Bray takes the view that most of the great armies had little to do with the "campaigns of empire." The actual battles were mostly decided by the bugs. He gives a very lengthy (and somewhat repetitive) enumeration of the "great plagues" in history, with some comment on how they affected events. About 211 pages of text, 2 chapters on Influenze, 10 or so pages of "Chapter Notes" and a 15 page bibliography.
The discussion of "current problems" is rather brief (but only compared to the rest of the book). It does present a rather complete picture of "who's the enemies" now - amongst the vermin.
For a "cheap" but reasonably scholarly book it's not a bad resource.