Ebola - David Quammen

This short (111 pages), very readable book was excerpted and augmented from Spillover, Quammen's earlier book about zoonoses - diseases that jump from an animal to man - and possible reasons why they are increasing in frequency.  The decision to create a more focused book on Ebola was stimulated, of course, by the devastating Ebola epidemic that began in Guinea in late 2013.  This book appeared before that epidemic had run its course and was intended to help people around the world understand the nature and course of this disease.

Ebola shows a classic zoonotic pattern of occurrence - emerging suddenly and killing tens or hundreds of people, then as quickly vanishing without a trace, only to re-emerge a few years later.  During the quiescent or latent period, the causative agent resides within a natural host or "reservoir" species - in which it may multiply freely, while causing little disruption or disease.  The devastating eruptions occur when some rare event causes the agent to infects an unusual host, such as man, leading quickly to death.  If the virus or other agent can be passed from human to human, the disease may spread quickly, but in isolated communities, it often reaches a dead-end, because of a lack of new victims to affect.  In this case, the outbreak ceases until another "spillover" or extraordinary infection event occurs.  Frequently, it can be very difficult to identify the reservoir species.

Bats are reservoir species for many zoonotic diseases, including that caused by Marburg virus, which is closely related to Ebola.  Good, though not conclusive, evidence suggests bats are also the reservoir for Ebola.  Quammen's book considers, at some length, why bats may be a favored reservoir for many viral diseases - all quite interesting speculations.  Another important issue considered in the book is why zoonotic outbreaks have become more common; Quammen relates the widely held view among zoonotic researchers that it is because of the increasing disruption of wilderness by the encroachment of human settlements and activities.  These encroachments bring humans into more direct and more frequent contact with many species that have long been spatially segregated.  As this trend continues and intensifies, we may expect zoonotic outbreaks to become more frequent, increasing the likelihood that some of these agents will adapt to human to human transmission, resulting in deadlier epidemics and, perhaps, The Next Big One - a world-wide pandemic such as bubonic plague in the middle ages or the Great Influenza of 1918.

Quammen is a terrific science writer - he digs deeply and understands his subject fully, he presents  the science via a lively narrative focused on the stories of individuals, and his anecdotes are frequently punctuated by a sharp, sometimes mordant wit.