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Document Sample
Introduction to
Epidemiological Methods
Bioterrorism Epidemiology
Module 4
Missouri Department of Health
And Senior Services
Learning Objectives
• Define bioterrorism epidemiology
• Describe epidemiological approach to
understanding disease etiology
• Recognize difference between incidence
and prevalence
• Distinguish between the stages of the
disease process
Biological and Chemical
Epidemiology
The study of the distribution and
determinants of diseases resulting from a
biological or chemical attack
Sources of Epidemiologic Clues to
a Disease Outbreak
• Clinician’s office or medical clinic
• Emergency room
• Laboratory
• Veterinary Clinic
• Pharmacy
Epidemiologic Approach to
Understanding Disease Etiology
• Descriptive epidemiology - identifying
associations of disease in relation to
• Time
• Place
• Persons
Epidemiologic Approach to
Understanding Disease Etiology
• Analytic epidemiology
• Identify associations of disease with
possible etiologic factors (chemical
release, biological agent)
• Further refine and test hypotheses regarding
etiology
Problems Investigating the Causes
of Disease
• Specific agent might not be known
• Location of agent release might not be known
• Signs and symptoms might not differentiate
disease
• More than one agent might be used
• Time of agent release might not be known
• Latency period might not be known
• Latency is not the same for all people
Epidemiologic Triad of Disease
Host
Agent Environment
Epidemiologic Triad of Disease
Host
Agent Environment
Epidemiologic Triad of Disease
Host
Agent Environment
Epidemiologic Triad of Disease
Host
Agent Environment
Modes of Transmission
• Direct Host
• Contact
• Droplets
• Indirect
• Airborne
• Vehicle-borne Agent Environment
• Vector-borne
• Mechanical
• Biologic
Modes of Transmission
• Direct Host
• Contact
• Droplets
• Indirect
• Airborne Agent Environment
• Vehicle-borne
• Vector-borne
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Temperature
Sex Chemical (nerve, blister) Humidity
Race Nuclear Altitude
Religion Bombs and flammables Wind
Customs Crowding
Occupation
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Temperature
Sex Chemical (nerve, blister) Humidity
Race Nuclear Altitude
Religion Bombs and flammables Wind
Customs Crowding
Occupation
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Factors That May Be
Associated With Disease
Host Characteristics Types of Agents and Examples Environmental Factors
Age Biologic (bacteria, viruses, toxin) Location of Release
Sex Chemical (nerve, blister) Temperature
Race Nuclear Humidity
Religion Bombs and flammables Altitude
Customs Wind
Occupation Crowding
Genetic profile
Marital status
Immune status
Vaccination status
Numerators and
Denominators
What Is a Numerator
• Count of cases
What Is a Numerator
• Count of cases
• Frequently organized in a line-listing
Line Listing
a
Case Summaries
Di sease Attendance at
Status Soccer Game Resi dence
1 Di d Not
Attended
Di seased Li ve wi th 1
Game
m il e
2 Di d Not
Not Attend
Di seased Li ve wi th 1
Game
m il e
3 Li ved
Attended
Di seased wi thi n 1
Game
m il e
4 Di d Not
Not Attend
Di seased Li ve wi th 1
Game
m il e
5 Li ved
Not Attended
wi thi n 1
Di seased Game
m il e
6 Di d Not
Not Not Attend
Li ve wi th 1
Di seased Game
m il e
7 Di d Not
Not Attended
Li ve wi th 1
Di seased Game
m il e
8 Li ved
Not Not Attend
wi thi n 1
Di seased Game
m il e
9 Di d Not
Not Attended
Li ve wi th 1
Di seased Game
m il e
T otal N 9 9 9
a. Li mi ted to fi rst 100 cases.
What Is a Numerator
• Count of cases
• Frequently organized in a line-listing
• Allows for regrouping and counting cases
by their various characteristics
What Is a Numerator
• Count of cases
• Frequently organized in a line-listing
• Allows for regrouping and counting cases
by their various characteristics
• Might be incident or prevalence cases
Incidence and Prevalence
Incidence =
Incidence and Prevalence
Number of new cases of a disease
Incidence =
over a period of time
Incidence and Prevalence
Prevalence =
Incidence and Prevalence
Total number of cases of a
Prevalence = disease
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
Recovery
Death
Incidence
Prevalence
Pot
Relationship Between
Incidence and Prevalence
• Under the assumption of a steady-state
Prevalence = I * D Recovery
Death
I = incidence Incidence
Prevalence
D = duration Pot
Relationship Between
Incidence and Prevalence
• Under the assumption of a steady-state
Prevalence = I * D Recovery
Death
I = incidence Incidence
Prevalence
D = duration Pot
Relationship Between
Incidence and Prevalence
• Under the assumption of a steady-state
Prevalence = I * D Recovery
Death
I = incidence Incidence
Prevalence
D = duration Pot
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
Episodes of Tularemia
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
What is the prevalence of tularemia
on July 1998 in these 20 people?
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
What is the prevalence of tularemia
on July 1998 in these 20 people?
Number of Persons
20 M
L
K
J I
15
H
G
F
10
D E
5
C
B
0
A
Nov. 96 Jan. 97 Jul-98 Dec. 99
TIME
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
The Natural History of Disease
Outcome
Healthy Cure
Control
Disease Symptoms Seek Diagnosis Disability
Treatment
Onset Care Death
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