A Quantitative Framework to Define the End of an Outbreak: Application to Ebola Virus Disease

Abstract The end-of-outbreak declaration is an important step in controlling infectious disease outbreaks. An objective estimation of the confidence level that an outbreak is over is important to reduce the risk of post-declaration flare-ups. We developed a simulation-based model to quantify that confidence. We tested it on simulated Ebola Virus Disease data. We found these confidence estimates were most sensitive to the instantaneous reproduction number, the reporting rate, and the time between the symptom onset to death or recovery of the last detected case. For Ebola Virus Disease, our results suggest that the current World Health Organization criterion of 42 days since the recovery or death of the last detected case is too short and sensitive to underreporting. Therefore, we suggest a shift to a preliminary end-of-outbreak declaration after 63 days from the symptom onset day of the last detected case. This preliminary declaration should still be followed by 90 days of enhanced surveillance to capture potential flare-ups of cases, after which the official end-of-outbreak can be declared. This sequence corresponds to more than 95% confidence that an outbreak is over in most of the scenarios examined. Our framework is generic, and therefore could be adapted to estimate end-of-outbreak confidence for other infectious diseases.

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A quantitative framework to define the end of an outbreak: application to Ebola Virus Disease

10.1101/2020.02.17.20024042 ◽

2020 ◽

Cited By ~ 1

Author(s):

Bimandra A Djaafara ◽

Natsuko Imai ◽

Esther Hamblion ◽

Benido Impouma ◽

Christl A Donnelly ◽

...

Keyword(s):

Symptom Onset ◽

Ebola Virus ◽

Reproduction Number ◽

Virus Disease ◽

Disease Outbreaks ◽

Reporting Rate ◽

Ebola Virus Disease ◽

Surveillance Period ◽

Infectious Disease Outbreaks ◽

Simulation Based

Declaring the end of an outbreak is an important step in controlling infectious disease outbreaks. An objective estimation of the probability of cases arising in the future is important to reduce the risk of post-declaration flare-ups. We developed a simulation-based model to quantify that probability. We tested it on simulated Ebola Virus Disease (EVD) data and found this probability was most sensitive to the instantaneous reproduction number, the reporting rate, and the delay between symptom onset and recovery or death of the last detected case. For EVD, our results suggest that the current WHO criterion of 42 days since the outcome of the last detected case is too short and very sensitive to underreporting. The 90 days of enhanced surveillance period after the end-of-outbreak declaration is therefore crucial to capture potential flare-ups of cases. Hence, we suggest a shift to a preliminary end-of-outbreak declaration after 63 days from the symptom onset day of the last detected case. This should be followed by a 90-day enhanced surveillance, after which the official end-of-outbreak can be declared. This corresponds to less than 5% probability of flare ups in most of the scenarios examined. Our quantitative framework could be adapted to define end-of-outbreak criteria for other infectious diseases.

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How World Health Organization has fared in tackling the 2014-2015 outbreak of Ebola virus disease?

Journal of Research in Medical Sciences ◽

10.4103/1735-1995.170635 ◽

2015 ◽

Vol 20 (9) ◽

pp. 919

Author(s):

SaurabhR Shrivastava ◽

PrateekS Shrivastava ◽

Jegadeesh Ramasamy

Keyword(s):

World Health Organization ◽

Ebola Virus ◽

Virus Disease ◽

Ebola Virus Disease ◽

World Health ◽

Health Organization

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The Epidemiological Presentation Pattern of Ebola Virus Disease Outbreaks: Changes from 1976 to 2019

Prehospital and Disaster Medicine ◽

10.1017/s1049023x20000333 ◽

2020 ◽

Vol 35 (3) ◽

pp. 247-253

Author(s):

Pedro Arcos González ◽

Ángel Fernández Camporro ◽

Anneli Eriksson ◽

Carmen Alonso Llada

Keyword(s):

At Risk ◽

Ebola Virus ◽

Virus Disease ◽

Disease Outbreaks ◽

Case Fatality ◽

Ebola Virus Disease ◽

World Health ◽

Study Objective ◽

Population At Risk ◽

Case Fatality Ratio

AbstractIntroduction:Ebola Virus Disease (EVD) is the international health emergency paradigm due to its epidemiological presentation pattern, impact on public health, resources necessary for its control, and need for a national and international response.Study Objective:The objective of this work is to study the evolution and progression of the epidemiological presentation profile of Ebola disease outbreaks since its discovery in 1976 to the present, and to explore the possible reasons for this evolution from different perspectives.Methods:Retrospective observational study of 38 outbreaks of Ebola disease occurred from 1976 through 2019, excluding laboratory accidents. United Nations agencies and programs; Ministries of Health; the US Centers for Disease Control and Prevention (CDC); ReliefWeb; emergency nongovernmental organizations; and publications indexed in PubMed, EmBase, and Clinical Key have been used as sources of data. Information on the year of the outbreak, date of beginning and end, duration of the outbreak in days, number of cases, number of deaths, population at risk, geographic extension affected in Km2, and time of notification of the first cases to the World Health Organization (WHO) have been searched and analyzed.Results:Populations at risk have increased (P = .024) and the geographical extent of Ebola outbreaks has grown (P = .004). Reporting time of the first cases of Ebola to WHO has been reduced (P = .017) and case fatality (P = .028) has gone from 88% to 62% in the period studied. There have been differences (P = .04) between the outbreaks produced by the Sudan and Zaire strains of the virus, both in terms of duration and case fatality ratio (Sudan strain 74.5 days on average and 62.7% of case fatality ratio versus Zaire strain with 150 days on average and 55.4% case fatality ratio).Conclusion:There has been a change in the epidemiological profile of the Ebola outbreaks from 1976 through 2019 with an increase in the geographical extent of the outbreaks and the population at risk, as well as a significant decrease in the outbreaks case fatality rate. There have been advances in the detection and management capacity of outbreaks, and the notification time to the WHO has been reduced. However, there are social, economic, cultural, and political obstacles that continue to greatly hinder a more efficient epidemiological approach to Ebola disease, mainly in Central Africa.

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Reconsidering the Ethical Permissibility of the Use of Unregistered Interventions against Ebola Virus Disease

Cambridge Quarterly of Healthcare Ethics ◽

10.1017/s0963180114000681 ◽

2015 ◽

Vol 24 (3) ◽

pp. 366-369 ◽

Cited By ~ 2

Author(s):

JOSHUA T. LANDRY ◽

THOMAS FOREMAN ◽

MICHAEL KEKEWICH

Keyword(s):

Ebola Virus ◽

Virus Disease ◽

Ebola Virus Disease ◽

World Health ◽

Ethical Considerations ◽

Ethical Imperative ◽

The World ◽

Considerable Debate ◽

Health Organization ◽

Do So

Abstract:Ethical considerations for the use of unregistered interventions for Ebola virus disease have sparked considerable debate among academic and clinical ethicists. In August 2014 the World Health Organization (WHO) convened a panel of experts to discuss approaches to the outbreak in West Africa, with the goal of determining "whether it is ethical to use unregistered interventions with unknown adverse effects for possible treatment or prophylaxis”.1 The panel concluded that there would be an ethical imperative to provide such unregistered interventions if specific criteria could be met. This paper evaluates the WHO conclusion and argues that although it may be reasonable to provide unregistered interventions considering the circumstance, there is no clear ethical imperative to do so.

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Early transmission dynamics of Ebola virus disease (EVD), West Africa, March to August 2014

Eurosurveillance ◽

10.2807/1560-7917.es2014.19.36.20894 ◽

2014 ◽

Vol 19 (36) ◽

Cited By ~ 81

Author(s):

H Nishiura ◽

G Chowell

Keyword(s):

Sierra Leone ◽

Ebola Virus ◽

Reproduction Number ◽

Virus Disease ◽

Ebola Virus Disease ◽

World Health ◽

Primary Case ◽

Specific Data ◽

Health Organization ◽

Country Specific

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.

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The 2014 Ebola virus disease outbreak in West Africa

Journal of General Virology ◽

10.1099/vir.0.067199-0 ◽

2014 ◽

Vol 95 (8) ◽

pp. 1619-1624 ◽

Cited By ~ 139

Author(s):

Derek Gatherer

Keyword(s):

West Africa ◽

Ebola Virus ◽

Virus Disease ◽

Single Case ◽

Atlantic Coast ◽

Urban Setting ◽

Ebola Virus Disease ◽

World Health ◽

The Republic ◽

Health Organization

On 23 March 2014, the World Health Organization issued its first communiqué on a new outbreak of Ebola virus disease (EVD), which began in December 2013 in Guinée Forestière (Forested Guinea), the eastern sector of the Republic of Guinea. Located on the Atlantic coast of West Africa, Guinea is the first country in this geographical region in which an outbreak of EVD has occurred, leaving aside the single case reported in Ivory Coast in 1994. Cases have now also been confirmed across Guinea as well as in the neighbouring Republic of Liberia. The appearance of cases in the Guinean capital, Conakry, and the transit of another case through the Liberian capital, Monrovia, presents the first large urban setting for EVD transmission. By 20 April 2014, 242 suspected cases had resulted in a total of 147 deaths in Guinea and Liberia. The causative agent has now been identified as an outlier strain of Zaire Ebola virus. The full geographical extent and degree of severity of the outbreak, its zoonotic origins and its possible spread to other continents are sure to be subjects of intensive discussion over the next months.

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Clinical and epidemiological features of the disease caused by the Ebola virus, at the present stage: pathogenetic basis of therapy

Epidemiology and Infectious Diseases (Russian Journal) ◽

10.17816/eid40848 ◽

2015 ◽

Vol 20 (1) ◽

pp. 32-39

Author(s):

O. I Kiselev ◽

L. M Tsybalova ◽

E. G Deeva ◽

V. V Tsvetkov ◽

G. S Golobokov ◽

...

Keyword(s):

West Africa ◽

Coming Out ◽

Ebola Virus ◽

Virus Disease ◽

Disease Outbreaks ◽

Multiple Organ ◽

World Health ◽

Pathogenetic Therapy ◽

Sporadic Cases ◽

Health Organization

Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever is severe acute infectious diseases accompanied by the development of severe systemic inflammatory response followed by the addition of disseminated intravascular coagulation and multiple organ failure. Since 1976 in Africa regularly observed disease outbreaks among humans caused by different types of Ebola virus. Modern epidemic in West Africa began in Guinea in February 2014 and is still going on, coming out of the country and distributed in Liberia, Sierra Leone and Nigeria. According to the World Health Organization (WHO) on December 14, 2014 recorded 18,603 cases of them confirmed EVD 11807, fatal 6915. From July 2014 to currently registered sporadic cases EVD among health care workers caring for patients, as well as among tourists returning from countries affected by the epidemic is already outside of West Africa. Due to the limited use of specific antiviral therapy with special attention to the management ofpatients with EVD should be paid to the intensive and timely pathogenetic therapy. Today, the only way to reduce morbidity and mortality among people from EVD is awareness on the risk factors of infection and the use ofpersonal protective measures.

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Addressing Disease-Related Stigma During Infectious Disease Outbreaks

Disaster Medicine and Public Health Preparedness ◽

10.1017/dmp.2018.157 ◽

2019 ◽

Vol 13 (5-6) ◽

pp. 989-994 ◽

Cited By ~ 14

Author(s):

Leah S. Fischer ◽

Gordon Mansergh ◽

Jonathan Lynch ◽

Scott Santibanez

Keyword(s):

Infectious Disease ◽

Zika Virus ◽

Ebola Virus ◽

Virus Disease ◽

Disease Outbreaks ◽

Ebola Virus Disease ◽

Effective Control ◽

Infectious Disease Outbreaks ◽

Influenza A H1n1 ◽

Related Stigma

ABSTRACTOutbreaks of emerging infectious disease are a constant threat. In the last 10 years, there have been outbreaks of 2009 influenza A (H1N1), Ebola virus disease, and Zika virus. Stigma associated with infectious disease can be a barrier to adopting healthy behaviors, leading to more severe health problems, ongoing disease transmission, and difficulty controlling infectious disease outbreaks. Much has been learned about infectious disease and stigma in the context of nearly 4 decades of the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome pandemic. In this paper, we define stigma, discuss its relevance to infectious disease outbreaks, including how individuals and communities can be affected. Adapting lessons learned from the rich literature on HIV-related stigma, we propose a strategy for reducing stigma during infectious disease outbreaks such as Ebola virus disease and Zika virus. The implementation of brief, practical strategies such as the ones proposed here might help reduce stigma and facilitate more effective control of emerging infectious diseases.

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Emergence of the Ebola Virus Disease in West Africa

Examining the Role of Environmental Change on Emerging Infectious Diseases and Pandemics - Advances in Human Services and Public Health ◽

10.4018/978-1-5225-0553-2.ch007 ◽

2017 ◽

pp. 163-177

Author(s):

Samir Dervisevic

Keyword(s):

West Africa ◽

Ebola Virus ◽

Virus Disease ◽

Central Africa ◽

Ebola Virus Disease ◽

World Health ◽

Viral Haemorrhagic Fever ◽

The World ◽

Viral Illness ◽

Health Organization

This chapter gives an overview on the recent outbreak of Ebola Virus Disease in West Africa which has lasted for over seventeen months. The Ebola virus has been implicated as a causative agent of viral haemorrhagic fever occurring in Central Africa over the last thirty-nine years. However, the Ebola virus has not previously been recognised as an endemic virus causing outbreaks of viral illness in West Africa. The start of what was to become the largest Ebola virus disease (EVD) outbreak in known history was first reported to the World Health Organization (WHO) on the 23rd of March 2014 and since then it has transformed into an unprecedented and severe epidemic affecting the three countries of West Africa (Guinea, Liberia and Sierra Leone). The emergence of this lethal virus in a setting of profound poverty, a dysfunctional public-health and a weak government infrastructure alarmed the wider world and caused dread from an uncontrollable spread.

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