Epidemiology triad.pdf

Diploma Medical and Health Science

1. Institut
Latihan
Kementerian
Kesihatan
Malaysia (ILKKM)
Prog
:
Diploma in Medical And Health Science (DPMH)
Year 1
Sem
I
MHBE 2013
BASIC EPIDEMIOLOGY ;
Epidemiology Triad
(2 Hour)

2. Learningoutcome (LO) ;
1.Describe epidemiology triad.
2.Interpret the relationship between host ,
agent and environment.
3.Discuss concept of intervention related
to host , agent and environment.
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3. 1.Definitionof term.
2.Model of triad.
3.Model of Relationship
between triad and prevention.
4.Model of intervention in triad.
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Content outline :

4. History epidemiology;
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John Snow(15 March 1813 –16
June 1858) was an English
physician and a leader in the
development
ofanaesthesiaand
medicalhygiene. He is
considered one of the founders
of modernepidemiology, in
part because of his work in
tracing the source of acholera
outbreak in Soho, London, in
1854.
Cholera Minimata
is aneurologicaldisease
caused by
severemercury
poisoning. Signs and
symptoms
includeataxia,numbne
ssin the hands and
feet, generalmuscle
weakness,loss of
peripheral vision, and
damage
tohearingandspeech.
Minamata disease
was first discovered
inMinamatacity
inKumamoto
prefecture,Japan,
in 1956

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It was caused by the release
ofmethylmercuryin the
industrialwastewaterfrom theChisso
Corporation’s chemical factory, which
continued from 1932 to 1968.
thighlytoxicchemicalbioaccumulatedandbio
magnifiedin shellfish and fish inMinamata
Bayand theShiranui Sea, which, when
eaten by the local population, resulted in
mercury poisoning. While cat, dog, pig, and
human deaths continued for 36 years.
Cont’…History epidemiology;

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Simplest of these is the epidemiologic triad or triangle, the
traditional model for infectious disease.
The triad consists of an externalAGENT, a susceptibleHOST, and
anENVIRONMENT that brings the host and agent together.
In this model, disease results from theinteraction between the agent and
the susceptible host in an environment that supports transmission of the
agent from a source to that host
Source ; https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section8.html
Definition of term;

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Model of epid.triad;
Triad

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Cont’..Model of epid.triad;
1.AGENT;
Originally referred to an infectious 1.microorganism
or pathogen: a virus, bacterium, parasite, or other
microbe, 2.physical(eg; electrical, radiation, noises etc) ,
3. chemical (eg; L-tryptophan contaminant responsible for
eosinophilia-myalgiasyndrome).
Generally, the agent must be present for disease to occur
(pahtogenicity) ; however, presence of that agent alone is not always
sufficient to cause disease.

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Cont’..Model of epid.triad;
2. HOST;
Hostrefers to the HUMAN who can get the
disease, also called intrinsic factor.
Opportunities for exposure are often influenced FACTORS by ;
1.behaviorssuch as sexual practices
2.hygiene
3.age and sex
Susceptibility and response to an agent are influenced by factors such as genetic
composition, nutritional and immunologic status, anatomic structure, presence of
disease or medications, and psychological makeup.

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Cont’..Model of epid.triad;
3. ENIVIROMENT;
Environmentrefers to extrinsic factorsthat
affect the agent and the opportunity for
exposure.
Environmental factors include ;
1.Physical factorssuch as geology and
climate
2.Biologicfactors such as insects that
transmit the agent
3.Socioeconomicfactors such as
crowding, sanitation
4.Availability of health services.

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Discuss;
where? who? why? what? how?

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Model of RELATIONSHIP ;
Stability Vs Instability

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Model of RELATIONSHIP ;
1.AGENTbecome infectious.
- Agent become strongest.
- Host poor immunity and sick.
- Without environment
influences.
Outcome= Disease Spread

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Model of
RELATIONSHIP ;
2. AGENTbecome infectious.
- Agent become strong.
- Host poor immunity and sick.
- Within environment
influences.
Outcome= Disease Spread

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Model of
RELATIONSHIP ;
3. AGENTbecome infectious.
- Agent not strong.
- Host highly susceptible.
- Without environment
influences.
Outcome= Disease Spread

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Model of
RELATIONSHIP ;
4. AGENTbecome infectious.
- Agent not strong.
- Host high susceptible.
- Within environment/
enforcement poor
influences.
Outcome= Disease Spread

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Model of
RELATIONSHIP ;
5. Stability triad.
- Agent/vectors controlled.
- Host good life style, and immunize.
- Within environment/
enforcement .
Outcome= Disease
Controlled

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Model of intervention;

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Strategies related to ENVIRONMENT include attention to
general environmental factor such as;
i.Standards of housing
ii.Nutrition
iii.Working condition
iv.Water supplies
v.Sewage disposal
vi.Control of environmental pollution
vii.Enforcement
Example ;
Prevention of transmission of food-borne infection are by hygienic
food production.
Model of
intervention;

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Strategies related to HUMAN(HOST) ;
1.include enhancement of general or specific resistance to
disease, i.eby improved nutrient or immunization.
2.Modification of personnel behaviour i.eby encouraging
people to adapt healthier lifestyles by not smoking,
avoiding obesity and exercising regularly ,etc.
3.Use of screening to detect predisposing conditions or the
early stage of disease, when action can be taken to
prevent its onset or control its progress, i.eblood
pressure to prevent hypertension or mammography for
breast cancer detection.
Model of
intervention;

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Discuss ;
Source ; https://www.thestar.com.my/lifestyle/living/2019/06/27/control-aedes-reduce-dengue

22. Student reading/ priority references :
Book / Journal / Article
NoReferences
1.GordisLeon (2013) Epidemiology, 5th edition,Elsevier
Suander,USA.
2.William C. Cockerham(2016) Medical sociology 13th edition,
Routledge,USA
3.Schneider.M.J(2014),Introduction to public health (4th
Edition),Jones & Bartlett Learning,USA
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Internet/ e book/ online
NoReferences
1.http://www.moh.gov.my/
2.https://www.who.int/
3.https://books.google.com.my/books?id=AXZz6JIV9ikC&pri
ntsec=frontcover#v=onepage&q&f=false
4.https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section9.
html

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24. Recommendationfor student Independent Learning (IL) ;
Activities Source
1.Search anddownload https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section8.h
tml
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC260
0290/
2.Reading relatedtopic As above and,
https://www.thestar.com.my/lifestyle/living/2019/06/27/contr
ol-aedes-reduce-dengue
3.Make short note relatedtopicAs above and,
https://www.thestar.com.my/lifestyle/living/2019/06/27/contr
ol-aedes-reduce-dengue
4.Discus and answer
Exercise 1.8
https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section8.h
tml9/10/2020
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