In the last half of the twentieth century, public health continued to expand its established roles. However, new forces were at work to further broaden its purview. Among these were the aging of the populations in industrialized regions, recognition of the importance of behavioral factors in determining the health of populations, exacerbation of social inequalities in health, increasing violence (at the domestic level as well as at the civil and international level), and globalization.
As infant and child mortality declined in the industrialized countries, life expectancy and the proportions of the elderly in populations increased. Consequently, diseases such as heart disease and cancer became more important. After World War II, epidemiological research concentrated on identifying risk factors for these and other chronic diseases. A prominent role for behavioral factors was readily demonstrated. Particularly, cigarette smoking was identified as a major etiological factor for heart disease and for several cancers, particularly lung cancer. Other behavioral factors, such as diet, exercise, and obesity, were found to be causally associated with several other diseases. Ameliorating adverse behavioral risk factors has become a major function of public health agencies.
Since the mid–nineteenth century, the relationship between socioeconomic status and health has been widely recognized. However, in the late twentieth century epidemiological research has pointed out additional differences in health status between gender, ethnic, and occupational groups. Such inequalities appear to be increasing and are being recognized as a major challenge for modern public health.
Domestic violence, gang warfare, ethnic conflicts and genocide, and civil wars and wars between nations have resulted in substantial mortality and a vast disruption of societies. In some countries, including the United States, homicide has become a major cause of death among those under twenty years of age. Around the world, many millions of displaced persons live in enormous refugee camps with minimum medical and public health facilities. Clearly, the health effects of war and violence demand to be addressed.
Increased globalization and technological advances have resulted in worldwide economic, political, and social interdependence. However, recognition of the interdependence of regions and nations with respect to health and disease was institutionalized in 1902, when the Pan American Health Organization was established to coordinate communicable disease surveillance and quarantine in the western hemisphere. By the end of the century, the major global public health problems included the manifold consequences of atmospheric warming; pollution of the oceans and fresh waters of the world and the depletion of fisheries; the rapid growth of the world'spopulation; the emergence of new infectious diseases, including HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome); and the increased production and use of addictive drugs. These are daunting challenges for the World Health Organization and other international agencies.
Nevertheless, in 1977, public health registered its greatest historical feat. In that year, the eradication of one of the human species' most dreaded and lethal diseases, smallpox, was completed. The last case occurred in 1977 in the East African nation of Somalia and the eradication was certified by a Commission of the World Health Organization in 1979.
Although the Sanitary movement of the nineteenth century and the development of bacteriology substantially lowered death rates from enteric diseases, other serious health problems still existed. One was the appalling and ubiquitous rate of infant mortality. First in Europe, then in Britain and in the United States, maternal and child health programs were initiated with an emphasis on nutrition, medical care, and, eventually, health inspection in schools. Muckraking journalists exposed disgraceful conditions in the food processing industry, leading to the imposition of widespread governmental regulation. High rates of occupational diseases and industrial injuries led to programs for industrial hygiene and occupational health. Mental health was identified as a public health issue, and specific nutritional deficiencies were recognized as risk factors for a spectrum of diseases. Furthermore, pioneering studies of pellagra, a vitamin-deficiency disease, by Joseph Goldberger and Edgar Sydenstricker, revealed the complex environmental, social, and biological interactions responsible for the occurrence and distribution of such diseases.
The growing scope and complexity of public health concerns led to the establishment of academic programs to expand research and train relevant technical personnel. At the University of London, a school of Tropical Medicine was established in 1905 and, in the United States, a School for Health Officers was created jointly by Harvard University and the Massachusetts Institute of Technology in 1913. The first school of public health in the United States was established in 1916 at Johns Hopkins University with a grant of $267,000 from the Rockefeller Foundation. Subsequently, the Foundation supported the establishment of schools of public health at Harvard, the University of Michigan, the University of London, and in several other locations around the world.
By midcentury, the basic activities of public health had been widely recognized in the industrialized world. These components were: communicable diseases control, environmental sanitation, maternal and child health services, health education, occupational and industrial hygiene, nutrition, and, in most developed countries, the provision of medical care. In the United States, only medical care for the indigent, the aged, and for certain diseases (e.g., tuberculosis) were considered within the purview of public health.
An important role has also been played by the philanthropic foundations and voluntary health organizations. For example, the Rockefeller Foundation provided the impetus and financial resources to initiate public health professional education and the Milbank Fund pioneered the establishment of local health departments in New York State by carrying out demonstration projects around the state. Other important foundations include the Julius Rosenwald Fund, the Russell Sage Foundation, and the Twentieth Century Fund.
Voluntary health agencies evolved in the late nineteenth and early twentieth centuries in Europe and North America, growing out of the failure of public health organizations to fully apply knowledge created by the new biomedical sciences, and by the continuing deplorable condition of the urban poor. Organizations like the Pennsylvania Society for the Prevention of Tuberculosis (which evolved into the American Lung Association) took on the task of public education, case counseling, financial aid, and advocacy for relevant legislative action, while organizations like the Henry Street Settlement in New York City and Hull House in Chicago provided social and medical services in slum neighborhoods. By the mid–twentieth century there were more than 20,000 voluntary health agencies in the United States alone.
With the discoveries of pathogenic bacteria by Louis Pasteur in France and Robert Koch in Germany in the late 1870s and early 1880s, the science of microbiology was born. Consequent developments in immunology and parasitology provided epidemiologists and other public health workers with the tools to study and understand epidemic phenomena. Sanitation could become sciencebased and the development of vaccines promised the prevention of many infectious diseases. A new era of rational public health was established.
COLONIALISM AND PUBLIC HEALTH
From the sixteenth through the nineteenth century, European countries had competitively colonized most of the tropical world. The contagious diseases they brought with them frequently ravaged indigenous populations. Conversely, the prevalent diseases of colonized areas threatened the invaders. Colonial sanitation and medical care was originally designed to serve the interests of the colonists. However, after the establishment of biomedical science, there was enhanced incentive to control the major tropical diseases that were interfering with the economic development of the colonies (e.g., malaria and yellow fever). In India, in 1897, Ronald Ross identified the mosquito vector of malaria, leading to the partial control of the world's most prevalent endemic disease and vastly increasing the agricultural output and, incidentally, the population of the subcontinent. In Cuba, in 1900, Walter Reed and his colleagues identified the mosquito vector of yellow fever. Subsequently, William C. Gorgas, by extensive application of larvicide, eradicated the disease from Cuba and controlled it, along with malaria, in Panama. This action permitted the construction of the canal that had previously been abandoned because of the devastating impact of these diseases.
When these colonies gained independence, mostly during the twentieth century, much of the public health infrastructures put in place by the colonial powers were transferred intact to the new nations. The ability to effectively utilize these resources has varied considerably, contributing to the development of international public health organizations.
The Enlightenment (the period from 1750 until the mid–nineteenth century) was characterized by unprecedented industrial, social, and political developments, and the resulting societal impacts were immense, culminating in the Industrial Revolution. It was in Germany that the first major contribution of the period to public health occurred. Between 1779 and 1816, Johann Peter Frank, a leading clinician, medical educator, and hospital administrator, published a six-volume treatise, System of a Complete Medical Policy, in which he proposed a sweeping scheme of governmental regulations and programs to protect the population against disease and to promote health. His proposals covered the entire life span from birth to death. The actions that he advocated ranged from measures of personal hygiene and medical care to environmental regulation and social engineering.
Meanwhile, in England, Jeremy Bentham (1748–1832) was enunciating a similar humanitarian social philosophy and consequent political reform. InIntroduction to the Principles of Morals and Legislation (1789), Bentham argued, among other ideas, that society should be organized for the greatest benefit for the greatest number (Utilitarianism). In hisConstitutional Code (1830), Bentham proposed radical new legislation dealing with such issues as prison reform, the establishment of aministry of health, birth control, and a variety of sanitary measures.
Implementing these concepts in the mid–nineteenth century fell to Bentham's disciples, particularly Edwin Chadwick. Chadwick had been secretary of England's Poor Law Commission, established in 1834 to effectuate the New Poor Law, and was aware of the pervading interaction of disease and poverty. Thus, when the Commission undertook a special study in 1839 of the prevalence and causation of preventable diseases, particularly of the working poor, Chadwick took the lead. The resulting publication, General Report on the Sanitary Condition of the Labouring Population of Great Britain (1842), is considered one of the most important documents of modern public health.
Chadwick documented the status of housing of the working population, the lack of sewerage and adequate supplies of water, the unhygienic circumstances of places of work, the life expectancy of various social classes, the economic impact of unsanitary conditions, and the evidence for the beneficial health effects of preventive measures. As a result, sewerage, potable and plentiful water supplies, refuse disposal, proper ventilation of residences and places of work, supervision of public works by qualified professionals, and legislative authorization of measures to obtain these results were put forward.
Chadwick's report was widely circulated and carefully considered. In the United States, it stimulated a similar survey based on more sophisticated survey methods and with more comprehensive recommendations. The Report of a General Plan for the Promotion of Public and Personal Health (1850), authored by the organizer and first president of the American Statistical Association, Lemuel Shattuck, put forward fifty recommendations (many still worthy of implementation but not yet realized) and a model state public health law. Although both of these reports impacted national and local legislation, their more enduring effect was to define the purview and establish the organizational framework of the field of public health in the late nineteenth and early twentieth centuries.
It was during the Renaissance, a period of great commercial, scientific, cultural, and political development, that the bubonic plague, or "Black Death," swept over Europe and the Near East killing an estimated one-fourth to one-third of the population between 1347 and 1351. For the following two-and-a-half centuries, periodic epidemics of plague decimated these populations.
There were other epidemics as well. In the sixteenth century two new diseases, syphilis and the "English sweat," an ill-defined condition, possibly a form of influenza, were widespread in Europe. The ever-present smallpox was transported to the Americas, where it decimated the native populations. These catastrophic events precipitated the three most important contributions to public health of the Renaissance: the organization of boards of health, the promulgation of a theory of contagion, and the introduction of health statistics.
With the recurrence of plague epidemics, it finally became apparent in the cities of northern Italy that the ad hoc arrangements of the city councils were inadequate to deal with these episodes. By the middle of the fifteenth century, the major cities of the region had established permanent boards of health who were responsible for determining the existence of plague, establishing quarantine, issuing health passes, arranging for the burial of plague victims and the fumigation of their residences, and the management of lazarettos (houses and institutions of quarantine). The boards maintained close relations with the local physicians who provided medical care and prophylactic advice. As time passed, the boards expanded their purview to the control of markets, sewage systems, water supplies, cemeteries, and the cleanliness of streets; and they took jurisdiction over the professional activities of physicians and surgeons, the preparation and sale of drugs, and the activities of beggars and prostitutes. With the disappearance of plague at the end of the seventeenth century, the boards of health of northern Italy withered away. Nevertheless, they provided a model for nineteenth-century organization of public health activities.
Although vague theories of the contagious nature of certain diseases had existed since ancient times, it was the Italian physician and scholar, Girolamo Fracastoro (who had written an epochal description of syphilis, giving the disease its name), who, in 1546, published On Contagions and the Cure of Contagious Diseases. Fracastoro proposed that many diseases are caused by transmissible, self-propagating, disease-specific agents called "germs" (seminaria), which propagate themselves in tissues of the infected host and cause disease by setting up chemical processes. Most importantly, Fracastoro proposed that germs are spread by direct contact (person to person), by contact with fomites (inanimate objects), and by distant transmission.
By early in the fifteenth century, the Italian boards of health instituted a system of death registration, first for contagious diseases and subsequently for all diseases. The resulting bills of mortality have provided continuous data on mortality in Italy from the Renaissance to the present. In seventeenth-century London, analysis of bills of mortality by John Graunt in his epochal treatise Natural and Political Observations … Made Upon the Bills of Mortality (1662) laid the basis for the modern use of statistics for the planning and evaluation of public health activities.
During the Dark Ages (about 500–1000 C.E.), Western Europe experienced a period of social and political disintegration. Large cities disappeared, replaced by small villages surrounding the castles of feudal chiefs. The only unifying force was Christianity, and it was in the monasteries that the learning and culture of the Greco-Roman world was preserved. Furthermore, in many of these institutions, piped water supplies, sanitary sewers, privies, bathing facilities, and heating and ventilation were provided. In addition, some monasteries constructed hospices to shelter travelers and sick persons, though the medical care provided in them was primitive at best. In Eastern Europe and Asia Minor, however, feudalism did not exist, and medicine advanced and became centered in major secular hospitals established in Byzantium, Baghdad, and Cairo.
The most important disease of the period was leprosy, manifested by a continent-wide epidemic beginning in the sixth century and lasting through the fifteenth. Lepers were excluded from communities and segregated. Elaborate rules and regulations were set up to diagnose the disease and isolate cases. Leper houses (leprosaria) were established, and it is estimated that by the end of the twelfth century there were 19,000 such houses throughout Europe. Isolation of cases of leprosy in medieval times represents the earliest application of a public health practice still in use.
By about 1000 C.E., the stagnation in the West gave way to change. Feudal fiefdoms were being consolidated into nation states, cities and towns were growing, education was beginning to be secularized, and the Crusades were bringing increased interaction between the Islamic East and the Christian West. As these changes occurred, the responsibility for communal functions was transferred from the feudal lords and ecclesiastic authorities to lay councils presided over by a hierarchy of hereditary or appointed officials. Public health activities, such as overseeing the water supply and sewerage, street cleaning, and supervision of the markets, fell under the jurisdiction of the councils.
The establishment, in Salerno, Italy, of the first organized medical school was indicative of the changes occurring in Western Europe. This institution, founded in the eleventh or twelfth century, was particularly remarkable for two reasons: It was a lay organization, independent of the church, and it welcomed students of any race or creed. Its faculty included women, who apparently dealt with obstetric issues, and the renowned peripatetic scholar, Constantine the African (1020–1087), who translated many important Arabic works into Latin. Its most prominent literary product was the Regimen Sanitatis Salernitanum, a lengthy poem, prescribing healthy habits from birth to old age. Drawing on the whole corpus of Greco-Roman and Arabian medical writings the Regimenemphasized personal hygiene, diet, exercise, and temperance. It was the first "health guide" for the masses.
Elements of Winslow's concept of public health can be found in the earliest evidence of communal living. Paleopathology, the study of fossils and other artifacts, reveals that early Homo sapiens, who were hunter-gatherers, suffered from essentially the same diseases that afflict people today.
In remote parts of the world—in the Amazon, Indonesia, Australia, and Africa—isolated communities exist that anthropologists believe follow lifestyles typical of prehistoric populations. These peoples share the belief that diseases are caused by malevolent supernatural forces. To diagnose, treat, and, in some cases, prevent the spread of these malevolent forces, all primitive societies have created a class of "shamans"—persons specially trained to intervene on the spiritual and physical level. Thus, the most primitive societies provide an "organized" approach to the recognition and management of disease.
The social structure of the earliest primitive villages was probably not very different from that of the earlier hunter-gatherer tribes, and physical amenities were, no doubt, similarly unchanged. However, the establishment of cities brought about major developments. Archaeologists have found that all the great cities of antiquity in Asia, Europe, Africa, and South America had municipal water supplies and sewerage systems. The culmination of ancient sanitary engineering was accomplished in Rome, where aqueducts supplied the city with water in amounts comparable to many modern municipal systems and sewers and drains carried away the wastewater. Part of the great central drain of ancient Rome, the Cloaca Maxima, still serves as part of the sewerage of the modern city.
It was the exigencies of urban living, not considerations of health and disease, that necessitated sanitary engineering. Supernatural explanations of disease did not evoke or require an environmental origin for disease. However, in the fifth and fourth centuries B.C.E., in Greece, an empirical explanation of disease was proposed by the physician Hippocrates and his followers who described diseases in objective terms, and rejected supernatural causes. In his book On Airs, Waters, Places, the relations of disease to physical, social, and behavioral settings are presented for the first time. This book served as a guide for decisions regarding the location of urban sites in the Greco-Roman world, and may be considered the first rational guide to the establishment of a science-based public health.
Public health was defined by the American public health leader, Charles-Edward A. Winslow, in 1920 as, "the science and art of preventing disease, prolonging life, and promoting physical health and efficiency through organized community efforts for the sanitation of the environment, the control of community infections, the education of the individual in principles of personal hygiene, the organization of medical and nursing service for the early diagnosis and preventive treatment of disease, and the development of the social machinery which will ensure to every individual in the community a standard of living adequate for the maintenance of health." Although a modern nosologist would add mentalto physical aspects of health, Winslow's definition has not been superseded. It provided the basis for the World Health Organization's definition of health: "A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity" (1948).