title: Spatiotemporal Evolution of Ebola Virus Disease at Sub-National Level during the 2014 West Africa Epidemic: Model Scrutiny and Data Meagreness.
abstract: BACKGROUND
  The Ebola outbreak in West Africa has infected at least 27,443 individuals and killed 11,207, based on data until 24 June, 2015, released by the World Health Organization (WHO). This outbreak has been characterised by extensive geographic spread across the affected countries Guinea, Liberia and Sierra Leone, and by localized hotspots within these countries. The rapid recognition and quantitative assessment of localised areas of higher transmission can inform the optimal deployment of public health resources.
  
  
  METHODS
  A variety of mathematical models have been used to estimate the evolution of this epidemic, and some have pointed out the importance of the spatial heterogeneity apparent from incidence maps. However, little is known about the district-level transmission. Given that many response decisions are taken at sub-national level, the current study aimed to investigate the spatial heterogeneity by using a different modelling framework, built on publicly available data at district level. Furthermore, we assessed whether this model could quantify the effect of intervention measures and provide predictions at a local level to guide public health action. We used a two-stage modelling approach: a) a flexible spatiotemporal growth model across all affected districts and b) a deterministic SEIR compartmental model per district whenever deemed appropriate.
  
  
  RESULTS
  Our estimates show substantial differences in the evolution of the outbreak in the various regions of Guinea, Liberia and Sierra Leone, illustrating the importance of monitoring the outbreak at district level. We also provide an estimate of the time-dependent district-specific effective reproduction number, as a quantitative measure to compare transmission between different districts and give input for informed decisions on control measures and resource allocation. Prediction and assessing the impact of control measures proved to be difficult without more accurate data. In conclusion, this study provides us a useful tool at district level for public health, and illustrates the importance of collecting and sharing data.
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Santermans
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Robesyn
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.
authors.forename: Tapiwa
authors.initials: T
authors.lastname: Ganyani
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Sudre
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.
authors.forename: Christel
authors.initials: C
authors.lastname: Faes
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Chantal
authors.initials: C
authors.lastname: Quinten
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Wim
authors.initials: W
authors.lastname: Van Bortel
authors.affiliation: Expertise centre for Digital Media, iMinds, tUL, Diepenbeek, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Haber
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.|Expertise centre for Digital Media, iMinds, tUL, Diepenbeek, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kovac
authors.affiliation: Expertise centre for Digital Media, iMinds, tUL, Diepenbeek, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Van Reeth
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.|Department of Public Health, University of Turin, Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Testa
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.|Centre for Health Economics Research and Modelling Infectious Diseases, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.
authors.forename: Niel
authors.initials: N
authors.lastname: Hens
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Diamantis
authors.initials: D
authors.lastname: Plachouras
mesh_terms: D029043:Ebolavirus / Q000502:physiology*; D058872:Epidemics / Q000706:statistics & numerical data; D019142:Hemorrhagic Fever, Ebola / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission*; D006801:Humans; D008962:Models, Theoretical