Virus X: Tracking the New Killer Plagues by Frank Ryan, M.D. was first published in 1997 and is 430 pages long, including an appendix of a time line of emerging viruses, notes, and index. If you've been reading virus books like I've been reading virus books, Virus X holds nothing totally new or startling but it does cover the investigations into some of the world's most deadly viral epidemics. For a general interest, Ryan's book is more successful than the last two books, Virus Hunter and Level 4, written by some of the actual doctors in the field. I would have to agree with reviews that say it is better written early on and falls off a bit in the later chapters, but it is still worth reading if you are interested in the subject.
I did read for the first time (that I can remember) that the Marburg virus carrying monkeys were imported to use their liver tissue for the polio vaccine. When examined postmortem, "The livers, in particular, seemed to be shot to pieces." Of course, it could be I noticed this after reading Polio earlier this year. I find the whole idea that monkey tissue has been used to create vaccinations and then injected into people quite disturbing.
Another interesting note: When [the director of the Arbovirus Laboratory at Yale] is sent a virus from a sick traveler who has arrived in New York City, he will not only diagnose the causative virus but tell you in what country, rain forest, subtropical savannah, town, or district the person picked up that strain of virus."