10. Epidemiology – brief history.

Epidemiology: Brief History

Definition

• Epidemiology is the science that studies the distribution, frequency and determinants of diseases in populations.
• It investigates disease occurrence, spread, risk factors and preventive measures.
• The term comes from Greek: epi (upon) + demos (people) + logos (science).
• Originally focused on infectious diseases, but today includes both communicable and non-communicable diseases.

Historical Development

• Hippocrates (460–377 BC)
• First suggested that environmental and lifestyle factors influence health and disease.
• Considered the first person to link disease with living conditions rather than supernatural causes.
• R. Robertson (1803)
• Conducted one of the earliest epidemiological investigations.
• Studied relationships between health habits and health status.
• John Snow (1855)
• Known as the Father of Modern Epidemiology.
• Investigated the cholera epidemic in London.
• Demonstrated the relationship between contaminated drinking water and cholera transmission.
• Introduced the scientific study of disease distribution and sources of infection.
• Alistair Gregg (1941)
• Demonstrated the association between maternal rubella infection and congenital cataracts in newborns.
• Doll & Hill (1950–1964)
• Proved the relationship between cigarette smoking and lung cancer.
• One of the most important studies in chronic disease epidemiology.
• Frederick McKay (1908–1931)
• Studied “Colorado Brown Stain” (dental fluorosis).
• Observed lower caries prevalence in affected populations.
• In 1931 increased fluoride concentration in drinking water was identified.
• Established the preventive role of fluoride against dental caries.

What Epidemiology Studies

• Communicable diseases
• Influenza, cholera, HIV/AIDS, hepatitis, tuberculosis.
• Focuses on transmission mechanisms, outbreaks and prevention.
• Non-communicable diseases
• Cardiovascular diseases, diabetes, cancer, respiratory diseases and renal diseases.
• Focuses on risk factors, prevention and disease trends.
• Epidemiology studies:
• Disease frequency.
• Disease distribution.
• Causes and determinants.
• Risk factors.
• Prevention and control measures.

Main Goals of Epidemiology

• Determine the spread and frequency of diseases.
• Identify risk factors and causes.
• Investigate mechanisms of disease transmission.
• Develop prophylactic and preventive measures.
• Evaluate preventive and treatment programmes.
• Assist healthcare planning and reforms.
• Improve population health and quality of life.
• Types of Epidemiology
• Descriptive Epidemiology
• Describes disease according to:
• Person
• Place
• Time
• Also studies:
• Age
• Sex
• Occupation
• Residence
• Answers:
• Who gets the disease?
• Where does it occur?
• When does it occur?

Analytical Epidemiology

Identifies causes and risk factors.

Examines relationships between exposure and disease.

Example: smoking – lung cancer.

Answers:

Why does disease occur?

How does it spread?

Experimental (Interventional) Epidemiology Evaluates preventive and therapeutic interventions.

Examples:

Vaccination programmes

Fluoride programmes

Health education campaigns

Importance in Dentistry

• Measures prevalence and severity of:
• Dental caries.
• Periodontal diseases.
• Identifies high-risk groups.
• Evaluates preventive programmes.