I read it a few years back also. Reccomended! As I recall, the caretaker did have ebola, but it was the new 4th mutation known as the reston strain. The virus spreads by contact of others with the bodily fluids mostly spread when a victim crashes and bleeds out. Since the reston strain produced few and mild symptoms, it would not have spread as dangerously and been hopefully harmless as a cold if it did.
Another striking memory I have is the description of the man vs. monkey scenario which the teams had to face. A 10lb. monkey is an aproximate match for a 200lb. man. The monkey will use its tail to hold around the neck, while ripping the head with its teeth and gouging eyes etc. And a monkey's strength is about 7 times that of a humans by weight. I'm glad I wasn't part of that nightmare.