2024-2025 Epidemiology CC
EPIDEMIOLOGY
LESSON 1: EPIDEMIOLOGY AND PUBLIC HEALTH
EPIDEMIOLOGY AND PUBLIC HEALTH
DEFINITIONS 1. Epidemiology and Public Health
• Epidemiology is a method of reasoning about disease that deals with biological
inference derived from observations of disease phenomena in population groups
epidemiology
“upon" demos logos
• Often considered the core science of public health, epidemiology involves “the “people" “study"
study of distribution and determinants of disease frequency = the study of the occurrence of
illness
• Scientific research intends to fill the gaps in knowledge or improve current knowledge with a
final goal of improving society
• Epidemiologic research has a final goal of improving public health
EPIDEMIOLOGIC RESEARCH
• Main strength: assessment of disease burden or the relationship (association) between
exposure and disease in a population of interest
• Method: counting withing groups and comparing
• Main challenges
o Who to count?
o When to count?
o How to compare?
• Three types of questions:
o What is the burden of disease?
o What is the prognosis of a disease?
o Which are the risk factors/exposures causing the disease?
• What is epidemiology?
o The study of the distribution and determinants of health-related states or events
(including disease), and the application of this study to the control of disease and other
health problems
o Various methods can be used to carry out epidemiological investigations: surveillance
and descriptive studies can be used to study distribution, analytical studies are used to
study determinants
• Three types of epidemiology to answer these questions:
o Descriptive epidemiology: non-causal analyses which describe observed data (e.g.
surveillance)
Surveillance = the ongoing, systemic collection, analysis and interpretation of health-
Descriptive related data essential to planning, implementation and evaluation of public health
practice, closely integrated with the timely dissemination of these data to those
responsible for prevention and control
Analytical
1
, 2024-2025 Epidemiology CC
o Predictive (prognosis) epidemiology: use of observed data to make statements or
predictions (e.g. used in clinical epidemiology)
o Causal (etiologic) epidemiology: causal effects of risk factors/exposures on disease
emiology and! Descriptive
Public Health
epidemiology is crucial to develop analytical epidemiology
! Epidemiology results are not the only prove for causality
pidemiology?
Exposure-oriented epidemiology Outcome-oriented epidemiology
• Environmental epidemiology • Infectious disease epidemiology
• Occupational epidemiology • Cancer epidemiology
• Pharmacoepidemiology • Mental health epidemiology
• Nutritional epidemiology • Neurologic diseases epidemiology
• Genetic epidemiology • Reproductive epidemiology
• Molecular epidemiology • Respiratory disease epidemiology
• Social epidemiology • Dental epidemiology
• etc. • Clinical epidemiology
• Chronic disease epidemiology
• etc.
PUBLIC HEALTH
• The art and science of preventing disease, prolonging life and promoting health through the
organized efforts of society
• The community effort to protects, maintain and improve the health of a population by organized
means, including preventive programs, hygiene, education and other inventions
1. Epidemiology and Public Health
• What is the role of public health?
o Surveillance What is public health?
= descriptive epidemiology to establish objectives and priorities
o Health services
= planning and evaluation of health care services
o Disease prevention 1. Epidemiology and Public Health
§ Primary prevention
= intervening before health effects occur, through
What is public health?
measures such as vaccinations, altering risky behaviors
and banning substances known to be associated with a
disease or 3.health condition
Disease prevention
§ Secondary prevention Epidemiology
= screening to identify Secondary
Primary disease in the earliest stages, before
Tertiary
the onset prevention
of signs and prevention
symptoms, through
preventionmeasures such as
mammography and regular blood pressure testing Surveillance
§ Tertiary prevention
Detection of risk factors
= managing disease post diagnosis to slow or stop disease
Evaluation of interventions
progression through measures such as chemotherapy,
Evaluation of diagnostic tests
rehabilitation and screening for complications (e.g. chronic
disease management, cardiac rehabilitation, pain management clinics…)
o Health promotion
= enables people to increase control over their own health. It covers a wide range of
social and environmental interventions that are designed to benefit and protect
individual people’s health and quality of life by addressing and preventing the root cause
of ill health, not just focusing on treatment and cure (e.g. city bikes in Antwerp)
o Health protection
= minimization of the exposure to health hazards to protect the population by ensuring
environmental, occupational, toxicological and food safety
2
,2024-2025 Epidemiology CC
1. Epidemiology and Public Health
EPIDEMIOLOGY PURPOSES IN PUBLIC HEALTH PRACTICE
Public health approach
Risk Factor Intervention
Surveillance Implementation
Identification Evaluation
Adapted from CDC link
• Discover the agent, and environmental factors that affect health
• Determine the relative importance of causes of illness, disability and death
• Identify those segments of the population that have the greatest risk from specific cause of ill
1. Epidemiology and Public Health
health
• Evaluate the effectiveness of healthEpidemiology:
programs and services infield
a multidisciplinary improving population health
! Epidemiology is a multidisciplinary field
HISTORY
Hippocrates of Kos (400 BC)
• Greek physician and philosopher
• Disease demonic possession and divine displeasure
• Greek physician and philosopher
• Diseases demonic possession and divine displeasure
• To physicians: Disease occurrence can be related to environment.
• Earthly causes: “On Airs, Waters and Places”, at community of origin
• Behavior: “fond of drinking and eating to excess…”
• Change from mysticism towards observation and reason as causes of disease
Avicenna (1st-2nd century)
• Persian philosopher, scientist, and physician.
• Empirical evidence and disease causation:
• experimentation and quantification
• Infectious diseases (ID) could be spread by contagion
• Quarantine to limit the spread of ID
3
, 2024-2025 Epidemiology CC
Fracastoro (15th-16th century)
• Italian physician and poet
• Extended the theory of contagion: theory about how contagious disease spreads
• Plague, typhus and syphilis: spread through self-replicating particles (seminaria or
• seeds) [“Germ theory”]
• Seminaria:
• Very small and diseases specific
• Spread by:
• Direct person-to-person contact
• Indirect contact (fomites)
• Transmission at a distant (air or water)
• Affected by atmospheric conditions
• Poem about Syphilis
John Graunt (17th century)
•
British
•
World’s first epidemiologist and demographer
History
•
Bills of Mortality in London and later, throughout England (deaths, baptisms, causes of death,
age at death,…) [15th-19th century)
• Demography: London population dynamics (growth due to inmigration),sex ratios
• Epidemiology:
Pioneers of Epidemiology and Public Health
• Trends of diseases
• Disease misclassification
Bernadino Ramazzini (1633-1714)
• Excess deaths during epidemics
• Italian physician
Bernadino Ramazzini (17th-18th century)
• Occupational medicine
• Italian physician
• Risks related to dozens of occupational hazards
• Occupational medicine
• Review
o Risksof suggestions forofprevention
related to dozens occupationaland treatment
hazards
o Review of suggestions for prevention and treatment
57
William Farr (19th century)
• British
• Compilation of data for epidemiologic research: General Register Office: registry of births,
marriages, and
• Death with occupation, age and cause of death.
• Continuation of the work of Graunt.
• Occupations and mortality.
• Cholera deaths and altitude (“Miasma theory” = bad air)
4
EPIDEMIOLOGY
LESSON 1: EPIDEMIOLOGY AND PUBLIC HEALTH
EPIDEMIOLOGY AND PUBLIC HEALTH
DEFINITIONS 1. Epidemiology and Public Health
• Epidemiology is a method of reasoning about disease that deals with biological
inference derived from observations of disease phenomena in population groups
epidemiology
“upon" demos logos
• Often considered the core science of public health, epidemiology involves “the “people" “study"
study of distribution and determinants of disease frequency = the study of the occurrence of
illness
• Scientific research intends to fill the gaps in knowledge or improve current knowledge with a
final goal of improving society
• Epidemiologic research has a final goal of improving public health
EPIDEMIOLOGIC RESEARCH
• Main strength: assessment of disease burden or the relationship (association) between
exposure and disease in a population of interest
• Method: counting withing groups and comparing
• Main challenges
o Who to count?
o When to count?
o How to compare?
• Three types of questions:
o What is the burden of disease?
o What is the prognosis of a disease?
o Which are the risk factors/exposures causing the disease?
• What is epidemiology?
o The study of the distribution and determinants of health-related states or events
(including disease), and the application of this study to the control of disease and other
health problems
o Various methods can be used to carry out epidemiological investigations: surveillance
and descriptive studies can be used to study distribution, analytical studies are used to
study determinants
• Three types of epidemiology to answer these questions:
o Descriptive epidemiology: non-causal analyses which describe observed data (e.g.
surveillance)
Surveillance = the ongoing, systemic collection, analysis and interpretation of health-
Descriptive related data essential to planning, implementation and evaluation of public health
practice, closely integrated with the timely dissemination of these data to those
responsible for prevention and control
Analytical
1
, 2024-2025 Epidemiology CC
o Predictive (prognosis) epidemiology: use of observed data to make statements or
predictions (e.g. used in clinical epidemiology)
o Causal (etiologic) epidemiology: causal effects of risk factors/exposures on disease
emiology and! Descriptive
Public Health
epidemiology is crucial to develop analytical epidemiology
! Epidemiology results are not the only prove for causality
pidemiology?
Exposure-oriented epidemiology Outcome-oriented epidemiology
• Environmental epidemiology • Infectious disease epidemiology
• Occupational epidemiology • Cancer epidemiology
• Pharmacoepidemiology • Mental health epidemiology
• Nutritional epidemiology • Neurologic diseases epidemiology
• Genetic epidemiology • Reproductive epidemiology
• Molecular epidemiology • Respiratory disease epidemiology
• Social epidemiology • Dental epidemiology
• etc. • Clinical epidemiology
• Chronic disease epidemiology
• etc.
PUBLIC HEALTH
• The art and science of preventing disease, prolonging life and promoting health through the
organized efforts of society
• The community effort to protects, maintain and improve the health of a population by organized
means, including preventive programs, hygiene, education and other inventions
1. Epidemiology and Public Health
• What is the role of public health?
o Surveillance What is public health?
= descriptive epidemiology to establish objectives and priorities
o Health services
= planning and evaluation of health care services
o Disease prevention 1. Epidemiology and Public Health
§ Primary prevention
= intervening before health effects occur, through
What is public health?
measures such as vaccinations, altering risky behaviors
and banning substances known to be associated with a
disease or 3.health condition
Disease prevention
§ Secondary prevention Epidemiology
= screening to identify Secondary
Primary disease in the earliest stages, before
Tertiary
the onset prevention
of signs and prevention
symptoms, through
preventionmeasures such as
mammography and regular blood pressure testing Surveillance
§ Tertiary prevention
Detection of risk factors
= managing disease post diagnosis to slow or stop disease
Evaluation of interventions
progression through measures such as chemotherapy,
Evaluation of diagnostic tests
rehabilitation and screening for complications (e.g. chronic
disease management, cardiac rehabilitation, pain management clinics…)
o Health promotion
= enables people to increase control over their own health. It covers a wide range of
social and environmental interventions that are designed to benefit and protect
individual people’s health and quality of life by addressing and preventing the root cause
of ill health, not just focusing on treatment and cure (e.g. city bikes in Antwerp)
o Health protection
= minimization of the exposure to health hazards to protect the population by ensuring
environmental, occupational, toxicological and food safety
2
,2024-2025 Epidemiology CC
1. Epidemiology and Public Health
EPIDEMIOLOGY PURPOSES IN PUBLIC HEALTH PRACTICE
Public health approach
Risk Factor Intervention
Surveillance Implementation
Identification Evaluation
Adapted from CDC link
• Discover the agent, and environmental factors that affect health
• Determine the relative importance of causes of illness, disability and death
• Identify those segments of the population that have the greatest risk from specific cause of ill
1. Epidemiology and Public Health
health
• Evaluate the effectiveness of healthEpidemiology:
programs and services infield
a multidisciplinary improving population health
! Epidemiology is a multidisciplinary field
HISTORY
Hippocrates of Kos (400 BC)
• Greek physician and philosopher
• Disease demonic possession and divine displeasure
• Greek physician and philosopher
• Diseases demonic possession and divine displeasure
• To physicians: Disease occurrence can be related to environment.
• Earthly causes: “On Airs, Waters and Places”, at community of origin
• Behavior: “fond of drinking and eating to excess…”
• Change from mysticism towards observation and reason as causes of disease
Avicenna (1st-2nd century)
• Persian philosopher, scientist, and physician.
• Empirical evidence and disease causation:
• experimentation and quantification
• Infectious diseases (ID) could be spread by contagion
• Quarantine to limit the spread of ID
3
, 2024-2025 Epidemiology CC
Fracastoro (15th-16th century)
• Italian physician and poet
• Extended the theory of contagion: theory about how contagious disease spreads
• Plague, typhus and syphilis: spread through self-replicating particles (seminaria or
• seeds) [“Germ theory”]
• Seminaria:
• Very small and diseases specific
• Spread by:
• Direct person-to-person contact
• Indirect contact (fomites)
• Transmission at a distant (air or water)
• Affected by atmospheric conditions
• Poem about Syphilis
John Graunt (17th century)
•
British
•
World’s first epidemiologist and demographer
History
•
Bills of Mortality in London and later, throughout England (deaths, baptisms, causes of death,
age at death,…) [15th-19th century)
• Demography: London population dynamics (growth due to inmigration),sex ratios
• Epidemiology:
Pioneers of Epidemiology and Public Health
• Trends of diseases
• Disease misclassification
Bernadino Ramazzini (1633-1714)
• Excess deaths during epidemics
• Italian physician
Bernadino Ramazzini (17th-18th century)
• Occupational medicine
• Italian physician
• Risks related to dozens of occupational hazards
• Occupational medicine
• Review
o Risksof suggestions forofprevention
related to dozens occupationaland treatment
hazards
o Review of suggestions for prevention and treatment
57
William Farr (19th century)
• British
• Compilation of data for epidemiologic research: General Register Office: registry of births,
marriages, and
• Death with occupation, age and cause of death.
• Continuation of the work of Graunt.
• Occupations and mortality.
• Cholera deaths and altitude (“Miasma theory” = bad air)
4
