IGIENE. — Hygiene (ὕγλεια = health) may be defined as the science and practice of health. Its fundamental aim is the prolongation of human life through the physical and psychological well-being of the individual and of the community of which he is a part; this end it seeks to achieve through the conception, elaboration, and subsequent application of methods of its own, suited to remove completely, or at least to neutralize, harmful environmental factors, or those inherent in the various individual organic constitutions or in the structure of the social body.
From a broad point of view, a distinction may be made between scientific hygiene and practical hygiene. The former investigates the reasons for the measures to be applied according to clearly defined theoretical principles; it constitutes a major branch of medical knowledge, which developed particularly and markedly as a result of the fundamental microbiological discoveries and epidemiological observations of the last century. The latter draws, instead, from centuries of empirical experience and from the data of modern experimentation and observation the rules for the technical implementation of the postulates enunciated by scientific hygiene; unlike the latter, it has its normative origins in the most ancient legislation, and in this respect it has within itself an educational, civic, and moral purpose.
From hygiene concerning the individual (individual hygiene), which historically constituted the beginning of a complex of empirical observations that in remote times imposed themselves upon the human mind as concepts useful for preserving the physical life of the individual himself, there developed a hygiene concerning the demographic community as a whole (public hygiene), and its evolution always proceeded in direct proportion to the civilization of the respective people.
By the very nature of its tasks, hygiene must range over the domain of numerous disciplines, which supply it with the knowledge on which it elaborates and establishes its own methods of research and practical application. It draws its material from meteorology, climatology, geology, hydrology, the various fields of physiology and pathology, as well as from the sociological disciplines. Air, water, soil, clothing, nutrition, urban and rural construction, the struggle against infectious diseases and those known as “social” diseases (tuberculosis, malaria, diabetes, rheumatism, etc.), welfare organizations for maternity, childhood, old age, the physically and psychologically disabled, workers, etc., the hygienic improvement of the individual and the species, health legislation: these are the principal objects of hygiene. It is truly an encyclopedic task which, owing to the needs of modern times, has been divided into specialized branches (food hygiene, industrial, hospital, military, naval, social-welfare, urban, rural, building hygiene, etc.), each developing according to its respective theoretical and practical orientations, but all working together fruitfully and tending toward the physical and psychological well-being of the individual and the community.
The development of hygiene has always proceeded parallel to intellectual education: to the education of the social community, in the sense that it should possess an exact evaluation of the importance to be attributed to the physical and mental health of its members, and to the education of the individual as a citizen within the State; the latter, in turn, becomes a legislative and therefore normative and imperative factor, codifying the fundamental concept that hygiene, in the broadest sense of the term, must be regarded as true preventive medicine both for the individual himself and for the demographic group.
The degree of social development of a civilization is measured by the totality of the hygienic measures that it imposes legislatively, implements, and finally disseminates among the population for an eminently educational and practical purpose.
Empirical notions and experiences of daily life constituted, at the dawn of history, during the period of the great migrations, the first rudiments of individual hygiene; and when populations, abandoning nomadism, gathered in permanent settlements, the need arose to provide normative measures which, by limiting the individual’s freedom in the face of the needs of the community, would defend public health from the dangers resulting from agglomeration. The codification of those norms among the first civilizations (Chinese, Japanese, Assyro-Babylonian, Egyptian, Indian, Hebrew) was accomplished with a profound sense of nature, and from the empirical medicine of those periods, essentially religious and priestly in character, there derived the practices of bathing, massage, gymnastics, and diet; meanwhile, hygienic thought evolved (particularly among the Jewish people), and it was destined to assume the task of providing for the physical and psychological health not only of the individual but also, and to a much greater extent, of the demographic aggregate: in a word, hygiene became the fundamental cornerstone of a political program.
Throughout the course of the historical centuries, the influence of social events has always exercised a profound effect on the evolution of the hygienic idea, and this has marked, over the passage of time, periods of admirable ascent alternating with periods of decline, which in certain calamitous eras (famines, wars, pestilences) went so far as to annihilate every more elementary hygienic custom.
Thus the Greek world may be outlined as an incomparable master of hygiene, the first to have made the physical education of youth a genuine State program, seeking to achieve, through individual education, the most perfect eurythmic physical and mental harmony within the community. Dietetics rose in Greece to the dignity of a hygienic science, and many of the Hippocratic concepts that anticipated the modern contagionist doctrine informed an entire legislation from which there emerged a clear program of public health: the cleaning of streets, provisions for drinking water, control of foodstuffs, regulation of markets, mortuary policing, baths, gymnasia, private and public construction, etc.; this clearly demonstrates that the development of hygiene proceeds parallel to the education of the intellect.
The same may be inferred from the Roman world, with its grandly simple technique of aqueducts, sewers, baths, and the reclamation of marshy lands, with its building works in general and its codified organization for the medical assistance of the population.
Through the flow of the centuries, from the Greco-Roman world one descends to the early Middle Ages, its obscure heir, yet one that bore within itself the germs of the Renaissance and, despite the decline of hygienic practices, witnessed the first hospital foundations of the Byzantine East and the development of the monastic Orders devoted to assisting the sick; while the school of Salerno transmitted medical-hygienic thought in its purest form during a period extremely difficult for the scientific tradition; while epidemics, which raged throughout the then-known world and had already given the Church occasion to concern itself with the health of populations (v. sotto), brought about, particularly in the fourteenth and fifteenth centuries, among the merchant Republics, a rapid hygienic revival and advance, embodied in the elaboration of prophylactic health legislation, which would later serve as a clear model for similar subsequent legislation. The first treatises on individual hygiene then appeared (Taddeo Alderotti of Florence, Aldobrandino da Siena, Ugo Benzi), in which, together with the concept of personal individuality, there also revived the consciousness of self-defense as a member of the social body.
The subsequent prosperity of industry and commerce in the Italian Communes of the Renaissance, which saw their settled populations increase rapidly, led to the establishment of institutions of social assistance and to the promulgation of compulsory regulations that may today be regarded as the germ of future protective labor legislation. Memorable names in the history of hygiene arose with the Renaissance, and their constellation continued chronologically down to our own day: Fracastoro and Ingrassia in the sixteenth century: the former revived the principle of « contagium animatum sed vivum », while the latter was an indefatigable organizer in the struggle against the Sicilian plague; in the seventeenth and eighteenth centuries, Vallisnieri, who likewise championed the contagionist theory; Ramazzini, the true initiator of modern social medicine, who established the principles of hygiene and of the clinical study of occupational diseases; Lancisi, whose inspired observations contain the fundamental precepts that two centuries later would form the cornerstones of the struggle against malaria; Monsignor Gastaldi, special health commissioner of the Papal government, an ingenious and prolific legislator of the anti-plague campaign in seventeenth-century Rome; Antonio Cocchi and Domenico Cotugno, on whose initiative protective measures against phthisis were promulgated in Tuscany; Giovanni Pietro Frank, who, toward the end of the eighteenth century, set forth in a classic treatise, gathering them into a coordinated system, the most important doctrines of public hygiene, regulated its measures, and affirmed public health as their supreme foundation.
But an even more rapid advance in hygiene began in England as a result of the cholera epidemic of 1830. That nation saw its maritime routes rendered unsafe by contagion, and consequently its most important factor of economic life threatened. Hence a series of elaborate protective laws for prophylactic purposes, concerning ships and ports of disembarkation. Likewise, the urbanization of the rural population in the great industrial and commercial cities of England made that nation aware of the need to regulate the hygienic problems arising from the concentration of urban centers: hence a large series of « health acts », constituting an important record of an unparalleled evolution in the domain of public and private hygiene.
Meanwhile, a systematic organization of health administration was also being established in Germany; there, as in France and Italy, studies and investigations followed one another rapidly. Beginning with Jenner’s practical successes in smallpox vaccination, and with the discoveries of Agostino Bassi (concerning muscardine in silkworms), Pasteur, Lister, and so many other distinguished men, they would lead to the present state of the struggle against infectious diseases. At the same time, all the other branches of hygiene would develop, aided by modern technology, forming a « corpus » of knowledge and applications directed toward the social and economic well-being of nations.
Hygiene, following the progress of civilization among peoples, like every other manifestation of human activity, has increasingly instilled in humanity the conviction of the great benefits it provides. Today this activity proceeds in correlation with the results of scientific investigation and tends, in an increasingly rational manner, to secure and preserve for individuals and communities the best conditions of life. It has taken its place among the biological and social sciences, and its importance is confirmed every day by the advantages it brings to civilized peoples: an increase in average human life expectancy, a reduction in mortality and morbidity rates, increased productive capacity, and so forth. Since it has the duty of guaranteeing every individual in the community complete health protection, in order to compensate for the inadequacy of the means of individual self-defense, hygiene has become a function of the State.