The document discusses public health and the natural history of disease. It defines health using the WHO definition and outlines 8 key determinants of health - biological, behavioral, environmental, socioeconomic, health services, aging, gender and other factors. It then explains the concept of disease and the triangle of epidemiology involving agent, host and environmental factors. Finally, it describes the natural history of disease, including stages of susceptibility, subclinical disease and clinical disease.

1. Public Health

2. What is ‘Health’ ?
 Oxford dictionary
State of being well in body or
mind

3.  “Health is a state of complete physical, mental and
social well-being and not merely the absence of
disease or Infirmity.”
W.H.O. Definition of Health

4. DETERMINANTS OF HEALTH
 The factors which influence health lie both within
the individual and externally in the society .
 These factors which promoting or deleterious of
health.

5. Determinants of Health
1. Biological determinant
2. Behavioural & socio-cultural conditions
3. Environment
4. Socio-economic conditions
5. Health services
6. Aging & population
7. Gender
8. Other factors.

6. 1) Biological determinants
A number of diseases are known to be of
genetic origin, e.g.
 Chromosomal anomalies
 Mental retardation
 Diabetes

7. 2)Behavioral and social culture conditions
 Life style is “ The way people live”
reflecting a whole range of social values ,
attitude and activities.
 It is composed of cultural and behavioral
patterns and lifelong personal habits that have
developed through processes of socialization .

8. 2)Behavioral and social culture
conditions
Life style in developed c.
 Smoking
 Obesity
 Drug addiction
Life style in developing c.
 Poor nutrition
 Personal hygiene

9. 3) Environment
 Environment is classified as “internal”
and “external”.
 Internal : each & every component part, every
tissue, organ & organ system & their harmonious
functioning within the system
 External: all that which is external to the
individual human host.
 It can be divided into physical, biological and
psychosocial components.e.g
eating habits, life style &
personal habits

10. 4) Socio-economic conditions
 It influence human health
1. Economic status
2. Education
3. Occupation
4. Political influence

11. 4) Socio-economic conditions
 Economic status
 When ↑
 ↓ morbidity
 ↑ life expectancy
 Improving the quality of life
 Improving the purchasing power
 ↑ heart diseases, diabetes & obesity.
 Family size.

12. 4) Socio-economic conditions
 Education
1. ↑ literacy ( male) ---------↓ poverty
2. ↑ literacy ( females)------- ↓ malnutrion , ↓ infant
mortality rate

13. 4) Socio-economic conditions
 Occupation
1. State of being employed in productive work
promotes health
2. Loss of work mean loss of income & cause
psychological & social damage.

14. 4) Socio-economic conditions
 Political system
1. Resource allocation.
2. Health services available.
3. Manpower policy.

15. 5) Health services
 Improve health status of population
by:
1. Immunization of children
2. Provision of safe water supply can
prevent mortality & morbidity from
water borne diseases.
3. Care of pregnant women reduce of
maternal & child morbidity &
mortality.

16. 6) Ageing of the population
• ↑ prevalence of chronic diseases & disability

17. 7 ) Gender
 Nutrition
 Reproductive health
 Ageing
 Life style
 Increase awareness among
policy makers of women’s
health issues & encourages
their inclusion in all
development plans as a
priority

18. 8) Other factors
 Food & agriculture
 Industry
 Social welfare

19. Concept of Disease

20. Disease
 Oxford English Dictionary – the condition of
body or some part of organ of body in which its
functions are disrupted or deranged.
 Simplest definition – ‘Opposite to Health’.
 Disease is a physiological/psychological
dysfunction.

23. The Triangle of Epidemiology

24. Agent Factors
What are the “Types of
agent factors” ???

25. Host Factors
1. Demographic characteristic ( age, sex, ethnicity)
2. Biological characteristic ( genetic factors,
cholesterol in the blood)
3. Social & economic characteristic ( socio-
economic status, education, occupation, stress,
housing)
4. Lifestyle factors (living habits, nutrition,
smoking, physical exercise )

26. Environmental factors
 Intrinsic
 Extrinsic
1. Physical environment
2. Biological environment
3. Psychosocial environment

29. Natural history of
disease

30. Natural History of Disease
 It is the progression of a disease process in an
individual over time, in the absence of
treatment.
 The time frame of disease may vary from
individual to individual.

31. Stage of susceptibility
 The process begins with the appropriate exposure to the
factors.
 For an infectious disease, the exposure is a
microorganism.
 For cancer, the exposure may be tobacco smoke (for
lung cancer)

32. Stage of subclinical disease
 pathological changes occur without the individual
being aware of them.
 extending from the time of exposure to onset of
disease symptoms,
 called the incubation period (infectious diseases)
& the latency period (chronic diseases).
 Disease is asymptomatic (no symptoms)
 Incubation periods of varying from minutes to
decades .

33. Exposure Clinical Effect Incubation/Latency
Period
Salmonella Diarrhea, often with
fever and cramps
6–48 hr
Hepatitis A virus Hepatitis 14–50 days, average 4
weeks
Hepatitis B virus Hepatitis 50–180 days, usually 2–3
m
Human immunodeficiency
virus
AIDS <1 to 15+ years

34.  Although disease is not apparent during I.P,
pathologic changes may be detectable with
laboratory, radiographic, or other screening
methods.
 intervention at this early stage is more
effective than treatment given after the
disease has progressed and become
symptomatic

35. Stage of clinical disease.
 The onset of symptoms marks the transition from
subclinical to clinical disease.
 Most diagnoses are made during the stage of
clinical disease.
 The disease process ends either in recovery,
disability or death