Introduction to Epidemiology and Public Health
Epidemiology and Public health
The word epidemiology comes from Greek
- Epi = upon
- Demi/demos = people
- Ology/logos = study
Definitions
‘Epidemiology is a method of reasoning about disease that deals with biological interference
derived from observations of disease phenomena in population groups.’ ~ David E. Lilienfeld, 1978
- David E. Lilienfeld took 23 different definitions of epidemiology and made it into 1 definition.
‘Often considered the core science of public health, epidemiology involves ‘the study of the
distribution and determinants of disease frequency’, or put even more simply ‘the study of the
occurrence of illness’’. ~ K. Rothman, 2012
Scientific research
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.
Epidemiological research
- Main strength: assessment of disease burden or the relationship (association) between
exposure and disease a population of interest
- Method: counting within groups and comparing
- Main challenges?
o Who to count?
o When to count?
o How to compare?
Three types of questions
1. What is the burden of disease? -> about amount, prevalence, incidence
2. What is the prognosis of a disease? -> how is it going to evolve
3. Which are the risk factors/exposures causing a disease? -> sometimes people get sick but we
don’t know the cause
Three types of epidemiology to answer questions:
1. Descriptive epidemiology: non-casual analyses which describe observed data (e.g.
surveillance) -> what is surveillance? Systematic collection, analysis and interpretation of
data.
The ongoing, systematic collection, analysis and interpretation of health-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.
2. Predictive (prognosis) epidemiology: use of observed data to make statements or
predictions (e.g. used in clinical epidemiology) -> for example different markers we can
predict how the outcome will be.
3. Casual (etiologic) epidemiology: causal effects of risk factors/exposures on disease.
1
,What is epidemiology?
WHO
‘Epidemiology is 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 diseases and other health
problems. 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.’
However, descriptive epidemiology is crucial to develop analytic epidemiology. Epidemiology results
are not the only prove for causality.
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
What is public health?
WHO
‘The art and science of preventing disease, prolonging life and promoting
health through the organized efforts of society’.
Rothman 2012
‘The community effort to protect, maintain, and improve the health of a
population by organized means, including preventive programs, hygiene,
education, and other interventions.’
1. Surveillance -> descriptive epidemiology to establish objectives and priorities
2. Health services -> planning and evaluation of health care services
3. Disease prevention
o Primary prevention -> intervening before health effects occur, through measures
such as vaccinations, altering risky behaviors (poor eating habits, tobacco use), and
banning substances known to be associated with a disease or health condition.
o Secondary prevention -> screening to identify diseases in the earliest stages, before
the onset of signs and symptoms, through measures such as mammography and
regular blood pressure testing.
o Tertiary prevention -> managing disease post diagnosis to slow or stop disease
progression through measures such as chemotherapy, rehabilitation, and screening
for complications.
2
, 4. Health promotion -> ‘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 causes of ill health, not just focusing on treatment and cure.’
o Good governance for health
o Health literacy
o Healthy cities (Urban planning)
5. Health protection -> minimization of the exposure to health hazards on order to protect the
population by ensuring environmental, occupational, toxicological and food safety.
What is the role of public health?
- Establish health objectives and priorities
- Health promotion
- Disease prevention
- Health protection
- Health services
Epidemiology purposes in public health practice
- Discover the agent, host, and environmental factors that affect health
- Determine the relative importance of causes o illness, disability, and death
- Identify those segments of the population that have the greatest risk from specific causes of
ill health
- Evaluate the effectiveness of health programs and services in improving population health
Epidemiology: a multidisciplinary field
History
Pioneers of epidemiology and public health
Hippocrates of Kos (460-377 BC)
- Greek physician and philosopher
- Diseases demonic possession and divine displeasure -> change from mysticism towards
observation and reason as causes of disease
Avicenna (930-1037)
- Persian philosopher, scientist, and physician
- Infectious diseases could be spread by contagion
Fracastoro (1479-1553)
- 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]
3
, John Graunt (1620-1674)
- British
- Epidemiology: trends of diseases, disease misclassification, excess deaths during epidemics
Bernadino Ramazzini (1633-1714)
- Italian physician
- Occupational medicine
o Risks related to dozens of occupational hazards
o Review of suggestions for prevention and treatment
William Farr (1807-1883)
- British
- Compilation of data for epidemiologic research: General Register Office: registry of births,
marriages, and death with occupation, age and cause of death
John Snow (1813-1858)
- British
- Founding father of epidemiology (and anesthesiology)
- Investigation of an outbreak of cholera -> cholera transmission through contaminated water,
pioneer of epidemiologic study design
Ignasz Semmelweis (1818-1865)
- Hungarian physician
- Doctors were the source of disease of their patients
- Washing hands before returning to their wards decline considerably the risk of puerperal
fever
Florence Nightingale (1820-1910)
- British nurse
- Plotted monthly deaths attributable to preventable and unpreventable causes
Janet Lane-Claypon
- British
- First retrospective cohort study (1912), first (modern) case-control study (1926)
- Study design, systematic and random error
Wade Hampton Frost (1880-1938)
- First professor ef epidemiology
- Outbreak of yellow fever in the US -> was able to get rid of the outbreak
4
Epidemiology and Public health
The word epidemiology comes from Greek
- Epi = upon
- Demi/demos = people
- Ology/logos = study
Definitions
‘Epidemiology is a method of reasoning about disease that deals with biological interference
derived from observations of disease phenomena in population groups.’ ~ David E. Lilienfeld, 1978
- David E. Lilienfeld took 23 different definitions of epidemiology and made it into 1 definition.
‘Often considered the core science of public health, epidemiology involves ‘the study of the
distribution and determinants of disease frequency’, or put even more simply ‘the study of the
occurrence of illness’’. ~ K. Rothman, 2012
Scientific research
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.
Epidemiological research
- Main strength: assessment of disease burden or the relationship (association) between
exposure and disease a population of interest
- Method: counting within groups and comparing
- Main challenges?
o Who to count?
o When to count?
o How to compare?
Three types of questions
1. What is the burden of disease? -> about amount, prevalence, incidence
2. What is the prognosis of a disease? -> how is it going to evolve
3. Which are the risk factors/exposures causing a disease? -> sometimes people get sick but we
don’t know the cause
Three types of epidemiology to answer questions:
1. Descriptive epidemiology: non-casual analyses which describe observed data (e.g.
surveillance) -> what is surveillance? Systematic collection, analysis and interpretation of
data.
The ongoing, systematic collection, analysis and interpretation of health-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.
2. Predictive (prognosis) epidemiology: use of observed data to make statements or
predictions (e.g. used in clinical epidemiology) -> for example different markers we can
predict how the outcome will be.
3. Casual (etiologic) epidemiology: causal effects of risk factors/exposures on disease.
1
,What is epidemiology?
WHO
‘Epidemiology is 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 diseases and other health
problems. 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.’
However, descriptive epidemiology is crucial to develop analytic epidemiology. Epidemiology results
are not the only prove for causality.
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
What is public health?
WHO
‘The art and science of preventing disease, prolonging life and promoting
health through the organized efforts of society’.
Rothman 2012
‘The community effort to protect, maintain, and improve the health of a
population by organized means, including preventive programs, hygiene,
education, and other interventions.’
1. Surveillance -> descriptive epidemiology to establish objectives and priorities
2. Health services -> planning and evaluation of health care services
3. Disease prevention
o Primary prevention -> intervening before health effects occur, through measures
such as vaccinations, altering risky behaviors (poor eating habits, tobacco use), and
banning substances known to be associated with a disease or health condition.
o Secondary prevention -> screening to identify diseases in the earliest stages, before
the onset of signs and symptoms, through measures such as mammography and
regular blood pressure testing.
o Tertiary prevention -> managing disease post diagnosis to slow or stop disease
progression through measures such as chemotherapy, rehabilitation, and screening
for complications.
2
, 4. Health promotion -> ‘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 causes of ill health, not just focusing on treatment and cure.’
o Good governance for health
o Health literacy
o Healthy cities (Urban planning)
5. Health protection -> minimization of the exposure to health hazards on order to protect the
population by ensuring environmental, occupational, toxicological and food safety.
What is the role of public health?
- Establish health objectives and priorities
- Health promotion
- Disease prevention
- Health protection
- Health services
Epidemiology purposes in public health practice
- Discover the agent, host, and environmental factors that affect health
- Determine the relative importance of causes o illness, disability, and death
- Identify those segments of the population that have the greatest risk from specific causes of
ill health
- Evaluate the effectiveness of health programs and services in improving population health
Epidemiology: a multidisciplinary field
History
Pioneers of epidemiology and public health
Hippocrates of Kos (460-377 BC)
- Greek physician and philosopher
- Diseases demonic possession and divine displeasure -> change from mysticism towards
observation and reason as causes of disease
Avicenna (930-1037)
- Persian philosopher, scientist, and physician
- Infectious diseases could be spread by contagion
Fracastoro (1479-1553)
- 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]
3
, John Graunt (1620-1674)
- British
- Epidemiology: trends of diseases, disease misclassification, excess deaths during epidemics
Bernadino Ramazzini (1633-1714)
- Italian physician
- Occupational medicine
o Risks related to dozens of occupational hazards
o Review of suggestions for prevention and treatment
William Farr (1807-1883)
- British
- Compilation of data for epidemiologic research: General Register Office: registry of births,
marriages, and death with occupation, age and cause of death
John Snow (1813-1858)
- British
- Founding father of epidemiology (and anesthesiology)
- Investigation of an outbreak of cholera -> cholera transmission through contaminated water,
pioneer of epidemiologic study design
Ignasz Semmelweis (1818-1865)
- Hungarian physician
- Doctors were the source of disease of their patients
- Washing hands before returning to their wards decline considerably the risk of puerperal
fever
Florence Nightingale (1820-1910)
- British nurse
- Plotted monthly deaths attributable to preventable and unpreventable causes
Janet Lane-Claypon
- British
- First retrospective cohort study (1912), first (modern) case-control study (1926)
- Study design, systematic and random error
Wade Hampton Frost (1880-1938)
- First professor ef epidemiology
- Outbreak of yellow fever in the US -> was able to get rid of the outbreak
4
