An update on the risk of transmission of Ebola virus (EBOV) via the food chain – Part 2
‘Top-down’ (e.g. surveillance-based) and ‘bottom-up’ approaches (e.g. using the standard microbial risk assessment paradigm) were combined to assess the risk of foodborne transmission of Ebola virus to persons in Europe arising from the consumption of raw food other than bushmeat imported from African countries where human outbreaks due to Zaïre Ebola virus (ZEBOV) have occurred. Using the ‘top-down’ approach, it was concluded that food other than bushmeat has never been identified as associated with human ZEBOV cases in any of the reported outbreaks. There is no evidence for foodborne transmission of ZEBOV to persons in the European Union (EU). The ‘bottom-up’ approach revealed that the necessary sequence of events in the risk pathway involves many hurdles: 1) the raw food to be exported has to be contaminated with ZEBOV at the point of origin; 2) the imported food needs to contain viable virus when it arrives in the EU; 3) the person has to be exposed to the virus; and 4) the person needs to get infected following exposure. Each of these steps is necessary in order for a case of disease to occur and none have been documented to happen in practice. Due to lack of data and knowledge, which results in very high uncertainty, it is not possible to quantify the risk of foodborne transmission of ZEBOV derived from the consumption of these imported foods, or in fact whether or not this mode of transmission could occur at all. The overall conclusions of both approaches are consistent and suggest that the risk of foodborne transmission of ZEBOV via food other than bushmeat imported into the EU remains a theoretical possibility only and has never been demonstrated in practice. However, the uncertainty in the combined assessment is considered high given the lack of data.