Phenology supports the eco-environmental hypothesis for Ebola spillover events

Ebola virus disease outbreaks in mammals (including humans and great apes) start with sporadic host switches from unknown reservoir species. The factors leading to such spillover events are not clearly understood. Filoviridae have a wide range of natural hosts and are unstable once outside hosts. Spillover events, which involve the physical transfer of viral particles across species, could therefore be directly promoted by conditions of host ecology and environment. In this report we outline a proof of concept that temporal fluctuations of a set of eco-environmental variables describing the dynamics of the host ecosystem are able to predict such events of Ebola virus spillover to humans and animals. We newly compiled a dataset of climate and phenology variables and Ebola virus disease spillovers in humans and animals. We identified critical biotic and abiotic conditions for spillovers via multiple regression and neural networks based time series regression. Phenology variables proved to be overall better predictors than climate variables. African phenology variables are not yet available as a comprehensive online resource. Given the likely importance of phenology for forecasting the likelihood of future Ebola spillover events, our results highlight the need for more phenology monitoring to supply data for predictive modelling efforts. _________________________________________