WorldWideScience

Sample records for internists epidemics outbreaks

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. Outbreak of epidemic keratoconjunctivitis caused by adenovirus in medical residents.

    Science.gov (United States)

    Melendez, Carlos Pantoja; Florentino, Margarita Matias; Martinez, Irma Lopez; Lopez, Herlinda Mejia

    2009-01-01

    The present work documents an outbreak of epidemic keratoconjunctivitis among ophthalmology residents, its influence in the presentation of the community cases, the use of molecular techniques for its diagnosis, and the implementation of successful control measures for its containment. Isolation of the etiologic agent was achieved using cultured African green monkey kidney epithelial cells (VERO). Through molecular tests, such as polymerase chain reaction (PCR) and DNA sequencing, the genotype of the isolated virus was identified. The sequences obtained were aligned with data reported in the NCBI GenBank. A scheme of outbreak control measures was designed to enforce correct sanitary measures in the clinic. The statistical program, Epi info 2002, and openepi were used to determine the attack rate. The Excel Microsoft program was used to elaborate the endemic channel. Nine of the ten samples studied were isolated from the culture and identified by Adenovirus-specifc PCR. Sequencing allowed identification of Ad8 as the agent responsible for the outbreak. The attack rate was 24.39 cases per 100. The epidemic curve allowed identification of a disseminated source in the Institute of Ophthalmology "Conde de Valenciana." It was not possible to calculate the incubation periods among the cases. The endemic channel showed the presence of an epidemic keratoconjunctivitis among the patients that had been cared for at the out-patient services of the institute. One outbreak of a disseminated source caused by Ad8 was detected in the institute among its medical residents, probably associated with relaxation of the habitual sanitary measures during an epidemic of hemorrhagic conjunctivitis among the patients cared for at the institute. The proposed scheme to control the outbreak allowed for its containment and controlled the epidemic of associated cases.

  6. 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.

  7. An outbreak of epidemic keratoconjunctivitis at an outpatient ophthalmology clinic

    Directory of Open Access Journals (Sweden)

    Timothy J Doyle

    2010-12-01

    Full Text Available Epidemic keratoconjunctivitis (EKC is an acute eye infection caused by adenovirus. We investigated an outbreak of EKC at an outpatient ophthalmology practice in the context of a suspected community wide increase in EKC activity. A site visit was made to the facility reporting the outbreak. A line list was created of patients clinically diagnosed with EKC at the practice during the previous 5 months. A questionnaire was faxed to all other licensed ophthalmologists in the county regarding recent EKC activity in their facility. Descriptive data analyses were conducted. The outbreak facility reported 37 patients clinically diagnosed with EKC during the previous 5 months. In addition, the single ophthalmologist at the practice also had symptoms compatible with EKC during the outbreak period. Specimens were collected on 4 patients and all were positive for adenovirus serotype 8. Forty percent of ophthalmologists surveyed in the county saw at least one EKC patient in the previous 3 months, and 20% reported a perceived increase in EKC activity in recent months over normal seasonal patterns. The outbreak at the facility likely began as part of a widespread community increase in EKC that may have been amplified at the facility through nosocomial transmission. Medical providers experiencing increases in EKC activity above seasonally expected norms should contact their public health department for assistance with etiologic diagnoses and outbreak control.

  8. 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.

  9. 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.

  10. Ebola hemorrhagic fever outbreaks: strategies for effective epidemic management, containment and control

    Directory of Open Access Journals (Sweden)

    Gerald Amandu Matua

    2015-05-01

    The current epidemic management approaches are largely “reactive”, with containment efforts aimed at halting spread of existing outbreaks. We recommend that for better outcomes, in addition to “reactive” interventions, “pre-emptive” strategies also need to be instituted. We conclude that emphasizing both “reactive” and “pre-emptive” strategies is more likely to lead to better epidemic preparedness and response at individual, community, institutional, and government levels, resulting in timely containment of future Ebola outbreaks.

  11. The Impact of an Epidemic Outbreak on Consumer Expenditures:An Empirical Assessment for MERS Korea

    Directory of Open Access Journals (Sweden)

    Hojin Jung

    2016-05-01

    Full Text Available In this paper, we investigate the effect of an epidemic outbreak on consumer expenditures. In light of scanner panel data on consumers’ debit and credit card transactions, we present empirical evidence that outbreaks cause considerable disruption in total consumer expenditures with significant heterogeneity across categories. Our findings strongly imply that customers alter their behaviors to reduce the risk of infection. The estimated effect of an epidemic outbreak is qualitatively different from that of other macroeconomic factors. The implications of this research provide important guidance for policy interventions and marketing decisions aimed at sustaining economic growth.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    John M Drake

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

  14. 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.

  15. Ebola hemorrhagic fever outbreaks: strategies for effective epidemic management, containment and control.

    Science.gov (United States)

    Matua, Gerald Amandu; Van der Wal, Dirk Mostert; Locsin, Rozzano C

    2015-01-01

    Ebola hemorrhagic fever, caused by the highly virulent RNA virus of the filoviridae family, has become one of the world's most feared pathogens. The virus induces acute fever and death, often associated with hemorrhagic symptoms in up to 90% of infected patients. The known sub-types of the virus are Zaire, Sudan, Taï Forest, Bundibugyo and Reston Ebola viruses. In the past, outbreaks were limited to the East and Central African tropical belt with the exception of Ebola Reston outbreaks that occurred in animal facilities in the Philippines, USA and Italy. The on-going outbreak in West Africa that is causing numerous deaths and severe socio-economic challenges has resulted in widespread anxiety globally. This panic may be attributed to the intense media interest, the rapid spread of the virus to other countries like United States and Spain, and moreover, to the absence of an approved treatment or vaccine. Informed by this widespread fear and anxiety, we analyzed the commonly used strategies to manage and control Ebola outbreaks and proposed new approaches that could improve epidemic management and control during future outbreaks. We based our recommendations on epidemic management practices employed during recent outbreaks in East, Central and West Africa, and synthesis of peer-reviewed publications as well as published "field" information from individuals and organizations recently involved in the management of Ebola epidemics. The current epidemic management approaches are largely "reactive", with containment efforts aimed at halting spread of existing outbreaks. We recommend that for better outcomes, in addition to "reactive" interventions, "pre-emptive" strategies also need to be instituted. We conclude that emphasizing both "reactive" and "pre-emptive" strategies is more likely to lead to better epidemic preparedness and response at individual, community, institutional, and government levels, resulting in timely containment of future Ebola outbreaks. Copyright

  16. Water-borne epidemic outbreaks; Brotes epidemicos de transmision hidrica

    Energy Technology Data Exchange (ETDEWEB)

    Ciranda Larrea, F.B.; Hidalgo Garcia, E.; Peiro Callizo, E.F.; Herrero Alana, G.

    1995-12-31

    The control of water-transmitted infections is one of the key aims of any Public Heath-Care System. For this paper a descriptive epidemiologic analysis has been performed using data obtained through normalized forms as well as Annual Reports of Epidemiology Units and Veterinary Inspection Records. A total of 22 outbreaks have been recorded in the period of reference. Those outbreaks affected 2.263 people. The attack-rate was of 99 people affected for each 1000 ar risk. The main agents turned out to be Norwalk virus, Rotavirus and A-Hepatitis virus. The most important risk factor was undoubtedly the ingestion of untreated or not properly treated water. The improvement of water treatment and distribution systems, the increase in the population being supplied with potable water, along with the ease of the drought have caused a significant drop in the number of water-transmitted outbreaks. (Author)

  17. 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

  18. Dutch Q fever epidemic in a ‘One Health’ context: outbreaks, seroprevalence and occupational risks

    NARCIS (Netherlands)

    Schimmer, Barbara

    2018-01-01

    Q fever is a worldwide zoonosis caused by the bacterium Coxiella burnetii (C. burnetii). Small ruminants, in particular sheep and goats, have been associated with community Q fever outbreaks in other countries. Just prior to the Dutch Q fever epidemic, a nationwide survey indicated that only 2.4% of

  19. 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)

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

    Science.gov (United States)

    Upadhyay, Ranjit Kumar; Roy, Parimita

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

  1. The 2012 Madeira dengue outbreak: epidemiological determinants and future epidemic potential.

    Directory of Open Access Journals (Sweden)

    José Lourenço

    2014-08-01

    Full Text Available Dengue, a vector-borne viral disease of increasing global importance, is classically associated with tropical and sub-tropical regions around the world. Urbanisation, globalisation and climate trends, however, are facilitating the geographic spread of its mosquito vectors, thereby increasing the risk of the virus establishing itself in previously unaffected areas and causing large-scale epidemics. On 3 October 2012, two autochthonous dengue infections were reported within the Autonomous Region of Madeira, Portugal. During the following seven months, this first 'European' dengue outbreak caused more than 2000 local cases and 81 exported cases to mainland Europe. Here, using an ento-epidemiological mathematical framework, we estimate that the introduction of dengue to Madeira occurred around a month before the first official cases, during the period of maximum influx of airline travel, and that the naturally declining temperatures of autumn were the determining factor for the outbreak's demise in early December 2012. Using key estimates, together with local climate data, we further propose that there is little support for dengue endemicity on this island, but a high potential for future epidemic outbreaks when seeded between May and August-a period when detection of imported cases is crucial for Madeira's public health planning.

  2. The 2012 Madeira dengue outbreak: epidemiological determinants and future epidemic potential.

    Science.gov (United States)

    Lourenço, José; Recker, Mario

    2014-08-01

    Dengue, a vector-borne viral disease of increasing global importance, is classically associated with tropical and sub-tropical regions around the world. Urbanisation, globalisation and climate trends, however, are facilitating the geographic spread of its mosquito vectors, thereby increasing the risk of the virus establishing itself in previously unaffected areas and causing large-scale epidemics. On 3 October 2012, two autochthonous dengue infections were reported within the Autonomous Region of Madeira, Portugal. During the following seven months, this first 'European' dengue outbreak caused more than 2000 local cases and 81 exported cases to mainland Europe. Here, using an ento-epidemiological mathematical framework, we estimate that the introduction of dengue to Madeira occurred around a month before the first official cases, during the period of maximum influx of airline travel, and that the naturally declining temperatures of autumn were the determining factor for the outbreak's demise in early December 2012. Using key estimates, together with local climate data, we further propose that there is little support for dengue endemicity on this island, but a high potential for future epidemic outbreaks when seeded between May and August-a period when detection of imported cases is crucial for Madeira's public health planning.

  3. [Epidemic outbreak of 81 cases of brucellosis following the consumption of fresh cheese without pasteurization].

    Science.gov (United States)

    Castell Monsalve, J; Rullán, J V; Peiró Callizo, E F; Nieto-Sandoval Alcolea, A

    1996-01-01

    In spite of the great effort that has been made in recent years in Castilla-La Mancha to control brucelosis, a lack of awareness on the part of producers and consumers leads to major epidemic outbreak, such as the one described below. A description of the outbreak is described and a study is conducted of cases and controls to determine the factors which are responsible for the epidemic. Unadjusted and adjusted Odds Ratios (O.R.) are obtained together with their confidence intervals, for the main epidemiological factors studied. A total of 81 cases of brucelosis were recorded in a period of 25 weeks. All the cases occurred in the same borough or were in some way linked to it. In the case and controls study no differences were found with regard to age, sex, contact with livestock or the consumption of pasteurised milk or cheese. A strong link was established between the illness and the consumption of home-made cottage cheese prepared by a small-scale producer in the borough, (O.R. = 311.9; C.I. = 95% = 41.48-12735)., whose livestock turned out to be infected with Brucella Mellitensis. This outbreak showed that in Spain, there is a risk of contracting brucelosis by consuming non-pasteurised dairy products, particularly cheese, when these are not subjected to the normal sanitary and health controls. The benefits of epidemiological research in the search for cases and determining the factors responsible for the outbreak are also demonstrated. An intensification of controls, the cleansing of the herds and flocks and health education in general, are suitable instruments for controlling this zoonosis in Spain.

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

    Directory of Open Access Journals (Sweden)

    Carlos Polanco

    2013-01-01

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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Nohrstedt, Daniel; Baekkeskov, Erik

    2018-01-01

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

  7. Protecting healthcare workers in an acute care environment during epidemics: lessons learned from the SARS outbreak

    Directory of Open Access Journals (Sweden)

    John Casken

    2011-01-01

    Full Text Available During the 2002-2003 the SARS outbreak resulted in 8,450 illnesses and 812 deaths. Out of these documented cases 1706 were among healthcare workers (HCWsThe purpose of this paper is to focus on and examine the details of infection control (IC measures and which of these measures appear to be the most effective in stopping disease spread. Historically, HCWs have had poor compliance with the use of IC measures prior to the SARS outbreak. A number of lessons were learned from the SARS epidemic that should be incorporated into healthcare institutions policies and procedures. They include the following: an emphasis on the correct and immediate use of IC measures; an increased focus on HCWs recognizing early perceived threats; healthcare institutions should mandate routine in-house education with periodic updates on IC measures; administrators need to acknowledge and encourage role models among staff; engineeringcontrols should be put in place to protect staff from pathogens; and finally, there should be clear and constant communication between administration and staff.

  8. 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.

  9. Rapid qualitative review of ethical issues surrounding healthcare for pregnant women or women of reproductive age in epidemic outbreaks.

    Science.gov (United States)

    Hummel, Patrik; Saxena, Abha; Klingler, Corinna

    2018-01-01

    This article describes, categorizes, and discusses the results of a rapid literature review aiming to provide an overview of the ethical issues and corresponding solutions surrounding pregnancies in epidemic outbreaks. The review was commissioned by the World Health Organization to inform responses to the Zika outbreak that began in 2015. Due to the urgency of the response efforts that needed to be informed by the literature search, a rapid qualitative review of the literature published in PubMed was conducted. The search and analysis were based on the operationalization of 3 key concepts: ethics, pregnancy, and epidemic outbreak. Ethical issues and solutions were interpreted within a principlist framework. The data were analyzed using qualitative content analysis. The search identified 259 publications, of which the full text of 23 papers was read. Of those, 20 papers contained a substantive part devoted to the topic of interest and were therefore analyzed further. We clustered the ethical issues and solutions around 4 themes: uncertainty, harms, autonomy/liberty, and effectiveness. Recognition of the identified ethical issues and corresponding solutions can inform and improve response efforts, public health planning, policies, and decision-making, as well as the activities of medical staff and counselors who practice before, during, or after an epidemic outbreak that affects pregnant women or those of reproductive age. The rapid review format proved to be useful despite its limited data basis and expedited review process.

  10. Implication of lateral genetic transfer in the emergence of Aeromonas hydrophila isolates of epidemic outbreaks in channel catfish.

    Directory of Open Access Journals (Sweden)

    Mohammad J Hossain

    Full Text Available To investigate the molecular basis of the emergence of Aeromonas hydrophila responsible for an epidemic outbreak of motile aeromonad septicemia of catfish in the Southeastern United States, we sequenced 11 A. hydrophila isolates that includes five reference and six recent epidemic isolates. Comparative genomics revealed that recent epidemic A. hydrophila isolates are highly clonal, whereas reference isolates are greatly diverse. We identified 55 epidemic-associated genetic regions with 313 predicted genes that are present in epidemic isolates but absent from reference isolates and 35% of these regions are located within genomic islands, suggesting their acquisition through lateral gene transfer. The epidemic-associated regions encode predicted prophage elements, pathogenicity islands, metabolic islands, fitness islands and genes of unknown functions, and 34 of the genes encoded in these regions were predicted as virulence factors. We found two pilus biogenesis gene clusters encoded within predicted pathogenicity islands. A functional metabolic island that encodes a complete pathway for myo-inositol catabolism was evident by the ability of epidemic A. hydrophila isolates to use myo-inositol as a sole carbon source. Testing of A. hydrophila field isolates found a consistent correlation between myo-inositol utilization as a sole carbon source and the presence of an epidemic-specific genetic marker. All epidemic isolates and one reference isolate shared a novel O-antigen cluster. Altogether we identified four different O-antigen biosynthesis gene clusters within the 11 sequenced A. hydrophila genomes. Our study reveals new insights into the evolutionary changes that have resulted in the emergence of recent epidemic A. hydrophila strains.

  11. Identification of resistance and virulence factors in an epidemic Enterobacter hormaechei outbreak strain

    NARCIS (Netherlands)

    Paauw, A.; Caspers, M.P.M.; Leverstein-van Hall, M.A.; Schuren, F.H.J.; Montijn, R.C.; Verhoef, J.; Fluit, A.C.

    2009-01-01

    Bacterial strains differ in their ability to cause hospital outbreaks. Using comparative genomic hybridization, Enterobacter cloacae complex isolates were studied to identify genetic markers specific for Enterobacter cloacae complex outbreak strains. No outbreak-specific genes were found that were

  12. The Significance of Witness Sensors for Mass Casualty Incidents and Epidemic Outbreaks.

    Science.gov (United States)

    Pan, Chih-Long; Lin, Chih-Hao; Lin, Yan-Ren; Wen, Hsin-Yu; Wen, Jet-Chau

    2018-02-02

    Due to the increasing number of natural and man-made disasters, mass casualty incidents occur more often than ever before. As a result, health care providers need to adapt in order to cope with the overwhelming patient surge. To ensure quality and safety in health care, accurate information in pandemic disease control, death reduction, and health quality promotion should be highlighted. However, obtaining precise information in real time is an enormous challenge to all researchers of the field. In this paper, innovative strategies are presented to develop a sound information network using the concept of "witness sensors." To overcome the reliability and quality limitations of information obtained through social media, researchers must focus on developing solutions that secure the authenticity of social media messages, especially for matters related to health. To address this challenge, we introduce a novel concept based on the two elements of "witness" and "sensor." Witness sensors can be key players designated to minimize limitations to quality of information and to distinguish fact from fiction during critical events. In order to enhance health communication practices and deliver valid information to end users, the education and management of witness sensors should be further investigated, especially for implementation during mass casualty incidents and epidemic outbreaks. ©Chih-Long Pan, Chih-Hao Lin, Yan-Ren Lin, Hsin-Yu Wen, Jet-Chau Wen. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 02.02.2018.

  13. Predicting Rift Valley Fever Inter-epidemic Activities and Outbreak Patterns: Insights from a Stochastic Host-Vector Model.

    Directory of Open Access Journals (Sweden)

    Sansao A Pedro

    2016-12-01

    Full Text Available Rift Valley fever (RVF outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency.

  14. STROKE PREVENTION IN INTERNIST PRACTICE

    Directory of Open Access Journals (Sweden)

    D. A. Napalkov

    2011-01-01

    Full Text Available Stroke secondary prevention in internist practice is discussed in accordance with up to date guidelines. Modern pharmacotherapy includes antiaggregants or anticoagulants, statins, and antihypertensive drugs. The choice of drugs is mostly founded on the rules of evidence based medicine, which allow adjusting individual treatment depending on clinical conditions. The composition of perindopril and indapamide is a preferred nowadays combination of antihypertensive drugs.

  15. An epidemic outbreak of Vibrio Cholerae El Tor 01 serotype ogawa biotype in a Lalpur town, Jamnagar, India

    Directory of Open Access Journals (Sweden)

    H D Shah

    2012-01-01

    Full Text Available Background: On December 19, 2010, 57 cases of gastroenteritis were reported in the community health center of Lalpur town. A rapid response team was sent to investigate the outbreak on December 21, 2010. Aim: To identify the source, to institute control and prevention measures. Materials and Methods: The outbreak was confirmed using the previous Integrated Integrated Disease Surveillance Project (IDSP data. Detailed history was taken, line listing of patients and house-to-house investigations were done. Environmental investigation and laboratory investigation of stool samples were also done. As the study was conducted during emergency response to the outbreak and was designed to provide information to orient the public health response, ethical approval was not required. Remedial measures were implemented. Results: Three hundred and thirty cases were reported during December 19, 2010 to January 2, 2011 in Lalpur town of Jamnagar district. Nineteen patients were found to be positive for Vibrio Cholerae 01 serotype ogawa biotype out of 117 stool samples. The mean age of patients was 24.23΁19.01 years. The outbreak had 1.88% attack rate with no mortality and 59.1% cases had to be admitted. Investigations revealed that the epidemic was waterborne. Ten leakages were found in the pipelines of the affected areas of Lalpur town near two riverbanks. Conclusion: Among identified gaps, delays in the initiation of the investigation of the epidemic and repairing of leakages were most important. In India, waterborne epidemics are usual occurrences during the year. In this scenario, the village health and sanitation committee and water board should follow guidelines, and monitoring of water sources, proper sewage disposal and sanitation measures should be undertaken.

  16. Identifying more epidemic clones during a hospital outbreak of multidrug-resistant Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Matthieu Domenech de Cellès

    Full Text Available Infections caused by multidrug-resistant bacteria are a major concern in hospitals. Current infection-control practices legitimately focus on hygiene and appropriate use of antibiotics. However, little is known about the intrinsic abilities of some bacterial strains to cause outbreaks. They can be measured at a population level by the pathogen's transmission rate, i.e. the rate at which the pathogen is transmitted from colonized hosts to susceptible hosts, or its reproduction number, counting the number of secondary cases per infected/colonized host. We collected data covering a 20-month surveillance period for carriage of multidrug-resistant Acinetobacter baumannii (MDRAB in a surgery ward. All isolates were subjected to molecular fingerprinting, and a cluster analysis of profiles was performed to identify clonal groups. We then applied stochastic transmission models to infer transmission rates of MDRAB and each MDRAB clone. Molecular fingerprinting indicated that 3 clonal complexes spread in the ward. A first model, not accounting for different clones, quantified the level of in-ward cross-transmission, with an estimated transmission rate of 0.03/day (95% credible interval [0.012-0.049] and a single-admission reproduction number of 0.61 [0.30-1.02]. The second model, accounting for different clones, suggested an enhanced transmissibility of clone 3 (transmission rate 0.047/day [0.018-0.091], with a single-admission reproduction number of 0.81 [0.30-1.56]. Clones 1 and 2 had comparable transmission rates (respectively, 0.016 [0.001-0.045], 0.014 [0.001-0.045]. The method used is broadly applicable to other nosocomial pathogens, as long as surveillance data and genotyping information are available. Building on these results, more epidemic clones could be identified, and could lead to follow-up studies dissecting the functional basis for variation in transmissibility of MDRAB lineages.

  17. 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

  18. Outbreak of a cluster with epidemic behavior due to Serratia marcescens after colistin administration in a hospital setting.

    Science.gov (United States)

    Merkier, Andrea Karina; Rodríguez, María Cecilia; Togneri, Ana; Brengi, Silvina; Osuna, Carolina; Pichel, Mariana; Cassini, Marcelo H; Centrón, Daniela

    2013-07-01

    Serratia marcescens causes health care-associated infections with important morbidity and mortality. Particularly, outbreaks produced by multidrug-resistant isolates of this species, which is already naturally resistant to several antibiotics, including colistin, are usually described with high rates of fatal outcomes throughout the world. Thus, it is important to survey factors associated with increasing frequency and/or emergence of multidrug-resistant S. marcescens nosocomial infections. We report the investigation and control of an outbreak with 40% mortality due to multidrug-resistant S. marcescens infections that happened from November 2007 to April 2008 after treatment with colistin for Acinetobacter baumannii meningitis was started at hospital H1 in 2005. Since that year, the epidemiological pattern of frequently recovered species has changed, with an increase of S. marcescens and Proteus mirabilis infections in 2006 in concordance with a significant decrease of the numbers of P. aeruginosa and A. baumannii isolates. A single pulsed-field gel electrophoresis (PFGE) cluster of S. marcescens isolates was identified during the outbreak. When this cluster was compared with S. marcescens strains (n = 21) from 10 other hospitals (1997 to 2010), it was also identified in both sporadic and outbreak isolates circulating in 4 hospitals in Argentina. In132::ISCR1::blaCTX-M-2 was associated with the multidrug-resistant cluster with epidemic behavior when isolated from outbreaks. Standard infection control interventions interrupted transmission of this cluster even when treatment with colistin continued in several wards of hospital H1 until now. Optimizing use of colistin should be achieved simultaneously with improved infection control to prevent the emergence of species naturally resistant to colistin, such as S. marcescens and P. mirabilis.

  19. The basic reproduction number R0 and effectiveness of reactive interventions during dengue epidemics: the 2002 dengue outbreak in Easter Island, Chile.

    Science.gov (United States)

    Chowell, Gerardo; Fuentes, R; Olea, A; Aguilera, X; Nesse, H; Hyman, J M

    2013-01-01

    We use a stochastic simulation model to explore the effect of reactive intervention strategies during the 2002 dengue outbreak in the small population of Easter Island, Chile. We quantified the effect of interventions on the transmission dynamics and epidemic size as a function of the simulated control intensity levels and the timing of initiation of control interventions. Because no dengue outbreaks had been reported prior to 2002 in Easter Island, the 2002 epidemic provided a unique opportunity to estimate the basic reproduction number R0 during the initial epidemic phase, prior to the start of control interventions. We estimated R0 at 27.2 (95%CI: 14.8, 49.3). We found that the final epidemic size is highly sensitive to the timing of start of interventions. However, even when the control interventions start several weeks after the epidemic onset, reactive intervention efforts can have a significant impact on the final epidemic size. Our results indicate that the rapid implementation of control interventions can have a significant effect in reducing the epidemic size of dengue epidemics.

  20. Economic impact of chikungunya epidemic: out-of-pocket health expenditures during the 2007 outbreak in Kerala, India.

    Science.gov (United States)

    Vijayakumar, K; George, B; Anish, T S; Rajasi, R S; Teena, M J; Sujina, C M

    2013-01-01

    The southern state of Kerala, India was seriously affected by a chikungunya epidemic in 2007. As this outbreak was the first of its kind, the morbidity incurred by the epidemic was a challenge to the state's public health system. A cross sectional survey was conducted in five districts of Kerala that were seriously affected by the epidemic, using a two-stage cluster sampling technique to select households, and the patients were identified using a syndromic case definition. We calculated the direct health expenditure of families and checked whether it exceed the margins of catastrophic health expenditure (CHE). The median (IQR) total out-of-pocket (OOP) health expenditure in the study population was USD7.4 (16.7). The OOP health expenditure did not show any significant association with increasing per-capita monthly income.The major share (47.4%) of the costs was utilized for buying medicines, but costs for transportation (17.2%), consultations (16.6%), and diagnoses (9.9%) also contributed significantly to the total OOP health expenditure. The OOP health expenditure was high in private sector facilities, especially in tertiary care hospitals. For more than 15% of the respondents, the OOP was more than double their average monthly family income. The chikungunya outbreak of 2007 had significantly contributed to the OOP expenditure of the affected community in Kerala.The OOP health expenditure incurred was high, irrespective of the level of income. Governments should attempt to ensure comprehensive financial protection by covering the costs of care, along with loss of productivity.

  1. 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.

  2. 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.

  3. THE "LEGAL EPIDEMIOLOGY" OF THE TEEN SEXTING EPIDEMIC: HOW THE MEDIA INFLUENCED A LEGISLATIVE OUTBREAK

    OpenAIRE

    Kimberlianne Podlas

    2012-01-01

    This article considers the media‟s impact on the “legal epidemiology” of the teen sexting epidemic.  Here, “teen sexting epidemic” refers to two things: (1) the belief that sext messaging by teens is rampant and spreading, hence, is an epidemic; and (2) the process by which a piece of information spreads like a virus, came to be understood as a pathogen infecting teens, resulted in a rash of child pornography prosecutions, and erupted into an o...

  4. What Internet services would patients like from hospitals during an epidemic? Lessons from the SARS outbreak in Toronto.

    Science.gov (United States)

    Rizo, Carlos A; Lupea, Doina; Baybourdy, Homayoun; Anderson, Matthew; Closson, Tom; Jadad, Alejandro R

    2005-08-03

    International health organizations and officials are bracing for a pandemic. Although the 2003 severe acute respiratory syndrome (SARS) outbreak in Toronto did not reach such a level, it created a unique opportunity to identify the optimal use of the Internet to promote communication with the public and to preserve health services during an epidemic. The aim of the study was to explore patients' attitudes regarding the health services that might be provided through the Internet to supplement those traditionally available in the event of a future mass emergency situation. We conducted "mask-to-mask" surveys of patients at three major teaching hospitals in Toronto during the second outbreak of SARS. Patients were surveyed at the hospital entrances and selected clinics. Descriptive statistics and logistic regression models were used for the analysis. In total, 1019 of 1130 patients responded to the survey (90% overall response rate). With respect to Internet use, 70% (711/1019) used the Internet by themselves and 57% (578/1019) with the help of a friend or family member. Of the Internet users, 68% (485/711) had already searched the World Wide Web for health information, and 75% (533/711) were interested in communicating with health professionals using the Internet as part of their ongoing care. Internet users expressed interest in using the Web for the following reasons: to learn about their health condition through patient education materials (84%), to obtain information about the status of their clinic appointments (83%), to send feedback to the hospital about how to improve its services (77%), to access screening tools to help determine if they were potentially affected by the infectious agent responsible for the outbreak (77%), to renew prescriptions (75%), to consult with their health professional about nonurgent matters (75%), and to access laboratory test results (75%). Regression results showed that younger age, higher education, and English as a first

  5. Potential for epidemic take-off from the primary outbreak farm via livestock movements

    Science.gov (United States)

    2011-01-01

    Background We consider the potential for infection to spread in a farm population from the primary outbreak farm via livestock movements prior to disease detection. We analyse how this depends on the time of the year infection occurs, the species transmitting, the length of infectious period on the primary outbreak farm, location of the primary outbreak, and whether a livestock market becomes involved. We consider short infectious periods of 1 week, 2 weeks and 4 weeks, characteristic of acute contagious livestock diseases. The analysis is based on farms in Scotland from 1 January 2003 to 31 July 2007. Results The proportion of primary outbreaks from which an acute contagious disease would spread via movement of livestock is generally low, but exhibits distinct annual cyclicity with peaks in May and August. The distance that livestock are moved varies similarly: at the time of the year when the potential for spread via movements is highest, the geographical spread via movements is largest. The seasonal patterns for cattle differ from those for sheep whilst there is no obvious seasonality for pigs. When spread via movements does occur, there is a high risk of infection reaching a livestock market; infection of markets can amplify disease spread. The proportion of primary outbreaks that would spread infection via livestock movements varies significantly between geographical regions. Conclusions In this paper we introduce a set-up for analysis of movement data that allows for a generalized assessment of the risk associated with infection spreading from a primary outbreak farm via livestock movements, applying this to Scotland, we assess how this risk depends upon the time of the year, species transmitting, location of the farm and other factors. PMID:22115121

  6. Ebola hemorrhagic fever outbreaks: strategies for effective epidemic management, containment and control

    OpenAIRE

    Matua, Gerald Amandu; Wal, Dirk Mostert Van der; Locsin, Rozzano C.

    2015-01-01

    Ebola hemorrhagic fever, caused by the highly virulent RNA virus of the filoviridae family, has become one of the world's most feared pathogens. The virus induces acute fever and death, often associated with hemorrhagic symptoms in up to 90% of infected patients. The known sub-types of the virus are Zaire, Sudan, Taï Forest, Bundibugyo and Reston Ebola viruses. In the past, outbreaks were limited to the East and Central African tropical belt with the exception of Ebola Reston outbreaks that o...

  7. Non-homogeneous stochastic birth and death processes with applications to epidemic outbreak data

    NARCIS (Netherlands)

    van den Broek, J.

    2012-01-01

    The subject of this thesis is the non-homogeneous birth-death process with some of its special cases and its use in modeling epidemic data. This model describes changes in the size of a population. New population members can appear with a rate, called the birth rate or the reproductive power, and

  8. The highly pathogenic avian influenza A (H7N7) virus epidemic in the Netherlands in 2003 - lessons learned from the first five outbreaks

    NARCIS (Netherlands)

    Elbers, A.R.W.; Fabri, T.; Vries, T.S.; Wit, de J.J.; Pijpers, A.; Koch, G.

    2004-01-01

    Clinical signs and gross lesions observed in poultry submitted for postmortem examination (PME) from the first five infected poultry flocks preceding the detection of the primary outbreak of highly pathogenic avian influenza (HPAI) of subtype H7N7 during the 2003 epidemic in the Netherlands are

  9. Classification of a hypervirulent Aeromonas hydrophila pathotype responsible for epidemic outbreaks in warm-water fishes

    Science.gov (United States)

    Lineages of hypervirulent Aeromonas hydrophila (vAh) are the cause of persistent outbreaks of motile Aeromonas septicemia in warm-water fishes worldwide. Over the last decade, this virulent lineage of A. hydrophila has resulted in annual losses of millions of tons of farmed carp and catfish in the P...

  10. Chikungunya virus outbreak expansion and microevolutionary events affecting epidemiology and epidemic potential

    Directory of Open Access Journals (Sweden)

    Powers AM

    2015-03-01

    Full Text Available Ann M PowersArboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USAAbstract: Chikungunya virus (CHIKV is a mosquito-borne virus that is associated with severe and prolonged arthralgia. Starting in 2004, CHIKV reemerged in a series of outbreaks along the east coast of Africa and on several islands of the Indian Ocean. Over the subsequent 10 years, the virus spread throughout the globe and caused over three million cases. Molecular characterization of the genomes over time revealed changes that were associated with changes in epidemiology and transmission patterns. Monitoring and exploitation of these changes may lead to better understanding of viral movement and potential options for prevention and control.Keywords: chikungunya, alphaviral evolution, molecular epidemiology, transmission, outbreaks

  11. 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.

  12. Epidemic outbreaks in growing scale-free networks with local structure

    Science.gov (United States)

    Ni, Shunjiang; Weng, Wenguo; Shen, Shifei; Fan, Weicheng

    2008-09-01

    The class of generative models has already attracted considerable interest from researchers in recent years and much expanded the original ideas described in BA model. Most of these models assume that only one node per time step joins the network. In this paper, we grow the network by adding n interconnected nodes as a local structure into the network at each time step with each new node emanating m new edges linking the node to the preexisting network by preferential attachment. This successfully generates key features observed in social networks. These include power-law degree distribution pk∼k, where μ=(n-1)/m is a tuning parameter defined as the modularity strength of the network, nontrivial clustering, assortative mixing, and modular structure. Moreover, all these features are dependent in a similar way on the parameter μ. We then study the susceptible-infected epidemics on this network with identical infectivity, and find that the initial epidemic behavior is governed by both of the infection scheme and the network structure, especially the modularity strength. The modularity of the network makes the spreading velocity much lower than that of the BA model. On the other hand, increasing the modularity strength will accelerate the propagation velocity.

  13. [Epidemics and pandemics in general practice. What can we learn from the swine flu (H1N1) and EHEC outbreak?].

    Science.gov (United States)

    Eisele, M; Hansen, H; Wagner, H-O; von Leitner, E; Pohontsch, N; Scherer, M

    2014-06-01

    As primary care givers with a coordinating function, general practitioners (GP) play a key role in dealing with epidemics and pandemics. As of yet, there are no studies in Germany describing the difficulties experienced by GPs in patient care during epidemics/pandemics. This study aimed at identifying the problem areas in GPs' patient care during the H1N1 and EHEC (enterohemorrhagic strain of Escherichia coli) outbreaks. With this information, recommendations for guaranteeing proper patient care during future epidemics/pandemics can be derived. In all, 12 qualitative, semi-structured, open guideline interviews with GPs in Hamburg and Lübeck were conducted, transcribed, and evaluated with qualitative content analysis. Five areas in ambulatory patient care were identified in which changes are needed from the primary care perspective: provision of information for GPs, workload, financing of epidemic-related measures, organization of the practices, care of those taken ill. The workload of GPs in particular can and should be reduced through successful, centralized information distribution during epidemics/pandemics. The GP's function as a coordinator should be supported and consolidated, in order to relieve the in-patient sector in cases of an epidemic/pandemic. Secured financing of epidemic-associated measures can help ensure patient care.

  14. 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

  15. Role of healthcare workers in early epidemic spread of Ebola: policy implications of prophylactic compared to reactive vaccination policy in outbreak prevention and control.

    Science.gov (United States)

    Coltart, Cordelia E M; Johnson, Anne M; Whitty, Christopher J M

    2015-10-19

    Ebola causes severe illness in humans and has epidemic potential. How to deploy vaccines most effectively is a central policy question since different strategies have implications for ideal vaccine profile. More than one vaccine may be needed. A vaccine optimised for prophylactic vaccination in high-risk areas but when the virus is not actively circulating should be safe, well tolerated, and provide long-lasting protection; a two- or three-dose strategy would be realistic. Conversely, a reactive vaccine deployed in an outbreak context for ring-vaccination strategies should have rapid onset of protection with one dose, but longevity of protection is less important. In initial cases, before an outbreak is recognised, healthcare workers (HCWs) are at particular risk of acquiring and transmitting infection, thus potentially augmenting early epidemics. We hypothesise that many early outbreak cases could be averted, or epidemics aborted, by prophylactic vaccination of HCWs. This paper explores the potential impact of prophylactic versus reactive vaccination strategies of HCWs in preventing early epidemic transmissions. To do this, we use the limited data available from Ebola epidemics (current and historic) to reconstruct transmission trees and illustrate the theoretical impact of these vaccination strategies. Our data suggest a substantial potential benefit of prophylactic versus reactive vaccination of HCWs in preventing early transmissions. We estimate that prophylactic vaccination with a coverage >99% and theoretical 100% efficacy could avert nearly two-thirds of cases studied; 75% coverage would still confer clear benefit (40% cases averted), but reactive vaccination would be of less value in the early epidemic. A prophylactic vaccination campaign for front-line HCWs is not a trivial undertaking; whether to prioritise long-lasting vaccines and provide prophylaxis to HCWs is a live policy question. Prophylactic vaccination is likely to have a greater impact on the

  16. An epidemic outbreak of nephrogenic systemic fibrosis in a Danish hospital

    International Nuclear Information System (INIS)

    Marckmann, Peter

    2008-01-01

    The nephrological department of Copenhagen University Hospital Herlev experienced an epidemic accumulation of patients developing nephrogenic systemic fibrosis in the period 2002-2006. Systematic studies of these patients revealed that they all had a gadodiamide-enhanced magnetic resonance examination prior to their symptoms, and that they all had severe renal insufficiency (chronic kidney disease stage 5) at the time of their exposure to gadodiamide. Besides exposure to gadodiamide, our analyses indicated that increasing cumulative gadodiamide exposure (i.e. repeated exposures), and higher serum concentrations of ionized calcium and phosphate were cofactors that raised the risk of developing nephrogenic systemic fibrosis. Higher cumulative gadodiamide exposure, higher prescribed erythropoietin dosage at exposure, and being hemodialysis patient were three factors associated with nephrogenic systemic fibrosis in its most severe form. Retrospective reviews of patients records and patient interviews revealed the large variability in symptoms and clinical course of nephrogenic systemic fibrosis, but also highlighted that the typical initial symptoms were symmetric swelling, discoloration and pain of lower legs, whereas the typical late symptoms of severely affected patients were skin thickening, stiffness, contractures, and debilitating disabilities. In conclusion, nephrogenic systemic fibrosis is a serious iatrogenic disease of patients with renal insufficiency caused by some Gd-containing contrast agents, in particular gadodiamide. Unfortunately, there is no proven curative treatment. It is therefore essential that future cases of nephrogenic systemic fibrosis are prevented

  17. 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.

  18. Epidemic Outbreak Surveillance (EOS)

    National Research Council Canada - National Science Library

    Scofield, Thomas C

    2005-01-01

    .... The funding supported the hiring of technical and administrative personnel necessary to carry out protocols to standardize methods of specimen collection and to optimize the processing of these specimens...

  19. Epidemic Outbreak Surveillance (EOS)

    National Research Council Canada - National Science Library

    Scofield, Thomas C

    2005-01-01

    ...) to provide the administrative, management, logistical, and programmatic services in collaboration with HQ, USAF/SGR in accordance with the statement of work and with tasks developed by the research...

  20. Data-Driven Risk Assessment from Small Scale Epidemics: Estimation and Model Choice for Spatio-Temporal Data with Application to a Classical Swine Fever Outbreak.

    Science.gov (United States)

    Gamado, Kokouvi; Marion, Glenn; Porphyre, Thibaud

    2017-01-01

    Livestock epidemics have the potential to give rise to significant economic, welfare, and social costs. Incursions of emerging and re-emerging pathogens may lead to small and repeated outbreaks. Analysis of the resulting data is statistically challenging but can inform disease preparedness reducing potential future losses. We present a framework for spatial risk assessment of disease incursions based on data from small localized historic outbreaks. We focus on between-farm spread of livestock pathogens and illustrate our methods by application to data on the small outbreak of Classical Swine Fever (CSF) that occurred in 2000 in East Anglia, UK. We apply models based on continuous time semi-Markov processes, using data-augmentation Markov Chain Monte Carlo techniques within a Bayesian framework to infer disease dynamics and detection from incompletely observed outbreaks. The spatial transmission kernel describing pathogen spread between farms, and the distribution of times between infection and detection, is estimated alongside unobserved exposure times. Our results demonstrate inference is reliable even for relatively small outbreaks when the data-generating model is known. However, associated risk assessments depend strongly on the form of the fitted transmission kernel. Therefore, for real applications, methods are needed to select the most appropriate model in light of the data. We assess standard Deviance Information Criteria (DIC) model selection tools and recently introduced latent residual methods of model assessment, in selecting the functional form of the spatial transmission kernel. These methods are applied to the CSF data, and tested in simulated scenarios which represent field data, but assume the data generation mechanism is known. Analysis of simulated scenarios shows that latent residual methods enable reliable selection of the transmission kernel even for small outbreaks whereas the DIC is less reliable. Moreover, compared with DIC, model choice

  1. A dynamic case definition is warranted for adequate notification in an extended epidemic setting: the Dutch Q fever outbreak 2007-2009 as exemplar.

    Science.gov (United States)

    Jaramillo-Gutierrez, G; Wegdam-Blans, M C; ter Schegget, R; Korbeeck, J M; van Aken, R; Bijlmer, H A; Tjhie, J H; Koopmans, M P

    2013-10-10

    Q fever is a notifiable disease in the Netherlands:laboratories are obliged to notify possible cases to the Municipal Health Services. These services then try to reconfirm cases with additional clinical and epidemiological data and provide anonymised reports to the national case register of notifiable diseases. Since the start of the 2007–2009 Dutch Q fever outbreak,notification rules remained unchanged, despite new laboratory insights and altered epidemiology. In this study, we retrospectively analysed how these changes influenced the proportion of laboratory-defined acute Q fever cases (confirmed, probable and possible)that were included in the national case register, during(2009) and after the outbreak (2010 and 2011).The number of laboratory-defined cases notified to the Municipal Health Services was 377 in 2009, 96 in 2010 and 50 in 2011. Of these, 186 (49.3%) in 2009, 12(12.5%) in 2010 and 9 (18.0%) in 2011 were confirmed as acute infection by laboratory interpretation. The proportion of laboratory-defined acute Q fever cases that was reconfirmed by the Municipal Health Services and that were included in the national case register decreased from 90% in 2009, to 22% and 24% in 2010 and 2011, respectively. The decrease was observed in all categories of cases, including those considered to be confirmed by laboratory criteria. Continued use ofa pre-outbreak case definition led to over-reporting of cases to the Municipal Health Services in the post-epidemic years. Therefore we recommend dynamic laboratory notification rules, by reviewing case definitions periodically in an ongoing epidemic, as in the Dutch Q fever outbreak.

  2. Review of a major epidemic of methicillin-resistant Staphylococcus aureus: The costs of screening and consequences of outbreak management

    NARCIS (Netherlands)

    A. van der Zee (Anneke); W. Hendriks; L.D. Roorda (Lieuwe); J.M. Ossewaarde (Jacobus); J. Buitenwerf (Johannes)

    2013-01-01

    textabstractBackground: A major outbreak of methicillin-resistant Staphylococcus aureus (MRSA) occurred in locations C and Z of our hospital and lasted for several years. It affected 1,230 patients and 153 personnel. Methods: Outbreak management was installed according to the Dutch "search and

  3. Discrimination and abuse experienced by general internists in Canada.

    Science.gov (United States)

    Cook, D J; Griffith, L E; Cohen, M; Guyatt, G H; O'Brien, B

    1995-10-01

    To identify the frequency of psychological and emotional abuse, gender discrimination, verbal sexual harassment, physical sexual harassment, physical assault, and homophobia experienced by general internists. Cross-sectional survey. Canadian general internal medicine practices. The overall response rate was 70.6% (984/1,393); the 501 respondents who classified themselves as general internists were studied. Three-fourths of the internists experienced psychological and emotional abuse at the hands of patients, and 38% of the women and 26% of the men experienced physical assault by patients. The majority of the female internists experienced gender discrimination by patients (67%) and by physician peers (56%). Forty-five percent of the women experienced verbal sexual harassment by patients, and 22% experienced physical sexual harassment by patients. The male internists experienced verbal sexual harassment from nurses slightly more often than the female internists did (19% vs 13%, p > 0.05). Verbal sexual harassment by male colleagues was reported by 35% of the female internists, and physical sexual harassment was reported by 11%. Approximately 40% of general internists reported homophobic remarks by both health care team members and patients. Abuse, discrimination, and homophobia are prevalent in the internal medicine workplace. A direct, progressive, multidisciplinary approach is necessary to label and address these problems.

  4. Estimating the reproductive number, total outbreak size, and reporting rates for Zika epidemics in South and Central America

    Directory of Open Access Journals (Sweden)

    Deborah P. Shutt

    2017-12-01

    Full Text Available As South and Central American countries prepare for increased birth defects from Zika virus outbreaks and plan for mitigation strategies to minimize ongoing and future outbreaks, understanding important characteristics of Zika outbreaks and how they vary across regions is a challenging and important problem. We developed a mathematical model for the 2015/2016 Zika virus outbreak dynamics in Colombia, El Salvador, and Suriname. We fit the model to publicly available data provided by the Pan American Health Organization, using Approximate Bayesian Computation to estimate parameter distributions and provide uncertainty quantification. The model indicated that a country-level analysis was not appropriate for Colombia. We then estimated the basic reproduction number to range between 4 and 6 for El Salvador and Suriname with a median of 4.3 and 5.3, respectively. We estimated the reporting rate to be around 16% in El Salvador and 18% in Suriname with estimated total outbreak sizes of 73,395 and 21,647 people, respectively. The uncertainty in parameter estimates highlights a need for research and data collection that will better constrain parameter ranges.

  5. Estimating the reproductive number, total outbreak size, and reporting rates for Zika epidemics in South and Central America.

    Science.gov (United States)

    Shutt, Deborah P; Manore, Carrie A; Pankavich, Stephen; Porter, Aaron T; Del Valle, Sara Y

    2017-12-01

    As South and Central American countries prepare for increased birth defects from Zika virus outbreaks and plan for mitigation strategies to minimize ongoing and future outbreaks, understanding important characteristics of Zika outbreaks and how they vary across regions is a challenging and important problem. We developed a mathematical model for the 2015/2016 Zika virus outbreak dynamics in Colombia, El Salvador, and Suriname. We fit the model to publicly available data provided by the Pan American Health Organization, using Approximate Bayesian Computation to estimate parameter distributions and provide uncertainty quantification. The model indicated that a country-level analysis was not appropriate for Colombia. We then estimated the basic reproduction number to range between 4 and 6 for El Salvador and Suriname with a median of 4.3 and 5.3, respectively. We estimated the reporting rate to be around 16% in El Salvador and 18% in Suriname with estimated total outbreak sizes of 73,395 and 21,647 people, respectively. The uncertainty in parameter estimates highlights a need for research and data collection that will better constrain parameter ranges. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Outbreak of vancomycin-resistant Enterococcus faecium in a haematology unit: risk factor assessment and successful control of the epidemic

    NARCIS (Netherlands)

    Timmers, Gert Jan; van der Zwet, Wil C.; Simoons-Smit, Ina M.; Savelkoul, Paul H. M.; Meester, Helena H. M.; Vandenbroucke-Grauls, Christina M. J. E.; Huijgens, Peter C.

    2002-01-01

    We describe an outbreak of vancomycin-resistant Enterococcus faecium (VRE) on the haematology ward of a Dutch university hospital. After the occurrence of three consecutive cases of bacteraemia with VRE, strains were genotyped and found to be identical. During the next 4 months an intensive

  7. Measles Epidemics Among Children in Vietnam: Genomic Characterization of Virus Responsible for Measles Outbreak in Ho Chi Minh City, 2014

    Directory of Open Access Journals (Sweden)

    Van H. Pham

    2014-12-01

    Conclusions: Measles viruses responsible for outbreaks in Southern Vietnam belonged to a genotype D8 variant group which had unique amino acid sequences in the N gene. Our report provides important genomic information about the virus for measles elimination in Southeast Asia.

  8. An epidemiological investigation of the early phase of the porcine epidemic diarrhea (PED) outbreak in Canadian swine herds in 2014: A case-control study.

    Science.gov (United States)

    Perri, Amanda M; Poljak, Zvonimir; Dewey, Cate; Harding, John C S; O'Sullivan, Terri L

    2018-02-01

    The first case of porcine epidemic diarrhea (PED) in Canada was diagnosed in January 2014 in Ontario, approximately 9 months after PED emerged in the United States. An early investigation of the Canadian outbreak suspected that the probable source of the virus was contaminated feed. The objective of this study was to evaluate the role of feed and other possible factors in the early phase of the PED outbreak in Canadian swine herds. The study period of interest for this case-control study was January 22nd to March 1st, 2014. A case herd was defined as a swine herd with a confirmed positive laboratory diagnostic test (RT-PCR) results for PED virus, along with pigs exhibiting typical clinical signs at the herd level during the study period. A questionnaire was administered to participating producers from the 22 Canadian swine herds enrolled (n = 9 case and n = 13 control herds). Case herd producers were asked to provide information from the initial day of onset of clinical signs and 30 days prior to that day. Control herds were matched to a case herd on the basis of province, herd type and approximate size. The period of interest for a control herd was matched to the initial day of clinical signs of PED for the case herd, along with the 30 days prior to this day. The questionnaire questions focused on herd demographics, biosecurity protocols, live animal movements onto and off sites, deadstock movements, feed and people movements for both the case and control herds. The questionnaire for control herds were based on their matched case's period of interest, and together with case herds formed a matched stratum. Multivariable exact conditional logistic regression and mixed multivariable logistic regression models, with the matched stratum as a random effect, were used to assess the association between various risk factors and the odds of PED introduction into a herd. After adjusting for biosecurity practices, the odds of a PED occurrence was 38.1 (95% CI: 2

  9. 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

  10. Theorizing "Big Events" as a potential risk environment for drug use, drug-related harm and HIV epidemic outbreaks.

    Science.gov (United States)

    Friedman, Samuel R; Rossi, Diana; Braine, Naomi

    2009-05-01

    Political-economic transitions in the Soviet Union, Indonesia, and China, but not the Philippines, were followed by HIV epidemics among drug users. Wars also may sometimes increase HIV risk. Based on similarities in some of the causal pathways through which wars and transitions can affect HIV risk, we use the term "Big Events" to include both. We first critique several prior epidemiological models of Big Events as inadequately incorporating social agency and as somewhat imprecise and over-generalizing in their sociology. We then suggest a model using the following concepts: first, event-specific HIV transmission probabilities are functions of (a) the probability that partners are infection-discordant; (b) the infection-susceptibility of the uninfected partner; (c) the infectivity of the infected--as well as (d) the behaviours engaged in. These probabilities depend on the distributions of HIV and other variables in populations. Sexual or injection events incorporate risk behaviours and are embedded in sexual and injection partnership patterns and community networks, which in turn are shaped by the content of normative regulation in communities. Wars and transitions can change socio-economic variables that can sometimes precipitate increases in the numbers of people who engage in high-risk drug and sexual networks and behaviours and in the riskiness of what they do. These variables that Big Events affect may include population displacement; economic difficulties and policies; police corruption, repressiveness, and failure to preserve order; health services; migration; social movements; gender roles; and inter-communal violence--which, in turn, affect normative regulation, youth alienation, networks and behaviours. As part of these pathways, autonomous action by neighbourhood residents, teenagers, drug users and sex workers to maintain their economic welfare, health or happiness may affect many of these variables or otherwise mediate whether HIV epidemics follow

  11. 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 ...

  12. [Precision medicine : a required approach for the general internist].

    Science.gov (United States)

    Waeber, Gérard; Cornuz, Jacques; Gaspoz, Jean-Michel; Guessous, Idris; Mooser, Vincent; Perrier, Arnaud; Simonet, Martine Louis

    2017-01-18

    The general internist cannot be a passive bystander of the anticipated medical revolution induced by precision medicine. This latter aims to improve the predictive and/or clinical course of an individual by integrating all biological, genetic, environmental, phenotypic and psychosocial knowledge of a person. In this article, national and international initiatives in the field of precision medicine are discussed as well as the potential financial, ethical and limitations of personalized medicine. The question is not to know if precision medicine will be part of everyday life but rather to integrate early the general internist in multidisciplinary teams to ensure optimal information and shared-decision process with patients and individuals.

  13. Assessment of African Swine Fever Diagnostic Techniques as a Response to the Epidemic Outbreaks in Eastern European Union Countries: How To Improve Surveillance and Control Programs.

    Science.gov (United States)

    Gallardo, C; Nieto, R; Soler, A; Pelayo, V; Fernández-Pinero, J; Markowska-Daniel, I; Pridotkas, G; Nurmoja, I; Granta, R; Simón, A; Pérez, C; Martín, E; Fernández-Pacheco, P; Arias, M

    2015-08-01

    This study represents a complete comparative analysis of the most widely used African swine fever (ASF) diagnostic techniques in the European Union (EU) using field and experimental samples from animals infected with genotype II ASF virus (ASFV) isolates circulating in Europe. To detect ASFV, three different PCRs were evaluated in parallel using 785 field and experimental samples. The results showed almost perfect agreement between the Universal ProbeLibrary (UPL-PCR) and the real-time (κ = 0.94 [95% confidence interval {CI}, 0.91 to 0.97]) and conventional (κ = 0.88 [95% CI, 0.83 to 0.92]) World Organisation for Animal Health (OIE)-prescribed PCRs. The UPL-PCR had greater diagnostic sensitivity for detecting survivors and allows earlier detection of the disease. Compared to the commercial antigen enzyme-linked immunosorbent assay (ELISA), good-to-moderate agreement (κ = 0.67 [95% CI, 0.58 to 0.76]) was obtained, with a sensitivity of 77.2% in the commercial test. For ASF antibody detection, five serological methods were tested, including three commercial ELISAs, the OIE-ELISA, and the confirmatory immunoperoxidase test (IPT). Greater sensitivity was obtained with the IPT than with the ELISAs, since the IPT was able to detect ASF antibodies at an earlier point in the serological response, when few antibodies are present. The analysis of the exudate tissues from dead wild boars showed that IPT might be a useful serological tool for determining whether or not animals had been exposed to virus infection, regardless of whether antibodies were present. In conclusion, the UPL-PCR in combination with the IPT was the most trustworthy method for detecting ASF during the epidemic outbreaks affecting EU countries in 2014. The use of the most appropriate diagnostic tools is critical when implementing effective control programs. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  14. Assessment of African Swine Fever Diagnostic Techniques as a Response to the Epidemic Outbreaks in Eastern European Union Countries: How To Improve Surveillance and Control Programs

    Science.gov (United States)

    Nieto, R.; Soler, A.; Pelayo, V.; Fernández-Pinero, J.; Markowska-Daniel, I.; Pridotkas, G.; Nurmoja, I.; Granta, R.; Simón, A.; Pérez, C.; Martín, E.; Fernández-Pacheco, P.; Arias, M.

    2015-01-01

    This study represents a complete comparative analysis of the most widely used African swine fever (ASF) diagnostic techniques in the European Union (EU) using field and experimental samples from animals infected with genotype II ASF virus (ASFV) isolates circulating in Europe. To detect ASFV, three different PCRs were evaluated in parallel using 785 field and experimental samples. The results showed almost perfect agreement between the Universal ProbeLibrary (UPL-PCR) and the real-time (κ = 0.94 [95% confidence interval {CI}, 0.91 to 0.97]) and conventional (κ = 0.88 [95% CI, 0.83 to 0.92]) World Organisation for Animal Health (OIE)-prescribed PCRs. The UPL-PCR had greater diagnostic sensitivity for detecting survivors and allows earlier detection of the disease. Compared to the commercial antigen enzyme-linked immunosorbent assay (ELISA), good-to-moderate agreement (κ = 0.67 [95% CI, 0.58 to 0.76]) was obtained, with a sensitivity of 77.2% in the commercial test. For ASF antibody detection, five serological methods were tested, including three commercial ELISAs, the OIE-ELISA, and the confirmatory immunoperoxidase test (IPT). Greater sensitivity was obtained with the IPT than with the ELISAs, since the IPT was able to detect ASF antibodies at an earlier point in the serological response, when few antibodies are present. The analysis of the exudate tissues from dead wild boars showed that IPT might be a useful serological tool for determining whether or not animals had been exposed to virus infection, regardless of whether antibodies were present. In conclusion, the UPL-PCR in combination with the IPT was the most trustworthy method for detecting ASF during the epidemic outbreaks affecting EU countries in 2014. The use of the most appropriate diagnostic tools is critical when implementing effective control programs. PMID:26041901

  15. 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.

  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. Perceptions of conflict of interest: surgeons, internists, and learners compared.

    Science.gov (United States)

    de Gara, Christopher J; Rennick, Kim C; Hanson, John

    2013-05-01

    Making a conflict of interest declaration is now mandatory at continuing medical education CME accredited events. However, these declarations tend to be largely perfunctory. This study sought to better understand physician perceptions surrounding conflict of interest. The same PowerPoint (Microsoft, Canada) presentation (http://www.youtube.com/watch?v=mQSOvch7Yg0&feature=g-upl) was delivered at multiple University of Alberta and Royal College CME-accredited events to surgeons, internists, and learners. After each talk, the audience was invited to complete an anonymous, pretested, and standardized 5-point Likert scale (strongly disagree to strongly agree) questionnaire. A total of 136 surveys were analyzed from 31 surgeons, 49 internists, and 56 learners. In response to the question regarding whether by simply making a declaration, the speaker had provided adequate proof of any conflicts of interest, 71% of surgeons thought so, whereas only 35% of internists and 39% of learners agreed or strongly agreed (P = .004). Further probing this theme, the audience was asked whether a speaker must declare fees or monies received from industry for consulting, speaking, and research support. Once again there was a variance of opinion, with only 43% of surgeons agreeing or strongly agreeing with this statement; yet, 80% of internists and 71% of learners felt that such a declaration was necessary (P = .013). On the topic of believability (a speaker declaration makes him or her and the presentation more credible), the 3 groups were less polarized: 50% of surgeons, 41% of internists, and 52% of learners (P = .2) felt that this was the case. Although two thirds of surgeons (68%) and learners (66%) and nearly all internists (84%) felt that industry-sponsored research was biased, these differences were not significant (P = .2). Even when they are completely open and honest, conflict of interest declarations do not negate the biases inherent in a speaker's talk or research when it is

  18. An epidemic outbreak of cryptosporidiosis

    DEFF Research Database (Denmark)

    Mølbak, Kåre; Højlyng, Niels; Ingholt, Liselotte

    1990-01-01

    In the first year of a prospective community study of childhood diarrhea conducted in a semiurban area in the capital of Guinea Bissau, Cryptosporidium sp. was found in 73 (6.0%) of 1216 episodes of diarrhea. The parasite was the second most prevalent intestinal parasite, and the only one...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Impact of the Ebola outbreak on routine immunization in western area, Sierra Leone - a field survey from an Ebola epidemic area

    Directory of Open Access Journals (Sweden)

    Xiaojin Sun

    2017-04-01

    Full Text Available Abstract Background Since March 2014, the Ebola Virus Disease (EVD outbreak in West Africa disrupted health care systems - especially in Guinea, Liberia and Sierra Leone – with a consequential stress on the area’s routine immunization programs. To address perceived decreased vaccination coverage, Sierra Leone conducted a catch-up vaccination campaign during 24–27 April 2015. We conducted a vaccination coverage survey and report coverage estimates surrounding the time of the EVD outbreak and the catch-up campaign. Methods We selected 3 villages from each of 3 communities and obtained dates of birth and dates of vaccination with measles vaccine (MV and the 3rd dose of Pentavalent vaccine (Pentavalent3 of all children under 4 years of age in the 9 selected villages. Vaccination data were obtained from parent-held health cards. We calculated the children’s MV and Pentavalent3 coverage rates at 3 time points, 1 August 2014, 1 April 2015, and 1 May 2015, representing coverage rates before the EVD outbreak, during the EVD outbreak, and after the Maternal and Child Health Week (MCHW catch-up campaign. Results The final sample size was 168 children. MV coverage among age-eligible children was 71.3% (95% confidence interval [CI]: 62.1% - 80.4% and 45.7% (95% CI: 29.2% - 62.2% before and during the outbreak of EVD, respectively, and was 56.8% (95% CI: 40.8% - 72.7% after the campaign. Pentavalent3 coverage among age-eligible children was 79.8% (95% CI: 72.6% - 87.0% and 40.0% (95% CI: 22.5% - 57.5% before and during the outbreak of EVD, and was 56.4% (95% CI: 39.1% - 73.4% after the campaign. Conclusions Coverage levels of MV and Pentavalent3 were low before the EVD outbreak and decreased further during the outbreak. Although the MCHW catch-up campaign increased coverage levels, coverage remained below pre-outbreak levels. High-quality supplementary immunization activities should be conducted and routine immunization should be strengthened to

  6. Science You Can Use Bulletin: From death comes life: Recovery and revolution in the wake of epidemic outbreaks of mountain pine beetle

    Science.gov (United States)

    Karl Malcolm; Chuck Rhoades; Michael Battaglia; Paula Fornwalt; Rob Hubbard; Kelly Elder; Byron Collins

    2012-01-01

    Changing climatic conditions and an abundance of dense, mature pine forests have helped to spur an epidemic of mountain pine beetles larger than any in recorded history. Millions of forested acres have been heavily impacted and have experienced extreme rates of tree mortality. This has raised concerns among many people that the death, desiccation, and decomposition of...

  7. Genomic epidemiology of the haitian cholera outbreak: a single introduction followed by rapid, extensive, and continued spread characterized the onset of the epidemic

    DEFF Research Database (Denmark)

    Eppinger, Mark; Pearson, Talima; Koenig, Sara S. K.

    2014-01-01

    In this genomic epidemiology study, we have applied high-resolution whole-genome-based sequence typing methodologies on a comprehensive set of genome sequences that have become available in the aftermath of the Haitian cholera epidemic. These sequence resources enabled us to reassess the degree...

  8. Performance of clinical signs in poultry for the detection of outbreaks during the avian influenza A (H7N7) epidemic in the Netherlands in 2003

    NARCIS (Netherlands)

    Elbers, A.R.W.; Koch, G.; Bouma, A.

    2005-01-01

    The aim of this study was to make an inventory of the clinical signs of high-pathogenicity avian influenza (HPAI), to facilitate the development of an operational syndrome-reporting system (SRS) in The Netherlands as an early warning system for HPAI outbreaks. A total of 537 poultry flocks (240

  9. Performance of clinical signs in poultry for the detection of outbreaks during the avian influenza A (H7N7) epidemic in The Netherlands in 2003.

    Science.gov (United States)

    Elbers, Armin R W; Koch, Guus; Bouma, Annemarie

    2005-06-01

    The aim of this study was to make an inventory of the clinical signs of high-pathogenicity avian influenza (HPAI), to facilitate the development of an operational syndrome-reporting system (SRS) in The Netherlands as an early warning system for HPAI outbreaks. A total of 537 poultry flocks (240 infected and 297 non-infected) with a clinical suspicion of an infection with HPAI virus were investigated with respect to the clinical signs observed. Standardized reports were analysed with respect to observed clinical signs in the flocks. Various poultry types were distinguished. In infected commercial flocks with egg-producing chickens, the presence of increased mortality, apathy, coughing, reduction in normal vocalization, or pale eggs appeared to be overall the most sensitive indicators to detect a HPAI outbreak, matching a sensitivity of 99% with a specificity of 23%. In infected turkey flocks, the presence of apathy, decreased growth performance, reduction of normal vocalization, swollen sinuses, yawning, huddling, mucosal production from the beak, or lying down with an extended neck appeared to be overall the most sensitive indicators to detect a HPAI outbreak, matching a sensitivity of 100% with a specificity of 79%. In infected backyard/hobby flocks, increased mortality or swollen head appeared to be overall the most sensitive indicators of a HPAI outbreak, matching a sensitivity of 100% with a specificity of 26%. These results indicate that there is a solid basis for the choice of using increased mortality in the operational SRS in The Netherlands as an early warning system for HPAI outbreaks. The presence of apathy, specifically for turkeys, should be added to the SRS as an indicator.

  10. Cholera in the Portuguese Region of Alto Minho in the Second Half of the Nineteenth Century: Epidemic Outbreaks, Treatment and Behaviours

    Directory of Open Access Journals (Sweden)

    Alexandra Esteves

    2010-11-01

    Full Text Available The aim of our work is to analyse the impact of cholera outbreaks that took place in Alto Minho, a region in the North of Portugal, in a century in which, due to several developments, distances became shorter and people from different parts of the globe became closer, and thus explaining the spreading of a disease that manifests itself quickly and evolves rapidly. We also intend to evaluate the effect of the measures undertaken by administrative and sanitary authorities and to verify the alterations in the daily life of the affected communities as far as economic activities, organization, cleanness and hygiene in the public venue are concerned, emphasizing on the temporary suspension of the relations with the neighbouring region of Galiza equally affected by numerous cholera outbreaks.

  11. 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.

  12. 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

  13. (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.

  14. Understanding apparently non-exponential outbreaks Comment on "Mathematical models to characterize early epidemic growth: A review" by Gerardo Chowell et al.

    Science.gov (United States)

    Champredon, David; Earn, David J. D.

    2016-09-01

    Mechanistic mathematical modelling of the population dynamics of infectious diseases has advanced tremendously over the last few decades [1-6]. Transmission models have been applied to countless diseases of public health importance, including seasonal and pandemic influenza [7], childhood diseases such as measles [8,9] and whooping cough [10], vector transmitted diseases such as malaria [11] and dengue [12], and waterborne diseases such as cholera [13-15]. Much attention in recent years has been directed to emergent diseases such as SARS [16], new subtypes of influenza [17,18], Ebola [19,20], and Zika [21], for which an understanding of early outbreak dynamics is critical.

  15. Effects of operational decisions on the diffusion of epidemic disease: A system dynamics modeling of the MERS-CoV outbreak in South Korea.

    Science.gov (United States)

    Shin, Nina; Kwag, Taewoo; Park, Sangwook; Kim, Yon Hui

    2017-05-21

    We evaluated the nosocomial outbreak of Middle East Respiratory Syndrome (MERS) Coronavirus (CoV) in the Republic of Korea, 2015, from a healthcare operations management perspective. Establishment of healthcare policy in South Korea provides patients' freedom to select and visit multiple hospitals. Current policy enforces hospitals preference for multi-patient rooms to single-patient rooms, to lower financial burden. Existing healthcare systems tragically contributed to 186 MERS outbreak cases, starting from single "index patient" into three generations of secondary infections. By developing a macro-level health system dynamics model, we provide empirical knowledge to examining the case from both operational and financial perspectives. In our simulation, under base infectivity scenario, high emergency room occupancy circumstance contributed to an estimated average of 101 (917%) more infected patients, compared to when in low occupancy circumstance. Economic patient room design showed an estimated 702% increase in the number of infected patients, despite the overall 98% savings in total expected costs compared to optimal room design. This study provides first time, system dynamics model, performance measurements from an operational perspective. Importantly, the intent of this study was to provide evidence to motivate public, private, and government healthcare administrators' recognition of current shortcomings, to optimize performance as a whole system, rather than mere individual aspects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. 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

  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. Fitting outbreak models to data from many small norovirus outbreaks

    Directory of Open Access Journals (Sweden)

    Eamon B. O’Dea

    2014-03-01

    Full Text Available Infectious disease often occurs in small, independent outbreaks in populations with varying characteristics. Each outbreak by itself may provide too little information for accurate estimation of epidemic model parameters. Here we show that using standard stochastic epidemic models for each outbreak and allowing parameters to vary between outbreaks according to a linear predictor leads to a generalized linear model that accurately estimates parameters from many small and diverse outbreaks. By estimating initial growth rates in addition to transmission rates, we are able to characterize variation in numbers of initially susceptible individuals or contact patterns between outbreaks. With simulation, we find that the estimates are fairly robust to the data being collected at discrete intervals and imputation of about half of all infectious periods. We apply the method by fitting data from 75 norovirus outbreaks in health-care settings. Our baseline regression estimates are 0.0037 transmissions per infective-susceptible day, an initial growth rate of 0.27 transmissions per infective day, and a symptomatic period of 3.35 days. Outbreaks in long-term-care facilities had significantly higher transmission and initial growth rates than outbreaks in hospitals.

  19. Attitudes and Practices Among Internists Concerning Genetic Testing

    Science.gov (United States)

    Chung, Wendy; Marder, Karen; Shanmugham, Anita; Chin, Lisa J.; Stark, Meredith; Leu, Cheng-Shiun; Appelbaum, Paul S.

    2012-01-01

    Many questions remain concerning whether, when, and how physicians order genetic tests, and what factors are involved in their decisions. We surveyed 220 internists from two academic medical centers about their utilization of genetic testing. Rates of genetic utilizations varied widely by disease. Respondents were most likely to have ordered tests for Factor V Leiden (16.8%), followed by Breast/Ovarian Cancer (15.0%). In the past 6 months, 65% had counseled patients on genetic issues, 44% had ordered genetic tests, 38.5% had referred patients to a genetic counselor or geneticist, and 27.5% had received ads from commercial labs for genetic testing. Only 4.5% had tried to hide or disguise genetic information, and genetic discrimination. Only 53.4% knew of a geneticist/genetic counselor to whom to refer patients. Most rated their knowledge as very/somewhat poor concerning genetics (73.7%) and guidelines for genetic testing (87.1%). Most felt needs for more training on when to order tests (79%), and how to counsel patients (82%), interpret results (77.3%), and maintain privacy (80.6%). Physicians were more likely to have ordered a genetic test if patients inquired about genetic testing (pgenetic counselor to whom to refer patients (pgenetic counselor in the past 6 months, had more comfort counseling patients about testing (pgenetics, larger practices (pgenetic discrimination (pgenetic test was associated with patients inquiring about testing, having referred patients to a geneticist/genetic counselor and knowing how to order tests., These data suggest that physicians recognize their knowledge deficits, and are interested in training. These findings have important implications for future medical practice, research, and education. PMID:22585186

  20. What is the role of general internists in the tertiary or academic setting?

    Science.gov (United States)

    Tanriover, Mine Durusu; Rigby, Shirley; van Hulsteijn, L Harry; Ferreira, Faustino; Oliveira, Narcisso; Schumm-Draeger, Petra-Maria; Weidanz, Frauke; Kramer, Mark H H

    2015-01-01

    The changing demography of European populations mandates a vital role for internists in caring for patients in each level of healthcare. Internists in the tertiary or academic setting are highly ranked in terms of their responsibilities: they are clinicians, educators, researchers, role models, mentors and administrators. Contrary to the highly focused approach of sub-specialties, general internists working in academic settings can ensure that coordinated care is delivered in the most cost-conscious and efficient way. Moreover, internal medicine is one of the most appropriate specialties in which to teach clinical reasoning skills, decision-making and analytical thinking, as well as evidence based, patient oriented medicine. Internists deal with challenging patients of the new millennium with a high burden of chronic diseases and polypharmacy; practice personalised medicine with a wide scientific background and so they are the perfect fit to establish and implement new tools for scientific research. In conclusion, internal medicine is developing a new identity as a specialty in its own right. The European Federation of Internal Medicine supports the concept of academic internists and calls upon the member countries to construct academic (general) internal medicine departments in their respective countries. As 'internal medicine is the cornerstone of every national healthcare system', academic (general) internal medicine should strive to be the cornerstone of every integrated, patient-centred, modern medical care and training system. Copyright © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  1. Mitigating Infectious Disease Outbreaks

    Science.gov (United States)

    Davey, Victoria

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

  2. Brote epidémico por Salmonella richmond en Castellón, España Epidemic outbreak caused by Salmonella richmond in Castellón, España

    Directory of Open Access Journals (Sweden)

    María Rosario Pac Sa

    1998-02-01

    Full Text Available Se efectuó un estudio de casos y controles para investigar un brote de gastroenteritis aguda declarado en un destacamento militar situado en una zona rural de Castellón, España. El objetivo del estudio fue conocer las causas del brote y adoptar medidas de control. En total se incluyó a 135 hombres de los 153 que componían dicho destacamento. Entre el 9 y el 11 de agosto de 1993 se notificaron 45 casos, cuya media de edad fue de 19,2 ± 1,5 años. La tasa de ataque fue de 33,3%. En el cuadro clínico predominaron diarreas (76%, vómitos (67%, náuseas (67% y dolor abdominal (28%. La mediana de la duración de los síntomas fue un día y la del período de incubación, 33 horas. Solo se hospitalizó a un paciente y la evolución de todos los afectados fue buena. En cinco de 14 coprocultivos realizados se aisló Salmonella richmond (6,7:y:1,2. También se detectó una asociación entre el consumo de agua de una acequia, que discurría próxima al campamento, y la enfermedad. Mediante un modelo de regresión logística se constató que el consumo del agua de esta fuente permaneció asociado con el estado de caso después de ajustar la asociación según la edad y el consumo de distintos alimentos (razón de posibilidades = 96,5; intervalo de confianza de 95%: 11,4 ­ 814,4. El riesgo de padecer la enfermedad aumentó con la cantidad de agua ingerida (prueba de tendencia X² = 65,4; P A case-control study was carried out to investigate an outbreak of acute gastroenteritis among a military detachment stationed in a rural area of Castellón, España. The purpose of the study was to determine the causes of the outbreak and develop control measures. Of the 153 men in the detachment, 135 were included in the study. Between 9 and 11 August 1993, 45 cases were reported; the patients' average age was 19.2 ± 1.5 years. The attack rate was 33.3%. The clinical picture was dominated by the following symptoms: diarrhea (76%, vomiting (67%, nausea (67%, and

  3. Context analysis for epidemic control in the Netherlands

    NARCIS (Netherlands)

    Huizer, Y.L.; Kraaij-Dirkzwager, M.M.; Timen, A.; Schuitmaker-Warnaar, T.J.; van Steenbergen, J.E.

    2014-01-01

    When epidemics occur, experts advise the Ministries on effective control measures. There is uncertainty in the translation of epidemiological evidence into effective outbreak management interventions, due to contradicatory problem perspectives, diverse interests and time pressure. Several models

  4. 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.

  5. 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.

  6. 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 ...

  7. A history of the INTERNIST-1 and Quick Medical Reference (QMR) computer-assisted diagnosis projects, with lessons learned.

    Science.gov (United States)

    Miller, R A

    2010-01-01

    The INTERNIST-1/Quick Medical Reference (QMR) diagnostic decision support project spans four decades, from 1971-onward. This paper describes the history of the project and details insights gained of relevance to the general clinical and informatics communities.

  8. [Diabetic foot syndrome from the perspective of internist educated in podiatry].

    Science.gov (United States)

    Jirkovská, Alexandra

    2016-01-01

    Podiatry is the science dealing with the diagnostics and treatment of the foot and ankle and associated tissues and structures by all appropriate methods and also with the local manifestation of the overall processes in this area. Diabetic foot disease is defined as infection, ulceration or destruction of tissues of the foot associated with neuropathy and/or peripheral artery disease in the lower extremity of people with diabetes according to the latest edition of the International Consensus. Successful treatment and prevention of diabetic foot syndrome depends on a holistic approach, in which it is seen as part of the multiple organ involvement. Teamwork of series of experts is therefore necessary. Internist with diabetes and podiatric education plays a key role in this team in particular, when control diabetes and in the prevention and treatment of co-morbidities, in the diagnosis of malnutrition and in the nutritional therapy and in the early diagnosis and effective treatment of infections. Last but not least, internist in collaboration with other professionals works when treatment of lower limb ischemia, suitable offloading of the ulcer and topical therapy and in the prevention of ulcers. Recurrent ulcerations are the major problem in podiatry and it can occur in up to 40% of patients in the first year after healing. Follow-up of patients with diabetic foot syndrome by experienced internist can help reduce the serious consequences, including amputation and cardiovascular mortality.Key words: diabetic foot - internal medicine - podiatry.

  9. [Practice of Internal Medicine in Latin America. Role of the internist].

    Science.gov (United States)

    Varela, Nacor

    2002-01-01

    This article explores the causes of the crisis in the role of internists. As in the United States, the progressive specialization of internists lead to a dehumanized, expensive and technical practice of medicine. Aiming to better incomes and prestige, more than 60% of internists practice as specialists. Primary care physicians, with a very low rate of problem solving, cover 75% of consultations. Specialists, with increasing costs, cover the rest of consultations. Patients, medical schools and health organizations are claiming the return of the general internal medicine specialist. To increase the interest for general internal medicine, several strategies are applicable. Medical students interested in general internal medicine could receive a focused training, provided by these specialists. A greater emphasis should be put on primary care. More independent, secondary care diagnostic and treatment centers, should be created. Continuous medical education should be done with periodical re certification of physicians. The public health system should increase its wages and the generalist view should be maintained by physicians when practicing at their private offices.

  10. 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.

  11. Ebola Viral Hemorrhagic Disease Outbreak in West Africa- Lessons ...

    African Journals Online (AJOL)

    ... to contain the Ebola epidemic. Key words: Ebola, viral hemorrhagic fever, West Africa, lessons, Uganda .... the corresponding surveillance systems for detecting priority diseases. ... A major outbreak of Yellow Fe- ver was reported in five ...

  12. Epidemic Spreading with Heterogeneous Awareness on Human Networks

    Directory of Open Access Journals (Sweden)

    Yanling Lu

    2017-01-01

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

  13. 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.

  14. 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.

  15. 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.

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

    International Nuclear Information System (INIS)

    Yang, Han-Xin; Wu, Zhi-Xi

    2014-01-01

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

  17. A national comparison of burnout and work-life balance among internal medicine hospitalists and outpatient general internists.

    Science.gov (United States)

    Roberts, Daniel L; Shanafelt, Tait D; Dyrbye, Liselotte N; West, Colin P

    2014-03-01

    General internists suffer higher rates of burnout and lower satisfaction with work-life balance than most specialties, but the impact of inpatient vs outpatient practice location is unclear. Physicians in the American Medical Association Physician Masterfile were previously surveyed about burnout, depression, suicidal ideation, quality of life, fatigue, work-life balance, career plans, and health behaviors. We extracted and compared data for these variables for the 130 internal medicine hospitalists and 448 outpatient general internists who participated. Analyses were adjusted for age, sex, hours worked, and practice setting. There were 52.3% of the hospitalists and 54.5% of the outpatient internists affected by burnout (P = 0.86). High scores on the emotional exhaustion subscale (43.8% vs 48.1%, P = 0.71) and on the depersonalization subscale (42.3% vs 32.7%, P = 0.17) were common but similar in frequency in the 2 groups. Hospitalists were more likely to score low on the personal accomplishment subscale (20.3% vs 9.6%, P = 0.04). There were no differences in symptoms of depression (40.3% for hospitalists vs 40.0% for outpatient internists, P = 0.73) or recent suicidality (9.2% vs 5.8%, P = 0.15). Rates of reported recent work-home conflict were similar (48.4% vs 41.3%, P = 0.64), but hospitalists were more likely to agree that their work schedule leaves enough time for their personal life and family (50.0% vs 42.0%, P = 0.007). Burnout was common among both hospitalists and outpatient general internists, although hospitalists were more satisfied with work-life balance. A better understanding of the causes of distress and identification of solutions for all internists is needed. © 2014 Society of Hospital Medicine.

  18. Does an in-house internist at a GP practice result in reduced referrals to hospital-based specialist care?

    Science.gov (United States)

    Quanjel, Tessa C C; Winkens, Anne; Spreeuwenberg, Marieke D; Struijs, Jeroen N; Winkens, Ron A G; Baan, Caroline A; Ruwaard, Dirk

    2018-03-01

    Consistent evidence on the effects of specialist services in the primary care setting is lacking. Therefore, this study evaluated the effects of an in-house internist at a GP practice on the number of referrals to specialist care in the hospital setting. Additionally, the involved GPs and internist were asked to share their experiences with the intervention. A retrospective interrupted times series study. Two multidisciplinary general practitioner (GP) practices. An internist provided in-house patient consultations in two GP practices and participated in the multidisciplinary meetings. The referral data extracted from the electronic medical record system of the GP practices, including all referral letters from the GPs to specialist care in the hospital setting. The number of referrals to internal medicine in the hospital setting. This study used an autoregressive integrated moving average model to estimate the effect of the intervention taking account of a time trend and autocorrelation among the observations, comparing the pre-intervention period with the intervention period. It was found that the referrals to internal medicine did not statistically significant decrease during the intervention period. This small explorative study did not find any clues to support that an in-house internist at a primary care setting results in a decrease of referrals to internal medicine in the hospital setting. Key Points An in-house internist at a primary care setting did not result in a significant decrease of referrals to specialist care in the hospital setting. The GPs and internist experience a learning-effect, i.e. an increase of knowledge about internal medicine issues.

  19. Canine distemper outbreak in rhesus monkeys, China.

    Science.gov (United States)

    Qiu, Wei; Zheng, Ying; Zhang, Shoufeng; Fan, Quanshui; Liu, Hua; Zhang, Fuqiang; Wang, Wei; Liao, Guoyang; Hu, Rongliang

    2011-08-01

    Since 2006, canine distemper outbreaks have occurred in rhesus monkeys at a breeding farm in Guangxi, People's Republic of China. Approximately 10,000 animals were infected (25%-60% disease incidence); 5%-30% of infected animals died. The epidemic was controlled by vaccination. Amino acid sequence analysis of the virus indicated a unique strain.

  20. Canine Distemper Outbreak in Rhesus Monkeys, China

    Science.gov (United States)

    Qiu, Wei; Zheng, Ying; Zhang, Shoufeng; Fan, Quanshui; Liu, Hua; Zhang, Fuqiang; Wang, Wei; Liao, Guoyang

    2011-01-01

    Since 2006, canine distemper outbreaks have occurred in rhesus monkeys at a breeding farm in Guangxi, People’s Republic of China. Approximately 10,000 animals were infected (25%–60% disease incidence); 5%–30% of infected animals died. The epidemic was controlled by vaccination. Amino acid sequence analysis of the virus indicated a unique strain. PMID:21801646

  1. Severe Dengue Fever Outbreak in Taiwan.

    Science.gov (United States)

    Wang, Sheng-Fan; Wang, Wen-Hung; Chang, Ko; Chen, Yen-Hsu; Tseng, Sung-Pin; Yen, Chia-Hung; Wu, Deng-Chyang; Chen, Yi-Ming Arthur

    2016-01-01

    Dengue fever (DF) is a vector-borne disease caused by dengue viruses (DENVs). Epidemic dengue occurs intermittently in Taiwan. In 2014, Taiwan experienced its largest DF outbreak. There were 15,732 DF cases reported. There were a total of 136 dengue hemorrhagic fever (DHF) cases, of which 20 resulted in death. Most DF cases were reported in southern Taiwan. A total of 15,043 (96%) cases were from Kaohsiung, a modern city in southern Taiwan. This report reviews DF epidemics in Taiwan during 2005-2014. The correlation between DF and DHF along with temperature and precipitation were conjointly examined. We conclude that most dengue epidemics in Taiwan resulted from imported DF cases. Results indicate three main factors that may have been associated with this DF outbreak in Kaohsiung: an underground pipeline explosion combined with subsequent rainfall and higher temperature. These factors may have enhanced mosquito breeding activity, facilitating DENV transmission. © The American Society of Tropical Medicine and Hygiene.

  2. [Work and Training Conditions of Young German Physicians in Internal Medicine - Results of a Second Nationwide Survey by Young Internists from the German Society of Internal Medicine and the German Professional Association of Internists.

    Science.gov (United States)

    Raspe, Matthias; Vogelgesang, Anja; Fendel, Johannes; Weiß, Cornelius; Schulte, Kevin; Rolling, Thierry

    2018-04-01

     Medical specialty training is the basis for career development of young internists and it is vital for the delivery of high-quality medical care. In 2014 the young internists of two professional bodies in Germany conducted a survey among their young members and described major factors influencing training and working conditions. We present the results of a follow-up survey to describe changes of these factors over time. An additional focus is set on the difficulties of balancing medical career and family.  In the end of 2016 we conducted an online-based survey of all members in training of the German Society of Internal Medicine (DGIM) and the Professional Association of German Internists (BDI). The questionnaire used in the 2014 survey was modified and items investigating the balance between career and family were added.  A total of 1587 questionnaires were returned and analysed. Mayor findings did not change over time. Psychosocial strain remains very high among medical trainees in internal medicine. A structured training curriculum and meaningful feedback are associated with lower psychosocial strain and higher work satisfaction. Internists - and here especially women - with children experience the daily balance of medical career and family as extremely challenging.  These results demonstrate that there is still a serious need for adjusting training and working conditions of young internists in Germany. Especially the role and increasing importance of female physicians has to be recognized by enabling a successful integration of medical career and family. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Swine flu - A pandemic outbreak

    Directory of Open Access Journals (Sweden)

    Jini George

    Full Text Available Hippocrates had described influenza like outbreak in 412 B.C. and since then repeated influenza like epidemics and pandemics have been recorded in recent times. One of the greatest killers of all time was the pandemic of swine flu (Spanish flu of 1918-1919, when 230 million people died. Annual influenza epidemics are estimated to affect 5–15% of the global population, resulting in severe illness in 3–5 million patients causing 250,000–500,000 deaths worldwide. Severe illness and deaths occur mainly in the high-risk populations of infants, the elderly and chronically ill patients. The 2009 outbreak of swine flu is thought to be a mutation more specifically a reassortment of four known strains of influenza A virus subtype H1N1; one endemic in humans, one endemic in birds, and two endemic in pigs. WHO officially declared the outbreak to be a pandemic on June 11, 2009, but stressed that the new designation was a result of the global "spread of the virus," not its severity. [Vet World 2009; 2(12.000: 472-474

  4. Perceived competence and attitudes towards patients with suicidal behaviour: a survey of general practitioners, psychiatrists and internists

    OpenAIRE

    Grimholt, Tine K; Haavet, Ole R; Jacobsen, Dag; Sandvik, Leiv; Ekeberg, Oivind

    2014-01-01

    Background Competence and attitudes to suicidal behaviour among physicians are important to provide high-quality care for a large patient group. The aim was to study different physicians’ attitudes towards suicidal behaviour and their perceived competence to care for suicidal patients. Methods A random selection (n = 750) of all registered General Practitioners, Psychiatrists and Internists in Norway ...

  5. Epidemic risk from cholera introductions into Mexico.

    Science.gov (United States)

    Moore, Sean M; Shannon, Kerry L; Zelaya, Carla E; Azman, Andrew S; Lessler, Justin

    2014-02-21

    Stemming from the 2010 cholera outbreak in Haiti, cholera transmission in Hispaniola continues with over 40,000 cases in 2013. The presence of an ongoing cholera outbreak in the region poses substantial risks to countries throughout the Americas, particularly in areas with poor infrastructure. Since September 9, 2013 nearly 200 cholera cases have been reported in Mexico, as a result of introductions from Hispaniola or Cuba. There appear to have been multiple introductions into Mexico resulting in outbreaks of 2 to over 150 people. Using publicly available data, we attempt to estimate the reproductive number (R) of cholera in Mexico, and thereby assess the potential of continued introductions to establish a sustained epidemic. We estimate R for cholera in Mexico to be between 0.8 to 1.1, depending on the number of introductions, with the confidence intervals for the most plausible estimates crossing 1. These results suggest that the efficiency of cholera transmission in some regions of Mexico is near that necessary for a large epidemic. Intensive surveillance, evaluation of water and sanitation infrastructure, and planning for rapid response are warranted steps to avoid potential large epidemics in the region.

  6. Autoimmune hepatitis in a teenage boy: 'overlap' or 'outlier' syndrome--dilemma for internists.

    Science.gov (United States)

    Talukdar, Arunansu; Khanra, Dibbendhu; Mukherjee, Kabita; Saha, Manjari

    2013-02-08

    An 18-year-old boy presented with upper gastrointestinal bleeding and jaundice. Investigations revealed coarse hepatomegaly, splenomegaly and advanced oesophageal varices. Blood reports showed marked rise of alkaline phosphatase and more than twofold rise of transaminases and IgG. Liver histology was suggestive of piecemeal necrosis, interphase hepatitis and bile duct proliferation. Antinuclear antibody was positive in high titre along with positive antismooth muscle antibody and antimitochondrial antibody. The patient was positive for human leukocyte antigen DR3 type. Although an 'overlap' syndrome exists between autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC), a cholestatic variant of AIH, a rare 'outlier' syndrome could not be excluded in our case. Moreover, 'the chicken or the egg', AIH or PBC, the dilemma for the internists continued. The patient was put on steroid and ursodeoxycholic acid with unsatisfactory response. The existing international criteria for diagnosis of AIH are not generous enough to accommodate its variant forms.

  7. 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...

  8. Integrated internist - addiction medicine - hepatology model for hepatitis C management for individuals on methadone maintenance.

    Science.gov (United States)

    Martinez, A D; Dimova, R; Marks, K M; Beeder, A B; Zeremski, M; Kreek, M J; Talal, A H

    2012-01-01

    Despite a high prevalence of hepatitis C virus (HCV) among drug users, HCV evaluation and treatment acceptance are extremely low among these patients when referred from drug treatment facilities for HCV management. We sought to increase HCV treatment effectiveness among patients from a methadone maintenance treatment program (MMTP) by maintaining continuity of care. We developed, instituted and retrospectively assessed the effectiveness of an integrated, co-localized care model in which an internist-addiction medicine specialist from MMTP was embedded in the hepatitis clinic. Methadone maintenance treatment program patients were referred, evaluated by the internist and hepatologist in hepatitis clinic and provided HCV treatment with integration between both sites. Of 401 evaluated patients, anti-HCV antibody was detected in 257, 86% of whom were older than 40 years. Hepatitis C virus RNA levels were measured in 222 patients, 65 of whom were aviremic. Of 157 patients with detectable HCV RNA, 125 were eligible for referral to the hepatitis clinic, 76 (61%) of whom accepted and adhered with the referral. Men engaged in MMTP <36 months were significantly less likely to be seen in hepatitis clinic than men in MMTP more than 36 months (odds ratio = 7.7; 95% confidence interval 2.6-22.9) or women. We evaluated liver histology in 63 patients, and 83% had moderate to advanced liver disease. Twenty-four patients initiated treatment with 19 completing and 13 (54%) achieving sustained response. In conclusion, integrated care between the MMTP and the hepatitis clinic improves adherence with HCV evaluation and treatment compared to standard referral practices. © 2010 Blackwell Publishing Ltd.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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

  14. Five challenges for stochastic epidemic models involving global transmission

    Directory of Open Access Journals (Sweden)

    Tom Britton

    2015-03-01

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

  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. Evaluating Subcriticality during the Ebola Epidemic in West Africa.

    Directory of Open Access Journals (Sweden)

    Wayne T A Enanoria

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

  17. Hospitals and organizational models based on the intensity of treatment: the internist's point of view

    Directory of Open Access Journals (Sweden)

    Giuseppe Chesi

    2012-01-01

    Full Text Available IntroductionThe type of patients being treated in our hospitals has changed significantly. Today's patients are much older with more complicated, polypathological problems. As a result, hospital organization and management structures must also change, particularly in Internal Medicine. A widely discussed approach, organization according to “intensity of treatment,” could be an appropriate solution from an organizational viewpoint that would also satisfy these new demands.Materials and methodsWith the aid of a questionnaire sent to internists working in the hospitals of Italy's Emilia-Romagna region and the review of the relevant medical literature, we defined structural, organizational, technological, managerial, and staffing characteristics to better determine and classify this model. We analyzed questionnaire responses of 31 internists heading operative units in their hospitals, a relatively homogeneous subgroup with experience in organizing and managing healthcare as well as its clinical aspects.ResultsAnalysis of these questionnaires revealed important points concerning the model: 1 an accurate identification of the medical care on which to base the model; 2 a well-defined strategy for differentiated allocation of staff to structural and technological areas depending on the level of medical care provided in the area; 3 an accurate definition of the types and features of patients targeted by each level of medical care; 4 an early exchange (starting from the patient's arrival in the Emergency Department of information and medical knowledge among Emergency Department physicians and those present during the initial stages of hospitalization; 5 a precise definition of responsibilities in the different areas, operative and collaborative stages among different physicians and medical staff, the different disciplines involved in the process.ConclusionsAmong the physicians responsible for managing complex areas of Internal Medicine in Emilia

  18. 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.

  19. 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.

  20. Alkaline stabilization of manure slurry inactivates porcine epidemic diarrhea virus

    Science.gov (United States)

    The porcine epidemic diarrhea virus (PEDv) outbreak in North America has substantially impacted swine production since it causes nearly 100% mortality in infected pre-weaned piglets. The PED virus is transmitted via the fecal oral route and manure may remain a source of reinfection; therefore, prop...

  1. 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 ...

  2. Porcine Epidemic Diarrhea Virus among Farmed Pigs, Ukraine.

    Science.gov (United States)

    Dastjerdi, Akbar; Carr, John; Ellis, Richard J; Steinbach, Falko; Williamson, Susanna

    2015-12-01

    An outbreak of porcine epidemic diarrhea occurred in the summer of 2014 in Ukraine, severely affecting piglets <10 days of age; the mortality rate approached 100%. Full genome sequencing showed the virus to be closely related to strains reported from North America, showing a sequence identity of up to 99.8%.

  3. The 1992 measles epidemic in Cape Town - a changing ...

    African Journals Online (AJOL)

    Over the last 6 years there has been a decline in the incidence of measles in Cape Town. However, during August 1992 an outbreak occurred, with cases reported at many schools in children presumably immunised. The objectives of this study were to characterise the epidemic in Cape Town and to determine possible ...

  4. 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...

  5. Slow Epidemic of Lymphogranuloma Venereum L2b Strain

    Science.gov (United States)

    Spaargaren, Joke; Schachter, Julius; Moncada, Jeanne; de Vries, Henry J.C.; Fennema, Han S.A.; Peña, A. Salvador; Coutinho, Roel A.

    2005-01-01

    We traced the Chlamydia trachomatis L2b variant in Amsterdam and San Francisco. All recent lymphogranuloma venereum cases in Amsterdam were caused by the L2b variant. This variant was also present in the 1980s in San Francisco. Thus, the current "outbreak" is most likely a slowly evolving epidemic. PMID:16318741

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

    Science.gov (United States)

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

    2015-06-01

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

  7. Disease Outbreak News

    Science.gov (United States)

    ... MERS-CoV) Pandemic (H1N1) 2009 Influenza at the Human-Animal Interface (HAI) Related documents WHO outbreak communication guide 2008 WHO outbreak communications guidelines Outbreak communication: ...

  8. 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%.

  9. 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.

  10. 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.

  11. 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.

  12. Epidemic contact tracing via communication traces.

    Directory of Open Access Journals (Sweden)

    Katayoun Farrahi

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

  13. Epidemic contact tracing via communication traces.

    Science.gov (United States)

    Farrahi, Katayoun; Emonet, Rémi; Cebrian, Manuel

    2014-01-01

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

  14. 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.

  15. A simple model for behaviour change in epidemics

    Directory of Open Access Journals (Sweden)

    Brauer Fred

    2011-02-01

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

  16. outbreak of hepatitis 'E' in risalpur garrison

    International Nuclear Information System (INIS)

    Sharif, T.B.; Tariq, W.U.Z.

    2007-01-01

    Hepatitis E virus is an RNA virus. It results in epidemics/outbreaks in geographical areas lacking clean water and sanitation. It is excreted in stools and is enterically transmitted (faeco-oral route). The clinical picture resembles other acute hepatitis and diagnosis is clinched by detecting anti-HEV IgM in infected individuals. It is a self-limiting disease and does not progress to chronicity. There is no vaccine available so far, to confer immunity against HEV infection. HEV is endemic in many parts of the world and has resulted in many epidemics / outbreaks worldwide. It is also endemic in Pakistan and epidemics / outbreaks have generally been under reported. To establish the cause of outbreak Blood samples of the patients (n=195), admitted in isolation ward were collected aseptically for routine baseline investigations and hepatitis screening. Separate blood samples were sent to Armed Forces Institute of pathology (AFIP), Rawalpindi for detection of antibodies to hepatitis E virus (Anti HEV IgM). Water samples collected during the outbreak were tested by multiple tube technique. MPN (Most Probable Number) method was used to determine faecal coliform bacteria per 100 ml of water sample. All the patients (n=195) on admission had raised ALT (Alanine Aminotransferase) levels along with hyperbilirubinemia, 37% had raised TLC with polymorphonuclear response. None had HBsAg (Hepatitis B surface antign) or anti-HCV (antibodies to hepatitis C virus), 23% had prolonged PT (Prothrombin Time). Samples despatched to AFIP Rawalpindi confirmed the presence of anti-HEV IgM. Follow up analysis revealed many fold increase in ALT levels. Average stay in the Hospital was 23.6 days per patient. All the water samples were declared unfit for drinking due to high coliform count. At present, no vaccine is available to protect against HEV infection. Mainstay for prevention and occurrence is to formulate cost-effective strategies for improvement of self/environmental hygiene and

  17. 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....

  18. 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.

  19. Mathematical modeling of Avian Influenza epidemic with bird vaccination in constant population

    Science.gov (United States)

    Kharis, M.; Amidi

    2018-03-01

    The development of the industrial world and human life is increasingly modern and less attention to environmental sustainability causes the virus causes the epidemic has a high tendency to mutate so that the virus that initially only attack animals, is also found to have the ability to attack humans. The epidemics that lasted some time were bird flu epidemics and swine flu epidemics. The flu epidemic led to several deaths and many people admitted to the hospital. Strain (derivatives) of H5N1 virus was identified as the cause of the bird flu epidemic while the H1N1 strain of the virus was identified as the cause of the swine flu epidemic. The symptoms are similar to seasonal flu caused by H3N2 strain of the virus. Outbreaks of bird flu and swine flu initially only attacked animals, but over time some people were found to be infected with the virus.

  20. 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

  1. Disneyland Measles Outbreak

    OpenAIRE

    Palladino, Erica

    2015-01-01

    This media information sheet analyzes print and online coverage of the 2015 Disneyland measles outbreak. The frameworks that the media used to report on the outbreak presented vaccination as the only viable option from preventing the spread of measles. Reporting also failed to mention that the 2015 Disneyland measles outbreak was smaller than U.S. measles outbreaks in 2013 and 2014.

  2. 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.

  3. Post-Ebola Measles Outbreak in Lola, Guinea, January-June 2015(1).

    Science.gov (United States)

    Suk, Jonathan E; Paez Jimenez, Adela; Kourouma, Mamadou; Derrough, Tarik; Baldé, Mamadou; Honomou, Patric; Kolie, Nestor; Mamadi, Oularé; Tamba, Kaduono; Lamah, Kalaya; Loua, Angelo; Mollet, Thomas; Lamah, Molou; Camara, Amara Nana; Prikazsky, Vladimir

    2016-06-01

    During public health crises such as the recent outbreaks of Ebola virus disease in West Africa, breakdowns in public health systems can lead to epidemics of vaccine-preventable diseases. We report here on an outbreak of measles in the prefecture of Lola, Guinea, which started in January 2015.

  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. [Epidemic of bacillary dysentery in the Rwanda refugee camps of the Goma region (Zaire, North Kivu) in August 1994].

    Science.gov (United States)

    Milleliri, J M; Soares, J L; Signoret, J; Bechen, R; Lamarque, D; Boutin, J P; Coué, J C; Niel, L; Merouze, F; Rey, J L

    1995-09-01

    The authors describe the extension of an outbreak of bacillary dysentery among the Rwandese populations seeking refuge in the region of Goma, Zaire in august 1994. Analysis of the epidemiological surveillance data and of the bacteriological laboratory results of the Bioforce, show that this epidemic was probably facilitated by the preceding cholera outbreak. In such circumstances, rapid sterilization of the virus reservoir, by short course treatments, might be beneficial in limiting the extension of the epidemic.

  6. Detecting and Responding to a Dengue Outbreak: Evaluation of Existing Strategies in Country Outbreak Response Planning

    Directory of Open Access Journals (Sweden)

    Julia Harrington

    2013-01-01

    Full Text Available Background. Dengue outbreaks are occurring with increasing frequency and intensity. Evidence-based epidemic preparedness and effective response are now a matter of urgency. Therefore, we have analysed national and municipal dengue outbreak response plans. Methods. Thirteen country plans from Asia, Latin America and Australia, and one international plan were obtained from the World Health Organization. The information was transferred to a data analysis matrix where information was extracted according to predefined and emerging themes and analysed for scope, inconsistencies, omissions, and usefulness. Findings. Outbreak response planning currently has a considerable number of flaws. Outbreak governance was weak with a lack of clarity of stakeholder roles. Late timing of responses due to poor surveillance, a lack of combining routine data with additional alerts, and lack of triggers for initiating the response weakened the functionality of plans. Frequently an outbreak was not defined, and early response mechanisms based on alert signals were neglected. There was a distinct lack of consideration of contextual influences which can affect how an outbreak detection and response is managed. Conclusion. A model contingency plan for dengue outbreak prediction, detection, and response may help national disease control authorities to develop their own more detailed and functional context specific plans.

  7. Measles outbreak investigation in Guji zone of Oromia Region, Ethiopia.

    Science.gov (United States)

    Belda, Ketema; Tegegne, Ayesheshem Ademe; Mersha, Amare Mengistu; Bayenessagne, Mekonnen Getahun; Hussein, Ibrahim; Bezabeh, Belay

    2017-01-01

    Despite the increase of immunization coverage (administrative) of measles in the country, there are widespread outbreaks of measles. In this respect, we investigated one of the outbreaks that occurred in hard to reach kebeles of Guji Zone, Oromia region, to identify the contributing factors that lead to the protracted outbreak of measles. We used a cross-sectional study design to investigate a measles outbreak in Guji zone, Oromia region. Data entry and analysis was performed using EPI-Info version 7.1.0.6 and MS-Microsoft Excel. In three months' time a total of 1059 suspected cases and two deaths were reported from 9 woredas affected by a measles outbreak in Guji zone. The cumulative attack rate of 81/100,000 population and case fatality ratio of 0.2% was recorded. Of these, 821 (77.5%) cases were measles vaccine. Although, all age groups were affected under five years old were more affected 495 (48%) than any other age groups. In response to the outbreak, an outbreak response immunization was organized at the 11th week of the epidemic, when the epidemic curve started to decline. 6 months to14 years old were targeted for outbreak response immunization and the overall coverage was 97 % (range: 90-103%). Case management with vitamin A supplementation, active case search, and health education was some of the activities carried out to curb the outbreak. We conclude that low routine immunization coverage in conjunction with low access to routine immunization in hard to reach areas, low community awareness in utilization of immunization service, inadequate cold chain management and delivery of a potent vaccine in hard to reach woredas/kebeles were likely contributed to the outbreak that's triggered a broad spread epidemic affecting mostly children without any vaccination. We also figured that the case-based surveillance lacks sensitivity and timely confirmation of the outbreak, which as a result outbreak response immunization were delayed. We recommend establishing

  8. Specialist physician knowledge of chronic kidney disease: A comparison of internists and family physicians in West Africa

    Directory of Open Access Journals (Sweden)

    Emmanuel I. Agaba

    2012-05-01

    Full Text Available Background: Postgraduate training is aimed at equipping the trainee with the necessary skills to practise as an expert. Non-nephrology specialist physicians render the bulk of pre-end-stage renal disease care for patients with chronic kidney disease (CKD. We sought to ascertain the knowledge of CKD amongst non-nephrology specialist physicians who serve as trainers and examiners for a training, accrediting and certifying body in postgraduate medicine in West Africa. We also compared the knowledge of family physicians and non-nephrology internists. Methods: Self-administered questionnaires were distributed to non-nephrology specialist physicians who serve as examiners for the West African College of Physicians. Results: Only 19 (27.5% of the respondents were aware of the Kidney Disease Outcomes Quality Initiatives guidelines for CKD management. Twenty five (36.2% of the respondents had adequate knowledge of CKD. There was no significant difference in the proportion of family physicians and non-nephrology internists who had adequate knowledge of CKD (27.3% vs. 40.4% respectively; p = 0.28. Hypertension and diabetes mellitus were identified by all of the physicians as risk factors for CKD. Non-nephrology internists more frequently identified systemic lupus erythematosus as a risk factor for CKD, urinalysis with microscopy as a laboratory test for CKD evaluation, and bone disease as a complication of CKD than family physicians. Conclusion: There is a lack of adequate CKD knowledge amongst non-nephrology specialist physicians, since many of them are unaware of the CKD management guidelines. Educational efforts are needed to improve the knowledge of CKD amongst non-nephrology specialist physicians. Guidelines on CKD need to be widely disseminated amongst these physicians.

  9. 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.

  10. Experimental Infection of Young Pigs with an Early European Strain of Porcine Epidemic Diarrhoea Virus and a Recent US Strain

    DEFF Research Database (Denmark)

    Lohse, Louise; Krog, Jesper Schak; Strandbygaard, Bertel

    2017-01-01

    Outbreaks of porcine epidemic diarrhoea (PED) were reported across Europe during the 1980s and 1990s, but only sporadic outbreaks occurred in recent years. PED virus (PEDV) spread for the first time into the USA in 2013 and has caused severe economic losses. Retrospectively, it was found that two...

  11. Ebola Virus Epidemic in West Africa and Beyond

    Directory of Open Access Journals (Sweden)

    Oscar G Gómez-Duarte

    2014-10-01

    Full Text Available Is there a reason to fear that an Ebola outbreak may strike Latin America? The fear may not be unreasonable taking into account the history of epidemics that have affected the American continent since colonization times in 1492. Old World small pox epidemics spread and killed millions of Native Americans north and south from the equator. Imported West Nile virus infections reported in New York in 1999 dramatically spread East to West of the United States. Most recently, Chikungunya virus arrived to Central America in 2013 and has already infected close to 1 million people in Mexico, Central American countries, Brazil, Colombia, Ecuador, Guyanas, Paraguay, and Venezuela.

  12. Random migration processes between two stochastic epidemic centers.

    Science.gov (United States)

    Sazonov, Igor; Kelbert, Mark; Gravenor, Michael B

    2016-04-01

    We consider the epidemic dynamics in stochastic interacting population centers coupled by random migration. Both the epidemic and the migration processes are modeled by Markov chains. We derive explicit formulae for the probability distribution of the migration process, and explore the dependence of outbreak patterns on initial parameters, population sizes and coupling parameters, using analytical and numerical methods. We show the importance of considering the movement of resident and visitor individuals separately. The mean field approximation for a general migration process is derived and an approximate method that allows the computation of statistical moments for networks with highly populated centers is proposed and tested numerically. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    DEFF Research Database (Denmark)

    Viboud, Cecile; Simonsen, Lone; Chowell, Gerardo

    2016-01-01

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

  14. Association of Heavy Rainfall on Genotypic Diversity in V. cholerae Isolates from an Outbreak in India

    Directory of Open Access Journals (Sweden)

    A. K. Goel

    2011-01-01

    Full Text Available The outbreak of waterborne disease cholera has been associated with rainfall and flooding events by contamination of potable water with environmental Vibrio cholerae. The continuation of the epidemic in a region, however, is often due to secondary transmission of the initial outbreak strain through human waste. This paper reports, on the contrary, a rapid shift of genotype from one V. cholerae strain to another one in an epidemic region. V. cholerae isolated from patients during 2005 cholera epidemic in Chennai, India were characterized using PCR identification of toxin genes, antibiogram, and genomic fingerprinting analysis. The results showed that in spite of the similarity of toxin genes and antibiogram, the Vibrio isolates grouped into two different clusters based on the ERIC-PCR fingerprinting. Each cluster corresponded to a distinct peak of cholera outbreak, which occurred after separate heavy rainfall. The results suggest that the rainfall event can bring various genotypes of V. cholerae strains causing multiple outbreaks.

  15. Where is the difference between an epidemic and a high endemic level with respect to nosocomial infection control measures? An analysis based on the example of vancomycin-resistant Enterococcus faecium in hematology and oncology departments

    Directory of Open Access Journals (Sweden)

    Ulrich, Nikos

    2017-08-01

    Full Text Available Some infection control recommendations distinguish epidemic and endemic levels for infection control. However, it is often difficult to separate long lasting outbreaks from high endemic levels and it remains open, if this distinction is really useful.Aim: To compare infection control measures in endemic and epidemic outbreaks.Methods: The example of vancomycin-resistant outbreaks in haematology or oncology departments was used to analyse differences in infection control measures between outbreaks and high endemic levels. The outbreak database and PubMed, including long lasting outbreaks, were used for this analysis. Two time limits were used for separation: 6 and 12 months. In addition, monoclonal and polyclonal outbreaks were distinguished. Findings: A total of 36 outbreaks were included. 13 outbreaks lasted 6 months or less, 9 outbreaks more than 6 months but at maximum 12 months and 9 more than 12 months. For the remaining outbreaks, no information about their duration was available. Altogether, 11 outbreaks were monoclonal and 20 polyclonal. ri infection control measures, there were almost no differences between the different groups compared. Patient screening was given up in 37.5% of long lasting outbreaks (>12 months and hand hygiene not reported in the majority of polyclonal outbreaks (77.8%.Conclusion: Despite many institutions trying to add further infection control measures in case of an outbreak, evidence based infection control measures should be implemented in endemic and epidemic situations. The crucial aspect is probably the degree of implementation and its control in both situations.

  16. Descripción de un brote epidémico de toxoplasmosis aguda en pacientes inmunocompetentes miembros de las fuerzas militares de Colombia durante operaciones de selva Description of an epidemic outbreak of acute toxoplasmosis in immunocompetent patients from Colombian Armed Forces during jungle operations

    Directory of Open Access Journals (Sweden)

    Luis Eduardo Pino

    2009-06-01

    report of an epidemic outbreak caused by Toxoplasma gondii in military personnel deployed to rural areas located at La Macarena, Meta , Colombia. All 18 cases were confirmed by IgG indirect immunofluorescence (IFI with titers higher than 1:1,024 (normal range: 1:16. Their main symptoms were fever, adenopathies and pulmonary and gastrointestinal compromise. One patient developed severe myocardial compromise. All the patients recovered after treatment with pyrimetamine/sulfadoxine and clyndamicin for 3 weeks. A possible hypothesis for this outbreak was the consumption of contaminated water with oocysts, and probably the severity of the compromise could be elicited by a “wild” strain of the parasite as it is reported in the literature. Unfortunately, it was impossible to isolate and identify the specific strain.

  17. Ebola virus disease in West Africa: outbreak or epidemic?

    African Journals Online (AJOL)

    Gboyega Ogunbanjo

    2014-08-20

    Aug 20, 2014 ... Control and Prevention, the European Commission and the. Economic ... active public health surveillance system in place to respond to infectious ... it takes approximately eight hours for a flight from Abidjan,. Ivory Coast, West ...

  18. Perceived competence and attitudes towards patients with suicidal behaviour: a survey of general practitioners, psychiatrists and internists.

    Science.gov (United States)

    Grimholt, Tine K; Haavet, Ole R; Jacobsen, Dag; Sandvik, Leiv; Ekeberg, Oivind

    2014-05-08

    Competence and attitudes to suicidal behaviour among physicians are important to provide high-quality care for a large patient group. The aim was to study different physicians' attitudes towards suicidal behaviour and their perceived competence to care for suicidal patients. A random selection (n = 750) of all registered General Practitioners, Psychiatrists and Internists in Norway received a questionnaire. The response rate was 40%. The Understanding of Suicidal Patients Scale (USP; scores scales were used to measure self-perceived competence, level of commitment, empathy and irritation felt towards patients with somatic and psychiatric diagnoses. Questions about training were included. The physicians held positive attitudes towards suicide attempters (USP = 20.3, 95% CI: 19.6-20.9). Internists and males were significantly less positive. There were no significant differences in the physicians in their attitudes toward suicide in case of incurable illness according to specialty. The physicians were most irritated and less committed to substance misuse patients. Self perceived competence was relatively high. Forty-three percent had participated in courses about suicide assessment and treatment. The physicians reported positive attitudes and relatively high competence. They were least committed to treat patients with substance misuse. None of the professional groups thought that patients with incurable illness should be given help to commit suicide. Further customized education with focus on substance misuse might be useful.

  19. Avalanche outbreaks emerging in cooperative contagions

    Science.gov (United States)

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

    2015-11-01

    The spreading of contagions can exhibit a percolation transition, which separates transitory prevalence from outbreaks that reach a finite fraction of the population. Such transitions are commonly believed to be continuous, but empirical studies have shown more violent spreading modes when the participating agents are not limited to one type. Striking examples include the co-epidemic of the Spanish flu and pneumonia that occurred in 1918 (refs , ), and, more recently, the concurrent prevalence of HIV/AIDS and a host of diseases. It remains unclear to what extent an outbreak in the presence of interacting pathogens differs from that due to an ordinary single-agent process. Here we study a mechanistic model for understanding contagion processes involving inter-agent cooperation. Our stochastic simulations reveal the possible emergence of a massive avalanche-like outbreak right at the threshold, which is manifested as a discontinuous phase transition. Such an abrupt change arises only if the underlying network topology supports a bottleneck for cascaded mutual infections. Surprisingly, all these discontinuous transitions are accompanied by non-trivial critical behaviours, presenting a rare case of hybrid transition. The findings may imply the origin of catastrophic occurrences in many realistic systems, from co-epidemics to financial contagions.

  20. 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.

  1. 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).

  2. 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.

  3. Specialist physician knowledge of chronic kidney disease: A comparison of internists and family physicians in West Africa

    Directory of Open Access Journals (Sweden)

    Antonios H. Tzamaloukas

    2012-05-01

    Full Text Available Background: Postgraduate training is aimed at equipping the trainee with the necessary skills to practise as an expert. Non-nephrology specialist physicians render the bulk of pre-end-stage renal disease care for patients with chronic kidney disease (CKD. We sought to ascertain the knowledge of CKD amongst non-nephrology specialist physicians who serve as trainers and examiners for a training, accrediting and certifying body in postgraduate medicine in West Africa. We also compared the knowledge of family physicians and non-nephrology internists.Methods: Self-administered questionnaires were distributed to non-nephrology specialist physicians who serve as examiners for the West African College of Physicians.Results: Only 19 (27.5% of the respondents were aware of the Kidney Disease Outcomes Quality Initiatives guidelines for CKD management. Twenty five (36.2% of the respondents had adequate knowledge of CKD. There was no significant difference in the proportion of family physicians and non-nephrology internists who had adequate knowledge of CKD (27.3% vs. 40.4% respectively; p = 0.28. Hypertension and diabetes mellitus were identified by all of the physicians as risk factors for CKD. Non-nephrology internists more frequently identified systemic lupus erythematosus as a risk factor for CKD, urinalysis with microscopy as a laboratory test for CKD evaluation, and bone disease as a complication of CKD than family physicians.Conclusion: There is a lack of adequate CKD knowledge amongst non-nephrology specialist physicians, since many of them are unaware of the CKD management guidelines. Educational efforts are needed to improve the knowledge of CKD amongst non-nephrology specialist physicians. Guidelines on CKD need to be widely disseminated amongst these physicians.Connaissances des spécialistes des maladies rénales chroniques : Une comparaison des internistes et des médecins de famille en Afrique de l’OuestContexte: La formation de troisi

  4. 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)

  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. A primer on stochastic epidemic models: Formulation, numerical simulation, and analysis

    Directory of Open Access Journals (Sweden)

    Linda J.S. Allen

    2017-05-01

    Full Text Available Some mathematical methods for formulation and numerical simulation of stochastic epidemic models are presented. Specifically, models are formulated for continuous-time Markov chains and stochastic differential equations. Some well-known examples are used for illustration such as an SIR epidemic model and a host-vector malaria model. Analytical methods for approximating the probability of a disease outbreak are also discussed. Keywords: Branching process, Continuous-time Markov chain, Minor outbreak, Stochastic differential equation, 2000 MSC: 60H10, 60J28, 92D30

  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. Spatio-temporal magnitude and direction of highly pathogenic avian influenza (H5N1) outbreaks in Bangladesh

    DEFF Research Database (Denmark)

    Ahmed, Syed Sayeem Uddin; Ersbøll, Annette Kjær; Biswas, Paritosh K.

    2011-01-01

    The number of outbreaks of HPAI-H5N1 reported by Bangladesh from 2007 through 2011 placed the country among the highest reported numbers worldwide. However, so far, the understanding of the epidemic progression, direction, intensity, persistence and risk variation of HPAI-H5N1 outbreaks over spac...

  9. Key data for outbreak evaluation: building on the Ebola experience.

    Science.gov (United States)

    Cori, Anne; Donnelly, Christl A; Dorigatti, Ilaria; Ferguson, Neil M; Fraser, Christophe; Garske, Tini; Jombart, Thibaut; Nedjati-Gilani, Gemma; Nouvellet, Pierre; Riley, Steven; Van Kerkhove, Maria D; Mills, Harriet L; Blake, Isobel M

    2017-05-26

    Following the detection of an infectious disease outbreak, rapid epidemiological assessment is critical for guiding an effective public health response. To understand the transmission dynamics and potential impact of an outbreak, several types of data are necessary. Here we build on experience gained in the West African Ebola epidemic and prior emerging infectious disease outbreaks to set out a checklist of data needed to: (1) quantify severity and transmissibility; (2) characterize heterogeneities in transmission and their determinants; and (3) assess the effectiveness of different interventions. We differentiate data needs into individual-level data (e.g. a detailed list of reported cases), exposure data (e.g. identifying where/how cases may have been infected) and population-level data (e.g. size/demographics of the population(s) affected and when/where interventions were implemented). A remarkable amount of individual-level and exposure data was collected during the West African Ebola epidemic, which allowed the assessment of (1) and (2). However, gaps in population-level data (particularly around which interventions were applied when and where) posed challenges to the assessment of (3). Here we highlight recurrent data issues, give practical suggestions for addressing these issues and discuss priorities for improvements in data collection in future outbreaks.This article is part of the themed issue 'The 2013-2016 West African Ebola epidemic: data, decision-making and disease control'. © 2017 The Authors.

  10. Ebola viral hemorrhagic disease outbreak in West Africa- lessons from Uganda.

    Science.gov (United States)

    Mbonye, Anthony K; Wamala, Joseph F; Nanyunja, Miriam; Opio, Alex; Makumbi, Issa; Aceng, Jane Ruth

    2014-09-01

    There has been a rapid spread of Ebola Viral Hemorrhagic disease in Guinea, Liberia and Sierra Leone since March 2014. Since this is the first time of a major Ebola outbreak in West Africa; it is possible there is lack of understanding of the epidemic in the communities, lack of experience among the health workers to manage the cases and limited capacities for rapid response. The main objective of this article is to share Uganda's experience in controlling similar Ebola outbreaks and to suggest some lessons that could inform the control of the Ebola outbreak in West Africa. The article is based on published papers, reports of previous Ebola outbreaks, response plans and experiences of individuals who have participated in the control of Ebola epidemics in Uganda. Lessons learnt: The success in the control of Ebola epidemics in Uganda has been due to high political support, effective coordination through national and district task forces. In addition there has been active surveillance, strong community mobilization using village health teams and other community resources persons, an efficient laboratory system that has capacity to provide timely results. These have coupled with effective case management and infection control and the involvement of development partners who commit resources with shared responsibility. Several factors have contributed to the successful quick containment of Ebola outbreaks in Uganda. West African countries experiencing Ebola outbreaks could draw some lessons from the Uganda experience and adapt them to contain the Ebola epidemic.

  11. Varicella outbreak in Sudanese refugees from Calais.

    Science.gov (United States)

    Lesens, O; Baud, O; Henquell, C; Lhermet Nurse, A; Beytout, J

    2016-05-01

    We describe an outbreak of varicella in 31 Sudanese refugees (all except one were male, mean age: 26 ± 1), from the Calais migrant camp and sheltered in a French transit area. The attack rate was 39%. Adults are scantly immunized against varicella zoster virus in East Africa and may be exposed to epidemics once in France. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.

  12. How Will Climate Change Impact Cholera Outbreaks?

    Science.gov (United States)

    Nasr Azadani, F.; Jutla, A.; Rahimikolu, J.; Akanda, A. S.; Huq, A.; Colwell, R. R.

    2014-12-01

    Environmental parameters associated with cholera are well documented. However, cholera continues to be a global public health threat. Uncertainty in defining environmental processes affecting growth and multiplication of the cholera bacteria can be affected significantly by changing climate at different temporal and spatial scales, either through amplification of the hydroclimatic cycle or by enhanced variability of large scale geophysical processes. Endemic cholera in the Bengal Delta region of South Asia has a unique pattern of two seasonal peaks and there are associated with asymmetric and episodic variability in river discharge. The first cholera outbreak in spring is related with intrusion of bacteria laden coastal seawater during low river discharge. Cholera occurring during the fall season is hypothesized to be associated with high river discharge related to a cross-contamination of water resources and, therefore, a second wave of disease, a phenomenon characteristic primarily in the inland regions. Because of difficulties in establishing linkage between coarse resolutions of the Global Climate Model (GCM) output and localized disease outbreaks, the impact of climate change on diarrheal disease has not been explored. Here using the downscaling method of Support Vector Machines from HADCM3 and ECHAM models, we show how cholera outbreak patterns are changing in the Bengal Delta. Our preliminary results indicate statistically significant changes in both seasonality and magnitude in the occurrence of cholera over the next century. Endemic cholera is likely to transform into epidemic forms and new geographical areas will be at risk for cholera outbreaks.

  13. Absence of race- or gender-specific income disparities among full-time white and Asian general internists working for the Veterans Administration.

    Science.gov (United States)

    Weeks, William B; Wallace, Amy E

    2010-02-01

    Gender-based, but not race-based, income disparities exist among general internists who practice medicine in the private sector. The aim of this study was to assess whether race- or gender-based income disparities existed among full-time white and Asian general internists who worked for the Veterans Health Administration of the US Department of Veterans Affairs (VA) between fiscal years 2004 and 2007, and whether any disparities changed after the VA enacted physician pay reform in early 2006. A retrospective study was conducted of all nonsupervisory, board-certified, full-time white or Asian VA general internists who did not change their location of practice between fiscal years 2004 and 2007. A longitudinal cohort design and linear regression modeling, adjusted for physician characteristics, were used to compare race- and gender-specific incomes in fiscal years 2004-2007. A total of 176 physicians were included in the study: 82 white males, 33 Asian males, 30 white females, and 31 Asian females. In all fiscal years examined, white males had the highest mean annual incomes, though not statistically significantly so. Regression analyses for fiscal years 2004 through 2006 revealed that physician age and years of service were predictive of total income. After physician pay reform was enacted, Asian male VA primary care physicians had higher annual incomes than did physicians in all other race or gender categories, after adjustment for age and years of VA service, though these differences were not statistically significant. No significant gender-based income disparities were noted among these white and Asian VA physicians. Our findings for white and Asian general internists suggest that the VA' s goal of maintaining a racially diverse workforce may have been effected, in part, through use of market pay among primary care general internists. Copyright 2010. Published by Elsevier Inc.

  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. 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. 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 ...

  19. 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 ...

  20. 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...

  1. On the relative role of different age groups in influenza epidemics.

    Science.gov (United States)

    Worby, Colin J; Chaves, Sandra S; Wallinga, Jacco; Lipsitch, Marc; Finelli, Lyn; Goldstein, Edward

    2015-12-01

    The identification of key "driver" groups in influenza epidemics is of much interest for the implementation of effective public health response strategies, including vaccination programs. However, the relative importance of different age groups in propagating epidemics is uncertain. During a communicable disease outbreak, some groups may be disproportionately represented during the outbreak's ascent due to increased susceptibility and/or contact rates. Such groups or subpopulations can be identified by considering the proportion of cases within the subpopulation occurring before (Bp) and after the epidemic peak (Ap) to calculate the subpopulation's relative risk, RR=Bp/Ap. We estimated RR for several subpopulations (age groups) using data on laboratory-confirmed US influenza hospitalizations during epidemics between 2009-2014. Additionally, we simulated various influenza outbreaks in an age-stratified population, relating the RR to the impact of vaccination in each subpopulation on the epidemic's initial effective reproductive number R_e(0). We found that children aged 5-17 had the highest estimates of RR during the five largest influenza A outbreaks, though the relative magnitude of RR in this age group compared to other age groups varied, being highest for the 2009 A/H1N1 pandemic. For the 2010-2011 and 2012-2013 influenza B epidemics, adults aged 18-49, and 0-4 year-olds had the highest estimates of RR respectively. For 83% of simulated epidemics, the group with the highest RR was also the group for which initial distribution of a given quantity of vaccine would result in the largest reduction of R_e(0). In the largest 40% of simulated outbreaks, the group with the highest RR and the largest vaccination impact was children 5-17. While the relative importance of different age groups in propagating influenza outbreaks varies, children aged 5-17 play the leading role during the largest influenza A epidemics. Extra vaccination efforts for this group may contribute

  2. 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

  3. 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).

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Field observations during the Bluetongue serotype 8 epidemic in 2006 II. Morbidity and mortality rate, case fatality and clinical recovery in sheep and cattle in the Netherlands

    NARCIS (Netherlands)

    Elbers, A.R.W.; Backx, A.; Mintiens, K.; Gerbier, G.; Staubach, C.; Hendrickx, G.; Spek, van der A.N.

    2008-01-01

    Data collected in the Netherlands during the Bluetongue serotype 8 (BTV-8) epidemic indicated that in outbreak cattle herds, predominantly dairy and nursing cows were clinically affected and not young stock, beef cattle, beef calves, or breeding animals. In outbreak sheep flocks, mainly ewes and ¿

  9. 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.

  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. Manure treatment and natural inactivation of porcine epidemic diarrhea virus in soils

    Science.gov (United States)

    The outbreak of porcine epidemic diarrhea virus (PEDv) in North America has substantially impacted U.S. swine production in recent years. The virus it is easily transmitted among pigs and causes nearly 100% mortality in pre-weaned piglets. Because PEDv is an enteric virus spread via fecal-oral conta...

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

    Science.gov (United States)

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

  13. Pre-epidemic preparedness and the control of Lassa fever in ...

    African Journals Online (AJOL)

    The country seems not to have learnt from past epidemics most especially the 2014 Ebola Virus Disease (EVD) outbreak. After the declaration of Nigeria EVD free, most control arsenals were relaxed, isolation and quarantine structures were dismantled and preventive efforts such as provision of Personal Protective ...

  14. Inter-laboratory study to characterize the detection of serum antibodies against porcine epidemic diarrhoea virus

    DEFF Research Database (Denmark)

    Strandbygaard, Bertel; Lavazza, Antonio; Lelli, Davide

    2016-01-01

    Porcine epidemic diarrhea virus (PEDV) has caused extensive economic losses to pig producers in many countries. It was recently introduced, for the first time, into North America and outbreaks have occurred again in multiple countries within Europe as well. To assess the properties of various dia...

  15. Human angiostrongyliasis outbreak in Dali, China.

    Directory of Open Access Journals (Sweden)

    Shan Lv

    Full Text Available BACKGROUND: Several angiostrongyliasis outbreaks have been reported in recent years but the disease continues to be neglected in public health circles. We describe an outbreak in Dali, southwest China in order to highlight some key problems for the control of this helminth infection. METHODOLOGY/PRINCIPAL FINDINGS: All available medical records of suspected angiostrongyliasis patients visiting hospitals in Dali in the period 1 October 2007-31 March 2008 were reviewed, and tentative diagnoses of varying strengths were reached according to given sets of criteria. Snails collected from local markets, restaurants and natural habitats were also screened for the presence of Angiostrongylus cantonensis. A total of 33 patients met criteria for infection, and 11 among them were classified as clinically confirmed. An additional eight patients were identified through a surveillance system put in operation in response to the outbreak. The epidemic lasted for 8 months with its peak in February 2008. Of the 33 patients, 97.0% complained of severe headache. 84.8% patients had high eosinophil cell counts either in the peripheral blood or in cerebrospinal fluid (CSF. Three-quarters of the patients were treated with a combination of albendazole and corticosteroids, resulting in significantly improved overall conditions. Twenty-two patients reported the consumption of raw or undercooked snails prior to the onset of the symptoms, and approximately 1.0% of the Pomacea canaliculata snails on sale were found to be infected with A. cantonensis. The snails were also found in certain habitats around Dali but no parasites were detected in these populations. CONCLUSIONS/SIGNIFICANCE: The import and sale of infected P. canaliculata is the likely trigger for this angiostrongyliasis outbreak. Awareness of angiostrongyliasis must be raised, and standardized diagnosis and treatment are needed in order to provide clinicians with a guide to address this disease. Health education

  16. Human angiostrongyliasis outbreak in Dali, China.

    Science.gov (United States)

    Lv, Shan; Zhang, Yi; Chen, Shao-Rong; Wang, Li-Bo; Fang, Wen; Chen, Feng; Jiang, Jin-Yong; Li, Yuan-Lin; Du, Zun-Wei; Zhou, Xiao-Nong

    2009-09-22

    Several angiostrongyliasis outbreaks have been reported in recent years but the disease continues to be neglected in public health circles. We describe an outbreak in Dali, southwest China in order to highlight some key problems for the control of this helminth infection. All available medical records of suspected angiostrongyliasis patients visiting hospitals in Dali in the period 1 October 2007-31 March 2008 were reviewed, and tentative diagnoses of varying strengths were reached according to given sets of criteria. Snails collected from local markets, restaurants and natural habitats were also screened for the presence of Angiostrongylus cantonensis. A total of 33 patients met criteria for infection, and 11 among them were classified as clinically confirmed. An additional eight patients were identified through a surveillance system put in operation in response to the outbreak. The epidemic lasted for 8 months with its peak in February 2008. Of the 33 patients, 97.0% complained of severe headache. 84.8% patients had high eosinophil cell counts either in the peripheral blood or in cerebrospinal fluid (CSF). Three-quarters of the patients were treated with a combination of albendazole and corticosteroids, resulting in significantly improved overall conditions. Twenty-two patients reported the consumption of raw or undercooked snails prior to the onset of the symptoms, and approximately 1.0% of the Pomacea canaliculata snails on sale were found to be infected with A. cantonensis. The snails were also found in certain habitats around Dali but no parasites were detected in these populations. The import and sale of infected P. canaliculata is the likely trigger for this angiostrongyliasis outbreak. Awareness of angiostrongyliasis must be raised, and standardized diagnosis and treatment are needed in order to provide clinicians with a guide to address this disease. Health education campaigns could limit the risk, and a hospital-based surveillance system should be

  17. [The cholera epidemic in Latin America].

    Science.gov (United States)

    Olsvik, O

    1992-05-30

    An outbreak of cholera started in Peru in January 1991 and spread through most Latin American countries within a year. This was the first known epidemic of cholera in America for more than a century. In 1991, 321,334 persons were reported to have cholera in Peru, 119,063 were hospitalized, and 2,906 died. Other countries like Ecuador, Colombia, Guatemala, Brazil, Mexico, Bolivia, Chile, El Salvador, Venezuela and Honduras were also affected, but these countries combined accounted for only 20% of the cases registered in Peru. In April 1992, all Latin American countries except Uruguay, Paraguay and French Guyana have reported cholera. The mortality rate for the epidemic in Latin America was only 1%, mainly owing to good oral rehydration treatment provided by Local health services and the Pan American Health Organization. The causative organism was Vibrio cholerae, serogroup O1, serotype Inaba (and Ogawa) of the El Tor biotype. Genetic characterization shows this strain to be unique, and the designation is reserved for the Latin American strain, distinguishing it from the other El Tor isolates from the 7th pandemic.

  18. 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.

  19. Estimating the transmission potential of supercritical processes based on the final size distribution of minor outbreaks.

    Science.gov (United States)

    Nishiura, Hiroshi; Yan, Ping; Sleeman, Candace K; Mode, Charles J

    2012-02-07

    Use of the final size distribution of minor outbreaks for the estimation of the reproduction numbers of supercritical epidemic processes has yet to be considered. We used a branching process model to derive the final size distribution of minor outbreaks, assuming a reproduction number above unity, and applying the method to final size data for pneumonic plague. Pneumonic plague is a rare disease with only one documented major epidemic in a spatially limited setting. Because the final size distribution of a minor outbreak needs to be normalized by the probability of extinction, we assume that the dispersion parameter (k) of the negative-binomial offspring distribution is known, and examine the sensitivity of the reproduction number to variation in dispersion. Assuming a geometric offspring distribution with k=1, the reproduction number was estimated at 1.16 (95% confidence interval: 0.97-1.38). When less dispersed with k=2, the maximum likelihood estimate of the reproduction number was 1.14. These estimates agreed with those published from transmission network analysis, indicating that the human-to-human transmission potential of the pneumonic plague is not very high. Given only minor outbreaks, transmission potential is not sufficiently assessed by directly counting the number of offspring. Since the absence of a major epidemic does not guarantee a subcritical process, the proposed method allows us to conservatively regard epidemic data from minor outbreaks as supercritical, and yield estimates of threshold values above unity. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  20. 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.

  1. 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

  2. Trends of major disease outbreaks in the African region, 2003-2007.

    Science.gov (United States)

    Kebede, Senait; Duales, Sambe; Yokouide, Allarangar; Alemu, Wondimagegnehu

    2010-03-01

    Communicable disease outbreaks cause millions of deaths throughout Sub-Saharan Africa each year. Most of the diseases causing epidemics in the region have been nearly eradicated or brought under control in other parts of the world. In recent years, considerable effort has been directed toward public health initiatives and strategies with a potential for significant impact in the fight against infectious diseases. In 1998, the World Health Organization African Regional Office (WHO/AFRO) launched the Integrated Disease Surveillance and Response (IDSR) strategy aimed at mitigating the impact of communicable diseases, including epidemic-prone diseases, through improving surveillance, laboratory confirmation and appropriate and timely public health interventions. Over the past decade, WHO and its partners have been providing technical and financial resources to African countries to strengthen epidemic preparedness and response (EPR) activities. This review examined the major epidemics reported to WHO/AFRO from 2003 to 2007. we conduct a review of documents and reports obtained from WHO/AFRO, WHO inter-country team, and partners and held meeting and discussions with key stakeholders to elicit the experiences of local, regional and international efforts against these epidemics to evaluate the lessons learned and to stimulate discussion on the future course for enhancing EPR. The most commonly reported epidemic outbreaks in Africa include: cholera, dysentery, malaria and hemorrhagic fevers (e.g. Ebola, Rift Valley fever, Crimean-Congo fever and yellow fever). The cyclic meningococcal meningitis outbreak that affects countries along the "meningitis belt" (spanning Sub-Saharan Africa from Senegal and The Gambia to Kenya and Ethiopia) accounts for other major epidemics in the region. The reporting of disease outbreaks to WHO/AFRO has improved since the launch of the IDSR strategy in 1998. Although the epidemic trends for cholera showed a decline in case fatality rate (CFR

  3. Sverdlovsk Anthrax Outbreak: An Educational Case Study

    Science.gov (United States)

    Steele, S. J.; van der Vink, G.

    2002-05-01

    In April and May of 1979 an Anthrax epidemic broke out in the city of Sverdlovsk (now Ekaterinburg) in the former Soviet Union. Sixty-four people were reported to have died from the outbreak, although there is still debate concerning the actual number of victims. While Soviet officials initially attributed this outbreak to contaminated meat, the US Government maintained that the outbreak was due to a leakage from a biological weapons facility. We have created and implemented an undergraduate educational exercise based on the forensic analysis of this event. Students were provided case data of the victims, area satellite images and meteorological data. One goal of the exercise was for students to reconstruct the most probable scenario of events through valid inference based on the limited information and uncertainties associated with the data set. Another goal was to make students sensitive to issues of biological weapons and bioterrorism. The exercise was highly rated by students even before the events of September 11. There is a clear need to educate students, particularly in the sciences, to be aware of the signatures of terrorist activities. Evidence of terrorist activities is more likely to appear from unintended discoveries than from active intelligence gathering. We believe our national security can be enhanced by sensitizing those that monitor the natural environment to the signatures of terrorist activities through the types of educational exercises that we have developed.

  4. [The new administration approach of the National Health System: implications for internal medicine. The point of view of the internist].

    Science.gov (United States)

    Marcon, G; Gardini, F; Voltan, G P

    1997-10-01

    The laws for the reform of the Italian National Health Service (502, 517) show marked bureaucratic and administrative patterns. The aim of these laws seems to be mainly a tight control of the health expenses instead of an improvement of health care. This choice is confirmed by the selection of indicators (DRG's) more fit for reimbursement rather than for quality assurance in health care. Moreover, these indicators are only a poor expression of the real medical status of the patients. The reform of the British NHS appears very similar to the Italian reform, mainly for the empowerment of managers to detriment of health professionals and of health care quality. The reforms designed with the collaboration of health workers may be more useful than the reforms based mainly upon bureaucratic principles. Only with this collaboration the double target of the reduction of health related costs and of the maintenance of an acceptable quality may be achieved. The professional associations and the academic world must be involved in the political and organisational choices related with health care, mainly in the fields of the setting of organisational standards and of the training of actual and future doctors. The model proposed is that of internal medicine as an example of the ideal set of skills useful for a mixed clinical and organisational task. The internists, used to the solution of complex clinical problems, may be the ideal candidates for the role of clinical managers.

  5. Investigation of an outbreak of Salmonella enterica serovar Newport infection.

    Science.gov (United States)

    Irvine, W N; Gillespie, I A; Smyth, F B; Rooney, P J; McClenaghan, A; Devine, M J; Tohani, V K

    2009-10-01

    A large outbreak of Salmonella enterica serotype Newport infection occurred in Northern Ireland during September and October 2004. Typing of isolates from patients confirmed that this strain was indistinguishable from that in concurrent outbreaks in regions of England, in Scotland and in the Isle of Man. A total of 130 cases were distributed unequally across local government district areas in Northern Ireland. The epidemic curve suggested a continued exposure over about 4 weeks. A matched case-control study of 23 cases and 39 controls found a statistically significant association with a history of having eaten lettuce in a meal outside the home and being a case (odds ratio 23.7, 95% confidence interval 1.4-404.3). This exposure was reported by 57% of cases. Although over 300 food samples were tested, none yielded any Salmonella spp. Complexity and limited traceability in salad vegetable distribution hindered further investigation of the ultimate source of the outbreak.

  6. Diphtheria outbreak with high mortality in northeastern Nigeria.

    Science.gov (United States)

    Besa, N C; Coldiron, M E; Bakri, A; Raji, A; Nsuami, M J; Rousseau, C; Hurtado, N; Porten, K

    2014-04-01

    SUMMARY A diphtheria outbreak occurred from February to November 2011 in the village of Kimba and its surrounding settlements, in Borno State, northeastern Nigeria. We conducted a retrospective outbreak investigation in Kimba village and the surrounding settlements to better describe the extent and clinical characteristics of this outbreak. Ninety-eight cases met the criteria of the case definition of diphtheria, 63 (64.3%) of whom were children aged diphtheria. None of the 98 cases received diphtheria antitoxin, penicillin, or erythromycin during their illness. The overall case-fatality ratio was 21.4%, and was highest in children aged 0-4 years (42.9%). Low rates of immunization, delayed clinical recognition of diphtheria and absence of treatment with antitoxin and appropriate antibiotics contributed to this epidemic and its severity.

  7. Surveillance and Outbreak Response Management System (SORMAS) to support the control of the Ebola virus disease outbreak in West Africa.

    Science.gov (United States)

    Fähnrich, C; Denecke, K; Adeoye, O O; Benzler, J; Claus, H; Kirchner, G; Mall, S; Richter, R; Schapranow, M P; Schwarz, N; Tom-Aba, D; Uflacker, M; Poggensee, G; Krause, G

    2015-03-26

    In the context of controlling the current outbreak of Ebola virus disease (EVD), the World Health Organization claimed that 'critical determinant of epidemic size appears to be the speed of implementation of rigorous control measures', i.e. immediate follow-up of contact persons during 21 days after exposure, isolation and treatment of cases, decontamination, and safe burials. We developed the Surveillance and Outbreak Response Management System (SORMAS) to improve efficiency and timeliness of these measures. We used the Design Thinking methodology to systematically analyse experiences from field workers and the Ebola Emergency Operations Centre (EOC) after successful control of the EVD outbreak in Nigeria. We developed a process model with seven personas representing the procedures of EVD outbreak control. The SORMAS system architecture combines latest In-Memory Database (IMDB) technology via SAP HANA (in-memory, relational database management system), enabling interactive data analyses, and established SAP cloud tools, such as SAP Afaria (a mobile device management software). The user interface consists of specific front-ends for smartphones and tablet devices, which are independent from physical configurations. SORMAS allows real-time, bidirectional information exchange between field workers and the EOC, ensures supervision of contact follow-up, automated status reports, and GPS tracking. SORMAS may become a platform for outbreak management and improved routine surveillance of any infectious disease. Furthermore, the SORMAS process model may serve as framework for EVD outbreak modeling.

  8. Outbreaks and Investigations

    Science.gov (United States)

    ... Who Gets Fungal Infections? People living with HIV/AIDS Organ Transplant Patients Cancer Patients Hospitalized Patients Stem Cell Transplant Patients Medications that Weaken Your Immune System Outbreaks Rhizopus Investigation CDC at Work Global Fungal Diseases Cryptococcal Meningitis ...

  9. Investigating Listeria Outbreaks

    Centers for Disease Control (CDC) Podcasts

    Dr. Emily Cartwright, Infectious Disease fellow at Emory University and former EIS Officer with CDC’s Division of Foodborne, Waterborne, and Environmental Diseases discusses foodborne Listeria outbreaks.

  10. National Outbreak Reporting System

    Data.gov (United States)

    U.S. Department of Health & Human Services — The National Outbreak Reporting System (NORS) is a web-based platform designed to support reporting to CDC by local, state, and territorial health departments in the...

  11. Study on the Occurrence and Epidemic Model of Rape Sclerotinia Stem Rot of ‘Zheyou 50’

    OpenAIRE

    Xu Sen-fu; Wang Hui-fu; Yu Shanhong; Wang En-guo

    2013-01-01

    In order to investigate invading and epidemic rules of rape sclerotinia stem rot of ‘Zheyou 50’ and promote the development of brassica campestris industry, this paper studied the outbreak regularity and epidemic model of rape sclerotinia stem rot according to field investigation and infection. The result showed that machinery direct seeding rape was good for the occurrence of sclerotinia stem rot for the reason of late seeding and high density. The period from water damage appeared to wiltin...

  12. 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.

  13. 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.

  14. Assessing node risk and vulnerability in epidemics on networks

    Science.gov (United States)

    Rogers, T.

    2015-01-01

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

  15. Mean-field level analysis of epidemics in directed networks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiazeng [School of Mathematical Sciences, Peking University, Beijing 100871 (China); Liu, Zengrong [Mathematics Department, Shanghai University, Shanghai 200444 (China)], E-mail: wangjiazen@yahoo.com.cn, E-mail: zrongliu@online.sh.cn

    2009-09-04

    The susceptible-infected-removed spreading model in a directed graph is studied. The mean-field level rate equations are built with the degree-degree connectivity correlation element and the (in, out)-degree distribution. And the outbreak threshold is obtained analytically-it is determined by the combination of connectivity probability and the degree distribution. Furthermore, the methods of calculating the degree-degree correlations in directed networks are presented. The numerical results of the discrete epidemic processes in networks verify our analyses.

  16. Mean-field level analysis of epidemics in directed networks

    International Nuclear Information System (INIS)

    Wang, Jiazeng; Liu, Zengrong

    2009-01-01

    The susceptible-infected-removed spreading model in a directed graph is studied. The mean-field level rate equations are built with the degree-degree connectivity correlation element and the (in, out)-degree distribution. And the outbreak threshold is obtained analytically-it is determined by the combination of connectivity probability and the degree distribution. Furthermore, the methods of calculating the degree-degree correlations in directed networks are presented. The numerical results of the discrete epidemic processes in networks verify our analyses.

  17. The importance of thinking beyond the water-supply in cholera epidemics

    DEFF Research Database (Denmark)

    Phelps, Matthew D.; Azman, Andrew S.; Lewnard, Joseph A.

    2017-01-01

    the contribution of long-cycle waterborne transmission between neighborhoods using historical municipal water infrastructure data, fitting the force of infection from hydraulic flow, then comparing model performance. We found the epidemic was characterized by considerable transmission heterogeneity. Some...... municipal water quality. We recommend public health planners consider programs aimed at interrupting short-cycle transmission as essential tools in the cholera control arsenal. Author summary: John Snow’s seminal work on the London cholera epidemic and Broadway pump helped establish cholera......-cycle transmission to the epidemic. We find transmission between neighborhoods during the epidemic did not follow water pipe connections, suggesting little evidence of long-cycle transmission. Instead, we suggest that short-cycle transmission was likely critical to the propagation of the outbreak. Interventions...

  18. 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.

  19. Time evolution of predictability of epidemics on networks

    Science.gov (United States)

    Holme, Petter; Takaguchi, Taro

    2015-04-01

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

  20. 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...

  1. Impact of Severe Acute Respiratory Syndrome (SARS Outbreaks on the Use of Emergency Department Medical Resources

    Directory of Open Access Journals (Sweden)

    Chien-Cheng Huang

    2005-06-01

    Conclusion: The SARS outbreak did not eliminate the need of critically ill patients for advanced medical support. However, besides an overall decrease in patient numbers, the SARS epidemic markedly altered demographic information, clinical characteristics, and the use of medical services by adult patients in the ED of a SARS-dedicated hospital.

  2. Outbreak of avian influenza H7N3 on a turkey farm in the Netherlands

    NARCIS (Netherlands)

    Velkers, F.C.; Bouma, A.; Matthijs, M.G.R.; Koch, G.; Westendorp, S.T.; Stegeman, J.A.

    2006-01-01

    This case report describes the course of an outbreak of avian influenza on a Dutch turkey farm. When clinical signs were observed their cause remained unclear. However, serum samples taken for the monitoring campaign launched during the epidemic of highly pathogenic avian influenza in 2003, showed

  3. Increased Rotavirus Prevalence in Diarrheal Outbreak Precipitated by Localized Flooding, Solomon Islands, 2014.

    Science.gov (United States)

    Jones, Forrest K; Ko, Albert I; Becha, Chris; Joshua, Cynthia; Musto, Jennie; Thomas, Sarah; Ronsse, Axelle; Kirkwood, Carl D; Sio, Alison; Aumua, Audrey; Nilles, Eric J

    2016-05-01

    Flooding on 1 of the Solomon Islands precipitated a nationwide epidemic of diarrhea that spread to regions unaffected by flooding and caused >6,000 cases and 27 deaths. Rotavirus was identified in 38% of case-patients tested in the city with the most flooding. Outbreak potential related to weather reinforces the need for global rotavirus vaccination.

  4. An outbreak of gastroenteritis due to Escherichia coli 0142 H6 in a neonatal department

    NARCIS (Netherlands)

    Gerards, L. J.; Hennekam, R. C.; von Dijk, W. C.; Roord, J. J.; Fleer, A.

    1984-01-01

    An outbreak of gastroenteritis due to Escherichia coli 0142 H6 in a neonatal ward is described. The epidemic affected 16 of 24 infants (infection-rate 66 per cent), of whom one died due to necrotizing enterocolitis. Administration of antibiotics was of limited value in treatment or in eradicating E.

  5. Social Network Sensors for Early Detection of Contagious Outbreaks

    Science.gov (United States)

    Christakis, Nicholas A.; Fowler, James H.

    2010-01-01

    Current methods for the detection of contagious outbreaks give contemporaneous information about the course of an epidemic at best. It is known that individuals near the center of a social network are likely to be infected sooner during the course of an outbreak, on average, than those at the periphery. Unfortunately, mapping a whole network to identify central individuals who might be monitored for infection is typically very difficult. We propose an alternative strategy that does not require ascertainment of global network structure, namely, simply monitoring the friends of randomly selected individuals. Such individuals are known to be more central. To evaluate whether such a friend group could indeed provide early detection, we studied a flu outbreak at Harvard College in late 2009. We followed 744 students who were either members of a group of randomly chosen individuals or a group of their friends. Based on clinical diagnoses, the progression of the epidemic in the friend group occurred 13.9 days (95% C.I. 9.9–16.6) in advance of the randomly chosen group (i.e., the population as a whole). The friend group also showed a significant lead time (pepidemic, a full 46 days before the peak in daily incidence in the population as a whole. This sensor method could provide significant additional time to react to epidemics in small or large populations under surveillance. The amount of lead time will depend on features of the outbreak and the network at hand. The method could in principle be generalized to other biological, psychological, informational, or behavioral contagions that spread in networks. PMID:20856792

  6. Strategies for Early Outbreak Detection of Malaria in the Amhara Region of Ethiopia

    Science.gov (United States)

    Nekorchuk, D.; Gebrehiwot, T.; Mihretie, A.; Awoke, W.; Wimberly, M. C.

    2017-12-01

    Traditional epidemiological approaches to early detection of disease outbreaks are based on relatively straightforward thresholds (e.g. 75th percentile, standard deviations) estimated from historical case data. For diseases with strong seasonality, these can be modified to create separate thresholds for each seasonal time step. However, for disease processes that are non-stationary, more sophisticated techniques are needed to more accurately estimate outbreak threshold values. Early detection for geohealth-related diseases that also have environmental drivers, such as vector-borne diseases, may also benefit from the integration of time-lagged environmental data and disease ecology models into the threshold calculations. The Epidemic Prognosis Incorporating Disease and Environmental Monitoring for Integrated Assessment (EPIDEMIA) project has been integrating malaria case surveillance with remotely-sensed environmental data for early detection, warning, and forecasting of malaria epidemics in the Amhara region of Ethiopia, and has five years of weekly time series data from 47 woredas (districts). Efforts to reduce the burden of malaria in Ethiopia has been met with some notable success in the past two decades with major reduction in cases and deaths. However, malaria remains a significant public health threat as 60% of the population live in malarious areas, and due to the seasonal and unstable transmission patterns with cyclic outbreaks, protective immunity is generally low which could cause high morbidity and mortality during the epidemics. This study compared several approaches for defining outbreak thresholds and for identifying a potential outbreak based on deviations from these thresholds. We found that model-based approaches that accounted for climate-driven seasonality in malaria transmission were most effective, and that incorporating a trend component improved outbreak detection in areas with active malaria elimination efforts. An advantage of these early

  7. Multiple origins of outbreak populations of a native insect pest in an agro-ecosystem.

    Science.gov (United States)

    Kobayashi, T; Sakurai, T; Sakakibara, M; Watanabe, T

    2011-06-01

    Native insects can become epidemic pests in agro-ecosystems. A population genetics approach was applied to analyze the emergence and spread of outbreak populations of native insect species. Outbreaks of the mirid bug, Stenotus rubrovittatus, have rapidly expanded over Japan within the last two decades. To characterize the outbreak dynamics of this species, the genetic structure of local populations was assessed using polymorphisms of the mtDNA COI gene and six microsatellite loci. Results of the population genetic analysis suggested that S. rubrovittatus populations throughout Japan were genetically isolated by geographic distance and separated into three genetic clusters occupying spatially segregated regions. Phylogeographic analysis indicated that the genetic structure of S. rubrovittatus reflected post-glacial colonization. Early outbreaks of S. rubrovittatus in the 1980s occurred independently of genetically isolated populations. The genetic structure of the populations did not fit the pattern of an outbreak expansion, and therefore the data did not support the hypothesis that extensive outbreaks were caused by the dispersal of specific pestiferous populations. Rather, the historical genetic structure prior to the outbreaks was maintained throughout the increase in abundance of the mirid bug. Our study indicated that changes in the agro-environment induced multiple outbreaks of native pest populations. This implies that, given suitable environmental conditions, local populations may have the potential to outbreak even without invasion of populations from other environmentally degraded areas.

  8. Entomologic investigations during an outbreak of West Nile virus disease in Maricopa County, Arizona, 2010.

    Science.gov (United States)

    Godsey, Marvin S; Burkhalter, Kristen; Young, Ginger; Delorey, Mark; Smith, Kirk; Townsend, John; Levy, Craig; Mutebi, John-Paul

    2012-12-01

    Entomologic investigations were conducted during an intense outbreak of West Nile virus (WNV) disease in Maricopa County, Arizona during July 31-August 9, 2010. The investigations compared the East Valley outbreak area, and a demographically similar control area in northwestern metropolitan Phoenix where no human cases were reported. Five mosquito species were identified in each area, and species composition was similar in both areas. Significantly more Culex quinquefasciatus females were collected by gravid traps at Outbreak sites (22.2 per trap night) than at control sites (8.9 per trap night), indicating higher Cx. quinquefasciatus abundance in the outbreak area. Twenty-eight WNV TaqMan reverse transcription-polymerase chain reaction-positive mosquito pools were identified, including 24 of Cx. quinquefasciatus, 3 of Psorophora columbiae, and 1 of Culex sp. However, Cx. quinquefasciatus WNV infection rates did not differ between outbreak and control sites. At outbreak sites, 30 of 39 engorged Cx. quinquefasciatus had fed on birds, 8 of 39 on humans, and 1 of 39 on a lizard. At control sites, 20 of 20 identified blood meals were from birds. Data suggest that Cx. quinquefasciatus was the primary enzootic and epidemic vector of this outbreak. The most important parameters in the outbreak were vector abundance and blood meal analysis, which suggested more frequent contact between Cx. quinquefasciatus and human hosts in the outbreak area compared with the control area.

  9. An outbreak of Ebola in Uganda.

    Science.gov (United States)

    Okware, S I; Omaswa, F G; Zaramba, S; Opio, A; Lutwama, J J; Kamugisha, J; Rwaguma, E B; Kagwa, P; Lamunu, M

    2002-12-01

    An outbreak of Ebola disease was reported from Gulu district, Uganda, on 8 October 2000. The outbreak was characterized by fever and haemorrhagic manifestations, and affected health workers and the general population of Rwot-Obillo, a village 14 km north of Gulu town. Later, the outbreak spread to other parts of the country including Mbarara and Masindi districts. Response measures included surveillance, community mobilization, case and logistics management. Three coordination committees were formed: National Task Force (NTF), a District Task Force (DTF) and an Interministerial Task Force (IMTF). The NTF and DTF were responsible for coordination and follow-up of implementation of activities at the national and district levels, respectively, while the IMTF provided political direction and handled sensitive issues related to stigma, trade, tourism and international relations. The international response was coordinated by the World Health Organization (WHO) under the umbrella organization of the Global Outbreak and Alert Response Network. A WHO/CDC case definition for Ebola was adapted and used to capture four categories of cases, namely, the 'alert', 'suspected', 'probable' and 'confirmed cases'. Guidelines for identification and management of cases were developed and disseminated to all persons responsible for surveillance, case management, contact tracing and Information Education Communication (IEC). For the duration of the epidemic that lasted up to 16 January 2001, a total of 425 cases with 224 deaths were reported countrywide. The case fatality rate was 53%. The attack rate (AR) was highest in women. The average AR for Gulu district was 12.6 cases/10 000 inhabitants when the contacts of all cases were considered and was 4.5 cases/10 000 if limited only to contacts of laboratory confirmed cases. The secondary AR was 2.5% when nearly 5000 contacts were followed up for 21 days. Uganda was finally declared Ebola free on 27 February 2001, 42 days after the last case

  10. Early rigorous control interventions can largely reduce dengue outbreak magnitude: experience from Chaozhou, China.

    Science.gov (United States)

    Liu, Tao; Zhu, Guanghu; He, Jianfeng; Song, Tie; Zhang, Meng; Lin, Hualiang; Xiao, Jianpeng; Zeng, Weilin; Li, Xing; Li, Zhihao; Xie, Runsheng; Zhong, Haojie; Wu, Xiaocheng; Hu, Wenbiao; Zhang, Yonghui; Ma, Wenjun

    2017-08-02

    Dengue fever is a severe public heath challenge in south China. A dengue outbreak was reported in Chaozhou city, China in 2015. Intensified interventions were implemented by the government to control the epidemic. However, it is still unknown the degree to which intensified control measures reduced the size of the epidemics, and when should such measures be initiated to reduce the risk of large dengue outbreaks developing? We selected Xiangqiao district as study setting because the majority of the indigenous cases (90.6%) in Chaozhou city were from this district. The numbers of daily indigenous dengue cases in 2015 were collected through the national infectious diseases and vectors surveillance system, and daily Breteau Index (BI) data were reported by local public health department. We used a compartmental dynamic SEIR (Susceptible, Exposed, Infected and Removed) model to assess the effectiveness of control interventions, and evaluate the control effect of intervention timing on dengue epidemic. A total of 1250 indigenous dengue cases was reported from Xiangqiao district. The results of SEIR modeling using BI as an indicator of actual control interventions showed a total of 1255 dengue cases, which is close to the reported number (n = 1250). The size and duration of the outbreak were highly sensitive to the intensity and timing of interventions. The more rigorous and earlier the control interventions implemented, the more effective it yielded. Even if the interventions were initiated several weeks after the onset of the dengue outbreak, the interventions were shown to greatly impact the prevalence and duration of dengue outbreak. This study suggests that early implementation of rigorous dengue interventions can effectively reduce the epidemic size and shorten the epidemic duration.

  11. Early rigorous control interventions can largely reduce dengue outbreak magnitude: experience from Chaozhou, China

    Directory of Open Access Journals (Sweden)

    Tao Liu

    2017-08-01

    Full Text Available Abstract Background Dengue fever is a severe public heath challenge in south China. A dengue outbreak was reported in Chaozhou city, China in 2015. Intensified interventions were implemented by the government to control the epidemic. However, it is still unknown the degree to which intensified control measures reduced the size of the epidemics, and when should such measures be initiated to reduce the risk of large dengue outbreaks developing? Methods We selected Xiangqiao district as study setting because the majority of the indigenous cases (90.6% in Chaozhou city were from this district. The numbers of daily indigenous dengue cases in 2015 were collected through the national infectious diseases and vectors surveillance system, and daily Breteau Index (BI data were reported by local public health department. We used a compartmental dynamic SEIR (Susceptible, Exposed, Infected and Removed model to assess the effectiveness of control interventions, and evaluate the control effect of intervention timing on dengue epidemic. Results A total of 1250 indigenous dengue cases was reported from Xiangqiao district. The results of SEIR modeling using BI as an indicator of actual control interventions showed a total of 1255 dengue cases, which is close to the reported number (n = 1250. The size and duration of the outbreak were highly sensitive to the intensity and timing of interventions. The more rigorous and earlier the control interventions implemented, the more effective it yielded. Even if the interventions were initiated several weeks after the onset of the dengue outbreak, the interventions were shown to greatly impact the prevalence and duration of dengue outbreak. Conclusions This study suggests that early implementation of rigorous dengue interventions can effectively reduce the epidemic size and shorten the epidemic duration.

  12. Planning for smallpox outbreaks

    Science.gov (United States)

    Ferguson, Neil M.; Keeling, Matt J.; John Edmunds, W.; Gani, Raymond; Grenfell, Bryan T.; Anderson, Roy M.; Leach, Steve

    2003-10-01

    Mathematical models of viral transmission and control are important tools for assessing the threat posed by deliberate release of the smallpox virus and the best means of containing an outbreak. Models must balance biological realism against limitations of knowledge, and uncertainties need to be accurately communicated to policy-makers. Smallpox poses the particular challenge that key biological, social and spatial factors affecting disease spread in contemporary populations must be elucidated largely from historical studies undertaken before disease eradication in 1979. We review the use of models in smallpox planning within the broader epidemiological context set by recent outbreaks of both novel and re-emerging pathogens.

  13. OmpU as a biomarker for rapid discrimination between toxigenic and epidemic Vibrio cholerae O1/O139 and non-epidemic Vibrio cholerae in a modified MALDI-TOF MS assay

    NARCIS (Netherlands)

    Paauw, A.; Trip, H.; Niemcewicz, M.; Sellek, R.; Heng, J.M.E.; Mars-Groenendijk, R.H.; Jong, A.L. de; Majchrzykiewicz-Koehorst, J.A.; Olsen, J.S.; Tsivtsivadze, E.

    2014-01-01

    Background Cholera is an acute diarrheal disease caused by Vibrio cholerae. Outbreaks are caused by a genetically homogenous group of strains from serogroup O1 or O139 that are able to produce the cholera toxin. Rapid detection and identification of these epidemic strains is essential for an

  14. The Social Impact of Communication during Epidemics: Bioethical and Public Health Perspectives

    Directory of Open Access Journals (Sweden)

    Eduardo Alfredo Duro

    2018-06-01

    Full Text Available Public health communication and, especially during a crisis scenario such as an epidemics, is mediated by ethical conflicts ranging from values to deontology. In an intercommunicated world, the social support during outbreaks and epidemics becomes global and the state presence is a key to social protection. This should also be translated into timely, urgent and effective communication strategies from the public health perspective as well as efforts to prevent and avoid fake news or skewed information from any sources. Scenarios with lack of connection and obstacles in mass communication in public health major threats are described.

  15. 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.

  16. 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.

  17. [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.

  18. Hurricanes, climate change and the cholera epidemic in Puerto Rico of 1855-1856.

    Science.gov (United States)

    Christenson, Bernard

    2008-01-01

    Hurricanes and global climate changes may affect the environmental factors of cholera dynamics in warm coastal areas, vulnerable to seasonal or sporadic outbreaks. The cholera epidemic of Puerto Rico in 1855-1856 had a profound effect on the Puerto Rican society; but it was not influenced by any climatic events, such as preceding hurricanes or storms based on past documentary sources. Particularly, the environmental non-toxigenic strains of Vibrio Cholerae in Puerto Rican water sources can maintain their pathogenic potential for sporadic or erratic toxigenic cholera outbreaks--if a "perfect storm" ever occurs.

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

    NARCIS (Netherlands)

    Garza, D.R.; Thompson, C.C.; Loureiro, E.C.; Dutilh, B.E.; Inada, D.T.; Junior, E.C.; Cardoso, J.F.; Nunes, M.R.; Lima, C.P. de; Silvestre, R.V.; Nunes, K.N.; Santos, E.C.; Edwards, R.A.; Vicente, A.C.; Sa Morais, L.L. de

    2012-01-01

    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

  20. 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.

  1. Extreme weather events and infectious disease outbreaks.

    Science.gov (United States)

    McMichael, Anthony J

    2015-01-01

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

  2. Core Genome Multilocus Sequence Typing for Identification of Globally Distributed Clonal Groups and Differentiation of Outbreak Strains of Listeria monocytogenes

    OpenAIRE

    Chen, Yi; Gonzalez-Escalona, Narjol; Hammack, Thomas S.; Allard, Marc W.; Strain, Errol A.; Brown, Eric W.

    2016-01-01

    ABSTRACT Many listeriosis outbreaks are caused by a few globally distributed clonal groups, designated clonal complexes or epidemic clones, of Listeria monocytogenes, several of which have been defined by classic multilocus sequence typing (MLST) schemes targeting 6 to 8 housekeeping or virulence genes. We have developed and evaluated core genome MLST (cgMLST) schemes and applied them to isolates from multiple clonal groups, including those associated with 39 listeriosis outbreaks. The cgMLST...

  3. Responding to Outbreaks

    Centers for Disease Control (CDC) Podcasts

    2009-04-27

    In this podcast, a team of CDC specialists travels to Uganda and tracks the source of an Ebola outbreak where CDC scientists are studying bats for clues to the Ebola mystery.  Created: 4/27/2009 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 4/27/2009.

  4. Investigating Listeria Outbreaks

    Centers for Disease Control (CDC) Podcasts

    2013-01-04

    Dr. Emily Cartwright, Infectious Disease fellow at Emory University and former EIS Officer with CDC’s Division of Foodborne, Waterborne, and Environmental Diseases discusses foodborne Listeria outbreaks.  Created: 1/4/2013 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 1/8/2013.

  5. Foodborne Norovirus Outbreaks

    Centers for Disease Control (CDC) Podcasts

    2012-09-17

    Dr. Aron Hall, a CDC epidemiologist specializing in noroviruses, discusses foodborne norovirus outbreaks.  Created: 9/17/2012 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID); National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/17/2012.

  6. 19th-century and early 20th-century jaundice outbreaks, the USA.

    Science.gov (United States)

    Teo, C G

    2018-01-01

    Historical enquiry into diseases with morbidity or mortality predilections for particular demographic groups can permit clarification of their emergence, endemicity, and epidemicity. During community-wide outbreaks of hepatitis A in the pre-vaccine era, clinical attack rates were higher among juveniles rather than adults. In community-wide hepatitis E outbreaks, past and present, mortality rates have been most pronounced among pregnant women. Examination for these characteristic predilections in reports of jaundice outbreaks in the USA traces the emergence of hepatitis A and also of hepatitis E to the closing three decades of the 19th century. Thereafter, outbreaks of hepatitis A burgeoned, whereas those of hepatitis E abated. There were, in addition, community-wide outbreaks that bore features of neither hepatitis A nor E; they occurred before the 1870s. The American Civil War antedated that period. If hepatitis A had yet to establish endemicity, then it would not underlie the jaundice epidemic that was widespread during the war. Such an assessment may be revised, however, with the discovery of more extant outbreak reports.

  7. 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.

  8. Genomic characterization of a large outbreak of Legionella pneumophila serogroup 1 strains in Quebec City, 2012.

    Directory of Open Access Journals (Sweden)

    Simon Lévesque

    Full Text Available During the summer of 2012, a major Legionella pneumophila serogroup 1 outbreak occurred in Quebec City, Canada, which caused 182 declared cases of Legionnaire's disease and included 13 fatalities. Legionella pneumophila serogroup 1 isolates from 23 patients as well as from 32 cooling towers located in the vicinity of the outbreak were recovered for analysis. In addition, 6 isolates from the 1996 Quebec City outbreak and 4 isolates from patients unrelated to both outbreaks were added to allow comparison. We characterized the isolates using pulsed-field gel electrophoresis, sequence-based typing, and whole genome sequencing. The comparison of patients-isolated strains to cooling tower isolates allowed the identification of the tower that was the source of the outbreak. Legionella pneumophila strain Quebec 2012 was identified as a ST-62 by sequence-based typing methodology. Two new Legionellaceae plasmids were found only in the epidemic strain. The LVH type IV secretion system was found in the 2012 outbreak isolates but not in the ones from the 1996 outbreak and only in half of the contemporary human isolates. The epidemic strains replicated more efficiently and were more cytotoxic to human macrophages than the environmental strains tested. At least four Icm/Dot effectors in the epidemic strains were absent in the environmental strains suggesting that some effectors could impact the intracellular replication in human macrophages. Sequence-based typing and pulsed-field gel electrophoresis combined with whole genome sequencing allowed the identification and the analysis of the causative strain including its likely environmental source.

  9. Influenza outbreak during Sydney World Youth Day 2008: the utility of laboratory testing and case definitions on mass gathering outbreak containment.

    Directory of Open Access Journals (Sweden)

    Sebastiaan J van Hal

    Full Text Available BACKGROUND: Influenza causes annual epidemics and often results in extensive outbreaks in closed communities. To minimize transmission, a range of interventions have been suggested. For these to be effective, an accurate and timely diagnosis of influenza is required. This is confirmed by a positive laboratory test result in an individual whose symptoms are consistent with a predefined clinical case definition. However, the utility of these clinical case definitions and laboratory testing in mass gathering outbreaks remains unknown. METHODS AND RESULTS: An influenza outbreak was identified during World Youth Day 2008 in Sydney. From the data collected on pilgrims presenting to a single clinic, a Markov model was developed and validated against the actual epidemic curve. Simulations were performed to examine the utility of different clinical case definitions and laboratory testing strategies for containment of influenza outbreaks. Clinical case definitions were found to have the greatest impact on averting further cases with no added benefit when combined with any laboratory test. Although nucleic acid testing (NAT demonstrated higher utility than indirect immunofluorescence antigen or on-site point-of-care testing, this effect was lost when laboratory NAT turnaround times was included. The main benefit of laboratory confirmation was limited to identification of true influenza cases amenable to interventions such as antiviral therapy. CONCLUSIONS: Continuous re-evaluation of case definitions and laboratory testing strategies are essential for effective management of influenza outbreaks during mass gatherings.

  10. Internet and free press are associated with reduced lags in global outbreak reporting.

    Science.gov (United States)

    McAlarnen, Lindsey; Smith, Katherine; Brownstein, John S; Jerde, Christopher

    2014-10-30

    Global outbreak detection and reporting have generally improved for a variety of infectious diseases and geographic regions in recent decades. Nevertheless, lags in outbreak reporting remain a threat to the global human health and economy. In the time between first occurrence of a novel disease incident and public notification of an outbreak, infected individuals have a greater possibility of traveling and spreading the pathogen to other nations. Shortening outbreak reporting lags has the potential to improve global health by preventing local outbreaks from escalating into global epidemics. Reporting lags between the first record and the first public report of an event were calculated for 318 outbreaks occurring 1996-2009. The influence of freedom of the press, Internet usage, per capita health expenditure, and cell phone subscriptions, on the timeliness of outbreak reporting was evaluated. Freer presses and increasing Internet usage correlate with reduced time between the first record of an outbreak and the public report. Increasing Internet usage reduced the expected reporting lag from more than one month in nations without Internet users to one day in those where 75 of 100 people use the Internet. Advances in technology and the emergence of more open and free governments are associated with to improved global infectious disease surveillance.

  11. 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

  12. Perspectives on model forecasts of the 2014-2015 Ebola epidemic in West Africa

    DEFF Research Database (Denmark)

    Chowell, Gerardo; Viboud, Cécile; Simonsen, Lone

    2017-01-01

    The unprecedented impact and modeling efforts associated with the 2014–2015 Ebola epidemic in West Africa provides a unique opportunity to document the performances and caveats of forecasting approaches used in near-real time for generating evidence and to guide policy. A number of international...... academic groups have developed and parameterized mathematical models of disease spread to forecast the trajectory of the outbreak. These modeling efforts often relied on limited epidemiological data to derive key transmission and severity parameters, which are needed to calibrate mechanistic models. Here...... changes and case clustering; (3) challenges in forecasting the long-term epidemic impact very early in the outbreak; and (4) ways to move forward. We conclude that rapid availability of aggregated population-level data and detailed information on a subset of transmission chains is crucial to characterize...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. [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.

  19. A local outbreak of dengue caused by an imported case in Dongguan China

    Directory of Open Access Journals (Sweden)

    Peng Hong-Juan

    2012-01-01

    Full Text Available Abstract Background Dengue, a mosquito-borne febrile viral disease, is found in tropical and sub-tropical regions around the world. Since the first occurrence of dengue was confirmed in Guangdong, China in 1978, dengue outbreaks have been reported sequentially in different provinces in South China transmitted by.peridomestic Ae. albopictus mosquitoes, diplaying Ae. aegypti, a fully domestic vector that transmits dengue worldwide. Rapid and uncontrolled urbanization is a characteristic change in developing countries, which impacts greatly on vector habitat, human lifestyle and transmission dynamics on dengue epidemics. In September 2010, an outbreak of dengue was detected in Dongguan, a city in Guangdong province characterized by its fast urbanization. An investigation was initiated to identify the cause, to describe the epidemical characteristics of the outbreak, and to implement control measures to stop the outbreak. This is the first report of dengue outbreak in Dongguan, even though dengue cases were documented before in this city. Methods Epidemiological data were obtained from local Center of Disease Control and prevention (CDC. Laboratory tests such as real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR, the virus cDNA sequencing, and Enzyme-Linked immunosorbent assay (ELISA were employed to identify the virus infection and molecular phylogenetic analysis was performed with MEGA5. The febrile cases were reported every day by the fever surveillance system. Vector control measures including insecticidal fogging and elimination of habitats of Ae. albopictus were used to control the dengue outbreak. Results The epidemiological studies results showed that this dengue outbreak was initiated by an imported case from Southeast Asia. The outbreak was characterized by 31 cases reported with an attack rate of 50.63 out of a population of 100,000. Ae. albopictus was the only vector species responsible for the outbreak. The virus c

  20. 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...

  1. First Isolation of Dengue Virus from the 2010 Epidemic in Nepal

    OpenAIRE

    Pandey, Basu D.; Nabeshima, Takeshi; Pandey, Kishor; Rajendra, Saroj P.; Shah, Yogendra; Adhikari, Bal R.; Gupta, Govinda; Gautam, Ishan; Tun, Mya M. N.; Uchida, Reo; Shrestha, Mahendra; Kurane, Ichiro; Morita, Kouichi

    2013-01-01

    Denguei is an emerging disease in Nepal and was first observed as an outbreak in nine lowland districts in 2006. In 2010, however, a large epidemic of dengue occurred with 4,529 suspected and 917 serologicallyconfirmed cases and five deaths reported in government hospitals in Nepal. The collection of demographic information was performed along with an entomological survey and clinical evaluation of the patients. A total of 280 serum samples were collected from suspected dengue patients. These...

  2. Yellow fever cases in Asia: primed for an epidemic.

    Science.gov (United States)

    Wasserman, Sean; Tambyah, Paul Anantharajah; Lim, Poh Lian

    2016-07-01

    There is currently an emerging outbreak of yellow fever in Angola. Cases in infected travellers have been reported in a number of other African countries, as well as in China, representing the first ever documented cases of yellow fever in Asia. There is a large Chinese workforce in Angola, many of whom may be unvaccinated, increasing the risk of ongoing importation of yellow fever into Asia via busy commercial airline routes. Large parts of the region are hyperendemic for the related Flavivirus dengue and are widely infested by Aedes aegypti, the primary mosquito vector of urban yellow fever transmission. The combination of sustained introduction of viraemic travellers, an ecology conducive to local transmission, and an unimmunized population raises the possibility of a yellow fever epidemic in Asia. This represents a major global health threat, particularly in the context of a depleted emergency vaccine stockpile and untested surveillance systems in the region. In this review, the potential for a yellow fever outbreak in Asia is discussed with reference to the ecological and historical forces that have shaped global yellow fever epidemiology. The limitations of surveillance and vector control in the region are highlighted, and priorities for outbreak preparedness and response are suggested. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  3. 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.

  4. Yellow fever cases in Asia: primed for an epidemic

    Directory of Open Access Journals (Sweden)

    Sean Wasserman

    2016-07-01

    Full Text Available There is currently an emerging outbreak of yellow fever in Angola. Cases in infected travellers have been reported in a number of other African countries, as well as in China, representing the first ever documented cases of yellow fever in Asia. There is a large Chinese workforce in Angola, many of whom may be unvaccinated, increasing the risk of ongoing importation of yellow fever into Asia via busy commercial airline routes. Large parts of the region are hyperendemic for the related Flavivirus dengue and are widely infested by Aedes aegypti, the primary mosquito vector of urban yellow fever transmission. The combination of sustained introduction of viraemic travellers, an ecology conducive to local transmission, and an unimmunized population raises the possibility of a yellow fever epidemic in Asia. This represents a major global health threat, particularly in the context of a depleted emergency vaccine stockpile and untested surveillance systems in the region. In this review, the potential for a yellow fever outbreak in Asia is discussed with reference to the ecological and historical forces that have shaped global yellow fever epidemiology. The limitations of surveillance and vector control in the region are highlighted, and priorities for outbreak preparedness and response are suggested.

  5. Epidemiological Investigation of an Outbreak of Viral Hepatitis.

    Science.gov (United States)

    Singh, Pmp; Handa, S K; Banerjee, A

    2006-10-01

    There was a rise in the number of viral hepatitis cases in a regimental training centre in Mar 2003 and an epidemic of viral hepatitis was suspected. The clinical case sheets and preliminary investigations carried out in the local military hospital (MH) were reviewed. A cross sectional descriptive epidemiological study was undertaken with survey odf the suspected sewage and water pipelines. A total of 36 cases occurred from Mar 2003 to Apr 2003. There was clustering in time and space suggesting common source epidemic. All the 36 serum samples tested for IgM anti HEV antibodies were positive. Exploration of the water pipelines revealed sewage contamination due to leakage in the pipeline passing close to the sewage line. The overall attack rate was 1.44%. The outbreak of viral hepatitis in the regimental training centre occurred due to sewage contamination of drinking water pipeline.

  6. A spatially explicit model for the future progression of the current Haiti cholera epidemic

    Science.gov (United States)

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

    2011-12-01

    As a major cholera epidemic progresses in Haiti, and the figures of the infection, up to July 2011, climb to 385,000 cases and 5,800 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 textit{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 texttrademark project). The model directly account 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. 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, clean water supply and educational campaigns, thus emerging as an essential component of the control of future cholera

  7. 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.

  8. Measles Elimination Efforts and 2008–2011 Outbreak, France

    Science.gov (United States)

    Lévy-Bruhl, Daniel; Baudon, Claire; Freymuth, François; Lamy, Mathieu; Maine, Catherine; Floret, Daniel; Parent du Chatelet, Isabelle

    2013-01-01

    Although few measles cases were reported in France during 2006 and 2007, suggesting the country might have been close to eliminating the disease, a dramatic outbreak of >20,000 cases occurred during 2008–2011. Adolescents and young adults accounted for more than half of cases; median patient age increased from 12 to 16 years during the outbreak. The highest incidence rate was observed in children <1 year of age, reaching 135 cases/100,000 infants during the last epidemic wave. Almost 5,000 patients were hospitalized, including 1,023 for severe pneumonia and 27 for encephalitis/myelitis; 10 patients died. More than 80% of the cases during this period occurred in unvaccinated persons, reflecting heterogeneous vaccination coverage, where pockets of susceptible persons still remain. Although vaccine coverage among children improved, convincing susceptible young adults to get vaccinated remains a critical issue if the target to eliminate the disease by 2015 is to be met. PMID:23618523

  9. Progression of Ebola Therapeutics During the 2014-2015 Outbreak.

    Science.gov (United States)

    Mendoza, Emelissa J; Qiu, Xiangguo; Kobinger, Gary P

    2016-02-01

    The recent Ebola virus (EBOV) outbreak in West Africa was the deadliest EBOV epidemic in history, highlighting the need for a safe and efficacious treatment against EBOV disease (EVD). In the absence of an approved treatment, experimental drugs were utilized under compassionate grounds hoping to diminish EVD-associated morbidity and mortality. As more data were collected from safety studies, Phase II/III clinical trials were introduced in Guinea, Sierra Leone, and Liberia to test promising candidates, including small-molecule drugs, RNA-based treatments, and antibody-based therapies. In this review, we summarize the use of, and preliminary observations from, current clinical trials with EVD therapeutics, shedding light on experimental drug selection, emergency clinical evaluation, and the impact these factors may have on future infectious disease outbreaks. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  10. 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.

  11. 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.

  12. 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.

  13. An outbreak of Vibrio cholerae in Vikas Nagar, Chandigarh, India

    Directory of Open Access Journals (Sweden)

    Sonia Puri

    2014-01-01

    Full Text Available Background : On 1 July 2012, a large number of cases of acute diarrheal episodes were reported in Vikas Nagar, Chandigarh. A rapid response team was sent to investigate this outbreak on 3 July 2012. Aim : To determine the reasons for the outbreak and to focus on the identification of a gap in the management of the epidemic by applying remedial measures in the Vibrio cholera outbreak in the Vikas Nagar area of Chandigarh district. Materials and Methods : A house-to-house survey of 2765 houses was performed with 20 teams of Auxillary Nurse Midwife ANM/Anganwadi workers. Information regarding age, sex, place of residence, occupation, date of onset and treatment history and laboratory finding were collected. Environmental investigation and laboratory investigation of the stool samples were also performed. As the study was conducted during an emergency response to the outbreak, and was designed to provide information to orient the public health response, ethical approval was not required. Remedial measures were implemented. Results : A total of 1875 patients reported to the various health facilities of the Vikas Nagar area with complaints of increased frequency of loose watery diarrhea and a few had vomiting episodes during the time period of 1 - 14 July 2012. Four deaths were reported. Three hundred eighteen (318 cases were found in the house-to-house survey of 2765 houses of the area. Twenty-six percent of the cases were in the age group of 1800 MPN/100 mL was reported from 10 water samples. Investigations revealed that the epidemic was waterborne. Leakages in the pipes were found at many places leading to mixing of water with drainage, and water samples collected from the houses of the cases were found to be positive for Vibrio cholerae. Conclusion : Among the identified gaps, delays in the initiation of the investigation of the epidemic and pipe leakages were the most important. In India, waterborne epidemics are usual occurrences during the year

  14. 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.

  15. Cholera outbreak in Senegal in 2005: was climate a factor?

    Directory of Open Access Journals (Sweden)

    Guillaume Constantin de Magny

    Full Text Available Cholera is an acute diarrheal illness caused by Vibrio cholerae and occurs as widespread epidemics in Africa. In 2005, there were 31,719 cholera cases, with 458 deaths in the Republic of Senegal. We retrospectively investigated the climate origin of the devastating floods in mid-August 2005, in the Dakar Region of Senegal and the subsequent outbreak of cholera along with the pattern of cholera outbreaks in three other regions of that country. We compared rainfall patterns between 2002 and 2005 and the relationship between the sea surface temperature (SST gradient in the tropical Atlantic Ocean and precipitation over Senegal for 2005. Results showed a specific pattern of rainfall throughout the Dakar region during August, 2005, and the associated rainfall anomaly coincided with an exacerbation of the cholera epidemic. Comparison of rainfall and epidemiological patterns revealed that the temporal dynamics of precipitation, which was abrupt and heavy, was presumably the determining factor. Analysis of the SST gradient showed that the Atlantic Ocean SST variability in 2005 differed from that of 2002 to 2004, a result of a prominent Atlantic meridional mode. The influence of this intense precipitation on cholera transmission over a densely populated and crowded region was detectable for both Dakar and Thiès, Senegal. Thus, high resolution rainfall forecasts at subseasonal time scales should provide a way forward for an early warning system in Africa for cholera and, thereby, trigger epidemic preparedness. Clearly, attention must be paid to both natural and human induced environmental factors to devise appropriate action to prevent cholera and other waterborne disease epidemics in the region.

  16. Ebola virus outbreak, updates on current therapeutic strategies.

    Science.gov (United States)

    Elshabrawy, Hatem A; Erickson, Timothy B; Prabhakar, Bellur S

    2015-07-01

    Filoviruses are enveloped negative-sense single-stranded RNA viruses, which include Ebola and Marburg viruses, known to cause hemorrhagic fever in humans with a case fatality of up to 90%. There have been several Ebola virus outbreaks since the first outbreak in the Democratic Republic of Congo in 1976 of which, the recent 2013-2015 epidemic in Guinea, Liberia, and Sierra Leone is the largest in recorded history. Within a few months of the start of the outbreak in December 2013, thousands of infected cases were reported with a significant number of deaths. As of March 2015, according to the Centers for Disease Control and Prevention, there have been nearly 25,000 suspected cases, with 15,000 confirmed by laboratory testing, and over 10,000 deaths. The large number of cases and the high mortality rate, combined with the lack of effective Food and Drug Administration-approved treatments, necessitate the development of potent and safe therapeutic measures to combat the current and future outbreaks. Since the beginning of the outbreak, there have been considerable efforts to develop and characterize protective measures including vaccines and antiviral small molecules, and some have proven effective in vitro and in animal models. Most recently, a cocktail of monoclonal antibodies has been shown to be highly effective in protecting non-human primates from Ebola virus infection. In this review, we will discuss what is known about the nature of the virus, phylogenetic classification, genomic organization and replication, disease transmission, and viral entry and highlight the current approaches and efforts, in the development of therapeutics, to control the outbreak. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Legionnaires’ Disease: Clinicoradiological Comparison of Sporadic Versus Outbreak Cases

    Directory of Open Access Journals (Sweden)

    Hafiz Rizwan Talib Hashmi

    2017-06-01

    Full Text Available Background: In 2015, New York City experienced the worst outbreak of Legionnaires’ disease in the history of the city. We compare patients seen during the 2015 outbreak with sporadic cases of Legionella during the past 5 years. Methods: We conducted a retrospective chart review of 90 patients with Legionnaires’ disease, including sporadic cases of Legionella infection admitted from 2010 to 2015 (n = 55 and cases admitted during the 2015 outbreak (n = 35. Results: We saw no significant differences between the 2 groups regarding demographics, smoking habits, alcohol intake, underlying medical disease, or residence type. Univariate and multivariate analyses showed that patients with sporadic case of Legionella had a longer stay in the hospital and intensive care unit as well as an increased stay in mechanical ventilation. Short-term mortality, discharge disposition, and most clinical parameters did not differ significantly between the 2 groups. Conclusions: We found no specific clinicoradiological characteristics that could differentiate sporadic from epidemic cases of Legionella . Early recognition and high suspicion for Legionnaires’ disease are critical to provide appropriate treatment. Cluster of cases should increase suspicion for an outbreak.

  18. 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

  19. Polio infrastructure strengthened disease outbreak preparedness and response in the WHO African Region.

    Science.gov (United States)

    Kouadio, Koffi; Okeibunor, Joseph; Nsubuga, Peter; Mihigo, Richard; Mkanda, Pascal

    2016-10-10

    The continuous deployments of polio resources, infrastructures and systems for responding to other disease outbreaks in many African countries has led to a number of lessons considered as best practice that need to be documented for strengthening preparedness and response activities in future outbreaks. We reviewed and documented the influence of polio best practices in outbreak preparedness and response in Angola, Nigeria and Ethiopia. Data from relevant programmes of the WHO African Region were also analyzed to demonstrate clearly the relative contributions of PEI resources and infrastructure to effective disease outbreak preparedness and response. Polio resources including, human, financial, and logistic, tool and strategies have tremendously contributed to responding to diseases outbreaks across the African region. In Angola, Nigeria and Ethiopia, many disease epidemics including Marburg Hemorrhagic fever, Dengue fever, Ebola Virus Diseases (EVD), Measles, Anthrax and Shigella have been controlled using existing polio Eradication Initiatives resources. Polio staffs are usually deployed in occasions to supports outbreak response activities (coordination, surveillance, contact tracing, case investigation, finance, data management, etc.). Polio logistics such vehicles, laboratories were also used in the response activities to other infectious diseases. Many polio tools including micro planning, dashboard, guidelines, SOPs on preparedness and response have also benefited to other epidemic-prone diseases. The Countries' preparedness and response plan to WPV importation as well as the Polio Emergency Operation Center models were successfully used to develop, strengthen and respond to many other diseases outbreak with the implication of partners and the strong leadership and ownership of governments. This review has important implications for WHO/AFRO initiative to strengthening and improving disease outbreak preparedness and responses in the African Region in respect

  20. Health Services Vulnerability During the Ebola Outbreak: A Qualitative Report

    Directory of Open Access Journals (Sweden)

    Nasir Amanat

    2017-07-01

    Full Text Available Ebola is an infectious disease, which is caused by a virus belonging to the Filoviridae group. The outbreak of the disease in the African countries in 2015 caused massive death and contamination of the healthcare personnel those who were engaged in treating the infected patients and caused irreparable damage to the healthcare system. In this study, the vulnerability of the team of health service providers during the Ebola outbreak in Liberia, Guinea and Sierra Leone is studied. The article also proposes solutions that can be learned as a lesson, help in increasing their resilience in similar biological hazards and planning management strategies for similar events in the future. Long before the outbreak took place, West African countries were already facing acute problems in terms of access to health services and health infrastructure. The most important shortcomings for the same were identified as insufficient number of health personnel and capacity shortage that prevented the people from being ready to deal with such uncalled events viz. accidents and epidemic disease outbreak. The Ebola epidemic exacerbated the persisting problems caused due to a shortage of personnel in these countries and caused the death of a large number of common people as well as healthcare personnel. Generally, the vulnerability of the health team working during the Ebola outbreak could be divided into five general dimensions: 1. Management weakness; 2. Lack of engineering and environmental control; 3. Obstacles in the use of personal protective equipment; 4. Not having enough skills and practice exercises; and 5. Ignoring the social factors and satisfaction of the healthcare personnel. The main theme of the study was failure to understand the risk of personnel in accidents and disasters. Findings revealed building capacity and reducing vulnerability of the healthcare personnel against disasters and epidemics depends upon the perceived risk, which is a decisive factor

  1. Sequential detection of influenza epidemics by the Kolmogorov-Smirnov test

    Directory of Open Access Journals (Sweden)

    Closas Pau

    2012-10-01

    Full Text Available Abstract Background Influenza is a well known and common human respiratory infection, causing significant morbidity and mortality every year. Despite Influenza variability, fast and reliable outbreak detection is required for health resource planning. Clinical health records, as published by the Diagnosticat database in Catalonia, host useful data for probabilistic detection of influenza outbreaks. Methods This paper proposes a statistical method to detect influenza epidemic activity. Non-epidemic incidence rates are modeled against the exponential distribution, and the maximum likelihood estimate for the decaying factor λ is calculated. The sequential detection algorithm updates the parameter as new data becomes available. Binary epidemic detection of weekly incidence rates is assessed by Kolmogorov-Smirnov test on the absolute difference between the empirical and the cumulative density function of the estimated exponential distribution with significance level 0 ≤ α ≤ 1. Results The main advantage with respect to other approaches is the adoption of a statistically meaningful test, which provides an indicator of epidemic activity with an associated probability. The detection algorithm was initiated with parameter λ0 = 3.8617 estimated from the training sequence (corresponding to non-epidemic incidence rates of the 2008-2009 influenza season and sequentially updated. Kolmogorov-Smirnov test detected the following weeks as epidemic for each influenza season: 50−10 (2008-2009 season, 38−50 (2009-2010 season, weeks 50−9 (2010-2011 season and weeks 3 to 12 for the current 2011-2012 season. Conclusions Real medical data was used to assess the validity of the approach, as well as to construct a realistic statistical model of weekly influenza incidence rates in non-epidemic periods. For the tested data, the results confirmed the ability of the algorithm to detect the start and the end of epidemic periods. In general, the proposed test could

  2. Simple decision tools to help optimize the control strategy 2 weeks into a Danish FMD epidemic

    DEFF Research Database (Denmark)

    Willeberg, Preben; Hisham Beshara Halasa, Tariq; Boklund, Anette

    2012-01-01

    The choice of whether or not to apply emergency vaccination is one of the most difficult decisions facing the authorities when foot-and-mouth disease (FMD) breaks out in a free country (Barnett et al. 2002). A simple quantitative tool has been proposed using the first 14-days incidence (FFI...... detected after day 14, the epidemic duration after day 14 and the size of the affected region at the end of the epidemic. Statistically significant positive correlations were found in all regression analyses of the data. There was, however, a high degree of variation (Fig. 1), which is to be expected...... to estimate predictive values by applying selected cut-off- values for both the dependent and the independent variables (Table 1). Emergency vaccination should be considered during an outbreak if the predicted cumulative size, duration or cost of the epidemic appears alarming (EU 2003, Kitching et al. 2005...

  3. Mean field theory of epidemic spreading with effective contacts on networks

    International Nuclear Information System (INIS)

    Wu, Qingchu; Chen, Shufang

    2015-01-01

    We present a general approach to the analysis of the susceptible-infected-susceptible model with effective contacts on networks, where each susceptible node will be infected with a certain probability only for effective contacts. In the network, each node has a given effective contact number. By using the one-vertex heterogenous mean-field (HMF) approximation and the pair HMF approximation, we obtain conditions for epidemic outbreak on degree-uncorrelated networks. Our results suggest that the epidemic threshold is closely related to the effective contact and its distribution. However, when the effective contact is only dependent of node degree, the epidemic threshold can be established by the degree distribution of networks.

  4. 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.

  5. The 2014 Ebola virus outbreak in West Africa highlights no evidence of rapid evolution or adaptation to humans.

    Science.gov (United States)

    Li, Xingguang; Zai, Junjie; Liu, Haizhou; Feng, Yi; Li, Fan; Wei, Jing; Zou, Sen; Yuan, Zhiming; Shao, Yiming

    2016-10-21

    Following its immergence in December 2013, the recent Zaire Ebola virus (EBOV) outbreak in West Africa has spread and persisted for more than two years, making it the largest EBOV epidemic in both scale and geographical region to date. In this study, a total of 726 glycoprotein (GP) gene sequences of the EBOV full-length genome obtained from West Africa from the 2014 outbreak, combined with 30 from earlier outbreaks between 1976 and 2008 were used to investigate the genetic divergence, evolutionary history, population dynamics, and selection pressure of EBOV among distinct epidemic waves. Results from our dataset showed that no non-synonymous substitutions occurred on the GP gene coding sequences of EBOV that were likely to have affected protein structure or function in any way. Furthermore, the significantly different dN/dS ratios observed between the 2014 West African outbreak and earlier outbreaks were more likely due to the confounding presence of segregating polymorphisms. Our results highlight no robust evidence that the 2014 EBOV outbreak is fast-evolving and adapting to humans. Therefore, the unprecedented nature of the 2014 EBOV outbreak might be more likely related to non-virological elements, such as environmental and sociological factors.

  6. First isolation of dengue virus from the 2010 epidemic in Nepal.

    Science.gov (United States)

    Pandey, Basu D; Nabeshima, Takeshi; Pandey, Kishor; Rajendra, Saroj P; Shah, Yogendra; Adhikari, Bal R; Gupta, Govinda; Gautam, Ishan; Tun, Mya M N; Uchida, Reo; Shrestha, Mahendra; Kurane, Ichiro; Morita, Kouichi

    2013-09-01

    Dengue is an emerging disease in Nepal and was first observed as an outbreak in nine lowland districts in 2006. In 2010, however, a large epidemic of dengue occurred with 4,529 suspected and 917 serologically-confirmed cases and five deaths reported in government hospitals in Nepal. The collection of demographic information was performed along with an entomological survey and clinical evaluation of the patients. A total of 280 serum samples were collected from suspected dengue patients. These samples were subjected to routine laboratory investigations and IgM-capture ELISA for dengue serological identification, and 160 acute serum samples were used for virus isolation, RT-PCR, sequencing and phylogenetic analysis. The results showed that affected patients were predominately adults, and that 10% of the cases were classified as dengue haemorrhagic fever/ dengue shock syndrome. The genetic characterization of dengue viruses isolated from patients in four major outbreak areas of Nepal suggests that the DENV-1 strain was responsible for the 2010 epidemic. Entomological studies identified Aedes aegypti in all epidemic areas. All viruses belonged to a monophyletic single clade which is phylogenetically close to Indian viruses. The dengue epidemic started in the lowlands and expanded to the highland areas. To our knowledge, this is the first dengue isolation and genetic characterization reported from Nepal.

  7. Epidemic waves of cholera in the last two decades in Mozambique.

    Science.gov (United States)

    Langa, José Paulo; Sema, Cynthia; De Deus, Nilsa; Colombo, Mauro Maria; Taviani, Elisa

    2015-07-04

    Africa is increasingly affected by cholera. In Mozambique, cholera appeared in the early 1970s when the seventh pandemic entered Africa from the Indian subcontinent. In the following decades, several epidemics were registered in the country, the 1997-1999 epidemic being the most extended. Since then, Mozambique has been considered an endemic area for cholera, characterized by yearly outbreaks occurring with a seasonal pattern. At least three pandemic variants are thought to have originated in the Indian subcontinent and spread worldwide at different times. To understand the epidemiology of cholera in Mozambique, whether the disease re-emerges periodically or is imported by different routes of transmission, we investigated clinical V. cholerae O1 isolated during 1997-1999 and 2012-2014 epidemics. By detecting and characterizing seven genetic elements, the mobilome profile of each isolate was obtained. By comparing it to known seventh pandemic reference strains, it was possible to discern among different V. cholerae O1 variants active in the country. During 1997-1999, epidemic strains showed two different genetic profiles, both related to a pandemic clone that originated from India and was reported in other African countries in the 1990s. Isolates from 2012-2014 outbreaks showed a genetic background related to the pandemic strains currently active as the prevalent causative agent of cholera worldwide. Despite cholera being endemic in Mozambique, the epidemiology of the disease in the past 20 years has been strongly influenced by the cholera seventh pandemic waves that originated in the Indian subcontinent.

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

    Science.gov (United States)

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

    2000-02-01

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

  9. Effects of human dynamics on epidemic spreading in Côte d'Ivoire

    Science.gov (United States)

    Li, Ruiqi; Wang, Wenxu; Di, Zengru

    2017-02-01

    Understanding and predicting outbreaks of contagious diseases are crucial to the development of society and public health, especially for underdeveloped countries. However, challenging problems are encountered because of complex epidemic spreading dynamics influenced by spatial structure and human dynamics (including both human mobility and human interaction intensity). We propose a systematical model to depict nationwide epidemic spreading in Côte d'Ivoire, which integrates multiple factors, such as human mobility, human interaction intensity, and demographic features. We provide insights to aid in modeling and predicting the epidemic spreading process by data-driven simulation and theoretical analysis, which is otherwise beyond the scope of local evaluation and geometrical views. We show that the requirement that the average local basic reproductive number to be greater than unity is not necessary for outbreaks of epidemics. The observed spreading phenomenon can be roughly explained as a heterogeneous diffusion-reaction process by redefining mobility distance according to the human mobility volume between nodes, which is beyond the geometrical viewpoint. However, the heterogeneity of human dynamics still poses challenges to precise prediction.

  10. 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.

  11. 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.

  12. Epidemic of Postsurgical Infections Caused by Mycobacterium massiliense▿

    Science.gov (United States)

    Duarte, Rafael Silva; Lourenço, Maria Cristina Silva; Fonseca, Leila de Souza; Leão, Sylvia Cardoso; Amorim, Efigenia de Lourdes T.; Rocha, Ingrid L. L.; Coelho, Fabrice Santana; Viana-Niero, Cristina; Gomes, Karen Machado; da Silva, Marlei Gomes; de Oliveira Lorena, Nádia Suely; Pitombo, Marcos Bettini; Ferreira, Rosa M. C.; de Oliveira Garcia, Márcio Henrique; de Oliveira, Gisele Pinto; Lupi, Otilia; Vilaça, Bruno Rios; Serradas, Lúcia Rodrigues; Chebabo, Alberto; Marques, Elizabeth Andrade; Teixeira, Lúcia Martins; Dalcolmo, Margareth; Senna, Simone Gonçalves; Sampaio, Jorge Luiz Mello

    2009-01-01

    An epidemic of infections after video-assisted surgery (1,051 possible cases) caused by rapidly growing mycobacteria (RGM) and involving 63 hospitals in the state of Rio de Janeiro, Brazil, occurred between August 2006 and July 2007. One hundred ninety-seven cases were confirmed by positive acid-fast staining and/or culture techniques. Thirty-eight hospitals had cases confirmed by mycobacterial culture, with a total of 148 available isolates recovered from 146 patients. Most (n = 144; 97.2%) isolates presented a PRA-hsp65 restriction pattern suggestive of Mycobacterium bolletii or Mycobacterium massiliense. Seventy-four of these isolates were further identified by hsp65 or rpoB partial sequencing, confirming the species identification as M. massiliense. Epidemic isolates showed susceptibility to amikacin (MIC at which 90% of the tested isolates are inhibited [MIC90], 8 μg/ml) and clarithromycin (MIC90, 0.25 μg/ml) but resistance to ciprofloxacin (MIC90, ≥32 μg/ml), cefoxitin (MIC90, 128 μg/ml), and doxycycline (MIC90, ≥64 μg/ml). Representative epidemic M. massiliense isolates that were randomly selected, including at least one isolate from each hospital where confirmed cases were detected, belonged to a single clone, as indicated by the analysis of pulsed-field gel electrophoresis (PFGE) patterns. They also had the same PFGE pattern as that previously observed in two outbreaks that occurred in other Brazilian cities; we designated this clone BRA100. All five BRA100 M. massiliense isolates tested presented consistent tolerance to 2% glutaraldehyde. This is the largest epidemic of postsurgical infections caused by RGM reported in the literature to date in Brazil. PMID:19403765

  13. Continental synchronicity of human influenza virus epidemics despite climactic variation.

    Science.gov (United States)

    Geoghegan, Jemma L; Saavedra, Aldo F; Duchêne, Sebastián; Sullivan, Sheena; Barr, Ian; Holmes, Edward C

    2018-01-01

    The factors that determine the pattern and rate of spread of influenza virus at a continental-scale are uncertain. Although recent work suggests that influenza epidemics in the United States exhibit a strong geographical correlation, the spatiotemporal dynamics of influenza in Australia, a country and continent of approximately similar size and climate complexity but with a far smaller population, are not known. Using a unique combination of large-scale laboratory-confirmed influenza surveillance comprising >450,000 entries and genomic sequence data we determined the local-level spatial diffusion of this important human pathogen nationwide in Australia. We used laboratory-confirmed influenza data to characterize the spread of influenza virus across Australia during 2007-2016. The onset of established epidemics varied across seasons, with highly synchronized epidemics coinciding with the emergence of antigenically distinct viruses, particularly during the 2009 A/H1N1 pandemic. The onset of epidemics was largely synchronized between the most populous cities, even those separated by distances of >3000 km and those that experience vastly diverse climates. In addition, by analyzing global phylogeographic patterns we show that the synchronized dissemination of influenza across Australian cities involved multiple introductions from the global influenza population, coupled with strong domestic connectivity, rather than through the distinct radial patterns of geographic dispersal that are driven by work-flow transmission as observed in the United States. In addition, by comparing the spatial structure of influenza A and B, we found that these viruses tended to occupy different geographic regions, and peak in different seasons, perhaps indicative of moderate cross-protective immunity or viral interference effects. The highly synchronized outbreaks of influenza virus at a continental-scale revealed here highlight the importance of coordinated public health responses in the

  14. 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.

  15. 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

  16. [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.

  17. [EPIDEMIOLOGIC FEATURES OFNOROVIRUS INFECTION OUTBREAK IN THE REPUBLIC OF NORTH OSSETIA-ALANIA].

    Science.gov (United States)

    Maletskaya, O V; Tibilov, A G; Prislegina, D A; Gazieva, G K; Otaraeva, N I; Volynkina, A S; Saveliev, V N; Lyamkin, G I; Zaitsev, A A; Kulichenko, A N

    2016-01-01

    Analysis of epidemiologic features of a norovirus outbreak in Alagir city of the Republic of North Ossetia-Alania and effectiveness of measures of its liquidation. Data from maps-schemes of water supply system of Alagir city and statistical documentation of Centre of Hygiene and Epidemiology in the Republic of North Ossetia-Alania were used in the study. Indication of norovirus in clinical material and water samples was carried out bypolymerase chain reaction method. Etiological agent of outbreak disease was established--genotype II norovirus. Realization of fecal-oral mechanisms of water transmission pathway of the causative agent of norovirus infection was detected. Conditions facilitating emergence and development of the indicated outbreak were determined--non-satisfactory sanitary-technical condition of water. supply system of the city. The studied water outbreak of norovirus infection was caused by GII.17 genotype virus, that currently gradually displaces GII.IV genotype, and was characterized by an intensive start, involvement of all population age groups into the epidemic process (with primary infection of adults), low family focality, predominance of average severity disease forms in the clinical presentation. The counter-epidemic measures carried out ensured rapid localization and liquidation of the norovirus infection outbreak.

  18. [DETERMINATION OF TYPES OF EPIDEMIC MANIFESTATIONS OF CHOLERA IN REGIONS OF THE CRIMEA FEDERAL DISTRICT (REPUBLIC OF CRIMEA)].

    Science.gov (United States)

    Onischenko, G G; Popova, A Yu; Moskvitina, E A; Penkovskaya, N A; Listopad, S A; Titova, S V; Kruglikov, V D

    2015-01-01

    The aim of the study was determination of the type of epidemic manifestations of cholera in the Republic of Crimea based on evaluation of epidemic manifestations of cholera risk of introduction and spread of the infection. It was concluded, that, based on the cholera outbreaks, that had taken place, contamination of surface water bodies (fresh and sea) and sewage by Vibrio cholerae O1 ctxA+ and Vibrio cholerae O1 ctXA- potential epidemic danger of introduction of the infection by various types of international transport, population migration, the presence of epidemiologic risk in realization of water pathway of transmission of cholera causative agent and several other social conditions, the Republic of Crimea remains in the group of territories of type I by epidemic manifestations of cholera.

  19. 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.

  20. 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

  1. Forecasting rodent outbreaks in Africa

    DEFF Research Database (Denmark)

    Leirs, Herwig; Verhagen, Ron; Verheyen, Walter

    1996-01-01

    1. Rainfall data were collated for years preceding historical outbreaks of Mastomys rats in East Africa in order to test the hypothesis that such outbreaks occur after long dry periods. 2. Rodent outbreaks were generally not preceded by long dry periods. 3. Population dynamics of Mastomys...... natalensis rats in Tanzania are significantly affected by the distribution of rainfall during the rainy season. 4. All previous rodent outbreaks in Tanzania were preceded by abundant rainfall early in the rainy season, i.e, towards the end of the year. 5. A flow chart is constructed to assess the likelihood...

  2. Incentives for reporting disease outbreaks.

    Directory of Open Access Journals (Sweden)

    Ramanan Laxminarayan

    Full Text Available BACKGROUND: Countries face conflicting incentives to report infectious disease outbreaks. Reports of outbreaks can prompt other countries to impose trade and travel restrictions, which has the potential to discourage reporting. However, reports can also bring medical assistance to contain the outbreak, including access to vaccines. METHODS: We compiled data on reports of meningococcal meningitis to the World Health Organization (WHO from 54 African countries between 1966 and 2002, a period is marked by two events: first, a large outbreak reported from many countries in 1987 associated with the Hajj that resulted in more stringent requirements for meningitis vaccination among pilgrims; and second, another large outbreak in Sub-Saharan Africa in 1996 that led to a new international mechanism to supply vaccines to countries reporting a meningitis outbreak. We used fixed-effects regression modeling to statistically estimate the effect of external forcing events on the number of countries reporting cases of meningitis to WHO. FINDINGS: We find that the Hajj vaccination requirements started in 1988 were associated with reduced reporting, especially among countries with relatively fewer cases reported between 1966 and 1979. After the vaccine provision mechanism was in place in 1996, reporting among countries that had previously not reported meningitis outbreaks increased. INTERPRETATION: These results indicate that countries may respond to changing incentives to report outbreaks when they can do so. In the long term, these incentives are likely to be more important than surveillance assistance in prompt reporting of outbreaks.

  3. Estimating the effectiveness of early control measures through school absenteeism surveillance in observed outbreaks at rural schools in Hubei, China.

    Science.gov (United States)

    Fan, Yunzhou; Yang, Mei; Jiang, Hongbo; Wang, Ying; Yang, Wenwen; Zhang, Zhixia; Yan, Weirong; Diwan, Vinod K; Xu, Biao; Dong, Hengjin; Palm, Lars; Liu, Li; Nie, Shaofa

    2014-01-01

    School absenteeism is a common data source in syndromic surveillance, which allows for the detection of outbreaks at an early stage. Previous studies focused on its correlation with other data sources. In this study, we evaluated the effectiveness of control measures based on early warning signals from school absenteeism surveillance in rural Chinese schools. A school absenteeism surveillance system was established in all 17 primary schools in 3 adjacent towns in the Chinese region of Hubei. Three outbreaks (varicella, mumps, and influenza-like illness) were detected and controlled successfully from April 1, 2012, to January 15, 2014. An impulse susceptible-exposed-infectious-recovered model was used to fit the epidemics of these three outbreaks. Moreover, it simulated the potential epidemics under interventions resulting from traditional surveillance signals. The effectiveness of the absenteeism-based control measures was evaluated by comparing the simulated datasets. The school absenteeism system generated 52 signals. Three outbreaks were verified through epidemiological investigation. Compared to traditional surveillance, the school absenteeism system generated simultaneous signals for the varicella outbreak, but 3 days in advance for the mumps outbreak and 2-4 days in advance for the influenza-like illness outbreak. The estimated excess protection rates of control measures based on early signals were 0.0%, 19.0-44.1%, and 29.0-37.0% for the three outbreaks, respectively. Although not all outbreak control measures can benefit from early signals through school absenteeism surveillance, the effectiveness of early signal-based interventions is obvious. School absenteeism surveillance plays an important role in reducing outbreak spread.

  4. Rapid response to Ebola outbreaks in remote areas - Liberia, July-November 2014.

    Science.gov (United States)

    Kateh, Francis; Nagbe, Thomas; Kieta, Abraham; Barskey, Albert; Gasasira, Alex Ntale; Driscoll, Anne; Tucker, Anthony; Christie, Athalia; Karmo, Ben; Scott, Colleen; Bowah, Collin; Barradas, Danielle; Blackley, David; Dweh, Emmanuel; Warren, Felicia; Mahoney, Frank; Kassay, Gabriel; Calvert, Geoffrey M; Castro, Georgina; Logan, Gorbee; Appiah, Grace; Kirking, Hannah; Koon, Hawa; Papowitz, Heather; Walke, Henry; Cole, Isaac B; Montgomery, Joel; Neatherlin, John; Tappero, Jordan W; Hagan, Jose E; Forrester, Joseph; Woodring, Joseph; Mott, Joshua; Attfield, Kathleen; DeCock, Kevin; Lindblade, Kim A; Powell, Krista; Yeoman, Kristin; Adams, Laura; Broyles, Laura N; Slutsker, Laurence; Larway, Lawrence; Belcher, Lisa; Cooper, Lorraine; Santos, Marjorie; Westercamp, Matthew; Weinberg, Meghan Pearce; Massoudi, Mehran; Dea, Monica; Patel, Monita; Hennessey, Morgan; Fomba, Moses; Lubogo, Mutaawe; Maxwell, Nikki; Moonan, Patrick; Arzoaquoi, Sampson; Gee, Samuel; Zayzay, Samuel; Pillai, Satish; Williams, Seymour; Zarecki, Shauna Mettee; Yett, Sheldon; James, Stephen; Grube, Steven; Gupta, Sundeep; Nelson, Thelma; Malibiche, Theophil; Frank, Wilmont; Smith, Wilmot; Nyenswah, Tolbert

    2015-02-27

    West Africa is experiencing its first epidemic of Ebola virus disease (Ebola). As of February 9, Liberia has reported 8,864 Ebola cases, of which 3,147 were laboratory-confirmed. Beginning in August 2014, the Liberia Ministry of Health and Social Welfare (MOHSW), supported by CDC, the World Health Organization (WHO), and others, began systematically investigating and responding to Ebola outbreaks in remote areas. Because many of these areas lacked mobile telephone service, easy road access, and basic infrastructure, flexible and targeted interventions often were required. Development of a national strategy for the Rapid Isolation and Treatment of Ebola (RITE) began in early October. The strategy focuses on enhancing capacity of county health teams (CHT) to investigate outbreaks in remote areas and lead tailored responses through effective and efficient coordination of technical and operational assistance from the MOHSW central level and international partners. To measure improvements in response indicators and outcomes over time, data from investigations of 12 of 15 outbreaks in remote areas with illness onset dates of index cases during July 16-November 20, 2014, were analyzed. The times to initial outbreak alerts and durations of the outbreaks declined over that period while the proportions of patients who were isolated and treated increased. At the same time, the case-fatality rate in each outbreak declined. Implementation of strategies, such as RITE, to rapidly respond to rural outbreaks of Ebola through coordinated and tailored responses can successfully reduce transmission and improve outcomes.

  5. A Waterborne Gastroenteritis Outbreak Caused by Norovirus GII.17 in a Hotel, Hebei, China, December 2014.

    Science.gov (United States)

    Qin, Meng; Dong, Xiao-Gen; Jing, Yan-Yan; Wei, Xiu-Xia; Wang, Zhao-E; Feng, Hui-Ru; Yu, Hong; Li, Jin-Song; Li, Jie

    2016-09-01

    Norovirus (NoV) is responsible for an estimated 90 % of all epidemic nonbacterial outbreaks of gastroenteritis worldwide. Waterborne outbreaks of NoV are commonly reported. A novel GII.17 NoV strain emerged as a major cause of gastroenteritis outbreaks in China during the winter of 2014/2015. During this time, an outbreak of gastroenteritis occurred at a hotel in a ski park in Hebei Province, China. Epidemiological investigations indicated that one water well, which had only recently been in use, was the probable source. GII.17 NoV was detected by real-time reverse-transcription polymerase chain reaction from samples taken from cases, from concentrated water samples from water well, and from the nearby sewage settling tank. Nucleotide sequences of NoV extracted from clinical and water specimens were genetically identical and had 99 % homology with Beijing/CHN/2015. All epidemiological data indicated that GII.17 NoV was responsible for this outbreak. This is the first reported laboratory-confirmed waterborne outbreak caused by GII.17 NoV genotype in China. Strengthening management of well drinking water and systematica monitoring of NoV is essential for preventing future outbreaks.

  6. 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.

  7. 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....

  8. 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.

  9. 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…

  10. 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...

  11. Devising a method towards development of early warning tool for detection of malaria outbreak.

    Science.gov (United States)

    Verma, Preeti; Sarkar, Soma; Singh, Poonam; Dhiman, Ramesh C

    2017-11-01

    Uncertainty often arises in differentiating seasonal variation from outbreaks of malaria. The present study was aimed to generalize the theoretical structure of sine curve for detecting an outbreak so that a tool for early warning of malaria may be developed. A 'case/mean-ratio scale' system was devised for labelling the outbreak in respect of two diverse districts of Assam and Rajasthan. A curve-based method of analysis was developed for determining outbreak and using the properties of sine curve. It could be used as an early warning tool for Plasmodium falciparum malaria outbreaks. In the present method of analysis, the critical C max (peak value of sine curve) value of seasonally adjusted curve for P. falciparum malaria outbreak was 2.3 for Karbi Anglong and 2.2 for Jaisalmer districts. On case/mean-ratio scale, the C max value of malaria curve between C max and 3.5, the outbreak could be labelled as minor while >3.5 may be labelled as major. In epidemic years, with mean of case/mean ratio of ≥1.00 and root mean square (RMS) ≥1.504 of case/mean ratio, outbreaks can be predicted 1-2 months in advance. The present study showed that in P. falciparum cases in Karbi Anglong (Assam) and Jaisalmer (Rajasthan) districts, the rise in C max value of curve was always followed by rise in average/RMS or both and hence could be used as an early warning tool. The present method provides better detection of outbreaks than the conventional method of mean plus two standard deviation (mean+2 SD). The identified tools are simple and may be adopted for preparedness of malaria outbreaks.

  12. Multidrug-Resistant Bacterial Outbreaks in Burn Units: A Synthesis of the Literature According to the ORION Statement.

    Science.gov (United States)

    Girerd-Genessay, Isabelle; Bénet, Thomas; Vanhems, Philippe

    2016-01-01

    The objective of this study is to review the literature on multidrug-resistant bacteria (MDRB) outbreaks in burn units according to the outbreak reports and intervention studies of nosocomial infection statement. A PubMed search engine was enlisted to identify reports, in English and French, on MDRB outbreaks in burn units, with no date restrictions, using the following key words: ("burn" OR "burns" OR "severe burn") AND ("unit" OR "critical care" OR "acute care" OR "intensive care" OR "center" OR "centre" OR "department") AND ("outbreak" OR "epidemic") AND ("resistant" OR "multidrug-resistant" OR "resistance" OR "MDR" OR "MDRO"). Twenty-nine articles on such outbreaks in burn units were analyzed. A wide variety of these outbreaks were studied in terms of the microbial agents involved, length of outbreak, and attack rate (1.9-66.7%). The most frequent bacteria were methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii. Screening of staff revealed carrier rates of 0 to 20% in 16 studies. Environmental samples were taken in 21 studies and were positive in 14 of them. The mortality rate among infected patients varied from 0 to 33%. Implementation of isolation precautions did not always suffice, with unit closure being necessary in five outbreaks. The lack of consensus on how to manage such outbreak was highlighted. MDRB infections or colonizations are responsible for increased morbidity and mortality in vulnerable burn patients. Their management is problematic because of multifactorial transmission and limited therapeutic possibilities.

  13. 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.

  14. Ongoing dengue epidemic - Angola, June 2013.

    Science.gov (United States)

    2013-06-21

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

  15. Brote con síntomas respiratorios en la provincia de Almería por una posible exposición a microalgas tóxicas An epidemic outbreak with respiratory symptoms in the province of Almeria (Spain due to toxic microalgae exposure

    Directory of Open Access Journals (Sweden)

    Pilar Barroso García

    2008-12-01

    Full Text Available Objetivos: Describir un brote con clínica de irritación de las vías respiratorias, notificado en una localidad de la costa almeriense en agosto de 2006, así como la investigación etiológica realizada. Métodos: Estudio descriptivo y de casos y controles. Se dividió la localidad en 3 zonas según su mayor o menor cercanía al mar (de 1 a 3. La sintomatología fue valorada subjetivamente de menor a mayor gravedad (1 a 3. Se estimaron las tasas de ataque (TA. Para relacionar la gravedad de los síntomas por zonas y el tipo de exposición se calcularon las odds ratio (OR y sus intervalos de confianza del 95% (IC95%. También se utilizó la prueba de la χ2 y el test exacto de Fisher. Se realizó una investigación ambiental. Resultados: Se encuestó a 57 casos y 26 controles. Se estimó una TA del 69%. El síntoma más frecuente fue el estornudo (87,7%. Los individuos de la zona 1 presentaron mayor riesgo de padecer sintomatología de más gravedad que los de la zona 3 (OR = 46,7; IC95%: 4,7-2.067,4. Los que indicaron una mayor permanencia fuera de la vivienda tuvieron mayor riesgo de enfermar (OR = 12,2; IC95%: 1,1-615,1. En agua de mar se detectaron 1.200 células/l de dinoflagelados Ostreopsis. Conclusiones: Se trata de un brote con sintomatología respiratoria, con distinto grado de afectación según la cercanía al mar de la vivienda. Según la investigación epidemiológica y ambiental, lo más probable es que se haya debido a la presencia de microalgas tóxicas Ostreopsis.Aim: To describe an outbreak with symptoms of respiratory tract irritation reported in a village located on the Almerian coast in August 2006, as well as the etiological research performed. Methods: We performed a descriptive case-control study. The village was divided into three areas (from 1 to 3 according to the distance from the sea. Symptomatology was subjectively assessed on an ascending severity scale (from 1 to 3. Attack rates (AR were estimated. To correlate

  16. Gastroenteritis outbreaks on cruise ships

    DEFF Research Database (Denmark)

    Mouchtouri, Varvara A; Verykouki, Eleni; Zamfir, Dumitru

    2017-01-01

    When an increased number of acute gastroenteritis (AG) cases is detected among tourists staying at the same accommodation, outbreak management plans must be activated in a timely manner to prevent large outbreaks. Syndromic surveillance data collected between 1 January 2010 and 31 December 2013...

  17. 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

  18. Seroprevalence of human enterovirus 71 and coxsackievirus A16 in Guangdong, China, in pre- and post-2010 HFMD epidemic period.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available BACKGROUND: Human Enterovirus 71 and Coxsackie A16 have caused many outbreaks in the last decade in mainland China, resulting in thousands of fatal cases. Seroepidemiology which provides important information to document population immunity is rare in China. METHODOLOGY/PRINCIPAL FINDINGS: A cross sectional study of Enterovirus 71 (EV71 and Coxsackie A16 (CA16 seroprevalence was carried out in Guangdong, China, pre- and post- the 2010 hand, foot and mouth disease (HFMD epidemic period. The levels of EV71 and CA16 specific antibodies were evaluated by a microneutralization test and the geometric mean titer (GMT was calculated and compared. Our results indicated frequent infection by EV71 and CA16 in Guangdong before the 2010 epidemic. Only EV71 neutralizing antibody but not CA16 seroprevalence was significantly increased after the 2010 HFMD epidemic. Children less than 3 years old especially those aged 2 years showed the lowest positive rates for EV71 and CA16 NA before epidemic and the most significantly increased EV71 seroprevalence after epidemic. CA16 GMT values declined after the 2010 epidemic. CONCLUSIONS: These results indicate EV71 was the major pathogen of HFMD in Guangdong during the 2010 epidemic. The infection occurs largely in children less than 3 years, who should have first priority to receive an EV71 vaccine.

  19. Identifying the pattern of molecular evolution for Zaire ebolavirus in the 2014 outbreak in West Africa.

    Science.gov (United States)

    Liu, Si-Qing; Deng, Cheng-Lin; Yuan, Zhi-Ming; Rayner, Simon; Zhang, Bo

    2015-06-01

    The current Ebola virus disease (EVD) epidemic has killed more than all previous Ebola outbreaks combined and, even as efforts appear to be bringing the outbreak under control, the threat of reemergence remains. The availability of new whole-genome sequences from West Africa in 2014 outbreak, together with those from the earlier outbreaks, provide an opportunity to investigate the genetic characteristics, the epidemiological dynamics and the evolutionary history for Zaire ebolavirus (ZEBOV). To investigate the evolutionary properties of ZEBOV in this outbreak, we examined amino acid mutations, positive selection, and evolutionary rates on the basis of 123 ZEBOV genome sequences. The estimated phylogenetic relationships within ZEBOV revealed that viral sequences from the same period or location formed a distinct cluster. The West Africa viruses probably derived from Middle Africa, consistent with results from previous studies. Analysis of the seven protein regions of ZEBOV revealed evidence of positive selection acting on the GP and L genes. Interestingly, all putatively positive-selected sites identified in the GP are located within the mucin-like domain of the solved structure of the protein, suggesting a possible role in the immune evasion properties of ZEBOV. Compared with earlier outbreaks, the evolutionary rate of GP gene was estimated to significantly accelerate in the 2014 outbreak, suggesting that more ZEBOV variants are generated for human to human transmission during this sweeping epidemic. However, a more balanced sample set and next generation sequencing datasets would help achieve a clearer understanding at the genetic level of how the virus is evolving and adapting to new conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. The macroeconomics of targeting: the case of an enduring epidemic.

    Science.gov (United States)

    Bell, Clive; Gersbach, Hans

    2009-01-01

    What is the right balance among policy interventions in order to ensure economic growth over the long run when an epidemic causes heavy mortality among young adults? We argue that, in general, policies to combat the disease and promote education must be concentrated, in certain ways, at first on some subgroups of society. This concentration involves what we term the macroeconomics of targeting. The central comparison is then between programs under which supported families enjoy the benefits of spending on health and education simultaneously (DT), and those under which the benefits in these two domains are sequenced (ST). When levels of human capital are uniformly low at the outbreak, DT is superior to ST if the mortality rate exceeds some threshold value. Outside aid makes DT more attractive; but DT restricts support to fewer families initially and so increases inequality. A summary account of the empirical evidence is followed by an application of the framework to South Africa.

  1. Oscillations in epidemic models with spread of awareness.

    Science.gov (United States)

    Just, Winfried; Saldaña, Joan; Xin, Ying

    2018-03-01

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

  2. Epidemic spread in coupled populations with seasonally varying migration rates

    Science.gov (United States)

    Muzyczyn, Adam; Shaw, Leah B.

    2009-03-01

    The H5N1 strain of avian influenza has spread worldwide, and this spread may be due to seasonal migration of birds and mixing of birds from different regions in the wintering grounds. We studied a multipatch model for avian influenza with seasonally varying migration rates. The bird population was divided into two spatially distinct patches, or subpopulations. Within each patch, the disease followed the SIR (susceptible-infected-recovered) model for epidemic spread. Migration rates were varied periodically, with a net flux toward the breeding grounds during the spring and towards the wintering grounds during the fall. The case of two symmetric patches reduced to single-patch SIR dynamics. However, asymmetry in the birth and contact rates in the breeding grounds and wintering grounds led to bifurcations to longer period orbits and chaotic dynamics. We studied the bifurcation structure of the model and the phase relationships between outbreaks in the two patches.

  3. The spreading time in SIS epidemics on networks

    Science.gov (United States)

    He, Zhidong; Van Mieghem, Piet

    2018-03-01

    In a Susceptible-Infected-Susceptible (SIS) process, we investigate the spreading time Tm, which is the time when the number of infected nodes in the metastable state is first reached, starting from the outbreak of the epidemics. We observe that the spreading time Tm resembles a lognormal-like distribution, though with different deep tails, both for the Markovian and the non-Markovian infection process, which implies that the spreading time can be very long with a relatively high probability. In addition, we show that a stronger virus, with a higher effective infection rate τ or an earlier timing of the infection attempts, does not always lead to a shorter average spreading time E [Tm ] . We numerically demonstrate that the average spreading time E [Tm ] in the complete graph and the star graph scales logarithmically as a function of the network size N for a fixed fraction of infected nodes in the metastable state.

  4. Assessment of the response to cholera outbreaks in two districts in Ghana.

    Science.gov (United States)

    Ohene, Sally-Ann; Klenyuie, Wisdom; Sarpeh, Mark

    2016-11-02

    Despite recurring outbreaks of cholera in Ghana, very little has been reported on assessments of outbreak response activities undertaken in affected areas. This study assessed the response activities undertaken in two districts, Akatsi District in Volta Region and Komenda-Edina-Eguafo-Abirem (KEEA) Municipal in Central Region during the 2012 cholera epidemic in Ghana. We conducted a retrospective assessment of the events, strengths and weaknesses of the cholera outbreak response activities in the two districts making use of the WHO cholera evaluation tool. Information sources included surveillance and facility records, reports and interviews with relevant health personnel involved in the outbreak response from both district health directorates and health facilities. We collected data on age, sex, area of residence, date of reporting to health facility of cholera cases, district population data and information on the outbreak response activities and performed descriptive analyses of the outbreak data by person, time and place. The cholera outbreak in Akatsi was explosive with a high attack rate (AR) of 374/100,000 and case fatality rate (CFR) of 1.2 % while that in KEEA was on a relatively smaller scale AR of 23/100,000 but with a high case fatality rate of 18.8 %. For both districts, we identified multiple strengths in the response to the outbreak including timely notification of the district health officials which triggered prompt investigation of the suspected outbreak facilitating confirmation of cholera and initiation of public health response activities. Others were coordination of the activities by multi-sectoral committees, instituting water, sanitation and hygiene measures and appropriate case management at health facilities. We also found areas that needed improvement in both districts including incomplete surveillance data, sub-optimal community based surveillance considering the late reporting and the deaths in the community and the inadequate

  5. Ecological consequences of mountain pine beetle outbreaks for wildlife in western North American forests

    Science.gov (United States)

    Saab, Victoria A.; Latif, Quresh S.; Rowland, Mary M.; Johnson, Tracey N.; Chalfoun, Anna D.; Buskirk, Steven W.; Heyward, Joslin E.; Dresser, Matthew A.

    2014-01-01

    Mountain pine beetle (Dendroctonus ponderosae) (MPB) outbreaks are increasingly prevalent in western North America, causing considerable ecological change in pine (Pinus spp.) forests with important implications for wildlife. We reviewed studies examining wildlife responses to MPB outbreaks and postoutbreak salvage logging to inform forest management and guide future research. Our review included 16 studies describing MPB outbreak relationships with 89 bird species and 6 studies describing relationships with 11 mammalian species, but no studies of reptiles or amphibians. We included studies that compared wildlife response metrics temporally (before versus after the outbreak) and spatially (across sites that varied in severity of outbreak) in relation to beetle outbreaks. Outbreaks ranged in size from 20,600 to ≥107 ha and studies occurred 1‐30 years after the peak MPB outbreak, but most studies were conducted over the short-term (i.e., ≤6 years after the peak of MPB-induced tree mortality). Birds were the only taxa studied frequently; however, high variability existed among those studies to allow many inferences, although some patterns were evident. Avian studies concluded that cavity-nesting species responded more favorably to beetle-killed forests than species with open-cup nests, and species nesting in the shrub layer favored outbreak forests compared with ground and open-cup canopy nesters that generally showed mixed relationships. Bark-drilling species as a group clearly demonstrated a positive short-term association with MPB epidemics compared with that of other foraging assemblages. Cavity-nesting birds that do not consume bark beetles (i.e., secondary cavity-nesting species and nonbark-drilling woodpeckers) also exhibited some positive responses to MPB outbreaks, although not as pronounced or consistent as those of bark-drilling woodpeckers. Mammalian responses to MPB outbreaks were mixed. Studies consistently reported negative effects of MPB

  6. Epidemic spreading on dynamical networks with temporary hubs and stable scale-free degree distribution

    International Nuclear Information System (INIS)

    Wu, An-Cai

    2014-01-01

    Recent empirical analyses of some realistic dynamical networks have demonstrated that their degree distributions are stable scale-free (SF), but the instantaneous well-connected hubs at one point of time can quickly become weakly connected. Motivated by these empirical results, we propose a simple toy dynamical agent-to-agent contact network model, in which each agent stays at one node of a static underlay network and the nearest neighbors swap their positions with each other. Although the degree distribution of the dynamical network model at any one time is equal to that in the static underlay network, the numbers and identities of each agent’s contacts will change over time. It is found that the dynamic interaction tends to suppress epidemic spreading in terms of larger epidemic threshold, smaller prevalence (the fraction of infected individuals) and smaller velocity of epidemic outbreak. Furthermore, the dynamic interaction results in the prevalence to undergo a phase transition at a finite threshold of the epidemic spread rate in the thermodynamic limit, which is in contradiction to the absence of an epidemic threshold in static SF networks. Some of these findings obtained from heterogeneous mean-field theory are in good agreement with numerical simulations. (paper)

  7. Impact of human mobility on the emergence of dengue epidemics in Pakistan

    Science.gov (United States)

    Wesolowski, Amy; Qureshi, Taimur; Boni, Maciej F.; Sundsøy, Pål Roe; Johansson, Michael A.; Rasheed, Syed Basit; Engø-Monsen, Kenth; Buckee, Caroline O.

    2015-01-01

    The recent emergence of dengue viruses into new susceptible human populations throughout Asia and the Middle East, driven in part by human travel on both local and global scales, represents a significant global health risk, particularly in areas with changing climatic suitability for the mosquito vector. In Pakistan, dengue has been endemic for decades in the southern port city of Karachi, but large epidemics in the northeast have emerged only since 2011. Pakistan is therefore representative of many countries on the verge of countrywide endemic dengue transmission, where prevention, surveillance, and preparedness are key priorities in previously dengue-free regions. We analyze spatially explicit dengue case data from a large outbreak in Pakistan in 2013 and compare the dynamics of the epidemic to an epidemiological model of dengue virus transmission based on climate and mobility data from ∼40 million mobile phone subscribers. We find that mobile phone-based mobility estimates predict the geographic spread and timing of epidemics in both recently epidemic and emerging locations. We combine transmission suitability maps with estimates of seasonal dengue virus importation to generate fine-scale dynamic risk maps with direct application to dengue containment and epidemic preparedness. PMID:26351662

  8. Epidemic Dissemination of a Carbapenem-Resistant Acinetobacter baumannii Clone Carrying armA Two Years After Its First Isolation in an Italian Hospital.

    Science.gov (United States)

    Milan, Annalisa; Furlanis, Linda; Cian, Franca; Bressan, Raffaela; Luzzati, Roberto; Lagatolla, Cristina; Deiana, Maria Luisa; Knezevich, Anna; Tonin, Enrico; Dolzani, Lucilla

    2016-12-01

    This study describes the dissemination of a carbapenem-resistant Acinetobacter baumannii (CRAB) strain in a university hospital in Northeast Italy. Characterization of the outbreak strain was combined with a retrospective analysis of all CRAB isolates collected in the same hospital during the 5 years preceding the outbreak, with the aim of elucidating the origin of the epidemic spread. The outbreak strain was shown to belong to the International Clone II and carry the bla OXA-23 gene, flanked by two ISAba1 sequences in opposite orientation (Tn2006 arrangement). The epidemic clone harbored also the bla OXA-66 allele of the carbapenemase intrinsic to A. baumannii, the determinant of ArmA 16S rRNA methylase and a class 1 integron, with the aacA4, catB8, and aadA1 cassette array. Genotype analysis, performed by macrorestriction analysis and VRBA, revealed that isolates related to outbreak strain had been sporadically collected from inpatients in the 2 years preceding outbreak start. Carriage of bla OXA-66 , armA, and the integron further supported relatedness of these isolates to the outbreak clone. Outbreak initially involved three medical wards, typically hosting elderly patients with a history of prolonged hospitalization. The study highlights the need to adopt strict infection control measures also when CRAB isolation appears to be a sporadic event.

  9. Rapid simulation of spatial epidemics: a spectral method.

    Science.gov (United States)

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

    2015-04-07

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

  10. Predicting epidemic risk from past temporal contact data.

    Directory of Open Access Journals (Sweden)

    Eugenio Valdano

    2015-03-01

    Full Text Available Understanding how epidemics spread in a system is a crucial step to prevent and control outbreaks, with broad implications on the system's functioning, health, and associated costs. This can be achieved by identifying the elements at higher risk of infection and implementing targeted surveillance and control measures. One important ingredient to consider is the pattern of disease-transmission contacts among the elements, however lack of data or delays in providing updated records may hinder its use, especially for time-varying patterns. Here we explore to what extent it is possible to use past temporal data of a system's pattern of contacts to predict the risk of infection of its elements during an emerging outbreak, in absence of updated data. We focus on two real-world temporal systems; a livestock displacements trade network among animal holdings, and a network of sexual encounters in high-end prostitution. We define the node's loyalty as a local measure of its tendency to maintain contacts with the same elements over time, and uncover important non-trivial correlations with the node's epidemic risk. We show that a risk assessment analysis incorporating this knowledge and based on past structural and temporal pattern properties provides accurate predictions for both systems. Its generalizability is tested by introducing a theoretical model for generating synthetic temporal networks. High accuracy of our predictions is recovered across different settings, while the amount of possible predictions is system-specific. The proposed method can provide crucial information for the setup of targeted intervention strategies.

  11. Impact of porcine epidemic diarrhea on performance of growing pigs.

    Directory of Open Access Journals (Sweden)

    Julio Alvarez

    Full Text Available The impact of porcine epidemic diarrhea virus (PEDv infection on the US pork industry has mainly been attributed to the mortality that it causes in suckling piglets, and, consequently, much effort has been invested in the quantification of its effect in sow farms. However, no information on the performance of surviving pigs that were exposed to the PEDv as piglets is available. Here, a retrospective cohort study to evaluate the impact of porcine epidemic diarrhea virus (PEDv infection on growing pigs' performance, as indicated by mortality, average daily gain (ADG, average daily feed intake (ADFI, and feed conversion ratio (FCR was performed using production records from weaned pigs in nursery and wean-to-finish sites from sow farms that became PEDv-infected between May 2013 and June 2014. Production records from the first batch of growing pigs weaned in infected flows after the PEDv outbreak ("infected batches" were compared with those from pigs weaned within the previous 14 to 120 days ("control batches". Performance records from infected and control batches, paired by flow, were compared using non-parametric paired tests. Mortality, ADG and FCR were significantly different in PEDv-positive (infected compared with PEDv-negative (control batches, with a mean increase of mortality and FCR of 11% and 0.5, respectively, and a decrease of ADG of 0.16 lb/day. Our results demonstrate a poorer performance of growing pigs weaned after a PEDv outbreak compared with those weaned within the previous 14-120 days, suggesting that in addition to the mortality induced by PEDv in suckling pigs, the disease also impairs the performance of surviving pig. These findings help to quantify the impact of PEDv infection in the US and, ultimately, contribute to efforts to quantify the cost-effectiveness of disease prevention and control measures.

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

    Directory of Open Access Journals (Sweden)

    Cécile Viboud

    2016-06-01

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

  13. Outbreak of avian influenza H7N3 on a turkey farm in the Netherlands

    OpenAIRE

    Velkers, F.C.; Bouma, A.; Matthijs, M.G.R.; Koch, G.; Westendorp, S.T.; Stegeman, J.A.

    2006-01-01

    This case report describes the course of an outbreak of avian influenza on a Dutch turkey farm. When clinical signs were observed their cause remained unclear. However, serum samples taken for the monitoring campaign launched during the epidemic of highly pathogenic avian influenza in 2003, showed that all the remaining turkeys were seropositive against an H7 strain of avian influenza virus, and the virus was subsequently isolated from stored carcases. The results of a reverse-transcriptase P...

  14. Cancerous patients and outbreak of Escherichia coli: an important issue in oncology

    OpenAIRE

    Joob, Beuy; Wiwanitkit, Viroj

    2014-01-01

    The widespread of the Escherichia coli outbreak in Europe becomes an important public concern at global level. The infection can be serious and might result in death. The retrospective literature review on this specific topic is performed. In this specific brief article, the author presented and discussed on the problem of Escherichia coli infection in the cancerous patients. This is an actual important issue in medical oncology for the scenario of Escherichia coli epidemic.

  15. Ongoing outbreak of dengue type 1 in the Autonomous Region of Madeira, Portugal: preliminary report.

    Science.gov (United States)

    Sousa, C A; Clairouin, M; Seixas, G; Viveiros, B; Novo, M T; Silva, A C; Escoval, M T; Economopoulou, A

    2012-12-06

    Following the identification of two autochthonous cases of dengue type 1 on 3 October 2012, an outbreak of dengue fever has been reported in Madeira, Portugal. As of 25 November, 1,891 cases have been detected on the island where the vector Aedes aegypti had been established in some areas since 2005. This event represents the first epidemic of dengue fever in Europe since 1928 and concerted control measures have been initiated by local health authorities.

  16. An outbreak of cholera in Medipally village, Andhra Pradesh, India, 2013

    OpenAIRE

    Uthappa, Chengappa K.; Allam, Ramesh R.; Nalini, Chava; Gunti, Deepak; Udaragudi, Prasada R.; Tadi, Geetha P.; Murhekar, Manoj V.

    2015-01-01

    Background Cholera continues to remain endemic in over 50 countries and has caused large epidemics with around 3?5 million cases occurring every year in Asia alone. In India, cholera is endemic in many states. However, etiological information and age-specific incidence related to cholera outbreaks is limited. In November 2013, district authorities reported a cluster of diarrheal disease among residents of Medipally to the state surveillance unit. We investigated this cluster to confirm its et...

  17. Outbreaks source: A new mathematical approach to identify their possible location

    Science.gov (United States)

    Buscema, Massimo; Grossi, Enzo; Breda, Marco; Jefferson, Tom

    2009-11-01

    Classical epidemiology has generally relied on the description and explanation of the occurrence of infectious diseases in relation to time occurrence of events rather than to place of occurrence. In recent times, computer generated dot maps have facilitated the modeling of the spread of infectious epidemic diseases either with classical statistics approaches or with artificial “intelligent systems”. Few attempts, however, have been made so far to identify the origin of the epidemic spread rather than its evolution by mathematical topology methods. We report on the use of a new artificial intelligence method (the H-PST Algorithm) and we compare this new technique with other well known algorithms to identify the source of three examples of infectious disease outbreaks derived from literature. The H-PST algorithm is a new system able to project a distances matrix of points (events) into a bi-dimensional space, with the generation of a new point, named hidden unit. This new hidden unit deforms the original Euclidean space and transforms it into a new space (cognitive space). The cost function of this transformation is the minimization of the differences between the original distance matrix among the assigned points and the distance matrix of the same points projected into the bi-dimensional map (or any different set of constraints). For many reasons we will discuss, the position of the hidden unit shows to target the outbreak source in many epidemics much better than the other classic algorithms specifically targeted for this task. Compared with main algorithms known in the location theory, the hidden unit was within yards of the outbreak source in the first example (the 2007 epidemic of Chikungunya fever in Italy). The hidden unit was located in the river between the two village epicentres of the spread exactly where the index case was living. Equally in the second (the 1967 foot and mouth disease epidemic in England), and the third (1854 London Cholera epidemic

  18. The potential impact of case-area targeted interventions in response to cholera outbreaks: A modeling study.

    Science.gov (United States)

    Finger, Flavio; Bertuzzo, Enrico; Luquero, Francisco J; Naibei, Nathan; Touré, Brahima; Allan, Maya; Porten, Klaudia; Lessler, Justin; Rinaldo, Andrea; Azman, Andrew S

    2018-02-01

    Cholera prevention and control interventions targeted to neighbors of cholera cases (case-area targeted interventions [CATIs]), including improved water, sanitation, and hygiene, oral cholera vaccine (OCV), and prophylactic antibiotics, may be able to efficiently avert cholera cases and deaths while saving scarce resources during epidemics. Efforts to quickly target interventions to neighbors of cases have been made in recent outbreaks, but little empirical evidence related to the effectiveness, efficiency, or ideal design of this approach exists. Here, we aim to provide practical guidance on how CATIs might be used by exploring key determinants of intervention impact, including the mix of interventions, "ring" size, and timing, in simulated cholera epidemics fit to data from an urban cholera epidemic in Africa. We developed a micro-simulation model and calibrated it to both the epidemic curve and the small-scale spatiotemporal clustering pattern of case households from a large 2011 cholera outbreak in N'Djamena, Chad (4,352 reported cases over 232 days), and explored the potential impact of CATIs in simulated epidemics. CATIs were implemented with realistic logistical delays after cases presented for care using different combinations of prophylactic antibiotics, OCV, and/or point-of-use water treatment (POUWT) starting at different points during the epidemics and targeting rings of various radii around incident case households. Our findings suggest that CATIs shorten the duration of epidemics and are more resource-efficient than mass campaigns. OCV was predicted to be the most effective single intervention, followed by POUWT and antibiotics. CATIs with OCV started early in an epidemic focusing on a 100-m radius around case households were estimated to shorten epidemics by 68% (IQR 62% to 72%), with an 81% (IQR 69% to 87%) reduction in cases compared to uncontrolled epidemics. These same targeted interventions with OCV led to a 44-fold (IQR 27 to 78) reduction in

  19. 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...

  20. 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

  1. Recent evolutionary history of human immunodeficiency virus type 1 subtype B: Reconstruction of epidemic onset based on sequence distances to the common ancestor

    NARCIS (Netherlands)

    Lukashov, Vladimir V.; Goudsmit, Jaap

    2002-01-01

    We obtained and studied HIV-1 sequences with a known sampling year from three outbreaks of the HIV-1 epidemic: 141 env V3 (270 nt) sampled between 1984 and 1992 and 117 pol prot/RT (804 nt) sequences sampled between 1986 and 1999 from Dutch homosexual men and injecting drug users (IDUs), as well as

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

    Directory of Open Access Journals (Sweden)

    Hossein Hatami

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Linda Munson

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

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

    Science.gov (United States)

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

    2008-06-25

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

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

    Science.gov (United States)

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

    2008-01-01

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

  6. Clinical aspects of a nationwide epidemic of severe haemolytic uremic syndrome (HUS in children

    Directory of Open Access Journals (Sweden)

    Gudmundsdottir Helga

    2011-07-01

    Full Text Available Abstract Background Report a nationwide epidemic of Shiga toxin-producing E. coli (STEC O103:H25 causing hemolytic uremic syndrome (D+HUS in children. Methods Description of clinical presentation, complications and outcome in a nationwide outbreak. Results Ten children (median age 4.3 years developed HUS during the outbreak. One of these was presumed to be a part of the outbreak without microbiological proof. Eight of the patients were oligoanuric and in need of dialysis. Median need for dialysis was 15 days; one girl did not regain renal function and received a kidney transplant. Four patients had seizures and/or reduced consciousness. Cerebral oedema and herniation caused the death of a 4-year-old boy. Two patients developed necrosis of colon with perforation and one of them developed non-autoimmune diabetes. Conclusion This outbreak of STEC was characterized by a high incidence of HUS among the infected children, and many developed severe renal disease and extrarenal complications. A likely explanation is that the O103:H25 (eae and stx2-positive strain was highly pathogen, and we suggest that this serotype should be looked for in patients with HUS caused by STEC, especially in severe forms or outbreaks.

  7. Healthcare Workers Emotions, Perceived Stressors and Coping Strategies During a MERS-CoV Outbreak.

    Science.gov (United States)

    Khalid, Imran; Khalid, Tabindeh J; Qabajah, Mohammed R; Barnard, Aletta G; Qushmaq, Ismael A

    2016-03-01

    Healthcare workers (HCWs) are at high risk of contracting Middle East respiratory syndrome coronavirus (MERS-CoV) during an epidemic. We explored the emotions, perceived stressors, and coping strategies of healthcare workers who worked during a MERS-CoV outbreak in our hospital. A cross-sectional descriptive survey design. A tertiary care hospital. HCWs (150) who worked in high risk areas during the April-May 2014 MERS-CoV outbreak that occurred in Jeddah, Saudi Arabia. We developed and administered a "MERS-CoV staff questionnaire" to study participants. The questionnaire consisted of 5 sections with 72 questions. The sections evaluated hospital staffs emotions, perceived stressors, factors that reduced their stress, coping strategies, and motivators to work during future outbreaks. Responses were scored on a scale from 0-3. The varying levels of stress or effectiveness of measures were reported as mean and standard deviation, as appropriate. Completed questionnaires were returned by 117 (78%) of the participants. The results had many unique elements. HCWs ethical obligation to their profession pushed them to continue with their jobs. The main sentiments centered upon fear of personal safety and well-being of colleagues and family. Positive attitudes in the workplace, clinical improvement of infected colleagues, and stoppage of disease transmission among HCWs after adopting strict protective measures alleviated their fear and drove them through the epidemic. They appreciated recognition of their efforts by hospital management and expected similar acknowledgment, infection control guidance, and equipment would entice them to work during future epidemics. The MERS-CoV outbreak was a distressing time for our staff. Hospitals can enhance HCWs experiences during any future MERS-CoV outbreak by focusing on the above mentioned aspects. © 2016 Marshfield Clinic.

  8. Optimal allocation of resources for suppressing epidemic spreading on networks

    Science.gov (United States)

    Chen, Hanshuang; Li, Guofeng; Zhang, Haifeng; Hou, Zhonghuai

    2017-07-01

    Efficient allocation of limited medical resources is crucial for controlling epidemic spreading on networks. Based on the susceptible-infected-susceptible model, we solve the optimization problem of how best to allocate the limited resources so as to minimize prevalence, providing that the curing rate of each node is positively correlated to its medical resource. By quenched mean-field theory and heterogeneous mean-field (HMF) theory, we prove that an epidemic outbreak will be suppressed to the greatest extent if the curing rate of each node is directly proportional to its degree, under which the effective infection rate λ has a maximal threshold λcopt=1 / , where is the average degree of the underlying network. For a weak infection region (λ ≳λcopt ), we combine perturbation theory with the Lagrange multiplier method (LMM) to derive the analytical expression of optimal allocation of the curing rates and the corresponding minimized prevalence. For a general infection region (λ >λcopt ), the high-dimensional optimization problem is converted into numerically solving low-dimensional nonlinear equations by the HMF theory and LMM. Counterintuitively, in the strong infection region the low-degree nodes should be allocated more medical resources than the high-degree nodes to minimize prevalence. Finally, we use simulated annealing to validate the theoretical results.

  9. Melamine nephrotoxicity: an emerging epidemic in an era of globalization.

    Science.gov (United States)

    Bhalla, Vivek; Grimm, Paul C; Chertow, Glenn M; Pao, Alan C

    2009-04-01

    Recent outbreaks of nephrolithiasis and acute kidney injury among children in China have been linked to ingestion of milk-based infant formula contaminated with melamine. These cases provide evidence in humans for the nephrotoxicity of melamine, which previously had been described only in animals. The consequences of this outbreak are already severe and will likely continue to worsen. Herein we summarize the global impact of the melamine milk contamination, the reemergence of melamine-tainted animal feed, and potential mechanisms of melamine nephrotoxicity. Large-scale epidemiologic studies are necessary to further characterize this disease and to assess its potential long-term sequelae. This epidemic of environmental kidney disease highlights the morbidity associated with adulterated food products available in today's global marketplace and reminds us of the unique vulnerability of the kidney to environmental insults. Melamine is the latest in a growing list of diverse potentially toxic compounds about which nephrologists and other health-care providers responsible for the diagnosis and management of kidney disease must now be aware.

  10. Suppressing epidemic spreading in multiplex networks with social-support

    Science.gov (United States)

    Chen, Xiaolong; Wang, Ruijie; Tang, Ming; Cai, Shimin; Stanley, H. Eugene; Braunstein, Lidia A.

    2018-01-01

    Although suppressing the spread of a disease is usually achieved by investing in public resources, in the real world only a small percentage of the population have access to government assistance when there is an outbreak, and most must rely on resources from family or friends. We study the dynamics of disease spreading in social-contact multiplex networks when the recovery of infected nodes depends on resources from healthy neighbors in the social layer. We investigate how degree heterogeneity affects the spreading dynamics. Using theoretical analysis and simulations we find that degree heterogeneity promotes disease spreading. The phase transition of the infected density is hybrid and increases smoothly from zero to a finite small value at the first invasion threshold and then suddenly jumps at the second invasion threshold. We also find a hysteresis loop in the transition of the infected density. We further investigate how an overlap in the edges between two layers affects the spreading dynamics. We find that when the amount of overlap is smaller than a critical value the phase transition is hybrid and there is a hysteresis loop, otherwise the phase transition is continuous and the hysteresis loop vanishes. In addition, the edge overlap allows an epidemic outbreak when the transmission rate is below the first invasion threshold, but suppresses any explosive transition when the transmission rate is above the first invasion threshold.

  11. Modelling the propagation of social response during a disease outbreak.

    Science.gov (United States)

    Fast, Shannon M; González, Marta C; Wilson, James M; Markuzon, Natasha

    2015-03-06

    Epidemic trajectories and associated social responses vary widely between populations, with severe reactions sometimes observed. When confronted with fatal or novel pathogens, people exhibit a variety of behaviours from anxiety to hoarding of medical supplies, overwhelming medical infrastructure and rioting. We developed a coupled network approach to understanding and predicting social response. We couple the disease spread and panic spread processes and model them through local interactions between agents. The social contagion process depends on the prevalence of the disease, its perceived risk and a global media signal. We verify the model by analysing the spread of disease and social response during the 2009 H1N1 outbreak in Mexico City and 2003 severe acute respiratory syndrome and 2009 H1N1 outbreaks in Hong Kong, accurately predicting population-level behaviour. This kind of empirically validated model is critical to exploring strategies for public health intervention, increasing our ability to anticipate the response to infectious disease outbreaks. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  12. The biennial cycle of respiratory syncytial virus outbreaks in Croatia

    Directory of Open Access Journals (Sweden)

    Drazenovic Vladimir

    2008-01-01

    Full Text Available Abstract The paper analyses the epidemic pattern of respiratory syncytial virus (RSV outbreaks in children in Croatia. Over a period of 11 consecutive winter seasons (1994–2005 3,435 inpatients from Zagreb County aged from infancy to 10 years who were hospitalised with acute respiratory tract infections were tested for RSV-infection. RSV was identified in nasopharyngeal secretions of patients by virus isolation in cell culture and by detection of viral antigen with monoclonal antibodies. In the Zagreb area, RSV outbreaks were proven to vary in a two-year cycle, which was repeated every 23–25 months. This biennial cycle comprised one larger and one smaller season. Climate factors correlated significantly with the number of RSV cases identified only in the large seasons, which suggests that the biennial cycle is likely to continue regardless of meteorological conditions. Knowledge of this biennial pattern should be useful in predicting the onset of RSV outbreaks in Croatia, and would facilitate planning for the prevention and control of RSV infections in the region.

  13. Mycobacterium massiliense outbreak after intramuscular injection, South Korea.

    Science.gov (United States)

    Kim, H J; Cho, Y; Lee, S; Kook, Y; Lee, D; Lee, J; Park, B J

    2012-10-01

    SUMMARY We conducted an epidemic investigation to discover the route of transmission and the host factors of an outbreak of post-injection abscesses. Of the 2984 patients who visited a single clinic, 77 cases were identified and 208 age- and sex-matched controls were selected for analysis. Injected medications per se were not found to be responsible, and a deviation from safe injection practice suggested the likelihood of diluent contamination. Therefore the injected medications were classified according to whether there was a need for a diluent, and two medications showed a statistically significant association, i.e. injection with pheniramine [adjusted odds ratios (aOR) 5·93, 95% confidence interval (CI) 2·97-11·87] and ribostamycin (aOR 47·95, 95% CI 11·08-207·53). However, when considered concurrently, pheniramine lost statistical significance (aOR 8·71, 95% CI 0·44-171·61) suggesting that normal saline was the causative agent of this outbreak. Epidemiological evidence strongly suggested that this post-injection outbreak was caused by saline contaminated with Mycobacterium massiliense without direct microbiological evidence.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

    Viboud, Cécile; Simonsen, Lone; Moghadas, Seyed M.

    2016-01-01

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

  16. A comprehensive database of the geographic spread of past human Ebola outbreaks

    Science.gov (United States)

    Mylne, Adrian; Brady, Oliver J.; Huang, Zhi; Pigott, David M.; Golding, Nick; Kraemer, Moritz U.G.; Hay, Simon I.

    2014-01-01

    Ebola is a zoonotic filovirus that has the potential to cause outbreaks of variable magnitude in human populations. This database collates our existing knowledge of all known human outbreaks of Ebola for the first time by extracting details of their suspected zoonotic origin and subsequent human-to-human spread from a range of published and non-published sources. In total, 22 unique Ebola outbreaks were identified, composed of 117 unique geographic transmission clusters. Details of the index case and geographic spread of secondary and imported cases were recorded as well as summaries of patient numbers and case fatality rates. A brief text summary describing suspected routes and means of spread for each outbreak was also included. While we cannot yet include the ongoing Guinea and DRC outbreaks until they are over, these data and compiled maps can be used to gain an improved understanding of the initial spread of past Ebola outbreaks and help evaluate surveillance and control guidelines for limiting the spread of future epidemics. PMID:25984346

  17. A comprehensive database of the geographic spread of past human Ebola outbreaks.

    Science.gov (United States)

    Mylne, Adrian; Brady, Oliver J; Huang, Zhi; Pigott, David M; Golding, Nick; Kraemer, Moritz U G; Hay, Simon I

    2014-01-01

    Ebola is a zoonotic filovirus that has the potential to cause outbreaks of variable magnitude in human populations. This database collates our existing knowledge of all known human outbreaks of Ebola for the first time by extracting details of their suspected zoonotic origin and subsequent human-to-human spread from a range of published and non-published sources. In total, 22 unique Ebola outbreaks were identified, composed of 117 unique geographic transmission clusters. Details of the index case and geographic spread of secondary and imported cases were recorded as well as summaries of patient numbers and case fatality rates. A brief text summary describing suspected routes and means of spread for each outbreak was also included. While we cannot yet include the ongoing Guinea and DRC outbreaks until they are over, these data and compiled maps can be used to gain an improved understanding of the initial spread of past Ebola outbreaks and help evaluate surveillance and control guidelines for limiting the spread of future epidemics.

  18. Risk and Outbreak Communication: Lessons from Taiwan's Experiences in the Post-SARS Era.

    Science.gov (United States)

    Hsu, Yu-Chen; Chen, Yu-Ling; Wei, Han-Ning; Yang, Yu-Wen; Chen, Ying-Hwei

    In addition to the impact of a disease itself, public reaction could be considered another outbreak to be controlled during an epidemic. Taiwan's experience with SARS in 2003 highlighted the critical role played by the media during crisis communication. After the SARS outbreak, Taiwan's Centers for Disease Control (Taiwan CDC) followed the WHO outbreak communication guidelines on trust, early announcements, transparency, informing the public, and planning, in order to reform its risk communication systems. This article describes the risk communication framework in Taiwan, which has been used to respond to the 2009-2016 influenza epidemics, Ebola in West Africa (2014-16), and MERS-CoV in South Korea (2015) during the post-SARS era. Many communication strategies, ranging from traditional media to social and new media, have been implemented to improve transparency in public communication and promote civic engagement. Taiwan CDC will continue to maintain the strengths of its risk communication systems and resolve challenges as they emerge through active evaluation and monitoring of public opinion to advance Taiwan's capacity in outbreak communication and control. Moreover, Taiwan CDC will continue to implement the IHR (2005) and to promote a global community working together to fight shared risks and to reach the goal of "One World, One Health."

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

    Science.gov (United States)

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

    2016-03-01

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

  20. Ecologic Features of Plague Outbreak Areas, Democratic Republic of the Congo, 2004–2014

    Science.gov (United States)

    Shako, Jean-Christophe; Gaudart, Jean; Sudre, Bertrand; Ilunga, Benoit Kebela; Shamamba, Stomy Karhemere Bi; Diatta, Georges; Davoust, Bernard; Tamfum, Jean-Jacques Muyembe; Piarroux, Renaud; Piarroux, Martine

    2018-01-01

    During 2004–2014, the Democratic Republic of the Congo (DRC) declared 54% of plague cases worldwide. Using national data, we characterized the epidemiology of human plague in DRC for this period. All 4,630 suspected human plague cases and 349 deaths recorded in DRC came from Orientale Province. Pneumonic plague cases (8.8% of total) occurred during 2 major outbreaks in mining camps in the equatorial forest, and some limited outbreaks occurred in the Ituri highlands. Epidemics originated in 5 health zones clustered in Ituri, where sporadic bubonic cases were recorded throughout every year. Classification and regression tree characterized this cluster by the dominance of ecosystem 40 (mountain tropical climate). In conclusion, a small, stable, endemic focus of plague in the highlands of the Ituri tropical region persisted, acting as a source of outbreaks in DRC. PMID:29350136

  1. Evaluation of Strategies to Control a Potential Outbreak of Foot-and-Mouth Disease in Sweden

    DEFF Research Database (Denmark)

    Dórea, Fernanda C.; Nöremark, Maria; Widgren, Stefan

    2017-01-01

    of enforcement of interventions, was assessed. With the estimated currently available resources, an FMD outbreak in Sweden is expected to be controlled (i.e., last infected herd detected) within 3 weeks of detection in any evaluated scenario. The density of farms in the area where the epidemic started would have...... little impact on the time to control the outbreak, but spread in high density areas would require more surveillance resources, compared to areas of lower farm density. The use of vaccination did not result in a reduction in the expected number of infected herds. Preemptive depopulation was able to reduce...... the number of infected herds in extreme scenarios designed to test a combination of worst-case conditions of virus introduction and spread, but at the cost of doubling the number of herds culled. This likely resulted from a combination of the small outbreaks predicted by the spread model, and the high...

  2. A ‘post-honeymoon’ measles epidemic in Burundi: mathematical model-based analysis and implications for vaccination timing

    Directory of Open Access Journals (Sweden)

    Katelyn C. Corey

    2016-09-01

    Full Text Available Using a mathematical model with realistic demography, we analyze a large outbreak of measles in Muyinga sector in rural Burundi in 1988–1989. We generate simulated epidemic curves and age × time epidemic surfaces, which we qualitatively and quantitatively compare with the data. Our findings suggest that supplementary immunization activities (SIAs should be used in places where routine vaccination cannot keep up with the increasing numbers of susceptible individuals resulting from population growth or from logistical problems such as cold chain maintenance. We use the model to characterize the relationship between SIA frequency and SIA age range necessary to suppress measles outbreaks. If SIAs are less frequent, they must expand their target age range.

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

    Science.gov (United States)

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

    2013-11-01

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

  4. Learning from history, predicting the future: the UK Dutch elm disease outbreak in relation to contemporary tree disease threats

    Science.gov (United States)

    Potter, Clive; Harwood, Tom; Knight, Jon; Tomlinson, Isobel

    2011-01-01

    Expanding international trade and increased transportation are heavily implicated in the growing threat posed by invasive pathogens to biodiversity and landscapes. With trees and woodland in the UK now facing threats from a number of disease systems, this paper looks to historical experience with the Dutch elm disease (DED) epidemic of the 1970s to see what can be learned about an outbreak and attempts to prevent, manage and control it. The paper draws on an interdisciplinary investigation into the history, biology and policy of the epidemic. It presents a reconstruction based on a spatial modelling exercise underpinned by archival research and interviews with individuals involved in the attempted management of the epidemic at the time. The paper explores what, if anything, might have been done to contain the outbreak and discusses the wider lessons for plant protection. Reading across to present-day biosecurity concerns, the paper looks at the current outbreak of ramorum blight in the UK and presents an analysis of the unfolding epidemiology and policy of this more recent, and potentially very serious, disease outbreak. The paper concludes by reflecting on the continuing contemporary relevance of the DED experience at an important juncture in the evolution of plant protection policy. PMID:21624917

  5. Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania

    OpenAIRE

    Mweya, Clement N.; Kimera, Sharadhuli I.; Mellau, Lesakit S. B.; Mboera, Leonard E. G.

    2015-01-01

    Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans. Objective: To determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania. Methods: A cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mos...

  6. 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....

  7. 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.

  8. 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.

  9. Training mid-career internists to perform high-quality colonoscopy: a pilot training programme to meet increasing demands for colonoscopy.

    Science.gov (United States)

    Shah-Ghassemzadeh, Nicole K; Jackson, Christian S; Juma, David; Strong, Richard M

    2017-08-01

    Colorectal cancer (CRC) is the second leading cause of cancer deaths in the USA. Despite a recent rise in CRC screening there remains an increasing demand for colonoscopy, yet a limited supply of gastroenterologists who can meet this need. To determine if a mid-career general internist (GIN) could be trained to perform high-quality colonoscopes via an intensive training programme. A GIN trained 2-3 days/week, 4-5 hours/day, for 7 months with an experienced gastroenterologist. Their independent performance was then compared with that of a gastroenterology attending (GA), with and without a gastroenterology fellow (GF). The primary outcome was to compare caecal intubation rates, adenoma detection rates (ADRs), interval CRC rates and complications between the three groups. 989 patients were initially included in the study, and 818 were included in the final analysis. Caecal intubation rates were 95%, 94% and 93% for the GIN, GA+GF and GA, respectively (p=0.31). The overall polyp detection rates were 68%, 39% and 44% among the GIN, GA+GF and GA, respectively (pdemand for colonoscopists. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  10. Deriving a model for influenza epidemics from historical data.

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Jaideep; Lefantzi, Sophia

    2011-09-01

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

  11. Deciphering the Origin of the 2012 Cholera Epidemic in Guinea by Integrating Epidemiological and Molecular Analyses

    Science.gov (United States)

    Rebaudet, Stanislas; Mengel, Martin A.; Koivogui, Lamine; Moore, Sandra; Mutreja, Ankur; Kande, Yacouba; Yattara, Ousmane; Sarr Keita, Véronique; Njanpop-Lafourcade, Berthe-Marie; Fournier, Pierre-Edouard; Garnotel, Eric; Keita, Sakoba; Piarroux, Renaud

    2014-01-01

    Cholera is typically considered endemic in West Africa, especially in the Republic of Guinea. However, a three-year lull period was observed from 2009 to 2011, before a new epidemic struck the country in 2012, which was officially responsible for 7,350 suspected cases and 133 deaths. To determine whether cholera re-emerged from the aquatic environment or was rather imported due to human migration, a comprehensive epidemiological and molecular survey was conducted. A spatiotemporal analysis of the national case databases established Kaback Island, located off the southern coast of Guinea, as the initial focus of the epidemic in early February. According to the field investigations, the index case was found to be a fisherman who had recently arrived from a coastal district of neighboring Sierra Leone, where a cholera outbreak had recently occurred. MLVA-based genotype mapping of 38 clinical Vibrio cholerae O1 El Tor isolates sampled throughout the epidemic demonstrated a progressive genetic diversification of the strains from a single genotype isolated on Kaback Island in February, which correlated with spatial epidemic spread. Whole-genome sequencing characterized this strain as an “atypical” El Tor variant. Furthermore, genome-wide SNP-based phylogeny analysis grouped the Guinean strain into a new clade of the third wave of the seventh pandemic, distinct from previously analyzed African strains and directly related to a Bangladeshi isolate. Overall, these results highly suggest that the Guinean 2012 epidemic was caused by a V. cholerae clone that was likely imported from Sierra Leone by an infected individual. These results indicate the importance of promoting the cross-border identification and surveillance of mobile and vulnerable populations, including fishermen, to prevent, detect and control future epidemics in the region. Comprehensive epidemiological investigations should be expanded to better understand cholera dynamics and improve disease control

  12. Self-mating in the definitive host potentiates clonal outbreaks of the apicomplexan parasites Sarcocystis neurona and Toxoplasma gondii.

    Directory of Open Access Journals (Sweden)

    Jered M Wendte

    2010-12-01

    Full Text Available Tissue-encysting coccidia, including Toxoplasma gondii and Sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. During its sexual life stage, T. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. Out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. In contrast, selfing and other life history traits, such as asexual expansion of tissue-cysts by oral transmission among intermediate hosts, have been proposed to explain the genetic basis for the clonal population structure of T. gondii. In this study, we investigated the contributing roles self-mating and sexual recombination play in nature to maintain clonal population structures and produce or expand parasite clones capable of causing disease epidemics for two tissue encysting parasites. We applied high-resolution genotyping against strains isolated from a T. gondii waterborne outbreak that caused symptomatic disease in 155 immune-competent people in Brazil and a S. neurona outbreak that resulted in a mass mortality event in Southern sea otters. In both cases, a single, genetically distinct clone was found infecting outbreak-exposed individuals. Furthermore, the T. gondii outbreak clone was one of several apparently recombinant progeny recovered from the local environment. Since oocysts or sporocysts were the infectious form implicated in each outbreak, the expansion of the epidemic clone can be explained by self-mating. The results also show that out-crossing preceded selfing to produce the virulent T. gondii clone. For the tissue encysting coccidia, self-mating exists as a key adaptation potentiating the epidemic expansion and transmission of newly emerged parasite clones that can profoundly shape parasite population genetic structures or cause

  13. Self-mating in the definitive host potentiates clonal outbreaks of the apicomplexan parasites Sarcocystis neurona and Toxoplasma gondii.

    Science.gov (United States)

    Wendte, Jered M; Miller, Melissa A; Lambourn, Dyanna M; Magargal, Spencer L; Jessup, David A; Grigg, Michael E

    2010-12-23

    Tissue-encysting coccidia, including Toxoplasma gondii and Sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. During its sexual life stage, T. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. Out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. In contrast, selfing and other life history traits, such as asexual expansion of tissue-cysts by oral transmission among intermediate hosts, have been proposed to explain the genetic basis for the clonal population structure of T. gondii. In this study, we investigated the contributing roles self-mating and sexual recombination play in nature to maintain clonal population structures and produce or expand parasite clones capable of causing disease epidemics for two tissue encysting parasites. We applied high-resolution genotyping against strains isolated from a T. gondii waterborne outbreak that caused symptomatic disease in 155 immune-competent people in Brazil and a S. neurona outbreak that resulted in a mass mortality event in Southern sea otters. In both cases, a single, genetically distinct clone was found infecting outbreak-exposed individuals. Furthermore, the T. gondii outbreak clone was one of several apparently recombinant progeny recovered from the local environment. Since oocysts or sporocysts were the infectious form implicated in each outbreak, the expansion of the epidemic clone can be explained by self-mating. The results also show that out-crossing preceded selfing to produce the virulent T. gondii clone. For the tissue encysting coccidia, self-mating exists as a key adaptation potentiating the epidemic expansion and transmission of newly emerged parasite clones that can profoundly shape parasite population genetic structures or cause devastating disease

  14. Whole-Genome Characterization of Epidemic Neisseria meningitidis Serogroup C and Resurgence of Serogroup W, Niger, 2015

    Science.gov (United States)

    Kretz, Cecilia B.; Retchless, Adam C.; Sidikou, Fati; Issaka, Bassira; Ousmane, Sani; Schwartz, Stephanie; Tate, Ashley H.; Pana, Assimawè; Njanpop-Lafourcade, Berthe-Marie; Nzeyimana, Innocent; Nse, Ricardo Obama; Deghmane, Ala-Eddine; Hong, Eva; Brynildsrud, Ola Brønstad; Novak, Ryan T.; Meyer, Sarah A.; Oukem-Boyer, Odile Ouwe Missi; Ronveaux, Olivier; Caugant, Dominique A.; Taha, Muhamed-Kheir

    2016-01-01

    In 2015, Niger reported the largest epidemic of Neisseria meningitidis serogroup C (NmC) meningitis in sub-Saharan Africa. The NmC epidemic coincided with serogroup W (NmW) cases during the epidemic season, resulting in a total of 9,367 meningococcal cases through June 2015. To clarify the phylogenetic association, genetic evolution, and antibiotic determinants of the meningococcal strains in Niger, we sequenced the genomes of 102 isolates from this epidemic, comprising 81 NmC and 21 NmW isolates. The genomes of 82 isolates were completed, and all 102 were included in the analysis. All NmC isolates had sequence type 10217, which caused the outbreaks in Nigeria during 2013–2014 and for which a clonal complex has not yet been defined. The NmC isolates from Niger were substantially different from other NmC isolates collected globally. All NmW isolates belonged to clonal complex 11 and were closely related to the isolates causing recent outbreaks in Africa. PMID:27649262

  15. 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.

  16. Zika virus infection in Vietnam: current epidemic, strain origin, spreading risk, and perspective.

    Science.gov (United States)

    Chu, Dinh-Toi; Ngoc, Vo Truong Nhu; Tao, Yang

    2017-11-01

    Zika virus infection and its associated microcephaly have being receiving global concern. This infection has spread widely since the first outbreak was recorded in Africa in 1952. Now, it has been reported in over 70 countries on five continents including Africa, North and South America, Asia, and Europe. Vietnam is one of the most recent countries which had cases of Zika virus infection at the end of 2016. This country has also reported the first case of a microcephaly-born baby which was probably linked to Zika virus infection. However, information on the Zika virus epidemic in Vietnam is still limited. This brief report intends to update the current Zika virus epidemic, and to discuss challenges and perspectives in controlling this infection in Vietnam.

  17. 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

  18. Retrospective Analysis of the 2014–2015 Ebola Epidemic in Liberia

    Science.gov (United States)

    Atkins, Katherine E.; Pandey, Abhishek; Wenzel, Natasha S.; Skrip, Laura; Yamin, Dan; Nyenswah, Tolbert G.; Fallah, Mosoka; Bawo, Luke; Medlock, Jan; Altice, Frederick L.; Townsend, Jeffrey; Ndeffo-Mbah, Martial L.; Galvani, Alison P.

    2016-01-01

    The 2014–2015 Ebola epidemic has been the most protracted and devastating in the history of the disease. To prevent future outbreaks on this scale, it is imperative to understand the reasons that led to eventual disease control. Here, we evaluated the shifts of Ebola dynamics at national and local scales during the epidemic in Liberia. We used a transmission model calibrated to epidemiological data between June 9 and December 31, 2014, to estimate the extent of community and hospital transmission. We found that despite varied local epidemic patterns, community transmission was reduced by 40–80% in all the counties analyzed. Our model suggests that the tapering of the epidemic was achieved through reductions in community transmission, rather than accumulation of immune individuals through asymptomatic infection and unreported cases. Although the times at which this transmission reduction occurred in the majority of the Liberian counties started before any large expansion in hospital capacity and the distribution of home protection kits, it remains difficult to associate the presence of interventions with reductions in Ebola incidence. PMID:26928839

  19. Retrospective Analysis of the 2014-2015 Ebola Epidemic in Liberia.

    Science.gov (United States)

    Atkins, Katherine E; Pandey, Abhishek; Wenzel, Natasha S; Skrip, Laura; Yamin, Dan; Nyenswah, Tolbert G; Fallah, Mosoka; Bawo, Luke; Medlock, Jan; Altice, Frederick L; Townsend, Jeffrey; Ndeffo-Mbah, Martial L; Galvani, Alison P

    2016-04-01

    The 2014-2015 Ebola epidemic has been the most protracted and devastating in the history of the disease. To prevent future outbreaks on this scale, it is imperative to understand the reasons that led to eventual disease control. Here, we evaluated the shifts of Ebola dynamics at national and local scales during the epidemic in Liberia. We used a transmission model calibrated to epidemiological data between June 9 and December 31, 2014, to estimate the extent of community and hospital transmission. We found that despite varied local epidemic patterns, community transmission was reduced by 40-80% in all the counties analyzed. Our model suggests that the tapering of the epidemic was achieved through reductions in community transmission, rather than accumulation of immune individuals through asymptomatic infection and unreported cases. Although the times at which this transmission reduction occurred in the majority of the Liberian counties started before any large expansion in hospital capacity and the distribution of home protection kits, it remains difficult to associate the presence of interventions with reductions in Ebola incidence. © The American Society of Tropical Medicine and Hygiene.

  20. First dengue haemorrhagic fever epidemic in the Americas, 1981: insights into the causative agent.

    Science.gov (United States)

    Rodriguez-Roche, Rosmari; Hinojosa, Yoandri; Guzman, Maria G

    2014-12-01

    Historical records describe a disease in North America that clinically resembled dengue haemorrhagic fever during the latter part of the slave-trading period. However, the dengue epidemic that occurred in Cuba in 1981 was the first laboratory-confirmed and clinically diagnosed outbreak of dengue haemorrhagic fever in the Americas. At that time, the presumed source of the dengue type 2 strain isolated during this epidemic was considered controversial, partly because of the limited sequence data and partly because the origin of the virus appeared to be southern Asia. Here, we present a molecular characterisation at the whole-genome level of the original strains isolated at different time points during the epidemic. Phylogenetic trees constructed using Bayesian methods indicated that 1981 Cuban strains group within the Asian 2 genotype. In addition, the study revealed that viral evolution occurred during the epidemic - a fact that could be related to the increasing severity from month to month. Moreover, the Cuban strains exhibited particular amino acid substitutions that differentiate them from the New Guinea C prototype strain as well as from dengue type 2 strains isolated globally.

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

    Directory of Open Access Journals (Sweden)

    Ernest Tambo

    2016-05-01

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

  2. Recurrent dynamics in an epidemic model due to stimulated bifurcation crossovers

    International Nuclear Information System (INIS)

    Juanico, Drandreb Earl

    2015-01-01

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

  3. Social and economic influences on human behavioural response in an emerging epidemic

    Science.gov (United States)

    Phang, P.; Wiwatanapataphee, B.; Wu, Y. H.

    2017-10-01

    The human behavioural changes have been recognized as an important key in shaping the disease spreading and determining the success of control measures in the course of epidemic outbreaks. However, apart from cost-benefit considerations, in reality, people are heterogeneous in their preferences towards adopting certain protective actions to reduce their risk of infection, and social norms have a function in individuals’ decision making. Here, we studied the interplay between the epidemic dynamics, imitation dynamics and the heterogeneity of individual protective behavioural response under the considerations of both economic and social factors, with a simple mathematical compartmental model and multi-population game dynamical replicator equations. We assume that susceptibles in different subpopulations have different preferences in adopting either normal or altered behaviour. By incorporating both intra- and inter-group social pressure, the outcome of the strategy distribution depends on the initial proportion of susceptible with normal and altered strategies in both subpopulations. The increase of additional cost to susceptible with altered behaviour will discourage people to take up protective actions and hence results in higher epidemic final size. For a specific cost of altered behaviour, the social group pressure could be a “double edge sword”, though. We conclude that the interplays between individual protective behaviour adoption, imitation and epidemic dynamics are necessarily complex if both economic and social factors act on populations with existing preferences.

  4. Mycobacterium tuberculosis strains potentially involved in the TB epidemic in Sweden a century ago.

    Directory of Open Access Journals (Sweden)

    Ramona Groenheit

    Full Text Available UNLABELLED: A hundred years ago the prevalence of tuberculosis (TB in Sweden was one of the highest in the world. In this study we conducted a population-based search for distinct strains of Mycobacterium tuberculosis complex isolated from patients born in Sweden before 1945. Many of these isolates represent the M. tuberculosis complex population that fueled the TB epidemic in Sweden during the first half of the 20(th century. METHODS: Genetic relationships between strains that caused the epidemic and present day strains were studied by spoligotyping and restriction fragment length polymorphism. RESULTS: The majority of the isolates from the elderly population were evolutionary recent Principal Genetic Group (PGG2/3 strains (363/409 or 88.8%, and only a low proportion were ancient PGG1 strains (24/409 or 5.9%. Twenty-two were undefined. The isolates demonstrated a population where the Euro-American superlineage dominated; in particular with Haarlem (41.1% and T (37.7% spoligotypes and only 21.2% belonged to other spoligotype families. Isolates from the elderly population clustered much less frequently than did isolates from a young control group population. CONCLUSIONS: A closely knit pool of PGG2/3 strains restricted to Sweden and its immediate neighbours appears to have played a role in the epidemic, while PGG1 strains are usually linked to migrants in todaýs Sweden. Further studies of these outbreak strains may give indications of why the epidemic waned.

  5. Recurrent dynamics in an epidemic model due to stimulated bifurcation crossovers

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-15

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

  6. Outbreak Column 16: Cognitive errors in outbreak decision making.

    Science.gov (United States)

    Curran, Evonne T

    2015-01-01

    During outbreaks, decisions must be made without all the required information. People, including infection prevention and control teams (IPCTs), who have to make decisions during uncertainty use heuristics to fill the missing data gaps. Heuristics are mental model short cuts that by-and-large enable us to make good decisions quickly. However, these heuristics contain biases and effects that at times lead to cognitive (thinking) errors. These cognitive errors are not made to deliberately misrepresent any given situation; we are subject to heuristic biases when we are trying to perform optimally. The science of decision making is large; there are over 100 different biases recognised and described. Outbreak Column 16 discusses and relates these heuristics and biases to decision making during outbreak prevention, preparedness and management. Insights as to how we might recognise and avoid them are offered.

  7. Genetic characterization of an epidemic of Plasmodium falciparum malaria among Yanomami Amerindians.

    Science.gov (United States)

    Laserson, K F; Petralanda, I; Almera, R; Barker, R H; Spielman, A; Maguire, J H; Wirth, D F

    1999-12-01

    Malaria parasites are genetically diverse at all levels of endemicity. In contrast, the merozoite surface protein (MSP) alleles in samples from 2 isolated populations of Yanomami Amerindians during an epidemic of Plasmodium falciparum were identical. The nonvariable restriction fragment length polymorphism patterns further suggested that the sequential outbreak comprised only a single P. falciparum genotype. By examination of serial samples from single human infections, the MSP characteristics were found to remain constant throughout the course of infection. An apparent clonal population structure of parasites seemed to cause outbreaks in small isolated villages. The use of standard molecular epidemiologic methods to measure genetic diversity in malaria revealed the occurrence of a genetically monomorphic population of P. falciparum within a human community.

  8. 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.

  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. 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.

  11. 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.

  12. 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

  13. 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

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

    OpenAIRE

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

    2016-01-01

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

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

    DEFF Research Database (Denmark)

    Chowell, Gerardo; Viboud, Cécile; Simonsen, Lone

    2016-01-01

    in the first few disease generations, before susceptible depletion sets in. In reality, outbreaks can display subexponential (i.e. polynomial) growth in the first few disease generations, owing to clustering in contact patterns, spatial effects, inhomogeneous mixing, reactive behaviour changes or other...... and simulations from mechanistic models, and provide validation against a range of empirical disease datasets. Our results suggest that subexponential growth in the early phase of an epidemic is the rule rather the exception. Mechanistic simulations show that slight modifications to the classical susceptible...

  16. Stochastic persistence and stationary distribution in an SIS epidemic model with media coverage

    Science.gov (United States)

    Guo, Wenjuan; Cai, Yongli; Zhang, Qimin; Wang, Weiming

    2018-02-01

    This paper aims to study an SIS epidemic model with media coverage from a general deterministic model to a stochastic differential equation with environment fluctuation. Mathematically, we use the Markov semigroup theory to prove that the basic reproduction number R0s can be used to control the dynamics of stochastic system. Epidemiologically, we show that environment fluctuation can inhibit the occurrence of the disease, namely, in the case of disease persistence for the deterministic model, the disease still dies out with probability one for the stochastic model. So to a great extent the stochastic perturbation under media coverage affects the outbreak of the disease.

  17. Acute hemorrhagic conjunctivitis epidemic in São Paulo State, Brazil, 2011

    Directory of Open Access Journals (Sweden)

    Norma H. Medina

    Full Text Available ABSTRACT Acute hemorrhagic conjunctivitis (AHC infection is highly contagious and can lead to explosive epidemics. In early February 2011, the Center for Epidemiologic Surveillance of the State of São Paulo Health Secretariat (SES-SP in Brazil received reports of conjunctivitis outbreaks from rural areas of the state that subsequently spread statewide. This report describes that AHC epidemic and its etiologic agent. Data from the Ministry of Health Information System for Notifiable Diseases (SinanNet and the SES-SP epidemiologic surveillance system for conjunctivitis, developed to detect outbreaks, confirm the etiologic agent, and carry out control measures, were analyzed. Eye (conjunctival swab samples were taken from patients with clinical presentation of viral conjunctivitis to perform viral laboratory diagnosis. A total of 1 067 981 conjunctivitis cases were reported to the surveillance system for 2011; there was an increase in the number of cases in epidemiologic weeks 6–26 (summer season versus previous years. Most cases occurred in the metropolitan region of Greater São Paulo. Of 93 collected samples, 57 tested positive for coxsackievirus-A24 (CV-A24, based on virus isolation in tissue-culture cell lines, reverse transcription polymerase chain reaction (RT-PCR, and enterovirus sequencing of RT-PCR. The data analysis showed that the fast-spreading etiologic agent of the AHC epidemic that occurred in the summer of 2011 was CV-A24. The AHC epidemic was due to an enterovirus that occurred sporadically, spread rapidly and with great magnitude, and had substantial socioeconomic impact due to the high level of absenteeism at work and school.

  18. Trichinellosis epidemics in AP Vojvodina in the period 2000-2009

    Directory of Open Access Journals (Sweden)

    Šeguljev Zorica

    2011-01-01

    Full Text Available In the observed decade, 1300 cases of trichinellosis were registered in Vojvodina, including three with a lethal outcome. The lethality was 0.23%. The incidences of trichinellosis ranged from 2.2/100,000 to 13.6/100,000. The rate of incidence depends both on the number of epidemics and the size of the epidemic reported in a year. Most incidences were reported in 2002 and 2005, as a consequence of the spread of trichinellosis through the purchase of infested food. The epidemic of trichinellosis in the Middle Banat district that started at the end of 2001 is considered to be the largest outbreak of human trichinellosis in Vojvodina, when 313 people got sick. In most of the cases the affected people reported they had eaten smoked sausages. The high incidence of trichinellosis in 2005 was a consequence of three thrichinellosis outbreaks that had been spreading through infested smoked sausages originating from illegal production and trade. More than 200 cases of trichinellosis were reported in Vojvodina. Today, Srem is still considered a hyperendemic area, because more than 30% of all the epidemics occur in this area. The available data indicate that trichinellosis is spread all over Vojvodina and that the absence of control results in the risk from the incidence of human trichinellosis. In many European countries the epidemiological situation is stable, but in our country trichinellosis is the most important zoonotic disease. This unstable epidemiological situation is the consequence of the widespread infection, culinary customs, and the fact that there is inadequate control of meat and meat products in households and illegal trade.

  19. 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.

  20. 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.

  1. The Chikungunya epidemic in Italy and its repercussion on the blood system.

    Science.gov (United States)

    Liumbruno, Giancarlo Maria; Calteri, Deanna; Petropulacos, Kyriakoula; Mattivi, Andrea; Po, Claudio; Macini, Pierluigi; Tomasini, Ivana; Zucchelli, Paolo; Silvestri, Anna Rita; Sambri, Vittorio; Pupella, Simonetta; Catalano, Liviana; Piccinini, Vanessa; Calizzani, Gabriele; Grazzini, Giuliano

    2008-10-01

    The Chikungunya virus (CHIKV) is transmitted by Aedes mosquitoes and recently caused a massive epidemic on La Réunion Island, in the Indian Ocean. Between July and September 2007 it caused the first autochthonous epidemic outbreak in Europe, in the Region of Emilia-Romagna in the north-east of Italy. After the first reports of an unusually high number of patients with a febrile illness of unknown origin in two contiguous villages, an outbreak investigation was carried out to identify the primary source of infection, the modes of transmission and the dynamics of the epidemic. An active surveillance system was also implemented. Laboratory diagnosis was performed through serology and polymerase chain reaction (PCR) analysis. Blood donation was discontinued in the areas involved from September to October 2007 and specific precautionary blood safety and self-sufficiency measures were adopted by the regional health and blood authorities and the National Blood Centre. An estimate method to early assess the risk of viraemic blood donations by asymptomatic donors was developed, as a tool for "pragmatic" risk assessment and management, aiming at providing a reliable order of magnitude of the mean risk of CHIKV transmission through blood transfusion. Two hundred and seventeen cases of CHIKV infection were identified between 4th July and 28th September. The disease was fairly mild in most of the cases. The precautionary measures adopted in the blood system caused a considerable reduction of the collection of blood components and of the delivery of plasma to the pharmaceutical industry for contract manufacturing. The estimated risk of CHIKV transmission through blood transfusion peaked in the third week of August. ACHIKV epidemic poses considerable problems for public health authorities, who not only need good routine programmes of vector control and epidemiological surveillance but also local and national emergency plans to sustain the blood supply, so as to promptly deal

  2. Genetic diversity of ORF3 and spike genes of porcine epidemic diarrhea virus in Thailand.

    Science.gov (United States)

    Temeeyasen, Gun; Srijangwad, Anchalee; Tripipat, Thitima; Tipsombatboon, Pavita; Piriyapongsa, Jittima; Phoolcharoen, Waranyoo; Chuanasa, Taksina; Tantituvanont, Angkana; Nilubol, Dachrit

    2014-01-01

    Porcine epidemic diarrhea virus (PEDV) has become endemic in the Thai swine industry, causing economic losses and repeated outbreaks since its first emergence in 2007. In the present study, 69 Thai PEDV isolates were obtained from 50 swine herds across Thailand during the period 2008-2012. Both partial and complete nucleotide sequences of the spike (S) glycoprotein and the nucleotide sequences of ORF3 genes were determined to investigate the genetic diversity and molecular epidemiology of Thai PEDV. Based on the analysis of the partial S glycoprotein genes, the Thai PEDV isolates were clustered into 2 groups related to Korean and Chinese field isolates. The results for the complete spike genes, however, demonstrated that both groups were grouped in the same cluster. Interestingly, both groups of Thai PEDV isolates had a 4-aa (GENQ) insertion between positions 55 and 56, a 1-aa insertion between positions 135 and 136, and a 2-aa deletion between positions 155 and 156, making them identical to the Korean KNU series and isolates responsible for outbreaks in China in recent years. In addition to the complete S sequences, the ORF3 gene analyses suggested that the isolates responsible for outbreaks in Thailand are not vaccine related. The results of this study suggest that the PEDV isolates responsible for outbreaks in Thailand since its emergence represent a variant of PEDV that was previously reported in China and Korea. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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...

  5. An outbreak of aseptic meningitis in Podlaskie Voivodeship in 2014

    Directory of Open Access Journals (Sweden)

    Magda Orzechowska

    2016-12-01

    Full Text Available Enteroviruses cause common infections with various clinical course and forms, such as hand-foot-and-mouth disease (Boston exanthem disease, herpangina, myocarditis and pericarditis, widespread myositis (epidemic pleurodynia, Bornholm disease, or aseptic inflammation of the nervous system, among children and adolescents. An increase in aseptic meningitis cases of enteroviral aetiology, including the E30 virus, was occasionally observed in various European countries. In 2014, an outbreak of aseptic meningitis was reported in Podlaskie Voivodeship. A total of 640 cases were reported between June 1 and November 30, 2014, of which 228 had confirmed enteroviral aetiology. Summer and autumn seasons favour the incidence of viral infections of the central nervous system. Symptomatic infections are more common in males than females. Infections with enterovirus show the tendency to form endemic regions.

  6. Measles outbreak--California, December 2014-February 2015.

    Science.gov (United States)

    Zipprich, Jennifer; Winter, Kathleen; Hacker, Jill; Xia, Dongxiang; Watt, James; Harriman, Kathleen

    2015-02-20

    On January 5, 2015, the California Department of Public Health (CDPH) was notified about a suspected measles case. The patient was a hospitalized, unvaccinated child, aged 11 years with rash onset on December 28. The only notable travel history during the exposure period was a visit to one of two adjacent Disney theme parks located in Orange County, California. On the same day, CDPH received reports of four additional suspected measles cases in California residents and two in Utah residents, all of whom reported visiting one or both Disney theme parks during December 17-20. By January 7,seven California measles cases had been confirmed, and CDPH issued a press release and an Epidemic Information Exchange (Epi-X) notification to other states regarding this outbreak. Measles transmission is ongoing.

  7. Risk factors for porcine reproductive and respiratory syndrome outbreaks in Vietnamese small stock farms.

    Science.gov (United States)

    Truong, V M; Gummow, B

    2014-07-01

    To examine risk factors that could have played a role in the 2010 porcine reproductive and respiratory syndrome (PRRS) outbreak in Yenhung district, Quangninh province, North-Vietnam, with the purpose of establishing why existing control measures implemented after previous outbreaks had failed to prevent further outbreaks. A case-control study was carried out in Yenhung district. Data were obtained by an interview-based questionnaire survey. The sampling unit was households, which equated to small-scale pig farms. A total of 150 case and 150 control households were selected at communes affected by the 2010 PRRS epidemic during April to June. Risk factors were analysed using binary logistic regression and unconditional multiple logistic regression. Households infected with PRRS were significantly associated with multiple variables belonging to three main groups: (1) location of the farms: i.e. farms positioned risk factor most strongly associated with infected households in the 2010 outbreak (OR=22; 95% CI=12-42). The results show that the epidemiology of PRRS in Quangninh province was linked to sociological and cultural practices, and that effective PRRS control needs an integrated approach coupled with behavioural changes in the pig raising practices of the general public. Failure to recognise this could explain why further outbreaks have occurred.

  8. Phocine distemper virus (PDV) seroprevalence as predictor for future outbreaks in harbour seals.

    Science.gov (United States)

    Ludes-Wehrmeister, Eva; Dupke, Claudia; Harder, Timm C; Baumgärtner, Wolfgang; Haas, Ludwig; Teilmann, Jonas; Dietz, Rune; Jensen, Lasse F; Siebert, Ursula

    2016-02-01

    Phocine distemper virus (PDV) infections caused the two most pronounced mass mortalities in marine mammals documented in the past century. During the two outbreaks, 23,000 and 30,000 harbour seals (Phoca vitulina), died in 1988/1989 and 2002 across populations in the Wadden Sea and adjacent waters, respectively. To follow the mechanism and development of disease spreading, the dynamics of Morbillivirus-specific antibodies in harbour seal populations in German and Danish waters were examined. 522 serum samples of free-ranging harbour seals of different ages were sampled between 1990 and 2014. By standard neutralisation assays, Morbillivirus-specific antibodies were detected, using either the PDV isolate 2558/Han 88 or the related canine distemper virus (CDV) strain Onderstepoort. A total of 159 (30.5%) of the harbour seals were seropositive. Annual seroprevalence rates showed an undulating course: Peaks were seen in the post-epidemic years 1990/1991 and 2002/2003. Following each PDV outbreak, seroprevalence decreased and six to eight years after the epidemics samples were tested seronegative, indicating that the populations are now again susceptible to new PDV outbreak. After the last outbreak in 2002, the populations grew steadily to an estimated maximum (since 1975) of about 39,100 individuals in the Wadden Sea in 2014 and about 23,540 harbour seals in the Kattegat area in 2013. A re-appearence of PDV would presumably result in another epizootic with high mortality rates as encountered in the previous outbreaks. The current high population density renders harbour seals vulnerable to rapid spread of infectious agents including PDV and the recently detected influenza A virus. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Remote Sensing Contributions to Prediction and Risk Assessment of Natural Disasters Caused by Large Scale Rift Valley Fever Outbreaks

    Science.gov (United States)

    Anyamba, Assaf; Linthicum, Kenneth J.; Small, Jennifer; Britch, S. C.; Tucker, C. J.

    2012-01-01

    Remotely sensed vegetation measurements for the last 30 years combined with other climate data sets such as rainfall and sea surface temperatures have come to play an important role in the study of the ecology of arthropod-borne diseases. We show that epidemics and epizootics of previously unpredictable Rift Valley fever are directly influenced by large scale flooding associated with the El Ni o/Southern Oscillation. This flooding affects the ecology of disease transmitting arthropod vectors through vegetation development and other bioclimatic factors. This information is now utilized to monitor, model, and map areas of potential Rift Valley fever outbreaks and is used as an early warning system for risk reduction of outbreaks to human and animal health, trade, and associated economic impacts. The continuation of such satellite measurements is critical to anticipating, preventing, and managing disease epidemics and epizootics and other climate-related disasters.

  10. Selection tool for foodborne norovirus outbreaks.

    Science.gov (United States)

    Verhoef, Linda P B; Kroneman, Annelies; van Duynhoven, Yvonne; Boshuizen, Hendriek; van Pelt, Wilfrid; Koopmans, Marion

    2009-01-01

    Detection of pathogens in the food chain is limited mainly to bacteria, and the globalization of the food industry enables international viral foodborne outbreaks to occur. Outbreaks from 2002 through 2006 recorded in a European norovirus surveillance database were investigated for virologic and epidemiologic indicators of food relatedness. The resulting validated multivariate logistic regression model comparing foodborne (n = 224) and person-to-person (n = 654) outbreaks was used to create a practical web-based tool that can be limited to epidemiologic parameters for nongenotyping countries. Non-genogroup-II.4 outbreaks, higher numbers of cases, and outbreaks in restaurants or households characterized (sensitivity = 0.80, specificity = 0.86) foodborne outbreaks and reduced the percentage of outbreaks requiring source-tracing to 31%. The selection tool enabled prospectively focused follow-up. Use of this tool is likely to improve data quality and strain typing in current surveillance systems, which is necessary for identification of potential international foodborne outbreaks.

  11. Norovirus: U.S. Trends and Outbreaks

    Science.gov (United States)

    ... harvested from contaminated water and raspberries irrigated with contaminated water have caused norovirus outbreaks. Norovirus on Cruise Ships Over 90% of diarrheal disease outbreaks on cruise ships are caused by norovirus ( ...

  12. Reporting and Surveillance for Norovirus Outbreaks

    Science.gov (United States)

    ... Vaccine Surveillance Network (NVSN) Foodborne Diseases Active Surveillance Network (FoodNet) National Outbreak Reporting System (NORS) Estimates of Foodborne Illness in the United States CDC's Vessel Sanitation Program CDC Feature: Surveillance for Norovirus Outbreaks Top ...

  13. Two aircraft carriers’ perspectives: a comparative of control measures in shipboard H1N1 outbreaks.

    Science.gov (United States)

    Harwood, Jared L; LaVan, Joseph T; Brand, George J

    2013-02-01

    The USS George Washington (GW) and the USS Ronald Reagan (RR), 2 US Navy aircraft carriers, experienced almost simultaneous outbreaks of novel H1N1 influenza A in the summer of 2009. We compared the respective epidemic control measures taken and subsequent lessons learned. Data were collated from both outbreaks to assess various elements including attack rate, isolation/quarantine protocols, and treatment methods. The respective duration of each outbreak was compared with survival curve analysis. The number of personnel affected in each outbreak was compared using χ2 analysis. Differences were found in the protocols used on the 2 ships. The GW treated about two-thirds of the patients with oseltamivir through day 14 and quarantined all patients meeting case definition throughout the outbreak. Face masks were used throughout. The RR used oseltamivir and quarantined many fewer patients (through days 5 and 3, respectively). No face masks were used after day 5. The outbreaks were similar in duration (GW = 25 days, RR = 27 days, P = .38), but the RR had significantly more cases (n = 253 vs 142, P < .0001). A portion of each group had samples that were confirmed H1N1 by polymerase chain reaction. GW's protocol, including aggressive oseltamivir treatment of two-thirds of the cases and quarantine throughout the duration decreased the overall number of personnel affected, likely reducing the overall control reproduction number. Both outbreaks were similar in duration. Even though the GW expended significantly more resources than the RR, if the 2009 pandemic H1N1 strain had been as clinically severe as the 1918 pandemic, a more stringent treatment protocol may have been the only way to prevent significant operational impact.

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

    Directory of Open Access Journals (Sweden)

    S Napp

    relationship was not linear, probably as a result of the complex relationship between temperature and the different parameters affecting BTV transmission. Rt values for BTV-1 in Andalusia fell below the threshold of 1 when temperatures dropped below 21°C, a much higher threshold than that reported in other BTV outbreaks, such as the BTV-8 epidemic in Northern Europe. This divergence may be explained by differences in the adaptation to temperature of the main vectors of the BTV-1 epidemic in Andalusia (Culicoides imicola compared those of the BTV-8 epidemic in Northern Europe (Culicoides obsoletus. Importantly, we found that BTV transmission (Rt value increased significantly in areas with higher densities of sheep. Our analysis also established that control of BTV-1 in Andalusia was complicated by the simultaneous establishment of several distant foci at the start of the epidemic, which may have been caused by several independent introductions of infected vectors from the North of Africa. We discuss the implications of these findings for BTV surveillance and control in this region of Europe.

  15. TOWARDS MODELING DISEASE OUTBREAK NOTIFICATION SYSTEMS

    OpenAIRE

    Farag Azzedin; Jaweed Yazdani,; Salahadin Adam; Mustafa Ghaleb

    2014-01-01

    Disease outbreak detection, monitoring and notification systems play an important role in assessing threats to public health since disease outbreaks are becoming increasingly common world-wide. There are several systems in use around the world, with coverage of national, international and global disease outbreaks. These systems use different taxonomies and classifications for the detection and prioritization of potential disease outbreaks. In this paper, we study and analyze th...

  16. The dengue preface to endemic in mainland China: the historical largest outbreak by Aedes albopictus in Guangzhou, 2014.

    Science.gov (United States)

    Luo, Lei; Jiang, Li-Yun; Xiao, Xin-Cai; Di, Biao; Jing, Qin-Long; Wang, Sheng-Yong; Tang, Jin-Ling; Wang, Ming; Tang, Xiao-Ping; Yang, Zhi-Cong

    2017-09-22

    Dengue was regarded as a mild epidemic in mainland China transmitted by Aedes albopictus. However, the 2014 record-breaking outbreak in Guangzhou could change the situation. In order to provide an early warning of epidemic trends and provide evidence for prevention and control strategies, we seek to characterize the 2014 outbreak through application of detailed cases and entomological data, as well as phylogenetic analysis of viral envelope (E) gene. We used case survey data identified through the Notifiable Infectious Disease Report System, entomological surveillance and population serosurvey, along with laboratory testing for IgM/IgG, NS1, and isolation of viral samples followed by E gene sequencing and phylogenetic analysis to examine the epidemiological and molecular characteristics of the outbreak. The 2014 dengue outbreak in Guangzhou accounted for nearly 80% of total reported cases that year in mainland China; a total of 37,376 cases including 37,340 indigenous cases with incidence rate 2908.3 per million and 36 imported cases were reported in Guangzhou, with 14,055 hospitalized and 5 deaths. The epidemic lasted for 193 days from June 11 to December 21, with the highest incidence observed in domestic workers, the unemployed and retirees. The inapparent infection rate was 18.00% (135/750). In total, 96 dengue virus 1 (DENV-1) and 11 dengue virus 2 (DENV-2) strains were isolated. Phylogenetic analysis indicated that the DENV-1 strains were divided into genotype I and V, similar to the strains isolated in Guangzhou and Dongguan in 2013. The DENV-2 strains isolated were similar to those imported from Thailand on May 11 in 2014 and that imported from Indonesia in 2012. The 2014 dengue epidemic was confirmed to be the first co-circulation of DENV-1 and DENV-2 in Guangzhou. The DENV-1 strain was endemic, while the DENV-2 strain was imported, being efficiently transmitted by the Aedes albopictus vector species at levels as high as Aedes aegypti.

  17. Enhancing preparation for large Nipah outbreaks beyond Bangladesh: Preventing a tragedy like Ebola in West Africa

    Directory of Open Access Journals (Sweden)

    Halsie Donaldson

    2018-07-01

    Full Text Available The Nipah virus has been transmitted from person-to-person via close contact in non-urban parts of India (including Kerala May 2018, Bangladesh, and the Philippines. It can cause encephalitis and pneumonia, and has a high case fatality rate. Nipah is a One Health zoonotic infectious disease linked to fruit bats, and sometimes pigs or horses. We advocate anticipating and preparing for urban and larger rural outbreaks of Nipah. Immediate enhanced preparations would include standardized guidance on infection prevention and control, and personal protective equipment, from the World Health Organization (WHO on their OpenWHO website and 2018 “Managing Epidemics” handbook, along with adding best clinical practices by experts in countries with multiple outbreaks such as Bangladesh and India. Longer-term enhanced preparations include accelerating development of field diagnostics, antiviral drugs, immune-based therapies, and vaccines. WHO-coordinated multi-partner protocols to test investigational treatments, diagnostics, and vaccines are needed, by analogy to such protocols for Ebola during the unanticipated pan-epidemic in Guinea, Liberia, and Sierra Leone. Anticipating and preparing now for urban and rural Nipah outbreaks in nations with no experience with Nipah will help avoid the potential for what the United Nations 2016 report on Ebola in West Africa called a “preventable tragedy”. Keywords: Nipah epidemics beyond Bangladesh, Nipah countermeasures, Nipah, One Health

  18. Management of outbreaks of nosocomial pathogens in Neonatal Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    B. Ghirardi

    2013-12-01

    Full Text Available Outbreaks of nosocomial pathogens are one of the most relevant problems in Neonatal Intensive Care Unit (NICU. Many factors contribute to the onset of an epidemic, including virulence of the pathogen and vulnerability of the infants hospitalized in NICU. Outbreaks are often caused by multidrug-resistant organisms (MDROs. MDROs are defined as microorganisms, predominantly bacteria, that are resistant to one or more classes of antimicrobial agents. MDROs, including methicillin-resistant Staphylococcus aureus (MRSA, vancomycin-resistant enterococci (VRE and certain gram-negative bacilli (GNB, have important infection control implications. Once MDROs are introduced into a healthcare setting, transmission and persistence of the resistant strain is determined by the availability of vulnerable patients, selective pressure exerted by antimicrobial use, increased potential for transmission from larger numbers of infected or colonized patients (“colonization pressure”, and the impact of adherence to prevention efforts. Often, routine infection control measures are not enough to contain outbreaks, and additional control measures are needed, including implementation of hand hygiene, cohorting of infected/colonized infants, neonatal surveillance cultures, screening of healthcare workers and decolonization of neonates and/or healthcare workers in selected cases. In this review, we report the practices we developed in our NICU to contain an epidemic. These recommendations reflect the experience of the group, as well as the findings of the current literature.

  19. Dengue Outbreak in Hadramout, Yemen, 2010: An Epidemiological Perspective

    Science.gov (United States)

    Ghouth, Abdulla Salim Bin; Amarasinghe, Ananda; Letson, G. William

    2012-01-01

    We analyzed surveillance data of a dengue outbreak (2010) reported to the Hadramout Health Office (Yemen) and retrospectively analyzed dengue-related epidemiological and entomological events reported in Hadramout from 2005 to 2009. A total of 630 immunoglobulin M (IgM) -confirmed dengue cases of 982 febrile cases was reported during the period from February to June of 2010; 12 cases died, giving case fatality a rate of 1.9%. Among febrile cases, the highest proportion of dengue cases (37.3%) was reported in the 15- to 24-year-old age group. The overall attack rate was 0.89/1,000. The average number of cases reported by month over the preceding 5-year period compared with the 2010 data is consistent with endemicity of dengue in the region and supports epidemic designation for the dengue activity in 2010. Recognition of endemic dengue transmission and potential for substantial dengue epidemics highlight the need for consistent laboratory-based surveillance that can support prevention and control activities accordingly. PMID:22665621

  20. Zika virus infections in pregnancy: epidemics and case management

    Directory of Open Access Journals (Sweden)

    Fatih sahiner

    2016-03-01

    Full Text Available Zika virus is an RNA virus belonging to the Flaviviridae family, and is primarily transmitted by Aedes mosquitoes. Only a small number of cases had been described until 2007 when the first major Zika virus outbreak occurred on Yap Island, Micronesia. Approximately 80% of people infected with Zika virus do not exhibit any symptoms. Symptomatic infections are generally moderate and characterized by acute onset of fever, maculopapular rash, arthralgia, or conjunctivitis. The virus has recently attracted a broad interest due to the emerging cases of microcephaly that are possibly associated with mothers infected by the Zika virus during pregnancy, and the regional increases in the incidence of Guillain-Barre syndrome during the epidemic periods. Although the relationship between Zika virus infection and these abnormalities is not obviously understood yet, Zika virus testing is recommended for infants with microcephaly or intracranial calcifications whose mothers were potentially infected with the Zika virus during pregnancy. Every day, new reports are being published about the outbreaks associated with this virus; nevertheless, no new cases of this virus have been reported in Turkey. Despite this, we cannot currently exclude the possibility of the encounter with the virus because of the presence of Aedes mosquitoes, which are responsible for the spread of the virus, are prevalent in Turkey, and an increasing number of travel-related cases are being reported from different countries. In the light of the current knowledge on this virus, this review aims to discuss the course of Zika virus infections in detail, especially congenital infection, and presenting current information about the case management and preventive measures. [Cukurova Med J 2016; 41(1.000: 143-151

  1. Measles (Rubeola) Cases and Outbreaks

    Science.gov (United States)

    ... Address What’s this? Submit What's this? Submit Button Measles Cases and Outbreaks Language: English (US) Español (Spanish) ... Español: Casos y brotes de sarampión Number of measles cases by year since 2010 Measles cases per ...

  2. Outbreak of Sporotrichosis, Western Australia

    Science.gov (United States)

    Feeney, Kynan T.; Whittle, Amanda J.; Altman, Shelley A.; Speers, David J.

    2007-01-01

    A cluster of sporotrichosis cases occurred in the Busselton-Margaret River region of Western Australia from 2000 to 2003. Epidemiologic investigation and mycologic culture for Sporothrix schenckii implicated hay initially distributed through a commercial hay supplier as the source of the outbreak. Declining infection rates have occurred after various community measures were instigated. PMID:17953099

  3. Larval outbreaks in West Greenland

    DEFF Research Database (Denmark)

    Lund, Magnus; Raundrup, Katrine; Westergaard-Nielsen, Andreas

    2017-01-01

    effects of a larval outbreak in 2011 on vegetation productivity and CO2 exchange. We estimate a decreased carbon (C) sink strength in the order of 118–143 g C m−2, corresponding to 1210–1470 tonnes C at the Kobbefjord catchment scale. The decreased C sink was, however, counteracted the following years...

  4. 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.

  5. 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

  6. Essential information: Uncertainty and optimal control of Ebola outbreaks.

    Science.gov (United States)

    Li, Shou-Li; Bjørnstad, Ottar N; Ferrari, Matthew J; Mummah, Riley; Runge, Michael C; Fonnesbeck, Christopher J; Tildesley, Michael J; Probert, William J M; Shea, Katriona

    2017-05-30

    Early resolution of uncertainty during an epidemic outbreak can lead to rapid and efficient decision making, provided that the uncertainty affects prioritization of actions. The wide range in caseload projections for the 2014 Ebola outbreak caused great concern and debate about the utility of models. By coding and running 37 published Ebola models with five candidate interventions, we found that, despite this large variation in caseload projection, the ranking of management options was relatively consistent. Reducing funeral transmission and reducing community transmission were generally ranked as the two best options. Value of information (VoI) analyses show that caseloads could be reduced by 11% by resolving all model-specific uncertainties, with information about model structure accounting for 82% of this reduction and uncertainty about caseload only accounting for 12%. Our study shows that the uncertainty that is of most interest epidemiologically may not be the same as the uncertainty that is most relevant for management. If the goal is to improve management outcomes, then the focus of study should be to identify and resolve those uncertainties that most hinder the choice of an optimal intervention. Our study further shows that simplifying multiple alternative models into a smaller number of relevant groups (here, with shared structure) could streamline the decision-making process and may allow for a better integration of epidemiological modeling and decision making for policy.

  7. Essential information: Uncertainty and optimal control of Ebola outbreaks

    Science.gov (United States)

    Li, Shou-Li; Bjornstad, Ottar; Ferrari, Matthew J.; Mummah, Riley; Runge, Michael C.; Fonnesbeck, Christopher J.; Tildesley, Michael J.; Probert, William J. M.; Shea, Katriona

    2017-01-01

    Early resolution of uncertainty during an epidemic outbreak can lead to rapid and efficient decision making, provided that the uncertainty affects prioritization of actions. The wide range in caseload projections for the 2014 Ebola outbreak caused great concern and debate about the utility of models. By coding and running 37 published Ebola models with five candidate interventions, we found that, despite this large variation in caseload projection, the ranking of management options was relatively consistent. Reducing funeral transmission and reducing community transmission were generally ranked as the two best options. Value of information (VoI) analyses show that caseloads could be reduced by 11% by resolving all model-specific uncertainties, with information about model structure accounting for 82% of this reduction and uncertainty about caseload only accounting for 12%. Our study shows that the uncertainty that is of most interest epidemiologically may not be the same as the uncertainty that is most relevant for management. If the goal is to improve management outcomes, then the focus of study should be to identify and resolve those uncertainties that most hinder the choice of an optimal intervention. Our study further shows that simplifying multiple alternative models into a smaller number of relevant groups (here, with shared structure) could streamline the decision-making process and may allow for a better integration of epidemiological modeling and decision making for policy.

  8. Sporothrix brasiliensis outbreaks and the rapid emergence of feline sporotrichosis.

    Science.gov (United States)

    Sanchotene, Karine Ortiz; Madrid, Isabel Martins; Klafke, Gabriel Baracy; Bergamashi, Mariana; Della Terra, Paula Portella; Rodrigues, Anderson Messias; de Camargo, Zoilo Pires; Xavier, Melissa Orzechowski

    2015-11-01

    Sporotrichosis is the main subcutaneous mycosis in Brazil, and is caused by Sporothrix schenckii and allied species. Sporothrix propagules present on soil and plant debris may be traumatically inoculated into the cutaneous/ subcutaneous tissues of the warm-blooded host. An alternative route involves direct animal-animal and animal-human transmissions through deep scratches and bites of diseased cats. Sporotrichosis is much more common than previously appreciated with several cases emerging over the years especially in South and Southeast Brazil. We conducted an epidemiological surveillance in endemic areas of feline sporotrichosis in the southern region of Rio Grande do Sul state, Brazil. Over the last 5-year period the number of feline sporotrichosis in Rio Grande increased from 0.75 new cases per month in 2010 to 3.33 cases per month in 2014. The wide geographic distribution of diagnosed cases highlights the dynamics of Sporothrix transmission across urban areas with high population density. Molecular identification down to species level by PCR-RFLP of cat-transmitted Sporothrix revealed the emergence of the clonal offshoot S. brasiliensis during feline outbreaks; this scenario is similar to the epidemics taking place in the metropolitan areas of Rio de Janeiro and São Paulo. Controlling and preventing sporotrichosis outbreaks are essential steps to managing the disease among humans and animals. © 2015 Blackwell Verlag GmbH.

  9. An outbreak of leptospirosis among Peruvian military recruits.

    Science.gov (United States)

    Russell, Kevin L; Montiel Gonzalez, Marco A; Watts, Douglas M; Lagos-Figueroa, Roberto C; Chauca, Gloria; Ore, Marianela; Gonzalez, Jose E; Moron, Cecilia; Tesh, Robert B; Vinetz, Joseph M

    2003-07-01

    Acute undifferentiated febrile illnesses are common in tropical developing countries but are difficult to diagnose on clinical grounds alone. Leptospirosis is rarely diagnosed, despite evidence that sporadic cases and epidemics continue to occur worldwide. The purpose of this study was to diagnose an outbreak of acute undifferentiated febrile illness among Peruvian military recruits that developed after a training exercise in the high jungle rainforest of Peru. Of 193 military recruits, 78 developed an acute febrile illness with varied manifestations. Of these, 72 were found to have acute leptospirosis by a microscopic agglutination test (MAT). An enzyme-linked immunosorbent assay using Leptospira biflexa antigen was insensitive for the detection of anti-leptospiral IgM antibodies compared with the MAT (20 of 72, 28%). This outbreak of acute undifferentiated febrile illness among Peruvian military recruits was due to leptospirosis. High clinical suspicion, initiation of preventative measures, and performance of appropriate diagnostic testing is warranted in similar settings to identify, treat, and prevent leptospirosis.

  10. Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

    Directory of Open Access Journals (Sweden)

    Narendran Pradeep Kumar

    2011-12-01

    Full Text Available India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8% suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68% of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002. Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019 and 31-40 (χ2 = 5.84; p = 0.016 years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

  11. Contract Support and Facilitation of Epidemic Outbreak Surveillance (EOS) Program Final Operating Capability (FOC)

    Science.gov (United States)

    2007-08-01

    parapertussis ASR* Market HSV Non-typing ASR* Market HSV Typing ASR* Market Enterovirus ASR* Market Parvovirus B19 ASR* Market TACSTD1 ASR* Market...utilizes a monoclonal antibody against the group- reactive antigen of human adenovirus to qualitatively detect the presence of this antigen in...hybridization between pathogens for most positive strains tested, i.e. reactivity of fluA with fluA, fluB, and Strep. pyogenes. Conversely, most of

  12. The impact of movements and animal density on continental scale cattle disease outbreaks in the United States.

    Directory of Open Access Journals (Sweden)

    Michael G Buhnerkempe

    Full Text Available Globalization has increased the potential for the introduction and spread of novel pathogens over large spatial scales necessitating continental-scale disease models to guide emergency preparedness. Livestock disease spread models, such as those for the 2001 foot-and-mouth disease (FMD epidemic in the United Kingdom, represent some of the best case studies of large-scale disease spread. However, generalization of these models to explore disease outcomes in other systems, such as the United States's cattle industry, has been hampered by differences in system size and complexity and the absence of suitable livestock movement data. Here, a unique database of US cattle shipments allows estimation of synthetic movement networks that inform a near-continental scale disease model of a potential FMD-like (i.e., rapidly spreading epidemic in US cattle. The largest epidemics may affect over one-third of the US and 120,000 cattle premises, but cattle movement restrictions from infected counties, as opposed to national movement moratoriums, are found to effectively contain outbreaks. Slow detection or weak compliance may necessitate more severe state-level bans for similar control. Such results highlight the role of large-scale disease models in emergency preparedness, particularly for systems lacking comprehensive movement and outbreak data, and the need to rapidly implement multi-scale contingency plans during a potential US outbreak.

  13. Ebola Virus Epidemic in West Africa: Global Health Economic Challenges, Lessons Learned, and Policy Recommendations.

    Science.gov (United States)

    Elmahdawy, Mahmoud; Elsisi, Gihan H; Carapinha, Joao; Lamorde, Mohamed; Habib, Abdulrazaq; Agyie-Baffour, Peter; Soualmi, Redouane; Ragab, Samah; Udezi, Anthony W; Usifoh, Cyril; Usifoh, Stella

    2017-09-01

    The Ebola virus has spread across several Western Africa countries, adding a significant financial burden to their health systems and economies. In this article the experience with Ebola is reviewed, and economic challenges and policy recommendations are discussed to help curb the impact of other diseases in the future. The West African Ebola virus disease epidemic started in resource-constrained settings and caused thousands of fatalities during the last epidemic. Nevertheless, given population mobility, international travel, and an increasingly globalized economy, it has the potential to re-occur and evolve into a global pandemic. Struggling health systems in West African countries hinder the ability to reduce the causes and effects of the Ebola epidemic. The lessons learned include the need for strengthening health systems, mainly primary care systems, expedited access to treatments and vaccines to treat the Ebola virus disease, guidance on safety, efficacy, and regulatory standards for such treatments, and ensuring that research and development efforts are directed toward existing needs. Other lessons include adopting policies that allow for better flow of relief, averting the adverse impact of strong quarantine policy that includes exaggerating the aversion behavior by alarming trade and business partners providing financial support to strengthen growth in the affected fragile economies by the Ebola outbreak. Curbing the impact of future Ebola epidemics, or comparable diseases, requires increased long-term investments in health system strengthening, better collaboration between different international organizations, more funding for research and development efforts aimed at developing vaccines and treatments, and tools to detect, treat, and prevent future epidemics. Copyright © 2017. Published by Elsevier Inc.

  14. Timing and utilization of antenatal care services in Liberia: Understanding the pre-Ebola epidemic context.

    Science.gov (United States)

    Luginaah, Isaac N; Kangmennaang, Joseph; Fallah, Mosoka; Dahn, Bernice; Kateh, Francis; Nyenswah, Tolbert

    2016-07-01

    In Liberia, 75% of those who died from 2014 Ebola epidemic were women and the effects of this gruelling epidemic were more severely felt by pregnant women. This immediately raised fears about the long-term impacts of the epidemic on maternal and child health. As part of a larger study, this paper uses Andersen's behavioural model of health care utilization and Goffman's stigma theory to explain the timing and utilization of maternal health services before the outbreak of the Ebola epidemic as a background to the potential long-term effects on maternal health. We conducted survival and multiple regression analysis using the 2007 (N = 3524) and 2013 (N = 5127) Liberia's Demographic and Health Survey (LDHS) data. Our sample consisted of women of reproductive age (15-49 years) that had given birth in the last five years preceding the survey year. The findings show that from 2007 to 2013, there was an overall improvement in the timing of first antenatal care (ANC) visits (TR = 0.92, p delivery with skilled birth attendants. The results also show county and regional disparities in the utilization of ANC services with South Eastern A region emerging as a relatively vulnerable place. Also, access to ANC services defined by distance to a health facility strongly predicted utilization. We argue that the Ebola epidemic likely eroded many of the previous gains in maternal health care, and may have left a lingering negative effect on the access and utilization of maternal health services in the long-term. The study makes relevant policy recommendations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Evidence for emergency vaccination having played a crucial role to control the 1965/66 foot-and-mouth disease outbreak in Switzerland

    Directory of Open Access Journals (Sweden)

    Dana eZingg

    2015-12-01

    Full Text Available Foot-and-mouth disease (FMD is a highly contagious disease which caused several large outbreaks in Europe in the last century. The last important outbreak in Switzerland took place in 1965/66 and affected more than 900 premises and more than 50,000 animals were slaughtered. Large scale emergency vaccination of the cattle and pig population has been applied to control the epidemic. In recent years, many studies have used infectious disease models to assess the impact of different disease control measures, including models developed for diseases exotic for the specific region of interest. Often, the absence of real outbreak data makes a validation of such models impossible. This study aimed to evaluate whether a spatial, stochastic simulation model (the Davis Animal Disease Simulation model can predict the course of a Swiss FMD epidemic based on the available historic input data on population structure, contact rates, epidemiology of the virus and quality of the vaccine. In addition, the potential outcome of the 1965/66 FMD epidemic without application of vaccination was investigated. Comparing the model outcomes to reality, only the largest 10% of the simulated outbreaks approximated the number of animals being culled. However, the simulation model highly overestimated the number of culled premises. While the outbreak duration could not be well reproduced by the model compared to the 1965/66 epidemic, it was able to accurately estimate the size of the area infected. Without application of vaccination the model predicted a much higher mean number of culled animals than with vaccination, demonstrating that vaccination was likely crucial in disease control for the Swiss FMD outbreak in 1965/66. The study demonstrated the feasibility to analyze historical outbreak data with modern analytical tools. However, it also confirmed that predicted epidemics from a most carefully parametrized model cannot integrate all eventualities of a real epidemic

  16. Ebola outbreak in West Africa: a neglected tropical disease

    Directory of Open Access Journals (Sweden)

    Alcides Troncoso

    2015-04-01

    Full Text Available Neglected tropical diseases (NTDs are remediable injustices of our times. Poverty is the starting point, and the ultimate outcome, of NTD. Ebola is just one of many NTDs that badly need attention. Ebola exacerbates West Africa's poverty crisis. The virus spreading in Guinea, Liberia and Sierra Leone has led to food shortages and neglect of other devastating tropical illnesses. A health crisis that was ignored for months until it was out of control is now beginning to get the attention required, if not the resources. So far, the world´s nations have contributed far less than the $ 1 billion. The U.N. estimates would need to control the epidemic before it becomes endemic. Past outbreaks of Ebola have flared up in remote, forested communities, disconnected from much of the outside world. But the outbreak in West Africa has not slowed yet, and it worsens there the chances of it spreading to other countries. Ebola draws attention to NTD. Ebola is not only a health emergency, but also it´s a poverty crisis. The current Global Ebola crisis presents a multitude of challenges in terms of our capacity to respond; the future is even less predictable. Ebola outbreak represents inequity in health as the occurrence of health differences considered unnecessary, avoidable, unfair, and unjust, thus adding a moral and ethical dimension to health inequalities. Health equity does not refer only to the fairness in the distribution of health or the provision of health care; rather, it is linked with the larger issues of fairness and justice in social arrangements.

  17. Investigation of key interventions for shigellosis outbreak control in China.

    Directory of Open Access Journals (Sweden)

    Tianmu Chen

    Full Text Available Shigellosis is a major public health concern in China, where waterborne disease outbreaks are common. Shigellosis-containing strategies, mostly single or multiple interventions, are implemented by primary-level health departments. Systematic assessment of the effectiveness of these measures is scarce. To estimate the efficacy of commonly used intervention strategies, we developed a Susceptible-Exposed-Infectious/Asymptomatic-Recovered-Water model. No intervention was predicted to result in a total attack rate (TAR of 90% of the affected population (95% confidence interval [CI]: 86.65-92.80 and duration of outbreak (DO of 89 days, and the use of single-intervention strategies can be futile or even counter-productive. Prophylactics and water disinfection did not improve TAR or DO. School closure for up to 3 weeks did not help but only increased DO. Isolation alone significantly increased DO. Only antibiotics treatment could shorten the DO to 35 days with TAR unaffected. We observed that these intervention effects were additive when in combined usage under most circumstances. Combined intervention "Isolation+antibiotics+prophylactics+water disinfection" was predicted to result in the lowest TAR (41.9%, 95%CI: 36.97-47.04% and shortest DO (28 days. Our actual Shigellosis control implementation that also included school closure for 1 week, attained comparable results and the modeling produced an epidemic curve of Shigellosis highly similar to our actual outbreak data. This lends a strong support to the reality of our model that provides a possible reference for public health professionals to evaluate their strategies towards Shigellosis control.

  18. 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.

  19. 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.

  20. 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...

  1. EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare), 2014. Scientific Opinion on porcine epidemic diarrhoea and emerging pig deltacoronavirus

    DEFF Research Database (Denmark)

    Bøtner, Anette

    In the last decade, many porcine epidemic diarrhoea (PED) outbreaks have been reported by several countries in Asia whereas only a few Member States of the European Union (EU) have reported PED clinical cases and/or PED virus (PEDV)-seropositive animals. This alphacoronavirus was first reported...... in the USA in May 2013, followed by rapid spread throughout the country and outbreaks reported by several countries in the Americas. The recent PEDV-EU isolates have high level of sequence identity to PEDV-Am isolates. Based on nucleotide sequencing, multiple variants of PEDV are circulating in Europe...

  2. 1600 AD Huaynaputina Eruption (Peru, Abrupt Cooling, and Epidemics in China and Korea

    Directory of Open Access Journals (Sweden)

    Jie Fei

    2016-01-01

    Full Text Available The 1600 AD Huaynaputina eruption in Peru was one of the largest volcanic eruptions in history over the past 2000 years. This study operated on the hypothesis that this event dramatically affected the weather and environment in China and the Korean Peninsula. Over the course of this research the Chinese and Korean historical literatures as well as dendrochronology records were examined. The historical evidence points to the conclusion that the eruption was followed by an abrupt cooling period and epidemic outbreaks in 1601 AD within both China and the Korean Peninsula. These records manifested themselves in unseasonably cold weather resulting in severe killing frosts in northern China in the summer and autumn of 1601 AD. In southern China (Zhejiang and Anhui Provinces and Shanghai Municipality, July was abnormally cold with snow, with an autumn that saw anomalously hot weather. In addition, there was unseasonable snowfall that autumn within Yunnan Province. Widespread disease outbreaks occurred in August, September, and October in northern and southern China. In Korea, the spring and early summer of 1601 AD were unusually cold, and conditions led to further widespread epidemics occurring in August.

  3. 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

  4. The importance of thinking beyond the water-supply in cholera epidemics: A historical urban case-study.

    Science.gov (United States)

    Phelps, Matthew D; Azman, Andrew S; Lewnard, Joseph A; Antillón, Marina; Simonsen, Lone; Andreasen, Viggo; Jensen, Peter K M; Pitzer, Virginia E

    2017-11-01

    Planning interventions to respond to cholera epidemics requires an understanding of the major transmission routes. Interrupting short-cycle (household, foodborne) transmission may require different approaches as compared long-cycle (environmentally-mediated/waterborne) transmission. However, differentiating the relative contribution of short- and long-cycle routes has remained difficult, and most cholera outbreak control efforts focus on interrupting long-cycle transmission. Here we use high-resolution epidemiological and municipal infrastructure data from a cholera outbreak in 1853 Copenhagen to explore the relative contribution of short- and long-cycle transmission routes during a major urban epidemic. We fit a spatially explicit time-series meta-population model to 6,552 physician-reported cholera cases from Copenhagen in 1853. We estimated the contribution of long-cycle waterborne transmission between neighborhoods using historical municipal water infrastructure data, fitting the force of infection from hydraulic flow, then comparing model performance. We found the epidemic was characterized by considerable transmission heterogeneity. Some neighborhoods acted as localized transmission hotspots, while other neighborhoods were less affected or important in driving the epidemic. We found little evidence to support long-cycle transmission between hydrologically-connected neighborhoods. Collectively, these findings suggest short-cycle transmission was significant. Spatially targeted cholera interventions, such as reactive vaccination or sanitation/hygiene campaigns in hotspot neighborhoods, would likely have been more effective in this epidemic than control measures aimed at interrupting long-cycle transmission, such as improving municipal water quality. We recommend public health planners consider programs aimed at interrupting short-cycle transmission as essential tools in the cholera control arsenal.

  5. 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.

  6. Core Genome Multilocus Sequence Typing for Identification of Globally Distributed Clonal Groups and Differentiation of Outbreak Strains of Listeria monocytogenes.

    Science.gov (United States)

    Chen, Yi; Gonzalez-Escalona, Narjol; Hammack, Thomas S; Allard, Marc W; Strain, Errol A; Brown, Eric W

    2016-10-15

    Many listeriosis outbreaks are caused by a few globally distributed clonal groups, designated clonal complexes or epidemic clones, of Listeria monocytogenes, several of which have been defined by classic multilocus sequence typing (MLST) schemes targeting 6 to 8 housekeeping or virulence genes. We have developed and evaluated core genome MLST (cgMLST) schemes and applied them to isolates from multiple clonal groups, including those associated with 39 listeriosis outbreaks. The cgMLST clusters were congruent with MLST-defined clonal groups, which had various degrees of diversity at the whole-genome level. Notably, cgMLST could distinguish among outbreak strains and epidemiologically unrelated strains of the same clonal group, which could not be achieved using classic MLST schemes. The precise selection of cgMLST gene targets may not be critical for the general identification of clonal groups and outbreak strains. cgMLST analyses further identified outbreak strains, including those associated with recent outbreaks linked to contaminated French-style cheese, Hispanic-style cheese, stone fruit, caramel apple, ice cream, and packaged leafy green salad, as belonging to major clonal groups. We further developed lineage-specific cgMLST schemes, which can include accessory genes when core genomes do not possess sufficient diversity, and this provided additional resolution over species-specific cgMLST. Analyses of isolates from different common-source listeriosis outbreaks revealed various degrees of diversity, indicating that the numbers of allelic differences should always be combined with cgMLST clustering and epidemiological evidence to define a listeriosis outbreak. Classic multilocus sequence typing (MLST) schemes targeting internal fragments of 6 to 8 genes that define clonal complexes or epidemic clones have been widely employed to study L. monocytogenes biodiversity and its relation to pathogenicity potential and epidemiology. We demonstrated that core genome MLST

  7. Outbreak of Bacillus cereus infections in a neonatal intensive care unit traced to balloons used in manual ventilation.

    Science.gov (United States)

    Van Der Zwet, W C; Parlevliet, G A; Savelkoul, P H; Stoof, J; Kaiser, A M; Van Furth, A M; Vandenbroucke-Grauls, C M

    2000-11-01

    In 1998, an outbreak of systemic infections caused by Bacillus cereus occurred in the Neonatal Intensive Care Unit of the University Hospital Vrije Universiteit, Amsterdam, The Netherlands. Three neonates developed sepsis with positive blood cultures. One neonate died, and the other two neonates recovered. An environmental survey, a prospective surveillance study of neonates, and a case control study were performed, in combination with molecular typing, in order to identify potential sources and transmission routes of infection. Genotypic fingerprinting by amplified-fragment length polymorphism (AFLP) showed that the three infections were caused by a single clonal type of B. cereus. The same strain was found in trachea aspirate specimens of 35 other neonates. The case control study showed mechanical ventilation with a Sensormedics ventilation machine to be a risk factor for colonization and/or infection (odds ratio, 9.8; 95% confidence interval, 1.1 to 88.2). Prospective surveillance showed that colonization with B. cereus occurred exclusively in the respiratory tract of mechanically ventilated neonates. The epidemic strain of B. cereus was found on the hands of nursing staff and in balloons used for manual ventilation. Sterilization of these balloons ended the outbreak. We conclude that B. cereus can cause outbreaks of severe opportunistic infection in neonates. Typing by AFLP proved very useful in the identification of the outbreak and in the analysis of strains recovered from the environment to trace the cause of the epidemic.

  8. Transmission of equine influenza virus during an outbreak is characterized by frequent mixed infections and loose transmission bottlenecks.

    Directory of Open Access Journals (Sweden)

    Joseph Hughes

    2012-12-01

    Full Text Available The ability of influenza A viruses (IAVs to cross species barriers and evade host immunity is a major public health concern. Studies on the phylodynamics of IAVs across different scales - from the individual to the population - are essential for devising effective measures to predict, prevent or contain influenza emergence. Understanding how IAVs spread and evolve during outbreaks is critical for the management of epidemics. Reconstructing the transmission network during a single outbreak by sampling viral genetic data in time and space can generate insights about these processes. Here, we obtained intra-host viral sequence data from horses infected with equine influenza virus (EIV to reconstruct the spread of EIV during a large outbreak. To this end, we analyzed within-host viral populations from sequences covering 90% of the infected yards. By combining gene sequence analyses with epidemiological data, we inferred a plausible transmission network, in turn enabling the comparison of transmission patterns during the course of the outbreak and revealing important epidemiological features that were not apparent using either approach alone. The EIV populations displayed high levels of genetic diversity, and in many cases we observed distinct viral populations containing a dominant variant and a number of related minor variants that were transmitted between infectious horses. In addition, we found evidence of frequent mixed infections and loose transmission bottlenecks in these naturally occurring populations. These frequent mixed infections likely influence the size of epidemics.

  9. How does increasing immunity change spread kernel parameters in subsequent outbreaks? – A simulation study on Bluetongue Virus

    DEFF Research Database (Denmark)

    Græsbøll, Kaare; Bødker, Rene; Enøe, Claes

    Modelling the spatial spread of vector borne diseases, one may choose methods ranging from statistic to process oriented. One often used statistic tool is the empirical spread kernel. An empiric spread kernel fitted to outbreak data provides hints on the spread mechanisms, and may provide a good...... estimate on how future epidemics could proceed under similar conditions. However, a number of variables influence the spread of vector borne diseases. If one of these changes significantly after an outbreak, it needs to be incorporated into the model to improve the prediction on future outbreaks. Examples...... of such changes are: vaccinations, acquired immunity, vector density and control, meteorological variations, wind pattern, and so on. Including more and more variables leads to a more process oriented model. A full process oriented approach simulates the movement of virus between vectors and host, describing...

  10. Ebolavirus is evolving but not changing: No evidence for functional change in EBOV from 1976 to the 2014 outbreak.

    Science.gov (United States)

    Olabode, Abayomi S; Jiang, Xiaowei; Robertson, David L; Lovell, Simon C

    2015-08-01

    The 2014 epidemic of Ebola virus disease (EVD) has had a devastating impact in West Africa. Sequencing of ebolavirus (EBOV) from infected individuals has revealed extensive genetic variation, leading to speculation that the virus may be adapting to humans, accounting for the scale of the 2014 outbreak. We computationally analyze the variation associated with all EVD outbreaks, and find none of the amino acid replacements lead to identifiable functional changes. These changes have minimal effect on protein structure, being neither stabilizing nor destabilizing, are not found in regions of the proteins associated with known functions and tend to cluster in poorly constrained regions of proteins, specifically intrinsically disordered regions. We find no evidence that the difference between the current and previous outbreaks is due to evolutionary changes associated with transmission to humans. Instead, epidemiological factors are likely to be responsible for the unprecedented spread of EVD. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  11. The role of risk perception in willingness to respond to the 2014-2016 West African Ebola outbreak

    DEFF Research Database (Denmark)

    Gee, Stephanie; Skovdal, Morten

    2017-01-01

    using NVivo 10. Results: We found that numerous individual and social-level factors played a role in modifying risk perception in health workers. Institutional trust emerged as a key risk attenuator, as did past experience, self-efficacy, duty of care, humanitarian ethos, and cognitive heuristics...... workers is essential for an effective epidemic response, health workforce capacity in times of crisis may be significantly impacted by how risks are perceived by health staff. This study aimed to explore how risk perceptions influenced healthcare workers’ willingness to respond during this outbreak....... Methods: Through in-depth interviews with 11 front-line international health care workers who chose to respond to the West Africa outbreak, this qualitative study explores how perceptions of risk developed and subsequently mediated the decision to respond to the outbreak. Data was thematically organized...

  12. Review. Systems for prevention and control of epidemic emergencies

    Directory of Open Access Journals (Sweden)

    Paolo Calistri

    2013-09-01

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

  13. Mutually cooperative epidemics on power-law networks

    Science.gov (United States)

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

    2017-08-01

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

  14. Constructing rigorous and broad biosurveillance networks for detecting emerging zoonotic outbreaks.

    Directory of Open Access Journals (Sweden)

    Mac Brown

    Full Text Available Determining optimal surveillance networks for an emerging pathogen is difficult since it is not known beforehand what the characteristics of a pathogen will be or where it will emerge. The resources for surveillance of infectious diseases in animals and wildlife are often limited and mathematical modeling can play a supporting role in examining a wide range of scenarios of pathogen spread. We demonstrate how a hierarchy of mathematical and statistical tools can be used in surveillance planning help guide successful surveillance and mitigation policies for a wide range of zoonotic pathogens. The model forecasts can help clarify the complexities of potential scenarios, and optimize biosurveillance programs for rapidly detecting infectious diseases. Using the highly pathogenic zoonotic H5N1 avian influenza 2006-2007 epidemic in Nigeria as an example, we determined the risk for infection for localized areas in an outbreak and designed biosurveillance stations that are effective for different pathogen strains and a range of possible outbreak locations. We created a general multi-scale, multi-host stochastic SEIR epidemiological network model, with both short and long-range movement, to simulate the spread of an infectious disease through Nigerian human, poultry, backyard duck, and wild bird populations. We chose parameter ranges specific to avian influenza (but not to a particular strain and used a Latin hypercube sample experimental design to investigate epidemic predictions in a thousand simulations. We ranked the risk of local regions by the number of times they became infected in the ensemble of simulations. These spatial statistics were then complied into a potential risk map of infection. Finally, we validated the results with a known outbreak, using spatial analysis of all the simulation runs to show the progression matched closely with the observed location of the farms infected in the 2006-2007 epidemic.

  15. Epidemic Risk from Cholera Introductions into Mexico

    OpenAIRE

    Moore, Sean M.; Shannon, Kerry L.; Zelaya, Carla E.; Azman, Andrew S.; Lessler, Justin

    2014-01-01

    Stemming from the 2010 cholera outbreak in Haiti, cholera transmission in Hispaniola continues with over 40,000 cases in 2013. The presence of an ongoing cholera outbreak in the region poses substantial risks to countries throughout the Americas, particularly in areas with poor infrastructure. Since September 9, 2013 nearly 200 cholera cases have been reported in Mexico, as a result of introductions from Hispaniola or Cuba. There appear to have been multiple introductions into Mexico resultin...

  16. Oncological emergencies for the internist

    Directory of Open Access Journals (Sweden)

    Umesh Das

    2015-01-01

    Full Text Available An oncologic emergency is defined as any acute, potentially life-threatening event, either directly or indirectly related to a patient′s cancer (ca or its treatment. It requires rapid intervention to avoid death or severe permanent damage. Most oncologic emergencies can be classified as metabolic, hematologic, structural, or side effects from chemotherapy agents. Tumor lysis syndrome is a metabolic emergency that presents as severe electrolyte abnormalities. The condition is treated with aggressive hydration, allopurinol or urate oxidase to lower uric acid levels. Hypercalcemia of malignancy is treated with aggressive rehydration, furosemide, and intravenous (IV bisphosphonates. Syndrome of inappropriate antidiuretic hormone should be suspected if a patient with ca presents with normovolemic hyponatremia. This metabolic condition usually is treated with fluid restriction and furosemide. Febrile neutropenia is a hematologic emergency that usually requires inpatient therapy with broad-spectrum antibiotics, although outpatient therapy may be appropriate for low-risk patients. Hyperviscosity syndrome usually is associated with Waldenstrφm′s macroglobulinemia, which is treated with plasmapheresis and chemotherapy. Structural oncologic emergencies are caused by direct compression of surrounding structures or by metastatic disease. Superior vena cava syndrome is the most common structural oncological emergency. Treatment options include chemotherapy, radiation, and IV stenting. Epidural spinal cord compression can be treated with dexamethasone, radiation, or surgery. Malignant pericardial effusion, which often is undiagnosed in ca patients, can be treated with pericardiocentesis or a pericardial window procedure.

  17. Cholera epidemic in Guinea-Bissau (2008): the importance of "place".

    Science.gov (United States)

    Luquero, Francisco J; Banga, Cunhate Na; Remartínez, Daniel; Palma, Pedro Pablo; Baron, Emanuel; Grais, Rebeca F

    2011-05-04

    As resources are limited when responding to cholera outbreaks, knowledge about where to orient interventions is crucial. We describe the cholera epidemic affecting Guinea-Bissau in 2008 focusing on the geographical spread in order to guide prevention and control activities. We conducted two studies: 1) a descriptive analysis of the cholera epidemic in Guinea-Bissau focusing on its geographical spread (country level and within the capital); and 2) a cross-sectional study to measure the prevalence of houses with at least one cholera case in the most affected neighbourhood of the capital (Bairro Bandim) to detect clustering of households with cases (cluster analysis). All cholera cases attending the cholera treatment centres in Guinea-Bissau who fulfilled a modified World Health Organization clinical case definition during the epidemic were included in the descriptive study. For the cluster analysis, a sample of houses was selected from a satellite photo (Google Earth™); 140 houses (and the four closest houses) were assessed from the 2,202 identified structures. We applied K-functions and Kernel smoothing to detect clustering. We confirmed the clustering using Kulldorff's spatial scan statistic. A total of 14,222 cases and 225 deaths were reported in the country (AR = 0.94%, CFR = 1.64%). The more affected regions were Biombo, Bijagos and Bissau (the capital). Bairro Bandim was the most affected neighborhood of the capital (AR = 4.0). We found at least one case in 22.7% of the houses (95%CI: 19.5-26.2) in this neighborhood. The cluster analysis identified two areas within Bairro Bandim at highest risk: a market and an intersection where runoff accumulates waste (p<0.001). Our analysis allowed for the identification of the most affected regions in Guinea-Bissau during the 2008 cholera outbreak, and the most affected areas within the capital. This information was essential for making decisions on where to reinforce treatment and to guide control and prevention

  18. Vibrio cholerae O1 epidemic variants in Angola: a retrospective study between 1992 and 2006.

    Directory of Open Access Journals (Sweden)

    Romy eValia

    2013-11-01

    Full Text Available Cholera is still a major public health concern in many African countries. In Angola, after a decade of absence, cholera reemerged in 1987, spreading throughout the country until 1996, with outbreaks recurring in a seasonal pattern. In 2006 Angola was hit by one of the most severe outbreaks of the last decade, with ca. 240,000 cases reported.We analyzed 21 clinical strains isolated between 1992 and 2006 from several provinces throughout the country: Benguela, Bengo, Luanda, Cuando Cubango and Cabinda. We used two multiplex PCR assays to investigate discriminatory mobile genetic elements (ICEs, VSP-II, GI12, GI14, GI15, K and TLC phages and we compared the profiles obtained with those of different reference V. cholerae O1 variants (prototypical, altered and hybrid, responsible for the ongoing 7th pandemic. We also tested the strains for the presence of specific VSP-II variants and for the presence of a genomic island (WASA-1, correlated with the transmission of seventh pandemic cholera from Africa to South America. Based on the presence/absence of the analyzed genetic elements, five novel profiles were detected in the epidemic strains circulating in the 1990s. The most frequent profiles, F and G, were characterized by the absence of ICEs and the three GIs tested, and the presence of genomic island WASA-1 and the WASA variant of the VSP-II island. Our results identified unexpected variability within the 1990s epidemic, showing different rearrangements in a dynamic part of the genome not present in the prototypical V. cholerae O1 N16961. Moreover the 2006 strains differed from the current pandemic V. cholerae O1 strain. Taken together, our results highlight the role of horizontal gene transfer in diversifying the genetic background of V. cholerae within a single epidemic.

  19. Vibrio cholerae O1 epidemic variants in Angola: a retrospective study between 1992 and 2006.

    Science.gov (United States)

    Valia, Romy; Taviani, Elisa; Spagnoletti, Matteo; Ceccarelli, Daniela; Cappuccinelli, Piero; Colombo, Mauro M

    2013-01-01

    Cholera is still a major public health concern in many African countries. In Angola, after a decade of absence, cholera reemerged in 1987, spreading throughout the country until 1996, with outbreaks recurring in a seasonal pattern. In 2006 Angola was hit by one of the most severe outbreaks of the last decade, with ca. 240,000 cases reported. We analyzed 21 clinical strains isolated between 1992 and 2006 from several provinces throughout the country: Benguela, Bengo, Luanda, Cuando Cubango, and Cabinda. We used two multiplex PCR assays to investigate discriminatory mobile genetic elements (MGE) [Integrative Conjugative Elements (ICEs), VSP-II, GI12, GI14, GI15, K, and TLC phages] and we compared the profiles obtained with those of different reference V. cholerae O1 variants (prototypical, altered, and hybrid), responsible for the ongoing 7th pandemic. We also tested the strains for the presence of specific VSP-II variants and for the presence of a genomic island (GI) (WASA-1), correlated with the transmission of seventh pandemic cholera from Africa to South America. Based on the presence/absence of the analyzed genetic elements, five novel profiles were detected in the epidemic strains circulating in the 1990s. The most frequent profiles, F and G, were characterized by the absence of ICEs and the three GIs tested, and the presence of GI WASA-1 and the WASA variant of the VSP-II island. Our results identified unexpected variability within the 1990s epidemic, showing different rearrangements in a dynamic part of the genome not present in the prototypical V. cholerae O1 N16961. Moreover the 2006 strains differed from the current pandemic V. cholerae O1 strain. Taken together, our results highlight the role of horizontal gene transfer (HGT) in diversifying the genetic background of V. cholerae within a single epidemic.

  20. Cholera epidemics, war and disasters around Goma and Lake Kivu: an eight-year survey.

    Directory of Open Access Journals (Sweden)

    Didier Bompangue

    Full Text Available BACKGROUND: During the last eight years, North and South Kivu, located in a lake area in Eastern Democratic Republic of Congo, have been the site of a major volcano eruption and of numerous complex emergencies with population displacements. These conditions have been suspected to favour emergence and spread of cholera epidemics. METHODOLOGY/PRINCIPAL FINDINGS: In order to assess the influence of these conditions on outbreaks, reports of cholera cases were collected weekly from each health district of North Kivu (4,667,699 inhabitants and South Kivu (4,670,121 inhabitants from 2000 through 2007. A geographic information system was established, and in each health district, the relationships between environmental variables and the number of cholera cases were assessed using regression techniques and time series analysis. We further checked for a link between complex emergencies and cholera outbreaks. Finally, we analysed data collected during an epidemiological survey that was implemented in Goma after Nyiragongo eruption. A total of 73,605 cases and 1,612 deaths of cholera were reported. Time series decomposition showed a greater number of cases during the rainy season in South Kivu but not in North Kivu. Spatial distribution of cholera cases exhibited a higher number of cases in health districts bordering lakes (Odds Ratio 7.0, Confidence Interval range 3.8-12.9. Four epidemic reactivations were observed in the 12-week periods following war events, but simulations indicate that the number of reactivations was not larger than that expected during any random selection of period with no war. Nyiragongo volcanic eruption was followed by a marked decrease of cholera incidence. CONCLUSION/SIGNIFICANCE: Our study points out the crucial role of some towns located in lakeside areas in the persistence of cholera in Kivu. Even if complex emergencies were not systematically followed by cholera epidemics, some of them enabled cholera spreading.

  1. Modeling the 2016-2017 Yemen Cholera Outbreak with the Impact of Limited Medical Resources.

    Science.gov (United States)

    He, Daihai; Wang, Xueying; Gao, Daozhou; Wang, Jin

    2018-05-01

    We present a mathematical model to investigate the transmission dynamics of the 2016-2017 Yemen Cholera Outbreak. Our model describes the interaction between the human hosts and the pathogenic bacteria, under the impact of limited medical resources. We fit our model to Yemen epidemic data published by the World Health Organization, at both the country and regional levels. We find that the Yemen cholera outbreak is shaped by the interplay of environmental, socioeconomic, and climatic factors. Our results suggest that improvement of the public health system and strategic implementation of control measures with respect to time and location are key to future cholera prevention and intervention in Yemen. Copyright © 2018. Published by Elsevier Ltd.

  2. Outbreak of avian influenza H7N3 on a turkey farm in the Netherlands.

    Science.gov (United States)

    Velkers, F C; Bouma, A; Matthijs, M G R; Koch, G; Westendorp, S T; Stegeman, J A

    2006-09-23

    This case report describes the course of an outbreak of avian influenza on a Dutch turkey farm. When clinical signs were observed their cause remained unclear. However, serum samples taken for the monitoring campaign launched during the epidemic of highly pathogenic avian influenza in 2003, showed that all the remaining turkeys were seropositive against an H7 strain of avian influenza virus, and the virus was subsequently isolated from stored carcases. The results of a reverse-transcriptase pcr showed that a H7N3 strain was involved, and it was characterised as of low pathogenicity. However, its intravenous pathogenicity index was 2.4, characterising it as of high pathogenicity, suggesting that a mixture of strains of low and high pathogenicity may have been present in the isolate. The outbreak remained limited to three farms.

  3. Data-driven outbreak forecasting with a simple nonlinear growth model.

    Science.gov (United States)

    Lega, Joceline; Brown, Heidi E

    2016-12-01

    Recent events have thrown the spotlight on infectious disease outbreak response. We developed a data-driven method, EpiGro, which can be applied to cumulative case reports to estimate the order of magnitude of the duration, peak and ultimate size of an ongoing outbreak. It is based on a surprisingly simple mathematical property of many epidemiological data sets, does not require knowledge or estimation of disease transmission parameters, is robust to noise and to small data sets, and runs quickly due to its mathematical simplicity. Using data from historic and ongoing epidemics, we present the model. We also provide modeling considerations that justify this approach and discuss its limitations. In the absence of other information or in conjunction with other models, EpiGro may be useful to public health responders. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  4. An Explosive Cholera Outbreak In A Rural Community of Gujarat State

    Directory of Open Access Journals (Sweden)

    Sengupta P.G

    1994-01-01

    Full Text Available Research Question : What are the epidemiological features of an el Tor biotype of V. cholerae outbreak? Objective : To describe the epidemiological features of a cholera outbreak. Design: Epidemic investigation. Setting : Rural area near Baroda city. Participants : Residents of the village hamlet. Results : The overall attack rate among 248 people was 13.3% and was highest (26.9% in the 0-4 years age group. All the patients, except one who died at home, had to be hospitalized for treatment . V. Cholerae biotype el Tor serotype Inaba and phage type IV could be isolated from 62.5% of the cases. Some pathogens could be isolated in pure culture from the open well water which was the only source of drinking water for the hamlet.

  5. Effects of a Severe Mountain Pine Beetle Epidemic in Western Alberta, Canada under Two Forest Management Scenarios

    Directory of Open Access Journals (Sweden)

    Richard R. Schneider

    2010-01-01

    Full Text Available We used a simulation model to investigate possible effects of a severe mountain pine beetle (Dendroctonus ponderosae Hopkins epidemic under two management scenarios in Alberta, Canada. Our simulated outbreak was based on the current epidemic in British Columbia, which may kill close to 80% of the province's pine volume. Our two management scenarios were conventional harvest and a pine-reduction strategy modeled on a component of Alberta's Mountain Pine Beetle Management Strategy. The pine strategy seeks to reduce the number of susceptible pine stands by 75% over the next 20 years through targeted harvesting by the forest industry. Our simulations showed that the pine strategy could not be effectively implemented, even if the onset of the beetle outbreak was delayed for 20 years. Even though we increased mill capacity by 20% and directed all harvesting to high volume pine stands during the pine strategy's surge cut, the amount of highly susceptible pine was reduced by only 43%. Additional pine volume remained within mixed stands that were not targeted by the pine strategy. When the outbreak occurred in each scenario, sufficient pine remained on the landscape for the beetle to cause the timber supply to collapse. Alternative management approaches and avenues for future research are discussed.

  6. Semiquantitative Decision Tools for FMD Emergency Vaccination Informed by Field Observations and Simulated Outbreak Data

    DEFF Research Database (Denmark)

    Willeberg, Preben; AlKhamis, Mohammad; Boklund, Anette

    2017-01-01

    We present two simple, semiquantitative model-based decision tools, based on the principle of first 14 days incidence (FFI). The aim is to estimate the likelihood and the consequences, respectively, of the ultimate size of an ongoing FMD epidemic. The tools allow risk assessors to communicate...... and optimize the presentation of the resulting data for urgent decisions to be made by the risk managers, we estimated the sensitivity, specificity, as well as the negative and positive predictive values, using a chosen day-14 outbreak number as predictor of the magnitude of the number of remaining post-day-14...

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

    Science.gov (United States)

    Poletto, Chiara; Tizzoni, Michele; Colizza, Vittoria

    2013-12-07

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

  8. Predicting the evolution of large cholera outbreaks: lessons learnt from the Haiti case study

    Science.gov (United States)

    Bertuzzo, Enrico; Mari, Lorenzo; Righetto, Lorenzo; Knox, Allyn; Finger, Flavio; Casagrandi, Renato; Gatto, Marino; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2013-04-01

    Mathematical models can provide key insights into the course of an ongoing epidemic, potentially aiding real-time emergency management in allocating health care resources and possibly anticipating the impact of alternative interventions. Spatially explicit models of waterborne disease are made routinely possible by widespread data mapping of hydrology, road network, population distribution, and sanitation. Here, we study the ex-post reliability of predictions of the ongoing Haiti cholera outbreak. Our model consists of a set of dynamical equations (SIR-like, i.e. subdivided into the compartments of Susceptible, Infected and Recovered individuals) describing a connected network of human communities where the infection results from the exposure to excess concentrations of pathogens in the water, which are, in turn, driven by hydrologic transport through waterways and by mobility of susceptible and infected individuals. Following the evidence of a clear correlation between rainfall events and cholera resurgence, we test a new mechanism explicitly accounting for rainfall as a driver of enhanced disease transmission by washout of open-air defecation sites or cesspool overflows. A general model for Haitian epidemic cholera and the related uncertainty is thus proposed and applied to the dataset of reported cases now available. The model allows us to draw predictions on longer-term epidemic cholera in Haiti from multi-season Monte Carlo runs, carried out up to January 2014 by using a multivariate Poisson rainfall generator, with parameters varying in space and time. Lessons learned and open issues are discussed and placed in perspective. We conclude that, despite differences in methods that can be tested through model-guided field validation, mathematical modeling of large-scale outbreaks emerges as an essential component of future cholera epidemic control.

  9. 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.

  10. An online spatiotemporal prediction model for dengue fever epidemic in Kaohsiung (Taiwan).

    Science.gov (United States)

    Yu, Hwa-Lung; Angulo, José M; Cheng, Ming-Hung; Wu, Jiaping; Christakos, George

    2014-05-01

    The emergence and re-emergence of disease epidemics is a complex question that may be influenced by diverse factors, including the space-time dynamics of human populations, environmental conditions, and associated uncertainties. This study proposes a stochastic framework to integrate space-time dynamics in the form of a Susceptible-Infected-Recovered (SIR) model, together with uncertain disease observations, into a Bayesian maximum entropy (BME) framework. The resulting model (BME-SIR) can be used to predict space-time disease spread. Specifically, it was applied to obtain a space-time prediction of the dengue fever (DF) epidemic that took place in Kaohsiung City (Taiwan) during 2002. In implementing the model, the SIR parameters were continually updated and information on new cases of infection was incorporated. The results obtained show that the proposed model is rigorous to user-specified initial values of unknown model parameters, that is, transmission and recovery rates. In general, this model provides a good characterization of the spatial diffusion of the DF epidemic, especially in the city districts proximal to the location of the outbreak. Prediction performance may be affected by various factors, such as virus serotypes and human intervention, which can change the space-time dynamics of disease diffusion. The proposed BME-SIR disease prediction model can provide government agencies with a valuable reference for the timely identification, control, and prevention of DF spread in space and time. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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.

  12. Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology.

    Science.gov (United States)

    Jepsen, Jane U; Hagen, Snorre B; Karlsen, Stein-Rune; Ims, Rolf A

    2009-12-07

    Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000-2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.

  13. Dengue disease outbreak definitions are implicitly variable

    Directory of Open Access Journals (Sweden)

    Oliver J. Brady

    2015-06-01

    Full Text Available Infectious diseases rarely exhibit simple dynamics. Outbreaks (defined as excess cases beyond response capabilities have the potential to cause a disproportionately high burden due to overwhelming health care systems. The recommendations of international policy guidelines and research agendas are based on a perceived standardised definition of an outbreak characterised by a prolonged, high-caseload, extra-seasonal surge. In this analysis we apply multiple candidate outbreak definitions to reported dengue case data from Brazil to test this assumption. The methods identify highly heterogeneous outbreak characteristics in terms of frequency, duration and case burden. All definitions identify outbreaks with characteristics that vary over time and space. Further, definitions differ in their timeliness of outbreak onset, and thus may be more or less suitable for early intervention. This raises concerns about the application of current outbreak guidelines for early warning/identification systems. It is clear that quantitatively defining the characteristics of an outbreak is an essential prerequisite for effective reactive response. More work is needed so that definitions of disease outbreaks can take into account the baseline capacities of treatment, surveillance and control. This is essential if outbreak guidelines are to be effective and generalisable across a range of epidemiologically different settings.

  14. 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

  15. [The EHEC O104:H4 outbreak in Germany 2011 - lessons learned?!].

    Science.gov (United States)

    Rissland, J; Kielstein, J T; Stark, K; Wichmann-Schauer, H; Stümpel, F; Pulz, M

    2013-04-01

    The EHEC O104:H4 outbreak 2011 in Germany provided numerous insights into the recognition and control of such epidemic situations. Food-borne outbreaks and their related dynamics may lead to a critical burden of disease and an eventual capacity overload of the medical care system. Possible difficulties in the microbiological diagnostics of new or significantly altered infectious agents may result in a delayed detection of the outbreak as well as the launching of interventional measures. Besides an early notification of the local public health office by the affected institutions, in which a complete electronic procedure and additional sentinel or surveillance instruments (e. g., in emergency departments of hospitals) may be of great help, an interdisciplinary cooperation of the local public health and food safety agencies is the key to an effective outbreak control. Corresponding organizations on the state and federal level should support the investigation process by microbiological diagnostics and advanced epidemiological analysis as well as examination of the food chains. Finally, successful crisis communication relies on "speaking with one voice" (not necessarily one person). Immediate, transparent, appropriate and honest information of the general public concerning the reasons, consequences and (counter-) measures of a crisis are the best means to keep the trust of the population and to counteract the otherwise inevitable speculations. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Development of artificial intelligence approach to forecasting oyster norovirus outbreaks along Gulf of Mexico coast.

    Science.gov (United States)

    Chenar, Shima Shamkhali; Deng, Zhiqiang

    2018-02-01

    This paper presents an artificial intelligence-based model, called ANN-2Day model, for forecasting, managing and ultimately eliminating the growing risk of oyster norovirus outbreaks. The ANN-2Day model was developed using Artificial Neural Network (ANN) Toolbox in MATLAB Program and 15-years of epidemiological and environmental data for six independent environmental predictors including water temperature, solar radiation, gage height, salinity, wind, and rainfall. It was found that oyster norovirus outbreaks can be forecasted with two-day lead time using the ANN-2Day model and daily data of the six environmental predictors. Forecasting results of the ANN-2Day model indicated that the model was capable of reproducing 19years of historical oyster norovirus outbreaks along the Northern Gulf of Mexico coast with the positive predictive value of 76.82%, the negative predictive value of 100.00%, the sensitivity of 100.00%, the specificity of 99.84%, and the overall accuracy of 99.83%, respectively, demonstrating the efficacy of the ANN-2Day model in predicting the risk of norovirus outbreaks to human health. The 2-day lead time enables public health agencies and oyster harvesters to plan for management interventions and thus makes it possible to achieve a paradigm shift of their daily management and operation from primarily reacting to epidemic incidents of norovirus infection after they have occurred to eliminating (or at least reducing) the risk of costly incidents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Epidemiological and Ecological Characterization of the EHEC O104:H4 Outbreak in Hamburg, Germany, 2011.

    Directory of Open Access Journals (Sweden)

    Maike Tahden

    Full Text Available In 2011, a large outbreak of entero-hemorrhagic E. coli (EHEC and hemolytic uremic syndrome (HUS occurred in Germany. The City of Hamburg was the first focus of the epidemic and had the highest incidences among all 16 Federal States of Germany. In this article, we present epidemiological characteristics of the Hamburg notification data. Evaluating the epicurves retrospectively, we found that the first epidemiological signal of the outbreak, which was in form of a HUS case cluster, was received by local health authorities when already 99 EHEC and 48 HUS patients had experienced their first symptoms. However, only two EHEC and seven HUS patients had been notified. Middle-aged women had the highest risk for contracting the infection in Hamburg. Furthermore, we studied timeliness of case notification in the course of the outbreak. To analyze the spatial distribution of EHEC/HUS incidences in 100 districts of Hamburg, we mapped cases' residential addresses using geographic information software. We then conducted an ecological study in order to find a statistical model identifying associations between local socio-economic factors and EHEC/HUS incidences in the epidemic. We employed a Bayesian Poisson model with covariates characterizing the Hamburg districts as well as incorporating structured and unstructured spatial effects. The Deviance Information Criterion was used for stepwise variable selection. We applied different modeling approaches by using primary data, transformed data, and preselected subsets of transformed data in order to identify socio-economic factors characterizing districts where EHEC/HUS outbreak cases had their residence.

  18. Staphylococcus aureus epidemic in a neonatal nursery: a strategy of infection control.

    Science.gov (United States)

    Bertini, Giovanna; Nicoletti, PierLuigi; Scopetti, Franca; Manoocher, Pourshaban; Dani, Carlo; Orefici, Graziella

    2006-08-01

    The risk of nosocomial infection due to Staphylococcus aureus in fullterm newborns is higher under hospital conditions where there are overcrowded nurseries and inadequate infection control techniques. We report on an outbreak of skin infection in a Maternity Nursery (May 21, 2000) and the measures undertaken to bring the epidemic under control. These measures included: separating neonates already present in the nursery on August 23, 2000 from ones newly arriving by creating two different cohorts, one of neonates born before this date and one of neonates born later; restricting healthcare workers caring for S. aureus- infected infants from working with non-infected infants; disallowing carrier healthcare workers from caring for patients; introducing contact and droplet precautions (including the routine use of gowns, gloves, and mask); ensuring appropriate disinfection of potential sources of contamination. A representative number of isolates were typed by genomic DNA restriction length polymorphism analysis by means of pulsed-field gel electrophoresis (PFGE). Among the 227 cases of skin lesions, microbiological laboratory analyses confirmed that 175 were staphylococcal infections. The outbreak showed a gradual reduction in magnitude when the overcrowding of the Nursery was reduced by separating the newborns into the two different Nurseries (two cohorts). The genotyping of the strains by PFGE confirmed the nurse-to-newborn transmission of S. aureus. The measures adopted for controlling the S. aureus outbreak can, in retrospect, be assessed to have been very effective.

  19. Inter-epidemic transmission of Rift Valley fever in livestock in the Kilombero River Valley, Tanzania: a cross-sectional survey.

    Directory of Open Access Journals (Sweden)

    Robert D Sumaye

    Full Text Available BACKGROUND: In recent years, evidence of Rift Valley fever (RVF transmission during inter-epidemic periods in parts of Africa has increasingly been reported. The inter-epidemic transmissions generally pass undetected where there is no surveillance in the livestock or human populations. We studied the presence of and the determinants for inter-epidemic RVF transmission in an area experiencing annual flooding in southern Tanzania. METHODOLOGY: A cross-sectional sero-survey was conducted in randomly selected cattle, sheep and goats in the Kilombero river valley from May to August 2011, approximately four years after the 2006/07 RVF outbreak in Tanzania. The exposure status to RVF virus (RVFV was determined using two commercial ELISA kits, detecting IgM and IgG antibodies in serum. Information about determinants was obtained through structured interviews with herd owners. FINDINGS: An overall seroprevalence of 11.3% (n = 1680 was recorded; 5.5% in animals born after the 2006/07 RVF outbreak and 22.7% in animals present during the outbreak. There was a linear increase in prevalence in the post-epidemic annual cohorts. Nine inhibition-ELISA positive samples were also positive for RVFV IgM antibodies indicating a recent infection. The spatial distribution of seroprevalence exhibited a few hotspots. The sex difference in seroprevalence in animals born after the previous epidemic was not significant (6.1% vs. 4.6% for females and males respectively, p = 0.158 whereas it was significant in animals present during the outbreak (26.0% vs. 7.8% for females and males respectively, p15 km from the flood plain were more likely to have antibodies than those living <5 km (OR 1.92; 95% CI 1.04-3.56. Species, breed, herd composition, grazing practices and altitude were not associated with seropositivity. CONCLUSION: These findings indicate post-epidemic transmission of RVFV in the study area. The linear increase in seroprevalence in the post-epidemic annual cohorts

  20. 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