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The most important function of public health in its broadest sense is to seek an optimal harmony between groups of people in society and their environment. This goal can be achieved in three ways: (a) by methods to improve host resistance of populations to environmental hazards; (b) by effective plans to improve the safety of the environment; and (c) by improving health-care systems designed to increase the likelihood, efficiency, and effectiveness of the first two goals. With respect to infectious diseases there are special elements within each of the three categories (Table 8-1). One might then view communicable diseases as an imbalance in the relationship of people and their environment which favors microbial dominance in populations.


It is argued that improved host resistance is the purview of clinical medicine and that both environmental safety and public health systems are public health efforts. However, improved resistance in populations cannot be divorced from necessary educational and effective health delivery systems. For that reason it may be considered an essential component of public health. In this schema of public health, the infectious agent is considered not as a separate focus but as one important component of the environment. This organization is designed to integrate the schema with a concept of health, and of public health in particular. The implication is that the organism is a necessary but not sufficient cause of ill health; it is only one of many risk factors. Moreover, humans constantly encounter myriads of potential microbial pathogens, and removing all such organisms is untenable. It seems more fruitful to develop effective barriers between humans and problematic environmental microbes or at the very least to create pathways for peaceful coexistence. In addition, to many authors it has seemed that public health has focused excessively on environmental controls and too little on the health-care system. Yet all of these categories are interrelated: a change in any aspect of the three areas perturbs the entire system and has a direct effect on public health.

With respect to improved host resistance, McKeown1 has argued that improved nutrition, personal hygiene, and public sanitation have more to do with the control of infectious diseases than vaccines and health care. There is no question, however, that vaccines and new antibiotics have greatly reduced morbidity and mortality from infectious diseases.2 For example, with respect to smallpox, the vaccine—in concert ...

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