Beasts of the Earth: Animals, Humans, and Disease E. Fuller Torrey and Robert H. Yolken New Brunswick, NJ: Rutgers University Press, 2005. 191 pp. $23.95 (cloth)

Although we have always coinhabited the earth with animals and their microorganisms (often in close proximity because of domestication), zoonotic infections tend to make the headlines today. Beasts of the Earth is therefore timely. Torrey and Yolken present a compendium of infectious diseases set in a historical context. They make the ubiquity of microorganisms as part of the planet's biomass amply clear, and they correctly stress that there is no escaping them. Despite this undeniable fact, are individual instances or outbreaks of zoonotic infection really more common in today's world than they have been in the past? Although the authors promise to provide evidence of the “increasing incidence of animal-associated human diseases,” I think they fail to convince the reader. This could be because the evidence is indeed lacking, barring a few well-known exceptions, such as the likely animal origins of the coronavirus responsible for severe acute respiratory syndrome.

The immense amount of material covered allows the book to be divided into 11 chapters. However, this also frequently results in digression from the book's aim of educating us about zoonotic infections. The authors discuss the history of many infections in which the link to animals is tenuous at best. In the chapter “Humans as Farmers,” they provide a laundry list of microbes that have likely made the jump to humans (without citing references) and include some highly questionable examples, such as sexual transmission as depicted in the Cambridge Illustrated History of Prehistoric Art! On page 50, they begin a long segment on measles and humans, without providing any convincing data on when it developed from an animal disease into a human disease, other than the fact that the virus has homology with rinderpest. Pertussis (discussed on page 41) is dealt with in the same way, and the scientific papers that are quoted are not discussed. Periodically, there are long discussions that involve the romanticization of infectious diseases, such as the 5 pages devoted to the affliction of Shelley, Keats, Poe, Kafka, and other poets and writers by tuberculosis. (Once again, the evidence that Mycobacterium tuberculosis is a bacterium of zoonotic origin appears to be sparse). The chapters are arranged in logical sequence, but the descriptions of infectious diseases in this book would better culminate with chapter 9, in which the authors review severe acute respiratory syndrome and avian influenza, rather than with chapter 10, “The Coming Plagues,” in which many of the animal disease outbreaks reviewed have no predicted relationship to human transmission. According to this book, the emergence of West Nile virus is linked to technology, which is another questionable presumption.

The last chapter, with its promising title, “A Four-Footed View of History,” includes highly speculative descriptions of the fall of civilizations throughout history. The authors mention the variety of infectious diseases that occurred contemporaneously with the flourishing and then fall of these civilizations, but they unearth little evidence that the diseases that they discuss decimated these civilizations.

One could take issue with the book's premise. Perhaps the only thing that has changed in the modern world with regard to zoonotic infections is our ability to travel large distances rapidly, creating the obvious potential for rapid spread of infections that have already traveled from animals to humans. One could, therefore, characterize the sentence on page xii—“The present period of changing animal-human relationships may represent the most profound alteration in this relationship since animals were domesticated ten thousand years ago”—as unnecessarily alarmist.

A drawback of the book is its length. Despite an entertaining style of writing, it is no easy read. Instead, it is a weighty compendium of the authors' exhaustive research on the history and folklore behind animal and some non—animal-related infectious diseases. The bibliography is voluminous and impressive. The reader can glean facts and stories about specific infections most effectively by perusing the index. This makes it an excellent resource for those with a bent for medical history of infectious diseases. I would caution the reader, however, that there are some factual errors. An egregious one, repeated in several places where the disease is discussed, is the statement that the Lyme disease spirochete is transmitted to humans from deer, dogs, and cats.

For the lay person and for the medical or scientific person not versed in infectious diseases, Beasts of the Earth is a good introduction to the daunting challenges our society still faces in the control of infectious diseases.