disease detectives ii host agent environment

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


2. Learn moreabout agents ofdisease so thatnew, effectivetreatments andpreventions canbe found.


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The GOALS


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.

disease detectives ii host agent environment

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