only partial information accessible about the status of individuals and their connections. The main goal of an effective control measure is to stop the epidemic at a lowest possible cost, including treatment and cost necessary to track the disease spread. We show that delay in detection of infectious individuals and presence of long-range links are the most important factors determining the cost. However, the details of long-range links are usually the least-known element of the social interactions due to their occasional character and potentially short life-span. We show that under some conditions on the probability of disease spread, it is advisable to attempt to track those links, even if this involves additional costs. Thus, collecting some additional knowledge about the network structure might be beneficial to ensure a successful and cost-effective control.

Political drivers of epidemic response: foreign healthcare workers and the 2014 Ebola outbreak.

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Nohrstedt, Daniel; Baekkeskov, Erik

2018-01-01

This study demonstrates that countries responded quite differently to calls for healthcare workers (HCWs) during the Ebola epidemic in West Africa in 2014. Using a new dataset on the scale and timing of national pledges and the deployment of HCWs to states experiencing outbreaks of the virus disease (principally, Guinea, Liberia, and Sierra Leone), it shows that few foreign nations deployed HCWs early, some made pledges but then fulfilled them slowly, and most sent no HCWs at all. To aid understanding of such national responses, the paper reviews five theoretical perspectives that offer potentially competing or complementary explanations of foreign government medical assistance for international public health emergencies. The study systematically validates that countries varied greatly in whether and when they addressed HCW deployment needs during the Ebola crisis of 2014, and offers suggestions for a theory-driven inquiry to elucidate the logics of foreign interventions in critical infectious disease epidemics. © 2018 The Author(s). Disasters © Overseas Development Institute, 2018.

Leveraging social networks for understanding the evolution of epidemics

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2011-01-01

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 predicted by our simulator match

Leveraging social networks for understanding the evolution of epidemics

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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

The Western Africa ebola virus disease epidemic exhibits both global exponential and local polynomial growth rates.

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Chowell, Gerardo; Viboud, Cécile; Hyman, James M; Simonsen, Lone

2015-01-21

While many infectious disease epidemics are initially characterized by an exponential growth in time, we show that district-level Ebola virus disease (EVD) outbreaks in West Africa follow slower polynomial-based growth kinetics over several generations of the disease. We analyzed epidemic growth patterns at three different spatial scales (regional, national, and subnational) of the Ebola virus disease epidemic in Guinea, Sierra Leone and Liberia by compiling publicly available weekly time series of reported EVD case numbers from the patient database available from the World Health Organization website for the period 05-Jan to 17-Dec 2014. We found significant differences in the growth patterns of EVD cases at the scale of the country, district, and other subnational administrative divisions. The national cumulative curves of EVD cases in Guinea, Sierra Leone, and Liberia show periods of approximate exponential growth. In contrast, local epidemics are asynchronous and exhibit slow growth patterns during 3 or more EVD generations, which can be better approximated by a polynomial than an exponential function. The slower than expected growth pattern of local EVD outbreaks could result from a variety of factors, including behavior changes, success of control interventions, or intrinsic features of the disease such as a high level of clustering. Quantifying the contribution of each of these factors could help refine estimates of final epidemic size and the relative impact of different mitigation efforts in current and future EVD outbreaks.

Effects of the infectious period distribution on predicted transitions in childhood disease dynamics.

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Krylova, Olga; Earn, David J D

2013-07-06

The population dynamics of infectious diseases occasionally undergo rapid qualitative changes, such as transitions from annual to biennial cycles or to irregular dynamics. Previous work, based on the standard seasonally forced 'susceptible-exposed-infectious-removed' (SEIR) model has found that transitions in the dynamics of many childhood diseases result from bifurcations induced by slow changes in birth and vaccination rates. However, the standard SEIR formulation assumes that the stage durations (latent and infectious periods) are exponentially distributed, whereas real distributions are narrower and centred around the mean. Much recent work has indicated that realistically distributed stage durations strongly affect the dynamical structure of seasonally forced epidemic models. We investigate whether inferences drawn from previous analyses of transitions in patterns of measles dynamics are robust to the shapes of the stage duration distributions. As an illustrative example, we analyse measles dynamics in New York City from 1928 to 1972. We find that with a fixed mean infectious period in the susceptible-infectious-removed (SIR) model, the dynamical structure and predicted transitions vary substantially as a function of the shape of the infectious period distribution. By contrast, with fixed mean latent and infectious periods in the SEIR model, the shapes of the stage duration distributions have a less dramatic effect on model dynamical structure and predicted transitions. All these results can be understood more easily by considering the distribution of the disease generation time as opposed to the distributions of individual disease stages. Numerical bifurcation analysis reveals that for a given mean generation time the dynamics of the SIR and SEIR models for measles are nearly equivalent and are insensitive to the shapes of the disease stage distributions.

Certainties and Uncertainties Facing Emerging Respiratory Infectious Diseases: Lessons from SARS

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Yee-Chun Chen

2008-06-01

Full Text Available Every emerging infectious disease is a challenge to the whole of mankind. There are uncertainties regarding whether there will be a pandemic, if it will be caused by the highly pathogenic H5N1 influenza virus, when or where it will occur, how imminent or how severe it will be. No one can accurately predict if and when a given virus will become a pandemic virus. Pandemic prevention strategies must be based on preparing for the unexpected and being capable of reacting accordingly. There is growing evidence that infection control measures were helpful in containment of severe acute respiratory syndrome (SARS as well as avian influenza. Compliance of standard infection control measures, intensive promotion of hand and respiratory hygiene, vigilance and triage of patients with febrile illness, and specific infection control measures are key components to contain a highly contagious disease in hospital and to protect healthcare workers, patients and visitors. The importance of standard precautions for any patient and cleaning and disinfection for the healthcare environment cannot be overemphasized. SARS illustrated dramatically the potential of air travel and globalization for the dissemination of an emerging infectious disease. To prevent the potential serious consequences of pandemic influenza, timely implementation of pharmaceutical and non-pharmaceutical interventions locally within the outbreak area is the key to minimizing global spread. Herein, we relate our perspective on useful lessons derived from a review of the SARS epidemic that may be useful to physicians, especially when looking ahead to the next epidemic.

The book of infectious diseases—a living document

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Ashfaq Hasan

2014-07-01

Full Text Available Planet Earth continues to be pillaged by its dominant species. Man’s incursions into forests have resulted in denudation of massive tracts of land, and the displaced inhabitants—vectors carrying exotic infectious agents—have begun to wander deeper into man’s territory. In 1993, in South-Western United States, the Sin Nombre virus (the first Hantavirus normally a pathogen of mice, developed its first taste for Homo sapiens. In 1997, the avian influenza H5N1 virus, jumped species to man. In 2002, a virus of civet cats in the Guangdong Province in Southern China transformed itself into the lethal SARS virus. In 2009, two swine strains, one human strain, and one bird strain of influenza all combined them-selves into a new deadly strain—the H1N1 Swine Flu virus. And only last year, the MERS-Coronavirus became a new player in the changea-ble game of infectious disease. Almost as soon as the world comes stumblingly to terms with one new epidemic, another unleashes itself. Lessons were clearly not learnt after the Ebola epidemic in 1976 which was followed by another major outbreak in Zaire in 1995. This year, confronted with a death-count that ex-ceeds the combined tally of all previous Ebola epidemics, the WHO has finally declared the Ebola outbreak in West Africa as an “extraordinary event” and admitted that it is indeed a “public health risk to other countries.” As a human pathogen, the Ebola virus is four dec-ades old. True to form, the little-affected developed nations—the countries with the resources to tackle emerging infections—have taken no great interest in the matter. Forty precious years have ticked by. The CDC admits: “We do not know how to treat Ebola or vaccinate against it—and it will be a long time before we do.” As with the other major infectious killers that ravage the developing world, the profit margin for a drug against Ebola is slender. The Zaire Ebola virus though, is special—it is the most deadly

Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004.

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Tinker, Sarah C; Moe, Christine L; Klein, Mitchel; Flanders, W Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E

2010-01-01

The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the United States, and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240,000 emergency department visits for gastrointestinal illness during 1993-2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants.

Infectious disease modeling a hybrid system approach

CERN Document Server

Liu, Xinzhi

2017-01-01

This volume presents infectious diseases modeled mathematically, taking seasonality and changes in population behavior into account, using a switched and hybrid systems framework. The scope of coverage includes background on mathematical epidemiology, including classical formulations and results; a motivation for seasonal effects and changes in population behavior, an investigation into term-time forced epidemic models with switching parameters, and a detailed account of several different control strategies. The main goal is to study these models theoretically and to establish conditions under which eradication or persistence of the disease is guaranteed. In doing so, the long-term behavior of the models is determined through mathematical techniques from switched systems theory. Numerical simulations are also given to augment and illustrate the theoretical results and to help study the efficacy of the control schemes.

Clinical manifestations of gastrointestinal form of food allergy in children and approaches to its diagnosis

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Yu.R. Chernysh

2017-08-01

Full Text Available Gastrointestinal food allergy is caused by the development of allergic inflammation in the mucosa of the gastrointestinal tract. The mechanisms of this inflammation are immunogflobulin E (IgE-mediated (oral allergic syndrome, immediate gastrointestinal hypersensitivity, non-IgE-mediated (protein-induced enterocolitis syndrome, protein-induced enteropathy, protein-induced allergic proctocolitis and mixed IgE- and non-IgE-mediated reactions (eosinophilic esophagitis, eosinophilic gastritis and eosinophilic gastroenteritis. Gastrointestinal manifestations of food allergy are also combined with symptoms of atopic diseases, more often with atopic dermatitis, urticaria and angioedema. Clinical manifestations of allergic lesions of the gastrointestinal tract are different and non-specific. Common signs of gastrointestinal allergy include: vomiting (occurs from a few minutes to 4–6 hours after eating; сolic (immediately or several hours after eating; constipation; diarrhea; refusal of food (from a specific product or complete refusal to eat; abdominal pain; flatulence, the presence of mucus and eosinophils in the stool; poor appetite; headache. Differential diagnosis of gastrointestinal food allergy should be carried out with diseases such as disease and abnormalities in the development of the digestive system, mental and metabolic disorders, intoxications, infectious diseases, pancreatic endocrine gland failure, celiac disease, cystic fibrosis, immunodeficiencies, disaccharidic insufficiency, side effects of medications, endocrine pathology, irritable bowel syndrome. Methods for diagnosing gastrointestinal allergy, which currently exist, are limited and imperfect. This requires further scientific researches aimed at timely detection of this pathology, prevention in genetically predisposed children, development of optimal diagnostic algorithms, prevention of the progression of clinical manifestations, the choice of individual diet therapy and

Advances in Integrative Nanomedicine for Improving Infectious Disease Treatment in Public Health.

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Bell, Iris R; Schwartz, Gary E; Boyer, Nancy N; Koithan, Mary; Brooks, Audrey J

2013-04-01

Infectious diseases present public health challenges worldwide. An emerging integrative approach to treating infectious diseases is using nanoparticle (NP) forms of traditional and alternative medicines. Advantages of nanomedicine delivery methods include better disease targeting, especially for intracellular pathogens, ability to cross membranes and enter cells, longer duration drug action, reduced side effects, and cost savings from lower doses. We searched Pubmed articles in English with keywords related to nanoparticles and nanomedicine. Nanotechnology terms were also combined with keywords for drug delivery, infectious diseases, herbs, antioxidants, homeopathy, and adaptation. NPs are very small forms of material substances, measuring 1-100 nanometers along at least one dimension. Compared with bulk forms, NPs' large ratio of surface-area-to-volume confers increased reactivity and adsorptive capacity, with unique electromagnetic, chemical, biological, and quantum properties. Nanotechnology uses natural botanical agents for green manufacturing of less toxic NPs. Nanoparticle herbs and nutriceuticals can treat infections via improved bioavailability and antiinflammatory, antioxidant, and immunomodulatory effects. Recent studies demonstrate that homeopathic medicines may contain source and/or silica nanoparticles because of their traditional manufacturing processes. Homeopathy, as a form of nanomedicine, has a promising history of treating epidemic infectious diseases, including malaria, leptospirosis and HIV/AIDS, in addition to acute upper respiratory infections. Adaptive changes in the host's complex networks underlie effects. Nanomedicine is integrative, blending modern technology with natural products to reduce toxicity and support immune function. Nanomedicine using traditional agents from alternative systems of medicine can facilitate progress in integrative public health approaches to infectious diseases.

Adding fuel to the fire: alcohol's effect on the HIV epidemic in Sub-Saharan Africa.

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Hahn, Judith A; Woolf-King, Sarah E; Muyindike, Winnie

2011-09-01

Alcohol consumption adds fuel to the HIV epidemic in sub-Saharan Africa (SSA). SSA has the highest prevalence of HIV infection and heavy episodic drinking in the world. Alcohol consumption is associated with behaviors such as unprotected sex and poor medication adherence, and biological factors such as increased susceptibility to infection, comorbid conditions, and infectiousness, which may synergistically increase HIV acquisition and onward transmission. Few interventions to decrease alcohol consumption and alcohol-related sexual risk behaviors have been developed or implemented in SSA, and few HIV or health policies or services in SSA address alcohol consumption. Structural interventions, such as regulating the availability, price, and advertising of alcohol, are challenging to implement due to the preponderance of homemade alcohol and beverage industry resistance. This article reviews the current knowledge on how alcohol impacts the HIV epidemic in SSA, summarizes current interventions and policies, and identifies areas for increased research and development.

Hepatic lesions that mimic metastasis on radiological imaging during chemotherapy for gastrointestinal malignancy: Recent updates

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You, Sung Hye; Park, Beom Jin; Kim, Yeul Hong [Anam Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

2017-06-15

During chemotherapy in patients with gastrointestinal malignancy, the hepatic lesions may occur as chemotherapy-induced lesions or tumor-associated lesions, with exceptions for infectious conditions and other incidentalomas. Focal hepatic lesions arising from chemotherapy-induced hepatopathies (such as chemotherapy-induced sinusoidal injury and steatosis) and tumor-associated eosinophilic abscess should be considered a mimicker of metastasis in patients with gastrointestinal malignancy. Accumulating evidence suggests that chemotherapy for gastrointestinal malignancy in the liver has roles in both the therapeutic effects for hepatic metastasis and injury to the non-tumor bearing hepatic parenchyma. In this article, we reviewed the updated concept of chemotherapy-induced hepatopathies and tumor-associated eosinophilic abscess in the liver, focusing on the pathological and radiological findings. Awareness of the causative chemo-agent, pathophysiology, and characteristic imaging findings of these mimickers is critical for accurate diagnosis and avoidance of unnecessary exposure of the patient to invasive tissue-based diagnosis and operation.

Genealogical evidence for epidemics of selfish genes.

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Ingvarsson, Par K; Taylor, Douglas R

2002-08-20

Some genetic elements spread infectiously in populations by increasing their rate of genetic transmission at the expense of other genes in the genome. These so-called selfish genetic elements comprise a substantial portion of eukaryotic genomes and have long been viewed as a potent evolutionary force. Despite this view, little is known about the evolutionary history of selfish genetic elements in natural populations, or their genetic effects on other portions of the genome. Here we use nuclear and chloroplast gene genealogies in two species of Silene to show the historical pattern of selection on a well known selfish genetic element, cytoplasmic male sterility. We provide evidence that evolution of cytoplasmic male sterility has been characterized by frequent turnovers of mutations in natural populations, thus supporting an epidemic model for the evolution of selfish genes, where new mutations repeatedly arise and rapidly sweep through populations.

Epidemic typhus.

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Bechah, Yassina; Capo, Christian; Mege, Jean-Louis; Raoult, Didier

2008-07-01

Epidemic typhus is transmitted to human beings by the body louse Pediculus humanus corporis. The disease is still considered a major threat by public-health authorities, despite the efficacy of antibiotics, because poor sanitary conditions are conducive to louse proliferation. Until recently, Rickettsia prowazekii, the causal agent, was thought to be confined to human beings and their body lice. Since 1975, R prowazekii infection in human beings has been related to contact with the flying squirrel Glaucomys volans in the USA. Moreover, Brill-Zinsser disease, a relapsed form of epidemic typhus that appears as sporadic cases many years after the initial infection, is unrelated to louse infestation. Stress or a waning immune system are likely to reactivate this earlier persistent infection, which could be the source of new epidemics when conditions facilitate louse infestation. Finally, R prowazekii is a potential category B bioterrorism agent, because it is stable in dried louse faeces and can be transmitted through aerosols. An increased understanding of the pathogenesis of epidemic typhus may be useful for protection against this bacterial threat.

How to make epidemiological training infectious.

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Steve E Bellan

Full Text Available Modern infectious disease epidemiology builds on two independently developed fields: classical epidemiology and dynamical epidemiology. Over the past decade, integration of the two fields has increased in research practice, but training options within the fields remain distinct with few opportunities for integration in the classroom. The annual Clinic on the Meaningful Modeling of Epidemiological Data (MMED at the African Institute for Mathematical Sciences has begun to address this gap. MMED offers participants exposure to a broad range of concepts and techniques from both epidemiological traditions. During MMED 2010 we developed a pedagogical approach that bridges the traditional distinction between classical and dynamical epidemiology and can be used at multiple educational levels, from high school to graduate level courses. The approach is hands-on, consisting of a real-time simulation of a stochastic outbreak in course participants, including realistic data reporting, followed by a variety of mathematical and statistical analyses, stemming from both epidemiological traditions. During the exercise, dynamical epidemiologists developed empirical skills such as study design and learned concepts of bias while classical epidemiologists were trained in systems thinking and began to understand epidemics as dynamic nonlinear processes. We believe this type of integrated educational tool will prove extremely valuable in the training of future infectious disease epidemiologists. We also believe that such interdisciplinary training will be critical for local capacity building in analytical epidemiology as Africa continues to produce new cohorts of well-trained mathematicians, statisticians, and scientists. And because the lessons draw on skills and concepts from many fields in biology--from pathogen biology, evolutionary dynamics of host--pathogen interactions, and the ecology of infectious disease to bioinformatics, computational biology, and

Pains and Gains from China's Experiences with Emerging Epidemics: From SARS to H7N9

OpenAIRE

Wei, Pengfei; Cai, Zelang; Hua, Jinwen; Yu, Weijia; Chen, Jiajie; Kang, Kang; Qiu, Congling; Ye, Lanlan; Hu, Jiayun; Ji, Kunmei

2016-01-01

Over the recent decades, China experienced several emerging virus outbreaks including those caused by the severe acute respiratory syndrome- (SARS-) coronavirus (Cov), H5N1 virus, and H7N9 virus. The SARS tragedy revealed faults in China’s infectious disease prevention system, propelling the Chinese government to enact reforms that enabled better combating of the subsequent H1N1 and H7N9 avian flu epidemics. The system is buttressed by three fundamental, mutually reinforcing components: (1) e...

Epidemics spreading in interconnected complex networks

International Nuclear Information System (INIS)

Wang, Y.; Xiao, G.

2012-01-01

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.

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.

INFECTIOUS DISEASES IN CHILDREN: THE ROLE IN THE OCCURRENCE OF SOMATIC PATHOLOGY

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L. N. Mazankova

2013-01-01

Full Text Available The article examines the relationship of infectious diseases, especially opportunistic and viral infections, with the formation of chronic and physical illness. Scientific meta-analysis of the effect of infections on the start of autoimmune disease, chronic diseases of broncho-pulmonary and cardiovascular system, gastrointestinal tract, urinary and other systems is carried out. Special attention is given to the role of fetal viral infection in the development of congenital malformations and intrauterine pathology. The article discusses the prevention measures taken for controlling certain somatic diseases.

How to analytically characterize the epidemic threshold within the coupled disease-behavior systems?. Comment on "Coupled disease-behavior dynamics on complex networks: A review" by Z. Wang et al.

Science.gov (United States)

Xia, Cheng-Yi; Ding, Shuai; Sun, Shi-Wen; Wang, Li; Gao, Zhong-Ke; Wang, Juan

2015-12-01

As is well known, outbreak of epidemics may drive the human population to take some necessary measures to protect themselves from not being infected by infective ones, these precautions in turn will also keep from the further spreading of infectious diseases among the population. Thus, to fully comprehend the epidemic spreading behavior within real-world systems, the interplay between disease dynamics and human behavioral and social dynamics needs to be considered simultaneously, such that some effective containment-measures can be successfully developed [1-3].

Oscillations in epidemic models with spread of awareness.

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Just, Winfried; Saldaña, Joan; Xin, Ying

2018-03-01

We study ODE models of epidemic spreading with a preventive behavioral response that is triggered by awareness of the infection. Previous studies of such models have mostly focused on the impact of the response on the initial growth of an outbreak and the existence and location of endemic equilibria. Here we study the question whether this type of response is sufficient to prevent future flare-ups from low endemic levels if awareness is assumed to decay over time. In the ODE context, such flare-ups would translate into sustained oscillations with significant amplitudes. Our results show that such oscillations are ruled out in Susceptible-Aware-Infectious-Susceptible models with a single compartment of aware hosts, but can occur if we consider two distinct compartments of aware hosts who differ in their willingness to alert other susceptible hosts.

Dynamics of an epidemic model with quarantine on scale-free networks

Science.gov (United States)

Kang, Huiyan; Liu, Kaihui; Fu, Xinchu

2017-12-01

Quarantine strategies are frequently used to control or reduce the transmission risks of epidemic diseases such as SARS, tuberculosis and cholera. In this paper, we formulate a susceptible-exposed-infected-quarantined-recovered model on a scale-free network incorporating the births and deaths of individuals. Considering that the infectivity is related to the degrees of infectious nodes, we introduce quarantined rate as a function of degree into the model, and quantify the basic reproduction number, which is shown to be dependent on some parameters, such as quarantined rate, infectivity and network structures. A theoretical result further indicates the heterogeneity of networks and higher infectivity will raise the disease transmission risk while quarantine measure will contribute to the prevention of epidemic spreading. Meanwhile, the contact assumption between susceptibles and infectives may impact the disease transmission. Furthermore, we prove that the basic reproduction number serves as a threshold value for the global stability of the disease-free and endemic equilibria and the uniform persistence of the disease on the network by constructing appropriate Lyapunov functions. Finally, some numerical simulations are illustrated to perform and complement our analytical results.

Review of the role of probiotics in gastrointestinal diseases in adults.

Science.gov (United States)

Sebastián Domingo, Juan José

Probiotics may act as biological agents that modify the intestinal microbiota and certain cytokine profiles, which can lead to an improvement in certain gastrointestinal diseases. To conduct a review of the evidence of the role of probiotics in certain gastrointestinal diseases in adults. Review conducted using appropriate descriptors, filters and limits in the PubMed database (MEDLINE). The MeSH terms used were Probiotics [in the title] AND Gastrointestinal Diseases, with the following limits or filters: Types of study: Systematic Reviews, Meta-Analysis, Guideline, Practice Guideline, Consensus Development Conference (and Consensus Development Conference NIH), Randomized Controlled Trial, Controlled Clinical Trial and Clinical Trial; age: adults (19 or older); language: English and Spanish; in humans, and with at least one abstract. Full texts of all the Systematic Reviews and meta-analyses directly related to the review's objective were obtained, as well as the Randomised Controlled Trials of the studies that were considered relevant and of sufficient quality for this review. Certain probiotics, different for each process, have proven to be effective and beneficial in cases of acute infectious diarrhoea, antibiotic-associated diarrhoea, Clostridium difficile-associated diarrhoea, pouchitis and Helicobacter pylori infection eradication. Although some probiotics have not demonstrated any benefit, there are certain gastrointestinal diseases in which the use of probiotics, true biological agents, can be recommended. Copyright © 2017 Elsevier España, S.L.U., AEEH y AEG. All rights reserved.

Natural Disasters, Corpses and the Risk of Infectious Diseases

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JM Conly

2005-01-01

Full Text Available The recent occurrence of the category 4 Hurricane Katrina devastated the United States? Gulf Coast. The hurricane caused widespread destruction and flooding, and left hundreds of thousands of people homeless. The mounting death toll was reported at almost 300 deaths as of September 8, 2005 (1,2. The unfolding events and high death toll have left an unusual situation in which there are many decomposing corpses either lying on the streets or floating in the flood waters. The presence of these corpses in open settings, such as in public places and in the water that has inundated much of the city of New Orleans, naturally raises concerns about the occurrence of infectious disease epidemics (3. In the aftermath of large natural disasters, instinctive uncertainties arise among workers and the general population with respect to the appropriate handling and disposal of dead bodies and human remains. Given the recent occurrence of Hurricane Katrina as a large natural disaster and the unprecedented setting of the numerous corpses requiring disposal, it was considered timely to review the infectious disease risks associated with the handling of dead bodies.

Disease Extinction Versus Persistence in Discrete-Time Epidemic Models.

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van den Driessche, P; Yakubu, Abdul-Aziz

2018-04-12

We focus on discrete-time infectious disease models in populations that are governed by constant, geometric, Beverton-Holt or Ricker demographic equations, and give a method for computing the basic reproduction number, [Formula: see text]. When [Formula: see text] and the demographic population dynamics are asymptotically constant or under geometric growth (non-oscillatory), we prove global asymptotic stability of the disease-free equilibrium of the disease models. Under the same demographic assumption, when [Formula: see text], we prove uniform persistence of the disease. We apply our theoretical results to specific discrete-time epidemic models that are formulated for SEIR infections, cholera in humans and anthrax in animals. Our simulations show that a unique endemic equilibrium of each of the three specific disease models is asymptotically stable whenever [Formula: see text].

Rhodotorula Endogenous Endophthalmitis: A Novel Harbinger of the Injection Drug Epidemic in the United States

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Preston M. Luong

2017-01-01

Full Text Available Endogenous endophthalmitis is a rare but feared infectious ocular complication of injection drug use (IDU. The recent opioid epidemic in the United States threatens to increase the incidence of this disease. We report the first case of endogenous endophthalmitis in the United States caused by the emerging fungal pathogen Rhodotorula in an injection drug user which led to no light perception vision (NLP. Worldwide experience with Rhodotorula endogenous endophthalmitis is limited, but existing cases suggest infection by this particular fungal genus has a grim prognosis.

Infectious endocarditis caused by Escherichia coli

DEFF Research Database (Denmark)

Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

2011-01-01

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad......-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra......-intestinal pathogenic E. coli (ExPEC) are able to colonize tissue outside the gastrointestinal tract and contain a variety of virulence factors that may enable the pathogens to invade and induce infections in the cardiac endothelia. In these cases echocardiography as the imaging technology is of paramount importance...

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....

Poverty, global health, and infectious disease: lessons from Haiti and Rwanda.

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Alsan, Marcella M; Westerhaus, Michael; Herce, Michael; Nakashima, Koji; Farmer, Paul E

2011-09-01

Poverty and infectious diseases interact in complex ways. Casting destitution as intractable, or epidemics that afflict the poor as accidental, erroneously exonerates us from responsibility for caring for those most in need. Adequately addressing communicable diseases requires a biosocial appreciation of the structural forces that shape disease patterns. Most health interventions in resource-poor settings could garner support based on cost/benefit ratios with appropriately lengthy time horizons to capture the return on health investments and an adequate accounting of externalities; however, such a calculus masks the suffering of inaction and risks eroding the most powerful incentive to act: redressing inequality. Copyright © 2011 Elsevier Inc. All rights reserved.

Integrated travel network model for studying epidemics: Interplay between journeys and epidemic

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Ruan, Zhongyuan; Wang, Chaoqing; Ming Hui, Pak; Liu, Zonghua

2015-06-01

The ease of travelling between cities has contributed much to globalization. Yet, it poses a threat on epidemic outbreaks. It is of great importance for network science and health control to understand the impact of frequent journeys on epidemics. We stress that a new framework of modelling that takes a traveller’s viewpoint is needed. Such integrated travel network (ITN) model should incorporate the diversity among links as dictated by the distances between cities and different speeds of different modes of transportation, diversity among nodes as dictated by the population and the ease of travelling due to infrastructures and economic development of a city, and round-trip journeys to targeted destinations via the paths of shortest travel times typical of human journeys. An example is constructed for 116 cities in China with populations over one million that are connected by high-speed train services and highways. Epidemic spread on the constructed network is studied. It is revealed both numerically and theoretically that the traveling speed and frequency are important factors of epidemic spreading. Depending on the infection rate, increasing the traveling speed would result in either an enhanced or suppressed epidemic, while increasing the traveling frequency enhances the epidemic spreading.

Myalgic encephalomyelitis, chronic fatigue syndrome: An infectious disease.

Science.gov (United States)

Underhill, R A

2015-12-01

The etiology of myalgic encephalomyelitis also known as chronic fatigue syndrome or ME/CFS has not been established. Controversies exist over whether it is an organic disease or a psychological disorder and even the existence of ME/CFS as a disease entity is sometimes denied. Suggested causal hypotheses have included psychosomatic disorders, infectious agents, immune dysfunctions, autoimmunity, metabolic disturbances, toxins and inherited genetic factors. Clinical, immunological and epidemiological evidence supports the hypothesis that: ME/CFS is an infectious disease; the causal pathogen persists in patients; the pathogen can be transmitted by casual contact; host factors determine susceptibility to the illness; and there is a population of healthy carriers, who may be able to shed the pathogen. ME/CFS is endemic globally as sporadic cases and occasional cluster outbreaks (epidemics). Cluster outbreaks imply an infectious agent. An abrupt flu-like onset resembling an infectious illness occurs in outbreak patients and many sporadic patients. Immune responses in sporadic patients resemble immune responses in other infectious diseases. Contagion is shown by finding secondary cases in outbreaks, and suggested by a higher prevalence of ME/CFS in sporadic patients' genetically unrelated close contacts (spouses/partners) than the community. Abortive cases, sub-clinical cases, and carrier state individuals were found in outbreaks. The chronic phase of ME/CFS does not appear to be particularly infective. Some healthy patient-contacts show immune responses similar to patients' immune responses, suggesting exposure to the same antigen (a pathogen). The chronicity of symptoms and of immune system changes and the occurrence of secondary cases suggest persistence of a causal pathogen. Risk factors which predispose to developing ME/CFS are: a close family member with ME/CFS; inherited genetic factors; female gender; age; rest/activity; previous exposure to stress or toxins

Lessons from the Ebola Outbreak: Action Items for Emerging Infectious Disease Preparedness and Response.

Science.gov (United States)

Jacobsen, Kathryn H; Aguirre, A Alonso; Bailey, Charles L; Baranova, Ancha V; Crooks, Andrew T; Croitoru, Arie; Delamater, Paul L; Gupta, Jhumka; Kehn-Hall, Kylene; Narayanan, Aarthi; Pierobon, Mariaelena; Rowan, Katherine E; Schwebach, J Reid; Seshaiyer, Padmanabhan; Sklarew, Dann M; Stefanidis, Anthony; Agouris, Peggy

2016-03-01

As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future epidemics. Our interdisciplinary team identified key lessons learned from the Ebola outbreak that can be clustered into three areas: environmental conditions related to early warning systems, host characteristics related to public health, and agent issues that can be addressed through the laboratory sciences. In particular, we need to increase zoonotic surveillance activities, implement more effective ecological health interventions, expand prediction modeling, support medical and public health systems in order to improve local and international responses to epidemics, improve risk communication, better understand the role of social media in outbreak awareness and response, produce better diagnostic tools, create better therapeutic medications, and design better vaccines. This list highlights research priorities and policy actions the global community can take now to be better prepared for future emerging infectious disease outbreaks that threaten global public health and security.

Cyber Epidemic Models with Dependences

OpenAIRE

Xu, Maochao; Da, Gaofeng; Xu, Shouhuai

2016-01-01

Studying models of cyber epidemics over arbitrary complex networks can deepen our understanding of cyber security from a whole-system perspective. In this paper, we initiate the investigation of cyber epidemic models that accommodate the {\\em dependences} between the cyber attack events. Due to the notorious difficulty in dealing with such dependences, essentially all existing cyber epidemic models have assumed them away. Specifically, we introduce the idea of Copulas into cyber epidemic mode...

Networking of Public Health Microbiology Laboratories Bolsters Europe’s Defenses against Infectious Diseases

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Barbara Albiger

2018-02-01

Full Text Available In an era of global health threats caused by epidemics of infectious diseases and rising multidrug resistance, microbiology laboratories provide essential scientific evidence for risk assessment, prevention, and control. Microbiology has been at the core of European infectious disease surveillance networks for decades. Since 2010, these networks have been coordinated by the European Centre for Disease Prevention and Control (ECDC. Activities delivered in these networks include harmonization of laboratory diagnostic, antimicrobial susceptibility and molecular typing methods, multicentre method validation, technical capacity mapping, training of laboratory staff, and continuing quality assessment of laboratory testing. Cooperation among the European laboratory networks in the past 7 years has proved successful in strengthening epidemic preparedness by enabling adaptive capabilities for rapid detection of emerging pathogens across Europe. In partnership with food safety authorities, international public health agencies and learned societies, ECDC-supported laboratory networks have also progressed harmonization of routinely used antimicrobial susceptibility and molecular typing methods, thereby significantly advancing the quality, comparability and precision of microbiological information gathered by ECDC for surveillance for zoonotic diseases and multidrug-resistant pathogens in Europe. ECDC continues to act as a catalyst for sustaining continuous practice improvements and strengthening wider access to laboratory capacity across the European Union. Key priorities include optimization and broader use of rapid diagnostics, further integration of whole-genome sequencing in surveillance and electronic linkage of laboratory and public health systems. This article highlights some of the network contributions to public health in Europe and the role that ECDC plays managing these networks.

DRINKING WATER TURBIDITY AND EMERGENCY DEPARTMENT VISITS FOR GASTROINTESTINAL ILLNESS IN ATLANTA, 1993 – 2004

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Tinker, Sarah C.; Moe, Christine L.; Klein, Mitchel; Flanders, W. Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E.

2013-01-01

Background The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well-understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the U.S., and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. Methods We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240 000 emergency department visits for gastrointestinal illness during 1993–2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. Results For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. This association was not observed for all treatment plants in plant-specific analyses. Conclusions Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants. PMID:18941478

Immunophenotyping in post-giardiasis functional gastrointestinal disease and chronic fatigue syndrome

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Hanevik Kurt

2012-10-01

Full Text Available Abstract Background A Giardia outbreak was associated with development of post-infectious functional gastrointestinal disorders (PI-FGID and chronic fatigue syndrome (PI-CFS. Markers of immune dysfunction have given conflicting results in CFS and FGID patient populations. The aim of this study was to evaluate a wide selection of markers of immune dysfunction in these two co-occurring post-infectious syndromes. Methods 48 patients, reporting chronic fatigue in a questionnaire study, were clinically evaluated five years after the outbreak and grouped according to Fukuda criteria for CFS (n=19 and idiopathic chronic fatigue (n=5 and Rome II criteria for FGIDs (n=54. 22 Giardia exposed non-fatigued individuals and 10 healthy unexposed individuals were recruited as controls. Peripheral blood lymphocyte subsets were analyzed by flow cytometry. Results In peripheral blood we found significantly higher CD8 T-cell levels in PI-FGID, and significantly lower NK-cell levels in PI-CFS patients. Severity of abdominal and fatigue symptoms correlated negatively with NK-cell levels. A tendency towards lower T-cell CD26 expression in FGID was seen. Conclusion Patients with PI-CFS and/or PI-FGID 5 years after Giardia lamblia infection showed alterations in NK-cell and CD8-cell populations suggesting a possible immunological abnormality in these conditions. We found no significant changes in other markers examined in this well-defined group of PI-CFS and PI-FGID elicited by a gastrointestinal infection. Controlling for co-morbid conditions is important in evaluation of CFS-biomarkers.

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.

[Epidemic of Staphylococcus aureus nosocomial infections resistant to methicillin in a maternity ward].

Science.gov (United States)

Le Coq, M; Simon, I; Sire, C; Tissot-Guerraz, F; Fournier, L; Aho, S; Noblot, G; Reverdy, M E; Françoise, M

2001-02-01

Methicillin-resistant Staphylococcus aureus (MRSA) nosocomial infections frequently occur in the hospital environment, but their incidence is less often observed in neonates. In the present investigation, seventeen cases were recorded over a nine-week period (two cases per week). Pulsed field gradient gel electrophoresis confirmed the clonal character of the strain. The hypothesis of manually-transmitted infection due to contamination from multiple sources was reinforced by the fact the epidemic persisted in spite of the elimination of the main human infectious source and an absence of risk factors determined by the case-control study. The role of environmental factors in the persistence of this outbreak of MRSA infection has been considered.

The epidemic profiles of intensive care units in Hospital oncologico SOLCA, Quito

International Nuclear Information System (INIS)

Caballero, Henry; Marin, Karina; Gonzalez, Alba; Vega, Mireya; Castelo, Marcelo; Trujillo Cruz, Freddy

2006-01-01

The epidemic profiles of intensive care units are very few and they have not been published recently, punctual epidemic studies of morbidity, mortality and quality controls of intensive care exist, but we could not find the profiles of the oncological units. Since the establishment of the intensive care unit of Oncological Hospital Solca in Quito city. It was not possible to find any epidemiological profile of this unit because it is important to know their morbidity rates, mortality, the main complications and to relate these with the study of the index prognostic, to plan the annual operative programs and the innovations according to the specific necessities, justified by realities studied, to observe the organic shortcoming that in critical patients are present, for a planning adapted in the outlines with the rational use of medication, since the critical users have specific characteristics especially in the infectious processes, due to their immunosuppression condition and for the chemotherapy administration and the radiotherapy, oncological patient for their condition they are poly medicates and it requires the use of interventionist processes, that triggers major risks of complications and infection with opportunist germs. (The author)

The GLEaMviz computational tool, a publicly available software to explore realistic epidemic spreading scenarios at the global scale

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Quaggiotto Marco

2011-02-01

Full Text Available Abstract Background Computational models play an increasingly important role in the assessment and control of public health crises, as demonstrated during the 2009 H1N1 influenza pandemic. Much research has been done in recent years in the development of sophisticated data-driven models for realistic computer-based simulations of infectious disease spreading. However, only a few computational tools are presently available for assessing scenarios, predicting epidemic evolutions, and managing health emergencies that can benefit a broad audience of users including policy makers and health institutions. Results We present "GLEaMviz", a publicly available software system that simulates the spread of emerging human-to-human infectious diseases across the world. The GLEaMviz tool comprises three components: the client application, the proxy middleware, and the simulation engine. The latter two components constitute the GLEaMviz server. The simulation engine leverages on the Global Epidemic and Mobility (GLEaM framework, a stochastic computational scheme that integrates worldwide high-resolution demographic and mobility data to simulate disease spread on the global scale. The GLEaMviz design aims at maximizing flexibility in defining the disease compartmental model and configuring the simulation scenario; it allows the user to set a variety of parameters including: compartment-specific features, transition values, and environmental effects. The output is a dynamic map and a corresponding set of charts that quantitatively describe the geo-temporal evolution of the disease. The software is designed as a client-server system. The multi-platform client, which can be installed on the user's local machine, is used to set up simulations that will be executed on the server, thus avoiding specific requirements for large computational capabilities on the user side. Conclusions The user-friendly graphical interface of the GLEaMviz tool, along with its high level

Multiple routes transmitted epidemics on multiplex networks

International Nuclear Information System (INIS)

Zhao, Dawei; Li, Lixiang; Peng, Haipeng; Luo, Qun; Yang, Yixian

2014-01-01

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.

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.

Risk Prevention of Spreading Emerging Infectious Diseases Using a HybridCrowdsensing Paradigm, Optical Sensors, and Smartphone.

Science.gov (United States)

Edoh, Thierry

2018-04-10

The risk of spreading diseases within (ad-hoc)crowds and the need to pervasively screen asymptomatic individuals to protect the population against emerging infectious diseases, request permanentcrowd surveillance., particularly in high-risk regions. Thecase of Ebola epidemic in West Africa in recent years has shown the need for pervasive screening. The trend today in diseases surveillance is consisting of epidemiological data collection about emerging infectious diseases using social media, wearable sensors systems, or mobile applications and data analysis. This approach presents various limitations. This paper proposes a novel approach for diseases monitoring and risk prevention of spreading infectious diseases. The proposed approach, aiming at overcoming the limitation of existing disease surveillance approaches, combines the hybrid crowdsensing paradigm with sensing individuals' bio-signals using optical sensors for monitoring any risks of spreading emerging infectious diseases in any (ad-hoc) crowds. A proof-of-concept has been performed using a drone armed with a cat s60 smartphone featuring a Forward Looking Infra-Red (FLIR) camera. According to the results of the conducted experiment, the concept has the potential to improve the conventional epidemiological data collection. The measurement is reliable, and the recorded data are valid. The measurement error rates are about 8%.

Dynamical Analysis of SIR Epidemic Models with Distributed Delay

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Wencai Zhao

2013-01-01

Full Text Available SIR epidemic models with distributed delay are proposed. Firstly, the dynamical behaviors of the model without vaccination are studied. Using the Jacobian matrix, the stability of the equilibrium points of the system without vaccination is analyzed. The basic reproduction number R is got. In order to study the important role of vaccination to prevent diseases, the model with distributed delay under impulsive vaccination is formulated. And the sufficient conditions of globally asymptotic stability of “infection-free” periodic solution and the permanence of the model are obtained by using Floquet’s theorem, small-amplitude perturbation skills, and comparison theorem. Lastly, numerical simulation is presented to illustrate our main conclusions that vaccination has significant effects on the dynamical behaviors of the model. The results can provide effective tactic basis for the practical infectious disease prevention.

Politics and pellagra: the epidemic of pellagra in the U.S. in the early twentieth century.

Science.gov (United States)

Bollet, A. J.

1992-01-01

The epidemic of pellagra in the first half of this century at its peak produced at least 250,000 cases and caused 7,000 deaths a year for several decades in 15 southern states. It also filled hospital wards in other states, which had a similar incidence but refused to report their cases. Political influences interfered, not only with surveillance of the disease, but also in its study, recognition of its cause, and the institution of preventive measures when they became known. Politicians and the general public felt that it was more acceptable for pellagra to be infectious than for it to be a form of malnutrition, a result of poverty and thus an embarrassing social problem. Retrospectively, a change in the method of milling cornmeal, degermination, which began shortly after 1900, probably accounted for the appearance of the epidemic; such a process was suggested at the time, but the suggestion was ignored. PMID:1285449

Infectious diseases prioritisation for event-based surveillance at the European Union level for the 2012 Olympic and Paralympic Games.

Science.gov (United States)

Economopoulou, A; Kinross, P; Domanovic, D; Coulombier, D

2014-04-17

In 2012, London hosted the Olympic and Paralympic Games (the Games), with events occurring throughout the United Kingdom (UK) between 27 July and 9 September 2012. Public health surveillance was performed by the Health Protection Agency (HPA). Collaboration between the HPA and the European Centre for Disease Prevention and Control (ECDC) was established for the detection and assessment of significant infectious disease events (SIDEs) occurring outside the UK during the time of the Games. Additionally, ECDC undertook an internal prioritisation exercise to facilitate ECDC’s decisions on which SIDEs should have preferentially enhanced monitoring through epidemic intelligence activities for detection and reporting in daily surveillance in the European Union (EU). A team of ECDC experts evaluated potential public health risks to the Games, selecting and prioritising SIDEs for event-based surveillance with regard to their potential for importation to the Games, occurrence during the Games or export to the EU/European Economic Area from the Games. The team opted for a multilevel approach including comprehensive disease selection, development and use of a qualitative matrix scoring system and a Delphi method for disease prioritisation. The experts selected 71 infectious diseases to enter the prioritisation exercise of which 27 were considered as priority for epidemic intelligence activities by ECDC for the EU for the Games.

From epidemics to information propagation: Striking differences in structurally similar adaptive network models

Science.gov (United States)

Trajanovski, Stojan; Guo, Dongchao; Van Mieghem, Piet

2015-09-01

The continuous-time adaptive susceptible-infected-susceptible (ASIS) epidemic model and the adaptive information diffusion (AID) model are two adaptive spreading processes on networks, in which a link in the network changes depending on the infectious state of its end nodes, but in opposite ways: (i) In the ASIS model a link is removed between two nodes if exactly one of the nodes is infected to suppress the epidemic, while a link is created in the AID model to speed up the information diffusion; (ii) a link is created between two susceptible nodes in the ASIS model to strengthen the healthy part of the network, while a link is broken in the AID model due to the lack of interest in informationless nodes. The ASIS and AID models may be considered as first-order models for cascades in real-world networks. While the ASIS model has been exploited in the literature, we show that the AID model is realistic by obtaining a good fit with Facebook data. Contrary to the common belief and intuition for such similar models, we show that the ASIS and AID models exhibit different but not opposite properties. Most remarkably, a unique metastable state always exists in the ASIS model, while there an hourglass-shaped region of instability in the AID model. Moreover, the epidemic threshold is a linear function in the effective link-breaking rate in the AID model, while it is almost constant but noisy in the AID model.

Characterizing the reproduction number of epidemics with early subexponential growth dynamics.

Science.gov (United States)

Chowell, Gerardo; Viboud, Cécile; Simonsen, Lone; Moghadas, Seyed M

2016-10-01

Early estimates of the transmission potential of emerging and re-emerging infections are increasingly used to inform public health authorities on the level of risk posed by outbreaks. Existing methods to estimate the reproduction number generally assume exponential growth in case incidence in the first few disease generations, before susceptible depletion sets in. In reality, outbreaks can display subexponential (i.e. polynomial) growth in the first few disease generations, owing to clustering in contact patterns, spatial effects, inhomogeneous mixing, reactive behaviour changes or other mechanisms. Here, we introduce the generalized growth model to characterize the early growth profile of outbreaks and estimate the effective reproduction number, with no need for explicit assumptions about the shape of epidemic growth. We demonstrate this phenomenological approach using analytical results and simulations from mechanistic models, and provide validation against a range of empirical disease datasets. Our results suggest that subexponential growth in the early phase of an epidemic is the rule rather the exception. Mechanistic simulations show that slight modifications to the classical susceptible-infectious-removed model result in subexponential growth, and in turn a rapid decline in the reproduction number within three to five disease generations. For empirical outbreaks, the generalized-growth model consistently outperforms the exponential model for a variety of directly and indirectly transmitted diseases datasets (pandemic influenza, measles, smallpox, bubonic plague, cholera, foot-and-mouth disease, HIV/AIDS and Ebola) with model estimates supporting subexponential growth dynamics. The rapid decline in effective reproduction number predicted by analytical results and observed in real and synthetic datasets within three to five disease generations contrasts with the expectation of invariant reproduction number in epidemics obeying exponential growth. The

The wisdom of crowds in action: Forecasting epidemic diseases with a web-based prediction market system.

Science.gov (United States)

Li, Eldon Y; Tung, Chen-Yuan; Chang, Shu-Hsun

2016-08-01

The quest for an effective system capable of monitoring and predicting the trends of epidemic diseases is a critical issue for communities worldwide. With the prevalence of Internet access, more and more researchers today are using data from both search engines and social media to improve the prediction accuracy. In particular, a prediction market system (PMS) exploits the wisdom of crowds on the Internet to effectively accomplish relatively high accuracy. This study presents the architecture of a PMS and demonstrates the matching mechanism of logarithmic market scoring rules. The system was implemented to predict infectious diseases in Taiwan with the wisdom of crowds in order to improve the accuracy of epidemic forecasting. The PMS architecture contains three design components: database clusters, market engine, and Web applications. The system accumulated knowledge from 126 health professionals for 31 weeks to predict five disease indicators: the confirmed cases of dengue fever, the confirmed cases of severe and complicated influenza, the rate of enterovirus infections, the rate of influenza-like illnesses, and the confirmed cases of severe and complicated enterovirus infection. Based on the winning ratio, the PMS predicts the trends of three out of five disease indicators more accurately than does the existing system that uses the five-year average values of historical data for the same weeks. In addition, the PMS with the matching mechanism of logarithmic market scoring rules is easy to understand for health professionals and applicable to predict all the five disease indicators. The PMS architecture of this study affords organizations and individuals to implement it for various purposes in our society. The system can continuously update the data and improve prediction accuracy in monitoring and forecasting the trends of epidemic diseases. Future researchers could replicate and apply the PMS demonstrated in this study to more infectious diseases and wider

Producing infectious enterovirus type 71 in a rapid strategy

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Qin E-De

2010-06-01

Full Text Available Abstract Background Enterovirus 71 (EV71 is an etiologic agent of hand-foot-and-mouth disease (HFMD, and recent HFMD epidemics worldwide have been associated with a severe form of brainstem encephalitis associated with pulmonary edema and high case-fatality rates. EV71 contains a positive-sense single-stranded genome RNA of approximately 7400 bp in length which encodes a polyprotein with a single open reading frame (ORF, which is flanked by untranslated regions at both the 5' and 3' ends. Results A long distance RT-PCR assay was developed to amplify the full length genome cDNA of EV71 by using specific primes carrying a SP6 promoter. Then the in vitro synthesized RNA transcripts from the RT-PCR amplicons were then transfected into RD cells to produce the rescued virus. The rescued virus was further characterized by RT-PCR and indirect fluorescent-antibody (IFA assay in comparison with the wild type virus. The rescued viruses were infectious on RD cells and neurovirulent when intracerebrally injected into suckling mice. Conclusions Thus, we established a rapid method to produce the infectious full length cDNA of EV71 directly from RNA preparations and specific mutations can be easily engineered into the rescued enterovirus genome by this method.

Strengthening epidemiologic investigation of infectious diseases in Korea: lessons from the Middle East Respiratory Syndrome outbreak

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Changhwan Lee

2015-09-01

Full Text Available The recent outbreak of Middle East Respiratory Syndrome (MERS coronavirus infection in Korea resulted in large socioeconomic losses. This provoked the Korean government and the general public to recognize the importance of having a well-established system against infectious diseases. Although epidemiologic investigation is one of the most important aspects of prevention, it has been pointed out that much needs to be improved in Korea. We review here the current status of the Korean epidemiologic service and suggest possible supplementation measures. We examine the current national preventive infrastructure, including human resources such as Epidemic Intelligence Service officers, its governmental management, and related policies. In addition, we describe the practical application of these resources to the recent MERS outbreak and the progress in preventive measures. The spread of MERS demonstrated that the general readiness for emerging infectious diseases in Korea is considerably low. We believe that it is essential to increase society’s investment in disease prevention. Fostering public health personnel, legislating management policies, and establishing research centers for emerging infectious diseases are potential solutions. Evaluating international preventive systems, developing cooperative measures, and initiating improvements are necessary. We evaluated the Korean epidemiologic investigation system and the public preventive measures against infectious diseases in light of the recent MERS outbreak. We suggest that governmental authorities in Korea enforce preventive policies, foster the development of highly qualified personnel, and increase investment in the public health domain of infectious disease prevention.

Economic cost and burden of dengue during epidemics and non-epidemic years in Taiwan

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Dih-Ling Luh

2018-03-01

Full Text Available Background: Determining the disease and economic burden of dengue is critical for the allocation of public health resources. Several studies have used disability-adjusted life-years (DALYs to estimate the disease burden of dengue in different regions. However, there are no published studies discussing the estimates of dengue-related economic and disease burden specifically in Taiwan. Objectives: We assessed the economic cost and disease burden of dengue infections in Taiwan for the period 1998–2014, and compared these during epidemic and non-epidemic years. Methods: We estimated the annual DALYs per million population using the disability weights for dengue fever (DF, dengue hemorrhagic fever (DHF, dengue shock syndrome (DSS, and death cases. Economic costs were estimated and divided into direct (medical costs and indirect costs (lost work days and caregiver fees. Results: For the period 1998–2014, a mean of 115.3 (range: 6.3–934.3 DALYs per million population annually were lost to dengue. In epidemic years, direct costs associated with dengue resulted mostly from hospitalization (86.09%, emergency (7.77%, outpatient (6.10%, and drug costs (0.03%. For indirect costs, lost productivity due to death (70.76% was the dominant contributor. Overall, the costs were 12.3 times higher in epidemic years than in non-epidemic years (Wilcoxon rank sum test, p < 0.05. Conclusions: This study is the first to evaluate the economic costs and disease burden of dengue infections for this period in Taiwan, and reveals significant differences in economic impact between epidemic and non-epidemic years. Keywords: Economic cost of disease, Disease burden, Disability-adjusted life years (DALYs, Dengue, Epidemic

Information content of household-stratified epidemics

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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.

Information content of household-stratified epidemics.

Science.gov (United States)

Kinyanjui, T M; Pellis, L; House, T

2016-09-01

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. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Phylogeography of infectious haematopoietic necrosis virus in North America

DEFF Research Database (Denmark)

Kurath, G.; Garver, K.A.; Troyer, R.M.

2003-01-01

Infectious hematopoietic necrosis virus (IHNV) is a rhabdoviral pathogen that infects wild and cultured salmonid fish throughout the Pacific Northwest of North America. IHNV causes severe epidemics in young fish and can cause disease or occur asymptomatically in adults. In a broad survey of 323...... IHNV field isolates, sequence analysis of a 303 nucleotide variable region within the glycoprotein gene revealed a maximum nucleotide diversity of 8(.)6%, indicating low genetic diversity overall for this virus. Phylogenetic analysis revealed three major virus genogroups, designated U, M and L, which...... varied in topography and geographical range. Intragenogroup genetic. diversity measures indicated that the M genogroup had three- to fourfold more diversity than the other genogroups and suggested relatively rapid evolution of the M genogroup and stasis within the U genogroup. We speculate that factors...

Global HIV/AIDS Epidemic

Science.gov (United States)

... Policy The Global HIV/AIDS Epidemic The Global HIV/AIDS Epidemic Published: Nov 29, 2017 Facebook Twitter ... 2001-FY 2018 Request The Global Response to HIV/AIDS International efforts to combat HIV began in ...

Epidemic modeling in complex realities.

Science.gov (United States)

Colizza, Vittoria; Barthélemy, Marc; Barrat, Alain; Vespignani, Alessandro

2007-04-01

In our global world, the increasing complexity of social relations and transport infrastructures are key factors in the spread of epidemics. In recent years, the increasing availability of computer power has enabled both to obtain reliable data allowing one to quantify the complexity of the networks on which epidemics may propagate and to envision computational tools able to tackle the analysis of such propagation phenomena. These advances have put in evidence the limits of homogeneous assumptions and simple spatial diffusion approaches, and stimulated the inclusion of complex features and heterogeneities relevant in the description of epidemic diffusion. In this paper, we review recent progresses that integrate complex systems and networks analysis with epidemic modelling and focus on the impact of the various complex features of real systems on the dynamics of epidemic spreading.

Rationale for an HIV / AIDS prevention and mitigation strategy for Africa: combatting the multisectoral impact of the epidemic.

Science.gov (United States)

Lyerly, W H

1996-01-01

Unlike most infectious diseases in Africa, HIV/AIDS affects the urban elite as well as the rural poor, and generally during their most economically productive years. An increase in deaths among young adults of the magnitude predicted is likely to have substantial adverse effects on economic, political, and military/security stability throughout Africa. AIDS is causing increased stress on fragile African economic infrastructures as labor productivity declines, particularly in agricultural, labor-dependent economies. AIDS is causing obstacles to trade, foreign investment and tourism. Health systems and social coping mechanisms already are overburdened. High rates of HIV infection among police and military personnel threaten internal security. Furthermore, the demobilization of military forces in Africa may exacerbate the epidemic when HIV-infected soldiers return home and spread the virus. This presentation will illustrate why African AIDS Programs must be expanded to mitigate the multisectoral impact of the epidemic while preserving its spread.

THE ORGANIZATION OF HOSPITAL CARE DURING THE EPIDEMIC OF INFLUENZA AND SARS FOR THE 2016 SEASON IN VELIKY NOVGOROD

Directory of Open Access Journals (Sweden)

M. V. Yuhno

2016-01-01

Full Text Available Analyzed organization of preventive measures and  patient  care  in  Velikiy Novgorod in  connection with  the  exceeding of the  epidemic threshold for influenza and  acute respiratory viral  infections in  2016.  The  epidemic rise  of influenza and  other  acute  respiratory viral  infections exceeded epidemiological and economic thresholds among  the cumulative population on the  territory  of the  Novgorod region started from the 3rd week 2016 (18.01.2016–24.01.2016 and continued for 4 weeks (until  mid February.  The peak  of the epidemic was passed on the 4th calendar week  of 2016, when  the weekly prevalence rate was 135,7 per 10 thousand population (8447,  the  epidemic  threshold was  exceeded in 2 times. In terms  of conversion to the  infectious diseases hospital, a multidisciplinary clinic № 2 «Central city clinical hospital» carried  out specialized medical assistance 301 the patient with  acute respiratory diseases and  influenza, 67 of which were confirmed influenza caused by the H1N1 virus, of which  28 patients would,  if hospitalized in serious  and critical condition and  needed to be held-Institute the  intensive care manual.

Human mobility and time spent at destination: impact on spatial epidemic spreading.

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Poletto, Chiara; Tizzoni, Michele; Colizza, Vittoria

2013-12-07

Host mobility plays a fundamental role in the spatial spread of infectious diseases. Previous theoretical works based on the integration of network theory into the metapopulation framework have shown that the heterogeneities that characterize real mobility networks favor the propagation of epidemics. Nevertheless, the studies conducted so far assumed the mobility process to be either Markovian (in which the memory of the origin of each traveler is lost) or non-Markovian with a fixed traveling time scale (in which individuals travel to a destination and come back at a constant rate). Available statistics however show that the time spent by travelers at destination is characterized by wide fluctuations, ranging from a single day up to several months. Such varying length of stay crucially affects the chance and duration of mixing events among hosts and may therefore have a strong impact on the spread of an emerging disease. Here, we present an analytical and a computational study of epidemic processes on a complex subpopulation network where travelers have memory of their origin and spend a heterogeneously distributed time interval at their destination. Through analytical calculations and numerical simulations we show that the heterogeneity of the length of stay alters the expression of the threshold between local outbreak and global invasion, and, moreover, it changes the epidemic behavior of the system in case of a global outbreak. Additionally, our theoretical framework allows us to study the effect of changes in the traveling behavior in response to the infection, by considering a scenario in which sick individuals do not leave their home location. Finally, we compare the results of our non-Markovian framework with those obtained with a classic Markovian approach and find relevant differences between the two, in the estimate of the epidemic invasion potential, as well as of the timing and the pattern of its spatial spread. These results highlight the importance of

Comparison of filtering methods for the modeling and retrospective forecasting of influenza epidemics.

Directory of Open Access Journals (Sweden)

Wan Yang

2014-04-01

Full Text Available A variety of filtering methods enable the recursive estimation of system state variables and inference of model parameters. These methods have found application in a range of disciplines and settings, including engineering design and forecasting, and, over the last two decades, have been applied to infectious disease epidemiology. For any system of interest, the ideal filter depends on the nonlinearity and complexity of the model to which it is applied, the quality and abundance of observations being entrained, and the ultimate application (e.g. forecast, parameter estimation, etc.. Here, we compare the performance of six state-of-the-art filter methods when used to model and forecast influenza activity. Three particle filters--a basic particle filter (PF with resampling and regularization, maximum likelihood estimation via iterated filtering (MIF, and particle Markov chain Monte Carlo (pMCMC--and three ensemble filters--the ensemble Kalman filter (EnKF, the ensemble adjustment Kalman filter (EAKF, and the rank histogram filter (RHF--were used in conjunction with a humidity-forced susceptible-infectious-recovered-susceptible (SIRS model and weekly estimates of influenza incidence. The modeling frameworks, first validated with synthetic influenza epidemic data, were then applied to fit and retrospectively forecast the historical incidence time series of seven influenza epidemics during 2003-2012, for 115 cities in the United States. Results suggest that when using the SIRS model the ensemble filters and the basic PF are more capable of faithfully recreating historical influenza incidence time series, while the MIF and pMCMC do not perform as well for multimodal outbreaks. For forecast of the week with the highest influenza activity, the accuracies of the six model-filter frameworks are comparable; the three particle filters perform slightly better predicting peaks 1-5 weeks in the future; the ensemble filters are more accurate predicting peaks in

[Chikungunya, La Réunion and Mayotte, 2005-2006: an epidemic without a story?].

Science.gov (United States)

Flahault, Antoine; Aumont, Gilles; Boisson, Véronique; de Lamballerile, Xavier; Favier, François; Fontenille, Didier; Gaüzère, Bernard-Alex; Journeaux, Sophie; Lotteau, Vincent; Paupy, Christophe; Sanquer, Marie-Anne; Setbon, Michel

2007-01-01

Many triggering factors for onset of emerging infectious diseases are now recognised, such as: globalisation, demographic increase, population movements, international trade, urbanisation, forest destruction, climate changes, loss in biodiversity, and extreme life conditions such as poverty, famine and war. Epidemic burden is often leading to disasters, in terms of human losses, as well as economic, political or social consequences. These outbreaks may jeopardize within a few weeks or months, industry, trade, or tourism. While dengue and its most severe forms (hemorrhagic and shock syndrome) is spreading all over the tropical world, another arbovirosis, chikungunya disease dramatically spread in Indian Ocean islands where 30 to 75% of population were infected in 2005 and 2006, and then extended its progression towards India, Sri Lanka, Indonesia, Malaysia, Maldives islands with more than a million people infected with the East-African strain, replacing the former Asian strain which was known to prevail more than 30 years ago in India. Patients experience sequelae with disability, work loss, and rarely severe outcome recently identified in La Réunion and Mayotte (French overseas territories). No country, no part of the world may consider itself as protected against such events. However, consequences of emerging or re-emerging diseases are more and more unacceptable when they impact the poorest countries of the world. Viruses, bacteria, as well as wild animals, birds, or arthropods are not stopped by borders. It is time now to promote barriers against infectious diseases, including prevention, anticipation, disease surveillance and research. This is not only for humanitarian reasons, but also for contributing to a sustainable development with equity for worldwide population. This report presents comprehensive actions taken in 2006 for tracing the epidemic and mobilise research, as requested to the task force set up by the Prime Minister by March 20, 2006.

Epidemics spread in heterogeneous populations

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Capała, Karol; Dybiec, Bartłomiej

2017-05-01

Individuals building populations are subject to variability. This variability affects progress of epidemic outbreaks, because individuals tend to be more or less resistant. Individuals also differ with respect to their recovery rate. Here, properties of the SIR model in inhomogeneous populations are studied. It is shown that a small change in model's parameters, e.g. recovery or infection rate, can substantially change properties of final states which is especially well-visible in distributions of the epidemic size. In addition to the epidemic size and radii distributions, the paper explores first passage time properties of epidemic outbreaks.

Modeling human gastrointestinal inflammatory diseases using microphysiological culture systems.

Science.gov (United States)

Hartman, Kira G; Bortner, James D; Falk, Gary W; Ginsberg, Gregory G; Jhala, Nirag; Yu, Jian; Martín, Martín G; Rustgi, Anil K; Lynch, John P

2014-09-01

Gastrointestinal illnesses are a significant health burden for the US population, with 40 million office visits each year for gastrointestinal complaints and nearly 250,000 deaths. Acute and chronic inflammations are a common element of many gastrointestinal diseases. Inflammatory processes may be initiated by a chemical injury (acid reflux in the esophagus), an infectious agent (Helicobacter pylori infection in the stomach), autoimmune processes (graft versus host disease after bone marrow transplantation), or idiopathic (as in the case of inflammatory bowel diseases). Inflammation in these settings can contribute to acute complaints (pain, bleeding, obstruction, and diarrhea) as well as chronic sequelae including strictures and cancer. Research into the pathophysiology of these conditions has been limited by the availability of primary human tissues or appropriate animal models that attempt to physiologically model the human disease. With the many recent advances in tissue engineering and primary human cell culture systems, it is conceivable that these approaches can be adapted to develop novel human ex vivo systems that incorporate many human cell types to recapitulate in vivo growth and differentiation in inflammatory microphysiological environments. Such an advance in technology would improve our understanding of human disease progression and enhance our ability to test for disease prevention strategies and novel therapeutics. We will review current models for the inflammatory and immunological aspects of Barrett's esophagus, acute graft versus host disease, and inflammatory bowel disease and explore recent advances in culture methodologies that make these novel microphysiological research systems possible. © 2014 by the Society for Experimental Biology and Medicine.

Antibody transferred from the blood to the gastrointestinal tract and its role in enteric immunity of neonatal calves

International Nuclear Information System (INIS)

Besser, T.E.

1986-01-01

High passive blood immunoglobulin concentrations are associated with decreased infectious enteric disease mortality in neonatal calves. Passive immunoglobulin transferred from the blood to the gastrointestinal tract may explain this protection. To measure the rate at which immunoglobulin G 1 (IgG 1 ) is transferred to the gastrointestinal tract, 125 I-labelled bovine IgG 1 anti-DNP antibody was administered to calves by intravenous injection. The clearance rate of 125 I-IgG 1 from the blood was measured and compared to the rate of 125 I-IgG 1 appearance in the gastrointestinal tract, as measured (1) by the rate of fecal 125 I-IgG 1 excretion, and (2) by the amount of 125 I-IgG 1 in the gastrointestinal tract of calves at necropsy. Rotavirus antibody titers in the gastrointestinal contents of 5- and 10-days-old calves correlated with the calves' serum passive rotavirus antibody titers, and were increased in proportion to the amount of colostral antibody fed on the first day of life. In contrast, when colostral rotavirus antibody was fed to 48-hour-old calves, when absorption of passive immunoglobulin does not occur, there was no measurable increase in antibody in the intestine 5 days later. Intestinal antibody in the 5- and 10-day-old calves therefore resulted from blood antibody transferred to the gastrointestinal tract. Rotavirus antibody administered to calves by parenteral injection protected them from infection and diarrhea after rotavirus challenge. These results indicate that passive blood IgG enters the calf gastrointestinal tract, where it contributes to intestinal immunity

One Health, emerging infectious diseases and wildlife: two decades of progress?

Science.gov (United States)

Cunningham, Andrew A; Daszak, Peter; Wood, James L N

2017-07-19

Infectious diseases affect people, domestic animals and wildlife alike, with many pathogens being able to infect multiple species. Fifty years ago, following the wide-scale manufacture and use of antibiotics and vaccines, it seemed that the battle against infections was being won for the human population. Since then, however, and in addition to increasing antimicrobial resistance among bacterial pathogens, there has been an increase in the emergence of, mostly viral, zoonotic diseases from wildlife, sometimes causing fatal outbreaks of epidemic proportions. Concurrently, infectious disease has been identified as an increasing threat to wildlife conservation. A synthesis published in 2000 showed common anthropogenic drivers of disease threats to biodiversity and human health, including encroachment and destruction of wildlife habitat and the human-assisted spread of pathogens. Almost two decades later, the situation has not changed and, despite improved knowledge of the underlying causes, little has been done at the policy level to address these threats. For the sake of public health and wellbeing, human-kind needs to work better to conserve nature and preserve the ecosystem services, including disease regulation, that biodiversity provides while also understanding and mitigating activities which lead to disease emergence. We consider that holistic, One Health approaches to the management and mitigation of the risks of emerging infectious diseases have the greatest chance of success.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'. © 2017 The Authors.

Travelling wave solutions for an infection-age structured epidemic model with external supplies

International Nuclear Information System (INIS)

Ducrot, Arnaud; Magal, Pierre

2011-01-01

The aim of this paper is to investigate the spatial invasion of some infectious disease. The contamination process is described by the age since infection. Compared with the classical Kermack and McKendrick's model, the vital dynamic is not omitted, and we allow some constant input flux into the population. This problem is rather natural in the context of epidemic problems and it has not been studied. Here we prove an existence and non-existence result for travelling wave solutions. We also describe the minimal wave speed. We are able to construct a suitable Lyapunov like functional decreasing along the travelling wave allowing to derive some qualitative properties, namely their convergence towards equilibrium points at x = ±∞

Hepatitis E epidemics in India

Indian Academy of Sciences (India)

The first well recorded epidemic was in 1955-56 here in Delhi with nearly 30000 cases. Large outbreaks occurred in 1978 in Kashmir. My interest in this disease began in 1991 during investigations into a large epidemic of hepatitis E in Kanpur that my mentor, later Prof SR Naik, and I undertook. I will use this epidemic as an ...

Efficient control of epidemics spreading on networks: balance between treatment and recovery.

Science.gov (United States)

Oleś, Katarzyna; Gudowska-Nowak, Ewa; Kleczkowski, Adam

2013-01-01

We analyse two models describing disease transmission and control on regular and small-world networks. We use simulations to find a control strategy that minimizes the total cost of an outbreak, thus balancing the costs of disease against that of the preventive treatment. The models are similar in their epidemiological part, but differ in how the removed/recovered individuals are treated. The differences in models affect choice of the strategy only for very cheap treatment and slow spreading disease. However for the combinations of parameters that are important from the epidemiological perspective (high infectiousness and expensive treatment) the models give similar results. Moreover, even where the choice of the strategy is different, the total cost spent on controlling the epidemic is very similar for both models.

Stability analysis of an HIV/AIDS epidemic model with treatment

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Cai, Liming; Li, Xuezhi; Ghosh, Mini; Guo, Baozhu

2009-07-01

An HIV/AIDS epidemic model with treatment is investigated. The model allows for some infected individuals to move from the symptomatic phase to the asymptomatic phase by all sorts of treatment methods. We first establish the ODE treatment model with two infective stages. Mathematical analyses establish that the global dynamics of the spread of the HIV infectious disease are completely determined by the basic reproduction number [real]0. If [real]01. Then, we introduce a discrete time delay to the model to describe the time from the start of treatment in the symptomatic stage until treatment effects become visible. The effect of the time delay on the stability of the endemically infected equilibrium is investigated. Moreover, the delay model exhibits Hopf bifurcations by using the delay as a bifurcation parameter. Finally, numerical simulations are presented to illustrate the results.

Mutually cooperative epidemics on power-law networks

Science.gov (United States)

Cui, Peng-Bi; Colaiori, Francesca; Castellano, Claudio

2017-08-01

The spread of an infectious disease can, in some cases, promote the propagation of other pathogens favoring violent outbreaks, which cause a discontinuous transition to an endemic state. The topology of the contact network plays a crucial role in these cooperative dynamics. We consider a susceptible-infected-removed-type model with two mutually cooperative pathogens: An individual already infected with one disease has an increased probability of getting infected by the other. We present a heterogeneous mean-field theoretical approach to the coinfection dynamics on generic uncorrelated power-law degree-distributed networks and validate its results by means of numerical simulations. We show that, when the second moment of the degree distribution is finite, the epidemic transition is continuous for low cooperativity, while it is discontinuous when cooperativity is sufficiently high. For scale-free networks, i.e., topologies with diverging second moment, the transition is instead always continuous. In this way we clarify the effect of heterogeneity and system size on the nature of the transition, and we validate the physical interpretation about the origin of the discontinuity.

The global dynamics for a stochastic SIS epidemic model with isolation

Science.gov (United States)

Chen, Yiliang; Wen, Buyu; Teng, Zhidong

2018-02-01

In this paper, we investigate the dynamical behavior for a stochastic SIS epidemic model with isolation which is as an important strategy for the elimination of infectious diseases. It is assumed that the stochastic effects manifest themselves mainly as fluctuation in the transmission coefficient, the death rate and the proportional coefficient of the isolation of infective. It is shown that the extinction and persistence in the mean of the model are determined by a threshold value R0S . That is, if R0S 1, then the disease is stochastic persistent in the means with probability one. Furthermore, the existence of a unique stationary distribution is discussed, and the sufficient conditions are established by using the Lyapunov function method. Finally, some numerical examples are carried out to confirm the analytical results.

Detection of intestinal protozoa in paediatric patients with gastrointestinal symptoms by multiplex real-time PCR.

Science.gov (United States)

Maas, L; Dorigo-Zetsma, J W; de Groot, C J; Bouter, S; Plötz, F B; van Ewijk, B E

2014-06-01

The performance of a multiplex real-time PCR for the detection of Blastocystis, Dientamoeba fragilis, Giardia lamblia, Cryptosporidium species and Entamoeba species in faecal samples was evaluated in an observational prospective study. Paediatric patients (0-18 years) presenting with gastrointestinal symptoms and suspected of having enteroparasitic disease were included. A questionnaire on gastrointestinal symptoms and the chosen treatment was completed at the start of the study and after 6 weeks. Of 163 paediatric patients (mean age, 7.8 years), 114 (70%) had a PCR-positive faecal sample. D. fragilis was detected most frequently, in 101 patients, followed by Blastocystis in 49. In faecal samples of 47 patients, more than one protozoan was detected, mainly the combination of D. fragilis and Blastocystis. Reported gastrointestinal symptoms were abdominal pain (78%), nausea (30%), and altered bowel habits (28%). Eighty-nine of the PCR-positive patients were treated with antibiotics. A significant reduction in abdominal pain was observed both in treated and in untreated patients. This study demonstrated that multiplex real-time PCR detects a high percentage of intestinal protozoa in paediatric patients with gastrointestinal symptoms. However, interpretation and determination of the clinical relevance of a positive PCR result in this population are still difficult. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

The use of convalescent plasma to treat emerging infectious diseases: focus on Ebola virus disease.

Science.gov (United States)

Winkler, Anne M; Koepsell, Scott A

2015-11-01

The purpose of this review is to discuss the use of convalescent plasma for the treatment of emerging infectious diseases, focusing on the recent use for the treatment of Ebola virus disease (EVD). Ebola convalescent plasma has been used as a therapy for treatment of EVD during the 2014 West Africa epidemic. Several cases from the United States and Europe have been recently published, in addition to multiple ongoing clinical trials in the United States and West Africa. Even more recently, convalescent plasma has been used for treatment of individuals with Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Although the first reports of successful treatment with passive immune therapy date back to the early 1900s, convalescent plasma has materialized as a possible therapy for patients who develop infection from one of the emerging infectious diseases such as EVD or MERS-CoV, although the efficacy of such therapy has yet to be proven in clinical trials.

Development and Characterization of Recombinant Virus Generated from a New World Zika Virus Infectious Clone.

Science.gov (United States)

Weger-Lucarelli, James; Duggal, Nisha K; Bullard-Feibelman, Kristen; Veselinovic, Milena; Romo, Hannah; Nguyen, Chilinh; Rückert, Claudia; Brault, Aaron C; Bowen, Richard A; Stenglein, Mark; Geiss, Brian J; Ebel, Gregory D

2017-01-01

Zika virus (ZIKV; family Flaviviridae, genus Flavivirus) is a rapidly expanding global pathogen that has been associated with severe clinical manifestations, including devastating neurological disease in infants. There are currently no molecular clones of a New World ZIKV available that lack significant attenuation, hindering progress toward understanding determinants of transmission and pathogenesis. Here we report the development and characterization of a novel ZIKV reverse genetics system based on a 2015 isolate from Puerto Rico (PRVABC59). We generated a two-plasmid infectious clone system from which infectious virus was rescued that replicates in human and mosquito cells with growth kinetics representative of wild-type ZIKV. Infectious clone-derived virus initiated infection and transmission rates in Aedes aegypti mosquitoes comparable to those of the primary isolate and displayed similar pathogenesis in AG129 mice. This infectious clone system provides a valuable resource to the research community to explore ZIKV molecular biology, vaccine development, antiviral development, diagnostics, vector competence, and disease pathogenesis. ZIKV is a rapidly spreading mosquito-borne pathogen that has been linked to Guillain-Barré syndrome in adults and congenital microcephaly in developing fetuses and infants. ZIKV can also be sexually transmitted. The viral molecular determinants of any of these phenotypes are not well understood. There is no reverse genetics system available for the current epidemic virus that will allow researchers to study ZIKV immunity, develop novel vaccines, or develop antiviral drugs. Here we provide a novel infectious clone system generated from a recent ZIKV isolated from a patient infected in Puerto Rico. This infectious clone produces virus with in vitro and in vivo characteristics similar to those of the primary isolate, providing a critical tool to study ZIKV infection and disease. Copyright © 2016 American Society for Microbiology.

Nationwide variation in the effects of temperature on infectious gastroenteritis incidence in Japan

Science.gov (United States)

Onozuka, Daisuke; Hagihara, Akihito

2015-08-01

Although several studies have investigated the effects of temperature on the incidence of infectious gastrointestinal disease in a single city or region, few have investigated variations in this association using nationwide data. We obtained weekly data, gathered between 2000 and 2012, pertaining to infectious gastroenteritis cases and weather variability in all 47 Japanese prefectures. A two-stage analysis was used to assess the nonlinear and delayed relationship between temperature and morbidity. In the first stage, a Poisson regression allowing for overdispersion in a distributed lag nonlinear model was used to estimate the prefecture-specific effects of temperature on morbidity. In the second stage, a multivariate meta-analysis was applied to pool estimates at the national level. The pooled overall relative risk (RR) was highest in the 59.9th percentile of temperature (RR, 1.08; 95% CI: 1.01, 1.15). Meta-analysis results also indicated that the estimated pooled RR at lower temperatures (25th percentile) began immediately but did not persist, whereas an identical estimate at a higher temperature (75th percentile) was delayed but persisted for several weeks. Our results suggest that public health strategies aimed at controlling temperature-related infectious gastroenteritis may be more effective when tailored according to region-specific weather conditions.

Current status of cleaning and disinfection for gastrointestinal endoscopy in China: a survey of 122 endoscopy units.

Science.gov (United States)

Zhang, Xiuli; Kong, Jinyan; Tang, Ping; Wang, Shufang; Hyder, Qurratulain; Sun, Gang; Zhang, Rugang; Yang, Yunsheng

2011-04-01

Adequate compliance with the existing guidelines for cleaning and disinfection of gastrointestinal endoscopes and accessories is necessary to obtain high-level disinfection and prevent pathogen transmission. To investigate cleaning and disinfection practice in China. A questionnaire with 21 questions concerning gastrointestinal endoscopy reprocessing was sent by e-mail to 189 endoscopy units in China. One hundred and twenty-two (80.39%) of the 189 units responded. Compared with the low-workload units (disinfectant (88.5%) in all the units. In 23/122 (18.8%) units, the exposure time to glutaraldehyde was <45 min in the case of infectious disease patients. Eighty-six of 122 (70.5%) units reused disposable materials, of which 21/86 (24.4%) reused disposable forceps and disposable polypectomy hooks, and 2/86 (1.6%) reused disposable injection needles intermittently. Although gastrointestinal endoscopy has developed rapidly in China in the past decade, there is still room for improvement in the practice of endoscopy reprocessing, especially in middle-sized and small cities. Copyright © 2011 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Observed and projected drivers of emerging infectious diseases in Europe.

Science.gov (United States)

Semenza, Jan C; Rocklöv, Joacim; Penttinen, Pasi; Lindgren, Elisabet

2016-10-01

Emerging infectious diseases are of international concern because of the potential for, and impact of, pandemics; however, they are difficult to predict. To identify the drivers of disease emergence, we analyzed infectious disease threat events (IDTEs) detected through epidemic intelligence collected at the European Centre for Disease Prevention and Control (ECDC) between 2008 and 2013, and compared the observed results with a 2008 ECDC foresight study of projected drivers of future IDTEs in Europe. Among 10 categories of IDTEs, foodborne and waterborne IDTEs were the most common, vaccine-preventable IDTEs caused the highest number of cases, and airborne IDTEs caused the most deaths. Observed drivers for each IDTE were sorted into three main groups: globalization and environmental drivers contributed to 61% of all IDTEs, public health system drivers contributed to 21%, and social and demographic drivers to 18%. A multiple logistic regression analysis showed that four of the top five drivers for observed IDTEs were in the globalization and environment group. In the observational study, the globalization and environment group was related to all IDTE categories, but only to five of eight categories in the foresight study. Directly targeting these drivers with public health interventions may diminish the chances of IDTE occurrence from the outset. © 2016 New York Academy of Sciences.

Deriving a model for influenza epidemics from historical data.

Energy Technology Data Exchange (ETDEWEB)

Ray, Jaideep; Lefantzi, Sophia

2011-09-01

In this report we describe how we create a model for influenza epidemics from historical data collected from both civilian and military societies. We derive the model when the population of the society is unknown but the size of the epidemic is known. Our interest lies in estimating a time-dependent infection rate to within a multiplicative constant. The model form fitted is chosen for its similarity to published models for HIV and plague, enabling application of Bayesian techniques to discriminate among infectious agents during an emerging epidemic. We have developed models for the progression of influenza in human populations. The model is framed as a integral, and predicts the number of people who exhibit symptoms and seek care over a given time-period. The start and end of the time period form the limits of integration. The disease progression model, in turn, contains parameterized models for the incubation period and a time-dependent infection rate. The incubation period model is obtained from literature, and the parameters of the infection rate are fitted from historical data including both military and civilian populations. The calibrated infection rate models display a marked difference in which the 1918 Spanish Influenza pandemic differed from the influenza seasons in the US between 2001-2008 and the progression of H1N1 in Catalunya, Spain. The data for the 1918 pandemic was obtained from military populations, while the rest are country-wide or province-wide data from the twenty-first century. We see that the initial growth of infection in all cases were about the same; however, military populations were able to control the epidemic much faster i.e., the decay of the infection-rate curve is much higher. It is not clear whether this was because of the much higher level of organization present in a military society or the seriousness with which the 1918 pandemic was addressed. Each outbreak to which the influenza model was fitted yields a separate set of

Coupling effects on turning points of infectious diseases epidemics in scale-free networks.

Science.gov (United States)

Kim, Kiseong; Lee, Sangyeon; Lee, Doheon; Lee, Kwang Hyung

2017-05-31

Pandemic is a typical spreading phenomenon that can be observed in the human society and is dependent on the structure of the social network. The Susceptible-Infective-Recovered (SIR) model describes spreading phenomena using two spreading factors; contagiousness (β) and recovery rate (γ). Some network models are trying to reflect the social network, but the real structure is difficult to uncover. We have developed a spreading phenomenon simulator that can input the epidemic parameters and network parameters and performed the experiment of disease propagation. The simulation result was analyzed to construct a new marker VRTP distribution. We also induced the VRTP formula for three of the network mathematical models. We suggest new marker VRTP (value of recovered on turning point) to describe the coupling between the SIR spreading and the Scale-free (SF) network and observe the aspects of the coupling effects with the various of spreading and network parameters. We also derive the analytic formulation of VRTP in the fully mixed model, the configuration model, and the degree-based model respectively in the mathematical function form for the insights on the relationship between experimental simulation and theoretical consideration. We discover the coupling effect between SIR spreading and SF network through devising novel marker VRTP which reflects the shifting effect and relates to entropy.

Effect of vaccination strategies on the dynamic behavior of epidemic spreading and vaccine coverage

International Nuclear Information System (INIS)

Cai, Chao-Ran; Wu, Zhi-Xi; Guan, Jian-Yue

2014-01-01

The transmission of infectious, yet vaccine-preventable, diseases is a typical complex social phenomenon, where the increasing level of vaccine update in the population helps to inhibit the epidemic spreading, which in turn, however, discourages more people to participate in vaccination campaigns, due to the “externality effect” raised by vaccination. We herein study the impact of vaccination strategies, pure, continuous (rather than adopt vaccination definitely, the individuals choose to taking vaccine with some probabilities), or continuous with randomly mutation, on the vaccination dynamics with a spatial susceptible-vaccinated-infected-recovered (SVIR) epidemiological model. By means of extensive Monte-Carlo simulations, we show that there is a crossover behavior of the final vaccine coverage between the pure-strategy case and the continuous-strategy case, and remarkably, both the final vaccination level and epidemic size in the continuous-strategy case are less than them in the pure-strategy case when vaccination is cheap. We explain this phenomenon by analyzing the organization process of the individuals in the continuous-strategy case in the equilibrium. Our results are robust to the SVIR dynamics defined on other spatial networks, like the Erdős–Rényi and Barabási–Albert networks

Need for integrative thinking to fight against emerging infectious diseases. Proceedings of the 5th seminar on emerging infectious diseases, March 22, 2016 - current trends and proposals.

Science.gov (United States)

Burdet, C; Guégan, J-F; Duval, X; Le Tyrant, M; Bergeron, H; Manuguerra, J-C; Raude, J; Leport, C; Zylberman, P

2018-02-01

We present here the proceedings of the 5th seminar on emerging infectious diseases, held in Paris on March 22nd, 2016, with seven priority proposals that can be outlined as follows: encourage research on the prediction, screening and early detection of new risks of infection; develop research and surveillance concerning transmission of pathogens between animals and humans, with their reinforcement in particular in intertropical areas ("hot-spots") via public support; pursue aid development and support in these areas of prevention and training for local health personnel, and foster risk awareness in the population; ensure adapted patient care in order to promote adherence to treatment and to epidemic propagation reduction measures; develop greater awareness and better education among politicians and healthcare providers, in order to ensure more adapted response to new types of crises; modify the logic of governance, drawing from all available modes of communication and incorporating new information-sharing tools; develop economic research on the fight against emerging infectious diseases, taking into account specific driving factors in order to create a balance between preventive and curative approaches. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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

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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

[Infectious diseases research].

Science.gov (United States)

Carratalà, Jordi; Alcamí, José; Cordero, Elisa; Miró, José M; Ramos, José Manuel

2008-12-01

There has been a significant increase in research activity into infectious diseases in Spain in the last few years. The Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) currently has ten study groups, with the cooperation of infectious diseases specialists and microbiologists from different centres, with significant research activity. The program of Redes Temáticas de Investigación Cooperativa en Salud (Special Topics Cooperative Health Research Networks) is an appropriate framework for the strategic coordination of research groups from the Spanish autonomous communities. The Spanish Network for Research in Infectious Diseases (REIPI) and the Network for Research in AIDS (RIS) integrate investigators in Infectious Diseases from multiple groups, which continuously perform important research projects. Research using different experimental models in infectious diseases, in numerous institutions, is an important activity in our country. The analysis of the recent scientific production in Infectious Diseases shows that Spain has a good position in the context of the European Union. The research activity in Infectious Diseases carried out in our country is a great opportunity for the training of specialists in this area of knowledge.

Antibody transferred from the blood to the gastrointestinal tract and its role in enteric immunity of neonatal calves

Energy Technology Data Exchange (ETDEWEB)

Besser, T.E.

1986-01-01

High passive blood immunoglobulin concentrations are associated with decreased infectious enteric disease mortality in neonatal calves. Passive immunoglobulin transferred from the blood to the gastrointestinal tract may explain this protection. To measure the rate at which immunoglobulin G/sub 1/ (IgG/sub 1/) is transferred to the gastrointestinal tract, /sup 125/I-labelled bovine IgG/sub 1/ anti-DNP antibody was administered to calves by intravenous injection. The clearance rate of /sup 125/I-IgG/sub 1/ from the blood was measured and compared to the rate of /sup 125/I-IgG/sub 1/ appearance in the gastrointestinal tract, as measured (1) by the rate of fecal /sup 125/I-IgG/sub 1/ excretion, and (2) by the amount of /sup 125/I-IgG/sub 1/ in the gastrointestinal tract of calves at necropsy. Rotavirus antibody titers in the gastrointestinal contents of 5- and 10-days-old calves correlated with the calves' serum passive rotavirus antibody titers, and were increased in proportion to the amount of colostral antibody fed on the first day of life. In contrast, when colostral rotavirus antibody was fed to 48-hour-old calves, when absorption of passive immunoglobulin does not occur, there was no measurable increase in antibody in the intestine 5 days later. Intestinal antibody in the 5- and 10-day-old calves therefore resulted from blood antibody transferred to the gastrointestinal tract. Rotavirus antibody administered to calves by parenteral injection protected them from infection and diarrhea after rotavirus challenge. These results indicate that passive blood IgG enters the calf gastrointestinal tract, where it contributes to intestinal immunity.

Observability and Controllability of Networks: Symmetry in Representations of Brains and Controllers for Epidemics

Science.gov (United States)

Schiff, Steven

Observability and controllability are essential concepts to the design of predictive observer models and feedback controllers of networked systems. We present a numerical and group representational framework, to quantify the observability and controllability of nonlinear networks with explicit symmetries that shows the connection between symmetries and nonlinear measures of observability and controllability. In addition to the topology of brain networks, we have advanced our ability to represent network nodes within the brain using conservation principles and more accurate biophysics that unifies the dynamics of spikes, seizures, and spreading depression. Lastly, we show how symmetries in controller design can be applied to infectious disease epidemics. NIH Grants 1R01EB014641, 1DP1HD086071.

Dynamics and optimal control of a non-linear epidemic model with relapse and cure

Science.gov (United States)

Lahrouz, A.; El Mahjour, H.; Settati, A.; Bernoussi, A.

2018-04-01

In this work, we introduce the basic reproduction number R0 for a general epidemic model with graded cure, relapse and nonlinear incidence rate in a non-constant population size. We established that the disease free-equilibrium state Ef is globally asymptotically exponentially stable if R0 1, we proved that the system model has at least one endemic state Ee. Then, by means of an appropriate Lyapunov function, we showed that Ee is unique and globally asymptotically stable under some acceptable biological conditions. On the other hand, we use two types of control to reduce the number of infectious individuals. The optimality system is formulated and solved numerically using a Gauss-Seidel-like implicit finite-difference method.

Nonvariceal upper gastrointestinal bleeding

International Nuclear Information System (INIS)

Burke, Stephen J.; Weldon, Derik; Sun, Shiliang; Golzarian, Jafar

2007-01-01

Nonvariceal upper gastrointestinal bleeding (NUGB) remains a major medical problem even after advances in medical therapy with gastric acid suppression and cyclooxygenase (COX-2) inhibitors. Although the incidence of upper gastrointestinal bleeding presenting to the emergency room has slightly decreased, similar decreases in overall mortality and rebleeding rate have not been experienced over the last few decades. Many causes of upper gastrointestinal bleeding have been identified and will be reviewed. Endoscopic, radiographic and angiographic modalities continue to form the basis of the diagnosis of upper gastrointestinal bleeding with new research in the field of CT angiography to diagnose gastrointestinal bleeding. Endoscopic and angiographic treatment modalities will be highlighted, emphasizing a multi-modality treatment plan for upper gastrointestinal bleeding. (orig.)

Nonvariceal upper gastrointestinal bleeding

Energy Technology Data Exchange (ETDEWEB)

Burke, Stephen J.; Weldon, Derik; Sun, Shiliang [University of Iowa, Department of Radiology, Iowa, IA (United States); Golzarian, Jafar [University of Iowa, Department of Radiology, Iowa, IA (United States); University of Iowa, Department of Radiology, Carver College of Medicine, Iowa, IA (United States)

2007-07-15

Nonvariceal upper gastrointestinal bleeding (NUGB) remains a major medical problem even after advances in medical therapy with gastric acid suppression and cyclooxygenase (COX-2) inhibitors. Although the incidence of upper gastrointestinal bleeding presenting to the emergency room has slightly decreased, similar decreases in overall mortality and rebleeding rate have not been experienced over the last few decades. Many causes of upper gastrointestinal bleeding have been identified and will be reviewed. Endoscopic, radiographic and angiographic modalities continue to form the basis of the diagnosis of upper gastrointestinal bleeding with new research in the field of CT angiography to diagnose gastrointestinal bleeding. Endoscopic and angiographic treatment modalities will be highlighted, emphasizing a multi-modality treatment plan for upper gastrointestinal bleeding. (orig.)

IMPACT OF MIGRATION ON TUBERCULOSIS AND HIV EPIDEMIC SITUATION IN RUSSIA

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O. B. Nechaeva

2015-01-01

Full Text Available The growing changes in migration and mobility of the population in Russia require additional study of the epidemic situation related to infectious diseases and evaluation of preparedness of specialized medical services and existing resources of the health care system. Assessment of the incidence rates shows the higher figures among foreign citizens compared to native population as regards tuberculosis (2013: 163.2 versus 61.6 per 100,000 population and lower figures for HIV-infection (107.5 versus 315.1 respectively.The study of behavioral risks of acquiring infectious diseases (HIV-infection, sexually transmitted diseases, tuberculosis and socio-economic living conditions and factors influencing on the self-referral to the Russian medical units conducted among labor migrants in St. Petersburg, showed fairly low level of awareness of socially important diseases and protection from infections in migrants. Due to the fear of deportation in case of detection of infectious diseases, high price of medical services and lack of motivation of the employer to pay for medical insurance, migrants often practice self-treatment. Very few migrants (10% present themselves for mandatory annual fluorography screening.A significant flow of refugees from Ukraine especially from the regions with high risk of infectious diseases require special attention from the Russian Ministry of Health and the relevant financial support.There is also a lack of cooperation between bodies of Rospotrebnadzor and medical units submitting data on notifications of HIV-infection and tuberculosis in foreign citizens. Coordination mechanisms have to be improved to overcome the found deficiencies. 

Rapid simulation of spatial epidemics: a spectral method.

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Brand, Samuel P C; Tildesley, Michael J; Keeling, Matthew J

2015-04-07

Spatial structure and hence the spatial position of host populations plays a vital role in the spread of infection. In the majority of situations, it is only possible to predict the spatial spread of infection using simulation models, which can be computationally demanding especially for large population sizes. Here we develop an approximation method that vastly reduces this computational burden. We assume that the transmission rates between individuals or sub-populations are determined by a spatial transmission kernel. This kernel is assumed to be isotropic, such that the transmission rate is simply a function of the distance between susceptible and infectious individuals; as such this provides the ideal mechanism for modelling localised transmission in a spatial environment. We show that the spatial force of infection acting on all susceptibles can be represented as a spatial convolution between the transmission kernel and a spatially extended 'image' of the infection state. This representation allows the rapid calculation of stochastic rates of infection using fast-Fourier transform (FFT) routines, which greatly improves the computational efficiency of spatial simulations. We demonstrate the efficiency and accuracy of this fast spectral rate recalculation (FSR) method with two examples: an idealised scenario simulating an SIR-type epidemic outbreak amongst N habitats distributed across a two-dimensional plane; the spread of infection between US cattle farms, illustrating that the FSR method makes continental-scale outbreak forecasting feasible with desktop processing power. The latter model demonstrates which areas of the US are at consistently high risk for cattle-infections, although predictions of epidemic size are highly dependent on assumptions about the tail of the transmission kernel. Copyright © 2015 Elsevier Ltd. All rights reserved.

The immunology of the allergy epidemic and the hygiene hypothesis.

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Lambrecht, Bart N; Hammad, Hamida

2017-09-19

The immunology of the hygiene hypothesis of allergy is complex and involves the loss of cellular and humoral immunoregulatory pathways as a result of the adoption of a Western lifestyle and the disappearance of chronic infectious diseases. The influence of diet and reduced microbiome diversity now forms the foundation of scientific thinking on how the allergy epidemic occurred, although clear mechanistic insights into the process in humans are still lacking. Here we propose that barrier epithelial cells are heavily influenced by environmental factors and by microbiome-derived danger signals and metabolites, and thus act as important rheostats for immunoregulation, particularly during early postnatal development. Preventive strategies based on this new knowledge could exploit the diversity of the microbial world and the way humans react to it, and possibly restore old symbiotic relationships that have been lost in recent times, without causing disease or requiring a return to an unhygienic life style.

Efficient control of epidemics spreading on networks: balance between treatment and recovery.

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Katarzyna Oleś

Full Text Available We analyse two models describing disease transmission and control on regular and small-world networks. We use simulations to find a control strategy that minimizes the total cost of an outbreak, thus balancing the costs of disease against that of the preventive treatment. The models are similar in their epidemiological part, but differ in how the removed/recovered individuals are treated. The differences in models affect choice of the strategy only for very cheap treatment and slow spreading disease. However for the combinations of parameters that are important from the epidemiological perspective (high infectiousness and expensive treatment the models give similar results. Moreover, even where the choice of the strategy is different, the total cost spent on controlling the epidemic is very similar for both models.

Networked SIS Epidemics With Awareness

KAUST Repository

Paarporn, Keith; Eksin, Ceyhun; Weitz, Joshua S.; Shamma, Jeff S.

2017-01-01

We study a susceptible-infected-susceptible 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

Gastrointestinal tuberculosis.

Science.gov (United States)

Galloway, D J; Scott, R N

1986-10-01

In the developed countries gastrointestinal tuberculosis is no longer common in clinical practice. In this setting the importance of the condition lies in the vagaries of its presentation and the fact that it is eminently treatable, usually by a combination of chemotherapy and surgery. The clinical features and complications of gastrointestinal tuberculosis are highlighted by the seven cases which we report. Diagnosis and treatment of this condition is discussed and attention is drawn to the importance of case notification. Clinicians should bear in mind the diagnosis of gastrointestinal tuberculosis when dealing with any patient with non-specific abdominal symptoms.

Spread pattern of the first dengue epidemic in the city of Salvador, Brazil

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Carvalho Marilia S

2008-02-01

Full Text Available Abstract Background The explosive epidemics of dengue that have been occurring in various countries have stimulated investigation into new approaches to improve understanding of the problem and to develop new strategies for controlling the disease. The objective of this study was to evaluate the characteristics of diffusion of the first dengue epidemic that occurred in the city of Salvador in 1995. Methods The epidemiological charts and records of notified cases of dengue in Salvador in 1995 constituted the source of data. The cases of the disease were georeferenced according to census areas (spatial units and epidemiological weeks (temporal unit. Kernel density estimation was used to identify the pattern of spatial diffusion using the R-Project computer software program. Results Of the 2,006 census areas in the city, 1,400 (70% registered cases of dengue in 1995 and the spatial distribution of these records revealed that by the end of 1995 practically the entire city had been affected by the virus, with the largest concentration of cases occurring in the western region, composed of census areas with a high population density and predominantly horizontal residences compared to the eastern region of the city, where there is a predominance of vertical residential buildings. Conclusion The pattern found in this study shows the characteristics of the classic process of spreading by contagion that is common to most infectious diseases. It was possible to identify the epicenter of the epidemic from which centrifugal waves of the disease emanated. Our results suggest that, if a more agile control instrument existed that would be capable of rapidly reducing the vector population within a few days or of raising the group immunity of the population by means of a vaccine, it would theoretically be possible to adopt control actions around the epicenter of the epidemic and consequently reduce the incidence of the disease in the city. This finding emphasizes

Zinc and gastrointestinal disease

Institute of Scientific and Technical Information of China (English)

Sonja; Skrovanek; Katherine; DiGuilio; Robert; Bailey; William; Huntington; Ryan; Urbas; Barani; Mayilvaganan; Giancarlo; Mercogliano; James; M; Mullin

2014-01-01

This review is a current summary of the role that both zinc deficiency and zinc supplementation can play in the etiology and therapy of a wide range of gastrointestinal diseases. The recent literature describing zinc action on gastrointestinal epithelial tight junctions and epithelial barrier function is described. Zinc enhancement of gastrointestinal epithelial barrier function may figure prominently in its potential therapeutic action in several gastrointestinal diseases.

Epidemic myalgia and myositis associated with human parechovirus type 3 infections occur not only in adults but also in children: findings in Yamagata, Japan, 2014.

Science.gov (United States)

Mizuta, K; Yamakawa, T; Kurokawa, K; Chikaoka, S; Shimizu, Y; Itagaki, T; Katsushima, F; Katsushima, Y; Ito, S; Aoki, Y; Matoba, Y; Tanaka, S; Yahagi, K

2016-04-01

We previously reported an association between human parechovirus type 3 (HPeV3) and epidemic myalgia with myositis in adults during summers in which an HPeV3 outbreak occurred in children. However, this disease association has not yet been reported elsewhere. We have since continued our surveillance to accumulate data on this disease association and to confirm whether myalgia occurs in children as well as adults. Between June and August 2014, we collected 380 specimens from children with infectious diseases. We also collected clinical specimens from two adult and three paediatric patients suspected of myalgia. We then performed virus isolation and reverse-transcription-PCR using the collected specimens. We detected HPeV3 in 26 children with infectious diseases, which we regarded as indicating an outbreak. We also confirmed HPeV3 infection in all patients suspected of myalgia. In particular the symptoms in two boys, complaining of myalgia and fever, closely matched the criteria for adult myalgia. Based on our findings from 2008, 2011 and 2014, we again urge that clinical consideration be given to the relationship between myalgia and HPeV3 infections during HPeV3 outbreaks in children. Furthermore, our observations from 2014 suggest that epidemic myalgia and myositis occur not only in adults but also in children.

Societal learning in epidemics: intervention effectiveness during the 2003 SARS outbreak in Singapore.

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John M Drake

Full Text Available BACKGROUND: Rapid response to outbreaks of emerging infectious diseases is impeded by uncertain diagnoses and delayed communication. Understanding the effect of inefficient response is a potentially important contribution of epidemic theory. To develop this understanding we studied societal learning during emerging outbreaks wherein patient removal accelerates as information is gathered and disseminated. METHODS AND FINDINGS: We developed an extension of a standard outbreak model, the simple stochastic epidemic, which accounts for societal learning. We obtained expressions for the expected outbreak size and the distribution of epidemic duration. We found that rapid learning noticeably affects the final outbreak size even when learning exhibits diminishing returns (relaxation. As an example, we estimated the learning rate for the 2003 outbreak of severe acute respiratory syndrome (SARS in Singapore. Evidence for relaxation during the first eight weeks of the outbreak was inconclusive. We estimated that if societal learning had occurred at half the actual rate, the expected final size of the outbreak would have reached nearly 800 cases, more than three times the observed number of infections. By contrast, the expected outbreak size for societal learning twice as effective was 116 cases. CONCLUSION: These results show that the rate of societal learning can greatly affect the final size of disease outbreaks, justifying investment in early warning systems and attentiveness to disease outbreak by both government authorities and the public. We submit that the burden of emerging infections, including the risk of a global pandemic, could be efficiently reduced by improving procedures for rapid detection of outbreaks, alerting public health officials, and aggressively educating the public at the start of an outbreak.

Sensitivity analysis of infectious disease models: methods, advances and their application

Science.gov (United States)

Wu, Jianyong; Dhingra, Radhika; Gambhir, Manoj; Remais, Justin V.

2013-01-01

Sensitivity analysis (SA) can aid in identifying influential model parameters and optimizing model structure, yet infectious disease modelling has yet to adopt advanced SA techniques that are capable of providing considerable insights over traditional methods. We investigate five global SA methods—scatter plots, the Morris and Sobol’ methods, Latin hypercube sampling-partial rank correlation coefficient and the sensitivity heat map method—and detail their relative merits and pitfalls when applied to a microparasite (cholera) and macroparasite (schistosomaisis) transmission model. The methods investigated yielded similar results with respect to identifying influential parameters, but offered specific insights that vary by method. The classical methods differed in their ability to provide information on the quantitative relationship between parameters and model output, particularly over time. The heat map approach provides information about the group sensitivity of all model state variables, and the parameter sensitivity spectrum obtained using this method reveals the sensitivity of all state variables to each parameter over the course of the simulation period, especially valuable for expressing the dynamic sensitivity of a microparasite epidemic model to its parameters. A summary comparison is presented to aid infectious disease modellers in selecting appropriate methods, with the goal of improving model performance and design. PMID:23864497

Learning lessons from operational research in infectious diseases: can the same model be used for noncommunicable diseases in developing countries?

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Bosu WK

2014-12-01

Full Text Available William K Bosu Department of Epidemics and Disease Control, West African Health Organisation, Bobo-Dioulasso, Burkina Faso Abstract: About three-quarters of global deaths from noncommunicable diseases (NCDs occur in developing countries. Nearly a third of these deaths occur before the age of 60 years. These deaths are projected to increase, fueled by such factors as urbanization, nutrition transition, lifestyle changes, and aging. Despite this burden, there is a paucity of research on NCDs, due to the higher priority given to infectious disease research. Less than 10% of research on cardiovascular diseases comes from developing countries. This paper assesses what lessons from operational research on infectious diseases could be applied to NCDs. The lessons are drawn from the priority setting for research, integration of research into programs and routine service delivery, the use of routine data, rapid-assessment survey methods, modeling, chemoprophylaxis, and the translational process of findings into policy and practice. With the lines between infectious diseases and NCDs becoming blurred, it is justifiable to integrate the programs for the two disease groups wherever possible, eg, screening for diabetes in tuberculosis. Applying these lessons will require increased political will, research capacity, ownership, use of local expertise, and research funding. Keywords: infectious diseases, noncommunicable diseases, operational research, developing countries, integration

Epidemics in interconnected small-world networks.

Science.gov (United States)

Liu, Meng; Li, Daqing; Qin, Pengju; Liu, Chaoran; Wang, Huijuan; Wang, Feilong

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 has rarely been considered. Here, we study the susceptible-infected-susceptible (SIS) model of epidemic spreading in a system comprising two interconnected small-world networks. We find that the epidemic threshold in such networks decreases when the rewiring probability of the component small-world networks increases. When the infection rate is low, the rewiring probability affects the global steady-state infection density, whereas when the infection rate is high, the infection density is insensitive to the rewiring probability. Moreover, epidemics in interconnected small-world networks are found to spread at different velocities that depend on the rewiring probability.

Epidemics in interconnected small-world networks.

Directory of Open Access Journals (Sweden)

Meng Liu

Full Text Available 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 has rarely been considered. Here, we study the susceptible-infected-susceptible (SIS model of epidemic spreading in a system comprising two interconnected small-world networks. We find that the epidemic threshold in such networks decreases when the rewiring probability of the component small-world networks increases. When the infection rate is low, the rewiring probability affects the global steady-state infection density, whereas when the infection rate is high, the infection density is insensitive to the rewiring probability. Moreover, epidemics in interconnected small-world networks are found to spread at different velocities that depend on the rewiring probability.

Spatial distribution of 12 class B notifiable infectious diseases in China: A retrospective study.

Science.gov (United States)

Zhu, Bin; Fu, Yang; Liu, Jinlin; Mao, Ying

2018-01-01

China is the largest developing country with a relatively developed public health system. To further prevent and eliminate the spread of infectious diseases, China has listed 39 notifiable infectious diseases characterized by wide prevalence or great harm, and classified them into classes A, B, and C, with severity decreasing across classes. Class A diseases have been almost eradicated in China, thus making class B diseases a priority in infectious disease prevention and control. In this retrospective study, we analyze the spatial distribution patterns of 12 class B notifiable infectious diseases that remain active all over China. Global and local Moran's I and corresponding graphic tools are adopted to explore and visualize the global and local spatial distribution of the incidence of the selected epidemics, respectively. Inter-correlations of clustering patterns of each pair of diseases and a cumulative summary of the high/low cluster frequency of the provincial units are also provided by means of figures and maps. Of the 12 most commonly notifiable class B infectious diseases, viral hepatitis and tuberculosis show high incidence rates and account for more than half of the reported cases. Almost all the diseases, except pertussis, exhibit positive spatial autocorrelation at the provincial level. All diseases feature varying spatial concentrations. Nevertheless, associations exist between spatial distribution patterns, with some provincial units displaying the same type of cluster features for two or more infectious diseases. Overall, high-low (unit with high incidence surrounded by units with high incidence, the same below) and high-high spatial cluster areas tend to be prevalent in the provincial units located in western and southwest China, whereas low-low and low-high spatial cluster areas abound in provincial units in north and east China. Despite the various distribution patterns of 12 class B notifiable infectious diseases, certain similarities between

The physiological challenges of the 1952 Copenhagen poliomyelitis epidemic and a renaissance in clinical respiratory physiology

Science.gov (United States)

West, John B.

2005-01-01

The 1952 Copenhagen poliomyelitis epidemic provided extraordinary challenges in applied physiology. Over 300 patients developed respiratory paralysis within a few weeks, and the ventilator facilities at the infectious disease hospital were completely overwhelmed. The heroic solution was to call upon 200 medical students to provide round-the-clock manual ventilation using a rubber bag attached to a tracheostomy tube. Some patients were ventilated in this way for several weeks. A second challenge was to understand the gas exchange and acid-base status of these patients. At the onset of the epidemic, the only measurement routinely available in the hospital was the carbon dioxide concentration in the blood, and the high values were initially misinterpreted as a mysterious “alkalosis.” However, pH measurements were quickly instituted, the PCO2 was shown to be high, and modern clinical respiratory acid-base physiology was born. Taking a broader view, the problems highlighted by the epidemic underscored the gap between recent advances made by physiologists and their application to the clinical environment. However, the 1950s ushered in a renaissance in clinical respiratory physiology. In 1950 the coverage of respiratory physiology in textbooks was often woefully inadequate, but the decade saw major advances in topics such as mechanics and gas exchange. An important development was the translation of the new knowledge from departments of physiology to the clinical setting. In many respects, this period was therefore the beginning of modern clinical respiratory physiology. PMID:16020437

Infectious and non-infectious neurologic complications in heart transplant recipients.

Science.gov (United States)

Muñoz, Patricia; Valerio, Maricela; Palomo, Jesús; Fernández-Yáñez, Juan; Fernández-Cruz, Ana; Guinea, Jesús; Bouza, Emilio

2010-05-01

Neurologic complications are important causes of morbidity and mortality in heart transplant (HT) recipients. New immunomodulating agents have improved survival rates, although some have been associated with a high rate of neurologic complications (infectious and non-infectious). We conducted this study to analyze the frequency of these complications, before and after the use of daclizumab induction therapy. We reviewed all neurologic complications in our HT cohort, comparing infectious with non-infectious complications over 2 periods of time in which different induction therapies were used (316 patients with OKT3 or antithymocyte globulin from 1988 to 2002, and 68 patients with daclizumab from 2003 to 2006). Neurologic complications were found in 75/384 patients (19.5%) with a total of 78 episodes. Non-infectious complications accounted for 68% of the 78 episodes of neurologic complications. A total of 51 patients and 53 episodes were detailed as follows: 25 episodes of stroke (25 of 78 total episodes, 32%; 19 ischemic, 6 hemorrhagic); 7 neuropathies; 6 seizures; 4 episodes of transient ischemic attack (TIA); 3 anoxic encephalopathy; 2 each brachial plexus palsy and metabolic encephalopathy; and 1 each myoclonia, central nervous system (CNS) lymphoma, subdural hematoma, and Cotard syndrome. Mean time to presentation of stroke, TIA, and encephalopathy was 1 day (range, 1-19 d) posttransplant. Mortality rate among non-infectious complications was 12/53 (22.6%). Infectious complications accounted for 32% of the 78 total episodes. We found 25 episodes in 24 patients: 17 herpes zoster (median, 268 d after HT), 3 CNS aspergillosis (median, 90 d after HT), 1 CNS toxoplasmosis and tuberculosis (51 d after HT), 1 pneumococcal meningitis (402 d after HT), and 2 Listeria meningitis (median, 108 d after HT). The 3 patients with CNS aspergillosis died. The mortality rate among patients with infectious neurologic complications was 12% (42.8% if the CNS was involved). When we

Modeling the Effects of Duration and Size of the Control Zones on the Consequences of a Hypothetical African Swine Fever Epidemic in Denmark

DEFF Research Database (Denmark)

Halasa, Tariq; Bøtner, Anette; Mortensen, Sten

2018-01-01

control an epidemic of ASF. A previously published and well documented simulation model for ASF virus spread between herds was used to examine the epidemiologic and economic impacts of the duration and size of the control zones around affected herds. In the current study, scenarios were run, where......African swine fever (ASF) is a notifiable infectious disease. The disease is endemic in certain regions in Eastern Europe constituting a risk of ASF spread toward Western Europe. Therefore, as part of contingency planning, it is important to continuously explore strategies that can effectively...... or clinical and serological surveillance of herds within the zones. Sensitivity analysis was conducted on influential input parameters in the model. The model predicts that reducing the duration of the protection and surveillance zones has no impact on the epidemiological consequences of the epidemics, while...

Cytokine patterns in paediatric patients presenting serious gastrointestinal and respiratory bacterial infections

Science.gov (United States)

Palacios-Martínez, Monika; Rodríguez-Cruz, Leonor; Cortés-Bejar, Consuelo Del Carmen; Valencia-Chavarría, Fernando; Martínez-Gómez, Daniel; González-Torres, María Cristina

2014-01-01

In the adaptive immune response, the types of cytokines produced define whether there is a cellular (T1) or a humoral (T2) response. Specifically, in the T1 response, interleukin 2 (IL-2), interferon γ (IFN-γ) and tumor necrosis factor β (TNF-β) are produced, whereas in the T2 response, IL-4, IL-5, IL- 6, IL-10 and IL-13 are primarily produced. Cytokines are primarily involved in the regulation of immune system cells. The aim of the present study was to evaluate the cytokine patterns (Type 1/Type 2) and TNF-α expression levels in children with severe gastrointestinal and respiratory bacterial infections. The enzyme-linked immunosorbent assay (ELISA) technique was used to identify the cytokines and the infectious agents. The results obtained demonstrated that, in general, children with bacterial infections experienced an increase in IL-2, IFN-γ and IL-4 concentrations and a decrease in TNF-α, IL-5 and IL-6 concentrations when compared to healthy children. Specifically, type 1 cytokines and an increased TNF-α concentration were found in children with gastrointestinal infections. However, patients with respiratory infections showed increased concentrations of both T2 (IL-4, IL-6 and IL-10) and T1 (IL-2 and IFN-γ) components. Thus, it was concluded that children with gastrointestinal infections exclusively developed a T1 response, whereas children with respiratory infections developed a T1/T2 response to fight the infection. PMID:26155128

Infectious Diseases

Science.gov (United States)

... But some of them can make you sick. Infectious diseases are diseases that are caused by germs. There ... many different ways that you can get an infectious disease: Through direct contact with a person who is ...

Can rapid integrated polymerase chain reaction-based diagnostics for gastrointestinal pathogens improve routine hospital infection control practice? A diagnostic study.

Science.gov (United States)

Pankhurst, Louise; Macfarlane-Smith, Louissa; Buchanan, James; Anson, Luke; Davies, Kerrie; O'Connor, Lily; Ashwin, Helen; Pike, Graham; Dingle, Kate E; Peto, Timothy Ea; Wordsworth, Sarah; Walker, A Sarah; Wilcox, Mark H; Crook, Derrick W

2014-08-01

Code assay, sensitivities for each organism compared with standard microbiological testing ranged from 43% to 94% and specificities from 95% to 98%, with particularly poor performance for S. enterica. Relatively large numbers of unexpected positives not confirmed with quantitative PCR were also observed, particularly for S. enterica, Giardia lamblia and Cryptosporidium spp. As the results indicated that S. enterica detection might provide generic challenges to other multiplex assays for gastrointestinal pathogens, the Luminex xTag(®) gastrointestinal assay was also run blinded on the same extracts (937/948 remaining) and on re-extracted samples (839/948 with sufficient material). For Campylobacter spp., C. difficile and norovirus, high sensitivities (> 92%) and specificities (> 96%) were observed. For S. enterica, on the original MassCode/Oxford extracts, Luminex sensitivity compared with standard microbiological testing was 84% [95% confidence interval (CI) 73% to 93%], but this dropped to 46% on a fresh extract, very similar to MassCode, with a corresponding increase in specificity from 92% to 99%. Overall agreement on the per-sample diagnosis compared with combined microbiology plus PCR for the main four/all pathogens was 85.6%/64.7%, 87.0%/82.9% and 89.8%/86.8% for the MassCode assay, Luminex assay/MassCode extract and Luminex assay/fresh extract, respectively. Luminex assay results from fresh extracts implied that 5% of samples did not represent infectious diarrhoea, even though enteropathogens were genuinely present. Managing infectious diarrhoea was a significant burden for infection control teams (taking 21% of their time) and better diagnostics were identified as having major potential benefits for patients. Overall, the Luminex xTag gastrointestinal panel showed similar or superior sensitivity and specificity to the MassCode assay. However, on fresh extracts, this test had low sensitivity to detect a key enteric pathogen, S. enterica; making it an unrealistic

[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.

Concurrency can drive an HIV epidemic by moving R0 across the epidemic threshold

NARCIS (Netherlands)

Leung, Ka Yin; Kretzschmar, Mirjam

2015-01-01

OBJECTIVE: The objective of this study is to investigate whether concurrency can drive an HIV epidemic by moving R0 across the epidemic threshold. DESIGN AND METHODS: We use a mathematical framework for a dynamic partnership network and the spread of a one-stage infection to study how concurrency is

Ebola epidemic--Liberia, March-October 2014.

Science.gov (United States)

Nyenswah, Tolbert; Fahnbulleh, Miatta; Massaquoi, Moses; Nagbe, Thomas; Bawo, Luke; Falla, James Dorbor; Kohar, Henry; Gasasira, Alex; Nabeth, Pierre; Yett, Sheldon; Gergonne, Bernadette; Casey, Sean; Espinosa, Benjamin; McCoy, Andrea; Feldman, Heinz; Hensley, Lisa; Baily, Mark; Fields, Barry; Lo, Terrence; Lindblade, Kim; Mott, Josh; Boulanger, Lucy; Christie, Athalia; Wang, Susan; Montgomery, Joel; Mahoney, Frank

2014-11-21

On March 21, 2014, the Guinea Ministry of Health reported the outbreak of an illness characterized by fever, severe diarrhea, vomiting and a high fatality rate (59%), leading to the first known epidemic of Ebola virus disease (Ebola) in West Africa and the largest and longest Ebola epidemic in history. As of November 2, Liberia had reported the largest number of cases (6,525) and deaths (2,697) among the three affected countries of West Africa with ongoing transmission (Guinea, Liberia, and Sierra Leone). The response strategy in Liberia has included management of the epidemic through an incident management system (IMS) in which the activities of all partners are coordinated. Within the IMS, key strategies for epidemic control include surveillance, case investigation, laboratory confirmation, contact tracing, safe transportation of persons with suspected Ebola, isolation, infection control within the health care system, community engagement, and safe burial. This report provides a brief overview of the progression of the epidemic in Liberia and summarizes the interventions implemented.

Epidemic Spreading with Heterogeneous Awareness on Human Networks

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Yanling Lu

2017-01-01

Full Text Available The spontaneous awareness behavioral responses of individuals have a significant impact on epidemic spreading. In this paper, a modified Susceptible-Alert-Infected-Susceptible (SAIS epidemic model with heterogeneous awareness is presented to study epidemic spreading in human networks and the impact of heterogeneous awareness on epidemic dynamics. In this model, when susceptible individuals receive awareness information about the presence of epidemic from their infected neighbor nodes, they will become alert individuals with heterogeneous awareness rate. Theoretical analysis and numerical simulations show that heterogeneous awareness can enhance the epidemic threshold with certain conditions and reduce the scale of virus outbreaks compared with no awareness. What is more, for the same awareness parameter, it also shows that heterogeneous awareness can slow effectively the spreading size and does not delay the arrival time of epidemic spreading peak compared with homogeneous awareness.

Epidemics in adaptive networks with community structure

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Shaw, Leah; Tunc, Ilker

2010-03-01

Models for epidemic spread on static social networks do not account for changes in individuals' social interactions. Recent studies of adaptive networks have modeled avoidance behavior, as non-infected individuals try to avoid contact with infectives. Such models have not generally included realistic social structure. Here we study epidemic spread on an adaptive network with community structure. We model the effect of heterogeneous communities on infection levels and epidemic extinction. We also show how an epidemic can alter the community structure.

Development of functional gastrointestinal disorders after Giardia lamblia infection

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Hanevik Kurt

2009-04-01

Full Text Available Abstract Background Functional gastrointestinal disorders (FGID may occur following acute gastroenteritis. This long-term complication has previously not been described after infection with the non-invasive protozoan Giardia lamblia. This study aims to characterize persistent abdominal symptoms elicited by Giardia infection according to Rome II criteria and symptoms scores. Methods Structured interview and questionnaires 12–30 months after the onset of Giardia infection, and at least 6 months after Giardia eradication, among 82 patients with persisting abdominal symptoms elicited by the Giardia infection. All had been evaluated to exclude other causes. Results We found that 66 (80.5% of the 82 patients had symptoms consistent with irritable bowel syndrome (IBS and 17 (24.3% patients had functional dyspepsia (FD according to Rome II criteria. IBS was sub classified into D-IBS (47.0%, A-IBS (45.5% and C-IBS (7.6%. Bloating, diarrhoea and abdominal pain were reported to be most severe. Symptoms exacerbation related to specific foods were reported by 45 (57.7% patients and to physical or mental stress by 34 (44.7% patients. Conclusion In the presence of an IBS-subtype pattern consistent with post-infectious IBS (PI-IBS, and in the absence of any other plausible causes, we conclude that acute Giardia infection may elicit functional gastrointestinal diseases with food and stress related symptoms similar to FGID patients in general.

Meta-genomic analysis of toilet waste from long distance flights; a step towards global surveillance of infectious diseases and antimicrobial resistance

DEFF Research Database (Denmark)

Petersen, Thomas Nordahl; Rasmussen, Simon; Hasman, Henrik

2015-01-01

Human populations worldwide are increasingly confronted with infectious diseases and antimicrobial resistance spreading faster and appearing more frequently. Knowledge regarding their occurrence and worldwide transmission is important to control outbreaks and prevent epidemics. Here, we performed...... for bacteria and antimicrobial resistance genes. An average of 106,839 (0.06%) reads were assigned to resistance genes with genes encoding resistance to tetracycline, macrolide and beta-lactam resistance genes as the most abundant in all samples. We found significantly higher abundance and diversity of genes...

Epidemic spreading on weighted complex networks

International Nuclear Information System (INIS)

Sun, Ye; Liu, Chuang; Zhang, Chu-Xu; Zhang, Zi-Ke

2014-01-01

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.

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.

Investigation of airborne foot-and-mouth disease virus transmission during low-wind conditions in the early phase of the UK 2001 epidemic

DEFF Research Database (Denmark)

Mikkelsen, T.; Alexandersen, S.; Astrup, P.

2003-01-01

animals. Such spread can be rapid and extensive, and it is known in certain circumstances to have transmitted disease over a distance of several hundred kilometres. During the 2001 FMD epidemic in the United Kingdom (UK), atmospheric dispersion models were applied in real time in order to assess...... techniques and presents the results obtained of detailed analyses performed during the early stages of the UK 2001 epidemic. This paper investigates the potential for disease spread in relation to two outbreaks (Burnside Farm, Heddon-on-the-Wall and Prestwick Hall Farm, Ponteland, Northumberland). A separate...... and secretions which can be infectious, the stability of the virus in the environment, the multiplicity of routes of infection and the very small doses of the virus that can initiate infection. One of the mechanisms of spread is the carriage of droplets and droplet nuclei exhaled in the breath of infected...

Disease-induced mortality in density-dependent discrete-time S-I-S epidemic models.

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Franke, John E; Yakubu, Abdul-Aziz

2008-12-01

The dynamics of simple discrete-time epidemic models without disease-induced mortality are typically characterized by global transcritical bifurcation. We prove that in corresponding models with disease-induced mortality a tiny number of infectious individuals can drive an otherwise persistent population to extinction. Our model with disease-induced mortality supports multiple attractors. In addition, we use a Ricker recruitment function in an SIS model and obtained a three component discrete Hopf (Neimark-Sacker) cycle attractor coexisting with a fixed point attractor. The basin boundaries of the coexisting attractors are fractal in nature, and the example exhibits sensitive dependence of the long-term disease dynamics on initial conditions. Furthermore, we show that in contrast to corresponding models without disease-induced mortality, the disease-free state dynamics do not drive the disease dynamics.

Distribution of sasX, pvl, and qacA/B genes in epidemic methicillin-resistant Staphylococcus aureus strains isolated from East China

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Kong H

2018-01-01

Full Text Available Haishen Kong,1,2 Lingmei Fang,3 Rujin Jiang,4 Jixiang Tong2 1State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; 2Key Laboratory of Clinical In Vitro Diagnostic Techniques of Zhejiang Province, Department of Laboratory Medicine, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; 3Clinical Laboratory, Chunan First People’s Hospital, Zhejiang Province People’s Hospital Chunan Branch, Hangzhou, China; 4Clinical Laboratory, Yuhang Hospital of Traditional Chinese Medicine, Hangzhou, China Background: Methicillin-resistant Staphylococcus aureus (MRSA is a major nosocomial pathogen. Various virulence and antiseptic-resistant factors increase the pathogenicity of MRSA strains and allow for increased infection rates.Purpose: The purpose of this study was to investigate the prevalence and distribution of virulence-associated and antiseptic-resistant genes from epidemic MRSA strains isolated from East China.Methods: A newly designed multiplex PCR assay was used to assess whether the virulence-associated genes sasX and pvl and the chlorhexidine tolerance gene qacA/B were present in 189 clinical isolates of MRSA. Multilocus sequence typing (MLST and Staphylococcal protein A (spa typing of these isolates were also performed. The frequency of these genes in isolates with epidemic sequence types (STs was investigated. Results: Twenty STs and 36 spa types with five epidemic clones (ST5-t311, ST59-t437, ST5-t002, ST239-t030, and ST239-t037 were identified. The prevalence of sasX, pvl, and qacA/B in all isolates was 5.8%, 10.1%, and 20.1%, respectively. The prevalences of these genes in isolates with ST5, ST59, ST239, and other ST genetic backgrounds were all significantly different (P<0.001. Isolates that had the highest frequency of sas

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

Epidemic cholera spreads like wildfire

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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.

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. ...... to prevent contact allergy epidemics. It is essential that dermatologist, scientists, administrators, and consumers organize and structure known methods to accelerate the control of emerging contact allergens....

EVALUATION AND PREDICTIVE METHODS OF EPIDEMICAL SITUATION IN THE AREA OF ACUTE ENTERIC INFECTIONS

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Malysh N.G.

2017-06-01

Full Text Available Introduction. Despite the fact, that nowadays acute intestinal infections (AII sick rate is decreasing, the aggravation of the epidemical situation is always there. Increased attention to AII caused by unpredictable epidemical rises of the AII diseases, which cannot be prevented without assessing the epidemical situation of these infections and forecasting of the levels of sick rate. However, developed mathematical methods of forecasting in most cases do not take into account the risk factors, also they are time-consuming and it is difficult to calculate them; and developed special computer programs, which predict infectious sick rates, are often in the lack in the institutions of sanitary-epidemiological service. An urgent problem for today is establishing of the most influential social and environmental factors, which can make a contribution to the spread of AII. The aim of this work was to improve the method of assessment and prediction of epidemic situation of AII by identifying the influence of climatic and demographic factors. Materials and methods. In order to determine the influence of meteorological and demographic factors on the epidemic process of acute intestinal infections the official reports of the State Sanitary and Epidemiological Service of Ukraine in Sumy region, the Department of Statistics, Sumy Regional Center for Hydrometeorology and Environmental Monitoring have been studied. Results and discussion. The work on the evaluation of the epidemiological situation of the AII begins from collecting data, according to the AII sick rate. The main source of this information is the logbook of infectious diseases, which recorded all sick people that were found in the area. It is necessary to gather the initial information, calculate the sick rate and monthly distribution of AII cases on investigated area and evaluate the tendency. At the same time with accounting of AII cases on investigated territory, takes place a monitoring of air

Pains and Gains from China’s Experiences with Emerging Epidemics: From SARS to H7N9

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Pengfei Wei

2016-01-01

Full Text Available Over the recent decades, China experienced several emerging virus outbreaks including those caused by the severe acute respiratory syndrome- (SARS- coronavirus (Cov, H5N1 virus, and H7N9 virus. The SARS tragedy revealed faults in China’s infectious disease prevention system, propelling the Chinese government to enact reforms that enabled better combating of the subsequent H1N1 and H7N9 avian flu epidemics. The system is buttressed by three fundamental, mutually reinforcing components: (1 enduring government administration reforms, including legislation establishing a unified public health emergency management system; (2 prioritized funding for biotechnology and biomedicine industrialization, especially in the areas of pathogen identification, drug production, and the development of vaccines and diagnostics; and (3 increasing investment for public health and establishment of a rapid-response infectious diseases prevention and control system. China is now using its hard-gained experience to support the fight against Ebola in Africa and the Middle East Respiratory Syndrome in its own country.

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

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

2017-09-01

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.

Angiography and the gastrointestinal bleeder

International Nuclear Information System (INIS)

Baum, S.

1982-01-01

The role of angiography in the diagnosis and treatment of gastrointestinal hemorrhage is discussed. Three categories of gastrointestinal bleeding are considered: upper gastrointestinal bleeding due to gastroesophageal varices, upper gastrointestinal bleeding of arterial or capillary origin, and lower gastrointestinal bleeding. The advantages and disadvantages of angiography are compared with those of radionuclide scanning and endoscopy or colonoscopy. It is anticipated that, as radionuclide scans are more widely employed, angiography will eventually be performed only in those patients with positive scans

Biophysical, infrastructural and social heterogeneities explain spatial distribution of waterborne gastrointestinal disease burden in Mexico City

Science.gov (United States)

Baeza, Andrés; Estrada-Barón, Alejandra; Serrano-Candela, Fidel; Bojórquez, Luis A.; Eakin, Hallie; Escalante, Ana E.

2018-06-01

Due to unplanned growth, large extension and limited resources, most megacities in the developing world are vulnerable to hydrological hazards and infectious diseases caused by waterborne pathogens. Here we aim to elucidate the extent of the relation between the spatial heterogeneity of physical and socio-economic factors associated with hydrological hazards (flooding and scarcity) and the spatial distribution of gastrointestinal disease in Mexico City, a megacity with more than 8 million people. We applied spatial statistics and multivariate regression analyses to high resolution records of gastrointestinal diseases during two time frames (2007–2009 and 2010–2014). Results show a pattern of significant association between water flooding events and disease incidence in the city center (lowlands). We also found that in the periphery (highlands), higher incidence is generally associated with household infrastructure deficiency. Our findings suggest the need for integrated and spatially tailored interventions by public works and public health agencies, aimed to manage socio-hydrological vulnerability in Mexico City.

Upper Gastrointestinal Complications and Cardiovascular/Gastrointestinal Risk Calculator in Patients with Myocardial Infarction Treated with Aspirin.

Science.gov (United States)

Wen, Lei

2017-08-20

Aspirin is widely used for the prevention of cardiovascular and cerebrovascular diseases for the past few years. However, much attention has been paid to the adverse effects associated with aspirin such as gastrointestinal bleeding. How to weigh the benefits and hazards? The current study aimed to assess the feasibility of a cardiovascular/gastrointestinal risk calculator, AsaRiskCalculator, in predicting gastrointestinal events in Chinese patients with myocardial infarction (MI), determining unique risk factor(s) for gastrointestinal events to be considered in the calculator. The MI patients who visited Shapingba District People's Hospital between January 2012 and January 2016 were retrospectively reviewed. Based on gastroscopic data, the patients were divided into two groups: gastrointestinal and nongastrointestinal groups. Demographic and clinical data of the patients were then retrieved for statistical analysis. Univariate and multiple logistic regression analyses were used to identify independent risk factors for gastrointestinal events. The receiver operating characteristic (ROC) curves were used to assess the predictive value of AsaRiskCalculator for gastrointestinal events. A total of 400 MI patients meeting the eligibility criteria were analyzed, including 94 and 306 in the gastrointestinal and nongastrointestinal groups, respectively. The data showed that age, male gender, predicted gastrointestinal events, and Helicobacter pylori (HP) infection were positively correlated with gastrointestinal events. In multiple logistic regression analysis, predicted gastrointestinal events and HP infection were identified as risk factors for actual gastrointestinal events. HP infection was highly predictive in Chinese patients; the ROC curve indicated an area under the curve of 0.822 (95% confidence interval: 0.774-0.870). The best diagnostic cutoff point of predicted gastrointestinal events was 68.0‰, yielding sensitivity and specificity of 60.6% and 93

Can rewiring strategy control the epidemic spreading?

Science.gov (United States)

Dong, Chao; Yin, Qiuju; Liu, Wenyang; Yan, Zhijun; Shi, Tianyu

2015-11-01

Relation existed in the social contact network can affect individuals' behaviors greatly. Considering the diversity of relation intimacy among network nodes, an epidemic propagation model is proposed by incorporating the link-breaking threshold, which is normally neglected in the rewiring strategy. The impact of rewiring strategy on the epidemic spreading in the weighted adaptive network is explored. The results show that the rewiring strategy cannot always control the epidemic prevalence, especially when the link-breaking threshold is low. Meanwhile, as well as strong links, weak links also play a significant role on epidemic spreading.

Influenza in Poland in 2013 and 2013/2014 epidemic season

Science.gov (United States)

Kondratiuk, Katarzyna; Czarkowski, Mirosław P; Hallmann-Szelińska, Ewelina; Staszewska, Ewa; Bednarska, Karolina; Cielebąk, Ewa; Brydak, Lidia B

2016-01-01

Analysis of epidemiological situation of influenza in Poland in 2013 and 2013/14 epidemic season in reference to previous years and seasons. Analysis was based on: 1) data collected within influenza routine surveillance system in Poland, including data published in annual bulletins “Infectious diseases and poisonings in Poland” as well as unpublished data gathered in the Department of Epidemiology of the NIPH-NIH; 2) data collected within influenza system - Sentinel, and beyond this system, concerning results of virological tests carried out in 2013/14 epidemic season in the Department of Influenza Research, National Influenza Center in the NIPHNIH and/or laboratories of provincial sanitary and epidemiological stations which are gathered in the National Influenza Center. Compared to 2012, the number of influenza and influenza-like cases increased more than twofold in 2013 in Poland. A total of 3 164 405 cases were reported. Incidence was 8 218.7 per 100,000 population (33 733.2 in 0-4 age group). As many as 0.45% of patients were referred to hospitals. According to the data of the Central Statistical Office, 115 deaths due to influenza were notified. Based on the data of the sanitary inspection (incomplete data), the percentage of population vaccinated against influenza was 2.4% (7.7% of persons aged more than 64 years). A total of 2 780 945 cases were registered in 2013/14 epidemic season. Its peak was reported in March 2014. Incidence was 7 224.0 per 100,000 population (35 172.8 in 0-4 age group). Compared to 2012/13 epidemic season, it was lower by 8.0%. Incidence rates ranged from 29 339.6 in pomorskie voivodeship to 1 306.5 in lubuskie voivodeship. Nearly a half of all cases (48.7%) were registered in children and adolescents up to 15 years. As many as 0.34% of patients were referred to hospitals (0.87% of persons aged more than 64 years). From the data of the Central Statistical Office transpires that 8 deaths due to influenza were reported in epidemic

Defining and detecting malaria epidemics in south-east Iran.

Science.gov (United States)

McKelvie, William R; Haghdoost, Ali Akbar; Raeisi, Ahmad

2012-03-23

A lack of consensus on how to define malaria epidemics has impeded the evaluation of early detection systems. This study aimed to develop local definitions of malaria epidemics in a known malarious area of Iran, and to use that definition to evaluate the validity of several epidemic alert thresholds. Epidemic definition variables generated from surveillance data were plotted against weekly malaria counts to assess which most accurately labelled aberrations. Various alert thresholds were then generated from weekly counts or log counts. Finally, the best epidemic definition was used to calculate and compare sensitivities, specificities, detection delays, and areas under ROC curves of the alert thresholds. The best epidemic definition used a minimum duration of four weeks and week-specific and overall smoothed geometric means plus 1.0 standard deviation. It defined 13 epidemics. A modified C-SUM alert of untransformed weekly counts using a threshold of mean+0.25 SD had the highest combined sensitivity and specificity. Untransformed C-SUM alerts also had the highest area under the ROC curve. Defining local malaria epidemics using objective criteria facilitated the evaluation of alert thresholds. This approach needs further study to refine epidemic definitions and prospectively evaluate epidemic alerts.

Effect of hand hygiene on infectious diseases in the office workplace: A systematic review.

Science.gov (United States)

Zivich, Paul N; Gancz, Abigail S; Aiello, Allison E

2018-04-01

Extensive data suggests that hand hygiene is a critical intervention for reducing infectious disease transmission in the clinical setting. However, it is unclear whether hand hygiene is effective at cutting down on infectious illnesses in non-clinical workplaces. The aim of this review is to assess the current literature concerning the effects of hand-washing interventions on infectious disease prevention among employees in nonclinical, office-based workplaces. In compiling this review, PubMed, Scopus, and Business Source Premier were examined for studies published from 1960 through 2016. Eleven studies (eight experimental, two observational, one a simulation) were identified as eligible for inclusion. Hand-hygiene interventions at various levels of rigor were shown to reduce self-reported illness symptoms. Hand hygiene is thought to be more effective against gastrointestinal illness than it is against respiratory illness, but no clear consensus has been reached on this point. Minimal hand-hygiene interventions seem to be effective at reducing the incidence of employee illness. Along with reducing infections among employees, hand-hygiene programs in the workplace may provide additional benefits to employers by reducing the number of employee health insurance claims and improving employee morale. Future research should use objective measures of hand hygiene and illness, and explore economic impacts on employers more fully. Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Multi-scale model of epidemic fade-out: Will local extirpation events inhibit the spread of white-nose syndrome?

Science.gov (United States)

O'Reagan, Suzanne M; Magori, Krisztian; Pulliam, J Tomlin; Zokan, Marcus A; Kaul, RajReni B; Barton, Heather D; Drake, John M

2015-04-01

White-nose syndrome (WNS) is an emerging infectious disease that has resulted in severe declines of its hibernating bat hosts in North America. The ongoing epidemic of white-nose syndrome is a multi-scale phenomenon becau.se it causes hibernaculum-level extirpations, while simultaneously spreading over larger spatial scales. We investigate a neglected topic in ecological epidemiology: how local pathogen-driven extirpations impact large-scale pathogen spread. Previous studies have identified risk factors for propagation of WNS over hibernaculum and landscape scales but none of these have tested the hypothesis that separation of spatial scales and disease-induced mortality at the hibernaculum level might slow or halt its spread. To test this hypothesis, we developed a mechanistic multi-scale model parameterized using white-nose syndrome.county and site incidence data that connects hibernaculum-level susceptible-infectious-removed (SIR) epidemiology to the county-scale contagion process. Our key result is that hibernaculum-level extirpations will not inhibit county-scale spread of WNS. We show that over 80% of counties of the contiguous USA are likely to become infected before the current epidemic is over and that geometry of habitat connectivity is such that host refuges are exceedingly rare. The macroscale spatiotemporal infection pattern that emerges from local SIR epidemiological processes falls within a narrow spectrum of possible outcomes, suggesting that recolonization, rescue effects, and multi-host complexities at local scales are not important to forward propagation of WNS at large spatial scales. If effective control measures are not implemented, precipitous declines in bat populations are likely, particularly in cave-dense regions that constitute the main geographic corridors of the USA, a serious concern for bat conservation.

Bioengineering of Tobacco Mosaic Virus to Create a Non-Infectious Positive Control for Ebola Diagnostic Assays

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Lam, Patricia; Gulati, Neetu M.; Stewart, Phoebe L.; Keri, Ruth A.; Steinmetz, Nicole F.

2016-03-01

The 2014 Ebola epidemic is the largest to date. There is no cure or treatment for this deadly disease; therefore there is an urgent need to develop new diagnostics to accurately detect Ebola. Current RT-PCR assays lack sensitive and reliable positive controls. To address this critical need, we devised a bio-inspired positive control for use in RT-PCR diagnostics: we encapsulated scrambled Ebola RNA sequences inside of tobacco mosaic virus to create a biomimicry that is non-infectious, but stable, and could therefore serve as a positive control in Ebola diagnostic assays. Here, we report the bioengineering and validation of this probe.

Addressing population heterogeneity and distribution in epidemics models using a cellular automata approach.

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López, Leonardo; Burguerner, Germán; Giovanini, Leonardo

2014-04-12

The spread of an infectious disease is determined by biological and social factors. Models based on cellular automata are adequate to describe such natural systems consisting of a massive collection of simple interacting objects. They characterize the time evolution of the global system as the emergent behaviour resulting from the interaction of the objects, whose behaviour is defined through a set of simple rules that encode the individual behaviour and the transmission dynamic. An epidemic is characterized trough an individual-based-model built upon cellular automata. In the proposed model, each individual of the population is represented by a cell of the automata. This way of modeling an epidemic situation allows to individually define the characteristic of each individual, establish different scenarios and implement control strategies. A cellular automata model to study the time evolution of a heterogeneous populations through the various stages of disease was proposed, allowing the inclusion of individual heterogeneity, geographical characteristics and social factors that determine the dynamic of the desease. Different assumptions made to built the classical model were evaluated, leading to following results: i) for low contact rate (like in quarantine process or low density population areas) the number of infective individuals is lower than other areas where the contact rate is higher, and ii) for different initial spacial distributions of infected individuals different epidemic dynamics are obtained due to its influence on the transition rate and the reproductive ratio of disease. The contact rate and spatial distributions have a central role in the spread of a disease. For low density populations the spread is very low and the number of infected individuals is lower than in highly populated areas. The spacial distribution of the population and the disease focus as well as the geographical characteristic of the area play a central role in the dynamics of the

Susceptibility of Ae. aegypti (Diptera: Culicidae) to infection with epidemic (subtype IC) and enzootic (subtypes ID, IIIC, IIID) Venezuelan equine encephalitis complex alphaviruses.

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Ortiz, Diana I; Kang, Wenli; Weaver, Scoti C

2008-11-01

To test the hypothesis that enzootic and epidemic Venezuelan equine encephalitis (VEE) complex alphaviruses can infect and be transmitted by Ae. aegypti, we conducted a series of experimental infection studies. One set of experiments tested the susceptibility of geographic strains of Ae. aegypti from Peru and Texas (U.S.A.) for epidemic (subtype IC) and enzootic (subtype ID) strains from Colombia/Venezuela, whereas the second set of experiments tested the susceptibility of Ae. aegypti from Iquitos, Peru, to enzootic VEE complex strains (subtypes ID, IIIC, and IIID) isolated in the same region, at different infectious doses. Experimental infections using artificial bloodmeals suggested that Ae. aegypti mosquitoes, particularly the strain from Iquitos, Peru, is moderately to highly susceptible to all of these VEE complex alphaviruses. The occurrence of enzootic VEE complex viruses circulating endemically in Iquitos suggests the possibility of a dengue-like transmission cycle among humans in tropical cities.

[Infectious endocarditis due to Gemella morbillorum found by splenic infarction--a case report].

Science.gov (United States)

Hosaka, Yumiko; Kimura, Takuma; Suzuki, Ryo; Chong, Tonghyo; Shoji, Michi; Aoki, Yasuko

2010-09-01

A 64-year-old man with prostate cancer and bone metastasis admitted for nausea, left abdominal pain showed no abnormal, and fever, abdominal ultrasound or chest X-ray findings. Despite antibiotics, left abdominal pain persisted for several days. Abdominal computed tomography (CT), showed splenic infarction. Transesophageal echocardiography suggested infectious endocarditis (IE) as a possible infarction cause, and roth spots were found on the retina. Gemella morbillorum was detected from blood culture. IE commonly causes Fever of Unknown Origin found by infarction. G. morbillorum, an anaerobic gram-positive, viridans group streptococci, is indigenous to the oropharynx, upper respiratory, urogenital, and gastrointestinal tracts, and is thought to have weak toxicity and pathogenicity in the body.

Defining and detecting malaria epidemics in south-east Iran

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McKelvie William R

2012-03-01

Full Text Available Abstract Background A lack of consensus on how to define malaria epidemics has impeded the evaluation of early detection systems. This study aimed to develop local definitions of malaria epidemics in a known malarious area of Iran, and to use that definition to evaluate the validity of several epidemic alert thresholds. Methods Epidemic definition variables generated from surveillance data were plotted against weekly malaria counts to assess which most accurately labelled aberrations. Various alert thresholds were then generated from weekly counts or log counts. Finally, the best epidemic definition was used to calculate and compare sensitivities, specificities, detection delays, and areas under ROC curves of the alert thresholds. Results The best epidemic definition used a minimum duration of four weeks and week-specific and overall smoothed geometric means plus 1.0 standard deviation. It defined 13 epidemics. A modified C-SUM alert of untransformed weekly counts using a threshold of mean + 0.25 SD had the highest combined sensitivity and specificity. Untransformed C-SUM alerts also had the highest area under the ROC curve. Conclusions Defining local malaria epidemics using objective criteria facilitated the evaluation of alert thresholds. This approach needs further study to refine epidemic definitions and prospectively evaluate epidemic alerts.

Configuring the autism epidemic

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Seeberg, Jens; Christensen, Fie Lund Lindegaard

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....

Unsynchronized influenza epidemics in two neighboring subtropical cities

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Xiujuan Tang

2018-04-01

Full Text Available Objective: The aim of this study was to examine the synchrony of influenza epidemics between Hong Kong and Shenzhen, two neighboring subtropical cities in South China. Methods: Laboratory-confirmed influenza data for the period January 2006 to December 2016 were obtained from the Shenzhen Center for Disease Control and Prevention and the Department of Health in Hong Kong. The population data were retrieved from the 2011 population censuses. The weekly rates of laboratory-confirmed influenza cases were compared between Shenzhen and Hong Kong. Results: Unsynchronized influenza epidemics between Hong Kong and Shenzhen were frequently observed during the study period. Influenza A/H1N1 caused a more severe pandemic in Hong Kong in 2009, but the subsequent seasonal epidemics showed similar magnitudes in both cities. Two influenza A/H3N2 dominant epidemic waves were seen in Hong Kong in 2015, but these epidemics were very minor in Shenzhen. More influenza B epidemics occurred in Shenzhen than in Hong Kong. Conclusions: Influenza epidemics appeared to be unsynchronized between Hong Kong and Shenzhen most of the time. Given the close geographical locations of these two cities, this could be due to the strikingly different age structures of their populations. Keywords: Influenza epidemics, Synchrony, Shenzhen, Hong Kong

Networked SIS Epidemics With Awareness

KAUST Repository

Paarporn, Keith

2017-07-20

We study a susceptible-infected-susceptible 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 (MFAs) are derived. The states of the MFA are interpreted as the nodes\\' probabilities of being infected. We show a sufficient condition for the existence of a

Epidemic dynamics and endemic states in complex networks

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Pastor-Satorras, Romualdo; Vespignani, Alessandro

2001-06-01

We study by analytical methods and large scale simulations a dynamical model for the spreading of epidemics in complex networks. In networks with exponentially bounded connectivity we recover the usual epidemic behavior with a threshold defining a critical point below that the infection prevalence is null. On the contrary, on a wide range of scale-free networks we observe the absence of an epidemic threshold and its associated critical behavior. This implies that scale-free networks are prone to the spreading and the persistence of infections whatever spreading rate the epidemic agents might possess. These results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks.

Epidemic dynamics and endemic states in complex networks

International Nuclear Information System (INIS)

Pastor-Satorras, Romualdo; Vespignani, Alessandro

2001-01-01

We study by analytical methods and large scale simulations a dynamical model for the spreading of epidemics in complex networks. In networks with exponentially bounded connectivity we recover the usual epidemic behavior with a threshold defining a critical point below that the infection prevalence is null. On the contrary, on a wide range of scale-free networks we observe the absence of an epidemic threshold and its associated critical behavior. This implies that scale-free networks are prone to the spreading and the persistence of infections whatever spreading rate the epidemic agents might possess. These results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks

Jakub Penson and his studies on acute renal failure during typhus epidemics in Warsaw Ghetto.

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Rutkowski, Boleslaw

2004-01-01

In the Warsaw Ghetto established by the German Nazis as a special district for Polish Jews in 1940 there were two typhus epidemics. Many patients affected by this disease (1500 during the first and 6500 during second epidemic) were treated at The Department of Infectious Disease of Czyste Hospital headed by Dr Jakub Penson--a Polish physician of Jewish origin. A heroic group of 20 physicians not only treated patients in these tragic circumstances, but also performed in defiance of Nazi prohibition, scientific studies on the clinical course of typhus with special attention on hyperazotemia and renal complication. The results of their observations were presented in 1941-42 during clinical meetings in Czyste Hospital and later published by Penson in 1946 in the Polish Physicians Weekly. Among other clinical statements a description of acute renal failure of extrarenal origin, caused by dehydration and toxic influence of primary disease seems the most important one. It has to be taken into account that acute renal failure appearing during Crush Syndrome was described by Bywaters in 1941. Jakub Penson survived the German Nazi occupation and later become a head of the Internal Medicine Department in Gdansk Medical University and one of the precursors of clinical nephrology in Poland.

Phylodynamic analysis of HIV sub-epidemics in Mochudi, Botswana

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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.

Time evolution of predictability of epidemics on networks

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Holme, Petter; Takaguchi, Taro

2015-04-01

Epidemic outbreaks of new pathogens, or known pathogens in new populations, cause a great deal of fear because they are hard to predict. For theoretical models of disease spreading, on the other hand, quantities characterizing the outbreak converge to deterministic functions of time. Our goal in this paper is to shed some light on this apparent discrepancy. We measure the diversity of (and, thus, the predictability of) outbreak sizes and extinction times as functions of time given different scenarios of the amount of information available. Under the assumption of perfect information—i.e., knowing the state of each individual with respect to the disease—the predictability decreases exponentially, or faster, with time. The decay is slowest for intermediate values of the per-contact transmission probability. With a weaker assumption on the information available, assuming that we know only the fraction of currently infectious, recovered, or susceptible individuals, the predictability also decreases exponentially most of the time. There are, however, some peculiar regions in this scenario where the predictability decreases. In other words, to predict its final size with a given accuracy, we would need increasingly more information about the outbreak.

Feeding difficulties in children with food protein-induced gastrointestinal allergies.

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Meyer, Rosan; Rommel, Nathalie; Van Oudenhove, Lukas; Fleming, Catharine; Dziubak, Robert; Shah, Neil

2014-10-01

There is paucity of data on the prevalence of feeding difficulties in Food Protein-Induced Gastrointestinal Allergies (FPIGA) and their clinical characteristics. However, it is a commonly reported problem by clinicians. We set out to establish the occurrence of feeding difficulties in children with FPIGA, the association with gastrointestinal and extra-intestinal symptoms and number of foods eliminated from the diet. This retrospective observational analysis was performed in patients seen between 2002 and 2009 at Great Ormond Street Children's Hospital, Gastroenterology Department, London. Medical records where FPIGA was documented using the terms from the National Institute of Allergy and Infectious Disease and National Institute of Clinical Excellence and confirmed using an elimination diet, followed by a challenge were included. Feeding difficulties were assessed using a criteria previously used in healthy toddlers in the UK. Data from 437 children (203 female) were collected. Significantly more children with feeding difficulties presented with abdominal distention and bloating (P = 0.002), vomiting (P foods eliminated from the diet in the children with/without feeding difficulties (P = 0.028). Clinical manifestations like vomiting, constipation, rectal bleeding, weight loss, and the presence of extra-intestinal manifestations in addition to the number of foods avoided are in our FPIGA population linked to feeding difficulties. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

Modeling the Effects of Duration and Size of the Control Zones on the Consequences of a Hypothetical African Swine Fever Epidemic in Denmark

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Halasa, Tariq; Bøtner, Anette; Mortensen, Sten; Christensen, Hanne; Wulff, Sisse Birk; Boklund, Anette

2018-01-01

African swine fever (ASF) is a notifiable infectious disease. The disease is endemic in certain regions in Eastern Europe constituting a risk of ASF spread toward Western Europe. Therefore, as part of contingency planning, it is important to continuously explore strategies that can effectively control an epidemic of ASF. A previously published and well documented simulation model for ASF virus spread between herds was used to examine the epidemiologic and economic impacts of the duration and size of the control zones around affected herds. In the current study, scenarios were run, where the duration of the protection and surveillance zones were reduced from 50 and 45 days to 35 and 25 days or to 35 and 25 days, respectively. These scenarios were run with or without enlargement of the surveillance zone around detected herds from 10 to 15 km. The scenarios were also run with only clinical or clinical and serological surveillance of herds within the zones. Sensitivity analysis was conducted on influential input parameters in the model. The model predicts that reducing the duration of the protection and surveillance zones has no impact on the epidemiological consequences of the epidemics, while it may result in a substantial reduction in the total economic losses. In addition, the model predicts that increasing the size of the surveillance zone from 10 to 15 km may reduce both the epidemic duration and the total economic losses, in case of large epidemics. The ranking of the control strategies by the total costs of the epidemics was not influenced by changes of input parameters in the sensitivity analyses. PMID:29616228

[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

Antioxidant supplements for preventing gastrointestinal cancers

DEFF Research Database (Denmark)

Bjelakovic, G; Nikolova, D; Simonetti, R G

2004-01-01

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.......Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory....

The Characteristics of TB Epidemic and TB/HIV Co-Infection Epidemic: A 2007-2013 Retrospective Study in Urumqi, Xinjiang Province, China.

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Wang Wei

Full Text Available This study was aimed to find out epidemiologic characteristic of tuberculosis (TB cases, and Human Immunodeficiency Virus (HIV positive cases among TB patients (TB/HIV co-infection through demographic, temporal, and spatial study in Urumqi.Descriptive statistics and multivariate logistic regression were applied to identify the epidemiologic characteristics and risk factors of TB epidemic and TB/HIV co-infection epidemic. All addresses of each TB case, TB/HIV co-infection case, and administrative street were transformed into geographical coordinate. Subsequently, the geocoded address for 82 streets was transformed into a dot map used as the basis of spatial datasets. In addition, the paper also used quantile map and the spatial scan statistic in order to identify the spatial distribution and spatial clusters of TB epidemic and TB/HIV co-infection epidemic.There was a declining trend of the notification rates of TB epidemic from 2007 to 2009, as well as a rising trend from 2010 to 2013. However, the notification rates of TB/HIV co-infection epidemic showed a rising trend from 2007 to 2010, and a declining trend from 2011 to 2013. Moreover, a significant share of TB epidemic and TB/HIV co-infection epidemic happened between the age of 15 to 45 years old, indicating an increase in risk of TB and TB/HIV infection. It is worth noting that the risk of HIV infection for male TB patients was 2.947 times (95% CI [2.178, 3.988] than that of female patients. Han ethnicity and Uygur ethnicity in urban region accounted for a large proportion of total TB and TB/HIV co-infection cases. Most of the TB cases of minorities in Urumqi showed a statistically significant increase in risk of HIV infection than Han ethnicity in Urumqi. In addition, the spatial distribution of TB epidemic and TB/HIV co-infection epidemic was highly skewed. Most of the local clusters were located in urban area and rural-urban continuum where showed an increase in risk of TB and TB

Understanding Ebola: the 2014 epidemic.

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Kaner, Jolie; Schaack, Sarah

2016-09-13

Near the end of 2013, an outbreak of Zaire ebolavirus (EBOV) began in Guinea, subsequently spreading to neighboring Liberia and Sierra Leone. As this epidemic grew, important public health questions emerged about how and why this outbreak was so different from previous episodes. This review provides a synthetic synopsis of the 2014-15 outbreak, with the aim of understanding its unprecedented spread. We present a summary of the history of previous epidemics, describe the structure and genetics of the ebolavirus, and review our current understanding of viral vectors and the latest treatment practices. We conclude with an analysis of the public health challenges epidemic responders faced and some of the lessons that could be applied to future outbreaks of Ebola or other viruses.

Scintigraphic evaluation of gastrointestinal motility disorders

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Choe, Jae Gol [College of Medicine, Korea Univ., Seoul (Korea, Republic of)

2001-02-01

Current scintigraphic tests of gastrointestinal motor function provides relevant pathophysiologic information, but their clinical utility is controversial. Many scintigraphic methods are developed to investigate gastrointestinal motility from oral cavity to colon. These are esophageal transit scintigraphy, oropharyngeal transit study, gastric emptying test, small bowel transit time measurement, colon transit study and gastroesopahgeal reflux scintigraphy. Scintigraphy of gastrointestinal tract is the most physiologic and noninvasive method to evaluate gastrointestinal motility disorders. Stomach emptying test is regarded as a gold standard in motility study. Gastrointestinal transit scintigraphy also has a certain role in assessment of drug effect to GI motility and changes after theraphy of motility disorders. Scintigraphy provides noninvasive and quantitative assessment of physiological transit throughout the gastrointestinal tract, and it is extremely useful for diagnosing gastrointestinal motor dysfunction. This article reviews the current procedures, indications, significance and guidelines for gastrointestinal motility measurements by scintigraphy.

Scintigraphic evaluation of gastrointestinal motility disorders

International Nuclear Information System (INIS)

Choe, Jae Gol

2001-01-01

Current scintigraphic tests of gastrointestinal motor function provides relevant pathophysiologic information, but their clinical utility is controversial. Many scintigraphic methods are developed to investigate gastrointestinal motility from oral cavity to colon. These are esophageal transit scintigraphy, oropharyngeal transit study, gastric emptying test, small bowel transit time measurement, colon transit study and gastroesopahgeal reflux scintigraphy. Scintigraphy of gastrointestinal tract is the most physiologic and noninvasive method to evaluate gastrointestinal motility disorders. Stomach emptying test is regarded as a gold standard in motility study. Gastrointestinal transit scintigraphy also has a certain role in assessment of drug effect to GI motility and changes after theraphy of motility disorders. Scintigraphy provides noninvasive and quantitative assessment of physiological transit throughout the gastrointestinal tract, and it is extremely useful for diagnosing gastrointestinal motor dysfunction. This article reviews the current procedures, indications, significance and guidelines for gastrointestinal motility measurements by scintigraphy

[Massive hemorrhage of upper gastrointestinal tract caused by gastrointestinal stromal tumor of the stomach--case report].

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Lalović, Nenad; Dukić Vladicić, Nikolina; Marić, Radmil; Cuk, Mirjana; Simatović, Milan; Jokanović, Dragana

2012-01-01

Acute bleeding from the upper gastrointestinal system is a medical emergency which is followed by high mortality rate, ranging from 6 to 15% in spite of modern diagnostic methods and treatment. Bleeding from the upper gastrointestinal system may be caused by gastrointestinal stromal tumors of the stomach, which are mainly characterized by occult bleeding, while profuse bleeding rarely occurs accompanied by hemorrhagic shock. Gastrointestinal stromal tumors of stomach are the most common mesenchimal tumors of the gastrointestinal tract. In our study we showed a 60-year-old female patient with profuse bleeding from the stomach and the clinical picture of severe hemorrhagic shock, caused by gastrointestinal stromal tumor. An ovoid junction, raised towards the lumen, covered with ulcerated mucosa in several places and followed by massive arterial bleeding was found intraoperatively, after the performed gastrotomy. Histopathological examination with immunohistochemical analysis confirmed that this was a gastrointestinal stromal tumor of the stomach. Acute bleeding from the digestive system is a sudden and serious condition of the body. Urgent esophagogastroduodenoscopy is a sensitive and specific diagnostic and therapeutic method of choice. Massive bleeding from the upper gastrointestinal tract is very rarely caused by gastrointestinal stromal tumors, whose clinical picture is very heterogeneous and depends on tumor size and location. Abundant bleeding from the tumor is an indication for urgent surgical intervention. According to the literature massive hemorrhage of the upper digestive system can rarely be caused by gastrointestinal stromal tumor of the stomach. It is shown that abundant hemorrhage of the upper digestive tract can be caused with gastric gastrointestinal stromal tumor. Surgical resection is the main form of treatment of gastrointestinal stromal tumors of the digestive system and bleeding from these tumors caused by failure of endoscopic hemostasis.

Inferring epidemic contact structure from phylogenetic trees.

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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.

Malaria epidemic and drug resistance, Djibouti.

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

2005-02-01

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.

Population medicine and control of epidemics.

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Benchaoui, Hafid

2010-01-01

Population medicine is an important component of veterinary care in livestock (farm animals) and companion animals (pets). This chapter covers some of the chemotherapeutic approaches undertaken at population level to control infectious diseases in domestic animals. Optimisation of health, productivity and welfare in livestock commonly entails implementation of whole-herd or whole-flock strategies to effectively counter the negative impact of infectious diseases. Gastro-intestinal and liver parasites of grazing cattle and sheep are endemic in most parts of the world and can result in significant production losses. Strategically timed anthelmintic treatments are instituted with the double objective of reducing worm burdens in infected animals and ensuring reduction of pasture contamination with infective larvae. Mastitis is another major endemic problem, particularly in cattle, which causes significant economic losses to dairy farmers globally. As a painful inflammatory condition of the cow's udder, clinical mastitis also raises animal welfare concerns. Prevention of clinical mastitis requires rigorous post-milking hygiene, identification and culling of chronically infected cows, attention to the cow's environment and therapeutic management of udder health during the dry period. A third condition that can cause high levels of morbidity and mortality is bacterial respiratory disease. Pneumonia in young livestock is often exacerbated by stressful transportation and co-mingling of animals from different herds. The welfare consequences and production losses can be significant. Antimicrobial treatment of pneumonic animals and, when appropriate, of in-contact animals living in the same air-space is an integral part of whole-herd respiratory disease management. The role of the veterinary profession is to also ensure that principles of population medicine are understood and adhered to by pet owners. The increase in pet ownership and the importance of the human-animal bond in

Modelling control of epidemics spreading by long-range interactions.

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Dybiec, Bartłomiej; Kleczkowski, Adam; Gilligan, Christopher A

2009-10-06

We have studied the spread of epidemics characterized by a mixture of local and non-local interactions. The infection spreads on a two-dimensional lattice with the fixed nearest neighbour connections. In addition, long-range dynamical links are formed by moving agents (vectors). Vectors perform random walks, with step length distributed according to a thick-tail distribution. Two distributions are considered in this paper, an alpha-stable distribution describing self-similar vector movement, yet characterized by an infinite variance and an exponential power characterized by a large but finite variance. Such long-range interactions are hard to track and make control of epidemics very difficult. We also allowed for cryptic infection, whereby an infected individual on the lattice can be infectious prior to showing any symptoms of infection or disease. To account for such cryptic spread, we considered a control strategy in which not only detected, i.e. symptomatic, individuals but also all individuals within a certain control neighbourhood are treated upon the detection of disease. We show that it is possible to eradicate the disease by using such purely local control measures, even in the presence of long-range jumps. In particular, we show that the success of local control and the choice of the optimal strategy depend in a non-trivial way on the dispersal patterns of the vectors. By characterizing these patterns using the stability index of the alpha-stable distribution to change the power-law behaviour or the exponent characterizing the decay of an exponential power distribution, we show that infection can be successfully contained using relatively small control neighbourhoods for two limiting cases for long-distance dispersal and for vectors that are much more limited in their dispersal range.

Testing the hypothesis that treatment can eliminate HIV: a nationwide, population-based study of the Danish HIV epidemic in men who have sex with men.

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Okano, Justin T; Robbins, Danielle; Palk, Laurence; Gerstoft, Jan; Obel, Niels; Blower, Sally

2016-07-01

Worldwide, approximately 35 million individuals are infected with HIV; about 25 million of these live in sub-Saharan Africa. WHO proposes using treatment as prevention (TasP) to eliminate HIV. Treatment suppresses viral load, decreasing the probability an individual transmits HIV. The elimination threshold is one new HIV infection per 1000 individuals. Here, we test the hypothesis that TasP can substantially reduce epidemics and eliminate HIV. We estimate the impact of TasP, between 1996 and 2013, on the Danish HIV epidemic in men who have sex with men (MSM), an epidemic UNAIDS has identified as a priority for elimination. We use a CD4-staged Bayesian back-calculation approach to estimate incidence, and the hidden epidemic (the number of HIV-infected undiagnosed MSM). To develop the back-calculation model, we use data from an ongoing nationwide population-based study: the Danish HIV Cohort Study. Incidence, and the hidden epidemic, decreased substantially after treatment was introduced in 1996. By 2013, incidence was close to the elimination threshold: 1·4 (median, 95% Bayesian credible interval [BCI] 0·4-2·1) new HIV infections per 1000 MSM and there were only 617 (264-858) undiagnosed MSM. Decreasing incidence and increasing treatment coverage were highly correlated; a treatment threshold effect was apparent. Our study is the first to show that TasP can substantially reduce a country's HIV epidemic, and bring it close to elimination. However, we have shown the effectiveness of TasP under optimal conditions: very high treatment coverage, and exceptionally high (98%) viral suppression rate. Unless these extremely challenging conditions can be met in sub-Saharan Africa, the WHO's global elimination strategy is unlikely to succeed. National Institute of Allergy and Infectious Diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gastrointestinal Headache; a Narrative Review

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Majid T Noghani

2016-08-01

Full Text Available There are studies reporting primary headaches to be associated with gastrointestinal disorders, and some report resolution of headache following the treatment of the associated gastrointestinal disorder. Headache disorders are classified by The International Headache Society as primary or secondary; however, among the secondary headaches, those attributed to gastrointestinal disorders are not appreciated. Therefore, we aimed to review the literature to provide evidence for headaches, which originate from the gastrointestinal system. Gastrointestinal disorders that are reported to be associated with primary headaches include dyspepsia, gastro esophageal reflux disease (GERD, constipation, functional abdominal pain, inflammatory bowel syndrome (IBS, inflammatory bowel disorders (IBD, celiac disease, and helicobacter pylori (H. Pylori infection. Some studies have demonstrated remission or improvement of headache following the treatment of the accompanying gastrointestinal disorders. Hypotheses explaining this association are considered to be central sensitization and parasympathetic referred pain, serotonin pathways, autonomic nervous system dysfunction, systemic vasculopathy, and food allergy. Traditional Persian physicians, namely Ebn-e-Sina (Avicenna and Râzi (Rhazes believed in a type of headache originating from disorders of the stomach and named it as an individual entity, the "Participatory Headache of Gastric Origin". We suggest providing a unique diagnostic entity for headaches coexisting with any gastrointestinal abnormality that are improved or cured along with the treatment of the gastrointestinal disorder.

Determinants and Drivers of Infectious Disease Threat Events in Europe.

Science.gov (United States)

Semenza, Jan C; Lindgren, Elisabet; Balkanyi, Laszlo; Espinosa, Laura; Almqvist, My S; Penttinen, Pasi; Rocklöv, Joacim

2016-04-01

Infectious disease threat events (IDTEs) are increasing in frequency worldwide. We analyzed underlying drivers of 116 IDTEs detected in Europe during 2008-2013 by epidemic intelligence at the European Centre of Disease Prevention and Control. Seventeen drivers were identified and categorized into 3 groups: globalization and environment, sociodemographic, and public health systems. A combination of >2 drivers was responsible for most IDTEs. The driver category globalization and environment contributed to 61% of individual IDTEs, and the top 5 individual drivers of all IDTEs were travel and tourism, food and water quality, natural environment, global trade, and climate. Hierarchical cluster analysis of all drivers identified travel and tourism as a distinctly separate driver. Monitoring and modeling such disease drivers can help anticipate future IDTEs and strengthen control measures. More important, intervening directly on these underlying drivers can diminish the likelihood of the occurrence of an IDTE and reduce the associated human and economic costs.

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

Survivability of porcine epidemic diarrhea virus (PEDV) in bovine plasma submitted to spray drying processing and held at different time by temperature storage conditions.

Science.gov (United States)

Pujols, Joan; Segalés, Joaquim

2014-12-05

Bovine plasma was inoculated with porcine epidemic diarrhea virus (PEDV) at an average final titer of 4.2 log10 TCID50/mL to determine the effect of spray drying on viral inactivation. Using a laboratory scale drier, inoculated plasma was spray dried at 200 °C inlet temperature and either 70 or 80 °C throughout substance. Both liquid and dried samples were subjected to three passages on VERO cell monolayers to determine PEDV infectivity. Results indicated liquid samples contained infective virus, but none of the spray dried samples were infectious. Also, survivability of PEDV inoculated on spray dried bovine plasma (SDBP) and stored at 4, 12 or 22 °C was determined for 7, 14 and 21 days. Commercial SDBP powder was inoculated with PEDV to an average final titer of 2.8 log10 TCID50/g. Five samples per time and temperature conditions were subjected to three passages on VERO cell monolayers to determine PEDV infectivity. The virus was non-infectious for all samples stored at 22 °C at 7, 14 and 21 days. PEDV was infective in 1 out of 5 samples stored at 12 °C at 7 days, but none of the samples stored for 14 and 21 days were infectious in cell culture. For samples stored at 4 °C, 4 out of 5 samples were infectious at 7 days, 1 out of 5 samples were infectious at 14 days, but none were infectious at 21 days. In summary, PEDV was not infectious on cell culture within 7 days when stored at room temperature and within 21 days when stored at refrigerated temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

Gastrointestinal Manifestations of Cystic Fibrosis

Science.gov (United States)

2016-01-01

Cystic fibrosis has historically been considered a pulmonary disease, but with the increasing life expectancy of these patients, gastrointestinal manifestations are becoming more important. Furthermore, nutritional status is closely linked to pulmonary function and, thus, overall mortality. This article discusses gastrointestinal manifestations (which involve nutritional, pancreatic, hepatobiliary, and, in particular, gastrointestinal tract issues) of cystic fibrosis as well as management of the disease. In addition, the article discusses studies that have been critical to our understanding of gastrointestinal manifestations of cystic fibrosis. PMID:27330503

Scintigraphic assessment of gastrointestinal motility

DEFF Research Database (Denmark)

Madsen, Jan Lysgård

2014-01-01

intestinal and colonic transit. This article reviews current imaging techniques, methods for data processing and principles for evaluating results when scintigraphy is used to assess gastrointestinal motility. Furthermore, clinical indications for performing scintigraphy are reviewed.......Gastrointestinal transit reflects overall gastrointestinal motor activity and is regulated by a complex interplay between neural and hormonal stimuli. Thus, transit measurements provide a measure of the combined effects of gastrointestinal muscular activity and feedback from the gut and brain....... Dysmotility in the different major segments of the gastrointestinal tract may give rise to similar symptoms; hence, localizing transit abnormalities to a specific segment is a valuable element of diagnostic evaluation. Scintigraphy is an effective noninvasive tool to assess gastric emptying as well as small...

Obesity and the gastrointestinal tract: you are what you eat.

Science.gov (United States)

Wolfe, M Michael; Boylan, Michael O

2014-01-01

Obesity represents a complex multifactorial syndrome that develops from interactions among genetic and environmental factors and is a leading cause of illness and death. The prevalence of obesity in the United States has increased dramatically since 1975. Although often ignored, the gastrointestinal tract, and the gastrointestinal regulatory peptides in particular, constitutes an ideal starting point for defining and investigating obesity as it represents the route by which all nutrients are ingested, processed, and absorbed. Another important factor to consider when evaluating the etiology of obesity is the capacity for all animals to store nutrients. Insulin is the most potent anabolic hormone, and it appears to have evolved from the need to maximize energy efficiency, obviating the requirement to continuously forage for food. Organisms expressing this important peptide possessed a distinct survival advantage and flourished. During the course of evolution, insulin biosynthesis translocated from the intestine to pancreatic islets, which necessitated a messenger from the intestine to complete the "enteroinsular axis." The eventual development of glucose-dependent insulinotropic polypeptide (GIP) and other incretins fulfilled this requirement. GIP appears to offer an additional survival benefit by not only stimulating intestinal glucose transport and maximally releasing insulin to facilitate nutrient storage but also by its insulin-mimetic properties, including enhanced uptake of glucose by adipocytes. This physiological redundancy offered by insulin and GIP ensured the survival of organisms during times when food was scarce. As food is no longer scarce, at least in the West, this survival advantage appears to have contributed to the current obesity epidemic.

Deciphering Dynamics of Recent Epidemic Spread and Outbreak in West Africa: The Case of Ebola Virus

Science.gov (United States)

Upadhyay, Ranjit Kumar; Roy, Parimita

Recently, the 2014 Ebola virus (EBOV) outbreak in West Africa was the largest outbreak to date. In this paper, an attempt has been made for modeling the virus dynamics using an SEIR model to better understand and characterize the transmission trajectories of the Ebola outbreak. We compare the simulated results with the most recent reported data of Ebola infected cases in the three most affected countries Guinea, Liberia and Sierra Leone. The epidemic model exhibits two equilibria, namely, the disease-free and unique endemic equilibria. Existence and local stability of these equilibria are explored. Using central manifold theory, it is established that the transcritical bifurcation occurs when basic reproduction number passes through unity. The proposed Ebola epidemic model provides an estimate to the potential number of future cases. The model indicates that the disease will decline after peaking if multisectorial and multinational efforts to control the spread of infection are maintained. Possible implication of the results for disease eradication and its control are discussed which suggests that proper control strategies like: (i) transmission precautions, (ii) isolation and care of infectious Ebola patients, (iii) safe burial, (iv) contact tracing with follow-up and quarantine, and (v) early diagnosis are needed to stop the recurrent outbreak.

Disease spreading with epidemic alert on small-world networks

International Nuclear Information System (INIS)

Han, Xiao-Pu

2007-01-01

Base on two-dimension small-world networks, a susceptible-infected model with epidemic alert is proposed in this Letter. In this model, if some parts of the network are alarmed as dangerous, a fraction of edges between the alarmed parts and others will be removed, and two cases of alerting rules that the degree and frequency of contacts kept unchanged are considered respectively. The numerical simulations show that the spreading velocity is reduced by the accurate and timely epidemic alert, and the more accurate and timely, the stronger the deceleration effect. This model indicates that to broadcast epidemic alert timely is helpful and necessary in the control of epidemic spreading, and in agreement with the general view of epidemic alert. This work is helpful to understand the effects of epidemic alert on disease spreading

About Infectious Mononucleosis

Science.gov (United States)

... Infectious mononucleosis, also called “mono,” is a contagious disease. Epstein-Barr virus (EBV) is the most common cause of infectious mononucleosis, but other viruses can also cause this disease. It is common among teenagers and young adults, ...

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

Scintigraphic and Endoscopic Evaluation of Radiation-induced Acute Gastrointestinal Syndrome in Micro-pig Model

International Nuclear Information System (INIS)

Lee, Seung-Sook; Kim, Kyung-Min; Kim, Jin; Jang, Won-Suk; Lee, Jung-Eun; Kim, Noo-Ri; Lee, Sun-Joo; Kim, Mi-Sook; Ji, Young-Hoon; Cheon, Gi-Jeong; Lim, Sang-Moo

2007-01-01

Micro-pig model can be served as a proper substitute for humans in studying acute radiation syndrome following radiation-exposure accidents, especially showing similar clinico-pathologic response of hematopoietic and gastrointestinal (GI) syndrome to human. Among acute GI syndrome induced by radiation, GI motility disturbance has not been studied, however, it would be important in a viewpoint of affecting infectious progression from GI tract. Here, we employed scintigraphy of GI transit time and sequential endoscopic examination and tissue sampling in micropigs followed by abdominal radiation exposure. The specific aims of this study are to evaluate objective evidence of GI motility disturbance by scintigraphic evaluation and to find corresponding clinicoapthologic changes in radiation-induced acute GI syndrome

Waterborne Campylobacter jejuni epidemic in a Finnish hospital for rheumatic diseases.

Science.gov (United States)

Rautelin, H; Koota, K; von Essen, R; Jahkola, M; Siitonen, A; Kosunen, T U

1990-01-01

A waterborne Campylobacter jejuni outbreak in the Rheumatism Foundation Hospital in Heinola, Finland, in November-December 1986 is described. 32 patients and 62 members of the staff developed gastrointestinal symptoms. C. jejuni heat-stable serotype 45 was isolated from the faeces of 32 enteritis patients and from none of the controls. No other enteropathogens were found. Positive serological responses to C. jejuni acid extract antigen were detected by enzyme immunoassay in 34% of the symptomatic hospital patients, in 40% of the symptomatic staff members, and in 10% of the controls. The clinical course of the illness was mostly mild and self-limited. No striking progress in the arthritis symptoms of the patients was found after the outbreak. The hospital has its own water supply. C. jejuni of the same serotype as the epidemic strain was isolated from the water of the pipeline system. After a careful examination some aged components of the waterworks were found to be responsible for leaks that resulted in the contamination of the water.

FRED (a Framework for Reconstructing Epidemic Dynamics): an open-source software system for modeling infectious diseases and control strategies using census-based populations.

Science.gov (United States)

Grefenstette, John J; Brown, Shawn T; Rosenfeld, Roni; DePasse, Jay; Stone, Nathan T B; Cooley, Phillip C; Wheaton, William D; Fyshe, Alona; Galloway, David D; Sriram, Anuroop; Guclu, Hasan; Abraham, Thomas; Burke, Donald S

2013-10-08

Mathematical and computational models provide valuable tools that help public health planners to evaluate competing health interventions, especially for novel circumstances that cannot be examined through observational or controlled studies, such as pandemic influenza. The spread of diseases like influenza depends on the mixing patterns within the population, and these mixing patterns depend in part on local factors including the spatial distribution and age structure of the population, the distribution of size and composition of households, employment status and commuting patterns of adults, and the size and age structure of schools. Finally, public health planners must take into account the health behavior patterns of the population, patterns that often vary according to socioeconomic factors such as race, household income, and education levels. FRED (a Framework for Reconstructing Epidemic Dynamics) is a freely available open-source agent-based modeling system based closely on models used in previously published studies of pandemic influenza. This version of FRED uses open-access census-based synthetic populations that capture the demographic and geographic heterogeneities of the population, including realistic household, school, and workplace social networks. FRED epidemic models are currently available for every state and county in the United States, and for selected international locations. State and county public health planners can use FRED to explore the effects of possible influenza epidemics in specific geographic regions of interest and to help evaluate the effect of interventions such as vaccination programs and school closure policies. FRED is available under a free open source license in order to contribute to the development of better modeling tools and to encourage open discussion of modeling tools being used to evaluate public health policies. We also welcome participation by other researchers in the further development of FRED.

Immunoglobulins for preventing hepatitis A

DEFF Research Database (Denmark)

Liu, Jian Ping; Nikolova, Dimitrinka; Fei, Yutong

2009-01-01

Hepatitis A (infectious hepatitis) is a common epidemic disease. Immunoglobulins for passive immunisation are used as prevention.......Hepatitis A (infectious hepatitis) is a common epidemic disease. Immunoglobulins for passive immunisation are used as prevention....

Epidemic spreading in a hierarchical social network.

Science.gov (United States)

Grabowski, A; Kosiński, R A

2004-09-01

A model of epidemic spreading in a population with a hierarchical structure of interpersonal interactions is described and investigated numerically. The structure of interpersonal connections is based on a scale-free network. Spatial localization of individuals belonging to different social groups, and the mobility of a contemporary community, as well as the effectiveness of different interpersonal interactions, are taken into account. Typical relations characterizing the spreading process, like a range of epidemic and epidemic curves, are discussed. The influence of preventive vaccinations on the spreading process is investigated. The critical value of preventively vaccinated individuals that is sufficient for the suppression of an epidemic is calculated. Our results are compared with solutions of the master equation for the spreading process and good agreement of the character of this process is found.

Characterization of cis-Acting RNA Elements of Zika Virus by Using a Self-Splicing Ribozyme-Dependent Infectious Clone.

Science.gov (United States)

Liu, Zhong-Yu; Yu, Jiu-Yang; Huang, Xing-Yao; Fan, Hang; Li, Xiao-Feng; Deng, Yong-Qiang; Ji, Xue; Cheng, Meng-Li; Ye, Qing; Zhao, Hui; Han, Jian-Feng; An, Xiao-Ping; Jiang, Tao; Zhang, Bo; Tong, Yi-Gang; Qin, Cheng-Feng

2017-11-01

Zika virus (ZIKV) has caused significant outbreaks and epidemics in the Americas recently, raising global concern due to its ability to cause microcephaly and other neurological complications. A stable and efficient infectious clone of ZIKV is urgently needed. However, the instability and toxicity of flavivirus cDNA clones in Escherichia coli hosts has hindered the development of ZIKV infectious clones. Here, using a novel self-splicing ribozyme-based strategy, we generated a stable infectious cDNA clone of a contemporary ZIKV strain imported from Venezuela to China in 2016. The constructed clone contained a modified version of the group II self-splicing intron P.li.LSUI2 near the junction between the E and NS1 genes, which were removed from the RNA transcripts by an easy-to-establish in vitro splicing reaction. Transfection of the spliced RNAs into BHK-21 cells led to the production of infectious progeny virus that resembled the parental virus. Finally, potential cis -acting RNA elements in ZIKV genomic RNA were identified based on this novel reverse genetics system, and the critical role of 5'-SLA promoter and 5'-3' cyclization sequences were characterized by a combination of different assays. Our results provide another stable and reliable reverse genetics system for ZIKV that will help study ZIKV infection and pathogenesis, and the novel self-splicing intron-based strategy could be further expanded for the construction of infectious clones from other emerging and reemerging flaviviruses. IMPORTANCE The ongoing Zika virus (ZIKV) outbreaks have drawn global concern due to the unexpected causal link to fetus microcephaly and other severe neurological complications. The infectious cDNA clones of ZIKV are critical for the research community to study the virus, understand the disease, and inform vaccine design and antiviral screening. A panel of existing technologies have been utilized to develop ZIKV infectious clones. Here, we successfully generated a stable

[Infestation status Aedes albopictus and related mosquito-borne infectious disease risk in central urban area in Shanghai].

Science.gov (United States)

Gao, Q; Xiong, C L; Zhou, Y B; Cao, H; Jiang, Q W

2016-05-01

To evaluate Aedes albopictus infestation status in the central urban area of Shanghai, and analyze the related epidemic risk of mosquito-borne infectious disease. Consecutive mosquito surveillance was conducted in the green lands and residential areas in the central urban area of Shanghai during 2012-2014, the Aedes albopictus density and its seasonal fluctuation were observed; the sequence of Aedes albopictus in Shanghai was aligned with that in other epidemic area abroad, and the susceptibility of Aedes albopictus to mosquito-borne virus and endemic risk were analyzed. No Aedes aegypti was found in the central urban area of Shanghai. As predominant species in both the residential area and the green lands, the proportion of Aedes albopictus in the residential area was significantly higher than that in the green lands(78.53% vs. 19.99%, χ(2) =15 525.168, PAedes albopictus in Shanghai and Aedes albopictus in Africa was quite far. No Aedes aegypti was found in Shanghai and its surrounding areas, while Aedes albopictus infestation in the central urban area of Shanghai was serious. Strict measures should be taken to reduce the Aedes albopictus density for the effective control Zika virus spread.

UK investments in global infectious disease research 1997-2010: a case study.

Science.gov (United States)

Head, Michael G; Fitchett, Joseph R; Cooke, Mary K; Wurie, Fatima B; Hayward, Andrew C; Atun, Rifat

2013-01-01

Infectious diseases account for 15 million deaths per year worldwide, and disproportionately affect young people, elderly people, and the poorest sections of society. We aimed to describe the investments awarded to UK institutions for infectious disease research. We systematically searched databases and websites for information on research studies from funding institutions and created a comprehensive database of infectious disease research projects for the period 1997-2010. We categorised studies and funding by disease, cross-cutting theme, and by a research and development value chain describing the type of science. Regression analyses were reported with Spearman's rank correlation coefficient to establish the relation between research investment, mortality, and disease burden as measured by disability-adjusted life years (DALYs). We identified 6170 funded studies, with a total research investment of UK£2·6 billion. Studies with a clear global health component represented 35·6% of all funding (£927 million). By disease, HIV received £461 million (17·7%), malaria £346 million (13·3%), tuberculosis £149 million (5·7%), influenza £80 million (3·1%), and hepatitis C £60 million (2·3%). We compared funding with disease burden (DALYs and mortality) to show low levels of investment relative to burden for gastrointestinal infections (£254 million, 9·7%), some neglected tropical diseases (£184 million, 7·1%), and antimicrobial resistance (£96 million, 3·7%). Virology was the highest funded category (£1 billion, 38·4%). Leading funding sources were the Wellcome Trust (£688 million, 26·4%) and the Medical Research Council (£673 million, 25·8%). Research funding has to be aligned with prevailing and projected global infectious disease burden. Funding agencies and industry need to openly document their research investments to redress any inequities in resource allocation. None. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gastrointestinal Stromal Tumors: A Case Report

OpenAIRE

Sashidharan, Palankezhe; Matele, Apoorva; Matele, Usha; Al Felahi, Nowfel; Kassem, Khalid F.

2014-01-01

Advances in the identification of gastrointestinal stromal tumors, its molecular and immunohiostochemical basis, and its management have been a watershed in the treatment of gastrointestinal tumors. This paradigm shift occurred over the last two decades and gastrointestinal stromal tumors have now come to be understood as rare gastrointestinal tract tumors with predictable behavior and outcome, replacing the older terminologies like leiomyoma, schwannoma or leiomyosarcoma. This report present...

An epidemic process mediated by a decaying diffusing signal

International Nuclear Information System (INIS)

Faria, Fernando P; Dickman, Ronald

2012-01-01

We study a stochastic epidemic model consisting of elements (organisms in a community or cells in tissue) with fixed positions, in which damage or disease is transmitted by diffusing agents ('signals') emitted by infected individuals. The signals decay as well as diffuse; since they are assumed to be produced in large numbers, the signal concentration is treated deterministically. The model, which includes four cellular states (susceptible, transformed, depleted, and removed), admits various interpretations: spread of an infection or infectious disease, or of damage in a tissue in which injured cells may themselves provoke further damage, and as a description of the so-called radiation-induced bystander effect, in which the signals are molecules capable of inducing cell damage and/or death in unirradiated cells. The model exhibits a continuous phase transition between spreading and nonspreading phases. We formulate two mean-field theory (MFT) descriptions of the model, one of which ignores correlations between the cellular state and the signal concentration, and another that treats such correlations in an approximate manner. Monte Carlo simulations of the spread of infection on the square lattice yield values for the critical exponents and the fractal dimension consistent with the dynamic percolation universality class

Macrolides: A Canadian Infectious Disease Society Position Paper

Directory of Open Access Journals (Sweden)

S McKenna

2001-01-01

Full Text Available Since the introduction of erythromycin in 1965, no new compounds from the macrolide antimicrobial class were licensed in Canada until the 1990s. Clarithromycin and azithromycin, since their introduction, have become important agents for treating a number of common and uncommon infectious diseases. They have become prime agents in the treatment of respiratory tract infections, and have revolutionized the management of both genital chlamydial infections, by the use of single-dose therapy with azithromycin, and nontuberculous mycobacterial infections, by the use of clarithromycin. The improvement of clarithromycin and azithromycin over the gastrointestinal intolerability of erythromycin has led to supplanting the use of the latter for many primary care physicians. Unfortunately, the use of these agents has also increased the likelihood for misuse and has raised concerns about a resultant increase in the rates of macrolide resistance in many important pathogens, such as Streptococcus pneumoniae. This paper reviews the pharmacology and evidence for the current indications for use of these newer agents, and provides recommendations for appropriate use.

Different Epidemic Models on Complex Networks

International Nuclear Information System (INIS)

Zhang Haifeng; Small, Michael; Fu Xinchu

2009-01-01

Models for diseases spreading are not just limited to SIS or SIR. For instance, for the spreading of AIDS/HIV, the susceptible individuals can be classified into different cases according to their immunity, and similarly, the infected individuals can be sorted into different classes according to their infectivity. Moreover, some diseases may develop through several stages. Many authors have shown that the individuals' relation can be viewed as a complex network. So in this paper, in order to better explain the dynamical behavior of epidemics, we consider different epidemic models on complex networks, and obtain the epidemic threshold for each case. Finally, we present numerical simulations for each case to verify our results.

HIV epidemics in Shenzhen and Chongqing, China.

Directory of Open Access Journals (Sweden)

Shu Yang

Full Text Available Men who have sex with men (MSM and heterosexuals are the populations with the fastest growing HIV infection rates in China. We characterize the epidemic growth and age patterns between these two routes from 2004 to 2015 in Chongqing and Shenzhen, China.Data were downloaded from the National HIV/ AIDS Comprehensive Response Information Management System. For the new HIV diagnoses of heterosexuals and MSM in both cities, we estimated the growth rates by fitting different sub-exponential models. Heat maps are used to show their age patterns. We used histograms to compare these patterns by birth cohort.The MSM epidemics grew significantly in both cities. Chongqing experienced quadratic growth in HIV reported cases with an estimated growth rate of 0.086 per week and a "deceleration rate" of 0.673. HIV reported cases of MSM in Shenzhen grew even more drastically with a growth rate of 0.033 per week and "deceleration rate" of 0.794. The new infections are mainly affecting the ages of 18 to 30 in Chongqing and ages of 20 to 35 in Shenzhen. They peaked in early 1990's and mid-1990's birth cohorts in Chongqing and Shenzhen respectively. The HIV epidemic among heterosexuals grew rapidly in both cities. The growth rates were estimated as 0.02 and 0.028 in Chongqing and Shenzhen respectively whereas the "deceleration rates" were 0.878 and 0.790 in these two places. It affected mostly aged 18 to 75 in males and 18 to 65 in females in Chongqing and aged 18 to 45 in males and 18 to 50 in females in Shenzhen in 2015. In Chongqing, the heterosexual female epidemics display two peaks in HIV diagnoses in the birth cohorts of early 1950's and early 1980's, with heterosexual male epidemics peaked in early 1940's and early 1960's. The heterosexual male and female epidemics display higher rates in the birth cohort 1940-1960, than the birth cohort 1960-1990. It peaked in birth cohorts of 1950's and 1980's in Shenzhen.We revealed striking differences in epidemic growth

Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks.

Science.gov (United States)

Onaga, Tomokatsu; Gleeson, James P; Masuda, Naoki

2017-09-08

Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks

Science.gov (United States)

Onaga, Tomokatsu; Gleeson, James P.; Masuda, Naoki

2017-09-01

Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

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

Treatment of infectious complications of acquired immunodeficiency syndrome.

Science.gov (United States)

Furio, M M; Wordell, C J

1985-01-01

The infectious complications of the acquired immunodeficiency syndrome (AIDS) are discussed, and the conventional and nonconventional therapies used for these infections are reviewed. The infections most commonly encountered in patients with AIDS are Pneumocystis carinii pneumonia (58%), Candida esophagitis (31%), toxoplasmosis (21%), cytomegalovirus infections (15%), and herpes-simplex virus infections (12%). Pneumocystis carinii pneumonia is the most common life-threatening process in these patients. Trimethoprim-sulfamethoxazole (TMP-SMZ) is considered the drug of choice for its treatment. Oral candidiasis often indicates the progression to AIDS in the high-risk populations of homosexual or bisexual men, intravenous drug abusers, and individuals with hemophilia. Nystatin suspension is commonly used to treat oral candidiasis, while Candida esophagitis demands systemic therapy with ketoconazole. Toxoplasmosis most commonly manifests itself in patients with AIDS as a cerebral mass lesion. The recommended therapy includes sulfadiazine and pyrimethamine. AIDS patients frequently experience protozoal invasion of the intestinal tract with Giardia lamblia, Isospora belli, and Cryptosporidium muris. Various drugs have been tried for these infections, including quinacrine hydrochloride, metronidazole, TMP-SMZ, and spiramycin. Cytomegalovirus (CMV) infections commonly involve the lungs, gastrointestinal tract, eyes, brain, and nervous system. Attempts to treat these disseminated CMV infections with antiviral agents, including acyclovir, have not been successful. However, acyclovir has been found beneficial in the treatment of herpes-simplex virus infections. Multiple infectious complications may occur in patients with AIDS as a result of the cellular-immune deficiency associated with this disease. Until more research is done with AIDS patients, therapy must be based on the data available from the treatment of these infections in immunosuppressed patients without AIDS.

The peculiarities of combined pathology of the upper gastrointestinal tract with allergic dermatoses in children

Directory of Open Access Journals (Sweden)

T.V. Sorokman

2017-04-01

Full Text Available Background. The recent studies indicate that one of the causes of allergic dermatoses (AD in children and adults is pathology of the gastrointestinal tract. However, many problems of the emergence of these combinations have not yet been resolved. The purpose of the study was to establish the incidence and the nature of lesions of the upper gastrointestinal tract (UGIT in children with allergic dermatoses. Materials and methods. On the base of the Chernivtsi Regional Children’s Hospital, 40 children with allergic dermatoses combined with the pathology of the upper gastrointestinal tract and 20 patients with AD, but without the UGIT pathology, aged 3 to 18 years were examined. A clinical and laboratory studies were conducted twice (routine clinical tests, chamber scratch test with non-infectious allergens during AD remission, as well as fibrogastroduodenoscopy, ultrasound, pH-measuring biochemical blood tests (alanine aminotransferase (ALT, aspartate aminotransferase (AST, gamma glutaminetransferase (GGTP, alkaline phosphatase, cholesterol, identification of H.pylori. Results. It was indicated that out of 40 examined children with AD, 30 (75 % persons had various lesions of the esophagus, stomach and duodenum. In 10 (25 % children, the functional changes, such as duodenogastral reflex (70 % and failure of the cardia (30 %, were detected. A multiple nature of reflux was observed in 85.7 % of children with chronic gastroduodenitis and in 100 % of children with esophagitis and duodenal ulcer disease. The contamination with H.pylori was detected in 72.5 % of cases. The increased activity of ALT and AST, GGTP, alkaline phosphatase and serum cholesterol was established. Conclusion. In 75 % of children with allergic dermatoses, an organic pathology of the upper gastrointestinal tract was diagnosed, thus, a gastroenterological examination should be recommended to all patients.

Epidemic threshold in directed networks

Science.gov (United States)

Li, Cong; Wang, Huijuan; Van Mieghem, Piet

2013-12-01

Epidemics have so far been mostly studied in undirected networks. However, many real-world networks, such as the online social network Twitter and the world wide web, on which information, emotion, or malware spreads, are directed networks, composed of both unidirectional links and bidirectional links. We define the directionality ξ as the percentage of unidirectional links. The epidemic threshold τc for the susceptible-infected-susceptible (SIS) epidemic is lower bounded by 1/λ1 in directed networks, where λ1, also called the spectral radius, is the largest eigenvalue of the adjacency matrix. In this work, we propose two algorithms to generate directed networks with a given directionality ξ. The effect of ξ on the spectral radius λ1, principal eigenvector x1, spectral gap (λ1-λ2), and algebraic connectivity μN-1 is studied. Important findings are that the spectral radius λ1 decreases with the directionality ξ, whereas the spectral gap and the algebraic connectivity increase with the directionality ξ. The extent of the decrease of the spectral radius depends on both the degree distribution and the degree-degree correlation ρD. Hence, in directed networks, the epidemic threshold is larger and a random walk converges to its steady state faster than that in undirected networks with the same degree distribution.

Gastrointestinal Stromal Tumors: A Case Report

Directory of Open Access Journals (Sweden)

Palankezhe Sashidharan

2014-03-01

Full Text Available Advances in the identification of gastrointestinal stromal tumors, its molecular and immunohiostochemical basis, and its management have been a watershed in the treatment of gastrointestinal tumors. This paradigm shift occurred over the last two decades and gastrointestinal stromal tumors have now come to be understood as rare gastrointestinal tract tumors with predictable behavior and outcome, replacing the older terminologies like leiomyoma, schwannoma or leiomyosarcoma. This report presents a case of gastric gastrointestinal stromal tumor operated recently in a 47-year-old female patient and the outcome, as well as literature review of the pathological identification, sites of origin, and factors predicting its behavior, prognosis and treatment.

Adaptive contact networks change effective disease infectiousness and dynamics.

Science.gov (United States)

Van Segbroeck, Sven; Santos, Francisco C; Pacheco, Jorge M

2010-08-19

Human societies are organized in complex webs that are constantly reshaped by a social dynamic which is influenced by the information individuals have about others. Similarly, epidemic spreading may be affected by local information that makes individuals aware of the health status of their social contacts, allowing them to avoid contact with those infected and to remain in touch with the healthy. Here we study disease dynamics in finite populations in which infection occurs along the links of a dynamical contact network whose reshaping may be biased based on each individual's health status. We adopt some of the most widely used epidemiological models, investigating the impact of the reshaping of the contact network on the disease dynamics. We derive analytical results in the limit where network reshaping occurs much faster than disease spreading and demonstrate numerically that this limit extends to a much wider range of time scales than one might anticipate. Specifically, we show that from a population-level description, disease propagation in a quickly adapting network can be formulated equivalently as disease spreading on a well-mixed population but with a rescaled infectiousness. We find that for all models studied here--SI, SIS and SIR--the effective infectiousness of a disease depends on the population size, the number of infected in the population, and the capacity of healthy individuals to sever contacts with the infected. Importantly, we indicate how the use of available information hinders disease progression, either by reducing the average time required to eradicate a disease (in case recovery is possible), or by increasing the average time needed for a disease to spread to the entire population (in case recovery or immunity is impossible).

Gastrointestinal Headache; a Narrative Review

OpenAIRE

Majid T Noghani; Hossein Rezaeizadeh; Sayed Mohammad Baqer Fazljoo; Mahmoud Yousefifard; Mansoor Keshavarz

2016-01-01

There are studies reporting primary headaches to be associated with gastrointestinal disorders, and some report resolution of headache following the treatment of the associated gastrointestinal disorder. Headache disorders are classified by The International Headache Society as primary or secondary; however, among the secondary headaches, those attributed to gastrointestinal disorders are not appreciated. Therefore, we aimed to review the literature to provide evidence for headaches, which or...

Prevalence of infectious and non-infectious diseases in cattle population in Moulvibazar district of Bangladesh

OpenAIRE

Chowdhury, Q M Monzur Kader; Roy, Sawrab; Alam, Shahrul; Ahmed, Juned

2018-01-01

Infectious and non-infectious diseases of cattle cause great economic losses of farmers as well as country every year by reducing growth, production and mortality of cattle population. The objective of this research work was to find out the prevalence of infectious and non-infectious diseases of cattle at Moulvibazar, Sylhet, Bangladesh. A total of 2285 clinical cases were diagnosed at District Veterinary Hospital in Moulvibazar, Bangladesh during January to June, 2016. Disease diagnosis was ...

Infectious diseases in competitive sports.

Science.gov (United States)

Goodman, R A; Thacker, S B; Solomon, S L; Osterholm, M T; Hughes, J M

1994-03-16

Participation in competitive sports is popular and widely encouraged throughout the United States. Reports of infectious disease outbreaks among competitive athletes and recent publicity regarding infectious disease concerns in sports underscore the need to better characterize the occurrence of these problems. To identify reports of infectious diseases in sports, we performed a comprehensive search of the medical literature (MEDLINE) and newspaper databases in two on-line services (NEXIS and DIALOG PAPERS). Articles selected from the literature review included those describing cases or outbreaks of disease in which exposure to an infectious agent was likely to have occurred during training for competitive sports or during actual competition. Articles from the newspaper review included reports of outbreaks, exposures, or preventive measures that directly or indirectly involved teams or spectators. The literature review identified 38 reports of infectious disease outbreaks or other instances of transmission through person-to-person (24 reports), common-source (nine reports), or airborne (five reports) routes; the newspaper search identified 28 reports. Infectious agents included predominantly viruses but also a variety of fungi and gram-positive and gram-negative bacteria. Our findings indicate that strategies to prevent transmission of infectious diseases in sports must recognize risks at three levels: the individual athlete, the team, and spectators or others who may become exposed to infectious diseases as a result of sports-related activities. Team physicians and others who are responsible for the health of athletes should be especially familiar with the features of infectious diseases that occur in sports and measures for the prevention of these problems.

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...

Modeling Epidemics Spreading on Social Contact Networks.

Science.gov (United States)

Zhang, Zhaoyang; Wang, Honggang; Wang, Chonggang; Fang, Hua

2015-09-01

Social contact networks and the way people interact with each other are the key factors that impact on epidemics spreading. However, it is challenging to model the behavior of epidemics based on social contact networks due to their high dynamics. Traditional models such as susceptible-infected-recovered (SIR) model ignore the crowding or protection effect and thus has some unrealistic assumption. In this paper, we consider the crowding or protection effect and develop a novel model called improved SIR model. Then, we use both deterministic and stochastic models to characterize the dynamics of epidemics on social contact networks. The results from both simulations and real data set conclude that the epidemics are more likely to outbreak on social contact networks with higher average degree. We also present some potential immunization strategies, such as random set immunization, dominating set immunization, and high degree set immunization to further prove the conclusion.

Gastrointestinal polyposis in Cowden disease

International Nuclear Information System (INIS)

Kullnig, P.; Steiner, H.; Porsch, G.; Smolle, J.

1987-01-01

A case of Cowden disease (multiple hamartoma syndrome) with marked gastrointestinal polyposis is presented. The differential diagnosis of gastrointestinal polyposis syndromes is discussed. (orig.) [de

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

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.

Pathogens: A New Open Access Journal Serving All Those Interested in Infectious Disease

Directory of Open Access Journals (Sweden)

Lawrence S. Young

2011-09-01

Full Text Available Infection ranks alongside cardiovascular disease as the major cause of human death across the world. Word Health Organization data for 2002 shows that 26% of all deaths, almost 15 million in number, were due to infectious disease with HIV/AIDS, TB and malaria being the top three responsible infections. A significant proportion of these deaths were due to lower respiratory infections and diarrheal diseases in children. The worldwide morbidity associated with infectious disease is incalculable. When considered along with the consequences of infection in animals, it is hard to imagine any other disease that has such a significant impact on our lives―on health systems, on agriculture and on world economics. Our understanding of the agents responsible for infections―bacteria, fungi, parasites, prions and viruses―has an interesting history that heralds the great developments in modern biology and demonstrates how an understanding of disease pathogenesis can lead to successful prophylactic and therapeutic interventions. Van Leeuwenhoek’s first observation of bacteria under the light microscope, John Snow’s investigations tracing the source of a cholera epidemic in Victorian London’s Soho and Pasteur’s vaccines for rabies and anthrax contributed to an acceptance of the germ theory of disease and to the rational, scientific application of this knowledge to develop innovative disease control measures ranging from hygienic practices to antibiotics. [...

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.

Optimal Control of Interdependent Epidemics in Complex Networks

OpenAIRE

Chen, Juntao; Zhang, Rui; Zhu, Quanyan

2017-01-01

Optimal control of interdependent epidemics spreading over complex networks is a critical issue. We first establish a framework to capture the coupling between two epidemics, and then analyze the system's equilibrium states by categorizing them into three classes, and deriving their stability conditions. The designed control strategy globally optimizes the trade-off between the control cost and the severity of epidemics in the network. A gradient descent algorithm based on a fixed point itera...

Predicting extinction rates in stochastic epidemic models

International Nuclear Information System (INIS)

Schwartz, Ira B; Billings, Lora; Dykman, Mark; Landsman, Alexandra

2009-01-01

We investigate the stochastic extinction processes in a class of epidemic models. Motivated by the process of natural disease extinction in epidemics, we examine the rate of extinction as a function of disease spread. We show that the effective entropic barrier for extinction in a susceptible–infected–susceptible epidemic model displays scaling with the distance to the bifurcation point, with an unusual critical exponent. We make a direct comparison between predictions and numerical simulations. We also consider the effect of non-Gaussian vaccine schedules, and show numerically how the extinction process may be enhanced when the vaccine schedules are Poisson distributed

Suppressing traffic-driven epidemic spreading by adaptive routing strategy

International Nuclear Information System (INIS)

Yang, Han-Xin; Wang, Zhen

2016-01-01

The design of routing strategies for traffic-driven epidemic spreading has received increasing attention in recent years. In this paper, we propose an adaptive routing strategy that incorporates topological distance with local epidemic information through a tunable parameter h. In the case where the traffic is free of congestion, there exists an optimal value of routing parameter h, leading to the maximal epidemic threshold. This means that epidemic spreading can be more effectively controlled by adaptive routing, compared to that of the static shortest path routing scheme. Besides, we find that the optimal value of h can greatly relieve the traffic congestion in the case of finite node-delivering capacity. We expect our work to provide new insights into the effects of dynamic routings on traffic-driven epidemic spreading.

Infectious mononucleosis #3 (image)

Science.gov (United States)

Infectious mononucleosis is caused by the Epstein-Barr virus. It is a viral infection causing high temperature, sore throat, and swollen lymph glands. Infectious mononucleosis can be contagious if the infected person comes ...

Epidemic dynamics and endemic states in complex networks

OpenAIRE

Pastor-Satorras, Romualdo; Vespignani, Alessandro

2001-01-01

We study by analytical methods and large scale simulations a dynamical model for the spreading of epidemics in complex networks. In networks with exponentially bounded connectivity we recover the usual epidemic behavior with a threshold defining a critical point below which the infection prevalence is null. On the contrary, on a wide range of scale-free networks we observe the absence of an epidemic threshold and its associated critical behavior. This implies that scale-free networks are pron...

Tumor del estroma gastrointestinal Tumor of the gastrointestinal stroma

Directory of Open Access Journals (Sweden)

Jorge Felipe Montero León

2012-03-01

Full Text Available Los tumores del estroma gastrointestinal, conocidos según sus siglas en inglés como GIST (gastrointestinal stromal tumors, son tumores mesenquimales que aparecen en cualquier lugar a lo largo del tracto intestinal. Este trabajo tiene el propósito de presentar una paciente de 60 años de edad que asiste a la consulta de ginecología del Instituto Nacional de Oncología y Radiobiología, por presentar dolor en el epigastrio, que se irradia al flanco derecho, con un aumento de volumen en la fosa iliaca derecha, y por ultrasonografía se plantea un tumor de ovario derecho, que se proyecta hacia el epigastrio y a hipocondrio derecho. Se describe la intervención quirúrgica y los hallazgos encontrados en estudios macro y microscópicos, así como en estudios posteriores por inmunohistoquímica de la lesión. Se concluye con un diagnóstico de tumor del estroma gastrointestinal y los resultados de las intervenciones quirúrgicas y medicamentosas realizadas. Se recomienda valorar la importancia de una estrecha relación entre cirujanos generales y ginecólogos frente a enfermedades inesperadas, por su difícil diagnóstico preoperatorio, que conllevan a un tratamiento quirúrgico adecuado, y que por la complejidad que requieren, necesitan de la competencia de ambas especialidades quirúrgicas.The tumors of the gastrointestinal stroma, known in English language as GIST (gastrointestinal stromal tumors are mesenchymal tumors appearing in any place throughout the intestinal tract. The objective of present paper is to present the case of a female patient aged 60 came to Genecology consultation of the National Institute of Oncology and Radiobiology due pain in epigastrium irradiating to right flank with increase of volume in the right iliac fossa and by ultrasonography it is a tumor of right ovarium projecting to epigastrium and the right hypochondrium. The surgical intervention is described as well as the findings noted in macro- and microscopic studies

Upper gastrointestinal bleeding in patients with CKD.

Science.gov (United States)

Liang, Chih-Chia; Wang, Su-Ming; Kuo, Huey-Liang; Chang, Chiz-Tzung; Liu, Jiung-Hsiun; Lin, Hsin-Hung; Wang, I-Kuan; Yang, Ya-Fei; Lu, Yueh-Ju; Chou, Che-Yi; Huang, Chiu-Ching

2014-08-07

Patients with CKD receiving maintenance dialysis are at risk for upper gastrointestinal bleeding. However, the risk of upper gastrointestinal bleeding in patients with early CKD who are not receiving dialysis is unknown. The hypothesis was that their risk of upper gastrointestinal bleeding is negatively linked to renal function. To test this hypothesis, the association between eGFR and risk of upper gastrointestinal bleeding in patients with stages 3-5 CKD who were not receiving dialysis was analyzed. Patients with stages 3-5 CKD in the CKD program from 2003 to 2009 were enrolled and prospectively followed until December of 2012 to monitor the development of upper gastrointestinal bleeding. The risk of upper gastrointestinal bleeding was analyzed using competing-risks regression with time-varying covariates. In total, 2968 patients with stages 3-5 CKD who were not receiving dialysis were followed for a median of 1.9 years. The incidence of upper gastrointestinal bleeding per 100 patient-years was 3.7 (95% confidence interval, 3.5 to 3.9) in patients with stage 3 CKD, 5.0 (95% confidence interval, 4.8 to 5.3) in patients with stage 4 CKD, and 13.9 (95% confidence interval, 13.1 to 14.8) in patients with stage 5 CKD. Higher eGFR was associated with a lower risk of upper gastrointestinal bleeding (P=0.03), with a subdistribution hazard ratio of 0.93 (95% confidence interval, 0.87 to 0.99) for every 5 ml/min per 1.73 m(2) higher eGFR. A history of upper gastrointestinal bleeding (Pupper gastrointestinal bleeding risk. In patients with CKD who are not receiving dialysis, lower renal function is associated with higher risk for upper gastrointestinal bleeding. The risk is higher in patients with previous upper gastrointestinal bleeding history and low serum albumin. Copyright © 2014 by the American Society of Nephrology.

[Common pediatric infectious diseases following natural disasters].

Science.gov (United States)

Yao, Kai-Hu

2013-06-01

Natural disasters may lead to the outbreaks of infectious diseases because they increase the risk factors for infectious diseases. This paper reviews the risk factors for infectious diseases after natural disasters, especially earthquake, and the infectious diseases following disasters reported in recent years. The infectious diseases after earthquake include diarrhea, cholera, viral hepatitis, upper respiratory tract infection, tuberculosis, measles, leptospirosis, dengue fever, tetanus, and gas gangrene, as well as some rare infections. Children are vulnerable to infectious diseases, so pediatricians should pay more attention to the research on relationship between infectious diseases and natural disasters.

Stemming the obesity epidemic : a tantalizing prospect

NARCIS (Netherlands)

Veerman, J Lennert; Barendregt, Jan J; van Beeck, Ed F; Seidell, Jacob C; Mackenbach, Johan P

OBJECTIVE: Obesity is a growing problem worldwide, but there are no good methods to assess the future course of the epidemic and the potential influence of interventions. We explore the behavior change needed to stop the obesity epidemic in the U.S. RESEARCH METHODS AND PROCEDURES: We modeled the

Exercise and the gastro-intestinal tract

African Journals Online (AJOL)

on perfonnance and me value of cardiovascular training in improving performance in aerobic sports is well recognised. The role of me gastro-intestinal tracr, bom as a limiting and sustaining facror in aerobic exercises, is less well appreciared. Gastro-intestinal symptoms. The spectrum of gastro-intestinal effecrs of exercise ...

The rise and fall of rabies in Japan: A quantitative history of rabies epidemics in Osaka Prefecture, 1914-1933.

Directory of Open Access Journals (Sweden)

Aiko Kurosawa

2017-03-01

Full Text Available Japan has been free from rabies since the 1950s. However, during the early 1900s several large-scale epidemics spread throughout the country. Here we investigate the dynamics of these epidemics between 1914 and 1933 in Osaka Prefecture, using archival data including newspapers. The association between dog rabies cases and human population density was investigated using Mixed-effects models and epidemiological parameters such as the basic reproduction number (R0, the incubation and infectious period and the serial interval were estimated. A total of 4,632 animal rabies cases were reported, mainly in dogs (99.0%, 4,584 cases during two epidemics from 1914 to 1921, and 1922 to 1933 respectively. The second epidemic was larger (3,705 cases than the first (879 cases, but had a lower R0 (1.50 versus 2.42. The first epidemic was controlled through capture of stray dogs and tethering of pet dogs. Dog mass vaccination began in 1923, with campaigns to capture stray dogs. Rabies in Osaka Prefecture was finally eliminated in 1933. A total of 3,805 rabid dog-bite injuries, and 75 human deaths were reported. The relatively low incidence of human rabies, high ratio of post-exposure vaccines (PEP and bite injuries by rabid dogs (minimum 6.2 to maximum 73.6, between 1924 and 1928, and a decline in the proportion of bite victims that developed hydrophobia over time (slope = -0.29, se = 3, p < 0.001, indicated that increased awareness and use of PEP might have prevented disease. Although significantly more dog rabies cases were detected at higher human population densities (slope = 0.66, se = 0.03, p < 0.01, there were fewer dog rabies cases detected per capita (slope = -0.34, se = 0.03, p < 0.01. We suggest that the combination of mass vaccination and restriction of dog movement enabled by strong legislation was key to eliminate rabies. Moreover, the prominent role of the media in both reporting rabies cases and efforts to control the disease likely contributed

Reporting systems in gastrointestinal endoscopy: Requirements and standards facilitating quality improvement: European Society of Gastrointestinal Endoscopy position statement

NARCIS (Netherlands)

Bretthauer, Michael; Aabakken, Lars; Dekker, Evelien; Kaminski, Michal F.; Rösch, Thomas; Hultcrantz, Rolf; Suchanek, Stepan; Jover, Rodrigo; Kuipers, Ernst J.; Bisschops, Raf; Spada, Cristiano; Valori, Roland; Domagk, Dirk; Rees, Colin; Rutter, Matthew D.

2016-01-01

To develop standards for high quality of gastrointestinal endoscopy, the European Society of Gastrointestinal Endoscopy (ESGE) has established the ESGE Quality Improvement Committee. A prerequisite for quality assurance and improvement for all gastrointestinal endoscopy procedures is

Could the Recent Zika Epidemic Have Been Predicted?

Science.gov (United States)

Vecchi, G. A.; Munoz, A. G.; Thomson, M. C.; Stewart-Ibarra, A. M.; Chourio, X.; Nájera, P.; Moran, Z.; Yang, X.

2017-12-01

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.

European Society of Gastrointestinal Endoscopy - Establishing the key unanswered research questions within gastrointestinal endoscopy

DEFF Research Database (Denmark)

Rees, Colin J; Ngu, Wee Sing; Regula, Jaroslaw

2016-01-01

Background and study aim: Gastrointestinal endoscopy is a rapidly evolving research field. The European Society of Gastrointestinal Endoscopy (ESGE) plays a key role in shaping opinion and endoscopy activity throughout Europe and further afield. Establishing key unanswered questions within the fi...

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.

Set-membership estimations for the evolution of infectious diseases in heterogeneous populations.

Science.gov (United States)

Tsachev, Tsvetomir; Veliov, Vladimir M; Widder, Andreas

2017-04-01

The paper presents an approach for set-membership estimation of the state of a heterogeneous population in which an infectious disease is spreading. The population state may consist of susceptible, infected, recovered, etc. groups, where the individuals are heterogeneous with respect to traits, relevant to the particular disease. Set-membership estimations in this context are reasonable, since only vague information about the distribution of the population along the space of heterogeneity is available in practice. The presented approach comprises adapted versions of methods which are known in estimation and control theory, and involve solving parametrized families of optimization problems. Since the models of disease spreading in heterogeneous populations involve distributed systems (with non-local dynamics and endogenous boundary conditions), these problems are non-standard. The paper develops the needed theoretical instruments and a solution scheme. SI and SIR models of epidemic diseases are considered as case studies and the results reveal qualitative properties that may be of interest.

Epidemic spreading with activity-driven awareness diffusion on multiplex network.

Science.gov (United States)

Guo, Quantong; Lei, Yanjun; Jiang, Xin; Ma, Yifang; Huo, Guanying; Zheng, Zhiming

2016-04-01

There has been growing interest in exploring the interplay between epidemic spreading with human response, since it is natural for people to take various measures when they become aware of epidemics. As a proper way to describe the multiple connections among people in reality, multiplex network, a set of nodes interacting through multiple sets of edges, has attracted much attention. In this paper, to explore the coupled dynamical processes, a multiplex network with two layers is built. Specifically, the information spreading layer is a time varying network generated by the activity driven model, while the contagion layer is a static network. We extend the microscopic Markov chain approach to derive the epidemic threshold of the model. Compared with extensive Monte Carlo simulations, the method shows high accuracy for the prediction of the epidemic threshold. Besides, taking different spreading models of awareness into consideration, we explored the interplay between epidemic spreading with awareness spreading. The results show that the awareness spreading can not only enhance the epidemic threshold but also reduce the prevalence of epidemics. When the spreading of awareness is defined as susceptible-infected-susceptible model, there exists a critical value where the dynamical process on the awareness layer can control the onset of epidemics; while if it is a threshold model, the epidemic threshold emerges an abrupt transition with the local awareness ratio α approximating 0.5. Moreover, we also find that temporal changes in the topology hinder the spread of awareness which directly affect the epidemic threshold, especially when the awareness layer is threshold model. Given that the threshold model is a widely used model for social contagion, this is an important and meaningful result. Our results could also lead to interesting future research about the different time-scales of structural changes in multiplex networks.

Epidemic spreading with activity-driven awareness diffusion on multiplex network

Science.gov (United States)

Guo, Quantong; Lei, Yanjun; Jiang, Xin; Ma, Yifang; Huo, Guanying; Zheng, Zhiming

2016-04-01

There has been growing interest in exploring the interplay between epidemic spreading with human response, since it is natural for people to take various measures when they become aware of epidemics. As a proper way to describe the multiple connections among people in reality, multiplex network, a set of nodes interacting through multiple sets of edges, has attracted much attention. In this paper, to explore the coupled dynamical processes, a multiplex network with two layers is built. Specifically, the information spreading layer is a time varying network generated by the activity driven model, while the contagion layer is a static network. We extend the microscopic Markov chain approach to derive the epidemic threshold of the model. Compared with extensive Monte Carlo simulations, the method shows high accuracy for the prediction of the epidemic threshold. Besides, taking different spreading models of awareness into consideration, we explored the interplay between epidemic spreading with awareness spreading. The results show that the awareness spreading can not only enhance the epidemic threshold but also reduce the prevalence of epidemics. When the spreading of awareness is defined as susceptible-infected-susceptible model, there exists a critical value where the dynamical process on the awareness layer can control the onset of epidemics; while if it is a threshold model, the epidemic threshold emerges an abrupt transition with the local awareness ratio α approximating 0.5. Moreover, we also find that temporal changes in the topology hinder the spread of awareness which directly affect the epidemic threshold, especially when the awareness layer is threshold model. Given that the threshold model is a widely used model for social contagion, this is an important and meaningful result. Our results could also lead to interesting future research about the different time-scales of structural changes in multiplex networks.

Effects of epidemic threshold definition on disease spread statistics

Science.gov (United States)

Lagorio, C.; Migueles, M. V.; Braunstein, L. A.; López, E.; Macri, P. A.

2009-03-01

We study the statistical properties of SIR epidemics in random networks, when an epidemic is defined as only those SIR propagations that reach or exceed a minimum size sc. Using percolation theory to calculate the average fractional size of an epidemic, we find that the strength of the spanning link percolation cluster P∞ is an upper bound to . For small values of sc, P∞ is no longer a good approximation, and the average fractional size has to be computed directly. We find that the choice of sc is generally (but not always) guided by the network structure and the value of T of the disease in question. If the goal is to always obtain P∞ as the average epidemic size, one should choose sc to be the typical size of the largest percolation cluster at the critical percolation threshold for the transmissibility. We also study Q, the probability that an SIR propagation reaches the epidemic mass sc, and find that it is well characterized by percolation theory. We apply our results to real networks (DIMES and Tracerouter) to measure the consequences of the choice sc on predictions of average outcome sizes of computer failure epidemics.

The influence of school holiday timing on epidemic impact.

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Eames, K T D

2014-09-01

The impact of reactive school closure on an epidemic is uncertain, since it is not clear how an unplanned closure will affect social mixing patterns. The effect of school holidays on social mixing patterns is better understood. Here, we use mathematical models to explore the influence of the timing of school holidays on the final size and peak incidence of an influenza-like epidemic. A well-timed holiday can reduce the impact of an epidemic, in particular substantially reducing an epidemic's peak. Final size and peak incidence cannot both be minimized: a later holiday is optimal for minimizing the final size, while an earlier holiday minimizes peak incidence. Using social mixing data from the UK, we estimated that, had the 2009 influenza epidemic not been interrupted by the school summer holidays, the final size would have been about 20% larger and the peak about 170% higher.

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

Human drivers of ecological and evolutionary dynamics in emerging and disappearing infectious disease systems.

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Rogalski, Mary A; Gowler, Camden D; Shaw, Clara L; Hufbauer, Ruth A; Duffy, Meghan A

2017-01-19

Humans have contributed to the increased frequency and severity of emerging infectious diseases, which pose a significant threat to wild and domestic species, as well as human health. This review examines major pathways by which humans influence parasitism by altering (co)evolutionary interactions between hosts and parasites on ecological timescales. There is still much to learn about these interactions, but a few well-studied cases show that humans influence disease emergence every step of the way. Human actions significantly increase dispersal of host, parasite and vector species, enabling greater frequency of infection in naive host populations and host switches. Very dense host populations resulting from urbanization and agriculture can drive the evolution of more virulent parasites and, in some cases, more resistant host populations. Human activities that reduce host genetic diversity or impose abiotic stress can impair the ability of hosts to adapt to disease threats. Further, evolutionary responses of hosts and parasites can thwart disease management and biocontrol efforts. Finally, in rare cases, humans influence evolution by eradicating an infectious disease. If we hope to fully understand the factors driving disease emergence and potentially control these epidemics we must consider the widespread influence of humans on host and parasite evolutionary trajectories.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'. © 2016 The Author(s).

Could the Recent Zika Epidemic Have Been Predicted?

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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.

epidemic teach us?

African Journals Online (AJOL)

frequently brings shame, fear and guilt: dealing with this for some will begin a process of .... 'AZT treatment will have a limited effect on the epidemic, as we are targeting ... others to make the decisions that control my life. It is ironic that a society ...

Moving beyond too little, too late: managing emerging infectious diseases in wild populations requires international policy and partnerships

Science.gov (United States)

Voyles, Jamie; Kilpatrick, A. Marm; Collins, James P.; Fisher, Matthew C.; Frick, Winifred F.; McCallum, Hamish I.; Willis, Craig K.R.; Blehert, David S.; Murray, Kris A.; Puschendorf, Robert; Rosenblum, Erica Bree; Bolker, Benjamin M.; Cheng, Tina L.; Langwig, Kate E.; Linder, Daniel L.; Toothman, Mary; Wilber, Mark Q.; Briggs, Cheryl J.

2015-01-01

Emerging infectious diseases (EIDs) are on the rise due to multiple factors, including human facilitated movement of pathogens, broad-scale landscape changes, and perturbations to ecological systems (Jones et al. 2008; Fisher et al. 2012). Epidemics in wildlife are problematic because they can lead to pathogen spillover to new host organisms, erode biodiversity and threaten ecosystems that sustain human societies (Fisher et al. 2012; Kilpatrick 2011). There have been recent calls for large-scale research approaches to combat threats EIDs pose to wildlife (Sleeman 2013). While it is true that developing new analytical models, diagnostic assays and molecular tools will significantly avance outr abilities to respond to disease threats, we also propose that addressing difficult problems in EIDs will require considerable shofts in international health policy and infrastructure. While there are currently international organizations responsbile for rapidly initiating and coordinating preventative measures to control infectious diseases in human, livestock, and arable systems, there are few comparable instiutions that have the authority to implement transnational responses to EIDs in wildlife. This absence of well-developed infastructure hampers the rapid responses necessary to mitigate international spread of EIDs.

Dynamical Interplay between Awareness and Epidemic Spreading in Multiplex Networks

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Granell, Clara; Gómez, Sergio; Arenas, Alex

2013-09-01

We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases.

Dynamical interplay between awareness and epidemic spreading in multiplex networks.

Science.gov (United States)

Granell, Clara; Gómez, Sergio; Arenas, Alex

2013-09-20

We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases.

Disease-induced resource constraints can trigger explosive epidemics

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Böttcher, L.; Woolley-Meza, O.; Araújo, N. A. M.; Herrmann, H. J.; Helbing, D.

2015-11-01

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 parameters that characterize the spreading process. Our model and results apply beyond epidemics to contagion dynamics that self-induce constraints on recovery, thereby amplifying the spreading process.

2,500-year Evolution of the Term Epidemic

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Martin-Granel, Estelle

2006-01-01

The term epidemic (from the Greek epi [on] plus demos [people]), first used by Homer, took its medical meaning when Hippocrates used it as the title of one of his famous treatises. At that time, epidemic was the name given to a collection of clinical syndromes, such as coughs or diarrheas, occurring and propagating in a given period at a given location. Over centuries, the form and meaning of the term have changed. Successive epidemics of plague in the Middle Ages contributed to the definition of an epidemic as the propagation of a single, well-defined disease. The meaning of the term continued to evolve in the 19th-century era of microbiology. Its most recent semantic evolution dates from the last quarter of the 20th century, and this evolution is likely to continue in the future. PMID:16707055

Epidemic spreading on interconnected networks.

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Saumell-Mendiola, Anna; Serrano, M Ángeles; Boguñá, Marián

2012-08-01

Many real networks are not isolated from each other but form networks of networks, often interrelated in nontrivial ways. Here, we analyze an epidemic spreading process taking place on top of two interconnected complex networks. We develop a heterogeneous mean-field approach that allows us to calculate the conditions for the emergence of an endemic state. Interestingly, a global endemic state may arise in the coupled system even though the epidemics is not able to propagate on each network separately and even when the number of coupling connections is small. Our analytic results are successfully confronted against large-scale numerical simulations.

Epidemic Spread in Networks Induced by Deactivation Mechanism

International Nuclear Information System (INIS)

Yu Xiaoling; Wu Xiao; Zhang Duanming; Li Zhihao; Liang Fang; Wang Xiaoyu

2008-01-01

We have studied the topology and epidemic spreading behaviors on the networks in which deactivation mechanism and long-rang connection are coexisted. By means of numerical simulation, we find that the clustering coefficient C and the Pearson correlation coefficient r decrease with increasing long-range connection μ and the topological state of the network changes into that of BA model at the end (when μ = 1). For the Susceptible-Infect-Susceptible model of epidemics, the epidemic threshold can reach maximum value at μ = 0.4 and presents two different variable states around μ = 0.4

The need for data science in epidemic modelling. Comment on: "Mathematical models to characterize early epidemic growth: A review" by Gerardo Chowell et al.

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Danon, Leon; Brooks-Pollock, Ellen

2016-09-01

In their review, Chowell et al. consider the ability of mathematical models to predict early epidemic growth [1]. In particular, they question the central prediction of classical differential equation models that the number of cases grows exponentially during the early stages of an epidemic. Using examples including HIV and Ebola, they argue that classical models fail to capture key qualitative features of early growth and describe a selection of models that do capture non-exponential epidemic growth. An implication of this failure is that predictions may be inaccurate and unusable, highlighting the need for care when embarking upon modelling using classical methodology. There remains a lack of understanding of the mechanisms driving many observed epidemic patterns; we argue that data science should form a fundamental component of epidemic modelling, providing a rigorous methodology for data-driven approaches, rather than trying to enforce established frameworks. The need for refinement of classical models provides a strong argument for the use of data science, to identify qualitative characteristics and pinpoint the mechanisms responsible for the observed epidemic patterns.

Transferring the Malaria Epidemic Prediction Model to Users in East ...

International Development Research Centre (IDRC) Digital Library (Canada)

Transferring the Malaria Epidemic Prediction Model to Users in East Africa. In the highlands of East Africa, epidemic malaria is an emerging climate-related hazard that urgently needs addressing. Malaria incidence increased by 337% during the 1987 epidemic in Rwanda. In Tanzania, Uganda and Kenya, malaria incidence ...

Foreign bodies in gastrointestinal tract

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Ayşe Kefeli

2014-03-01

Full Text Available Objective: Ingested foreign bodies in gastrointestinal tract are a common event which can cause serious morbidity and mortality in the children and adult population. For this reason, early diagnosis and treatment are crucial for preventing these life threatening complications. In this study, we aimed to analyze the characteristics of the patients with upper gastrointestinal foreign bodies that were treated in our department. Methods: Patients diagnosed with upper gastrointestinal foreign bodies who were admitted to our hospital between February 2010 and August2013 were evaluated retrospectively. The data regarding their age, gender, clinical profile, type and localization of the esophageal foreign body, performed endoscopic procedure and initial symptoms of the patients were noted and analyzed statistically. Results: Thirty-eight patients with a diagnosis of gastrointestinal foreign body were included in this study. Of these patients, 21 were male and 17 were female. The youngest patient was 17 years old and the oldest patient was 79 years old. Most of the foreign bodies (%55.3 detected in the stomach. Food waste and metallic objects in 21 and 16 patients respectively. The most common complaint was dysphagia (%50. After endoscopic intervention three of the patients were directed to surgery. Conclusion: Early recognition and treatment of gastrointestinal foreign bodies is important as their complications are life threatening. The best method of removal of foreign bodies is controversial. Early management with upper gastrointestinal endoscopy is the most efficient and safe treatment method in current conditions.

Epidemic spreading between two coupled subpopulations with inner structures

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Ruan, Zhongyuan; Tang, Ming; Gu, Changgui; Xu, Jinshan

2017-10-01

The structure of underlying contact network and the mobility of agents are two decisive factors for epidemic spreading in reality. Here, we study a model consisting of two coupled subpopulations with intra-structures that emphasizes both the contact structure and the recurrent mobility pattern of individuals simultaneously. We show that the coupling of the two subpopulations (via interconnections between them and round trips of individuals) makes the epidemic threshold in each subnetwork to be the same. Moreover, we find that the interconnection probability between two subpopulations and the travel rate are important factors for spreading dynamics. In particular, as a function of interconnection probability, the epidemic threshold in each subpopulation decreases monotonously, which enhances the risks of an epidemic. While the epidemic threshold displays a non-monotonic variation as travel rate increases. Moreover, the asymptotic infected density as a function of travel rate in each subpopulation behaves differently depending on the interconnection probability.

Epidemic Intelligence. Langmuir and the Birth of Disease Surveillance

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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.

Sleep Dysfunction and Gastrointestinal Diseases.

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Khanijow, Vikesh; Prakash, Pia; Emsellem, Helene A; Borum, Marie L; Doman, David B

2015-12-01

Sleep deprivation and impaired sleep quality have been associated with poor health outcomes. Many patients experience sleep disturbances, which can increase the risk of medical conditions such as hypertension, obesity, stroke, and heart disease as well as increase overall mortality. Recent studies have suggested that there is a strong association between sleep disturbances and gastrointestinal diseases. Proinflammatory cytokines, such as tumor necrosis factor, interleukin-1, and interleukin-6, have been associated with sleep dysfunction. Alterations in these cytokines have been seen in certain gastrointestinal diseases, such as gastroesophageal reflux disease, inflammatory bowel disease, liver disorders, and colorectal cancer. It is important for gastroenterologists to be aware of the relationship between sleep disorders and gastrointestinal illnesses to ensure good care for patients. This article reviews the current research on the interplay between sleep disorders, immune function, and gastrointestinal diseases.

Scintigraphic evaluation of gastrointestinal bleeding

International Nuclear Information System (INIS)

Park, Yong Tai; Lee, Choon Keun; Lee, Sun Wha; Choi, Woo Suk; Yoon, Yup; Lim, Jae Hoon

1988-01-01

Gastrointestinal bleeding remains a major diagnostic problem. Although advances have been made in the medical and surgical methods of managing gastrointestinal bleeding, the commonly employed techniques of barium radiography, endoscopy, and angiography may not successfully localize the site and define the cause of gastrointestinal bleeding. Two widely available technetium-99m-labeled radiopharmaceuticals, sulfur colloid and red blood cells are currently used in the evaluation of patients who are bleeding from the gastrointestinal tract. Surgically confirmed 19 patients with use of 99m Tc-sulfur colloid (7 cases) and 99m Tc-RBC (12 cases) were retrospectively evaluated. The overall sensitivity of scintigraphy in detection of bleeding and localization of bleeding site was 68% and 84%, respectively. The authors conclude that bleeding scintigraphy is a safe, sensitive, and non-invasive method as an effective screening test before performing angiography or surgery.

NON-INFECTIOUS DISORDERS OF WARMWATER FISHES

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Compared with infectious diseases and disorders, few non-infectious diseases and disorders in cultured fish have severe biologic or economic impact. Culture practices, however, often establish environments that promote infectious disease by weakening the immune response or by pro...

A geographic information system for the study of past epidemics: The 1705 epidemic in Martigues (Bouches-du-Rhône, France

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Stéfan Tzortzis

2012-01-01

Full Text Available At the beginning of the 18th century, the Provence region was hit by several severe epidemics whose causes are still not clearly understood.To draw up epidemic profiles and to identify the pathogenic agents concerned, we constituted a large onomastic database and built ageographic information system for Martigues, a medium-sized community in the south of France. The cross-linking of epidemiological,spatial and demographical data allows us to propose a new diagnosis for the epidemic which reached Martigues in the autumn of 1705.

Infectious diseases of afghan immigrants in the united states: review of published reports

International Nuclear Information System (INIS)

Pilsczek, F.H.

2011-01-01

Infectious diseases of immigrants may differ from patients born and resident in the same country, especially if immigrants from Africa or Asia live in Europe or North America. Because the available information is limited published reports of infections of Afghan immigrants in the United States and other countries were analysed. Four reports from the US and 15 reports from other countries were identified [7, (46.7%) Pakistan, 5 (33.3%) Iran, 1 (6.7%) United Kingdom, 1 (6.7%) Germany, 1 (6.7%) Israel)]. Reports from the US were case reports or case series of infections with gastro-intestinal parasites and Mycobacterium tuberculosis (1, 25%), Echinococcus species (2, 50%), and Plasmodium vivax (1, 25%). Reports from other countries were case reports, case series, or surveys and investigated infections with Echinococcus species (2, 13%), Hepatitis B virus (HBV) (1, 6.7%), M. tuberculosis (6, 40%), P. falciparum (1, 6.7%), Leishmania tropica (3, 20%), Fasciola hepatica (1, 6.7%), and M. leprae (1, 6.7%). The reports suggest that Echinococcus species and L. tropica infections can be encountered in Afghan immigrants in the US, and the frequency of a positive PPD (purified protein derivative) response or HBsAg test was increased. An infectious diseases database specific for the country of residence readily available to clinicians treating Afghan patients outside of Afghanistan may be useful. (author)

The role of endoscopy in pediatric gastrointestinal bleeding

Science.gov (United States)

Franke, Markus; Geiß, Andrea; Greiner, Peter; Wellner, Ulrich; Richter-Schrag, Hans-Jürgen; Bausch, Dirk; Fischer, Andreas

2016-01-01

Background and study aims: Gastrointestinal bleeding in children and adolescents accounts for up to 20 % of referrals to gastroenterologists. Detailed management guidelines exist for gastrointestinal bleeding in adults, but they do not encompass children and adolescents. The aim of this study was to assess gastrointestinal bleeding in pediatric patients and to determine an investigative management algorithm accounting for the specifics of children and adolescents. Patients and methods: Pediatric patients with gastrointestinal bleeding admitted to our endoscopy unit from 2001 to 2009 (n = 154) were identified. Retrospective statistical and neural network analysis was used to assess outcome and to determine an investigative management algorithm. Results: The source of bleeding could be identified in 81 % (n = 124/154). Gastrointestinal bleeding was predominantly lower gastrointestinal bleeding (66 %, n = 101); upper gastrointestinal bleeding was much less common (14 %, n = 21). Hematochezia was observed in 94 % of the patients with lower gastrointestinal bleeding (n = 95 of 101). Hematemesis (67 %, n = 14 of 21) and melena (48 %, n = 10 of 21) were associated with upper gastrointestinal bleeding. The sensitivity and specificity of a neural network to predict lower gastrointestinal bleeding were 98 % and 63.6 %, respectively and to predict upper gastrointestinal bleeding were 75 % and 96 % respectively. The sensitivity and specifity of hematochezia alone to predict lower gastrointestinal bleeding were 94.2 % and 85.7 %, respectively. The sensitivity and specificity for hematemesis and melena to predict upper gastrointestinal bleeding were 82.6 % and 94 %, respectively. We then developed an investigative management algorithm based on the presence of hematochezia and hematemesis or melena. Conclusions: Hematochezia should prompt colonoscopy and hematemesis or melena should prompt esophagogastroduodenoscopy. If no

[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.

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 ...

Dynamics of infectious diseases

International Nuclear Information System (INIS)

Rock, Kat; Brand, Sam; Moir, Jo; Keeling, Matt J

2014-01-01

Modern infectious disease epidemiology has a strong history of using mathematics both for prediction and to gain a deeper understanding. However the study of infectious diseases is a highly interdisciplinary subject requiring insights from multiple disciplines, in particular a biological knowledge of the pathogen, a statistical description of the available data and a mathematical framework for prediction. Here we begin with the basic building blocks of infectious disease epidemiology—the SIS and SIR type models—before considering the progress that has been made over the recent decades and the challenges that lie ahead. Throughout we focus on the understanding that can be developed from relatively simple models, although accurate prediction will inevitably require far greater complexity beyond the scope of this review. In particular, we focus on three critical aspects of infectious disease models that we feel fundamentally shape their dynamics: heterogeneously structured populations, stochasticity and spatial structure. Throughout we relate the mathematical models and their results to a variety of real-world problems. (review article)

Is the New Heroin Epidemic Really New? Racializing Heroin.

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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. Copyright © 2016 National Medical Association. Published by Elsevier Inc. All rights reserved.

West Nile Virus: High Transmission Rate in North-Western European Mosquitoes Indicates Its Epidemic Potential and Warrants Increased Surveillance.

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Jelke J Fros

Full Text Available West Nile virus (WNV is a highly pathogenic flavivirus transmitted by Culex spp. mosquitoes. In North America (NA, lineage 1 WNV caused the largest outbreak of neuroinvasive disease to date, while a novel pathogenic lineage 2 strain circulates in southern Europe. To estimate WNV lineage 2 epidemic potential it is paramount to know if mosquitoes from currently WNV-free areas can support further spread of this epidemic.We assessed WNV vector competence of Culex pipiens mosquitoes originating from north-western Europe (NWE in direct comparison with those from NA. We exposed mosquitoes to infectious blood meals of lineage 1 or 2 WNV and determined the infection and transmission rates. We explored reasons for vector competence differences by comparing intrathoracic injection versus blood meal infection, and we investigated the influence of temperature. We found that NWE mosquitoes are highly competent for both WNV lineages, with transmission rates up to 25%. Compared to NA mosquitoes, transmission rates for lineage 2 WNV were significantly elevated in NWE mosquitoes due to better virus dissemination from the midgut and a shorter extrinsic incubation time. WNV infection rates further increased with temperature increase.Our study provides experimental evidence to indicate markedly different risk levels between both continents for lineage 2 WNV transmission and suggests a degree of genotype-genotype specificity in the interaction between virus and vector. Our experiments with varying temperatures explain the current localized WNV activity in southern Europe, yet imply further epidemic spread throughout NWE during periods with favourable climatic conditions. This emphasizes the need for intensified surveillance of virus activity in current WNV disease-free regions and warrants increased awareness in clinics throughout Europe.

Are we prepared for emerging and re-emerging diseases? Experience and lessons from epidemics that occurred in Tanzania during the last five decades.

Science.gov (United States)

Karimuribo, Esron D; Mboera, Leonard E G; Mbugi, Erasto; Simba, Azma; Kivaria, Fredrick M; Mmbuji, Peter; Rweyemamu, Mark M

2011-12-01

This paper reviews preparedness for containing and controlling emerging and re-emerging diseases drawing lessons from disease events that occurred in animal and human populations in the last five decades (1961-2011). A comprehensive analysis based on retrieval and analysis of grey and published literature as well as reported cases was carried out to document type and trend of occurrence of emerging and re-emerging infectious diseases in different parts of Tanzania. Overall, the majority of diseases reported in the country were viral in nature followed by bacterial diseases. The trend for the occurrence shows a number of new emerging diseases as well as re-occurrence of old diseases in both animal (domestic and wild) and human populations. In humans, the major disease epidemics reported in the last five decades include cholera, influenza A H1N1, plague and rubella. In animals, the major epidemic diseases reported were Contagious Bovine Pleuropneumonia, Contagious Caprine Pleuropneumonia, Peste des petits ruminants and Giraffe Ear and Skin Diseases. Some epidemics have been reported in both human and animal populations including Rift Valley fever and anthrax. The emergence of the 'fit-for purpose' approaches and technologies such as the discipline of One Health, use of participatory epidemiology and disease surveillance and mobile technologies offers opportunity for optimal use of limited resources to improve early detection, diagnosis and response to disease events and consequently reduced impact of such diseases in animal and human populations.

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

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

International Nuclear Information System (INIS)

Yang, Han-Xin; Wu, Zhi-Xi

2014-01-01

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 an 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 exist 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. (paper)

Canine distemper virus infection among wildlife before and after the epidemic.

Science.gov (United States)

Suzuki, Junko; Nishio, Yohei; Kameo, Yuki; Terada, Yutaka; Kuwata, Ryusei; Shimoda, Hiroshi; Suzuki, Kazuo; Maeda, Ken

2015-11-01

In 2007-2008, a canine distemper virus (CDV) epidemic occurred among wild animals in Wakayama Prefecture, Japan, and many mammals, including the wild boar and deer, were infected. In this study, CDV prevalence among wild animals was surveyed before and after the epidemic. At first, an enzyme-linked immunosorbent assay (ELISA) with horseradish peroxidase-conjugated protein A/G was established to detect CDV antibodies in many mammalian species. This established ELISA was available for testing dogs, raccoons and raccoon dogs as well as virus-neutralization test. Next, a serological survey of wild mammalians was conducted, and it was indicated that many wild mammalians, particularly raccoons, were infected with CDV during the epidemic, but few were infected before and after the epidemic. On the other hand, many raccoon dogs died during the epidemic, but CDV remained prevalent in the remaining population, and a small epidemic occurred in raccoon dogs in 2012-2013. These results indicated that the epidemic of 2007-2008 may have been intensified by transmission to raccoons.

MOSES: A Matlab-based open-source stochastic epidemic simulator.

Science.gov (United States)

Varol, Huseyin Atakan

2016-08-01

This paper presents an open-source stochastic epidemic simulator. Discrete Time Markov Chain based simulator is implemented in Matlab. The simulator capable of simulating SEQIJR (susceptible, exposed, quarantined, infected, isolated and recovered) model can be reduced to simpler models by setting some of the parameters (transition probabilities) to zero. Similarly, it can be extended to more complicated models by editing the source code. It is designed to be used for testing different control algorithms to contain epidemics. The simulator is also designed to be compatible with a network based epidemic simulator and can be used in the network based scheme for the simulation of a node. Simulations show the capability of reproducing different epidemic model behaviors successfully in a computationally efficient manner.

[Infectious diseases].

Science.gov (United States)

Chapuis-Taillard, Caroline; de Vallière, Serge; Bochud, Pierre-Yves

2009-01-07

In 2008, several publications have highlighted the role of climate change and globalization on the epidemiology of infectious diseases. Studies have shown the extension towards Europe of diseases such as Crimea-Congo fever (Kosovo, Turkey and Bulgaria), leismaniosis (Cyprus) and chikungunya virus infection (Italy). The article also contains comments on Plasmodium knowlesi, a newly identified cause of severe malaria in humans, as well as an update on human transmission of the H5NI avian influenza virus. It also mentions new data on Bell's palsy as well as two vaccines (varicella-zoster and pneumococcus), and provides a list of recent guidelines for the treatment of common infectious diseases.

Epidemic spreading through direct and indirect interactions.

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Ganguly, Niloy; Krueger, Tyll; Mukherjee, Animesh; Saha, Sudipta

2014-09-01

In this paper we study the susceptible-infected-susceptible epidemic dynamics, considering a specialized setting where popular places (termed passive entities) are visited by agents (termed active entities). We consider two types of spreading dynamics: direct spreading, where the active entities infect each other while visiting the passive entities, and indirect spreading, where the passive entities act as carriers and the infection is spread via them. We investigate in particular the effect of selection strategy, i.e., the way passive entities are chosen, in the spread of epidemics. We introduce a mathematical framework to study the effect of an arbitrary selection strategy and derive formulas for prevalence, extinction probabilities, and epidemic thresholds for both indirect and direct spreading. We also obtain a very simple relationship between the extinction probability and the prevalence. We pay special attention to preferential selection and derive exact formulas. The analysis reveals that an increase in the diversity in the selection process lowers the epidemic thresholds. Comparing the direct and indirect spreading, we identify regions in the parameter space where the prevalence of the indirect spreading is higher than the direct one.

The fastest spreader in SIS epidemics on networks

NARCIS (Netherlands)

He, Z.; Van Mieghem, P.F.A.

2018-01-01

Identifying the fastest spreaders in epidemics on a network helps to ensure an efficient spreading. By ranking the average spreading time for different spreaders, we show that the fastest spreader may change with the effective infection rate of a SIS epidemic process, which means that the

Burden of infectious diseases, substance use disorders, and mental illness among Ukrainian prisoners transitioning to the community.

Directory of Open Access Journals (Sweden)

Lyuba Azbel

Full Text Available The epidemics of incarceration, substance use disorders (SUDs, and infectious diseases are inextricably intertwined, especially in the Former Soviet Union (FSU. Few objective data documenting this relationship regionally are available. We therefore conducted a comprehensive, representative country-wide prison health survey in Ukraine, where one of the world's most volatile HIV epidemics persists, in order to address HIV prevention and treatment needs.A nation-wide, multi-site randomly sampled biobehavioral health survey was conducted in four Ukrainian regions in 13 prisons among individuals being released within six months. After consent, participants underwent standardized health assessment surveys and serological testing for HIV, viral hepatitis, and syphilis.Of the 402 participants (mean age = 31.9 years, 20.1% were female. Prevalence of HIV, HCV, HBV, and syphilis was 19.4% (95% CI = 15.5%-23.3%, 60.2% (95% CI = 55.1%-65.4%, 5.2% (95% CI = 3.3%-7.2%, and 10% (95% CI = 7.4%-13.2%, respectively, with regional differences observed; HIV prevalence in the south was 28.6%. Among the 78 HIV-infected inmates, 50.7% were unaware of their HIV status and 44 (56.4% had CD4<350 cells/mL, of which only five (11% antiretroviral-eligible inmates were receiving it. Nearly half of the participants (48.7% reported pre-incarcertion drug injection, primarily of opioids, yet multiple substance use (31.6% and alcohol use disorders (56.6% were common and 40.3% met screening criteria for depression.This is the only such representative health study of prisoners in the FSU. This study has important implications for regional prevention and treatment because, unlike elsewhere, there is no recent evidence for reduction in HIV incidence and mortality in the region. The prevalence of infectious diseases and SUDs is high among this sample of prisoners transitioning to the community. It is critical to address pre- and post-release prevention and treatment needs with the

Infectious disease control in the Ionian Islands during the British Protection (1815-1864).

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Tsiamis, Costas; Thalassinou, E; Poulakou-Rebelakou, E; Anogiatis-Pelé, D; Hatzakis, A

2013-09-01

This review presents the medical and social role of British military doctors in the formation of the British sanitary campaign in the Ionian Islands during the period 1815-1864. They were the core of a health system based on the old sanitary model of the Venetian Republic, which was the former ruler of the region. The British innovation and reorganisation of the old lazarettos (a quarantine system for maritime travellers), the new marine sanitary procedures, the determination of quarantine duration for major infectious diseases along with the introduction of the vaccination system resulted in a satisfactory defence against epidemics in Greece during the 19th century. The British military physicians applied and established West European medical ideas, as well as the principles of preventive medicine, for the first time in the Greek territory and this is a historical example of a successful sanitary campaign based on the experience of military physicians and their collaboration with civilian physicians.

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 pe...... assigninglower repair times among the network nodes. They believe that the event-driven simulation model can be highly beneficialfor network providers, since it could be used during the network planning process for facilitating cost-effective networksurvivability design.......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...... performance improvement via differentiated repair times. First, theyidentify the most vulnerable and the most strategic nodes in the network. Then, via extensive event-driven simulations theyshow that strategic placement of resources for improved failure recovery has better performance than randomly...

Topology dependent epidemic spreading velocity in weighted networks

International Nuclear Information System (INIS)

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

2014-01-01

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. (paper)

Re-emergence of cholera in the Americas: Risks, susceptibility, and ecology

Directory of Open Access Journals (Sweden)

Mathieu JP Poirier

2012-01-01

Full Text Available Background: The re-emergence of cholera in Haiti has established a new reservoir for the seventh cholera pandemic which threatens to spread to other countries in the Americas. Materials and Methods: Statistics from this new epidemic are compared to the 1991 Peru epidemic, which demonstrated the speed and complexity with which this disease can spread from country to country. Environmental factors implicated in the spread of Vibrio cholerae such as ocean currents and temperatures, as well as biotic factors from zooplankton to waterfowl pose a risk for many countries in the Americas. Results: The movement of people and goods from Hispaniola are mostly destined for North America, but occur to some degree throughout the Americas. These modes of transmission, and the probability of uncontrolled community spread beyond Hispaniola, however, are completely dependent upon risk factors within these countries such as water quality and availability of sanitation. Although North America has excellent coverage of these deterrents to the spread of infectious gastrointestinal diseases, many countries throughout Latin America and the Caribbean lack these basic services and infrastructures. Conclusions : In order to curb the immediate spread of cholera in Hispaniola, treatment availability should be expanded to all parts of the island and phase II epidemic management initiatives must be developed.

National Infectious Diseases Surveillance data of South Korea.

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