scholarly journals Investigating the potential benefit that requiring travellers to self-isolate on arrival may have upon the reducing of case importations during international outbreaks of influenza, SARS, Ebola virus disease and COVID-19

2020 ◽  
Author(s):  
Declan Bays ◽  
Emma Bennett ◽  
Thomas Finnie
Keyword(s):  
Potential Benefit ◽  
Detection Rate ◽  
Ebola Virus ◽  
Virus Disease ◽  
International Travel ◽  
Ebola Virus Disease ◽  
Detection Rates ◽  
Potential Effectiveness

AbstractWith the advent of rapid international travel, disease can now spread between nations faster than ever. As such, when outbreaks occur in foreign states, pressure mounts to reduce the risk of importing cases to the home nation. In a previous paper, we developed a model to investigate the potential effectiveness of deploying screening at airports during outbreaks of influenza, SARS, and Ebola. We also applied the model to the current COVID-19 outbreak. This model simulated the testing of travellers (assumed not to be displaying symptoms prior to boarding their flight) as they arrived at their destination. The model showed that the reduction in risk of case importation that screening alone could deliver was minimal across most scenarios considered, with outputs indicating that screening alone could detect at most 46.4%, 12.9%, and 4.0% of travellers infected with influenza, SARS and Ebola respectively, while the model also reported a detection rate of 12.0% for COVID-19. In this paper, we present a brief modification to this model allowing us to assess the added impact that quarantining incoming travelers for various periods may have on reducing the risk of case importation. Primary results show that requiring all travellers to undergo 5 days of self-isolation on arrival, after which they are tested again, has the potential to increase rates of detection to 100%, 87.6%, 81.7% and 41.3% for travellers infected with influenza, SARS, COVID-19 and Ebola respectively. Extending the period of self-isolation to 14 days increases these potential detection rates to 100%, 100%, 99.5% and 91.8% respectively.

scholarly journals Using simulation to assess the potential effectiveness of implementing screening at national borders during international outbreaks of influenza, SARS, Ebola virus disease and COVID-19

2020 ◽  
Author(s):  
Declan Bays ◽  
Emma Bennett ◽  
Thomas Finnie
Keyword(s):  
Ebola Virus ◽  
Virus Disease ◽  
Epidemiological Data ◽  
Disease Outbreak ◽  
Air Travel ◽  
International Travel ◽  
Case Scenario ◽  
Potential Effectiveness ◽  
Potential Success ◽  
Risk Of Disease

The effectiveness of screening travellers for signs of infection during times of international disease outbreak is contentious, especially as the reduction of the risk of disease importation can be very small. Border screening typically consists of arriving individuals being thermally scanned for signs of fever and/or completing a survey to declare any possible symptoms, and while more thorough testing typically exists, these would generally prove more disruptive to deploy. In this paper, we utilise epidemiological data and Monte Carlo simulation to calculate the potential success rate of deploying border screening for a range of diseases (including the current COVID-19 pandemic) in varying outbreak scenarios. We negate the issue of testing precision by assuming a perfect test is used; our outputs then represent the best-case scenario. We then use these outputs to briefly explore the types of scenarios where the implementation of border screening could prove most effective. Our models only considers screening implemented at airports, due to air travel being the predominant method of international travel. Primary results showed that in the best-case scenario, screening has the potential to detect 46.4%, 12.9% and 4.0% of travellers infected with influenza, SARS and ebola respectively, while screening for COVID-19 could potentially detect 12.0% of infected travellers. We compare our results to those already in the published literature.

Mathematical Analysis of the Role of Detection Rate on Dynamical Spread of Ebola Virus Disease

2020 ◽  
Vol 3 (1) ◽  
pp. 37-52
Author(s):  
Akanni John Olajide
Keyword(s):  
Detection Rate ◽  
Ebola Virus ◽  
Virus Disease ◽  
Ebola Virus Disease ◽  
Accurate Estimation ◽  
Infection Prevalence ◽  
Progression Rate ◽  
Case Detection ◽  
Case Detection Rate ◽  
Disease Free

In this paper, a non-linear mathematical model of the Ebola virus disease with case detection rate is proposed and analyzed. The whole population under consideration is divided into five compartments e.g. susceptible, latently infected, infected undetected, infected detected, and recovered to study the transmission dynamics of the Ebola virus disease. Based on the immunity level, susceptible individuals move to exposed class or directly to infected detected class once they come into contact with an infective. This has been incorporated through the progression rate which is slow. The equilibria of the model and the basic reproduction number R0 are computed. It is observed that the disease-free equilibrium of the model is locally asymptotically stable when R0<1. The model exhibits forward bifurcation under certain restrictions on parameters, which indicate that the model has a single endemic equilibrium for R0<1. This suggests that an accurate estimation of parameters and the level of control measures are required to reduce the infection prevalence of the Ebola virus in the endemic region and just R0<1 is enough to eliminate the disease from the population. R0needs to be lowered much below one to confirm the global stability of the disease-free equilibrium. Numerical simulation is performed to demonstrate the analytical results. It is found that the increase in the rate of case detection rate leads to a decrease in the threshold value of R0. Numerical simulations have been carried out to support the analytic results.

JOINT ESTIMATION OF THE TRANSMISSIBILITY AND SEVERITY OF EBOLA VIRUS DISEASE IN REAL TIME

2017 ◽  
Vol 25 (04) ◽  
pp. 587-603 ◽  
Author(s):  
YUSUKE ASAI ◽  
HIROSHI NISHIURA
Keyword(s):  
Real Time ◽  
Ebola Virus ◽  
Virus Disease ◽  
Critical Role ◽  
Estimation Method ◽  
Case Fatality ◽  
Ascertainment Bias ◽  
Joint Estimation ◽  
Ebola Virus Disease ◽  
Strong Impact

The effective reproduction number [Formula: see text], the average number of secondary cases that are generated by a single primary case at calendar time [Formula: see text], plays a critical role in interpreting the temporal transmission dynamics of an infectious disease epidemic, while the case fatality risk (CFR) is an indispensable measure of the severity of disease. In many instances, [Formula: see text] is estimated using the reported number of cases (i.e., the incidence data), but such report often does not arrive on time, and moreover, the rate of diagnosis could change as a function of time, especially if we handle diseases that involve substantial number of asymptomatic and mild infections and large outbreaks that go beyond the local capacity of reporting. In addition, CFR is well known to be prone to ascertainment bias, often erroneously overestimated. In this paper, we propose a joint estimation method of [Formula: see text] and CFR of Ebola virus disease (EVD), analyzing the early epidemic data of EVD from March to October 2014 and addressing the ascertainment bias in real time. To assess the reliability of the proposed method, coverage probabilities were computed. When ascertainment effort plays a role in interpreting the epidemiological dynamics, it is useful to analyze not only reported (confirmed or suspected) cases, but also the temporal distribution of deceased individuals to avoid any strong impact of time dependent changes in diagnosis and reporting.

scholarly journals Characterisation of the T-cell response to Ebola virus glycoprotein amongst survivors of the 2013–16 West Africa epidemic

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
T. R. W. Tipton ◽  
Y. Hall ◽  
J. A. Bore ◽  
A. White ◽  
L. S. Sibley ◽  
...  
Keyword(s):  
T Cell ◽  
West Africa ◽  
Cell Response ◽  
Ebola Virus ◽  
Medical Condition ◽  
Virus Disease ◽  
T Cell Response ◽  
Ebola Virus Disease ◽  
Cell Phenotype ◽  
T Cell Epitopes

AbstractZaireebolavirus (EBOV) is a highly pathogenic filovirus which can result in Ebola virus disease (EVD); a serious medical condition that presents as flu like symptoms but then often leads to more serious or fatal outcomes. The 2013–16 West Africa epidemic saw an unparalleled number of cases. Here we show characterisation and identification of T cell epitopes in surviving patients from Guinea to the EBOV glycoprotein. We perform interferon gamma (IFNγ) ELISpot using a glycoprotein peptide library to identify T cell epitopes and determine the CD4+ or CD8+ T cell component response. Additionally, we generate data on the T cell phenotype and measure polyfunctional cytokine secretion by these antigen specific cells. We show candidate peptides able to elicit a T cell response in EBOV survivors and provide inferred human leukocyte antigen (HLA) allele restriction. This data informs on the long-term T cell response to Ebola virus disease and highlights potentially important immunodominant peptides.

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