Unit-II-Concept of Health & Disease.pptx

Nursing epidemiology

1. Epidemiology Unit-II  Concept of Health & Disease Muhammad Shahid MSN,BSN,DCN, RN, BSc Assistant Professor/Principal School Of Nursing Kharadar General Hospital

2. Objectives At the completion of this unit learners will be able to: Discuss the terms of Health, Disease, and Well-being. 2. Describe the concept of causation. 3. Understand the Health indicator 11/6/2023 2

3. Concept of Health Definitions : “Absence of disease” In some cultures, health and harmony are considered equivalent, Harmony : "being at peace with the self, the community, god and cosmos". (Indian Ayurveda and Greek) 11/6/2023 3

4. Concept of Health Modern medicine: Studies disease, and neglects of the study of health. In 1977, the 30th World Health Assembly decided that the main social target of governments and WHO : "the attainment by all citizens of the world by the year 2000 of a level of health that will permit them to lead a socially and economically productive life”, "Health for All" 11/6/2023 4

5. Changing Concepts of Health 11/6/2023 5

6. Biomedical Concept 11/6/2023 6

7. Ecological Concept 11/6/2023 7

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10. BASIC CONCEPTS Health: (WHO,1948) a state of complete physical , mental & social Wellbeing , not merely the absence of disease. Wellness: Level of wellbeing, a person perceives of being healthy. Disease: Alteration of structure and function of body. Disease or discomfort. Or physiological and psychological dysfunction. Anything that leads to discomfort, pain, distress, disability or death. Illness: Subjective state of the person who is experiecing a state of not feeling well. Sickness: A state of social dysfunction that the individual assumes when not feeling well. 10 11/6/2023

11. WHO Definition of Health Health is a state of complete physical , mental and social well-being and not merely an absence of disease or infirmity and ability to lead socially and economically productive life. 11/6/2023 11 Constitution of the World Health Organization-1947

12. Concept of disease “A condition in which body function is impaired, departure from a state of health, an alteration of the human body interrupting the performance of the vital functions.” - Webster. A critical premise of epidemiology is that disease and other health events do not occur randomly in a population, but are more likely to occur in some members of the population than others because of risk factors that may not be distributed randomly in the population.  One important use of epidemiology is to identify the factors that place some members at greater risk than others. 11/6/2023 12

13. The Health-Sickness spectrum

14. Historical Theories for causation of disease “Supernatural causes”& Karma Theory of humors (humor means fluid) The miasmatic theory of disease Theory of contagion Germ theory Epidemiological Triad Multi-factorial causation Web of causation ………Supernatural to multi-factorial causes… Environment Agent Host

15. HEALTH AND ILLNESS

16. 11/6/2023 16 Factors Affecting Disease Transmission Host Vector Agent Environment -- Susceptibility -- Immune response -- Resistance --- Portal(s) of entry -- Virulence Toxigenicity -- Infectivity Resistance -- Pathogenicity Antigenicity VECTOR -- Prevalence -- Portal(s) of entry -- Balance of immune to susceptible individuals --- Opportunity for exposure (e.g. crowding)

17. Routes of transmission 11/6/2023 17

18. Conti.... Infectivity: The ability of an infectious agent to cause infection, measured as the proportion of persons exposed to an infectious agent who become infected. Pathogenicity: The ability of an agent to cause disease after infection , measured as the proportion of persons infected by an agent who then experience clinical disease . Virulence: The ability of an infectious agent to cause severe disease , measured as the proportion of persons with the disease who become severely ill or die. Toxogenicity: Ability of the pathogenic organism to produce injurious substances that damage the host . Resistance: Ability not to be affected by something. Antigenicity: The degree to which a substance is able to stimulate an immune response . 11/6/2023 18

19. Concept of Web causation The interrelationships of several factors that precipitate a particular disease. OR It is used to analyzes interrelationships among multiple factors that contribute to the occurrence of a disease or condition. There are at least three (and probably more) more likely reasons that causation is an issue in epidemiology. 11/6/2023 19

20. Conti… First , it is a science relying heavily on observational studies. Second, epidemiology deals with general causal claims , such as ‘Smoking causes lung cancer’. These claims are hard to interpret. Finally, the identification of causes in many sciences . There is no single cause. Causes of disease are interacting Multiple action and reaction occur between promoters and inhibitors of disease. Example diabetes, cancer 11/6/2023 20

21. Web causation 11/6/2023 21

22. Web of causation Change in life style Stress Abundance of food Smoking Emotional Aging & D Disturbance other factor Obesity Lack of physical activity Hypertension Hyperlidemia Increase catacholamine Changes in walls of arteries thrombotic activity Coronory atherosclerosis Coronary occlusion Myocardial Ischemia Myocardial Infarction

23. Epidemiological Triad 11/6/2023 23

24. Iceberg Phenomenon of disease Iceberg phenomenon of disease gives a picture of the spectrum of diseases in a community . Cases of illness correctly diagnosed by clinicians in the community often represent only the “tip of the iceberg.” Many additional cases may be too early to diagnose or may remain asymptomatic . Examples: Tuberculosis, meningitis, polio, hepatitis A, AIDS. The risk is that persons with in-apparent or undiagnosed infections may be able to transmit infection to others. 11/6/2023 24

25. Conti.... The part of the iceberg below the water level denoted the latent, subclinical , undiagnosed and carrier states in the community, which forms the major part. Symptoms are just tip of ice berg Headache Constipation Poor concentration Fatigue Anexiety /depression Insomnia Immune weakness Arthritis / fibromyalgias 11/6/2023 25

26. Encephalitis, meningitis, myelitis Increased risk with age & co-morbid conditions Reportable condition <1% infections "ICEBERG PHENOMENON" 11/6/2023 26

27. WNF (10-30%) No “overt” CNS involvement Fever, rash, headache, myalgia, arthralgia Not a reportable condition 10 -30% infections "ICEBERG PHENOMENON" 11/6/2023 27

28. Asymptomatic WN infection (70-90%) Asymptomatic infection Not reportable condition Same virus / antibody kinetics Life-long immunity Potential problem for blood banking & organ donation 70-90% infections "ICEBERG PHENOMENON" 11/6/2023 28

29. The pyramid and iceberg of disease 1 Diseased, diagnosed & controlled 2 Diagnosed, uncontrolled 3 Undiagnosed or wrongly diagnosed disease 4 Risk factors for disease 5 Free of risk factors Diagnosed disease Undiagnosed or wrongly diagnosed disease 11/6/2023 29

30. 11/6/2023 30 Example: Cholera , Polio, hypertension, malnutrition etc.

31. Health indicator Health indicators are quantifiable characteristics of a population which researchers use as supporting evidence for describing the health of a population. Typically, researchers will use a survey methodology to gather information about certain people. Use statistcs in an attempt to generalize the infromaion collected to the entire population. Use the statistical analysis to make a statement about the health of the population. Health indicators are often used by governement to guide health care policy . A common example of health indicator is life expectancy . 11/6/2023 31

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33. Characteristics of Health indicators A health indicators which will be used internationally to describe global health should have the following characteristics: It should be defined in such a way that it can be measured uniformly internationally . It must have statistical validity The indicator must be data which can feasibly be collected. The analysis of the data must result in recommendation on which people can make changes to improve health. 11/6/2023 33

34. Conti..... Mortality indicators: Crude death rate Life expectancy Infant mortality rate Maternal mortality rate Proportional mortality rate Morbidity indicators: Prevelance rate Incidence rate 11/6/2023 34

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36. Conti..... Health status (Conditions): Low birth weight Obesity Arthiritis Diabetes Asthma High blood pressure Cancer incidence Chronic pain Depression Reports of waterborne diseases or foodborne illness 11/6/2023 36

37. Enabling, risk factors and causes All may be necessary but rarely sufficent to cause a particular disease or state. Predisposing: Age, sex, or previous illness may create a state of susceptibility to a disease agent. Enabling: Low income, poor nutrition, bad housing, or inadequate medical care may favor the development of disease Conversely, circumstances that assist in recovery or in helath maintenance may be anabling. 11/6/2023 37

38. Conti..... Risk factors (Condition determinant, Predisposing factor): “ Probability of an event during a specified period of time”. Risk is the likelihood, usually quantified as an incidence rate or cumulative incidence proportion , that an individual will develop a given disease in a given time period. An individual attribute or exposure that is positively or negatively associated with the occurence of a disease. Attribute: Risk factor that is an intrinsic characteristics of the individual (E.g. Genetic susceptible, age, sex, weight). Exposure: Risk factor that is in the envirnment external to the individual (E.g., Nutrition, housing, or toxic agent.) 11/6/2023 38

39. Conti..... Cause: “ Interacting causally to produce disease”. The combination of necessary and sufficient factors (E.g. Attributes and exposures) the presence of which alone or in combination, at some time during an individual’s life, inevitably result in disease in that individual. Causal pathway (Causal web, cause and effect relationship ) Etiology, the study of disease causes and their modes of operation. Necessary cause: A risk factor that must be or present for the disease to occur. Sufficent cause: The minimal combination of risk factors acting on the inidividual. E.g. Sometime Environment. 11/6/2023 39

40. References G.Leon, (2009). Teaches the basic principles and methods of epidemiology (4 th edi.) Rothman, K.J., Greenland, S., Lash, T.L.,(2010) Modern epidemiology, 3 rd Edition, Lippincott williams and wilkins. 11/6/2023 40