The Hot Zone by Richard Preston

This was a really good read. I heard about it several months ago on a Reddit post where a commented stated something like, "there's a cave in Africa that gives an unknown disease to everyone enters it, only three people who ever entered it have survived." The next comment pointed out that that wasn't entirely true, and that they were probably referring to Kitum Cave as featured in the this book.

The Hot Zone: The Terrifying True Story of the Origins of the Ebola Virus