The Experts below are selected from a list of 11151 Experts worldwide ranked by ideXlab platform

Gerardo Chowell - One of the best experts on this subject based on the ideXlab platform.

  • spatial variability in the reproduction number of Ebola Virus Disease democratic republic of the congo january september 2019
    Eurosurveillance, 2019
    Co-Authors: Gerardo Chowell, Kenji Mizumoto, Amna Tariq, Kimberlyn Roosa, Jun Kong, Ping Yan
    Abstract:

    The ongoing Ebola Virus Disease epidemic (August 2018─October 2019) in the Democratic Republic of the Congo, has been exacerbated by deliberate attacks on healthcare workers despite vaccination efforts. Using a mathematical/statistical modelling framework, we present the quantified effective reproduction number (Rt) at national and regional levels as at 29 September. The weekly trend in Rt displays fluctuations while our recent national-level Rt falls slightly above 1.0 with substantial uncertainty, which suggests improvements in epidemic control.

  • theoretical perspectives on the infectiousness of Ebola Virus Disease
    Theoretical Biology and Medical Modelling, 2015
    Co-Authors: Hiroshi Nishiura, Gerardo Chowell
    Abstract:

    Background: Ebola Virus Disease (EVD) has generated a large epidemic in West Africa since December 2013. This mini-review is aimed to clarify and illustrate different theoretical concepts of infectiousness in order to compare the infectiousness across different communicable Diseases including EVD. Methods: We employed a transmission model that rests on the renewal process in order to clarify theoretical concepts on infectiousness, namely the basic reproduction number, R0, which measures the infectiousness per generation of cases, the force of infection (i.e. the hazard rate of infection), the intrinsic growth rate (i.e. infectiousness per unit time) and the per-contact probability of infection (i.e. infectiousness per effective contact). Results: Whereas R0 of EVD is similar to that of influenza, the growth rate (i.e. the measure of infectiousness per unit time) for EVD was shown to be comparatively lower than that for influenza. Moreover, EVD and influenza differ in mode of transmission whereby the probability of transmission per contact is lower for EVD compared to that of influenza. Conclusions: The slow spread of EVD associated with the need for physical contact with body fluids supports social distancing measures including contact tracing and case isolation. Descriptions and interpretations of different variables quantifying infectiousness need to be used clearly and objectively in the scientific community and for risk communication.

  • the western africa Ebola Virus Disease epidemic exhibits both global exponential and local polynomial growth rates
    arXiv: Populations and Evolution, 2014
    Co-Authors: Gerardo Chowell, Cecile Viboud, James M Hyman, Lone Simonsen
    Abstract:

    Background: 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. Methods: 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. Results: 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. Conclusions: 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.

  • transmission dynamics and control of Ebola Virus Disease evd a review
    BMC Medicine, 2014
    Co-Authors: Gerardo Chowell, Hiroshi Nishiura
    Abstract:

    The complex and unprecedented Ebola epidemic ongoing in West Africa has highlighted the need to review the epidemiological characteristics of Ebola Virus Disease (EVD) as well as our current understanding of the transmission dynamics and the effect of control interventions against Ebola transmission. Here we review key epidemiological data from past Ebola outbreaks and carry out a comparative review of mathematical models of the spread and control of Ebola in the context of past outbreaks and the ongoing epidemic in West Africa. We show that mathematical modeling offers useful insights into the risk of a major epidemic of EVD and the assessment of the impact of basic public health measures on Disease spread. We also discuss the critical need to collect detailed epidemiological data in real-time during the course of an ongoing epidemic, carry out further studies to estimate the effectiveness of interventions during past outbreaks and the ongoing epidemic, and develop large-scale modeling studies to study the spread and control of viral hemorrhagic fevers in the context of the highly heterogeneous economic reality of African countries.

  • early transmission dynamics of Ebola Virus Disease evd west africa march to august 2014
    Eurosurveillance, 2014
    Co-Authors: Hiroshi Nishiura, Gerardo Chowell
    Abstract:

    The effective reproduction number, Rt, of Ebola Virus Disease was estimated using country-specific data reported from Guinea, Liberia and Sierra Leone to the World Health Organization from March to August, 2014. Rt for the three countries lies consistently above 1.0 since June 2014. Country-specific Rt for Liberia and Sierra Leone have lied between 1.0 and 2.0. Rt<2 indicate that control could be attained by preventing over half of the secondary transmissions per primary case.

Alicia Rosello - One of the best experts on this subject based on the ideXlab platform.

  • Ebola Virus Disease in the democratic republic of the congo 1976 2014
    eLife, 2015
    Co-Authors: Placide Mbala, Alicia Rosello, Mathias Mossoko, Stefan Flasche, Albert Jan Van Hoek, Anton Camacho, Sebastian Funk, Adam J Kucharski, Benoit Kebela Ilunga
    Abstract:

    The Democratic Republic of the Congo has experienced the most outbreaks of Ebola Virus Disease since the Virus' discovery in 1976. This article provides for the first time a description and a line list for all outbreaks in this country, comprising 996 cases. Compared to patients over 15 years old, the odds of dying were significantly lower in patients aged 5 to 15 and higher in children under five (with 100% mortality in those under 2 years old). The odds of dying increased by 11% per day that a patient was not hospitalised. Outbreaks with an initially high reproduction number, R (>3), were rapidly brought under control, whilst outbreaks with a lower initial R caused longer and generally larger outbreaks. These findings can inform the choice of target age groups for interventions and highlight the importance of both reducing the delay between symptom onset and hospitalisation and rapid national and international response.

  • Ebola Virus Disease in the democratic republic of the congo 1976 2014
    eLife, 2015
    Co-Authors: Placide Mbala, Alicia Rosello, Mathias Mossoko, Stefan Flasche, Anton Camacho, Sebastian Funk, Adam J Kucharski, Albert Jan Van Hoek, Benoit Kebela Ilunga
    Abstract:

    Ebola Virus Disease commonly causes symptoms such as high fever, vomiting, and diarrhoea. It may also cause muscle pain, headaches, and bleeding, and often leads to death. There have been seven outbreaks of Ebola Virus Disease in the Democratic Republic of the Congo (DRC) since 1976. The DRC is the country that has had the most outbreaks of this Disease in the world. The most recent outbreak in the DRC was in 2014; this was separate from the outbreak that started in West Africa in the same year. Rosello, Mossoko et al. have now compiled the data from all seven of the outbreaks in the DRC into a single dataset, which covers almost 1000 patients. Analysing this data revealed that people between 25 and 64 years of age were most likely to be infected by the Ebola Virus, possibly because most healthcare workers fall into this category. Age also affected how likely a patient was to die, with those aged under 5 and over 15 more likely to die than those aged between 5 and 15. Delaying going to hospital once symptoms had started, even by one day, also increased the likelihood of death. Rosello, Mossoko et al. also examined the Ebola Virus effective reproduction number, which indicates how many people, on average, an infected person passes the Virus on to. Outbreaks that initially featured Viruses with a reproduction number larger than three tended to be stemmed quickly. However, when the reproduction number was lower, national and international organisations were slower to respond to the signs of the outbreak, leading to outbreaks that lasted longer. Further research is needed to understand why the likelihood of death is different for different age groups and to investigate the effect of the different routes of transmission of the Virus on interventions such as vaccination.

Benoit Kebela Ilunga - One of the best experts on this subject based on the ideXlab platform.

  • Ebola Virus Disease in the democratic republic of the congo 1976 2014
    eLife, 2015
    Co-Authors: Placide Mbala, Alicia Rosello, Mathias Mossoko, Stefan Flasche, Anton Camacho, Sebastian Funk, Adam J Kucharski, Albert Jan Van Hoek, Benoit Kebela Ilunga
    Abstract:

    Ebola Virus Disease commonly causes symptoms such as high fever, vomiting, and diarrhoea. It may also cause muscle pain, headaches, and bleeding, and often leads to death. There have been seven outbreaks of Ebola Virus Disease in the Democratic Republic of the Congo (DRC) since 1976. The DRC is the country that has had the most outbreaks of this Disease in the world. The most recent outbreak in the DRC was in 2014; this was separate from the outbreak that started in West Africa in the same year. Rosello, Mossoko et al. have now compiled the data from all seven of the outbreaks in the DRC into a single dataset, which covers almost 1000 patients. Analysing this data revealed that people between 25 and 64 years of age were most likely to be infected by the Ebola Virus, possibly because most healthcare workers fall into this category. Age also affected how likely a patient was to die, with those aged under 5 and over 15 more likely to die than those aged between 5 and 15. Delaying going to hospital once symptoms had started, even by one day, also increased the likelihood of death. Rosello, Mossoko et al. also examined the Ebola Virus effective reproduction number, which indicates how many people, on average, an infected person passes the Virus on to. Outbreaks that initially featured Viruses with a reproduction number larger than three tended to be stemmed quickly. However, when the reproduction number was lower, national and international organisations were slower to respond to the signs of the outbreak, leading to outbreaks that lasted longer. Further research is needed to understand why the likelihood of death is different for different age groups and to investigate the effect of the different routes of transmission of the Virus on interventions such as vaccination.

  • Ebola Virus Disease in the democratic republic of the congo 1976 2014
    eLife, 2015
    Co-Authors: Placide Mbala, Alicia Rosello, Mathias Mossoko, Stefan Flasche, Albert Jan Van Hoek, Anton Camacho, Sebastian Funk, Adam J Kucharski, Benoit Kebela Ilunga
    Abstract:

    The Democratic Republic of the Congo has experienced the most outbreaks of Ebola Virus Disease since the Virus' discovery in 1976. This article provides for the first time a description and a line list for all outbreaks in this country, comprising 996 cases. Compared to patients over 15 years old, the odds of dying were significantly lower in patients aged 5 to 15 and higher in children under five (with 100% mortality in those under 2 years old). The odds of dying increased by 11% per day that a patient was not hospitalised. Outbreaks with an initially high reproduction number, R (>3), were rapidly brought under control, whilst outbreaks with a lower initial R caused longer and generally larger outbreaks. These findings can inform the choice of target age groups for interventions and highlight the importance of both reducing the delay between symptom onset and hospitalisation and rapid national and international response.

  • Ebola Virus Disease in the democratic republic of congo
    The New England Journal of Medicine, 2014
    Co-Authors: Gael Darren Maganga, Jimmy Kapetshi, Benoit Kebela Ilunga, Felix Kabange, Placide Mbala Kingebeni, Vital Mondonge, Eric Bertherat, Jean Jacques Muyembe, Nicolas Berthet, Sylvie Briand
    Abstract:

    Background The seventh reported outbreak of Ebola Virus Disease (EVD) in the equatorial African country of the Democratic Republic of Congo (DRC) began on July 26, 2014, as another large EVD epidemic continued to spread in West Africa. Simultaneous reports of EVD in equatorial and West Africa raised the question of whether the two outbreaks were linked. Methods We obtained data from patients in the DRC, using the standard World Health Organization clinical-investigation form for viral hemorrhagic fevers. Patients were classified as having suspected, probable, or confirmed EVD or a non-EVD illness. Blood samples were obtained for polymerase-chain-reaction–based diagnosis, viral isolation, sequencing, and phylogenetic analysis. Results

Hiroshi Nishiura - One of the best experts on this subject based on the ideXlab platform.

  • recrudescence of Ebola Virus Disease outbreak in west africa 2014 2016
    International Journal of Infectious Diseases, 2017
    Co-Authors: Hyojung Lee, Hiroshi Nishiura
    Abstract:

    Abstract Objectives There have been errors in determining the end of the Ebola Virus Disease (EVD) epidemic when adhering to the criteria of the World Health Organization. The present study aimed to review and learn from all known recrudescence events in West Africa occurring in 2014–2016. Methods Background mechanisms of five erroneous declarations in Guinea, Liberia, and Sierra Leone during 2014–2016 were reviewed. Results Three cases of recrudescence were suspected to have been caused by sexual contact with survivors, one to be due to international migration, and one was linked to a potentially immunocompromised mother. The three sexual transmission events involving survivors—the first two in Liberia and one in Sierra Leone—required 164 days, >150 days, and approximately 180 days, respectively, from discharge of the survivors to confirmation of the recrudescent case. Conclusions The events of recrudescence were associated with relatively uncommon routes of transmission other than close contact during burial or care-giving, including sexual transmission, possible immunocompromise, and migration. Recognition of the sexual transmission risk among survivors could potentially involve discrimination, which may lead to under-ascertainment.

  • theoretical perspectives on the infectiousness of Ebola Virus Disease
    Theoretical Biology and Medical Modelling, 2015
    Co-Authors: Hiroshi Nishiura, Gerardo Chowell
    Abstract:

    Background: Ebola Virus Disease (EVD) has generated a large epidemic in West Africa since December 2013. This mini-review is aimed to clarify and illustrate different theoretical concepts of infectiousness in order to compare the infectiousness across different communicable Diseases including EVD. Methods: We employed a transmission model that rests on the renewal process in order to clarify theoretical concepts on infectiousness, namely the basic reproduction number, R0, which measures the infectiousness per generation of cases, the force of infection (i.e. the hazard rate of infection), the intrinsic growth rate (i.e. infectiousness per unit time) and the per-contact probability of infection (i.e. infectiousness per effective contact). Results: Whereas R0 of EVD is similar to that of influenza, the growth rate (i.e. the measure of infectiousness per unit time) for EVD was shown to be comparatively lower than that for influenza. Moreover, EVD and influenza differ in mode of transmission whereby the probability of transmission per contact is lower for EVD compared to that of influenza. Conclusions: The slow spread of EVD associated with the need for physical contact with body fluids supports social distancing measures including contact tracing and case isolation. Descriptions and interpretations of different variables quantifying infectiousness need to be used clearly and objectively in the scientific community and for risk communication.

  • transmission dynamics and control of Ebola Virus Disease evd a review
    BMC Medicine, 2014
    Co-Authors: Gerardo Chowell, Hiroshi Nishiura
    Abstract:

    The complex and unprecedented Ebola epidemic ongoing in West Africa has highlighted the need to review the epidemiological characteristics of Ebola Virus Disease (EVD) as well as our current understanding of the transmission dynamics and the effect of control interventions against Ebola transmission. Here we review key epidemiological data from past Ebola outbreaks and carry out a comparative review of mathematical models of the spread and control of Ebola in the context of past outbreaks and the ongoing epidemic in West Africa. We show that mathematical modeling offers useful insights into the risk of a major epidemic of EVD and the assessment of the impact of basic public health measures on Disease spread. We also discuss the critical need to collect detailed epidemiological data in real-time during the course of an ongoing epidemic, carry out further studies to estimate the effectiveness of interventions during past outbreaks and the ongoing epidemic, and develop large-scale modeling studies to study the spread and control of viral hemorrhagic fevers in the context of the highly heterogeneous economic reality of African countries.

  • early transmission dynamics of Ebola Virus Disease evd west africa march to august 2014
    Eurosurveillance, 2014
    Co-Authors: Hiroshi Nishiura, Gerardo Chowell
    Abstract:

    The effective reproduction number, Rt, of Ebola Virus Disease was estimated using country-specific data reported from Guinea, Liberia and Sierra Leone to the World Health Organization from March to August, 2014. Rt for the three countries lies consistently above 1.0 since June 2014. Country-specific Rt for Liberia and Sierra Leone have lied between 1.0 and 2.0. Rt<2 indicate that control could be attained by preventing over half of the secondary transmissions per primary case.

Tom E Fletcher - One of the best experts on this subject based on the ideXlab platform.

  • diagnosis of febrile illnesses other than Ebola Virus Disease at an Ebola treatment unit in sierra leone
    Clinical Infectious Diseases, 2015
    Co-Authors: Matthew K Oshea, Mark S Bailey, Tom E Fletcher, Kate A Clay, Darren G Craig, Steven W Matthews, Emma Hutley
    Abstract:

    Patients with febrile illnesses presenting to an Ebola treatment unit in Sierra Leone had a wide range of diagnoses other than Ebola Virus Disease. Rapid diagnostic tests were useful in confirming these diagnoses, reducing the length of patient stay with valuable consequences. These alternative diagnoses should assist in future planning.

  • safety and feasibility of a strategy of early central venous catheter insertion in a deployed uk military Ebola Virus Disease treatment unit
    Intensive Care Medicine, 2015
    Co-Authors: Paul Rees, Lucy Lamb, T C Nicholsonroberts, C Ardley, Mark S Bailey, David Hinsley, Tom E Fletcher, Stuart Dickson
    Abstract:

    Purpose Early central venous catheter (CVC) insertion in Ebola Virus Disease (EVD) is a novel approach and has not previously been described. This report delineates the safety, feasibility and clinical implications of early CVC insertion as the optimum means of vascular access in patients with EVD, in the setting of a deployed military Ebola Virus Disease treatment unit in Sierra Leone.

  • clinical presentation of patients with Ebola Virus Disease in conakry guinea
    The New England Journal of Medicine, 2015
    Co-Authors: Elhadj Ibrahima Bah, William A. Fischer, Tom E Fletcher, Francois Lamontagne, Shevin T Jacob, David M Brettmajor, Marie Claire Lamah, Amadou A Sall, Nahoko Shindo, Sow Mamadou Saliou
    Abstract:

    BackgroundIn March 2014, the World Health Organization was notified of an outbreak of Zaire EbolaVirus in a remote area of Guinea. The outbreak then spread to the capital, Conakry, and to neighboring countries and has subsequently become the largest epidemic of Ebola Virus Disease (EVD) to date. MethodsFrom March 25 to April 26, 2014, we performed a study of all patients with laboratory-confirmed EVD in Conakry. Mortality was the primary outcome. Secondary outcomes included patient characteristics, complications, treatments, and comparisons between survivors and nonsurvivors. ResultsOf 80 patients who presented with symptoms, 37 had laboratory-confirmed EVD. Among confirmed cases, the median age was 38 years (interquartile range, 28 to 46), 24 patients (65%) were men, and 14 (38%) were health care workers; among the health care workers, nosocomial transmission was implicated in 12 patients (32%). Patients with confirmed EVD presented to the hospital a median of 5 days (interquartile range, 3 to 7) after t...

  • caring for critically ill patients with Ebola Virus Disease perspectives from west africa
    American Journal of Respiratory and Critical Care Medicine, 2014
    Co-Authors: Robert A. Fowler, William A. Fischer, Tom E Fletcher, Francois Lamontagne, Shevin T Jacob, David M Brettmajor, James V Lawler, Frederique A Jacquerioz, Catherine F Houlihan, Tim Odempsey
    Abstract:

    The largest ever Ebola Virus Disease outbreak is ravaging West Africa. The constellation of little public health infrastructure, low levels of health literacy, limited acute care and infection prevention and control resources, densely populated areas, and a highly transmissible and lethal viral infection have led to thousands of confirmed, probable, or suspected cases thus far. Ebola Virus Disease is characterized by a febrile severe illness with profound gastrointestinal manifestations and is complicated by intravascular volume depletion, shock, profound electrolyte abnormalities, and organ dysfunction. Despite no proven Ebola Virus-specific medical therapies, the potential effect of supportive care is great for a condition with high baseline mortality and one usually occurring in resource-constrained settings. With more personnel, basic monitoring, and supportive treatment, many of the sickest patients with Ebola Virus Disease do not need to die. Ebola Virus Disease represents an illness ready for a paradigm shift in care delivery and outcomes, and the profession of critical care medicine can and should be instrumental in helping this happen.