Note to self and others who have read Richard Preston's "Hot Zone": The 1989 Reston (US) incident was NOT caused by a single-base mutation of Ebola, but by a distinct monkey virus. Preston seems to have made that up to dramatize events.
I read that book when I was probably way too young for it, and that incident made me spend a lot of time staring at the ceiling in the middle of the night. I'll have to dig into it more!