2020 Disease Detectives 071619
2020 Disease Detectives 071619
2020 Disease Detectives 071619
KAREN LANCOUR
National Bio Rules
Committee Chairman
Event Rules – 2020
DISCLAIMER
This presentation was prepared using
draft rules. There may be some changes
in the final copy of the rules. The rules
which will be in your Coaches Manual and
Student Manuals will be the official rules.
Event Rules – 2020
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What Determines the Health of a Population?
Genes and Biology
Social/Societal
Characteristics;
Total Ecology Health Behaviors
Medical Care
Centers for Disease Control and Prevention. Social determinants of health. http://www.cdc.gov/socialdeterminants/FAQ.html. 16
Public Health Core Sciences
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Types of Public Health
Issues
Alcohol-related harms
Food safety
Healthcare-associated
infections
Heart disease and stroke
HIV
Motor vehicle injury
Nutrition, physical activity
and obesity
Prescription drug overdose
Teen pregnancy
Tobacco use
EPIDEMIOLOGY
Scientific Method – organized problem solving
Distribution and determinants of disease in human
populations
Prevent and control those diseases
Health-related events:
chronic diseases
environmental problems
behavioral problems
injuries
infectious diseases
Descriptive and Analytic Epidemiology
Descriptive Analytic
epidemiology epidemiology
Experimental
Epidemiology
study
Descriptive
types
Observational
Analytic
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KEY TERMS
Formulate Conclusions
Report Results
Sample Line Listing from six case report forms on a wedding reception
outbreak
ID # Initials Date Diagnosis How Age Sex County Physician Wedding
of Onset Confirmed
1 KR 7/23 probable trichinosis Not done 29 M Columbia Goodman Yes
Identifying information
Demographic information
Clinical information
Reporter information
Types of Descriptive Studies
Types of Descriptive Studies – Study the distribution of a
problem by cases or outcome, frequency in population, exposure,
time pattern or environmental factor (Studies without a control
group can be used for descriptive purposes!)
a. Case report/case series – case report = detail report of a single
patient from one or more doctors while case series =
characteristics of several patients
b. Correlative studies – correlates general characteristics of the
population with health problem frequency with several groups
during the same period of time
Time series analysis – correlate within the same population
a different point in time
Ecologic relations – correlate relative to specific ecologic
factors as diet
c. Cross sectional - a survey of a population where participants are
selected irrespective of exposure or disease status
Step 6: Describe in terms of
Time, Place and Person Triad
x axis= units of time equal to 1/4 to 1/3 incubation time and y axis = # of cases
Note: a single point or source will have only one peak, a plateau will show a
continuous common source, several uniform peaks will indicate a propagated
outbreak spread from person to person
Step 7: Develop Hypothesis
(Agent/Host/Environment triad)
1. Agent /host /environment = agent capable of
causing disease & its source host or persons
susceptible to agent + environment allowing them
to get together
Infectious Groups: viruses, bacteria, protistans
(protozoa), fungi, animals (worms)
2. Testable – hypothesis must be in a form that is
testable
3. Current knowledge & background – it should be
based upon current knowledge and be updated or
modified as new information is uncovered!!!
Step 8: Evaluate Hypothesis
(Analytical Studies = Control Group)
1. Compare with established fact – these are
used when evidence is strong and clear cut
2. Observational Studies: (Study
determinants of health problems – how &
why)
Cohort – Based upon exposure status
whether or not they have outcome
(illness) works forward from exposure
Case-Control - Works backward from
effect or illness to suspected cause.
3. Must have lab verification to validate
hypothesis.
Cohort Study – Exposure
Both groups have a known exposure
and are checked for future outcomes or
illness.
retrospective: (historic cohort) starts
at exposure in past & moves forward to
outcome
prospective: starts a present exposure
and moves forward in time to outcome
Sample Cohort Study
using 2 X 2 table
400 people attended a special awards dinner
Some persons became ill. The suspected
culprit was the potato salad. The population
at the dinner was then surveyed to
determine who became ill.
Disease Yes Disease No
Exposed (Ate salad) 150 (a) 30 (b)
Unexposed(no salad) 50 (c) 170 (d)
Calculating Attack Rate &
Relative Risk
This means that people who ate at Restaurant A were 5.8 times
more likely to develop hepatitis A than were people who did not eat
there.
a = # of case patients exposed b = # of control exposed
c = # of case patients unexposed d = # of control unexposed
Potential Types of Error in Data
Collection - Division C
False Relationships
Random Error - the divergence due to
chance alone, of an observation on sample
from the true population value, leading to
lack of precision in measurement of
association
Bias - systematic error in an epidemiologic
study that results in an incorrect estimation
of the association between exposure and
health-related event
Potential Types of Error in
Data Collection – Div. C
Non-Causal Relationships
Confounding – occurs when the effects of
two risk factors are mixed in the
occurrence of the health-related event
under study - when an extraneous factor
is related to both disease and exposure
Step 9: As necessary,
Reconsider, Refine, and
Re-evaluate Hypotheses
o ratio – value obtained by dividing one quantity by another – a ratio often compares two rates.
Number or rate of events, items, persons, etc. in one group
Number or rate of events, items, persons, etc. in another group
o proportion – the comparison of a part to the whole as the number of cases divided by the total
population – does not have a time dimension, It can be expressed as a decimal, a fraction, or a
percentage
Number of persons or events with a particular characteristic X 10n
Total number of persons or events, of which the numerator is a subset
Disease Control
Concept of control: disease control
describes ongoing operations aimed at
reducing
The incidence of disease
The duration of disease and consequently
the risk of transmission
The effects of infection, including both the
physical and psychosocial complications
The financial burden to the community
Disease Control Process
Preventable Causes of Disease
BEINGS
Biological factors and Behavioral Factors
Environmental factors
Immunologic factors
Nutritional factors
Genetic factors
Services, Social factors, and Spiritual factors
[JF Jekel, Epidemiology, Biostatistics, and Preventive Medicine, 1996]
Natural history of disease
Onset of Usual time of
symptoms diagnosis
Exposure
Pathologic
changes
PRIMARY
PREVENTION SECONDARY
TERTIARY
PREVENTION
PREVENTION
Strategy for Prevention
Identify
Populations
Modify Existing at High
Disease Risk
Intervention (based on demography /
family history,
Programs host factors..)
Assess
Evaluate Exposure
Intervention
Programs
Conduct
Research on
Apply Mechanisms
(including the study of
Population-Based genetic susceptibility)
Intervention
Programs
PREVENTION APPROACHES
Population-Based Approach:
• Preventive measure widely applied to an
entire population (public health approach)
High-Risk Approach:
• Target group of individual at high
risk