title: Assessing the international spreading risk associated with the 2014 west african ebola outbreak.
abstract: BACKGROUND
  The 2014 West African Ebola Outbreak is so far the largest and deadliest recorded in history. The affected countries, Sierra Leone, Guinea, Liberia, and Nigeria, have been struggling to contain and to mitigate the outbreak. The ongoing rise in confirmed and suspected cases, 2615 as of 20 August 2014, is considered to increase the risk of international dissemination, especially because the epidemic is now affecting cities with major commercial airports.
  
  
  METHODS
  We use the Global Epidemic and Mobility Model to generate stochastic, individual based simulations of epidemic spread worldwide, yielding, among other measures, the incidence and seeding events at a daily resolution for 3,362 subpopulations in 220 countries. The mobility model integrates daily airline passenger traffic worldwide and the disease model includes the community, hospital, and burial transmission dynamic. We use a multimodel inference approach calibrated on data from 6 July to the date of 9 August 2014. The estimates obtained were used to generate a 3-month ensemble forecast that provides quantitative estimates of the local transmission of Ebola virus disease in West Africa and the probability of international spread if the containment measures are not successful at curtailing the outbreak.
  
  
  RESULTS
  We model the short-term growth rate of the disease in the affected West African countries and estimate the basic reproductive number to be in the range 1.5 - 2.0 (interval at the 1/10 relative likelihood). We simulated the international spreading of the outbreak and provide the estimate for the probability of Ebola virus disease case importation in countries across the world. RESULTS indicate that the short-term (3 and 6 weeks) probability of international spread outside the African region is small, but not negligible. The extension of the outbreak is more likely occurring in African countries, increasing the risk of international dissemination on a longer time scale.
authors: Laboratory for the Modeling of Biological and Socio-technical Systems, Northeastern University, Boston, Massachusetts, USA.
authors: Marcelo F C
authors: MF
authors: Gomes
authors: Laboratory for the Modeling of Biological and Socio-technical Systems, Northeastern University, Boston, Massachusetts, USA.
authors: Ana
authors: A
authors: Pastore Y Piontti
authors: Institute for Scientific Interchange (ISI), Torino, Italy.
authors: Luca
authors: L
authors: Rossi
authors: Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
authors: Dennis
authors: D
authors: Chao
authors: Department of Biostatistics, University of Florida, Gainesville, Florida, USA.
authors: Ira
authors: I
authors: Longini
authors: Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center and Biostatistics, University of Washington, Seattle, Washington, USA.
authors: M Elizabeth
authors: ME
authors: Halloran
authors: Laboratory for the Modeling of Biological and Socio-Technical Systems, Northeastern University, Boston, Massachusetts, USA.
authors: Alessandro
authors: A
authors: Vespignani
keywords: 2014WA; EVD; disease model; disease outbreak; infectious disease
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