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21046 results in Infectious Disease

Page 237 of 1053

  • 4 - Mortality Decline, Food, and Population Growth: “Standard of Living” and Nutrition

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 48-57

  • Summary

    Despite many limitations of the records showing cause of death and some degree of inaccuracy in the level of cause-specific mortality, the historical data indicate that infectious diseases predominated in the mid-18th century when overall mortality began to decline in England and other parts of Europe. Wrigley and Schofield's analysis of aggregated data from several hundred parishes in England confirmed the findings of earlier studies that mortality in England declined from the mid-18th century. All of the 11 severe mortality crises (30% above trend) occurred before 1750, and the last secondary crisis (20–30% above trend) was in 1762–63. After 1802–3 there were only two years in which mortality was more than 10% above the trend level, in 1846–47 and 1848–49. Figure 4.1 shows the dramatic change in the pattern of annual fluctuations in the crude death rate from the 1740s, and the greatly diminished spikes in annual mortality compared with earlier years. The death rate had generally been lower than the birthrate between 1540 and 1640, and population may have approached the limit that could be fed given the land available and the state of agricultural technology. Although there does not appear to have been an increase in subsistence crises, the increase in demand would have led to increased food prices, exacerbating poverty. From the 1740s, the more rapid population growth put further pressure on food supplies, which had to be increased just to maintain existing levels of average consumption per capita.

    Wrigley and Schofield found that short-term variations in mortality were determined by factors other than food supply and there was little correlation between food supply and mortality over the long run. Using their aggregate data, Fogel found that less than 10% of “crisis mortality” (50–100% above normal) in England between 1541 and 1871 was due to famines, and that the decline in mortality was not due primarily to a reduction in “crisis mortality,” whether caused by famines or not.

  • 1 - Background

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 8-18

  • Summary

    The decline in mortality from the mid-18th century in England and other European countries and the more rapid growth in population that occurred up to the mid-20th century have been the subject of investigation and debate among historians, geographers, economists, demographers, and medical specialists. Attention has focused on the relative importance of different factors, such as treatment, care of the sick, measures to control and prevent infectious diseases, living conditions, “standard of living,” nutrition, and changes in the nature of some diseases. Historians and economists have considered the decline in mortality in the context of agricultural and industrial revolutions leading to improvements in food supplies and expansion of economic activity. Studies of the relationship between food supply and death rates in the period leading up to the mortality transition have indicated that many epidemic diseases caused spikes in mortality that were independent of the effects of famine and poor harvests. In earlier premodern times, changes in the infectious disease environment were linked with great transformations in the way of life of humans, particularly the development of agriculture and adaptation to living in settled communities. Eventually urbanization and large-scale migrations led to new ways of living in very different environments, while trade and changes in population size and density brought exposure to new pathogens, different infectious diseases, and changes in the immunological status of individuals and populations.

    Industrial development and economic growth in Western countries eventually brought many improvements in living conditions, but the concept of “standard of living” is too general to provide a satisfactory explanation for the decline in mortality and increased life expectancy. It reflects the values of particular sections of society, cultures, and historical periods and masks factors specific to the decline in mortality from particular diseases. It is clearly important to distinguish the specific changes in people's lives that contributed to improved survival chances. In the limited sense of people's own economic circumstances and access to food, shelter, and other basic needs, the concept of “standard of living” can generate hypotheses that are testable with reference to specific indicators.

  • 3 - A New Infectious Disease Environment

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 34-47

  • Summary

    Human history has been marked by significant migrations and adaptation to new methods of survival, with consequences for the infectious disease environment, health, longevity, and population. This chapter briefly outlines evolutionary changes in the human condition that led to agriculture, the growth of towns, and exposure to new infections, and considers the infectious disease environment in England when the long-term decline in mortality began. The infectious diseases that contributed to high mortality in the 18th century and the relationship of mortality decline to population growth and food supply are a particular focus. Population increased despite adverse changes in the infectious disease environment, and survival was dependent on immune defenses as well as food supplies. The importance of immunity may be less obvious now that infectious diseases in Western countries are relatively mild and appear to cause few deaths, although immune responses to invasive microorganisms occur continuously throughout life, whether or not there is any discernible acute sickness. In some cases the immune response can become less efficient with age, while other microorganisms, or the immune response to them, can have adverse biophysiological consequences resulting in chronic disease.

    Although microorganisms causing some of the infectious diseases that were major killers in the 17th and 18th century are no longer prevalent in England, other common microorganisms continue to cause childhood epidemic diseases, respiratory infections, and gastrointestinal disorders. Some of these microorganisms are associated with chronic diseases that are now major causes of death. Although environmental, socioeconomic, lifestyle, and behaviorrelated risk factors contribute to the development of these diseases, common microorganisms have been confirmed as causal agents in some chronic diseases, while the involvement of infection in the underlying biophysiological processes in other chronic diseases is strongly suspected. Some chronic disorders have been linked with long-term effects of childhood infections or exposure to microorganisms during adult life, which will be considered in chapters 10–13 along with the issue of the criteria that can be applied to assess causality. At this stage, the possibility of infections being involved in chronic diseases can be borne in mind in considering evolutionary changes that have affected humans, their infectious disease environment, and their immune responses.

  • Preface

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp ix-xii

  • Summary

    Much has been written since the 1970s about the causes of the decline in mortality from infectious diseases, but far less about the emergence of chronic diseases. When Abdel Omran first referred to the change in predominant causes of death as an “epidemiologic transition,” academic studies tended to focus more on issues raised by Thomas McKeown in his influential book The Modern Rise of Population. McKeown's emphasis on improvements in the “standard of living” and nutrition as key determinants of increased life expectancy aroused considerable controversy, while Omran's “theory” of transition remained a basically descriptive framework for analysis of changes in disease and mortality. The epidemiological transition is ongoing globally, and constitutes a fundamental change in the human condition; as such, the phenomenon has both contemporary relevance and historical importance.

    One objective of this book is to review evidence from local, national, and international studies indicating that preventive measures and changes in behavior played a far greater role in mortality decline in England and globally than McKeown or Omran suggested. However, the aim is to go beyond the controversy over the relative importance of “human intervention” and “standard of living” as determinants of increased life expectancy. Assessment of changes in disease and mortality in England since the 18th century and their possible causes is fundamental to an understanding of how contemporary patterns of disease emerged. A very long-term perspective is particularly important as it encompasses the development of a preventive approach to disease in response to devastating epidemics of plague, smallpox, and typhus that laid the foundation for later health interventions. Records of cause-specific mortality available for England, with supporting data from other Western countries, form the basis of this review of the epidemiological transition and illustrate its main features—acute infectious diseases being superseded by chronic diseases as the predominant causes of death, a shift in age at death from childhood to older adult ages, increased life expectancy, and a larger, “aging” population.

    A central theme of the book is the interrelated nature of diseases, particularly the role of microbial infection in chronic diseases, which indicates there is another dimension to epidemiological transition. The original concept oversimplified the process, viewing it as the replacement of one group of distinct diseases (infectious) by another (“degenerative” or “noncommunicable”).

  • 2 - Theoretical Framework, Data, and Study Outline: The Concept of Epidemiological Transition

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 19-33

  • Summary

    The original concept of “epidemiologic transition” outlined by Omran in 1971 focused attention on extremely important changes in cause of death. The infectious diseases that had caused very high mortality among children and adults in the past had been replaced as the main causes of death in industrialized countries by chronic diseases among adults assumed to be noninfectious in origin. There was much criticism of his concept as a “theory,” and it does appear simplistic in the light of subsequent findings about the etiology of chronic diseases. Patterns of disease, mortality, and life expectancy are more complex than a simple shift to predominantly chronic diseases as infectious disease mortality declined. Nevertheless, despite criticisms and revisions of the phases of “epidemiologic transition,” it has provided a framework for comparison of secular trends and profiles of disease in different populations. An objective of this study is to develop a perspective on historical changes in disease and mortality that goes beyond descriptive accounts of different phases of transition, takes into account disease etiology and the interrelationships between diseases, and contributes to an understanding of how contemporary patterns of disease have come about.

    Omran's first formulation of his theory consisted of five propositions, which can be summarized as follows:

  • 1. “Mortality is a fundamental factor in population dynamics.”

  • 2. “A long-term shift occurs in mortality and disease patterns whereby pandemics of infection are gradually displaced by degenerative and man-made diseases as the chief form of morbidity and primary cause of death.”

  • 3. “The most profound changes in health and disease patterns obtain among children and young women.”

  • 4. “The shifts in health and disease patterns that characterise the epidemiologic transition are closely associated with the demographic and socioeconomic transitions that constitute the modernisation complex.”

  • 5. There are three basic models of the “epidemiologic transition” corresponding to the experience of most Western countries, countries such as Japan where the transition was more rapid, and developing countries where the decline in mortality commenced more recently.

  • 6 - Typhus, Typhoid, Cholera, Diarrhea, and Dysentery

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 77-89

  • Summary

    Although smallpox epidemics predominated in the pattern of mortality fluctuations in the 18th century in England and other European countries, many deaths among children and adults were attributed to “fevers.” Hospital statistics and medical writings suggest that typhus was probably a more significant component of “fevers” mortality in England in the 18th century than typhoid. Typhus and typhoid were first distinguished under national registration in 1869, by which time typhus mortality had declined and typhoid accounted for a higher proportion of deaths. Of the 18,390 “fevers” deaths in that year, 47% were attributed to typhoid, 23% to typhus, and 30% to “simple fever.” “Convulsions” was often recorded as the “cause” of death in the first two years of life, although the symptoms are likely to have been due to bacterial infections linked with poor hygiene and fecal contamination of water and food, and with viral diseases such as smallpox that had not displayed the recognized symptoms. Many other deaths involving gastrointestinal disorders among children and adults were probably recorded in the London Bills of Mortality as “griping of the guts,” “bloody flux,” and “surfeit.”

    The vagueness of some cause-of-death categories and increasing recognition of diseases clearly affect the assessment of their contribution to overall mortality decline. Even for the registration period, quantification based on cause-specific death rates is simplistic because of concurrent infections and interrelationships between diseases. Nevertheless, a summary of the simple components of mortality change provides some indication of the relative importance of different categories of disease and symptoms (see appendix C1). Estimates based on the London Bills of Mortality suggest that the death rate declined by 32% between 1751 and 1801. In simple arithmetic terms, the main contributions to each unit of change were “fevers” (-0.25), convulsions/teething (-0.40), consumption (-0.09), and smallpox (-0.08).3 National registration data indicate that the death rate in England and Wales declined by 22% between 1851 and 1901, with contributions to each unit of change from typhus/typhoid fevers (-0.17), cholera, diarrhea and dysentery (-0.12), convulsions/teething (-0.14), consumption (-0.33), and smallpox (-0.05).

  • 9 - Tuberculosis

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 118-130

  • Summary

    Death rates from different acute infectious diseases began to decline at different times in the 18th and 19th centuries, reflecting the relative success of different preventive interventions and other factors. While major killers such as smallpox, typhus, cholera, and typhoid had been nearly eliminated by the end of the 19th century, measles and respiratory disease death rates did not decline. The lack of decline in death rates from respiratory disease in the second half of the 19th century (see chapter 10) contrasts with the decline in death rates from the chronic infectious disease respiratory tuberculosis considered here. This highly visible wasting disease was endemic in London by the 17th century. The death rate from “consumption” recorded in the London Bills of Mortality increased up to the 1740s, leveled off, and then declined after 1800. Because death rates from some other causes declined, “consumption” accounted for an increasing proportion of all deaths, 14% in 1700–49 and 22% in 1750–99. The term “consumption” probably referred to many “wasting” conditions, and Black noted at the time that it was “lax and indefinite” and included many types of emaciation. Deaths from lung diseases other than tuberculosis, such as bronchitis, may have been included, while some deaths involving respiratory conditions were recorded as “asthma.” Even so, in the experience of Black and contemporary physicians, a very large proportion of “consumption” deaths in the 18th century were due to pulmonary phthisis, a term used for respiratory tuberculosis. In the 19th century, tuberculosis became a major public health problem exacerbated by rapid population growth in the towns, and it caused much longterm sickness and death, particularly among adults.

    Under national registration, other nonrespiratory forms of tuberculosis were recorded separately, including infection of lymph nodes in the neck (scrofula) and abdomen (tabes mesenterica), and tubercular meningitis. There could have been some transfer of recording between phthisis and these categories as well as transfers-in from vague categories such as “atrophy,” which may have included some people wasted by tuberculosis.4 There were probably some transfers between phthisis and the respiratory disease category in the early years of national registration, although the decline of 34% in the death rate from phthisis between 1838 and 1850 is likely to reflect some genuine decline in respiratory tuberculosis mortality.

  • 12 - Cancer

  • Alexander Mercer, Independent researcher and the author of Disease, Mortality and Population in Transition: Epidemiological-Demographic Change in England Since the Eighteenth Century as Part of a Global Phenomenon
  • Book:
    Infections, Chronic Disease, and the Epidemiological Transition
    Published by:
    Boydell & Brewer
    Published online:
    14 March 2018
    Print publication:
    30 December 2014, pp 163-180

  • Summary

    Cancer is not exclusively a modern disease, and paleopathological evidence of many of its forms has been found in ancient human remains. Even so, the evidence from thousands of prehistoric and ancient remains, such as fossils, mummies, and skeletons, suggests neoplasms were not common until after the medieval period in Europe. Investigation of Egyptian mummies suggests malignancies were rare, although multiple melanoma cases have been well documented, and also nasopharyngeal carcinoma, which is readily identifiable through damage to the skull. Hippocrates made the distinction between malignant and benign cancers in the fifth century BC. Although malignant cancers are now usually referred to as malignant neoplasms, the term cancer is used here as it has a longer history in the research literature. At the end of the 18th century in England, there were early references to cancer as a form of “tubercle,” and only a few deaths were recorded in the “cancer” category in the London Bills of Mortality. In some cases the wasting may have been difficult to distinguish from the effects of tuberculosis for the purposes of recording cause of death. When national registration began in England and Wales, the term malignant tumors was already in use, although “carcinoma” was not formally distinguished from “genuine crude tubercle” until 1855. Pathologists sought to define the difference between cancer and tuberculosis, which occur in many of the same sites in the body, and the idea of an inverse relationship developed despite both occurring at the same time in a few cases. It is now usual to regard cancers as a group of diseases, differing widely in etiology, frequency of occurrence, and site of manifestation.

    The underlying processes in cancer have long been regarded as linked with the cumulative effects of irritants and carcinogens. Burnet suggested that errors in the repair of DNA could explain associations between carcinogens and particular sites of cancer, such as radiation and skin cancer, cigarette smoking and lung cancer, naphthylamines and bladder cancer, radium salts in paints and bone sarcoma, and many others. The molecular-level process in “environmental cancer” could involve a carcinogenic agent entering cells and causing damage to the DNA, which can be repaired but with an increased risk of informational error and abnormal cells that can replicate out of control.

Page 237 of 1053