Fundamentals of Epidemiology: Population, Health, and Prevention
1) Why Study Epidemiology?
Epidemiology studies the distribution and frequency of disease in a community to control or eradicate it. It compares frequencies, quantified by statistics, using a method similar to the scientific method.
2) Scientific Method Steps
The scientific method has four steps:
- Observation: Analyzing a patient’s physical and mental aspects, including symptoms.
- Hypothesis Formulation: Developing possible illnesses and causes.
- Verification: Conducting studies for diagnosis.
- Conclusion: Determining the medical diagnosis and treatment.
In epidemiology:
- Observation: Number of cases and distribution.
- Hypothesis Formulation: Supposition.
- Verification: a) Course, b) Experimentally.
- Conclusions: Through a) clinical observation, b) laboratory experiments, c) epidemiological studies.
3) Population Classification
Populations can be classified as urban and rural.
4) Argentina’s Population Characteristics
In Argentina, about 75% of the population is urban. There are notable differences in birth and mortality rates between urban and rural populations, both being higher in rural areas. Sex and age are also important; more males are born, but they experience higher early mortality. Age structure is related to global development.
5) & 6) Population Pyramids
What is a Population Pyramid?
A population pyramid is a graphical representation of age information from census data. It has transverse axes (vertical and horizontal) representing population, with males and females on either side of the vertical line.
Types of Population Pyramids
- Wide Base: Rapidly decreasing towards the apex (underdeveloped countries).
- Wide Base: Slowly declining towards the apex (developing countries).
- Narrow Base: Thickened at the center, slowly declining towards the apex (developed countries).
7) Determining Population Structure
Population structure is determined by birth, mortality, and migration. Birth rate is the most significant factor, determining the broad base of pyramids in underdeveloped and developing countries. Infant mortality rates determine the rapidity of the decline towards the apex.
8) Defining Health
Health is the “state of complete physical, mental, and social well-being and not merely the absence of disease or accident.” It has two components: welfare and freedom from disease.
Welfare is expressed in three ways:
- Physically: Subjective feeling that no organs or functions are impaired.
- Psychically: Inner balance, intellectual and emotional.
- Socially: Constructive engagement with the social environment.
Absence of disease involves examining the concept of disease, which implies an abnormality in organic or functional health.
9) Stages of Illness
All diseases have three stages:
- Clinical stage, asymptomatic.
- Prodromal stage: Symptoms and signs indicate the presence of disease.
- Advanced disease stage: Symptoms and signs constitute a syndrome.
10) Defining Prevention
Prevention is a series of barriers against disease development.
11) Levels of Prevention
Prevention is divided into primary, secondary, and tertiary levels.
Primary Prevention (pre-pathogenic period):
- Health Promotion: Government initiatives promoting health, nutrition, education, etc. (lectures, debates, advertisements).
- Specific Protection: Preventing specific diseases (vaccination, water fluoridation).
Secondary Prevention (early pathogenic period):
- Early Diagnosis
- Early Treatment
Examples include doctor visits at the onset of symptoms for early diagnosis and treatment.
Tertiary Prevention (late pathogenic period):
- Limiting the Damage (e.g., endodontics, extractions).
- Rehabilitation (e.g., dentures, physical and psychological rehabilitation, social reintegration).
12) Factors Derived from the Middle Disease
The presence or absence of disease depends on several factors. Poverty is a significant negative influence, evident in:
- Housing: Overcrowding, poor construction, unmet needs (sewer, water, electricity, gas).
- Health: High rates of unvaccinated children, lack of healthcare access.
- Education: Low income, late school entry, high repeat rates in primary school.
- Nutrition: Malnutrition, especially in children under 5, leading to diseases like caries.
- Work: Unemployment and underemployment.