This is a book about zoonoses, diseases that come to humans from other animals. It is scary, sure, because there are always new microbes out there ready to go rampaging through our vast society. It is also rather comforting, both the methodical search for vectors and reservoirs, the details of transmission and treatment, the stream of breakthroughs that enable researchers to locate and sequence. And through it all, Quammen maintains a casual, light conversational tone, reassuring the reader that sure, horrible new diseases can (and will) spring up seemingly out of nowhere to spread around the world, but that also we have been pretty good at controlling those sorts of outbreaks.
There's quite a lot about Ebola here, written before this summer's outbreak. It should prove very comforting to everyone whose loved ones are not currently infected. I heap praise upon him for pointing out that it isn't nearly as grotesque as Preston painted it in The Hot Zone.
The only part I really disliked was the pure fiction of The Voyager, which was too long and added nothing. This was particularly annoying as I was nearing the end and racing to finish quickly before the future biologist usurped in entirely.
I don't usually comment on covers, but I will say that Chip Kidd managed to make a very disturbing one.