Infections, Chronic Disease, and the Epidemiological Transition: A New Perspective by Alexander Mercer (review)

In 1971 Abdul Omran published a paper coining the phrase “Epidemiologic Transition.” The paper was meant to defend the World Health Organization’s program of international family planning and in the process took what everyone knew or thought they knew was happening in the developed world, a shift from the predominance of infectious diseases to chronic diseases, and turned it into a model linking chronic disease to economic development.¹ The theory was largely ignored for nearly two decades but was rediscovered in a big way at the end of the 1980s when the international health community began to discover that low and middle income countries were or might be facing increasing incidence of chronic disease (called non-communicable disease [NCDs] in global health parlance). The theory has been justifiably criticized and modified by numerous writers (including Omran himself, who revised it several times) but it has remained a convenient framework for discussing apparently changing disease patterns in the developing world as well as strategies to confront them. I say “apparently” because both morbidity and mortality statistics have been very poor in many countries so that it is hard to be certain whether some diseases are significantly more numerous or are being noticed more because of better data or because they are now on everyone’s watch list. The number of citations to Omran’s paper has kept rising as NCDs have received more and more attention. (In 2011, a special session of the United Nations was devoted to them.) And there has been a recent spate of works evaluating, developing, or modifying the theory. My personal Endnote library contains fourteen articles or books published in 2014 devoted to the Epidemiologic Transition or the Health Transition, a rival and purportedly more wide-ranging theoretical approach.

The book under review is thus part of a larger scholarly debate. Its originality lies in bringing together scholarship around the epidemiological transition with that around the McKeown Thesis, well known to historians. Correctly pointing out that Omran’s theory lacks any discussion of mechanisms behind shifting disease patterns, the author makes use of the large literature around the McKeown Thesis, as well as a wealth of other studies, to fill this lacuna. This results in a lengthy book that summarizes a huge body of work on changing disease patterns in a way that many readers will find useful. Some of the results will not be especially surprising. To explain the decline of major infectious diseases, the author comes down on the side of those like Simon Szreter who argue that public health reforms and changes in behavior were more significant factors than rising living standards and better nutrition as McKeown argued. The rise of chronic diseases is also explained by the usual factors: decline in infant mortality leading to longer lives, sedentary urban life, etc. But the book’s most original and frequently repeated argument is that many chronic diseases are either directly caused by microorganisms, or are sequelae or long-term consequences of infection(s). This is hardly earth-shattering news to anyone who keeps up with newspaper science columns but no one to my knowledge has marshaled this much evidence to demonstrate the point. Mercer’s view thus calls into question the standard infectious/non-infectious distinction, which dominates so much medical history.² This is fair enough. Multi-morbidities everywhere and the mixed disease regimes found in low-income countries do not fit neatly into any such dichotomy and the same is likely true of Western nations before the mid-twentieth century. It is good to be reminded of this. However what Mercer ignores is that there are historical, institutional, and economic reasons why we make such distinctions. Diseases that mainly affect adults rather than children, that develop slowly and linger for long periods, often requiring expensive long-term care, require different preventive and caring responses than illnesses that spread...