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8/4/2019 Disease Detectives II Host Agent Environment
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Disease Detectives IIHost, Agent and Environment
Science Olympiad Team
Carmel High School
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For the Science Olympiad
Disease Detectives event, team
members can only have a non-
programmable calculator. NO
reference materials are allowed.
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For the disease detective
the laboratory is
the world!
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Two frameworks
for our detective work
Person Host
Place Agent
Time Environment
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Today weToday we
brainstormbrainstorm
Host
Agent
Environment
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Host variables to look at
Who?
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HOST
The host is the individual who gets the
disease of interest.
The disease detective is usually interested
in studying POPULATIONS of hosts that
things in common.
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A population is a group of
individuals with something incommon.
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Some host characteristics
Age! Considered the most important
single determinant of health status.
Sex/ gender
Race
Ethnicity
Religion
Workplaces Affiliations:schools, clubs
Lifestyle:physical activity, sexual
practices, smoking, alcohol and drug use
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If the host is an animal or plant
Genus and species Subspecies orvariety
Age Sex Diet/nutrient
requirements
Adaptations:
Defenses againstdisease and
predators Reproductivefunctions andmating strategy
Means of acquiringand digesting food(acquiring matterand energy).
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Agent characteristics: Lets look at
What?
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The agentis the
CAUSE
of the disease orproblem.
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We will spend some time later
looking at agents of disease.
What is the causative agent ofAIDS?
What is the agent ofsalmonella infection?
What is the agent ofcoronary artery disease?
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What is the causative agent ofAIDS?
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What is the agent that
causes salmonellagastroenteritis?
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What is the agentofcoronary arterydisease?
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What is the agent ofcoronary artery disease?
Oops! The one-agent, one-disease modelbreaks
down.
There are many agents that contribute to the
development of coronary artery disease.
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What are some of the factors that interact in
complex ways to lead to development ofcoronary artery disease?
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Environmental variables to look at
Whereand
how?
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Environments that contribute to disease
CONDITIONS:
Hazardous workplaces:
noise, dangerous
chemicals
Vectors of disease
Basements with high
radon gas levels
Dirty water supplies Inadequate food supplies
Extreme heat or cold
BEHAVIORS:
Failure to store and cook
food properly
Failure to practiceabstinence or use condoms
DUI
Social environments that
favor violence. Smoking, including places
that have passive smoking
i t f
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Mosquitoes arevectorsofdisease.
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Mosquito control programs help
modify the environment so thatthe vectors are eliminated.
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What techniques can we use to kill
mosquitoes at each stage of its life cycle?
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The GOALS
of disease detectives are to:
1. Determine the cause of diseaseoutbreaks so that the progress of thedisease in the community can be
stopped.
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The GOALS
of disease detectives are to:
2. Learn moreabout agents ofdisease so thatnew, effectivetreatments andpreventions canbe found.
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The GOALS
of disease detectives are to:
3.Contribute to the body ofscientificknowledge about disease.
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Some new termsSome new terms
EnEndemicdemic
EpiEpidemicdemicOutbreakOutbreak
PanPandemicdemic
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Endemic
An adjective that refers to the normal,
expected background rate of disease in a
population.
In determining if the rate of disease is what
we expect, we must consider factors like
location, age group, season of year, etc.
The endemic rate of flu is lower in the
summer than in the winter.
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Epidemic
As a noun, refers to an increase in the
rate of disease. The rate of disease is
much higher than expected in a given
location at a given time of year.
There was a flu epidemic in Western
Europe in 1974.
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Outbreak An outbreak of disease is a mini-
epidemic. An outbreak is usually
localized to an institution (hospital,
school, etc.).
There was an outbreak of food
poisoning in the Polly Panda Day Care
Center last week. It was caused by
contaminated potato salad.
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Pandemic
A worldwide epidemic.
To say global pandemic isredundant.
The AIDS pandemic shows nosigns of abating, especially in
Africa.
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Disease Agent of the Week
Viral Hepatitis
Hepatitis A
Hepatitis B
Hepatitis C
He atitis D
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The liver is the bodys chemicalfactory. It produces hundreds of
products and catalyzes manybiochemical reactions. It is a vitalorgan. Infection of the liver can
cause serious disease, even death!
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What doeshepatitismean?
Hepatitis means inflammation of the liver.
There are many causes of hepatitis, including:
Ingestion oftoxic substances
Chronic alcohol abuse
Viruses: hepatitisA, B, C, D
Certain bacteria
Autoimmune disorders: immune system attacks
its own tissues!
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itis means inflammation of
Encephalitis
Nephritis
Hepatitis
Dermatitis Rhinitis
Otitis
Gastritis
Enteritis
Gastroenteritis
Myocarditis
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What is a virus?
A virus is a self-replicating system of
nucleic acid (DNA or RNA) enclosed in a
protein coat.
Viruses affect bacteria (bacteriophages),
plants, and animals.
Not all viruses cause disease.
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An electron micrograph of the
hepatitis B virus.
This virus is a double-stranded DNA virus.
It is transmitted only among humans.
Primates can be experimentally infected,
but do not acquire the disease in nature.
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Means of transmission
Hepatitis A fecal-oral -- inunsanitary conditions. Peopleacquire the virus by ingestion with
food or water.
Hepatitis B, C, and D blood-borne pathogen acquired frominfected blood or body fluids.
Wh t f th
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What are some of the
human body fluids?
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Based on what you know
Which category of viral hepatitis is most
likely to be transmitted in community-wide
epidemics?
Which category of viral hepatitis is most
likely to occursporadically among
individuals in the community?
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Think about it.
Infectious diseases are
transmitted by BEHAVIORS.
What are some behaviors thatfavor transmission of blood and
body fluids?
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What can diseaseinvestigators do to stop
the spread of a hepatitisA outbreak?
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Prevention of additional cases
ofhepatitis A
Education: handwashing, using only safe,
pasteurized food.
Lifestyle: discontinue fertilization of fields
with human feces. Installation of indoor
plumbing in developing countries.
Immunization of healthy people with the
new hepatitis A vaccine.
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What can diseaseinvestigators do to stop
the spread of a hepatitisB in the community?
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Prevention of hepatitis B, C, and D
and otherbloodborne pathogens.
Education: about means of spread of thediseases. Healthcare workers must sterilizeequipment between patients.
Lifestyle: Teaching injectible drug users not toshare needles. Discouraging cultural practicesthat favor transmission of blood and body fluids.
Immunization of healthy persons againsthepatitis B. A vaccine against hepatitis C isexpected soon.
The blood supply of most
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The blood supply of most
nations is tested for
bloodborne pathogens like
Hepatitis B
Hepatitis C
Elevated liver enzymes in the blood
that might indicate hepatitis. Malaria(transmitted by mosquitoes)
HIV (human immunodeficiency virus)
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Carmel Science Olympiad Team
Thank you for your hardwork and thought today.