Emerging Infections is the first of a new series entitled Biomedical Research Reports created to address topics of broad clinical and social import. This book is a collection of in-depth reports by leading researchers on major emerging infections. Its focus is current research related to pathogenesis, treatment, and prevention, but it also addresses the basis for issues of concern to public health and avenues to prevention. The reports, written for biomedical researchers and interested clinicians, are comprehensive and well referenced.
Each chapter stands alone in its discussion of a particular disease and its causative organism. The first chapter is an engrossing introduction by the editor of the book, Richard Krause. The reader benefits from his 47 years in infectious-disease research and his insightful perspective. We learn of the introduction of sexually transmitted diseases into Hawaii by Captain Cook's crew in 1778. Since the Hawaiians had no immunity to these diseases and there was no cultural stigma associated with sexual activity, venereal disease spread rampantly in one year, only to be followed by epidemics of tuberculosis, measles, and typhoid. These events caused the population to shrink from 300,000 to 30,000 in one generation. The Hawaiian example of the lack of immunity against organisms introduced by travelers recalls the spread of the human immunodeficiency virus (HIV) in Africa along truck routes.
The chapters that follow cover tuberculosis, cholera, Escherichia coli O157:H7 infections, group A streptococcal diseases, influenza, dengue fever, Lyme disease, HIV infection, hantaviral diseases, Ebola virus infections, malaria, transmissible spongiform encephalopathies, and new parasitic protozoa and arthropod-borne pathogens. Discussions of antibiotic resistance in bacteria and analytic theory of epidemics merit separate chapters. The excellent chapter on the analytic theory of disease takes the willing reader through increasingly complex mathematical models of disease transmission that use findings from studies of disease transmission and pathogenesis. In the process, principles of disease transmission are presented in rich detail, providing a foundation for the chapters to come. Within-host immunity, herd immunity, heterogeneity in transmission, and the evolution of resistance are among the various topics discussed. These themes recur throughout the book as they relate to the specific diseases. One sees how an analytic model can be used to explore the complex interplay of biologic factors or how to use epidemiologic data to design programs of disease control.
The chapter on Ebola virus contains the unnerving statement that we do not know where the organism came from or where it is going. In the chapter on arthropod-borne pathogens, the author stresses the obvious boon of global warming to arthropods. The inclusion of these chapters is testimony to the newness of some of the truly emerging infections, like that caused by Ebola virus, in contrast to other infections that might properly be called "reemerging," such as tuberculosis or group A streptococcal infection. These chapters, though brief, seem designed to appeal to the research community and funding sources, with their agendas.
Several authors stress the worrisome consequences of the worldwide movement of populations to large urban centers. In 1900, 5 percent of the world's population lived in cities, but by 2025, 61 percent will reside in cities. Although transmission dynamics clearly differ from organism to organism, humans can bring malaria, Lyme disease, and HIV and Ebola virus infections with them to new locations, where the size of the population can markedly increase the potential for the spread of disease. Studies in 1846 of the introduction of measles in the Faeroe Islands of Denmark demonstrated that a population of 500,000 was required to support continuous transmission. Throughout the book, classic studies of past epidemics are recounted to provide a context for assessments of the danger of diseases that are still new and whose risk to humans is unknown.
A recurring theme of many chapters is that infections reemerge in areas where control measures transiently succeed in reducing the incidence of disease. Programs of eradication can lead to a decrease in herd immunity over time. When the program is withdrawn, as often happens with changes in governments or social upheaval, the disease can recur at a higher frequency and with more severe consequences in the unprotected population. Epidemics of malaria in parts of Africa and diphtheria in Russia are recent cases in point.
This book presents the challenges posed by emerging infections with breadth and an informed historical perspective. Emerging Infections is a refreshing and stimulating book.
Reviewed by Ellie E. Schoenbaum, M.D.
