scholarly journals Extinction pathways and outbreak vulnerability in a stochastic Ebola model

2017 ◽  
Vol 14 (127) ◽  
pp. 20160847 ◽  
Author(s):  
Garrett T. Nieddu ◽  
Lora Billings ◽  
James H. Kaufman ◽  
Eric Forgoston ◽  
Simone Bianco
Keyword(s):  
Ebola Virus ◽  
Reproduction Number ◽  
Virus Disease ◽  
Zoonotic Diseases ◽  
Animal Reservoir ◽  
Human Host ◽  
Zoonotic Viruses ◽  
Disease Agent ◽  
Dynamic Population ◽  
Modelling Approach

A zoonotic disease is a disease that can be passed from animals to humans. Zoonotic viruses may adapt to a human host eventually becoming endemic in humans, but before doing so punctuated outbreaks of the zoonotic virus may be observed. The Ebola virus disease (EVD) is an example of such a disease. The animal population in which the disease agent is able to reproduce in sufficient number to be able to transmit to a susceptible human host is called a reservoir. There is little work devoted to understanding stochastic population dynamics in the presence of a reservoir, specifically the phenomena of disease extinction and reintroduction. Here, we build a stochastic EVD model and explicitly consider the impacts of an animal reservoir on the disease persistence. Our modelling approach enables the analysis of invasion and fade-out dynamics, including the efficacy of possible intervention strategies. We investigate outbreak vulnerability and the probability of local extinction and quantify the effective basic reproduction number. We also consider the effects of dynamic population size. Our results provide an improved understanding of outbreak and extinction dynamics in zoonotic diseases, such as EVD.

scholarly journals Recombinant Lloviu virus as a model to study inaccessible zoonotic viruses

2021 ◽  
Author(s):  
Adam Joseph Hume ◽  
Baylee Heiden ◽  
Judith Olejnik ◽  
Ellen Lee Suder ◽  
Stephen Ross ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Inflammatory Responses ◽  
Virus Disease ◽  
Target Cells ◽  
Human Pathogens ◽  
Animal Reservoir ◽  
Cis Acting ◽  
Zoonotic Viruses ◽  
Virus Rescue ◽  
Virus Recombinant

Next generation sequencing has revealed the presence of many RNA viruses in animal reservoir hosts, including many closely related to known human pathogens. Despite their zoonotic potential, many of these viruses remain understudied due to not yet being cultured. While reverse genetic systems can facilitate virus rescue, this is often hindered by missing viral genome ends. A prime example is Lloviu virus (LLOV), an uncultured filovirus that is closely related to the highly pathogenic Ebola virus. Using minigenome systems, we complemented the missing LLOV genomic ends and identified cis-acting elements required for LLOV replication that were lacking in the published sequence. We leveraged these data to generate recombinant full-length LLOV clones and rescue infectious virus. Recombinant LLOV (rLLOV) displays typical filovirus features, as shown by electron microscopy. Known target cells of Ebola virus, including macrophages and hepatocytes, are permissive to rLLOV infection, suggesting that humans could be potential hosts. However, inflammatory responses in human macrophages, a hallmark of Ebola virus disease, are not induced by rLLOV. We also used rLLOV to test antivirals targeting multiple facets of the replication cycle. Rescue of uncultured viruses of pathogenic concern represents a valuable tool in our arsenal against pandemic preparedness.

scholarly journals Protective population behavior change in outbreaks of emerging infectious disease

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Evans K. Lodge ◽  
Annakate M. Schatz ◽  
John M. Drake
Keyword(s):  
Behavior Change ◽  
Ebola Virus ◽  
Virus Disease ◽  
Population Level ◽  
Emerging Infections ◽  
Emerging Pathogens ◽  
Susceptible Population ◽  
Zoonotic Infections ◽  
Zoonotic Viruses ◽  
And Behavior

Abstract Background During outbreaks of emerging and re-emerging infections, the lack of effective drugs and vaccines increases reliance on non-pharmacologic public health interventions and behavior change to limit human-to-human transmission. Interventions that increase the speed with which infected individuals remove themselves from the susceptible population are paramount, particularly isolation and hospitalization. Ebola virus disease (EVD), Severe Acute Respiratory Syndrome (SARS), and Middle East Respiratory Syndrome (MERS) are zoonotic viruses that have caused significant recent outbreaks with sustained human-to-human transmission. Methods This investigation quantified changing mean removal rates (MRR) and days from symptom onset to hospitalization (DSOH) of infected individuals from the population in seven different outbreaks of EVD, SARS, and MERS, to test for statistically significant differences in these metrics between outbreaks. Results We found that epidemic week and viral serial interval were correlated with the speed with which populations developed and maintained health behaviors in each outbreak. Conclusions These findings highlight intrinsic population-level changes in isolation rates in multiple epidemics of three zoonotic infections with established human-to-human transmission and significant morbidity and mortality. These data are particularly useful for disease modelers seeking to forecast the spread of emerging pathogens.

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

2014 ◽  
Vol 19 (36) ◽  
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.

scholarly journals Ebola virus disease outbreak in Nigeria: transmission dynamics and rapid control

2015 ◽  
Author(s):  
Christian L Althaus ◽  
Nicola Low ◽  
Emmanuel O. Musa ◽  
Faisal Shuaib ◽  
Sandro Gsteiger
Keyword(s):  
Ebola Virus ◽  
Reproduction Number ◽  
Time Window ◽  
Index Case ◽  
Virus Disease ◽  
Control Measures ◽  
Ebola Virus Disease ◽  
Transmission Model ◽  
The Individual ◽  
The Impact

International air travel has already spread Ebola virus disease (EVD) to major cities as part of the unprecedented epidemic that started in Guinea in December 2013. An infected airline passenger arrived in Nigeria on July 20, 2014 and caused an outbreak in Lagos and then Port Harcourt. After a total of 20 reported cases, including 8 deaths, Nigeria was declared EVD free on October 20, 2014. We quantified the impact of early control measures in preventing further spread of EVD in Nigeria and calculated the risk that a single undetected case will cause a new outbreak. We fitted an EVD transmission model to data from the outbreak in Nigeria and estimated the individual reproduction number of the index case at 9.0 (95% confidence interval [CI]: 5.2-15.6). We also found that the net reproduction number fell below unity 15 days (95% CI: 11-21 days) after the arrival of the index case. Hence, our study illustrates the time window for successful containment of EVD outbreaks caused by infected air travelers.

scholarly journals Ebola virus disease in the Democratic Republic of the Congo, 1976-2014

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Alicia Rosello ◽  
Mathias Mossoko ◽  
Stefan Flasche ◽  
Albert Jan Van Hoek ◽  
Placide Mbala ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Democratic Republic ◽  
Reproduction Number ◽  
Virus Disease ◽  
Age Groups ◽  
Ebola Virus Disease ◽  
Virus Discovery ◽  
International Response ◽  
Republic Of The Congo ◽  
First Time

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.

scholarly journals Modelling the Effect of Post-mortem Contact on the Spread of Ebola with Quarantine As an Intervention

2016 ◽  
Vol 8 (4) ◽  
pp. 176
Author(s):  
Francis T. Oduro ◽  
Joseph Baafi ◽  
George Apaaboah
Keyword(s):  
Numerical Simulations ◽  
Ebola Virus ◽  
Reproduction Number ◽  
Virus Disease ◽  
Disease Outbreak ◽  
Virus Species ◽  
Post Mortem ◽  
Fatal Disease ◽  
The Family ◽  
Better Than

Ebola virus disease (EVD) is a severe, often fatal disease in humans and other non-human primates caused by infection with any of the four identified Ebola virus species of the family Filoviridae. This paper develops the SEIR and the SEIHDR epidemic models that investigate the effects of the ante-mortem contact and post-mortem contact on the spread of the disease. The reproduction number of the models are determined. The equilibria and conditions for the existence of the equilibria are also determined. The models are solved numerically and the numerical simulations implemented to elucidate various scenarios. The results of the models are then compared to WHO data of confirmed cases for the 2014 Ebola outbreak in Liberia. It is observed that the SEIHDR model agrees better with the data than the SEIR model. Moreover, a new model, the SEIQDR model (a modification of the SEIHDR Model) is formulated which incorporates quarantine as an intervention. Again, this SEIQDR model is compared to the WHO data of confirmed cases for the 2014 Ebola outbreak in Liberia. The results of the SEIQDR model is found to agree better than those of the other models especially in respect of the latter stages  of the disease outbreak. Finally, the effect of vaccination on both the SEIHDR and the SEIQDR models is investigated. Different rates of vaccination using numerical simulations in order to predict the effect of vaccination on the infected individuals over time is also discussed. The SEIQDR model with vaccination indicates a lower threshold which should not be less than 25\% as compared to the SEIHDR model for which vaccination should not be less than 65\%. It is observed that vaccination as an additional strategy helps to control the disease more effectively.

scholarly journals Ebola virus disease outbreak in Nigeria: lessons to learn

2014 ◽  
Author(s):  
Christian L Althaus ◽  
Sandro Gsteiger ◽  
Nicola Low
Keyword(s):  
Ebola Virus ◽  
Reproduction Number ◽  
Virus Disease ◽  
Control Measures ◽  
Ebola Virus Disease ◽  
Transmission Model ◽  
Port Harcourt ◽  
Airline Passenger ◽  
Net Reproduction ◽  
The Impact

International air travel has already spread Ebola virus disease (EVD) to major cities as part of the unprecedented epidemic that started in Guinea in December 2013. An infected airline passenger arrived in Nigeria on July 20, 2014 and caused an outbreak in Lagos and then Port Harcourt. After a total of 20 reported cases, including 8 deaths, Nigeria was declared EVD free on October 20, 2014. We quantified the impact of early control measures in preventing further spread of EVD in Nigeria and calculated the risk that a single undetected case will cause a new outbreak. We fitted an EVD transmission model to data from the outbreak in Nigeria and estimated the basic reproduction number R0 = 9.0 (95% confidence interval [CI]: 5.2-15.6). We also found that the net reproduction number Rt fell below unity 15 days (95% CI: 11-21 days) after the arrival of the index case. Using the estimated value of R0 in Nigeria, we calculated that the risk of an outbreak from a single undetected case was 89% (95% CI: 81-94%). Even though R0 in Nigeria was high, EVD outbreaks caused by infected air travelers can be successfully contained if control measures are rapidly implemented.

scholarly journals Rapid drop in the reproduction number during the Ebola outbreak in the Democratic Republic of Congo

2015 ◽  
Author(s):  
Christian L Althaus
Keyword(s):  
Rural Areas ◽  
Ebola Virus ◽  
Democratic Republic ◽  
Reproduction Number ◽  
Democratic Republic Of Congo ◽  
Virus Disease ◽  
Outbreak Detection ◽  
Transmission Model ◽  
Republic Of Congo ◽  
Net Reproduction

In 2014, the Democratic Republic of Congo (DRC) experienced an outbreak of Ebola virus disease (EVD) with 69 reported cases. I fitted an EVD transmission model to data of this outbreak and estimated the basic reproduction number R0 = 5.2 (95% confidence interval [CI]: 4.0-6.7). The model suggests that the net reproduction number Rt fell below unity 28 days (95% CI: 25-34 days) after the onset of symptoms in the index case. This illustrates that early outbreak detection and rapid implementation of control interventions are crucial for preventing wider spread of EVD in rural areas.

scholarly journals Spatial variability in the reproduction number of Ebola virus disease, Democratic Republic of the Congo, January–September 2019

2019 ◽  
Vol 24 (42) ◽  
Author(s):  
Kenji Mizumoto ◽  
Amna Tariq ◽  
Kimberlyn Roosa ◽  
Jun Kong ◽  
Ping Yan ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Democratic Republic ◽  
Reproduction Number ◽  
Virus Disease ◽  
National Level ◽  
Statistical Modelling ◽  
Ebola Virus Disease ◽  
Modelling Framework ◽  
Republic Of The Congo ◽  
Substantial Uncertainty

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 (R t) at national and regional levels as at 29 September. The weekly trend in R t displays fluctuations while our recent national-level R t falls slightly above 1.0 with substantial uncertainty, which suggests improvements in epidemic control.

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