General Epidemiology

Question 1

Definition of Epidemiology?

Answer 1

Study of prevalent health conditions of population.

• Who does/does not get sick with particular disease?
• Where illness is/is not found?
• Under what particular condition does it occur?

Question 2

Importance of Epidemiology Methods?

Answer 2

• Public health workers know prevailing levels of disease/disability.
• Recognize changes in health of population.
• Epidemiology —> tool to alert us for early warning signs of bio-terrorism.

Question 3

Conceptual bases of epidemiology are derived from other disciplines such as…?

Answer 3

1) Statistic
2) Physiology
3) Sociology
4) Demography
5) Biology

Question 4

When did modern epidemiology begin?

Answer 4

• When we had a better understanding of germ theory & developed methods to track source & spread of communicable diseases.
• Cholera outbreak paved way for current methods for investigation & control of disease outbreaks.

Question 5

What does epidemiology focus on?

Answer 5

1) Populations rather than individuals.

2) Health promotion & disease/injury prevention rather than treatment/cure.

Question 6

Diagnostic tools for epidemiology?

Answer 6

Statistics & data rather than thermometers/BP cuffs.

Question 7

Determinants of health?

Answer 7

Health is a state of complete:

• Physical
• Mental
• Social
• Spiritual wellbeing & not merely the absence of disease/infirmity.

Question 8

Definition of disease?

Answer 8

Deviation from normal status which can be defined statistically, socially or according to life cycle.

Question 9

What is natural pattern of disease?

Answer 9

Characteristic pattern of progression in absence of intervention.

• Four stages of progression:
  1) Stage of Susceptibility:
  Disease process that begins prior to exposure to disease/injury when normal body defenses are affected to a degree that the individual is vulnerable to pathogen/set of risk factors associated with particular illness.

2) Stage of Sub-clinical disease:
After exposure, many diseases have latency period when the person is having pathogenic changes from the disease, but no overt clinical symptoms. Period of latency may be very brief or many years. With infectious diseases, each disease has characteristic time period of latency (Incubation Period). With non-infectious diseases, eg: cancer/hypersensitive disorder, time range for latency period varies greatly. Person are clinically asymptomatic but pathogenic changes may be detected by various screening measures.

3) Stage of Clinical Disease:
Onset of symptoms indicates beginning of stage of clinical disease. Disease process may be serve/mild & may vary in length. Some people never progress to this stage.

4) Stage of Recovery, Disability or Death:
Refers to outcomes of the disease when there is no intervention & may range from recovery, disability or death.

Question 10

Three Levels of Prevention

Answer 10

1ry Prevention: health promotion & protection/disease or injury prevention.
Health promotion = things that positively contribute to high-level of human health & well being.
- At individual level, it includes:
1) Maintaining proper nutrition
2) Regular exercise
3) Stress management
4) Regular, sufficient sleep

• At population level:
  1) Establishing policies &/or corporate behaviors that assure clean air, potable water, safe & pollution free places to live & access resources that affect health positively.

Disease/Injury prevention:
Includes things that prevent specific diseases or injuries. Age & situation appropriate immunizations for preventable diseases e.g. measles, flu, smallpox. Injury prevention e.g. wearing seat belt.

2ry Prevention:
Early diagnosis & treatment of health problems. Screening for health problems includes methods that detect presence of health problem before overt clinical symptoms occur. Disability & death can be prevented if diseases is detected on time.

Tertiary Prevention: Rehabilitation and/or limitation of disability.

Question 11

What are the epidemiological methods?

Answer 11

1) Epidemiological Triad: most commonly used model particularly when dealing with communicable diseases.
2) Web of Caution: explains lifestyle/behavior induced diseases, many of which are chronic.
3) Wheel model: explains the causation in the individual level where there is a genetic core surrounded by other factors e.g. education, occupation, age, sex, life style…