In an analysis of nearly 40 years of “lessons learned” since the first Ebola outbreak, Laurie Garrett stresses the importance of avoiding infected animals:
[T]he index case – the initial person contaminated with the Ebola virus – is usually a hunter or villager who recently spent time deep in a tropical forest and came into contact with an animal carrying the virus. In Yambuku, the index case was a hunter; in Kikwit he was a charcoal-maker who spent a week burning wood in the forest to sell in town; in a prior West African outbreak, the index case was a family that killed and ate an ailing chimpanzee. Stopping the spread must include cutting off contact between forest animals and human beings, especially tropical fruit bats that harbor the virus without harm to themselves, and the monkeys and apes that eat the bats or fruit that they chew on, contracting Ebola in the process.
Unfortunately, climate change makes it increasingly difficult for humans to maintain that distance:
Across Africa, typically shy bat species pollinate the trees of the rain forests as they nocturnally scour for fruit. As the heat increases in the upper canopies of forests, due to climate change, and as humans increase their logging operations, the bat populations are now under great stress. When distressed by such environmental changes, animals are more likely to venture near human habitation in search of food, and come down from the upper tiers of forests into tree levels filled with predatory monkeys and chimps.