Ebola: new methodology to identify the drivers for spillover

EFSA’s experts have investigated the factors that may have contributed to the transmission of the Ebola virus from animals to humans in West Africa. The drivers for this spillover event range from social to environmental. They include deforestation, hunting and demographic changes in wildlife.

Understanding the drivers for Ebola spillover requires a multi-disciplinary perspective, experts conclude. “This report clearly shows how important it is that research on the emergence of infectious diseases should take a holistic approach, picking from different disciplines,” says Franck Berthe, Head of EFSA’s Animal and Plant Health unit. “The methodology used in this report can be applied to other complex topics that require graphical visualisation of diverse yet connected factors.

Experts identified the drivers through a literature review and grouped them according to categories – social, technological, environmental, economic, and political. They analysed the main arguments used in literature to identify links between drivers, and produced visualisations showing networks of drivers, their interactions and the strength of their links.

The report has some limitations and therefore the outcomes need to be interpreted with caution. For example, there are only a few documented spillover events for which scientific evidence is available. Also few studies explicitly address the issue of drivers. The visualisations are based on current knowledge and should be validated through field studies.

The current outbreak in West Africa was caused by the Zaire Ebola virus, which started in Guinea in 2013 and then spread to neighbouring countries. It is still active in Guinea and Sierra Leone. 

The report was developed by EFSA scientists and external experts from the World Health Organization, the Food and Agriculture Organization and the European Centre for Disease Prevention and Control with expertise drawn from a variety of disciplines – such as human and veterinary medicine, epidemiology, social sciences, and environmental sciences.  

Media contacts