Thanks to Kelly Hills for picking up on Maia Majumder's comments on the origins of the Guinea Ebola outbreak. An intriguing Twitter discussion followed Kelly's citation of this 2004 report in Emerging Infectious Diseases: Ecologic and Geographic Distribution of Filovirus Disease. It's a long article that deserves your attention. The abstract:
We used ecologic niche modeling of outbreaks and sporadic cases of filovirus-associated hemorrhagic fever (HF) to provide a large-scale perspective on the geographic and ecologic distributions of Ebola and Marburg viruses.
We predicted that filovirus would occur across the Afrotropics: Ebola HF in the humid rain forests of central and western Africa, and Marburg HF in the drier and more open areas of central and eastern Africa. Most of the predicted geographic extent of Ebola HF has been observed; Marburg HF has the potential to occur farther south and east.
Ecologic conditions appropriate for Ebola HF are also present in Southeast Asia and the Philippines, where Ebola Reston is hypothesized to be distributed.
This first large-scale ecologic analysis provides a framework for a more informed search for taxa that could constitute the natural reservoir for this virus family.