Infectious Disease Epidemiology: Theory and Practice

The study of infectious diseases has contributed much to the development of epidemiological principles and research methods but textbooks about infectious disease epidemiology are surprisingly few and far between. The title ‘Infectious Disease Epidemiology: Theory and Practice’ temptingly promises to fill this niche. Unfortunately, whilst the book is strong on epidemic-ology it is weak on epidemiology. Five sections of this six-part book comprehensively describe the epidemiology of various infectious diseases but only one addresses the theory of infectious disease epidemiology. The book covers the epidemiology of a wide selection of diseases, with an emphasis on new and emerging infections such as HIV and associated opportunistic conditions, Lyme disease and tuberculosis. A great deal of information, much of it only published in journals, is now synthesized for those of us who cannot read the 20 or so articles per day required to keep up with rapid advances in our field. ‘Real-life’ examples used to illustrate epidemiological principles and methods are also welcome. The editors' interest in HIV infection, however, has resulted in an over-reliance of examples from this field, comprising 18 of 26 examples presented in the first four chapters. Together with the absence of chapters on diseases such as measles, polio and leprosy this diminishes the importance of these conditions in terms of current burden of disease and historical contributions to the principles and practice of infectious disease epidemiology. In the chapter on study design the editors wisely advise readers to consult other major textbooks of epidemiology for information. Certainly readers should not rely on this chapter, which has some basic errors and omissions. For example, in a table summarizing study designs, prevalence is given as a measure of association in a cohort study and, in a case-control study, relative risk is presented as the primary measure of association. The accompanying text explaining relative risk states that, ‘… if the difference is large (i.e. statistically significant) the exposure is a risk factor for the disease’, a statement which will send shudders down any decent epidemiologist's spine. The importance of bias in case-control studies is discussed, although recall and response bias are used synonymously, and controlling for confounding receives no mention in this chapter. Randomized controlled trials are given short shrift, with design issues in the avoidance of bias (randomization, blinding and handling of dropouts in analysis) sacrificed to a discussion of the ethics of antiretroviral trials in developing countries. Finally, in a modern epidemiology textbook, the lack of any mention of the role of systematic reviews and meta-analysis is surprising. I enjoyed the presentation of John Snow's investigations on the distribution of cholera cases as the first geographical information system and this chapter provided an excellent overview of the role of these methods with a range of interesting examples. Chapters on mathematical modelling, vaccine epidemiology, sexually transmitted diseases and Lyme disease were also accessible and readable. Editorial carelessness was a constant irritation, with misspelt names and misprints, albeit sometimes amusing, as in ‘oral dehydration therapy’. This book brings together an impressive array of subject matter but it is not the last word on infectious disease epidemiology. The choice of disease examples presumably reflects the interests of Johns Hopkins University researchers but it also makes the book rather parochial and the almost exclusive citation of practice in the US in chapters such as that on surveillance and outbreak epidemiology will be frustrating to an international readership.