AIDS, he adds, that destroyer of 30 million people, is of zoonotic origin.

In “Spillover” Mr. Quammen investigates many of these diseases, some more than others. He describes the baffled horror of initial outbreaks and then tracks calmly backward. He talks to virologists, doctors, field biologists and survivors about how the animal-to-human infection came to pass. He hopscotches the globe like a journalistic Jason Bourne. Often there aren’t doctors left to be interviewed. The medical personnel who first came into contact with sick patients are frequently dead.

Among these diseases, the devils we know are bad enough. Mr. Quammen also thinks determinedly about what he calls the NBO’s — the Next Big Ones. “Will the Next Big One come out of a rain forest or a market in southern China?” he asks. “Will the Next Big One kill” 30 million or 40 million people? He makes you dread that sneeze at the back of the bus.

Mr. Quammen, whose previous books include “The Song of the Dodo” (1996) and “Monster of God” (2003), is not just among our best science writers but among our best writers, period. (Check out his much anthologized short story “Walking Out,” about a father and son gone hunting, if you want a taste of his fiction.) That he hasn’t won a nonfiction National Book Award or Pulitzer Prize is an embarrassment.

“Spillover” is a work of synthesis, not original science, and Mr. Quammen is generous about crediting his sources. But he doesn’t shy from serious science, to the extent that he sometimes apologizes for going overboard:

“If you followed all that, at a quick reading,” he writes on Page 136, “you have a future in biology.” (I suffered flashbacks to my least favorite college courses.) His zest for honest science leads him into one of his book’s most interesting detours, a polite but rigorous takedown of Richard Preston’s 1994 best seller “The Hot Zone,” about an outbreak of the Ebola filovirus.