Introduction to Public Health & Epdemiology Surveillance Cou[1]
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Transcript of Introduction to Public Health & Epdemiology Surveillance Cou[1]
8/18/2019 Introduction to Public Health & Epdemiology Surveillance Cou[1]
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Pakistan Field Epidemiology and
Laboratory Training Program
Introduction to Epidemiology
King Cholera dispenses contagion:
the London Cholera Epidemic of 1866
George John Pinwell
Short Training Course on Avian Influenza Surveillance
6-8 February, Islamabad, Pakistan
8/18/2019 Introduction to Public Health & Epdemiology Surveillance Cou[1]
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Learning Objectives
♦ Define Epidemiology
♦ Summarize the epidemiologicapproach
♦ List the uses of Epidemiology♦ Describe the interactions between
host, agent, and environment
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Epidemiological Principles
♦ Diseases (or other health events)
don’t occur at random
♦ Diseases (or other health events)have causal and preventive factorswhich can be identified
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Epidemiology
Epi = upon
Demos = population
Logos = study of
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Definition
The study of the distribution anddeterminants of health related states orevents in specified human populations and
its application to the control of healthproblems
Last, 1988
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Key Words:
The study of the distribution anddeterminants of health related states orevents in specified human populations and
its application to the control of healthproblems.
Distribution Time, place, person
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Key Words:
The study of the distribution anddeterminants of health related states orevents in specified human populations and
its application to the control of healthproblems.
Determinants Cause, risk factors
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Key Words:
The study of the distribution anddeterminants of health related states orevents in specified human populations and
its application to the control of healthproblems.
Population Public health
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Key Words:
The study of the distribution anddeterminants of health related states orevents in specified human populations and
its application to the control of healthproblems.
Application Information for
action
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Uses of Epidemiology
♦ Determine the magnitude and trends
♦ Identify the etiology or cause of disease
♦ Determine the mode of transmission♦ Identify risk factors or susceptibility
♦ Determine the role of the environment
♦ Evaluate the impact of the controlmeasures
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Epidemiologist Core Functions
♦ Public health surveillance
♦ Investigation
♦ Data analysis
♦ Evaluation
♦ Communication
♦ Management and teamwork
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Public Health Cycle
Evaluate population
health and program
output, repeat cycle Target/Evaluate
Analyze
Intervene
Communicate
Descriptive
epidemiology, surveys,
surveillance, Quality
assurance
Analytic epidemiology
defines risk factors
Communications to
decision makers, media, on
problem and risk factors.
Management, advocacy,
communications
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Basic Epidemiologic Approach
♦ Observe
♦ Count cases (events)
♦ Describe
– Time, place, person
– Calculate rates,
♦ Compare rates♦ Develop hypothesis
♦ Test hypothesis
♦ Implement actions (control, prevention)
Descriptive
Epidemiology
Analytical
Epidemiology
d d l
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Medicine Versus Epidemiology
ClinicalMedicine
Epidemiology
Focus Individuals Populations
Main Goal Diagnosis andTreatment
Prevention andControl
Questions What is wrong
with this patient?What treatment isappropriate?
What are the
leading causes ofdeath or disabilityin this population?
What can be doneto reduce/preventthem?
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Epidemiology and Disease
L l f Di
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Levels of Disease
EndemicEndemic
EpidemicEpidemic
PandemicPandemic
Increasing amount of disease
SporadicSporadic
E id i l i T i d
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Epidemiologic Triad
H t A t E i t
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Host, Agent, Environment
Host
AgeSex
Religion
Exercise
Behavior
Co-morbidity
Genetics
Food
H t A t E i t
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Host, Agent, Environment
Host Agent
AgeSex
Religion
Exercise
Behavior
Co-morbidityGenetics
Biologicmicroorganisms
Chemical toxins
Physical trauma
Nutrition
Host Agent En i onment
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Host, Agent, Environment
Host Agent Environment
AgeSex
Religion
SES
Exercise
Behavior
Co-morbidity
Genetics
BiologicMicroorganisms
Chemical Toxins
Physical Trauma
Nutrition
Disease vectorsPopulation density
Air quality
Weather
Noise
Food and watersources
Chain of Infection
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Chain of Infection
Reservoir
Mode ofTransmission
Susceptible
Host
Mode ofTransmission
Reservoir
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Reservoir
Habitat in which the disease normally
lives and multiplies • People
- Symptomatic - Smallpox
- Asymptomatic - HIV
• Animals (Zoonoses)
- Brucellosis- Plague
• Environmental
- Histoplasmosis- Legionnaires’ bacillus
Mode of Transmission
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Mode of Transmission
♦ Direct
– Contact - Cutaneous Anthrax, Hookworm – Droplet –Smallpox
♦ Indirect – Airborne – Histoplasmosis, Inhalation Anthrax
– Vehicle-borne food or water - Salmonella
– Vectorborne
• Mechanical – Shigella by fly limbs
• Biological – Malaria (maturation)
Chain of Infection
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Chain of Infection
Reservoir
Mode ofTransmission
SusceptibleHost
Mode ofTransmission
Do you need to identify the agent to control it?
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Do you need to identify the agent to control it?
Disease Controlmeasure
Year Agent Year
Scurvy Diet 1753 Vitamin C 1928
Pellagra Diet 1754 Niacin 1924
Smallpox Vaccination 1798 Orthopoxvirus
1958
Cholera Water
quality
1849 Vibrio
cholerae
1893
Yellowfever
Mosquitocontrol
1901 Flavivirus 1928
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The art of epidemiological thinking
is to draw conclusions
from imperfect data
George W. Comstock
Acknowledgements
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Acknowledgements
♦ Presentations
– M. Valenciano and D. Coulombier, WHO Lyon
– C. Whalen, Case Western Reserve
– E. Simoes, CDC
♦ Reference books
– M. Gregg, Field Epidemiology, 2 nd ed.
– R. Timmreck, An Introduction to Epidemiology