Drivers for occasional spillover event of Ebola virus

Zaïre Ebola virus, spillover, reservoir, susceptible species, drivers
First published in the EFSA Journal
25 juin 2015
25 juin 2015
Scientific Report


In order to identify the drivers for spillover of Ebola virus from animal to humans, a set of drivers for spillover of infectious diseases was identified from the literature. A subset of scientific studies was used to structure a corpus of relevant arguments. This corpus was used to analyse the driver network and visualise the driver behaviour. The analysis led to the identification of 40 drivers, connected through 142 linkages. The visualisation of the driver network showed that central drivers involved in spillover are ‘Hunting’, ‘Deforestation/forest fragmentation’, and ‘Demographic changes of wildlife’. The most frequent driver links identified were ‘Deforestation/forest fragmentation’ leading to ‘Ecosystem changes’ and ‘Livelihoods resilience’ leading to ‘Hunting’. Different limitations may affect this methodology, such as the limited number of documented Ebola spillover events from which scientific evidence is available, the limited number of published studies which address the issue of drivers for spillover, and the nature of some review studies interpreting evidence from original research papers. The findings reported here should therefore be interpreted as a reflection of the current view of the scientific community on Ebola virus spillover, rather than a comprehensive representation of drivers of spillover. The methodology used in this report demonstrates a more structured and transparent approach to analysing drivers for infectious diseases. This methodology could further be applied to other complex topics that would benefit from visualisations of diverse yet connected factors. One of the main conclusions of this work is that understanding the drivers of Ebola virus spillover in West Africa requires a multi-disciplinary perspective. The need for cooperation across disciplines is not limited to Ebola. Research on the drivers of emergence of infectious diseases at the human/animal interface should take a holistic approach, including multidisciplinary backgrounds and fostering knowledge from different disciplines.

European Food Safety Authority
ALPHA [at]
EFSA Journal 2015;13(6):4161
Question Number
On request from
European Commission