A Textbook of Public Health Dentistry CM Marya
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1Public Health2

Changing Concepts of Health and Prevention of DiseaseChapter 1

CM Marya
Health is defined in the World Health Organization's Constitution as “a state of complete physical, social and mental well-being, and not merely the absence of disease or infirmity.
Thus health “is a positive concept emphasizing social and personal resources as well as physical capabilities”.
To be healthy is to be in a state of homeostasis (balance) with one's surroundings. A healthy person, therefore, needs to maintain healthy habits such as taking regular exercise and adequate rest, adopting a high level of personal hygiene, eating a nutritionally balanced diet, abstaining from the abuse of drugs and alcohol, taking care of one's mental well-being and developing social skills to interact in a positive manner within society.
Many factors combine together to affect the health of individuals and communities. Whether people are healthy or not, is determined by their circumstances and environment. The factors which have been found to have the most significant influence – for better or worse – are widely known as the determinants of health. While health and social services make a contribution to health, most of the key determinants of health lie outside the direct influence of health and social care; for example, education, employment, housing, and environment. To a large extent, factors such as genetics, where we live, the state of our environment, our income and education level, and our relationships with friends and family all have considerable impacts on health, whereas the more commonly considered factors such as access and use of health care services often have less of an impact.
Public Health Agency of Canada and the World Health Organization has identified 12 determinants of health:
  1. Income and social status: Health status improves at each step up the income and social hierarchy. High income determines living conditions such as safe housing and ability to buy sufficient good food. The healthiest populations are those in societies which are prosperous and have an equitable distribution of wealth.
  2. Employment: Unemployment, underemployment and stressful work are associated with poorer health. People who have more control over their work circumstances and fewer stress related demands of the job are healthier and often live longer than those in more stressful or riskier work and activities
  3. Education: Health status improves with level of education. Education increases opportunities for income and job security, and equips people with a sense of control over life circumstances-key factors that influence health. Low education levels are linked with poor health, more stress and lower self-confidence.
  4. Social environments: The array of values and norms of a society, in varying ways, influence the health and well-being of individuals and populations. In addition, social stability, recognition of diversity, safety, good working relationships, and cohesive communities provide a supportive society that reduces or avoids many potential risks to good health. Studies have shown that low availability of emotional support and low social participation has a negative impact on health and well-being.
  5. Physical environments: Physical factors in the natural environment (e.g., air, water quality) are key influences on health. Factors in the human-built environment such as housing, workplace safety and road design are also important influences.
  6. Healthy child development: The effect of prenatal and early childhood experiences on subsequent health, well-being, coping skills and competence is very powerful. Children born in low-income families are more likely than those born to high-income families to have low birth weights, to eat less nutritious food, and to have more difficulty in school.
  7. Personal health practices and coping skills: Balanced eating, keeping active, smoking, drinking, and how we deal with life's stresses and challenges, all affect health.
  8. Health services: Access and use of services that prevent and treat disease influencing health.
  9. Social support networks: Support from families, friends and communities is associated with better health. The importance of effective responses to stress and having the support of family and friends provides a caring and supportive relationship that seems to act as a buffer against health problems.
  10. Biology and genetic endowment: Inheritance plays a part in determining lifespan, healthiness and the likelihood of developing certain illnesses.
  11. Gender: Men and women suffer from different types of diseases at different ages.
  12. Culture: Culture can be defined as all the ways of life including arts, beliefs and institutions of a population that are passed down from generation to generation. Culture includes codes of manners, dress, language, religion, rituals, norms of behavior such as law and morality, and systems of belief as well as the art. Customs and traditions, and the beliefs of the family and community, all affect health.
Dimensions of Health
Health is complex and involves the interaction of various factors. In 1948, the World Health Organization identified parameters to measure the functionality of an individual. The first three identified barometers include the physical, the social, and the mental constructs. Later, the emotional, spiritual, and environmental dimensions were added to the list.
(i) Physical
It is an ability of human body structure to function properly. Levels of physical fitness are determined by interacting genetic, environmental and individual factors. It is also affected by many interacting variables such as age, sex, diet, disease, stress, sleep, physical activity, medical and dental services, and by one's life cycle and lifestyle.
A physically fit person can carry out usual daily activities without undue fatigue and has enough energy to enjoy leisure time and to meet common emergencies.
(ii) Social
It is the ability to interact with other individuals. Social deprivation - intellectual, emotional, ethical, and spiritual - and prolonged exposure to social pathology and poverty may seriously impede the actualization of the individual's constructive potentialities.
(iii) Mental
Ability to process information and act properly.
(iv) Emotional
Ability to cope, adjust, and adapt.
(v) Spiritual
It is the belief in some force or dynamic other than humans. Human health involves a struggle to achieve a meaningful relationship with the universe and life. To ignore humankind's psychospiritual nature in developing models of health, would be to deal with a dehumanized caricature.
(vi) Environmental
It comprises of (i) External: one's surroundings, (e.g., habitat, occupation) and (ii) Internal: an individual's internal structure (e.g., genetics)
  1. Germ theory of disease (monocausal): Work of Koch and Pasteur revealed that the prevailing health problems of the time were the products of living organisms. Isolation of bacillus causing tuberculosis and identification of the organism responsible for 22 infectious diseases between 1880 to 1900, gave rise to the idea that each disease had a single and a specific cause. A set of rules was formulated by Koch (Koch postulates) for establishing causal relationship between a microorganism and a disease states. In brief, it was essential that to be ascribed a causal role, the agent must always be found with the disease in question and not with any other disease.
  2. Epidemiological triad: The germ theory could not explain why not all those exposed to pathogen become ill: an organism or other noxious agent is a necessary, but not a sufficient cause of disease. The epidemiological triangle approach sees disease as the product of an interaction between an agent, a host, and the environment. The epidemiological triangle is useful in understanding infectious disorders, but is less useful with respect to chronic and degenerative disorders such as stroke arthritis and heart disease.
  3. Web of causation: The web of causation considers all the predisposing factors of any type and their complex interrelationship with each other. This model is ideally suited for study of chronic diseases, where the disease agent is often not known. The disease is the outcome of the interaction of the multiple factors. It does not mean that to control a disease all or most of the factors need to be removed or controlled. The removal or elimination of even one factor may sometime be sufficient to control a disease provided that factor is sufficiently important.
  4. The theory of general susceptibility: This theory has emerged over the past 25 years and is different in important ways from monocausal and multicausal cause of disease. It is not concerned with identifying single or multiple risk factors associated with specific disorders. It seeks to understand why some social groups are more susceptible to disease and death in general.
  5. The socio-environmental approach: During the 1980s, the theory of general susceptibility became more explicitly formulated as the socio-environm ental approach. This approach seeks to identify the factors which make and keep people healthy and is not much concerned with the cause of the disease. It focuses on the population rather than the individuals. It forms the basis for the health promotion strategies.
Prevention of Disease
Prevention can be defined as ‘the action of keeping from happening, or of rendering impossible, an anticipated event or act.’
This definition assumes that the thing being prevented is anticipated, but it does not mean that the extent, severity, or extent of the thing is always known. Prevention in health care means action to stop ill health before it begins.
Criteria for Disease Prevention
  1. The disease and conditions are significant.
  2. There is prevention that works.
  3. Prevention is better than cure, repair, or doing nothing.
  4. Sufficient resources are available to implement the preventive measures.
  5. The economics can be calculated.
  6. The process is ethical.
  1. Disease is significant:
    Significance of disease can be assessed in terms of three factors;
    • Incidence and prevalence (how much disease is there and how many people are affected).
    • Mortality and morbidity (what are the effects of disease – mild discomfort, disablement or death).
    • Economics (what is the cost of the disease to the individual or the nation).
  2. There is prevention that works:
    For an effective preventive strategy
    • The natural history of disease must be understood (etiology; determinants; predisposing, initiating, exciting, environmental factors; stages of disease progression etc.).
    • There should be an effective intervention available.
  3. Prevention is better than cure, repair, or doing nothing:
    Even if a preventive method is available, certain factors need to be considered:
    • Acceptability
    • Economics
    • Balance against process and outcome of disease.
    • Acceptable associated risk
  4. Availability of resources to implement the preventive measures:
    This includes all necessary and sufficient resources such as
    1. Manpower numbers.
    2. Manpower skills and ability
    3. Materials.
    4. Time.
    5. Political will.
    Often sufficient resources are available but priority for their utilization is not there.
  5. Economics:
    Economics can be calculated by:
    1. Cost efficiency
    2. Cost benefit
    3. Cost utility
      To overcome the difficulty of comparing different health care approaches such as cost effective analysis (CEA) and cost benefit analysis (CBA) an approach termed cost utility analysis (CUA) has been developed where a universal currency, a single quantitative unit is constructed.
      The terms could be understood in terms of dentistry, as follows:
      - Cost Efficiency
      Cost of implementation
      No. of tooth surfaces saved
      - Cost Effectiveness
      Cost of implementation
      Savings in cost of treatment
      - Cost Benefit
      Cost of implementation
      Benefits to quality of life
  6. Ethics
    Ethics is concerned with what is right or what is wrong. Ethics in health care including prevention is as valid in preventing strategies as in any other element of health care provision.
An Ideal Public Health Measure Should Be
  1. Of proven efficacy in the reduction of the targeted diseases.
  2. Easily and efficiently implemented, using minimum quantity of materials and equipments.
  3. Medically safe.
  4. Readily administered by non-medical person.
  5. Attainable by the beneficiaries regardless of their socioeconomic, income, educational and occupational status.
  6. Readily available and easily accessible to large number of individuals.
  7. Inexpensive and hence affordable to majority of population.
  8. Uncomplicated and easily learned by people.
  9. Administered with maximum acceptance on the part of the patients.
  10. Administered with minimum compliance on the part of the people.
Successful prevention depends upon:
  • A knowledge of causation,
  • Dynamics of transmission,
  • Identification of risk factors and risk groups,
  • Availability of prophylactic or early detection and treatment measures,
  • An organization for applying these measures to appropriate persons or groups, and
  • Continuous evaluation of development of procedures applied
These can be studied under two main frameworks:
  1. Levels of Prevention
    1. Primordial prevention
    2. Primary prevention
    3. Secondary prevention
    4. Tertiary prevention.
  2. Approaches of Prevention
    • High risk (target) strategy
    • Mass (whole population) strategy.
  1. Primordial prevention: It is the prevention of emergence or development of risk factors in countries or population group in which they have not yet appeared. Individual and mass education is main intervention method in primordial prevention.
  2. Primary prevention: It is defined as ‘action taken prior to the onset of the disease, which removes the possibility that a disease will even occur’. It is carried out on healthy populations. Information and / or public health measure to the whole population may be sufficient to maintain a disease free environment. It may be accomplished by measures designed to promote general health and well being or by specific protective measures.
  3. Secondary prevention: It can be defined as ‘actions which halts the progress of a disease at its incipient stage and prevents complications’. It is carried out on targeted population identified by their being exposed to, or indulgence, in factors that place them ‘at risk’. The individual or the population is required to change, either to take some new action, or to cease an established action, or both, in order to lower the levels of risk.
  4. Tertiary prevention: It provides a cure at an early stage in disease process, containing the disease or its effects on a long term basis and seeks to prevent a recurrence of the disease. It can be defined as ‘all measures available to reduce or limit impairments and disabilities, minimizing suffering caused by existing departures from good health and to promote the patients adjustment to irremediable conditions’. The individual or population is aware of the disease, can see its effects and requires rehabilitation.
Modes of Intervention
Primary Prevention (Prepathogenesis)
Primary preventive services are those that prevent the initiation of disease.
  1. Health promotion: It is process of enabling people to increase control over and to improve health. This can be achieved by
    1. Health education; instruction on proper plaque removal, daily tooth brushing and flossing
    2. Environment modification such as safe water, control of insects and rodents.
    3. Nutritional interventions: improvement of nutrition in vulnerable group.
    4. Lifestyle and behavioural changes; which favor health
  2. Specific protection: These are activities designed to protect against disease agents by decreasing the susceptibility of the host or by establishing barrier against agents in the environment. Methods include immunization, use of specific nutrition, avoidance of allergens, protection from carcinogens, ingestion of optimally fluoridated water and application of pit and fissure sealants.
Secondary Prevention
(Pathogenesis: Initial Stage of Pathogenesis)
It is defined as “action which halts the progress of a disease at its incipient stage and prevents complications.”
These services intervene or prevent the progression and recurrence of disease.
  1. Early diagnosis: WHO Expert Committee in 1973 defined early detection of health disorders as “the detection of disturbances of homeostatic and compensatory mechanism while biochemical, morphological and functional changes are still reversible.”
    The earlier the disease is diagnosed and treated the better is its prognosis and helps to prevent the occurrence of more cases.
    Actions that detect and treat disease at an early stage thus hinder the progress of a disease and prevent complications. i.e. intervention in early pathogenesis phase.
    The methods (tools) employed for early diagnosis are:
    1. Screening for sub-clinical disease, either in screening surveys or in periodic medical examinations.
    2. Case finding (individual and community).
  2. Prompt treatment: Secondary prevention attempts to arrest the disease process, restore health by seeking out unrecognized disease and treating it before irreversible pathological changes take place, and reverse communicability of infectious diseases.
Tertiary Prevention
(Pathogenesis: Late Stage of Pathogenesis)
Actions taken when the disease process has advanced beyond its early stages i.e. intervention in late pathogenesis phase.
It is defined as “all the measures available to reduce or limit impairments and disabilities, and to promote the patients’ adjustment to irremediable conditions.”
Intervention that should be accomplished in the stage of tertiary prevention is disability limitation, and rehabilitation.
The aim of tertiary prevention is to limit disability and prevent further complications or death.
  1. Disability limitation
    The objective of this intervention is to prevent or stop the transition of the disease process from impairment to handicap (Fig. 1.1). The sequence is as follows:
    • Disease
    • Impairment
    • Disability
    • Handicap
    1. Impairment: It is “any loss or abnormality of psychological, physiological or anatomical structure or function.”
    2. Disability: It is “any restriction or lack of ability to perform an activity in the manner or within the range considered normal for the human being.”
      zoom view
      Fig. 1.1: Transition of disease process
      Levels of prevention
      Concept of prevention
      Prevention of disease initiation
      Prevention of disease progression and recurrence
      Prevention of loss of function
      Modes of intervention
      Health promotion specific protection
      Early diagnosis and prompt treatment
      Disability limitation rehabilitation
    3. Handicap: It is termed as “a disadvantage for a given individual, resulting from an impairment or disability that limits or prevents the fulfillment of a role in the community that is normal (depending on age, sex, and social and cultural factors) for that individual.”
      Tools for tertiary prevention include rehabilitation
  2. Rehabilitation: It is defined as “the combined and coordinated use of medical, social, educational, and vocational measures for training and retraining the individual to the highest possible level of functional ability.”
It is a measure to train the disable individuals to reach the highest level of functional ability by using combined coordinated medical, social, vocational, psychological and educational measures.
Rehabilitation comprises:
  1. Medical rehabilitation: restoration of function or physical loss.
  2. Educational rehabilitation: change of educational methods.
  3. Vocational (occupational) rehabilitation: restoration of the capacity to earn a livelihood.
  4. Social rehabilitation: restoration of family and social relationships.
  5. Psychological rehabilitation: restoration of personal confidence
Examples of rehabilitation:
  1. Special schools for blind pupils.
  2. Provision of aids for crippled.
  3. Reconstructive surgery for leprotics.
  4. Modification of life for tuberculous or cardiac patients.
High-risk Strategy
Here the population is classified in relation to the degree of risk which individuals or groups of individuals exhibit, or are exposed to. It aims to bring preventive care to individuals or a group at special risk, which will reduce their risk factors.
  1. Doctor-patient relationship.
  2. Better motivation.
  3. Cost benefits.
  4. Individual appropriateness.
  1. Criteria for ‘at risk’ not clear.
  2. Cost of screening.
  3. Does not tackle cause of disease.
  4. Misses transitional populations.
Mass Strategy
“Population strategy” is directed at the whole population irrespective of individual risk levels.
This approach does not differentiate between individuals in any defined population and is directed towards the whole population. It treats all individuals as at equal risk. Underlying factors which contribute to the etiology of the disease, or themselves are causative factors, are targeted for alteration. The population approach is directed towards socio-economic, behavioral and lifestyle changes.
  1. Easier.
  2. Behaviorally appropriate for whole population.
  3. Gets to the cause of the disease.
  4. Reaches all who may become high risk / sufferers.
  1. Requires a lot of motivation.
  2. Dilution of efforts.
  3. Dilution of effects.
  4. Less specific.
  5. Higher rate of failure.
  6. Lessened benefit to individuals.
Barriers (Challenges) to Preventive Strategies
  1. Diversity of population
    A homogeneous message may not be appropriate for a heterogeneous population. Population varies in social status, age, ethnicity, differing attitudes, beliefs, expectations, knowledge, understanding and disease level etc.
  2. Inherent beliefs/mores
    These include – fear of health/medical profession, confusion from previous message, erroneous message etc.
  3. Advertising
    Propaganda produces pressure selling on children and blackmail on parents.
  4. Pressure groups
    Many pressure groups base their opposition to health promoting moves on the basis of loss of autonomy and choice (seat belts, smoking in public places), and others on medical and epidemiological evidence (water fluoridation etc.).
  5. Access
    Access to people to improve health is usually poorest to those who are in most need of intervention, e.g. Social class III, IV, V, kids, risk group.
  6. Resources
    Although governments stress the importance of prevention, the major drain on health resources is the acute health care sector. Directing resources into prevention is still not completely addressed.