WorldWideScience

Sample records for hypothetical disease epidemics

  1. The Impact of Resources for Clinical Surveillance on the Control of a Hypothetical Foot-and-Mouth Disease Epidemic in Denmark

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Boklund, Anette

    2014-01-01

    The objectives of this study were to assess whether current surveillance capacity is sufficient to fulfill EU and Danish regulations to control a hypothetical foot-and-mouth disease (FMD) epidemic in Denmark, and whether enlarging the protection and/or surveillance zones could minimize economic...... losses. The stochastic spatial simulation model DTU-DADS was further developed to simulate clinical surveillance of herds within the protection and surveillance zones and used to model spread of FMD between herds. A queuing system was included in the model, and based on daily surveillance capacity, which...... resources for surveillance did not improve the situation, but fewer resources could result in larger epidemics and costs. Enlarging the protection zone was a better strategy than the basic scenario. Despite that enlarging the surveillance zone might result in shorter epidemic duration, and lower number...

  2. [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.

  3. Impact of clinical surveillance during a foot-and-mouth disease epidemic

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Boklund, Anette

    duration, number of infected herds and the economic losses from an epidemic. The stochastic spatial simulation model DTU-DADS was enhanced to include simulation of surveillance of herds within the protection and surveillance zones and the model was used to model spread of FMD between herds. A queuing......The objectives of this study were to assess, whether the current surveillance capacity is sufficient to fulfill EU and Danish regulations to control a hypothetical foot-and-mouth disease (FMD) epidemic in Denmark, and whether enlarging the protection and/or surveillance zones could reduce epidemic...... showed that the default surveillance capacity is sufficient to survey herds within one week of the zones establishment, as the regulations demand. Extra resources for surveillance did not reduce the costs of the epidemics, but fewer resources could result in larger epidemics and costs. Furthermore...

  4. Spread of epidemic disease on networks

    Science.gov (United States)

    Newman, M. E.

    2002-07-01

    The study of social networks, and in particular the spread of disease on networks, has attracted considerable recent attention in the physics community. In this paper, we show that a large class of standard epidemiological models, the so-called susceptible/infective/removed (SIR) models can be solved exactly on a wide variety of networks. In addition to the standard but unrealistic case of fixed infectiveness time and fixed and uncorrelated probability of transmission between all pairs of individuals, we solve cases in which times and probabilities are nonuniform and correlated. We also consider one simple case of an epidemic in a structured population, that of a sexually transmitted disease in a population divided into men and women. We confirm the correctness of our exact solutions with numerical simulations of SIR epidemics on networks.

  5. Hypothetical views on some unusual disease associations with ...

    African Journals Online (AJOL)

    Sickle cell anemia (SCA) is a disease accompanied with several complications arising mainly from vasoocclusion and haemolysis. There are also complications of infections which may occur due to defective cell mediated and humoral immunity. However, there are associations that have been observed to be unusual in ...

  6. On The Travelling Wave Solution For An SEIR Epidemic Disease ...

    African Journals Online (AJOL)

    We present the travelling wave solution for a Susceptible, Exposed, Infective and Removed (SEIR) epidemic disease model. For this SEIR model, the disease is driven by both the latent and infective class (the diffusion term is included in both classes). The population is closed. Keywords: Epidemic model, spatial spread, ...

  7. 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

  8. Food system consequences of a fungal disease epidemic in a major crop.

    Science.gov (United States)

    Godfray, H Charles J; Mason-D'Croz, Daniel; Robinson, Sherman

    2016-12-05

    Fungal diseases are major threats to the most important crops upon which humanity depends. Were there to be a major epidemic that severely reduced yields, its effects would spread throughout the globalized food system. To explore these ramifications, we use a partial equilibrium economic model of the global food system (IMPACT) to study a hypothetical severe but short-lived epidemic that reduces rice yields in the countries affected by 80%. We modelled a succession of epidemic scenarios of increasing severity, starting with the disease in a single country in southeast Asia and ending with the pathogen present in most of eastern Asia. The epidemic and subsequent crop losses led to substantially increased global rice prices. However, as long as global commodity trade was unrestricted and able to respond fast enough, the effects on individual calorie consumption were, to a large part, mitigated. Some of the worse effects were projected to be experienced by poor net-rice importing countries in sub-Saharan Africa, which were not affected directly by the disease but suffered because of higher rice prices. We critique the assumptions of our models and explore political economic pressures to restrict trade at times of crisis. We finish by arguing for the importance of 'stress-testing' the resilience of the global food system to crop disease and other shocks.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Author(s).

  9. The hidden epidemic: confronting sexually transmitted diseases

    National Research Council Canada - National Science Library

    Eng, Thomas R; Butler, William T

    .... In addition, STDs increase the risk of HIV transmission. The Hidden Epidemic examines the scope of sexually transmitted infections in the United States and provides a critical assessment of the nation's response to this public health crisis...

  10. 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.

  11. Reiter′s Disease - Clinical Profile of Epidemic Form

    Directory of Open Access Journals (Sweden)

    H S Girgia

    1980-01-01

    Full Text Available Absence of urethritis need not exclude the possiblity of Reiter′s disease in young males where conjunctivitis and polyarthritis are cardinal features. Appearance of cutaneous lesion early in the course of the disease heralds a poor prognosis specially in the rare epidemic form of the disease. Two cases of Reiter′s disease are reported. Both belonged to the dysentric type of the disease; sometimes ref to as the epidemic form. Relatively high dose of steroids necessary to control symptoms.

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

    Science.gov (United States)

    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

  13. Predicting and controlling infectious disease epidemics using temporal networks

    OpenAIRE

    Masuda, Naoki; Holme, Petter

    2013-01-01

    Infectious diseases can be considered to spread over social networks of people or animals. Mainly owing to the development of data recording and analysis techniques, an increasing amount of social contact data with time stamps has been collected in the last decade. Such temporal data capture the dynamics of social networks on a timescale relevant to epidemic spreading and can potentially lead to better ways to analyze, forecast, and prevent epidemics. However, they also call for extended anal...

  14. 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...

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

    Directory of Open Access Journals (Sweden)

    Lyle Fearnley

    2010-12-01

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

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

    African Journals Online (AJOL)

    Obesity has become a worldwide epidemic, and its prevalence has been projected to grow by 40% in the next decade. This increasing prevalence has implications for the risk of diabetes, cardiovascular disease and also for Chronic Kidney Disease. A high body mass index is one of the strongest risk factors for new-onset ...

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

    OpenAIRE

    Lyle Fearnley

    2010-01-01

    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 o...

  18. Disease-induced resource constraints can trigger explosive epidemics

    Science.gov (United States)

    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.

  19. 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.

  20. Predicting Subnational Ebola Virus Disease Epidemic Dynamics from Sociodemographic Indicators.

    Directory of Open Access Journals (Sweden)

    Linda Valeri

    Full Text Available The recent Ebola virus disease (EVD outbreak in West Africa has spread wider than any previous human EVD epidemic. While individual-level risk factors that contribute to the spread of EVD have been studied, the population-level attributes of subnational regions associated with outbreak severity have not yet been considered.To investigate the area-level predictors of EVD dynamics, we integrated time series data on cumulative reported cases of EVD from the World Health Organization and covariate data from the Demographic and Health Surveys. We first estimated the early growth rates of epidemics in each second-level administrative district (ADM2 in Guinea, Sierra Leone and Liberia using exponential, logistic and polynomial growth models. We then evaluated how these growth rates, as well as epidemic size within ADM2s, were ecologically associated with several demographic and socio-economic characteristics of the ADM2, using bivariate correlations and multivariable regression models.The polynomial growth model appeared to best fit the ADM2 epidemic curves, displaying the lowest residual standard error. Each outcome was associated with various regional characteristics in bivariate models, however in stepwise multivariable models only mean education levels were consistently associated with a worse local epidemic.By combining two common methods-estimation of epidemic parameters using mathematical models, and estimation of associations using ecological regression models-we identified some factors predicting rapid and severe EVD epidemics in West African subnational regions. While care should be taken interpreting such results as anything more than correlational, we suggest that our approach of using data sources that were publicly available in advance of the epidemic or in real-time provides an analytic framework that may assist countries in understanding the dynamics of future outbreaks as they occur.

  1. Cardiovascular disease: A Global Epidemic extending into Sub ...

    African Journals Online (AJOL)

    Background: Cardiovascular disease is a global epidemic; the prevalence is currently stable in the developed world but is on a rapid rise in the developing world particularly in Sub-Saharan Africa. It is the commonest cause of morbidity and mortality globally. Its victims are older in the developed world but younger in Africa ...

  2. Overcrowding and disease epidemics in colonial Lagos: rethinking ...

    African Journals Online (AJOL)

    Thus, it degenerated to overcrowding and disease epidemics as epitomised by the outbreak of tuberculosis and bubonic plague in 1919 and between 1924 and 1930 respectively. The paper, therefore, concludes that with the available evidence at our disposal, it is obvious that the road and railway were constructed to ...

  3. Predicting and controlling infectious disease epidemics using temporal networks.

    Science.gov (United States)

    Masuda, Naoki; Holme, Petter

    2013-01-01

    Infectious diseases can be considered to spread over social networks of people or animals. Mainly owing to the development of data recording and analysis techniques, an increasing amount of social contact data with time stamps has been collected in the last decade. Such temporal data capture the dynamics of social networks on a timescale relevant to epidemic spreading and can potentially lead to better ways to analyze, forecast, and prevent epidemics. However, they also call for extended analysis tools for network epidemiology, which has, to date, mostly viewed networks as static entities. We review recent results of network epidemiology for such temporal network data and discuss future developments.

  4. The hidden epidemic: confronting sexually transmitted diseases

    National Research Council Canada - National Science Library

    Eng, Thomas R; Butler, William T

    ... of Sexually Transmitted Diseases INSTITUTE OF MEDICINE Division of Health Promotion and Disease Prevention NATIONAL ACADEMY PRESS Washington, D.C. 1997 Copyrightthe cannot be not from book, paper however, version for formatting, original authoritative the typesetting-specific the as from created publication files XML from other this ...

  5. Preventing the Epidemic of Non-Communicable Diseases: An Overview

    OpenAIRE

    Robson , Anthony ,

    2013-01-01

    International audience; Diet, lifestyle and environment do not just affect a person's health, they also determine the health of their children and possibly the health of their grandchildren. Non-communicable disease is a global epidemic because of the combined effect of the modern diet (including drug abuse) and a sedentary lifestyle. A low energy dense, drug-free diet rich in bioavailable nutrients-plus-exercise is most effective for preventing non-communicable disease throughout life. Nanoc...

  6. Numerical Analysis of Fractional Order Epidemic Model of Childhood Diseases

    Directory of Open Access Journals (Sweden)

    Fazal Haq

    2017-01-01

    Full Text Available The fractional order Susceptible-Infected-Recovered (SIR epidemic model of childhood disease is considered. Laplace–Adomian Decomposition Method is used to compute an approximate solution of the system of nonlinear fractional differential equations. We obtain the solutions of fractional differential equations in the form of infinite series. The series solution of the proposed model converges rapidly to its exact value. The obtained results are compared with the classical case.

  7. [Epidemics and diseases during the Independence period in Mexico].

    Science.gov (United States)

    Viesca-Treviño, Carlos

    2010-01-01

    The epidemics and endemic diseases in Mexico were not a problem before the Independence period. Hunger was less than in the past. The 1806 Influenza epidemics had been forgotten. Measles was considered a benign illness. In 1810, there was an increase in the number of cases of black vomit in Veracruz. Sixty percent of 541 hospitalized patients die of the disease. In 1812, an outbreak of yellow fever spread from Veracruz to Jalapa accompanying the movement of troops and killing over 300 soldiers of the Castilla's Battalion. The appearance of petechial fever, maybe typhus marketed in 1813 the onset of the most important epidemics. The preceding was the indirect effect of war: diseases of prisons and military quarters which became overwhelming in times where the movements of troops and of important groups of populations along with crowing, loss homes, hunger and bad hygiene habits. There was also Influenza or "pestilent cold." Measures of detection and quarantine were taken. "Naranjate" mixed with tartaric cremor was used against fever. Fumigation with nitric acid and burners, where they incinerated gun powder were among the health protection policies. It is noteworthy the advance and relief provided by the introduction of smallpox vaccine, the only preventive mean useful against smallpox which was a breakthrough in public health.

  8. The other epidemics. Sexually transmitted diseases.

    Science.gov (United States)

    Jacobson, J L

    1993-01-01

    Around 70% of female infertility in developing countries is caused by sexually transmitted diseases (STDs) that can be traced back to husbands or partners. STDs and reproductive tract infections cause 750,000 deaths and 75 million illnesses among women each year worldwide, and these deaths may more than double by the year 2000. Death rates are rising fastest in Africa, followed by Asia and Latin America. About 450,000 cases of potentially fatal reproductive tract cancers are diagnosed annually: an estimated 354,000 occur in Third World women, virtually all of whom die. Worldwide, roughly 250 million new infections of chlamydia, gonorrhea, and the human papillomavirus are sexually transmitted each year. Chlamydia and the human papillomavirus account for 50 million and 30 million new cases per year, respectively. The human immunodeficiency virus (HIV) infected 1 million people worldwide between April and December 1991, according to the World Health Organization. A study in the Indian state of Maharashtra revealed that 92% of the 650 rural women examined had an average of 3.6 infections of gynecological type or sexually transmitted type per women. Another study in 2 rural Egyptian villages found that half of 509 nonpregnant women aged 20 to 60 years had infections. Only 2 facilities for the diagnosis and treatment of STDs exist in all of Kenya. In Ibadan, Nigeria, with a population of 2 million, there is only 1 recognized STD clinic. The physical consequences of several STDs have been linked to increased risks of AIDS transmission. Early recognition and treatment of STDs in pregnant women would cut infant mortality. Maternal infections with chlamydia, gonorrhea, or herpes are transferred to infants at birth 25% to 50% of the time. In Africa, infant blindness caused by gonorrhea infection is 50 times more common than in industrial countries. The International Women's Health Coalition's March 1992 meeting of more than 50 Third World scientists, health advocates, and

  9. Optimal sampling strategies for detecting zoonotic disease epidemics.

    Directory of Open Access Journals (Sweden)

    Jake M Ferguson

    2014-06-01

    Full Text Available The early detection of disease epidemics reduces the chance of successful introductions into new locales, minimizes the number of infections, and reduces the financial impact. We develop a framework to determine the optimal sampling strategy for disease detection in zoonotic host-vector epidemiological systems when a disease goes from below detectable levels to an epidemic. We find that if the time of disease introduction is known then the optimal sampling strategy can switch abruptly between sampling only from the vector population to sampling only from the host population. We also construct time-independent optimal sampling strategies when conducting periodic sampling that can involve sampling both the host and the vector populations simultaneously. Both time-dependent and -independent solutions can be useful for sampling design, depending on whether the time of introduction of the disease is known or not. We illustrate the approach with West Nile virus, a globally-spreading zoonotic arbovirus. Though our analytical results are based on a linearization of the dynamical systems, the sampling rules appear robust over a wide range of parameter space when compared to nonlinear simulation models. Our results suggest some simple rules that can be used by practitioners when developing surveillance programs. These rules require knowledge of transition rates between epidemiological compartments, which population was initially infected, and of the cost per sample for serological tests.

  10. Optimal sampling strategies for detecting zoonotic disease epidemics.

    Science.gov (United States)

    Ferguson, Jake M; Langebrake, Jessica B; Cannataro, Vincent L; Garcia, Andres J; Hamman, Elizabeth A; Martcheva, Maia; Osenberg, Craig W

    2014-06-01

    The early detection of disease epidemics reduces the chance of successful introductions into new locales, minimizes the number of infections, and reduces the financial impact. We develop a framework to determine the optimal sampling strategy for disease detection in zoonotic host-vector epidemiological systems when a disease goes from below detectable levels to an epidemic. We find that if the time of disease introduction is known then the optimal sampling strategy can switch abruptly between sampling only from the vector population to sampling only from the host population. We also construct time-independent optimal sampling strategies when conducting periodic sampling that can involve sampling both the host and the vector populations simultaneously. Both time-dependent and -independent solutions can be useful for sampling design, depending on whether the time of introduction of the disease is known or not. We illustrate the approach with West Nile virus, a globally-spreading zoonotic arbovirus. Though our analytical results are based on a linearization of the dynamical systems, the sampling rules appear robust over a wide range of parameter space when compared to nonlinear simulation models. Our results suggest some simple rules that can be used by practitioners when developing surveillance programs. These rules require knowledge of transition rates between epidemiological compartments, which population was initially infected, and of the cost per sample for serological tests.

  11. Disease Extinction Versus Persistence in Discrete-Time Epidemic Models.

    Science.gov (United States)

    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].

  12. RABBIT POX : II. PATHOLOGY OF THE EPIDEMIC DISEASE.

    Science.gov (United States)

    Greene, H S

    1934-09-30

    The lesions found in animals with epidemic rabbit pox have been described in this paper. The most distinctive gross lesion in all organs and tissues was the small nodule or papule which was found to consist of mononuclear infiltration and necrosis. Diffuse lesions were also found in which the infiltration was widespread and accompanied by edema, hemorrhage and extensive necrosis of affected tissues and organs. The possibility of the diffuse lesions being due to the action of secondary invaders was considered, but available evidence indicated that the different types, including pneumonia, represented reactions to a single causative agent. Moreover, an intimate relationship was observed to exist between lesions and small blood vessels in which primary endothelial damage was usually apparent. The degree of vascular damage generally corresponded to the extent of the lesion and it is probable that this in turn corresponded to the dose of the causative agent. The close analogy between the clinical manifestations and pathological processes of this disease in the rabbit and small pox in man led to the conclusion that the disease in the rabbit is essentially the same as small pox, and that it is probably produced by a virus closely related to the virus of small pox. Available evidence indicated that the infection originated in the Institute and that it spread in atypical form or masked by some other disease until it reached the breeding colony as a clearly defined epidemic infection.

  13. Early cost-utility analysis of general and cerebrospinal fluid-specific Alzheimer's disease biomarkers for hypothetical disease-modifying treatment decision in mild cognitive impairment

    NARCIS (Netherlands)

    Handels, Ron L. H.; Joore, Manuela A.; Tran-Duy, An; Wimo, Anders; Wolfs, Claire A. G.; Verhey, Frans R. J.; Severens, Johan L.

    Introduction: The study aimed to determine the room for improvement of a perfect cerebrospinal fluid (CSF) biomarker and the societal incremental net monetary benefit of CSF in subjects with mild cognitive impairment (MCI) assuming a hypothetical disease-modifying Alzheimer's disease (AD) treatment.

  14. A final size relation for epidemic models of vector-transmitted diseases

    OpenAIRE

    Fred Brauer

    2017-01-01

    We formulate and analyze an age of infection model for epidemics of diseases transmitted by a vector, including the possibility of direct transmission as well. We show how to determine a basic reproduction number. While there is no explicit final size relation as for diseases transmitted directly, we are able to obtain estimates for the final size of the epidemic.

  15. Some models for epidemics of vector-transmitted diseases

    Directory of Open Access Journals (Sweden)

    Fred Brauer

    2016-10-01

    Full Text Available Vector-transmitted diseases such as dengue fever and chikungunya have been spreading rapidly in many parts of the world. The Zika virus has been known since 1947 and invaded South America in 2013. It can be transmitted not only by (mosquito vectors but also directly through sexual contact. Zika has developed into a serious global health problem because, while most cases are asymptomatic or very light, babies born to Zika - infected mothers may develop microcephaly and other very serious birth defects.We formulate and analyze two epidemic models for vector-transmitted diseases, one appropriate for dengue and chikungunya fever outbreaks and one that includes direct transmission appropriate for Zika virus outbreaks. This is especially important because the Zika virus is the first example of a disease that can be spread both indirectly through a vector and directly (through sexual contact. In both cases, we obtain expressions for the basic reproduction number and show how to use the initial exponential growth rate to estimate the basic reproduction number. However, for the model that includes direct transmission some additional data would be needed to identify the fraction of cases transmitted directly. Data for the 2015 Zika virus outbreak in Barranquilla, Colombia has been used to fit parameters to the model developed here and to estimate the basic reproduction number.

  16. Feeder density enhances house finch disease transmission in experimental epidemics.

    Science.gov (United States)

    Moyers, Sahnzi C; Adelman, James S; Farine, Damien R; Thomason, Courtney A; Hawley, Dana M

    2018-05-05

    Anthropogenic food provisioning of wildlife can alter the frequency of contacts among hosts and between hosts and environmental sources of pathogens. Despite the popularity of garden bird feeding, few studies have addressed how feeders influence host contact rates and disease dynamics. We experimentally manipulated feeder density in replicate aviaries containing captive, pathogen-naive, groups of house finches ( Haemorhous mexicanus ) and continuously tracked behaviours at feeders using radio-frequency identification devices. We then inoculated one bird per group with Mycoplasma gallisepticum (Mg), a common bacterial pathogen for which feeders are fomites of transmission, and assessed effects of feeder density on house finch behaviour and pathogen transmission. We found that pathogen transmission was significantly higher in groups with the highest density of bird feeders, despite a significantly lower rate of intraspecific aggressive interactions relative to the low feeder density groups. Conversely, among naive group members that never showed signs of disease, we saw significantly higher concentrations of Mg-specific antibodies in low feeder density groups, suggesting that birds in low feeder density treatments had exposure to subclinical doses of Mg. We discuss ways in which the density of garden bird feeders could play an important role in mediating the intensity of Mg epidemics.This article is part of the theme issue 'Anthropogenic resource subsidies and host-parasite dynamics in wildlife'. © 2018 The Author(s).

  17. 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.

  18. Degree of host susceptibility in the initial disease outbreak influences subsequent epidemic spread

    Science.gov (United States)

    Severns, Paul M.; Estep, Laura K.; Sackett, Kathryn E.; Mundt, Christopher C.

    2014-01-01

    Summary Disease epidemics typically begin as an outbreak of a relatively small, spatially explicit population of infected individuals (focus), in which disease prevalence increases and rapidly spreads into the uninfected, at-risk population. Studies of epidemic spread typically address factors influencing disease spread through the at-risk population, but the initial outbreak may strongly influence spread of the subsequent epidemic.We initiated wheat stripe rust Puccinia striiformis f. sp. tritici epidemics to assess the influence of the focus on final disease prevalence when the degree of disease susceptibility differed between the at-risk and focus populations.When the focus/at-risk plantings consisted of partially genetic resistant and susceptible cultivars, final disease prevalence was statistically indistinguishable from epidemics produced by the focus cultivar in monoculture. In these experimental epidemics, disease prevalence was not influenced by the transition into an at-risk population that differed in disease susceptibility. Instead, the focus appeared to exert a dominant influence on the subsequent epidemic.Final disease prevalence was not consistently attributable to either the focus or the at-risk population when focus/at-risk populations were planted in a factorial set-up with a mixture (~28% susceptible and 72% resistant) and susceptible individuals. In these experimental epidemics, spatial heterogeneity in disease susceptibility within the at-risk population appeared to counter the dominant influence of the focus.Cessation of spore production from the focus (through fungicide/glyphosate application) after 1.3 generations of stripe rust spread did not reduce final disease prevalence, indicating that the focus influence on disease spread is established early in the epidemic.Synthesis and applications. Our experiments indicated that outbreak conditions can be highly influential on epidemic spread, even when disease resistance in the at-risk population

  19. Impact of delay on disease outbreak in a spatial epidemic model

    Science.gov (United States)

    Zhao, Xia-Xia; Wang, Jian-Zhong

    2015-04-01

    One of the central issues in studying epidemic spreading is the mechanism on disease outbreak. In this paper, we investigate the effects of time delay on disease outbreak in spatial epidemics based on a reaction-diffusion model. By mathematical analysis and numerical simulations, we show that when time delay is more than a critical value, the disease outbreaks. The obtained results show that the time delay is an important factor in the spread of the disease, which may provide new insights on disease control.

  20. Dental X-ray exposure and Alzheimer's disease: a hypothetical etiological association.

    Science.gov (United States)

    Rodgers, Caroline C

    2011-07-01

    Despite the fact that Alzheimer's disease was identified more than 100 years ago, its cause remains elusive. Although the chance of developing Alzheimer's disease increases with age, it is not a natural consequence of aging. This article proposes that dental X-rays can damage microglia telomeres - the structures at the end of chromosomes that determine how many times cells divide before they die - causing them to age prematurely. Degenerated microglia lose their neuroprotective properties, resulting in the formation of neurofibrillary tau tangles and consequently, the neuronal death that causes Alzheimer's dementia. The hypothesis that Alzheimer's is caused specifically by microglia telomere damage would explain the delay of one decade or longer between the presence of Alzheimer's brain pathology and symptoms; telomere damage would not cause any change in microglial function, it would just reset the countdown clock so that senescence and apoptosis occurred earlier than they would have without the environmental insult. Once microglia telomere damage causes premature aging and death, the adjacent neurons are deprived of the physical support, maintenance and nourishment they require to survive. This sequence of events would explain why therapies and vaccines that eliminate amyloid plaques have been unsuccessful in stopping dementia. Regardless of whether clearing plaques is beneficial or harmful - which remains a subject of debate - it does not address the failing microglia population. If microglia telomere damage is causing Alzheimer's disease, self-donated bone marrow or dental pulp stem cell transplants could give rise to new microglia populations that would maintain neuronal health while the original resident microglia population died. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  2. A chaotic model for the epidemic of Ebola virus disease in West Africa (2013-2016)

    Science.gov (United States)

    Mangiarotti, Sylvain; Peyre, Marisa; Huc, Mireille

    2016-11-01

    An epidemic of Ebola Virus Disease (EVD) broke out in Guinea in December 2013. It was only identified in March 2014 while it had already spread out in Liberia and Sierra Leone. The spill over of the disease became uncontrollable and the epidemic could not be stopped before 2016. The time evolution of this epidemic is revisited here with the global modeling technique which was designed to obtain the deterministic models from single time series. A generalized formulation of this technique for multivariate time series is introduced. It is applied to the epidemic of EVD in West Africa focusing on the period between March 2014 and January 2015, that is, before any detected signs of weakening. Data gathered by the World Health Organization, based on the official publications of the Ministries of Health of the three main countries involved in this epidemic, are considered in our analysis. Two observed time series are used: the daily numbers of infections and deaths. A four-dimensional model producing a very complex dynamical behavior is obtained. The model is tested in order to investigate its skills and drawbacks. Our global analysis clearly helps to distinguish three main stages during the epidemic. A characterization of the obtained attractor is also performed. In particular, the topology of the chaotic attractor is analyzed and a skeleton is obtained for its structure.

  3. Influence of infection rate and migration on extinction of disease in spatial epidemics

    NARCIS (Netherlands)

    Sun, G.Q.; Liu, Q.X.; Jin, Z.; Chakraborty, A.; Li, B.L.

    2010-01-01

    Extinction of disease can be explained by the patterns of epidemic spreading, yet the underlying causes of extinction are far from being well understood. To reveal a mechanism of disease extinction, a cellular automata model with both birth, death rate and migration is presented. We find that, in

  4. Protection motivation theory and social distancing behaviour in response to a simulated infectious disease epidemic.

    Science.gov (United States)

    Williams, Lynn; Rasmussen, Susan; Kleczkowski, Adam; Maharaj, Savi; Cairns, Nicole

    2015-01-01

    Epidemics of respiratory infectious disease remain one of the most serious health risks facing the population. Non-pharmaceutical interventions (e.g. hand-washing or wearing face masks) can have a significant impact on the course of an infectious disease epidemic. The current study investigated whether protection motivation theory (PMT) is a useful framework for understanding social distancing behaviour (i.e. the tendency to reduce social contacts) in response to a simulated infectious disease epidemic. There were 230 participants (109 males, 121 females, mean age 32.4 years) from the general population who completed self-report measures assessing the components of PMT. In addition, participants completed a computer game which simulated an infectious disease epidemic in order to provide a measure of social distancing behaviour. The regression analyses revealed that none of the PMT variables were significant predictors of social distancing behaviour during the simulation task. However, fear (β = .218, p < .001), response efficacy (β = .175, p < .01) and self-efficacy (β = .251, p < .001) were all significant predictors of intention to engage in social distancing behaviour. Overall, the PMT variables (and demographic factors) explain 21.2% of the variance in intention. The findings demonstrated that PMT was a useful framework for understanding intention to engage in social distancing behaviour, but not actual behaviour during the simulated epidemic. These findings may reflect an intention-behaviour gap in relation to social distancing behaviour.

  5. Gender and leadership for health literacy to combat the epidemic rise of noncommunicable diseases.

    Science.gov (United States)

    Manhanzva, Rufaro; Marara, Praise; Duxbury, Theodore; Bobbins, Amy Claire; Pearse, Noel; Hoel, Erik; Mzizi, Thandi; Srinivas, Sunitha C

    2017-08-01

    Until recently, the noncommunicable diseases (NCDs) epidemic has been considered only a significant burden to men in high-income countries. However, latest figures indicate that half of all NCD-related deaths affect women, especially in low- and middle-income countries (LMICs), with global responses to the NCD epidemic overlooking the significance of women and girls in their approaches and programs. This case study highlights the burden of disease challenging South Africa that disproportionately affects women in the country and suggests that the country, along with other LMICs internationally, requires a shift in the gender-based leadership of health literacy and self-empowerment.

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

    Science.gov (United States)

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

    2013-01-01

    We report the results of a study we conducted using a simple multiplayer online game that simulates the spread of an infectious disease through a population composed of the players. We use our virtual epidemics game to examine how people respond to epidemics. The analysis shows that people's behavior is responsive to the cost of self-protection, the reported prevalence of disease, and their experiences earlier in the epidemic. Specifically, decreasing the cost of self-protection increases the rate of safe behavior. Higher reported prevalence also raises the likelihood that individuals would engage in self-protection, where the magnitude of this effect depends on how much time has elapsed in the epidemic. Individuals' experiences in terms of how often an infection was acquired when they did not engage in self-protection are another factor that determines whether they will invest in preventive measures later on. All else being equal, individuals who were infected at a higher rate are more likely to engage in self-protective behavior compared to those with a lower rate of infection. Lastly, fixing everything else, people's willingness to engage in safe behavior waxes or wanes over time, depending on the severity of an epidemic: when prevalence is high, people are more likely to adopt self-protective measures as time goes by; when prevalence is low, a ‘self-protection fatigue’ effect sets in whereby individuals are less willing to engage in safe behavior over time. PMID:23326360

  7. Estimating the spatial distribution of a plant disease epidemic from a sample

    Science.gov (United States)

    Sampling is of central importance in plant pathology. It facilitates our understanding of how epidemics develop in space and time and can also be used to inform disease management decisions. Making inferences from a sample is necessary because we rarely have the resources to conduct a complete censu...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    African Journals Online (AJOL)

    factors for Chronic Kidney Disease (CKD), like diabetes and hypertension, and it ... Epidemiology of obesity in adults and children. Over the last 3 .... Table 1. Studies examining the association of obesity with various measures of CKD. Study.

  10. Communicating risk and promoting disease mitigation measures in epidemics and emerging disease settings.

    Science.gov (United States)

    Schiavo, Renata; May Leung, May; Brown, Mason

    2014-03-01

    This review aims to identify and assess evidence on interventions to communicate risk and promote disease mitigation measures in epidemics and emerging disease outbreak settings. The study focuses on data that are relevant to low and middle-income country (LMIC) settings. We conducted a comprehensive literature search using five major electronic databases (Pubmed Medline, Biomed Central, EMBASE, Science of Citation Index, and Cochrane Library) and other sources to identify relevant studies published from January 2002 to July 2013. The review was guided by the socio-ecological model/perspective of public health and the ideation theory and focused on interventions at the community, healthcare, and multi-sectoral settings, which also reflect key intervention levels of the Ottawa Charter for Health Promotion. Eligible quantitative studies were selected according to specific study criteria and assessed using the Critical Appraisal Skills Program (CASP) framework. Conversely, qualitative studies, reviews, case studies, and editorials were not included. Studies were selected by two independent reviewers. Twenty-nine relevant studies from 16 countries were included. Most studies focused on a single intervention or intervention level, rather than multi-sectoral interventions. The majority of the evidence relates to programs aimed at behavioral and social results (or relevant intermediate steps) within a specific population group. Two studies included implications for improvements in health service delivery, two studies examined the intervention's impact on health systems-related outcomes, and three had also implications for environmental health outcomes. Cost- and health equity-related implications for select evidence were also discussed. The paucity of well-designed quantitative evaluations of interventions to communicate health risk and promote disease control measures in LMICs does not allow for any definitive conclusions. Yet, the review identified several promising

  11. The link between the epidemics of obesity and allergic diseases

    DEFF Research Database (Denmark)

    Hersoug, Lars-Georg; Linneberg, A

    2007-01-01

    There is increasing epidemiological evidence that obesity increases the risk of asthma, atopic, and autoimmune diseases. We hypothesize that the increase in these diseases is caused, at least in part, by decreased immunological tolerance as a consequence of immunological changes induced by adipok......There is increasing epidemiological evidence that obesity increases the risk of asthma, atopic, and autoimmune diseases. We hypothesize that the increase in these diseases is caused, at least in part, by decreased immunological tolerance as a consequence of immunological changes induced......-lymphocytes (Tregs). Additionally, adiponectin, which decreases with increasing obesity, down-regulates the secretion of IL10 from macrophages and adipocytes. These changes in IL6, leptin, and IL10 decrease the regulatory effect of Tregs resulting in decreased immunological tolerance to antigens. In pregnant women......, these obesity-induced immunological changes might be transmitted to the fetus by epigenetic inheritance thereby increasing the risk of atopic disease. We propose that obesity results in immunological changes resulting in decreased immunological tolerance to antigens and skewing of the immune system towards a Th...

  12. Political Economy of Epidemic Kidney Disease in Sri Lanka

    Directory of Open Access Journals (Sweden)

    Asoka Bandarage

    2013-10-01

    Full Text Available The Chronic Kidney Disease (CKD, taking the lives of thousands in poor farming communities in Sri Lanka, is commonly seen as a problem peculiar to the island’s north central dry zone agricultural region. The prevailing bio-medical focus is on identifying one or more “environmental nephrotoxins.” While delineating important controversies on the etiology of the disease, this article seeks to broaden the discourse on the hitherto neglected political economy of CKD in Sri Lanka. In so doing, it seeks to bring together the bio-medical debate on the impact of widespread and unregulated use of agrochemicals on public health and kidney disease with broader global interdisciplinary perspectives on the industrialization of agriculture and the consolidation of food production by transnational agribusiness corporations. The article concludes pointing out environmentally sustainable and socially equitable development and organic agriculture as the long-term solutions to CKD in Sri Lanka and elsewhere.

  13. Dynamics of a stochastic delayed SIR epidemic model with vaccination and double diseases driven by Lévy jumps

    Science.gov (United States)

    Liu, Qun; Jiang, Daqing; Shi, Ningzhong; Hayat, Tasawar

    2018-02-01

    In this paper, we study the dynamics of a stochastic delayed SIR epidemic model with vaccination and double diseases which make the research more complex. The environment variability in this paper is characterized by white noise and Lévy noise. We establish sufficient conditions for extinction and persistence in the mean of the two epidemic diseases. It is shown that: (i) time delay and Lévy noise have important effects on the persistence and extinction of epidemic diseases; (ii) two diseases can coexist under certain conditions.

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

    African Journals Online (AJOL)

    for chronic kidney disease (CKD), like diabetes and hypertension, and it has a direct impact .... meta-analysis, kidney cancers had the third highest risk associated with obesity (relative ..... Ellington AA, Malik AR, Klee GG, et al. Association of ...

  15. West Africa Ebola Virus Disease Epidemic: The Africa Experience ...

    African Journals Online (AJOL)

    Ebola Virus Disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe acute viral illness characterized by sudden onset of fever, myalgia, malaise, and severe headache, followed by vomiting and diarrhea and, in some instances, bleeding. The 2014 West Africa outbreak is the largest in history, affecting ...

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

    African Journals Online (AJOL)

    Obesity has also been shown to be a risk factor for nephrolithiasis, and for a number of malignancies including kidney cancer. This year World Kidney Day promotes education on the harmful consequences of obesity and its association with kidney disease, advocating a healthy lifestyle and health policy measures that ...

  17. Nonalcoholic fatty liver disease: A comprehensive review of a growing epidemic

    Science.gov (United States)

    Hassan, Kareem; Bhalla, Varun; Ezz El Regal, Mohammed; A-Kader, H Hesham

    2014-01-01

    Nonalcoholic fatty liver disease (NAFLD) is quickly becoming one of the most prominent causes of liver disease worldwide. The increasing incidence of NAFLD is tied to the obesity epidemic and the subsequent metabolic derangements brought along with it. Current efforts to elucidate the mechanism and causes of the disease have answered some questions, but much remains unknown about NAFLD. The aim of this article is to discuss the current knowledge regarding the pathogenesis of the disease, as well as the current and future diagnostic, preventative, and therapeutic options available to clinicians for the management of NAFLD. PMID:25232245

  18. Some Models for Epidemics of Vector-Transmitted Diseases

    OpenAIRE

    Brauer, Fred; Castillo-Chavez, Carlos; Mubayi, Anuj; Towers, Sherry

    2016-01-01

    Vector-transmitted diseases such as dengue fever and chikungunya have been spreading rapidly in many parts of the world. The Zika virus has been known since 1947 and invaded South America in 2013. It can be transmitted not only by (mosquito) vectors but also directly through sexual contact. Zika has developed into a serious global health problem because, while most cases are asymptomatic or very light, babies born to Zika - infected mothers may develop microcephaly and other very serious birt...

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

    Directory of Open Access Journals (Sweden)

    Carlos Polanco

    2013-01-01

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

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

    Science.gov (United States)

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

    2013-01-01

    A severe respiratory disease epidemic outbreak correlates with a high demand of specific supplies and specialized personnel to hold it back in a wide region or set of regions; these supplies would be beds, storage areas, hemodynamic monitors, and mechanical ventilators, as well as physicians, respiratory technicians, and specialized nurses. We describe an online cumulative sum based model named Overcrowd-Severe-Respiratory-Disease-Index based on the Modified Overcrowd Index that simultaneously monitors and informs the demand of those supplies and personnel in a healthcare network generating early warnings of severe respiratory disease epidemic outbreaks through the interpretation of such variables. A post hoc historical archive is generated, helping physicians in charge to improve the transit and future allocation of supplies in the entire hospital network during the outbreak. The model was thoroughly verified in a virtual scenario, generating multiple epidemic outbreaks in a 6-year span for a 13-hospital network. When it was superimposed over the H1N1 influenza outbreak census (2008–2010) taken by the National Institute of Medical Sciences and Nutrition Salvador Zubiran in Mexico City, it showed that it is an effective algorithm to notify early warnings of severe respiratory disease epidemic outbreaks with a minimal rate of false alerts. PMID:24069063

  1. Two profitless delays for an SEIRS epidemic disease model with vertical transmission and pulse vaccination

    International Nuclear Information System (INIS)

    Meng Xinzhu; Jiao Jianjun; Chen Lansun

    2009-01-01

    Since the investigation of impulsive delay differential equations is beginning, the literature on delay epidemic models with pulse vaccination is not extensive. In this paper, we propose a new SEIRS epidemic disease model with two profitless delays and vertical transmission, and analyze the dynamics behaviors of the model under pulse vaccination. Using the discrete dynamical system determined by the stroboscopic map, we obtain a 'infection-free' periodic solution, further, show that the 'infection-free' periodic solution is globally attractive when some parameters of the model are under appropriate conditions. Using a new modeling method, we obtain sufficient condition for the permanence of the epidemic model with pulse vaccination. We show that time delays, pulse vaccination and vertical transmission can bring different effects on the dynamics behaviors of the model by numerical analysis. Our results also show the delays are 'profitless'. In this paper, the main feature is to introduce two discrete time delays, vertical transmission and impulse into SEIRS epidemic model and to give pulse vaccination strategies.

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

    Science.gov (United States)

    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.

  3. Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama

    OpenAIRE

    Crawford, Andrew J.; Lips, Karen R.; Bermingham, Eldredge

    2010-01-01

    Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytrium dendrobatidis. Despite the severity of the crisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing...

  4. Disease epidemics: Lessons for resilience in an increasingly connected world

    Science.gov (United States)

    Allen, Craig R.; DeWitte, S.N.; Kurth, M.H.; Linkov, I.

    2016-01-01

    In public health, the term resilience often refers to the personality traits that individuals possess which help them endure and recover from stressors. However, resilience as a system characteristic, especially in regards to complex social-ecological systems, can be informative for public health at scales larger than the individual. Acute shocks to systems occur against a background of existing conditions, which are crucial determinants of the eventual public health outcomes of those shocks, and in the context of complex dependencies among and between ecological and societal elements. Many components of a system's baseline condition are chronic public health concerns themselves and diminish the capacity of the system to perform in the face of acute shocks. The emerging field of resilience management is concerned with holistically assessing and improving a system's ability to prepare for and absorb disruption, and then recover and adapt across physical, information, environmental and social domains. Integrating resilience considerations into current risk- and evidence-based approaches to disease control and prevention1 can move public health efforts toward more proactive and comprehensive solutions for protecting and improving the health of communities. Here, we look to the case of the Black Death as an illustrative case of a dramatic transformation in human history, an acute shock to a system that was underlain by chronic social maladies, to derive lessons about resilience management for public health in contemporary systems.

  5. Epidemicity thresholds for water-borne and water-related diseases.

    Science.gov (United States)

    Mari, Lorenzo; Casagrandi, Renato; Rinaldo, Andrea; Gatto, Marino

    2018-06-14

    Determining the conditions that favor pathogen establishment in a host community is key to disease control and eradication. However, focusing on long-term dynamics alone may lead to an underestimation of the threats imposed by outbreaks triggered by short-term transient phenomena. Achieving an effective epidemiological response thus requires to look at different timescales, each of which may be endowed with specific management objectives. In this work we aim to determine epidemicity thresholds for some prototypical examples of water-borne and water-related diseases, a diverse family of infections transmitted either directly through water infested with pathogens or by vectors whose lifecycles are closely associated with water. From a technical perspective, while conditions for endemicity are determined via stability analysis, epidemicity thresholds are defined through generalized reactivity analysis, a recently proposed method that allows the study of the short-term instability properties of ecological systems. Understanding the drivers of water-borne and water-related disease dynamics over timescales that may be relevant to epidemic and/or endemic transmission is a challenge of the utmost importance, as large portions of the developing world are still struggling with the burden imposed by these infections. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Alzheimer Disease and Its Growing Epidemic: Risk Factors, Biomarkers, and the Urgent Need for Therapeutics.

    Science.gov (United States)

    Hickman, Richard A; Faustin, Arline; Wisniewski, Thomas

    2016-11-01

    Alzheimer disease (AD) represents one of the greatest medical challenges of this century; the condition is becoming increasingly prevalent worldwide and no effective treatments have been developed for this terminal disease. Because the disease manifests at a late stage after a long period of clinically silent neurodegeneration, knowledge of the modifiable risk factors and the implementation of biomarkers is crucial in the primary prevention of the disease and presymptomatic detection of AD, respectively. This article discusses the growing epidemic of AD and antecedent risk factors in the disease process. Disease biomarkers are discussed, and the implications that this may have for the treatment of this currently incurable disease. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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

  8. Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama.

    Science.gov (United States)

    Crawford, Andrew J; Lips, Karen R; Bermingham, Eldredge

    2010-08-03

    Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytrium dendrobatidis. Despite the severity of the crisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing changes in abundance and evolutionary diversity within the amphibian community of El Copé, Panama, following a disease epidemic and mass-mortality event. The epidemic reduced taxonomic, lineage, and phylogenetic diversity similarly. We discovered that 30 species were lost, including five undescribed species, representing 41% of total amphibian lineage diversity in El Copé. These extirpations represented 33% of the evolutionary history of amphibians within the community, and variation in the degree of population loss and decline among species was random with respect to the community phylogeny. Our approach provides a fast, economical, and informative analysis of loss in a community whether measured by species or phylogenetic diversity.

  9. Spatial statistical analysis of basal stem root disease under natural field epidemic of oil palm

    Science.gov (United States)

    Kamu, Assis; Phin, Chong Khim; Seman, Idris Abu; Wan, Hoong Hak; Mun, Ho Chong

    2015-02-01

    Oil palm or scientifically known as Elaeis guineensis Jacq. is the most important commodity crop in Malaysia and has greatly contributed to the economy growth of the country. As far as disease is concerned in the industry, Basal Stem Rot (BSR) caused by Ganoderma boninence remains the most important disease. BSR disease is the most widely studied with information available for oil palm disease in Malaysia. However, there is still limited study on the spatial as well as temporal pattern or distribution of the disease especially under natural field epidemic condition in oil palm plantation. The objective of this study is to spatially identify the pattern of BSR disease under natural field epidemic using two geospatial analytical techniques, which are quadrat analysis for the first order properties of partial pattern analysis and nearest-neighbor analysis (NNA) for the second order properties of partial pattern analysis. Two study sites were selected with different age of tree. Both sites are located in Tawau, Sabah and managed by the same company. The results showed that at least one of the point pattern analysis used which is NNA (i.e. the second order properties of partial pattern analysis) has confirmed the disease is complete spatial randomness. This suggests the spread of the disease is not from tree to tree and the age of palm does not play a significance role in determining the spatial pattern of the disease. From the spatial pattern of the disease, it would help in the disease management program and for the industry in the future. The statistical modelling is expected to help in identifying the right model to estimate the yield loss of oil palm due to BSR disease in the future.

  10. Intercontinental spread of a genetically distinctive complex of clones of Neisseria meningitidis causing epidemic disease.

    Science.gov (United States)

    Caugant, D A; Frøholm, L O; Bøvre, K; Holten, E; Frasch, C E; Mocca, L F; Zollinger, W D; Selander, R K

    1986-07-01

    Strains of Neisseria meningitidis responsible for an epidemic of meningococcal disease occurring in Norway since the mid-1970s and for recent increases in the incidence of disease in several other parts of Europe have been identified by multilocus enzyme electrophoresis as members of a distinctive group of 22 closely related clones (the ET-5 complex). Clones of this complex have also colonized South Africa, Chile, Cuba, and Florida, where they have been identified as the causative agents of recent outbreaks of meningococcal disease. There is strong circumstantial evidence that outbreaks of disease occurring in Miami in 1981 and 1982 were caused in large part by bacteria that reached Florida via human immigrants from Cuba.

  11. Impact of interventions and the incidence of ebola virus disease in Liberia-implications for future epidemics.

    Science.gov (United States)

    Kirsch, Thomas D; Moseson, Heidi; Massaquoi, Moses; Nyenswah, Tolbert G; Goodermote, Rachel; Rodriguez-Barraquer, Isabel; Lessler, Justin; Cumings, Derek A T; Peters, David H

    2017-03-01

    To better understand the impact of national and global efforts to contain the Ebola virus disease epidemic of 2014–15 in Liberia, we provide a detailed timeline of the major interventions and relate them to the epidemic curve.  In addition to personal experience in the response, we systematically reviewed situation reports from the Liberian government, UN, CDC, WHO, UNICEF, IFRC, USAID, and local and international news reports to create the timeline. We extracted data on the timing and nature of activities and compared them to the timeline of the epidemic curve using the reproduction number—the estimate of the average number of new cases caused by a single case.  Interventions were organized around five major strategies, with the majority of resources directed to the creation of treatment beds. We conclude that no single intervention stopped the epidemic; rather, the interventions likely had reinforcing effects, and some were less likely than others to have made a major impact. We find that the epidemic’s turning coincided with a reorganization of the response in August–September 2014, the emergence of community leadership in control efforts, and changing beliefs and practices in the population. Ebola Treatment Units were important for Ebola treatment, but the vast majority of these treatment centre beds became available after the epidemic curve began declining. Similarly, the United Nations Mission for Ebola Emergency Response was launched after the epidemic curve had already turned.  These findings have significant policy implications for future epidemics and suggest that much of the decline in the epidemic curve was driven by critical behaviour changes within local communities, rather than by international efforts that came after the epidemic had turned. Future global interventions in epidemic response should focus on building community capabilities, strengthening local ownership, and dramatically reducing delays in the response.

  12. Summer epidemics of apple scab : The relationship between measurements and their implications for the development of predictive models and threshold levels under different disease control regimes

    NARCIS (Netherlands)

    Holb, I.J.; Heijne, B.; Jeger, M.J.

    2003-01-01

    A 2-year study on epidemic progress of apple scab was conducted at Randwijk, the Netherlands, in 1998 and 1999. The summer epidemic caused by conidia was studied instead of the well-described spring season epidemic originating from ascospores. The aim was to investigate relationships between disease

  13. Dynamical behavior of an epidemic model for a vector-borne disease with direct transmission

    International Nuclear Information System (INIS)

    Cai Liming; Li Xuezhi; Li Zhaoqiang

    2013-01-01

    An epidemic model of a vector-borne disease with direct transmission is investigated. The reproduction number (R 0 ) of the model is obtained. Rigorous qualitative analysis of the model reveals the presence of the phenomenon of backward bifurcation (where the stable disease-free equilibrium (DFE) coexists with a stable endemic equilibrium when the reproduction number of the disease is less than unity) in the standard incidence model. The phenomenon shows that the classical epidemiological requirement of having the reproduction number less than unity is no longer sufficient, although necessary, for effectively controlling the spread of some vector-borne diseases in a community. The backward bifurcation phenomenon can be removed by substituting the standard incidence with a bilinear mass action incidence. By using Lyapunov function theory and LaSalle invariance principle, it is shown that the unique endemic equilibrium for the model with a mass action incidence is globally stable if the reproduction number R mass is greater than one in feasible region. This suggests that the use of standard incidence in modelling some vector-borne diseases with direct transmission results in the presence of backward bifurcation. Numerical simulations analyze the effect of the direct transmission and the disease-induced death rate on dynamics of the disease transmission, and also verify our analyzed results.

  14. Stability and disease persistence in an age-structured SIS epidemic model with vertical transmission and proportionate mixing assumption

    International Nuclear Information System (INIS)

    El-Doma, M.

    2001-02-01

    The stability of the endemic equilibrium of an SIS age-structured epidemic model of a vertically as well as horizontally transmitted disease is investigated when the force of infection is of proportionate mixing assumption type. We also investigate the uniform weak disease persistence. (author)

  15. Epidemiology of Epidemic Ebola Virus Disease in Conakry and Surrounding Prefectures, Guinea, 2014–2015

    Science.gov (United States)

    Brody, Debra; Coronado, Fátima; Rondy, Marc; Fiebig, Lena; Carcelen, Andrea; Deyde, Varough M.; Mesfin, Samuel; Retzer, Kyla D.; Bilivogui, Pepe; Keita, Sakoba; Dahl, Benjamin A.

    2016-01-01

    In 2014, Ebola virus disease (EVD) in West Africa was first reported during March in 3 southeastern prefectures in Guinea; from there, the disease rapidly spread across West Africa. We describe the epidemiology of EVD cases reported in Guinea’s capital, Conakry, and 4 surrounding prefectures (Coyah, Dubreka, Forecariah, and Kindia), encompassing a full year of the epidemic. A total of 1,355 EVD cases, representing ≈40% of cases reported in Guinea, originated from these areas. Overall, Forecariah had the highest cumulative incidence (4× higher than that in Conakry). Case-fatality percentage ranged from 40% in Conakry to 60% in Kindia. Cumulative incidence was slightly higher among male than female residents, although incidences by prefecture and commune differed by sex. Over the course of the year, Conakry and neighboring prefectures became the EVD epicenter in Guinea. PMID:26812047

  16. Epidemiology of Epidemic Ebola Virus Disease in Conakry and Surrounding Prefectures, Guinea, 2014-2015.

    Science.gov (United States)

    Rico, Adriana; Brody, Debra; Coronado, Fátima; Rondy, Marc; Fiebig, Lena; Carcelen, Andrea; Deyde, Varough M; Mesfin, Samuel; Retzer, Kyla D; Bilivogui, Pepe; Keita, Sakoba; Dahl, Benjamin A

    2016-02-01

    In 2014, Ebola virus disease (EVD) in West Africa was first reported during March in 3 southeastern prefectures in Guinea; from there, the disease rapidly spread across West Africa. We describe the epidemiology of EVD cases reported in Guinea's capital, Conakry, and 4 surrounding prefectures (Coyah, Dubreka, Forecariah, and Kindia), encompassing a full year of the epidemic. A total of 1,355 EVD cases, representing ≈40% of cases reported in Guinea, originated from these areas. Overall, Forecariah had the highest cumulative incidence (4× higher than that in Conakry). Case-fatality percentage ranged from 40% in Conakry to 60% in Kindia. Cumulative incidence was slightly higher among male than female residents, although incidences by prefecture and commune differed by sex. Over the course of the year, Conakry and neighboring prefectures became the EVD epicenter in Guinea.

  17. [Chronic non-communicable diseases: a global epidemic of the 21st century].

    Science.gov (United States)

    Andersen, Karl; Gudnason, Vilmundur

    2012-11-01

    Chronic non-communicable diseases (NCDs) are the cause of 86% of all deaths in the EU and 65% of deaths worldwide. A third of these deaths occur before the age of sixty years. The NCDs affect 40% of the adult population of the EU and two thirds of the population reaching retirement age suffers from two or more NCDs. The NCDs are a global epidemic challenging economic growth in most countries. According to the WHO, NCDs are one of the major threats to worldwide social and economic development in the 21st century. The problem is of great concern to the international community and was discussed at a High level meeting at the UN General Assembly in September 2011. In this paper we review the epidemic of NCDs both from a national and international perspective. We discuss the causes and consequences. In a second review paper we reflect on the political health policy issues raised by the international community in order to respond to the problem. These issues will become a major challenge for social and economic development in most countries of the world in the coming decades.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Azañón's disease. A 19th century epidemic of neurolathyrism in Spain.

    Science.gov (United States)

    Giménez-Roldán, S; Spencer, P S

    2016-12-01

    The cultivation and consumption of grasspea (Lathyrus sativus) in Spain probably dates back centuries, especially during times of famine when the neurotoxic potential of this legume was expressed in the form of a spastic paraparesis known as neurolathyrism. Little known outside the country, the epidemic of neurolathyrism in the years following the Spanish Civil War (1936-1939) came to affect more than a thousand people. In late 1872, during the Six Years Revolutionary Term, young Alejandro San Martín Satrústegui (1847-1908), then editor of the popular weekly El Siglo Médico, travelled to Azañón, a remote village in the province of Guadalajara, to clarify a so-far unknown disease. We analysed the original article published in 1873 by San Martin, as well as communications sent by El Siglo Médico readers reporting similar cases in many other Castilian provinces. San Martín's neurological findings in seven personally examined cases were astonishingly accurate; he concluded the subjects' neurological deficits resulted from injury to the lateral columns in the lower portion of the spinal cord. Description of the clinical findings provided both by San Martín, and by the readers of El Siglo Médico, leave no doubt as to the diagnosis of neurolathyrism. However, none suspected the patient's staple food was the determinant cause of the disease. San Martín proposed the eponym Azañón's disease for lack of a better name the same year (1873) in which Cantani in Italy introduced the term lathyrism. The epidemic of neurolathyrism that affected many Castilian towns represents one of the best-documented in Europe during the last third of the 19th century. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Epidemic typhus.

    Science.gov (United States)

    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.

  1. Modeling sheep pox disease from the 1994-1998 epidemic in Evros Prefecture, Greece.

    Science.gov (United States)

    Malesios, C; Demiris, N; Abas, Z; Dadousis, K; Koutroumanidis, T

    2014-10-01

    Sheep pox is a highly transmissible disease which can cause serious loss of livestock and can therefore have major economic impact. We present data from sheep pox epidemics which occurred between 1994 and 1998. The data include weekly records of infected farms as well as a number of covariates. We implement Bayesian stochastic regression models which, in addition to various explanatory variables like seasonal and environmental/meteorological factors, also contain serial correlation structure based on variants of the Ornstein-Uhlenbeck process. We take a predictive view in model selection by utilizing deviance-based measures. The results indicate that seasonality and the number of infected farms are important predictors for sheep pox incidence. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

    Directory of Open Access Journals (Sweden)

    Clement N Mweya

    Full Text Available Rift Valley Fever (RVF is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics.Time-varying distributed delays (TVDD and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district.Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

  3. Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

    Science.gov (United States)

    Mweya, Clement N; Holst, Niels; Mboera, Leonard E G; Kimera, Sharadhuli I

    2014-01-01

    Rift Valley Fever (RVF) is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics. Time-varying distributed delays (TVDD) and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML) files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district. Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

  4. Porcine Epidemic Diarrhea in Europe: In-Detail Analyses of Disease Dynamics and Molecular Epidemiology.

    Science.gov (United States)

    Hanke, Dennis; Pohlmann, Anne; Sauter-Louis, Carola; Höper, Dirk; Stadler, Julia; Ritzmann, Mathias; Steinrigl, Adi; Schwarz, Bernd-Andreas; Akimkin, Valerij; Fux, Robert; Blome, Sandra; Beer, Martin

    2017-07-06

    Porcine epidemic diarrhea (PED) is an acute and highly contagious enteric disease of swine caused by the eponymous virus (PEDV) which belongs to the genus Alphacoronavirus within the Coronaviridae virus family. Following the disastrous outbreaks in Asia and the United States, PEDV has been detected also in Europe. In order to better understand the overall situation, the molecular epidemiology, and factors that might influence the most variable disease impact; 40 samples from swine feces were collected from different PED outbreaks in Germany and other European countries and sequenced by shot-gun next-generation sequencing. A total of 38 new PEDV complete coding sequences were generated. When compared on a global scale, all investigated sequences from Central and South-Eastern Europe formed a rather homogeneous PEDV S INDEL cluster, suggesting a recent re-introduction. However, in-detail analyses revealed two new clusters and putative ancestor strains. Based on the available background data, correlations between clusters and location, farm type or clinical presentation could not be established. Additionally, the impact of secondary infections was explored using the metagenomic data sets. While several coinfections were observed, no correlation was found with disease courses. However, in addition to the PEDV genomes, ten complete viral coding sequences from nine different data sets were reconstructed each representing new virus strains. In detail, three pasivirus A strains, two astroviruses, a porcine sapelovirus, a kobuvirus, a porcine torovirus, a posavirus, and an enterobacteria phage were almost fully sequenced.

  5. Porcine Epidemic Diarrhea in Europe: In-Detail Analyses of Disease Dynamics and Molecular Epidemiology

    Directory of Open Access Journals (Sweden)

    Dennis Hanke

    2017-07-01

    Full Text Available Porcine epidemic diarrhea (PED is an acute and highly contagious enteric disease of swine caused by the eponymous virus (PEDV which belongs to the genus Alphacoronavirus within the Coronaviridae virus family. Following the disastrous outbreaks in Asia and the United States, PEDV has been detected also in Europe. In order to better understand the overall situation, the molecular epidemiology, and factors that might influence the most variable disease impact; 40 samples from swine feces were collected from different PED outbreaks in Germany and other European countries and sequenced by shot-gun next-generation sequencing. A total of 38 new PEDV complete coding sequences were generated. When compared on a global scale, all investigated sequences from Central and South-Eastern Europe formed a rather homogeneous PEDV S INDEL cluster, suggesting a recent re-introduction. However, in-detail analyses revealed two new clusters and putative ancestor strains. Based on the available background data, correlations between clusters and location, farm type or clinical presentation could not be established. Additionally, the impact of secondary infections was explored using the metagenomic data sets. While several coinfections were observed, no correlation was found with disease courses. However, in addition to the PEDV genomes, ten complete viral coding sequences from nine different data sets were reconstructed each representing new virus strains. In detail, three pasivirus A strains, two astroviruses, a porcine sapelovirus, a kobuvirus, a porcine torovirus, a posavirus, and an enterobacteria phage were almost fully sequenced.

  6. Lifestyle Choices Fuel Epidemics of Diabetes and Cardiovascular Disease Among Asian Indians.

    Science.gov (United States)

    O'Keefe, Evan L; DiNicolantonio, James J; Patil, Harshal; Helzberg, John H; Lavie, Carl J

    2016-01-01

    Within the next 15years, India is projected to overtake China as the world's most populous nation. Due to the rapid pace of urbanization and modernization fueling population growth, in conjunction with a genetic predisposition to insulin resistance, India is suffering a rising epidemic of non-communicable diseases (NCDs), including coronary artery disease (CAD), type 2 diabetes mellitus (T2DM), and stroke. In addition to the genetic predisposition, major negative lifestyle factors are contributing to the alarming outbreak of cardiovascular disease (CVD) among the Asian Indian population; these factors include: 1) a diet high in added sugar, refined grains and other processed foods, 2) physical inactivity, 3) vitamin D deficiency (VDD), and 4) smoking/pollution. These risk factors are all highly modifiable, and steps to improve these issues should be taken urgently to avoid a worsening NCD crisis among the inhabitants of the South Asian subcontinent as well as for people with Asian Indian ethnicity worldwide. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Public health and public trust: Survey evidence from the Ebola Virus Disease epidemic in Liberia.

    Science.gov (United States)

    Blair, Robert A; Morse, Benjamin S; Tsai, Lily L

    2017-01-01

    Trust in government has long been viewed as an important determinant of citizens' compliance with public health policies, especially in times of crisis. Yet evidence on this relationship remains scarce, particularly in the developing world. We use results from a representative survey conducted during the 2014-15 Ebola Virus Disease (EVD) epidemic in Monrovia, Liberia to assess the relationship between trust in government and compliance with EVD control interventions. We find that respondents who expressed low trust in government were much less likely to take precautions against EVD in their homes, or to abide by government-mandated social distancing mechanisms designed to contain the spread of the virus. They were also much less likely to support potentially contentious control policies, such as "safe burial" of EVD-infected bodies. Contrary to stereotypes, we find no evidence that respondents who distrusted government were any more or less likely to understand EVD's symptoms and transmission pathways. While only correlational, these results suggest that respondents who refused to comply may have done so not because they failed to understand how EVD is transmitted, but rather because they did not trust the capacity or integrity of government institutions to recommend precautions and implement policies to slow EVD's spread. We also find that respondents who experienced hardships during the epidemic expressed less trust in government than those who did not, suggesting the possibility of a vicious cycle between distrust, non-compliance, hardships and further distrust. Finally, we find that respondents who trusted international non-governmental organizations (INGOs) were no more or less likely to support or comply with EVD control policies, suggesting that while INGOs can contribute in indispensable ways to crisis response, they cannot substitute for government institutions in the eyes of citizens. We conclude by discussing the implications of our findings for future

  8. Real time bayesian estimation of the epidemic potential of emerging infectious diseases.

    Directory of Open Access Journals (Sweden)

    Luís M A Bettencourt

    Full Text Available BACKGROUND: Fast changes in human demographics worldwide, coupled with increased mobility, and modified land uses make the threat of emerging infectious diseases increasingly important. Currently there is worldwide alert for H5N1 avian influenza becoming as transmissible in humans as seasonal influenza, and potentially causing a pandemic of unprecedented proportions. Here we show how epidemiological surveillance data for emerging infectious diseases can be interpreted in real time to assess changes in transmissibility with quantified uncertainty, and to perform running time predictions of new cases and guide logistics allocations. METHODOLOGY/PRINCIPAL FINDINGS: We develop an extension of standard epidemiological models, appropriate for emerging infectious diseases, that describes the probabilistic progression of case numbers due to the concurrent effects of (incipient human transmission and multiple introductions from a reservoir. The model is cast in terms of surveillance observables and immediately suggests a simple graphical estimation procedure for the effective reproductive number R (mean number of cases generated by an infectious individual of standard epidemics. For emerging infectious diseases, which typically show large relative case number fluctuations over time, we develop a bayesian scheme for real time estimation of the probability distribution of the effective reproduction number and show how to use such inferences to formulate significance tests on future epidemiological observations. CONCLUSIONS/SIGNIFICANCE: Violations of these significance tests define statistical anomalies that may signal changes in the epidemiology of emerging diseases and should trigger further field investigation. We apply the methodology to case data from World Health Organization reports to place bounds on the current transmissibility of H5N1 influenza in humans and establish a statistical basis for monitoring its evolution in real time.

  9. The use of gamification in the teaching of disease epidemics and pandemics.

    Science.gov (United States)

    Robinson, L A; Turner, I J; Sweet, M J

    2018-06-01

    With the launch of the teaching excellence framework, teaching in higher education (HE) is under greater scrutiny than ever before. Didactic lecture delivery is still a core element of many HE programmes but there is now a greater expectation for academics to incorporate alternative approaches into their practice to increase student engagement. These approaches may include a large array of techniques from group activities, problem-based learning, practical experience and mock scenarios to newly emerging approaches such as flipped learning practices and the use of gamification. These participatory forms of learning encourage students to become more absorbed within a topic that may otherwise be seen as rather 'dry' and reduce students engagement with, and therefore retention of, material. Here we use participatory-based teaching approaches in microbiology as an example to illustrate to University undergraduate students the potentially devastating effects that a disease can have on a population. The 'threat' that diseases may pose and the manner in which they may spread and/or evolve can be challenging to communicate, especially in relation to the timescales associated with these factors in the case of an epidemic or pandemic.

  10. Genome variability of foot-and-mouth disease virus during the short period of the 2010 epidemic in Japan.

    Science.gov (United States)

    Nishi, Tatsuya; Yamada, Manabu; Fukai, Katsuhiko; Shimada, Nobuaki; Morioka, Kazuki; Yoshida, Kazuo; Sakamoto, Kenichi; Kanno, Toru; Yamakawa, Makoto

    2017-02-01

    Foot-and-mouth disease virus (FMDV) is highly contagious and has a high mutation rate, leading to extensive genetic variation. To investigate how FMDV genetically evolves over a short period of an epidemic after initial introduction into an FMD-free area, whole L-fragment sequences of 104 FMDVs isolated from the 2010 epidemic in Japan, which continued for less than three months were determined and phylogenetically and comparatively analyzed. Phylogenetic analysis of whole L-fragment sequences showed that these isolates were classified into a single group, indicating that FMDV was introduced into Japan in the epidemic via a single introduction. Nucleotide sequences of 104 virus isolates showed more than 99.56% pairwise identity rates without any genetic deletion or insertion, although no sequences were completely identical with each other. These results indicate that genetic substitutions of FMDV occurred gradually and constantly during the epidemic and generation of an extensive mutant virus could have been prevented by rapid eradication strategy. From comparative analysis of variability of each FMDV protein coding region, VP4 and 2C regions showed the highest average identity rates and invariant rates, and were confirmed as highly conserved. In contrast, the protein coding regions VP2 and VP1 were confirmed to be highly variable regions with the lowest average identity rates and invariant rates, respectively. Our data demonstrate the importance of rapid eradication strategy in an FMD epidemic and provide valuable information on the genome variability of FMDV during the short period of an epidemic. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  11. 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.

  12. Childhood cardiovascular risk factors in South Asians: A cause of concern for adult cardiovascular disease epidemic

    International Nuclear Information System (INIS)

    Prasad, Duggirala Sivaram; Kabir, Zubair; Dash, Ashok Kumar; Das, Bhagabati Charan

    2011-01-01

    Cardiovascular risk factors in children are increasing at an alarming rate in the western world. However, there is limited information regarding these in the South Asian children. This review attempts at summarizing such evidence. South Asians are remarkable for the earlier onset of adult cardiovascular disease (CVD) by almost a decade compared to the Caucasians. We identified published literature, mainly on PubMed, Embase and Cochrane library using specific search terms such as lipid abnormalities, high blood pressure, hyperglycemia, tobacco use, obesity, physical inactivity, and unhealthy dietary practices. Atherosclerotic CVD processes begin early in childhood and are influenced over the life course by genetic and potentially modifiable risk factors and environmental exposure. 80% of adult CVD burden will fall on the developing nations by 2020. The concept of primordial prevention is fast emerging as a necessary prevention tool to curb adult CVD epidemic. Established guidelines and proven preventive strategies on cardiovascular health exist; however, are always implemented half-heartedly. Composite screening and prediction tools for adults can be adapted and validated in children tailored to South Asian population. South Asian children could be at a greater risk of developing cardiovascular risk factors at an earlier stage, thus, timely interventions are imperative

  13. Accuracy of Zika virus disease case definition during simultaneous Dengue and Chikungunya epidemics.

    Science.gov (United States)

    Braga, José Ueleres; Bressan, Clarisse; Dalvi, Ana Paula Razal; Calvet, Guilherme Amaral; Daumas, Regina Paiva; Rodrigues, Nadia; Wakimoto, Mayumi; Nogueira, Rita Maria Ribeiro; Nielsen-Saines, Karin; Brito, Carlos; Bispo de Filippis, Ana Maria; Brasil, Patrícia

    2017-01-01

    Zika is a new disease in the American continent and its surveillance is of utmost importance, especially because of its ability to cause neurological manifestations as Guillain-Barré syndrome and serious congenital malformations through vertical transmission. The detection of suspected cases by the surveillance system depends on the case definition adopted. As the laboratory diagnosis of Zika infection still relies on the use of expensive and complex molecular techniques with low sensitivity due to a narrow window of detection, most suspected cases are not confirmed by laboratory tests, mainly reserved for pregnant women and newborns. In this context, an accurate definition of a suspected Zika case is crucial in order for the surveillance system to gauge the magnitude of an epidemic. We evaluated the accuracy of various Zika case definitions in a scenario where Dengue and Chikungunya viruses co-circulate. Signs and symptoms that best discriminated PCR confirmed Zika from other laboratory confirmed febrile or exanthematic diseases were identified to propose and test predictive models for Zika infection based on these clinical features. Our derived score prediction model had the best performance because it demonstrated the highest sensitivity and specificity, 86·6% and 78·3%, respectively. This Zika case definition also had the highest values for auROC (0·903) and R2 (0·417), and the lowest Brier score 0·096. In areas where multiple arboviruses circulate, the presence of rash with pruritus or conjunctival hyperemia, without any other general clinical manifestations such as fever, petechia or anorexia is the best Zika case definition.

  14. Accuracy of Zika virus disease case definition during simultaneous Dengue and Chikungunya epidemics.

    Directory of Open Access Journals (Sweden)

    José Ueleres Braga

    Full Text Available Zika is a new disease in the American continent and its surveillance is of utmost importance, especially because of its ability to cause neurological manifestations as Guillain-Barré syndrome and serious congenital malformations through vertical transmission. The detection of suspected cases by the surveillance system depends on the case definition adopted. As the laboratory diagnosis of Zika infection still relies on the use of expensive and complex molecular techniques with low sensitivity due to a narrow window of detection, most suspected cases are not confirmed by laboratory tests, mainly reserved for pregnant women and newborns. In this context, an accurate definition of a suspected Zika case is crucial in order for the surveillance system to gauge the magnitude of an epidemic.We evaluated the accuracy of various Zika case definitions in a scenario where Dengue and Chikungunya viruses co-circulate. Signs and symptoms that best discriminated PCR confirmed Zika from other laboratory confirmed febrile or exanthematic diseases were identified to propose and test predictive models for Zika infection based on these clinical features.Our derived score prediction model had the best performance because it demonstrated the highest sensitivity and specificity, 86·6% and 78·3%, respectively. This Zika case definition also had the highest values for auROC (0·903 and R2 (0·417, and the lowest Brier score 0·096.In areas where multiple arboviruses circulate, the presence of rash with pruritus or conjunctival hyperemia, without any other general clinical manifestations such as fever, petechia or anorexia is the best Zika case definition.

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

    Science.gov (United States)

    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.

  16. Using a Negative Binomial Regression Model for Early Warning at the Start of a Hand Foot Mouth Disease Epidemic in Dalian, Liaoning Province, China.

    Science.gov (United States)

    An, Qingyu; Wu, Jun; Fan, Xuesong; Pan, Liyang; Sun, Wei

    2016-01-01

    The hand foot and mouth disease (HFMD) is a human syndrome caused by intestinal viruses like that coxsackie A virus 16, enterovirus 71 and easily developed into outbreak in kindergarten and school. Scientifically and accurately early detection of the start time of HFMD epidemic is a key principle in planning of control measures and minimizing the impact of HFMD. The objective of this study was to establish a reliable early detection model for start timing of hand foot mouth disease epidemic in Dalian and to evaluate the performance of model by analyzing the sensitivity in detectability. The negative binomial regression model was used to estimate the weekly baseline case number of HFMD and identified the optimal alerting threshold between tested difference threshold values during the epidemic and non-epidemic year. Circular distribution method was used to calculate the gold standard of start timing of HFMD epidemic. From 2009 to 2014, a total of 62022 HFMD cases were reported (36879 males and 25143 females) in Dalian, Liaoning Province, China, including 15 fatal cases. The median age of the patients was 3 years. The incidence rate of epidemic year ranged from 137.54 per 100,000 population to 231.44 per 100,000population, the incidence rate of non-epidemic year was lower than 112 per 100,000 population. The negative binomial regression model with AIC value 147.28 was finally selected to construct the baseline level. The threshold value was 100 for the epidemic year and 50 for the non- epidemic year had the highest sensitivity(100%) both in retrospective and prospective early warning and the detection time-consuming was 2 weeks before the actual starting of HFMD epidemic. The negative binomial regression model could early warning the start of a HFMD epidemic with good sensitivity and appropriate detection time in Dalian.

  17. 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

  18. Recalibrating disease parameters for increasing realism in modeling epidemics in closed settings

    Directory of Open Access Journals (Sweden)

    Livio Bioglio

    2016-11-01

    Full Text Available Abstract Background The homogeneous mixing assumption is widely adopted in epidemic modelling for its parsimony and represents the building block of more complex approaches, including very detailed agent-based models. The latter assume homogeneous mixing within schools, workplaces and households, mostly for the lack of detailed information on human contact behaviour within these settings. The recent data availability on high-resolution face-to-face interactions makes it now possible to assess the goodness of this simplified scheme in reproducing relevant aspects of the infection dynamics. Methods We consider empirical contact networks gathered in different contexts, as well as synthetic data obtained through realistic models of contacts in structured populations. We perform stochastic spreading simulations on these contact networks and in populations of the same size under a homogeneous mixing hypothesis. We adjust the epidemiological parameters of the latter in order to fit the prevalence curve of the contact epidemic model. We quantify the agreement by comparing epidemic peak times, peak values, and epidemic sizes. Results Good approximations of the peak times and peak values are obtained with the homogeneous mixing approach, with a median relative difference smaller than 20 % in all cases investigated. Accuracy in reproducing the peak time depends on the setting under study, while for the peak value it is independent of the setting. Recalibration is found to be linear in the epidemic parameters used in the contact data simulations, showing changes across empirical settings but robustness across groups and population sizes. Conclusions An adequate rescaling of the epidemiological parameters can yield a good agreement between the epidemic curves obtained with a real contact network and a homogeneous mixing approach in a population of the same size. The use of such recalibrated homogeneous mixing approximations would enhance the accuracy and

  19. Recalibrating disease parameters for increasing realism in modeling epidemics in closed settings.

    Science.gov (United States)

    Bioglio, Livio; Génois, Mathieu; Vestergaard, Christian L; Poletto, Chiara; Barrat, Alain; Colizza, Vittoria

    2016-11-14

    The homogeneous mixing assumption is widely adopted in epidemic modelling for its parsimony and represents the building block of more complex approaches, including very detailed agent-based models. The latter assume homogeneous mixing within schools, workplaces and households, mostly for the lack of detailed information on human contact behaviour within these settings. The recent data availability on high-resolution face-to-face interactions makes it now possible to assess the goodness of this simplified scheme in reproducing relevant aspects of the infection dynamics. We consider empirical contact networks gathered in different contexts, as well as synthetic data obtained through realistic models of contacts in structured populations. We perform stochastic spreading simulations on these contact networks and in populations of the same size under a homogeneous mixing hypothesis. We adjust the epidemiological parameters of the latter in order to fit the prevalence curve of the contact epidemic model. We quantify the agreement by comparing epidemic peak times, peak values, and epidemic sizes. Good approximations of the peak times and peak values are obtained with the homogeneous mixing approach, with a median relative difference smaller than 20 % in all cases investigated. Accuracy in reproducing the peak time depends on the setting under study, while for the peak value it is independent of the setting. Recalibration is found to be linear in the epidemic parameters used in the contact data simulations, showing changes across empirical settings but robustness across groups and population sizes. An adequate rescaling of the epidemiological parameters can yield a good agreement between the epidemic curves obtained with a real contact network and a homogeneous mixing approach in a population of the same size. The use of such recalibrated homogeneous mixing approximations would enhance the accuracy and realism of agent-based simulations and limit the intrinsic biases of

  20. Kin groups and trait groups: population structure and epidemic disease selection.

    Science.gov (United States)

    Fix, A G

    1984-10-01

    A Monte Carlo simulation based on the population structure of a small-scale human population, the Semai Senoi of Malaysia, has been developed to study the combined effects of group, kin, and individual selection. The population structure resembles D.S. Wilson's structured deme model in that local breeding populations (Semai settlements) are subdivided into trait groups (hamlets) that may be kin-structured and are not themselves demes. Additionally, settlement breeding populations are connected by two-dimensional stepping-stone migration approaching 30% per generation. Group and kin-structured group selection occur among hamlets the survivors of which then disperse to breed within the settlement population. Genetic drift is modeled by the process of hamlet formation; individual selection as a deterministic process, and stepping-stone migration as either random or kin-structured migrant groups. The mechanism for group selection is epidemics of infectious disease that can wipe out small hamlets particularly if most adults become sick and social life collapses. Genetic resistance to a disease is an individual attribute; however, hamlet groups with several resistant adults are less likely to disintegrate and experience high social mortality. A specific human gene, hemoglobin E, which confers resistance to malaria, is studied as an example of the process. The results of the simulations show that high genetic variance among hamlet groups may be generated by moderate degrees of kin-structuring. This strong microdifferentiation provides the potential for group selection. The effect of group selection in this case is rapid increase in gene frequencies among the total set of populations. In fact, group selection in concert with individual selection produced a faster rate of gene frequency increase among a set of 25 populations than the rate within a single unstructured population subject to deterministic individual selection. Such rapid evolution with plausible rates of

  1. Trade and investment liberalization and Asia's noncommunicable disease epidemic: a synthesis of data and existing literature.

    Science.gov (United States)

    Baker, Phillip; Kay, Adrian; Walls, Helen

    2014-09-12

    Trade and investment liberalization (trade liberalization) can promote or harm health. Undoubtedly it has contributed, although unevenly, to Asia's social and economic development over recent decades with resultant gains in life expectancy and living standards. In the absence of public health protections, however, it is also a significant upstream driver of non-communicable diseases (NCDs) including cardiovascular disease, cancer and diabetes through facilitating increased consumption of the 'risk commodities' tobacco, alcohol and ultra-processed foods, and by constraining access to NCD medicines. In this paper we describe the NCD burden in Asian countries, trends in risk commodity consumption and the processes by which trade liberalization has occurred in the region and contributed to these trends. We further establish pressing questions for future research on strengthening regulatory capacity to address trade liberalization impacts on risk commodity consumption and health. A semi-structured search of scholarly databases, institutional websites and internet sources for academic and grey literature. Data for descriptive statistics were sourced from Euromonitor International, the World Bank, the World Health Organization, and the World Trade Organization. Consumption of tobacco, alcohol and ultra-processed foods was prevalent in the region and increasing in many countries. We find that trade liberalization can facilitate increased trade in goods, services and investments in ways that can promote risk commodity consumption, as well as constrain the available resources and capacities of governments to enact policies and programmes to mitigate such consumption. Intellectual property provisions of trade agreements may also constrain access to NCD medicines. Successive layers of the evolving global and regional trade regimes including structural adjustment, multilateral trade agreements, and preferential trade agreements have enabled transnational corporations that

  2. 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.

  3. Virus-Specific Differences in Rates of Disease during the 2010 Dengue Epidemic in Puerto Rico

    Science.gov (United States)

    Sharp, Tyler M.; Hunsperger, Elizabeth; Santiago, Gilberto A.; Muñoz-Jordan, Jorge L.; Santiago, Luis M.; Rivera, Aidsa; Rodríguez-Acosta, Rosa L.; Gonzalez Feliciano, Lorenzo; Margolis, Harold S.; Tomashek, Kay M.

    2013-01-01

    Background Dengue is a potentially fatal acute febrile illness (AFI) caused by four mosquito-transmitted dengue viruses (DENV-1–4) that are endemic in Puerto Rico. In January 2010, the number of suspected dengue cases reported to the passive dengue surveillance system exceeded the epidemic threshold and an epidemic was declared soon after. Methodology/Principal Findings To characterize the epidemic, surveillance and laboratory diagnostic data were compiled. A suspected case was a dengue-like AFI in a person reported by a health care provider with or without a specimen submitted for diagnostic testing. Laboratory-positive cases had: (i) DENV nucleic acid detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in an acute serum specimen; (ii) anti-DENV IgM antibody detected by ELISA in any serum specimen; or (iii) DENV antigen or nucleic acid detected in an autopsy-tissue specimen. In 2010, a total of 26,766 suspected dengue cases (7.2 per 1,000 residents) were identified, of which 46.6% were laboratory-positive. Of 7,426 RT-PCR-positive specimens, DENV-1 (69.0%) and DENV-4 (23.6%) were detected more frequently than DENV-2 (7.3%) and DENV-3 (Puerto Rico in the late 1960's. This epidemic re-emphasizes the need for more effective primary prevention interventions to reduce the morbidity and mortality of dengue. PMID:23593526

  4. 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 ...

  5. Estimating Coextinction Risks from Epidemic Tree Death: Affiliate Lichen Communities among Diseased Host Tree Populations of Fraxinus excelsior

    Science.gov (United States)

    Jönsson, Mari T.; Thor, Göran

    2012-01-01

    At least 10% of the world’s tree species are threatened with extinction and pathogens are increasingly implicated in tree threats. Coextinction and threats to affiliates as a consequence of the loss or decline of their host trees is a poorly understood phenomenon. Ash dieback is an emerging infectious disease causing severe dieback of common ash Fraxinus excelsior throughout Europe. We utilized available empirical data on affiliate epiphytic lichen diversity (174 species and 17,800 observations) among 20 ash dieback infected host tree populations of F. excelsior on the island Gotland in the Baltic Sea, Sweden. From this, we used structured scenario projections scaled with empirical data of ash dieback disease to generate probabilistic models for estimating local and regional lichen coextinction risks. Average coextinction probabilities (Ā) were 0.38 (95% CI ±0.09) for lichens occurring on F. excelsior and 0.14 (95% CI ±0.03) when considering lichen persistence on all tree species. Ā was strongly linked to local disease incidence levels and generally increasing with lichen host specificity to F. excelsior and decreasing population size. Coextinctions reduced affiliate community viability, with significant local reductions in species richness and shifts in lichen species composition. Affiliates were projected to become locally extirpated before their hosts, illuminating the need to also consider host tree declines. Traditionally managed open wooded meadows had the highest incidence of ash dieback disease and significantly higher proportions of affiliate species projected to go extinct, compared with unmanaged closed forests and semi-open grazed sites. Most cothreatened species were not previously red-listed, which suggest that tree epidemics cause many unforeseen threats to species. Our analysis shows that epidemic tree deaths represent an insidious, mostly overlooked, threat to sessile affiliate communities in forested environments. Current conservation and

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

    Science.gov (United States)

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

    2017-09-01

    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.

  7. Estimating risk factors for farm-level transmission of disease: Foot and mouth disease during the 2001 epidemic in Great Britain

    Directory of Open Access Journals (Sweden)

    Paul R. Bessell

    2010-09-01

    Full Text Available Controlling an epidemic would be aided by establishing whether particular individuals in infected populations are more likely to transmit infection. However, few analyses have characterised such individuals. Such analyses require both data on who infected whom and on the likely determinants of transmission; data that are available at the farm level for the 2001 Foot and Mouth Disease epidemic in Great Britain. Using these data a putative number of daughter infected premises (IPs resulting from each IP was calculated where these daughters were within 3 km of the IP. A set of possible epidemiological, demographic, spatial and temporal risk factors were analysed, with the final multivariate generalised linear model (Poisson error term having 6 statistically significant (p<0.05 main effects including geographic area, local cattle and sheep densities, and the number of non-IP culls. This model demonstrates that farms are heterogeneous in their propensity to transmit infection to other farms and, importantly, that it may be possible to identify holdings that are at high risk of spreading disease a priori. Such information could be used to help prioritise the response to an epidemic. Keywords: Foot and mouth disease, Epidemiology, Risk modelling, Livestock, Disease control

  8. Analysis of the epidemiological dynamics during the 1982-1983 epidemic of foot-and-mouth disease in Denmark based on molecular high-resolution strain identification

    DEFF Research Database (Denmark)

    Christensen, Laurids Siig; Normann, Preben; Thykier-Nielsen, Søren

    2005-01-01

    An epidemic of foot-and-mouth disease (FMD) causing a total of 23 cases in 1982-1983, primarily on the island of Funen, Denmark, was subjected to molecular epidemiological investigations. In an attempt to exploit the quasi-species nature of foot-and-mouth disease virus strains for molecular high......-resolution strain identification in order to analyse the dynamics of this epidemic, full-length VP1 coding regions were sequenced for 17 isolates collected at different farms during the epidemic. The sequence information together with epidemiological information gathered during the epidemic suggests......, and the prerequisite of co- or superinfection of animals with variant strains in turn implies that they have a common source or epidemiologically related sources originating from an area with endemic FMD....

  9. Disease load at conception predicts survival in later epidemics in a historical French-Canadian cohort, suggesting functional trans-generational effects in humans.

    Directory of Open Access Journals (Sweden)

    Kai Willführ

    Full Text Available OBJECTIVE: Functional trans-generational and parental effects are potentially important determinants of health in several mammals. For humans, the existing evidence is weak. We investigate whether disease exposure triggers functional trans-generational response effects among humans by analyzing siblings who were conceived under different disease loads, and comparing their mortality in later epidemics. Under functional trans-generational response mechanisms, we expect that those who were conceived under high pathogenic stress load will have relatively low mortality during a later epidemic. METHODS: We use data from the Registre de la Population du Québec Ancien, which covers the historical population living in St. Lawrence Valley, Québec, Canada. Children born in 1705-1724 were grouped according to their exposure during conception to the measles 1714-15 epidemic. The 1714-15 epidemic was followed by two mortality crises in 1729-1734. The cause of the first crises in 1729 is not exactly known. The second crisis in 1732 was caused by a smallpox epidemic. Using proportional hazard Cox regression models with multivariate adjustment and with fixed-effects approach that compare siblings, we analyze whether mortality in 1729-1734 is affected by exposure to the 1714-15 epidemic. RESULTS: Children who were conceived during the peak of the measles epidemic of 1714-15 exhibited significantly lower mortality during the 1729-1734 crisis than those who were born before the 1714-15 epidemic (mortality hazard ratio 0.106, p<.05 in multivariate adjusted models; 0.142 p<.1 in sibling comparison models. CONCLUSIONS: The results are consistent with a trans-generational mechanism that functionally responds to pathogen stress and suggest that early disease exposure may be protective later in life. Alternative explanations for the mortality patterns are discussed and shown to be problematic.

  10. Implementation of an Ebola virus disease vaccine clinical trial during the Ebola epidemic in Liberia: Design, procedures, and challenges.

    Science.gov (United States)

    Kennedy, Stephen B; Neaton, James D; Lane, H Clifford; Kieh, Mark W S; Massaquoi, Moses B F; Touchette, Nancy A; Nason, Martha C; Follmann, Dean A; Boley, Fatorma K; Johnson, Melvin P; Larson, Gregg; Kateh, Francis N; Nyenswah, Tolbert G

    2016-02-01

    The index case of the Ebola virus disease epidemic in West Africa is believed to have originated in Guinea. By June 2014, Guinea, Liberia, and Sierra Leone were in the midst of a full-blown and complex global health emergency. The devastating effects of this Ebola epidemic in West Africa put the global health response in acute focus for urgent international interventions. Accordingly, in October 2014, a World Health Organization high-level meeting endorsed the concept of a phase 2/3 clinical trial in Liberia to study Ebola vaccines. As a follow-up to the global response, in November 2014, the Government of Liberia and the US Government signed an agreement to form a research partnership to investigate Ebola and to assess intervention strategies for treating, controlling, and preventing the disease in Liberia. This agreement led to the establishment of the Joint Liberia-US Partnership for Research on Ebola Virus in Liberia as the beginning of a long-term collaborative partnership in clinical research between the two countries. In this article, we discuss the methodology and related challenges associated with the implementation of the Ebola vaccines clinical trial, based on a double-blinded randomized controlled trial, in Liberia. © The Author(s) 2016.

  11. Serosurveillance of wild deer and wild boar after the epidemic of foot-and-mouth disease in the Netherlands in 2001

    NARCIS (Netherlands)

    Elbers, A.R.W.; Dekker, A.; Dekkers, L.J.M.

    2003-01-01

    Blood samples from 140 wild deer and 208 wild boar shot in the aftermath of the epidemic of foot-and-mouth disease in the Netherlands in 2001 were examined for antibodies to foot-and-mouth disease virus. They were all negative

  12. Knowledge, Attitudes, and Practices Related to Ebola Virus Disease at the End of a National Epidemic - Guinea, August 2015.

    Science.gov (United States)

    Jalloh, Mohamed F; Robinson, Susan J; Corker, Jamaica; Li, Wenshu; Irwin, Kathleen; Barry, Alpha M; Ntuba, Paulyne Ngalame; Diallo, Alpha A; Jalloh, Mohammad B; Nyuma, James; Sellu, Musa; VanSteelandt, Amanda; Ramsden, Megan; Tracy, LaRee; Raghunathan, Pratima L; Redd, John T; Martel, Lise; Marston, Barbara; Bunnell, Rebecca

    2017-10-20

    Health communication and social mobilization efforts to improve the public's knowledge, attitudes, and practices (KAP) regarding Ebola virus disease (Ebola) were important in controlling the 2014-2016 Ebola epidemic in Guinea (1), which resulted in 3,814 reported Ebola cases and 2,544 deaths.* Most Ebola cases in Guinea resulted from the washing and touching of persons and corpses infected with Ebola without adequate infection control precautions at home, at funerals, and in health facilities (2,3). As the 18-month epidemic waned in August 2015, Ebola KAP were assessed in a survey among residents of Guinea recruited through multistage cluster sampling procedures in the nation's eight administrative regions (Boké, Conakry, Faranah, Kankan, Kindia, Labé, Mamou, and Nzérékoré). Nearly all participants (92%) were aware of Ebola prevention measures, but 27% believed that Ebola could be transmitted by ambient air, and 49% believed they could protect themselves from Ebola by avoiding mosquito bites. Of the participants, 95% reported taking actions to avoid getting Ebola, especially more frequent handwashing (93%). Nearly all participants (91%) indicated they would send relatives with suspected Ebola to Ebola treatment centers, and 89% said they would engage special Ebola burial teams to remove corpses with suspected Ebola from homes. Of the participants, 66% said they would prefer to observe an Ebola-affected corpse from a safe distance at burials rather than practice traditional funeral rites involving corpse contact. The findings were used to guide the ongoing epidemic response and recovery efforts, including health communication, social mobilization, and planning, to prevent and respond to future outbreaks or sporadic cases of Ebola.

  13. Ebola virus disease outbreak; the role of field epidemiology training programme in the fight against the epidemic, Liberia, 2014.

    Science.gov (United States)

    Lubogo, Mutaawe; Donewell, Bangure; Godbless, Lucas; Shabani, Sasita; Maeda, Justin; Temba, Herilinda; Malibiche, Theophil C; Berhanu, Naod

    2015-01-01

    The African Field Epidemiology Network (AFENET) is a public health network established in 2005 as a non-profit networking alliance of Field Epidemiology and Laboratory Training Programs (FELTPs) and Field Epidemiology Training Programs (FETPs) in Africa. AFENET is dedicated to supporting Ministries of Health in Africa build strong, effective and sustainable programs and capacity to improve public health systems by partnering with global public health experts. The Network's goal is to strengthen field epidemiology and public health laboratory capacity to contribute effectively to addressing epidemics and other major public health problems in Africa. The goal for the establishment of FETP and FELTP was and still is to produce highly competent multi-disciplinary public health professionals who would assume influential posts in the public health structures and tackle emerging and re-emerging communicable and non-communicable diseases. AFENET currently networks 12 FELTPs and FETPs in sub-Saharan Africa with operations in 20 countries. During the Ebola Virus Disease (EVD) outbreak in West Africa, African Union Support for the Ebola Outbreak in West Africa (ASEOWA) supported FETP graduates from Uganda, Zimbabwe, Ethiopia and Tanzania for the investigation and control of the EVD outbreak in Liberia. The graduates were posted in different counties in Liberia where they lead teams of other experts conduct EVD outbreak investigations, Infection Control and Prevention trainings among health workers and communities, Strengthening integrated disease surveillance, developing Standard Operating Procedures for infection control and case notification in the Liberian setting as well as building capacity of local surveillance officers' conduct outbreak investigation and contact tracing. The team was also responsible for EVD data management at the different Counties in Liberia. The FETP graduates have been instrumental in the earlier successes registered in various counties in Liberia

  14. Abrupt transition to heightened poliomyelitis epidemicity in England and Wales, 1947-1957, associated with a pronounced increase in the geographical rate of disease propagation.

    Science.gov (United States)

    Smallman-Raynor, M R; Cliff, A D

    2014-03-01

    The abrupt transition to heightened poliomyelitis epidemicity in England and Wales, 1947-1957, was associated with a profound change in the spatial dynamics of the disease. Drawing on the complete record of poliomyelitis notifications in England and Wales, we use a robust method of spatial epidemiological analysis (swash-backwash model) to evaluate the geographical rate of disease propagation in successive poliomyelitis seasons, 1940-1964. Comparisons with earlier and later time periods show that the period of heightened poliomyelitis epidemicity corresponded with a sudden and pronounced increase in the spatial rate of disease propagation. This change was observed for both urban and rural areas and points to an abrupt enhancement in the propensity for the geographical spread of polioviruses. Competing theories of the epidemic emergence of poliomyelitis in England and Wales should be assessed in the light of this evidence.

  15. 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.

  16. Rainfall-driven epidemic cholera: hydrologic controls on water-borne disease and multi-season projections

    Science.gov (United States)

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

    2012-12-01

    Following the acknowledgement of a clear correlation between rainfall events and cholera resurgence, that was observed in Haiti starting from May 2011, we use a multi-variate Poisson generator to produce rainfall inputs, with which we force spatially explicit models of cholera spreading. Our models consist of ODE systems of equations, describing a network of human communities (divided in Susceptible, Infected and Recovered individuals) connected by river transport of pathogens and human mobility. We perform an a posteriori analysis -- from the beginning of the epidemic until December 2011 -- to assess the model reliability in predicting cholera cases and in testing control measures -- involving vaccination and sanitation campaigns. We then run a multi-seasonal prediction of the course of the epidemic until December 2015, to investigate further resurgences of cholera in the region and to evaluate, again, the effect of policies which may bring to the eradication of the disease in Haiti. We conclude that mathematical models may represent a key information tool for policy makers, as a way to preliminarly assess the possible future course of an epidemic and to test intervention policies to be deployed. Effect of intervention policies on the predicted course of the epidemic between 28/05-31/12/2011 (blue lines: simulations with the observed rainfall pattern; red lines/shaded range: median/25th-75th percentile range of simulations with generated rainfall). A) Effect of a reduction of the 20% of the contact rate , applied in one month starting from the 1st of June (dashed blue/red lines) or the 1st of July (dotted blue/red lines). B) A) Effect of a vaccination of 4 million individuals, implemented in one month starting from the 1st of June (dashed blue/red lines) or the 1st of July (dotted blue/red lines). C) Number of new cases in the period 28/05-31/12/2011 as a function of the reduction of the contact rate . D) Number of new cases in the period 28/05-31/12/2011 as a

  17. Glyphosate, Hard Water and Nephrotoxic Metals: Are They the Culprits Behind the Epidemic of Chronic Kidney Disease of Unknown Etiology in Sri Lanka?

    Science.gov (United States)

    Jayasumana, Channa; Gunatilake, Sarath; Senanayake, Priyantha

    2014-01-01

    The current chronic kidney disease epidemic, the major health issue in the rice paddy farming areas in Sri Lanka has been the subject of many scientific and political debates over the last decade. Although there is no agreement among scientists about the etiology of the disease, a majority of them has concluded that this is a toxic nephropathy. None of the hypotheses put forward so far could explain coherently the totality of clinical, biochemical, histopathological findings, and the unique geographical distribution of the disease and its appearance in the mid-1990s. A strong association between the consumption of hard water and the occurrence of this special kidney disease has been observed, but the relationship has not been explained consistently. Here, we have hypothesized the association of using glyphosate, the most widely used herbicide in the disease endemic area and its unique metal chelating properties. The possible role played by glyphosate-metal complexes in this epidemic has not been given any serious consideration by investigators for the last two decades. Furthermore, it may explain similar kidney disease epidemics observed in Andra Pradesh (India) and Central America. Although glyphosate alone does not cause an epidemic of chronic kidney disease, it seems to have acquired the ability to destroy the renal tissues of thousands of farmers when it forms complexes with a localized geo environmental factor (hardness) and nephrotoxic metals. PMID:24562182

  18. [The 2011 HUS epidemic in Germany. Challenges for disease control: what should be improved?].

    Science.gov (United States)

    Krause, G; Frank, C; Gilsdorf, A; Mielke, M; Schaade, L; Stark, K; Burger, R

    2013-01-01

    From May to July 2011 [corrected] the world's largest outbreak of hemolytic uremic syndrome (HUS) occurred in northern Germany with dramatic consequences for the population, the health care system and the food industry. In the following we examine the detection of the outbreak, epidemic management and related public communication aspects based on scientific publications, media reports as well as own and new data analyses. The subsequent 17 recommendations concern issues such as participation in and implementation of existing and new surveillance systems particularly with respect to physicians, broad application of finely tuned microbiological typing, improved personnel capacity and crisis management structures within the public health service and evidence-based communication by administrations and scientific associations. Outbreaks of similar dimensions can inevitably occur again and result in costs which will far exceed investments needed for early detection and control. This societal balance should be taken into account in spite of limited resources in the public health sector.

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

    Science.gov (United States)

    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.

  20. Seeking an optimal renal replacement therapy for the chronic kidney disease epidemic: the case for on-line hemodiafiltration.

    Science.gov (United States)

    Gatti, Emanuele; Ronco, Claudio

    2011-01-01

    The prevalence of chronic kidney disease (CKD) can be expected to increase dramatically in the foreseeable future, with suggestions that it has already reached epidemic proportions. The inadequate supply of donor organs, aggravated by an aging patient population, necessitates provision of sustainable dialysis treatment modalities. These treatment modalities must not only be of established clinical efficacy and effectiveness, but must simultaneously circumvent any potential treatment disparities due to geographical, social or other concurring factors. Home therapies might represent a partial solution to the complex issue of seeking optimal strategies to cope with the CKD epidemic. However, self-care renal replacement therapy (RRT), such as peritoneal dialysis (PD) and home therapies, can only be applied to a limited portion of the CKD population. Consequently, in preparation for coping with this CKD epidemic, specific large-scale plans need to be made that involve optimization of treatments already in use for the majority of the population requiring RRT, e.g. hemodialysis (HD). Extracorporeal chronic HD relies heavily on technology for its clinical success. Like the choice of the treatment modality and the complete medical approach to CKD patient care, the particular selection of the various components of the extracorporeal circuit has a significant impact on the well-being and survival of the patients. We present a medical-technological assessment of how best to treat vast numbers of dialysis patients under the financial restraints that are predicted to become even more severe as CKD entrenches itself as a more 'permanent epidemic'. A treatment modality is proposed that optimally addresses--and resolves--the debilitating effects of uremia, as well as of key clinical conditions closely linked to it. This treatment modality successfully tackles the issues of patient well-being, efficacy, effectiveness, safety and patient-nursing staff convenience--all in relation to

  1. An Emerging Epidemic of Noncommunicable Diseases in Developing Populations Due to a Triple Evolutionary Mismatch

    DEFF Research Database (Denmark)

    Koopman, Jacob J E; van Bodegom, David; Ziem, Juventus B

    2016-01-01

    With their transition from adverse to affluent environments, developing populations experience a rapid increase in the number of individuals with noncommunicable diseases. Here, we emphasize that developing populations are more susceptible than western populations to acquire these chronic disease...

  2. 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.

  3. Impact of infectious disease epidemics on tuberculosis diagnostic, management, and prevention services: experiences and lessons from the 2014–2015 Ebola virus disease outbreak in West Africa

    Directory of Open Access Journals (Sweden)

    Rashid Ansumana

    2017-03-01

    Full Text Available The World Health Organization (WHO Global Tuberculosis Report 2015 states that 28% of the world's 9.6 million new tuberculosis (TB cases are in the WHO Africa Region. The Mano River Union (MRU countries of West Africa–Guinea, Sierra Leone, and Liberia–have made incremental sustained investments into TB control programmes over the past two decades. The devastating Ebola virus disease (EVD outbreak of 2014–2015 in West Africa impacted significantly on all sectors of the healthcare systems in the MRU countries, including the TB prevention and control programmes. The EVD outbreak also had an adverse impact on the healthcare workforce and healthcare service delivery. At the height of the EVD outbreak, numerous staff members in all MRU countries contracted EBV at the Ebola treatment units and died. Many healthcare workers were also infected in healthcare facilities that were not Ebola treatment units but were national hospitals and peripheral health units that were unprepared for receiving patients with EVD. In all three MRU countries, the disruption to TB services due to the EVD epidemic will no doubt have increased Mycobacterium tuberculosis transmission, TB morbidity and mortality, and decreased patient adherence to TB treatment, and the likely impact will not be known for several years to come. In this viewpoint, the impact that the EVD outbreak had on TB diagnostic, management, and prevention services is described. Vaccination against TB with BCG in children under 5 years of age was affected adversely by the EVD epidemic. The EVD outbreak was a result of global failure and represents yet another ‘wake-up call’ to the international community, and particularly to African governments, to reach a consensus on new ways of thinking at the national, regional, and global levels for building healthcare systems that can sustain their function during outbreaks. This is necessary so that other disease control programmes (like those for TB, malaria

  4. Infectious diseases epidemic threats and mass gatherings: Refocusing global attention on the continuing spread of the Middle East Respiratory syndrome coronavirus (MERS-CoV)

    NARCIS (Netherlands)

    Zumla, A. (Alimuddin); Alagaili, A.N. (Abdulaziz N.); Cotten, M. (Matthew); Azhar, E.I. (Esam I.)

    2016-01-01

    textabstractMedia and World Health Organization (WHO) attention on Zika virus transmission at the 2016 Rio Olympic Games and the 2015 Ebola virus outbreak in West Africa diverted the attention of global public health authorities from other lethal infectious diseases with epidemic potential. Mass

  5. Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination.

    Science.gov (United States)

    Takahashi, Saki; Liao, Qiaohong; Van Boeckel, Thomas P; Xing, Weijia; Sun, Junling; Hsiao, Victor Y; Metcalf, C Jessica E; Chang, Zhaorui; Liu, Fengfeng; Zhang, Jing; Wu, Joseph T; Cowling, Benjamin J; Leung, Gabriel M; Farrar, Jeremy J; van Doorn, H Rogier; Grenfell, Bryan T; Yu, Hongjie

    2016-02-01

    Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus. Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible-infected-recovered (TSIR) epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40) and 27.13 for CV-A16 (IQR: 23.15, 31.34), with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation). EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the post-EV-A71

  6. Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination.

    Directory of Open Access Journals (Sweden)

    Saki Takahashi

    2016-02-01

    Full Text Available Hand, foot, and mouth disease (HFMD is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71 and Coxsackievirus A16 (CV-A16 being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus.Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible-infected-recovered (TSIR epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40 and 27.13 for CV-A16 (IQR: 23.15, 31.34, with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation. EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the

  7. Post-traumatic stress disorder in participants of foot-and-mouth disease epidemic control in Miyazaki, Japan, in 2010.

    Science.gov (United States)

    Hibi, Juri; Kurosawa, Aiko; Watanabe, Takuto; Kadowaki, Hazumu; Watari, Michiko; Makita, Kohei

    2015-08-01

    Foot-and-mouth disease (FMD) occurred in Miyazaki, Japan, in 2010, and 290,000 animals were culled. This paper describes the mental distress of the volunteers who had been dispatched to Miyazaki for disease control two years after the epidemic. It also assesses risk factors for post-traumatic stress disorder (PTSD). A participatory appraisal and self-administered questionnaire survey were conducted in 2012 for those who were dispatched to Miyazaki in 2010. The Impact of Event Scale-Revised (IES-R) was used as an indicator of PTSD, and univariate and multivariable analyses were performed. Of the 875 respondents, 1.3% had higher IES-R scores than the cut-off point (25), which is suggestive of PTSD. Mental stresses during and soon after FMD control and after two years were described. Four risk factors associated with high IES-R scores were found: transporting culled animals (Pstress during FMD control (Pstress at the time of the survey (Pstress two years later. Public services should provide an opportunity for them to consult with mental health specialists. These findings should be used to better prepare workers who deal with infectious diseases of animals, especially when they must be culled. The establishment of a collaborative framework between veterinary and mental health services is recommended.

  8. Water and infection : Epidemiological studies of epidemic and endemic waterborne disease

    OpenAIRE

    Nygård, Karin

    2008-01-01

    Infections transmitted by water continue to be a public health problem both in developing and in developed countries. In the developed countries, the classical waterborne diseases such as typhoid and cholera are almost eliminated, whereas other pathogens and challenges have emerged. The overall aim of the thesis was to investigate and describe aspects of water-associated infections in a Nordic setting. Contaminated water may act as a transmitter of infectious disease by various routes. E...

  9. Nutritional and food protection against epidemic emerging neuropathy. Epidemiological findings in the unique disease-free urban area of Cuba.

    Science.gov (United States)

    Barnouin, J; Verdura Barrios, T; Chassagne, M; Pérez Cristiá, R; Arnaud, J; Fleites Mestre, P; Montoya, M E; Favier, A

    2001-09-01

    A survey was conducted through the SECUBA (SEguridad alimentaria en CUba y Buena Alimentación) research program in Cuban healthy smokers living in Guantánamo and in Havana. The aim of the survey was to investigate biological and nutritional factors connected with the occurrence of zero epidemic neuropathy (EN) observed in Guantánamo urban area since the disease emerged in Cuba. Blood riboflavin status and carotenoid and selenium concentrations were higher in Guantánamo than in Havana smokers. Food dietary quantities of plantain banana, pepper (Capsicum spp.), bovine meat and milk products were higher in Guantánamo. Inversely, foods rich in cholesterol, especially eggs, were more consumed in Havana. Through riboflavin, carotenoid and selenium contents and specific antioxidants substances (indoleamines, capsaicin), the foods more consumed in Guantánamo could be considered as EN protective factors. Disease protective effects could be exerted via enhancement of defence mechanisms against free radical damage and related mechanisms focused on redox recycling of glutathione and local protection from carotenoids. Finally, the results of the present study should help Cuba, through a better EN control, to improve long-term food safety and define healthier dietary habits.

  10. Epidemic as a natural process.

    Science.gov (United States)

    Koivu-Jolma, Mikko; Annila, Arto

    2018-05-01

    Mathematical epidemiology is a well-recognized discipline to model infectious diseases. It also provides guidance for public health officials to limit outbreaks. Nevertheless, epidemics take societies by surprise every now and then, for example, when the Ebola virus epidemic raged seemingly unrestrained in Western Africa. We provide insight to this capricious character of nature by describing the epidemic as a natural process, i.e., a phenomenon governed by thermodynamics. Our account, based on statistical mechanics of open systems, clarifies that it is impossible to predict accurately epidemic courses because everything depends on everything else. Nonetheless, the thermodynamic theory yields a comprehensive and analytical view of the epidemic. The tenet subsumes various processes in a scale-free manner from the molecular to the societal levels. The holistic view accentuates overarching procedures in arresting and eradicating epidemics. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa

    Directory of Open Access Journals (Sweden)

    Clement Nyamunura Mweya

    2013-10-01

    Full Text Available Background: The East African region has experienced several Rift Valley fever (RVF outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. Methods: Diverse ecological niche modelling techniques have been developed for this purpose: we present a maximum entropy (Maxent approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Results: Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Conclusion: Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

  12. Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa.

    Science.gov (United States)

    Mweya, Clement Nyamunura; Kimera, Sharadhuli Iddi; Kija, John Bukombe; Mboera, Leonard E G

    2013-01-01

    The East African region has experienced several Rift Valley fever (RVF) outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. DIVERSE ECOLOGICAL NICHE MODELLING TECHNIQUES HAVE BEEN DEVELOPED FOR THIS PURPOSE: we present a maximum entropy (Maxent) approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex) responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

  13. Factors influencing psychological distress during a disease epidemic: Data from Australia's first outbreak of equine influenza

    Directory of Open Access Journals (Sweden)

    Stevens Garry J

    2008-10-01

    Full Text Available Abstract Background In 2007 Australia experienced its first outbreak of highly infectious equine influenza. Government disease control measures were put in place to control, contain, and eradicate the disease; these measures included movement restrictions and quarantining of properties. This study was conducted to assess the psycho-social impacts of this disease, and this paper reports the prevalence of, and factors influencing, psychological distress during this outbreak. Methods Data were collected using an online survey, with a link directed to the affected population via a number of industry groups. Psychological distress, as determined by the Kessler 10 Psychological Distress Scale, was the main outcome measure. Results In total, 2760 people participated in this study. Extremely high levels of non-specific psychological distress were reported by respondents in this study, with 34% reporting high psychological distress (K10 > 22, compared to levels of around 12% in the Australian general population. Analysis, using backward stepwise binary logistic regression analysis, revealed that those living in high risk infection (red zones (OR = 2.00; 95% CI: 1.57–2.55; p Conclusion Although, methodologically, this study had good internal validity, it has limited generalisability because it was not possible to identify, bound, or sample the target population accurately. However, this study is the first to collect psychological distress data from an affected population during such a disease outbreak and has potential to inform those involved in assessing the potential psychological impacts of human infectious diseases, such as pandemic influenza.

  14. The Challenge of Controlling the COPD Epidemic Chronic Obstructive Pulmonary Disease: Unmet Needs.

    Science.gov (United States)

    Polverino, Francesca; Celli, Bartolome

    2018-05-17

    Many unmet needs still remain in the assessment and treatment of patients with chronic obstructive pulmonary disease (COPD), particularly in relation to its under- and misdiagnosis, which lead to under- and mistreatment. This paucity of knowledge about the importance and presence of COPD, as well as its treatment, is seen with patients and carers as well as healthcare providers. This review considers the areas of key educational need, including the clinical characteristics of COPD, factors contributing to the disease, effective diagnosis, and clinical management of patients, and the implementation of treatment guidelines. As COPD remains the third most frequent cause of death in the world, we must continue to expand the scope and reach of our efforts to improve outcomes in this debilitating disease. Copyright © 2018. Published by Elsevier Inc.

  15. Economics of eradicating Foot-and-Mouth disease epidemics with alternative control strategies

    NARCIS (Netherlands)

    Bergevoet, R.H.M.; Asseldonk, van M.A.P.M.

    2014-01-01

    The paper presents an economic analysis of Foot-and-Mouth Disease (FMD) control strategies for livestock herds. Alternative vaccination-to-live control strategies were compared to the strategy that involves culling of all susceptible animals in an area of 1 km around infected herds in addition to

  16. Surveillance of emerging diseases in cattle : Application to the Schmallenberg virus epidemic in the Netherlands

    NARCIS (Netherlands)

    Veldhuis, A.M.B.

    2016-01-01

    Animal health surveillance is an essential component to protect animal health, facilitate trade, and protect public health. Reliable surveillance systems are able to rapidly identify outbreaks of emerging animal diseases in previously free areas to enable the implementation of control measures. In

  17. 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.

  18. Dialysis enrollment patterns in Guatemala: evidence of the chronic kidney disease of non-traditional causes epidemic in Mesoamerica.

    Science.gov (United States)

    Laux, Timothy S; Barnoya, Joaquin; Guerrero, Douglas R; Rothstein, Marcos

    2015-04-14

    In western Nicaragua and El Salvador, chronic kidney disease (CKD) is highly prevalent and generally affects young, male, agricultural (usually sugar cane) workers without the established CKD risk factors. It is yet unknown if the prevalence of this CKD of Non-Traditional causes (CKDnT) extends to the northernmost Central American country, Guatemala. Therefore, we sought to compare dialysis enrollment rates by region, municipality, sex, daily temperature, and agricultural production in Guatemala and assess if there is a similar CKDnT distribution pattern as in Nicaragua and El Salvador. The National Center for Chronic Kidney Disease Treatment (Unidad Nacional de Atención al Enfermo Renal Crónico) is the largest provider of dialysis in Guatemala. We used population, Human Development Index, literacy, and agricultural databases to assess the geographic, economic, and educational correlations with the National Center for Chronic Kidney Disease Treatment's hemodialysis and peritoneal dialysis enrollment database. Enrollment rates (per 100 000) inhabitants were compared by region and mapped for comparison to regional agricultural and daytime temperature data. The distribution of men and women enrolled in dialysis were compared by region using Fisher's exact tests. Spearman's rank correlation coefficients were calculated. Dialysis enrollment is higher in the Southwest compared to the rest of the country where enrollees are more likely (p Guatemala. In Guatemala, CKDnT incidence may have a similar geographic distribution as Nicaragua and El Salvador (higher in the high temperature and sugar cane growing regions). Therefore, it is likely that the CKNnT epidemic extends throughout the Mesoamerican region.

  19. 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.

  20. Cyclical changes in seroprevalence of leptospirosis in California sea lions: endemic and epidemic disease in one host species?

    Directory of Open Access Journals (Sweden)

    St Leger Judy

    2007-11-01

    Full Text Available Abstract Background Leptospirosis is a zoonotic disease infecting a broad range of mammalian hosts, and is re-emerging globally. California sea lions (Zalophus californianus have experienced recurrent outbreaks of leptospirosis since 1970, but it is unknown whether the pathogen persists in the sea lion population or is introduced repeatedly from external reservoirs. Methods We analyzed serum samples collected over an 11-year period from 1344 California sea lions that stranded alive on the California coast, using the microscopic agglutination test (MAT for antibodies to Leptospira interrogans serovar Pomona. We evaluated seroprevalence among yearlings as a measure of incidence in the population, and characterized antibody persistence times based on temporal changes in the distribution of titer scores. We conducted multinomial logistic regression to determine individual risk factors for seropositivity with high and low titers. Results The serosurvey revealed cyclical patterns in seroprevalence to L. interrogans serovar Pomona, with 4–5 year periodicity and peak seroprevalence above 50%. Seroprevalence in yearling sea lions was an accurate index of exposure among all age classses, and indicated on-going exposure to leptospires in non-outbreak years. Analysis of titer decay rates showed that some individuals probably maintain high titers for more than a year following exposure. Conclusion This study presents results of an unprecedented long-term serosurveillance program in marine mammals. Our results suggest that leptospirosis is endemic in California sea lions, but also causes periodic epidemics of acute disease. The findings call into question the classical dichotomy between maintenance hosts of leptospirosis, which experience chronic but largely asymptomatic infections, and accidental hosts, which suffer acute illness or death as a result of disease spillover from reservoir species.

  1. Viral meningitis epidemics and a single, recent, recombinant and anthroponotic origin of swine vesicular disease virus

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne; Nielsen, Sandra Cathrine Abel; Samaniego Castruita, Jose Alfredo

    2015-01-01

    BACKGROUND AND OBJECTIVES: Swine vesicular disease virus (SVDV) is a close relative of the human Enterovirus B serotype, coxsackievirus B5. As the etiological agent of a significant emergent veterinary disease, several studies have attempted to explain its origin. However, several key questions...... and non-coding regions supports that SVDV has a recombinant origin between coxsackievirus B5 and another Enterovirus B serotype, most likely coxsackievirus A9. Extensive Bayesian sequence-based analysis of the time of the most recent common ancestor of all analysed sequences places this within a few years...... around 1961. Epidemiological evidence points to China as an origin, but there are no available samples to test this conclusively. CONCLUSIONS AND IMPLICATIONS: Historical investigation and the clinical aspects of the involved Enterovirus B serotypes, makes the current results consistent with a hypothesis...

  2. Comparison of an Agent-based Model of Disease Propagation with the Generalised SIR Epidemic Model

    Science.gov (United States)

    2009-08-01

    utilising 10 metre square buildings with the outcome of in-building combat resolved using a modified Lanchester equation. This limited the usefulness of...observations and the Australian Army’s “Future Land Warfighting Concept – Complex Warfare ” [9] document that highlighted three inter-related complex...by military commanders wishing to assess the impact of disease (naturally occurring or through deliberate biological warfare attack) on their

  3. Distribution of cow-calf producers' beliefs about reporting cattle with clinical signs of foot-and-mouth disease to a veterinarian before or during a hypothetical outbreak.

    Science.gov (United States)

    Delgado, Amy H; Norby, Bo; Scott, H Morgan; Dean, Wesley; McIntosh, W Alex; Bush, Eric

    2014-12-01

    Understanding the prevalence of cattle producers' beliefs regarding disease reporting can help officials improve surveillance programs with passive data collection. A cross-sectional survey was conducted in Texas in 2008 and 2009 to determine beliefs about reporting cattle with clinical signs consistent with foot-and-mouth disease (FMD) either prior to (scenario 1) or during an on-going outbreak of FMD (scenario 2). Two questionnaires were developed and distributed to Texas cow-calf producers in order to evaluate their behavioral, control, and normative beliefs related to disease reporting. The context for each behavior was provided through the use of scenarios, and belief strength was measured using a 7-point Likert-like scale. Beliefs were compared across scenarios and demographic categories, and the effect of scenario on belief examined using ordinal logistic regression. Respondents agreed that reporting clinically suspect cases would have positive economic and emotional consequences; however, when an outbreak was known to be present, producers were less likely to agree with many of the positive outcomes of reporting. Important barriers to disease reporting indicated by producers included a lack of knowledge related to clinical signs of highly contagious cattle diseases and which cattle are at risk of contracting FMD. In general, beliefs about barriers to reporting did not differ based on scenario. Veterinarians and regulatory authorities were the groups perceived to most strongly expect disease reporting, regardless of the scenario. Risk education for producers related to clinical signs of reportable livestock diseases, post-reporting procedures, and an understanding of FMD introduction and spread may improve the reporting of cattle with clinical signs consistent with FMD. Published by Elsevier B.V.

  4. Assessing Hypothetical Gravity Control Propulsion

    OpenAIRE

    Millis, Marc G.

    2006-01-01

    Gauging the benefits of hypothetical gravity control propulsion is difficult, but addressable. The major challenge is that such breakthroughs are still only notional concepts rather than being specific methods from which performance can be rigorously quantified. A recent assessment by Tajmar and Bertolami used the rocket equation to correct naive misconceptions, but a more fundamental analysis requires the use of energy as the basis for comparison. The energy of a rocket is compared to an ide...

  5. Using multitype branching processes to quantify statistics of disease outbreaks in zoonotic epidemics.

    Science.gov (United States)

    Singh, Sarabjeet; Schneider, David J; Myers, Christopher R

    2014-03-01

    Branching processes have served as a model for chemical reactions, biological growth processes, and contagion (of disease, information, or fads). Through this connection, these seemingly different physical processes share some common universalities that can be elucidated by analyzing the underlying branching process. In this work we focus on coupled branching processes as a model of infectious diseases spreading from one population to another. An exceedingly important example of such coupled outbreaks are zoonotic infections that spill over from animal populations to humans. We derive several statistical quantities characterizing the first spillover event from animals to humans, including the probability of spillover, the first passage time distribution for human infection, and disease prevalence in the animal population at spillover. Large stochastic fluctuations in those quantities can make inference of the state of the system at the time of spillover difficult. Focusing on outbreaks in the human population, we then characterize the critical threshold for a large outbreak, the distribution of outbreak sizes, and associated scaling laws. These all show a strong dependence on the basic reproduction number in the animal population and indicate the existence of a novel multicritical point with altered scaling behavior. The coupling of animal and human infection dynamics has crucial implications, most importantly allowing for the possibility of large human outbreaks even when human-to-human transmission is subcritical.

  6. Using multitype branching processes to quantify statistics of disease outbreaks in zoonotic epidemics

    Science.gov (United States)

    Singh, Sarabjeet; Schneider, David J.; Myers, Christopher R.

    2014-03-01

    Branching processes have served as a model for chemical reactions, biological growth processes, and contagion (of disease, information, or fads). Through this connection, these seemingly different physical processes share some common universalities that can be elucidated by analyzing the underlying branching process. In this work we focus on coupled branching processes as a model of infectious diseases spreading from one population to another. An exceedingly important example of such coupled outbreaks are zoonotic infections that spill over from animal populations to humans. We derive several statistical quantities characterizing the first spillover event from animals to humans, including the probability of spillover, the first passage time distribution for human infection, and disease prevalence in the animal population at spillover. Large stochastic fluctuations in those quantities can make inference of the state of the system at the time of spillover difficult. Focusing on outbreaks in the human population, we then characterize the critical threshold for a large outbreak, the distribution of outbreak sizes, and associated scaling laws. These all show a strong dependence on the basic reproduction number in the animal population and indicate the existence of a novel multicritical point with altered scaling behavior. The coupling of animal and human infection dynamics has crucial implications, most importantly allowing for the possibility of large human outbreaks even when human-to-human transmission is subcritical.

  7. Structural responses to the obesity and non-communicable diseases epidemic: the Chilean Law of Food Labeling and Advertising.

    Science.gov (United States)

    Corvalán, C; Reyes, M; Garmendia, M L; Uauy, R

    2013-11-01

    In 12 July 2012, the Chilean Senate approved the Law of Food Labeling and Advertising, resulting from the joint efforts of a group of health professionals, researchers and legislators who proposed a regulatory framework in support of healthy diets and active living. Its goal was to curb the ongoing epidemic increase of obesity and non-communicable diseases. Two actions included: (i) improving point of food purchase consumer information by incorporating easy-to-understand front-of-packages labeling and specific messages addressing critical nutrients, and (ii) decreasing children's exposure to unhealthy foods by restricting marketing, advertising and sales. We summarize the work related to the law's release and discuss the conclusions reached by the various expert committees that were convened by the Ministry of Health to guide the development of the regulatory norms. Throughout the process, the food industry has overtly expressed its disagreement with the regulatory effort. The final content of the regulatory norms is still pending; however there are suggestions that its implementation will be delayed and might be modified based on the industry lobbying actions. These lessons should contribute to show the need of anticipating and addressing potential barriers to obesity-prevention policy implementation, particularly with respect to the role of the private sector. © 2013 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of the International Association for the Study of Obesity.

  8. Considerations of scale in the analysis of spatial pattern of plant disease epidemics.

    Science.gov (United States)

    Turechek, William W; McRoberts, Neil

    2013-01-01

    Scale is an important but somewhat neglected subject in plant pathology. Scale serves as an abstract concept, providing a framework for organizing observations and theoretical models, and plays a functional role in the organization of ecological communities and physical processes. Rich methodological resources are available to plant pathologists interested in considering either or both aspects of scale in their research. We summarize important concepts in both areas of the literature, particularly as they apply to the spatial pattern of plant disease, and highlight some new results that emphasize the importance of scaling on the emergence of different types of probability distribution in empirical observation. We also highlight the important links between heterogeneity and scale, which are of central importance in plant disease epidemiology and the analysis of spatial pattern. We consider statistical approaches that are available, where actual physical scale is known, and for more conceptual research on hierarchies, where scale plays a more abstract role, particularly for field-based research. For the latter, we highlight methods that plant pathologists could consider to account for the effect of scale in the design of field studies.

  9. The role of international migration in infectious diseases: the HIV epidemic and its trends in Japan.

    Science.gov (United States)

    Komatsu, Ryuichi; Sawada, Takashi

    2007-01-01

    Globalization and its associated international migrations facilitate the spread of infectious diseases. This article reports trends in and discusses the relation between international migration and HIV infection in Japan. The authors analyze relevant literature, drawing on government and other sources. Among foreigners in Japan, there were 27.0 reported HIV and 9.3 reported AIDS cases per million in 1990, and 52.9 HIV and 38.8 AIDS cases per million in 2000. These rates were initially 45 to 90 times the population prevalence of HIV and AIDS among Japanese, but are now only 10 to 20 times the prevalence among Japanese, as HIV becomes an increasing problem for the Japanese population. HIV-infected foreigners who are uninsured are at a disadvantage for diagnosis, counseling, and treatment compared with insured persons, and at a significantly higher risk for low CD4 counts. For all sections of Japan's population, counseling and testing are inadequate, and surveillance of behavioral risk, infection, and disease is limited. International migrants are at increased risk for HIV transmission and at a disadvantage for care and treatment. Japan needs both to develop policies that assist migrants and to respond to the growing threat among its nonmigrant population.

  10. Predicting and Evaluating the Epidemic Trend of Ebola Virus Disease in the 2014-2015 Outbreak and the Effects of Intervention Measures.

    Directory of Open Access Journals (Sweden)

    Zuiyuan Guo

    Full Text Available We constructed dynamic Ebola virus disease (EVD transmission models to predict epidemic trends and evaluate intervention measure efficacy following the 2014 EVD epidemic in West Africa. We estimated the effective vaccination rate for the population, with basic reproduction number (R0 as the intermediate variable. Periodic EVD fluctuation was analyzed by solving a Jacobian matrix of differential equations based on a SIR (susceptible, infective, and removed model. A comprehensive compartment model was constructed to fit and predict EVD transmission patterns, and to evaluate the effects of control and prevention measures. Effective EVD vaccination rates were estimated to be 42% (31-50%, 45% (42-48%, and 51% (44-56% among susceptible individuals in Guinea, Liberia and Sierra Leone, respectively. In the absence of control measures, there would be rapid mortality in these three countries, and an EVD epidemic would be likely recur in 2035, and then again 8~9 years later. Oscillation intervals would shorten and outbreak severity would decrease until the periodicity reached ~5.3 years. Measures that reduced the spread of EVD included: early diagnosis, treatment in isolation, isolating/monitoring close contacts, timely corpse removal, post-recovery condom use, and preventing or quarantining imported cases. EVD may re-emerge within two decades without control and prevention measures. Mass vaccination campaigns and control and prevention measures should be instituted to prevent future EVD epidemics.

  11. 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...

  12. 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].

  13. 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......Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of host species, the enormous quantities of virus liberated by infected animals, the range of excretions...

  14. Global health security: the wider lessons from the west African Ebola virus disease epidemic

    Science.gov (United States)

    Heymann, David L; Chen, Lincoln; Takemi, Keizo; Fidler, David P; Tappero, Jordan W; Thomas, Mathew J; Kenyon, Thomas A; Frieden, Thomas R; Yach, Derek; Nishtar, Sania; Kalache, Alex; Olliaro, Piero L; Horby, Peter; Torreele, Els; Gostin, Lawrence O; Ndomondo-Sigonda, Margareth; Carpenter, Daniel; Rushton, Simon; Lillywhite, Louis; Devkota, Bhimsen; Koser, Khalid; Yates, Rob; Dhillon, Ranu S; Rannan-Eliya, Ravi P

    2018-01-01

    The Ebola virus disease outbreak in West Africa was unprecedented in both its scale and impact. Out of this human calamity has come renewed attention to global health security—its definition, meaning, and the practical implications for programmes and policy. For example, how does a government begin to strengthen its core public health capacities, as demanded by the International Health Regulations? What counts as a global health security concern? In the context of the governance of global health, including WHO reform, it will be important to distil lessons learned from the Ebola outbreak. The Lancet invited a group of respected global health practitioners to reflect on these lessons, to explore the idea of global health security, and to offer suggestions for next steps. Their contributions describe some of the major threats to individual and collective human health, as well as the values and recommendations that should be considered to counteract such threats in the future. Many different perspectives are proposed. Their common goal is a more sustainable and resilient society for human health and wellbeing. PMID:25987157

  15. [History of human epidemic and endemic diseases in the southwest Indian Ocean].

    Science.gov (United States)

    Gaüzère, B-A; Aubry, P

    2013-05-01

    Smallpox has been known in the Mascarene Islands since 1729, and in 1898, the vaccinogenic and anti-rabies Institute of Tananarive, the future Pasteur Institute of Madagascar, was created to combat it. Cholera first arrived in the Mascarenes in 1819, but did not affect the Comoros Islands and Madagascar until the current pandemic. Bubonic plague has beset the ports of Madagascar and the Mascarenes since 1898. Girard and Robic developed the anti-plague vaccine in 1931 at the Pasteur Institute of Madagascar. The Mascarenes lost their reputation as Eden when malaria arrived in 1841, and this disease remains prominent in Madagascar and Comoros. Leprosy has been known in La Réunion since 1726 and is still very present in Mayotte, Anjouan, and Madagascar. Leptospirosis is a public health problem, except in Madagascar and the Comoros. Dengue, chikungunya, and Rift Valley fever are also present. HIV/AIDS is not a major concern, except in Mauritius, where it was spread by injection drug use, in the Seychelles and in Madagascar's largest cities. Madagascar is the principal site worldwide of chromoblastomycosis, first described there in 1914.

  16. Coverage of the Ebola Virus Disease Epidemic on YouTube.

    Science.gov (United States)

    Basch, Corey H; Basch, Charles E; Ruggles, Kelly V; Hammond, Rodney

    2015-10-01

    The recent Ebola virus disease (EVD) outbreak in 2014-2015 has been the largest and longest lasting to date. Media coverage about the outbreak has been extensive, but there are large gaps in our understanding of the ways in which widely accessed social media sites are used during times of public health crisis. The purpose of this study was to analyze widely viewed videos about EVD on the YouTube video-sharing site. We coded the source, content, and characteristics of the 100 most widely viewed videos about EVD on YouTube. The videos included in the sample were viewed more than 73 million times. The death toll in West Africa was mentioned in nearly one-third of the videos. Over one-third of the videos mentioned how EVD was generally transmitted. There was little mention of treatment and no mention of the need for US funding of disaster preparedness; coordination between local, state, and federal governments; or beds ready for containment. No significant differences in the number of views were identified between video sources with the exception of a significantly higher number of views for "consumer videos" compared with "commercial television videos." With 1 billion unique users a month, YouTube has potential for both enhancing education and spreading misinformation.

  17. Optimal control problem in correlation between smoking and epidemic of respiratory diseases

    Science.gov (United States)

    Aldila, D.; Apri, M.

    2014-02-01

    Smoking appears to be a risk factor that may increase the number of different pulmonary infections. This link is likely to be mediated by smoking adverse effects on the respiratory defenses. A mathematical model to describe correlation between the number of smokers and its effect on the number of infected people suffer from respiratory disease like influenza is constructed in this paper. Promotion of healthy life is accounted in the model as an optimal control problem to reduce the number of smokers. In this work, the transition rates from smokers to non-smokers and from non-smokers to smokers are regarded as the control variables. Assuming the control variables are constant, equilibrium points of the model can be obtained analytically. The basic reproductive ratio as the endemic threshold is taken from the spectral radius of the next-generation matrix. Using numerical simulation, we show that the healthy life promotion can reduce the number of infected person significantly by reducing the number of smokers. Furthermore, different initial conditions to show different situations in the field are also simulated. It is shown that a large effort to increase the transition rate from smokers to non-smokers and to reduce the transition from non-smokers to smokers should be applied in the endemic reduction scenario.

  18. Preventing a Cardiovascular Disease Epidemic among Indigenous Populations through Lifestyle Changes

    Directory of Open Access Journals (Sweden)

    Lee Stoner

    2012-01-01

    Full Text Available Cardiovascular disease (CVD is the driving force behind the discrepancy in life expectancy between indigenous and non-indigenous groups in many countries. Preceding CVD many indigenous groups exhibit a cluster of cardiometabolic risk factors, including overweight-obesity, diabetes, high cholesterol, and high blood pressure. In turn, modifiable lifestyle risk factors contribute to the development of this cluster of cardiometabolic conditions. Modifiable lifestyle risk factors include, but are not limited to, physical inactivity, poor nutrition, excessive alcohol consumption, and cigarette smoking. Notably, these metabolic and lifestyle risk factors are relatively simple to monitor and track. The current review will look at modifiable cardiometabolic (overweight-obesity, diabetes mellitus, high cholesterol, and high blood pressure and lifestyle (physical inactivity, poor nutrition, risky alcohol behavior, and cigarette smoking risk factors among indigenous populations from Australia (Aboriginal Australians and Torres Strait Islanders, New Zealand (Mβori and the United States (Native Americans. Discussion will focus on the causal relationship between modifiable lifestyle risk factors and cardiometabolic outcomes, as well as, simple measurements for tracking these risk factors.

  19. Hyperthyroidism in cats: what's causing this epidemic of thyroid disease and can we prevent it?

    Science.gov (United States)

    Peterson, Mark

    2012-11-01

    Since first being reported in the late 1970s, there has been a dramatic increase in the prevalence of hyperthyroidism in cats. It is now recognized worldwide as the most common feline endocrine disorder. Hyperthyroidism is an important cause of morbidity in cats older than 10 years of age. It is estimated that over 10% of all senior cats will develop the disorder. Despite its frequency, the underlying cause(s) of this common disease is/are not known, and no one has suggested a means to prevent the disorder. Because of the multiple risk factors that have been described for feline hyperthyroidism, it is likely that more than one factor is involved in its pathogenesis. Continuous, lifelong exposure to environmental thyroid disruptor chemicals or goitrogens in food or water, acting together in an additive or synergistic manner, may first lead to euthyroid goiter and then to autonomous adenomatous hyperplasia, thyroid adenoma and hyperthyroidism. This review draws on published research studies to summarize the available evidence about the risk factors for feline hyperthyroidism. Based on the known goitrogens that may be present in the cat's food, drinking water or environment, it proposes measures that cat owners can implement that might prevent, or reduce the prevalence of, thyroid tumors and hyperthyroidism in their cats.

  20. Molecular insights into the mechanisms of liver-associated diseases in early-lactating dairy cows: hypothetical role of endoplasmic reticulum stress.

    Science.gov (United States)

    Ringseis, R; Gessner, D K; Eder, K

    2015-08-01

    The transition period represents the most critical period in the productive life of high-yielding dairy cows due to both metabolic and inflammatory stimuli, which challenge the liver and predispose dairy cows to develop liver-associated diseases such as fatty liver and ketosis. Despite the fact that all high-yielding dairy cows are affected by marked metabolic stress due to a severe negative energy balance (NEB) during early lactation, not all cows develop liver-associated diseases. Although the reason for this is largely unknown, this indicates that the capacity of the liver to cope with metabolic and inflammatory challenges varies between individual high-yielding dairy cows. Convincing evidence exists that endoplasmic reticulum (ER) stress plays a key role in the development of fatty liver, and it has been recently shown that ER stress occurs in the liver of high-yielding dairy cows. This indicates that ER stress may be involved in the development of liver-associated diseases in dairy cows. The present review shows that the liver of dairy cows during early lactation is exposed to several metabolic and inflammatory challenges, such as non-esterified fatty acids, tumour necrosis factor α, interleukin-1β, reactive oxygen species and lipopolysaccharides, which are known inducers of ER stress. Thus, ER stress may represent a molecular basis for fatty liver development and account for the frequent occurrence of fatty liver and ketosis in high-yielding dairy cows. Interindividual differences between dairy cows in the activation of hepatic stress response pathways, such as nuclear factor E2-related factor 2, which is activated during ER stress and reduces the sensitivity of tissues to oxidative and inflammatory damage, might provide an explanation at the molecular level for differences in the capacity to cope with pathological inflammatory challenges during early lactation and the susceptibility to develop liver-associated diseases between early-lactating dairy cows

  1. Heterogeneity in District-Level Transmission of Ebola Virus Disease during the 2013-2015 Epidemic in West Africa.

    Directory of Open Access Journals (Sweden)

    Fabienne Krauer

    2016-07-01

    Full Text Available The Ebola virus disease (EVD epidemic in West Africa in 2013-2015 spread heterogeneously across the three hardest-hit countries Guinea, Liberia and Sierra Leone and the estimation of national transmission of EVD provides little information about local dynamics. To investigate district-level transmissibility of EVD, we applied a statistical modelling approach to estimate the basic reproduction number (R0 for each affected district and each country using weekly incident case numbers. We estimated growth rates during the early exponential phase of the outbreak using exponential regression of the case counts on the first eight weeks since onset. To take into account the heterogeneity between and within countries, we fitted a mixed effects model and calculated R0 based on the predicted individual growth rates and the reported serial interval distribution. At district level, R0 ranged from 0.36 (Dubréka to 1.72 (Beyla in Guinea, from 0.53 (Maryland to 3.37 (Margibi in Liberia and from 1.14 (Koinadugu to 2.73 (Western Rural in Sierra Leone. At national level, we estimated an R0 of 0.97 (95% CI 0.77-1.18 for Guinea, 1.26 (95% CI 0.98-1.55 for Liberia and 1.66 (95% CI 1.32-2.00 for Sierra Leone. Socio-demographic variables related to urbanisation such as high population density and high wealth index were found positively associated with R0 suggesting that the consequences of fast urban growth in West Africa may have contributed to the increased spread of EVD.

  2. How is Indonesia coping with its epidemic of chronic noncommunicable diseases? A systematic review with meta-analysis

    Science.gov (United States)

    Wall, Stig; Hakimi, Mohammad; Dewi, Fatwa Sari Tetra; Weinehall, Lars; Nichter, Mark; Nilsson, Maria; Kusnanto, Hari; Rahajeng, Ekowati; Ng, Nawi

    2017-01-01

    Background Chronic noncommunicable diseases (NCDs) have emerged as a huge global health problem in low- and middle-income countries. The magnitude of the rise of NCDs is particularly visible in Southeast Asia where limited resources have been used to address this rising epidemic, as in the case of Indonesia. Robust evidence to measure growing NCD-related burdens at national and local levels and to aid national discussion on social determinants of health and intra-country inequalities is needed. The aim of this review is (i) to illustrate the burden of risk factors, morbidity, disability, and mortality related to NCDs; (ii) to identify existing policy and community interventions, including disease prevention and management strategies; and (iii) to investigate how and why an inequitable distribution of this burden can be explained in terms of the social determinants of health. Methods Our review followed the PRISMA guidelines for identifying, screening, and checking the eligibility and quality of relevant literature. We systematically searched electronic databases and gray literature for English- and Indonesian-language studies published between Jan 1, 2000 and October 1, 2015. We synthesized included studies in the form of a narrative synthesis and where possible meta-analyzed their data. Results On the basis of deductive qualitative content analysis, 130 included citations were grouped into seven topic areas: risk factors; morbidity; disability; mortality; disease management; interventions and prevention; and social determinants of health. A quantitative synthesis meta-analyzed a subset of studies related to the risk factors smoking, obesity, and hypertension. Conclusions Our findings echo the urgent need to expand routine risk factor surveillance and outcome monitoring and to integrate these into one national health information system. There is a stringent necessity to reorient and enhance health system responses to offer effective, realistic, and affordable ways

  3. CARNSORE: Hypothetical reactor accident study

    International Nuclear Information System (INIS)

    Walmod-Larsen, O.; Jensen, N.O.; Kristensen, L.; Meide, A.; Nedergaard, K.L.; Nielsen, F.; Lundtang Petersen, E.; Petersen, T.; Thykier-Nielsen, S.

    1984-06-01

    Two types of design-basis accident and a series of hypothetical core-melt accidents to a 600 MWe reactor are described and their consequences assessed. The PLUCON 2 model was used to calculate the consequences which are presented in terms of individual and collective doses, as well as early and late health consequences. The site proposed for the nucelar power station is Carnsore Point, County Wexford, south-east Ireland. The release fractions for the accidents described are those given in WASH-1400. The analyses are based on the resident population as given in the 1979 census and on 20 years of data from the meteorological stations at Rosslare Harbour, 8.5 km north of the site. The consequences of one of the hypothetical core-melt accidents are described in detail in a meteorological parametric study. Likewise the consequences of the worst conceivable combination of situations are described. Finally, the release fraction in one accident is varied and the consequences of a proposed, more probable ''Class 9 accident'' are presented. (author)

  4. Pin1, a new player in the fate of HIF-1α degradation: an hypothetical mechanism inside vascular damage as Alzheimer’s disease risk factor.

    Directory of Open Access Journals (Sweden)

    Elena eLonati

    2014-01-01

    Full Text Available Aetiology of neurodegenerative mechanisms underlying Alzheimer's disease (AD are still under elucidation. The contribution of cerebrovascular deficiencies (such as cerebral ischemia/stroke has been strongly endorsed in recent years. Reduction of blood supply leading to hypoxic condition is known to activate cellular responses mainly controlled by hypoxia-inducible transcription factor-1 (HIF-1. Thus alterations of oxygen responsive HIF-1α subunit in the central nervous system may contribute to the cognitive decline, especially influencing mechanisms associated to APP (amyloid precursor protein amyloidogenic metabolism. Although HIF-1α protein level is known to be regulated by von Hippel-Lindau (VHL ubiquitin-proteasome system, it has been recently suggested that Gsk-3β (glycogen synthase kinase-3β promotes a VHL-independent HIF-1α degradation. Here we provide evidences that in rat primary hippocampal cell cultures, HIF-1α degradation might be mediated by a synergic action of Gsk-3β and Pin1 (peptidyl-prolyl cis/trans isomerase. In post-ischemic conditions, such as those mimicked with oxygen glucose deprivation (OGD, HIF-1α protein level increases remaining unexpectedly high for long time after normal condition restoration jointly with the increase of LDH (lactate dehydrogenase and BACE1 (β-secretase 1 protein expression (70% and 140% respectively. Interestingly the Pin1 activity decreases about 40%-60% and Pin1S16 inhibitory phosphorylation significantly increases, indicating that Pin1 binding to its substrate and enzymatic activity are reduced by treatment. Co-immunoprecipitation experiments demonstrate that HIF-1α/Pin1 in normoxia are associated, and that in presence of specific Pin1 and Gsk-3β inhibitors their interaction is reduced in parallel to an increase of HIF-1α protein level. Thus we suggest that in post-OGD neurons the high level of HIF-1α might be due to Pin1 binding ability and activity reduction which affects HIF-1

  5. Restricted Predicates for Hypothetical Datalog

    Directory of Open Access Journals (Sweden)

    Fernando Sáenz-Pérez

    2015-12-01

    Full Text Available Hypothetical Datalog is based on an intuitionistic semantics rather than on a classical logic semantics, and embedded implications are allowed in rule bodies. While the usual implication (i.e., the neck of a Horn clause stands for inferring facts, an embedded implication plays the role of assuming its premise for deriving its consequence. A former work introduced both a formal framework and a goal-oriented tabled implementation, allowing negation in rule bodies. While in that work positive assumptions for both facts and rules can occur in the premise, negative assumptions are not allowed. In this work, we cover this subject by introducing a new concept: a restricted predicate, which allows negative assumptions by pruning the usual semantics of a predicate. This new setting has been implemented in the deductive system DES.

  6. Epidemics on interconnected networks

    Science.gov (United States)

    Dickison, Mark; Havlin, S.; Stanley, H. E.

    2012-06-01

    Populations are seldom completely isolated from their environment. Individuals in a particular geographic or social region may be considered a distinct network due to strong local ties but will also interact with individuals in other networks. We study the susceptible-infected-recovered process on interconnected network systems and find two distinct regimes. In strongly coupled network systems, epidemics occur simultaneously across the entire system at a critical infection strength βc, below which the disease does not spread. In contrast, in weakly coupled network systems, a mixed phase exists below βc of the coupled network system, where an epidemic occurs in one network but does not spread to the coupled network. We derive an expression for the network and disease parameters that allow this mixed phase and verify it numerically. Public health implications of communities comprising these two classes of network systems are also mentioned.

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

    Science.gov (United States)

    Mikkelsen, T.; Alexandersen, S.; Astrup, P.; Champion, H. J.; Donaldson, A. I.; Dunkerley, F. N.; Gloster, J.; Sørensen, J. H.; Thykier-Nielsen, S.

    2003-11-01

    Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of host species, the enormous quantities of virus liberated by infected animals, the range of excretions 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 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 the potential for atmospheric dispersion of the disease. The operational value of such modelling is primarily to identify premises which may have been exposed so that the human resources for surveillance and disease control purposes are employed most effectively. The paper describes the combined modelling 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 paper (Gloster et al., 2002) provides a more detailed analysis of the airborne disease transmission in the vicinity of Burnside Farm. The combined results are consistent with airborne transmission of disease to livestock in the Heddon-on-the-Wall area. Local topography may have played a significant role in influencing the pattern of disease spread.

  8. Probing into the effectiveness of self-isolation policies in epidemic control

    International Nuclear Information System (INIS)

    Crokidakis, Nuno; Duarte Queirós, Sílvio M

    2012-01-01

    In this work, we inspect the reliability of controlling and quelling an epidemic disease mimicked by a susceptible–infected–susceptible (SIS) model defined on a complex network by means of current and implementable quarantine and isolation policies. Specifically, we consider that each individual in the network is originally linked to individuals of two types: members of the same household and acquaintances. The topology of this network evolves, taking into account a probability q that aims at representing the quarantine or isolation process in which the connection with acquaintances is severed according to standard policies of control of epidemics. Within current policies of self-isolation and standard infection rates, our results show that the propagation is either only controllable for hypothetical rates of compliance or not controllable at all

  9. Re-assessing the likelihood of airborne spread of foot-and-mouth disease at the start of the 1967-1968 UK foot-and-mouth disease epidemic

    DEFF Research Database (Denmark)

    Gloster, J.; Freshwater, A.; Sellers, R.F.

    2005-01-01

    The likelihood of airborne spread of foot-and-mouth disease at the start of the 1967-1968 epidemic is re-assessed in the light of current understanding of airborne disease spread. The findings strongly confirm those made at the time that airborne virus was the most likely cause of the rapid early...... development of the disease out to 60 km from the source. This conclusion is reached following a detailed epidemiological, meteorological and modelling study using original records and current modelling techniques. The role played by 'lee waves' as the mechanism for the spread is investigated. It is thought...... that they played little part in influencing the development of the epidemic. A number of lessons learned from the work are drawn, identifying the need for further research on the quantity and characteristics I of airborne virus. The results are also used to illustrate what advice would have been available...

  10. Computational structural and functional analysis of hypothetical proteins of Staphylococcus aureus

    OpenAIRE

    Mohan, Ramadevi; Venugopal, Subhashree

    2012-01-01

    Genome sequencing projects has led to an explosion of large amount of gene products in which many are of hypothetical proteins with unknown function. Analyzing and annotating the functions of hypothetical proteins is important in Staphylococcus aureus which is a pathogenic bacterium that cause multiple types of diseases by infecting various sites in humans and animals. In this study, ten hypothetical proteins of Staphylococcus aureus were retrieved from NCBI and analyzed for their structural ...

  11. Ebola Virus Disease 2013-2014 Outbreak in West Africa: An Analysis of the Epidemic Spread and Response

    Directory of Open Access Journals (Sweden)

    Orlando Cenciarelli

    2015-01-01

    Full Text Available The Ebola virus epidemic burst in West Africa in late 2013, started in Guinea, reached in a few months an alarming diffusion, actually involving several countries (Liberia, Sierra Leone, Nigeria, Senegal, and Mali. Guinea and Liberia, the first nations affected by the outbreak, have put in place measures to contain the spread, supported by international organizations; then they were followed by the other nations affected. In the present EVD outbreak, the geographical spread of the virus has followed a new route: the achievement of large urban areas at an early stage of the epidemic has led to an unprecedented diffusion, featuring the largest outbreak of EVD of all time. This has caused significant concerns all over the world: the potential reaching of far countries from endemic areas, mainly through fast transports, induced several countries to issue information documents and health supervision for individuals going to or coming from the areas at risk. In this paper the geographical spread of the epidemic was analyzed, assessing the sequential appearance of cases by geographic area, considering the increase in cases and mortality according to affected nations. The measures implemented by each government and international organizations to contain the outbreak, and their effectiveness, were also evaluated.

  12. Development of primary malignant melanoma during treatment with a TNF-α antagonist for severe Crohn’s disease: a case report and review of the hypothetical association between TNF-α blockers and cancer

    Directory of Open Access Journals (Sweden)

    Kouklakis G

    2013-03-01

    Full Text Available George Kouklakis,1 Eleni I Efremidou,2 Michael Pitiakoudis,3 Nikolaos Liratzopoulos,2 Alexandros Ch Polychronidis2 1Endoscopy Unit, 2First Surgical Department, 3Second Surgical Department, Medical School, Democritus University of Thrace, University Hospital of Alexandroupolis, Alexandroupolis, Greece Abstract: It is recognized that immunosuppression may lead to reduced immune surveillance and tumor formation. Because of the immunosuppressive properties of tumor necrosis factor (TNF-alpha (TNF-α antagonists, it is plausible that these biologics may increase the risk of the occurrence of malignancies or the reactivation of latent malignancies. TNF-α antagonists have gained momentum in the field of dermatology for treating rheumatoid arthritis and psoriasis, and they have revolutionized the treatment of other inflammatory autoimmune diseases such as refractory Crohn's disease. However, there is accumulating evidence that TNF-α inhibitors slightly increase the risk of cancer, including malignant melanoma (MM. The authors herein report the case of a 54-year-old female patient who developed a primary MM during treatment with adalimumab for severe Crohn’s disease resistant to successive medical therapies. The patient had been receiving this TNF-α blocker therapy for 3 years before the occurrence of MM. After wide surgical excision of the lesion and staging (based on Breslow thickness and Clark level, evaluation with a whole-body computed tomography scan was negative for metastatic disease. The long duration of the adalimumab therapy and the patient's lack of a predisposition to skin cancer suggest an association between anti-TNF-α drugs and melanocytic proliferation. The authors also review the literature on the potential association between anti-TNF regimens and the occurrence of malignancies such as melanocytic proliferations. There is a substantial hypothetical link between anti-TNF-α regimens such as adalimumab and the potential for cancers

  13. Epidemic cholera spreads like wildfire

    Science.gov (United States)

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

    2014-01-01

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

  14. Epidemics after Natural Disasters

    Science.gov (United States)

    Gayer, Michelle; Connolly, Maire A.

    2007-01-01

    The relationship between natural disasters and communicable diseases is frequently misconstrued. The risk for outbreaks is often presumed to be very high in the chaos that follows natural disasters, a fear likely derived from a perceived association between dead bodies and epidemics. However, the risk factors for outbreaks after disasters are associated primarily with population displacement. The availability of safe water and sanitation facilities, the degree of crowding, the underlying health status of the population, and the availability of healthcare services all interact within the context of the local disease ecology to influence the risk for communicable diseases and death in the affected population. We outline the risk factors for outbreaks after a disaster, review the communicable diseases likely to be important, and establish priorities to address communicable diseases in disaster settings. PMID:17370508

  15. 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.

  16. 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

  17. 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...

  18. Epidemic Trade

    DEFF Research Database (Denmark)

    Boerner, Lars; Severgnini, Battista

    ) of transmission of the disease between the transmitting and the receiving cities. We find that the speed depends on distance, political borders, and on the political importance of a city. Furthermore, variables related to the means of transportation like rivers and the sea, religious seasons such as Advent...

  19. Stochastic Processes in Epidemic Theory

    CERN Document Server

    Lefèvre, Claude; Picard, Philippe

    1990-01-01

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

  20. Contribution of the human immunodeficiency virus/acquired immunodeficiency syndrome epidemic to de novo presentations of heart disease in the Heart of Soweto Study cohort.

    Science.gov (United States)

    Sliwa, Karen; Carrington, Melinda J; Becker, Anthony; Thienemann, Friedrich; Ntsekhe, Mpiko; Stewart, Simon

    2012-04-01

    The contemporary impact of the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) epidemic on heart disease in South Africa (>5 million people affected) is unknown. The Heart of Soweto Study provides a unique opportunity to identify the contribution of cardiac manifestations of this epidemic to de novo presentations of heart disease in an urban African community in epidemiological transition. Chris Hani Baragwanath Hospital services the >1 million people living in Soweto, South Africa. A prospective, clinical registry captured data from all de novo cases of heart disease presenting to the Cardiology Unit during 2006-08. We describe all cases where HIV/AIDS was concurrently diagnosed. Overall, 518 of 5328 de novo cases of heart disease were identified as HIV-positive (9.7%) with 54% of these prescribed highly active anti-retroviral therapies on presentation. Women (62%) and Africans (97%) predominated with women being significantly younger than men 38 ± 13 vs. 42 ± 13 years (P = 0.002). The most common primary diagnosis attributable to HIV/AIDS was HIV-related cardiomyopathy (196 cases, 38%); being prescribed more anti-retroviral therapy (127/196 vs. 147/322; odds ratio 2.85, 95% confidence interval 1.81-3.88) with higher viral loads [median 110 000 (inter-quartile range 26 000-510 000) vs. 19 000 (3200-87 000); P = 0.018] and a lower CD4 count [median 180 (71-315) vs. 211 (96-391); P = 0.019] than the rest. An additional 128 cases (25%) were diagnosed with pericarditis/pericardial effusion with a range of other concurrent diagnoses evident, including 42 cases (8.1%) of HIV-related pulmonary arterial hypertension. Only 14 of all 581 cases of coronary artery disease (CAD) (2.4%, mean age 41 ± 13 years) were confirmed HIV-positive. Cardiac manifestations of HIV/AIDS identified within this cohort were relatively infrequent. While HIV-related cardiomyopathy and pericardial disease remain important targets for early detection and treatment in

  1. Swine enteric coronavirus disease: A review of 4 years with porcine epidemic diarrhoea virus and porcine deltacoronavirus in the United States and Canada.

    Science.gov (United States)

    Niederwerder, M C; Hesse, R A

    2018-06-01

    Swine enteric coronaviruses, including porcine epidemic diarrhoea virus (PEDV) and porcine deltacoronavirus (PDCoV), have emerged and spread throughout the North American swine industry over the last four years. These diseases cause significant losses within the pork industry and within the first year after PEDV introduction, approximately 10% of the US herd died due to the disease. Similar to other enteric coronaviruses, such as transmissible gastroenteritis virus (TGEV), these emerging swine enteric coronavirus diseases (SECD) are age-dependent, with high morbidity and mortality in neonatal pigs. Since the introduction of SECD, research has focused on investigating viral pathogenesis through experimental inoculation, increasing maternal antibody for neonatal protection, understanding transmission risks through feed and transportation, and outlining the importance of biosecurity in preventing SECD introduction and spread. A survey of swine professionals conducted for this review revealed that the majority of respondents (75%) believe SECD can be eradicated and that most herds have been successful at long-term elimination of SECD after exposure (80%). However, unique properties of SECD, such as ineffective immunity through parenteral vaccination and a low oral infectious dose, play a major role in management of SECD. This review serves to describe the current knowledge of SECD and the characteristics of these viruses which provide both opportunities and challenges for long-term disease control and potential eradication from the US swine population. © 2018 Blackwell Verlag GmbH.

  2. 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

  3. Epidemic processes in complex networks

    Science.gov (United States)

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

    2015-07-01

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

  4. Fundamental Moral Attitudes to Animals and Their Role in Judgment: An Empirical Model to Describe Fundamental Moral Attitudes to Animals and Their Role in Judgment on the Culling of Healthy Animals During an Animal Disease Epidemic

    NARCIS (Netherlands)

    Cohen, N.E.; Brom, F.W.A.; Stassen, E.N.

    2009-01-01

    In this paper, we present and defend the theoretical framework of an empirical model to describe people’s fundamental moral attitudes (FMAs) to animals, the stratification of FMAs in society and the role of FMAs in judgment on the culling of healthy animals in an animal disease epidemic. We used

  5. Household demographic determinants of Ebola epidemic risk.

    Science.gov (United States)

    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.

  6. Percolation and epidemics in random clustered networks

    Science.gov (United States)

    Miller, Joel C.

    2009-08-01

    The social networks that infectious diseases spread along are typically clustered. Because of the close relation between percolation and epidemic spread, the behavior of percolation in such networks gives insight into infectious disease dynamics. A number of authors have studied percolation or epidemics in clustered networks, but the networks often contain preferential contacts in high degree nodes. We introduce a class of random clustered networks and a class of random unclustered networks with the same preferential mixing. Percolation in the clustered networks reduces the component sizes and increases the epidemic threshold compared to the unclustered networks.

  7. 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

  8. Reducing hypothetical bias in choice experiments

    DEFF Research Database (Denmark)

    Ladenburg, Jacob; Olsen, Søren Bøye; Nielsen, Rasmus Christian Fejer

    eliminate some of the hypothetical bias. The present paper tests an addition to Cheap Talk, an Opt-Out Reminder. The Opt-Out Reminder is an objective short script presented prior to the choice sets, prompting the respondent to choose the opt-out alternative, if he/she finds the proposed policy generated...... alternatives in a choice set too expensive. The results suggest that adding an Opt-Out Reminder to Cheap Talk can in fact reduce hypothetical bias even further and reduces some of the ineffectiveness of CT in relation to the survey bid range and experienced respondents....

  9. Inferring epidemic contact structure from phylogenetic trees.

    Directory of Open Access Journals (Sweden)

    Gabriel E Leventhal

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

  10. 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.

  11. 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.

  12. Simulated epidemics in an empirical spatiotemporal network of 50,185 sexual contacts.

    Directory of Open Access Journals (Sweden)

    Luis E C Rocha

    2011-03-01

    Full Text Available Sexual contact patterns, both in their temporal and network structure, can influence the spread of sexually transmitted infections (STI. Most previous literature has focused on effects of network topology; few studies have addressed the role of temporal structure. We simulate disease spread using SI and SIR models on an empirical temporal network of sexual contacts in high-end prostitution. We compare these results with several other approaches, including randomization of the data, classic mean-field approaches, and static network simulations. We observe that epidemic dynamics in this contact structure have well-defined, rather high epidemic thresholds. Temporal effects create a broad distribution of outbreak sizes, even if the per-contact transmission probability is taken to its hypothetical maximum of 100%. In general, we conclude that the temporal correlations of our network accelerate outbreaks, especially in the early phase of the epidemics, while the network topology (apart from the contact-rate distribution slows them down. We find that the temporal correlations of sexual contacts can significantly change simulated outbreaks in a large empirical sexual network. Thus, temporal structures are needed alongside network topology to fully understand the spread of STIs. On a side note, our simulations further suggest that the specific type of commercial sex we investigate is not a reservoir of major importance for HIV.

  13. The role of subway travel in an influenza epidemic: a New York City simulation.

    Science.gov (United States)

    Cooley, Philip; Brown, Shawn; Cajka, James; Chasteen, Bernadette; Ganapathi, Laxminarayana; Grefenstette, John; Hollingsworth, Craig R; Lee, Bruce Y; Levine, Burton; Wheaton, William D; Wagener, Diane K

    2011-10-01

    The interactions of people using public transportation in large metropolitan areas may help spread an influenza epidemic. An agent-based model computer simulation of New York City's (NYC's) five boroughs was developed that incorporated subway ridership into a Susceptible-Exposed-Infected-Recovered disease model framework. The model contains a total of 7,847,465 virtual people. Each person resides in one of the five boroughs of NYC and has a set of socio-demographic characteristics and daily behaviors that include age, sex, employment status, income, occupation, and household location and membership. The model simulates the interactions of subway riders with their workplaces, schools, households, and community activities. It was calibrated using historical data from the 1957-1958 influenza pandemics and from NYC travel surveys. The surveys were necessary to enable inclusion of subway riders into the model. The model results estimate that if influenza did occur in NYC with the characteristics of the 1957-1958 pandemic, 4% of transmissions would occur on the subway. This suggests that interventions targeted at subway riders would be relatively ineffective in containing the epidemic. A number of hypothetical examples demonstrate this feature. This information could prove useful to public health officials planning responses to epidemics.

  14. Reactions to Hypothetical, Jealousy Producing Events.

    Science.gov (United States)

    Hansen, Gary L.

    1982-01-01

    Asked subjects (N=220) how they would feel about their mates' behavior in eight hypothetical situations designed to measure jealousy. Responses indicated that jealousy is likely to be a major issue. Sex role orientation is most consistently related to jealousy with sex role traditional subjects being the most jealous. (Author)

  15. Structural and Functional Annotation of Hypothetical Proteins of O139

    Directory of Open Access Journals (Sweden)

    Md. Saiful Islam

    2015-06-01

    Full Text Available In developing countries threat of cholera is a significant health concern whenever water purification and sewage disposal systems are inadequate. Vibrio cholerae is one of the responsible bacteria involved in cholera disease. The complete genome sequence of V. cholerae deciphers the presence of various genes and hypothetical proteins whose function are not yet understood. Hence analyzing and annotating the structure and function of hypothetical proteins is important for understanding the V. cholerae. V. cholerae O139 is the most common and pathogenic bacterial strain among various V. cholerae strains. In this study sequence of six hypothetical proteins of V. cholerae O139 has been annotated from NCBI. Various computational tools and databases have been used to determine domain family, protein-protein interaction, solubility of protein, ligand binding sites etc. The three dimensional structure of two proteins were modeled and their ligand binding sites were identified. We have found domains and families of only one protein. The analysis revealed that these proteins might have antibiotic resistance activity, DNA breaking-rejoining activity, integrase enzyme activity, restriction endonuclease, etc. Structural prediction of these proteins and detection of binding sites from this study would indicate a potential target aiding docking studies for therapeutic designing against cholera.

  16. 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.

    Science.gov (United States)

    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.

  17. 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.

    Science.gov (United States)

    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.

  18. An epidemic model for the interactions between thermal regime of rivers and transmission of Proliferative Kidney Disease in salmonid fish

    Science.gov (United States)

    Carraro, Luca; Bertuzzo, Enrico; Mari, Lorenzo; Gatto, Marino; Strepparava, Nicole; Hartikainen, Hanna; Rinaldo, Andrea

    2015-04-01

    Proliferative kidney disease (PKD) affects salmonid populations in European and North-American rivers. It is caused by the endoparasitic myxozoan Tetracapsuloides bryosalmonae, which exploits freshwater bryozoans (Fredericella sultana) and salmonids as primary and secondary hosts, respectively. Incidence and mortality, which can reach up to 90-100%, are known to be strongly related to water temperature. PKD has been present in brown trout population for a long time but has recently increased rapidly in incidence and severity causing a decline in fish catches in many countries. In addition, environmental changes are feared to cause PKD outbreaks at higher latitude and altitude regions as warmer temperatures promote disease development. This calls for a better comprehension of the interactions between disease dynamics and the thermal regime of rivers, in order to possibly devise strategies for disease management. In this perspective, a spatially explicit model of PKD epidemiology in riverine host metacommunities is proposed. The model aims at summarizing the knowledge on the modes of transmission of the disease and the life-cycle of the parasite, making the connection between temperature and epidemiological parameters explicit. The model accounts for both local population and disease dynamics of bryozoans and fish and hydrodynamic dispersion of the parasite spores and hosts along the river network. The model is time-hybrid, coupling inter-seasonal and intra-seasonal dynamics, the former being described in a continuous time domain, the latter seen as time steps of a discrete time domain. In order to test the model, a case study is conducted in river Wigger (Cantons of Aargau and Lucerne, Switzerland), where data about water temperature, brown trout and bryozoan populations and PKD prevalence are being collected.

  19. Elevated Annual Runoff Ratios in Pacific Northwest Catchments Impacted by Epidemic Foliage Disease of Douglas-fir

    Science.gov (United States)

    Bladon, K. D.; Bywater-Reyes, S.; LeBoldus, J. M.; Segura, C.; Ritokova, G.; Shaw, D. C.

    2017-12-01

    Catchments in the Western United States are undergoing unprecedented levels of tree die-off and/or reduced vigor due to increased severity of wildfire, drought, insect outbreaks, and disease. In the U.S. Pacific Northwest, Swiss needle cast (SNC) is the most damaging foliar disease of Douglas-fir (Pseudotsuga menziesii), physically obstructing stomata and preventing CO2 uptake and transpiration. A recent analysis in coastal Oregon indicated a substantial increase in area affected by the disease, from 530.5 km2 in 1996 to 2,387.1 km2 in 2015. Deforestation or reduced tree vigor can have profound impacts on catchment hydrology, in theory, producing increased streamflow due to reduced interception and transpiration. However, these increases have not always been detectable as impacts also depend on factors such as climate and vegetation composition. Moreover, press disturbances, such as insect outbreaks or disease, often do not result in complete removal of understorey or canopy vegetation. We analyzed trends in annual runoff ratios (quotient of discharge divided by precipitation) from 1990-2015 in 12 catchments (183-1,744 km2) in western Oregon. In general, runoff ratios increased by 10-27% in catchments with a total area of SNC >10%, with the most substantial runoff increases in catchments with SNC impacting >25% of the area. Interestingly, the most severely impacted catchment ( 90.5% SNC) showed a decrease in runoff. This is consistent with a potential compensatory response from understory western hemlock (Tsuga heterophylla) trees, a phenomenon observed in the most severely impacted sites. Findings from this study are important for assessing the impacts of biotic forest disturbances on water supply and aquatic ecosystem health.

  20. [International legal aspects of responsibility of states and international organizations for the spread of epidemics, pandemics and mass disease].

    Science.gov (United States)

    Kholikov, I V; Sazonova, K L

    2015-08-01

    The present article deals with international legal issues that arise in case when various mass diseases go beyond any national jurisdiction. The emphasis is made on the problem of international responsibility, which different actors have to bear in such cases. The authors also examine the implementation of responsibility mechanism, including the indentication of the relevant international court, authorized to establish such liability and identify the specific forms of its realization.

  1. 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....

  2. Toward a generalized theory of epidemic awareness in social networks

    Science.gov (United States)

    Wu, Qingchu; Zhu, Wenfang

    We discuss the dynamics of a susceptible-infected-susceptible (SIS) model with local awareness in networks. Individual awareness to the infectious disease is characterized by a general function of epidemic information in its neighborhood. We build a high-accuracy approximate equation governing the spreading dynamics and derive an approximate epidemic threshold above which the epidemic spreads over the whole network. Our results extend the previous work and show that the epidemic threshold is dependent on the awareness function in terms of one infectious neighbor. Interestingly, when a pow-law awareness function is chosen, the epidemic threshold can emerge in infinite networks.

  3. Be-CoDiS: A Mathematical Model to Predict the Risk of Human Diseases Spread Between Countries--Validation and Application to the 2014-2015 Ebola Virus Disease Epidemic.

    Science.gov (United States)

    Ivorra, Benjamin; Ngom, Diène; Ramos, Ángel M

    2015-09-01

    Ebola virus disease is a lethal human and primate disease that currently requires a particular attention from the international health authorities due to important outbreaks in some Western African countries and isolated cases in the UK, the USA and Spain. Regarding the emergency of this situation, there is a need for the development of decision tools, such as mathematical models, to assist the authorities to focus their efforts in important factors to eradicate Ebola. In this work, we propose a novel deterministic spatial-temporal model, called Between-Countries Disease Spread (Be-CoDiS), to study the evolution of human diseases within and between countries. The main interesting characteristics of Be-CoDiS are the consideration of the movement of people between countries, the control measure effects and the use of time-dependent coefficients adapted to each country. First, we focus on the mathematical formulation of each component of the model and explain how its parameters and inputs are obtained. Then, in order to validate our approach, we consider two numerical experiments regarding the 2014-2015 Ebola epidemic. The first one studies the ability of the model in predicting the EVD evolution between countries starting from the index cases in Guinea in December 2013. The second one consists of forecasting the evolution of the epidemic by using some recent data. The results obtained with Be-CoDiS are compared to real data and other model outputs found in the literature. Finally, a brief parameter sensitivity analysis is done. A free MATLAB version of Be-CoDiS is available at: http://www.mat.ucm.es/momat/software.htm.

  4. Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields-An ecofriendly approach.

    Science.gov (United States)

    Ghosh, Swapan Kumar; Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

    2018-01-01

    . viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields.

  5. Can epidemics be non-communicable?

    DEFF Research Database (Denmark)

    Seeberg, Jens; Meinert, Lotte

    2015-01-01

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

  6. The epidemiological characteristics of the 2007 foot-and-mouth disease epidemic in Sarpang and Zhemgang districts of Bhutan.

    Science.gov (United States)

    Dukpa, K; Robertson, I D; Ellis, T M

    2011-02-01

    This study was undertaken to compare the epidemiological characteristics of the 2007 foot-and-mouth disease outbreak in two districts of Sarpang and Zhemgang in Bhutan. Zhemgang district recorded a significantly higher cumulative incidence in all species (26.9%) as well as for cattle (29.3%) compared to Sarpang (6.5% and 7.4%, respectively). The case fatality for cattle in Zhemgang (14.1%) was significantly higher than in Sarpang (3.3%). A total of 404 cattle and 73 pigs died of FMD in Zhemgang, whereas only 21 cattle died in Sarpang. Although all four species were affected in Sarpang, no sheep or goats were affected in Zhemgang. Spatiotemporal analyses showed the existence of four significant clusters, a primary one in Sarpang and three secondary clusters in Zhemgang. The virus belonged to the PanAsia strain of the Middle-East South-Asia topotype (O serotype), and the strain was closely related to the PanAsia strain that circulated in Bhutan during the 2003/2004 outbreaks. The severity of FMD infection in Zhemgang district could be attributed to low vaccination coverage (36.5% in 2006 when compared to 87.6% in Sarpang), inadequate biosecurity, poor nursing care of the sick animals and delayed reporting to the livestock centre. This study highlights the ability of the PanAsia strain of the O serotype to cause unprecedented morbidity and mortality, especially in a naïve population. The study also highlights the benefits of maintaining good herd immunity in the susceptible population, through adequate vaccination coverage, to minimize the severity of infection and limit the spread of disease from infected to non-infected herds. © 2010 Blackwell Verlag GmbH.

  7. Enfermedad diarreica por rotavirus en brotes epidémicos Diarrheal disease caused by rotavirus in epidemic outbreaks

    Directory of Open Access Journals (Sweden)

    Jesús Reyna-Figueroa

    2012-02-01

    Full Text Available OBJETIVO: Determinar el perfil epidemiológico de los brotes de enfermedad diarreica aguda por rotavirus (RV ocurridos en pacientes pediátricos, mediante una revisión crítica de la literatura publicada entre 2000 y 2010. MÉTODOS: Se realizó una búsqueda de artículos publicados desde enero de 2000 hasta abril de 2010, recogidos por las bases de datos Artemisa, EBSCO, Embase, Imbiomed, Lilacs, Ovid, PubMed y Science Direct. En los estudios que cumplieron con los criterios de inclusión, se identificaron posibles factores de confusión y se atribuyeron riesgos de sesgo con base en el número de ítems considerados inadecuados en cada caso. Se describieron las características epidemiológicas y microbiológicas de los brotes. RESULTADOS: Solo 14 (10,8% de los 129 títulos identificados formaron parte de la muestra, los cuales sumaron 91 092 casos de diarrea aguda notificados. En 5 250 de estos casos se realizó la búsqueda de RV, la cual arrojó 1 711 (32,5% aislamientos positivos. Se observó que el RV del grupo A fue el agente causal en 100% de los brotes, mientras que el genotipo G9 fue documentado en 50% de los artículos. CONCLUSIONES: El RV, principalmente el serotipo G9, fue uno de los principales agentes responsables de los brotes de EDA en la última década. Un cuidadoso estudio de brote puede aportar información valiosa para el control y la prevención de la enfermedad por RV.OBJECTIVE: Determine the epidemiological profile of outbreaks of acute diarrheal disease caused by rotavirus (RV occurring in pediatric patients, based on a critical review of the literature published between 2000 and 2010. METHODS: A search was carried out for articles published from January 2000 to April 2010, collected by the Artemisa, EBSCO, Embase, Imbiomed, Lilacs, Ovid, PubMed, and Science Direct databases. In the studies that met the inclusion criteria, possible confounding factors were identified and risks of bias were attributed based on the

  8. Mathematical analysis and modeling of epidemics of rubber tree root diseases: Probability of infection of an individual tree

    Energy Technology Data Exchange (ETDEWEB)

    Chadoeuf, J.; Joannes, H.; Nandris, D.; Pierrat, J.C.

    1988-12-01

    The spread of root diseases in rubber tree (Hevea brasiliensis) due to Rigidoporus lignosus and Phellinus noxius was investigated epidemiologically using data collected every 6 month during a 6-year survey in a plantation. The aim of the present study is to see what factors could predict whether a given tree would be infested at the following inspection. Using a qualitative regression method we expressed the probability of pathogenic attack on a tree in terms of three factors: the state of health of the surrounding trees, the method used to clear the forest prior to planting, and evolution with time. The effects of each factor were ranked, and the roles of the various classes of neighbors were established and quantified. Variability between successive inspections was small, and the method of forest clearing was important only while primary inocula in the soil were still infectious. The state of health of the immediate neighbors was most significant; more distant neighbors in the same row had some effect; interrow spread was extremely rare. This investigation dealt only with trees as individuals, and further study of the interrelationships of groups of trees is needed.

  9. Estimating the future number of cases in the Ebola epidemic--Liberia and Sierra Leone, 2014-2015.

    Science.gov (United States)

    Meltzer, Martin I; Atkins, Charisma Y; Santibanez, Scott; Knust, Barbara; Petersen, Brett W; Ervin, Elizabeth D; Nichol, Stuart T; Damon, Inger K; Washington, Michael L

    2014-09-26

    The first cases of the current West African epidemic of Ebola virus disease (hereafter referred to as Ebola) were reported on March 22, 2014, with a report of 49 cases in Guinea. By August 31, 2014, a total of 3,685 probable, confirmed, and suspected cases in West Africa had been reported. To aid in planning for additional disease-control efforts, CDC constructed a modeling tool called EbolaResponse to provide estimates of the potential number of future cases. If trends continue without scale-up of effective interventions, by September 30, 2014, Sierra Leone and Liberia will have a total of approximately 8,000 Ebola cases. A potential underreporting correction factor of 2.5 also was calculated. Using this correction factor, the model estimates that approximately 21,000 total cases will have occurred in Liberia and Sierra Leone by September 30, 2014. Reported cases in Liberia are doubling every 15-20 days, and those in Sierra Leone are doubling every 30-40 days. The EbolaResponse modeling tool also was used to estimate how control and prevention interventions can slow and eventually stop the epidemic. In a hypothetical scenario, the epidemic begins to decrease and eventually end if approximately 70% of persons with Ebola are in medical care facilities or Ebola treatment units (ETUs) or, when these settings are at capacity, in a non-ETU setting such that there is a reduced risk for disease transmission (including safe burial when needed). In another hypothetical scenario, every 30-day delay in increasing the percentage of patients in ETUs to 70% was associated with an approximate tripling in the number of daily cases that occur at the peak of the epidemic (however, the epidemic still eventually ends). Officials have developed a plan to rapidly increase ETU capacities and also are developing innovative methods that can be quickly scaled up to isolate patients in non-ETU settings in a way that can help disrupt Ebola transmission in communities. The U.S. government and

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  12. 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.

  13. Facility-Based Delivery during the Ebola Virus Disease Epidemic in Rural Liberia: Analysis from a Cross-Sectional, Population-Based Household Survey.

    Directory of Open Access Journals (Sweden)

    John Ly

    2016-08-01

    Full Text Available The Ebola virus disease (EVD epidemic has threatened access to basic health services through facility closures, resource diversion, and decreased demand due to community fear and distrust. While modeling studies have attempted to estimate the impact of these disruptions, no studies have yet utilized population-based survey data.We conducted a two-stage, cluster-sample household survey in Rivercess County, Liberia, in March-April 2015, which included a maternal and reproductive health module. We constructed a retrospective cohort of births beginning 4 y before the first day of survey administration (beginning March 24, 2011. We then fit logistic regression models to estimate associations between our primary outcome, facility-based delivery (FBD, and time period, defined as the pre-EVD period (March 24, 2011-June 14, 2014 or EVD period (June 15, 2014-April 13, 2015. We fit both univariable and multivariable models, adjusted for known predictors of facility delivery, accounting for clustering using linearized standard errors. To strengthen causal inference, we also conducted stratified analyses to assess changes in FBD by whether respondents believed that health facility attendance was an EVD risk factor. A total of 1,298 women from 941 households completed the survey. Median age at the time of survey was 29 y, and over 80% had a primary education or less. There were 686 births reported in the pre-EVD period and 212 in the EVD period. The unadjusted odds ratio of facility-based delivery in the EVD period was 0.66 (95% confidence interval [CI] 0.48-0.90, p-value = 0.010. Adjustment for potential confounders did not change the observed association, either in the principal model (adjusted odds ratio [AOR] = 0.70, 95%CI 0.50-0.98, p = 0.037 or a fully adjusted model (AOR = 0.69, 95%CI 0.50-0.97, p = 0.033. The association was robust in sensitivity analyses. The reduction in FBD during the EVD period was observed among those reporting a belief that

  14. 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.

  15. The epidemic of Tuberculosis on vaccinated population

    Science.gov (United States)

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

    2017-09-01

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

  16. 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...

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

    Directory of Open Access Journals (Sweden)

    Christel Kamp

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

  18. Testing QCD with Hypothetical Tau Leptons

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.

    1998-10-21

    We construct new tests of perturbative QCD by considering a hypothetical {tau} lepton of arbitrary mass, which decays hadronically through the electromagnetic current. We can explicitly compute its hadronic width ratio directly as an integral over the e{sup +}e{sup -} annihilation cross section ratio, R{sub e{sup +}e{sup -}}. Furthermore, we can design a set of commensurate scale relations and perturbative QCD tests by varying the weight function away from the form associated with the V-A decay of the physical {tau}. This method allows the wide range of the R{sub e{sup +}e{sup -}} data to be used as a probe of perturbative QCD.

  19. Hypothetical conflict situations with friends and peers

    Directory of Open Access Journals (Sweden)

    Petrović Danijela S.

    2012-01-01

    Full Text Available This paper deals with age and sex differences in preferred strategies of conflict resolution in friendship and peer relationships. The study was conducted on the sample of 286 adolescents. Conflict resolution strategies have been investigated by the method of hypothetical conflict situations. For the purposes of this research, we have created an instrument consisting of 20 hypothetical situations, with the following subjects of conflict: breaking the agreement, non-compliance with opinion differences, provocations, dishonesty and stubbornness. Conflict resolution strategies we examined were giving in, withdrawal, competition and problem solving. The results have shown that problem solving is the dominant strategy of adolescents in conflict with friends, while in peer conflicts they more often opt for competition. Age differences are reflected in the fact that older adolescents are more likely to choose problem solving than younger, whereas younger adolescents are more likely to choose a retreat (withdrawal strategy than older. Girls are more prone to choosing problem solving than boys, who, on the other hand, tend to withdraw more than girls. Also, gender of the other person in the conflict is proved to be important - in conflict with male peers, adolescents choose competition to a greater extent and withdraw to a minor extent, compared to when they are in conflict with female peers. The results have practical implications as well. In programs for teaching constructive conflict resolution that are designed for younger adolescents there should be more emphasis on empowerment and training for assertive behaviour. In addition, when teaching about constructive conflict resolution strategies, it is important to consider the gender of adolescents as well as the gender of the person with whom they are in conflict.

  20. 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.

  1. 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.

  2. 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.

  3. Epidemic spreading in time-varying community networks.

    Science.gov (United States)

    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.

  4. The worldwide obesity epidemic.

    Science.gov (United States)

    James, P T; Leach, R; Kalamara, E; Shayeghi, M

    2001-11-01

    The recent World Health Organization (WHO) agreement on the standardized classification of overweight and obese, based on body mass index (BMI), allows a comparable analysis of prevalence rates worldwide for the first time. In Asia, however, there is a demand for a more limited range for normal BMIs (i.e., 18.5 to 22.9 kg/m(2) rather than 18.5 to 24.9 kg/m(2)) because of the high prevalence of comorbidities, particularly diabetes and hypertension. In children, the International Obesity Task-Force age-, sex-, and BMI-specific cutoff points are increasingly being used. We are currently evaluating BMI data globally as part of a new millennium analysis of the Global Burden of Disease. WHO is analyzing data in terms of 20 or more principal risk factors contributing to the primary causes of disability and lost lives in the 191 countries within the WHO. The prevalence rates for overweight and obese people are different in each region, with the Middle East, Central and Eastern Europe, and North America having higher prevalence rates. In most countries, women show a greater BMI distribution with higher obesity rates than do men. Obesity is usually now associated with poverty, even in developing countries. Relatively new data suggest that abdominal obesity in adults, with its associated enhanced morbidity, occurs particularly in those who had lower birth weights and early childhood stunting. Waist measurements in nationally representative studies are scarce but will now be needed to estimate the full impact of the worldwide obesity epidemic.

  5. The cholera epidemic in South Africa, 1980 - 1987 Epidemiological ...

    African Journals Online (AJOL)

    During the cholera epidemic in South Africa, 1980-1987, 25251 cases of cholera were bacteriologically proven. The case-fatality rate was 1,4%. Outbreaks occurred in the summer rainfall season. Age-specific aUack rates followed the pattern typically found during the 'epidemic phase' of the disease in most years. The vast ...

  6. Fractional virus epidemic model on financial networks

    Directory of Open Access Journals (Sweden)

    Balci Mehmet Ali

    2016-01-01

    Full Text Available In this study, we present an epidemic model that characterizes the behavior of a financial network of globally operating stock markets. Since the long time series have a global memory effect, we represent our model by using the fractional calculus. This model operates on a network, where vertices are the stock markets and edges are constructed by the correlation distances. Thereafter, we find an analytical solution to commensurate system and use the well-known differential transform method to obtain the solution of incommensurate system of fractional differential equations. Our findings are confirmed and complemented by the data set of the relevant stock markets between 2006 and 2016. Rather than the hypothetical values, we use the Hurst Exponent of each time series to approximate the fraction size and graph theoretical concepts to obtain the variables.

  7. Configuring the autism epidemic

    DEFF Research Database (Denmark)

    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....

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

    Science.gov (United States)

    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).

  9. Parameter Scaling for Epidemic Size in a Spatial Epidemic Model with Mobile Individuals.

    Directory of Open Access Journals (Sweden)

    Chiyori T Urabe

    Full Text Available In recent years, serious infectious diseases tend to transcend national borders and widely spread in a global scale. The incidence and prevalence of epidemics are highly influenced not only by pathogen-dependent disease characteristics such as the force of infection, the latent period, and the infectious period, but also by human mobility and contact patterns. However, the effect of heterogeneous mobility of individuals on epidemic outcomes is not fully understood. Here, we aim to elucidate how spatial mobility of individuals contributes to the final epidemic size in a spatial susceptible-exposed-infectious-recovered (SEIR model with mobile individuals in a square lattice. After illustrating the interplay between the mobility parameters and the other parameters on the spatial epidemic spreading, we propose an index as a function of system parameters, which largely governs the final epidemic size. The main contribution of this study is to show that the proposed index is useful for estimating how parameter scaling affects the final epidemic size. To demonstrate the effectiveness of the proposed index, we show that there is a positive correlation between the proposed index computed with the real data of human airline travels and the actual number of positive incident cases of influenza B in the entire world, implying that the growing incidence of influenza B is attributed to increased human mobility.

  10. The Prescription Opioid Pain Medication Overdose Epidemic

    Centers for Disease Control (CDC) Podcasts

    2016-04-19

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

  11. Social epidemics in the aftermath of disasters.

    NARCIS (Netherlands)

    IJzermans, C.J.

    2002-01-01

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

  12. Identification of the conserved hypothetical protein BPSL0317 in Burkholderia pseudomallei K96243

    Science.gov (United States)

    Yusoff, Nur Syamimi; Damiri, Nadzirah; Firdaus-Raih, Mohd

    2014-09-01

    Burkholderia pseudomallei K96243 is the causative agent of melioidosis, a disease which is endemic in Northern Australia and Southeastern Asia. The genome encodes several essential proteins including those currently annotated as hypothetical proteins. We studied the conservation and the essentiality of expressed hypothetical proteins in normal and different stress conditions. Based on the comparative genomics, we identified a hypothetical protein, BPSL0317, a potential essential gene that is being expressed in all normal and stress conditions. BPSL0317 is also phylogenetically conserved in the Burkholderiales order suggesting that this protein is crucial for survival among the order's members. BPSL0317 therefore has a potential to be a candidate antimicrobial drug target for this group of bacteria.

  13. Stochastic analysis of epidemics on adaptive time varying networks

    Science.gov (United States)

    Kotnis, Bhushan; Kuri, Joy

    2013-06-01

    Many studies investigating the effect of human social connectivity structures (networks) and human behavioral adaptations on the spread of infectious diseases have assumed either a static connectivity structure or a network which adapts itself in response to the epidemic (adaptive networks). However, human social connections are inherently dynamic or time varying. Furthermore, the spread of many infectious diseases occur on a time scale comparable to the time scale of the evolving network structure. Here we aim to quantify the effect of human behavioral adaptations on the spread of asymptomatic infectious diseases on time varying networks. We perform a full stochastic analysis using a continuous time Markov chain approach for calculating the outbreak probability, mean epidemic duration, epidemic reemergence probability, etc. Additionally, we use mean-field theory for calculating epidemic thresholds. Theoretical predictions are verified using extensive simulations. Our studies have uncovered the existence of an “adaptive threshold,” i.e., when the ratio of susceptibility (or infectivity) rate to recovery rate is below the threshold value, adaptive behavior can prevent the epidemic. However, if it is above the threshold, no amount of behavioral adaptations can prevent the epidemic. Our analyses suggest that the interaction patterns of the infected population play a major role in sustaining the epidemic. Our results have implications on epidemic containment policies, as awareness campaigns and human behavioral responses can be effective only if the interaction levels of the infected populace are kept in check.

  14. 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 ...

  15. 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

  16. 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 ...

  17. Kanpur epidemic: Time course

    Indian Academy of Sciences (India)

    The first peak was related to water contamination which began in December 1990. The second peak was related to failure of municipal authorities to chlorinate water during the 2nd week of February 1991. The epidemic came under control quickly after water contamination was controlled, providing confirmation for role of ...

  18. Trauma - the malignant epidemic

    African Journals Online (AJOL)

    national problem and the term 'malignant epidemic' is more applicable. These two ... In 1984 it stood at just over 400 000 per annum and today the figure is close to ... breadwinner, loss of productivity, expenses of rehabilitation and care of the ...

  19. GENERAL: Epidemic spreading on networks with vaccination

    Science.gov (United States)

    Shi, Hong-Jing; Duan, Zhi-Sheng; Chen, Guan-Rong; Li, Rong

    2009-08-01

    In this paper, a new susceptible-infected-susceptible (SIS) model on complex networks with imperfect vaccination is proposed. Two types of epidemic spreading patterns (the recovered individuals have or have not immunity) on scale-free networks are discussed. Both theoretical and numerical analyses are presented. The epidemic thresholds related to the vaccination rate, the vaccination-invalid rate and the vaccination success rate on scale-free networks are demonstrated, showing different results from the reported observations. This reveals that whether or not the epidemic can spread over a network under vaccination control is determined not only by the network structure but also by the medicine's effective duration. Moreover, for a given infective rate, the proportion of individuals to vaccinate can be calculated theoretically for the case that the recovered nodes have immunity. Finally, simulated results are presented to show how to control the disease prevalence.

  20. 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.

  1. 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...

  2. In Silico screening for functional candidates amongst hypothetical proteins

    DEFF Research Database (Denmark)

    Desler, Claus; Suravajhala, Prashanth; Sanderhoff, May

    2009-01-01

    eukaryotes. With the general belief that the majority of hypothetical proteins are the product of pseudogenes, it is essential to have a tool with the ability of pinpointing the minority of hypothetical proteins with a high probability of being expressed. RESULTS: Here, we present an in silico selection...

  3. Risk Management in Smallholder Cattle Farming: A Hypothetical Insurance Approach in Western Kenya

    OpenAIRE

    Otieno, David Jakinda; Oluoch-Kosura, Willis; Karugia, Joseph Thuo; Drucker, Adam G.; Rege, Edward

    2006-01-01

    Smallholder cattle farming is an important livelihood strategy in most developing countries like Kenya. However, tropical diseases in Africa often wipe out these valuable assets. This paper focuses on mitigation of cattle disease risks through a hypothetical insurance scheme. The study is based on data from a survey conducted on a purposive sample of 300 smallholder cattle farmers in Kakamega and Siaya districts of Western Kenya. Descriptive measures and a regression model were used in the an...

  4. Impacts of clustering on interacting epidemics.

    Science.gov (United States)

    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.

  5. Mechanistic movement models to understand epidemic spread.

    Science.gov (United States)

    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).

  6. Community Size Effects on Epidemic Spreading in Multiplex Social Networks

    OpenAIRE

    Liu, Ting; Li, Ping; Chen, Yan; Zhang, Jie

    2016-01-01

    The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explo...

  7. (Epidemic of bacillary dysentery)

    Energy Technology Data Exchange (ETDEWEB)

    Auger, P.; Pouliot, B.; De Grace, M.; Milot, C.; Lafortune, M.; Bergeron, Z.

    1981-10-01

    An outbreak of bacillary dysentery in 1978 affecting 928 persons, most of whom were living in the village of St-Jacques, PQ, is described. An epidemiologic study suggested the water supply as the source of the infection, and it was established that the water carried by the municipal aqueduct was contaminated by feces containing the causal agent, Shigella sonnei. This epidemic, the largest mentioned in he Canadian medical literature, demonstrates how contagious this infection is.

  8. Genomic and bioinformatics analyses of HAdV-4vac and HAdV-7vac, two human adenovirus (HAdV) strains that constituted original prophylaxis against HAdV-related acute respiratory disease, a reemerging epidemic disease.

    Science.gov (United States)

    Purkayastha, Anjan; Su, Jing; McGraw, John; Ditty, Susan E; Hadfield, Ted L; Seto, Jason; Russell, Kevin L; Tibbetts, Clark; Seto, Donald

    2005-07-01

    Vaccine strains of human adenovirus serotypes 4 and 7 (HAdV-4vac and HAdV-7vac) have been used successfully to prevent adenovirus-related acute respiratory disease outbreaks. The genomes of these two vaccine strains have been sequenced, annotated, and compared with their prototype equivalents with the goals of understanding their genomes for molecular diagnostics applications, vaccine redevelopment, and HAdV pathoepidemiology. These reference genomes are archived in GenBank as HAdV-4vac (35,994 bp; AY594254) and HAdV-7vac (35,240 bp; AY594256). Bioinformatics and comparative whole-genome analyses with their recently reported and archived prototype genomes reveal six mismatches and four insertions-deletions (indels) between the HAdV-4 prototype and vaccine strains, in contrast to the 611 mismatches and 130 indels between the HAdV-7 prototype and vaccine strains. Annotation reveals that the HAdV-4vac and HAdV-7vac genomes contain 51 and 50 coding units, respectively. Neither vaccine strain appears to be attenuated for virulence based on bioinformatics analyses. There is evidence of genome recombination, as the inverted terminal repeat of HAdV-4vac is initially identical to that of species C whereas the prototype is identical to species B1. These vaccine reference sequences yield unique genome signatures for molecular diagnostics. As a molecular forensics application, these references identify the circulating and problematic 1950s era field strains as the original HAdV-4 prototype and the Greider prototype, from which the vaccines are derived. Thus, they are useful for genomic comparisons to current epidemic and reemerging field strains, as well as leading to an understanding of pathoepidemiology among the human adenoviruses.

  9. Emergence of epidemics in rapidly varying networks

    International Nuclear Information System (INIS)

    Kohar, Vivek; Sinha, Sudeshna

    2013-01-01

    We describe a simple model mimicking disease spreading on a network with dynamically varying connections, and investigate the dynamical consequences of switching links in the network. Our central observation is that the disease cycles get more synchronized, indicating the onset of epidemics, as the underlying network changes more rapidly. This behavior is found for periodically switched links, as well as links that switch randomly in time. We find that the influence of changing links is more pronounced in networks where the nodes have lower degree, and the disease cycle has a longer infective stage. Further, when the switching of links is periodic we observe finer dynamical features, such as beating patterns in the emergent oscillations and resonant enhancement of synchronization, arising from the interplay between the time-scales of the connectivity changes and that of the epidemic outbreaks

  10. In Silico screening for functional candidates amongst hypothetical proteins

    Directory of Open Access Journals (Sweden)

    Sanderhoff May

    2009-09-01

    Full Text Available Abstract Background The definition of a hypothetical protein is a protein that is predicted to be expressed from an open reading frame, but for which there is no experimental evidence of translation. Hypothetical proteins constitute a substantial fraction of proteomes of human as well as of other eukaryotes. With the general belief that the majority of hypothetical proteins are the product of pseudogenes, it is essential to have a tool with the ability of pinpointing the minority of hypothetical proteins with a high probability of being expressed. Results Here, we present an in silico selection strategy where eukaryotic hypothetical proteins are sorted according to two criteria that can be reliably identified in silico: the presence of subcellular targeting signals and presence of characterized protein domains. To validate the selection strategy we applied it on a database of human hypothetical proteins dating to 2006 and compared the proteins predicted to be expressed by our selecting strategy, with their status in 2008. For the comparison we focused on mitochondrial proteins, since considerable amounts of research have focused on this field in between 2006 and 2008. Therefore, many proteins, defined as hypothetical in 2006, have later been characterized as mitochondrial. Conclusion Among the total amount of human proteins hypothetical in 2006, 21% have later been experimentally characterized and 6% of those have been shown to have a role in a mitochondrial context. In contrast, among the selected hypothetical proteins from the 2006 dataset, predicted by our strategy to have a mitochondrial role, 53-62% have later been experimentally characterized, and 85% of these have actually been assigned a role in mitochondria by 2008. Therefore our in silico selection strategy can be used to select the most promising candidates for subsequent in vitro and in vivo analyses.

  11. 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

  12. Unsynchronized influenza epidemics in two neighboring subtropical cities

    Directory of Open Access Journals (Sweden)

    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

  13. A Weighted Configuration Model and Inhomogeneous Epidemics

    Science.gov (United States)

    Britton, Tom; Deijfen, Maria; Liljeros, Fredrik

    2011-12-01

    A random graph model with prescribed degree distribution and degree dependent edge weights is introduced. Each vertex is independently equipped with a random number of half-edges and each half-edge is assigned an integer valued weight according to a distribution that is allowed to depend on the degree of its vertex. Half-edges with the same weight are then paired randomly to create edges. An expression for the threshold for the appearance of a giant component in the resulting graph is derived using results on multi-type branching processes. The same technique also gives an expression for the basic reproduction number for an epidemic on the graph where the probability that a certain edge is used for transmission is a function of the edge weight (reflecting how closely `connected' the corresponding vertices are). It is demonstrated that, if vertices with large degree tend to have large (small) weights on their edges and if the transmission probability increases with the edge weight, then it is easier (harder) for the epidemic to take off compared to a randomized epidemic with the same degree and weight distribution. A recipe for calculating the probability of a large outbreak in the epidemic and the size of such an outbreak is also given. Finally, the model is fitted to three empirical weighted networks of importance for the spread of contagious diseases and it is shown that R 0 can be substantially over- or underestimated if the correlation between degree and weight is not taken into account.

  14. Computational algebraic geometry of epidemic models

    Science.gov (United States)

    Rodríguez Vega, Martín.

    2014-06-01

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

  15. The impact of awareness on epidemic spreading in networks.

    Science.gov (United States)

    Wu, Qingchu; Fu, Xinchu; Small, Michael; Xu, Xin-Jian

    2012-03-01

    We explore the impact of awareness on epidemic spreading through a population represented by a scale-free network. Using a network mean-field approach, a mathematical model for epidemic spreading with awareness reactions is proposed and analyzed. We focus on the role of three forms of awareness including local, global, and contact awareness. By theoretical analysis and simulation, we show that the global awareness cannot decrease the likelihood of an epidemic outbreak while both the local awareness and the contact awareness can. Also, the influence degree of the local awareness on disease dynamics is closely related with the contact awareness.

  16. Epidemics spread in heterogeneous populations

    Science.gov (United States)

    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.

  17. 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)

  18. Epidemic spread in bipartite network by considering risk awareness

    Science.gov (United States)

    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.

  19. [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.

  20. Inferring epidemic network topology from surveillance data.

    Directory of Open Access Journals (Sweden)

    Xiang Wan

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

  1. A Comparison between Two Simulation Models for Spread of Foot-and-Mouth Disease

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Boklund, Anette; Stockmarr, Anders

    2014-01-01

    Two widely used simulation models of foot-and-mouth disease (FMD) were used in order to compare the models' predictions in term of disease spread, consequence, and the ranking of the applied control strategies, and to discuss the effect of the way disease spread is modeled on the predicted outcomes...... of each model. The DTU-DADS (version 0.100), and ISP (version 2.001.11) were used to simulate a hypothetical spread of FMD in Denmark. Actual herd type, movements, and location data in the period 1st October 2006 and 30th September 2007 was used. The models simulated the spread of FMD using 3 different...... areas and 1,000 in low density swine areas, and 1,000 sheep herds. Generally, DTU-DADS predicted larger, longer duration and costlier epidemics than ISP, except when epidemics started in cattle herds located in high density cattle areas. ISP supported suppressive vaccination rather than pre...

  2. Projected economic evaluation of the national implementation of a hypothetical HIV vaccination program among adolescents in South Africa, 2012

    Directory of Open Access Journals (Sweden)

    Nishila Moodley

    2016-04-01

    Full Text Available Abstract Background Adolescents in South Africa are at high risk of acquiring HIV. The HIV vaccination of adolescents could reduce HIV incidence and mortality. The potential impact and cost-effectiveness of a national school-based HIV vaccination program among adolescents was determined. Method The national HIV disease and cost burden was compared with (intervention and without HIV vaccination (comparator given to school-going adolescents using a semi-Markov model. Life table analysis was conducted to determine the impact of the intervention on life expectancy. Model inputs included measures of disease and cost burden and hypothetical assumptions of vaccine characteristics. The base-case HIV vaccine modelled cost at US$ 12 per dose; vaccine efficacy of 50 %; duration of protection of 10 years achieved at a coverage rate of 60 % and required annual boosters. Incremental cost-effectiveness ratios (ICER were calculated using life years gained (LYG serving as the outcome measure. Sensitivity analyses were conducted on the vaccine characteristics to assess parameter uncertainty. Results The HIV vaccination model yielded an ICER of US$ 5 per LYG (95 % CI ZAR 2.77–11.61 compared with the comparator, which is considerably less than the national willingness-to-pay threshold of cost-effectiveness. This translated to an 11 % increase in per capita costs from US$ 80 to US$ 89. National implementation of this intervention could potentially result in an estimated cumulative gain of 23.6 million years of life (95 % CI 8.48–34.3 million years among adolescents age 10–19 years that were vaccinated. The 10 year absolute risk reduction projected by vaccine implementation was 0.42 % for HIV incidence and 0.41 % for HIV mortality, with an increase in life expectancy noted across all age groups. The ICER was sensitive to the vaccine efficacy, coverage and vaccine pricing in the sensitivity analysis. Conclusions A national HIV vaccination program would

  3. Spatiotemporal Evolution of Ebola Virus Disease at Sub-National Level during the 2014 West Africa Epidemic: Model Scrutiny and Data Meagreness.

    Directory of Open Access Journals (Sweden)

    Eva Santermans

    Full Text Available The Ebola outbreak in West Africa has infected at least 27,443 individuals and killed 11,207, based on data until 24 June, 2015, released by the World Health Organization (WHO. This outbreak has been characterised by extensive geographic spread across the affected countries Guinea, Liberia and Sierra Leone, and by localized hotspots within these countries. The rapid recognition and quantitative assessment of localised areas of higher transmission can inform the optimal deployment of public health resources.A variety of mathematical models have been used to estimate the evolution of this epidemic, and some have pointed out the importance of the spatial heterogeneity apparent from incidence maps. However, little is known about the district-level transmission. Given that many response decisions are taken at sub-national level, the current study aimed to investigate the spatial heterogeneity by using a different modelling framework, built on publicly available data at district level. Furthermore, we assessed whether this model could quantify the effect of intervention measures and provide predictions at a local level to guide public health action. We used a two-stage modelling approach: a a flexible spatiotemporal growth model across all affected districts and b a deterministic SEIR compartmental model per district whenever deemed appropriate.Our estimates show substantial differences in the evolution of the outbreak in the various regions of Guinea, Liberia and Sierra Leone, illustrating the importance of monitoring the outbreak at district level. We also provide an estimate of the time-dependent district-specific effective reproduction number, as a quantitative measure to compare transmission between different districts and give input for informed decisions on control measures and resource allocation. Prediction and assessing the impact of control measures proved to be difficult without more accurate data. In conclusion, this study provides us a

  4. An inactivated vaccine made from a U.S. field isolate of porcine epidemic disease virus is immunogenic in pigs as demonstrated by a dose-titration.

    Science.gov (United States)

    Collin, Emily A; Anbalagan, Srivishnupriya; Okda, Faten; Batman, Ron; Nelson, Eric; Hause, Ben M

    2015-03-15

    Porcine epidemic diarrhea virus (PEDV), a highly pathogenic and transmissible virus in swine, was first detected in the U.S. in May, 2013, and has caused tremendous losses to the swine industry. Due to the difficulty in isolating and growing this virus in cell culture, few vaccine studies using cell culture propagated PEDV have been performed on U.S. strains in pigs. Therefore, the objective of this study was to evaluate the humoral immune response to the selected inactivated PEDV vaccine candidate in a dose-titration manner. PEDV was isolated from a pig with diarrhea and complete genome sequencing found >99% nucleotide identity to other U.S. PEDV. Inactivated adjuvanted monovalent vaccines were administered intramuscularly to five week old pigs in a dose titration experimental design, ranging from 6.0-8.0 log10 tissue culture infective dose (TCID50/mL), to evaluate immunogenicity using a fluorescent foci neutralization assay (FFN), fluorescent microsphere immunoassay (FMIA), and enzyme-linked immunosorbent assay (ELISA) on sera. Pigs vaccinated with 8.0 log10 TCID50/mL inactivated virus showed significantly higher FFN titers as well as FMIA and ELISA values than 6.0 log10 TCID50/mL vaccinates and the negative controls. These results demonstrate the immunogenicity of a PEDV inactivated viral vaccine with a U.S. strain via dose-titration. A future vaccination-challenge study would illustrate the efficacy of an inactivated vaccine and help evaluate protective FFN titers and ELISA and FMIA responses.

  5. 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.

  6. The epidemic of methylisothiazolinone

    DEFF Research Database (Denmark)

    Schwensen, Jakob F; Uter, Wolfgang; Bruze, Magnus

    2017-01-01

    BACKGROUND: The use of methylisothiazolinone (MI) in cosmetic products has caused an unprecedented epidemic of MI contact allergy. Current data concerning exposures at a European level are required. OBJECTIVES: To describe demographics and MI exposures for European patients with MI contact allergy....... METHODS: Eleven European dermatology departments from eight European countries prospectively collected data between 1 May and 31 October 2015 among consecutive patients who had positive patch test reactions to MI (2000 ppm aq.). RESULTS: A total of 6.0% (205/3434; range 2.6-13.0%) of patients had positive...... patch test reactions to MI. Dermatitis most frequently affected the hands (43.4%), face (32.7%), arms (14.6%), and eyelids (11.7%); 12.7% had widespread dermatitis. For 72.7% (149/205), MI contact allergy was currently relevant mainly because of exposure to cosmetic products (83.2%; 124...

  7. Reconstructing the 2003/2004 H3N2 influenza epidemic in Switzerland with a spatially explicit, individual-based model

    Science.gov (United States)

    2011-01-01

    Background Simulation models of influenza spread play an important role for pandemic preparedness. However, as the world has not faced a severe pandemic for decades, except the rather mild H1N1 one in 2009, pandemic influenza models are inherently hypothetical and validation is, thus, difficult. We aim at reconstructing a recent seasonal influenza epidemic that occurred in Switzerland and deem this to be a promising validation strategy for models of influenza spread. Methods We present a spatially explicit, individual-based simulation model of influenza spread. The simulation model bases upon (i) simulated human travel data, (ii) data on human contact patterns and (iii) empirical knowledge on the epidemiology of influenza. For model validation we compare the simulation outcomes with empirical knowledge regarding (i) the shape of the epidemic curve, overall infection rate and reproduction number, (ii) age-dependent infection rates and time of infection, (iii) spatial patterns. Results The simulation model is capable of reproducing the shape of the 2003/2004 H3N2 epidemic curve of Switzerland and generates an overall infection rate (14.9 percent) and reproduction numbers (between 1.2 and 1.3), which are realistic for seasonal influenza epidemics. Age and spatial patterns observed in empirical data are also reflected by the model: Highest infection rates are in children between 5 and 14 and the disease spreads along the main transport axes from west to east. Conclusions We show that finding evidence for the validity of simulation models of influenza spread by challenging them with seasonal influenza outbreak data is possible and promising. Simulation models for pandemic spread gain more credibility if they are able to reproduce seasonal influenza outbreaks. For more robust modelling of seasonal influenza, serological data complementing sentinel information would be beneficial. PMID:21554680

  8. 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

  9. 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.

  10. Epidemic extinction paths in complex networks

    Science.gov (United States)

    Hindes, Jason; Schwartz, Ira B.

    2017-05-01

    We study the extinction of long-lived epidemics on finite complex networks induced by intrinsic noise. Applying analytical techniques to the stochastic susceptible-infected-susceptible model, we predict the distribution of large fluctuations, the most probable or optimal path through a network that leads to a disease-free state from an endemic state, and the average extinction time in general configurations. Our predictions agree with Monte Carlo simulations on several networks, including synthetic weighted and degree-distributed networks with degree correlations, and an empirical high school contact network. In addition, our approach quantifies characteristic scaling patterns for the optimal path and distribution of large fluctuations, both near and away from the epidemic threshold, in networks with heterogeneous eigenvector centrality and degree distributions.

  11. 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.

  12. [The depression epidemic does not exist].

    Science.gov (United States)

    van der Feltz-Cornelis, Christina M

    2009-01-01

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

  13. Comparing hypothetical versus non-hypothetical methods for measuring willingness to pay in a food context

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Carrasco, L.; Brugarolas, M.; Martínez-Poveda, A.; Ruiz-Martínez, J.J.

    2015-07-01

    Choosing a valid procedure to measure willingness to pay (WTP) is crucial for designating optimum price policies or for evaluating the demand for new products. This study compares two methods for obtaining WTP in a food context: a random nth price auction and an open-ended contingent valuation (CV) question. Participants were regular salad tomato buyers of Alicante and they were randomly assigned to one of the two treatments. The products about which they would show their WTP were traditional tomato varieties. Both treatments were divided into three stages: in the first stage the only available information was a reference price for the tomatoes. In stages 2 and 3 we revealed the local origin and the organic grown of the tomatoes respectively. Our results show that in the auction the percentage of participants willing to pay the same or more than the reference price was between 20 and 30%. In the CV method this percentage was between 40 and 65%. The mean WTP in the auction, considering the whole of the individuals, was situated between 1.90 and 2.13 €/kg. These same results obtained through the CV were situated between 2.54 and 3.21 €/kg. The results confirmed the findings of previous papers in which the hypothetical bias of CV was clarified because it yields higher values for WTP than the auction, especially when referring to the number of individuals willing to pay more. Additionally, hedonic price models were estimated for the prices obtained by both methods with the result that in all the models, WTP was directly related to the price paid for the latest purchase of tomatoes. (Author)

  14. Comparing hypothetical versus non-hypothetical methods for measuring willingness to pay in a food context

    Directory of Open Access Journals (Sweden)

    Laura Martínez-Carrasco

    2015-12-01

    Full Text Available Choosing a valid procedure to measure willingness to pay (WTP is crucial for designating optimum price policies or for evaluating the demand for new products. This study compares two methods for obtaining WTP in a food context: a random nth price auction and an open-ended contingent valuation (CV question. Participants were regular salad tomato buyers of Alicante and they were randomly assigned to one of the two treatments. The products about which they would show their WTP were traditional tomato varieties. Both treatments were divided into three stages: in the first stage the only available information was a reference price for the tomatoes. In stages 2 and 3 we revealed the local origin and the organic grown of the tomatoes respectively. Our results show that in the auction the percentage of participants willing to pay the same or more than the reference price was between 20 and 30%. In the CV method this percentage was between 40 and 65%. The mean WTP in the auction, considering the whole of the individuals, was situated between 1.90 and 2.13 €/kg. These same results obtained through the CV were situated between 2.54 and 3.21 €/kg. The results confirmed the findings of previous papers in which the hypothetical bias of CV was clarified because it yields higher values for WTP than the auction, especially when referring to the number of individuals willing to pay more. Additionally, hedonic price models were estimated for the prices obtained by both methods with the result that in all the models, WTP was directly related to the price paid for the latest purchase of tomatoes.

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

    Science.gov (United States)

    Yao, Yiyang; Zhou, Yinzuo

    2017-02-01

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

  16. Epidemic spreading in time-varying community networks

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-15

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

  17. 2,500-year Evolution of the Term Epidemic

    Science.gov (United States)

    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

  18. Epidemic cholera in Latin America: spread and routes of transmission.

    Science.gov (United States)

    Guthmann, J P

    1995-12-01

    In the most recent epidemic of cholera in Latin America, nearly a million cases were reported and almost 9000 people died between January 1991 and December 1993. The epidemic spread rapidly from country to country, affecting in three years all the countries of Latin America except Uruguay and the Caribbean. Case-control studies carried out in Peru showed a significant association between drinking water and risk of disease. Cholera was associated with the consumption of unwashed fruit and vegetables, with eating food from street vendors and with contaminated crabmeat transported in travellers' luggage. This article documents the spread of the epidemic and its routes of transmission and discusses whether the introduction of the epidemic to Peru and its subsequent spread throughout the continent could have been prevented.

  19. Epidemic transmission on random mobile network with diverse infection periods

    Science.gov (United States)

    Li, Kezan; Yu, Hong; Zeng, Zhaorong; Ding, Yong; Ma, Zhongjun

    2015-05-01

    The heterogeneity of individual susceptibility and infectivity and time-varying topological structure are two realistic factors when we study epidemics on complex networks. Current research results have shown that the heterogeneity of individual susceptibility and infectivity can increase the epidemic threshold in a random mobile dynamical network with the same infection period. In this paper, we will focus on random mobile dynamical networks with diverse infection periods due to people's different constitutions and external circumstances. Theoretical results indicate that the epidemic threshold of the random mobile network with diverse infection periods is larger than the counterpart with the same infection period. Moreover, the heterogeneity of individual susceptibility and infectivity can play a significant impact on disease transmission. In particular, the homogeneity of individuals will avail to the spreading of epidemics. Numerical examples verify further our theoretical results very well.

  20. Multidimensional epidemic thresholds in diffusion processes over interdependent networks

    International Nuclear Information System (INIS)

    Salehi, Mostafa; Siyari, Payam; Magnani, Matteo; Montesi, Danilo

    2015-01-01

    Highlights: •We propose a new concept of multidimensional epidemic threshold for interdependent networks. •We analytically derive and numerically illustrate the conditions for multilayer epidemics. •We study the evolution of infection density and diffusion dynamics. -- Abstract: Several systems can be modeled as sets of interdependent networks where each network contains distinct nodes. Diffusion processes like the spreading of a disease or the propagation of information constitute fundamental phenomena occurring over such coupled networks. In this paper we propose a new concept of multidimensional epidemic threshold characterizing diffusion processes over interdependent networks, allowing different diffusion rates on the different networks and arbitrary degree distributions. We analytically derive and numerically illustrate the conditions for multilayer epidemics, i.e., the appearance of a giant connected component spanning all the networks. Furthermore, we study the evolution of infection density and diffusion dynamics with extensive simulation experiments on synthetic and real networks

  1. 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

  2. A simple model for behaviour change in epidemics

    Directory of Open Access Journals (Sweden)

    Brauer Fred

    2011-02-01

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

  3. A stochastic SIS epidemic model with vaccination

    Science.gov (United States)

    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.

  4. The threshold of a stochastic SIQS epidemic model

    Science.gov (United States)

    Zhang, Xiao-Bing; Huo, Hai-Feng; Xiang, Hong; Shi, Qihong; Li, Dungang

    2017-09-01

    In this paper, we present the threshold of a stochastic SIQS epidemic model which determines the extinction and persistence of the disease. Furthermore, we find that noise can suppress the disease outbreak. Numerical simulations are also carried out to confirm the analytical results.

  5. The epidemic of Athens, 430 - 426 BC | Retief | South African ...

    African Journals Online (AJOL)

    ... number of scholars who studied the subject, Thucydides' description does not accurately fit any existing disease, but we suggest that analysis of the signs and symptoms, considered in conjunction with significant epidemiological evidence, narrows down the many possibilities to epidemic typhus, plague, arboviral disease ...

  6. 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...

  7. Patient-Centred Coordinated Care in Times of Emerging Diseases and Epidemics. Contribution of the IMIA Working Group on Patient Safety.

    Science.gov (United States)

    Borycki, E; Cummings, E; Dexheimer, J W; Gong, Y; Kennebeck, S; Kushniruk, A; Kuziemsky, C; Saranto, K; Weber, J; Takeda, H

    2015-08-13

    In this paper the researchers describe how existing health information technologies (HIT) can be repurposed and new technologies can be innovated to provide patient-centered care to individuals affected by new and emerging diseases. The researchers conducted a focused review of the published literature describing how HIT can be used to support safe, patient-centred, coordinated care to patients who are affected by Ebola (an emerging disease). New and emerging diseases present opportunities for repurposing existing technologies and for stimulating the development of new HIT innovation. Innovative technologies may be developed such as new software used for tracking patients during new or emerging disease outbreaks or by repurposing and extending existing technologies so they can be used to support patients, families and health professionals who may have been exposed to a disease. The paper describes the development of new technologies and the repurposing and extension of existing ones (such as electronic health records) using the most recent outbreak of Ebola as an example.

  8. Epidemic spreading on contact networks with adaptive weights.

    Science.gov (United States)

    Zhu, Guanghu; Chen, Guanrong; Xu, Xin-Jian; Fu, Xinchu

    2013-01-21

    The heterogeneous patterns of interactions within a population are often described by contact networks, but the variety and adaptivity of contact strengths are usually ignored. This paper proposes a modified epidemic SIS model with a birth-death process and nonlinear infectivity on an adaptive and weighted contact network. The links' weights, named as 'adaptive weights', which indicate the intimacy or familiarity between two connected individuals, will reduce as the disease develops. Through mathematical and numerical analyses, conditions are established for population extermination, disease extinction and infection persistence. Particularly, it is found that the fixed weights setting can trigger the epidemic incidence, and that the adaptivity of weights cannot change the epidemic threshold but it can accelerate the disease decay and lower the endemic level. Finally, some corresponding control measures are suggested. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Lost in the Workplace: Is There an Occupational Disease Epidemic? Proceedings from a Seminar for the News Media (September 13-14, 1979).

    Science.gov (United States)

    Occupational Safety and Health Administration, Washington, DC.

    This document contains the texts of 10 panel discussions presented at a seminar designed to give the media an opportunity to learn about occupational health problems. Discussed first were protecting the American worker, and disease on the job. Personal testimony on worker health and a case study of the effects of asbestos were presented. Also…

  10. Dynamics of epidemics outbreaks in heterogeneous populations

    Science.gov (United States)

    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.

  11. 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%.

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

    Science.gov (United States)

    Hetzel, Géraldine

    2014-01-01

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

  13. Invited review: Epidemics on social networks

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    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

  14. Epidemics in partially overlapped multiplex networks.

    Directory of Open Access Journals (Sweden)

    Camila Buono

    Full Text Available Many real networks exhibit a layered structure in which links in each layer reflect the function of nodes on different environments. These multiple types of links are usually represented by a multiplex network in which each layer has a different topology. In real-world networks, however, not all nodes are present on every layer. To generate a more realistic scenario, we use a generalized multiplex network and assume that only a fraction [Formula: see text] of the nodes are shared by the layers. We develop a theoretical framework for a branching process to describe the spread of an epidemic on these partially overlapped multiplex networks. This allows us to obtain the fraction of infected individuals as a function of the effective probability that the disease will be transmitted [Formula: see text]. We also theoretically determine the dependence of the epidemic threshold on the fraction [Formula: see text] of shared nodes in a system composed of two layers. We find that in the limit of [Formula: see text] the threshold is dominated by the layer with the smaller isolated threshold. Although a system of two completely isolated networks is nearly indistinguishable from a system of two networks that share just a few nodes, we find that the presence of these few shared nodes causes the epidemic threshold of the isolated network with the lower propagating capacity to change discontinuously and to acquire the threshold of the other network.

  15. Impact of the infectious period on epidemics

    Science.gov (United States)

    Wilkinson, Robert R.; Sharkey, Kieran J.

    2018-05-01

    The duration of the infectious period is a crucial determinant of the ability of an infectious disease to spread. We consider an epidemic model that is network based and non-Markovian, containing classic Kermack-McKendrick, pairwise, message passing, and spatial models as special cases. For this model, we prove a monotonic relationship between the variability of the infectious period (with fixed mean) and the probability that the infection will reach any given subset of the population by any given time. For certain families of distributions, this result implies that epidemic severity is decreasing with respect to the variance of the infectious period. The striking importance of this relationship is demonstrated numerically. We then prove, with a fixed basic reproductive ratio (R0), a monotonic relationship between the variability of the posterior transmission probability (which is a function of the infectious period) and the probability that the infection will reach any given subset of the population by any given time. Thus again, even when R0 is fixed, variability of the infectious period tends to dampen the epidemic. Numerical results illustrate this but indicate the relationship is weaker. We then show how our results apply to message passing, pairwise, and Kermack-McKendrick epidemic models, even when they are not exactly consistent with the stochastic dynamics. For Poissonian contact processes, and arbitrarily distributed infectious periods, we demonstrate how systems of delay differential equations and ordinary differential equations can provide upper and lower bounds, respectively, for the probability that any given individual has been infected by any given time.

  16. Evaluation of hypothetical (153)Gd source for use in brachytherapy.

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    Ghorbani, Mahdi; Behmadi, Marziyeh

    2016-01-01

    The purpose of this work is to evaluate the dosimetric parameters of a hypothetical (153)Gd source for use in brachytherapy and comparison of the dosimetric parameters with those of (192)Ir and (125)I sources. Dose rate constant, the radial dose function and the two dimensional (2D) anisotropy function data for the hypothetical (153)Gd source were obtained by simulation of the source using MCNPX code and then were compared with the corresponding data reported by Enger et al. A comprehensive comparison between this hypothetical source and a (192)Ir source with similar geometry and a (125)I source was performed as well. Excellent agreement was shown between the results of the two studies. Dose rate constant values for the hypothetical (153)Gd, (192)Ir, (125)I sources are 1.173 cGyh(-1) U(-1), 1.044 cGyh(-1) U(-1), 0.925 cGyh(-1) U(-1), respectively. Radial dose function for the hypothetical (153)Gd source has an increasing trend, while (192)Ir has more uniform and (125)I has more rapidly falling off radial dose functions. 2D anisotropy functions for these three sources indicate that, except at 0.5 cm distance, (192)Ir and (125)I have more isotropic trends as compared to the (153)Gd source. A more uniform radial dose function, and 2D anisotropy functions with more isotropy, a much higher specific activity are advantages of (192)Ir source over (153)Gd. However, a longer half-life of (153)Gd source compared to the other two sources, and lower energy of the source with respect to (192)Ir are advantages of using (153)Gd in brachytherapy versus (192)Ir source.

  17. Flexible Modeling of Epidemics with an Empirical Bayes Framework

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    Brooks, Logan C.; Farrow, David C.; Hyun, Sangwon; Tibshirani, Ryan J.; Rosenfeld, Roni

    2015-01-01

    Seasonal influenza epidemics cause consistent, considerable, widespread loss annually in terms of economic burden, morbidity, and mortality. With access to accurate and reliable forecasts of a current or upcoming influenza epidemic’s behavior, policy makers can design and implement more effective countermeasures. This past year, the Centers for Disease Control and Prevention hosted the “Predict the Influenza Season Challenge”, with the task of predicting key epidemiological measures for the 2013–2014 U.S. influenza season with the help of digital surveillance data. We developed a framework for in-season forecasts of epidemics using a semiparametric Empirical Bayes framework, and applied it to predict the weekly percentage of outpatient doctors visits for influenza-like illness, and the season onset, duration, peak time, and peak height, with and without using Google Flu Trends data. Previous work on epidemic modeling has focused on developing mechanistic models of disease behavior and applying time series tools to explain historical data. However, tailoring these models to certain types of surveillance data can be challenging, and overly complex models with many parameters can compromise forecasting ability. Our approach instead produces possibilities for the epidemic curve of the season of interest using modified versions of data from previous seasons, allowing for reasonable variations in the timing, pace, and intensity of the seasonal epidemics, as well as noise in observations. Since the framework does not make strict domain-specific assumptions, it can easily be applied to some other diseases with seasonal epidemics. This method produces a complete posterior distribution over epidemic curves, rather than, for example, solely point predictions of forecasting targets. We report prospective influenza-like-illness forecasts made for the 2013–2014 U.S. influenza season, and compare the framework’s cross-validated prediction error on historical data to

  18. Engaging 'communities': anthropological insights from the West African Ebola epidemic.

    Science.gov (United States)

    Wilkinson, A; Parker, M; Martineau, F; Leach, M

    2017-05-26

    The recent Ebola epidemic in West Africa highlights how engaging with the sociocultural dimensions of epidemics is critical to mounting an effective outbreak response. Community engagement was pivotal to ending the epidemic and will be to post-Ebola recovery, health system strengthening and future epidemic preparedness and response. Extensive literatures in the social sciences have emphasized how simple notions of community, which project solidarity onto complex hierarchies and politics, can lead to ineffective policies and unintended consequences at the local level, including doing harm to vulnerable populations. This article reflects on the nature of community engagement during the Ebola epidemic and demonstrates a disjuncture between local realities and what is being imagined in post-Ebola reports about the lessons that need to be learned for the future. We argue that to achieve stated aims of building trust and strengthening outbreak response and health systems, public health institutions need to reorientate their conceptualization of 'the community' and develop ways of working which take complex social and political relationships into account.This article is part of the themed issue 'The 2013-2016 West African Ebola epidemic: data, decision-making and disease control'. © 2017 The Authors.

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

    Science.gov (United States)

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

    2011-01-01

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

  20. Hydro-epidemiology of Chronic Kidney Disease(CKD) in Sri Lanka and Its Similarities to the CKD Epidemic in Meso-America.Sarath Gunatilake M.D, Dr. P.H, Professor, California State University, Long Beach California

    Science.gov (United States)

    Illangasekera, T.; Gunatilake, S.

    2015-12-01

    Over 2000 years ago Sri Lanka was known as the granary of the east. This distinction was achieved with a massive rice production aided by an efficient irrigation system. The basic structural unit of this irrigation system -with thousands of man-made lakes- was a large reservoir collecting rain water from tributaries and redistributing it to a cascade of rice paddy farms. The rice cultivation used organic fertilizer and natural pesticides made from ancient Ayurvedic recipes. The sociopolitical changes initiated in the county in 1977 resulted in a modernized agricultural economy with the renovation of the old irrigation system. Heavy use of pesticides, mostly Glyphosate (brand name "Round Up") with government subsidized cheap synthetic fertilizer (mostly triple phosphate) contaminated with heavy metals, including Arsenic and Cadmium, became a common practice. As a result, the shallow aquifers in the lowest lying areas, recharged by the irrigation water, was contaminated with Calcium, Magnesium phosphates, and the heavy metals, rendering the drinking water from shallow wells in these areas, extremely hard and unpalatable. The practice of drinking water from the shallow wells in low lying areas, most of which are abandoned now, and the use and spraying of pesticides particularly Glyphosate (often without proper personal protective equipment) have been identified in a case control study, as the main risk factors responsible for a massive epidemic of Chronic Kidney Disease (CKD) affecting 450,000 young farmers, resulting in 23,000 deaths. It is hypothesized that the Glyphosate chelates heavy metals delivering it to the kidney, with contaminated drinking water and food, causing progressive kidney damage. The same irrigation system that contributed to past prosperity has now become a scourge within the realm of a modernized agriculture. Climatic variations, global warming and severe dehydration also have been identified as contributory factors. Similar CKD epidemic killing

  1. Diabetes mellitus type 2 and other chronic non-communicable diseases in the central region, Saudi Arabia (riyadh cohort 2: a decade of an epidemic

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    Alkharfy Khalid M

    2011-06-01

    Full Text Available Abstract Background Follow-up epidemiologic studies are needed to assess trends and patterns of disease spread. No follow-up epidemiologic study has been done in the Kingdom of Saudi Arabia to assess the current prevalence of major chronic, noncommunicable diseases, specifically in the urban region, where modifiable risk factors remain rampant. This study aims to fill this gap. Methods A total of 9,149 adult Saudis ages seven to eighty years (5,357 males (58.6% and 3,792 females (41.4% were randomly selected from the Riyadh Cohort Study for inclusion. Diagnosis of type 2 diabetes mellitus (DMT2 and obesity were based on the World Health Organization definitions. Diagnoses of hypertension and coronary artery disease (CAD were based on the Seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure and American Heart Association criteria, respectively. Results The overall crude prevalence of DMT2 was 23.1% (95% confidence interval (95% CI 20.47 to 22.15. The age-adjusted prevalence of DMT2 was 31.6%. DMT2 prevalence was significantly higher in males, with an overall age-adjusted prevalence of 34.7% (95% CI 32.6 to 35.4, than in females, who had an overall age-adjusted prevalence of 28.6% (95% CI 26.7 to 29.3 (P P Conclusion Comparisons of our findings with earlier data show that the prevalence of DMT2, hypertension and CAD in Riyadh, Saudi Arabia, has alarmingly worsened. Aggressive promotion of public awareness, continued screening and early intervention are pivotal to boosting a positive response.

  2. Ethics review of studies during public health emergencies - the experience of the WHO ethics review committee during the Ebola virus disease epidemic.

    Science.gov (United States)

    Alirol, Emilie; Kuesel, Annette C; Guraiib, Maria Magdalena; de la Fuente-Núñez, Vânia; Saxena, Abha; Gomes, Melba F

    2017-06-26

    Between 2013 and 2016, West Africa experienced the largest ever outbreak of Ebola Virus Disease. In the absence of registered treatments or vaccines to control this lethal disease, the World Health Organization coordinated and supported research to expedite identification of interventions that could control the outbreak and improve future control efforts. Consequently, the World Health Organization Research Ethics Review Committee (WHO-ERC) was heavily involved in reviews and ethics discussions. It reviewed 24 new and 22 amended protocols for research studies including interventional (drug, vaccine) and observational studies. WHO-ERC provided the reviews within on average 6 working days. The WHO-ERC often could not provide immediate approval of protocols for reasons which were not Ebola Virus Disease specific but related to protocol inconsistencies, missing information and complex informed consents. WHO-ERC considerations on Ebola Virus Disease specific issues (benefit-risk assessment, study design, exclusion of pregnant women and children from interventional studies, data and sample sharing, collaborative partnerships including international and local researchers and communities, community engagement and participant information) are presented. To accelerate study approval in future public health emergencies, we recommend: (1) internally consistent and complete submissions with information documents in language participants are likely to understand, (2) close collaboration between local and international researchers from research inception, (3) generation of template agreements for data and sample sharing and use during the ongoing global consultations on bio-banks, (4) formation of Joint Scientific Advisory and Data Safety Review Committees for all studies linked to a particular intervention or group of interventions, (5) formation of a Joint Ethics Review Committee with representatives of the Ethics Committees of all institutions and countries involved to

  3. Dynamics of cholera epidemics with impulsive vaccination and disinfection.

    Science.gov (United States)

    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.

  4. Epidemics on adaptive networks with geometric constraints

    Science.gov (United States)

    Shaw, Leah; Schwartz, Ira

    2008-03-01

    When a population is faced with an epidemic outbreak, individuals may modify their social behavior to avoid exposure to the disease. Recent work has considered models in which the contact network is rewired dynamically so that susceptibles avoid contact with infectives. We consider extensions in which the rewiring is subject to constraints that preserve key properties of the social network structure. Constraining to a fixed degree distribution destroys previously observed bistable behavior. The most effective rewiring strategy is found to depend on the spreading rate.

  5. 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.

  6. 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.

  7. Horizontal antimicrobial resistance transfer drives epidemics of multiple Shigella species.

    Science.gov (United States)

    Baker, Kate S; Dallman, Timothy J; Field, Nigel; Childs, Tristan; Mitchell, Holly; Day, Martin; Weill, François-Xavier; Lefèvre, Sophie; Tourdjman, Mathieu; Hughes, Gwenda; Jenkins, Claire; Thomson, Nicholas

    2018-04-13

    Horizontal gene transfer has played a role in developing the global public health crisis of antimicrobial resistance (AMR). However, the dynamics of AMR transfer through bacterial populations and its direct impact on human disease is poorly elucidated. Here, we study parallel epidemic emergences of multiple Shigella species, a priority AMR organism, in men who have sex with men to gain insight into AMR emergence and spread. Using genomic epidemiology, we show that repeated horizontal transfer of a single AMR plasmid among Shigella enhanced existing and facilitated new epidemics. These epidemic patterns contrasted with slighter, slower increases in disease caused by organisms with vertically inherited (chromosomally encoded) AMR. This demonstrates that horizontal transfer of AMR directly affects epidemiological outcomes of globally important AMR pathogens and highlights the need for integration of genomic analyses into all areas of AMR research, surveillance and management.

  8. Global Changes in Food Supply and the Obesity Epidemic.

    Science.gov (United States)

    Zobel, Emilie H; Hansen, Tine W; Rossing, Peter; von Scholten, Bernt Johan

    2016-12-01

    We explore how a global shift in the food system caused by global economic growth, increase in available food per capita and in food processing is a driver of the obesity epidemic. Economic development in most areas of the world has resulted in increased purchasing power and available per capita food. Supermarkets and a growing fast-food industry have transformed our dietary pattern. Ultra-processed food rich on sugars and saturated fat is now the major source of energy in most countries. The shift in food supply is considered a major driver of the obesity epidemic and the increasing prevalence of accompanying complications, such as type 2 diabetes, cardiovascular disease and cancer. However, the global shift might also have direct effects on the increase in type 2 diabetes, cardiovascular disease and cancer, independently of overweight and obesity. The shift in the food supply is a major driver of the obesity epidemic.

  9. Could the Recent Zika Epidemic Have Been Predicted?

    Directory of Open Access Journals (Sweden)

    Ángel G. Muñoz

    2017-07-01

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

  10. 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.

  11. On the Use of Human Mobility Proxies for Modeling Epidemics

    Science.gov (United States)

    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

  12. Hypothetical Scenario Generator for Fault-Tolerant Diagnosis

    Science.gov (United States)

    James, Mark

    2007-01-01

    The Hypothetical Scenario Generator for Fault-tolerant Diagnostics (HSG) is an algorithm being developed in conjunction with other components of artificial- intelligence systems for automated diagnosis and prognosis of faults in spacecraft, aircraft, and other complex engineering systems. By incorporating prognostic capabilities along with advanced diagnostic capabilities, these developments hold promise to increase the safety and affordability of the affected engineering systems by making it possible to obtain timely and accurate information on the statuses of the systems and predicting impending failures well in advance. The HSG is a specific instance of a hypothetical- scenario generator that implements an innovative approach for performing diagnostic reasoning when data are missing. The special purpose served by the HSG is to (1) look for all possible ways in which the present state of the engineering system can be mapped with respect to a given model and (2) generate a prioritized set of future possible states and the scenarios of which they are parts.

  13. Epidemic optic neuropathy in Cuba. Eye findings.

    Science.gov (United States)

    Sadun, A A; Martone, J F; Muci-Mendoza, R; Reyes, L; DuBois, L; Silva, J C; Roman, G; Caballero, B

    1994-05-01

    To characterize and establish a clinical definition of the optic neuropathy that appeared in epidemic form in Cuba in 1992 and 1993. At the invitation of the Cuban Ministry of Health, Havana, members of ORBIS International and the Pan American Health Organization, assembled teams that traveled to Cuba in May 1993. We were initially briefed by Cuban national experts in the areas of virology, nutrition, toxicology, ophthalmology, neurology, and public health. We then examined 20 patients on our own. Thirteen of these patients underwent a comprehensive neuro-ophthalmologic examination, including neurologic examination, ophthalmologic examination, visual fields, optic nerve function studies, contrast sensitivity studies, and funduscopy. We returned 4 months later to perform an additional 12 comprehensive neuro-ophthalmologic and follow-up examinations. Only seven of the 13 patients who were alleged to have the optic form of the epidemic and who were rigorously and systematically examined on the first visit demonstrated a bilateral optic neuropathy. These seven patients had several features that included decreased visual acuity, poor color vision, central scotomas, decreased contrast sensitivity, saccadic eye movements, and most prominent and distinctive of all, nerve fiber layer wedge defects of the papillomacular bundle. Our clinical definition was then implemented by the Cuban ophthalmologists and epidemiologists. On returning 4 months later, we found that all newly presented patients were correctly diagnosed to have the epidemic disease. With the new case definition and the application of a few simple psychophysical tests, the false-positive rate of diagnosis became much lower. After vitamin therapy, we reexamined the patients seen on our initial visit, and all showed marked improvement. The Cuban epidemic was characterized by an optic neuropathy with features that were similar to those of tobacco/alcohol amblyopia and Leber's optic atrophy. Recent political

  14. Analyses of hypothetical FCI's in a fast reactor

    International Nuclear Information System (INIS)

    Padilla, A. Jr.; Martin, F.J.; Niccoli, L.G.

    1981-01-01

    Parametric analyses using the SIMMER code were performed to evaluate the potential for a severe recriticality from a pressure-driven recompaction caused by an energetic FCI during the transition phase of a hypothetical accident in a fast reactor. For realistic and reasonable estimates for the assumed accident conditions, a severe recriticality was not predicted. The conditions under which a severe recriticality would be obtained or averted were identified. 10 figures, 2 tables

  15. Genome-wide screens for expressed hypothetical proteins

    DEFF Research Database (Denmark)

    Madsen, Claus Desler; Durhuus, Jon Ambæk; Rasmussen, Lene Juel

    2012-01-01

    A hypothetical protein (HP) is defined as a protein that is predicted to be expressed from an open reading frame, but for which there is no experimental evidence of translation. HPs constitute a substantial fraction of proteomes of human as well as of other organisms. With the general belief that...... that the majority of HPs are the product of pseudogenes, it is essential to have a tool with the ability of pinpointing the minority of HPs with a high probability of being expressed....

  16. Computer codes developed in FRG to analyse hypothetical meltdown accidents

    International Nuclear Information System (INIS)

    Hassmann, K.; Hosemann, J.P.; Koerber, H.; Reineke, H.

    1978-01-01

    It is the purpose of this paper to give the status of all significant computer codes developed in the core melt-down project which is incorporated in the light water reactor safety research program of the Federal Ministry of Research and Technology. For standard pressurized water reactors, results of some computer codes will be presented, describing the course and the duration of the hypothetical core meltdown accident. (author)

  17. Epidemics and Frequent Recombination within Species in Outbreaks of Human Enterovirus B-Associated Hand, Foot and Mouth Disease in Shandong China in 2010 and 2011.

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    Full Text Available The epidemiology and molecular characteristics of human enterovirus B (HEV-B associated with hand, foot and mouth disease (HFMD outbreaks in China are not well known. In the present study, we tested 201 HEV isolates from 233 clinical specimens from patients with severe HFMD during 2010-2011 in Linyi, Shandong, China. Of the 201 isolates, 189 were fully typed and 18 corresponded to HEV-B species (six serotypes CVA9, CVB1, CVB4, Echo 6, Echo 25 and Echo 30 using sensitive semi-nested polymerase chain reaction analysis of VP1 gene sequences. Phylogenetic analysis based on the VP1 region showed that eight E30SD belonged to a novel sub-genogroup D2; E25SD belonged to a novel sub-genogroup D6; E6SD belonged to sub-lineage C6 and five CVB1SD belonged to subgroup 4C; and B4SD belonged sub-lineage D2. The full viral genomes of the CVB1SD, E6SD, E25SD and E30SD isolates were sequenced. Analysis of phylogenetic and similarity plots indicated that E25SD recombined with E25-HN-2, E30FDJS03 and E4AUS250 at noncontiguous P2A-P3D regions, while E30SD, E30FDJ03, E25-HN-2 and E9 DM had shared sequences in discrete regions of P2 and P3. Both E6SD and B1SD shared sequences with E1-HN, B4/GX/10, B5-HN, and A9-Alberta in contiguous regions of most of P2 and P3. Genetic algorithm recombination detection analysis further confirmed the existence of multiple potential recombination points. In conclusion, analysis of the complete genomes of E25SD, E30SD, CVB1SD and E6SD isolated from HFMD patients revealed that they formed novel subgenogroup. Given the prevalence and recombination of these viruses in outbreaks of HFMD, persistent surveillance of HFMD-associated HEV-B pathogens is required to predict potential emerging viruses and related disease outbreaks.

  18. Status of vaccines for porcine epidemic diarrhea virus in the United States and Canada

    Science.gov (United States)

    In 2013, porcine epidemic diarrhea virus (PEDV) emerged in the United States as a rapidly spreading epidemic causing dramatic death losses in suckling piglets. Neonatal piglets are most vulnerable to clinical disease and their only protection is passive immunity from their dam. At the end of the thi...

  19. Processing counterfactual and hypothetical conditionals: an fMRI investigation.

    Science.gov (United States)

    Kulakova, Eugenia; Aichhorn, Markus; Schurz, Matthias; Kronbichler, Martin; Perner, Josef

    2013-05-15

    Counterfactual thinking is ubiquitous in everyday life and an important aspect of cognition and emotion. Although counterfactual thought has been argued to differ from processing factual or hypothetical information, imaging data which elucidate these differences on a neural level are still scarce. We investigated the neural correlates of processing counterfactual sentences under visual and aural presentation. We compared conditionals in subjunctive mood which explicitly contradicted previously presented facts (i.e. counterfactuals) to conditionals framed in indicative mood which did not contradict factual world knowledge and thus conveyed a hypothetical supposition. Our results show activation in right occipital cortex (cuneus) and right basal ganglia (caudate nucleus) during counterfactual sentence processing. Importantly the occipital activation is not only present under visual presentation but also with purely auditory stimulus presentation, precluding a visual processing artifact. Thus our results can be interpreted as reflecting the fact that counterfactual conditionals pragmatically imply the relevance of keeping in mind both factual and supposed information whereas the hypothetical conditionals imply that real world information is irrelevant for processing the conditional and can be omitted. The need to sustain representations of factual and suppositional events during counterfactual sentence processing requires increased mental imagery and integration efforts. Our findings are compatible with predictions based on mental model theory. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Learning from Ebola Virus: How to Prevent Future Epidemics

    Directory of Open Access Journals (Sweden)

    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.

  1. Preparation and Response to the 2014 Ebola Virus Disease Epidemic in Nigeria-The Experience of a Tertiary Hospital in Nigeria.

    Directory of Open Access Journals (Sweden)

    Dimie Ogoina

    Full Text Available The 2014 Ebola Virus Disease (EVD outbreak elicited global attention and challenged health systems around the world, Nigeria inclusive. We hereby report the preparation and response to the outbreak by a tertiary teaching hospital in Bayelsa State, Nigeria.Between 4th August and 31st October 2014, we conducted a mixed cross sectional and qualitative study to ascertain the EVD-related fear, myths and misconceptions among healthcare workers (HCWs, and to evaluate the plans, activities and challenges faced by the hospital during the outbreak. Data was collected using a self-administered questionnaire as well as by documented observations during the outbreak. HCWs were asked to rate their fear of EVD from 1 (no fear to 10 (highest fear.Out of 189 respondents, majority (>75% reported uncertainty about the myth that EVD can be prevented by drinking salt water or eating Garcinia kola, while 82% of respondents believed that EVD can be prevented by avoiding crowded places. About 40% of respondents expressed fear ratings of EVD of ≥ 7 out of 10. In response to the outbreak, the hospital established an EVD response team, organised EVD-sensitization and training programmes and commenced routine EVD surveillance activities. An EVD-isolation ward was constructed from an existing ward, a field incinerator was designed, hand sanitizers were produced locally and personal protective equipment were procured. No case of EVD was reported in the hospital, although three false alarms caused panic. Some HCWs adopted overly protective and avoidance behaviours, but these behaviours were abandoned after the outbreak was declared over.Our results suggest that the fear, myth and misconceptions were common among HCW during the outbreak. The EVD outbreak, however, helped to strengthen gaps in infection control and emergency preparedness in the hospital. Strategies to allay fear are required to contain future outbreaks of EVD in Nigeria hospitals.

  2. 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

  3. Understanding Ebola: the 2014 epidemic.

    Science.gov (United States)

    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.

  4. Colliding Epidemics and the Rise of Cryptococcosis

    Directory of Open Access Journals (Sweden)

    Christina C. Chang

    2015-12-01

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

  5. Epidemic spreading on interconnected networks.

    Science.gov (United States)

    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.

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  7. Association of Drought with Typhus Epidemics in Central Mexico

    Science.gov (United States)

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

    2007-05-01

    Typhus is an acute infectious disease caused by the bacteria Rickettsia prowazekii, which is transmitted among humans by the body lice (Pediculus humanus corporis). The disease is highly contagious and transmission is favored in populations living in crowded conditions. Under these circumstances, typhus transmission is facilitated by factors that favor the colonization and proliferation of body lice such as absence of personal hygiene and wearing the same clothes for long periods of time. Historically, periods of war and famine were associated with devastating epidemics with high mortality rates in many parts of the world. Central Mexico has a long record of typhus epidemics. In this region, at > 2000 meters above sea level, the disease was endemic and occurred with a seasonal pattern in winter, with occasional large epidemics. Recently, we completed a chronology of epidemics in Mexico. A total of 22 well-defined major typhus epidemics were identified between 1650 and 1920. All of them caused periods of increased mortality that lasted 2 - 4 years (more than one standard deviation from the previous ten year period). The record of typhus epidemics was evaluated against the tree-ring record of Cuauhtmoc La Fragua, Puebla. This chronology, based on Douglas fir, has demonstrated to be a faithful record of precipitation in central Mexico. The results indicate that a statistically significant drought (t test, p 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.

  8. 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

  9. Topology dependent epidemic spreading velocity in weighted networks

    NARCIS (Netherlands)

    Duan, W.; Quax, R.; Lees, M.; Qiu, X.; Sloot, P.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

  10. Improving epidemic malaria planning, preparedness and response in Southern Africa. Report on the 1st Southern African Regional Epidemic Outlook Forum, Harare, Zimbabwe, 26-29 September, 2004.

    Science.gov (United States)

    DaSilva, Joaquim; Garanganga, Brad; Teveredzi, Vonai; Marx, Sabine M; Mason, Simon J; Connor, Stephen J

    2004-10-22

    Malaria is a major public health problem for countries in the Southern Africa Development Community (SADC). While the endemicity of malaria varies enormously across this region, many of the countries have districts that are prone to periodic epidemics, which can be regional in their extent, and to resurgent outbreaks that are much more localized. These epidemics are frequently triggered by climate anomalies and often follow periods of drought. Many parts of Southern Africa have suffered rainfall deficit over the past three years and countries expect to see increased levels of malaria when the rains return to more 'normal' levels. Problems with drug and insecticide resistance are documented widely and the region contains countries with the highest rates of HIV prevalence to be found anywhere in the world. Consequently, many communities are vulnerable to severe disease outcomes should epidemics occur. The SADC countries have adopted the Abuja targets for Roll Back Malaria in Africa, which include improved epidemic detection and response, i.e., that 60% of epidemics will be detected within two weeks of onset, and 60% of epidemics will be responded to within two weeks of detection. The SADC countries recognize that to achieve these targets they need improved information on where and when to look for epidemics. The WHO integrated framework for improved early warning and early detection of malaria epidemics has been recognized as a potentially useful tool for epidemic preparedness and response planning. Following evidence of successful adoption and implementation of this approach in Botswana, the SADC countries, the WHO Southern Africa Inter-Country Programme on Malaria Control, and the SADC Drought Monitoring Centre decided to organize a regional meeting where countries could gather to assess their current control status and community vulnerability, consider changes in epidemic risk, and develop a detailed plan of action for the forthcoming 2004-2005 season. The

  11. Ebola epidemic of 2014-2015: unresolved ethical issues.

    Science.gov (United States)

    Garbuglia, Anna Rosa

    2016-01-01

    Some ethical aspects of the management of the Ebola epidemic in Guinea, Liberia and Sierra Leone which started in January 2014, have been questionable. First, as regards the prevention of the spread of the virus, the necessary epidemiological investigations on the origin of the infection were not carried out adequately and this did not help to curb the spread of the disease. A disparity has been observed between the western and African countries' access to the treatment of patients; this infringes on the principle of equality. This paper also focuses on how the Global Public Goods for Health principle was not fully respected in the management of the epidemic.

  12. Community Size Effects on Epidemic Spreading in Multiplex Social Networks.

    Directory of Open Access Journals (Sweden)

    Ting Liu

    Full Text Available The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explore the interactions between disease spreading and population response in terms of information diffusion and individuals' alertness. We model the system by mapping multiplex networks into two-layer networks and incorporating individuals' risk awareness, on the assumption that their response to the disease spreading depends on the size of the community they belong to. By comparing the final incidence of diseases in multiplex networks, we find that there is considerable mitigation of diseases spreading for full phase of spreading speed when individuals' protection responses are introduced. Interestingly, the degree of community overlap between the two layers is found to be critical factor that affects the final incidence. We also analyze the consequences of the epidemic incidence in communities with different sizes and the impacts of community overlap between two layers. Specifically, as the diseases information makes individuals alert and take measures to prevent the diseases, the effective protection is more striking in small community. These phenomena can be explained by the multiplexity of the networked system and the competition between two spreading processes.

  13. Community Size Effects on Epidemic Spreading in Multiplex Social Networks.

    Science.gov (United States)

    Liu, Ting; Li, Ping; Chen, Yan; Zhang, Jie

    2016-01-01

    The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explore the interactions between disease spreading and population response in terms of information diffusion and individuals' alertness. We model the system by mapping multiplex networks into two-layer networks and incorporating individuals' risk awareness, on the assumption that their response to the disease spreading depends on the size of the community they belong to. By comparing the final incidence of diseases in multiplex networks, we find that there is considerable mitigation of diseases spreading for full phase of spreading speed when individuals' protection responses are introduced. Interestingly, the degree of community overlap between the two layers is found to be critical factor that affects the final incidence. We also analyze the consequences of the epidemic incidence in communities with different sizes and the impacts of community overlap between two layers. Specifically, as the diseases information makes individuals alert and take measures to prevent the diseases, the effective protection is more striking in small community. These phenomena can be explained by the multiplexity of the networked system and the competition between two spreading processes.

  14. Reducing therapeutic misconception: A randomized intervention trial in hypothetical clinical trials.

    Directory of Open Access Journals (Sweden)

    Paul P Christopher

    Full Text Available Participants in clinical trials frequently fail to appreciate key differences between research and clinical care. This phenomenon, known as therapeutic misconception, undermines informed consent to clinical research, but to date there have been no effective interventions to reduce it and concerns have been expressed that to do so might impede recruitment. We determined whether a scientific reframing intervention reduces therapeutic misconception without significantly reducing willingness to participate in hypothetical clinical trials.This prospective randomized trial was conducted from 2015 to 2016 to test the efficacy of an informed consent intervention based on scientific reframing compared to a traditional informed consent procedure (control in reducing therapeutic misconception among patients considering enrollment in hypothetical clinical trials modeled on real-world studies for one of five disease categories. Patients with diabetes mellitus, hypertension, coronary artery disease, head/neck cancer, breast cancer, and major depression were recruited from medical clinics and a clinical research volunteer database. The primary outcomes were therapeutic misconception, as measured by a validated, ten-item Therapeutic Misconception Scale (range = 10-50, and willingness to participate in the clinical trial.154 participants completed the study (age range, 23-87 years; 92.3% white, 56.5% female; 74 (48.1% had been randomized to receive the experimental intervention. Therapeutic misconception was significantly lower (p = 0.004 in the scientific reframing group (26.4, 95% CI [23.7 to 29.1] compared to the control group (30.9, 95% CI [28.4 to 33.5], and remained so after controlling for education (p = 0.017. Willingness to participate in the hypothetical trial was not significantly different (p = 0.603 between intervention (52.1%, 95% CI [40.2% to 62.4%] and control (56.3%, 95% CI [45.3% to 66.6%] groups.An enhanced educational intervention augmenting

  15. The spatial resolution of epidemic peaks.

    Directory of Open Access Journals (Sweden)

    Harriet L Mills

    2014-04-01

    Full Text Available The emergence of novel respiratory pathogens can challenge the capacity of key health care resources, such as intensive care units, that are constrained to serve only specific geographical populations. An ability to predict the magnitude and timing of peak incidence at the scale of a single large population would help to accurately assess the value of interventions designed to reduce that peak. However, current disease-dynamic theory does not provide a clear understanding of the relationship between: epidemic trajectories at the scale of interest (e.g. city; population mobility; and higher resolution spatial effects (e.g. transmission within small neighbourhoods. Here, we used a spatially-explicit stochastic meta-population model of arbitrary spatial resolution to determine the effect of resolution on model-derived epidemic trajectories. We simulated an influenza-like pathogen spreading across theoretical and actual population densities and varied our assumptions about mobility using Latin-Hypercube sampling. Even though, by design, cumulative attack rates were the same for all resolutions and mobilities, peak incidences were different. Clear thresholds existed for all tested populations, such that models with resolutions lower than the threshold substantially overestimated population-wide peak incidence. The effect of resolution was most important in populations which were of lower density and lower mobility. With the expectation of accurate spatial incidence datasets in the near future, our objective was to provide a framework for how to use these data correctly in a spatial meta-population model. Our results suggest that there is a fundamental spatial resolution for any pathogen-population pair. If underlying interactions between pathogens and spatially heterogeneous populations are represented at this resolution or higher, accurate predictions of peak incidence for city-scale epidemics are feasible.

  16. 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.

  17. Epidemic Synchronization in Robotic Swarms

    DEFF Research Database (Denmark)

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

    2009-01-01

    Clock synchronization in swarms of networked mobile robots is studied in a probabilistic, epidemic framework. In this setting communication and synchonization is considered to be a randomized process, taking place at unplanned instants of geographical rendezvous between robots. In combination...... as an infinite-dimensional optimal controlproblem. Illustrative numerical examples are given and commented....

  18. The First American Cocaine Epidemic.

    Science.gov (United States)

    Courtwright, David T.

    1991-01-01

    Discusses the wave of cocaine abuse that followed the drug's recommendation by the late nineteenth-century medical community as a cure all. Details drug addiction among ethnic and social groups at the turn of the century. Warns that drug epidemics have important social and legal consequences. Suggests legal pressure may alter the form of drug…

  19. Epidemic Synchronization in Robotic Swarms

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  20. 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.

  1. 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.

  2. The paralytic poliomyelitis epidemic of 1978 in Jordan: epidemiological implications

    Science.gov (United States)

    Khuri-Bulos, Najwa; Melnick, Joseph L.; Hatch, Milford H.; Dawod, Saleh T.

    1984-01-01

    Poliomyelitis is endemic in Jordan, but until 1978 there were no epidemics. In that year, 66 children were admitted to the Jordan University Hospital with a paralytic illness, compared with 13 in 1979 and 11 in 1980. The epidemic reached a peak in the summer and fall of 1978. While 54% of the patients had not received any vaccine, 19% had received 3 doses of oral poliovaccine; 82% of the cases were in children less than 2 years of age, and all belonged to the lower socioeconomic group. There were 28 deaths with complications of the disease. Poliovirus was isolated from 10 out of 14 rectal swab samples examined (9 with poliovirus 1, 1 with poliovirus 2), and from 4 out of 13 throat specimens from the same patients. It is concluded that as a result of improving living standards in Jordan and neighbouring countries, more epidemics may occur unless immunization efforts against poliomyelitis are intensified. PMID:6609022

  3. 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.

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

    KAUST Repository

    Paarporn, Keith

    2016-04-20

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

  5. Demand curves for hypothetical cocaine in cocaine-dependent individuals.

    Science.gov (United States)

    Bruner, Natalie R; Johnson, Matthew W

    2014-03-01

    Drug purchasing tasks have been successfully used to examine demand for hypothetical consumption of abused drugs including heroin, nicotine, and alcohol. In these tasks, drug users make hypothetical choices whether to buy drugs, and if so, at what quantity, at various potential prices. These tasks allow for behavioral economic assessment of that drug's intensity of demand (preferred level of consumption at extremely low prices) and demand elasticity (sensitivity of consumption to price), among other metrics. However, a purchasing task for cocaine in cocaine-dependent individuals has not been investigated. This study examined a novel Cocaine Purchasing Task and the relation between resulting demand metrics and self-reported cocaine use data. Participants completed a questionnaire assessing hypothetical purchases of cocaine units at prices ranging from $0.01 to $1,000. Demand curves were generated from responses on the Cocaine Purchasing Task. Correlations compared metrics from the demand curve to measures of real-world cocaine use. Group and individual data were well modeled by a demand curve function. The validity of the Cocaine Purchasing Task was supported by a significant correlation between the demand curve metrics of demand intensity and O max (determined from Cocaine Purchasing Task data) and self-reported measures of cocaine use. Partial correlations revealed that after controlling for demand intensity, demand elasticity and the related measure, P max, were significantly correlated with real-world cocaine use. Results indicate that the Cocaine Purchasing Task produces orderly demand curve data, and that these data relate to real-world measures of cocaine use.

  6. [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

  7. Consequences of a hypothetical incident for different sectors

    CERN Document Server

    Bertinelli, F; Garion, C; Jimenez, J M; Parma, V; Perin, A; Schmidt, R; Tavian, L; Tock, J P; van Weelderen, R

    2011-01-01

    During the 2009 long shutdown, the LHC machine has been partially consolidated by adding safety relief devices in order to better protect the cryostats against large helium release and consequently to mitigate the risks of collateral damages. After recalling the present relief valve implementation and other mitigations related to the collateral damages, this paper describes the damage process of a hypothetical incident, presents its consequences for the different sectors and for beam energies up to 5 TeV with emphasis on the induced downtime.

  8. Effects of hypothetical improvised nuclear detonation on the electrical infrastructure

    International Nuclear Information System (INIS)

    Barrett, Christopher L.; Eubank, Stephen; Evrenosoglu, C. Yaman; Marathe, Achla; Marathe, Madhav V.; Phadke, Arun; Thorp, James; Vullikanti, Anil

    2013-01-01

    We study the impacts of a hypothetical improvised nuclear detonation (IND) on the electrical infrastructure and its cascading effects on other urban inter-dependent infrastructures of a major metropolitan area in the US. We synthesize open source information, expert knowledge, commercial software and Google Earth data to derive a realistic electrical transmission and distribution network spanning the region. A dynamic analysis of the geo-located grid is carried out to determine the cause of malfunction of components, and their short-term and long-term effect on the stability of the grid. Finally a detailed estimate of the cost of damage to the major components of the infrastructure is provided.

  9. Nuclear Reactor RA Safety Report, Vol. 16, Maximum hypothetical accident

    International Nuclear Information System (INIS)

    1986-11-01

    Fault tree analysis of the maximum hypothetical accident covers the basic elements: accident initiation, phase development phases - scheme of possible accident flow. Cause of the accident initiation is the break of primary cooling pipe, heavy water system. Loss of primary coolant causes loss of pressure in the primary circuit at the coolant input in the reactor vessel. This initiates safety protection system which should automatically shutdown the reactor. Separate chapters are devoted to: after-heat removal, coolant and moderator loss; accident effects on the reactor core, effects in the reactor building, and release of radioactive wastes [sr

  10. Effects of hypothetical improvised nuclear detonation on the electrical infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, Christopher L.; Eubank, Stephen; Evrenosoglu, C. Yaman; Marathe, Achla; Marathe, Madhav V.; Phadke, Arun; Thorp, James; Vullikanti, Anil [Virginia Tech, Blacksburg, VA (United States). Network Dynamics and Simulation Science Lab.

    2013-07-01

    We study the impacts of a hypothetical improvised nuclear detonation (IND) on the electrical infrastructure and its cascading effects on other urban inter-dependent infrastructures of a major metropolitan area in the US. We synthesize open source information, expert knowledge, commercial software and Google Earth data to derive a realistic electrical transmission and distribution network spanning the region. A dynamic analysis of the geo-located grid is carried out to determine the cause of malfunction of components, and their short-term and long-term effect on the stability of the grid. Finally a detailed estimate of the cost of damage to the major components of the infrastructure is provided.

  11. Epidemics in adaptive networks with community structure

    Science.gov (United States)

    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.

  12. Mathematical models in medicine: Diseases and epidemics

    International Nuclear Information System (INIS)

    Witten, M.

    1987-01-01

    This volume presents the numerous applications of mathematics in the life sciences and medicine, and demonstrates how mathematics and computers have taken root in these fields. The work covers a variety of techniques and applications including mathematical and modelling methodology, modelling/simulation technology, and philosophical issues in model formulation, leading to speciality medical modelling, artificial intelligence, psychiatric models, medical decision making, and molecular modelling

  13. 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.

  14. 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.

  15. 33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Hypothetical Example of Cost... APPORTIONMENT OF BRIDGE ALTERATIONS Pt. 277, App. B Appendix B to Part 277—Hypothetical Example of Cost... bridge was completed in 1908 and the superstructure completed in 1909. For this hypothetical example it...

  16. CHEMICAL VERSUS SERUM TREATMENT OF EPIDEMIC MENINGITIS.

    Science.gov (United States)

    Flexner, S; Amoss, H L

    1916-05-01

    of meningococci, and neither possesses antitoxic power. The mixture of antiserum with lysol and with protargol reduces to a certain extent the antileukotactic and antiphagocytic effect of the chemicals; but this action is insufficient to set aside wholly the injurious effects which they produce. It follows, therefore, that whatever theoretical advantages might accrue from a bactericidal activity exerted by these chemicals independently of the type of meningococcus causing epidemic meningitis, is more than offset by the harmful effects which they cause. Hence specific antiserum seems to provide the logical therapeutic agent with which to combat epidemic meningitis, since it is itself innocuous and promotes those processes essential to recovery from the disease. The problem up to the present has been that of producing an antiserum which represents the several types of the meningococcus, and this problem is now in a fair way to being solved.

  17. Vaccines as Epidemic Insurance.

    Science.gov (United States)

    Pauly, Mark V

    2017-10-27

    This paper explores the relationship between the research for and development of vaccines against global pandemics and insurance. It shows that development in advance of pandemics of a portfolio of effective and government-approved vaccines does have some insurance properties: it requires incurring costs that are certain (the costs of discovering, developing, and testing vaccines) in return for protection against large losses (if a pandemic treatable with one of the vaccines occurs) but also with the possibility of no benefit (from a vaccine against a disease that never reaches the pandemic stage). It then argues that insurance against the latter event might usefully be offered to organizations developing vaccines, and explores the benefits of insurance payments to or on behalf of countries who suffer from unpredictable pandemics. These ideas are then related to recent government, industry, and philanthropic efforts to develop better policies to make vaccines against pandemics available on a timely basis.

  18. Vaccines as Epidemic Insurance

    Directory of Open Access Journals (Sweden)

    Mark V. Pauly

    2017-10-01

    Full Text Available This paper explores the relationship between the research for and development of vaccines against global pandemics and insurance. It shows that development in advance of pandemics of a portfolio of effective and government-approved vaccines does have some insurance properties: it requires incurring costs that are certain (the costs of discovering, developing, and testing vaccines in return for protection against large losses (if a pandemic treatable with one of the vaccines occurs but also with the possibility of no benefit (from a vaccine against a disease that never reaches the pandemic stage. It then argues that insurance against the latter event might usefully be offered to organizations developing vaccines, and explores the benefits of insurance payments to or on behalf of countries who suffer from unpredictable pandemics. These ideas are then related to recent government, industry, and philanthropic efforts to develop better policies to make vaccines against pandemics available on a timely basis.

  19. Modelling dengue epidemic spreading with human mobility

    Science.gov (United States)

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

    2016-04-01

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

  20. Trial of risk assessment of a hypothetical nuclear facility

    International Nuclear Information System (INIS)

    Terao, Norichika; Suzuki, Mitsutoshi

    2013-01-01

    An equation for risk assessment in physical protection is shown by a probability of an adversary attack during a period time, P A , a probability of system effectiveness, P E , and consequence value, C. In addition, P E is shown as the multiplication of a probability of interruption of the facility, P I , by a probability of neutralization by response force, P N . In this study, it is assumed that an adversary assaults a hypothetical nuclear facility. The new quantification method about P A and P I in risk evaluation formula is devised, and risk assessment is attempted. In case of P A , the possibility of assaults against a nuclear facility is discussed by using terrorism data written in the open source database of terrorism, Global Terrorism Database (GTD), summarized by University of Maryland. In addition, it is discussed about P I by using the way of thinking of a risk assessment tool, EASI, developed by the Sandia National Laboratories (SNL). In the hypothetical nuclear facility, the performance of response force, sensors, and communication is expressed quantitatively by probability distribution based on some assumptions. (author)

  1. Evaluation of Nuclide Release Scenarios for a Hypothetical LILW Repository

    International Nuclear Information System (INIS)

    Lee, Youn Myoung; Jeong, Jong Tae

    2010-11-01

    A program for the safety assessment and performance evaluation of a low- and intermediate-level radioactive waste (LILW) repository system has been developed. Utilizing GoldSim (GoldSim, 2006), the program evaluates nuclide release and transport into the geosphere and biosphere under various disruptive natural and manmade events and scenarios that can occur after a waste package failure. We envisaged and illustrated these events and scenarios as occurring after the closure of a hypothetical LILW repository, and they included the degradation of various manmade barriers, pumping well drilling, and natural disruptions such as the sudden formation of a preferential flow pathway in the far-field area of the repository. Possible enhancement of nuclide transport facilitated by colloids or chelating agents is also dealt with. We used the newly-developed GoldSim template program, which is capable of various nuclide release scenarios and is greatly suited for simulating a potential repository given the geological circumstances in Korea, to create the detailed source term and near-field release scheme, various nuclide transport modes in the far-field geosphere area, and the biosphere transfer. Even though all parameter values applied to the hypothetical repository were assumed, the illustrative results, particularly the probabilistic calculations and sensitivity studies, may be informative under various scenarios

  2. Treating Obesity As a Disease

    Science.gov (United States)

    ... Obesity, And What You Can Do Understanding the American Obesity Epidemic Stress Management How Does Stress Affect You? ... Keeping the Weight Off • Obesity - Introduction - Understanding the American Obesity Epidemic - Treating Obesity as a Disease - Childhood Obesity ...

  3. Quantifying the quiet epidemic

    Science.gov (United States)

    2014-01-01

    During the late 20th century numerical rating scales became central to the diagnosis of dementia and helped transform attitudes about its causes and prevalence. Concentrating largely on the development and use of the Blessed Dementia Scale, I argue that rating scales served professional ends during the 1960s and 1970s. They helped old age psychiatrists establish jurisdiction over conditions such as dementia and present their field as a vital component of the welfare state, where they argued that ‘reliable modes of diagnosis’ were vital to the allocation of resources. I show how these arguments appealed to politicians, funding bodies and patient groups, who agreed that dementia was a distinct disease and claimed research on its causes and prevention should be designated ‘top priority’. But I also show that worries about the replacement of clinical acumen with technical and depersonalized methods, which could conceivably be applied by anyone, led psychiatrists to stress that rating scales had their limits and could be used only by trained experts. PMID:25866448

  4. 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.

  5. 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.

  6. Sudden transitions in coupled opinion and epidemic dynamics with vaccination

    Science.gov (United States)

    Pires, Marcelo A.; Oestereich, André L.; Crokidakis, Nuno

    2018-05-01

    This work consists of an epidemic model with vaccination coupled with an opinion dynamics. Our objective was to study how disease risk perception can influence opinions about vaccination and therefore the spreading of the disease. Differently from previous works we have considered continuous opinions. The epidemic spreading is governed by an SIS-like model with an extra vaccinated state. In our model individuals vaccinate with a probability proportional to their opinions. The opinions change due to peer influence in pairwise interactions. The epidemic feedback to the opinion dynamics acts as an external field increasing the vaccination probability. We performed Monte Carlo simulations in fully-connected populations. Interestingly we observed the emergence of a first-order phase transition, besides the usual active-absorbing phase transition presented in the SIS model. Our simulations also show that with a certain combination of parameters, an increment in the initial fraction of the population that is pro-vaccine has a twofold effect: it can lead to smaller epidemic outbreaks in the short term, but it also contributes to the survival of the chain of infections in the long term. Our results also suggest that it is possible that more effective vaccines can decrease the long-term vaccine coverage. This is a counterintuitive outcome, but it is in line with empirical observations that vaccines can become a victim of their own success.

  7. One Hundred Years in the Making: The Global Tobacco Epidemic.

    Science.gov (United States)

    Wipfli, Heather; Samet, Jonathan M

    2016-01-01

    Today's global tobacco epidemic may represent one of the first instances of the globalization of a noninfectious cause of disease. This article focuses on the first century of the global tobacco epidemic and its current status, reviewing the current and projected future of the global tobacco epidemic and the steps that are in progress to end it. In the United States and many countries of Western Europe, tobacco consumption peaked during the 1960s and 1970s and declined as tobacco control programs were initiated, motivated by the evidence indicting smoking as a leading cause of disease. Despite this policy advancement and the subsequent reductions in tobacco consumption, the global tobacco epidemic continued to grow exponentially in the later years of the twentieth century, as the multinational companies sought new markets to replace those shrinking in high-income countries. In response, between 2000 and 2004, the World Health Organization developed its first public health treaty, the Framework Convention on Tobacco Control, which entered into force in 2005. An accompanying package of interventions has been implemented. New approaches to tobacco control, including plain packaging and single representation of brands, have been implemented by Australia and Uruguay, respectively, but have been challenged by the tobacco industry.

  8. Epidemic processes in complex networks

    OpenAIRE

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

    2015-01-01

    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 t...

  9. Epidemic spreading on adaptively weighted scale-free networks.

    Science.gov (United States)

    Sun, Mengfeng; Zhang, Haifeng; Kang, Huiyan; Zhu, Guanghu; Fu, Xinchu

    2017-04-01

    We introduce three modified SIS models on scale-free networks that take into account variable population size, nonlinear infectivity, adaptive weights, behavior inertia and time delay, so as to better characterize the actual spread of epidemics. We develop new mathematical methods and techniques to study the dynamics of the models, including the basic reproduction number, and the global asymptotic stability of the disease-free and endemic equilibria. We show the disease-free equilibrium cannot undergo a Hopf bifurcation. We further analyze the effects of local information of diseases and various immunization schemes on epidemic dynamics. We also perform some stochastic network simulations which yield quantitative agreement with the deterministic mean-field approach.

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

    Science.gov (United States)

    Jung, Kwonil; Saif, Linda J

    2015-05-01

    Porcine epidemic diarrhea virus (PEDV), a member of the genera Alphacoronavirus in the family Coronaviridae, causes acute diarrhea/vomiting, dehydration and high mortality in seronegative neonatal piglets. For the last three decades, PEDV infection has resulted in significant economic losses in the European and Asian pig industries, but in 2013-2014 the disease was also reported in the US, Canada and Mexico. The PED epidemic in the US, from April 2013 to the present, has led to the loss of more than 10% of the US pig population. The disappearance and re-emergence of epidemic PED indicates that the virus is able to escape from current vaccination protocols, biosecurity and control systems. Endemic PED is a significant problem, which is exacerbated by the emergence (or potential importation) of multiple PEDV variants. Epidemic PEDV strains spread rapidly and cause a high number of pig deaths. These strains are highly enteropathogenic and acutely infect villous epithelial cells of the entire small and large intestines although the jejunum and ileum are the primary sites. PEDV infections cause acute, severe atrophic enteritis accompanied by viremia that leads to profound diarrhea and vomiting, followed by extensive dehydration, which is the major cause of death in nursing piglets. A comprehensive understanding of the pathogenic characteristics of epidemic or endemic PEDV strains is needed to prevent and control the disease in affected regions and to develop an effective vaccine. This review focuses on the etiology, epidemiology, disease mechanisms and pathogenesis as well as immunoprophylaxis against PEDV infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  12. 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

  13. Monitoring linked epidemics: the case of tuberculosis and HIV.

    Directory of Open Access Journals (Sweden)

    María S Sánchez

    Full Text Available BACKGROUND: The tight epidemiological coupling between HIV and its associated opportunistic infections leads to challenges and opportunities for disease surveillance. METHODOLOGY/PRINCIPAL FINDINGS: We review efforts of WHO and collaborating agencies to track and fight the TB/HIV co-epidemic, and discuss modeling--via mathematical, statistical, and computational approaches--as a means to identify disease indicators designed to integrate data from linked diseases in order to characterize how co-epidemics change in time and space. We present R(TB/HIV, an index comparing changes in TB incidence relative to HIV prevalence, and use it to identify those sub-Saharan African countries with outlier TB/HIV dynamics. R(TB/HIV can also be used to predict epidemiological trends, investigate the coherency of reported trends, and cross-check the anticipated impact of public health interventions. Identifying the cause(s responsible for anomalous R(TB/HIV values can reveal information crucial to the management of public health. CONCLUSIONS/SIGNIFICANCE: We frame our suggestions for integrating and analyzing co-epidemic data within the context of global disease monitoring. Used routinely, joint disease indicators such as R(TB/HIV could greatly enhance the monitoring and evaluation of public health programs.

  14. Travelling Wave Solutions in Multigroup Age-Structured Epidemic Models

    Science.gov (United States)

    Ducrot, Arnaut; Magal, Pierre; Ruan, Shigui

    2010-01-01

    Age-structured epidemic models have been used to describe either the age of individuals or the age of infection of certain diseases and to determine how these characteristics affect the outcomes and consequences of epidemiological processes. Most results on age-structured epidemic models focus on the existence, uniqueness, and convergence to disease equilibria of solutions. In this paper we investigate the existence of travelling wave solutions in a deterministic age-structured model describing the circulation of a disease within a population of multigroups. Individuals of each group are able to move with a random walk which is modelled by the classical Fickian diffusion and are classified into two subclasses, susceptible and infective. A susceptible individual in a given group can be crisscross infected by direct contact with infective individuals of possibly any group. This process of transmission can depend upon the age of the disease of infected individuals. The goal of this paper is to provide sufficient conditions that ensure the existence of travelling wave solutions for the age-structured epidemic model. The case of two population groups is numerically investigated which applies to the crisscross transmission of feline immunodeficiency virus (FIV) and some sexual transmission diseases.

  15. How heterogeneous susceptibility and recovery rates affect the spread of epidemics on networks

    Directory of Open Access Journals (Sweden)

    Wei Gou

    2017-08-01

    Full Text Available In this paper, an extended heterogeneous SIR model is proposed, which generalizes the heterogeneous mean-field theory. Different from the traditional heterogeneous mean-field model only taking into account the heterogeneity of degree, our model considers not only the heterogeneity of degree but also the heterogeneity of susceptibility and recovery rates. Then, we analytically study the basic reproductive number and the final epidemic size. Combining with numerical simulations, it is found that the basic reproductive number depends on the mean of distributions of susceptibility and disease course when both of them are independent. If the mean of these two distributions is identical, increasing the variance of susceptibility may block the spread of epidemics, while the corresponding increase in the variance of disease course has little effect on the final epidemic size. It is also shown that positive correlations between individual susceptibility, course of disease and the square of degree make the population more vulnerable to epidemic and avail to the epidemic prevalence, whereas the negative correlations make the population less vulnerable and impede the epidemic prevalence. Keywords: Networks, Heterogeneity, Susceptibility, Recovery rates, Correlation, The basic reproductive number, The final epidemic size

  16. Epidemics and dimensionality in hierarchical networks

    Science.gov (United States)

    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).

  17. 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.

  18. Quarantine generated phase transition in epidemic spreading

    Science.gov (United States)

    Dicksion, Mark; Lagorio, Cecilia; Vazquez, F.; Braunstein, L.; Macri, P. A.; Migueles, M. V.; Havlin, S.; Stanley, H. E.

    2011-03-01

    We study the critical effect of quarantine on the propagation of epidemics on an adaptive network of social contacts. For this purpose, we analyze the susceptible-infected-recovered (SIR) model in the presence of quarantine, where susceptible individuals protect themselves by disconnecting their links to infected neighbors with probability w, and reconnecting them to other susceptible individuals chosen at random. Starting from a single infected individual, we show by an analytical approach and simulations that there is a phase transition at a critical rewiring (quarantine) threshold wc separating a phase (w =wc) where the disease does not spread out. We find that in our model the topology of the network strongly affects the size of the propagation, and that wc increases with the mean degree and heterogeneity of the network. We also find that wc is reduced if we perform a preferential rewiring, in which the rewiring probability is proportional to the degree of infected nodes.

  19. Epidemic Dynamics in Open Quantum Spin Systems

    Science.gov (United States)

    Pérez-Espigares, Carlos; Marcuzzi, Matteo; Gutiérrez, Ricardo; Lesanovsky, Igor

    2017-10-01

    We explore the nonequilibrium evolution and stationary states of an open many-body system that displays epidemic spreading dynamics in a classical and a quantum regime. Our study is motivated by recent experiments conducted in strongly interacting gases of highly excited Rydberg atoms where the facilitated excitation of Rydberg states competes with radiative decay. These systems approximately implement open quantum versions of models for population dynamics or disease spreading where species can be in a healthy, infected or immune state. We show that in a two-dimensional lattice, depending on the dominance of either classical or quantum effects, the system may display a different kind of nonequilibrium phase transition. We moreover discuss the observability of our findings in laser driven Rydberg gases with particular focus on the role of long-range interactions.

  20. RELAP 5 Simulations of a hypothetical LOCA in Ringhals 2

    International Nuclear Information System (INIS)

    Caraher, D.

    1987-01-01

    RELAP5 simulations of a hypothetical LOCA in Ringhals 2 were conducted in order to determine the sensitivity of the calculated peak cladding temperature (PCT) to Appendix K requirements. The PCT was most sensitive to the assumed model decay heat: Changing from the 1979 ANS Standard to 1.2 times the 1973 Standard increased the PCT by 70 to 100K. After decay heat, the two parameters which affected the PCT the most were steam generator heat transfer and heat transfer lockout. The PCT was not sensitive to the assumed pump rotor condition (locked vs coasting); nor was it sensitive to a modest amount (5 to 10%) of steam generator tube plugging. (author)

  1. Hanford groundwater transport estimates for hypothetical radioactive waste incidents

    International Nuclear Information System (INIS)

    Arnett, R.C.; Brown, D.J.; Baca, R.G.

    1977-06-01

    This report presents an analysis of the impact of subsurface contamination resulting from a series of hypothetical leaks or accidents involving Hanford high-level radioactive defense waste. Estimates of the amounts and concentrations of radionuclides reaching the Columbia River through the Hanford unconfined aquifer flow path were obtained by means of predictive models. The results of the study showed that the spatially averaged concentrations of 99 Tc, 3 H, and 106 Ru in the ground water as it discharges into the Columbia River are at all times far below the respective ERDA Manual Chapter 0524 Concentration Guides for uncontrolled areas. Upon entering the Columbia River, additional large dilutions of the water containing trace quantities of contaminants will occur

  2. Willingness to pay for three hypothetical malaria vaccines in Nigeria.

    Science.gov (United States)

    Udezi, Waka Anthony; Usifoh, Cyril Odianose; Ihimekpen, Omoyeme Oluwatosin

    2010-08-01

    Unlike some African countries that have reported a approximately 50% reduction in malaria deaths in recent years, Nigeria has shown no evidence of a systematic decline in malaria burden. An important and sustainable reduction in malaria burden cannot be achieved unless an effective and inexpensive malaria vaccine becomes available. The goals of this study were to determine the willingness to pay (WTP) for 3 hypothetical malaria vaccines with different levels of protection (in years), effectiveness, and adverse effects; and to identify factors that influence the price that people are willing to pay in Nigeria. With the aid of a questionnaire, a contingent valuation method using payment cards was used to elicit WTP values for 3 hypothetical malaria vaccines. Payment cards contained both a description of the features of the vaccine being evaluated and price options. The 3 hypothetical vaccines had the following characteristics: vaccine A was 75% effective, protected for 3 years, and was well tolerated; vaccine B was 85% effective, protected for 6 years, and was less well tolerated than vaccine A; and vaccine C was 95% effective and protected for 12 years, but was the least well tolerated. Participants consisted of a convenience sample of individuals who were at the pharmacy waiting area of the state-owned hospitals located in Benin City and Warri, Nigeria. Every third patient or caregiver who was in the pharmacy to fill a prescription was asked to take part in the study as they waited to see the pharmacist. If consent was not granted, the next person in line was approached to be interviewed. Linear multiple regression analysis and nonparametric Kruskal-Wallis, Mann-Whitney, or chi(2) test was applied in inferential analysis, where necessary, to investigate the effects of sociodemographic factors on WTP. Prices on payment cards were expressed in Nigerian naira (NGN 150.00 approximately US $1.00), but study results were expressed in US dollars. A total of 359

  3. Calculated magnetocrystalline anisotropy of existing and hypothetical MCo5 compounds

    International Nuclear Information System (INIS)

    Opahle, Ingo; Richter, Manuel; Kuz'min, Michael D.; Nitzsche, Ulrike; Koepernik, Klaus; Schramm, Lutz

    2005-01-01

    The magnetic properties, lattice parameters and formation enthalpies of existing and hypothetical MCo 5 compounds (M=Y, La, Th, Mg, Ca and Sr) are calculated within the framework of density functional theory. In these compounds the magnetocrystalline anisotropy energy is dominated by itinerant Co 3d contributions. Band energy calculations suggest that-within in a rigid band picture-anisotropy energies of comparable size to those of hard magnetic materials containing rare earths could be obtained by hole doping of YCo 5 , e.g. by the substitution of Ca or Mg for Y. This idea is confirmed by the presented total energy calculations. However, the calculated enthalpies of formation suggest that CaCo 5 and MgCo 5 could only be prepared by non-equilibrium methods

  4. Adaptive major histocompatibility complex (MHC) and neutral genetic variation in two native Baltic Sea fishes (perch Perca fluviatilis and zander Sander lucioperca) with comparisons to an introduced and disease susceptible population in Australia (P. fluviatilis): assessing the risk of disease epidemics.

    Science.gov (United States)

    Faulks, L K; Östman, Ö

    2016-04-01

    This study assessed the major histocompatibility complex (MHC) and neutral genetic variation and structure in two percid species, perch Perca fluviatilis and zander Sander lucioperca, in a unique brackish ecosystem, the Baltic Sea. In addition, to assess the importance of MHC diversity to disease susceptibility in these populations, comparisons were made to an introduced, disease susceptible, P. fluviatilis population in Australia. Eighty-three MHC class II B exon 2 variants were amplified: 71 variants from 92 P. fluviatilis samples, and 12 variants from 82 S. lucioperca samples. Microsatellite and MHC data revealed strong spatial genetic structure in S. lucioperca, but not P. fluviatilis, across the Baltic Sea. Both microsatellite and MHC data showed higher levels of genetic diversity in P. fluviatilis from the Baltic Sea compared to Australia, which may have facilitated the spread of an endemic virus, EHNV in the Australian population. The relatively high levels of genetic variation in the Baltic Sea populations, together with spatial genetic structure, however, suggest that there currently seems to be little risk of disease epidemics in this system. To ensure this remains the case in the face of ongoing environmental changes, fisheries and habitat disturbance, the conservation of local-scale genetic variation is recommended. © 2016 The Fisheries Society of the British Isles.

  5. Predicting St. Louis encephalitis virus epidemics: lessons from recent, and not so recent, outbreaks.

    Science.gov (United States)

    Day, J F

    2001-01-01

    St. Louis encephalitis virus was first identified as the cause of human disease in North America after a large urban epidemic in St. Louis, Missouri, during the summer of 1933. Since then, numerous outbreaks of St. Louis encephalitis have occurred throughout the continent. In south Florida, a 1990 epidemic lasted from August 1990 through January 1991 and resulted in 226 clinical cases and 11 deaths in 28 counties. This epidemic severely disrupted normal activities throughout the southern half of the state for 5 months and adversely impacted tourism in the affected region. The accurate forecasting of mosquito-borne arboviral epidemics will help minimize their impact on urban and rural population centers. Epidemic predictability would help focus control efforts and public education about epidemic risks, transmission patterns, and elements of personal protection that reduce the probability of arboviral infection. Research associated with arboviral outbreaks has provided an understanding of the strengths and weaknesses associated with epidemic prediction. The purpose of this paper is to review lessons from past arboviral epidemics and determine how these observations might aid our ability to predict and respond to future outbreaks.

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

    Science.gov (United States)

    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.

  7. Multilingual event extraction for epidemic detection.

    Science.gov (United States)

    Lejeune, Gaël; Brixtel, Romain; Doucet, Antoine; Lucas, Nadine

    2015-10-01

    This paper presents a multilingual news surveillance system applied to tele-epidemiology. It has been shown that multilingual approaches improve timeliness in detection of epidemic events across the globe, eliminating the wait for local news to be translated into major languages. We present here a system to extract epidemic events in potentially any language, provided a Wikipedia seed for common disease names exists. The Daniel system presented herein relies on properties that are common to news writing (the journalistic genre), the most useful being repetition and saliency. Wikipedia is used to screen common disease names to be matched with repeated characters strings. Language variations, such as declensions, are handled by processing text at the character-level, rather than at the word level. This additionally makes it possible to handle various writing systems in a similar fashion. As no multilingual ground truth existed to evaluate the Daniel system, we built a multilingual corpus from the Web, and collected annotations from native speakers of Chinese, English, Greek, Polish and Russian, with no connection or interest in the Daniel system. This data set is available online freely, and can be used for the evaluation of other event extraction systems. Experiments for 5 languages out of 17 tested are detailed in this paper: Chinese, English, Greek, Polish and Russian. The Daniel system achieves an average F-measure of 82% in these 5 languages. It reaches 87% on BEcorpus, the state-of-the-art corpus in English, slightly below top-performing systems, which are tailored with numerous language-specific resources. The consistent performance of Daniel on multiple languages is an important contribution to the reactivity and the coverage of epidemiological event detection systems. Most event extraction systems rely on extensive resources that are language-specific. While their sophistication induces excellent results (over 90% precision and recall), it restricts their

  8. 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.

  9. 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.

  10. Hub nodes inhibit the outbreak of epidemic under voluntary vaccination

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haifeng; Wang Binghong [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)], E-mail: bhwang@ustc.edu.cn; Zhang Jie; Small, Michael [Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)], E-mail: ensmall@polyu.edu.hk; Zhou Changsong [Department of Physics, Centre for Nonlinear Studies, and Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems (Hong Kong), Hong Kong Baptist University, Kowloon Tong, Hong Kong (China)

    2010-02-15

    It is commonly believed that epidemic spreading on scale-free networks is difficult to control and that the disease can spread even with a low infection rate, lacking an epidemic threshold. In this paper, we study epidemic spreading on complex networks under the framework of game theory, in which a voluntary vaccination strategy is incorporated. In particular, individuals face the 'dilemma' of vaccination: they have to decide whether or not to vaccinate according to the trade-off between the risk and the side effects or cost of vaccination. Remarkably and quite excitingly, we find that disease outbreak can be more effectively inhibited on scale-free networks than on random networks. This is because the hub nodes of scale-free networks are more inclined to take self-vaccination after balancing the pros and cons. This result is encouraging as it indicates that real-world networks, which are often claimed to be scale free, can be favorably and easily controlled under voluntary vaccination. Our work provides a way of understanding how to prevent the outbreak of diseases under voluntary vaccination, and is expected to provide valuable information on effective disease control and appropriate decision-making.

  11. Planning horizon affects prophylactic decision-making and epidemic dynamics.

    Science.gov (United States)

    Nardin, Luis G; Miller, Craig R; Ridenhour, Benjamin J; Krone, Stephen M; Joyce, Paul; Baumgaertner, Bert O

    2016-01-01

    The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon-the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals' payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.

  12. Temporal prediction of epidemic patterns in community networks

    International Nuclear Information System (INIS)

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

    2013-01-01

    Most previous studies of epidemic dynamics on complex networks suppose that the disease will eventually stabilize at either a disease-free state or an endemic one. In reality, however, some epidemics always exhibit sporadic and recurrent behaviour in one region because of the invasion from an endemic population elsewhere. In this paper we address this issue and study a susceptible–infected–susceptible epidemiological model on a network consisting of two communities, where the disease is endemic in one community but alternates between outbreaks and extinctions in the other. We provide a detailed characterization of the temporal dynamics of epidemic patterns in the latter community. In particular, we investigate the time duration of both outbreak and extinction, and the time interval between two consecutive inter-community infections, as well as their frequency distributions. Based on the mean-field theory, we theoretically analyse these three timescales and their dependence on the average node degree of each community, the transmission parameters and the number of inter-community links, which are in good agreement with simulations, except when the probability of overlaps between successive outbreaks is too large. These findings aid us in better understanding the bursty nature of disease spreading in a local community, and thereby suggesting effective time-dependent control strategies. (paper)

  13. Hub nodes inhibit the outbreak of epidemic under voluntary vaccination

    International Nuclear Information System (INIS)

    Zhang Haifeng; Wang Binghong; Zhang Jie; Small, Michael; Zhou Changsong

    2010-01-01

    It is commonly believed that epidemic spreading on scale-free networks is difficult to control and that the disease can spread even with a low infection rate, lacking an epidemic threshold. In this paper, we study epidemic spreading on complex networks under the framework of game theory, in which a voluntary vaccination strategy is incorporated. In particular, individuals face the 'dilemma' of vaccination: they have to decide whether or not to vaccinate according to the trade-off between the risk and the side effects or cost of vaccination. Remarkably and quite excitingly, we find that disease outbreak can be more effectively inhibited on scale-free networks than on random networks. This is because the hub nodes of scale-free networks are more inclined to take self-vaccination after balancing the pros and cons. This result is encouraging as it indicates that real-world networks, which are often claimed to be scale free, can be favorably and easily controlled under voluntary vaccination. Our work provides a way of understanding how to prevent the outbreak of diseases under voluntary vaccination, and is expected to provide valuable information on effective disease control and appropriate decision-making.

  14. Rainfall mediations in the spreading of epidemic cholera

    Science.gov (United States)

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

    2013-10-01

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

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

    Science.gov (United States)

    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.

  16. Virulence evolution at the front line of spreading epidemics.

    Science.gov (United States)

    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.

  17. Effect of risk perception on epidemic spreading in temporal networks

    Science.gov (United States)

    Moinet, Antoine; Pastor-Satorras, Romualdo; Barrat, Alain

    2018-01-01

    Many progresses in the understanding of epidemic spreading models have been obtained thanks to numerous modeling efforts and analytical and numerical studies, considering host populations with very different structures and properties, including complex and temporal interaction networks. Moreover, a number of recent studies have started to go beyond the assumption of an absence of coupling between the spread of a disease and the structure of the contacts on which it unfolds. Models including awareness of the spread have been proposed, to mimic possible precautionary measures taken by individuals that decrease their risk of infection, but have mostly considered static networks. Here, we adapt such a framework to the more realistic case of temporal networks of interactions between individuals. We study the resulting model by analytical and numerical means on both simple models of temporal networks and empirical time-resolved contact data. Analytical results show that the epidemic threshold is not affected by the awareness but that the prevalence can be significantly decreased. Numerical studies on synthetic temporal networks highlight, however, the presence of very strong finite-size effects, resulting in a significant shift of the effective epidemic threshold in the presence of risk awareness. For empirical contact networks, the awareness mechanism leads as well to a shift in the effective threshold and to a strong reduction of the epidemic prevalence.

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

    Science.gov (United States)

    Greenhalgh, Susan

    2016-08-01

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

  19. A social contagious model of the obesity epidemic

    Science.gov (United States)

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

    2016-11-01

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

  20. Global Changes in Food Supply and the Obesity Epidemic

    DEFF Research Database (Denmark)

    Zobel, Emilie H.; Hansen, Tine W; Rossing, Peter

    2016-01-01

    power and available per capita food. Supermarkets and a growing fast-food industry have transformed our dietary pattern. Ultra-processed food rich on sugars and saturated fat is now the major source of energy in most countries. The shift in food supply is considered a major driver of the obesity......Purpose of Review We explore how a global shift in the food system caused by global economic growth, increase in available food per capita and in food processing is a driver of the obesity epidemic. Recent Findings Economic development in most areas of the world has resulted in increased purchasing...... epidemic and the increasing prevalence of accompanying complications, such as type 2 diabetes, cardiovascular disease and cancer. However, the global shift might also have direct effects on the increase in type 2 diabetes, cardiovascular disease and cancer, independently of overweight and obesity. Summary...

  1. 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...

  2. 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....

  3. Radiological Consequence Analyses Following a Hypothetical Severe Accident in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Juyub; Kim, Juyoul [FNC Technology Co., Yongin (Korea, Republic of)

    2016-10-15

    In order to reflect the lessons learned from the Fukushima Daiichi nuclear power plant accident, a simulator which is named NANAS (Northeast Asia Nuclear Accident Simulator) for overseas nuclear accident has been developed. It is composed of three modules: source-term estimation, atmospheric dispersion prediction and dose assessment. For the source-term estimation module, the representative reactor types were selected as CPR1000, BWR5 and BWR6 for China, Japan and Taiwan, respectively. Considering the design characteristics of each reactor type, the source-term estimation module simulates the transient of design basis accident and severe accident. The atmospheric dispersion prediction module analyzes the transport and dispersion of radioactive materials and prints out the air and ground concentration. Using the concentration result, the dose assessment module calculates effective dose and thyroid dose in the Korean Peninsula region. In this study, a hypothetical severe accident in Japan was simulated to demonstrate the function of NANAS. As a result, the radiological consequence to Korea was estimated from the accident. PC-based nuclear accident simulator, NANAS, has been developed. NANAS contains three modules: source-term estimation, atmospheric dispersion prediction and dose assessment. The source-term estimation module simulates a nuclear accident for the representative reactor types in China, Japan and Taiwan. Since the maximum calculation speed is 16 times than real time, it is possible to estimate the source-term release swiftly in case of the emergency. The atmospheric dispersion prediction module analyzes the transport and dispersion of radioactive materials in wide range including the Northeast Asia. Final results of the dose assessment module are a map projection and time chart of effective dose and thyroid dose. A hypothetical accident in Japan was simulated by NANAS. The radioactive materials were released during the first 24 hours and the source

  4. Modeling a Hypothetical 170Tm Source for Brachytherapy Applications

    International Nuclear Information System (INIS)

    Enger, Shirin A.; D'Amours, Michel; Beaulieu, Luc

    2011-01-01

    Purpose: To perform absorbed dose calculations based on Monte Carlo simulations for a hypothetical 170 Tm source and to investigate the influence of encapsulating material on the energy spectrum of the emitted electrons and photons. Methods: GEANT4 Monte Carlo code version 9.2 patch 2 was used to simulate the decay process of 170 Tm and to calculate the absorbed dose distribution using the GEANT4 Penelope physics models. A hypothetical 170 Tm source based on the Flexisource brachytherapy design with the active core set as a pure thulium cylinder (length 3.5 mm and diameter 0.6 mm) and different cylindrical source encapsulations (length 5 mm and thickness 0.125 mm) constructed of titanium, stainless-steel, gold, or platinum were simulated. The radial dose function for the line source approximation was calculated following the TG-43U1 formalism for the stainless-steel encapsulation. Results: For the titanium and stainless-steel encapsulation, 94% of the total bremsstrahlung is produced inside the core, 4.8 and 5.5% in titanium and stainless-steel capsules, respectively, and less than 1% in water. For the gold capsule, 85% is produced inside the core, 14.2% inside the gold capsule, and a negligible amount ( 170 Tm source is primarily a bremsstrahlung source, with the majority of bremsstrahlung photons being generated in the source core and experiencing little attenuation in the source encapsulation. Electrons are efficiently absorbed by the gold and platinum encapsulations. However, for the stainless-steel capsule (or other lower Z encapsulations) electrons will escape. The dose from these electrons is dominant over the photon dose in the first few millimeter but is not taken into account by current standard treatment planning systems. The total energy spectrum of photons emerging from the source depends on the encapsulation composition and results in mean photon energies well above 100 keV. This is higher than the main gamma-ray energy peak at 84 keV. Based on our

  5. Current Zika virus epidemiology and recent epidemics.

    Science.gov (United States)

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

    2014-07-01

    The Zika virus (ZIKV) is a mosquito-borne flavivirus (Aedes), similar to other arboviruses, first identified in Uganda in 1947. Few human cases were reported until 2007, when a Zika outbreak occurred in Yap, Micronesia, even though ZIKV activity had been reported in Africa and in Asia through virological surveillance and entomological studies. French Polynesia has recorded a large outbreak since October 2013. A great number of cases and some with neurological and autoimmune complications have been reported in a context of concurrent circulation of dengue viruses. The clinical presentation is a "dengue-like syndrome". Until the epidemic in French Polynesia, no severe ZIKV disease had been described so far. The diagnosis is confirmed by viral genome detection by genomic amplification (RT- PCR) and viral isolation. These two large outbreaks occurred in a previously unaffected area in less than a decade. They should raise awareness as to the potential for ZIKV to spread especially since this emergent disease is not well known and that some questions remain on potential reservoirs and transmission modes as well as on clinical presentations and complications. ZIKV has the potential to spread to new areas where the Aedes mosquito vector is present and could be a risk for Southern Europe. Strategies for the prevention and control of ZIKV disease should include the use of insect repellent and mosquito vector eradication. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  6. 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.

  7. Epidemic spreading and global stability of an SIS model with an infective vector on complex networks

    Science.gov (United States)

    Kang, Huiyan; Fu, Xinchu

    2015-10-01

    In this paper, we present a new SIS model with delay on scale-free networks. The model is suitable to describe some epidemics which are not only transmitted by a vector but also spread between individuals by direct contacts. In view of the biological relevance and real spreading process, we introduce a delay to denote average incubation period of disease in a vector. By mathematical analysis, we obtain the epidemic threshold and prove the global stability of equilibria. The simulation shows the delay will effect the epidemic spreading. Finally, we investigate and compare two major immunization strategies, uniform immunization and targeted immunization.

  8. 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.

  9. Ebola Policies That Hinder Epidemic Response by Limiting Scientific Discourse

    OpenAIRE

    Asgary, Ramin; Pavlin, Julie A.; Ripp, Jonathan A.; Reithinger, Richard; Polyak, Christina S.

    2015-01-01

    There is an unprecedented epidemic of Ebola virus disease (EVD) in west Africa. There has been a strong response from dedicated health professionals. However, there have also been irrational and fear-based responses that have contributed to misallocation of resources, stigma, and deincentivizing volunteers to combat Ebola at its source. Recently, the State of Louisiana Department of Health and Hospitals issued a ban on those coming from affected countries wishing to attend the annual meetings...

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

    Science.gov (United States)

    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.

  11. Climate drives the meningitis epidemics onset in west Africa.

    Directory of Open Access Journals (Sweden)

    Benjamin Sultan

    2005-01-01

    Full Text Available BACKGROUND: Every year West African countries within the Sahelo-Sudanian band are afflicted with major meningococcal meningitis (MCM disease outbreaks, which affect up to 200,000 people, mainly young children, in one of the world's poorest regions. The timing of the epidemic year, which starts in February and ends in late May, and the spatial distribution of disease cases throughout the "Meningitis Belt" strongly indicate a close linkage between the life cycle of the causative agent of MCM and climate variability. However, mechanisms responsible for the observed patterns are still not clearly identified. METHODS AND FINDINGS: By comparing the information on cases and deaths of MCM from World Health Organization weekly reports with atmospheric datasets, we quantified the relationship between the seasonal occurrence of MCM in Mali, a West African country, and large-scale atmospheric circulation. Regional atmospheric indexes based on surface wind speed show a clear link between population dynamics of the disease and climate: the onset of epidemics and the winter maximum defined by the atmospheric index share the same mean week (sixth week of the year; standard deviation, 2 wk and are highly correlated. CONCLUSIONS: This study is the first that provides a clear, quantitative demonstration of the connections that exist between MCM epidemics and regional climate variability in Africa. Moreover, this statistically robust explanation of the MCM dynamics enables the development of an Early Warning Index for meningitis epidemic onset in West Africa. The development of such an index will undoubtedly help nationwide and international public health institutions and policy makers to better control MCM disease within the so-called westward-eastward pan-African Meningitis Belt.

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

    Science.gov (United States)

    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.

  13. Cooperative SIS epidemics can lead to abrupt outbreaks

    Science.gov (United States)

    Ghanbarnejad, Fakhteh; Chen, Li; Cai, Weiran; Grassberger, Peter

    2015-03-01

    In this paper, we study spreading of two cooperative SIS epidemics in mean field approximations and also within an agent based framework. Therefore we investigate dynamics on different topologies like Erdos-Renyi networks and regular lattices. We show that cooperativity of two diseases can lead to strongly first order outbreaks, while the dynamics still might present some scaling laws typical for second order phase transitions. We argue how topological network features might be related to this interesting hybrid behaviors.

  14. Epidemics scenarios in the "Romantic network".

    Directory of Open Access Journals (Sweden)

    Alexsandro M Carvalho

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

  15. Information content of household-stratified epidemics

    Directory of Open Access Journals (Sweden)

    T.M. Kinyanjui

    2016-09-01

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

  16. 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.

  17. Modeling and Analysis of Epidemic Diffusion within Small-World Network

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2012-01-01

    Full Text Available To depict the rule of epidemic diffusion, two different models, the Susceptible-Exposure-Infected-Recovered-Susceptible (SEIRS model and the Susceptible-Exposure-Infected-Quarantine-Recovered-Susceptible (SEIQRS model, are proposed and analyzed within small-world network in this paper. Firstly, the epidemic diffusion models are constructed with mean-filed theory, and condition for the occurrence of disease diffusion is explored. Then, the existence and global stability of the disease-free equilibrium and the endemic equilibrium for these two complex epidemic systems are proved by differential equations knowledge and Routh-Hurwiz theory. At last, a numerical example which includes key parameters analysis and critical topic discussion is presented to test how well the proposed two models may be applied in practice. These works may provide some guidelines for decision makers when coping with epidemic diffusion controlling problems.

  18. A hypothetical severe reactor accident in Sosnovyj Bor, Russia

    International Nuclear Information System (INIS)

    Lahtinen, J.; Toivonen, H.; Poellaenen, R.; Nordlund, G.

    1993-12-01

    Individual doses and short-term radiological consequences from a hypothetical severe accident at the Russian nuclear power plant in Sosnovyj Bor were estimated for two sites in Finland. The sites are Kotka, located 140 km from the plant, and Helsinki, 220 km from the plant. The release was assumed to start immediately after the shutdown of the reactor (a 1000 MW RBMK unit) which had been operating at nominal power level for a long time. An effective release height of 500 m was assumed. The prevailing meteorological conditions during the release were taken to present the situation typical of the area (effective wind speed 9 m/s, neutral dispersion conditions). The release fractions applied in the study were of the same order as in the Chernobyl accident, i.e. 100% for noble gases, 60% for iodines, 40% for cesium and 1-10% for other radiologically important nuclides. The release was assumed to last 24 hours. However, half of the nuclides were released during the first hour. No attention was paid to the actual sequence of events that could lead to such release characteristics and time behaviour. The concentration and dose calculations were performed with a modified version of the computer code OIVA developed in Finnish Centre for Radiation and Nuclear Safety. Inhalation dose and external doses from the release plume and from the deposited activity were calculated for adults only, and no sheltering was considered. (11 refs., 4 figs., 6 tabs.)

  19. Consequence evaluation of hypothetical reactor pressure vessel support failure

    International Nuclear Information System (INIS)

    Lu, S.C.; Holman, G.S.; Lambert, H.E.

    1991-01-01

    This paper describes a consequence evaluation to address safety concerns raised by the radiation embrittlement of the reactor pressure vessel (RPV) supports for the Trojan nuclear power plant. The study comprises a structural evaluation and an effects evaluation and assumes that all four reactor vessel supports have completely lost the load carrying capability. The structural evaluation concludes that the Trojan reactor coolant loop (RCL) piping is capable of transferring loads to the steam generator (SG) supports and the reactor coolant pump (RCP) supports and that the SG supports and the RCP supports have sufficient design margins to accommodate additional loads transferred to them through the RCL piping. The effects evaluation, employing a systems analysis approach, investigates initiating events and the reliability of the engineered safeguard systems as the RPV is subject to movements caused by the RPV support failure. The evaluation identifies a number of areas for further investigation and concludes that a hypothetical failure of the Trojan RPV supports due to radiation embrittlement will not result in consequences of significant safety concerns. (author)

  20. Intersubassembly incoherencies and grouping techniques in LMFBR hypothetical overpower accident

    International Nuclear Information System (INIS)

    Wilburn, N.P.

    1977-10-01

    A detailed analysis was made of the FTR core using the 100-channel MELT-IIIA code. Results were studied for the transient overpower accident (where 0.5$/sec and 1$/sec ramps) and in which the Damage Parameter and the Failure Potential criteria were used. Using the information obtained from these series of runs, a new method of grouping the subassemblies into channels has been developed. Also, it was demonstrated that a 7-channel representation of the FTR core using this method does an adequate job of representing the behavior during a hypothetical disruptive transient overpower core accident. It has been shown that this new 7-channel grouping method does a better job than an earlier 20-channel grouping. It has also been demonstrated that the incoherency effects between subassemblies as shown during the 76-channel representation of the reactor can be adequately modeled by 7-channels, provided the 7-channels are selected according to the criteria stated in the report. The overall results of power and net reactivity were shown to be only slightly different in the two cases of the 7-channel and the 76-channel runs. Therefore, it can be concluded that any intersubassembly incoherencies can be modeled adequately by a small number of channels, provided the subassemblies making up these channels are selected according to the criteria stated

  1. Shock loading of reactor vessel following hypothetical core disruptive accident

    International Nuclear Information System (INIS)

    Srinivas, G.; Doshi, J.B.

    1990-01-01

    Hypothetical Core Disruptive Accident (HCDA) has been historically considered as the maximum credible accident in Fast Breeder Reactor systems. Environmental consequences of such an accident depends to a great extent on the ability of the reactor vessel to maintain integrity during the shock loading following an HCDA. In the present paper, a computational model of the reactor core and the surrounding coolant with a free surface is numerical technique. The equations for conservation of mass, momentum and energy along with an equation of state are considered in two dimensional cylindrical geometry. The reactor core at the end of HCDA is taken as a bubble of hot, vaporized fuel at high temperature and pressure, formed at the center of the reactor vessel and expanding against the surrounding liquid sodium coolant. The free surface of sodium at the top of the vessel and the movement of the core bubble-liquid coolant interface are tracked by Marker and Cell (MAC) procedure. The results are obtained for the transient pressure at the vessel wall and also for the loading on the roof plug by the impact of the slug of liquid sodium. The computer code developed is validated against a benchmark experiment chosen to be ISPRA experiment reported in literature. The computer code is next applied to predict the loading on the Indian Prototype Fast Breeder Reactor (PFBR) being developed at Kalpakkam

  2. The Diabetes Epidemic in Korea

    Directory of Open Access Journals (Sweden)

    Junghyun Noh

    2016-09-01

    Full Text Available Diabetes is one of the foremost public health issues worldwide that can lead to complications in many organ systems, and has become a significant cause of morbidity and mortality in Korea. According to data from the National Health Insurance Service (NHIS, about 2.7 million Koreans (8.0% aged 30 years or older had type 2 diabetes mellitus (T2DM in 2013. The prevalence of T2DM increased with age and rose from 5.6% in 2006 to 8.0% in 2013. Using data based on The Health Screening Service of the NHIS, 25% of Korean adults were reported to have prediabetes in 2013. The prevalence of an impaired fasting glucose tended to increase over time from 21.5% in 2006 to 25.0% in 2013. Even though nationwide health screening has been regularly conducted as a public service, the proportion of undiagnosed cases of diabetes was still reported to be on the higher side in the latest study. Based on the results of these epidemic studies, further actions will be needed to effectively implement lifestyle changes on a social level and increase measures for the early detection of diabetes to stem the tide of the epidemic.

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

    Science.gov (United States)

    Yang, Hui; Tang, Ming; Gross, Thilo

    2015-08-01

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that network heterogeneity, i.e. a broad degree distribution, can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. However, it has been pointed out that networks in which the properties of nodes are intrinsically heterogeneous can be very resilient to disease spreading. Heterogeneity in structure can enhance or diminish the resilience of networks with heterogeneous nodes, depending on the correlations between the topological and intrinsic properties. Here, we consider a plausible scenario where people have intrinsic differences in susceptibility and adapt their social network structure to the presence of the disease. We show that the resilience of networks with heterogeneous connectivity can surpass those of networks with homogeneous connectivity. For epidemiology, this implies that network heterogeneity should not be studied in isolation, it is instead the heterogeneity of infection risk that determines the likelihood of outbreaks.

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

    Science.gov (United States)

    Yang, Hui; Tang, Ming; Gross, Thilo

    2015-08-21

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that network heterogeneity, i.e. a broad degree distribution, can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. However, it has been pointed out that networks in which the properties of nodes are intrinsically heterogeneous can be very resilient to disease spreading. Heterogeneity in structure can enhance or diminish the resilience of networks with heterogeneous nodes, depending on the correlations between the topological and intrinsic properties. Here, we consider a plausible scenario where people have intrinsic differences in susceptibility and adapt their social network structure to the presence of the disease. We show that the resilience of networks with heterogeneous connectivity can surpass those of networks with homogeneous connectivity. For epidemiology, this implies that network heterogeneity should not be studied in isolation, it is instead the heterogeneity of infection risk that determines the likelihood of outbreaks.

  5. Epidemic spreading and immunization strategy in multiplex networks

    Science.gov (United States)

    Alvarez Zuzek, Lucila G.; Buono, Camila; Braunstein, Lidia A.

    2015-09-01

    A more connected world has brought major consequences such as facilitate the spread of diseases all over the world to quickly become epidemics, reason why researchers are concentrated in modeling the propagation of epidemics and outbreaks in multilayer networks. In this networks all nodes interact in different layers with different type of links. However, in many scenarios such as in the society, a multiplex network framework is not completely suitable since not all individuals participate in all layers. In this paper, we use a partially overlapped, multiplex network where only a fraction of the individuals are shared by the layers. We develop a mitigation strategy for stopping a disease propagation, considering the Susceptible-Infected- Recover model, in a system consisted by two layers. We consider a random immunization in one of the layers and study the effect of the overlapping fraction in both, the propagation of the disease and the immunization strategy. Using branching theory, we study this scenario theoretically and via simulations and find a lower epidemic threshold than in the case without strategy.

  6. [Modern methods application of genotyping of infectious diseases pathogens in the context of operational work of specialized anti-epidemic team during the XXII Olympic Winter Games and XI Paralympic Winter Games].

    Science.gov (United States)

    Kuzkin, B P; Kulichenko, A N; Volynkina, A S; Efremenko, D V; Kuznetsova, I V; Kotenev, E S; Lyamkin, G I; Kartsev, N N; Klindukhov, V P

    2015-01-01

    This paper considers the experience of genotyping and sequencing technologies in laboratories of specialized anti-epidemic team (SAET) during the XXII Olympic Winter Games and XI Paralympic Winter Games of 2014 in Sochi. The work carried out during the pre-Olympic period on performance of readiness by SAET for these studies is analyzed. The results of genotyping strains of pathogens during the Olympic Games are presented. A conclusion about the effectiveness of the use of molecular genetic techniques in terms of SAET is made.

  7. Predicting epidemic outbreak from individual features of the spreaders

    International Nuclear Information System (INIS)

    Da Silva, Renato Aparecido Pimentel; Viana, Matheus Palhares; Da Fontoura Costa, Luciano

    2012-01-01

    Knowing which individuals can be more efficient in spreading a pathogen throughout a determinate environment is a fundamental question in disease control. Indeed, over recent years the spread of epidemic diseases and its relationship with the topology of the involved system have been a recurrent topic in complex network theory, taking into account both network models and real-world data. In this paper we explore possible correlations between the heterogeneous spread of an epidemic disease governed by the susceptible–infected–recovered (SIR) model, and several attributes of the originating vertices, considering Erdös–Rényi (ER), Barabási–Albert (BA) and random geometric graphs (RGG), as well as a real case study, the US air transportation network, which comprises the 500 busiest airports in the US along with inter-connections. Initially, the heterogeneity of the spreading is achieved by considering the RGG networks, in which we analytically derive an expression for the distribution of the spreading rates among the established contacts, by assuming that such rates decay exponentially with the distance that separates the individuals. Such a distribution is also considered for the ER and BA models, where we observe topological effects on the correlations. In the case of the airport network, the spreading rates are empirically defined, assumed to be directly proportional to the seat availability. Among both the theoretical and real networks considered, we observe a high correlation between the total epidemic prevalence and the degree, as well as the strength and the accessibility of the epidemic sources. For attributes such as the betweenness centrality and the k-shell index, however, the correlation depends on the topology considered. (paper)

  8. Effects of contact network structure on epidemic transmission trees: implications for data required to estimate network structure.

    Science.gov (United States)

    Carnegie, Nicole Bohme

    2018-01-30

    Understanding the dynamics of disease spread is key to developing effective interventions to control or prevent an epidemic. The structure of the network of contacts over which the disease spreads has been shown to have a strong influence on the outcome of the epidemic, but an open question remains as to whether it is possible to estimate contact network features from data collected in an epidemic. The approach taken in this paper is to examine the distributions of epidemic outcomes arising from epidemics on networks with particular structural features to assess whether that structure could be measured from epidemic data and what other constraints might be needed to make the problem identifiable. To this end, we vary the network size, mean degree, and transmissibility of the pathogen, as well as the network feature of interest: clustering, degree assortativity, or attribute-based preferential mixing. We record several standard measures of the size and spread of the epidemic, as well as measures that describe the shape of the transmission tree in order to ascertain whether there are detectable signals in the final data from the outbreak. The results suggest that there is potential to estimate contact network features from transmission trees or pure epidemic data, particularly for diseases with high transmissibility or for which the relevant contact network is of low mean degree. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  9. 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...

  10. Malaria epidemic and drug resistance, Djibouti.

    Science.gov (United States)

    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.

  11. 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

  12. Simulation of Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins

    Science.gov (United States)

    Carleton, Glen B.

    2010-01-01

    Groundwater mounding occurs beneath stormwater management structures designed to infiltrate stormwater runoff. Concentrating recharge in a small area can cause groundwater mounding that affects the basements of nearby homes and other structures. Methods for quantitatively predicting the height and extent of groundwater mounding beneath and near stormwater Finite-difference groundwater-flow simulations of infiltration from hypothetical stormwater infiltration structures (which are typically constructed as basins or dry wells) were done for 10-acre and 1-acre developments. Aquifer and stormwater-runoff characteristics in the model were changed to determine which factors are most likely to have the greatest effect on simulating the maximum height and maximum extent of groundwater mounding. Aquifer characteristics that were changed include soil permeability, aquifer thickness, and specific yield. Stormwater-runoff variables that were changed include magnitude of design storm, percentage of impervious area, infiltration-structure depth (maximum depth of standing water), and infiltration-basin shape. Values used for all variables are representative of typical physical conditions and stormwater management designs in New Jersey but do not include all possible values. Results are considered to be a representative, but not all-inclusive, subset of likely results. Maximum heights of simulated groundwater mounds beneath stormwater infiltration structures are the most sensitive to (show the greatest change with changes to) soil permeability. The maximum height of the groundwater mound is higher when values of soil permeability, aquifer thickness, or specific yield are decreased or when basin depth is increased or the basin shape is square (and values of other variables are held constant). Changing soil permeability, aquifer thickness, specific yield, infiltration-structure depth, or infiltration-structure shape does not change the volume of water infiltrated, it changes the

  13. A hypothetical study of populations under constant mortality and fertility.

    Science.gov (United States)

    Gupta, R B

    1976-03-01

    28 countries with different characteristics have been selected in order to observe the amount of time it takes for these different countries to reach stable age distributions. The individual populations by sex and age were projected for 150 years in 5-year intervals with the present constant mortality and fertility schedules by component method. Observations have been made by considering the following characteristics of population when it has acquired stability: age distribution; the rate of growth, birthrate, and mortality rate; the population change; the intrinsic rate of growth, birthrate and mortality rate; and approximate time taken to stabilize the population. The initial age distribution has a significant part in the amount of time it takes for a population to acquire stability, and its intrinsic rate of growth is mostly dependent upon the existing age distribution of that population. The time taken for a country's population to become stable depends upon the age distribution, fertility and mortality schedules at the beginning. It has been observed that countries having a higher intrinsic rate of growth take comparatively less time in acquiring stability than the countries having a lower intrinsic rate of growth. The mortality and fertility schedules of a country is another important phenomenon. The populations of the different countries at the point of stability were growing according to their rates of growth. No specific trend of population growth could be found among the groups of countries. Time taken for stabilizing the population is completely based upon age distributions, fertility and mortality schedules a particular country was having at the beginning. The range of time taken for different countries to acquire stability generally ranged from 100 to 135 years. Among the different countries the relationship for the time it takes to acquire stability has not been established. This is a hypothetical approach in order to obtain some idea as to how a

  14. Studies of hypothetical and fundamental decay properties of positronium

    International Nuclear Information System (INIS)

    Wahl, W.

    1985-05-01

    For the solution of the CP problem in the standard theory of the strong interaction the existence of a neutral pseudoscalar boson was postulated which couples to quarks and leptons. If the mass of this so-called axion is smaller than two electron masses for orthopositronium 'o-Ps' the decay into one photon and axion is expected in concurrence to the standard decay into three photons. The detection of a monoenergetic photon would be an indication for this decay channel because the axion would only very weakly interact with matter. In the spectrum no lineshape of a monoenergetic photon is observed. From this results in dependence on the mass of a hypothetical particle and with a confidence limit of 90% for the branching ratio of o-Ps an upper limit which is in the range between 320 keV and 950 keV less than 10 -7 . Applied to the axion model an upper limit for the mass of the standard axion of 250 keV results. For the study of the fundamental decay properties of positronium the lifetime of o-Ps and the 3γ energy distribution of the decay quanta were measured. Furthermore the rare 4γ decay of para-positronium 'p-Ps' was searched for. The measured lifetime of o-Ps τ=141.2±1.2ns agrees well with the theoretical value. Calculations on the 3γ energy distribution are confirmed. For the 4γ decay of p-Ps predicted by QED with a branching ratio of ≅ 1.5x10 -6 an upper limit of 2x10 -5 results. (orig./HSI) [de

  15. Vulnerability Analysis of Physical Protection System at Hypothetical Facility

    International Nuclear Information System (INIS)

    Jung, Won Moog; Lee, Ho Jin; Yu, Dong Han; Min, Gyung Sik

    2006-01-01

    Since the 9/11 event in the U.S.A, International terror possibilities has been increasing for nuclear facilities including nuclear power plants(NPPs). It is necessary to evaluate the performance of an existing physical protection system(PPS) at nuclear facilities based on such malevolent acts. A PPS is a complex configuration of detection, delay, and response elements. Detection, delay, and response elements are all important to the analysis and evaluation of a PPS and its effectiveness. Methods are available to analyze a PPS and evaluate its effectiveness. Sandia National Laboratory(SNL) in the U.S.A was developed a System Analysis of Vulnerability to Intrusion (SAVI) computer code for evaluating the effectiveness of PPS against outsider threats. This study presents the vulnerability analysis of the PPS at hypothetical facility using SAVI code that the basic input parameters are from PPS of Hanaro Research Reactor at Korea Atomic Energy Research Institution. It is understand that PPS of research reactor and critical assemblies are deficient that that of NPP and nuclear materials of RRCAS are compact to transport For analysis, first, the site-specific Adversary Sequence Diagrams(ASDs) of the PPS is constructed. It helps to understand the functions of the existing PPS composed of physical areas and Protection Elements(PEs). Then, the most vulnerable path of an ASD as a measure of effectiveness is determined. The results in the analysis can used to suggest the possible PPS upgrades to the most vulnerable paths for the system like research reactor

  16. Recent results on the spatiotemporal modelling and comparative analysis of Black Death and bubonic plague epidemics

    Science.gov (United States)

    Christakos, G.; Olea, R.A.; Yu, H.-L.

    2007-01-01

    Background: This work demonstrates the importance of spatiotemporal stochastic modelling in constructing maps of major epidemics from fragmentary information, assessing population impacts, searching for possible etiologies, and performing comparative analysis of epidemics. Methods: Based on the theory previously published by the authors and incorporating new knowledge bases, informative maps of the composite space-time distributions were generated for important characteristics of two major epidemics: Black Death (14th century Western Europe) and bubonic plague (19th-20th century Indian subcontinent). Results: The comparative spatiotemporal analysis of the epidemics led to a number of interesting findings: (1) the two epidemics exhibited certain differences in their spatiotemporal characteristics (correlation structures, trends, occurrence patterns and propagation speeds) that need to be explained by means of an interdisciplinary effort; (2) geographical epidemic indicators confirmed in a rigorous quantitative manner the partial findings of isolated reports and time series that Black Death mortality was two orders of magnitude higher than that of bubonic plague; (3) modern bubonic plague is a rural disease hitting harder the small villages in the countryside whereas Black Death was a devastating epidemic that indiscriminately attacked large urban centres and the countryside, and while the epidemic in India lasted uninterruptedly for five decades, in Western Europe it lasted three and a half years; (4) the epidemics had reverse areal extension features in response to annual seasonal variations. Temperature increase at the end of winter led to an expansion of infected geographical area for Black Death and a reduction for bubonic plague, reaching a climax at the end of spring when the infected area in Western Europe was always larger than in India. Conversely, without exception, the infected area during winter was larger for the Indian bubonic plague; (5) during the

  17. 47 CFR 69.608 - Carrier Common Line hypothetical net balance.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Carrier Common Line hypothetical net balance. 69.608 Section 69.608 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER... net balance. The hypothetical net balance shall be equal to a Carrier Common Line revenue requirement...

  18. Using respondent uncertainty to mitigate hypothetical bias in a stated choice experiment

    Science.gov (United States)

    Richard C. Ready; Patricia A. Champ; Jennifer L. Lawton

    2010-01-01

    In a choice experiment study, willingness to pay for a public good estimated from hypothetical choices was three times as large as willingness to pay estimated from choices requiring actual payment. This hypothetical bias was related to the stated level of certainty of respondents. We develop protocols to measure respondent certainty in the context of a choice...

  19. Can a Repeated Opt-Out Reminder remove hypothetical bias in discrete choice experiments?

    DEFF Research Database (Denmark)

    Alemu, Mohammed Hussen; Olsen, Søren Bøye

    hypothetical bias in stated DCE. The data originates from a field experiment concerning consumer preferences for a novel food product made from cricket flour. Utilizing a between-subject design with three treatments, we find significantly higher marginal willingness to pay values in hypothetical than...

  20. Adolescents' explicit and implicit evaluations of hypothetical and actual peers with different bullying participant roles.

    Science.gov (United States)

    Pouwels, J Loes; Lansu, Tessa A M; Cillessen, Antonius H N

    2017-07-01

    This study examined how adolescents evaluate bullying at three levels of specificity: (a) the general concept of bullying, (b) hypothetical peers in different bullying participant roles, and (c) actual peers in different bullying participant roles. Participants were 163 predominantly ethnic majority adolescents in The Netherlands (58% girls; M age =16.34years, SD=0.79). For the hypothetical peers, we examined adolescents' explicit evaluations as well as their implicit evaluations. Adolescents evaluated the general concept of bullying negatively. Adolescents' explicit evaluations of hypothetical and actual peers in the bullying roles depended on their own role, but adolescents' implicit evaluations of hypothetical peers did not. Adolescents' explicit evaluations of hypothetical peers and actual peers were different. Hypothetical bullies were evaluated negatively by all classmates, whereas hypothetical victims were evaluated relatively positively compared with the other roles. However, when adolescents evaluated their actual classmates, the differences between bullies and the other roles were smaller, whereas victims were evaluated the most negatively of all roles. Further research should take into account that adolescents' evaluations of hypothetical peers differ from their evaluations of actual peers. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Explaining the discrepancy between intentions and actions: the case of hypothetical bias in contingent valuation

    Science.gov (United States)

    Icek Ajzen; Thomas C. Brown; Franklin Carvajal

    2004-01-01

    An experiment was designed to account for intention-behavior discrepancies by applying the theory of planned behavior to contingent valuation. College students (N = 160) voted in hypothetical and real payment referenda to contribute $8 to a scholarship fund. Overestimates of willingness to pay in the hypothetical referendum could not be attributed to moderately...

  2. Combining aptamers and in silico interaction studies to decipher the function of hypothetical proteins

    DEFF Research Database (Denmark)

    Suravajhala, Prashanth; Burri, Harsha Vardhan Reddy; Heiskanen, Arto

    2014-01-01

    We present the potential role of aptamers in elucidating the function of hypothetical proteins, as well as the possibilities provided by bioinformatics for establishing a benchmark for aptamer-protein prediction methods. With these future perspectives, the role of hypothetical proteins as target ...... molecules for diagnostics and therapies could prove to be very useful in development of medical technology....

  3. Suppressing epidemics with a limited amount of immunization units.

    Science.gov (United States)

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

    2011-12-01

    The way diseases spread through schools, epidemics through countries, and viruses through the internet is crucial in determining their risk. Although each of these threats has its own characteristics, its underlying network determines the spreading. To restrain the spreading, a widely used approach is the fragmentation of these networks through immunization, so that epidemics cannot spread. Here we develop an immunization approach based on optimizing the susceptible size, which outperforms the best known strategy based on immunizing the highest-betweenness links or nodes. We find that the network's vulnerability can be significantly reduced, demonstrating this on three different real networks: the global flight network, a school friendship network, and the internet. In all cases, we find that not only is the average infection probability significantly suppressed, but also for the most relevant case of a small and limited number of immunization units the infection probability can be reduced by up to 55%.

  4. 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.

  5. 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.

  6. Thermal characterization of organic matter along a (hypothetical) coalification gradient

    Science.gov (United States)

    Cavallo, Ornella; Provenzano, Maria Rosaria; Zaccone, Claudio

    2017-04-01

    Geochemical transformations of organic carbon (C) in aquatic and terrestrial ecosystems are important starting points for genesis of peats, brown coals and other coal precursors. The humification process plays a key role in biogeochemical transformations of organic C and, as a result, in the first stages of coal precursors formation. Thermal analysis was used by Schnitzer and other scientists since 1950-1960s, in order to investigate the stability of several organic materials of industrial value including peat and coal. What soil scientists found was the general occurrence of two exothermic peaks (exotherm 1 and 2) due to decomposition and combustion reactions of organic compounds having different thermal stability and, consequently, different degree of humification. Thermogravimetric analysis (TG) was carried out on different samples reproducing a "hypothetical" coalification gradient as follows: peat (IHSS Pahokee peat standard), fulvic acid (FA), a peat humic acid (HA), leonardite (IHSS Gascoyne standard) and charcoal. An aliquot of about 20 mg of each sample was heated in a ceramic crucible from 50 to 850˚ C at 30˚ C min-1, at a gas flow rate of 30 mL min-1 using a PerkinElmer TGA4000 thermobalance. Samples were analysed both under nitrogen and under synthetic air. All analyses were carried out in triplicate and the average coefficient of variation was bio-transformation of organic materials. Finally, the temperature at which half of the exothermic mass loss has occurred (TG-T50) was also calculated. Preliminary results obtained from TG analysis under air showed that WL2/WL1 ratio was lower for the FA sample and higher for leonardite and charcoal, following the order FA

  7. Emergency measures following hypothetical actions against nuclear facilities in Italy

    International Nuclear Information System (INIS)

    Rogani, A.; Tabet, E.

    2003-01-01

    Full text: After the Chernobyl accident a national emergency plan of protective measures for radiological emergencies has been set up in Italy to cope with nuclear risks which require actions at national level. Since most of the Italian nuclear installations are, at present, not operational, the most relevant nuclear risk sources identified in the national emergency plan stem from accidents in nuclear power plants near the Italian borders or aboard nuclearpropelled ships, or events related to the fall of nuclear-powered satellites and transportation of radioactive materials. The plan identifies a reference scenario for nation-wide emergency interventions and the proper structures to be involved in the radiological emergency. However, risks related to nuclear terrorism are not taken into account in the plan, whereas nuclear plants as well as nuclear materials and sources (in use in medical, scientific and industrial applications) are known to represent potential targets for hostile acts, potentially giving rise to harmful radioactive releases into the atmosphere. Along with four nuclear power plants, now undergoing a decommissioning procedure, several other nuclear facilities, such as provisional radioactive waste deposits or research centers, are present in Italy. Unfortunately not all of the radioactive waste inventory is conditioned in such a way to make a spread of radioactive contamination, as a consequence of a hostile action, unlikely; moreover, spent fuel elements are still kept, in some cases, inside the plant spent fuel storage pool. In this paper the hypothetical radiological impact of deliberate actions against some reference nuclear installations will be evaluated, together with its amplications for an appropriate profiling of the emergency countermeasures which could be required. Especially the case of a terrorism act against a spent fuel storage pool is worked out in some detail, as this event appears to be one of those with the most severe

  8. Stochastic inequalities and applications to dynamics analysis of a novel SIVS epidemic model with jumps

    Directory of Open Access Journals (Sweden)

    Xiaona Leng

    2017-06-01

    Full Text Available Abstract This paper proposes a new nonlinear stochastic SIVS epidemic model with double epidemic hypothesis and Lévy jumps. The main purpose of this paper is to investigate the threshold dynamics of the stochastic SIVS epidemic model. By using the technique of a series of stochastic inequalities, we obtain sufficient conditions for the persistence in mean and extinction of the stochastic system and the threshold which governs the extinction and the spread of the epidemic diseases. Finally, this paper describes the results of numerical simulations investigating the dynamical effects of stochastic disturbance. Our results significantly improve and generalize the corresponding results in recent literatures. The developed theoretical methods and stochastic inequalities technique can be used to investigate the high-dimensional nonlinear stochastic differential systems.

  9. Beyond network structure: How heterogeneous susceptibility modulates the spread of epidemics.

    Science.gov (United States)

    Smilkov, Daniel; Hidalgo, Cesar A; Kocarev, Ljupco

    2014-04-25

    The compartmental models used to study epidemic spreading often assume the same susceptibility for all individuals, and are therefore, agnostic about the effects that differences in susceptibility can have on epidemic spreading. Here we show that-for the SIS model-differential susceptibility can make networks more vulnerable to the spread of diseases when the correlation between a node's degree and susceptibility are positive, and less vulnerable when this correlation is negative. Moreover, we show that networks become more likely to contain a pocket of infection when individuals are more likely to connect with others that have similar susceptibility (the network is segregated). These results show that the failure to include differential susceptibility to epidemic models can lead to a systematic over/under estimation of fundamental epidemic parameters when the structure of the networks is not independent from the susceptibility of the nodes or when there are correlations between the susceptibility of connected individuals.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. 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.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Ceccato Pietro

    2005-01-01

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

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

    Science.gov (United States)

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

    2005-01-01

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

  15. Fishing for lobsters indirectly increases epidemics in sea urchins

    Science.gov (United States)

    Lafferty, Kevin D.

    2004-01-01

    Two ecological paradigms, the trophic cascade and the host-density threshold in disease, interact in the kelp-forest ecosystem to structure the community. To investigate what happens when a trophic cascade pushes a host population over a host-threshold density, I analyzed a 20-year data set of kelp forest communities at 16 sites in the region of the Channel Islands National Park, California, USA. Historically, lobsters, and perhaps other predators, kept urchin populations at low levels and kelp forests developed a community-level trophic cascade. In geographic areas where the main predators on urchins were fished, urchin populations increased to the extent that they overgrazed algae and starvation eventually limited urchin-population growth. Despite the limitation of urchin population size by food availability, urchin densities, at times, well exceeded the host-density threshold for epidemics. An urchin-specific bacterial disease entered the region after 1992 and acted as a density-dependent mortality source. Dense populations were more likely to experience epidemics and suffer higher mortality. Disease did not reduce the urchin population at a site to the density that predators previously did. Therefore, disease did not fully replace predators in the trophic cascade. These results indicate how fishing top predators can indirectly favor disease transmission in prey populations.

  16. [Epidemic research in the south of Fujian Province in modern times from the viewpoints of overseas communication].

    Science.gov (United States)

    Lin, Nan; Zhang, Sun-Biao; Zeng, Yi-Ling

    2012-09-01

    Under the particular geographical environment and social structure, different spatiality of epidemics was observed in the south of Fujian Province. Some important factors cannot be ignored in the study of local epidemics, such as its developed overseas communication, prosperous commercial activities between the East and the West and deep-rooted overseas emigration tradition. In modern times, public health ideas, therapies and prevention measures of west medicine were introduced, taking epidemic disease prevention as a turning point in this area, which promoted medical development of this area objectively, and valuable experience in disease prevention was accumulated.

  17. Human enterovirus 71 epidemics: what's next?

    Science.gov (United States)

    Yip, Cyril C. Y.; Lau, Susanna K. P.; Woo, Patrick C. Y.; Yuen, Kwok-Yung

    2013-01-01

    Human enterovirus 71 (EV71) epidemics have affected various countries in the past 40 years. EV71 commonly causes hand, foot and mouth disease (HFMD) in children, but can result in neurological and cardiorespiratory complications in severe cases. Genotypic changes of EV71 have been observed in different places over time, with the emergence of novel genotypes or subgenotypes giving rise to serious outbreaks. Since the late 1990s, intra- and inter-typic recombination events in EV71 have been increasingly reported in the Asia-Pacific region. In particular, ‘double-recombinant’ EV71 strains belonging to a novel genotype D have been predominant in mainland China and Hong Kong over the last decade, though co-circulating with a minority of other EV71 subgenotypes and coxsackie A viruses. Continuous surveillance and genome studies are important to detect potential novel mutants or recombinants in the near future. Rapid and sensitive molecular detection of EV71 is of paramount importance in anticipating and combating EV71 outbreaks. PMID:24119538

  18. Large-scale application of highly-diluted bacteria for Leptospirosis epidemic control.

    Science.gov (United States)

    Bracho, Gustavo; Varela, Enrique; Fernández, Rolando; Ordaz, Barbara; Marzoa, Natalia; Menéndez, Jorge; García, Luis; Gilling, Esperanza; Leyva, Richard; Rufín, Reynaldo; de la Torre, Rubén; Solis, Rosa L; Batista, Niurka; Borrero, Reinier; Campa, Concepción

    2010-07-01

    Leptospirosis is a zoonotic disease of major importance in the tropics where the incidence peaks in rainy seasons. Natural disasters represent a big challenge to Leptospirosis prevention strategies especially in endemic regions. Vaccination is an effective option but of reduced effectiveness in emergency situations. Homeoprophylactic interventions might help to control epidemics by using highly-diluted pathogens to induce protection in a short time scale. We report the results of a very large-scale homeoprophylaxis (HP) intervention against Leptospirosis in a dangerous epidemic situation in three provinces of Cuba in 2007. Forecast models were used to estimate possible trends of disease incidence. A homeoprophylactic formulation was prepared from dilutions of four circulating strains of Leptospirosis. This formulation was administered orally to 2.3 million persons at high risk in an epidemic in a region affected by natural disasters. The data from surveillance were used to measure the impact of the intervention by comparing with historical trends and non-intervention regions. After the homeoprophylactic intervention a significant decrease of the disease incidence was observed in the intervention regions. No such modifications were observed in non-intervention regions. In the intervention region the incidence of Leptospirosis fell below the historic median. This observation was independent of rainfall. The homeoprophylactic approach was associated with a large reduction of disease incidence and control of the epidemic. The results suggest the use of HP as a feasible tool for epidemic control, further research is warranted. 2010 Elsevier Ltd. All rights reserved.

  19. The psychiatric epidemic in the American workplace.

    Science.gov (United States)

    Brodsky, C M

    1988-01-01

    Several characteristics help distinguish MPI in the workplace from illness outbreaks due to physical causes: no laboratory or physical findings confirming an specific organic cause evidence of specific physical or psychological stressors victims are mostly women and those of lower socioeconomic status in the workplace hyperventilation-type symptoms are prominent apparent transmission by audiovisual cues rapid spread of the illness followed by rapid remission of symptoms, unless symptoms are fixed by physicians and litigation benign morbidity If a physical or chemical cause of the illness is not obvious and if episodes recur, the illness remains a mystery and the workplace becomes a breeding ground for anxiety, confusion, fear, and rumor. Economic pressures to resume normal operations are counteracted by fears that an environmental contaminant still exists. Once all physical explanations have been ruled out, investigators may turn to psychological explanations and focus on mass hysteria, but that explanation is primarily based on the absence of physical evidence rather than the presence of agreed-upon psychosocial conditions. Some reports suggest that the diagnosis of MPI is really an excuse for not conducting an adequate evaluation of low-level environmental contaminants. The disability in some workers is prolonged and points to non-work-related factors that may be contributing. Were it not for the unverifiable physical complaints and the workers' insistence that the symptoms are the result of physical disease and their concern about the complaints and their reactions to dismissal of their complaints, we would not consider these patients to have a mental disorder. These individuals are reinforced in their beliefs by some physicians and attorneys, and resultant litigation tends to fix their symptoms. In fact, a "conspiracy theory" evolves when there are enough convinced people--and enough people trying to dissuade them. Group phenomena reinforce their beliefs and

  20. BOLD responses in reward regions to hypothetical and imaginary monetary rewards.

    Science.gov (United States)

    Miyapuram, Krishna P; Tobler, Philippe N; Gregorios-Pippas, Lucy; Schultz, Wolfram

    2012-01-16

    Monetary rewards are uniquely human. Because money is easy to quantify and present visually, it is the reward of choice for most fMRI studies, even though it cannot be handed over to participants inside the scanner. A typical fMRI study requires hundreds of trials and thus small amounts of monetary rewards per trial (e.g. 5p) if all trials are to be treated equally. However, small payoffs can have detrimental effects on performance due to their limited buying power. Hypothetical monetary rewards can overcome the limitations of smaller monetary rewards but it is less well known whether predictors of hypothetical rewards activate reward regions. In two experiments, visual stimuli were associated with hypothetical monetary rewards. In Experiment 1, we used stimuli predicting either visually presented or imagined hypothetical monetary rewards, together with non-rewarding control pictures. Activations to reward predictive stimuli occurred in reward regions, namely the medial orbitofrontal cortex and midbrain. In Experiment 2, we parametrically varied the amount of visually presented hypothetical monetary reward keeping constant the amount of actually received reward. Graded activation in midbrain was observed to stimuli predicting increasing hypothetical rewards. The results demonstrate the efficacy of using hypothetical monetary rewards in fMRI studies. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Immunization strategy for epidemic spreading on multilayer networks

    Science.gov (United States)

    Buono, C.; Braunstein, L. A.

    2015-01-01

    In many real-world complex systems, individuals have many kinds of interactions among them, suggesting that it is necessary to consider a layered-structure framework to model systems such as social interactions. This structure can be captured by multilayer networks and can have major effects on the spreading of process that occurs over them, such as epidemics. In this letter we study a targeted immunization strategy for epidemic spreading over a multilayer network. We apply the strategy in one of the layers and study its effect in all layers of the network disregarding degree-degree correlation among layers. We found that the targeted strategy is not as efficient as in isolated networks, due to the fact that in order to stop the spreading of the disease it is necessary to immunize more than 80% of the individuals. However, the size of the epidemic is drastically reduced in the layer where the immunization strategy is applied compared to the case with no mitigation strategy. Thus, the immunization strategy has a major effect on the layer were it is applied, but does not efficiently protect the individuals of other layers.

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

    Science.gov (United States)

    Granell, Clara; Gómez, Sergio; Arenas, Alex

    2014-07-01

    Epidemiclike spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [C. Granell et al., Phys. Rev. Lett. 111, 128701 (2013).] presented an analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the spreading of information awareness to prevent infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease revealed the existence of a metacritical point at which the critical onset of the epidemics starts, depending on completion of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between the two competing processes for a wide spectrum of parameters representing the interaction between them. We also analyze the consequences of a massive broadcast of awareness (mass media) on the final outcome of the epidemic incidence. Importantly enough, the mass media make the metacritical point disappear. The results reveal that the main finding, i.e., existence of a metacritical point, is rooted in the competition principle and holds for a large set of scenarios.

  3. 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.

  4. 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.

  5. The prediction of epidemics through mathematical modeling.

    Science.gov (United States)

    Schaus, Catherine

    2014-01-01

    Mathematical models may be resorted to in an endeavor to predict the development of epidemics. The SIR model is one of the applications. Still too approximate, the use of statistics awaits more data in order to come closer to reality.

  6. 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.

  7. 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.

  8. 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

  9. Hypothetical atopic dermatitis-myeloproliferative neoplasm (AD-MPN syndrome

    Directory of Open Access Journals (Sweden)

    Toshiaki eKawakami

    2015-08-01

    Full Text Available Atopic dermatitis (AD is a chronic inflammatory skin disease. Myeloproliferative neoplasms (MPNs are hematopoietic malignancies caused by uncontrolled proliferation of hematopoietic stem/progenitor cells. Recent studies have described several mutant mice exhibiting both AD-like skin inflammation and MPN. Common pathways for skin inflammation encompass overexpression of thymic stromal lymphopoietin and reduced signaling of epidermal growth factor receptor in the epidermis, while overproduction of granulocyte-colony stimulating factor by keratinocytes and constitutive activation of Stat5 in hematopoietic stem cells are important for the development of MPN. The murine studies suggest the existence of a similar human disease tentatively termed the AD-MPN syndrome.

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

    Directory of Open Access Journals (Sweden)

    Vlad Novitsky

    2015-12-01

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

  11. Epidemics in Adaptive Social Networks with Temporary Link Deactivation

    Science.gov (United States)

    Tunc, Ilker; Shkarayev, Maxim S.; Shaw, Leah B.

    2013-04-01

    Disease spread in a society depends on the topology of the network of social contacts. Moreover, individuals may respond to the epidemic by adapting their contacts to reduce the risk of infection, thus changing the network structure and affecting future disease spread. We propose an adaptation mechanism where healthy individuals may choose to temporarily deactivate their contacts with sick individuals, allowing reactivation once both individuals are healthy. We develop a mean-field description of this system and find two distinct regimes: slow network dynamics, where the adaptation mechanism simply reduces the effective number of contacts per individual, and fast network dynamics, where more efficient adaptation reduces the spread of disease by targeting dangerous connections. Analysis of the bifurcation structure is supported by numerical simulations of disease spread on an adaptive network. The system displays a single parameter-dependent stable steady state and non-monotonic dependence of connectivity on link deactivation rate.

  12. Public acceptance of a hypothetical Ebola virus vaccine in Aceh, Indonesia: A hospital-based survey

    Directory of Open Access Journals (Sweden)

    Harapan Harapan

    2017-04-01

    Full Text Available Objective: To determine the acceptance towards a hypothetical Ebola virus vaccine (EVV and associated factors in a non-affected country, Indonesia. Methods: A hospital-based, cross-sectional study was conducted in four regencies of Aceh, Indonesia. A set of pre-tested questionnaires was used to obtain information on acceptance towards EVV and a range of explanatory variables. Associations between EVV acceptance and explanatory variables were tested using multi-steps logistic regression analysis and the Spearman's rank correlation. Results: Participants who had knowledge on Ebola virus disease (EVD were 45.3% (192/424 and none of the participants achieved 80% correct answers on the knowledge regarding to EVD. About 73% of participants expressed their willingness to receive the EVV. Education attainment, occupation, monthly income, have heard regarding to EVD previously, socioeconomic level, attitude towards vaccination practice and knowledge regarding to EVD were associated significantly with acceptance towards EVV in univariate analysis (P < 0.05. In the final multivariate model, socio-economic level, attitude towards vaccination practice and knowledge regarding to EVD were the independent explanatory variables for EVV acceptance. Conclusions: The knowledge of EVD was low, but this minimally affected the acceptance towards EVV. However, to facilitate optimal uptake of EVV, dissemination of vaccine-related information prior to its introduction is required.

  13. Identification of functional candidates amongst hypothetical proteins of Treponema pallidum ssp. pallidum.

    Science.gov (United States)

    Naqvi, Ahmad Abu Turab; Shahbaaz, Mohd; Ahmad, Faizan; Hassan, Md Imtaiyaz

    2015-01-01

    Syphilis is a globally occurring venereal disease, and its infection is propagated through sexual contact. The causative agent of syphilis, Treponema pallidum ssp. pallidum, a Gram-negative sphirochaete, is an obligate human parasite. Genome of T. pallidum ssp. pallidum SS14 strain (RefSeq NC_010741.1) encodes 1,027 proteins, of which 444 proteins are known as hypothetical proteins (HPs), i.e., proteins of unknown functions. Here, we performed functional annotation of HPs of T. pallidum ssp. pallidum using various database, domain architecture predictors, protein function annotators and clustering tools. We have analyzed the sequences of 444 HPs of T. pallidum ssp. pallidum and subsequently predicted the function of 207 HPs with a high level of confidence. However, functions of 237 HPs are predicted with less accuracy. We found various enzymes, transporters, binding proteins in the annotated group of HPs that may be possible molecular targets, facilitating for the survival of pathogen. Our comprehensive analysis helps to understand the mechanism of pathogenesis to provide many novel potential therapeutic interventions.

  14. Stochastic analysis of a novel nonautonomous periodic SIRI epidemic system with random disturbances

    Science.gov (United States)

    Zhang, Weiwei; Meng, Xinzhu

    2018-02-01

    In this paper, a new stochastic nonautonomous SIRI epidemic model is formulated. Given that the incidence rates of diseases may change with the environment, we propose a novel type of transmission function. The main aim of this paper is to obtain the thresholds of the stochastic SIRI epidemic model. To this end, we investigate the dynamics of the stochastic system and establish the conditions for extinction and persistence in mean of the disease by constructing some suitable Lyapunov functions and using stochastic analysis technique. Furthermore, we show that the stochastic system has at least one nontrivial positive periodic solution. Finally, numerical simulations are introduced to illustrate our results.

  15. Hopf Bifurcation of a Delayed Epidemic Model with Information Variable and Limited Medical Resources

    Directory of Open Access Journals (Sweden)

    Caijuan Yan

    2014-01-01

    Full Text Available We consider SIR epidemic model in which population growth is subject to logistic growth in absence of disease. We get the condition for Hopf bifurcation of a delayed epidemic model with information variable and limited medical resources. By analyzing the corresponding characteristic equations, the local stability of an endemic equilibrium and a disease-free equilibrium is discussed. If the basic reproduction ratio ℛ01, we obtain sufficient conditions under which the endemic equilibrium E* of system is locally asymptotically stable. And we also have discussed the stability and direction of Hopf bifurcations. Numerical simulations are carried out to explain the mathematical conclusions.

  16. The yellow Fever epidemic in Western mali, september-november 1987: why did epidemiological surveillance fail?

    Science.gov (United States)

    Kurz, X

    1990-03-01

    Recent yellow fever epidemics in West Africa have underlined the discrepancy between the official number of cases and deaths and those estimated by a retrospective epidemiological investigation. During the yellow fever epidemic that broke out in western Mali in September 1987, a total of 305 cases and 145 deaths were officially notified, but estimates revealed true figures abut five times higher. This paper attempts to discuss the factors that hindered early case detection and more complete reporting. They were, first, the insufficient training on the clinical diagnosis, the blood sampling method for laboratory confirmation, and the curative treatment of patients (resulting in low utilization of services); second, the lack of an action plan to prepare in advance a quick response to the epidemic, affecting reporting procedures at the peripheral level and active case-finding during the outbreak; and third, the lack of laboratory facilities for a quick confirmation of the disease. The difficulties experienced during the yellow fever epidemic in Mali demonstrated the importance of a preparedness strategy for epidemic control, based on an integrated approach of epidemiological surveillance within basic health service activities. The need for regional collaboration and for institutionalized funds in the donor community that could be mobilized for epidemic preparedness activities is also emphasized.

  17. Halting HIV/AIDS with avatars and havatars: a virtual world approach to modelling epidemics

    Directory of Open Access Journals (Sweden)

    Smith? Robert J

    2009-11-01

    Full Text Available Abstract Background A major deficit of all approaches to epidemic modelling to date has been the need to approximate or guess at human behaviour in disease-transmission-related contexts. Avatars are generally human-like figures in virtual computer worlds controlled by human individuals. Methods We introduce the concept of a "havatar", which is a (human, avatar pairing. Evidence is mounting that this pairing behaves in virtual contexts much like the human in the pairing might behave in analogous real-world contexts. Results We propose that studies of havatars, in a virtual world, may give a realistic approximation of human behaviour in real-world contexts. If the virtual world approximates the real world in relevant details (geography, transportation, etc., virtual epidemics in that world could accurately simulate real-world epidemics. Havatar modelling of epidemics therefore offers a complementary tool for tackling how best to halt epidemics, including perhaps HIV/AIDS, since sexual behaviour is a significant component of some virtual worlds, such as Second Life. Conclusion Havatars place the control parameters of an epidemic in the hands of each individual. By providing tools that everyone can understand and use, we could democratise epidemiology.

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

    Science.gov (United States)

    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.

  19. [Science in the crosshairs of enlightenment. Significance of hypothetical thinking].

    Science.gov (United States)

    Wieland, Wolfgang

    2011-01-01

    To further the enlightenment primarily or even only by means of science was the hope of most representatives of the movement of the enlightenment which gave its name to a whole period of European cultural history. Only a few of its representatives, like Montesquieu and Rousseau, doubted for good reasons, whether and how the goals of the enlightenment can be reached at all by the means of science alone. In his Discours préliminaires to the Encyclopédie D'Alembert still wanted to limit science proper to the narrower field of those kinds of research which were strictly based on observations and calculations alone. In this way he remained committed to Descartes' ideal method of receiving authentic knowledge only by deduction from evident axioms or fundamental theorems. Pascal's casual discovery of the calculation of probabilities allowed to apply mathematics on the hidden laws of the apparent casualties of the human life world. Bacon's project of empirical science as a rational and methodological art of conducting experiments could replace the methodological ideal of science more geometrico. Lichtenberg's refined sensibility for the subjunctive linguistic forms of hypothetical thinking indicates a new understanding of inventing and testing hypotheses as the two most important methods of the experimental sciences when compared to the formal sciences of logic and mathematics. Whoever is studying the history of science of modern times in the cross wire of the enlightenment, will realize soon that science has always been in need of being illuminated about its own chances, risks and side effects. The project of enlightenment through science had to be complemented by the project of an enlightenment about science right from its beginning. Because of the implicit risks and side effects the project of enlightenment has to be enlightenment despite of science and because of science. On the one hand, as a special form of human practice the sciences are directed towards

  20. Analysis of hypothetical LMFBR whole-core accidents in the USA

    International Nuclear Information System (INIS)

    Ferguson, D.R.; Deitrich, L.W.; Brown, N.W.; Waltar, A.E.

    1978-01-01

    Methods used for analysis of material behaviour, accident phenomenology and integrated accident calculations are reviewed. Applications of these methods to hypothetical LOF and TOP accidents are discussed. Recent results obtained from applications to FFTF and CRBRP are presented. (author)

  1. Utility and potential of rapid epidemic intelligence from internet-based sources.

    Science.gov (United States)

    Yan, S J; Chughtai, A A; Macintyre, C R

    2017-10-01

    Rapid epidemic detection is an important objective of surveillance to enable timely intervention, but traditional validated surveillance data may not be available in the required timeframe for acute epidemic control. Increasing volumes of data on the Internet have prompted interest in methods that could use unstructured sources to enhance traditional disease surveillance and gain rapid epidemic intelligence. We aimed to summarise Internet-based methods that use freely-accessible, unstructured data for epidemic surveillance and explore their timeliness and accuracy outcomes. Steps outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist were used to guide a systematic review of research related to the use of informal or unstructured data by Internet-based intelligence methods for surveillance. We identified 84 articles published between 2006-2016 relating to Internet-based public health surveillance methods. Studies used search queries, social media posts and approaches derived from existing Internet-based systems for early epidemic alerts and real-time monitoring. Most studies noted improved timeliness compared to official reporting, such as in the 2014 Ebola epidemic where epidemic alerts were generated first from ProMED-mail. Internet-based methods showed variable correlation strength with official datasets, with some methods showing reasonable accuracy. The proliferation of publicly available information on the Internet provided a new avenue for epidemic intelligence. Methodologies have been developed to collect Internet data and some systems are already used to enhance the timeliness of traditional surveillance systems. To improve the utility of Internet-based systems, the key attributes of timeliness and data accuracy should be included in future evaluations of surveillance systems. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. 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.

  3. Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic.

    Directory of Open Access Journals (Sweden)

    Daniel Rios Garza

    Full Text Available The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic characteristics and the determinants of this altered sucrose fermenting phenotype, the genome of the strain IEC224 was sequenced. This paper reports a broad genomic study of this strain, showing its correlation with the major epidemic lineage. The potentially mobile genomic regions are shown to possess GC content deviation, and harbor the main V. cholera virulence genes. A novel bioinformatic approach was applied in order to identify the putative functions of hypothetical proteins, and was compared with the automatic annotation by RAST. The genome of a large bacteriophage was found to be integrated to the IEC224's alanine aminopeptidase gene. The presence of this phage is shown to be a common characteristic of the El Tor strains from the Latin American epidemic, as well as its putative ancestor from Angola. The defective sucrose fermenting phenotype is shown to be due to a single nucleotide insertion in the V. cholerae sucrose-specific transportation gene. This frame-shift mutation truncated a membrane protein, altering its structural pore-like conformation. Further, the identification of a common bacteriophage reinforces both the monophyletic and African-Origin hypotheses for the main causative agent of the 1991 Latin America cholera epidemics.

  4. Stochastic dynamics of dengue epidemics.

    Science.gov (United States)

    de Souza, David R; Tomé, Tânia; Pinho, Suani T R; Barreto, Florisneide R; de Oliveira, Mário J

    2013-01-01

    We use a stochastic Markovian dynamics approach to describe the spreading of vector-transmitted diseases, such as dengue, and the threshold of the disease. The coexistence space is composed of two structures representing the human and mosquito populations. The human population follows a susceptible-infected-recovered (SIR) type dynamics and the mosquito population follows a susceptible-infected-susceptible (SIS) type dynamics. The human infection is caused by infected mosquitoes and vice versa, so that the SIS and SIR dynamics are interconnected. We develop a truncation scheme to solve the evolution equations from which we get the threshold of the disease and the reproductive ratio. The threshold of the disease is also obtained by performing numerical simulations. We found that for certain values of the infection rates the spreading of the disease is impossible, for any death rate of infected mosquitoes.

  5. 2014 Anthrax epidemic in Koubia prefecture, Guinea-Conakry.

    Science.gov (United States)

    Sow, M S; Boushab, M B; Balde, H; Camara, A; Sako, F B; Traoré, F A; Diallo, M O S; Diallo, M D; Keita, M; Sylla, A O; Tounkara, T M; Cissé, M

    2016-11-01

    Anthrax disease is an anthropozoonosis caused by a Gram-positive bacterium, Bacillus anthracis. Our objective was to describe the epidemiological, clinical and therapeutic features of the 2014 epidemic in Koubia prefecture. This retrospective study examined all of the anthrax cases reported in Fafaya, Koubia Prefecture. In March and April 2014, there were 39 cases of human anthrax reported, for an incidence of 1.135%. The mean age was 20.9 (± 18.3) with a sex ratio of 2.54 (28/11) in favor of men. Seventy-six percent (23/39) were single. More than one half were students (53.8%). The main clinical signs were fever in 71, 8% (n = 28 /), papules 59% (n = 23), vesicles of 59% (n = 23) Digestive and cutaneous signs represented 35.9 % and 64.1% respectively; 35% had ingested contaminated meat and 17.95% were in direct contact with a sick animal. We didn't find any correlation between the mode of infection and onset of signs. The fatality rate was 28.21%. The 2014 epidemic of anthrax disease in the Koubia prefecture was marked by a high incidence and lethality. Clinical manifestations were cutaneaous and digestive. These results may serve further interventions to fight against anthrax disease. They should mainly focus on an awareness of peasants, surveillance and vaccination of cattle. Other studies seem to be necessary.

  6. Critical behavior in a stochastic model of vector mediated epidemics

    Science.gov (United States)

    Alfinito, E.; Beccaria, M.; Macorini, G.

    2016-06-01

    The extreme vulnerability of humans to new and old pathogens is constantly highlighted by unbound outbreaks of epidemics. This vulnerability is both direct, producing illness in humans (dengue, malaria), and also indirect, affecting its supplies (bird and swine flu, Pierce disease, and olive quick decline syndrome). In most cases, the pathogens responsible for an illness spread through vectors. In general, disease evolution may be an uncontrollable propagation or a transient outbreak with limited diffusion. This depends on the physiological parameters of hosts and vectors (susceptibility to the illness, virulence, chronicity of the disease, lifetime of the vectors, etc.). In this perspective and with these motivations, we analyzed a stochastic lattice model able to capture the critical behavior of such epidemics over a limited time horizon and with a finite amount of resources. The model exhibits a critical line of transition that separates spreading and non-spreading phases. The critical line is studied with new analytical methods and direct simulations. Critical exponents are found to be the same as those of dynamical percolation.

  7. 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

  8. Spatio-Temporal Analysis of Epidemic Phenomena Using the R Package surveillance

    Directory of Open Access Journals (Sweden)

    Sebastian Meyer

    2017-05-01

    Full Text Available The availability of geocoded health data and the inherent temporal structure of communicable diseases have led to an increased interest in statistical models and software for spatio-temporal data with epidemic features. The open source R package surveillance can handle various levels of aggregation at which infective events have been recorded: individual-level time-stamped geo-referenced data (case reports in either continuous space or discrete space, as well as counts aggregated by period and region. For each of these data types, the surveillance package implements tools for visualization, likelihoood inference and simulation from recently developed statistical regression frameworks capturing endemic and epidemic dynamics. Altogether, this paper is a guide to the spatio-temporal modeling of epidemic phenomena, exemplified by analyses of public health surveillance data on measles and invasive meningococcal disease.

  9. The changing face of pediatric hypertension in the era of the childhood obesity epidemic.

    Science.gov (United States)

    Flynn, Joseph

    2013-07-01

    Historically, hypertension in childhood was thought to be an uncommon diagnosis, usually related to an underlying condition, most often parenchymal renal disease. Primary hypertension in childhood was felt to be quite rare. However, the worldwide childhood obesity epidemic has had a profound impact on the frequency of hypertension and other obesity-related conditions with the result that primary hypertension should now be viewed as one of the most common health conditions in the young. This review will present updated data on the prevalence of hypertension in children and adolescents, the impact of the childhood obesity epidemic on hypertension prevalence and blood pressure levels, shifts in how often primary hypertension is being diagnosed in childhood, and an overview of the pathophysiology of obesity-related hypertension. It is hoped that improved understanding of the significance of these issues will lead to improved recognition and treatment, which will be the key to averting an epidemic of cardiovascular disease in adulthood.

  10. Cell Phones ≠ Self and Other Problems with Big Data Detection and Containment during Epidemics.

    Science.gov (United States)

    Erikson, Susan L

    2018-03-08

    Evidence from Sierra Leone reveals the significant limitations of big data in disease detection and containment efforts. Early in the 2014-2016 Ebola epidemic in West Africa, media heralded HealthMap's ability to detect the outbreak from newsfeeds. Later, big data-specifically, call detail record data collected from millions of cell phones-was hyped as useful for stopping the disease by tracking contagious people. It did not work. In this article, I trace the causes of big data's containment failures. During epidemics, big data experiments can have opportunity costs: namely, forestalling urgent response. Finally, what counts as data during epidemics must include that coming from anthropological technologies because they are so useful for detection and containment. © 2018 The Authors Medical Anthropology Quarterly published by Wiley Periodicals, Inc. on behalf of American Anthropological Association.

  11. 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

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

    Science.gov (United States)

    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

  13. 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

  14. Global dynamics of a dengue epidemic mathematical model

    Energy Technology Data Exchange (ETDEWEB)

    Cai Liming [Department of Mathematics, Xinyang Normal University, Xinyang 464000 (China); Academy of Mathematics and Systems Science, Academia Sinica, Beijing 100080 (China)], E-mail: lmcai06@yahoo.com.cn; Guo Shumin [Beijing Institute of Information Control, Beijing 100037 (China); Li, XueZhi [Department of Mathematics, Xinyang Normal University, Xinyang 464000 (China); Ghosh, Mini [School of Mathematics and Computer Application, Thapar University, Patiala 147004 (India)

    2009-11-30

    The paper investigates the global stability of a dengue epidemic model with saturation and bilinear incidence. The constant human recruitment rate and exponential natural death, as well as vector population with asymptotically constant population, are incorporated into the model. The model exhibits two equilibria, namely, the disease-free equilibrium and the endemic equilibrium. The stability of these two equilibria is controlled by the threshold number R{sub 0}. It is shown that if R{sub 0} is less than one, the disease-free equilibrium is globally asymptotically stable and in such a case the endemic equilibrium does not exist; if R{sub 0} is greater than one, then the disease persists and the unique endemic equilibrium is globally asymptotically stable.

  15. Global dynamics of a dengue epidemic mathematical model

    International Nuclear Information System (INIS)

    Cai Liming; Guo Shumin; Li, XueZhi; Ghosh, Mini

    2009-01-01

    The paper investigates the global stability of a dengue epidemic model with saturation and bilinear incidence. The constant human recruitment rate and exponential natural death, as well as vector population with asymptotically constant population, are incorporated into the model. The model exhibits two equilibria, namely, the disease-free equilibrium and the endemic equilibrium. The stability of these two equilibria is controlled by the threshold number R 0 . It is shown that if R 0 is less than one, the disease-free equilibrium is globally asymptotically stable and in such a case the endemic equilibrium does not exist; if R 0 is greater than one, then the disease persists and the unique endemic equilibrium is globally asymptotically stable.

  16. 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.

  17. [Recurrent epidemics of gastroenteritis caused by norovirus GI.3 in a small hotel].

    Science.gov (United States)

    Soini, Jani; Hemminki, Kaisa; Pirnes, Aija; Roivainen, Merja; Al-Hello, Haider; Maunula, Leena; Kauppinen, Ari; Miettinen, Likka; Smit, Pieter W; Huusko, Sari; Toikkanen, Salla; Rimhanen-Finne, Ruska

    2016-01-01

    Recurrent cases of gastroenteritis occurred in a small hotel. The causative agent of disease could not be detected. The cause and the source of the disease were established through epidemiological investigations and laboratory diagnosis. The causative agent of the disease was norovirus GI.3. Norovirus GI was detected in the water from the well and on surfaces at the hotel. Both epidemiological investigations and laboratory diagnostics are needed in resolving epidemics. Continuous development of laboratory methods is important.

  18. Worm epidemics in wireless ad hoc networks

    Energy Technology Data Exchange (ETDEWEB)

    Nekovee, Maziar [BT Research, Polaris 134, Adastral Park, Martlesham, Suffolk IP5 3RE (United Kingdom); Centre for Computational Science, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2007-06-15

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  19. Worm epidemics in wireless ad hoc networks

    Science.gov (United States)

    Nekovee, Maziar

    2007-06-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  20. Worm epidemics in wireless ad hoc networks

    International Nuclear Information System (INIS)

    Nekovee, Maziar

    2007-01-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet