title: Theoretical perspectives on the infectiousness of Ebola virus disease.
abstract: BACKGROUND
  Ebola virus disease (EVD) has generated a large epidemic in West Africa since December 2013. This mini-review is aimed to clarify and illustrate different theoretical concepts of infectiousness in order to compare the infectiousness across different communicable diseases including EVD.
  
  
  METHODS
  We employed a transmission model that rests on the renewal process in order to clarify theoretical concepts on infectiousness, namely the basic reproduction number, R0, which measures the infectiousness per generation of cases, the force of infection (i.e. the hazard rate of infection), the intrinsic growth rate (i.e. infectiousness per unit time) and the per-contact probability of infection (i.e. infectiousness per effective contact).
  
  
  RESULTS
  Whereas R0 of EVD is similar to that of influenza, the growth rate (i.e. the measure of infectiousness per unit time) for EVD was shown to be comparatively lower than that for influenza. Moreover, EVD and influenza differ in mode of transmission whereby the probability of transmission per contact is lower for EVD compared to that of influenza.
  
  
  CONCLUSIONS
  The slow spread of EVD associated with the need for physical contact with body fluids supports social distancing measures including contact tracing and case isolation. Descriptions and interpretations of different variables quantifying infectiousness need to be used clearly and objectively in the scientific community and for risk communication.
authors.affiliation: Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. nishiurah@m.u-tokyo.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
authors.forename: Gerardo
authors.initials: G
authors.lastname: Chowell
mesh_terms: D050936:Basic Reproduction Number; D029043:Ebolavirus / Q000472:pathogenicity / Q000502:physiology*; D019142:Hemorrhagic Fever, Ebola / Q000635:transmission* / Q000821:virology*; D006801:Humans; D008954:Models, Biological; D012307:Risk Factors; D013997:Time Factors