How the Cows Turned Mad

  • Maxime Schwartz
University of California Press, 2003 238 pp. hardcover, $24.95 ISBN 0520235312 | ISBN: 0-520-23531-2

Any good drama has a number of key ingredients: strong characters, intrigue, unexpected plot twists and high stakes. The prion story has these aplenty and, as recounted by Maxime Schwartz, makes a fascinating and engrossing read. This is a thoroughly researched book that is written in an authoritative—but always accessible—style, as one might expect from a former head of the Institut Pasteur. The author instructively and expertly guides us through the complexities of scientific detective work and discovery, successfully interweaving the occasionally disparate threads of a plot that has played out for well over 200 years. It is an excellent introduction to the history of prion diseases, but it may not recite all of the key experiments—or explain the current controversies facing the prion protein-only hypothesis—in sufficient detail to satiate the prion devotee.

We begin our journey at a time in the early nineteenth century when scientific practitioners of the day attributed what we now know to be scrapie prion disease in sheep to the sexual frustration of overly amorous rams. As the pages turn, however, we observe how successive generations of scientific investigators slowly assembled the pieces of a new and deadly puzzle. Educationally, each advance in understanding is placed within the context of the scientific knowledge and techniques of the day. Occasionally the trail peters out, only to be picked up by another investigator in another country, decades later. At several junctions, the author reminds us how the echoes of history can manifest in our modern lives. For example, the spread of anthrax infection in the France of the 1880s was perpetuated by fertilizers prepared from the waste of infected animals. These events are remarkably reminiscent of the role of animal feed in the dissemination of bovine spongiform encephalopathy (BSE) prions in cattle a century later.

As we move into the modern era, Schwartz describes how investigators demonstrated that these strange encephalopathies were transmissible, first in sheep, and then across the species barrier from sheep into goats (which revealed the existence of distinct scrapie prion strains) and from goats into mice. The infection of mice was a significant step forward, dramatically accelerating the pace of laboratory research. About this time, it also became clear that the infectious agent, whatever it was, was resistant to formaldehyde treatment, a property not shared by any known virus. This was an important clue, hinting that the nature of the infectious agent was unique. As the story unfolds, Schwartz discusses most of the major advances in prion biology until the recent past, including the formulation of the protein-only hypothesis. However, the author's analyses of what are often fairly complex scientific issues can at times be too superficial, brushing any loose ends under the carpet.

The public health and economic fallout from the BSE epidemic, and the accumulating evidence that variant Creutzfeldt-Jakob disease resulted from exposure to BSE prions, has been huge, particularly in Europe. It is perhaps a little disappointing that Schwartz does not dedicate more of the book to the many lessons that can be learned about the political (mis)handling of the crisis, particularly in the UK.

Although prions may not make the front pages of our newspapers as frequently as they have in the past, “The Disease,” as Schwartz refers to it, has a habit of reappearing unexpectedly, and often with insidious consequences. The recent furor in Canada, where a single BSE-infected animal was identified, shows that prion diseases remain a significant menace against which we must be constantly vigilant. What the book aptly illustrates is that the gathering of scientific knowledge is probably our best hope for containing the prion diseases and for tackling the future problems that will assuredly come our way.