From the text:Kitum Cave is Mount Elgon’s equivalent of the Times Square subway station. It is an underground traffic zone, a biological mixing point where different species of animals and insects cross one another’s paths in an enclosed air space. A nice place for a virus to jump species.
Preston, Richard. The Hot Zone: The Terrifying True Story of the Origins of the Ebola Virus (p. 396). Knopf Doubleday Publishing Group. Kindle Edition.